• Journal of the Korean Ceramic Society
• /
• v.27 no.4
• /
• pp.513-520
• /
• 1990

Diamond film was deposited on Si wafer substrate from a gas mixture of methane, hydrogen and oxygen by microwave plasma-assisted chemical vapor deposition. The effects of the pre-treatments of the substrate and of the oxygen addition on the diamond film synthesis are described. In order to obtain diamond film, the substrate was pre-treated with 3 kinds of methods. When the substrate was ultrasonically vibrated within the ethyl alcohol dispersed with 25${\mu}{\textrm}{m}$ diamond powder, the denset diamond film was deposited. Addition of oxygen in the gas mixture of methane and hydrogen improved the crystallinity of the deposited diamond film and also increased the deposition rate of the diamond film more than two times.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.10
• /
• pp.1670-1674
• /
• 2007

Addition reactions of anilines (XC6H4NH2) to β-nitrostilbene (YC6H4CH=C(NO2)C6H4Y') have been investigated in acetonitrile at 30.0 oC. The magnitude of βX values (=0.11-0.34) indicates relatively earlier transition state for additions with anilines than with benzylamines. The signs of ρY and ρY' are positive with Δρ = ρY?ρY' = 0.04, demonstrating a TS imbalance with a negative charge development on the Cβ in the TS. The signs of cross-interaction constants ρXY (<0), ρXY' (<0) and ρYY' (>0) are consistent with bond forming and breaking processes. The relatively weak normal kinetic isotope effects involving deutarated nucleophiles, kH/kD>1, suggest an early, hydrogen-bonded, 4-member cyclic TS.

• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.4
• /
• pp.2145-2150
• /
• 2016

Background: Infection with hepatitis B virus (HBV) is a major global public health problem, with a wide spectrum of clinical manifestations. Human cytosolic glutathione-S-transferases (GSTs) include several classes such as alpha (A), mu (M), pi (P), sigma (S), zeta (Z), omega (O) and theta (T). The present study aimed to investigate the role of GST omega genes (GSTO1 and GSTO2) in different groups of patients infected with HBV. Materials and Methods: HBV groups were classified according to clinical history, serological tests and histological analysis into normal carriers (N), acute (A), chronic (CH), cirrhosis (CI) and hepatocellular carcinoma (HCC) cases. The study focused on determination of the genotypes of GST omega genes (GSTO1 and GSTO2) and GST activity and liver function tests. Results: The results showed that GSTO1 (A/A) was decreased in N, A, CH, CI and HCC groups compared to the C-group, while, GSTO1 (C/A) and GSTO1(C/C) genotypes were increased significantly in N, A, CH, CI and HCC groups. GSTO2 (A/A) was decreased in all studied groups as compared to the C-group but GSTO2(A/G) and GSTO2(G/G) genotypes were increased significantly. In addition, GST activities, albumin and TP levels were decreased in all studied groups compared to the C-group, while the activities of transaminases were increased to differing degrees. Conclusions: The results indicate that GSTO genetic polymorphisms may be considered as biomarkers for determining and predicting the progression of HBV infection.

• Applied Chemistry for Engineering
• /
• v.26 no.4
• /
• pp.413-420
• /
• 2015

PTMSP-ZIF composite membranes were prepared by the addition of zeolitic imidazolate framework (ZIF-8) into poly (1-trimethylsilyl-1-propyne) (PTMSP) having high gas permeability to improve trade-off relationship of the polymer membrane. PTMSP-ZIF composite membranes were prepared with different amounts of ZIF-8; 0, 5, 10, 20, 30 and 40 wt%. Gas permeation properties for $H_2$, $N_2$, $CO_2$, and $CH_4$ were investigated by increasing the amount of ZIF-8 in the PTMSP. The gas permeability of PTMSP-ZIF composite membranes within 5~30 wt% of ZIF-8 contents increased as ZIF-8 contents went up and decreased thereafter. The gas permeability for $CO_2$ showed the maximum value of 76080 barrer at 30 wt% of ZIF-8 content and PTMSP-ZIF composite membrane containing 20 wt% of ZIF-8 content had the highest selectivity ($CO_2/N_2$) with the value of 8.2. The selectivity ($H_2/N_2$) and selectivity ($CO_2/CH_4$) were almost the same as PTMSP in the range 10~40 wt% of the ZIF-8. Overall, PTMSP-ZIF composite membranes resulted in maintained selectivity and increased permeability compared to those of PTMSP membranes.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.6
• /
• pp.1195-1198
• /
• 2008

Kinetic studies of the additions of benzylamines to a noncyclic dicarbonyl group activated olefin, methyl $\alpha$-acetyl-$\beta$ -phenylacrylates (MAP), in acetonitrile at 30.0 ${^{\circ}C}$ are reported. The rates are lower than those for the cyclic dicarbonyl group activated olefins. The addition occurs in a single step with concurrent formation of the $C_\alpha$ -N and $C_\beta$ -H bonds through a four-center hydrogen bonded transition state. The kinetic isotope effects ($k_H/k_D$ > 1.0) measured with deuterated benzylamines ($XC_6H_4CH_2ND_2$) increase with a stronger electron acceptor substituent ($\delta\sigma$ X > 0) which is the same trend as those found for other dicarbonyl group activated series (1-4). The sign and magnitude of the cross-interaction constant, ρXY, is comparable to those for the normal bond formation processes in the $S_N2$ and addition reactions. The relatively low ${\Delta}H^\neq$ and large negative ${\Delta}S^\neq$ values are also consistent with the mechanism proposed.

• Transactions of the Korean hydrogen and new energy society
• /
• v.30 no.6
• /
• pp.593-600
• /
• 2019

The combustion characteristics of methane/hydrogen pre-mixed flame have been investigated with swirl stabilized flame in a laboratory-scale pre-mixed combustor with constant heat load of 5.81 kW. Hydrogen/methane fuel and air were mixed in a pre-mixer and introduced to the combustor through a burner nozzle with different degrees of swirl angle. The effects of hydrogen addition and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using particle image velocimetry (PIV), micro-thermocouples, various optical interference filters and gas analyzers to provide information about flow velocity, temperature distributions, and species concentrations of the reaction field. The results show that higher swirl intensity creates more recirculation flow, which reduces the temperature of the reaction zone and, consequently, reduces the thermal NO production. The distributions of flame radicals (OH, CH, C₂) are dependent more on the swirl intensity than the percentage of hydrogen added to methane fuel. The NO concentration at the upper part of the reaction zone is increased with an increase in hydrogen content in the fuel mixture because higher combustibility of hydrogen assists to promote faster chemical reaction, enabling more expansion of the gases at the upper part of the reaction zone, which reduces the recirculation flow. The CO concentration in the reaction zone is reduced with an increase in hydrogen content because the amount of C content is relatively decreased.

• Journal of the East Asian Society of Dietary Life
• /
• v.6 no.2
• /
• pp.127-134
• /
• 1996

This study was performed to investigate the effects of green tea activites in rats with administration of aluminum in drinking green tea. Male Sprague-Daweley rats were divided into five groups consisting of the control, aqueous green tea at the level of 1.5%, a aquous green tea(1.5%) and aluminum sulfate solution 500ppm, before the 2 weeks administration by aquous green tea(1.5%) and after the 2 weeks aluminum sulfate solution 500ppm, aluminum sulfate solution 500ppm. After 4weeks of feeding, serum enzymes activites were measured for experimental rats, and analyzed the activites of alanine amino trans aminase(ALT), asparate amino transminase(AST) , lactate dehydrogenase(LDH), cholinesterase(ChE). Comparing to control group, Alanine amino trans aminase (ALT) was decreased in aqueous green tea administrated group and increased significantly administration by aluminum sulfate solution 500ppm group. Alanine amino trans aminase(ALT) was decreased administration by aqueous green tea group and Increased addition to aluminum sulfate solution 500ppm group as compared to control group. Lactate dehydrogenase(LDH) was increased compared to control group by experimental group and increased significantly administration by aluminum sulfate solution 500ppm. Cholinesterase (ChE) activity was decreased compared to control group by experimental group.

• Korean Journal of Materials Research
• /
• v.9 no.8
• /
• pp.804-809
• /
• 1999

Silica films were prepared on Si single crystal substrates by a sol-gel process without DMF using TEOS as a starting material. Films were fabricated by spin coating technique. For films having a composition of TEOS : HCI(1:0.05mol), gelation time, the thickness of films, the formation of cracks and the microstructure of the films were investigated as a function of the molar ratio of $CH_3OH and H_2O$. With 8mol $CH_3OH$, the longest gelation time was measured to be 640hr. The thickness of the coated films was decreased with increasing content of $CH_3OH$. The films were sintered at $500^{\circ}C$ for 1hr with a heating rate of $0.6^{\circ}C$/min. The coated films showed worm-like grains and partially cracked microstructures at an amount of $CH_3OH$ 2mol and 4mol. The addition of more than 8 mole of $CH_2OH$ resulted in crack-free silica films. This suggests that crack-free films can be fabricated by controlling the surface tension energy of the sol solutions without DMF.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.4
• /
• pp.162-168
• /
• 2016

The aim was to investigate the effect of reducing the odorous and complex odor released during the decomposition of food wastes using effective microorganism (EM) as a function of time at $20^{\circ}C$ and $35^{\circ}C$. The variation of total microbial counts and dominant species counts in EM and leachate produced during food wastes decomposition was also observed. In general, the cumulative concentration of sulfur compounds ($H_2S$, $CH_3SH$) and complex odor released during food wastes decomposition increased with increasing elapsed time. The nitrogen compounds ($NH_3$, trimethyl amine), however, was not observed in all samples. The addition of EM in food wastes resulted in the reduction of concentration of sulfur compounds and complex odor, in spite of the increase of $CH_3CHO$ concentration. The dominant microbial species detected in EM were Lactobacillus species(Lactobacillus rhamnosus and Lactobacillus casei). In the leachate produced during food wastes decomposition, however, the various microbial community alternative to that detected in EM was observed. The EM could be potentially useful as a tools for reducing odor induced from the food waste decomposition process.

• Journal of the Korean Chemical Society
• /
• v.18 no.4
• /
• pp.223-238
• /
• 1974

CNDO/2 MO theoretical studies and kinetic studies of halide exchange reactions for alkylchloroformates have been carried out in order to investigate structure-reactivity relationship of alkylchloroformates. From the result of energetics, it was concluded that the most stable configuration of alkylchloroformate is that in which alkyl group and chlorine are trans to each other, and that the hindered rotation about the bond between the carbonyl carbon and alkoxy-oxygen bond is attributed to the ${\pi}-$electron delocalization. It has been found that the large charge separation is due to -M effect of carbonyl and alkoxy oxygens and-I effect of chlorine. The order of rates in solvents studied was $(CH_3)_2 > CO > CH_3CN{\gg}MeOH.$$I^->Br^->Cl^-$ in protic solvent, and of Cl^->Br^- >I^-$ in dipolar aprotic solvents. Alkyl group contribution has the decreasing order of $CH_3-> C_2H-{\gg}i-C_3H_7-.$ The solvent effect has been interpreted on the basis of initial and final state contribution. A transition state model has been suggested, and it has been proposed that the most favorable mechanism is the addition-elimination. From the results of activation parameters and electronic properties, an energy profile has been proposed. Structural factors determining reactivities of alkylchloroformates have been shown to be charge, energy level of ${\alpha}^*LUMO$ to C-Cl bond and ${\alpha}^{\ast} $antibonding strength with respect to C-Cl bond in this MO. Charge and polarizability of nucleophile, and the interaction of these effects with solvent structures are also found to be important.