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Hydrogen gas is used as a fuel for the proton exchange membrane fuel cell (PEMFC). Trace amount of carbon monoxide present in the reformate H₂ gas can poison the anode of the PEMFC. Therefore, preferential oxidation (PROX) of CO is essential for reducing the concentration of CO from a hydrogen-rich reformate gas. In this study, conventional Pt/Al₂O₃catalyst was prepared for the preferential oxidation of CO. The effects of catalyst preparation method, additive, and hydrogen on the performances of PROX reaction of CO were investigated. Water treatment and addition of Ce enhanced catalytic activity of the Pt/Al₂O₃ catalyst at low temperature below 100℃.
We reviewed 549 electrocardiograms obtained from 95 patients with Korean hemorrhagic fever to investigate the incidence and electrocardiographic characteristics, observe evolutional changes in those findings during the course of illness, identify the correlations with clinical findings, and then suggest pathophysiologic mechanisms in the development of abnormal electrocardiographic findings. The overall incidence of electrocardiographic abnormalites was 95.7%, and the frequency of each phase was 87.8% in the febrile phase, 91.3% in the hypotensive phase, 86.5% in the oliguric phase, 76.4% in the diuretic phase and 43.0% in the convalescent phase. The cardinal electrocardiographic findings were QT prolongation(82.1%), sinus bradycardia(73.7%), prominent U wave(53.7%), tall and peaked T wave(51.6%), ST-T changes(41.1 %) and sinus tachycardia(35.8%). The most frequently observed electrocardiographic findings of each phase were sinus tachycardia in the febrile and hypotensive phase, QT prolongation in the oliguric phase, sinus bradycardia in the diuretic phase and prominent U wave in the convalescent phase. The occurrence of abnormal electrocardiograms increased in patients with high serum creatinine levels during the oliguric and diuretic phases. The electrocardiographic abnormalities that persisted to the convalescent phase were QT prologation(seven cases), prominent U wave(seven cases), sinus bradycardia(five cases), and tall and peaked T wave(four cases). Even though almost all of the electrocardiographic abnormalities were mild and recovered shortly after the convalescent phase and there were no diagnostic electrocardiograms, we observed noteworthy electrocardiographic characteristics and evolutional changes during the course of illness and suggested the primary electrocardiographic changes in Korean hemorrhagic fever.
This study was undertaken to investigate the mutagenicity and antimutagenicity of Acanthopanax koreanum Nakai. Antimutagenic study on extract of A. koreanum was studied using the test with Salmonella typhimurium TA100, TA98. And mutagenicity study was studied using the test with S. typhimurium TA100, TA98, TA1535,TA1537 and Escherichia coli WP2 uvr A. A. koreanum was negative in Ames test with S. typhimurium and E. coli with or without S-9 mixture. Test substances of 5000 μg/μl, 2500 μg/μl and 600 μg/μl of A. koreanum extracts were chosen via toxicity test. Ames test was performed on positive control group, experimental group and negative control group in the presence of the metabolic activation system and metabolic non-activation system. As a result, there was no coherent increase and reverse mutation in all concentrations. Therefore, A. koreanum does not cause reverse mutation. In addition, A. koreanum showed strong antimutagenic activities in S. typhimurim TA100 and TA98. In conclusion,A. koreanum root may be an excellent antimutagenic agent.
원주의 가공기술을 개발하기 위한 초기 연구로써 진주 층 및 삽입 핵(CaCO3)을 사용하여 염료의 흡착 특성을 조사해 보았다. 진주 염색에 사용되는 것으로 알려져 있는 Rhodamine 6G, Rhodamine B, Methylene Blue를 염료로 선택하여 물, 메탄올, 에탄올, 아세톤 등의 용매를 사용하여 용해시킨 결과 염료용액 제조시 염료의 용해도로 인한 문제는 없는 것으로 판단되었다. 진주 층과 삽입 핵(CaCO3)을 60 micron크기로 파쇄한 후 Porosimeter를 사용하여 기공크기 면적과 내부표면적을 측정해 보았다. 측정 결과 기공크기, 기공체적, 내부표면적은 진주 층의 경우 대략 100 Å, 0.035 cm3/g, 1 m2/g, 삽입 핵은 대략 200 Å, 0.0116 cm3/g, 2m2/g 정도인 것으로 나타났다. Rhodamine 6G를 염료로 사용하여 진주 층과 삽입 핵에의 회분식 흡착 실험 결과 대략 20시간과 30시간 후에 각각 평형에 도달하는 것으로 나타났다. 평형 흡착 능의 경우 삽입핵에의 흡착 량은 진주 층에의 흡착 량의 약 20%에 해당되는 것으로 나타나 진주 핵에도 염료가 일부 흡착된다는 사실을 확인하였다. 탈착실험 결과 탈착률은 대략 13% 정도로 동일하나 삽입 핵의 탈착 평형 시간은 대략 10시간 정도로 진주 층의 50시간에 비해 5배 빠른 것으로 나타났다. This study represents characteristics of dye adsorption onto pearl and pearl nucleus (CaCO3). Three basic dyes such as Rhodamine 6G, Rhodimine B, and Methylene Blue were selected as model compounds for adsorption experiments because they were known to be used for processing pearls. Solubility of the dyes were investigated with various solvents such as distilled water, methanol, ethanol, and acetone and were found to be out of the range of precipitation. Pearl and pearl nucleus were reduced to powder of 60 ㎛ size and the pore characteristics of the powders were investigated using porosimeter. The pore size, pore volume, and surface area were found to be approximately 100 Å, 0.035 cm3/g, 1 m2/g for pearl and 200 Å, 0.0116 cm3/g, 2m2/g for pearl nucleus. From the batch adsorption experiment using Rhodamine 6G, it was found that equilibrium reached after 20 hours for pearl and 30 hours for pearl nucleus, respectively. Adsorption loading for pearl was 5 times larger than that for pearl nucleus. Desorption experiment showed that desorption percent was 13% for both adsorbents. However, time for desorption equilibrium for pearl nucleus was 10 hours and was 5 times shorter than that for pearl.
A novel pretreatment technique was applied to the conventional Pt/alumina catalyst to prepare for the highly efficient catalyst for the preferential oxidation of carbon monoxide in hydrogen-rich condition. Their performance was investigated by selective CO oxidation reaction. CO conversion with the oxygen-treated Pt/Alumina catalyst increased remarkably especially at the low temperature below 100℃. This result is promising for the normal operation of the proton exchange membrane fuel cell (PEMFC) without CO poisoning of the anode catalyst. XRD analysis results showed that metallic Pt peaks were not observed for the oxygen-treated catalyst. This implies that well dispersed small Pt particles exist on the catalyst. This result was confirmed by high resolution transmission electron microscopy (HRTEM) analysis. Consequently, it can be concluded that highly dispersed Pt nanoparticles could be prepared by the novel pretreatment technique and thus, CO conversion could be increased considerably especially at the low temperatures below 100℃.