아세톤-물 혼합용매내에서 1_1 전해질의 전기전도도에 대한 연구

오형식,김종현,전동철 木浦大學校基礎科學硏究所 1988 基礎科學硏究誌 Vol.6 No.-

여러가지 조성의 아세톤-물 혼합용매중에서 LiC1, LiBr 및 Lil의 희박용액 전도도를 25℃에서 측정하였다. 그 결과 각 전해질들의 여러 농도에 따르는 당량전도도의 변화가 Fuoss-Onsager's semiem-pirical 식에 대해서 좋은 일치를 보여 주었다. 또한 아세톤-물 혼합용매의 몰 분율이 증가함에 따라 극한당량전도도??값이 LiC1, LiI는 0.3 몰 분율에서, LiBr는 0.2 몰 분율에서 가장 작은 값을 나타내었다. Walden Product??는 LiC1와 LiBr가 0.1 몰 분율에서, LiI는 0.0 몰 분율에서 최대치를 보여 주었고, 그 후로는 아세톤 몰 분율의 증가에 따라 계속 감소하였다. The equivalent conductance of LiC1, LiBr and LiI have been measured in Acetone-Water mixtures of various composition (0.0∼0.6 mole fraction) at 25℃. The value of equivalent conductance agreed well with the Fuoss-Onsager's semiempirical equation. The minimum limiting equivalent conductance was found in 0.3 mole fraction Acetone for LiC1, LiI and LiBr was found in 0.2 mole fraction Acetone. The maximum Limiting Walden Products?? of LiC1 and LiBr was found in 0.0 mole fraction Acetone, and LiI was found in 0.0 mole fraction Acetone. And also, after 0.1 mole fraction and 0.0 mole fraction, decreased with increasing of mole fraction Acetone.

EtOH-Water 혼합용매 중에서 Fuoss-Onsager's Semiempirical Equation에 의한 Et₄NC1, Et₄NBr, Et₄NI 의 전도도

오형식,김종현 木浦大學校基礎科學硏究所 1985 基礎科學硏究誌 Vol.3 No.-

0.0 ∼ 0.4몰분율의 에탄올+물 혼합용매에서 Et₄NCI, Et₄NBr, Et₄NI의 당량전도도를 25℃에서 측정하였고, 각 염들의 극한당량전도도와 Conductance parameter 는 Fuoss-Onsager's semiempirical equatopn에 의하여 계산하였다. 당량전도도는 염들에 농도가 증가 할 수록 감소하였고 √c에 대한 ∧의 도시는 직선성을 보여 주었다. 극한당량전도도는 에탄올의 몰분율이 증가함에 따라 감소하였으며, 수용액(0.0m.f.)과 0.1몰분율 에탄올 사이에서 가장 큰 감소를 보여 주었다. The Equivalentc conductance of dilute solution of Et₄NCI, Et₄NBr and Et₄NI in Ethanol+Water mixtures for 0.0∼0.4 mole fraction wes determined at 25℃ the limiting equivalent conductance and conductance parameters have been computed by Fuoss-Onsager's semiempirical equation. Equivalent conductance(∧)of salts decreased with the increased of the salts concentration and the plot of ∧ vs.√c shawed nearly linearity. The limiting equivalent conductance?? decreased with the increase of mole fraction of Ethanol and the maximum decrement in ?? shows between 0.0 and 0.1mole fraction of Ethanol.

단결정 n-TiO₂광전극에 대한 Flatband Potentials와 Mott-Schottky 그림

오형식,성정섭 木浦大學校基礎科學硏究所 1986 基礎科學硏究誌 Vol.4 No.-

단 결정 TiO₂양극에 대한 표면제조 처리는 이상적인 Mott-Schottky 그림이 보인 바와 같이 매우 작은 주기분산을 나타냈다. Rutile boules의 세 형태(Prism, Al-free, optical grade)에서의 실험은 flatband potential에서 현저한 차이를 나타냈다. Prism grade, optical grade와 Al-free에서의 pH에 대한 flatband potential의 의존성은 각각 65, 62, 58mV/pH Unit였다. 즉, prism grade와 Al-free에서의 flatband potential의 차는 pH=1.0 에서 50mV, pH=12.1에서 160mV였다. 마지막으로 특별히 처리된 TiO₂시료는 전해질의 농도가 1.1M일때 이상 적인 Mott-Schottky 그림이 나타났으며 전해질의 농도가 0.25M보다 작으면 큰 주기 분산효과를 나타냈다. We have found a surface preparation treatment for single crystal TiO₂ photoanodes that produces ideal Mott-Schottky plots showing very little frequency dispersion. The special preparation procedure permitted precise determination of flatband potentials, and experiments with three types (prism grade, optical grade, and Al-free) of rutile boules showed significant difference in their flatband potentials. The average pH dependence of flatband potential for prism, optical grade and Al-free boules were 65, 62, 58mV/pH unit, respectively. For the prism grade and Al-free boules this represented flatband potential differences of 50mV at ph=1.0 and 160mV at ph=12.1. Finally, we observed that the specially treated TiO₂samples would only yield ideal Mott-Schottky plots if the concentration of the electroyte was about 1M. The use of electrolyte concentrations less than 0.25M produced large frequency dispersion effects.

비스(트리메틸실릴메틸)메톡시비닐실란의 합성

오형식,장주환 木浦大學校 基礎科學硏究所 1994 基礎科學硏究誌 Vol.12 No.-

비스(트리메틸실릴메틸)디클로로실란은 구리와 카드뮴을 각각 촉매와 조촉미로 사용하어 320 ℃에서 클로로메틸트리메틸실란을 금속규소와 직접반응에 제조하였다. 비스(트리메틸실릴메틸)디클로로실란을 메틸알콜과 반응시켜 비스(트리메틸실릴메틸)클로로메톡시실란을 합성하였고, 이를 비닐 그리냐르시약과 반응시켜 비스(트리메틸실릴메틸)메톡시비닐실란을 합성하였다. Bis(trimethylsilylmethyl)dichlorosilane has been prepared in 71% yield by the direct synthesis of α-chloromethylsilanes with metallic silicon in the presence of copper catalyst and cadmium cocatalyst using a spiral band agitator at the carefully controled temperature at 320℃ and we prepared the bis(trimethylsilymethyl)methoxyvinylsilane prepared by Grignard reaction in 63% yield.

축전용량 측정법에 의한 ZnO-O₂경계면에 대한 연구

오형식,전동철 木浦大學校基礎科學硏究所 1988 基礎科學硏究誌 Vol.6 No.-

반도체와 기체 사이에서의 거동을 조사 하는데 축전 용량 측정법이 전도도 측정을 대신할 수 있게 되었다. 산화아연 ?? 에 산소가 흡착 될때 형성되는 공간 전하 영역의 길이 ??를 축전용량 법을 이용하여 조사 하였고 흡착 과정에서 고갈층이 형성 됨을 알 수 있었다. 시료를 773K에서 1시간 배기 시킨후 흡착 온도(298K∼673K)에 따른 ??의 변화를 조사한 결과 온도가 증가할 수록 ??가 증가(112Å∼331Å)함을 알 수 있었다. 이러한 결과들로 부터 산소는 산화아연 표면에 받게 형태로 흡착되고 흡착 과정에서 표면에 에너지 장벽이 형성 됨을 알 수 있었다. Capacitance measurement was presented for studing semiconductor-gas interface. The depth of the space charge region ??, which has developed in the chemisorption of oxygen on ZnO single crystal, has been estimated from the capacitance measurements. After the sample was evacuated at 773K for 1 hr, the value of ?? appeared largely when adsorbed temperature was increased. From the results, it was suggested that oxgen was adsorbed as an acceptor on ZnO single crystal and an energy barrier at the surface was formed during the adsorption process.

TiO₂분말의 현탁액에서 광에 의한 수소와 과산화수소의 생성에 관한 연구

오형식,성정섭 木浦大學校基礎科學硏究所 1985 基礎科學硏究誌 Vol.3 No.-

TiO₂/water suspension에 UV광을 조사하여 생성되는 H₂와 H₂O₂를 연구했다. H₂와 H₂O₂의 생성속도는 GC와 요오드 적정법으로 측정했다. 여기서는 반도체의 양을 세가지로 나누어 실험한 결과 H₂의 극한속도는 조사시간이 약 2시간일때 였고 H₂O₂의 극한농도는 3시간 이후 일때 였으며 시간이 증가 할 수록 점차로 O 에 접근함을 알 수 있었다. H₂와 H₂O₂의 생성에 대한 양자효율은 각각??과 ??이었다. Photosynthetic generation of H₂and H₂O₂is demonstrated on UV-irradiated TiO₂/water suspensions. The rate of H₂and H₂O₂generation were monitored by a combined analytical-gas chromatographic procedure as a function of irradiation time and solid content. The rate of H₂evolution of TiO₂for three levels of solid content in the reaction mixture. A limiting rate of H₂generation is attained after∼2h of illuminations. This limiting rate is directly proportional to the concentration of TiO₂. A limiting concentration of H₂O₂is attained after ∼3th of illumination, and concomitantly the rate drops gradually to zero. The apparent quantum yields for generation of H₂and H₂O₂on TiO₂were calculated to be ?? and ??, respectively.

에탄올-물 혼합용매에서 o-Fluorobenzoic acid와 m-Fluorobenzoic acid의 해리상수에 관한 연구

오형식,김종현 木浦大學校基礎科學硏究所 1984 基礎科學硏究誌 Vol.2 No.-

ο-Fluorbenzoic acid, m-Fluorbenzoic acid의 해리상수를 Ostwald equation에 의하여 구하였고, Fuoss-Kraus에 의해 제시된 방법에 의해 보정하였다. 각 산들의 pK값은 Ethanol 함량에 따라 직선성을 보여주었다. Ethanol-Water혼합용매에서 각 산들의 해리 순서는 Benzoic Acid〈p-Fluorobenzoic Acid〈m-fluorobenzoic Acid〈ο-Fluorobenzoic Acid이었다. The dissociation constant of ο-Fluorobenzoic acid and m-Fluorobenzoic acid have been determined by OSTWALD equation. The results have been checked by the method suggested by FUOSS-KRAUS. The pK values of acid samples by two methods showed slight deviation in increased ethanol content. The order of dissociation of acids in Ethanol+Water mixtures was Benzoic acid 〈p-Fluorobenzoic acid〈m-Fluorozbenzoic acid〈ο-Fluorobenzoic acid.

메탄올-물 혼합용매에서 o-,m-,p-치환된 벤조산들의 해리상수에 관한 연구

吳炯植 木浦大學校基礎科學硏究所 1987 基礎科學硏究誌 Vol.5 No.-

메탄올-물 혼합용매에서 o-, m-, p-methylbenzoic acid와 o-, m-, p-aminoben-zoic의 해리상수를 Ostwald equation에 의하여 구하였고, Hammett o-Values에 비교 검토하였다. o-, m-, p-methylbenzoic acid는 methanol 함량50 무게퍼센트에서, 그리고 o-, m-, p-aminobenzoic acid는 30 무게퍼센트에서 최대값을 가졌고, 그 이후 methanol rich한 쪽으로 갈수록 감소하였다. 수용액에서 각 산들의 pKa값의 순서는 o-CH₃; 4.03〈p-CH₃; 4.07〈m-CH₃;4.21, o-NH₂; 4.30〈m-NH₂; 4.78〈p-NH₂; 5.07이었다. The pKa values of o-,m- p-methylbenzoic acid and o-, m-, p-aminobenzoic acid determined by Ostwald equation in methanol-water mixtures at 25℃ and ploted vs. Hammett o values. The pKa values of every weak acids are in-creased with increasing weight percent of methanal weight content, but o-, m-, p-methylbenzoic acids have the highest value at 50 weight percent of methanol-content and o-, m-, p-aminobenzoic acids have the highest value at 30 weight percent of methanol content. The order of pKa values of methylbenzoic acid and aminobenzoic acid in water solution was o-CH₃; 4.03〈p-CH₃; 4.07〈m- CH₃; 4.21, o-NH₂; 4.30〈M-NH₂; 4.78 p-NH₂; 5.07.

bis(trimethylsilylmethyl)methoxyphenylsilane의 열분해

오형식 木浦大學校 基礎科學硏究所 1993 基礎科學硏究誌 Vol.11 No.-

The Flash Vacuum Pyrolysis of bis(trimethylsilylmethyl)methoxyphenylsilane at 780℃ gave 1-phenyl-1,3-disilacyclobuthane and 1,3-bis(trimethylsilylmethyl)-1,3-diphenyl-1,3-disilane by intermolecular cyclization and intramolecular rearrangement, respectively. Bis-(trimethylsilylmethyl)methoxyphenylsilane containg a methoxy group on the central silicon atom is a good precursor for 1,3-disilacyclobutanes upon pyrolyzation.

當歸類가 혈관신생에 미치는 영향에 대한 비교연구

吳霞植,金亨煥,安德均,崔湖榮 대한본초학회 2001 大韓本草學會誌 Vol.16 No.2

A rat sponge implant model was used to examine the angiogenic effect of water extract of Angelica Gigantis Radix (EAG). Angelica Sinensis Radix (EAS) and Angelica Radix (EAA). It was based on subcutaneous implantation of sterile polyester sponges in the Sprague Dawley (SD) rat and we have characterized a dye method that incorporates 5% carmine red in 10% gelatin. Vascularity index (V.I.) expressed as ㎍ dye/㎎ dry tissue. The result of study is as follows; 1. Subcutaneous implantation of sterile polyester sponges in SD rats enhanced the angiogenesis over 14 days, as determined by measurements of relative angiogenic effects by a vascularity index. 2. Daily oral administration (100 ㎎/㎏ for 14 days) of EAS and EAA produced weak effect on sponge-induced angiogenesis but EAG caused intense neovasculalization. 3. PBS (50 μ1) and EAG (100 ㎎/㎏) - induced angiogenesis represents a special form of angiogenesis. 4. The vasoconstrictor peptidem, angiotensin Ⅱ(AⅡ), in daily doses of 100 nmol, caused an intense neovascularization and coadministration of the AⅡ (100 nmol) and EAG (100 ㎎/㎏), AⅡ and EAS (100 ㎎/㎏) and AⅡ and EAA (100 ㎎/㎏) produced angiogenic effect. Especially, AⅡ (100 nmol) and EAG (100 ㎎/㎏) caused very potent angiogenesis. We have shown that oral administration of EAG (100 ㎎/㎏) induced angiogenesis. Thus the sponge model offers a new means for continuous and reproducible studies on the controlling mechanisms of angiogenesis.