• Journal of the Korean Ceramic Society
• /
• v.29 no.11
• /
• pp.855-862
• /
• 1992

Thermoelectric power, electrical conductivity and Hall effect were measured, as functions of temperature in the range of 100 to 600 K, on polycrystalline Bi4/3Sb2/3Te3 which had been prepared via uniaxial hot-pressing at different temperatures in the range of 373 K to 773 K, aiming at searching a profitable processing route to a polycrystalline thermoelectric material, a promising, viable alternative to a single crystalline one. It was found that, with increasing temperature of pressing under a fixed pressure, the material, normally a p-type prior to being hot-pressed, underwent a transition to n-type. This transition was confirmed to be due to plastic deformation during hot-pressing and interpreted as being attributed to the change of the major ionic defect BiTe' into TeBi˙at temperature high enough for structure elements mobility. Thermoelectric figure-of-merit of the hot-pressed material was discussed in connection with the p-n transition in addition to microstructure.

• Solar Energy
• /
• v.7 no.2
• /
• pp.65-73
• /
• 1987

Microstructural basis for the thermal degradation of electrodeposited black chrome "solar-L-foil" heated in air has been investigated using scanning electron microscopy, energy dispersive x-ray analysis, X-ray diffraction techniques and UV-VIS-NIR spectre-photometer. Experimental result, the change in the shape of the particle comprising the film from their initial needle like structure to a more spherical shape with an oxide after 1hr annealing at $600^{\circ}C$ has been observed. The effect is to degrade solar absorptance of the thin film.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.177-177
• /
• 2007

ZnO는 3.36eV의 넓은 밴드캡을 가지는 II-IV족 반도체로써 태양전지, LED와 같은 광학적 소자로 이용이 기대가 되는 물질이다. 더욱이, 상온에서의 60meV에 해당하는 큰 엑시톤 에너지와 밴드캡 에지니어링이 가능하다는 장점 때문에 광학적 소자로 널리 이용되고 있는 GaN을 대체할 수 있는 물질로 주목을 받고 있다. 하지만, p-type ZnO는 형성이 어렵고 낮은 이동도와 케리어 농도의 특성을 보이고, 대기 중에 장시간 노출할 경우 n-type ZnO의 특성으로 돌아가는 불안정성을 보이고 있다. 최근에 몇몇의 연구자들에 의해 V족의 원소인 P(phosphorous), N(nitrogen), As(arsenic))를 도핑하여 p-type ZnO의 형성에 대한 논문이 발표되고 있다. 또한, V족 원소 중에 P는 p-type ZnO 형성에 효과적인 도핑 물질로 보고되 고 있다. 본 연구는 마그네트론 스퍼터링을 이용하여 다양한 온도에서 성장된 P도핑 ZnO 박막의 특성에 대해 연구하였다. P도핑된 ZnO 박막은 사파이어 기판에 buffer층을 사용한 Insulator 특성의 ZnO박막위에 400, 500, 600, $700^{\circ}C$에서 성장되 었다. 박막의 특성 분석에는 325nm의 파장을 가지는 He-Cd의 레이져 광원을 사용하여 10K의 저온 PL과 0.5T의 자기장을 사용한 van der Pauw configuration에 의한 Hall effect측정, 그리고 결정성 분석에는 XRD와 TEM을 이용하였다. 상온 Hall-effect 측정 결과, $400{\sim}600^{\circ}C$ 에서 성장된 박막은 n-type의 특성을 보였고, $700^{\circ}C$에서 성장된 Phosphorous 도핑 ZnO박막은 $1.19{\times}10^{17}$의 캐리어 농도를 가지는 p-type의 특성을 보였다. 그리고 XRD분석과 TEM분석을 통하여 박막의 성장온도가 증가 할수록 P도핑된 ZnO박막의 결정성이 향상되는 것을 알 수 있었다. 또한 10K의 저온 PL분석을 통해 p도핑에 의한 액셉터에 관련된 피크들을 관찰할 수 있었다.

• Journal of the Korean Chemical Society
• /
• v.30 no.2
• /
• pp.188-194
• /
• 1986

The rate constants for the solvolysis reactions of p-chlorobenzyl chloride in ethanol-water mixtures were determinded at 30${\circ}\;and\;40{\circ}$C up to 1,600bar. Rates of reaction were increased with increasing temperature and pressure, and decreased with increasing solvent composition of ethanol mole fraction. The plots of ln k against pressure are fitted to a second-order function in P, and values of ${\Delta}V^{\neq}\;and\;${\Delta}{\beta}^{\neq}$ are obtained. The values of ${\Delta}V^{\neq}\;and\;${\Delta}{\beta}^{\neq}$ extremum behavior at about 0.20 mole fraction of ethanol. This behavior is discussed in terms of solvent structure variation. From the relation between the plots of ln k versus the solvent parameter, q ≡ (D-1)/(2D+1), or the logarithmic molar water concentration, In $C_w$, it could be estimated that the reaction proceeds through $S_N1(2)$ mechanism.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.9
• /
• pp.69-74
• /
• 2012

This study investigated the TNT decomposition by the treatment of alkaline hydrolysis. To obtain this objecitive, spectrum shift characteristics, pH effect, kinetics, and product analysis were examined during the alkaline hydrolysis by means of hydroxide ions. At pH = 12, an aqueous solution of TNT was changed into yellow-brown coloring, in which its absorbances were newly increased in a range of wavelength 400-600 nm. From the kinetic data, pseudo-first-order rate constant in a excess of hydroxide ion, in contrast to TNT concentration, was $0.0022min^{-1}$, which means that the reaction rate between TNT and hydroxide ion can be very slow, and that 1,047 min is necessary to achieve a 90% reduction of the initial TNT. In products analyses, nitrite ions and formic acid were mainly produced by the alkaline hydrolysis, nitrate ions and oxalic acid as minor products were generated.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.28 no.6
• /
• pp.593-600
• /
• 2014

This study is aimed to investigate the anti-inflammatory effect of Euphorbiae kansui radix methanol extract (ERE) in lipopolysaccharide(LPS)-stimulated mouse peritoneal macrophages. Peritoneal macrophages were obtained from thioglycollate-injected Balb/c mice. Cells were stimulated with LPS or LPS plus interferon-gamma (IFN-${\gamma}$) in the presence of ERE and various inflammatory markers were assayed. Finally, LPS-induced signaling molecules were measured. ERE up to $400{\mu}g/m{\ell}$, was not cytotoxic to ERE inhibited LPS/IFN-${\gamma}$-induced nitric oxide (NO), inducible NO synthase. ERE also reduced the levels of cyclooxygenase-2 and the proinflammatory cytokines such as tumor necrosis factor-${\alpha}$, interleukin(IL)-6 and IL-12. The inhibitory effect of ERE on LPS-induced $I{\kappa}B{\alpha}$ degradation was weak but phosphorylation of JNK, p38 and ERK1/2 was strongly suppressed. Our data indicated that the anti-inflammatory effect of ERE in LPS-stimulated macrophages was partly mediated by its inhibition of JNK, p38 and ERK1/2.

• Korean Journal of Animal Reproduction
• /
• v.20 no.2
• /
• pp.171-177
• /
• 1996

This study was designed to evaluate the efficacy of antioxidants and amino acid with buffalo rat liver cell(BRLC), bovine oviductal epithelial cell(BOEC) and STOC monolayers in supporting the development of in vitro matured(IVM) and in vitro fertilized(IVF) bovine oocytes. Bovine embryos developed to the 2~8 cell stage after in vitro fertilization were cultured for 5 to 6 days at 39$^{\circ}C$ in CR1aa containing antioxidants and amino acids with various somatic cells. Embryo development was examined and cell numbers of blastocysts were counted by fluorescence staining method. In experiment 1, the proportion of embryos that reached the blastocyst stage in control, catalase(250U), SOD(600U), glutathione(100$\mu$M) and taurine(2.5mM) with BRLC were 11.4, 8, 0, 16.7 and 43.4 respectively. Taurine(2.5mM) with BRLC group was significantly the highest among treatments(P<0.05). In experiment 2, in vitro development rate into blastocyst in control, catalase(250U), SOD(600U), glutathione(100$\mu$M) and taurine(2.5mM) with BOEC were 15.8, 23.5, 22.8, 28.6 and 56.9 respectively. In experiment 3, embryonic development in all treatments as control, catalase(250U), SOD(600U), glutathione(100$\mu$M) and taurine(2.5mM) added to CR1aa with STO cells were 23.5, 24.5, 17.0, 28.8 and 50.0 blastocysts. These results show that antioxidants and amino acids with somatic cells can provide a significant benefit for coculture of early bovine embryos derived from IVM and IVF.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2002.07a
• /
• pp.219-219
• /
• 2002

The SPP003 is a mixture of water extract from Schizandrae Fructus, Poligoni multiflori Radix, Ginseng Radix Akba and Hoelen. The aim of this study was to investigate the anti-hyperglycemic effect of SPP003 in normal and streptozotocin (STZ)-induced diabetic rats, and to monitor the toxicity of SPP003. Oral glucose tolerance test (OGTT) was performed after oral administration of SPP003 100, 300, 600 and 900 mg/kg in normal rats. Blood glucese concentration was measured at -30 min (vehicle, SPP003 or tolbutamide 60 mg/kg, 0 min (glucose treatment), 60, 120 and 180 min. Rats were administerd STZ 65mg/kg (0.1M citrate buffer, pH 4.5) intraperitoneally to induce diabetes and administered vehicle, Spp003 (100, 300 and 600 mg/kg) or tolbutamide (60 mg/kg) orally once a day for 4 weeks. Blood glucose level was measured a 0, 4, 7, 14, 21 and 29 day after initial drug administration. A single oral toxicity of SPP003 was studied in Sprague-Dawley rats of both sexes. In this study, rats were administered with doses of 1, 2 and 5 g/kg of SPP003. In glucose tolerance test, SPP003 900 mg/kg markedly decreased glucose concentration at 1 hr after glucose treatment. Blood glucose levels were much higher in STZ-diabetic rats. These increases were significantly attenuated by SPP003 600 mg/kg. SPP003 did not show any signigicant toxicity. These findings suggest that SPP003 has hypoglycemic properties in STZ-diabetic rats.

• Restorative Dentistry and Endodontics
• /
• v.26 no.5
• /
• pp.436-442
• /
• 2001

Neuropeptide such as calcitonin gene-related peptide and substance P may mediate neurogenic inflammation, but little is known about the regulation of neuropeptide release from rat spinal cord. Eugenol has been reported to reduce odontogenic pain and is known to have a structure similar to capsaicin, a potent stimulant of certain nociceptors. This study was done to examine the effect of capsaicin and eugenol on immunoreactive calcitonin gene-related peptide (iCGRP) release from rat spinal cord and whether eugenol regulates capsaicin-sensitive release of iCCRP or it evokes capsaicin-sensitive release of iCGRP. The dor-sal half of rat lumbar spinal cord was chopped into 200$\mu$m slices. They were superfused (500$\mu$l/min) in vitro with an oxygenated Kreb's buffer. The EC$_{50}$ of capsaicin on iCGRP release was measured. Eugenol (600$\mu$M and 1.2mM) and vehicle (0.02% 2-hydroxyl-$\beta$-cyclodextrin) were administered prior to stimulation of rat lumbar spinal cord with capsaicin. The amount of iCGRP release from rat lumbar spinal cord was measured by radioimmunoassay. The results were as follows : 1. iCGRP release from rat lumbar spinal cord was dependent on concentration of capsaicin. The EC$_{50}$ of capsaicin on iCGRP release was 3$\mu$M. 2. In the vehicle treated group, capsaicin (3$\mu$M) evoked a 14-fold increase over basal iCGRP level. 3. Administration of 600$\mu$M and 1.2mM eugenol evoked a 2.2-fold increase and a 2.3-fold increase over basal iCGRP level respectively. 4. Administration of 600$\mu$M and 1.2mM eugenol increased capsaicin evoked release of iCGRP by more than 50%. These results indicate that eugenol evoke CGRP release from central nervous system and potentiate the pain-inducing action of capsaicin on it.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1992.05b
• /
• pp.26-27
• /
• 1992

The effect of activation and electroless nickel plating conditions on contact properties were investigated for selective electroless nickel plating of Si farers in order to obtain an optimum condition of contact hole filling. According to RCA prosess, p-type si 1 icon (100) surface was cleaned out and activated. The effects of temperture, DMAB concentration, time, and stirring iwere investigated for activation of p-type Si(100) surface. The optimal activation condition obtained was 0.5M HF, 1mM PdCl$_2$, 2mM EDTA, 7$0^{\circ}C$, 90sec under ultrasonic vibration. In electroless nickel plating, the effect of temperature, DMAB concentration, pH, and plating ti me were studied. The optimal plating condition found was 0. 10M NiS0$_4$.$H_2O$, 0.lIM Citrate, pH 6.8, 6$0^{\circ}C$, 30 minutes. The contact resistence of fi]ms wascomparatively low. It took 30 minutes to obtain 1$\mu$m thick film with 8$\mu$M DMAB concentration. The film surface roughness was improved with increasing temperature and decreasing pH of the plating solution. The best quality of the film was obtained with the condition of temperature 6$0^{\circ}C$ and pH 6.8. The micro-victors hardness of film was about 600Hv and was decreased wi th increasing particle size of plating layer.