• Carbon letters
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• v.14 no.2
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• pp.117-120
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• 2013

In this study, an electro-catalyst of Pt nanoparticles supported by polypyrrole-functionalized graphene (Pt/PPy-reduced graphene oxide [RGO]) is reported. The Pt nanoparticles are deposited on the PPy-RGO composite by chemical reduction of H2PtCl6 using NaBH4. The presence of graphene (RGO) caused higher activity. This might have been due to increased electro-chemically accessible surface areas, increased electronic conductivity, and easier charge-transfer at polymer-electrolyte interfaces, allowing higher dispersion and utilization of the deposited Pt nano-particles. Microstructure, morphology and crystallinity of the synthesized materials were investigated using X-ray diffraction and transmission electron microscopy. The results showed successful deposition of Pt nano-particles, with crystallite size of about 2.7 nm, on the PPy-RGO support film. Catalytic activity for methanol electro-oxidation in fuel cells was investigated using cyclic voltammetry. The fundamental electrochemical test results indicated that the electro-catalytic activity, for methanol oxidation, of the Pt/PPy-RGO combination was much better than for commercial catalyst.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.395-398
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• 2009

전기도금 방법을 사용해 각기 다른 환원 전압과 전기도금시간에서 Pd 수지상 나노와이어(Pd DNWs) 전극이 합성 되었으며 그 성장 기작을 논의하였다. 전기화학적인 도금 공정 동안 Pd DNWs 이<111>방향으로 성장하는 것을 확인할 수 있었는데, 이것은 전해질 속의 황산음이온들이 Pd 의 (111)면에 흡착하기 유리하기 때문이라고 사료된다. 가해준 환원전압이 증가함에 따라, 단 결정 수지상의 나노와이어의 가지는 길어지고 얇아지는 경향을 보였다. 이것은 전기도금 시간이 아니라 환원전압에 의해서만 나노와이어 가지의 직경이 조절됨을 보여준다

• Biomolecules & Therapeutics
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• v.8 no.4
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• pp.305-310
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• 2000

The present study examined the effect of a methanol extract of Evodiae Fructus on the blood pressure in spontaneously hypertensive rats (SHR). The systolic blood pressure was measured after rats were pretreated with phentolamine, propranolol, or $N_{\omega}$-nitro-$_{L}$-arginine methyl ester(NAME) and subsequently received methanol extract of Evodiae Fructus. In SHR, intraperitoneal administration of methanol extract of Evodiae Fructus (0.5 mg/kg) produced antihypertensive effect that lasted for at least 4 hours. Antihypertensive effect of Evodiae Fructus was more stronger than that with $\alpha$-adrenergic receptor antagonist phentolamine and was not affected by $\beta$-adrenergic receptor antagonist propranolol. The antihypertensive effect of Evodiae Fructus was abolished by pretreatment of NAME. Our findings suggest Evodiae Fructus has an hypertensive effect, which may be mediated through nitric oxide synthesis.s.

• Korean Journal of Microbiology
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• v.40 no.1
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• pp.17-22
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• 2004

Scutellaria baicalensis and Phellodendron amurense, which have been used traditionally in treatment of many kinds of illness including infectious diseases, were extracted with hexane, dichloromethane, methanol and water, respectively and serially. Antimicrobial activities of the extracts were examined by disk diffusion method. Methanol extract from Scutellaria baicalensis revealed high antimicrobial activities against MRSA, Gm-bacteria and Candida albicans, dichloromethnane extract from Phellodendron amurense showed lower activity than the extract of Scutellaria baicalensis. Results suggest that methanol extract from Scutellaria baicalensis could be one of the candidates for new antimicrobial agent against the antibiotic-resistant microorganisms by further steps for the purification, determination of structure and synthesis.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.252-258
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• 1999

Tetramethyl orthosilicate (TMOS) was obtained by the direct synthesis of methanol with metallic silicon including copper compound as a catalyst and zinc compound as a promoter. The effects of the preheating temperature and the preparation method of the contact mass on TMOS synthesis were investigated. The composition effects of the contact mass which was composed of metallic silicon with copper catalyst and various metallic halide promoters including Zn, Sn or Cd compound were studied also. The best performance on TMOS synthesis was observed on a mixed bed reactor containing metallic silicon preheated with CuCl as a catalyst and $ZnCl_2$ as a promoter. When Cu/Si = 7 wt %, Zn/Cu = 7 wt % was mixed in a slurry phase and activated into contact mass at $380^{\circ}C$, the average selectivity was 87.2% in the silicon consumption of 69.2% at $220^{\circ}C$.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.416-420
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• 2018

A comprehensive kinetic study has been conducted on dimethyl carbonate synthesis by transesterification reaction of ethylene carbonate with methanol. An alkali base metal (KOH) was used as catalyst in the synthesis of DMC, and its catalytic ability was investigated in terms of kinetics. The experiment was performed in a batch reactor at atmospheric pressure. The reaction orders, the activation energy and the rate constants were determined for both forward and backward reactions. The reaction order for forward and backward reactions was 0.87 and 2.15, and the activation energy was 12.73 and 29.28 kJ/mol, respectively. Using the general factor analysis in the design of experiments, we analyzed the main effects and interactions according to the MeOH/EC, reaction temperature and KOH concentration. DMC yield with various reaction conditions was presented for all ranges using surface and contour plot. Furthermore, the optimal conditions for DMC yield were determined using response surface method.

• Journal of Life Science
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• v.9 no.3
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• pp.248-252
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• 1999

Effects of the ultrasonic treatment on plant represents antifeeding activity and chitin synthesis inhibition activity against diamondback moth (Plutella xylostella L.) by a leaf-dipping method at a concentration of 5,000ppm. Methanol extracts of leaves of the ultrasonic treatment on plant was sequentially partitioned with n-hexane, chloroform, ethlyacetate, butanol and water fractions, and bioassayed. Antifeeding activities were observed in n-hexane, chloroform and ethlyacetate fractions. N-hexane fraction has 94.6% of strongest antifeeding activity against P. xylostella. From the n-hexane sequentially partitioned showed H6 and H8 fractions of antifeeding activities against P. xylostella. And chitin synthesis inhibition activity against P. xylostella was obtained the methaol, n-hexane and water fractions.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.566-572
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• 2007

Two hybrid catalysts for the direct synthesis of DME were prepared and the catalytic activity of these catalysts were investigated. The hybrid catalyst for the direct synthesis of DME was composed as the catalytic active components of methanol synthesis and dehydration. The methanol synthesis catalyst was formed from the precursor contained Cu and Zn, the methanol dehydration catalyst was used ${\gamma}-Al_2O_3$. As PM-CZ+D and CP-CZA/D, Two hybrid catalysts were prepared by physical mixing method (PM-CZ+D) and precipitation method (CP-CZA/D), respectively. PM-CZ+D was prepared by physically mixing methanol synthesis catalyst and methanol dehydration catalyst, CP-CZA/D was prepared by depositing Cu-Zn or Cu-Zn-Al components on ${\gamma}-Al_2O_3$. The crystallinity and the surface morphology of synthesized catalyst were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) to investigate the physical property of prepared catalyst. And BET surface area by $N_2$ adsorption and the surface area of Cu by $N_2O$ chemisorption were investigated about the hybrid catalysts. In addition, catalytic activity of these hybrid catalysts was examined with varying reaction conditions. At that time, the reaction temperature of $250{\sim}290^{\circ}C$, the reaction pressure of 50~70 atm, the $[H_2]/[CO]$ mole ratio of 0.5~2.0 and the space velocity of $1,500{\sim}6,000h^{-1}$ were investigated the catalytic activity. From these results, it was confirmed that the reactivity of CP-CZA/D was higher than that of PM-CZ+D. When the conditions of reaction temperature, pressure, $[H_2]/[CO]$ ratio and space velocity were $260^{\circ}C$, 50 atm and 1.0, $3,000h^{-1}$ respectively, CO conversion using CP-CZA/D hybrid catalyst was 72% and the CO conversion of CP-CZA/D was more than 20% compared with the CO conversion of PM-CZ+D. It was known that Cu surface area of CP-CZA/D hybrid catalyst was higher than that of hybrid PM-CZ+D catalyst using $N_2O$ chemisorption. It was assumed that the catalytic activity was improved because Cu particle of hybrid catalyst prepared by precipitation method was well dispersed.

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.211-218
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• 2002

In this study, Pt/Pd (1.1), PtPd (2:1) and PtPd (3:1) binary catalysts and Pt/Ru/Pd (5:4:1) ternary catalyst were designed. The catalysts were synthesized by impregnation method using $NaBH_4$ as a reducing agent. A good catalyst for methanol oxidation requires low on-set potential, stable durability and low activation energy. In order to investigate the catalytic activity for the methanol oxidation, electrochemical measurements such as cyclic voltammetry and chronoamperometry were peformed in sulfuric acid with/without methanol solution. In order to calculate the activation energy of the reaction, electrochemical measurements were also tested at different temperatures. For investigation of the structural analysis such as particle size and alloying, X-ray diffraction and transmission electron microscopy analysis were used. In order to identify the role of the Pd and to determine the composition of the surface of the Pt/Pd nanoparticles, X-ray photoelectron spectroscopy (XPS) analysis was investigated. The XPS spectra of Pd showed that Pd appears only as a metallic state in the binary catalysts. The chemical states of Pt in PtPd catalysts are both metallic and oxidative. Polarization curves and power density data were obtained by testing the DMFC unit cell performance of PtPd and PtRuPd catalysts. These data showed that Pt/Pd (2:1) and Pt/Ru/Pd (5:4:1) have better performance than Pt and Pt/Ru, respectively.

• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1183-1188
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• 2005

Several lipases of commercial grade were screened to catalyze the methanolysis of castor oil, and an immobilized Candida antarctica (Novozym 435) had the highest activity among the lipases tested. To enhance the yield of methyl ricinoleate, several reaction parameters were optimized. The optimum temperature was $50^{\circ}C$, and the original water content of lipase was sufficient to maintain the activity of lipase, and additional water supplied inhibited the methanolysis of castor oil. Because the lipase was deactivated by methanol, the reaction was tested by three-step addition of 1 molar equivalent of methanol to the oil. However, the oil was not completely converted to its methyl esters. The final reaction mixture using 3 molar equivalents of methanol to the oil consisted of $70\%$ methyl ricinoleate, $18\%$ monoricinoleate, $11\%$ diricinoleate, and trace triricinoleate at the equilibrium state. The yield of methyl ricinoleate was $97\%$ at 6 molar ratio of methanol to the oil with 300g of castor oil and 6g of immobilized Candida antarctica at $50^{\circ}C$ within 24 h.