• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.10a
• /
• pp.17.2-17.2
• /
• 2011

Double-walled carbon nanotubes (DWCNTs) were grown with vertical alignment on a Si wafer by using catalytic thermal chemical vapor deposition. This study investigated the effect of pre-annealing time of catalyst on the types of CNTs grown on the substrate. The catalyst layer is usually evolved into discretely distributed nanoparticles during the annealing and initial growth of CNTs. The 0.5-nm-thick Fe served as a catalyst, underneath which Al was coated as a catalyst support as well as a diffusion barrier on the Si substrate. Both the catalyst and support layers were coated by using thermal evaporation. CNTs were synthesized for 10 min by flowing 60 sccm of Ar and 60 sccm of H2 as a carrier gas and 20 sccm of C2H2 as a feedstock at 95 torr and $750^{\circ}C$. In this study, the catalyst and support layers were subject to annealing for 0~420 sec. As-grown CNTs were characterized by using field emission scanning electron microscopy, high resolution transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. The annealing for 90~300 sec caused the growth of DWCNTs as high as ~670 ${\mu}m$ for 10 min while below 90 sec and over 420 sec 300~830 ${\mu}m$-thick triple and multiwalled CNTs occurred, respectively. Several radial breathing mode (RBM) peaks in the Raman spectra were observed at the Raman shifts of 112~191 cm-1, implying the presence of DWCNTs, TWCNTs, MWCNTs with the tube diameters 3.4, 4.0, 6.5 nm, respectively. The maximum ratio of DWCNTs was observed to be ~85% at the annealing time of 180 sec. The Raman spectra of the as-grown DWCNTs showed low G/D peak intensity ratios, indicating their low defect concentrations. As increasing the annealing time, the catalyst layer seemed to be granulated, and then grown to particles with larger sizes but fewer numbers by Ostwald ripening.

• The Korean Journal of Physiology and Pharmacology
• /
• v.7 no.6
• /
• pp.357-362
• /
• 2003

Carbon monoxide (CO) is low molecular weight oxide gas that is endogenously produced under physiological conditions and interacts with another gas, nitric oxide (NO), to act as a gastrointestinal messenger. The aim of this study was to determine the effects of exogenous CO on L-type calcium channel currents of human jejunal circular smooth muscle cells. Cells were voltage clamped with 10 mM barium ($Ba^{2+}$) as the charge carrier, and CO was directly applied into the bath to avoid perfusion induced effects on the recorded currents. 0.2% CO was increased barium current ($I_{Ba}$) by $15{\pm}2$% ($mean{\pm}S.E.$, p<0.01, n=11) in the cells. To determine if the effects of CO on barium current were mediated through the cGMP pathway, cells were pretreated with 1-H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, $10{mu}M$), a soluble guanylyl cyclase inhibitor, and exogenous CO (0.2%) had no effect on barium currents in the presence of ODQ ($2{\pm}1$% increase, n=6, p>0.05). CO mediates inhibitory neurotransmission through the nitric oxide pathway. Therefore, to determine if the effects of CO on L-calcium channels were also mediated through NO, cells were incubated with $N^G-nitro-L-arginine$ (L-NNA, 1 mM), a nitric oxide synthase inhibitor. After L-NNA pretreatment, 0.2 % CO did not increase barium current ($4{\pm}2$% increase, n=6, p>0.05). NO donor, SNAP ($20{\mu}M$) increased barium current by $13{\pm}2$% (n=6, p<0.05) in human jejunal smooth muscle cells. These data suggest that CO activates L-type calcium channels through NO/cGMP dependant mechanism.

• YAKHAK HOEJI
• /
• v.36 no.3
• /
• pp.278-284
• /
• 1992

This study was performed to investigate the effects of ginseng saponins on the cerebral energy metabolite's contents influenced by carbon monoxide(CO) intoxication. Each experimental group was divided young ($5{\sim}8$ weeks) and aged ($43{\sim}52$ weeks) rats, and they were exposed at 5,000 ppm CO (72%HbCO) for 30 min. One of the other groups was pretreated with ginseng saponins for 5 days before CO intoxication. The contents of cerebral energy metabolites in cerebral cortex, stratum and hypothalamus were measured. In cerebral cortex of both young and aged rats, the levels of ATP and creatine phosphate were significantly decreased, while those of lactate were significantly increased. There was no difference between the levels of cerebral energy metabolites of young and aged rats. Pretreatment of ginseng saponins before CO intoxication lowered decrease of the levels of cerebral energy metabolites and ATP levels were significantly recovered. On the other hands, contents of lactate in stratum and hypothalamus of young rats were significantly increased and the levels of ATP and creatine phosphate in stratum and hypothalamus were completely recovered at 2 weeks after CO intoxication. The results suggest that ginseng saponins have an ameliorating action against disturbance of the cerebral energy metabolites by CO intoxication.

• Korean Journal of Veterinary Research
• /
• v.50 no.2
• /
• pp.145-149
• /
• 2010

This study was carried out to find whether phenidone (1-phenyl-3-pyrazolidinone), a cyclooxygenase as well as a lipoxygenase inhibitor, exhibits the preventive effect on carbon tetrachloride $(CCl_{4})-induced$ acute liver injury in rats. Rats were pretreated with phenidone at a dose of 50 or 200 mg/kg (p.o.) once daily for 3 consecutive days before $CCl_{4}$ administration. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured. Malondialdehyde (MDA) production was determined as an index of lipid peroxidation in the liver and serum. The histopathological changes in the liver were also examined in each group. The reduction in body weights was significantly inhibited in the phenidone-treated group than in the $CCl_{4}$ control group. Significant increase in the relative liver weights of the phenidone-treated groups was observed compared with either the vehicle or $CCl_{4}$ groups. Elevation of serum AST and ALT activities occurred after $CCl_{4}$ treatment was significantly attenuated by the pretreatment with phenidone. The elevation of MDA levels in liver and serum were completely inhibited in phenidone-treated groups. The protective effects on phenidone-treated groups were confirmed histopathologically. These results suggest that phenidone may be a useful protector through modulation of hepatic inflammation in $(CCl_{4})-induced$ acute liver injury.

• Analytical Science and Technology
• /
• v.12 no.3
• /
• pp.218-223
• /
• 1999

A single use, screen-printed sensor for the measurement of liquid phase ethanol was developed and its electrochemical performance was investigated. Disposable type edthanol sensor was fabricated by serially screen printing the carbon paste, silverd pasted and insulator inlon a polyester substrate to pattern working and reference electrode sites and electrical contact. Alcohol dehydrogenase(ADH) or alcohol oxidase(AOD) together with appropriate electron transfer mediators was immobilized on the working electrode. To improve the sensitivity and reproducibility of carbon paste electrode, some pretreatment procedures were applied and their resultant electrochemical performance was examined. The disposable type electrochemical ethanol sensor developed in this study conveniently determines the ethanol in liquid samples such as blood and in fermentation process.

• Archives of Pharmacal Research
• /
• v.24 no.2
• /
• pp.114-118
• /
• 2001

The present study was undertaken to investigate whether or not the hepatoprotective activity of acetylbergenin was superior to bergenin in carbon tetrachloride ($CCl_4$)-intoxicated rat. Acetylbergenin was synthesized by acetylating bergenin, which was isolated from Mallotus japonicus. The hepatoprotective effects of acetylbergenin were examined against $CCl_4$-induced liver damage in rats by means of serum and liver biochemical Indices. Acetylbergenin was administered orally once daily for 7 successive days, then a 0.5 ${m/kg}$ mixture of $CCl_4$in olive oil (1:1) was intraperitoneally injected at 12 h and 36 h after the final administration of acetylbergenin. Pretreatment with acetylbergenin reduced the elevated serum enzymatic activities of alanine/aspartate aminotransferase, sorbitol dehydrogenase and $\gamma$-glutamyltransferase in a dose dependent fashion. Acetylbergenin also prevented the elevation of hepatic malondialdehyde formation and depletion of glutathione content dose dependently in $CCl_4$-intoxicates rats. In addition, the decreased activities of glutathione S-transferase and glutathione reductase were restored to almost normal levels. The results of this study strongly suggest that acetylbergenin n has potent hepatoprotective activity against $CCl_4$-induced hepatic damage in rats by glutathione-mediated detoxification as well as having free radical scavenging activity. In addition, acetylbergenin doses of 50 ${mg/kg}$showed almost the same levels of hepatoprotection activity as 100 ${mg/kg}$ of bergenin, indicating that lipophilic acetylbergenin is more active against the antihepatotoxic effects of $CCl_4$ than those of the much less lipophilic bergenin.

• Advances in Traditional Medicine
• /
• v.4 no.1
• /
• pp.28-36
• /
• 2004

The purpose of this study was to investigate the pharmacological effects of low-esterified pectin on carbon tetrachloride $(CCL_4)-induced$ hepatotoxicity in rats. The study included two experiments. In the first experiment the animals were given daily $CCL_4$ through gavage for 7 days and then 10, 50, or 250 mg/kg b.w. of pectin for 21 days. At the end of experiment rats were killed within 24 hours. The increased bilirubin level, enhanced alanine aminotransferase and aspartate aminotransferase activity in plasma induced by $CCL_4$ were partly normalized by pectin administration in a dose-dependent manner. The pectin treatment also resulted in significant recovery of $CCL_4-induced$ decrease of the liver glycogen content. In addition, pectin significantly improved $CCL_4-induced$ alterations of pro-oxidant and antioxidant biochemical parameters in liver and plasma compared to those of rats administered $CCL_4$. In the second experiment the animals were given daily 10, 50 or 250 mg/ kg b.w. of pectin for 21 days before a 7-day administration of $CCL_4$. Rats were killed 24 hours after the end of experiment. Pretreatment with pectin before $CCL_4$ administration resulted in significantly inhibited increase of the blood enzymatic activities of alanine and aspartate aminotransferases and bilirubin level in a dose-dependent manner. Also, preliminary administration of pectin prevented elevation of malondialdehyde and conjugated diene levels in liver and plasma as well as a reduction of glutathione content in liver of rats given $CCL_4$. These results suggest that low-esterified pectin exert healing and preventive effects on $CCL_4-induced$ hepatotoxicity in rats.

• Toxicological Research
• /
• v.25 no.1
• /
• pp.29-33
• /
• 2009

Phellinus gilvus (PG) is a widely used mushroom for health promotion. We studied the hepatoprotective effect of the polysaccharide aqueous extract of PG (PGP) against carbon tetrachloride ($CCl_4$)-induced liver injury in rats. Sprague Dawley rats were divided into 5 groups: Normal control, $CCl_4$ control, PGP 50, 100, and 200 mg/kg + $CCl_4$. The levels of serum biochemical parameters, liver lipid peroxide and antioxidant enzymes, and histological appearances were evaluated. The $CCl_4$-induced increments of alanine aminotransferase, asparate aminotransferase, and alkaline phosphatase levels in serum were significantly decreased by PGP-pretreatments. The PGP dose-dependently decreased hepatic malondialdehyde formations in $CCl_4$-treatment groups. Hepatic antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) were elevated by PGP in $CCl_4$-treatment groups. Histopathological evaluation of liver showed that the loss of hepatocytes, fatty changes, swelling and extensive necrosis of hepatocytes in centrilobular regions of the $CCl_4$-treated rats were ameliorated by PGP pretreatment. The PGP has hepatoprotective and antioxidative effects in $CCl_4$-induced liver injury of rat.

• Archives of Pharmacal Research
• /
• v.10 no.1
• /
• pp.36-41
• /
• 1987

The conversion of xanthine dehydrogenase (type D) into xanthine oxidase (type D) was significantly increased in serum and liver of all $CCI_4$ treated rats on the necrosis and early cirrhosis stage of liver tissue. In the pretreatment of prednisolone, the ratio of type O per type O + D showed the decreasing tendency in serum, but the significant decrease in liver. In vitro, the conversion of liver xanthine oxidase from type D into type O was markedly increased by following preincubation with lysosomal fraction. The type conversion of xanthine oxidase may be caused by protelytic enzymes in lysosome.

• Microbiology and Biotechnology Letters
• /
• v.24 no.3
• /
• pp.376-379
• /
• 1996

Cane molasses, the most widely used carbon source for the industrial fermentation of L-lysine, usually contains a high concentration of calcium ions which tend to cause scaling problem in the recovery process. To remove the calcium ions, cane molasses was pretrea ted with sulfuric acid by adjusting the pH to 2.5-3.5. When the pretreated solution was directly heat-sterilized and used in the fermentation, a significant reduction in L-lysine production was observed. In this paper, we proved that sucrose is a superior substrate for L-lysine fermentation to that of glucose or fructose and that the above-mentioned decrease of L-lysine production was caused by the hydrolysis of sucrose in the molasses when the molasses was heat-sterilized at a low pH. The problem was overcome by adjusting the pH of molasses to neutral before sterilization.