• Rapid Communication in Photoscience
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• 제4권1호
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• pp.19-21
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• 2015

Zeolite is an ideal host material for encapsulating nano-size metal catalyst species because of its defined microporous structure, prominent adsorption/condensation properties, high surface area, chemical/thermal stability, and transparency to light. In this study, $TiO_2$ photocatalyst was incorporated in highly hydrophobic Y zeolite and its photocatalytic activity was examined in the photocatalytic oxidation of olefins under UV-light irradiation using molecular oxygen as an oxygen source. $TiO_2$ nanoparticles incorporated in hydrophobic Y zeolite exhibited a markedly enhanced photocatalytic activity compared with bare $TiO_2$ owing to its excellent affinity toward organic moieties, which facilitates the mass transfer of organic substrates and allows them to efficiently access to the neighboring active $TiO_2$ surface.

• 약학회지
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• 제39권3호
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• pp.306-313
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• 1995

The aim of the present study was to produce low molecular weight cathepsin B inhibitor. A strain of Streptomyces aburabiensis isolated from soil in Korea was selected and the optimum condition for the production of the inhibitor was evaluated. Glucose and soytone were selected as best carbon and nitrogen sources, respectively. From the kinetic analysis in batch fermentation, it was found that the specific cathepsin B inhibitor production rate (q$_{p}$) was linearly related to specific growh rate ($\mu$). The inhibitor in culture filtrate was purified by adsorption on activated charcoal, butanot extraction, silica gel chromatography, ion exchange chromatography using Dowex-1 (Cl form) and Amberlite IRC-50 (H$^{+}$ form), and preparative TLC. From the UV, IR, Mass spectroscopy and $^{1}$H-NMR, the inhibitor was thought to be a new inhibitor of which molecular weight was 199.

• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.587-591
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• 1999

A molecular dynamics simulation study on the structure and dynamics of Na+ ions in non-rigid dehydrated Na12-A zeolite framework at 298.15 K was conducted using the same method reported in previous studies on rigid and non-rigid Na12-A zeolite frameworks. The agreement between the experimental and calculated results for the zeolite-A framework atoms of structural parameters for non-rigid dehydrated Na12-A zeolite is generally quite good, and for the adsorbed Na+ions the agreement is acceptable. The calculated bond lengths are generally in good agreement with the experimental results and other theoretical data. The calculated IR spectrum by Fourier transform of the total dipole moment autocorrelation function shows two major peaks around 2700 cm-1 and 7000 cm-1. The former appeared in the calculated IR spectra of non-rigid zeolite-A framework only system and the latter remains unexplained except, perhaps, indicating a new formation of a vibrational mode of the framework due to the adsorption of Na+ ions. The peaks above 6200-6800 cm-1 in non-rigid dehydrated Nal2-A zeolite are much larger than those in non-rigid dehydrated H12-A zeolite.

• 한국지하수토양환경학회지:지하수토양환경
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• 제11권2호
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• pp.13-21
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• 2006

다환방향족 탄화수소는 화석연료의 사용 등으로 자연계에 유출되며, 매우 낮은 용해도로 인해 토양과 강한 결합을 형성하여 장기적으로 영향을 준다. 이러한 PAHs로 오염된 토양을 복원하기 위해 계면활성제를 사용한 토양세척 공법을 사용하게 되며, 공정 시 계면활성제의 사용으로 전체 복원 비용이 증가하게 된다. 이에 토양복원 시 사용된 계면활성제의 재사용을 위한 연구들이 많이 진행되고 있다. 본 연구에서는 활성탄을 이용한 계면활성제 재사용 기술을 개발하였다. 활성탄으로는 원료물질과 활성방법이 같고 입자 크기가 다른 세 가지 GAC(Darco 4-12, 12-20, 20-40 메쉬)를 사용하였으며, PAH로는 phenanthrene을 계면활성제로는 Triton X-100을 사용하여 회분식으로 실험을 수행하였다. 이때 Triton X-100 용액에서 phenanthrene의 선택적 흡착정도를 보기위해 선택도를 사용하였다. 실험결과 입자 크기가 작을수록, 비표면적과 기공 부피가 클수록 높은 선택도를 나타내었다. 선택도는 세 활성탄 모두 1보다 높아 Triton X-100 용액으로부터 phenanthrene이 효과적으로 분리됨을 알 수 있었다. 본 연구의 결과, PAHs와 같은 소수성물질로 오염된 토양의 세척시 발생하는 계면활성제 용액을 적절한 특성을 가진 활성탄을 이용하면 오염물질을 선택적으로 제거시킬 수 있음을 알 수 있다. 따라서 활성탄을 이용한 선택적 흡착을 이용하면 토양 세척시 계면활성제 사용량을 줄이게 되어 복원 비용을 절감하는 효과를 가져올 것으로 예상된다.

• 청정기술
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• 제19권1호
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• pp.38-43
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• 2013

저등급 석탄의 건조 후 안정화하기 위한 방법으로 탄화수소의 기상흡착에 대한 연구를 수행하였다. 밀폐된 5 L의 데시케이터 용기에 건조 석탄과 안정화제를 넣고 주어진 온도에서 일정 시간 동안 유지시킨 후 석탄의 표면 특성과 자연발화 경향을 살펴보았다. 기상흡착 후 건조 석탄의 표면적은 미세기공을 중심으로 감소하였다. 흡착시간과 온도가 증가할수록 안정화 석탄의 자연발화 경향은 감소하는 것으로 나타났다. 안정화제의 종류에 따른 자연발화 경향은 큰 차이를 보이지 않았다. 분석 결과에 의하면 석탄의 0.5 wt% 이하인 소량 흡착으로 안정화 효과를 나타내는 것이 확인되었으며, 저온에서 기상흡착에 의한 안정화 현상은 저분자량의 탄화수소 흡착에 의한 것으로 나타났다.

• Smart Structures and Systems
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• 제8권1호
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• pp.17-37
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• 2011

The microcantilever (MCL) sensor is one of the most promising platforms for next-generation label-free biosensing applications. It outperforms conventional label-free detection methods in terms of portability and parallelization. In this paper, an overview of recent advances in our understanding of the coupling between biomolecular interactions and MCL responses is given. A dual compact optical MCL sensing platform was built to enable biosensing experiments both in gas-phase environments and in solutions. The thermal bimorph effect was found to be an effective nanomanipulator for the MCL platform calibration. The study of the alkanethiol self-assembly monolayer (SAM) chain length effect revealed that 1-octanethiol ($C_8H_{17}SH$) induced a larger deflection than that from 1-dodecanethiol ($C_{12}H_{25}SH$) in solutions. Using the clinically relevant biomarker C-reactive protein (CRP), we revealed that the analytical sensitivity of the MCL reached a diagnostic level of $1{\sim}500{\mu}g/ml$ within a 7% coefficient of variation. Using grazing incident x-ray diffractometer (GIXRD) analysis, we found that the gold surface was dominated by the (111) crystalline plane. Moreover, using X-ray photoelectron spectroscopy (XPS) analysis, we confirmed that the Au-S covalent bonds occurred in SAM adsorption whereas CRP molecular bindings occurred in protein analysis. First principles density functional theory (DFT) simulations were also used to examine biomolecular adsorption mechanisms. Multiscale modeling was then developed to connect the interactions at the molecular level with the MCL mechanical response. The alkanethiol SAM chain length effect in air was successfully predicted using the multiscale scheme.

• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.77-81
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• 2006

The commercially available Amberlite XAD-2 and XAD-4 resins were modified with macrocyclic protoporphyrin IX (PPIX) or tetrakis(p-carboxyphenyl) porphyrin (TCPP) to enhance the adsorption capacity for phenol and chlorophenols. The chemically modified polymeric adsorbents (XAD-2+PPIX, XAD-2+TCPP, XAD-4+PPIX, and XAD-4+TCPP) were applied to the solid phase extraction as an adsorbent material for the preconcentration of phenol and chlorophenols in environmental waters. Generally, the synthesized adsorbents showed higher recoveries than underivatized adsorbents, XAD-2 and XAD-4, without matrix interferences. Especially, XAD-4+PPIX showed more than 90% recoveries for all compounds used in this study including hydrophilic phenol. The major factor for the increase of the adsorption capacity was the increase of $\pi$-$\pi$ interaction between adsorbents and samples due to the introduction of the porphyrin molecule. However, the breakthrough volumes and recovery values of the XADs+TCPP columns were slightly decreased for the bulky chlorophenols such as TCP and PCP. Using molecular mechanics methods, the structures of TCPP and PPIX were compared with that of porphine, the parent molecule of porphyrin. Four bulky p-carboxyphenyl groups of TCPP were torsional each other, thus the molecular plane of TCPP were not on the same level. In conclusion, the decrease of breakthrough volumes and recovery values of XADs+TCPP columns for bulky phenols can be explained by the steric hindrance of the $\pi$-$\pi$ interaction between porphyrin plane and the phenols.

• 한국결정성장학회지
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• 제9권6호
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• pp.590-596
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• 1999

염화물욕 아연도금에서 순환셀 도금장치에 3전극계를 부착하여 첨가제 효과를 조사하였다. 도금액에 폴리에틸렌글리콜(이하 PEG)의 첨가는 도금 과전압을 증가시키고 수소발생을 억제하는데 이것은 첨가제에 의하여 아연 이온의 이동을 억제하거나 음극에 첨가제 흡착에 의한 것으로 생각된다. 그러나 PEG는 사용되는 도금액의 물성(전도도, 점도, 비중)에는 영향을 미치지 않는 것으로 나타났다. 도금층에 미치는 영향은 표면 조도가 개선되고, 광택도가 감소된다. 이러한 영향은 PEG 분자수가 클수록 증가되나 분자수가 다른 PEG의 혼합첨가제에서는 광택도 감소가 줄어든다. 이러한 것은 도금층 결정면의 방향성, 입자의 크기 및 형태가 PEG 분자 수에 따라 다르게 나타나는 것에 기인하는 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.768-774
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• 2017

Horseradish peroxidase (HRP) catalyzes the oxidation of aromatic compounds by hydrogen peroxide via insoluble polymer formation, which can be precipitated from the wastewater. For HRP immobilization, poly(lactic-co-glycolic acid) (PLGA) fine carrier supports were produced by using the Nano Spray Dryer B-90. Immobilized HRP was used to remove the persistent 2,4-dichlorophenol from model wastewater. Both extracted (9-16 U/g) and purified HRP (11-25 U/g) retained their activity to a high extent after crosslinking to the PLGA particles. The immobilized enzyme activity was substantially higher in both the acidic and the alkaline pH regions compared with the free enzyme. Optimally, 98% of the 2,4-dichlorophenol could be eliminated using immobilized HRP due to catalytic removal and partly to adsorption on the carrier supports. Immobilized enzyme kinetics for 2,4-dichlorophenol elimination was studied for the first time, and it could be concluded that competitive product inhibition took place.

• Journal of Microbiology and Biotechnology
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• 제16권1호
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• pp.15-19
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• 2006

A ferredoxin adsorbed hetero self-assembled layer was fabricated on chemically modified Au substrate, 4-Aminothiophenol (4-ATP) was deposited onto Au substrate and then N-succinimidyl-3-[2-pyridyldithio] propionate (SPDP) was adsorbed on the 4-ATP layer, since SPDP was used as a bridging molecule for ferredoxin adsorption, Ferredoxin/SPDP/4-ATP structured hetero layer was constructed because of strong chemical binding of ferredoxin, SPDP, and 4-ATP, The surface of the ferredoxin-adsorbed SPDP/4-ATP layer was observed by scanning tunneling microscopy, The hetero film formation was verified by surface plasmon resonance measurement. The current flow and rectifying property based on the scanning tunneling spectroscopy I-V characteristics was achieved in the proposed hetero layer. Thus, the hetero layer structure of ferredoxin functioned as a molecular diode with rectifying property, The proposed molecular diode can be usefully applied for the development of molecular scale electronic devices.