• Biotechnology and Bioprocess Engineering:BBE
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• 제5권1호
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• pp.48-52
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• 2000

An autotrophic sulfur oxidizer, Thiobacillus sp. ASWW-2, was isolated from activated sludge, and its sulfur oxidation activity was characterized. Thiobacillus sp. ASWW-2 could oxidize elemental sulfur on the broad range from pH 2 to 8. When 5-50 g/L of elemental sulfur was supplemented as a substrate, the growth and sulfur oxidation activity of Thiobacillus sp. ASWW-2 was not inhibited. The specific sulfur oxidation rate of strain ASWW-2 decreased gradually until sulfate was accumulated in medium up to 10 g/L. In the range of sulfate concentration from 10 g/L to 50 g/L, the sulfur oxidation rate could keep over $2.0g-S/g-DCW{\cdot}d$. It indicated that Thiobacillus sp. ASWW-2 has tolerance to high concentration of sulfate.

• 한국미생물·생명공학회지
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• 제34권4호
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• pp.338-341
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• 2006

The growth characteristics of sulfur-oxidizing bacteria, Acidithiobacillus thiooxidans AZ11, MET, and TAS were investigated in mineral salt media supplemented with elemental sulfur of 1$\sim$50 g $L^{-1}$. The sulfur oxidation rates of A. thiooxidans. MET and TAS increased highly with increasing sulfur concentration up to 10 g L$^{-1}$, but the rates increased slowly in sulfur concentration over 10 g L$^{-1}$. A. thiooxidans AZ11 showed the parallel increase of sulfur oxidation rate until sulfur concentration increased up to 40 g L$^{-1}$. The maximum sulfur oxidation rates (V$_{max}$) of AZl1, MET and TAS were 1.88, 1.38 and 0.43 g S L$^{-1}$ d$^{-1}$, respectively. The maximum specific growth rates (${\mu}_{max}$) of AZ11, MET, and TAS were 0.33 d$^{-1}$, 0.30 d$^{-1}$ and 0.45 d$^{-1}$, respectively. Although MET and TAS couldn't grow at sulfate concentration of 40 g L$^{-1}$, AZ11 could grow in the presence of 58 g L$^{-1}$ sulfate, the final oxidation product of elemental sulfur.

• 한방안이비인후피부과학회지
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• 제20권2호통권33호
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• pp.68-76
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• 2007

Objectives : This experimental study was performed to investigate the effects of Sulfur extract on anti-inflammation and anti-Propionibacterium acnes. Methods : The cytotoxicity of Sulfur extract about viability of Raw 264.7 cell were tested using a colorimetric tetrazolium assay(MTT assay). To investigate the anti-inflammation effects of Sulfur extract on LPS-induced macrophage Raw 264.7 cell, we used ELISA kit and Western blots. We evaluated anti-oxidation effects of Sulfur extract on HaCaT cell by Enzyme recycling method. And we investigated the inhibitory effects of Sulfur extract on Propionibactrium acnes using paper disk diffusion method. Results: 1. Sulfur extract has a little cytotoxicity in Raw 264.7 cell. 2. Concentration of $100\;{\mu}g/m{\ell}$ Sulfur extract inhibited the production of NO in the Raw 264.7 cell stimulated with LPS. 3. Sulfur extract showed a oxidation inhibition effect by decreasing the DPPH radicals. 4. Sulfur extract has not the significant inhibition effect of Propionibactrium acnes. Conclusions: These results indicate that Sulfur extract has anti-inflammation and anti-oxidation effects. If further study is performed, the use of Sulfur extract will be valuable and benificial in the therapy of Propionibactrium acnes.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.17-22
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• 2009

The mixotrophic growth with methanol plus thiosulfate was examined in nutrient-limited mixotrophic condition for Methylobacterium goesingense CBMB5 and Methylobacterium fujisawaense CBMB37. Thiosulfate oxidation increased the growth and protein yield in mixotrophic medium that contained 150mM methanol and 20mM sodium thiosulfate, at 144 h. Respirometric study revealed that thiosulfate was the most preferable reduced inorganic sulfur source, followed by sulfite and sulfur. M. goesingense CBMB5 and M. fujisawaense CBMB37 oxidized thiosulfate directly to sulfate, and intermediate products of thiosulfate oxidation such as polythionates, sulfite, and sulfur were not detected in spent medium and they did not yield positive amplification for tested soxB primers. Enzymes of thiosulfate oxidation such as rhodanese and sulfite oxidase activities were detected in cell-free extracts of M. goesingense CBMB5, and M. fujisawaense CBMB37, and thiosulfate oxidase (tetrathionate synthase) activity was not observed. It indicated that both the organisms use the "non-S4 intermediate" sulfur oxidation pathway for thiosulfate oxidation. It is concluded from this study that M. goesingense CBMB5, and M. fujisawaense CBMB37 exhibited mixotrophic metabolism in medium containing methanol plus thiosulfate and that thiosulfate oxidation and the presence of a "Paracoccus sulfur oxidation" (PSO) pathway in methylotrophic bacteria are species dependant.

• International Journal of Automotive Technology
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• 제7권6호
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• pp.653-658
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• 2006

The enormous increase in the use of fossil energy sources throughout the world has caused severe air pollution and a depletion of energy. Besides, it seems very difficult to comply with the upcoming stringent emission standards in vehicles. In order to develop low emission engines, research on better qualified fuels as alternative fuels to secure high engine performance becomes a more important issue than ever. Since sulfur contained in diesel fuel is transformed in sulfate-laden particulate matters when a catalyst is applied, it is necessary to provide low sulfur fuels before any Pt-based oxidation catalysts are applied. But the excessive reduction of sulfur levels may cause the lubricity of fuel and engine performance to degrade. In this aspect, biodiesel fuel derived from rice bran is applied to compensate viscosity lost in the desulfurization treatment. This research is focused on the performance of an 11,000cc diesel engine and the emission characteristics by the introduction of ULSD(Ultra Low Sulfur Diesel), BD20(Diesel 80%+Biodiesel 20%) and a diesel oxidation catalyst, where BD20 is used to improve the lubricity of fuel in fuel injection systems as fuel additives or alternative fuels.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.870-876
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• 2005

It seems very difficult to comply with upcoming stringent emission standards in vehicles. To develop low emission engines, better quality of automotive fuels must be achieved. Since sulfur contents in diesel fuels are transformed to sulfate-laden particulate matters as a catalyst is applied, it is necessary to provide low sulfur fuels before any Pt-based oxidation catalysts are applied. In general, flash point, distillation $90\%$ and cetane index are improved but viscosity can be worse in the process of desulfurization of diesel fuel. Excessive reduction of sulfur may cause to degrade viscosity of fuels and engine performance in fuel injection systems. This research focused on the performance of an 11,000 cc diesel engine and emission characteristics by the introduction of ULSD, bio-diesel and a diesel oxidation catalyst, where the bio-diesel was used to improve viscosity of fuels in fuel injection systems as fuel additives or alternative fuels.

• 한국대기환경학회지
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• 제13권6호
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• pp.487-495
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• 1997

The most desirable diesel oxidation catalyst (DOC) should have the properties of oxidizing CO, HC and SOF effectively at low exhaust gas temperature while minimizing the formation of sulfate at high exhaust gas temperature. Precious metals such as platinum and palladium have been known to be sufficiently active for oxidizing SOF and also to have high activity for the oxidation of sulfur dioxide $(SO_2)$ to sulfur trioxide $(SO_3)$. There is a need to develop a highly selective catalyst which can promote the oxidation SOF efficiently, on the other hand, suppress the oxidation of $SO_2$. In this study, a Pt-V catalyst was prepared by impregnating platinum and vanadium onto a Ti-Si wash coated ceramic monolith substrate. A prepared Pt-V catalytic converter was installed on a heavy duty diesel engine and the effect of fuel sulfur on particulate matter (PM) of heavy duty diesel engine was measured. The effect of fuel sulfur on PM of Pt-V was also compared with that of a commercialized Pt catalyst currently being used in some of the heavy duty diesel engines in advanced countries. Only 1 $\sim$ 3% of sulfur in the diesel fuel was converted to sulfate in PM for the engine without catalyst, but almost 100% of sulfur conversion was achieved for the engine with Pt catalyst at maximum loading condition. In the case of Pt-V catalyst, there was no big difference in conversion with the base engine even at maximum loading condition. The reason of SOF increase according to the increase of suflate emission was identified as the washing off effect of bound water in sulfate.

• Environmental Engineering Research
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• 제7권3호
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• pp.129-136
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• 2002

• 생명과학회지
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• 제18권1호
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• pp.9-15
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• 2008

마늘의 주성분인 유황 함유 화합물을 이용하여 사람 low density lipoprotein (LDL)의 산화에 대하여 항산화 활성을 실험하였다. 유황함유화합물인 1-methyl-1-cysteine, dimethyl trisulfide 및 1-vinyl-4H-1,3-dithiin의 농도를 각각 40, 60, $80{\mu}g/ml$ 씩 첨가하여 $Cu^{2+}$ 및 macrophages 유도로 LDL을 산화할 때 항산화 효능을 TBARS로 측정한 결과 용량 의존형으로 나타났으며 유황 함유 화합물이 모두 효능이 있었으며 항산화력은 2-vinyl-4H-1,3-dithiin > 1-methyl-1-cysteine > methyl trisulfide 순이었다. 이 때 유황 함유 화합물의 LDL에 대한 공액 2중결합에 대한 항산화 실험에서도 항산화 효과가 있었으며 $60{\mu}g/ml$의 농도에서 거의 억제되었다. 유황 함유 화합물 중에서는 2-vinyl-4H-1,3-dithiin이 다른 유황 함유 화합물에 비하여 약간 높은 항산화 효능을 나타내었다. Endothelial cell을 이용한 LDL의 산화에 대한 억제율은 2-vinyl-4H-1,3-dithiin이 가장 높게 나타났다.

• 대한화학회지
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• 제31권4호
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• pp.322-327
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• 1987

$ZrO_2$의 표면을 $H_2SO_4$로 처리하거나 $SO_2,\;H_2S,\;CS_2$로 처리한 후 산화시킴으로 개질하였다. 처리된 황화합물의 산화종과 산화상태를 적외선분광법과 X-선광전자분광법으로 조사하였다. 처리된 황화합물을 산화시킨 후에는 사용된 황화합물의 종류에는 관계없이 개질된 $ZrO_2$는 모두 강한 산성질을 나타내었다. 개질된 $ZrO_2$가 초강산의 성질을 나타내는 것은 가장 높은 산화상태의 황($SO_4{^{2-}}$)에 기인하였다.