• 한국전산유체공학회지
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• 제21권1호
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• pp.103-109
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• 2016

With the rapid increase in the number of patients with cardiopulmonary diseases, more cardiopulmonary circulatory assist devices are also needed. These devices can be employed when heart and/or lung function poorly. Due to the critical role they take, these devices have to be designed optimally from both mechanical and biomechanical aspects. This paper presents the CFD results of a baseline model of a centrifugal blood pump for the ECMO condition. The details of flow characteristics of the baseline model together with the performance curves and the modified index of hemolysis(MIH) are investigated. Then, the geometry of baseline impeller and the volute are modified in order to improve the biomechanical performance and reduce the MIH value. The numerical simulations of two cases represent that when impeller radius and prime volume decrease the MIH value also decreases. In addition, the modified geometry shows more uniform pressure distribution inside the volute. The findings provide valuable information for further modification and improvement of centrifugal blood pumps from both mechanical and biomechanical aspects.

• 한국발생생물학회지:발생과생식
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• 제18권3호
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• pp.153-160
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• 2014

Adaptive development of early stage embryo is well established and recently it is explored that the mammalian embryos also have adaptive ability to the stressful environment. However, the mechanisms are largely unknown. In this study, to evaluate the possible role of aquaporin in early embryo developmental adaptation, the expression of aquaporin (AQP) 5 gene which is detected during early development were examined by the environmental condition. To compare expression patterns between in vivo and in vitro, we conducted quantitative RT-PCR and analyzed localization of the AQP5 by whole mount immunofluorescence. At in vivo condition, Aqp5 expressed in oocyte and in all the stages of preimplantation embryo. It showed peak at 2-cell stage and decreased continuously until morula stage. At in vitro condition, Aqp5 expression pattern was similar with in vivo embryos. It expressed both at embryonic genome activation phase and second mid-preimplantation gene activation phase, but the fold changes were modified between in vivo embryos and in vitro embryos. During in vivo development, AQP5 was mainly localized in apical membrane of blastomeres of 4-cell and 8-cell stage embryos, and then it was localized in cytoplasm. However, the main localization area of AQP5 was dramatically shifted after 8-cell stage from cytoplasm to nucleus by in vitro development. Those results explore the modification of Aqp5 expression levels and location of its final products by in vitro culture. It suggests that expression of Aqp5 and the roles of AQP5 in homeostasis can be modulated by in vitro culture, and that early stage embryos can develop successfully by themselves adapting to their condition through modulation of the specific gene expression and localization.

• Membrane and Water Treatment
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• 제11권1호
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• pp.1-10
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• 2020

An understanding of particle-particle interactions in filtration requires studying the detachment as well as the attachment of nanoparticles. Nanoparticles captured in a granular media filter can be released by changing the physicochemical factors. In this study, the detachment of captured silver nanoparticles (AgNPs) in granular media filtration was examined under different ionic strengths, ion type, and the presence or absence of natural organic matter (NOM). Filtration velocity and ionic strength were chosen as the physical and chemical factors to cause the detachment. Increasing filtration velocity caused a negligible amount of AgNP detachment. On the other hand, lowering ionic strength showed different release amounts depending on the background ions, implying a population of loosely captured particles inside the filter bed. Overall detachment was affected by ionic strength and ion type, and to a lesser degree by NOM coating which resulted in slightly more detachment (in otherwise identical conditions) than in the absence of that coating, possibly by steric effects. The secondary energy minimum with Na ions was deeper and wider than with Ca ions, probably due to the lack of complexation with citrate and charge neutralization that would be caused by Ca ions. This result implies that the change in chemical force by reducing ionic strength of Na ions could significantly enhance the detachment compared to that caused by a change in physical force, due to a weak electrostatic deposition between nanoparticles and filter media. A modification of the 1-D filtration model to incorporate a detachment term showed good agreement with experimental data; estimating the detachment coefficients for that model suggested that the detachment rate could be similar regardless of the amount of previously captured AgNPs.

• 한국물환경학회지
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• 제36권4호
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• pp.275-283
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• 2020

Fecal coliforms are indicator bacteria to evaluate fecal contamination and microbiological safety in environment water. To examine fecal coliforms by membrane filtration, 1% rosolic acid solution dissolved in sodium hydroxide(0.2 M) should be added to m-FC medium according to Korean standard method. To reduce the exposure of researchers to harmful chemicals and expenditure of unnecessary cost, we evaluated if the rosolic acid solution is required to detect fecal coliforms. For 113 samples collected from five intake sources of Seoul, 42 samples of six tributaries, and 11 samples of sewage, the number of fecal coliforms was compared in medium with or without the reagent. As a result, the number was higher in m-FC medium without the reagent, but there was not a statistically significant difference. In the water intake, m-FC medium without the reagent could be used to examine fecal coliforms except in July, August and in case of rainfall. When heterotrophic plate counts exceeded 1,000 CFU/filter, or during rainfall, there was an effect of background bacteria in two types of the medium. However, it was more appropriate to use m-FC medium with the reagent to suppress gram-positive bacteria that can grow on medium without the reagent. In the tributary and sewage samples, the effect of the background bacteria was low, allowing the use of medium without the reagent regardless rainfall. Thus, it is necessary to present in standard method that the addition of rosolic acid solution in m-FC medium can be selected according to the characteristics of samples.

• The Korean Journal of Physiology and Pharmacology
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• 제7권1호
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• pp.15-23
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• 2003

Cellular redox state is known to be perturbed during ischemia and that $Ca^{2+}$ and $K^2$ channels have been shown to have functional thiol groups. In this study, the properties of thiol redox modulation of the ATP-sensitive $K^2$ ($K_{ATP}$) channel were examined in rabbit ventricular myocytes. Rabbit ventricular myocytes were isolated using a Langendorff column for coronary perfusion and collagenase. Single-channel currents were measured in excised membrane patch configuration of patch-clamp technique. The thiol oxidizing agent 5,5'-dithio-bis-(2-nitro-benzoic acid) (DTNB) inhibited the channel activity, and the inhibitory effect of DTNB was reversed by dithiothreitol (disulfide reducing agent; DTT). DTT itself did not have any effect on the channel activity. However, in the patches excised from the metabolically compromised cells, DTT increased the channel activity. DTT had no effect on the inhibitory action by ATP, showing that thiol oxidation was not involved in the blocking mechanism of ATP. There were no statistical difference in the single channel conductance for the oxidized and reduced states of the channel. Analysis of the open and closed time distributions showed that DTNB had no effect on open and closed time distributions shorter than 4 ms. On the other hand, DTNB decreased the life time of bursts and increased the interburst interval. N-ethylmaleimide (NEM), a substance that reacts with thiol groups of cystein residues in proteins, induced irreversible closure of the channel. The thiol oxidizing agents (DTNB, NEM) inhibited of the $K_{ATP}$ channel only, when added to the cytoplasmic side. The results suggested that metabolism-induced changes in the thiol redox can also modulate $K_{ATP}$ channel activity and that a modulatory site of thiol redox may be located on the cytoplasmic side of the $K_{ATP}$ channel in rabbit ventricular myocytes.

• 폴리머
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• 제38권3호
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• pp.293-298
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• 2014

본 연구에서는 방사선을 이용하여 다공성 polytetrafluoroethylene(PTFE) 지지체에 acrylonitrile(AN)과 친수성 작용기를 가진 sodium allylsulfonate(SAS)를 접목시켜 복합 연료전지막의 지지체로 사용되는 친수화 다공성 지지체를 제조하였다. SAS/AN의 몰비율, 단량체 농도, 방사선의 조사선량에 변화를 주어 제조된 지지체의 물성을 평가하였다. 제조된 지지체의 FTIR 분석을 통하여 각 단량체들이 다공성 PTFE 지지체에 성공적으로 그래프팅되었음을 확인하였다. 또한 FE-SEM과 gurley number 측정을 이용하여 그래프트율이 증가할수록 지지체 표면의 기공이 감소하는 것을 관찰하였고, 그래프트율, 접촉각, TBO(toluidine blue O) uptake 분석을 통해 그래프트율이 증가됨에 따라 제조된 지지체의 친수화도가 증가하는 것을 확인하였다.

• 대한의생명과학회지
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• 제15권1호
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• pp.37-45
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• 2009

Insect cell cultures have become important tools in the production of biological substances for use in a variety of research, human and veterinary medicine, and pest control applications. These applications often require the introduction of foreign DNA into the cells and have generally used methods originally developed for use with human and other mammalian cell cultures. While these methods can be successfully employed, they are often less efficient with insect cells and frequently involve complex procedures or require specialized equipment. Even when they do work, they may require substantial modification because of differences in the culture medium or growth patterns of insect cells. In this study, We have optimized transfection conditions of Sf9 cell line using insect expression vector pIZT/V5-His which expresses green fluorescent protein effectively. Human stem cell factor (hSCF) is a glycoprotein that plays a key role in hematopoiesis acting both as a positive and negative regulator, often in synergy with other cytokines. It also plays a key role in mast cell development, gametogenesis, and melanogenesis. It can exist in membrane-bound form and in proteolytically released soluble form. As determined by an enzyme-linked immunosorbent assay performed, hSCF level in supernatant averaged 995ng/ml. The human hSCF was partially purified by immunoaffinity chromatography and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The results show that the hSCF has N-linked carbohydrate and corresponds to the soluble form, at or about 223 amino acids in length. The findings suggest functional importance for soluble hSCF in cells.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.929-935
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• 2007

The objective of this study was to develop a rapid, simple, and qualitative acetylcholinesterase (AChE)- detection kit, based on a modification of the Ellman and ELISA methods, for the detection of organophosphorus (OP) and carbamate (CB) pesticide. The developed kits were used to screen a large number of agricultural samples (spiked and real) for OP and CB pesticide residues. AChE was extracted from the heads of honeybees (Apis mellifera L.) using Triton X-100, and was purified through 3 steps: diethylaminoethylcellulose chromatography (DEAE), affinity chromatography and membrane filtering, and Mono-Q column chromatography. Epoxy-activated Sepharose 6B affinity chromatography was used for large-scale purification. The presence of OP and CB pesticide residues in agricultural samples was assayed on the basis of AchE inhibition value. The presence (6 bands) or absence of some colored bands on the test line indicated a negative or positive result, respectively. The limits of detection for measured organophosphorus (OP) and carbamates (CB) pesticide residues in standard pesticide solutions and fortified samples were ranged from 0.50 to 2.50 ppm and 0.50 to 4.75 ppm, respectively.

• 약학회지
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• 제30권1호
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• pp.31-41
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• 1986

Sarcolemmal membrane fraction from canine ventricle was isolated from the discarded pellet after the first homogenization in the isolation procedure of sarcoplasmic reticulum (Method 1) and the protein yield, purity, and sidedness of this preparation were compared to those of sarcolemmal fraction prepared by method of Lee et al. (Method 2) and a slight modification of original protocol of Jones et al. (Method 3). Method 1 differed from Method 2 essentially only in that vigorous homogenization was carried out by omnimixer and homogenization medium containing 30mM Tris-maleate was used in the first step. The sarcolemmal fraction was enriched from 45 to 50 and 29-fold in [$^3H$] ouabain, [$^3H$] DHA, [$^3H$] QNB binding and $Na^+$, $K^+$-ATPase activity, respectively, compared to homogenate. Total $Na^+$, $K^+$-ATPase activity of highly sarcolemma enriched fraction was 144.6$\pm$16.4$\mu\textrm{mol}$ Pi/mg protein/hr, which was about 85%, of total ATPase activity, and the yield of the preparation was 15.7 mg protein per 100g of starting ventricular tissue. The sarcolemmal preparation supported $^{45}Ca^{2+}$-uptake in the presence of ATP but this uptake was not dependent on oxalate. Sarcolemmal $Na^+$, $K^+$-ATPase activity and detectable [$^3H$] ouabain binding were increased about 32% and 35%, respectively, by pretreatment of sarcolemmal fraction with optimal concentration of sodium dodecylsulfate (0.3-0.4mg/mg protein), suggesting that this preparation contained about 24% of sealed rightside-out vesicles, 26% of sealed inside-out vesicles, and 5001o of freely permeable (leaky) form. This procedure showed the highest protein yield and leaky population, compared to Method 2 and 3. On the other hand, sarcolemmal fraction prepared by Method 2 and 3 showed low value in protein yield but comtained high population of inside-out (46%) and rightside-out (49%) vesicles, respectively, compared to present procedure (Method 1). The results indicate that vigorous homogenization decreases the population of sealed sarcolemmal vesicles but increases the sarcolemmal protein yield per gram tissue and that this procedure is available for further purification of sarcolemmal fraction and for the receptor binding study of sarcolemma.

• 한국표면공학회지
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• 제49권3호
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• pp.286-300
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• 2016

Pd-Ag alloy membranes have attracted a great deal of attention for their use in hydrogen purification and separation due to their high theoretical permeability, infinite selectivity and chemical compatibility with hydro-carbon containing gas streams. For commercial application, Pd-based membranes for hydrogen purification and separation need not only a high perm-selectivity but also a stable long-term durability. However, it has been difficult to fabricate thin, dense Pd-Ag alloy membranes on a porous stainless steel metal support with surface pores free and a stable diffusion barrier for preventing metallic diffusion from the porous stainless steel support. In this study, thin Pd-Ag alloy membranes were prepared by advanced Pd/Ag/Pd/Ag/Pd multi-layer sputter deposition on the modified porous stainless steel support using rough polishing/$ZrO_2$ powder filling and micro-polishing surface treatment, and following Ag up-filling heat treatment. Because the modified Pd-Ag alloy membranes using rough polishing/$ZrO_2$ powder filling method demonstrate high hydrogen permeability as well as diffusion barrier efficiency, it leads to the performance improvement in hydrogen perm-selectivity. Our membranes, therefore, are expected to be applicable to industrial fields for hydrogen purification and separation owing to enhanced functionality, durability and metal support/Pd alloy film integration.