• Membrane Journal
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• v.24 no.3
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• pp.240-248
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• 2014

Porous PVDF hollow fiber membranes were prepared by hybrid process of TIPS(thermally induced phase separation) and stretching for membrane distillation. The tests were conducted to investigate that permeability of the membrane could be enhanced by reducing membrane wall thickness. During fiber spinning, dope discharge rate from nozzle was reduced and flow rate of bore fluid increased to make the wall thickness thinner. As dope discharge rate from nozzle was reduced and flow rate of bore fluid increased, the membrane wall thickness was reduced. As a result, air permeability, water permeability and vapor permeability of the membranes increased.

• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.37-45
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• 2022

The fungal cell wall and membrane are the principal targets of antifungals. Herein, we report that myricetin exerts antifungal activity against Candida albicans by damaging the cell wall integrity and notably enhancing the membrane permeability. In the presence of sorbitol, an osmotic protectant, the minimum inhibitory concentration (MIC) of myricetin against C. albicans increased from 20 to 40 and 80 ㎍/ml in 24 and 72 h, respectively, demonstrating that myricetin disturbs the cell wall integrity of C. albicans. Fluorescence microscopic images showed the presence of propidium iodide-stained C. albicans cells, indicating the myricetin-induced initial damage of the cell membrane. The effects of myricetin on the membrane permeability of C. albicans cells were assessed using crystal violet-uptake and intracellular material-leakage assays. The percentage uptakes of crystal violet for myricetin-treated C. albicans cells at 1×, 2×, and 4× the MIC of myricetin were 36.5, 60.6, and 79.4%, respectively, while those for DMSO-treated C. albicans cells were 28.2, 28.9, and 29.7%, respectively. Additionally, myricetin-treated C. albicans cells showed notable DNA and protein leakage, compared with the DMSO-treated controls. Furthermore, treatment of C. albicans cells with 1× the MIC of myricetin showed a 17.2 and 28.0% reduction in the binding of the lipophilic probes diphenylhexatriene and Nile red, respectively, indicating that myricetin alters the lipid components or order in the C. albicans cell membrane, leading to increased membrane permeability. Therefore, these data will provide insights into the pharmacological worth of myricetin as a prospective antifungal for treating C. albicans infections.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.3
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• pp.77-85
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• 2020

In this study, we proposed a method to replace the solid finite element model of the boiler membrane wall for coal-fired power plants using an equivalent shell model. The application of a bending load to the membrane wall creates greater displacement at both ends of the central portion when compared with the middle when an isotropic elastic constant is used in the shell model. This is inconsistent with the results of the solid model where the central portion is uniformly deformed. Here, we presented a method to determine the orthotropic elastic constants of the shell model in terms of bending stiffness and vibration characteristics to solve this problem. Our analysis of the orthotropic shell model showed that the error ratio was 0.9% for the maximum displacement due to the bending load, 0.3% for the first natural frequency, and 2.5% for the second natural frequency when compared with the solid model. In conclusion, a complicated boiler membrane wall composed of a large number of pipes and fins can be replaced with a simple shell model that shows equivalent bending stiffness and vibration characteristics using our proposed method.

• Microbiology and Biotechnology Letters
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• v.1 no.1
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• pp.19-23
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• 1973

This experiment was done to investigate the growth and the fine structural changes of Bacillus subtilis which were influenced by the penicillin with electromicroscope. The results were as follows; 1) The higher the concentration of penicillin the more prominent inhibition of the growth was observed. 2) The septa was not formed, derangements of synthesis of cell wall and cell membrane. 3) Cytoplasm was increased with swelling of cell body because of weakness of cell membrane induced by deranged synthesis of cell membrane. Some of the cells showed disruption of their membrane with loss of cytoplasm, remaining empty space, which suggest loss of cell function. 4) It can be suggested that penicillin had affected on the cell wall of Bacillus subtilis, and inhibited growth of the cell by deranging the formation of the cell wall.

• The Journal of the Korean Society for Microbiology
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• v.5 no.1
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• pp.9-18
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• 1970

The present study is of ultra-fine structures of Trichophyton rubrum, Trichophyton mentagrophytes, Microsporum canis and Epidermophyton floccosum by means of electron microscopy and reveals the following. 1. In contrast to the bacteria, the normal fungus contains nuclear membrane, mitochondria, endoplasmic reticulun, distinct cell wall and cell membrane and secretory granules as observed in the higher plants and animals. 2. Thickening of the cell wall, inapparent cell wall, inapparent cell membrane with the appearance of electron thin area(ETA) and increase of inclusions were observed in the L-1 treated groups. 3. Thickening of cell wall and increase of ETA were more apparent in the Epidermophyton floccosum than the other groups. 4. Increase of electron thin area was thought to be associated with autolysis.

• Journal of Microbiology
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• v.33 no.3
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• pp.228-233
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• 1995

As S. epidermidis cell was fractionated into cell wall, cell membrane, and cytoplasm, the cell membrane proved to be the most efficient absorbent for lead ion. Utrasonication was effective, when the cells were treated during their exponential growth. The amount of the lead ion adsorbed in cell membrane decreased as hydrogen ion concentration of solution increased. Protein purified from the cell membrane showed higher adsorption capacity for the lead ion than peptidoglycan, teichoic acid from cell wall, or cell membrane lipid. Modification of carboxyl groups in the membrane protein with ethylenediamine and 1-ethyl-3-carbodiimide hydrochloride resulted in a considerable decrease of lead ion adsorption capability, suggesting that the main binding site for lead ion was the carboxyl groups of protein in cell membrane.

• Membrane and Water Treatment
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• v.13 no.6
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• pp.313-320
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• 2022

Theoretical calculation results are presented for the enhancement of the water mass flow rate through the hydrophobic micro/nano pores in the membrane respectively on the micrometer and nanometer scales. The water-pore wall interfacial slippage is considered. When the pore diameter is critically low (less than 1.82nm), the water flow in the nanopore is non-continuum and described by the nanoscale flow equation; Otherwise, the water flow is essentially multiscale consisting of both the adsorbed boundary layer flow and the intermediate continuum water flow, and it is described by the multiscale flow equation. For no wall slippage, the calculated water flow rate through the pore is very close to the classical hydrodynamic theory calculation if the pore diameter (d) is larger than 1.0nm, however it is considerably smaller than the conventional calculation if d is less than 1.0nm because of the non-continuum effect of the water film. When the driving power loss on the pore is larger than the critical value, the wall slippage occurs, and it results in the different scales of the enhancement of the water flow rate through the pore which are strongly dependent on both the pore diameter and the driving power loss on the pore. Both the pressure drop and the critical power loss on the pore for starting the wall slippage are also strongly dependent on the pore diameter.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.31-35
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• 1995

Using the alkalophillic Bacillus sp. SH-8 and its mutant Bacillus sp. SH-8M capable of growing at the neutral pH, the amino acid compositions of the cell wall and cell membrane were studied at varying cultivation pH's. The pattem of protein electrophoresis was also tested. It was elucidated that the amino acids consisting of the cell wall were alanine, glutamic acid, lysine, aspartic acid, and meso-diaminopimelic acid. There was not any significant difference in the amino acid compositqon betweeo`two straqns regardless of the culture pH. As the results of HPLC ssay, glutamic acid and aspartic aciu accounted for more than 50% in the amqno acid composytqon of the cell wall. By the isolatqon of the crude cell membrane and the SDS-PAGE analysis, it was found that there was a considerable difference qn the protein pattern when the straqns were cultured at the neutral pH. In addition, by the two dimensional gel electrophoresis, it was confirmed that there was a difference in the protein patterns between two strains cultivated at the neutral pH medium but no difference at the alkaline medium.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.5-9
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• 1995

In the dry-jet-wet-spinning process of a hollow fiber membrane, the polymer solution is pumped into a coaxial tube, jet spinneret. The threadline emerging from the spinneret is stabilized by an internal coagulating medium(liquid or gas) as it emerges from the jet orifice. The nascent hollow thread is further stabilized in a quench bath as shown in Fig. 1. In this scheme, three mechanism of formatiota(temperature gradient, solvent evaporation, and solvent-nonsotvent exchange) can be combined. The changes which promote stabilization often play a dominant role in determining the ultimate fiber wall structure as well. Hence, in pratice, hollow fiber stabilization and development of membrane structure are commonly inseparable. However, fiber dimension(the inside diameter and wall thickness of the hollow fiber) is mainly a rheological problem and is determined by dope pumping rate, spinneret diatance from the coagulation bath, inner coagulant flow rate, and fiber draw-rate. Besides rheological phenomena play a prominent part in the final properties of the hollow fiber.

• Journal of Microbiology
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• v.33 no.4
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• pp.278-282
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• 1995

S. epidermidis cell was fractionated into cell wall, cell membrane and cytoplasm. The cell membrane adsorbed the most abundant $\textrm{Pb}_{2+}$ per unit dry weight of the three fractions tested. Adsorption behavior of $\textrm{Pb}_{2+}$ in lipid and protein, which are the main components of the cell membrane, indicated that phosphatidylethanolamine and phosphatidylinositol having phosphoryl group and gangliosides containing carboxyl groups adsorbed much more $\textrm{Pb}_{2+}$ than triglycerides lacking any chargeable functional groups. Protein purified from cell membrane adsorbed larger amount of $\textrm{Pb}_{2+}$ than total native cell membrane or cell membrane lipid.