다제내성 슈퍼박테리아에 대한 새로운 항생제인 항균 펩타이드

antimicrobial peptide; multi-drug resistance; biofilm; MRSA; lipopolysaccharide

According to the requirement of novel antimicrobial agents for the rapidly increasing emergence of multi-drug resistant pathogenic microbes, a number of researchers have found new antibiotics to overcome this resistance. Among them, antimicrobial peptides (AMPs) are host defense molecules found in a wide variety of invertebrate, plant, and animal species, and are promising to new antimicrobial candidates in pharmatherapeutic fields. Therefore, this review introduces the antimicrobial action of antimicrobial peptide and ongoing development as a pharmetherapeutic agent.

미생물연료전지를 이용한 유가공 폐수로부터 전기생산

dairy wastewater; microbial fuel cell; electricity; power density

Microbial fuel cell (MFC) is the major of bio-electrochemical system which can convert biomass spontaneously into electricity through the metabolic activity of the microorganisms. In this study, we used an activated sludge as a microbial inoculum and then investigated the feasibility of using dairy wastewater as a possible substrate for generating electricity in MFC. To examine the performance of MFC as power generator, the characteristics on cell potentials, power density, cyclic voltammetric analysis and sustainable power estimation were evaluated for dairy wastewater. The maximum power density of 40 mW/m2 was achieved when the dairy wastewater containing 2650 mg/L COD was used, leading to the removal of 88% of the COD. The results from this study demonstrate the feasibility of using MFC technology to generate electricity while simultaneously treating dairy wastewater effectively.

Removal of F-, NO3-, and PO43- ions from aqueous solution by aminoclays

Aminoclays; Wastewater treatment; Fluoride; Nitrate; Phosphate

Fluoride (F), nitrate (NO3-), and phosphate (PO4n-) anions are produced in large quantities by the use of cleaning agents in the electronics industry. Because of their high solubility in water and harmful impact on the environment, the development of an efficient treatment process for anionic species has been gaining increased attention. In this study, aminoclays with centered cationic metal ions, including Mg2+, Al3+, and Fe3+, were synthesized by a one-pot sol-gel reaction, and removal of F-, NO3-, and PO43- by the synthesized aminoclays was evaluated in an anion mixture system. The aminoclays resulted in exfoliated dispersions with high-density amino groups in aqueous solution. Among the anions studied, phosphate was preferentially removed by the aminoclays, which suggests that anion removal by aminoclays was mainly achieved by the electrostatic interactions between anions and aminoclays. Compared with aminopropyl-functionalized silica gel (average diameter: 40-63 μm), aminoclays showed higher anion removal efficiencies.

Characteristics of the product from steam activation of sewage sludge

Steam activation; Gasification; Sewage sludge; Producer gas; Tar; Sludge char

Steam activation of a dried sewage sludge was studied to produce hydrogen rich gas and sludge char for converting to energy and resources. A batch-type wire mesh reactor was used to study the characteristics of the steam activation. The characteristics of activation product (i.e., producer gas, gravimetric tar, light tar, and sludge char) were identified. With the increase in the steam feed rate, the sludge char decreased but the producer gas increased, having higher gas heating value. And tar generation slightly increased when a small amount of steam was fed, but when the steam feed rate significantly increased, tar decreased because part of the tar was converted into light gas. Hydrogen and carbon monoxide increased with the increase in the steam feed rate. And carbon dioxide, methane, ethylene, and ethane reached their maximum according to different production mechanisms up to decreasing the species. The gradually increase in the steam feed rate resulted in the creation of micropores, which developed to the maximum when the steam flow rate was 14 mL/g min. When excessive steam was supplied, however, micropores sank due to the resulting sintering phenomenon, and the adsorption capacity deteriorated. The sludge char had a mean pore size of 6.229 nm, which is the size of mesopores from which condensible tar (the cause of damage on the device) is properly adsorbed and removed.

Simulated economics assessment of hollow fiber CO2 separation modules

Economic Analysis; Modeling of Separation Process; Carbon Dioxide; Hollow Fiber Membrane

Various conditions under which the hollow fiber membrane separation system would be the optimal selection are investigated in terms of cost effectiveness. Numerical simulation is carried out to examine the effects of different configurations such as single-stage, two-stage and three-stage CO2 separation processes. In particular, the hollow fiber membrane processes for CO2 separation with vacuum pumps, heat exchangers, coolers and compressors to provide pressurized feed streams are analyzed. Operating costs are evaluated and compared numerically for the processes with and without recycle streams to compare feasibility for commercial implementation while maintaining the purity and recovery ratio as high as possible.

PEG 스페이서를 통해 Homing 펩타이드를 고정화한 산화철 나노입자의 제조 및 생의학적 응용

magnetite; homing peptide; IL-4 receptor; intracellular uptake; cancer cell.

Iron oxides (Fe3O4) are metabolically secreted after endocytosed by cells, indicating no cytotoxicity. Therefore, they are widely used as a contrast agent before photographing of magnetic resonance imaging. In this study, iron oxide nanoparticles are synthesized by the co-precipitation method and subsequently immobilized with a homing peptide (AP), which specifically interacts with interleukin-4 receptor located on the membrane of endothelial and bladder cancer cells. The size of AP-immobilized iron oxide particle is about 39 nm. Intracellular uptake of the AP-immobilized iron oxide nanoparticles was investigated using bladder cancer cells and fibroblasts as the control. As the result, the nanoparticles are specificially uptaken by bladder cancer cells. However, the nanoparticles are not specificially uptaken by fibroblast. It could be said that the AP-immobilized iron oxide nanoparticles have a potential to be used as a contrast agent for early diagnosis of cancer.

방사선을 이용한 실란 가교구조의 유/무기 복합 수소이온 교환막 제조 및 연료전지 성능 평가

radiation; grafting; poly(ethylene-co-tetrafluoroethylene); silane-crosslinking.

In this study, silane-crosslinked organic/inorganic composite membranes were prepared by simultaneous irradiation grafting of binary monomer mixtures (styrene and 3-(trimethoxysilyl)propyl methacrylate (TMSPM)) with various compositions onto a poly(ethylene-alt-tetraethylene) (ETFE) film and followed by sol-gel processing and sulfonation to provide a silane-crosslinked structure and a proton conducting ability, respectively. The Fourier transform infrared spectroscopy (FTIR) and thermo gravimetric analysis (TGA) were utilized to confirm the crosslinking of ETFE-g-PS/PTMSPM films. The prepared membranes with similar ion exchange capacity but a different TMSPM content were selected and their membrane properties were compared. The ETFE-g-PSSA/PTMSPM membranes were characterized by water uptake, dimensional stability, and proton conductivity after sulfonation. The membrane electrode assemblies (MEA) of the prepared membranes were fabricated and their single cell performances were measured.

워터젯 글라이딩 아크 플라즈마에 의한 사불화탄소 제거에 미치는 운전변수의 영향

non-CO2 gas; CF4; waterjet scrubber; gliding arc plasma; greenhouse gas

Tetrafluoromethane (CF4) has been used as the plasma etching and chemical vapor deposition (CVD) gas for semiconductor manufacturing processes. However, the gas need to be removed efficiently because of their strong absorption of infrared radiation and the long atmospheric lifetime which cause global warming effects. A waterjet gliding arc plasma system in which plasma is combined with the waterjet was developed to effectively produce OH radicals, resulting in efficient destruction of CF4 gas. Design factors such as electrode shape, electrode angle, gas nozzle diameter, electrode gap, and electrode length were investigated. The highest CF4 destruction of 93.4% was achieved at Arc 1 electrode shape, 20° electrode angle, 3 mm gas nozzle diameter, 3 mm electrode gap and 120 mm electrode length.

워터젯 글라이딩 아크 플라즈마를 이용한 사불화탄소 저감

Tetrafluoromethane; Waterjet; Gliding arc Plasma; Energy Efficiency; OH Radical

Tetrafluoromethane(CF4) has been used as etching and chamber cleaning gases for semiconductor manufacturing processes. These gases need to be removed efficiently because of their strong absorption of infrared radiation and long atmospheric lifetime which causes the global warming effect. We have developed a waterjet gliding arc plasma system in which plasma is combined with waterjet and investigated optimum operating conditions for efficient CF4 destruction through enlarging discharge region and producing large amount of OH radicals. The operating conditions are waterjet flow rate, initial CF4 concentration, total gas flow rate, specific energy input. Through the parametric studies, the highest CF4 destruction of 97% was achieved at 2.2% CF4, 7.2 kJ/L SEI, 9 L/min total gas flow rate and 25.5 mL/ min waterjet flow rate.

Modeling and simulation of hollow fiber CO2 separation modules

Multi-stage Module; Multilayer Perceptrons Back-propagation Networks; Modeling of Separation Process; Carbon Dioxide; Hollow Fiber Membrane

We developed two models for the CO2 separation process by hollow-fiber membrane modules. The explicit model, which is based on mass balances for the separation modules, is compared with the multilayer perceptrons (MLP) back-propagation neural networks model. Experimental data obtained from single-stage module with recycle are used to validate the explicit model as well as to train the MLP neural model. The effectiveness of the model is demonstrated by little discrepancy between experimental data and computational results. The explicit model for the single-stage module can easily be extended to the multi(three)-stage module. Because of the lack of experimental data for multi-stage modules, computational data from the explicit model with and without recycle are used as training data set for the MLP neural model. We examined the effects of recycle on the recovery based on the results of numerical simulations, and could see that the predicting performance is improved by recycle for multi-stage module. From the results of numerical simulations, the proposed models can be effectively used in the analysis and operation of gas separation processes by hollowfiber membrane modules.

Functional properties of hot water extract of a fish, seaweed, and mushroom mixture

Antioxidant Activity; Anticancer Activity; Hot Water Extract; Functional Food

The purpose of this study was to evaluate the effect of hot water extracts of a fish, seaweed, and mushroom mixture (FSM extract) on the antioxidant and anticancer activities for use as health and functional food resources. DPPH radical scavenging activity increased from 13.4 to 93.5% when the FSM extract concentration ranged from 0.5 to 25 mg/mL. The reducing power increased from 0.04 to 1.06 OD 700 nm when the FSM extract concentration increased from 0.25 to 10 mg/mL. Nitrite scavenging activity increased from 10.3 to 96.9% when the FSM extract concentration increased from 1 to 25 mg/mL. The activities of alcohol dehydrogenase and acetaldehyde dehydrogenase in the FSM extractfed group were 2.45 and 6.12 units/min, respectively. The activities of CAT, SOD, and GSH-Px in the FSM extractfed group were 19.7 units/mg protein, 11.5 units/mg protein, and 16.9 units/mg protein/min, respectively. Cell viabilities of SNU213, SNU324, and SNU354 were 7.5, 9.4, and 8.9%, respectively. Cell viabilities of SNU719, SNU1, and SNU5 ranged from 14.6 to 16.8%. However, for SNU216, SNU484, SNU601, SNU638, SNU668, SNU16, and SNU520, they were below10%. These results demonstrate that the FSM extract can be used in the functional food, pharmaceutical, and cosmetic industries.

Naphthalene destruction performance from tar model compound using a gliding arc plasma reformer

Tar Model Compound; Gliding Arc Plasma; Reformer; Thermal Destruction; Pyrolysis/Gasification

Recycling of various wastes such as sewage sludge requires an energy conversion process like thermal pyrolysis/gasification. During the process, tar and syngas are produced, but the tar brings trouble in pipelines and creates operating problems for the facility. In this study, to investigate naphthalene destruction in a gliding arc plasma reformer, parametric experiments were achieved in the variables that can affect the destruction efficiency. And through the parametric studies, the optimal operating conditions and the results were taken. For the parametric studies, steam input amount (steam/carbon ratio), input discharged power SEI (specific energy input), total feed gas amount, input naphthalene concentration, and electrode length were selected for experiments. Optimal conditions were 2.5 of S/C ratio, 1 kWh/m3 of SEI, 18.4 L/min of total gas amount, 1% of input naphthalene concentration, and 95 mm of electrode length. The corresponding maximum destruction efficiency of naphthalene was 79%, and energy efficiency showed 47 g/kWh.

Modeling and control of CO2 separation process with hollow fiber membrane modules

Multi-stage Model; Model Predictive Control; Modeling of Separation Process; Carbon Dioxide; Hollow Fiber Membrane

A multi-stage model is developed for CO2 separation by hollow-fiber membrane. The model permits rapid solution of the governing differential mass and pressure distribution in hollow-fiber gas separation modules using a computational scheme that does not rely on commercial software and conventional numerical methods such as shooting techniques. For 1-stage, 2-stage and 3-stage configurations the changes of required separation areas according to stage cuts are computed. A simple model predictive control technique is employed to provide optimal operation conditions based on the proposed model. Values of stage cuts can easily be identified for various desired mole fractions and recovery rates. From the results of numerical simulations, we can see that the proposed model can be effectively used in the control of gas separation process by hollow-fiber membrane modules.

저분자량 수용성 키토산의 항균 활성에 관한 연구

chitosan; antibacterial activity; pathogenic bacteria; lipid; water-soluble; negatively-charged membranes.

Chitosan is a natural polymer derived from chitin that has been widely used as a dietary supplement and in a variety of pharmacological and biomedical applications. In addition, water-soluble chitosan has been used to enhance the stability of chitosan in water and reduce cytotoxic activity induced by acetic acid. In this study, the antibiotic activity and mechanism of low molecular weight water-soluble chitosan (LMWSC; MW1, MW3, MW5, and MW10) were examined in pathogenic bacteria cells and vesicles containing bacterial membrane lipids. MW10 displayed potent antibacterial activity against pathogenic bacteria strains and no cytotoxicity against mammalian cells. In addition, the degree of calcein leakage was examined as a function of lipid composition (PE/PG=7/3 w/w). The results of these experiments demonstrated that MW10 promoted leakage in negatively-charged membranes. Furthermore, confocal microscopy revealed that MW10 was located in the plasma membrane.

천연 항균물질 루틴을 함유하는 PHBV 나노섬유의 제조 및 생체적합성

cytotoxicity; antibacterial; rutin; PHBV; KB cell.

Rutin(R) exhibits a wide range of biological activities including anticarcinogenic, antiinflammatory and antiviral actions. The purpose of this study is to investigate the effect of rutin concentrations (1 and 3 wt%) on the antibacterial activity of poly(3-hydroxybutylate-co-hydroxyvalerate)(PHBV) scaffolds. Antibacterial activity was evaluated by using Staphylococcus aureus and Klebsiella pneumoniae. Furthermore, the qualitative ongrowth of human KB endothelial cells was done to study in vitro cytotoxicity of the scaffolds. As the results, PHBV scaffolds containing 3 wt% rutin completely inhibited the proliferation of Staphylococcus aureus and Klebsiella pneumoniae. In addition, the PHBV/R scaffolds used in this study did not show any cytotoxicity when evaluated them with KB endothelial cells.

약물전달체로서 디옥시콜산이 결합된 히알루론산의 제조와 특성

hyaluronic acid; bile acid; deoxycholic acid; drug carrier; nanoparticle.

To develop hyaluronic acid (HA)-based anticancer agent carrier, hyaluronic acid was chemically modified with the hydrophobic group of deoxycholic acid(DA). The physicochemical properties of the deoxycholic acid-conjugated HA (HADA) were investigated by using 1H NMR, FTIR, spectrophotometer and TEM. Paclitaxel (Tx)-loaded HADA nanoparticles were prepared by a dialysis method. The loading efficiency of drug and drug contents of Tx-loaded HADA nanoparticles (HADA-Tx) were measured by HPLC. The anticancer activity of HADA-Tx was investigated by its cytotoxicity against KB cell in vitro. The HADA-Tx was shown to have the superior potential for the anticancer drug delivery.

전자빔을 이용한 Poly(dimethyl siloxane)의 개질

electron beam; modification; poly(dimethyl siloxane); thermal and mechanical properties; ctron beam; modification; poly(dimethyl siloxane); thermal and mechanical properties,wettability.

In this paper, poly(dimethyl siloxane) (PDMS) was modified using electron beam irradiation and its property was investigated. PDMS sheets prepared using a conventional thermal curing method were irradiated by electron beams at absorbed doses between 20 and 200 kGy and their properties were characterized using swelling degree and contact angle measurements, universal testing machine (UTM), thermogravimetric analyzer (TGA), and X-ray photoelectron spectrometer (XPS). The results of the swelling degree measurements, UTM, and TGA revealed that the swelling degree of the irradiated PDMS sheets was reduced down to 24% in comparison to the control sheet, and their compression strength and thermal decomposition temperature increased up to maximum 2.5 MPa and 10 ℃, respectively, due to the increase in crosslinking density by irradiation. In addition, on the basis of the results of contact angle measurements and XPS, the wettability of the PDMS sheets was enhanced up to 24% owing to the generation of hydrophilic functional groups on the PDMS surface by oxidation during electron beam irradiation.

생체 내 특정 조직의 표적을 위한 키토산 유도체

LMWSC; target; specific tissue; ligand; therapeutic gene; cancer

Chitosan as a natural polymer has superior physicochemical properties such as biocompatibility, biodegradability and nontoxicity, but application of chitosan for therapy of cancer and gene related-disease has been limited by poor solubility in aqueous solution. Therefore, low molecular weight water-soluble chitosan (LMWSC) with high reactivity and strong positive charge can be applied as a delivery system having function to carry in the specific tissue the bioactive material like poor solubility drug, or therapeutic gene and developed as a therapeutic system having good therapeutic efficiency. The most important factor for therapy of various diseases is to reveal the antigen or receptor expressed in specific lesion tissue and the antibody and ligand which can bind with antigen is to introduce at the biomaterials for enhancement the therapeutic efficiency. The studies for cationic synthetic polymer as drug or gene delivery have been actively erformed, but it has many problems such as toxicity in the body, therapeutic efficiency. From this point of view, this article demonstrated the introduction of functional groups to target the specific tissue and therapeutic strategy using the modification of LMWSC with free-amine group. The development of these delivery system will provide a positive vision for cancer therapy.

약물 및 유전자 전달체로 응용하기 위한 Poly(L-Lysine)이 결합된 O-Carboxymethyl Chitosan PEG의 제조와 특성

OCMCh-PEG; OCMCh-PEG-PLL; ion complex

O-carboxymethyl water-soluble chitosan (OCMCh) prepared for enhance the application of chitosan was modified with mthoxy polyethyleneglycol (mPEG) by ion-complex for long circulation in the blood. OCMCh-PEG-PLLs was prepared by forming ion-complex with OCMCh-PEG and Poly(L-Lysine) (PLL) for drug and gene delivery system. The physicochemcal characterisitcs of OCMCh-PEG-PLLs were investigated by FT-IR, 1H-NMR. These results showed that CMCh-PEG-PLLs were successfully syntehsized by ion-complex. Particle size distribution and zeta potential of the OCMCh-PEG-PLLs were determined using dynamic light scattering technique. Transmission electron microscopy (TEM) was also used to observe the morphology of the OCMCh-PEG-PLLs. OCMCh-PEG-PLLs have spherical shapes with particle size 290∼390 nm. OCMCh-PEG-PLLs were showed when the feeding amount of mPEG ratio was increased, particle size and zeta potential were decreased. Based on these results, it is possible to introduction of the OCMCh-PEG-PLLs into various biomedical fields such as drug and gene delivery system.

염료감응형 태양전지의 광전자 재결합 방지를 위한 Al2O3 코팅 TiO2 전극 제조

dye-sensitized solar cells; bohemite sol; Al2O3-coated TiO2; energy conversion efficiency

To increase the energy conversion efficiency of dye sensitized solar cells (DSSCs), it has been widely studied how to effectively transferred the electron generated from the adsorbed dye to the TiO2 electrode for avoiding the recombination of injected electrons and iodide ions (I-/I3-). For the blocking of the recombination, in this study, Al2O3-coated TiO2 electrode was prepared and applied for DSSCs. In especial, the optimal preparation conditions of Al2O3 coated onto TiO2 porous film was proposed for higher energy conversion efficiency. As a result, the solar cells fabricated from Al2O3-coated (i.e., particle size of bohemite sol : 100 nm) TiO2 electrodes showed superior conversion efficiency (9.0%) compared to the bare TiO2 electrodes (7.5%).

소수성 플라보노이드인 루테올린을 함유한 Ethosome의 제조 및 특성조사

ethosome; hydrophobic; luteolin; stability; liquid crystalline phase

Entrapment of hydrophobic flavonoid luteolin into ethosome was carried out for improving its stability and making practical application in the field of drug and cosmetics. The formation of liquid crystalline phase and its thermal properties were investigated by polarized optical microscopy and DSC. The phase inversion from W/O to W/O/W was detected by conductivity change with the addition of PBS buffer solution into the ethanol-dissolved lecithin mixture. The particle size change of ethosome with constituent composition was examined, which showed that the incorporation of luteolin into lecithin up to 10% had little effect on the size of ethosome. Enhancement of stability of luteolin by entrapment into ethosome was verified through DPPH test. The stabilization efficacy of ethosome was improved further by the addition of tocopherol.

Recycling of excess sludge using titanium tetrachloride (TiCl4) as a flocculant aid with alkaline-thermal hydrolysis

Activated sludge; Waste treatment; Metabolic engineering; Alkaline-thermal hydrolysis; Aerobic digestion; Titanium dioxide

The highly strengthened treatment and disposal of excess sludge based on economic and environmental regulation factors is one of the important issues to be dealt with in the activated sludge process. In this study, the reduction and recycling technology of excess sludge were investigated for the aim of achieving a zero emission of excess sludge produced from the activated sludge process using titaniumtetrachloride (TiCl4) as a flocculant aid with alkaline-thermal hydrolysis. Alkaline-thermal hydrolysis of excess sludge was obtained 73% and 40% reduction rate at pH 13 (60 8 ℃) and pH 11 (60 8 ℃), respectively. Flocculation was carried out using a Ti-salt flocculant and the collected sludge was dewatered and incinerated at 600 ℃ to produce TiO2 nanoparticles. The amount of total suspended solids and volatile suspended solids was significantly decreased with pH increase. The optimal dose of Ti-salt flocculation aid to improve dewatering ability of sludge breakage was 23.95 Ti-mg l^(-1). Also, in the batch culture, the supernatant after flocculation and the organic matter released from the lysed sludge were found to be useful as a source of energy for the growth ofmicroorganisms during the aerobic operations period. TiO2 produced from Ti-salt flocculation of excess sludge (TES) was characterized by X-ray diffraction, scanning electron microscopy/energy dispersive X-ray and photocatalytic activity.

PAA/PHA/Organoclay 나노복합재료의 제조 및 특성

poly(amic acid); polyhydroxyamides; thermal cyclization reaction; nanocomposite

Nanocomposite films were prepared by blending poly(amic acid)(PAA), poly(o-hydroxyamide)( PHA) and organically modified montmorillonite (OMMT) that has a layered structure. XRD, SEM and TEM were used to study the morphology of PAA/PHA nanocomposites, and DMA, TGA, UTM, LOI and PCFC techniques were used to characterize the mechanical and thermal properties, and flame retardancy of the nanocomposites. TEM images revealed that OMMT layers were well dispersed in the PAA/PHA matrix and showed exfoliation and intercalation behavior. The addition of 3 wt% OMMT to the PAA/PHA blend increased the initial modulus of PAA/ PHA blend to 3.68 GPa that was ca. 48% higher than that of the control PAA/PHA blend. Above 4 wt%, however, both the initial modulus and the tensile strength were found to decrease, which might be due to the aggregation of OMMT in PAA/PHA matrix. When the OMMT content was below 3 wt%, the thermal stability and flame retardancy of the PAA/PHA nanocomposites increased with increasing OMMT content.

Preparation of titanium oxide, iron oxide, and aluminium oxide from sludge generated from Ti-salt, Fe-salt and Al-salt flocculation of wastewater

Flocculation; Sludge recycling; Titanium dioxide; Hematite; Alumina

In this study, the settled floc (sludge) produced by aluminum sulfate (Al2(SO4)3), ferric chloride (FeCl3) and titanium tetrachloride (TiCl4) flocculation was recycled with a novel flocculation process, which has a significant potential to the lower cost of waste disposal, protect the environment and public health and yield economically useful by-products. Three coagulants removed 70% of organic matter in synthetic wastewater. The settled floc was incinerated in the range from 100 ℃ to 1000 ℃. Alumina (Al2O3), hematite (Fe2O3), titanium oxide (TiO2) which are the most widely used metal oxides were produced from the wastewater sludge generated by the flocculation in wastewater with Al2(SO4)3, FeCl3 and TiCl4, respectively. TiO2 particles produced from the sludge consisted of the large amount of nano size particles. Hematite (Fe2O3) and grattarolaite (Fe3 (PO4)O3 or Fe3PO7) included the majority of micro size (40%) particles. Alumina (Al2O3) also consisted of micro size (40%). Due to TiO2 usefulness of the application, detailed characterisation of TiO2 after calcination at different temperatures were investigated in terms of X-ray diffraction, energy dispersive X-ray, surface area and photoactivity.

Development of a novel method to prepare Fe- and Al-doped TiO2 from wastewater

Titanium oxide; Iron doping; Aluminium doping; Wastewater; Flocculation

A simple and novel method to synthesize iron and aluminium-doped titanium dioxide (TiO2) was investigated. Titanium tetrachloride (TiCl4) was used as a coagulant to remove organic matter from wastewater. The settled floc (sludge) was dewatered and incinerated at 600 ℃ after TiCl4 flocculation. The resultant by-product from the waste sludge was valuable TiO2. TiCl4 coagulant was added with FeCl3 and Al2(SO4)3 coagulants to dope iron and aluminium on TiO2 in a flocculation process. The effect of iron and aluminium on TiO2 was investigated in terms of scanning electron microscopy/energy dispersive Xray (SEM/EDX), X-ray diffraction (XRD), optical absorbance and photocatalytic activity. The majority of Fe/TiO2 and Al/TiO2 particleswere found to be less than 1 μm size formed by 0.1 μm agglomerates using SEM analysis. Fe/TiO2 included Ti, O, C, P and Fe elements and Al/TiO2 consisted of Ti, O, C, P and Al elements as confirmed by EDX results. Remaining organic carbon from the settled organic matter was the source of C atom in TiO2 whereas the P atom in TiO2 came from phosphorus nutrient present in wastewater. The majority of acetaldehyde with Fe/TiO2 and Al/TiO2 was significantly removed under UV irradiation within 60 min. However, at higher iron concentration, acetaldehyde removal decreased by almost 50%. Under visible light irradiation, the photo-decomposition of acetaldehyde using the Fe/TiO2 and Al/TiO2 was marginal.

Characteristics of phenol degradation by immobilized activated sludge

Phenol; Immobilized activated sludge; Wastewater; Loading rate

The effects of various factors involved in phenol degradation through an immobilized activated sludge with a photo-crosslinked resin were investigated. The immobilized activated sludge showed a higher relative activity of phenol degradation across a broader range of pH than free activated sludge. A higher rate of phenol degradation was observed when the bead size was smaller. The phenol degradation in the free activated sludge was inhibited at the 3000 mg/L of phenol, while that in the immobilized activated sludge was maintained at the same concentration for 28 h without any inhibition. The degradation rates of phenol were not directly proportional to the increasing amount of immobilized bead dosage, but the phenol degradation was completed in a shorter time than that for the free activated sludge. For the repeated reaction of immobilized activated sludge, the relative activity is increased up to eight times after seven repeated initial cycles. Continued treatment of immobilized activated sludge showed more than 95% of phenol removal efficiency under a loading rate of 5.59 kg-phenol/(m3 d), which is twice as large as the loading rate for the free activated sludge.

바이오가스 개질을 위한 글라이딩 아크 플라즈마 개질 시스템 개발

biogas; H2 yield; CO removal; PEMFC

The purpose of this study is to investigate the optimal condition for the hydrogen-rich gas production and the CO removal by reforming of gliding arc plasma reforming system using biogas. The parametric screening studies were carried out according to changes of steam feed amount, catalyst bed temperature in water gas reactor and catalyst bed temperature, input air flow rate in preferential oxidation reactor. The standard condition is as follows. The steam/carbon ratio, catalyst bed temperature, total gas flow rate, input electric power and biogas composition rate (CH4 : CO2) were fixed 3, 700 ℃, 16 L/min, 2.4 kW and 6 : 4, respectively. The results are as follow, HTS optimum operating conditions were S/C ratio of 3 and reactor temperature of 500℃. LTS were S/C ratio of 2.9 and temperature of 300℃. Also, PROX I optimum conditions were input air flow rate of 300 mL/min and reactor temperature of 190℃. PROX II were 200 mL/min and 190℃respectively. After having passed through each reactor, the results were as follows: 55% of H2 yield, 0% of CO selectivity, 99% of CH4 conversion rate, 27% of CO2 conversion rate, respectively.

폐수처리를 위한 미생물연료전지의 전기생산 특성

electricity; microbial fuel cell; resistance; energy

Microbial fuel cells (MFCs) have been known as a new alternative energy conversion technology for treating wastewater and producing electricity simultaneously. A MFC converts the chemical energy of the organic compounds to electrical energy through microbial catalysis at the anode under anaerobic conditions. To examine the performance of MFC, in this work, the characteristics of the efficiency of wastewater treatment and generation of electricity was evaluated for sewage. When acetate as a carbon source was added into the sewage, the removal efficiency of COD was increased from 75.7% to 88.2% and the voltage was increased significantly from 0.22 V to 0.4 V. The influence of distance between anode and cathode was examined and the effect of the surface area of anode was investigated under the various external resistances. It was found that the maximum power density was 610 mW/m2 and power generation was effective when the distance between the electrodes was shorter and the surface area of the anode was smaller.

형광체 첨가에 따른 염료감응형 태양전지의 효율 변화

dye-sensitized solar cells; TiO2; phosphor; conversion efficiency

Recently, dye-sensitized solar cell (DSSC), one of the solar cells, has been widely investigated. Studies on DSSCs can be classified into 4 fields such as TiO2 nanocrystalline materials, dyes, electrolytes and conductive plate. In this work, TiO2 nanoparticles for dye adsorption were synthesized, and added into the photo-electrode paste with different phosphor types and contents. Then, the influence of phosphor additives on the conversion efficiency of DSSCs was investigated. It was found that the maximum conversion efficiency was 8.81% when 0.5% of YAG phospher having the particle size of 400 nm was used.

하수슬러지 활성탄화로 개발

adsorbent; carbonization; steam activation; sewage sludge; pore development

The purposes of this study are to treat sewage sludge that has increasingly become an issue and to recycle it as the adsorbent. The adsorbent was produced by carbonization and simultaneous steam activation, and its characteristics were studied. Parametric screening studies were carried out for the preparation of good adsorbent. Optimum operating conditions were confirmed as input carbonization-activated temperature of 840 ℃, feed steam flow rate of 70 g/min, carbonization-activated time of 30 min and feed dried sludge of 10.8 kg/day, respectively. At this time, the iodine adsorptivity was maximized as 328.1 mg/g. Pore development, structure, element compound and content were confirmed by using nanoPOROSITY, SEM (Scanning electron microscope), and EDS (Energy dispersive spectroscopy). Through this result, it was known that the adsorbent derived from sewage sludge could be used for the treatment of leachate in a landfill, VOCs (Volatile organic compounds), and so on.

초임계 이산화탄소를 이용한 pH 감응성 하이드로젤 입자의 합성

Supercritical CO2; Hydrogel Nanoparticles; pH-Responsive; Intelligent Drug Delivery System

Recently, new methods to synthesize and process polymers without toxic organic solvents are needed in order to solve environmental problems. The use of supercritical carbon dioxide as a solvent for the polymer synthesis is attractive since it is non-toxic, non-flammable, naturally abundant, and the product may be easily separated from the solvent. In this study, we developed the method using super critical CO2 to prepare P(MAA-co-EGMA) hydrogel nanoparticles as an intelligent drug delivery carrier. The effects of concentrations of PtBuMA-PEO as a dispersion stabilizer and AIBN as an initiator on the particle synthesis were investigated. When PtBuMA-PEO concentration increased, the particle size decreased. However, there was no significant difference in the particle size according to the AIBN concentration. There was a drastic change of the equilibrium weight swelling ratio of P(MAA-co-EGMA) hydrogel nanoparticles at a pH of around 5, which is the pKa of PMAA. At a pH below 5, the hydrogels were in a relatively collapsed state but at a pH higher than 5, the hydrogels swelled to a high degree. In release experiments using Rh-B as a model solute, the P(MAA-co-EGMA) hydrogel nanoparticles showed a pH-sensitive release behavior. At low pH(pH 4.0) a small amount of Rh-B was released while at high pH(pH 6.0) a relatively large amount of Rh-B was released from the hydrogels.

Effect of Fomitopsis pinicola extract on blood glucose and lipid metabolism in diabetic rats

F. pinicola; Blood Glucose; Lipid Metabolism; Cholesterol

This study was performed to investigate the effects of Fomitopsis pinicola extract on blood glucose and lipid metabolism in diabetic rats. The blood glucose concentration was similar to that of the control at 30 min, but after 60 min of glucose administration the blood glucose concentration rapidly decreased, and after 120 min was 100.7±4.0 mg/dL, representing an approximate 50% decrease compared to the control. In the case of the diabetic rats induced by streptozotocin, the concentration of blood glucose was decreased from 362.0±16.7 to 204.5±11.4 mg/dL after 20 days of administration. HDL- and LDL-cholesterol concentrations were 39.0±4.3 mg/L and 13.2±3.4 mg/dL, respectively, representing an approximate increase of 73% and approximate decrease of 76%, respectively, compared to the control. The activities of aspartate aminotransferase and alanine transaminase were increased. On the other hand, activities of amylase, alkaline phosphatase, lactate dehydrogenase, glutamic oxaloacetic transaminase, and glutamic pyruvic transaminase were decreased compared to that of the control. No difference was evident between test and control rats with respect to white blood cell, red blood cell, hemocyte, hemoglobin, hematocrit, and platelet counts. These results indicate that F. pinicola extract is useful as a preventative and treatment agent for damage of liver and kidney cells.

Production of synthesis gas from methane using compression ignition reformer

Synthesis Gas; Hydrogen Production; Reforming; Biogas; Compression Ignition Engine

A new form for a partial oxidation compression ignition reformer, which is different from existing methods of reformation, is suggested to which the concept of super-adiabatic combustion is applied. In addition, experiments are conducted on variables such as the oxygen/methane ratio, the total flow rate, the intake preheating temperature, and the oxygen enrichment ratio, all of which affect the production of hydrogen, in order to understand the optimal features of the movement of the reformer. Results showed that the concentration of hydrogen and carbon monoxide was 20.84% and 13.36%, respectively, under the optimal standard conditions of an oxygen/methane ratio of 0.26, a total flow rate of 106.5 L/min, and an intake preheating temperature of 355 ℃. Under the same conditions, the concentration of hydrogen decreased to 20.31% when the oxygen enrichment ratio was 55.6%, while that of carbon monoxide increased to 20.85% when the oxygen enrichment ratio was 50.33%.

In vitro and in vivo Characterization of a Coronary Stent Coated with an Elastic Biodegradable Polymer for the Sustained Release of Paclitaxel

Modified Sulfonated Poly(arylene ether sulfone) Membranes Prepared via a Radiation Grafting Method for Fuel Cell Application

Fabrication of PHBV/Keratin Composite Nanofibrous Mats for Biomedical Applications

biomedical; fibrobalsts; keratin; nanofiber; PHBV.

Keratin is an important protein used in wound healing and tissue recovery. In this study, keratin was modified chemically with iodoacetic acid (IAA) to enhance its solubility in organic solvent. Poly(hydroxybutylate-cohydroxyvalerate) (PHBV) and modified keratin were dissolved in hexafluoroisopropanol (HFIP) and electrospun to produce nanofibrous mats. The resulting mats were surface-characterized by ATR-FTIR, field-emission scanning electron microscopy (FE-SEM) and electron spectroscopy for chemical analysis (ESCA). The pure m-keratin mat was cross-linked with glutaraldehyde vapor to make it insoluble in water. The biodegradation test in vitro showed that the mats could be biodegraded by PHB depolymerase and trypsin aqueous solution. The results of the cell adhesion experiment showed that the NIH 3T3 cells adhered more to the PHBV/m-keratin nanofibrous mats than the PHBV film. The BrdU assay showed that the keratin and PHBV/m-keratin nanofibrous mats could accelerate the proliferation of fibroblast cells compared to the PHBV nanofibrous mats.

Methotrexate-Incorporated Polymeric Micelles Composed of Methoxy Poly(ethylene glycol)-Grafted Chitosan

methotrexate; polymeric micelle; chitosan; ion complex; MPEG.

In this study, methotrexate (MTX)-encapsulated polymeric micelles using methoxy poly(ethylene glycol) (MPEG)-grafted chitosan (ChitoPEG) copolymer were prepared. The MTX-incorporated polymeric micelles of ChitoPEG copolymer has a particle size of around 50-100 nm. In 1H nuclear magnetic resonance (NMR) study, the specific peaks of MTX disappeared in heavy water (D2O) and only the specific peak of MPEG was observed, while all of the peaks were confirmed in dimethyl sulfoxide (DMSO). These results indicated that MTX was complexed with chitosan and then formed an ion complex inner-core of the polymeric micelle in an aqueous environment. The drug contents of the polymeric micelle were around 4~12% and the loading efficiency of MTX in the polymeric micelles was higher than 60% (w/w) for all of the formulations. The cytotoxicity of MTX and MTX-incorporated polymeric micelle against CT26 tumor cells was not significantly changed.

Albumin-conjugated Cadmium Sulfide Nanoparticles and their Interaction with KB Cells

cadmium sulfide nanoparticles; bovine serum albumin; biocompatibility; fluorescence intensity.

Cytotoxicity is a severe problem of cadmium sulfide nanoparticles (CSNPs) for use in biological systems. In the present study, mercaptoacetic acid-coated CSNPs were conjugated with bovine serum albumin (BSA) to improve biocompatibility. The surface properties of the CSNPs and albumin-conjugated CSNPs (ACSNPs) were characterized by XRD, UV, FTIR, EA, TEM and DLS. Human breast cancer cells (KB cells) were then cultured in the presence of the nanoparticles to evaluate the cytotoxicity of CSNPs and ACSNPs. Finally, the fluorescence intensity of the nanoparticles’ aqueous solution was examined using a fluorescence spectrometer. The results showed that the cell compatibility and fluorescence intensity of ACSNPs were higher than those of CSNPs. The strongly luminescent features of the biocompatible ACSNPs are promising for use in biological fields such as cellular labeling, intracellular tracking and molecular imaging.

Synthesis and Characterization of Thermosensitive Nanoparticles Based on PNIPAAm Core and Chitosan Shell Structure

nanoparticles; chitosan; lower critical solution temperature; thermosensitive.

Noble thermosensitive nanoparticles, based on a PNIPAAm-co-AA core and a chitosan shell structure, were designed and synthesized for the controlled release of the loaded drug. PNIPAAm nanoparticles containing a carboxylic group on their surface were synthesized using emulsion polymerization. The carboxylic groups were conjugated with the amino group of a low molecular weight, water soluble chitosan. The particle size of the synthesized nanoparticles was decreased from 380 to 25 nm as the temperature of the dispersed medium was increased. Chitosan-conjugated nanoparticles with 2~5 wt% MBA, a crosslinking monomer, induced a stable aqueous dispersion at a concentration of 1 mg/1 mL. The chitosan-conjugated nanoparticles showed thermosensitive behaviors such as LCST and size shrinkage that were affected by the PNIPAAm core and induced some particle aggregation around LCST, which was not shown in the NIPAAm-co-AA nanoparticles. These chitosan-conjugated nanoparticles are also expected to be more biocompatible than the PNIPAAm core itself through the chitosan shell structures.

항균성 PMMA 나노섬유 부직포의 제조

PMMA; nanofiber; silver nanoparticles; antibacterial activity

In this study, electrospinning conditions for PMMA were studied. Namely, the ratio of DMF and THF and its maximum concentration were examined. Conductivity of the polymer solution containing silver nanoparticles and its effect on fiber diameter were also studied. As the results, the maximum concentration for the electrospinning of PMMA was found at 18 wt%, and the ratio of DMF/THF was 7：3. The diameter of nanofibers obtained was 100-400 nm when the PMMA solution containing 1000 ppm silver was electrospun. It was found, from TEM results, that silver nanoparticles were distributed on the edge of fibers and the resulting nanofiber mats showed a good antibacterial activity.

천연 항균물질 함유 나노섬유의 제조 및 특성분석

electrospinning; PHBV; nanofiber; plant polyphenol; natural antimicrobial.

The fabrication of PHBV nanofibers containing various plant polyphenols by electrospinning has been examined. It has been found that the average diameters of fibers increased by the adding of polyphenols. The resulting fibers exhibited a uniform diameter ranging from 340 to 450 nm. As the concentration of polyphenols increased, the diameter of fibers increased due to the hydrogen bonding interaction between the ester groups of PHBV and hydroxyl groups of polyphenols. The interaction between PHBV and polyphenols, which forms a complex together in solution, was verifed by UV measurement. ATR-FTIR analysis confirmed the existence of the hydrogen bonding interaction. The semicrystalline structure of the PHBV nanofiber was observed from XRD pattern. The crystallinity of PHBV nanofibers was increased by the adding of polyphenols. PHBV nanofibers containing polyphenols showed superior antimicrobial activities.

소수성 항진균제 전달체로 응용하기 위한 데옥시콜릭산이 결합된 저분자량 수용성 키토산 나노입자의 제조와 특성

LMWSC; deoxycholic acid; antifungal; itraconazole; drug

To develop the carrier of hydrophobic antifungal agents based on low molecular weight watersoluble chitosan (LMWSC), LMWSC was chemically modified with deoxycholic acid (DA) which is one of the bile acid as a hydrophobic group. The nanoparticles (WSCDA) using DA conjugated LMWSC were characterized using dynamic light scattering(DLS) and transmittance electron microscope (TEM). The particle size of WSCDA ranged from 250 to 350 nm and increased with the number of DA substitution. The loaded itraconazole as an antifungal agent WSCDA nanoparticles (WSCDA-ITCN) were prepared by solvent evaporation method. The drug content and the loading efficiency were investigated approximately 9∼10% and 61∼68% by UV spectrophotometer, respectively. The release of drug from nanoparticles was slow and showed sustained release characteristics. Based on the results of release study that the higher DA contents in WSCDA, the slower the releasing rate, the WSCDA-ITCN could be used as an excellent antifungal agent.

Norfloxacin이 담지된 Poly(ε-caprolactone)/Poly(ethylene glycol) 이중블록공중합체 미셀의 제조

polymeric micelle; norfloxacin; biodegradable polymer; antimicrobial agent; diblock copolymer.

We prepared norfloxacin (NFX)-incorporated polymeric micelle using poly(ε-caprolactone)/ poly(ethylene glycol) (PCL/PEG, CE) diblock copolymers. Particle size was from 60 to 200 nm according to the PCL block length. Their critical association concentration (CAC) was decreased according to the increase of PCL block length. 1H-NMR study showed core-shell type micelle structures of CE diblock copolymers in the aqueous environment. Drug release from polymeric micelle was continued over 2 days. Duration of drug release was varied according to the PCL block length and drug contents. At antimicrobial activity test, polymeric micelle showed almost similar cytotoxicity compared to NFX itself.

Multiparticulation of ciprofloxacin HCl-encapsulated chitosan microspheres using poly(DL-lactide-co-glycolide)

Ciprofloxacin HCl; Low-molecular weight water-soluble chitosan; Microspheres; Multiparticulation; Sustained release

In this study, we prepared poly(DL-lactide-co-glycolide) (PLGA)-coated chitosan oligosaccharide (COS) microspheres. Ciprofloxacin HCl (CIP)-encapsulated COS microspheres were prepared by the pressure homogenization and spray drying technique. The microspheres have spherical shapes and their particle size was in the range of 2-3 μm in diameter. When they were coated with PLGA, PLGA-coated COS microspheres showed rough spherical surfaces, indicating that COS microspheres might be existed on the surface of particles in addition to the inside of particles. The efficiency of loading and size of particle were increased with the increase of the amount of PLGA feeding amount. At the effect of PLGA series, the loading efficiency and particle size were in the order of RG504H > RG503H > RG502H. Drug release rate was decreased with the increase of the amount of PLGA feeding and initial burst was 3-10 days according to the PLGA feeding amount. At the effect of PLGA series, drug release rate was in the order of RG502H > RG503H > RG504H. When acetone was used, drug release rate was slightly increased. PLGA-coated COS microspheres were successfully prepared and characterized.

Halogen-free flame retarding NBR/GTR foams

NBR/GTR blend; halogen-free flame retardant; di-melamin pyrophosphate; expandable graphite; red phosphorus; P-N synergy

The effectiveness of some halogen-free flame retardants (i.e. aluminium trihydroxide, red phosphorus, ammonium polyphosphate, di-melamine pyrophosphate and expandable graphite) in flame retardancy of acrylonitrile butadiene rubber (NBR)/ground tire rubber (GTR) foams, blown with azodicarbonamide has been investigated by means of cone calorimetry and limiting oxygen index tests. The GTR itself was effective to reduce flammability of NBR/GTR foams. The charring behavior and synergistic effect in flame retardancy of NBR/GTR foams filled with the flame retardants have also been considered. The results showed that the introduction of phosphorus compound and expandable graphite into the foam containing aluminium trihydroxide as a base flame retardant results in a processable and considerable flame retarding products. P and N containing flame retardant such as di-melamine pyrophosphate gave the highest flame retardancy in limiting oxygen index (LOI) test and in heat release rate of the NBR/GTR foams. The results also indicated that the P-N synergistic action was not only dependent on the component proportion of flame retardants used, but was also influenced to a great degree by the P2O5/N ratios. Published by Elsevier B.V.

Studies on saccharification from alginate using Stenotrophomonas maltophilia

saccharification; alginate; Stenotrophomonas maltophilia

Various environmental factors affecting saccharification from alginate using Stenotrophomonas maltophilia were investigated in flask cultures. The cell concentrations increased from 0.6 to 0.92 optical density (OD) at 660 nm when the agitation rate increased from 15 to 90 rpm. On the other hand, the maximum concentration of sugar was obtained at 3.8 g/l after 4 days of culture at 15 rpm. After 3 days of preculture at 33 degrees C, the sugar concentration peaked at 5.0 g/l after 5 days of culture. When 10 g/l of NaCl was used, the maximum concentration of sugar, 5.3 g/l, was obtained after 5 days of culture. Yeast extract and peptone were the best nitrogen source for effective saccharification. Especially, the sugar concentration was 6.1 g/l after 5 days of culture using a mixture of 1.0 g/l of yeast extract and 1.0 g/l of peptone. Under optimum conditions of culture and media, scale-up for effective saccharification from alginate was carried out in 5 1 flasks. The cell concentration after 2 days of culture was 0.61 OD at 660 nm and showed no further increase after 3 days of culture. The sugar concentrations from alginate were increased with increasing culture time to 7.9 g/l after 9 days of culture. (C) 2008 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.

생체의료용 재료로써 키틴.키토산의 특성

chitin; chitosan; LMWSC; biomedical materials; DDS; crystallin structure

Development of various medical systems was accomplished through the progress of biotechnological method for therapy of human diseases. Furthermore, drug delivery systems have been investigated to carry the bioactive materials such as drug or gene in the body effectively. The most important thing in this system is to develop biomedical polymers having biocompatibility, biodegradability, and non-toxicity. Chitosan, a natural polymer, has been importantly considered as biomedical materials due to its good biocompatibility and various bio-active characteristics. Since the property of chitosan is differently explained according to the crystalline structures of chitin, the study for structural analysis of chitin has to proceed to apply as a biomaterial. From this point of view, this article introduced the analysis of crystalline structural of chitin, general property of chitosan and potential characteristics of low molecular weight water-soluble chitosan (LMWSC) as a biomaterials. Furthermore, chemical modification of LMWSC using various functional groups was also performed to enhance its bioavailability and emphasize their potential as drug delivery carriers (DDS).

고순도 수소생산을 위한 고온전이 반응 연구

high-purity hydrogen; high temperature shift; CO concentration

The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. In general, most feasible strategies to generate hydrogen from hydrocarbon fuels consist of a reforming step to generate a mixture of H2, CO, CO2 and H2O (steam) followed by water gas shift (WGS) and CO clean-up steps. The WGS reaction that shifts CO to CO2 and simultaneously produces another mole of H2 was carried out in a two-stage catalytic conversion process involving a high temperature shift (HTS) and a low temperature shift (LTS). In a typical operation, gas emerges from the reformer is taken through a high temperature shift catalyst to reduce the CO concentration to about 3∼5%. The HTS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to a range of 2∼4%. The iron based catalysts (G-3C) was used for the HTS to convert the most of CO in the effluent from the partial oxidation (POX) to H2 and CO2 at a relatively high rate. Parametric screening studies were carried out for variations of the following variables: reaction temperature, steam flow rate, components ratio (H2/CO), and reforming gas flow rate.

PEMFC용 플라즈마 개질 시스템의 수소 생산

Glidarc; Hydrogen; Plasma Reforming; CO Shift; PEMFC

The purpose of this paper studied the optimal hydrogen production condition of plasma reforming system to operate the PEMFC. Plasma reforming reactor used with Ni catalyst reactor at the same time, So H2 concentration increased. Also the WGS and PrOx reactor were designed to remove CO concentration under 10 ppm, because CO has effect on catalyst poisoning of PEMFC. The maximum H2 production condition in plasma reforming system was S/C ratio 3.2, CH4 flow rate 2.0 L/min, catalytic reactor temperature 700±5 oC and input power 900 W. At this time, the concentration of produced syngas was H2 70.2%, CO 7.5%, CO2 16.2%, CH4 1.8%. The hydrogen yield, hydrogen selectivity and CH4 conversion rate were 56.8%, 38.1% and 92.2% respectively. The energy efficiency and specific energy requirement were 37.0%, 183.6 kJ/mol. In additional, The experiment of CO2/CH4 ratio proceeded. Also WGS reactor experiment was proceeding on optimum condition of plasma reactor and the exit concentration were H2 68%, CO 337 ppm, CO2 24.0%, CH4 2.2%, C2H4 0.4%, C2H6 4.1%. At this time, experiment result of PrOx reactor were H2 51.9%, CO 0%, CO2 17.3%.

Removal characteristics of metal cations and their mixtures using micellar-enhanced ultrafiltration

Heavy Metal; Micelle; Sodium Dodecyl Sulfate (SDS); Ultrafiltration

Divalent ions were removed by ultrafiltration of anionic surfactant solution and the removal characteristics in single and mixed systems were investigated. The removal efficiency was >95% when the ratio of sodium dodecyl sulfate (SDS) to metal ions (S/M ratio) was >10. In single metal systems, the removal efficiency of each metal ion was almost the same. In the mixture, however, there was slight difference (ca. 1-2%) of removal efficiency and the order was Cd2+>Cu2+>Co2+.Zn2+. As S/M ratio increased, the difference in removal efficiency diminished. To explain the difference of removal efficiency in a mixture, complexation of divalent metal ion with counterion was considered. The distribution of complexed form of each metal ion was calculated, but it did not coincide with the experimental results. Further research will be necessary for a clear explanation.

Improvement of combustion efficiency and reduction of NOx emission by external oscillation of reactants in an oil burner

External Oscillation; Low Emission Oil Burner; Combustibility; NOx

The important requirement for the development of burners is the achievement of low emissions, particularly NOx, while maintaining high combustion efficiency. In this work, an externally oscillated oil burner was developed which provides both high-efficiency combustion and low NOx emission simultaneously. To investigate combustion characteristics and NOx emission, parametric studies were carried out about oscillation frequency, forcing amplitude, and air velocity. Optimum combustion was achieved at frequency of 1,900 Hz, amplitude of 3 Vpp, and air velocity of 6.8 m/s. The NOx and CO emissions were reduced by 47% and 22%, respectively. In particular, the mechanism responsible for the inherently low NOx emission levels from an externally oscillated oil burner has been shown to be a short residence time at high temperature caused by rapid mixing with cooler residual gases.

All-trans Retinoic Acid Release from Surfactant-free Nanoparticles of Poly(DL-lactide-co-glycolide)

retinoic acid; surfactant-free nanoparticles; poly(DL-lactide-co-glycolide); dialysis; nanoprecipitation.

In this study, we prepared all-trans retinoic acid (ATRA)-encapsulated, surfactant-free, PLGA nanoparticles. The nanoparticles were formed by nanoprecipitation process, after which the solvent was removed by solvent evaporation or dialysis method. When a nanoparticle was prepared by the nanoprecipitation - solvent evaporation method, the nanoparticles were bigger than the nanoparticles of the nanoprecipitation - dialysis method, despite the higher although loading efficiency. Nanoparticles from the nanoprecipitation - dialysis method were smaller than 200 nm in diameter, while the loading efficiency was not significantly changed. Especially, nanoparticles prepared from DMAc, 1,4-dioxane, and DMF had a diameter of less than 100 nm. In the transmission electron microscopy (TEM) observations, all of the nanoparticles showed spherical shapes. The loading efficiency of ATRA was higher than 90 % (w/w) at all formulations with exception of THF. The drug content was increased with increasing drugfeeding amount while the loading efficiency was decreased. In the drug release study, an initial burst was observed for 2~6 days according to the variations of the formulation, after which the drug was continuously released over one month. Nanoparticles from the nanoprecipitation - dialysis method showed faster drug release than those from the nanoprecipitation - solvent evaporation method. The decreased drug release kinetics was observed at lower drug contents. In the tumor cell cytotoxicity test, ATRA-encapsulated, surfactant-free, PLGA nanoparticles exhibited similar cytotoxicity with that of ATRA itself.

Gas Permeation Properties of Hydroxyl-Group Containing Polyimide Membranes

gas separation; polyimide; hydroxyl group; diffusion coefficient; solubility coefficient

A series of hydroxyl-group containing polyimides (HPIs) were prepared in order to investigate the structure-gas permeation property relationship. Each polymer membrane had structural characteristics that varied according to the dianhydride monomers. The imidization processes were monitored using spectroscopic and thermog-ravimetric analyses. The single gas permeability of He, H2, CO2, O2, N2 and CH4 were measured and compared in order to determine the effect of the polymer structure and functional -OH groups on the gas transport properties. Surprisingly, the ideal selectivity of CO2/CH4 and H2/CH4 increased with increasing level of -OH incorporation, which affected the diffusion of H2 or the solubility of CO2 in HPIs. For H2/CH4 separation, the difference in the diffusion coefficients of H2 and CH4 was the main factor for improving the performance without showing any changes in the solubility coefficients. However, the solubility coefficient of CO2 in the HPIs increased at least four fold compared with the conventional polyimide membranes depending on the polymer structures. Based on these results, the polymer membranes modified with -OH groups in the polymer backbone showed favorable gas permeation and separation performance.

Tissue Engineering Using a Cyclic Strain Bioreactor and Gelatin/PLCL Scaffolds

Preparation and Characterization of Temperature-Sensitive Poly(N-isopropylacrylamide)-g-Poly(L-lactide-co-ε-caprolactone) Nanofibers

electrospinning; temperature-sensitive; tissue engineering; gamma ray irradiation

Biodegradable and elastic poly(L-lactide-co-ε-caprolactone) (PLCL) was electrospun to prepare nanofibers, and N-isopropylacrylamide (NIPAAm) was then grafted onto their surfaces under aqueous conditions using 60Co-γ irradiation. The graft yield increased with increasing irradiation dose from 5 to 10 kGy and the nanofibers showed a greater graft yield compared with the films. SEM confirmed that the PLCL nanofibers maintained an interconnected pore structure after grafting with NIPAAm. However, overdoses of irradiation led to the excessive formation of homopolymer gels on the surface of the PLCL nanofibers. The equilibrium swelling and deswelling ratio of the PNIPAAm-g-PLCL nanofibers (prepared with 10 kGy) was the highest among the samples, which was consistent with the graft yield results. The phase-separation characteristics of PNIPAAm in aqueous conditions conferred a unique temperature-responsive swelling behavior of PNIPAAm-g-PLCL nanofibers, showing the ability to absorb a large amount of water at < 32 ℃, and abrupt collapse when the temperature was increased to 40 ℃. In accordance with the temperature-dependent changes in swelling behavior, the release rate of indomethacin and FITC-BSA loaded in PNIPAAm-g-PLCL nanofibers by a diffusion-mediated process was regulated by the change in temperature. Both model drugs demonstrated greater release rate at 40 ℃ relative to that at 25 ℃. This approach of the temperature- controlled release of drugs from PNIPAAm-g-PLCL nanofibers using gamma-ray irradiation may be used to design drugs and protein delivery carriers in various biomedical applications.

전자선 조사에 의한 온도응답성 나노섬유 표면의 제조 및 특성분석

electrospinning; nanofiber; thermo-responsive property; electron beam irradiation; surface modification

We have fabricated a novel thermo-responsive nanofibrous surfaces by grafting PIPAAm by electron beam irradiation onto poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) nanofibrous mats. The electrospun PHBV nanofiber structures revealed randomly aligned fibers with average diameter of 400 nm. Increased atomic percent of nitrogen was observed on the PIPAAm-grafted PHBV mats after electron beam irradiation determined by ESCA. The amounts of PIPAAm-grafted onto PHBV films were 6.49 μg/cm2 determined by ATR-FTIR. The PIPAAm-grafted surfaces exhibited decreasing contact angles by lowering the temperature from 37 to 20 ℃, while ungrafted PHBV surfaces had negligible contact angle change. This result indicates that PIPAAm surfaces, which are hydrophobic at the higher temperature, became markedly more hydrophilic in response to a temperature reduction due to spontaneous hydration of the surface-grafted PIPAAm. Thermo-responsive nanofibers showed good tissue compatibility. Cultured cells were well detached and recovered from the surfaces by changing culture temperature from 37 to 20 ℃.

소수성 항암제의 전달체로 응용하기 위한 리소콜릭산이 결합된 키토산 나노입자의 제조와 특성

chitosan; nanoparticle; anticancer agent; lithocholic acid; paclitaxel

To develop carriers of hydrophobic anticancer agents based on chitosan, chitosan oligosaccharide lactate (COS) was chemically modified with lithocholic acid (LA) which is one of the bile acids as a hydrophobic group. The physicochemical properties of the lithocholic acid conjugated chitosan nanoparticles (COS-LA) were investigated using 1H-NMR spectroscopy, dynamic light scattering (DLS) and spectrofluorophotometer. COS-LA-paclitaxel (CLs-Tx) nanoparticles loading paclitaxel as an anticancer agent were prepared by a dialysis method and its loading efficiency was measured through HPLC. On the basis of DLS results, the estimated particle sizes of CLs-Tx were around 300 nm. Also, the critical micelle concentration (CMC) was proven to be dependent on the degree of substitution of lithocholic acid. It showed that the CLs-Tx has the superior potential for the application as a paclitaxel carrier.

폴리스티렌 나노섬유상에서의 간세포의 3차원 배양

electrospinning; nanofiber; hepatocyte; 3-D culture; specific hepatic functions

We have fabricated polystyrene (PS) nanofibrous scaffold for hepatocyte culture by electrospinning method and subsequently coated with specific ligand of poly[N-p-vinylbenzyl-O-β-D-galactopyranosyl-(1→4)-D-gluconamide](PVLA) to enhance hepatocytes attachment. Rat hepatocytes behavior on the PVLA-coated and non-coated PS nanofibrous matrices have been investigated. Electrospun PS nanofiber structures revealed randomly aligned fibers with average diameter of 500 nm. It is observed that PS nanofibrous matrix could incorporate many cells into the interior of the matrix probably due to the suitable pore size. Cell viabilities cultured on PVLA-coated PS nanofibrous mats were maintained for 3 weeks, while it was decreased rapidly on PVLA-coated PS dishes. High hepatic functions especially for albumin secretion and ammonia removal were maintained at least for 2 weeks on nanofibrous mats but rapidly decreased on flat PS dishes. These results indicate that nanofibrous structure enabled 3-D culture with high level of cell-cell contact results in providing cell-cell communications and subsequent long-term maintenance of specific cell functions.

Poly(amic acid)와 PBO 전구체의 블렌드 제조 및 특성

poly(amic acid); poly(o-hydroxyamide)s; thermal cyclization reaction; blend

The themal properties, morphology, mechanical properties and gas permeability of the blends of poly(amic acid)(PAA) and poly(o-hydroxyamides)(PHAs) having pendant group was investigated. The 5% weight loss and major weight loss of the blends occurred in the ranges of 348∼407 ℃ and 589∼615 ℃ upon a heating process. After a thermcal annealing, the tensile strength and initial modulus of blends increased 3.7∼52.9% and 34.4∼70% from the value of pure PAA, respectively. Especially the tensile strength and modulus of the PAA/MP-PHA=9/1 showed the highest values(97.5 MPa and 2.67 GPa, respectively), which were 53 and 70% higher than those of pure PAA. The fine PHA domains were found to be uniformly dispersed. The interfacial adhesion between PAA and PHA was identified to be good. The gas permeabilities of PAA/M-PHA blend increased with M-PHA contents.

Hydrogen Production from Methane under an Oxygen-enriched Conditions Using Compression Ignition Engine

hydrogen; reforming; oxygen-enriched

This study on methane reforming suggests a new method using partial oxidation compression ignition reformer where the concept of super-adiabatic combustion is applied. In this research, optimum condition for producing hydrogen from methane, which is the main component of biogas, using a compression ignition reformer, is studied as a basic approach for producing synthetic gas from biogas. For compression ignition reformer using partial oxidation reaction, an unmodified compressed ignition internal combustion engine is used. The experiment is carried out using enriched oxygen by adding oxygen, which is oxidant, to expand the limit of inflammability range so that the engine could be operated even at the fuel -rich. The oxygen/fuel ratio (oxygen enrichment rate), total flow rate and intake preheating temperature were used as experiment variables. When oxygen/fuel ratio (oxygen enrichment rate: 77.2 %) is 1.24, total flow rate is 208.4 L/min and intake preheating temperature is 400 ℃, the maximum hydrogen concentration obtained was 29.22, 26.93 and 23.53 % respectively.

Chemical Reactor of Superadiabatic Compression

chemical reactor; superadiabatic compression; syngas production; multistage compression

The new technology of manufacturing chemical products with the superadiabatic compression was suggested. The thermodynamic processes in the chemical reactor of superadiabatic compression (CRSAC) of cyclic operation with multistage compression on the basis of internal combustion engine principles were analyzed. The theoretical analysis of nitrogen fixation under air compression in the CRSAC was carried out to show the possibility of gas synthesis in CRSAC. The technology of the synthesis gas production in the CRSAC at partial oxidation of methane in the mode of volumetric ignition by compression without any external preheating a mixture was also considered. The possibility of the methane conversion for the CH4 concentration up to 30 % in the fuel-air mixture was shown. It was found that the part of the methane conversion to syngas with the ratio H2/CO = 2 can reach of 0.95∼0.99 in the reactor with two compression strokes at low compression ratio 10∼15. The specific power performance is more than 3 m3 of syngas per 1 kW-h of the consumed energy.

Reforming Characteristics for Hydrogen Production Using Plasmatron

reforming; hydrogen; plasma torch; fuel cell

A high-temperature plasma torch (a so-called plasmatron) was designed for a hydrogen production reformer. Experiments were carried out to determine the optimal operating conditions producing the maximum amount of hydrogen. The maximum values of the H2, CO, H2 yield and the energy conversion efficiency were 30.9, 20.2, 97.7, and 40.5 %, respectively. Parametric studies were performed regarding the effects of vapor, carbon dioxide, and catalyst addition in the reactor, respectively. In the case of vapor reforming, H2 was mostly unchanged with an average value of 29.2 %. However, CO was reduced as 6.6∼8.6 %, while CO2 was increased with the increase of the vapor flow rate. For carbon dioxide reforming, H2 was decreased with the increase of the CO2 flow rate, but CO and CO2 gradually increased. For reforming with the nickel catalyst, the amount of H2 produced was slightly larger than without catalyst addition in the reactor, while the CO and CO2 contents were lower, due to the increase of residence time and adsorption.

Cell Sheet Detachment from Poly(N-vinylcaprolactam-co-N-isopropylacrylamide) Grafted onto Tissue Culture Polystyrene Dishes

human fibroblast; poly(N-isopropylacrylamide); poly(N-vinylcaprolactam); hydration; cell detachment; cell culture

Fabrication of functional tissue constructs using sandwiched layers of cultured cells could prove to be an attractive approach to tissue engineering. Rapid detachment of cultured cell sheets is a very important recovery method that permits facile manipulation of the sheet and prevents functional damage. To induce hydrophilic and hydrophobic structural changes on the required culture substrate in response to a culture temperature alteration, poly(N-vinylcaprolactam-co-N-isopropylacrylamide) (PNVCL-co-PNIPAAm) was grafted onto tissue culture polystyrene (TCPS) dishes through electron beam irradiation. Chemical analyses using ATR-FTIR spectroscopy revealed that PNVCL-co-PNIPAAm was successfully grafted onto the surfaces of the TCPS dishes. The TCPS dishes grafted with PNVCL-co-PNIPAAm were utilized for the cell sheet detachment experiments. Approximately 150 min was required to detach most of the cell sheets from the PNVCL- co-PNIPAAm-grafted TCPS surfaces.

회전체를 부착한 수평형 로타리킬른 건조로의 설계 및 최적 운전조건 연구

sludge disposal technology; sewage sludge; dry process; rotary kiln; dried sludge

Sludge disposal technology has been studied with many researchers since disposal of sewage sludge has been a social problem. The current technologies include incineration, carbonization, pyrolysis, landfilling and fertilization. However, all of these processes require a dry process, because sewage sludge with more than 80% high water content is difficult to be used as a raw material. This study has the purpose to establish the optimal operation conditions and the technology as changing the variables: kiln residence time, sludge load, dryer temperature, by using the previous study that is rotary kiln type dryer designed as a numerical simulation study. As the results, optimum conditions are determined as follows: kiln residence time, sludge load, dryer temperature are 62.5 kg/m3.hr, 26.2 min, 330 ℃, respectively. Content of water, drying efficiency, weight loss, volume loss show that the results are 10 ± 2, 88, 80, 60%, and the dried sludge is released by a dryer below 10 mm.

유전자 전달체로서 히스티딘이 결합된 저분자량 수용성 키토산의 제조와 특성

LMWSC; histidine; nanoparticle; gene therapy

To improve transfection efficiency, we prepared histidine-low molecular weight water-soluble chitosan (LMWSC) having the potential to form complex with DNA as a cationic polymer. Histidine-LMWSC was synthesized by the esterification reaction and removing phthaloyl group. The histidine-LMWSC was characterized using FT-IR, 1H NMR spectra. Histidine-LMWSC was complexed with plasmid DNA (pDNA) in various polymer/DNA (N/P) weight ratios, and the complex was identified using gel retardation assay. The particle sizes of the hisitidine-LMWSC/DNA complexes were measured on a DLS instrument by fixing the histidine-LMWSC/DNA weight ratio of 10/1. Owing to the utilization of a large excess amount of cationic LMWSC against anionic DNA, the particle size of histidine-LMWSC/DNA complexes was in the range of 100∼200 nm. Therefore, histidine-LMWSC will be useful in the development of gene carriers.

Polyaniline/Polyimide 혼합막의 기체 분리 특성

gas separation; polyaniline; polyimide; doping; permselectivity

Polyaniline (PANI)/Polyimide (PI) membranes were prepared and the effects of PANI contents and doping on the structural properties and gas separation properties were studied. The polyamic acid (PAA) solution was prepared by the polycondensation reaction of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 4,4'-oxydianiline (ODA) in 1-methyl-2-pyrrolydinone (NMP) solvent. The PANI/PI blends were obtained by mixing PAA solution and PANI solution, and were doped with 1 M aqueous HCl solution for 24 h. The structural characterizations of the as-cast and doped membranes were examined by FT-IR, XRD, and TGA. The gas permeation experiments with H2, CO2, O2, N2, and CH4 were carried out by variable pressure method at 30 ℃ and 5 atm. For all gases tested, the permeability coefficients of the blends decreased with increasing PANI content and the magnitude of permeability was in the order of H2 > CO2 > O2 > N2 > CH4. The permeability for PANI/PI membranes decreased after the doping process while the permselectivity increased. For H2/CH4 separation, the doped PANI/PI (75/25) membrane has a permselectivity of 991.

산처리된 페이스트로 제조한 나노 구조체 TiO2 전극이 염료감응형 태양전지의 효율에 미치는 영향

dye-sensitized solar cells; TiO2; acid treatment; photoelectrode; I-V curves

Recently, dye sensitized solar cells (DSSCs) composed of nanoporous TiO2, light-sensitive dyes, electrolytes, and counter electrode have been received much attention. Nanostructured particles with higher surface area for the higher adsorption of Ru (II) dye are required to increase the quantity of light absorption. Also, it has been reported that the key factor to achieve high energy conversion efficiency in the photoelectrode of DSSC is the heat treatment of TiO2 paste with acid addition. In this work, we investigated the influence of acid treatment of TiO2 solar cell on the photovoltaic performance of DSSC. The working electrodes fabricated in this work were characterized by X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), field emission scanning electron microscope (FE-SEM), and atomic force microscope (AFM). In addition, the influence of nanostructured photoelectrode fabricated with the acid-treated paste on the energy conversion efficiency was investigated on the basis of photocurrent-potential curves. It was found that the influence of acid-treated paste on the photovoltaic efficiency was significant.

내부순환식 기포탑 반응기 상에서 MEA (monoethanolamine) 용액에 의한 이산화탄소 분리 및 메탄회수

carbon dioxide; methane; autocirculation bubble lift column reactor; gas purification; MEA (monoethanolamine)

For the simultaneous methane recovery and CO2-stripping, we have been developed dual vent auto circulation bubble lift column reactor, and evaluate optimum conditions for monoethanolamine (MEA) solutions as a CO2 absorbent. At the 5 wt% MEA solution, we investigated the pH change during CO2-stripping and absorption reaction, CO2-stripping rate with reaction time, methane recovery efficiency for various inflow rates of air, CO2-stripping rate for flow liquid over flow height, and CO2-stripping dependency on the temperature of absolvent solutions. The suggested optimum conditions for CO2 recovery with MEA in the dual vent auto circulation bubble lift column reactor were 40 mm over flow liquid height, 1.5 L/min of air inflow rate, and 25 ℃ of absorbent solution temperature.

고분자 전해질 연료전지용 플라즈마 개질 시스템에서 수소 생산 및 CO 산화반응에 관한 연구

Non-Thermal Plasma; Hydrogen; Reforming; Methane; Shift Reactor

Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as H2 supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). H2 selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the O2/C ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was 672 ℃ and input power 1.1 kJ/L, the production of H2 was maximized 41.1%. And CH4 conversion rate, H2 yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the O2/C ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, 235 ℃ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were H2 38%, CO<10 ppm, N2 36%, CO2 21% and CH4 4%.

Preparation and Characterization of Nanoparticles Using Poly(N-isopropylacrylamide)-Poly(ε-caprolactone) and Poly(ethylene glycol)-Poly(ε-caprolactone) Block Copolymers with Thermosensitive Function

nanoparticles; thermosensitive; PCL; PNiPAAm; PEG; drug delivery

Thermosensitive nanoparticles were prepared via the self-assembly of two different poly(ε-caprolactone)-based block copolymers of poly(N-isopropylacrylamide)-b-poly(ε-caprolactone) (PNPCL) and poly(ethylene glycol)-b-poly(ε-caprolactone) (PEGCL). The self-aggregation and thermosensitive behaviors of the mixed nanoparticles were investigated using 1H-NMR, turbidimetry, differential scanning microcalorimetry (micro-DSC), dynamic light scattering (DLS), and fluorescence spectroscopy. The copolymer mixtures (mixed nanoparticles, M1-M5, with different PNPCL content) formed nano-sized self-aggregates in an aqueous environment via the intra- and/or intermolecular association of hydrophobic PCL chains. The microscopic investigation of the mixed nanoparticles showed that the critical aggregation concentration (cac), the partition equilibrium constants (Kv) of pyrene, and the aggregation number of PCL chains per one hydrophobic microdomain varied in accordance with the compositions of the mixed nanoparticles. Furthermore, the PNPCL harboring mixed nanoparticles evidenced phase transition behavior, originated by coil to the globule transition of PNiPAAm block upon heating, thereby resulting in the turbidity change, endothermic heat exchange, and particle size reduction upon heating. The drug release tests showed that the formation of the thermosensitive hydrogel layer enhanced the sustained drug release patterns by functioning as an additional diffusion barrier.

Biotin-Conjugated Block Copolymeric Nanoparticles as Tumor-Targeted Drug Delivery Systems

nanoparticle; drug delivery; targeting; polyethylene oxide; polycaprolactone

To achieve targeted drug delivery for chemotherapy, a ligand-mediated nanoparticulate drug carrier was designed, which could identify a specific receptor on the surfaces of tumor cells. Biodegradable poly(ethylene oxide)/poly(ε-caprolactone) (PEG/PCL) amphiphilic block copolymers coupled to biotin ligands were synthesized with a variety of PEG/PCL compositions. Block copolymeric nanoparticles harboring the anticancer drug paclitaxel were prepared via micelle formation in aqueous solution. The size of the biotin-conjugated PEG/PCL nanoparticles was determined by light scattering measurements to be 88-118 nm, depending on the molecular weight of the block copolymer, and remained less than 120 nm even after paclitaxel loading. From an in vitro release study, biotin-conjugated PEG/PCL nanoparticles containing paclitaxel evidenced sustained release profiles of the drug with no initial burst effect. The biotin-conjugated PEG/PCL block copolymer itself evidenced no significant adverse effects on cell viability at 0.005-1.0 μg/mL of nanoparticle suspension regardless of cell type (normal human fibroblasts and HeLa cells). However, biotin-conjugated PEG/PCL harboring paclitaxel evidenced a much higher cytotoxicity for cancer cells than was observed in the PEG/PCL nanoparticles without the biotin group. These results showed that the biotinconjugated nanoparticles could improve the selective delivery of paclitaxel into cancer cells via interactions with overexpressed biotin receptors on the surfaces of cancer cells.

Gas Separation of Pyrolyzed Polymeric Membranes: Effect of Polymer Precursor and Pyrolysis Conditions

gas separation; polyimide; phenolic resin; polyacrylonitrile; cellulose acetate; pyrolized membrane

In this study, five representative, commercially available polymers, Ultem 1000 polyetherimide, Kapton polyimide, phenolic resin, polyacrylonitrile and cellulose acetate, were used to prepare pyrolyzed polymer membranes coated on a porous -alumina tube via inert pyrolysis for gas separation. Pyrolysis conditions (i.e., final temperature and thermal dwell time) of each polymer were determined using a thermogravimetric method coupled with real-time mass spectroscopy. The surface area and pore size distribution of the pyrolyzed materials derived from the polymers were estimated from the nitrogen adsorption/desorption isotherms. Pyrolyzed membranes from polymer precursors exhibited type I sorption behavior except cellulose acetate (type IV). The gas permeation of the carbon/ -alumina tubular membranes was characterized using four gases: helium, carbon dioxide, oxygen and nitrogen. The polyetherimide, polyimide, and phenolic resin pyrolyzed polymer membranes showed typical molecular sieving gas permeation behavior, while membranes from polyacrylonitrile and cellulose acetate exhibited intermediate behavior between Knudsen diffusion and molecular sieving. Pyrolyzed membranes with molecular sieving behavior (e.g., polyetherimide, polyimide, and phenolic resin) had a CO2/N2 selectivity of greater than 15; however, the membranes from polyacrylonitrile and cellulose acetate with intermediate gas transport behavior had a selectivity slightly greater than unity due to their large pore size.

저분자량 수용성 키토산이 분급화된 유전자 전달체의 제조 및 특성

low molecular-weight water soluble chitosan(LMWSC); chitosan oligosaccharides(COS); gene carrier; transfection

To obtain low molecular weight water soluble chitosan (LMWSC) with various molecular weights, chitosan oligosaccharides (COS) with lactic acid was separated by using ultrafilteration technique and LMWSC with a free amine group was prepared by the novel salts-removal method. The characterization of LMWSC removed the lactic acid and degree of deacetylation (DDA) were identified by FT-IR and 1H-NMR spectra. Polydispersity index (PDI) was 1.278∼1.499, which indicates a relatively molecular weight distribution. To identify the potential as a gene carrier, we confirmed the transfection efficiency of COS fractioned according to molecular weight successfully and the salt-removed LMWSC using 293T cell. Also, LMWSC derivatives prepared for improvement transfection efficiency were evaluated using Balb/C mice.

효과적인 유전자전달을 위한 표적성 리간드가 도입된 저분자량 수용성 키토산 나노입자의 제조 및 특성

LMWSC; folic acid; nanoparticle; gene therapy

Gene therapy using low molecular weight water soluble chitosan (LMWSC) as polycationic polymer shows good biocompatibility, but low transfection efficiency. The mechanism of folic acid (FA) uptake in the cells to promote targeting and internalization could improve transfection rates. The objective of this study was to synthesize and characterize the WSCFA-DNA complex and evaluate their cytotoxicity, in vitro. In 1H-NMR spectra, specific peaks appeared both of FA and LMWSC in D2O. WSCFA nanoparticles have spherical shapes with particle size show below 110 nm. In the cell cytotoxicity test, the WSCFA-DNA complex showed high cell viability, in vitro. Gel electrophoresis showed condensed DNA within the carriers. In vitro transfection efficiency was assayed by fluorescence spectroscopy. WSCFA nanoparticles have less cytotoxicity, good DNA condensation and particle size around 110 nm, which makes them a promising candidate as a non-viral gene vector.

Effect of PAC Addition on Dyeing Wastewater Treatment in a Hybrid Process of Fenton Oxidation and Membrane Separation

ultrafiltration; permeability; Fenton oxidation; dyeing wastewater

This study aimed at improving the treatment efficiency of dyeing wastewater using a hybrid process of Fenton oxidation and membrane separation. The supernatant after pre-treatment through Fenton oxidation of dyeing wastewater was fed to the ultra-filtration (UF) membrane separation system. In the Fenton oxidation process, the chemical oxygen demand (COD) removal efficiency was the highest at pH 3. To minimize membrane clogging of the UF membrane module, powdered activated carbon (PAC) was added to the pre-treated supernatant. The effect of PAC addition on the permeate flux and treatment efficiency of the membrane separation process was investigated. When PAC was added to the supernatant after pre-treatment through Fenton oxidation, the COD removal efficiency was 80.22 %. In the membrane separation process, the COD removal efficiency was 94.93 % when PAC was not added and 98.48 % when it was added. The permeate flux in the presence of PAC decreased more rapidly than it did in the absence of PAC, but the recovery of permeability from cleaning was relatively higher.

Hydrogen-rich Gas Production from Propane using Plasma-assisted Reforming

non-thermal plasma; propane reforming; gliding arc; synthesis gas; hydrogen-rich gas production

The reforming characteristics and optimal operating condition for syngas (synthesis gas) production were studied by using gliding arc plasma with a catalytic reactor. Parametric screening studies were undertaken for variations of the following variables: vapor flow ratio, CO2 flow ratio, reactant flow rate, and input electric power. When these variables were 0.65, 0.14, 14 L/min, and 1.37 kW, respectively, the production of hydrogen-rich gas was maximized with an optimal propane conversion rate of 62.6 %. Under these optimal conditions, the following syngas concentrations were determined: H2, 44.4 %; CO, 18.2 %; CH4, 11.2 %; C2H2, 2.7 %; C3H6, 1.9 %; C2H4, 0.6 %; and C3H4, 0.4 %. The carbon dioxide conversion rate was 29.2 % and the H2/CO ratio was 2.4.

Effect of Electron BeamIrradiation on Poly(vinylidene fluoride) Films at the Melting Temperature

PVDF film; electron beam irradiation; crosslinking; mechanical properties; X-ray diffraction

The radiation-induced changes taking place in poly(vinylidene fluoride) (PVDF) films exposed to electron beam irradiation were investigated in correlation with the applied doses. Films were irradiated in air at the melting temperature (174 °C) using a universal electron beam accelerator at doses in the range 50 200 kGy. Various properties of the melt-irradiated PVDF films were studied using ATR-FTIR spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction and scattering, and universal mechanical testing. The unirradiated PVDF film was used as a reference. Electron beam irradiation at the melting temperature induced changes in the physical, chemical, thermal, structural, and mechanical properties of the PVDF films; such changes varied depending on the irradiation dose.

WastewaterTreatment by Anaerobic Digestion Coupled with Membrane Processing

anaerobic digester; crossflow; ultrafiltration; membrane

Treatment of starch waste by an anaerobic digester-membrane system was studied. The starch waste was immersed into a hollow fiber membrane unit, of area 0.17 m2, with themembrane pore size varying from 0.03 to 0.15 μm. The hydraulic retention time (HRT) of the anaerobic digester ranged from 1.5 to 10 days and this variation had a significant effect on the treatment efficiency; in contrast, whereas the membrane size had no significant effect. The gas production was ca. 0.74 m3/kg chemical oxygen demand (COD) treated. The COD removal efficiency was ca. 80∼ 95 %, depending on the HRT. The effluent from the anaerobic filter, having a total COD in the range 4500 ∼ 5200 mg/L, was treated by crossflow ultrafiltration (UF) units. Experiments performed with different membrane pore sizes indicated that a membrane with a molecular weight cut-off (MWCO) size of 10⁶ showed a higher COD removal efficiency in the range of 83∼ 87 %, while maintaining a steady flux of 120 130 L/m2h. The scope of this study scope was also expanded to investigate the long term clogging effect of the membrane.

Hydroxypropyl-β-cyclodextrin Inclusion Complexes for Transdermal Delivery: Preparation, Inclusion Properties, Stability, and Release Behavior

hydroxypropyl-β-cyclodextrin; β-cyclodextrin; water solubility; vitamin; inclusion complex

Hydroxypropyl-β-cyclodextrin (HPCD), a highly water-soluble derivative, was synthesized by the substitution of the hydroxyl groups in the glucopyranose units of β-cyclodextrin (β-CD) with hydroxypropyl groups to improve its solubility in aqueous solution and its biocompatibility. β-CD has only limited water solubility (~1.8 g/mL at ambient temperature), whereas HPCD showed high water solubility and also dissolved in solvents such as methanol, ethanol, DMF, and DMSO. To investigate their feasibility for transdermal delivery applications, HPCD inclusion complexes containing several lipophilic guest molecules (retinol, tocopherol, and genistein) were prepared through complex formation by taking advantage of the special molecular structure of HPCD, which has a hydrophobic interior cavity and a hydrophilic exterior. The molar inclusion efficiency of guest molecules within HPCD was ca. 8~12 % when the feed molar ratio of guest molecules to CD was 1. The inclusion efficiency was influenced by the feed molar ratio and by the type of guest molecule. The stabilities of the inclusion complexes were investigated with respect to the temperature, pH, and solvent. HPCD complexes exhibited enhanced stability in comparison with those of the parent β-CD. From an in vitro skin permeation study using a Frantz diffusion cells, ca. 70~90 % permeation of guest molecules was observed within 7 days.

폐수의 고도처리를 위한 무산소/호기형 분리막생물반응조 - 역삼투 공정과 활성슬러지공정 - 정밀여과 - 역삼투 공정의 비교

membrane bioreactor; microfiltration; reverse osmosis

A membrane bioreactor (MBR) is an effective tool for wastewater treatment with recycling. MBR process has several advantages over conventional activated sludge process (ASP); reliability, compactness, and quality of treated water. The resulting high-quality and disinfected effluents suggest that MBR process can be suitable for the reused and recycling of wastewater. An anoxic/oxic (A/O) type MBR was applied to simultaneous removal of organics and nutrients in sewage. At first, the efficiency of submerged MBR process was investigated using a hollow fiber microfiltration membrane with a constant flux of 10.2 L/m2；h at each solids retention time (SRT). Results showed that protein/carbohydrate (P/C) ratio increased and total extracellular polymeric substances (EPS) remained constant with SRT increased. Secondly, A/O type MBR with a reverse osmosis (RO) membrane was employed to treat the municipal wastewater. The performance of A/O type MBR-RO process is better for the treatment of organics and nutrients than ASP-MF-RO process in terms of consistent effluents quality.

황련유래 단백질이 함유된 나노리포좀의 제조 및 특성

coptidis rhizoma; candida albicans; liposome; surface coating

Coptidis Rhizoma, an antimicrobial agent from natural source, is known to have the antiviral effect on the Candida albicans that causes the infectious dermatitis. The valuable protein was extracted from the Coptidis Rhizoma, To prevent denaturalization from external stimulus and improve adsorption onto the skin, the nano-sized liposomes were prepared as a carrier. The CPR-containing liposomes showed an average diameter of 187 nm, surface charge of 3.337 mV and 33% encapsulation efficiencyl. Therelease behavior of CRP from the liposome was investigated with various temperature and releasing time. The PVA solution was coated on the surface of liposome to improve the stability. The coated liposome showed slow release behavior in comparison with the non-coated liposome. The CRP in the liposome maintained the effect on the Candida albicans after treating it at 50 and with ultraviolet for 24 h.

플라즈마트론을 이용한 바이오가스 개질로부터 수소생산

Biogas; Plasmatron; Thermal Plasma; SynGas; Hydrogen Production

The purpose of this paper is to investigate the optimal operating condition for the hydrogen production by biogas reforming using the plasmatron induced thermal plasma. The component ratio of biogas(CH4/CO2) produced by anaerobic digestion reactor were 1.03, 1.28, 2.12, respectively. And the reforming experiment was performed. To improve hydrogen production and methane conversion rates, parametric screening studies were conducted, in which there are the variations of biogas flow ratio(biogas/TFR: total flow rate), vapor flow ratio(H2O/TFR: total flow rate) and input power. When the variations of biogas flow ratio, vapor flow ratio and input power were 0.32~0.37, 0.36~0.42, and 8 kW, respectively, the methance conversion reached its optimal operating condition, or 81.3~89.6％. Under the condition mentioned above, the wet basis concentrations of the synthetic gas were H2 27.11~40.23％, CO 14.31~18.61％. The hydrogen yield and the conversion rate of energy were 40.6~61％, 30.5~54.4％, respectively, the ratio of hydrogen to carbon monoxide(H2/CO) was 1.89~2.16.

On the modeling of electro-hydrodynamic flow in a wire-plate electrostatic precipitator

EHD; ESP; Chen-Kim Model; Modeling; Von-Karman Vortex

Modeling of the flow velocity fields for the electrohydrodynamic (EHD) flow in a wire-to-plate type electrostatic precipitator (ESP) was achieved. Solutions of the steady, two-dimensional Navier-Stokes equations have been computed. The equations were solved in the conservative finite-difference form on a fine uniform rectilinear grid of sufficient resolution to accurately capture the momentum boundary layers. The numerical procedure for differential equations was used by SIMPLEST [Michel, 2002], a derivative of Patankar’s SIMPLE algorithm, to bring rapid convergence. The Phoenics (Version 3.5.1) CFD code, coupled with Poisson’s and ion transport equations and electric body force in the momentum equation, developed in this study, was used for the numerical simulation. From calculations for the flow employing different flow models, the Chen-Kim k.ε turbulent model appeared to be the most appropriate choice to obtain a quantitative image of the resulting mean flow field and downstream wake flow of the rear wire, although this was obtained from a qualitative analysis due to the lack of experimental verification. The flow velocity field pattern showed a strong EHD secondary flow, which was clearly visible in the downstream regions of the corona wire despite the low Reynolds number for the electrode (ReCW=12.4). Secondary flow vortices were also caused by the EHD with increases in the discharge current.

Backflushing, pulsation and in-line flocculation techniques for flux improvement in crossflow microfiltration

Microfiltration; Backflushing; Pulsation; In-line Flocculation; Permeate Flux

Crossflow microfiltration (CFMF) is a better technique for removal of particles from water suspension. Clogging is the main drawback of membrane application, which causes a drop in permeate flux. Numerous techniques are available for flux improvement. In this work, three such techniques backflushing, pulsation and in-line flocculation, are reviewed. Two experimental studies have been analyzed and compared. In both techniques, better flux was reported with cleaning frequency of 1min. This shows that a longer interval causes increased internal clogging and deposition. However for the backflushing case, longer duration of backflushing produced higher flux improvement, while pulsating performed inconsistently with stop duration. Net permeate volume was observed higher in both experiments when Tf=1min, Tb=1 sec and Tf=1 min, Ts=1 sec. This is due to higher flux at Tf=1min and longer net operation time. Comparing the flux improvement in both techniques without flocculent addition, backflushing produced 200% increment at Tf=1 min and Tb=5 sec. This was 63% at Tf=1min and Ts=1 sec with pulsating. Flux increment was 162% with backflushing at Tf=1 min and Tb=1 sec.

Surface Modification of Magnetites Using Maltotrionic Acid and Folic Acid for Molecular Imaging

magnetite nanoparticles; maltotrionic acid; folic acid; intracellular uptake; particle internalization

Highly hydrophilic, uniform, superparamagnetic and nontoxic maltotrionic acid (MA)-coated magnetite nano-particles (MAM) were prepared and characterized by TEM, DLS, XRD and VSM. MA was used to improve the biocompatibility, monodispersity and non-specific intracellular uptake of nanoparticles. Folic acid (FA) was subsequently conjugated to the MAM to preferentially target KB cells (cancer cells) that have folate receptors expressed on their surfaces and to facilitate nanoparticles in their transit across the cell membrane. Finally, fluorescence isothiocyanate (FITC) was added to the nanoparticles to visualize the nanoparticle internalization into KB cells. After the cells were cultured in a media containing the MAM and MAM-folate conjugate (FAMAM), the results of fluorescence and confocal microscopy showed that both types of nanoparticles were internalized into the cells. Nevertheless, the amount of FAMAM uptake was higher than that of MAM. This result indicated that nanoparticles modified with MA and FA could be used to facilitate the nanoparticle uptake to specific KB cells (cancer cells) for molecular imaging.

Novel Sulfonated Poly(arylene ether ketone) Containing Benzoxazole Membranes for Proton Exchange Membrane Fuel Cell

fuel cell; membrane; poly(aryl ether ketone); polybenzoxazole; sulfonation

Novel sulfonated poly(aryl ether ketones) containing benzoxazole were directly synthesized by aromatic nucleophilic polycondensation using various ratios of 2,2'-bi[2-(4-flurophenyl)benzoxazol-6-yl]hexafluoropropane to sodium 5,5'-carbonylbis(2-fluorobenzenesulfonate). The copolymers were soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide at a relatively high solid composition (>15 wt%) and formed tough, flexible and transparent membranes. The membranes exhibited a degradation temperature of above 290 °C. The exact dissolution times of these membranes at 80 °C in Fenton’s reagent (3 wt% H2O2 containing 2 ppm FeSO4) were undetectable, confirming their excellent chemical stability in fuel cell application. The membranes showed a moderate increase in water uptake with respect to increasing temperature. The proton conductivities of the membranes were dependent on the composition and ranged from 1.10× 10-2 to 5.50×10-2 Scm-1 at 80 °C and 95% relative humidity (RH). At 120 °C without externally humidified conditions, the conductivities increased above 10-2 Scm-1 with respect to increasing benzoxazole content, which suggested that the benzoxazole moieties contributed to the proton conduction.

All-trans Retinoic Acid-Associated Low Molecular Weight Water-Soluble Chitosan Nanoparticles Based on Ion Complex

low molecular weight water-soluble chitosan; all-trans retinoic acid; polyion complex; nanoparticles; anticancer drug

The purpose of this study is to develop novel nanoparticles based on polyion complex formation between low molecular weight water-soluble chitosan (LMWSC) and all-trans retinoic acid (atRA). LMWSC nanoparticles encapsulating atRA based on polyion complex were prepared by mixing of atRA into LMWSC aqueous solution using ultrasonication. In FTIR spectra, the carbonyl group of atRA at 1690 cm-1 disappeared or decreased when ion complexes were formed between LMWSC and atRA. In 1H NMR spectra, specific peaks of atRA disappeared when atRA-encapsulated LMWSC (RAC) nanoparticles were reconstituted into D2O while specific peaks both of atRA and LMWSC appeared in D2O/DMSO (1/3, v/v) mixture. XRD patterns also showed that the crystal peaks of atRA were disappeared by encapsulation into LMWSC nanoparticles. LMWSC nanoparticles encapsulating atRA have spherical shapes with particle size below 200 nm. The mechanism of encapsulation of atRA into LMWSC nanoparticles was thought to be an ion complex formation between LMWSC and atRA. LMWSC nanoparticles showed high atRA loading efficiency over 90% (w/w). AtRA was continuously released from nanoparticles over 10 days. In in vitro cell cytotoxicity test, free atRA showed higher cytotoxic effect against CT 26 colon carcinoma cell line on 1 day. However, RAC nanoparticles showed similar cytotoxicity against CT 26 cells on 2 day. These results suggest the potential for the introduction of LMWSC nanoparticles into various biomedical fields such as drug delivery.

Preparation of Thermo-Responsive and Injectable Hydrogels Based on Hyaluronic Acid and Poly(N-isopropylacrylamide) and Their Drug Release Behaviors

hyaluronic acid; poly(N-isopropylacrylamide); injectable gel; drug delivery

Copolymers composed of hyaluronic acid (HA) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to create temperature-sensitive injectable gels for use in controlled drug delivery applications. Semi-telechelic PNIPAAm, with amino groups at the end of each main chain, was synthesized by radical polymerization using 2-aminoethanethiol hydrochloride (AESH) as the chain transfer agent, and was then grafted onto the carboxyl groups of HA using carbodiimide chemistry. The result of the thermo-optical analysis revealed that the phase transition of the PNIPAAm-grafted HA solution occurred at around 30~33 ℃. As the graft yield of PNIPAAm onto the HA backbone increased, the HA-g-PNIPAAm copolymer solution exhibited sharper phase transition. The short chain PNIPAAm-grafted HA (Mw =6,100) showed a narrower temperature range for optical turbidity changes than the long chain PNIPAAm-grafted HA (Mw= 13,100). PNIPAAm-grafted HA exhibited an increase in viscosity above 35 ℃, thus allowing the gels to maintain their shape for 24 h after in vivo administration. From the in vitro riboflavin release study, the HA-g-PNIPAAm gel showed a more sustained release behavior when the grafting yield of PNIPAAm onto the HA backbone was increased. In addition, BSA released from the PNIPAAm-g-HA gels showed a maximum concentration in the blood 12 h after being injected into the dorsal surface of a rabbit, followed by a sustained release profile after 60 h.

주사슬에 곁사슬기를 갖는 폴리히드록시아미드의 물성 및 난연특성

poly(hydroxyamide)s; poly(benzoxazole)s; thermal cyclization reaction; activation energy; heat release rate

Physical properties and flammability of polyhydroxyamides (PHAs) having poly(ethyleneglycol)methyl ether (MPEG) and/or dimethylphenoxy pendants were studied by using DSC, TGA, FTIR, pyrolysis combustion flow calorimeter(PCFC), and X-ray diffractometer. The degradation temperatures of the polymers were recorded in the ranges of 276~397 ℃ in air. PCFC results showed that the heat release (HR) capacity and total heat release (total HR) values of the PHAs were increased with increasing molecular weight of MPEG. In case of M-PHA 2 annealed at 290 ℃, the values of HR capacity were siginificantly decreased from 253 to 42 J/gK, and 60% weight loss temperatures increased from 408 to 856 ℃ with an annealing temperature. The activation energy for the decomposition reaction of the PHAs showed in the range of 129.3∼235.1 KJ/mol, which increased with increasing conversion. Tensile modulus of PHAs were decreased as increasing chain of MPEG, and showed an increase more than initial modulus after converted to PBOs.

티타니아 솔로 코팅된 폴리프로필렌 필터의 특성

polypropylene filter; titanium dioxide; titania sol

In this study, we coated the polypropylene filter with titania sol and investigated various characteristic such as its deodorization efficiency and sterilization effect of gram negative bacillus Escherichia coli (ATCC 25922) and gram positive bacillus Staphylococcus aureus (ATCC 6538). As the results, in case of titania sol coated polypropylene filter, the deodorization rate of ammonia, trimethylamin and acetic acid which cause indoor air pollution was 66%, 90% and 16% respectively. Also, the sterilization rate of gram negative bacillus Escherichia coli (ATCC 25922) and gram positive bacillus Staphylococcus aureus (ATCC 6538) was 99.9% after 24 hours.

저분자량 수용성 키토산을 이용한 동맥 벽 표적성 유전자 전달체의 합성

low molecular water-soluble chitosan(LMWSC); artery wall binding peptide(AWBP); N- hydroxysuccinimide polyethylene glycol vinylsulfone(NHS-PEG-VS); non-viral vector

Non-viral gene carriers continue to attract a great deal of interest due to advantageous safety profile. Among the non-viral gene carriers, cationic liposomes or synthetic gene carriers are efficient DNA carriers in vitro, but their in vivo applications are greatly hampered because of low biocompatibility. On the other hand, chitosan, a natural cationic polysaccharide, is a candidate non-viral vector for gene delivery because of its low cytotoxicity and high positive charges. In this work, targeted gene carrier was synthesized to target artery wall cells using low molecular water-soluble chitosan (LMWSC). The molecular weight(Mw) and degree of deacetylation(DDA) of LMWSC were measured by relative viscometer and Kina titration, respectively. The structure of LMWSC was analyzed by measuring FTIR, 1H-NMR, and 13C-NMR. AWBP-PEG-g-LMWSC was synthesized by conjugation of the artery wall binding peptide(AWBP), a specific targeting peptide, to the end of pegylated LMWSC as a gene carrier to target artery wall cells. The synthesized AWBP-PEG-g-LMWSC were analyzed by measuring FTIR, 1H-NMR, zeta-potentiometer, and atomic force microscopy(AFM).

Filtration Performance of Submerged Membrane in a Membrane Coupled Fixed Phase Biofilm Reactor

submerged membrane; nutrients removal; support carrier; biofilm

This research was carried out a membrane coupled fixed phase biofilm reactor (M-CFPBR) process using a waste lime support carrier to minimize membrane fouling of the membrane bioreactor (MBR) and to improve the removal efficiency of nitrogen and phosphorus in wastewater. Waste lime was pretreated and used as a material for a bead-type support carrier having a rough surface and large pore structure. In this work, we investigated the filtration characteristics of the submerged membrane and the removal efficiency of nutrients according to changes in air flow rate and support carrier volume fraction in the M-CFPBR process using a waste lime support carrier. The filtration time of the membrane increased with increasing the air flow rate under the same support carrier volume fraction. Under the condition that air flow rate was the same, filtration time increased, as the support carrier volume fraction was increased. The change of trans membrane pressure (TMP) with time reached 30 kPa within 160 h when the support carrier was not packed. However, as the support carrier volume fraction was increased from 10 % to 20 % and 30 %, the filtration time of the membrane was extended from 160 h to 280 h and 500 h respectively. The nitrogen removal efficiency was improved because the effective mixed liquor suspended solids (MLSS) concentration and effective solid retention time (SRT) increased within MBR as the support carrier volume fraction increased. Phosphorous removal efficiency was below maintained 10% when the support carrier was not packed, but when the support carrier was packed 10 %, 20 %, and 30 %, it increased 72 %, 85 %, and 89 % respectively. Therefore, the M-CFPBR process minimizes membrane fouling, thereby improving the filtration time and the wastewater treatment efficiency.

Production of Heterologous Protein from Pichia pasteris by Air Lift Bioreactor

Pichia pastoris; Saccharomyces cerevisiae; mouse α-amylase; heterologous protein; air lift bioreactor

For high-level expression of heterologous protein using a methylotrophic yeast, P. pastoris, in an air lift bioreactor, the initial methanol concentration and inoculation time were investigated. When 30 g/L of methanol was used, α-amylase activity was highest (235 U/mL). When the inoculation was carried out at 18 hr of culture, the maximum α-amylase activity was obtained (270 U/mL) and the consumed methanol concentration was 24.8 g/L. The α-amylase activity expressed in P. pasteris was stable up to 50℃ and showed 86.4% of residual activity at 60℃. However, in the case of S. cerevisiae, it remained only 57.3% under the same conditions. Between pH 6 and 7, the mouse α-amylase activity expressed in P. pasteris was stable. However, in the case of S. cerevisiae, it was stable between pH 7 and 8. Using the optimum culture conditions, the fed cultures were carried out for 4 days. The methanol consumption increased upon culture time up to 3 days, but after 4 days it began to decrease. The cell concentration was similar to that of S. cerevisiae. The maximum α-amylase activity was 610 U/mL at 4 days of culture; this value was about 6.0-fold higher than that of S. cerevisiae. In the case of product yield from methanol, it was 15.2 U/mL/g the consumed carbon source, which was about 11.5-fold higher than that of S. cerevisiae using glucose.

저밀도 폴리에틸렌 나노복합재료의 제조 및 특성

LDPE; organo-clay; polymer nanocomposite; flame retardancy

In this study, low density polyethylene/organo-clay nanocomposites were prepared by melt blending. Thermal property, structure, and morphology of the LDPE/organo-clay nanocomposites were investigated. When the composition ratios of the compounds of LDPE/PE-g-MA/organo-clay were 90/10/1~10 (w/w/w), X-ray diffractograms of LDPE/organo-clay nanocomposites revealed that the intercalation of polymer chains lead to increase the spacing between clay layers. TEM microphotographs showed that LDPE was intercalated into organo-clay. TGA performed under air atmosphere demonstrated a great increase in thermal stability of the LDPE/organo-clay nanocomposties. The maximum decomposition temperature of LDPE/organo-clay nanocomposite was increased about 80 ℃ compared with pure LDPE. When the organoclay contents were 1.0~5.0 wt%, the LOI values were increased with increasing the organo-clay content, but in the case of the contents more than 5.0 wt%, the LOI values were not increased any more.

Hydroxypropyl-β-cyclodextrin 포접복합체 제조를 위한 초임계유체 공정 연구

Itraconazole; Cyclodextrin; Inclusion Complex; Supercritical Fluid; Anti-Solvent

In this work, solid-state inclusion complex powders of itraconazole and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) were produced by a supercritical anti-solvent (SAS) process. In order to evaluate the degree of complexation, the thermal behavior of the microparticulate complexes was investigated using differential scanning calorimetry. The experimental results obtained for the solubility and dissolution rate of the microparticulate inclusion complexes in a buffer solution of pH 1.2 showed that the complexation of itraconazole with HP-β-CD results in a significant increase in the solubility and dissolution rate of itraconazole. The particle size of the SAS-produced inclusion complexes was dramatically reduced (<0.1-0.5 μm) compared with untreated itraconazole (30-50 μm) and HP-β-CD (50-100 μm). The solubility of itraconazole was increased with the increase of pressure at a constant temperature to ca. 758.6 μg/mL in an aqueous medium of pH 1.2. The dissolution rate of itraconazole was observed to be significantly improved and about 90% of itraconazole was found to be dissolved within 5-10 min.

Preparation of Ion Exchange Membranes for Fuel Cell Based on Crosslinked Poly(vinyl alcohol) with Poly(acrylic acid-co-maleic acid)

ionomeric membranes; proton conductivity; methanol permeability; crosslinked poly(vinyl alcohol) membranes; poly(acrylic acid-co-maleic acid); direct methanol fuel cell.

Crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at various crosslinking temperatures using poly(acrylic acid-co-maleic acid) (PAM) containing different PAM contents. The thermal properties of these PVA/PAM membranes prepared at various reaction temperatures were characterized using differential scanning calorimetry (DSC). The proton conductivity and methanol permeability of PVA/PAM membranes were then investigated as PAM content was varied from 3 to 13 wt%. It was found that the proton and methanol transport were dependent on PAM content in their function both as crosslinking agent and as donor of hydrophilic -COOH groups. Both these properties decreased monotonously with increasing PAM concentration. The proton conductivities of these PVA/PAM membranes were in the range from 10-3 to 10-2S/cm and the methanol permeabilities from 10-7 to 10-6cm2/sec. In addition, the effect of operating temperature up to 80 oC on ion conductivity was examined for three selected membranes: 7, 9 and 11 wt% PAM membranes. Ion conductivity increased with increasing operating temperature and showed and S/cm at 80 oC, respectively. The effects of crosslinking and ionomer group concentration were also examined in terms of water content, ion exchange capacity (IEC), and fixed ion concentration. In addition, the number of water molecules per ionomer site was calculated using both water contents and IEC values. With overall consideration for all the properties measured in this study, 7~9 wt% PAM membrane prepared at 140 oC exhibited the best performance. These characteristics of PVA/PAM membranes are desirable in applications related to the direct methanol fuel cell (DMFC).

Preparation and Charcterization of pH-Sensitive Poly(ethylene oxide) Grafted Methacrylic Acid and Acrylic Acid Hydrogels by γ-ray Irradiation

radiation; crosslinking; radiation grafting; poly(ethylene oxide); pH-sensitive hydrogels; drug delivery; insulin

pH-sensitive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing it in the small intestine. In this study, hydrogels based on poly(ethylene oxide) (PEO) networks grafted with methacrylic acid (MAA) or acrylic acid (AAc) were prepared via a two-step process. PEO hydrogels were prepared by γ-ray irradiation (radiation dose: 50 kGy, dose rate: 7.66 kGy/h), grafted by either MAA or AAc monomers onto the PEO hydrogels and finally underwent irradiation (radiation dose: 5-20 kGy, dose rate: 2.15 kGy/h). These grafted hydrogels showed a pH-sensitive swelling behavior. The grafted hydrogels were used as a carrier for the drug delivery systems for the controlled release of insulin. Drug-loaded hydrogels were placed in simulated gastric fluid (SGF, pH 1.2) for 2 hr and then in simulated intestinal fluid (SIF, pH 6.8). The in vitro drug release behaviors of these hydrogels were examined by quantification analysis with a UVVis spectrophotometer.

Immobilization of Lactobionic Acid on Polyurethane Films and Their Interaction with Hepatocytes

films; polyurethanes; surfaces; hepatocytes

Polyurethanes containing z-lysine segments in the main chain (PULL) were synthesized from 4,4'-diphenylmethyl diisocyanate, poly(tetramethylene glycol), and z-lysine oligomer as a chain extender. The PULL film was treated first with a 10% HBr-acetic acid solution and subsequently with a saturated sodium bicarbonate aqueous solution to produce a primary amine group on the surface (PULL-N). Lactobionic acid (LA).immobilized PULL (PULL-L) was prepared by the coupling reaction of the PULL surface amine groups and the LA carboxylic acid groups. The surface-modified PULLs were then characterized by attenuated total reflection-Fourier transform infrared spectroscopy, electron spectroscopy for chemical analysis, atomic force microscopy, and contact angle goniometry. In the hepatocytes adhesion experiment, the cells poorly adhered to the PULL surface, although they adhered moderately well to the PULL-N surface. On the other hand, the cells adhered well to the PULL-L surface, suggesting the good affinity of the surface β-galactose moieties for hepatocytes. When hepatocytes were cultured in the presence of epidermal growth factor for 48 h, the cells rapidly aggregated on the PULL-L surface, whereas they aggregated only slowly on the other surfaces. The PULL prepared in this study has the potential to be used as a coating material for the enhancement of hepatocyte adhesion.

Aging Effect of Poly(vinyl alcohol) Membranes Crosslinked with Poly(acrylic acid-co-maleic acid)

fuel cell; poly(vinyl alcohol); aging effect; crosslinking; membrane

Poly(vinyl alcohol) (PVA) membranes crosslinked with poly(acrylic acid-co-maleic acid) (PAM) were prepared to investigate the effect of aging on their morphology by swelling them for up to 7 days. PAM was used both as a crosslinking agent and as a donor of the hydrophilic -COOH group. A 30 wt% weight loss of the dry membrane was observed in the swelling test after 6 days. The surface of the membrane was dramatically changed after the swelling test. The surface roughness of the PVA/PAM membrane was increased, as determined by atomic force microscopy (AFM). The swelling loosened the polymer structure, due to the release of the unreacted polymer and the decomposition of the ester bond, thereby resulting in an increase in the free volume capable of containing water molecules. The water molecules present in the form of free water were determined by differential scanning calorimetry (DSC). The fraction of free water increased with increasing swelling time. The swelling of the membrane may provide space for the transport of protons and increase the mobility of the protonic charge carriers. The proton conductivity of the membranes measured at T = 30 and 50 oC was in the range of 10-3 to 10-2 S/cm, and slightly increased with increasing swelling time and temperature.

Transesterification and Compatibilization in the Blends of Bisphenol-A Polycarbonate and Poly(trimethylene terephthalate)

poly(trimethylene terephthalate); polycarbonate; blend; transesterification; compatibilization.

Melt blending of Bisphenol A polycarbonate (PC) and poly(trimethylene terephthalate) (PTT) was carried out over the entire composition range. The mixing time was varied up to 90 min. The resulting samples were analyzed by FT-IR, DSC, XRD, DMTA, 1H NMR, and SEM. The process of transesterification between the two polymers and their resulting compatibilization were observed. The behaviors of the PTT-rich and PC-rich blends were different and an equilibrium was found to exist. Peculiar behavior, which was different from that of the PTT-rich and PC-rich blends, was exhibited by the 50/50 (PTT/PC) blend.

Dimethylphenoxy와 MPEG 팬던트 그룹을 갖는 폴리벤즈옥사졸 전구체의 합성 및 특성

polyhydroxyamides; polybenzoxazoles; thermal cyclization reaction

Polyhydroxyamides (PHAs) having poly(ethylene glycol)methyl ether (MPEG) and/or dimethylphenoxy pendant groups were synthesized by solution polycondensation at low temperature. The inherent viscosities of the PHAs measured at 35 ℃ in DMAC or DMAc/LiCl solution were in the range of 0.51~2.31 dL/g. This precursor polymers were studied by FT-IR, 1H-NMR, DSC, and TGA. Solubility of the precursors with higher MPEG unit was increased, especially the polymer having MPEG (Mn=1100) was soluble or partially soluble in ethanol, methanol, and water as well as aprotic solvents, but the PBOs were nearly insoluble in a variety of solvents. PHAs were converted to polybenzoxazoles (PBOs) by thermal cyclization reaction with heat of endotherm. In case of the precursors having MPEG unit, the precursor polymers with a higher Mn were fully cyclized at a lower temperature than one with a lower Mn.

온도응답성 고분자의 패턴상 그래프트를 이용한 공배양법

patterning; thermo-responsive polymer; co-culture; endothelial cell; hepatocyte

Thermo-responsive poly(N-isopropylacrylamide) (PIPAAm) was covalently patterned by masked electron beam irradiation. Introduction of PIPAAm on tissue culture polystyrene dish was confirmed by ATR-FTIR and ESCA measurements. Hepatocytes were cultured at 37 ℃ on these surfaces. Cells adhered on PIPAAm-grafted domains were detached by reducing culture temperature to 20 ℃. Endothelial cells were then seeded and cultured on the same surfaces. Seeded endothelial cells were selectively attached on hepatocytes detached and PIPAAm-grafted domains and could be co-cultured with hepatocytes on the same culture dishes with clear pattern. This co-culture method enabled long-term co-culture of hepatocytes with endothelial cells.

디메틸 테레프탈레이트와 1,3-프로판디올 사이의 에스테르교환반응에 관한 연구

dimethyl terephthalate (DMT); 1,3-propanediol (PDO); transesterification; kinetic; bis(2-hydroxytrimethyl)terephthalate (BHTMT)

The transesterification of dimethyl terephthalate (DMT) with 1,3-propanediol (PDO) was investigated in the presence of catalyst, titanium (IV) butoxide (TBO), at 175~190 ℃ . The degree of transesterification reaction was measured by the output of methanol which was distilled from the reactor. The amount of methanol increased as the reaction temperature, molar ratio and catalyst concentration increased. The observed overall rate of the transesterification was third order; first order with respect to DMT, PDO, and the concentration of catalyst, respectively. Using calculated rate constants, the activation energy for transesterification was 26.93 kcal/mole. The melting temperature of bis(2-hydroxytrimethyl) terephthalate (BHTMT) was 85.2℃ and heat of fusion 141.3 J/g.

Effect of Residual Water on the Adsorption of Ethylene Dichloride onto Pellet-Type Activated Carbon

adsorption; desorption; ethylene dichloride; activated carbon; fixed-bed

Activated carbon has been used as an adsorbent for various industrial applications, such as solvent recovery, gas separation, catalytic reaction or conversion, and deodorization. In this study, the effect of residual water on the adsorption characteristics of ethylene dichloride (EDC) onto a pellet-type carbon adsorbent was investigated. Isothermal adsorption column was used to study the effects that the feed concentration, flow rate, and residual water in the activated carbon pellet have on the adsorption characteristics of EDC. Desorption characteristics of residual water in the activated carbon were also studied. The water content in the activated carbon was controlled in the range from 0 to 20% (w/w). The experimental data for the adsorption equilibrium of EDC on the activated carbon is expressed well by the Sips isotherm. The adsorption capacity of EDC decreased upon increasing the temperature and residual water content. The theoretical breakthrough curves plotted using a linear driving force (LDF) model represent the experimental data very well.

Properties of Conductive Poly(ethylene oxide) (PEO)/Carbon Black (CB) Composite as a Vapor Sensor

poly(ethylene oxide) (PEO); carbon black; vapor sensor; film casting; electric resistance; polymer thin film

We have investigated the effect of solvent and carbon black structure on the electric resistance of the vapor sensor composite materials prepared by dispersing carbon black (CB) into a poly(ethylene oxide) (PEO) matrix. PEO polymers having molecular weights of 2 X 10⁶ and 4 X 10⁶ were selected to be the polar crystalline polymers. Carbon black, with particle sizes ranging from 45 to 300 nm, was used as a conductive material. After PEO was dissolved completely in tetrahydrofuran at 50 ℃, CB was added and stirred into the polymer solution uniformly. A conductive PEO film containing CB was made by casting it on a glass plate. The electrical resistance of the conductive PEO film in various solvent vapors, such as acetone, benzene, ethanol, isopropyl alcohol, and tetrahydrofuran, was measured in a glass tube containing pure solvent at the bottom. We found that the electrical resistance of the PEO/CB composite increased drastically in polar-solvent vapor, but had a low response to a non- and low-polar-solvent vapor. A PEO film filled with CB of large particle size exhibited a high response of its electrical resistance against vapors.

유기물과 영양염류 동시제거를 위한 SM-SBR 공정과 MBR 공정의 비교

SM-SBR; MBR; membrane separation

This paper is to investigate the character of membrane separation and the removal efficiency of organics and nutrients by the changes of operation cycles through SM-SBR to minimize the membrane contamination and remove organics and nutrients simultaneously. The operation pressure for membrane separation was controlled to be maintained lower than critical permeable flux to minimize the membrane contamination which was defect of MBR process. The contaminated water was intermittently fed into membrane to extend operation period. When SM-SBR process operation cycle 6~12 h/cycle, the contamination of membrane was decreased while the operation period was extended. The nitrogen removal efficiencies of 6, 8, 12 h/cycle were 50%, 67%, 88%, respectively and the phosphorous removal efficiencies of each h/cycle were 36.8%, 47%, 65.4%, respectively. The organics removal efficiency was over 90% for all operation cycles. According, it is considered that the SM-SBR process developed in this study can be used very efficiency as small scale water recycle system for removing organics and nutrients simultaneously.

음식물 발효액을 이용한 SBR공정에서 생물학적 영양염류 제거에 관한 연구

SBR; external carbon source; nutrient removal

The ratio of carbon to nitrogen sources (C/N ratio) is important to satisfy the water purification level in biological treatment processes. Due to low carbon contents in wastewater, the removal efficiency was decreased in biological nutrients removal process. Therefore, it is necessary to compensate carbon source to increase removal efficiency. In this research, the effect of external carbon source fermented leachate of food waste (FLFW) was studied. The effects of FLFW addition into wastewater that had low C/N ratio in SBR process on nitrogen and phosphorous removal efficiencies were investigated. The removal effciencies of NH₄⁺-N and PO₄^3--P were increased 81%~98% and 37%~80% with the addition of FLFW. Although the activity of nitrogen oxidizing microorganism was decreased when the reaction temperature was decreased 10 ℃ lower than that of normal operation, phosphorous removal efficiency showed independent of temperature and increased with addition of FLFW. Therefore, the efficient nutrients removal process can be established when FLFW and wastewater that has low C/N ratio are simultaneoously fed into SBR reactor.

졸-겔법에 의해 제조한 티타니아 졸의 살균 및 탈취 특성

titanium dioxide; titania sol; photocatalytic; formaldehyde; disinfection

Generally, photocatalysis can be applied to produce energy economically, synthesize the useful materials, and remove enviromentally harmful materials by transforming solar energy to chemical energy. Recently, the availability of photocatalysis has greatly inspired interested in the environment of Ubiquitous. Therefore, the study for photocatalysis has progressed by many investigators, particularly in Korea. In this study, titania sol was prepared by the sol-gel process for disinfection activity and deodorization, and its disinfection activity was performed in Escherichia coli and Staphylococcus aureus. The results: in case of wall paper coated with titania sol, the deodorization efficacy was considerably increased above 98.3% and 97.8% for formaldehyde and ammonia that cause indoor air pollution, respectively. Also, the disinfection activity for Escherichia coli and Staphylococcus aureus showed superior character above 99.9% after 24 h. From these results, formaldehyde and ammonia can effectively be removed by titania sol prepared in this study. In addition, this photocatalysis was found to give a very high efficiency for disinfection of Escherichia coli and Staphylococcus aureus.

6FDA-DDBT/DABA 공중합 폴리이미드막에 의한 벤젠/싸이클로헥산 혼합액의 분리

separation of benzene/cyclohexane; copolyimide; pervaporation; sorption; crosslinking

Copolyimide membranes containing both sulfonyl (-SO₂) and trifluoromethyl (-CF₃) groups, which have high affinity for aromatic hydrocarbons, were prepared and the pervaporation properties of these membranes were investigated for the separation of benzene/cyclohexane mixtures. The 6FDA-DDBT/DABA copolyimides were obtained by polycondensation of 4,4`'hexafluoroisopropylidene dianhydride (6FDA) with dimethyl-3,7-diaminobenzothiophene-5,5`-dioxide (DDBT) and 3,5-diaminobenzoic acid (DABA). In order to prevent excessive swelling effects, the copolyimides were crosslinked with ethylene glycol. With the copolyimides synthesized, sorption and pervaporation experiments were performed for benzene/cyclohexane mixtures at 323 K, 333 K and 351 K. It has been found that all the crosslinked copolyimides showed high separation performances with good chemical and thermal stability. Compared with the noncrosslinked copolyimides, the chemically crosslinked copolyimides exhibited a lower permeation flux and a higher permselectivity. For the most promising membrane meterial, the crosslinked 6FDA-DDBT/DABA (9/1) had a specific permeation flux of 4.94 kgμm/m²h and a separation factor of 17.8 at a feed composition of 60 wt% benzene in cyclohexane at 351 K.

NBR/GTR발포체의 난연 및 발포특성에 대한 난연제의 영향

NBR; GTR; phosphorus/nitrogen containing flame retardant; flame retardancy; foaming property

In this study, flame retardancy and foaming properties of NBR/GTR foams with phosphorus/nitrogen-containing flame retardants were investigated. For TGA analysis of NBR/GTR foams, thermal properties were improved by increasing phosphorus content of flame retardants. Limiting oxygen index (LOI) was affected largely by foaming properties (cell structure, expandability, etc) and it increased when phosphorus/nitrogen-containing flame retardants were used. This was due to the N/P synergistic effect for high and hard char formation. When the phosphorus/nitrogen-containing flame retardants were 10 phr, foams with the highest LOI (34.0) were obtained. In case of cone-calorimeter test, heat release rate was increased as LOI values were decreased. When the phosphorus/nitrogen-containing flame retardants were 10 phr, foams obtained had the lowest heat release rate, total heat release, and carbon monoxide yield. Phosphorus/nitrogen-containing flame retardants had a considerable effect in the decrease of smoke density. It turns out that the dispersion of the additives and inner-pressure of the blends significantly influenced in determining the foaming properties.

폐석회 담체를 이용한 고정생물막 공정에서의 영양염류 제거 특성

support carrier; biofilm; waste lime; wastewater

In this study, new porous waste lime support carriers were developed and their removal efficiency of nutrient from wastewater in the biological aeration reactor was investigated. The effect of waste lime addition on the phosphate removal efficiency was investigated and the optimal waste lime concentration was found to be 8 g/L for 100 mg/L of PO₄-P solution. Cubic support carriers were prepared in the following order: mixing waste lime with curdlan solution, decreasing pH from 12 to 7, heating the samples at 120 ℃ for 30 min, and finally, dehydrating the samples at -70 ℃ for 48 hrs. When the volume percentage of the waste lime carriers increased from 10% to 30%, the removal efficiency of nitrogen significantly increased from 60% to 88%, and that of phosphate from 10% to 88%. These results indicate that the application of this new waste lime support carrier for wastewater treatment is very promising.

Hazardous Waste Destruction and Nitric Oxide Reduction with Externally Forced Oscillation

Hazardous Waste; Cavity Incinerator; External Oscillation; Nitric Oxide; CCl₄

The research described here focuses on the enhancement of hazardous waste destruction and the reduction in nitric oxide and unburned emissions in a cavity incinerator, which has externally forced acoustic oscillation. The specific configuration of the incinerator was manufactured to consist of two opposing jets and a rearward facing step [Chun, 1999]. The cavity-type incinerator warrants a sufficient residence time and effective turbulent mixing by the formation of a strong recirculation region in a combustion cavity. The experiments were carried out about combustion characteristics in a 3.2 kW laboratory scale, transportable, cavity incinerator without external oscillation. These showed that hazardous waste was destructed effectively, but unfortunately NO was increased by high gas temperature. To solve this problem, we developed an externally oscillated auxiliary burner embedded on the incinerator furnace. The external oscillation was effective to reduce NO which is produced at high temperature incineration and to destruct hazardous waste, simultaneously. Emissions of NO are seen to be decreased by nearly 60%, and DRE (destruction and removal efficiency) is above 99.99%, all with external forcing at a specific optimum conditions.

Steam Plasma Reforming of Biogas by Non-Thermal Pulsed Discharge

Biogas; Non-thermal Plasma; Plasma Reforming; SynGas; Pulse Corona

The purpose of this study was to develop technology that can convert biogas to synthesis gas (SynGas), a low emission substituted energy, using a non-thermal pulsed plasma method. To investigate the characteristics of the SynGas production from simulated biogas, the reforming characteristics were studied about the variations of pulse frequency, biogas component ratio (C₃H₈/CO₂), vapor flow ratio (H₂O/TFR), biogas velocity and pulse power. A maximum conversion rate of 49.1% was achieved for the biogas when the above parameters were 500 Hz, 1.5, 0.52, 0.32 m/s and 657W, respectively. Under the above-mentioned reference conditions, the dry basis concentrations of the SynGas were, H₂ 64.5%, CH₄ 8.1%, C₂H₂ 6.7%, C₃H₆ 4.9%, CO 0.8% and C₂H₄ 0.4%. The ratio of hydrogen to the other intermediates in the SynGas (H₂/ITMs) was 3.1.

Preparation of a Hydrophobized Chitosan Oligosaccharide for Application as an Efficient Gene Carrier

chitosan oligosaccharide (COS); cholesterol; gene delivery; hydrophobic moiety; nanoparticle.

To prepare chitosan-based polymeric amphiphiles that can form nanosized core-shell structures (nanoparticles) in aqueous milieu, chitosan oligosaccharides (COSs) were modified chemically with hydrophobic cholesterol groups. The physicochemical properties of the hydrophobized COSs (COSCs) were investigated by using dynamic light scattering and fluorescence spectroscopy. The feasibility of applying the COSCs to biomedical applications was investigated by introducing them into a gene delivery system. The COSCs formed nanosized self-aggregates in aqueous environments. Furthermore, the physicochemical properties of the COSC nanoparticles were closely related to the molecular weights of the COSs and the number of hydrophobic groups per COS chain. The critical aggregation concentration values decreased upon increasing the hydrophobicity of the COSCs. The COSCs efficiently condensed plasmid DNA into nanosized ion-complexes, in contrast to the effect of the unmodified COSs. An investigation of gene condensation, performed using a gel retardation assay, revealed that COS6(M_n= 6,040 Da) containing 5% of cholesteryl chloroformate (COS6C5) formed a stable DNA complex at a COS6C5/DNA weight ratio of 2. In contrast, COS6, the unmodified COS, failed to form a stable COS/DNA complex even at an elevated weight ratio of 8. Furthermore, the COS6C5/DNA complex enhanced the in vitro transfection efficiency on Human embryonic kidney 293 cells by over 100 and 3 times those of COS6 and poly(L-lysine),respectively.Therefore, hydrophobized chitosan oligosaccharide can be considered as an efficient gene carrier for gene delivery systems.

Nanofabrication of Microbial Polyester by Electrospinning Promotes Cell Attachment

electrospun nanofiber; PHBV; chondrocyte; cell attachment; tissue engineering

The biodegradable and biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a copolymer of microbial polyester, was fabricated as nanofibrous mats by electrospinning. Image analysis of the electrospun nanofibers fabricated from a 2 wt% 2,2,2-trifluoroethanol solution revealed a unimodal distribution pattern of fiber diameters with an observed average diameter of ca. 185 nm. The fiber diameter of electrospun fabrics could be controlled by adjusting the electrospinning parameters, including the solvent composition, concentration, applied voltage, and tip-to-collector distance. Chondrocytes derived from rabbit ear were cultured on a PHBV cast film and an electrospun PHBV nano-fibrous mat. After incubation for 2 h, the percentages of attached chondrocytes on the surfaces of the flat PHBV film and the PHBV nanofibrous mat were 19.0 and 30.1%, respectively. On the surface of the electrospun PHBV fabric, more chondrocytes were attached and appeared to have a much greater spreaded morphology than did that of the flat PHBV cast film in the early culture stage. The electrospun PHBV nanofabric provides an attractive structure for the attachment and growth of chondrocytes as cell culture surfaces for tissue engineering.

Preparation and Characterization of Sulfonated Poly(phthalazinone ether sulfone ketone) (SPPESK)/Silica Hybrid Membranes for Direct Methanol Fuel Cell Applications

sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK); silica; proton conductivity; methanol permeability; hybrid membrane

Sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) membranes and sol-gel derived SPPESK/silica hybrid membranes have been investigated as potential polymer electrolyte membranes for direct methanol fuel cell (DMFC) applications. In comparison with the SPPESK membrane, the SPPESK/silica membranes exhibited higher water content, improved proton conductivity, and lower methanol permeability. Notably, the silica embedded in the membrane acted as a material for reducing the fraction of free water and as a barrier for methanol transport through the membrane. From the results of proton conductivity and methanol permeability studies, we suggest that the fractions of bound and free water should be optimized to obtain desirable proton conductivities and methanol permeabilities. The highly sulfonated PPESK hybrid membrane (HSP-Si) displayed higher proton conductivity (3.42 × 10² S/cm) and lower methanol permeability (4.15 × 10⁷ cm²/s) than those of Nafion 117 (2.54 × 10² S/cm; 2.36 × 10⁶ cm²/s, respectively) at 30 °C. This characteristic of the SPPESK/silica membranes is desirable for future applications related to DMFCs.

Preparation of Alginate/Poly(N-isopropylacrylamide) Hydrogels Using Gamma-ray Irradiation Grafting

alginate; gamma-ray irradiation; graft; hydrogel; N-isopropylacrylamide.

To graft N-isopropylacrylamide (NIPAAm) onto alginate, varying dosages of γ-rays were irradiated onto alginate films in deionized water and methanol media, which are non-solvents of alginate. We investigated the hydrogels graft ratio, mechanical strength, swelling kinetics and ratio, and behavior with respect to drug release. The graft yield of NIPAAm increased upon increasing the irradiation dose. The use of the aqueous solution increased the graft yield relative to that obtained in methanol. The mechanical strength of the grafted hydrogels increased after grafting with NIPAAm. In a study of the swelling kinetics, we found that all hydrogels reached an equilibrium swollen state within 3 h. The equilibrium swelling ratio of the hydrogels decreased upon increasing the irradiation dose. The swelling ratio of the hydrogels decreased dramatically between 30 and 35 ℃ because phase separation of NIPAAm occurred at 32 ℃. The swelling process, with respect to the temperature change, was repeatable. An NIPAAm-grafted alginate containing a drug sustained its release rate until 3 h after an initial high drug release caused by a burst effect.

Anti-complement Effects of Anion-Substituted Poly(vinyl alcohol) Membranes

carboxymethylated poly(vinyl alcohol); sulfonated poly(vinyl alcohol); hemodialysis membrane; complement activation.

In a continuation of our previous studies on blood compatibility profiles of anion-substituted poly(vinyl alcohol) (PVA) membranes, in which hydroxyl groups have been replaced with carboxymethyl (C-PVA) and sulfonyl groups (S-PVA), we have studied the activation of complement components and the changes in white cell and platelet count in vitro and compared them with those of unmodified PVA, Cuprophane, and low-density polyethylene. Complement activation of fluid phase components, C3a, Bb, iC3b, and SC5b-9, and of bound phases, C3c, C3d, and SC5b-9, were assessed by enzyme-linked immunosorbent assay (ELISA) and immunoblot, respectively. The changes in the number of white cells and platelets following complement activation were counted using a Coulter counter. C-PVA and S-PVA activated C3 to a lesser extent than did PVA, which we attribute to the diminished level of surface nucleophiles of the samples. In addition, C- and S-PVA exhibit increased inhibition of Bb production, resulting in a decrease in the extent of C5 activation. Consequently, because of the reduced activation of C3 and C5, C- and S-PVA samples cause marked decreases in the SC5b-9 levels in plasma. We also found that the negatively charged sulfonate and carboxylate groups of the samples cause a greater extent of adsorbtion of the positively charged anaphylatoxins, C3a and C5a, because of strong electrostatic attraction, which in turn provides an inhibition of chemotaxis and activation of leukocytes. The ability to inhibit complement production, together with the binding ability of anaphylatoxins of the C- and S-PVA samples, leads to a prominent decrease in lysis of leukocytes as well as activation of platelets.

인슐린을 고정화한 폴리우레탄 막의 제조 및 섬유아세포와의 상호작용

insulin; polyurethane; fibroblasts; surface modification; proliferation

Polyurethanes containing L-lysine segments in the main chain (PULL) were synthesized from 4, 4′-diphenymethyl diisocynate, poly(tetramethylene glycol), and z-lysine oligomer as a chain extender. Insulinimmobilized polyurethanes (PULL-In) were prepared by a coupling reaction of PULL surface amino groups with insulins. The amount of immobilized insulin was about 0.30 nmol/cm², as determined by Bradford method. The interactions of NIH/3T3 fibroblasts with surface-modified PULLs were investigated using ³H-thymidine incoporation and optical microscopy. The cell growth rate on PULL-In film was higher than those on other substrates. The cell proliferation by the immobilized insulin was almost same as that by the free one.

팽창 흑연을 포함한 NBR/GTR 발포체의 난연 및 발포특성

NBR; GTR; expandable graphite; foaming property; flame retardancy

The influence of expandable graphite (EG) on flame retardancy and foaming properties of the NBR/GTR foams was studied. The foaming properties were similar to those of NBR/GTR foams without EG when the EG contents were 10~30 phr. The LOI values were increased with the EG content. For cone-calorimeter test, the data showed the trend similar to that from experiment. When the composition ratios of the compounds of NBR/GTR were 100~0/80~20 (w/w), and the EG contents were 10~30 phr, we obtained high flame retardancy foams with low heat release rate (HRR), total heat release (THR), effective heat of combustion (EHC) and carbon monoxide yield (COY). The smoke density is similar to CO yield values obtained by the cone-calorimeter test. TGA analysis also showed the results approximately similar to those from the LOI and cone-calorimeter experiments.

수용성 키토산으로 제조한 미세구의 분해성과 약물 방출 거동

water-soluble chitosan; degradation; microsphere; norfloxacin; glutaraldehyde

Water-soluble chitosan microspheres were prepared by emulsification of chitosan solution in mineral oil followed by crosslinking reaction with different amount of the crosslinking agent (glutaraldehyde), different chitosan concentration. Then, the physicochemical properties such as morphological change by degradation, drug loading efficiency, and drug release profiles were investigated with the drug loaded water-soluble chitosan microspheres. Norfloxacin loaded water-soluble chitosan microspheres showed excellent drug entrapping capacities without burst release caused by surface bound drug. The absence of the surface bound drug also confirmed by X-ray diffraction study. Degradation and drug release studies showed that the amount of the crosslinking agent played a crucial role for drug loading, release and degradation. The water-soluble chitosan microspheres showed more sustained drug release profiles with slower degradation and larger particle size by increasing crosslinking agent.

Radiation-Induced Copolymerization of 2-Hydroxyethyl methacrylate and Polyethylene glycol methacrylate, and Its Protein Adsorption and Bacterial Attachment

radiation-induced copolymerization; 2-hydroxyethyl methacrylate; polyethylene glycol methacrylate; hydrogel; protein adsorption; bacterial attachment; biomaterial

In an attempt to produce biomaterial that shows the low levels of adsorption of proteins and adhesion of bacteria, 2-hydroxyethyl methacrylate(HEMA) and polyethylene glycol methacrylate(PEG-MA) co-monomers with ethylene dimethacrylate(EDMA) crosslinker were co-polymerized by using a γ-ray radiation technique. PEG-MA having a different molecular weight of polyethylene oxide was used for synthesizing copolymeric hydrogels for contact lenses. The degree of polymerization and water content of the hydrogels were examined. The protein adsorption on the hydrogel surfaces was investigated by electron spectroscopy for chemical analysis (ESCA). Bacterial attachments were evaluated by examining the adhesion on hydrogel surfaces by microscope and a viable cell counting method against Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa). The amount of adsorption of protein and adhesion of bacteria on sample surface decreased significantly in the copolymer specimen of HEMA and PEG-MA, when comparing with the hydrogel of polyHEMA alone.

상용화제 SEBS-g-MA가 PA6/PP-g-MA 블렌드계의 나노 고차구조에 미치는 영향

morphology; PA6; PP; SEBS-g-MA; small angle x-ray scattering

Effect of maleic anhydride grafted triblock copolymer of poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS-g-MA) on the morphology of the blends of polyamide 6 (PA6) and maleated polypropylene (PP-g-MA) was investigated by small angle x-ray scattering, differential scanning calorimeter and scanning electron microscopy. The size of the dispered PA6 decreased with addition of SEBS-g-MA. SEBS-g-MA reacted with the amine group of PA6 during the melt-compounding, and as a result, the copolymer, formed by interfacial reaction between PA6 and SEBS-g-MA, led to reduction in size of the dispersed PA6. SEBS-g-MA was partially microphase-separated to dispersion phase, and its size increased proportional to the amount of added SEBS-g-MA and increased temperature. The microphase-separated dispersion phase highly affected the crystallinity of the PP-g-MA matrix and PA6 dispersion.

Computational Fluid Dynamics (CFD) Analysis and Experimental Study for Toxic Hazardous Waste Destruction in the Cavity Incinerator

Hazardous Waste; Cavity Incinerator; Reaction Model; CCl4; Flame Inhibition

We undertook numerical and experimental studies to develop a better incineration method for the destruction of CCl4. A phenomenological model for the turbulent reaction of CCl4, including a flame inhibition feature, has been successfully incorporated into a commercial code, simulating the incineration processes of this compound. The gaseous flow solution was obtained using SIMPLEST, a derivative of Patankar’s SIMPLE algorithm, with a k-ε turbulence model. A modified fast chemistry turbulent reaction model was developed to describe the flame inhibition due to the presence of CCl4, considering the corresponding burning velocity data of these mixtures. An experiment was carried out on a 5.2 kW laboratory scale, transportable, cavity-type incinerator, which warrants a sufficient residence time and effective turbulent mixing by the formation of a strong recirculation region in a combustor. To this end, the specific configuration of the incinerator was manufactured to consist of two opposing jets and a rearward facing step. The calculated data were in close agreement with the experimental data for the concentrations of major species, such as CCl4 and HCl, together with the temperature profiles. The experimental test gave the desired DRE of above 99.99%.

Molecular Thermodynamics Approach on Phase Equilibria of Dendritic Polymer Systems

Dendritic Polymer; Molecular Thermodynamics; Molecular Simulation; LLE; VLE; Structure; Specific Interaction

We suggest a molecular thermodynamic framework to describe the phase behavior of dendritic polymer systems. The proposed model, which is based on the lattice cluster theory, contains correlations of molecular structure and specific interactions such as hydrogen bonding to the phase equilibria of branch-structured polymer systems. We examine liquid-liquid equilibria (LLE) of hyperbranched polymer solutions and vapor-liquid equilibria (VLE) of dendrimer solutions in the viewpoints of effects of a branched structure and specific interaction formations among endgroups of dendritic polymer and solvent molecules. We investigate VLE of dendrimer/solvent (Benzyl Ether Dendrimer/Toluene) systems by the combination of a new lattice-based model and atomistic simulation technique. The interaction energy parameters are obtained by the pairs method [Baschnagel et al., 1991] including Monte Carlo simulation with excluded volume constraint. In the pairs method [Baschnagel et al., 1991], we do not simulate the whole molecule as in molecular dynamics or molecular mechanics, but only monomer segments interacting with solvent molecules. The proposed model shows improvements in prediction for both phase equilibria (VLE and LLE) due to the branched structure and specific interaction due to endgroups at periphery of dendritic polymer molecule. Atomic simulation technique gives good result in prediction without fitting variables. Our results show that the specific interactions between the endgroup and the solvent molecule play an important role in phase behavior of the given systems.

Plasma Protein Adsorption to Anion Substituted Poly(vinyl alcohol) Membranes

carboxymethylated poly(vinyl alcohol); sulfonated poly(vinyl alcohol); hemodialysis membrane; plasma protein adsorption.

Anion-substituted poly(vinyl alcohol) (PVA) membranes, carboxymethylated PVA (C-PVA), and sulfonated PVA (S-PVA) were prepared and the effects of these substitutions on the plasma protein adsorption were studied by one- and two-dimensional gel electrophoresis and immunoblotting. When Cuprophane was used as a negative control, the amount of total proteins bound to samples decreased in the order Cuprophane > PVA > C-PVA > S-PVA, which we attribute to the effects of the surface characteristics of the samples, such as their surface tensions and electrostatic properties, on the adsorption of proteins to the surfaces of the materials. The results revealed that albumin was the most abundant protein in all the samples. The proportion of adsorbed fibrinogen to S-PVA exceeded those of PVA and C-PVA, whereas S-PVA exhibited the lowest IgG adsorption affinity among the samples we studied.

Behavior of Hepatocytes Inoculated in Gelatin-Immobilized Polyurethane Foam

gelatin; polyurethane foam; hepatocyte; albumin secretion.

We have fabricated gelatin-immobilized polyurethane foams (PUFG) by dipping polyurethane foam (PUF) in an aqueous solution containing gelatin and by subsequent reaction with glutaraldehyde after freeze-drying. Gelatin aqueous solutions of different concentrations were used as the dipping solutions to control the amount of immobilized gelatin. The average pore size of PUF decreased with an increase in gelatin concentration. It was found from the hepatocyte adhesion experiment that the amount of hepatocytes seeded on PUFG1, prepared by using a 1% aqueous gelatin solution, was higher than that on other PUFGs. The hepatocytes inoculated in PUFG1 were slightly aggregated as the incubation time increased. The cells inoculated in PUFG1 showed higher ammonia removal ability than those monolayer-cultured on a gelatin-immobilized polystyrene dish (PSG) after 1 and 4 days of incubation time. The inoculated cells exhibited higher albumin secretion relative to monolayer-cultured hepatocytes on PSG. Albumin secretion by hepatocytes seeded on PUFG1 was increased by the presence of serum and was further increased by both the presence of serum and cytokines. The results obtained from a 3-(3,4-dimethylthiazol-2yl)-2,5- diphenyltetrazolium bromide (MTT) assay indicated that PUFG can provide a better microenvironment for hepatocyte culture along with nutrition and metabolite transfer through the high porosity of PUF.

Artificial Dermis Composed of Gelatin, Hyaluronic Acid and (1→3),(1→6)-β-Glucan

gelatin; β-glucan; hyaluronic acid; scaffold; skin

Porous scaffolds composed of gelatin and polysaccharides such as hyaluronic acid and b-glucan were prepared by using the freeze-drying method after cross-linking with 1-ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). The scaffold had an inter-connected pore structure with the sufficient pore size for use as a support for the growth of fibroblasts. Results for the contact angle and cell attachment confirmed that high gelatin content in a mixture was suitable for cellular attachment and distribution in two- or three-dimensional fibroblast cultures. However, the addition of polysaccharides aroused the synergistic effects of morphologic and mechanical property of gelatin-based scaffolds. To prepare the artificial dermis for the wound dressing to mimic the normal human dermal skin, fibroblasts were isolated from a childs foreskin, and cultured in gelatin-based scaffolds. An in vivo study showed that the artificial dermis containing the fibroblasts enhanced the wound healing rate and re-epithelialization of a full-thickness skin defect rather than the acellular scaffold after one week.

Preparation of Polymeric Self-Assembly and Its Application to Biomaterials

self-assembly; Langmuir-Blodgett films; polymeric micelle; polymeric nanoparticles; induced circular dichroism

The self-assembly of polymers can lead to supramolecular systems and is related to the their functions of material and life sciences. In this article, self-assembly of Langmuir-Blodgett (LB) films, polymer micelles, and polymeric nanoparticles, and their biomedical applications are described. LB surfaces with a well-ordered and layered structure adhered more cells including platelet, hepatocyte, and fibroblast than the cast surfaces with microphase-separated domains. Extensive morphologic changes were observed in LB surface-adhered cells compared to the cast films. Amphiphilic block copolymers, consisting of poly(γ-benzyl L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) [or poly(N-isopropylacrylamide) (PNIPAAm)] as the hydrophilic one, can self-assemble in water to form nanoparticles presumed to be composed of the hydrophilic shell and hydrophobic core. The release characteristics of hydrophobic drugs from these polymeric nanoparticles were dependent on the drug loading contents and chain length of the hydrophobic part of the copolymers. Achiral hydrophobic merocyanine dyes (MDs) were self-assembled in copolymeric nanoparticles, which provided a chiral microenvironment as redshifted aggregates, and the circular dichroism (CD) of MD was induced in the self-assembled copolymeric nanoparticles.

골수유래 간엽줄기세포와 점착성 단백질 및 폴리펩타이드가 흡착된 (락티이드/글리콜라이드) 공중합체 지지체와의 상호작용

cell adhesive biomolecules; poly(lactide-co-glycolide); bone marrow stromal stem cell; cell interaction

The interaction of cell adhesive protein and polypeptide with bone marrow stromal stem cells (BMSCs) grown in tissue engineered films and scaffolds were examined. Several proteins or polypeptide known as cell-adhesive were coated adsorption on poly(lactide-co-glycolide) (PLGA) films and scaffolds and adhesion and proliferation behavior of BMSC on those surfaces were compared. The protein and polypeptide used include collagen IV, fibrinogen, laminin, gelatin, fibronectin, and poly(L-lysine). The protein and polypeptide were adsorbed on the PLGA film surfaces with almost monolayer coverage except poly(L-lysine). BMSCs were cultured for 1, 2, and 4 days on the protein- or polypeptide-adsorbed PLGA films and scaffolds. The cell adhesion and proliferation behaviors were assessed by sulforho damine B assay. It was observed that the protein- or polypeptide-adsorbed surfaces showed better cell adhesion and proliferation than the control.

보호된 이소시아네이트기와 불소화 알킬기를 가지는 아크릴계 고분자의 합성과 특성

protected isocyanate group; fluoroalkyl group; water repellent polyacrylate derivative; reactivity ratio; contact angle

The copolymerizations of 2-fluorohexylethyl acrylate (FA) with 2-(o-(1-'methylpropylidenamino)carboxyl amino) ethyl methacrylate (MEM) with different molar ratios of the two monomers were carried out in methyl ethyl ketone using α,α',-azobisisobutyronitrile as an initiator to synthesize water repellent polyacrylate derivatives with protected isocyanate groups. The contents of FA and MEM in the copolymers were analyzed by NMR. The monomer reactivity ratios of MEM (1) and FA (2) were determined by Kelen-Tudos plot as follows : r₁=1.59 and r₂=0.50. The number-average molecular weights of the copolymers were in the range of 39400 to 72400 and the polydispersity indexes were about 1.5. The protected isocyanate groups in the copolymers were converted into isocyanate groups above 150 ℃. The contact angle of the copolymer with 65 mol% of FA for water was about 95 °.

활성탄에 의한 사염화탄소 흡착공정에서 잔존수분의 영향

Adsorption; Desorption; CCl4; Activated Carbon

Activated carbons have been used as adsorbents in various industrial application, such as solvent recovery, gas separation, deodorization, and catalysts. In this study, the effects of residual water on the activated carbon adsorbent surface on the adsorption capacity of CCl4 were investigated. Adsorption behavior in a fixed bed was studied in terms of feed concentration, flow rate, breakthrough curve and adsorption capacity for CCl4. Desorption characteristics of residual water on activated carbon were also studied. The water contents of the activated carbon were varied in the range of 0-20%(w/w) and all experiments were performed at 298.15 K. The adsorption equilibrium data CCl4 on the activated carbon were well expressed by Langmuir isotherm. The adsorption capacity of CCl4 decreased with increasing residual water content. Desorption of residual water in activated carbon decreased expotentially with CCl4 adsorption. The obtained breakthrough curves using LDF(linear driving force) model represented our experimental data.

대형 도시폐기물 소각로의 연소특성을 파악하기 위한 수치 해석적 연구

MSW; Incinerator; Combustion Model; CFD; Turbulent Flow

The interest of incineration, which is one of the effective methods for municipal waste disposal, has gradually increased because the incineration could reduce the volume and weight of the waste, and produce useful energy from the waste. This study has developed the 3-dimensional numerical model, and applied for the investigation of combustion characteristics and optimized operating conditions in MSW incinerator in Gwangju. The model developed in this study has been verified through the comparison between the predicted and the measured temperature in combustion chamber which is operating. By predictive results, the Sangmoo incinerator has a good characteristics of combustion efficiency and a low emission by the second burning in the main flame zone, even though after burning zone produces incomplete products by which primary air is introduced not enough.

폐유 캐비티 소각기 개발을 위한 수치해석

Cavity; Incinerator; Waste Oil; Combustion; Emission

We proposed advanced cavity incinerator to incinerate waste oil which is contained water. The cavity incinerator has heat recirculation region in the cavity to be burnt out completely in high temperature zone. And heat recuper, being left side of cavity, plays a role in the flame stabilization of auxiliary burner flame by heat recovery of exhaust gas. The results in standard incinerator, which was selected by iterative calculation, showed that the combustion and emission characteristics of cavity incinerator are excellent. And operating conditions were proposed by parametric screening studies about injection velocity, injection temperature and injection point of waste oil and air.

곁사슬에 ethoxy 그룹을 갖는 열방성 액정폴리에스테르와 폴리(에틸렌 2,6-나프탈레이트)와의 블렌드

TLCP; PEN; in-situ composite; nucleating agent

A new thermotropic liquid crystalline polymer (TLCP) with ethoxy side group was synthesized for the preparation of in-situ composite, and the blends of TLCP with poly(ethylene 2,6-naphthalate) (PEN) were prepared by solution blending. TLCP, PEN and blends (2, 5, 10 and 20 wt%) were characterized in terms of their thermal, mechanical and morphological properties. TLCP in the melt showed the nematic phase. The glass transition temperature (Tg) of PEN in the blends decreased with increasing content of TLCP; TLCP acted as a nucleating agent for the matrix polymer. The crystallization temperature (Tc) of PEN in the blends increased with increasing content of TLCP. In the blends, liquid crystalline phase did not reveal any significant macrophase separation and thermal degradation at the processing temperature. From scanning electron micrographs of cryogenically fractured surfaces, the TLCP domains were found to be fine and uniformly dispersed having 0.2 to 0.3 μm in size. Interfacial adhesion between TLCP and the matrix polymer was determined to be good. The modulus of TLCP/PEN blends were enhanced as TLCP's content increased.

항균제로서 8-히드록시퀴놀린의 moiety를 가지는 아크릴고분자의 합성과 특성

acrylic siging agent; microbicidal activity; release; 8-hydroxyquinoline

8-Quinolinyl acrylate and monomers of ethyl acrylate, methyl methacrylate, and acrylic acid were radically copolymerized in order to prepare an acrylic sizing agent with microbicidal activity. The yield and the molecular weight of the polymer increased with increasing the polymerization time. The number-average molecular weight was in the range of 26000 to 42000, and the polydispersity was in the range of 3.0 to 4.2. The glass transition temperature was at around 36 ℃, and the initial decomposition temperature was around 250 ℃. The release rate of 8-hydroxyquinoline from the polymer increased with increasing pH of the release medium. This result was attributed to the enhanced proton dissociation of carboxyl group of the acrylic acid unit in the polymer. The polymer was excellent for reducing microbial activity of the E.Coli.

폴리실록산-이미드 공중합체의 기체 투과 특성

poly(siloxane-imide); polysiloxane; copolymer; permeability; permselectivity

Poly(siloxane-imide)(PSI) copolymer membranes with various poly siloxane(PSX) contents were prepared and their structural characteristics and gas permeation properties of H2, CO2, O2, N2 and CH4 were studied. PSI membranes were obtained by the reaction of 1,2,4,5-benzenetetracarboxylic dianhydride(PMDA), 4,4'-oxydianiline(ODA) and amine-terminated PSX. The PSI membranes showed high thermal stability and their d-spacing value increased with increasing PSX content. The gas permeability coefficients through PSI membranes increased with increasing PSX content and decreased in the order of H2>CO2>O2>N2>CH4. In spite of the permeability enhancement, the permselectivity of CO2/CH4 increased and even those of H2/CH4, O2/N2, N2/CH4 were nearly constant. It was found that the permeability and permselectivity could be controlled by the PSX content.

연료전지용 고분자전해질막

polymer electrolyte fuel cell; polymer electrolyte membrane; direct methanol fuel cell; proton-conducting membrane

A highly efficient energy production from renewable sources, without pollutant emission such as CO2 and NOx, is no longer a fantastic dream of a far future. This low energy and environment-friendly technology is being realized by recent developments in the fuel cell technology. Among various kinds of the fuel cell, the polymer electrolyte fuel cell (PEFC) using proton-conducting membrane is the desirable choice in mobile and portable applications, due to its low operating temperature, possibility of using air as the oxidant medium and hydrogen or liquid as the fuel. However, many researches in the last decades have been focused on improving electrode catalyst and optimizing the stack design and operating conditions. That is, the development of membrane materials for PEFC has been overlooked and concentrated mainly on the perfluorinated polymer, Nafion®. Today, Nafion® is facing many problems such as decreased proton conductivity, due to the loss of water-uptake at high temperature, high gas permeability, methanol crossover, and high cost. Therefore, the development of effective and low cost membrane materials for fuel cells is very significant and urgent assignment in this fascinating field of fuel cell technology. In this review, some of the recent developments of proton-conducting polymeric membranes and future direction of the research on membranes for fuel cells are discussed.

Statistical Modeling of Electrochemical Removal of Sodium in Fermented Food Composts

Statistical Modeling; Sodium Removal; Compost; Response Surface Methodology

Electrochemical removal of sodium ion from fermented food composts was analyzed and statistically modeled by response surface methodology (RSM). Empirical models were developed to describe relationships between the operating variables (operation time, current density and water contents) and three responses (removal efficiency, energy expenditure and energy efficiency). Statistical analysis indicated that operation time and current density have significant effect on all responses. Good agreement between predicted and measured values confirmed the usefulness of the model. The models were verified by additional experimental at optimum conditions.

A Numerical Simulation of Hazardous Waste Destruction in a Three-Dimensional Dump Incinerator

Incinerator; Dump; CFD; CCl4; Nonequilibrium; Combustion

A predictive model of carbon tetrachloride (CCl4) incineration in a dump incinerator is described. An empirical model that incorporates the chemical kinetic aspects of CCl4 destruction is developed to describe the flame inhibition characteristics of CCl4, which is halogen compounds. Quantitative agreement is found between the predictions of the model and the measured values. Cavity hydrodynamics and flame structure studies are made in a dump incinerator proposed in this study. For the effective destruction of hazardous waste, the waste must injected in the recirculation region of high temperature with the condition of not disturbing the combustion cavity. The core flame has a significant impact on the structure of the recirculation region, in some cases completely changing the nature of the flow within the cavity. The dump incinerator has good characteristics for the destruction of hazardous waste. These characteristics should lead to a very compact device, one which is potentially transportable or usable in a dedicated manner by a small generator.

A Phenomenological Model for Linear Viscoelasticity of Monodisperse Linear Polymers

monodisperse polymers; linear viscoelasticity; molecular weight

Although the reptational model of Doi and Edwards gives a successful description of viscoelasticity of flexible linear polymers, the success is restricted to the terminal region.1 There have been several attempts to modify the Doi-Edwards model to describe wider range of time or frequency.2-6 This paper suggests a simple phenomenological model which can describe wider range of molecular weight than such molecular models can. Although our model is a phenomenological one, it is practical and convenient to predict the effect of molecular weight distribution on linear viscoelastic data because of its simple mathematical form.

Effect of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Surface with Different Wettability on Fibroblast Behavior

poly(3-hydroxybutyrate-co-3-hydroxyvalerate); corona discharge; chloric acid mixture solution; wettability; NIH/3T3 fibroblasts

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a microbial storage polymer with biodegradable properties. In order to improve the cell compatibility of PHBV surfaces, the physicochemical treatments have been demonstrated. In this study, physical method was corona discharge treatment and chemical method was chloric acid mixture solution treatment. The physicochemically treated PHBV film surfaces were characterized by the measurement of water contact angle, electron spectroscopy for chemical analysis, and scanning electron microscopy (SEM). The water contact angle of the physicochemically treated PHBV surfaces decreased from 75 to 30~40 degree, increased hydrophilicity, due to the introduction of oxygen-based functional group onto the PHBV backbone chain. The mouse NIH/3T3 fibroblasts cultured onto the physicochemically treated PHBV film surfaces with different wettability. The effect of the PHBV surface with different wettability was determined by SEM as counts of cell number and [3H]thymidine incorporation as measures of cell proliferation. As the surface wettability increased, the number of the cell adhered and proliferated on the surface was increased. The result seems closely related with the serum protein adsorption on the physicochemically treated PHBV surface. In conclusion, this study demonstrated that the surface wettability of biodegradable polymer as the PHBV plays an important role for cell adhesion and proliferation behavior for biomedical application.

Preparation and Characterization of Small Intestine Submucosa Powder Impregnated Poly(L-lactide) Scaffolds: The Application for Tissue Engineered Bone and Cartilage

SIS; PLA; tissue engineering; bone; scaffolds

In order to endow with new bioactive functionality from small intestine submucosa (SIS) powder as natural source to poly(L-lactide) (PLA) and poly(lactide-co-glycolide) (PLGA) synthetic biodegradable polymer, porous SIS/PLA and SIS/PLGA as natural/synthetic composite scaffolds were prepared by means of the solvent casting/salt leaching methods for the possibility of the application of tissue engineered bone and cartilage. A uniform distribution of good interconnected pores from the surface to core region was observed the pore size of 40~500 μm independent with SIS amount using the solvent casting/salt leaching method. Porosities, specific pore areas as well as pore size distribution also were almost same. After the fabrication of SIS/PLA hybrid scaffolds, the wetting properties was greatly enhanced resulting in more uniform cell seeding and distribution. Five groups as PGA nonwoven mesh without glutaraldehyde (GA) treatment, PLA scaffold without or with GA treatment, and SIS/PLA (Code No. 3 ;1: 12 of salt content, 0.4 : 1 of SIS content, and 144 μm of median pore size) without or with GA treatment were implanted into the back of nude mouse to observe the effect of SIS on the induction of cells proliferation by hematoxylin and eosin, and von Kossa staining for 8 weeks. It was observed that the effect of SIS/PLA scaffolds with GA treatment on bone induction are stronger than PLA scaffolds, that is to say, in the order of PLA/SIS scaffolds with GA treatment > PLA/SIS scaffolds without GA treatment > PGA nonwoven > PLA scaffolds only with GA treatment = PLA scaffolds only without GA treatment for the osteoinduction activity. The possible explanations are (1) many kinds of secreted, circulating, and extracellular matrix-bound growth factors from SIS to significantly affect critical processes of tissue development and differentiation, (2) the exposure of SIS to GA resulted in significantly calcification, and (3) peri-implant fibrosis due to covalent bonding between collagen molecule by crosslinking reaction. In conclusion, it seems that SIS plays an important role for bone induction in SIS/PLA scaffolds for the application of tissue engineering area.

계면활성제를 사용하지 않는 Poly(DL-lactide-co-glycolide) 나노입자로부터의 Norfloxacin 방출과 생분해 특성

poly(DL-lactide-co-glycolide); surfactant-free nanoparticles; dialysis method; norfloxacin; biodegradation

We have prepared the surfactant-free nanoparticles of poly(DL-lactide-co-glycolide)(PLGA) by dialysis method and their physicochemical properties such as particle size and drug contents were investigated against various solvent. The size of PLGA nanoparticles prepared by using dimethylacetamide (DMAc), dimethylformamide (DMF), and dimethylsulfoxide (DMSO) was smaller than that from acetone. Also, the order of drug contents was DMAc＞DMF＞DMSO = acetone. These phenomena could be expected from the fact that solvent affects the size of nanoparticles and drug contents. The PLGA nanoparticles have a good spherical shapes as observed from scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Also, surfactant-free nanoparticles entrapping norfloxacin (NFx) have a good drug loading capacity without free-drug on the surface of nanoparticles confirmed by the analysis of X-ray powder diffraction. Release kinetics of NFx used as a model drug was governed not only by drug contents but also by particle size. Also, the biodegradation rate of PLGA nanoparticles prepared from DMF was faster than that prepared from acetone, indicating that the biodegradation of PLGA nanoparticles is size-dependent.

항균제로서 m-크레졸의 Moiety를 가지는 고분자의 합성과 특성

microbicide; m-cresyl acrylate; terpolymerization; release

By the reaction of m-cresol as a microbicide with acryloyl chloride m-cresyl acrylate (CA) was synthesized, and polymers with the moiety of m-cresol were prepared by the radical terpolymerization of CA-methylmethacrylate-acrylic acid. The contents of CA unit in the polymers were found to be 4.7 mol% and 10.1 mol% from their nuclear magnetic resonance spectra. The number-average molecular weights of the polymers were in the range of 12000 to 15000. Through the hydrolysis of the polymers m-cresol was released. The release rate of the microbicide increased with increasing pH of the release medium. This result can be attributed to enhanced proton dissociation of carboxyl group of the acrylic acid unit in the polymers. These polymers showed microbicidal activities for S. aureus as a positive microbe and E. coli as a negative microbe.

페놀의 산화에 대한 전극재료와 촉매의 영향

catalyst; electrolyte; phenol

The activity of catalyst for oxidation of phenol, in the presence of NaCl electrolyte, has shown only at the Ti/IrO2 anode and not at the Ti/SnO2 anode. The catalytic action of NaCl was attributed to the participation of electrogenerated ClO(-) in the oxidation of organics, phenol and its oxidation products, near the anode or/and in the electrolyte.

Poly(DL-lactide)로 피막된 고분자 매트릭스로부터 약물 방출 조절 (III) - pH 1.2와 pH 7.4에서 피막 물질이 약물 방출에 미치는 영향

chitosan; chitosan hydrochloride; sulfonated chitosan; poly(DL-lactide); prednisolone

For application of drug delivery systems, the polymeric matrices coated with poly(DL-lactide) were prepared using chitin derivatives: chitosan, chitosan hydrochloride, and sulfonated chitosan. As a model drug, prednisolone was used in solution at pH 1.2 and pH 7.4. The release rate of prednisolone was slower at pH 7.4 than at pH 1.2. The release rate of prednisolone decreased in the decreasing order of chitosan, sulfonated chitosan, and chitosan hydrochloride. The drug release rate of polymeric matrices coated with poly(DL-lactide) was approximately two times slower and the burst effect of initial period of drug release was lesser than the non-coated one. From these results, it was determined that the formulations based on the chitin derivative matrices coated with poly(DL-lactide) were a plausible solution to the drug delivery problem of sustained-release of drug dosages.

Sol-Gel법을 이용한 규소-보란 환원제의 합성

sol-gel process; reducing agent

Silyl ammonium borohydride(SAB) was synthesized via acidic sol-gel route with subsequent cation exchange. The mole ratio of 1/1/4/2/1.0x10(-2) of 3-chloropropyl-triethoxy silane/dimethyldodecylamine/H2O/THF/HCl(catalyst) was determined to be the optimum for the sol-gel synthesis of silyl quarternary ammonium chloride(SAC). SAB was then prepared by the ionic metathesis of SAC and NaBH4. SAB was identified by the B-H stretching vibrations at 2371, 2320, 2274 cm(-1) on a FT-IR spectroscopy. The content of BH4(-) group in SAB was found to be 2.0 mmol/g. The gel SAC and SAB were found to have low surface area of amorphous structure and low thermal stability at high temperature, judged by TGA, BET, SEM, and low angle XRD analyses. The gel SAB was able to reduce PhCHO to PhCH2OH effectively.

부상 공정과 막분리를 이용한 염색 폐수의 색 제거

flotation; colour removal; membrane separation

This study investigated the treatment efficiencies of dye-wastewater using a flotation process and a membrane separation process. Among the three collectors, 1-hexadecylamine, dodecylamine, and octylamine, that were added to the flotation process for the colour removal of dye, the treatment with dodecylamine showed the best result having the colour removal rate of 99%. When the mole ratio of added collector to the dye concentration was less than 1.0, the colour removal depended on the pH, but when the ratio was greater than 1.0, it was no longer sensitive to the pH variation. For the treatment with 1-hexadecylamine, which had the lowest colour removal rate of 30% in the flotation process, the variation of the flow rate in the microfiltration process had negligible effect on the colour removal efficiency. But the addition of activated carbon powder, to the solution during the microfiltration step, enhanced the colour removal rate up to 96% of dye.

디메틸페녹시/알콕시 펜단트 그룹을 갖는 난연 폴리벤즈옥사졸 전구체

poly(benzoxazole); flameretardance; cyclization reaction; heat sink

Polyhydroxyamides(PHAs) having dimethylphenoxy and/or alkoxy pendant group were synthesized by condensation polymerization at room temperature for flame retarding applications. The resulting polymer precursors were characterized by FT-IR and 1H-NMR. PHAs were converted to polybenzoxazoles by thermal cyclization reaction. This reaction was highly endothermic and it was studied by TGA and DSC. To observe the cyclization condition of the polymer precursors, they were annealed in a muffle furnace under vacuum at various temperatures for 3 h. The polymer precursor having a dimethylphenoxy pendant group was the only one that was fully cyclized at the lowest temperature, 250 ℃. In case of the polymer having dialkoxy side chains, the polymer with a longer alkoxy chain was fully cyclized at a higher temperature than the polymer with a shorter alkoxy chain. Thus the cyclization reaction can be controlled by the combination of these two pendant groups. By means of wide-angle X-ray diffraction powder patterns, the fully extended alkoxy side chains formed crystalline domains between the layers of the main chains.

질산에 의한 폐 Poly(butylene terephthalate)의 해중합

waste PBT; particle size; hydrolysis; modified shrinking unreacted core model

Waste PBT powder was depolymerized by hydrolysis using 8.91 ~ 1314 M nitric acid at various temperatures between 70 ~ 100 ℃ below its melting temperature. The degree of depolymerization increased with increasing concentration of nitric acid and reaction temperature, and decreasing particle size. The kinetics of the acid hydrolysis could be expressed by a modified shrinking unreacted core model for surface reaction-controlling step. The effective surface area is proportional to the degree of unreacted PBT and is affected by the deposition of TPA product on the PBT. The apparent rate constant increased with decreasing particle size. The activation energy of the reaction was about 108 kJ/mol. The recovery ratio of TPA was about 95%.

Preparation and Characterization of Demineralized Bone Particle Impregnated Poly(L-lactide) Scaffolds

In order to endow with new bioactive functionality from demineralized bone particle (DBP) as natural source to poly(L-lactide) (PLA) synthetic biodegradable polymer, porous DBP/PLA as natural/synthetic composite scaffolds were prepared and compared by means of the emulsion freeze drying and solvent casting/salt leaching methods for the possibility of the application of tissue engineered bone and cartilage. For the emulsion freeze drying method, it was observed that the pore size decreased in the order of 79 μm (PLA control) > 47 μm (20% of DBP) > 23 μm (40% of DBP) > 15 μm (80% of DBP). Porosities as well as specific pore areas decreased with increasing the amount of DBP. It can be explained that DBP acts like emulsifier resulting in stabilizing water droplet in emulsion. For the solvent casting/salt leaching method, a uniform distribution of well interconnected pores from the surface to core region were observed the pore size of 80~70 μm independent with DBP amount. Porosities as well as specific pore areas also were almost same. For pore size distribution by the mercury intrusion porosimeter analysis between the two methods, the pore size distribution of the emulsion freeze drying method was broader than that of the solvent casting/salt leaching method due to the mechanism of emulsion formation. Scaffolds of PLA alone, DBP/PLA of 40 and 80%, and DBP powder were implanted on the back of athymic nude mouse to observe the effect of DBP on the induction of cells proliferation by hematoxylin and eosin staining for 8 weeks. It was observed that the effect of DBP/PLA scaffolds on bone induction are stronger than PLA scaffolds, even though the bone induction effect of DBP/PLA scaffold might be lowered than only DBP powder, that is to say, in the order of DBP only > DBP/PLA scaffolds of 40 and 80% DBP > PLA scaffolds only for osteoinduction activity. In conclusion, it seems that DBP plays an important role for bone induction in DBP/PLA scaffolds for the application of tissue engineering area.

Simultaneous Removal and Recovery of Cadmium and Cyanide Ions in Synthetic Wastewater by Ion Exchange

Ion Exchange; Simultaneous Removal; Cadmium and Cyanide; Recovery

Simultaneous removal and recovery of cyanide and cadmium ions using a strong-base anion exchange resin was studied on the basis of formation of Cd-CN complexes at high pH in synthetic wastewater containing cyanide and cadmium ions. Strong-base anion exchange resin particles, of Dowex1X8-50, were contacted with synthetic aqueous solutions. For different molar ratios between cyanide and cadmium, ion exchange characteristics of cadmium-cyanide complexes were studied experimentally in a batch reactor. Treatment efficiencies of packed and fluidized beds were compared under various conditions. Several regenerants, NaSCN, NaCN, and NaOH, were used to regenerate the exhausted resin. The rates of regeneration and recovery for the various regenerants were estimated and discussed. The resin used in this work, Dowex1X8-50, can exchange about 6.6 CN(-) meq./g resin and 3.2 Cd(2+) meq./g resin of cyanide and cadmium ions as complexes, respectively. Free cyanide ion has a lower selectivity than Cd-CN complexes on the anion exchange resin. The degree of treatment efficiency applied in this study was greater in the fluidized bed than packed bed. NaSCN was the best regenerant among regenerants used for regeneration of resin saturated with Cd-CN complexes.

역삼투에 의한 스테인레스 스틸 제조공장에서 배출된 유출수의 처리

Effluent; Membrane technology; Physico-chemical treatments; Permeate flux; Removal rate

This paper investigates the possibilities of treatment of effluent from stainless steel manufacturing plants by membrane technology and physico-chemical treatments. The initial permeate flux of the effluent was 1.2 L/㎡·h. The permeate flux decreased to 0.5 L/㎡·h and stabilized after 2 hrs. The removal rates of Cr(Ⅵ), TDS and F by revere osmosis (RO) were found to be 99.8, 96.1 and 96.1%, Respectively, but that of COD was somewhat low at 79.1%. It was revealed that we could not use RO to remove phenol because the removal rate of 6.7% was too low. On the other hand, we were able to decrease the concentration of RO permeate, from 68 mg/L to 0.01 mg/L, by an ion-exchange method(0-80 BV). The average removal rates of phenol and COD using hydrogen peroxide were 95.0% and 62.8%, respectively.

열방성 액정폴리에스테르와 폴리(에틸렌 테레프탈레이트)와의 블렌드

TLCP; In-situ composite; PET

A new thermotropic liquid crystalline polymer (TLCP) having a hexyloxy side group was synthesized for the application of in-situ composite, and the blends of TLCP with poly(ethylene terephthalate)(PET) were prepared by coprecipitation from a common solvent. The thermal, dynamic mechanical properties and morphology of the blends (2, 5, 10, and 20 wt% TLCP/PET) were investigated. In the blends, the liquid crystalline phase did not reveal any significant macrophase separation and thermal degradation at the processing temperature. According to the scanning electron micrograph observation, TLCP domains in the matrix were found to be more or less finely dispersed with 0.2 ㎛ to 0.6 ㎛ in size and interfacial adhesion between the TLCP and matrix polymer was prominent. Results of dynamic mechanical properties showed that modulus of in-situ composite was enhanced with increasing TLCP content.

개시제 및 촉진제 함량 변화에 따른 불포화 폴리에스테르의 경화 거동

Unsaturated polyester; Activation energy; Reaction rate equation

The activation energy has been quantified with initiator and accelerator content. From this result, the optimum condition of initiator and accelerator contents was determined. In this initiator and accelerator contents, unsaturated polyester (UP) was cured isothermally and the conversion rate was obtained. Reaction rate equation was used for obtaining reaction order. Calculated value was obtained from this reaction order, and it was compared with experimental value. Curing reaction of UP was satisfactory with n-order reaction and average reaction order value was about 1.38. In addition, the effect or initiator and accelerator contents on the mechanical properties was investigated by measuring glass transition temperature and hardness. The plasticizer effect was confirmed by the excessive initiator content.

펜턴산화와 막분리의 혼성공정에 의한 도금폐수처리

Fenton's oxidation; membrane separation; supernatant; reverse osmosis (RO)

The objective of this study is to propose optimum operating conditions in the treatment of the plating wastewater by using the hybrid process of Fenton''s oxidation and membrane separation. The supernatant after pre-treatment of Fenton''s oxidation was fed to membrane separation process. Optimum conditions for Fenton''s oxidation were pH 4 with dosage of H₂O₂ and FeSO₄ 7H₂O being 550mg/L and 500mg/L, respectively. The best conditions for the supernatant treatment were found to be pH 8.5 and operating pressure of 4.2 kg_f/㎠ in the membrane separation when reverse osmosis (RO) membrane of spiral wound type was used. The final treatment water quality was 14.44 mg/L, 0.02mg/L, 0.01mg/L, 0.16mg/L and 0.43mg/L in concentrations of COD, Cr³⁺, Cr⁶⁺, CN^- and Zn²⁺, respectively and pH 7.8. It was found that the final water was recyclable to the plating process without further adjustment of pH.

Biphenylrl를 포함하는 공액 공중합체의 합성 및 전계발광 특성

light-emitting diode; conjugated polymer; α-elimination; honer-emmons reaction

Poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene)(MEH-PPV) and poly(2-methoxy-5-(2-ethylhexyl-oxy)-1,4-phenylene vinylene-co-1,1''-biphenyl-4,4''-ylene vinylene) [poly(MEHPV-co-BPV)] with a different feed ratio of biphenyl group in the main chain were synthesized by α-elimination reaction. Poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-alt-1,1''-biphenyl-4,4''-ylene vinylene) [poly(MEHPV-alt-BPV)], which has alternating repeat unit, and poly(1,8-octanedioxy-2-methoxy-1,4-phenylene-1,2-ethenylene-1,1''-biphenyl-4,4''-ylene-1,2-ethenylene-3-methoxy-1,4-phenylene) [poly(BFMP8-BPV)] and poly(1,12-dodecaedioxy-s-methoxy-1,4-phenylene-1,2-ethenylene-1,1''-biphenyl4,4''-ylene-1,2-ethenylene-3-methoxy-1,4-phenylene)[poly(BFMP12-BPV)] containing both conjugated and non-conjugated group in the main chain were synthesized by the Honer-Emmons were examined. The solubility of poly(MEHPV-co-BPV)s in common organic solvents decreased rapidly with the increasing amount of BPV units in the copolymer. Emission spectrum of poly(MEHPV-co-BPV)s had two peaks corresponding to MEPHV(586 nm) and BPV(469, 495 nm) moiety, respctively. However, LED fabricated with poly(MEHPV-alt-BPV)showed relatively sharp single peak(544 nm) in the middle of the two peaks.

Polymerization of Ethylene Initiated with Trisiloxane-bridged Heterometallic Dinuclear Metallocene

The new trisiloxane-bridged heterometallic dinuclear metallocenes, hexamethyltrisiloxanediy-1(cyclopentadienyltitanium trichloride) (cyclopentadienylidenyl zirconium dichloride), Cl₂Ti-Cp(CH₃)₂Si-O-Si(CH₃) ₂-O-Si(CH₃)₂-Cp-ZrIndCl₂ (1) and hexamethyltrisiloxanediyl(cyclopentadienylindenylhafnium dichloride) (cyclopentadienylindenyl zirconium dichloride), Cl₂lndHf-Cp(CH₃₂Si-O-Si(CH₃) ₂-O-Si(CH₃)₂-Cp-ZrlndCl₂ (2) connecting two dissinilar metallocenes were synthesized and used for ethylene polymerization in the presence of modified methylaluminoxane (MMAO) cocatalyst. The catalytic activity of heterometallic dinuclear metallocenes, 1 and 2 was lower than that of corresponding mononuclear metallocene as well as two physically mixed catalysts. CpTiCl₃/Cp₂ZrCl₂ and Cp₂HfCl₂ZrCl₂. On the ofther hand, MWDof PE obtained with 1 and 2 remarkably broader (M_w/M_n became up to 9.4)than those of PEs prepared with the corresponding mononuclear metallocenes and mixed catalysts. With analysis by GPC and CFC, it was found that PE produced by the heterometallic dinuclear metallocenes exhibited the definite bimodal GPC curves that should cause the brodening of MWD.

the Effect of Fluid Shear Stress on Endothelial Cell Adhesiveness to Modified Polyurethane Surfaces

Generally vascular grafts with a relatively large inner diameter (>5mm) have been successfully employed for replacement in the human body. However, the use of small diameter grafts is limited, because these grafts rapidly occlude due to the thrombosis. the ideal blood-contacting surface of a prosthesis would be an endothelial cell (EC) lining, because the confluent monolayer of healthyl ECs that culture natural blood vessels represents the ideal nonthrombogenic surface. For vascular graft application, the stable EC adhesion on surface under flow conditions is very important. In this study, the adhesive strength of ECs attached on polymer surfaces coated with collagen type IV (Col IV), fibronectin (Fn), laminin (Ln), and treated with corona was investigated onto polyurethane (PU) films. The EC-attached PU surfaces were mounted on parallel-plate flow chambers in a flow system prepared for cell adhesiveness test. Three different shear stresses (100, 150, and 200 dyne/㎠ ) were applied to the flow chambers and each shear stress was maintained for 120 min to investigate the effect of shear stress and surface treatment condition on the EC adhesion strength. It was observed that the EC adhesion strength on the surface-modified PU films was in the order of Ln Fn>Col IV> corona>>control. More than 70% of the adhered cells were remained on surface-modified PU surface after applying the shear stress, 200 dyne/㎠ for 2 hrs, whereas the cells were completely detached on the control PU surface within 10 min after applying the same shear stress. It seems that the type of adsorbed proteins and hydrophilicity onto the PU surfaces play very important roles for cell adhesion strength.

Preparation and Gas Separation Properties of Asymmetric Polysulfone Membranes by a Dual Bath Method

Defect-free Asymmetric Membranes; Dual Bath Method; Wet/Wet Phase Inversion Technique

Defect-free skinned asymmetric gas separation membranes were prepared by a dual bath coagulation method that is a wet/wet phase inversion technique. The membranes were cast from a polysulfone/N,N-dimethyl-acetamide solution. In two sequent nonsolvent baths, the first bath using iso-propanol (IPA) leads to the formation of a dense skin top layer and the second bath using water makes the actual polymer precipitation. The top skin layer thickness was governed by changing the immersion time of the first IPA bath. We suggest that the growth rate of the skin layer is to be determined by a diffusion process.

Drug Release from Nanoparticles of Poly(DL-lactide-co-glycolide)

Poly(DL-lactide-co-glycolide); Nanoparticles; Dialysis Method; Clonazepam; Controlled Drug Release

Nanoparticles of Poly(DL-lactide-co-glycolide) (PLGA) were prepared by dialysis method without surfactant. The size of PLGA nanoparticles prepared from dimethylacetamide (DMAc), dimethylformamide (DMF), and dimethylsulfoxide (DMSO) as an initial solvent was smaller than that of acetone or 1,4-dioxane. Selected initial solvent used to dissolve the copolymer significantly affects the size of nanoparticles. Also, the size of PLGA nanoparticles was changed according to the copolymer composition. It was shown that PLGA nanoparticles have spherical shpaes from the results of scanning electron microscope (SEM) and transmission electron microscope (TEM) observations. From these results was shown the potential that the PLGA nanoparticles could be formed successively by dialysis method without surfactant. The drug-loading contents were also dependent on the copolymer composition and initial feeding amount of the drug. The greater lactide ration on the copolymer composition led to higher drug loading contents. Also, the higher the initial feeding amount of drug, the higher the drug loadging contents. Clonazepam (CNZ) was used as a model drug. CNZ was slowy released in higher lactide ratio in the copolymer composition and in the higher drug loading contents.

Electrochemical Removal of Sodium Ion from Fermented Food Composts

Electrochemical Removal; Foodwastes; Composts; Desalting; Sodium Chloride

Fermented food composts, to be recycled into fertilizer and animal feed, require sodium chloride concentrations to be less than 1 wt% due to several toxicities. Electrochemical methods are used to remove sodium ions from fermented food composts. By washing the compost with tap water (with no electric current applied), 48% of the initial sodium ion is removed. With an electric current density of 3 mA/㎠ (the distance between the electrodes is 16cm), the removal efficiency increases to 96% for a 36 h operation. Major factors influencing the efficiency are the treatment time and the electric current density. Removal efficiency increases with energy demand to yield 96% removal at 60 Kwh/㎥. Due to the difference in relative ionic mobility, less than 9% of calcium is removed, during the same operation time, which supports the feasibility of this method.

Lipid Nanospheres Containing Vitamin A or Vitamin E: Evaluation of Their Stabilities and In Vitro Skin Permeability

encapsulation; fat-soluble vitamin A and E; nanosphere; phospholipid; skin permeability

To encapsulate a fat-soluble vitamin, lecithin composed of several hydrogenated phospholipids obtained from soybean and an adjuvant were used. The resulting lipid nanospheres were about 200-300 nm in size and had a monodispersed-size distribution. Increasing the proportion of the oil phase produced large lipid droplets. The size and zeta-potential of a lipid nanosphere containing a 10 w/w% oil phase decreased with an increased proportion of lecithin and then leveled off with a lecithin content of about 1.2 w/w%. Furthermore, an attempt was made to improve the stability of a lipid nanosphere consisting of vitamin and lecithin by coating the surface of the lipid layer with several emulsifiers that had different hydrophilic lipophilic balance (HLB) values and molecular weights. The lipid nanosphere emulsion prepared with only lecithin showed a significant coalescence over a storage period of 60 days. However, the size of the lipid nanosphere was smaller and its in vitro stability was significantly improved compared with other formula, when Tween 80 was used as the cosurfactant. In particularly, the lipid nanosphere with the minimum size and maximum stability had a 1 : 1 content ratio of lecithin to Tween 80. From in vitro permeation experiments using rat skink it was found that the permeation of the vitamin from a lipid nanosphere was greater than that of free vitamin A or E, and varied depending on the composition and size of the lipid nanosphere.

Albumin Release form Multiblock Copolymer Consisting of Poly(γ-benzyl L-glutamate) and Poly(ethylene oxide)

Biodegradable hydrogel based on moltiblock copolymer composed of poly(γ-benzyl L-glutamate)(PBLG) as the biodegradable and hydrophobic part, and poly(ethylene oxide)(PEO) as the swellable and hydrophilic part was synthesized by polymerization of γ-benzyl L-glutamate N-carboxyanhydride(BLG-NCA) initiated by bis[poly(ethylene oxide)bis(amine)] and characterized. From infrared measurement, it was found that the polypeptide block exists in the α-helical conformation, as in PBLG homopolymer. Water content of the copolymers was dependent on the PEO content in the copolymers. The amount of albumin released from the multiblock copolymers increased with an increase of PEO content in the block copolymer. Albumin was mainly released from biodegadable hydrogel through the diffusion mechanism.

Aggregation Characteristics of Thionine-PVS and -SDS Systems in the Presence of Chitosan

The spectral behaviors of cationic dyes of thionine (Th) with varying concentration of polyvinylsulfate (PVS) and sodium dodecylsulfate (SDS) had been studied by absorption spectroscopy. Aggregation characteristics of Th-PVS-chitosan and Th-SDS-chitosan systems were investigated by degree of deacetylation of chitosan. Chitosan A,B and C with degree of deacethylation (0.87, 0.79, and 0.66) used were prepared by using NaOH 30, 40, and 50%, respectively. When chitosan A, B, and C were added to Th-SDS systems for S/D<80 system, the absorbance of Th-SDS-chitosan A, B, and C systems compared with that of Th-SDS systems showed the decreasing tendency. On the other hand, when chitosan A, B, and C were added to Th-PVS systems for P/D=0∼3000, the absorbance of Th-PVS-chitosan A, B, and C systems relative to Th-PVS systems showed the highly increasing tendency.