• Journal of Plant Biotechnology
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• 제39권2호
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• pp.106-113
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• 2012

Glycolysis is responsible for the conversion of glucose into pyruvate and for supplying reducing power and several metabolites. Fructose-1,6-bisphosphate aldolase (AtFBA1), a central enzyme in the glycolysis pathway, was isolated by functional complementation of the salt-sensitive phenotype of a calcineurin (CaN)-deficient yeast mutant. Under high salinity conditions, aldolase activity and the concentration of NADH were compromised. However, expression of AtFBA1 maintained aldolase activity and the NADH level in yeast cells. AtFBA1 shares a high degree of sequence identity with known class I type aldolases, and its expression was negatively regulated by stress conditions including NaCl. The fusion protein GFP-AtFBA1 was localized in the cytosol of Arabidopsis protoplasts. The seed germination and root elongation of AtFBA1 knock-out plants exhibited sensitivity to ABA and salt stress. These results indicate that AtFBA1 expression and aldolase activity is important for stress tolerance in yeast and plants.

• BMB Reports
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• 제44권5호
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• pp.341-346
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• 2011

The single-stranded DNA binding activity of the Escherichia coli RecA protein is crucial for homologous recombination to occur. This and other biochemical activities of ssDNA binding proteins may be affected by various factors. In this study, we analyzed the effect of $CaCl_2$, NaCl and $NH_4NO_3$ salts in combination with the pH and nucleotide cofactor effect on the ssDNA-binding activity of RecA. The studies revealed that, in addition to the inhibitory effect, these salts exert also a stimulatory effect on RecA. These effects occur only under very strict conditions, and the presence or absence and the type of nucleotide cofactor play here a major role. It was observed that in contrast to ATP, ATP${\gamma}$S prevented the inhibitory effect of NaCl and $NH_4NO_3$, even at very high salt concentration. These results indicate that ATP${\gamma}$S most likely stabilizes the structure of RecA required for DNA binding, making it resistant to high salt concentrations.

• Journal of Pharmaceutical Investigation
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• 제39권3호
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• pp.167-171
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• 2009

Poly(lactic-co-glycolic acid) (PLGA) microspheres have been a useful tool as a controlled drug delivery system for peptides and proteins. Recently, porous microspheres have gained great attention as inhalation drug delivery system due to their low aerodynamic densities. Here, we report highly porous PLGA microspheres, which were prepared by using a single o/w emulsification/solvent evaporation method. Two types of porogen, i.e., (i) extractable Pluronic F127 and (ii) gas foaming salt of ammonium bicarbonate, were used to induce pores on the surface of PLGA microspheres. The respective preparation conditions on dp/cp ratio and porogen concentration were determined by the previous preliminary experiments, and other preparation factors were further optimized on the basis of PLGA Mw and porogen type. The morphological features examined by scanning electron microscope (SEM) show these porous microspheres have highly porous surface structure with a diameter range of 20${\sim}$30 ${\mu}$m. These highly porous PLGA microspheres, which have much lower density, would be a practical aerosol system for pulmonary drug delivery.

• 한국식품과학회지
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• 제20권5호
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• pp.711-717
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• 1988

배추의 염절임중 배추 조직으로의 소금흡수 속도를 측정하고 확산에 관한 수학적인 모델과 computer simulation을 통해서 확산계수를 구하였다. 배추 줄기로의 소금의 침투 및 탈염 될 때의 확산계수는 각각 $1.7{\times}10^{-11}m^2/s$와 $11.6{\times}10^{-11}m^2/s$이었다. Apparent diffusivity는 소금의 농도와 배추의 종류에 커다란 영향을 받지 않으며, 온도의존성은 Arrhenius식으로 나타낼 수 있고 이때의 활성화 에너지는 66 KJ/mol 이었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.668-671
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• 2007

A numerical study was conducted on a simplified model of a high-temperature solar receiver which incorporates liquid-metal heat pipe. The objective of this paper is to compare the isothermal characteristics of the heat pipe receiver with the conventional receiver utilizing convection of molten salt as heat carrier. The solar receiver was assumed to be subject to a concentration ratio between 50 and 1,000 to supply high-temperature heat to a stirling engine for electric power generation. For simplicity of the analysis, a cylindrical geometry was assumed and typical dimensions were used based on available literature. The heat pipe had a shape of double-walled cavity and the working fluid was a sodium. The analysis was performed assuming that the radiation heat flux on the inner walls of the receiver was uniform, since the focus of this study was laid on the comparison of the conventional type and heat pipe type receiver. The results showed that the heat pipe type exhibited superior performance when the operating temperature becomes higher. In addition, to explore the advantage of the heat pipe receiver, the channel shape and dimensions should be adjusted to increase the heat transfer area between the wall and the heat trnasfer medium.

• 대한기관식도과학회지
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• 제4권1호
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• pp.64-72
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• 1998

This study aimed at observing the effect of diazepam on the contractility of trachealis muscle isolated from canine trachea, possible involvement of central or peripheral type benzodiazepine receptor, and the calcium related mechanism of action of diazepam. Trachealis muscle strips of 15 mm long were suspended in an isolated organ bath containing 1 ml of physiologic salt solution maintained at $37^{\circ}C$, and aerated with 95% $O_2$ /5% $CO_2$. Isometric myography was performed. Diazepam reduced the basal tone concentration dependently, and this inhibitory action was not affected by neither flumazenil, a central benzodiazepine receptor antagonist, nor PK11195, a peripheral benzodiazepine receptor antagonist. Pretreatment with diazepam showed the inhibitory effect on the concentration-response curves to agonists such as bethanechol, 5-hydroxytryptamine and histamine. Diazepam also caused concentration-related inhibition of contraction with potassium chloride 30 mM. The effect of diazepam on the basal tone and potassium chloride-induced contraction with calcium channel blockers were compared. Similar results were obtained in canine trachealis with verapamil, nifedipine and diltiazem. These results suggest that diazepam relax an airway muscle not via specific receptors but by a similar action as calcium channel blockers in canine trachealis muscle.

• 소성∙가공
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• 제8권3호
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• pp.295-295
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• 1999

In the present study, the corrosion behavior of AZ91D as-cast alloy was investigated form the viewpoint of the distribution aspect of precipitate ($Mg_{17}Al_{12}$) and the variation of Al concentration in the Mg-rich matrix. The dendrite arm spacing (DAS) of an as-cast specimen was measured as a function of degree which describes the distribution aspect of the precipitate, and the salt spray test was conducted for various grain-sired specimens fur 20 days. The dendrite arm spacing increased as the grain size increased to about 150㎛, but a constant value is indicated when the grain size exceeds that range. Although the relationship between the corrosion rate and grain size is of a nonlinear type, the linear trend between the corrosion rate and the dendrite arm spacing is maintained for the overall range of dendrite arm spacing. Since the precipitate in the as-cast alloy is discontinuously distributed, this linear relationship means that the variation of Al-solute concentration in the Mg-rich matrix has a more potent effect than the protective action of the precipitate on the corrosion behavior of an as-cast alloy.

• 한국식품저장유통학회지
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• 제21권5호
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• pp.627-635
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• 2014

분쇄한 생마늘 10%와 식염을 6, 8, 10 및 12%로 달리하여 저염 마늘 된장을 제조하고, 상온에서 6주간 숙성시키면서 일주일 간격으로 시료를 취하여 숙성기간에 따른 품질 특성의 변화를 분석하였다. 숙성 시간이 경과할수록 명도는 감소하였으나, 적색도와 황색도는 유의적인 변화의 경향이 없었다. 염도는 된장 제조 직후에 비해 숙성 6주차에 1% 정도씩 증가하였으며, pH는 저장기간이 경과할수록 점차 감소하였으며, 산도는 이와 상반되게 증가되는 경향이었다. 환원당은 숙성기간의 경과와 더불어 유의적으로 증가하여 된장 제조 직후에 1.34~1.88 g/100 g이던 것이 숙성 6주차에는 7.25~9.13 g/100 g으로 변화하였는데, 식염의 첨가 농도가 낮을수록 환원당의 함량이 더 높았다. 아미노태 질소는 100~130 mg%에서 숙성 6주차에는 210~290 mg%로 약 2배 증가하였는데, 식염의 첨가 농도가 높을수록 아미노태질소의 함량은 더 낮았다. 된장의 발효 균주인 Bacillus 균주의 생육은 숙성 14일까지 증가되다가 그 이후부터는 감소되는 경향이었는데, 식염 10%와 12% 첨가군에서는 숙성 14일까지 Bacillus 균주의 생육이 양호하였다. 반면 효모는 된장의 숙성 초기에 급격히 감소하였으며, 숙성 21일 이후에는 일정범위를 유지하여 큰 변화는 없었다. 이상의 결과를 종합하여 볼 때 마늘이 첨가된 저염 된장은 염농도가 낮을수록 환원당이나 아미노태 질소의 함량이 더 높았고, 이화학적인 품질에도 크게 영향을 받지 않아 6% 정도의 식염첨가로 저염화가 가능할 것으로 확인되었다.

• 상하수도학회지
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• 제24권1호
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• pp.93-101
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• 2010

Reverse osmosis (RO) membranes have been widely used for desalination as well as water and wastewater treatment facilities. Cleaning process is important to maintain stable operation as well as prevention of membrane fouling. Purpose of this research is to analyze electrostatistic and chemical characteristics after cleaning of RO membrane against $SiO_2$ scale. Four RO membranes of polyamide are used and examined about effect of chemical cleaning. EDTA (ethylene diamine tetraacetic acid) and SDS (sodium dodecil sulfate) and NaOH are applied for cleaning process after operation in synthetic water. Then, cleaning was performed with chemicals such concentration as 6hr, 12hr and 24hr, respectively. As a result, transmittances of FT-IR of four membranes are compared at each cleaning concentration. Ta/Tv shows difference of chemical composition between new membrane and cleaning membrane after cleaning. Type B of RO membrane is turned out to be most vulnerable to cleaning among four membranes. In terms of zeta potential, new membrane has -16 mV to +6 mV on pH while scaled membrane has -18 mV to 2 mV. However, it changed -23mV to 0.9 mV after cleaning. In comparison with existing salt rejection of RO membranes after cleaning, the rejection of the membranes goes down 0.7% maximum. Though cleaning changes the characteristics of membrane surface, it does not greatly affect salt rejection. pH is a critical factor to flux change in PA (polyamide) membrane.

• 한국세라믹학회지
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• 제46권6호
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• pp.648-652
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• 2009

Ceramic fiber separator is the promising material for thermal battery system because it reduces the production cost and offers the potential to a new application compared to a pellet type electrolyte. The electrolyte separator for thermal battery should be easily handled and loaded a large amount of the molten lithium salt. Ceramic fibers were used as an electrolyte separator and the lithium based molten salts were infiltrated into the ceramic filters. Leakage of molten salt (several lithium salts) leads to short-circuit during the thermal battery operation. In this study, a uniform and fine SiOC mat with fibers ranging from 1 to 3 ${\mu}m$ was obtained by electrospinning of polycarbosilane and pyrolysis. The optimum spinning conditions for obtaining fine diameters of SiOC fiber were controlled by the solution composition and concentration, applied voltage and spinning rate, release rate by porosity. The pore structures of the ceramic filter and the melting properties of the lithium salts affected to the electrolyte loading and leakage. The importance of the fiber size and porosity and their control was discussed and the mechanical properties were also discussed.