• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.993-1003
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• 2013

Methanotrophs are the most important sink of $CH_4$, which is a more highly potent greenhouse gas than $CO_2$. Methanotrophic abundance and community diversity in cover soils from two typical semi-aerobic landfills (SALs) in China were detected using real-time polymerase chain reaction (real-time-PCR) and denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA genes, respectively. Real time-PCR showed that Type I methanotrophs ranged from $1.07{\times}10^6$ to $2.34{\times}10^7$ copies/g soil and that of Type II methanotrophs from $1.51{\times}10^7$ to $1.83{\times}10^8$ copies/g soil. The ratio of Type II to Type I methanotrophic copy numbers ranged from 5.61 to 21.89, indicating that Type II methanotrophs dominated in SAL. DGGE revealed that Type I methanotrophs responded more sensitively to the environment, changing as the community structure varied with different soil types and locations. Methylobacter, Methylosarcina, and Methylomicrobium for Type I, and Methylocystis for Type II were most prevalent in the SAL cover layer. Abundant interflow $O_2$ with high $CH_4$ concentration in SALs is the reason for the higher population density of methanotrophs and the higher enrichment of Type II methanotrophs compared with anaerobic landfills and other ecosystems, which proved a conclusion that increasing the oxygen supply in a landfill cover layer would greatly improve $CH_4$ mitigation.

• Environmental Engineering Research
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• v.11 no.6
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• pp.311-317
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• 2006

Feasibility of destroying synthetic and actual leachate containing humic acids and ammonia compounds by supercritical water oxidation (SCWO) was evaluated. In this study, destruction efficiencies of humic acids and ammonia respectively were investigated at various reaction temperatures and residence times under pressure a supercritical pressure (280 atm). To lower reaction temperature, chemical oxidants were used. The experiment was carried out in a cylindrical batch reactor made of Hastelloy C-276 that can withstand high temperature and pressure. Concentrations of humic acids and ammonia were measured using a $COD_{Cr}$ method and an ammonia selective electrode, respectively. The optimal destructive condition of humic acids in the presence of stoichiometric oxygen(air) was 3 min at $380^{\circ}C$, but the temperature could be lowered to subcritical region ($360^{\circ}C$) along with $H_2O_2$ as an oxidant. For ammonia, the optimal destructive condition with air was 5 min at $660^{\circ}C$, but it was possible to operate the process for 3 minutes at $550^{\circ}C$ or 2 min at $600^{\circ}C$ along with $H_2O_2$ as an oxidant. At 2 min and $550^{\circ}C$ along with $H_2O_2$ as an oxidant, humic and ammonia compounds in the actual leachate were easily destructed and the effluent quality met the Korea Standard Leachate Quality.

• IMMUNE NETWORK
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• v.2 no.1
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• pp.25-34
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• 2002

Background: Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial hyperplasia and joint destruction. The synovial fibroblasts express cell adhesion molecules and have a role in adhesive interation with inflammatory cells in synovial tissue. It has been suggested that hypoxic conditioins are thought to exist in arthritic joints, and several studies indicate that reactive oxygen species (ROS) produced in hypoxic condition can initiate events that lead to pro-adhesive changes via increased expression of adhesion molecules. So, this study wsa designed to examine whether antioxidant can inhibit hypoxia-induced expression of ICAM-1 in cultured human synovial fibroblasts. Methods: Synovial fibroblasts were isolated from synovial tissue in patients with RA and cultured at hypoxic condition. Antioxidant, PDTC (pyrrolidine dithiocarbamate) were pre-treated for an hour before the hypoxic culture and synovial fibroblasts were harvested at 0, 6, 12, 24, 48 hours time points. Cell surface ICAM-1 expression in synovial fibroblasts was examined by the flow cytometric analysis. To analyse the expression of ICAM-1 mRNA, reverse-transcriptase polymerase chain reaction (RT-PCR) was performed. The levels of cytokines in culture supernatants were measured by ELISA, and activation of NF-${\kappa}B$ was analysed by electrophoretic mobility shift assay. The adhesive reaction between synovial fibroblasts and lymphocytes was assayed by measurement of fluorescent intensity of BCECF-AM in lymphocytes. Results: Hypoxic stimuli up-regulated the ICAM-1 expression as well as the adhesive interaction of human synvial fibroblasts to lymphocytes in a time-dependent manner, and PDTC inhibited hpyoxia-induced ICAM-1 expression and cell-cell interaction. PDTC also inhibited the hypoxia-induced activation of intracellular transcription factor, NF-${\kappa}B$. PDTC decreased the amount of hypoxia-induced production of IL-$1{\beta}$ and TNF-${\alpha}$. Conclusion: These studies demonstrate that PDTC inhibit the hypoxia-induced expression of the adhesion molecule, ICAM-1 and activation of NF-${\kappa}B$ in cultured human synovial fibroblasts.

• Journal of Korean Biological Nursing Science
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• v.10 no.1
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• pp.96-104
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• 2008

Purpose: We had executed the 3 3 5 5 walking club program for 12 weeks for one hour three times per week to evaluate the effect of the program on health of the elderly. Methods: A pre and post measurement tool of the program was applied to measure obesity, rate of body fat, blood pressure, vital capacity, standard vital capacity, intake capacity of maximum oxygen, grasping power, reaction of whole body, pulse, body mass index (BMI), total bodily score, age of bodily strength, age of health. Data collected from this tool was analyzed by SPSS in paired t-test. Results: The 3 3 5 5 walking club program has affected the weight control of the participants. The participants of 3 3 5 5 walking club program reduced their weight from 61.7 kg to 61.25 kg, rate of body fat from 21.89 kg to 21.22 kg, standard vital capacity from 2,393.56 ml to 2,380.44 ml, reaction of whole body from 475.38 msec to 439.33 msec, and increased grasping power from 22.06 to 23.16 ml (p<.05), total bodily score 68.91 points to 71.38 points significantly (p<.05). Conclusion: The result indicated that the 3.3.5.5 Walking club program has an positive effect on improving health care of the elderly without special exercise tools.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.3
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• pp.229-235
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• 2003

A 50W class MCFC stack was operated in order to test a new design of the circular shaped separator. in the new design, the anode gas was supplied into the stack and was exhausted out of the stack after the anode reaction. The exhausted gas was reacted with the cathode gas supplied with excess oxygen in the vessel in which the stack was placed. Then the reacted gas flowed into the cathode side of the stack and was exhausted through the outlet located in the center of the stack. The average voltage of the single cells in the stack was 0.835V under the current density of $150mA/cm^2$, initially, and the degradation rate of the stack voltage was 1.7%/1,000h. High stack voltage with good stability of the present stack was due to the small temperature gradient in the stack. The small temperature gradient as well as the easiness of temperature control was the result of the new configuration of the separator which utilized the heat of the combustion reaction between anode outlet gas and the cathode inlet gas for heating the stack.

• Resources Recycling
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• v.26 no.3
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• pp.39-46
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• 2017

AlN powder was prepared by carbon reduction and subsequent nitridation method through lab- scale experiments. AlN powder was synthesized using the mixture of high purity $Al_2O_3$ powder and carbon black at $1,600{\sim}1,700^{\circ}C$ for 0.5~6 hours under nitrogen atmosphere (flow rate of nitrogen gas: $4.7{\times}10^{-6}{\sim}20{\times}10^{-6}m^3/sec$) with variation of charged height of the mixture powder. Experimental results showed that size of the synthesized particles grows with increasing of temperature. The reaction activation energy was calculated as 382 kJ/mol at the temperature range, and it was considered that chemical reaction is the rate determining step. Content of oxygen and nitrogen of the prpared samples were 0.71~0.96 wt% and 30.7~35.1 wt%. The results was similar with those of the commercial AlN product.

• Journal of Plant Biology
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• v.17 no.2
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• pp.69-83
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• 1974

To elucidate the relationship between chemical structure and biological activity of alantolactone, and also to investigate the relationship between the growth of cells and the respiration of Chlorella pyrenoidosa affected by alantolactone, alantolactone and isoalantolactone were isolated from Inula helenium L., and di-, and tetrahydroalantolactones were prepared by the hydrogenation. At a concentration of 5$\times$10-5M alantolactone, the growth rate of Chlorella was greatly reduced. The viability of cells was also reduced over 50% within 2 hr at a concentration of 2.5$\times$10-4M alantolactone. However, oxygen uptake was increased by 20% over 3 hr. And 14CO2 production from glucose-1-14C, glucose-6-14C and 14C-acetate-U.L. was also increased by alantolactone. Biological activityof alantolactone was significantly reduced by cysteine, reduced glutathione or cystine but not by tryptophan or histidine. It was detected by spectrophotometrically and by TLC that alantolactone was also reacted with thiols except cystine. The solution of alantolactone reached with thiol gave the UV absorption spectrum of $\alpha$-saturated ${\gamma}$-lactone, and most of SH groups were disappeared by the addition reaction. From the reaction mixture of alantolactone and cysteine, a lactone adduct was isolated and purified. Isoalantolactone had shown similar activity as alantolactone, however, it was appeared that di-, and tetrahydroalantolactones were not only inactive biologically but also in vitro. It was concluded that there was no correlationship between increased respiration rate and mortality of Chlorella. During the respiration TCA cycle was activated, however it was uncertain that the activation of EMP or HMP was also appeared. Alantolactone and isoalantolactone were biologically active compounds but others were inactive. The reactivity of $\alpha$-methylene ${\gamma}$-lactone moiety toward SH group was principally responsible for its biological activity in sesquiterpene lactones.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.3
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• pp.290-297
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• 2016

The absorbent loss due to degradation in $CO_2$ capture process using aqueous alkanol amine solution has adverse effect on the economics of overall process. The degradation causes absorbent loss, equipment corrosion, foaming, adhesive material producing and viscosity increase in operation. In this study, the degradation characteristics of $CO_2$ capture process using MEA (monoehtanolamine) under various conditions such as $O_2$ partial pressure, $CO_2$ loading and absorbent temperature. The effects of iron, which generated from the equipment corrosion, on absorbent degradation were studied using $Fe_2SO_4$ containing MEA solution. The produced gases were analyzed by FT-IR(Fourier Transform Infrared Spectrophotometer) and the specifically measured $NH_3$ concentration was used as a degradation degree of aqueous MEA solution. The experiments showed that the higher $CO_2$ loadings (${\alpha}$), $O_2$ fraction ($y_{O2}$) and reaction temperature enhanced the more degradation of aqueous MEA solution. Comparing other operation parameters, the reaction temperature most affected on the degradation. Therefore, it could be concluded that the above parameters affects on degradation should be considered for the selections of $CO_2$ absorbent and operating conditions.

• Journal of the Korean Ceramic Society
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• v.39 no.4
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• pp.367-376
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• 2002

Electrical conduction in $SrZr_{1-x}Y_xO_{3-\delta}$((x=0.05, 0.10)-metal electrode system was investigated by impedance spectroscopy and two-probe d.c. conductivity measurement. Electrode conductivity in anodic direction varies with $P_W^{1/2}$( and that in cathodic direction with $P_{O2}^{1/4}$ in oxidizing atmosphere. In hydrogen atmosphere, the addition of water vapor increased the electrode conductivity both in anodic and cathodic direction. Increasing dopant concentration from 5 to 10% showed a more than four times increase in anodic conduction as well as bulk conduction of the solid electrolyte. This observation implies that unfilled oxygen vacancy concentration increases rapidly as the dopant content increases in humid atmosphere. The activation energy of cathodic conduction in Pt and Ag electrode was nearly same below $800^{\circ}C$ which means the rate of cathodic reaction is determined by the reaction in the electrolyte surface rather than on the metal electrodes.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.368-372
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• 2011

Aluminum nitride (AlN) has excellent thermal conductivity, whereas it has some disadvantage such as low sinterability. In this study, the effects of sintering additive content and sintering condition on thermal conductivity of pressureless sintered AlN ceramics were examined on the variables of 1~3 wt% sintering additive ($Y_2O_3$) content at $1900^{\circ}C$ in $N_2$ atmosphere with holding time of 2~10 h. All AlN specimens showed higher thermal conductivity as the $Y_2O_3$ content and holding time increase. The formation of secondary phases (yttrium aluminates) by reaction of $Y_2O_3$ and $Al_2O_3$ from AlN surface promoted the thermal conductivity of AlN specimens, because the secondary phases could reduce the oxygen contents in AlN lattice. Also, thermal conductivity was increased by long sintering time because of the uniform distribution and the elimination of the secondary phases at the grain boundary by the evaporation effect during long holding time. A carbothermal reduction reaction was also affected on the thermal conductivity. The thermal conductivity of AlN specimens sintered at $1900^{\circ}C$ for 10 h showed 130~200W/mK according to the content of sintering additive.