• 신재생에너지
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• 제2권4호
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• pp.64-69
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• 2006

There is a worldwide interest in the development and commercialization of polymer electrolyte membrane fuel cells [PEMFCs] for vehicular and stationary applications. One of the major objectives is the reduction of loaded electrode materials, which is comprise of the Pt-based noble metals. In this paper, a novel chemical strategy is described for the preparation and characterization of carbon-supported and surface-alloys, which were prepared by using a successive reduction process. After preparing Au colloid nanoparticles, the supporting of Au colloid nanoparticles occurred spontaneously in the carbon black-dispersed aqueous solution. Then nano-scaled active materials were formed on the surface of carbon-supported Au nanoparticles. The structural and electrochemical analyses indicate that the active materials were deposited on the surface of Au nanoparticles selectively and that an alloying process occurred during the successive reducing process. The carbon-supported & surface-alloys showed the higher electrocatalytic activity than those of the particle-alloys and commercial one [Johnson-Matthey] for the reaction of methanol and formic acid oxidation. The increased electrocatalytic activity might be attributed to the effective surface structure of surface-alloys, which have a high utilization of active materials for the surface reaction of electrode.

• Food Science and Biotechnology
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• 제18권2호
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• pp.323-329
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• 2009

The prescriptions (DB-1-DB-5) were prepared with the active herbal medicines, Acanthopanax senticosus, Glycyrrhiza uralensis, Polygonatum odoratum, and Cichorium intybus. The most active crude polysaccharide fraction (DB-2-3), which was isolated through the fractionation of hot-water extract from DB-2, was significantly reduced by periodate oxidation (52.7 and 63.7%) on intestinal immune system modulating and anticancer activity. When DB-2-3 was further fractionated by column chromatographies, DB-2-3IIc-2 showed the most potent activities. In addition, DB-2-3IIc stimulated the proliferation of bone marrow cells via Peyer's patch in dose-dependent pattern by oral administration. The metastasis of colon 26-M3.1 lung carcinoma had significantly inhibited in mice fed DB-2-3IIc at 1 mg/mouse (43.8%). DB-2-3IIc-2 mainly contained uronic acid (46.1%) and 42.5% of neutral sugar with a small amount of protein (7.6%), and component sugar analysis also showed that DB-2-3IIc-2 was composed Ara, Gal, and GalA (molar ratio; 0.50:0.63:1.00). It may be suggested that activities of DB-2-3IIc-2 are resulted from pectic polysaccharides containing a polygalacturonan moiety with side chain of neutral sugars, such as Ara and Gal.

• 한국세라믹학회지
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• 제51권4호
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• pp.307-311
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• 2014

ZnS and $ZnS/TiO_2$ were prepared by chemical deposition. The prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and transmission electron microscopy (TEM). The generation of reactive oxygen species was detected by monitoring the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Excellent catalytic degradation of methylene blue (MB) solution was observed using the $ZnS/TiO_2$ composites during irradiation with visible light. The results show that the photocatalytic performance of $TiO_2$ nanoparticles is improved by loading with ZnS.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3283-3290
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• 2010

The gas-phase dehydration of glycerol to acrolein was carried out over 10 wt % HSiW catalysts supported on different supports, viz. $\gamma-Al_2O_3$, $SiO_2-Al_2O_3$, $TiO_2$, $ZrO_2$, $SiO_2$, AC, $CeO_2$ and MgO. The same reaction was also conducted over each support without HSiW for comparison. Several characterization techniques, $N_2$-physisorption, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), the temperature-programmed desorption of ammonia ($NH_3$-TPD), temperature-programmed oxidation (TPO) with mass spectroscopy and CHNS analysis were employed to characterize the catalysts. The glycerol conversion generally increased with increasing amount of acid sites. Ceria showed the highest 1-hydroxyacetone selectivity at $315^{\circ}C$ among the various metal oxides. The supported HSiW catalyst showed superior catalytic activity to that of the corresponding support. Among the supported HSiW catalysts, HSiW/$ZrO_2$ and HSiW/$SiO_2-Al_2O_3$ showed the highest acrolein selectivity. In the case of HSiW/$ZrO_2$, the initial catalytic activity was recovered after the removal of the accumulated carbon species at $550^{\circ}C$ in the presence of oxygen.

• Journal of Ginseng Research
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• 제34권4호
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• pp.348-354
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• 2010

Black ginseng and white ginseng were extracted with 80% ethanol and evaluated for relative ginsenoside composition, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities, and antioxidant properties. As analyzed by HPLC, black ginseng contained a greater proportion of ginsenoside $Rg_3$ compared to white ginseng. White ginseng was characterized by undetectable ginsenoside $Rg_3$ but it contained more total ginsenosides than black ginseng. Black ginseng extract exhibited higher (p<0.05) free radical-scavenging activity, as well as higher antioxidant activities than white ginseng against 2,2-diphenyl-1-picryl-hydrazyl, superoxide dismutase, and xanthine oxidase, despite the fact that the total saponin content was higher in white ginseng than black ginseng. In addition, the black ginseng extract displayed greater AChE and BChE inhibitory activities. These results suggest that black ginseng has stronger effects on anti-oxidation and AChE and BChE inhibition than white ginseng.

• 한국재료학회지
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• 제25권7호
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• pp.358-363
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• 2015

We present an excellent detection for nitrogen monoxide (NO) gas using polycrystalline ZnO wire-like films synthesized via a simple method combined with sputtering of Zn metallic films and subsequent thermal oxidation of the sputtered Zn nanowire films in dry air. Structural and morphological characterization revealed that it would be possible to synthesize polycrystalline hexagonal wurtzite ZnO films of a wire-like nanostructure with widths of 100-150 nm and lengths of several microns by controlling the sputtering conditions. It was found from the gas sensing measurements that the ZnO wire-like thin film gas sensor showed a significantly high response, with a maximum value of 29.2 for 2 ppm NO at $200^{\circ}C$, as well as a reversible fast response to NO with a very low detection limit of 50 ppb. In addition, the ZnO wire-like thin film gas sensor also displayed an NO-selective sensing response for NO, $O_2$, $H_2$, $NH_3$, and CO gases. Our results illustrate that polycrystalline ZnO wire-like thin films are potential sensing materials for the fabrication of NO-sensitive high-performance gas sensors.

• Environmental Engineering Research
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• 제24권4호
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• pp.566-571
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• 2019

One-pot hydrothermal route was adopted to synthesize Al:BiVO₄, at 4 h and 8 h reaction durations, by adding 1% aluminiumoxide powder (w/v) to the precursors. The products were investigated using several characterization techniques that conform a significant morphological change and a decrease in bandgap energy of the materials upon Al modification of scheelite monoclinic bismuth vanadate matrix at both hydrothermal durations. Antibacterial experiments were performed against methicillin-resistant Staphylococcus aureus in visible light condition to harness the photoxidation property of Al-doped BiVO₄ and compare to that of unaltered BiVO₄. Minimum inhibitory concentration of the synthesized materials was identified. The results indicate that Al-doping on BiVO₄ has a significant effect on its photocatalytic antibacterial performance. Al:BiVO₄ synthesized at 8 h hydrothermal treatment parades excellent sunlight-driven photocatalysis compared to the one synthesized at 4 h.

• 한국식품영양과학회지
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• 제32권8호
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• pp.1323-1327
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• 2003

감은 예전부터 민간약으로 종기나 염증질환, 치질에 곶감을 이겨 붙였고 부스럼이나 화상에는 불에 말린 감을 바르면 통증을 멎게 하고 새살을 돋게 하는 효능이 있고 고혈압을 예방하고 동맥경화에 효과가 있는 성분이 있다고 알려져 있다. 사람의 plasma에서 thrombin time(TT)를 사용한 혈액 응고저해 assay를 이용하여 감꼭지에서 혈액응고저해물질을 겔여과크로마토그래피, 소수성크로마토그래피, 음이온교환크로마토그래피, 또 한번의 겔여과크로마토그래피를 통해 정제했다. 감꼭지의 혈액응고저해물질은 분자량이 130,000 ∼ 180,000으로 거대 분자이고 구성분은 C, H, O로 구성되어 있고 periodate oxidation시 거의 활성이 소멸되고 열에 안정하며 주로 glucose와 galactose로 구성된 다당류로 추정된다.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2984-2988
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• 2009

A gene (PH0311) encoding a hypothetical protein from the genome sequence data of the hyperthermophilic archaeon Pyrococcus horikoshii OT3 was cloned and over-expressed in Escherichia coli. The purified recombinant protein was found to possess FAD-dependent NADH oxidase activity, although it lacked sequence homology to any other known general NADH oxidase family. The product of the PH0311 gene was thus designated PhNOX (NADH oxidase from Pyrococcus horikoshii), with an estimated molecular weight of 84 kDa by gel filtration and 22 kDa by SDS-PAGE, indicating it to be a homotetramer of 22 kDa subunits. PhNOX catalyzed the oxidation of reduced ${\beta}$-NADH with subsequent formation of $H_2O_2$ in the presence of FAD as a cofactor, but not ${\alpha}$-NADH, ${\alpha}$-NADPH, or ${\beta}$-NADPH. PhNOX showed high affinity for ${\beta}$-NADH with a Km value of 3.70 ${\mu}$M and exhibited optimum activity at pH 8.0 and 95$^{\circ}C$ as it is highly stable against high temperature.

• BMB Reports
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• 제33권6호
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• pp.514-518
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• 2000

Two open reading frames of Haemophilus influenzae, HI0572 and HI0751, showing homology to a yeast thioredoxin peroxidase II (TPx II) and an E. coli thiol peroxidase $P_{20}$, respectively, were cloned and expressed in E. coli, and then the proteins were subsequently purified and characterized. HI0751 protein showed the thioredoxin (Trx)-dependent peroxidase activity, whereas HI0572 protein showed glutathione-dependent peroxidase. The HI0572 is the first peroxiredoxin with glutathione peroxidase activity rather than thioredoxin peroxidase. Purified HI0572 and HI0751 proteins protected specifically the inactivation of glutamine synthetase by metal catalyzed oxidation (MCO) systems composed of $Fe^{3+}$, $O_2$ and mercaptans such as dithiothreitol, ${\beta}-mercaptoethanol$ and glutathione (GSH). Unlike the HI0751 protein, the HI0572 protein was more effective in protecting glutamine synthetase from inactivation by the $GSH/Fe^{3+}/O_2$ system. It seems that these unique properties of the HI0572 protein are due to the structure containing a glutaredoxin domain at it's C-terminal in addition to a peroxiredoxin domain.