• Advances in Traditional Medicine
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• 제9권2호
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• pp.200-205
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• 2009

The n-hexane and carbon tetrachloride soluble fractions of a methanolic extract of the stem bark of the Couroupita guianensis furnished three compounds, identified as $\beta$-amyrin (1), betulin-$3{\beta}$-caffeate (2) and lupeol-$3{\beta}$-caffeate (3). The structures of the isolated compounds were deduced by extensive spectroscopic analysis as well as by comparison with published values. Compounds 1-3 were subjected to antioxidant screening through free radical scavenging activity by DPPH (1,1-diphenyl-2-picrylhydrazyl), where compound 2 showed moderate antioxidant activity with $IC_{50}$ value $108.0{\mu}g/ml$.

• Journal of Microbiology
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• 제37권1호
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• pp.14-20
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• 1999

Two extracellular proteases, EP I and EP II, from cells of Oligotropha carboxydovorans (formerly Pseudomonas carboxydovorans) DSM 1227 grown in nutrient broth were purified to greater than 95% homogeneity in five steps using azocasein as a substrate. The final specific activities of EPs I and II were 214.9 and 667.4 units per mg of protein. The molecular weights of native EPs I and II were determined to be 23,000. Sodium dodecyl sulfate-gel electrophoresis revealed the two enzymes to be monomers. The enzymes were found to be serine-type proteases. The activity of EP I was stimulated by Ca2+, Mg2+, and Ba2+, but that of EP II was not. The enzymes were completely inhibited by Fe2+, Hg2+, Co2+, Zn2+, and Cd2+. EDTA and EGTA exhibited a strong inhibitory effect on EP I. The optimal pH for the two enzymes was pH 9.0. The optimal temperatures for EP I and II were 60 and 50$^{\circ}C$, respectively. The enzymes were stable under alkaline conditions. The thermal stability of EP I was higher than that of EP II. Cell-free extracts did not inhibit the purified enzymes. The enzymes were active on casein, azocasein, azocoll, and carbon monoxide dehydrogenase, but weakly active with bovine serum albumin.

• 한국식품영양과학회지
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• 제22권6호
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• pp.678-684
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• 1993

To evaluate the role of xanthine oxidase in liver damage by CCl4, a group of rats were fed tungstate for a month, which suppressed the activities of xanthine oxidase in serum and liver. Control group of rats were fed standard diet without tungstate. Liver damage was induced both in tungstate fed and control groups by two intraperitoneal injections of CCl4 at the level of 0.1ml/100g body weight at intervals of 24 hours. Increases in the levels of serum alanine aminotransferase by CCl4 were significantly smaller in tungstate fed rats than in control rats. Concomitantly, histopathologic changes were less in tungstate fed rats than in control ones. In rats either treated with CCl4 or not, hepatic type O xanthine oxidase activities were remarkably reduced by tungstate feeding. Hepatic aniline hydroxylase activities were higher in rats fed tungstate than control rats when animals were not treated with CCl4, but the enzyme activities were lower in tungstate fed rats than control when they were treated with CCl4. Neither tungstate feeding nor CCl4 treatment caused any significant changes in hepatic glutathione contents, and activities of hepatic glutathione S-transferase, glutathione peroxidase and superoxide dismutase. It is concluded xanthine oxidase reaction augment CCl4 induced liver damage via oxygen free radical system.

• 한국환경보건학회지
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• 제26권2호
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• pp.59-66
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• 2000

Effects of carbon dioxide partial pressure(PCO2) on bacterial population, methane production rate and matter degradation in anaerobic digestion were investigated by using anaerobic chemostat type reactors at 35$\pm$1$^{\circ}C$, at the HRT of 7 days. At PCO2 of 0.5 atm, the specific methane production rate and specific substrate removal rate reached the maximum rates. The methane production rates in the reactors fed by mixed substrate were 26% higher than those obtained under the controlled condition. The number of acetate consuming methanogenic bacteria enumerated by the MPN(most probable number) method, decreased when PCO2 exceeded 0.7 atm. Hydrogen consuming methanogenic bacteria and homoacetogenic bacteria increased as PCO2 increased from 0.1 to 0.6 atm, however, decreased slightly at PCO2 above 0.7 atm. The number of hydrolytic bacteria, sulfate-reducing bacteria and H2-producing acetogenic bacterial were not much influenced by the change of PCO2. The potential methanogenic activity reached the maximum at PCO2 0.5 atm, however, decreased significantly when PCO2 exceeded 0.7 atm, would depend on free PCO2 concentration in solution.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.461-462
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• 2015

The government on Jeju Special Self-governing Province has a policy named 'Carbon Free Island Jeju by 2030'. The main purpose in this policy is to install wind power system with the total capacity of 1.35 GW by 2020. When the demand load on Jeju Island power system is lower than entire output power, a lot of dump power will be produced from the large-scale wind farms. It will be able to cause the wind power limit on Jeju Island. Consequently, the additional power facility must be installed to ensure stable power system operation in Jeju Island and increase wind power limit. From this point, this paper proposes the installation of MMC-HVDC, which can supply power in real time in the desired direction. The effectiveness of MMC-HVDC based on measured data of Jeju Island power system will be verified by using PSCAD/EMTDC simulation program.

• Natural Product Sciences
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• 제13권2호
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• pp.105-109
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• 2007

Alcoholic extract of Terminalia arjuna [TA] was evaluated far its hepatoprotective activity against carbon tetrachloride (CCl$_4$)-induced hepatic damage in rats. The hepatoprotective activity of TA was evaluated by measuring levels of serum marker enzymes like serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), serum alkaline phosphatase (SALP). The serum levels of total proteins(TP), total albumins (TAL) and bilirubin (BILN) were also estimated. The histological studies were also carried out to support the above parameters. Silymarin (SM) was used as standard drug. Administration of TA (250 and 500 mg/kg/po) markedly prevented CCl$_4$-induced elevation of levels of SGOT, SGPT, SALP, TP, TAL and BILN. These biochemical observations were supplemented by histopathological examination of liver sections. Alcoholic extract of TA also shown significant in-vitro free radical scavenging activity against 1, 1-diphenyl-2-picryl hydrazyl (DPPH) and nitric oxide (NO) radicals. Thus, the present study provides a scientific rationale for the traditional use of this plant in the management of liver diseases.

• 소성∙가공
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• 제25권6호
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• pp.353-358
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• 2016

Direct energy deposition (DED) is an additive manufacturing technique that involves the melting of metal powder with a high-powered laser beam and is used to build a variety of components. In recent year, it can be widely used in order to produce hard, wear resistant and/or corrosion resistant surface layers of metallic mechanical parts, such as dies and molds. For the purpose of the hardfacing to achieve high wear resistance and hardness, application of high speed steel (HSS) can be expected to improve the tool life. During the DED process using the high-carbon steel, however, defects (delamination or cracking) can be induced by rapid solidification of the molten powder. Thus, substrate preheating is generally adopted to reduce the deposition defect. While the substrate preheating ensures defect-free deposition, it is important to select the optimal preheating temperature since it also affects the microstructure evolution and mechanical properties. In this study, AISI M4 powder was deposited on the AISI 1045 substrate preheated at different temperatures (room temperature to $500^{\circ}C$). In addition, the micro-hardness distribution, cooling rates, and microstructures of the deposited layers were investigated in order to observe the influence of the substrate preheating on the mechanical and metallurgical properties.

• Archives of Pharmacal Research
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• 제20권6호
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• pp.620-628
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• 1997

6-Aryl-5-cyano-4-pyrimidinon-2-thione derivatives 1a-c reacted with ethyl iodide to give the corresponded 2-S-ethylpyrimidin-4-one-derivatives 2a-c. Compounds 2a-c was, in turn, reacted with hydrazine hydrate to give the sulfur free reaction products, 3a-c. These reaction products were taken as the starting materials for the synthesis of several newly synthesized heterocyclic derivatives. Reactions with several halogenated ketones, esters, chloroacetic acid and chloroacetamide give pyrimidotriazines 8,12 and 15 while their reactions with formic acid, acetic acid and carbon disulfide gave the corresponded triazolopyrimidines 17 and 21. The reaction with both acetyl acetone and ethylacetoacetate gave the corresponded 2-$(3^{I},5^{I}-dimethyl-1^{I}-pyrazoly$pyrimidine derivatives 20a-c and 24a-c respectively while the reaction with cinnamonitriles 25a-h afforded the corresponded aryl hydrazopyrimidines 27a-f. The structure of these reaction products were eatablished based on both elemental anlayses and spectral data studies.

• Steel and Composite Structures
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• 제33권1호
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• pp.93-109
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• 2019

In the present study, vibration analysis of double bonded micro sandwich cylindrical shells with saturated porous core and carbon/boron nitride nanotubes (CNT/BNNT) reinforced composite face sheets under multi-physical loadings based on Cooper-Naghdi theory is investigated. The material properties of the micro structure are assumed to be temperature dependent, and each of the micro-tubes is placed on the Pasternak elastic foundations, and mechanical, moisture, thermal, electrical, and magnetic forces are effective on the structural behavior. The distributions of porous materials in three distributions such as non-linear non-symmetric, nonlinear-symmetric, and uniform are considered. The relationship including electro-magneto-hydro-thermo-mechanical loadings based on modified couple stress theory is obtained and moreover the governing equations of motion using the energy method and the Hamilton's principle are derived. Also, Navier's type solution is also used to solve the governing equations of motion. The effects of various parameters such as material length scale parameter, temperature change, various distributions of nanotube, volume fraction of nanotubes, porosity and Skempton coefficients, and geometric parameters on the natural frequency of double bonded micro sandwich cylindrical shells are investigated. Increasing the porosity and the Skempton coefficients of the core in micro sandwich cylindrical shell lead to increase the natural frequency of the structure. Cylindrical shells and porous materials in the industry of filters and separators, heat exchangers and coolers are widely used and are generally accepted today.

• Advances in nano research
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• 제10권3호
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• pp.235-251
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• 2021

In the current study, the free vibrational behavior of a Porous Micro (PM) beam which is integrated with Functionally Graded Piezoelectric (FGP) layers with initial curvature is considered based on the two trigonometric shear deformation theories namely SSDBT and Tan-SDBT. The structure's mechanical properties are varied through its thicknesses following the given functions. The curved microbeam is exposed to electro-mechanical preload and also is rested on a Pasternak type of elastic foundation. Hamilton's principle is used to extract the motion equations and the MCST is used to capture the size effect. Navier's solution method is selected as an analytical method to solve the motion equations for a simply supported ends case and by validating the results for a simpler state with previously published works, effects of different important parameters on the behavior of the structure are considered. It is found that although increasing the porosity reduces the natural frequency, but enhancing the volume fraction of CNTs increasing it. Also, by increasing the central angle of the curved beam the vibrations of the structure increases. Designing and manufacturing more efficient smart structures such as sensors and actuators are of the aims of this study.