• Journal of the Korean Magnetic Resonance Society
• /
• v.22 no.4
• /
• pp.144-148
• /
• 2018

Catalytic enzyme Pyrazinamidase (PncA) from Mycobacterium tuberculosis can hydrolyze substrate pyrazinamide (PZA) to pyrazoic acid (POA) as active form of compound. Using NMR spectroscopy, pH-dependent catalytic properties were monitored including metal binding mode during converting PZA to POA. There seems to be a conformational change through zinc binding in active site from the perturbation of peak intensities in series of 2D HSQC spectra the conformation changes through zinc binding.

• Korean Journal of Soil Science and Fertilizer
• /
• v.11 no.1
• /
• pp.17-24
• /
• 1978

A field experiment was conducted on a soil where habitual zinc deficiency has been observed, to investigate the effectiveness of two forms of zinc containing fertilizers: zinc enriched fused phosphate and zinc enriched compound fertilizer. The result of present study is summarized as following. 1. The sail used for the study contained relatively large amount of 1N $CH_2COONH_4$ extractable Ca and the pH was 7.03. Available Zn extracted by 0.1 HCl and available $SiO_2$ extracted by NaOAc were 3.35 ppm and 67.7 ppm respectively. 2. In control plots Zinc content of rice plant measured at 20 days after transplanting was 22-23 ppm, which was a little higher than the critical level (20ppm). But at harvesting stage it dropped to 15ppm. 3. The ratios of $P_2O_5/Zn$ and N/Zn tended to lower as the zinc applied to the soil increased. 4. Application of Zinc clearly increased the number of tillers and plant height as compared to the control. It was also observed that the plots received znic headed and matured earlier compared to the control plots by two weeks. 5. Application of zinc increased all of the yield components and the yield of rice. However, there were no statistical differences in yield and yield components among the forms and levels of zinc fertilizers.

• YAKHAK HOEJI
• /
• v.46 no.6
• /
• pp.381-386
• /
• 2002

The synthesis of new 6-exomethylene sulbactam derivatives with 5-methyl-1,3,4-thiadiazole was described. The 6,6-dibromopenam 5 was reacted with $CH_3$MgBr and carbaldehyde 4 to afford the 6-bromo-6-(1-hydroxy-1-methyl)penicillanate 6, which was treated with acetic anhydride to give acetoxy compound 7. The deacetobromination of acetoxy compound 7 with zinc and acetic acid gave 6-exomethylen penams, Z-isomer 8 and E-isomer 9, which was oxidized to sulfones 10 by m-CPBA. The p-methoxybenzyl compounds 6-10 were deprotected by AlCl$_3$ and neutralized with NaOH solution to give the sodium salts 11-15.

• YAKHAK HOEJI
• /
• v.46 no.5
• /
• pp.307-312
• /
• 2002

The synthesis of new 6-exomethylene penams with benzothiazole ring was described. The 6,6-dibromopenam 5 was treated with $CH_3$MgBr and carbaldehyde 4 to afford the 6-bromo-6-(1-hydroxy-1-methyl)penicillanate 6, which was reacted with acetic anhydride to give acetoxy compound 7. The deacetobromination of acetoxy compound 7 with zinc and acetic acid gave 6-exomethylene penams, Z-isomer 8 and E-isomer 9, which was oxidized to sulfones 10 by m-CPBA. The p-methoxybenzyl compounds 6~10 were deprotected by AlCl$_3$ and neutralized to give the sodium salts 11~15.

• Applied Chemistry for Engineering
• /
• v.24 no.4
• /
• pp.433-437
• /
• 2013

Electrical discharge plasma created in a multi-channel porous ceramic membrane-supported catalyst was applied to the decomposition of a volatile organic compound (VOC). For the purpose of improving the oxidation capability, the ceramic membrane used as a low-pressure drop catalyst support was loaded with zinc oxide photocatalyst by the incipient wetness impregnation method. Alternating current-driven discharge plasma was created inside the porous ceramic membrane to produce reactive species such as radicals, ozone, ions and excited molecules available for the decomposition of VOC. As the voltage supplied to the reactor increased, the plasma discharge gradually propagated in the radial direction, creating an uniform plasma in the entire ceramic membrane above a certain voltage. Ethylene was used as a model VOC. The ethylene decomposition efficiency was examined with experimental variables such as the specific energy density, inlet ethylene concentration and zinc oxide loading. When compared at the identical energy density, the decomposition efficiency obtained with the zinc oxide-loaded ceramic membrane was substantially higher than that of the bare membrane case. Both nitrogen and oxygen played an important role in initiating the decomposition of ethylene. The rate of the decomposition is governed by the quantity of reactive species generated by the plasma, and a strong dependence of the decomposition efficiency on the initial concentration was observed.

• Journal of Photoscience
• /
• v.11 no.32
• /
• pp.83-87
• /
• 2004

A porphyrin compound containing a crown ether moiety (Por-Crown) and its zinc complex (ZnPor-Crown) have been prepared and the effect of the addition of alkali metal on their fluorescence has been investigated. As alkali metal cations were added, the absorption and fluorescence maxima did not change. However, the absorbance and intensity of fluorescence increased dramatically. Among the alkali metal cations tested, addition of K$^{+}$ and Cs$^{+}$ showed strongest enhancement of absorbance and fluorescence intensity of Por-Crown and ZnPor-Crown.own.

• YAKHAK HOEJI
• /
• v.44 no.2
• /
• pp.128-134
• /
• 2000

The synthesis of new 6-exomethylene penams with triazole ring was described. The 6,6-dibromopenam 5 was treated with $CH_3$MgBr and carbaldehyde 4 to afford the 6-bromo-6-(1-hydroxy-1-methyl)penicillanate 6, which was reacted with acetic anhydride to give acetoxy compound 7. The deacetobromination of 7 with zinc and acetic acid gave 6-exomethylenpenams, Z-isomer 8 and E-isomer 9, which were oxidized to sulfones 10 and 11 by m-CPBA. The p-methoxybenzyl compounds 6~11 were deprotected by AlCl$_3$ and neutralized to give the sodium salts 12~17.

• YAKHAK HOEJI
• /
• v.41 no.4
• /
• pp.480-483
• /
• 1997

The efficient synthesis of p-(acetylamino)phenylacetic acid(7), a antirheumatic agent, is reported. Methyl phenylacetate(3) was prepared from Friedel- Crafts reaction of benzene with methyl ${\alpha}$-chloro-${\alpha}$-(methylthio)acetate(1) followed by reductive desulfurization with zinc dust in acetic acid. Compound(7) was obtained from 3 by a sequence of nitration, reduction, N-acylation, and hydrolysis.

• Journal of Adhesion and Interface
• /
• v.4 no.3
• /
• pp.1-8
• /
• 2003

Adhesion between rubber compound and copper-film-coated steel plate (abbreviated hereafter as copper film plate) with different thicknesses of copper film was investigated. Two different methods were employed for the preparation of the copper film plates: a substitution plating of preelectroplated zinc with copper ion and a vacuum sputtering of copper on steel plate. Adhesion strength of the copper film plates with rubber compounds was largely dependent upon the thickness of copper film, regardless of their preparation methods. The copper film plates with thinner thickness than 75 nm showed high adhesion comparable to brass, while those with thicker copper film showed poor adhesion due to excessive growth of copper sulfide at adhesion interface.

• Journal of Korea Foundry Society
• /
• v.39 no.3
• /
• pp.33-43
• /
• 2019

In this study, the effects of Zn additions on the mechanical properties of Al-Si-Mg-Cu alloys were investigated by increasing the amount of Zn up to 8wt.%. As the Zn content was increased up to 6 wt.%, the yield strength and elongation changed linearly without any significant changes in the size and shape of the main reinforcement phase. However, it was confirmed by SEM observation that the Mg-Zn phase formed between the reinforcement phases when the amount of Zn added exceeded 7wt.%. A Mg-Zn intermetallic compound formed between the $Mg_2Si$ phase, becoming a crack initiation point under stress. Thus, the formation of the Mg-Zn phase may cause a sharp decrease in the elongation when Zn at levels exceeding 7 wt.%. It was also found that the matrix became more brittle with increasing the Zn content. From these results, it can be concluded that the formation of the Mg-Zn intermetallic compound and the brittle characteristics of the matrix are the main causes of the remarkable changes in the mechanical properties of this alloy system