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스트론튬이 도프된 페로브스카이트 La_1-x Sr_xCoO_3의 환원 반응
박일현,이형표,백성현 성균관대학교 기초과학연구소 1988 論文集 Vol.39 No.2
Sr-doped lanthanum cobalt oxides having perovskite structure, La_1-xSr_xCoO_3 (x=0, 0.2, 0.4, 0.6), were prepared in air at 1000℃ by ordinary solid state reactions and their physicochemical properties including particle morphology, non-stoichiometry, stability and reducibility were characterized by the use of TPR, XRD and SEM techniques. Particle size is not considerably affected by impurity dopant (Sr^2+ ion) but reduction behaviors and thermal stability were markedly varied according to the amounts of Sr (various x values). All these perovskites have oxygen deficient structure as follows. LaCoO_2.94, La_0.8Sr_0.2CoO_2.94, La_0.6Sr_0.4CoO_2.88, La_0.4Sr_0.6CoO_2.83. Finally, kinetics of reduction on each stage was discussed using well-established reduction models and kinetic parameters, activation energy and preexponential term, were evaluated from the optimum reaction model.
폴리에틸옥사졸린의 용해도, 점성도 및 밀도에 관한 연구
박일현 金烏工科大學校 1993 論文集 Vol.14 No.-
Solubilities of Polyethyloxazoline(PEOx) were investigated in 43 organic solvents. Some non-polar solvents (for example : benzene, cyclohexane ad carbon tetrachloride), diethyl ether and diethylamine etc, appeared as non-solvents for PEOx polymer. Based upon the intrinsic viscosities and huggins coefficients of PEOx measured in various solvents, we were able to conform that methanol and chlorofrom wee the good solvents and that methyl acetate and ethyl acetate were the poor solvents, respectively. The specific volume was obtained by means of two different experimental methods. The average partial specific volume(o.983mL/g) estimated from the specific refractive index increments(s.r.i.i.) using Glastone-Dale equation appeared to be large by 15% than that(0.853mL/g) obtained by the dilatometry. In oder to understand clearly why the difference came out, it needs further experiment. Also from analysis of the s.r.i.i. dta using Glastone-Dale equation, a value of n₂=1.519 was obtained for the refractive index of PEOx at ??, T=35℃
Bromopentammine Cr(Ⅲ) ion 의 Aquotization Mechanism 에 關한 硏究
朴一鉉 成均館大學校 1962 論文集 Vol.7 No.-
The aquation rate of Bromo-pentammine chrom (Ⅲ) complex ion [Cr(NH_3)_5Br]^2+ was measured in acidic solution at various temperature, hydrogen ion concentration and ionic stregth. It has been determined that the aquation reaction is first-order reaction and that aquation rate constant for the replacement of bromide by water is k= 6.1 × 10 exp(13) exp (-20500/RT). The aquation of [Cr(NH_3)_5Br]^2+ was found to be increased by increasing hydrogen ion concentration and ionic strength. An interpretation of aspects of ligand replacement with trivalent chromium and cobalt complexes is presented whereby it is inferred that an Sn2 mechanism holds for chromium complex and Snl mechanism for those of cobalt.
Perovskite 형 복합산화물 LaCoO_3의 생성 및 환원 반응에 관한 연구
박일현,이형표,유성덕,이상범 성균관대학교 기초과학연구소 1987 論文集 Vol.38 No.1
The reactions of formation and reduction of perovskite-type LaCoC_3 mixed oxide were investigated by means of thermogravimetric analysis(TG), differential thermal analysis(DTA), X-ray diffraction method (XRD) and infrared spectrometry(IR). According to the simultaneous TG-DTA measurements, it was confirmed that equimolar mixture of lanthanum and cobalt nitrates was decomposed via complex reaction stages and perovskite-type LaCoO_3 oxide was formed as final product at 670℃ in air. In order to clarify the decomposition stages of the mixed metal nitrates, decompositions of each metal nitrates were examined previously. The intermediates and final products were identified by using the X-ray diffractometer and IR spectrometer, and the volatile gaseous species evolved during the decomposition were also detected by IR spectrometry. The reduction reaction of LACoO_3 was studied by means of the sensitive spring balance in the static H_2 atmosphere. It was revealed that LaCoO_3 was reduced through the formation of intermediate with oxygen-deficient structure and to the final products La_2O_3 and Co metal. In the first reduction stage at 256∼416℃, LaCoO_3 was reduced to LaCoO_2.5, in which the color of the sample are initially black and turn to the violet green during reduction. the intermediate was quickly reoxidized in air to original LaCoO_3 oxide. This oxygen-deficient intermediate was further reduced to La_2O_3 and metallic Co through second reduction stage at 470∼620℃. Kinetic study for the reduction of LaCoO_3 was discussed by means of dynamic thermogravimetric analysis method. It showed that activation energies for the first and second reduction stages were 7.6 and 19.6 Kcal/mole, respectively.
항암제 및 항바이러스제에 관한 연구 : 알킬사슬을 가진 우라실 누클레오시드 유사체의 합성
박일현,명평근 충남대학교 암연구소 1991 癌共同硏究所 硏究誌 Vol.1 No.1
Some of halopyrimidine nucleosides and nucleotides have potent medicinal properties. As part of a series of synthetic studies on uracil/5-fluoro-uracil derivatives aimed at obtaining improved antitumor agents, we wish to report the synthesis of 1-allyl uracil, l-(2'-butenyl) uracil, l-(2', 3'-dihydroxypropyl) uracil and l-(2'-(2-hydroxyethoxy)ethyl) uracil. These are to be tested for their antitumor activities and furthermore to be used as starting compounds for another derivatives."
박일현,명평근 충남대학교 약학대학 의약품개발연구소 1990 藥學論文集 Vol.6 No.-
Some of halopyrimidine nucleosides and nucleotides have potent medicinal properties. As part of a series of synthetic studies on uracil/5-fluoro-uracil derivatives aimed at obtaining improved antitumor agents, we wish to report the synthesis of 1-allyl uracil, 1-(2'-butenyl) uracil, 1-(2',3'-dihydroxypropyl) uracil and 1-(2'-(2''-hydroxyethoxy)ethyl) uracil. These are to be tested for their antitumor activities and furthermore to be used as starting compounds for another derivatives.