• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.279-280
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• 2003

지구상의 대기환경 중에 가스상의 형태로 존재하는 황화합물은 크게 두 가지 유형으로 분류된다. 인류의 산업활동과 같은 여러 유형의 인위적 배출원을 통해 배출되는 황화합물의 절대적인 부분을 차지하며 가스상 산화물의 형태로 존재하는 이산화황과 같은 성분은 인위적 기원의 황성분을 대표한다 (Spiro et al., 1992). 그런데 이들과 달리 자연적인 조건에서 생물활동의 결과로 지구의 대기환경 중으로 유입되는 황화합물들은 그 종류가 다양할 뿐 아니라, 산화도가 낮은 환원황화합물 (reduced sulfur compounds)의 형태로 존재한다. (Andreae, 1990). (중략)

• Journal of Microbiology and Biotechnology
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• v.19 no.1
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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.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.180-187
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• 2005

Nine chemolithoautotrophic and 12 chemolithoheterotrophic sulfur oxidizing bacteria were isolated using enrichment technique in modified Starkey's medium. All isolates reduced pH of the growth medium through oxidation of elementai sulfur to sulfuric acid. Isolates utilized the thiosulfate as energy source except LCH. None of the isolates grew anaerobically and utilization of glucose was found only in chemolithoheterotrophic isolates SGA6 and JIG. In vitro sulfate production from elemental sulfur was found maximum for chemoiithoautotroph LCH ($43.2mg\;100\;mL^{-1}$) and least for chemolithoheterotroph JIG ($10.04mg\;100\;mL^{-1}$). The above tests suggested that all isolates belong to the member of Thiobacillus. For field inoculation of Thiobacillus, clay based pellet formulation was developed with the cell load of $2.5{\times}10^7cfu\;g^{-1}$ of pellet. It is easy to handle by the farmers and more likely to lead to successful farming.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.893-899
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• 2018

In the present study, we investigated the sulfur poisoning of the Ni anode in solid oxide fuel cells (SOFCs) as a function of operating conditions. Anode supported cells were fabricated, and sulfur poising tests were conducted as a function of current density, $H_2S$ concentration and humidity in the anode gas. The voltage drop was significant under the higher current density (${\sim}714mA/cm^2$) condition, while it was much reduced under the lower current density (${\sim}389mA/cm^2$) condition, at 100 ppm of $H_2S$. A secondary voltage drop, which occurred only at the high current density, was attributed to Ni oxidation in the anode. Thus, operation at high current density with high $H_2S$ concentration may lead to permanent deterioration in the anode. The effect of water content (10%) on the sulfur poisoning was also investigated through a constant current test (${\sim}500mA/cm^2$) at 10 ppm of $H_2S$. The cell operating with 10% wet anode gas showed a much smaller initial voltage drop, in comparison with a dry anode gas. The present study indicates that operating conditions, such as gas humidity and current density, should be carefully taken into account, especially when fuel cells are operated with $H_2S$ containing fuel.

• Korean Journal of Environmental Agriculture
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• v.33 no.3
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• pp.198-204
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• 2014

BACKGROUND: Caused by cultural environment, the fruit skin stain results in serious damages to pear fruit. Particularly susceptible to this damage, 'Niitaka' pear accounts for 82% of pear cultivation in Korea and many farmers growing the pear trees have suffered economic losses due to fruit skin stain. This study investigated the effect of different treatments of 'Niitaka' pear during growing period on the occurrence of fruit skin stain. METHODS AND RESULTS: The treatments in the field included gibberellin (GA) paste, spraying with amino acid tree fertilizer, functional bagging, and coating of the inner paper bag with agents. The relationships between tree vigor, mineral nutrition concentration and fruit skin stain occurrence were also investigated. The fruit skin stain symptoms occurred from young fruit (May 25) until harvest. There was no exposed fruit flesh. The occurrence of fruit skin stain was significantly reduced in normal tree (shoot length 110 cm), as well as using GA paste treatment, and bagging in calcium and lime sulfur coated bags. However, spraying with amino acid tree fertilizer made no difference in comparison to control. In addition, bags in which the inner paper was coated with lime sulfur and soybean oil resulted in chemical injury to the fruit skin caused by bagging. The K concentration of shoot wood and fruit skin were higher than those of the control. Also, there were lower T-N, K concentration of leaf. CONCLUSION: These results suggest that occurrence of fruit skin stain in 'Niitaka' pear fruits during the growing period can be reduced by GA paste and bagging in calcium and lime sulfur coated bags. The symptoms of chemical injury to the fruit skin caused by bagging in lime sulfur and soybean oil coated inner paper were different compared to skin stain occurring in fruit during the growing period.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.574-581
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• 2022

Nanofibers comprising reduced graphene oxide (rGO) and Mo₂C/Mo₂N nanoparticles (Mo₂C/Mo₂N rGO NFs) were prepared for a functional interlayer of Li-S batteries (LSBs). The well-dispersed Mo₂C and Mo₂N nanoparticles in the nanofiber structure served as active polar sites for efficient immobilization of dissolved lithium polysulfide. The rGO nanosheets in the structure also provide conductive channels for fast ion/electron transport during charging-discharging and ensured reuse of lithium polysulfide during redox reactions through a fast charge transfer process. As a result, the cell assembled with Mo₂C/Mo₂N rGO NFs-coated separator and pure sulfur electrode (70 wt% of sulfur content and 2.1 mg cm^-2 of sulfur loading) showed a stable discharge capacity of 476 mA h g^-1 after 400 charge-discharge cycles at 0.1 C. Furthermore, it exhibited a discharge capacity of 574 mA h g^-1 even at a high current density of 1.0 C. Therefore, we believe that the proposed unique nanostructure synthesis strategy could provide new insights into the development of sustainable and highly conductive polar materials as functional interlayers for high performance LSBs.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.435-444
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• 2003

In 1957, Schwarz and Foltz discovered that selenium (Se) was an essential trace mineral and nutritionists then started extensive studies to figure out the metabolic function of this element which has been called as toxic mineral. The discovery that glutathione peroxidase (GSH-Px) contained Se demonstrated a biochemical role for Se as an essential trace element. The major physiological function of Se containing GSH-Px is thought to maintain low levels of $H_2O_2$ and other hydroperoxides in the cell to prevent tissues from peroxidation damages. It is known that the GSH-Px activity is increased when animals were fed high dietary levels of Se. Chemical properties of Se have much in common with sulfur (S) therefore Se would follow the sulfur pathways in its metabolism in animal body. Two sources of Se are available for supplementation of Se in animal feed. Inorganic Se can also exist in selenide (-2), elemental (0), selenite (+4) and selenate (+6) oxidation state with other minerals. When sulfur in S containing amino acids is replaced by Se, organic Se can be made and named "eleno"prior to the name of S containing amino acid, i.e. selenomethionine. Selenium deficiency affects humans as well as animals and dysfunctions such as exudative diathesis, retained placenta, mastitis, liver necrosis, Keshan disease, numerous diseases and cancer. From several centuries ago, Se toxicity was recognized in various animal species and much of the current toxic Se levels has been established largely based upon the controlled toxicity studies used inorganic Se. Toxic effects of Se in animal result in reduced feed intake, growth retardation, ataxia, diarrhea, alopecia and sloughing of hooves. However, several experiments demonstrated that Se deficiencies or toxicities were varied by dietary Se levels and sources. Recent studies demonstrated that the incidence of colorectal and prostate cancer was reduced by approximately 50% when humans consumed 200 ${\mu}g$ of Se daily.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.1
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• pp.77-85
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• 2004

In this study, the concentrations of reduced S compounds (including hydrogen sulfide (H$_2$S); methyl mercaptan ($CH_3$SH); dimethyl sulfide (($CH_3$)$_2$S); carbon disulfide (CS$_2$); and dimethyl disulfide (($CH_3$)$_2$S$_2$) were determined from landfill gas (LFG) in three municipal landfill sites in the two cities of Gwang Ju (GJ) and Jeju (JJ), Korea. The S gas concentrations measured in these landfill sites were found to be dominated by H$_2$S with its mean concentration of 850 ppm from 10 LFG samples. Both absolute and relative dominance of H$_2$S was seen to be significant in most LFG samples, except those collected from very old and inactive landfills. Unlike the pattern of H$_2$S, other S gases were typically observed at much reduced concentration levels (a few ppm or less) as follows: DMS (3.5); $CH_3$SH (1.3); CS$_2$(1.2); and DMDS (0.02 ppm). If compared equally in mass concentration unit (mg m$^{-3}$ ), H$_2$S generally explained far above 90% of all S gas masses determined concurrently. Moreover, as its mass concentration commonly exceeds those of the major aromatic VOC components in LFG (like benzene and toluene), it appeared to be one of the most dominant gaseous components emitted as LFG in a quantitative sense.

• Journal of Environmental Science International
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• v.22 no.1
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• pp.109-117
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• 2013

The removal characteristics of composite odor and malodorous substances using 33 biofilters in sewage treatment facilities were investigated. The geometry mean values of composite odor and odor quotient were reduced by 52.7% and 59.2% at the outlet of the biofilters, respectively. The removal efficiencies of the biofiltes for the composite odor and odor quotient show a significant difference statistically(p=0.000<0.05). The median value of odor quotient of sulfur compounds was reduced by 69.1% at the outlet of the biofilter and the odor quotient of the sulfur compound at the inlet and outlet of the biofilter shows a significant difference statistically(p=0.000<0.05); on the other hand, those of the $NH_3$ and trimethylamine, aldehydes, VOCs and alcohols, organic acids do not.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.107-118
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• 2005

In this study, the concentrations of major odorous compounds including reduced sulfur compounds (OMS, CS$_2$, and DMDS) and aromatic VOC (benzene, toluene, xylene, etc.) were measured continuously using an on-line GC analytical system. Our measurements were made from a residential area of Ansan sity during about two week period of October, 2004. The highest mean concentrations of Sand VOC were found as 56.9 pbb of DMS and 21.7 ppb of toluene, respectively. The results of this study generally show that the pollution levels for both types of chemicals are significant relative to previous measurement results reported from comparable sites, if the results are compared simply in terms of the magnitude of the measured concentration data. Moreover, when the relative importance of different compounds is compared in terms of the odor strength, it indicated that the contribution of reduced S compounds may be much more important than that of VOC in the study area.