• Genomics & Informatics
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• v.8 no.4
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• pp.170-176
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• 2010

The Ribonucleotide reductases (RNR) are essential enzymes that catalyze the conversion of nucleotides to deoxynucleotides in DNA replication and repair in all living organisms. The RNRs operate by a free radical mechanism but differ in the composition of subunit, cofactor required and regulation by allostery. Based on these differences the RNRs are classified into three classesclass I, class II and class III which depend on oxygen, adenosylcobalamin and S-adenosylmethionine with an iron sulfur cluster respectively for radical generation. In this article thirty seven sequences belonging to each of the three classes of RNR were analyzed by using various tools of bioinformatics. Phylogenetic analysis, dot-plot comparisons and motif analysis was done to identify a number of differences in the three classes of RNRs. In this research article, we have attempted to decipher evolutionary relationship between the three classes of RNR by using bioinformatics approach.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.421-429
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• 1993

Dissolution reactions of chemical grade zinc sulfide and natural sphalerite were studied in ferric chloride solution as an oxidant. To enhance the leaching reaction, ultrasonic technique was employed in this investigation. For the reaction with pure zinc sulfide, chemical reaction was the rate limiting step in the range of low conversion irrespective of applying ultrasonic wave. And the diffusion through liquid film instead of diffusion through product layer of free sulfur was the rate determining step because ultrasonic vibration removes the product from reaction zone. In the case of sphalerite with the ultrasonic vibrator, it was found that inert mineral layer diffusion was the rate determining step, in which the elemental sulfurs formed were removed by the ultrasonic action. Experimental results showed that the ultrasonic technique proved to be the methods which can significants improve the leaching performance.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.4
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• pp.481-486
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• 1994

The effect of neutralization of urea-treated rice straw with sulfuric acid was investigated. Long-cut (15-20 cm) and short-cut (2-3 cm) rice straw were treated with 6% urea for 21 days, and the treated straw was mixed with an acid-molasses solution to neutralize free ammonia and kept airtightly in a plastic bag for 24 hours. The neutralized and non-neutralized straw were dried and subjected to chemical analysis and in vitro dry matter (DM) digestibility determination. The in vitro DM digestibility as well as crude protein (CP) content were remarkably improved by neutralization. Short-cutting of the straw before treatment gave a better result than the long-cut samples. Neutralization with sulfuric acid also affected the chemical composition and increased sulfur content of samples. The CP thus fixed by neutralization was proven to be kept stable for 3 months, and in vitro DM digestibility was not affected by the storing period.

• Journal of Korea Foundry Society
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• v.6 no.4
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• pp.277-283
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• 1986

The effects of copper as an alloying element on the microstructure of Compacted Vermicular graphite cast iron which was treated with Mg-REM spheroidizer have been studied. With the increase of copper content up to 2.0wt.%, the following results were obtained; First, the ratio of residual magnesium content in the as-cast iron has been found to be increased, possibly due to the decrease of sulfur content in the melt. Thus, the morphology of graphite in the as-cast iron has been found to be more nodular type. Second, the proportion of pearlite in the matrix has been found to he increased, however the matrix being with free carbide precipitates in the copper range of 1.2wt.% to 2.0wt.%. Third, the tensile strength of the as-cast iron in the temperature up to $400^{\circ}C$ was increased.

• Journal of the Korean institute of surface engineering
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• v.25 no.4
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• pp.173-180
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• 1992

The effects of the stabilizing additives such as NaCN, 2-MBT and Thiourea on bath decom-position, plating rate and surface morphology have been studied. Bath stability was increased in the order of an additive-free bath, and NaCN-, 2-MBT-, and Thiourea-stabilized baths. The sta-bilizing effects may be attributed to the stability of Cu(II) -complexes. The plating rate is the re-verse order of the bath stability. Accelerative effect of 2-MBT in proper quantity(0.3mg/$\ell$) may be explained by visualizing it absorbed through benzene ring or sulfur atom on portions of the sub-strates. The strong bond of the complexing part of the molecule to nearby chelated copper ions would tend to accelerate plating by making it easier for the Cu2+ -ligand bond to be broken. Sur-face morphologies of copper deposits depend on the bath additives. Electroless copper deposits from the 2-MBT stabilized baths are finer than the deposits from the NaCN- and Thiourea- stabi-lized baths due to the strong adsorption on the substrates.

• Journal of the Korean Chemical Society
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• v.11 no.1
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• pp.28-32
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• 1967

The direct acid leaching of domestic Marmatite concentrate at elevated temperatures and pressures was investigated. Almost 100 percent of zinc was extracted from the concentrate liberating free sulfur in 4 hours at $100^{\circ}C$ when the oxygen partial pressure was 5 atm. in sulfuric acid solution. By applying the Arrhenius equation to leach reaction in the range of $60^{circ}$ to $100^{\circ}C$ at the same oxygen partial pressure, 15.7 kcal per mole of activation energy was calculated. At the initial stage of leaching, the rate of reaction increased linearly by increasing temperature and pressure. The concentration of sulfuric acid gave minor effect to leaching velocity in the range of 5 to 20 percent. The particle size should be under 270 mesh for 100 percent extraction of zinc.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.50-58
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• 2018

Elephant garlic (Allium ampeloprasum var. ampeloprasum), which belongs to the Alliaceae family along with onion and garlic, has a flavor and shape similar to those of normal garlic but is not true garlic. Additionally, its properties are largely unknown, and its processing and product development have not been reported. In this study, we focused on using elephant garlic to produce a new type of vinegar, for which the market is rapidly growing because of its health benefits. First, we evaluated the effects of elephant garlic addition on acetic acid fermentation of rice wine by Acetobacter pasteurianus. In contrast to normal garlic, for which 2% (w/v) addition completely halted fermentation, addition of elephant garlic enabled slow but successful fermentation of ethanol to acetic acid. Metabolite analysis suggested that sulfur-containing volatile compounds were less abundant in elephant garlic than in normal garlic; these volatile compounds may be responsible for inhibiting acetic acid fermentation. After acetic acid fermentation, vinegar with elephant garlic did not have any sulfur-containing volatile compounds, which could positively contribute to the vinegar flavor. Moreover, the amino acid profile of the vinegar suggested that nutritional and sensory properties were more enhanced following addition of elephant garlic. Thus, elephant garlic may have applications in the development of a new vinegar product with improved flavor and quality and potential health benefits.

• Microbiology and Biotechnology Letters
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• v.6 no.4
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• pp.173-179
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• 1978

1) To study the productivity of single cell protein from the n-paraffin utilizing yeast, 235 yeast strains were isolatea from 90 samples 2) Optimum cell growth temperature of three strains selected was 40~45$^{\circ}C$ and these were identified as Candida tropicalis, Candida krusei and Torulopsis molischiana. 3) A-28 strain easily assimilated tetradecane, hexadecane and octadecane, but B-8 strain and C-15 strain assimilated more hexadecane than other n-paraffins. 4) Out of the selected three strains, the mass doubling time, specific growth rate and cell yield were 3.4~4.0 hours, 0.170~0.215, 86~98%, respectively. 5) Crude protein, fat, fiber, ash and nitrogen free extract of the selected three strains were found to be 48.2~61.2% 3.7~8.0%, 3.5~4.2%, 5.6~6.7%, 23.5~31.8%, respectively, and thiamine and riboflavin contents of dried yeast cell were 0.78~0.93 mg% and 6.03~7.3 mg%, respectively. 6) Yeast protein contained evenly most of amino acid, but the sulfur-containing amino acids were particularly low.

• Journal of Aquaculture
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• v.3 no.2
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• pp.155-165
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• 1990

The albinic phenomenon of flat-fish (Paralichthys olivaceus) was investigated by measuring protein content, tyrosinase activity, amino acid composition, and contents of vitamin A and C. These materials in the flat-fish feed-stuff were also tested. The amount of skin protein was higher than that of muscle in normal flat-fish. Catechol and L-dopa oxidase activity did not differ between normal and albinic flat-fish. The free amino acid of skin in normal flat-fish was 7.5 times that in albinic one. Sulfur-containing amino acid in normal flat-fish was also 6.3 times that in albinic ones. Vitamin A was not detected in both of flat-fish. The content of vitamin C in normal flat-fish was 7.8 times that in albinic one. The contents of protein, sulfur-containing amino acid and vitamin C in micro-encapsulated feed (one commercial feed in Japan) were the highest among the feed-stuff used in this experiment. The melanin formation of flat-fish skin was affected by substrates such as aromatic amino acid and cofactor such as sulfur amino acid.

• Resources Recycling
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• v.20 no.3
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• pp.48-54
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• 2011

Sulphuric acid leaching was conducted to extract the metal values from spent refinery catalyst. More than 95% of Ni and V and 30% of Mo could be leached out in 1 M sulphuric acid and 1 hr of leaching time. The decrease in Mo leaching was due to typical characteristic of Mo matrix. The activation energies of the leaching reactions showed the dissolution process follows a diffusion control mechanism. In order to leach out all Mo, further the leaching experiments were conducted with sulfur free spent refinery catalyst. For sulfur free spent refinery catalyst, a two step process of leaching with 1 M sulphuric acid followed by sodium carbonate washing showed better leaching than a two step leaching process with sodium carbonate followed by sulphuric acid washing, with almost 99% leaching of Ni, Mo and V. Solvent extraction using LIX 841 were conducted for a leach liquor containing Ni, 2 g/L; V, 9 g/L, Mo, 0.6 g/L. More than 98% of Mo was extracted from the leach liquor at A:O ratio of 5:2 in a 2 stage process. Similarly V was extracted at A:O ratio of 5:3 in a 2 stage process with 82% of total V extraction.