• 대한화학회지
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• 제28권2호
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• pp.102-108
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• 1984

$ZnCe_{1+y}O_2$상에서 CO산화반응 속도가 $300{\sim}500^{\circ}C$영역에서 측정되었다. 산화반응 속도는 CO에 1차 O2에 0.5차를 나타내는 속도식에 따랐으며 격자점의 산소와 Zn 도프에 기인되어 생성된 Vo-2e' 결함이 CO 및 O2의 활성화 sites로 작용되었다. 전기전도도 데이타와 rate law로 부터 산화반응 메카니즘이 규명되었으며 율속과정이 제안되었다

• Journal of Microbiology and Biotechnology
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• 제1권1호
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• pp.54-62
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• 1991

Cyclodextrin glucanotransferase(CGTase) derived from Bacillus macerans was immobilized by (1) covalent linkage on chitosan and chitin with glutaraldehyde, (2) adsorption on DEAE-cellulose and Amberite IRA 900 after succinylation, and (3) entrapment on alginate and polyacrylamide by cross linking. Adsorption on Amberite IRA 900 and covalent linking on chitosan were identified to be the most suitable immobilization methods considering the yield of activity and stability of immobilized CGTase. The enzymatic properties of immobilized CGTase were investigated and compared with those of the soluble CGTase. Thermal stability of CGTase immobilized on chitosan was increased from 50 to $55^{\circ}C$, and the optimum temperature of CGTase immobilized on Amberite IRA 900 was shifted from 55 to $50^{\circ}C$. The effect of molecular size of soluble starch (substrate) on immobilized CGTase investigated using partially liquefied substrates with different dextrose equivalent(DE). Cyclodextrin(CD) conversion yield augmented according to the increase of DE level for immobilized CGTase on Amberite IRA 900. CD conversion yield of partially cyclized starch with soluble CGTase was higher compared with liquefied one with ${\alpha}-amylase$.

• Journal of Pharmaceutical Investigation
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• 제41권2호
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• pp.91-94
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• 2011

The purpose of this study was to investigate the effect of peptide charge on the interaction between peptide and poly(D,L-lactide-co-glycolide) (PLGA) for evaluating mechanism of acylated peptide formation in PLGA matrix. As a model peptide, octreotide, a synthetic somatostatin analogue and active ingredient of commercial PLGA product, was used. The disulfide group of octreotide was reduced with dithiothreitol and the sulfhydryl groups were modified with N-${\beta}$-maleimidopropionic acid (BMPA) to neutralize octreotide with positive charge in physiological conditions. The BMPA-conjugated octreotide was identified by measuring the molecular mass with liquid chromatography-mass spectrometry. In the interaction study with PLGA, native octreotide showed initial adsorption to PLGA and substantial production of acylated peptides (56% of overall peptide), whereas BMPA-conjugated octreotide showed minimal adsorption to PLGA and no acylation products for 42 days. Consequently, the neutralization of octreotide completely inhibited the peptide acylation by preventing interaction of peptide with PLGA. In conclusion, this study demonstrates that the initial polymer interaction of peptide is important step for peptide acylation in PLGA matrix and suggests the modulation of peptide charge as strategy for inhibiting the formation of acylated peptide impurities.

• Applied Biological Chemistry
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• 제36권4호
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• pp.255-259
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• 1993

키틴 분해 효소활성이 높은 균주로 분리동정한 Aeromonas salmonicida YA7-625의 chitobiase를 ammonium sulfate침전, affinity adsorption, DEAE-cellulose chromatography, hydroxylapatite chromatography, gel filtration 과정을 통해 수율 47.2% 및 정제도 31.5로 분리, 정제 하였다. 정제된 chitobiase는 pH6.0, $40^{\circ}C$에서 최대의 활성을 나타내었고 분자량은 15,000 daltons로 추정되었다. 금속이온과 저해제들의 효과를 검토결과 효소의 활성에는 cystein, glutamic acid, aspartic acid, serine, tryptophan 및 tyrposine 잔기 등이 관여하는 것으로 유추되었다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.1-18
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• 2006

A novel transmission electron microscopy technique for the visualization of polymers adsorbed on secondary fines has been developed. This technique has been utilized in observing the adsorption behavior of various wet-end additives. The technique is sensitive enough not only to allow differentiation between linear and branched polymers, but also to observe differences in the adsorption behavior and conformational characteristics of particular polymeric derivatives. Conformational changes of a cationic polyacrylamide (CPAM) were examined in response to variations in wet-end conditions, such as mixing time and system conductivity. The molecular conformations of cationic starch and cationic guar gum were also examined by this technique. The technique has been employed to observe the effects of silica microparticles on the conformational characteristics of CPAM (drainage/retention aid) pre-adsorbed on secondary fines. The transmission electron microscopy method is a viable tool for investigating the macromolecular events that make up a large part of wet end chemistry in papermaking.

• 한국수소및신에너지학회논문집
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• 제21권1호
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• pp.72-79
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• 2010

This paper is studying the selective separation of methane and carbon dioxide which are the main ingredients of biogas. Adsorption performance of molecular sieve 13x for carbon dioxide seems to be reasonable. In this experiments carbon dioxide contains about 3~5 ppm of methane and it is impossible to obtain high purity carbon dioxide. Applying the low temperature technique, it is possible to separate methane and carbon dioxide from bio gas. PRO II simulation shows results a small change of liquefaction temperatures and no difference with the used thermodynamic models. Applying low temperature technique, It is possible to separate carbon dioxide and methane from biogas.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.210.2-210.2
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• 2014

Recently, molybdenum disulfide (MoS2) nanostructures have been investigated for applications of lithium-ion batteries, solar cell, and gas sensors. In this regard, we have studied atomic and electronic properties of MoS2 nanostructures with adsorbed atoms and molecules using density functional theory calculations. Our calculations reveal that the several atoms such as H, C, N, and F are chemically bound to several sites on the two-dimensional (2D) MoS2 surface. On the other hand, various contamination molecules such as CO, CO2, NO, NO2, and NH3 do not bind to the surface. Next, adsorption of various molecules on the one-dimensional (1D) armchair MoS2 nanoribbon is investigated. Contrary to the case of 2D MoS2 monolayer surface, some molecules (CO and NO) are bound well to the edge of the MoS2 nanoribbon. We find that the molecular states due to adsorption are located near the Fermi level, which makes the band gap narrower. Therefore, we suggest that monolayer MoS2 nanoribbons be used as the gas sensors or detectors.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권5호
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• pp.466-469
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• 2006

The bed stability of Streamline DEAE (p = 1.2 g/mL) in a 20mm (i.d.) glass expanded bed contactor, and its performance on the recovery of glucose 6-phosphate dehydrogenase (G6PDH) from unclarified yeast homogenate were investigated. A residence time distribution study showed that a stable expanded bed was achieved. The theoretical plate and Bodenstein numbers determined were 25 and 53, respectively. A recovery yield of 87% and purification factor of 4.1 were achieved in the operation using 5% (w/v) biomass concentration feedstock. The performance of the anion exchange EBAC was still considerable good at a biomass concentration as high as 15% (w/v).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.112-112
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• 2011

The interaction of water molecules with solid surfaces has been a subject of considerable interests, due to its importance in the fields from atmospheric and environmental phenomena to biology, catalysis and electrochemistry [1,2]. Among various kinds of surfaces, a lot of theoretical and experimental studies have been performed regarding water on MgO(100), however, to date, there has been no direct observation of water molecules on MgO by scanning tunneling microscope (STM) as compared with those on metal surface. Here, we will present the direct observation and manipulation of single water molecules on ultrathin MgO(100) films using low-temperature scanning tunneling microscope (LT-STM) [3]. Our results rationalize the previous theoretical predictions of isolated water molecules on MgO including the optimum adsorption sites and non-dissociative adsorption of water. Moreover, we were able to dissociate a water molecule by exciting the vibrational mode of water, which is unattainable on metal surfaces. The enhanced residual time of tunneling electrons in molecules on the insulating film is responsible for this unique pathway toward dissociation of water.

• 한국식품과학회지
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• 제28권3호
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• pp.604-608
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• 1996

부추에 존재하는 항미생물 활성물질에 관한 정보를 얻고자 항미생물 활성의 검색 및 항미생물 활성물질의 탐색을 시도하였다. 부추 MeOH추출물의 항미생물 활성을 17종의 미생물을 대상으로 검색한 결과 Gram 양성의 세균, Gram 음성의 세균 그리고 효모에 대해서 광범위한 미생물 증식 억제능을 나타냈다. 부추를 MeOH로 추출, 용매분획하여 얻어진 활성을 silica gel adsorption chromatography, Sephadex LH-20 chromatography, TLC, silica gel partition chromatography, HPLC 등의 방법으로 분석한 결과 부추에 존재하는 항비생물 활성물질은 약간의 극성을 띠는 중성물질로 200-400정도 분자량을 갖는 6종의 항미생물 활성물질의 존재가 확인되었다.