• 농업과학연구
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• 제11권2호
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• pp.315-321
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• 1984

0.1M tetraethylammoniumperchlorate (TEAP)를 지지전해질로 한 acetonitrile속에서 direct current (DC), differential pulse (DP) polarography 및 cyclo voltammetry (CV) 방법에 의한 Sumithion의 전기화학적 환원반응은 -1.0~-2.50volt vs. Ag-AgCl 범위에서, 제1단계로 P-Oph 결합의 분열에 의하여 dimethylthiophosphonyl radical과 p-nitro-m-cresol이 생성되는 1전자 유사가역반응이 일어나고, 제2단계는 전형적인 1전자 비가역 반응으로 dimethylthiophosphonyl radical이 dimethylthiophosphonate가 되며, 제3단계 반응은 2.7volt vs. Ag-AgCl의 높은 음전위에서 p-nitro-m-cresol은 4전자 비가역반응에 의한 nitro group의 환원으로 p-hydroxy-amino-m-cresol이 생성되는 총 3단계의 비가역적인 electron-transfer chemical reaction (EC) 메카니즘으로 전극반응이 진행됨을 알았다.

• 대한화학회지
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• 제24권6호
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• pp.457-462
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• 1980

Phosphoryl chloride와 allyl alcohol, 2,3-dibromopropanol, 2-pyrrolidone, ethylenimine을 반응하여 여러가지 phosphate와 phospshoric amide를 합성하였다. 합성한 화합물은 모두 열에 불안정하였으며, allyl phosphorodichloridate와 diallyl phosphorochloridate는 증류하면 상당량의 중합체가 생겼다. IR 스펙트라에서는 $1,300∼1,200 cm^{-1}$에서 P=O stretching의 특성밴드가 나타났으며 NMR 스펙트라는 인원자의 long range coupling 효과로 인해 복잡한 피이크를 보였다. 2,3-dibromopropyl phosphordichloridate의 mass 스펙트럼에서는 분자이온 피이크를 볼 수 없었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.565-568
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• 1998

The effects of denudation anneals on the properties of 256Mega-bit level devices were investigated. Based on the three-step anneal model, the redistribution of oxygen atom and the defect free zone depth were calculated. A significant outdiffusion of oxygen atoms is occurred during the denudation anneals at high temperature. Junction leakage current of P+/N-Well and N+/P-Well junctions, as a function of denudation anneal temperature, was decreased with increase of anneal temperature and is closely related with the behaviors of oxygen atoms. Also it is found that the denudation anneal at high temperature very effective for the fabrication of reliable 256Mega-bit level devices.

• 대한화학회지
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• 제44권3호
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• pp.184-189
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• 2000

메타-치환 피리딘의 치환기 효과를 조사하기 위하여 ab initio 계산을 수행하였다. 여러 메타-치환 피리딘의 최적화 된 구조로부터 정전기전위를 계산하였으며, 그 결과 피리딘의 질소 원자에서 최소정전기전위 값을 나타내었다. 최소정전기전위 값을 나타내었다. 최소정전기전위 값을 Hammett 치환기 상수, ${\sigma}_m$ 및 ${\Delta}pK_a$ 와 비교한 결과 흘륭한 상관성이 있음을 알았으며, 따라서 최소정전기전위가 치환기 효과를 나타내는 유용한 척도로 사용될 수 있음을 알 수 있었다.

• Applied Biological Chemistry
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• 제41권4호
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• pp.209-212
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• 1998

Methylan, a polysaccharide produced from Methylobacterium organophilum, was chemically modified by adding diethylaminoethyl (DEAE) group to the backbone of methylan. The structure of DEAE-methylan was determined by measuring its nitrogen content obtained from an elemental analysis. From the analysis of mass spectrum, the DEAE group in DEAE-methylan was also confirmed by determining diethylaminoethene as a separate form of DEAE. Mercury adsorption of DEAE-methylan was higher than that of native methylan. This fact was valid for a variety of pH, reaction times, metal concentrations, and polysaccharide concentrations. In particular, native methylan and DEAE-methylan adsorbed 16% (w/w) and 18% (w/w) for mercury after 30 min at pH 7, respectively. The increase in mercury adsorption of DEAE-methylan may be resulted from mercury adsorption by the lone pair electron of nitrogen atom in DEAE group.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.341-344
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• 2001

제일원리 슈도퍼텐셜 계산을 통해 강유전성 격자 불안정성의 미시적 기원과 페로브스카이트 PbTiO$_3$의 전자구조를 연구했다. 의사 얀-텔러 효과를 이용해서 격자 불안정성을 논의한다. 얀-텔러 효과의 원인은 O 원자의 p 궤도함수와 Ti 원자의 d 궤도함수의 혼성결합이다. 얀-텔러 효과는 브릴루앙 영역의 중심에서 가장 중요해진다는 것을 알 수 있었다.

• 미생물학회지
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• 제21권1호
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• pp.27-35
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• 1983

The stoichiometry between the consumption of CO and $O_2$ and the production of $CO_2(2CO+O_2{\rightarrow}2CO_2)$) showed that Pseudomonas carboxydohydrogena grows as a typical aerobic CO oxidizer with CO. The optimal concentration of CO for growth was found to be 30% in gas mixture with air. The initial buffer concentration of the culture medium did not affect the growth of this bacterium. P. carboxydohydrogena is an obligate aerobe and dose not use nitrate as a terminal electron acceptor. The CO dehydrogenase is an inducible and soluble enzyme. The reaction rate and stability were maximal at pH7.5, and the Arrhenius plot revealed an activation energy of 37.7kJ/mol (9.0 Kcal/mol). The crude enzyme used methylene blue, thionin, and toluylene blue as electron acceptors for the oxidation of CO to $Co_2$ under anaerobic conditions. It was found that water must be the source of the second oxygen atom for CO oxidation.

• Bulletin of the Korean Chemical Society
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• 제15권2호
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• pp.115-118
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• 1994

Samples of ($Bi_{2-x}Sb_x)PbSr_2Ca_2Cu_3O_y$, compositions with x=0.0, 0.1, and 0.2 were prepared by solid-state reaction. The solubility of Sb into the 2223 phase is lower than 0.05 for the ratio of Sb/Bi. The lack of stability of the Sb-substituted $Bi_2O_2$ double layers is likely to cause the solubility low. There is no great dependence of lattice parameters on the Sb-content, and bonds around the square-pyramidal Cu atom are not affected by the $Sb^{3+}$ ion substituted. The superconducting transition temperature of this system is decreased gradually with increase of Sb, which is tentatively attributable to the perturbation of the Bi 6p-O 2p band and/or to the low volume fraction of the 2223 phase.

• Bulletin of the Korean Chemical Society
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• 제12권5호
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• pp.525-529
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• 1991

A simple route is described for the selective functionalization of calixarene at the para positions of phenyl rings. Calix[4]arene tetraacetate 2, obtained from the treatment of calix[4]arene with acetic anhydride, undergoes Fries rearrangement to yield the diametrically para substituted p-diacetylcalix[4]arene 3 in 80% yield. The crystal and molecular strucutre has been determined by X-ray diffraction method. The crystals are orthorhombic, space group Pna21, with a = 11.121 (3), b = 10.374 (3), c = 21.690 (6) $\AA$ and Z = 4. The structure was solved by direct method and refined by full-matrix least-squares methods to final R of 0.036 for 1795 observed reflections. Each hydroxyl hydrogen atom is disordered over two positions. The macrocycle exists in the cone conformation which is determined by the strong circular intramolecular flip-flop type hydrogen bonds of phenolic OH, while crystal packing effects of the diametrically para-acetyl substituents seem to be responsible for the distortion of the cone conformation.

• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1084-1090
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• 1998

The oxidation of triphenylphosphine by [(tpy)(phen)RuⅣ(O)]2+ and [(bpy)(p-tert-butylpy)RuⅣ(0)]2+ (tpy is 2,2': 6',2"-terpyridine, phen is 1,10-phenanthroline, bpy is 2,2'-bipyridine, and p-tert-butylpy is para-tertbutylpyridine) in CH3CN has been studied. Experiments using 18O-labeled complex show the oxyl group transfer from [RuⅣ=O]2+ to triphenylphosphine occured quantitatively within experimental error. Kinetic data were fit to a second-order for [RuⅣ=O]2+ and [PPh3]. The initial product, [RuⅡ-OPPh3]2+, was formed as an observable intermediate and then underwent slow solvolysis. The reaction proceeded as endothermic in activation enthalpy and a decrease in activation entropy. The oxidative reactivity of four representative ruthenium mono-oxo oxidants against triphenylphosphine was compared. These systems have been utilized as electrochemical oxidative catalysts.