• Korean Journal of Veterinary Research
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• v.24 no.2
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• pp.245-266
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• 1984

As a fundamental study to increase the reproductive efficiency in cattle, highly motile sperm were separated and collected from raw semen, extended semen and frozen semen by different methods using various concentrations of bovine serum albumin or Tyrode's solution. Various characteristics and light microscopic and electron-microscopic morphology of sperm separated by different methods were compared. The results obtained were as follows; 1. The sperm separated from raw semen using bovine serum albumin showed significantly high value in motility, motile sperm count, percent of normal sperm and progressive motility, as compared with control sperm and revealed the highest sperm recovery rate when separated with 6% bovine serum albumin. 2. The sperm motility, percent of normal sperm and progressive motility of the highly motile sperm frozen after being separated from raw semen with bovine serum albumin, showed significantly high value than those of a control sperm and especially found the highest value when separated with 20% bovine serum albumin. 3. Light-microscopic percent of abnormality was significantly low in the prefrozen and postfrozen highly motile sperm separated with bovine serum albumin, as compared with control sperm. 4. Electron-microscopic finding of the highly motile sperm separated with bovine serum albumin showed low percent of deformity in the dilatation and vesiculation of cell membrane, in dilatation and density loss of acrosome than in those of control sperm. 5. It was impossible to separate the highly motile sperm from frozen semen with bovine serum albumin, but it was possible with Tyrode's solution. 6. Recovery rate of highly motile sperm from raw semen extended semen and frozen semen was the highest when the sperm pellet stood in Tyrde's solution for 80 minutes. 7. The highly motile sperm separated from raw semen, extended semen and frozen semen with Tyrode's solution showed significantly high value in motility, progressive motility and percent of normal sperm, as compared with control sperm. 8. Highly motile sperm, when separated from raw semen, extended semen and frozen semen with Tyrode's solution, showed significantly low percent of microscopic abnormality as compared with control sperm.

• Membrane Journal
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• v.25 no.2
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• pp.162-170
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• 2015

In this study, gas permeability of polyimide materials having a various amine group was measured and molecular dynamics was used to analyze the dynamic characteristics of the gas molecules in the polyimide by calculating the position and velocity of the gas molecules with change of the time. The gas permeability of polyimide membrane having substitution site which increase free volume in the polymer was increased. However, polyimide with rigid structure showed decreased gas permeability. As a result of analyzing the change in the gas permeation behavior using molecular dynamics simulations, we confirmed that the results show the same tendency with actual measurements of the gas permeability.

• Membrane Journal
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• v.30 no.6
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• pp.450-459
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• 2020

Membrane-based separations have the potential to reduce energy consumption and environmental impact associated with conventional processes. However, many researches have been done to develop new membrane materials with greater selectivity and permeability. Here, we report highly selective membranes by introducing bulky ethyl substituents into the polyimide. The ethyl group in the ortho position to the imide nitrogen interferes the chain packing and increases chain stiffness and the distance between the polymer chains. The polyimide membranes were synthesized from various aromatic dianhydrides and 4,4'-methylenebis(2,6-diethylaniline) (MDEA). The synthesized membranes with increased gas diffusion length due to bulky substituents showed improved propylene/propane (C3H6/C3H8) selectivity. Single gas permeation showed high C3H6/C3H8 selectivity of 14.5, and C3H6 permeability of 7.0 barrer was found in MDEA-polyimide. Mixed-gas permeation results also demonstrate that MDEA-polyimide can achieve high selectivity in mixed-gas environment. Furthermore, this approach could significantly increase the feasibility of economic propylene separation compared to conventional polymer materials.

• Journal of IKEEE
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• v.22 no.4
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• pp.1062-1067
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• 2018

In this study, the research processed with a chemical sensor for measuring trace amount of heavy metal ions which is based on the requirements of the efficient sensing technology as recent equipment is applies molecular system in the chemical sensing section that can precisely recognizing selective target substance and transmit its data to physical signal as a result. In this research is concentrated on realize highly precise by utilizing SPR sensor application of recognition functional sensing membrane. Consequently, according to DTSQ-dye sensing membrane, the resonance angle from low-concentration to the highest concentration $10^{-4}M$ of $Ag^+$ ion is $2.17[^{\circ}]$ and this result indicating 4.3 times larger resonance angle changes compare to the other metal substance. Based on SQ-dye sensing membrane, the difference of resonance angle between low concentration and the highest concentration $10^{-4}M$ of $Cu^{2+}$ ion is $2.3[^{\circ}]$ and this outcome is indicating 4.5 times greater resonance angle change to the other metal substance.

• Analytical Science and Technology
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• v.5 no.1
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• pp.33-39
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• 1992

THF-based crown-4 of 16-membered rings having tetrahydrofuran unit was synthesized by an acid-catalyzed condensation of furan and acetone followed by hydrogenation in an effort to obtain highly elective ionophores for lithium ions. The new ionophore was compared with previously reported ionophores under similar measurement conditions with the same plasticizer, tris(2-ethylhexyl) phosphate in poly(vinyl chloride)(PVC) membrane electrodes. Separate solution method was used to determine relative selectivity coefficients for the electrode. The selectivity coefficients($K_{LiM}^{POT}$) of lithium over ammonium, alkali and alkaline earth metal ions go from about $2.4{\times}10^{-1}$ to $2.3{\times}10^{-4}$ to working range and pH dependence have also been studied.

• Animal cells and systems
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• v.7 no.1
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• pp.75-79
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• 2003

Highly purified high performance thin layer chromatography (HPTLC) fractions containing a putative calcium influx factor (CIF) were prepared from the Jurkat cells and Xenopus oocytes in which $Ca^{2+}$ stores were depleted by thapsigargin treatment and from the yeast in which intracellular $Ca^{2+}$ stores were also depleted by genetic means. Microinjection of the fractions has been shown to elicit $Ca^{2+}$ dependent currents in Xenopus oocytes. The nature of the membrane currents evoked by the putative CIF appeared to be carried by chloride ions since the current was blocked by the selective chloride channel blocker 1 mM niflumic acid and its reversal potential was about -24 mV. Injection of the calcium chelator 1,2-bis(2-aminophenoxy)ethane-N, N, N',N'-tetraacetic acid (BAPTA) eradicated the current activities, suggesting the current responses are entirely $Ca^2$-dependent. Moreover, the currents were sensitive to the removal of extracellular calcium, indicating the dependence on calcium entry through the plasma membrane calcium entry channels. CIF activities were insensitive to protease, heat, and acid treatments and to Dische-reaction whereas the activities were sensitive to nucleotide pyrophosphatase and hydrazynolysis. The fraction might have a sugar because it was sensitive to Molisch test and Seliwaniff's resorcinol reaction. From the above results, CIF as a small and stable molecule seems to have pyrimidine, pyrophosphate, and a sugar moiety.oiety.

• Membrane Journal
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• v.33 no.4
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• pp.191-200
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• 2023

Polyethersulfone (PES) is a widely employed membrane material for water and industrial purification applications owing to its hydrophilicity and ease of phase separation. However, PES membranes and filters prepared using the nonsolvent induced phase separation method often encounter significant flux decline due to pore clogging and cake layer formation on the dense membrane surfaces. Our investigation revealed that tight microfiltration or loose ultrafiltration membranes can be subject to physical fouling due to the formation of a dense skin layer on the bottom side caused by water intrusion to the gap between the shrank membrane and the substrate. To investigate the effect of the bottom surface porosity on membrane fouling, two membranes with the same selective layers but different sub-layer structures were prepared using single and double layer casting methods, respectively. The double layered PES membrane with highly porous bottom surface showed high flux and physical fouling tolerance compared to the pristine single layer membrane. This study highlights the importance of physical optimization of the membrane structure to prevent membrane fouling.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.9.2-9.2
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• 2011

Ultrathin polyelectrolyte (PE) multilayer films prepared by the versatile layer-by layer (LbL) assembly method have been utilized for the preparation of light-emitting diodes, electrochromic, membrane, and drug delivery system, as well as for selective area patterning and particle surface modification because the various materials with specific properties can be inserted into the film with nano-level thickness irrespective of the size or the shape of substrate. Since the introduction of the LbL technique in 1991 by Decher and Hong, various hydrophilic materials can be inserted within LbL films through complementary interactions (i.e., electrostatic, hydrogen-bonding or covalent interaction). In this study, it is demonstrated that LbL SA multilayer films based on nucleophilic substitution reaction can allow the preparation of the highly efficient magnetic and/or optical films and nonvolatile memory devices.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.2
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• pp.133-145
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• 1998

$Ca^{2+}-signals$ in endothelial cells are determined by release from intracellular stores and entry through the plasma membrane. In this review, the nature of $Ca^{2+}$ entry and mechanisms of its control are reviewed. The following ion channels play a pivotal role in regulation of the driving force for $Ca^{2+}$ entry: an inwardly rectifying $K^+$ channel, identified as Kir2.1, a big-conductance, $Ca^{2+}-activated$ $K^+$ channel (hslo) and at least two $Cl^-$ channels (a volume regulated $Cl^-$ channel, VRAC, and a $Ca^{2+}$ activated $Cl^-$ channel, CaCC). At least two different types of $Ca^{2+}$-entry channels exist: 1. A typical CRAC-like, highly selective $Ca^{2+}$ channel is described. Current density for this $Ca^{2+}$ entry is approximately 0.1pA/pF at 0 mV and thus 10 times smaller than in Jurkat or mast cells. 2. Another entry pathway for $Ca^{2+}$ entry is a more non-selective channel, which might be regulated by intracellular $Ca^{2+}$. Although detected in endothelial cells, the functional role of trp1,3,4 as possible channel proteins is unclear. Expression of trp3 in macrovascular endothelial cells from bovine pulmonary artery induced non-selective cation channels which are probably not store operated or failed to induce any current. Several features as well as a characterisation of $Ca^{2+}$-oscillations in endothelial cells is also presented.

• Membrane Journal
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• v.6 no.3
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• pp.173-181
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• 1996

Common volatile organic compounds(VOCs) such as toluene and methanol were removed successfully from N$_{2}$ using a novel silicone-coated hollow fiber membrane module. This novel membrane is a thin film composite(TFC) and was highly efficient in removing VOCs selectively from a N$_{2}$ stream. This membrane had some innate advantages over other silicone-based membrane in that the selective barrier was ultrathin(~1 $\mu$m) and the porosity of the polypropylene substrate was high which leads to a low permeation resistance. The substram was very strongly bonded to the coating layer by plasma polymerization and can withstand a very high pressure. A small hollow fiber module having a length of 25cm and 50 fibers could remove 96~99% of toluene as well as methanol vapors when the feed flow rate was up to 60cc/min. The percent removal of VOCs were even higher when the feed inlet concentration was higher. This process is especially suitable for treating streams having a low flow rate and high VOCs concentration. The permeances of VOCs through this membrane was in the range of $4~30 \times 10^{-9}gmol/sec \cdot cm^{2}\cdot cmHg$ for both toluene and methanol, and nitrogen permeance was between $3~9 \times 10^{-10}gmol/sec \cdot cm^{2} \cdot cmHg$. High separation factor between 10~55 for toluene/N$_{2}$ and 15~125 for methanol/N$_{2}$ were obtained depending on the feed flow rate ranges and feed VOCs concentration levels.