• Journal of Periodontal and Implant Science
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• 제34권3호
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• pp.551-562
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• 2004

골재생을 위한 술식은 자가골, 합성골 등의 이식술, 골견인술, 골유도 재생술 등이 있으며, 더 나은 결과를 위해서 성장 인자나 cytokine의 적용, 전기적 자극 등이 이용될 수 있다. 이 중 골재생을 위한 전기적 자극을 이용한 골재생 방법에서 비교적 양호한 결과가 보고되어지고 있으며, 전기적 자극은 크게 direct current, inductive coupling, capacitive coupling으로 나뉘어 사용, 연구되어지고 있다. 하지만, 위의 전기적 자극들은 비교적 침습적이고, 환자들에게 불편감을 줄 수 있으며, 부가적인 장치가 필요한 단점이 있다. 따라서, 본 실험에서는 골재생을 촉진하기 위한 비침습적인 전기자극의 방법으로, negatively charged membrane을 이용하여, 토끼 요골의 골절성 결손부에서 negative electric field가 골재생에 미치는 영향을 연구하고자 하였다. 8마리 토끼의 양 요골에 10mm의 골절성 결손부를 형성한 후, 코로나 방전 장치로 -l000V로 대전시킨 polytetrafluoroethylene membrane을 사용하여, 실험군에는 negatively charged membrane을, 대조군에는 noncharged membrane을 적용시킨 후, 2, 4, 6, 8주째 2마리씩 희생하여 조직학적, 조직형태학적 분석을 실시하였다. 2주째, 대조군에서 골결손부에 대한 신생골의 비율은 0.32%, 실험군에서는 1.10%로 나타났으며, 4주째 대조군에서 골결손부에 대한 신생골의 비율은 6.86%, 실험군에서는 13.75%로, 대조군에 비해 실험군에서 더 많은 양의 신생골이 관찰되었다. 6주와 8주째도 대조군에 비해 실험군에서 더 많은 신생골이 관찰되었으나, 그 차이는 크지 않았다. 결론적으로, 토끼 요골의 골절성 결손부의 골치유에서 negatively charged membrane을 이용한 전기적 자극은 초기 골치유를 촉진시키며, 따라서, 이러한 방법의 전기극은 장골의 치유에 있어 비침습적이며, 유용한 수단이라고 사료된다.

• The Korean Journal of Physiology and Pharmacology
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• 제2권4호
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• pp.529-539
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• 1998

The effects of membrane surface charge originated from lipid head groups on ion channels were tested by analyzing the activity of single large conductance $Ca^{2+}-activated\;K^+$ (maxi K) channel from rat skeletal muscle. The conductances and open-state probability ($P_o$) of single maxi K channels were compared in three types of planar lipid bilayers formed from a neutral phosphatidylethanolamine (PE) or two negatively-charged phospholipids, phosphatidylserine (PS) and phosphatidylinositol (PI). Under symmetrical KCl concentrations $(3{\sim}1,000\;mM)$, single channel conductances of maxi K channels in charged membranes were $1.1{\sim}1.7$ times larger than those in PE membranes, and the differences were more pronounced at the lower ionic strength. The average slope conductances at 100 mM KCl were $251{\pm}9.9$, $360{\pm}8.7$ and $356{\pm}12.4$ $(mean{\pm}SEM)$ pS in PE, PS and PI membranes respectively. The potentials at which $P_o$ was 1/2, appeared to have shifted left by 40 mV along voltage axis in the membranes formed with PS or PI. Such shift was consistently seen at pCa 5, 4.5, 4 and 3.5. Estimation of the effect of surface charge from these data indicated that maxi K channels sensed the surface potentials at a distance of $8{\sim}9\;{\AA}$ from the membrane surface. In addition, similar insulation distance ($7{\sim}9\;{\AA}$) of channel mouth from the bilayer surface charge was predicted by a 3-barrier-2-site model of energy profile for the permeation of $K^+$ ions. In conclusion, despite the differences in structure and fluidity of phospholipids in bilayers, the activities of maxi K channels in two charged membranes composed of PS or PI were strikingly similar and larger than those in bilayers of PE. These results suggest that the enhancement of conductance and $P_o$ of maxi channels is mostly due to negative charges in the phospholipid head groups.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.7-10
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• 2004

Reversed micelles (RMs) are nanometer-scale molecular assemblies in organic media. Their surface films (membranes) are composed of surfactant molecules normally holding two hydrocarbon hydrophobic chains. Di-2-ethylhexyl sulfosuccinate (AOT), which is a negatively charged molecule, is most popular surfactant utilized to form reversed micelles.(omitted)

• 한국물환경학회지
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• 제22권1호
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• pp.1-6
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• 2006

In this study, five commercially available fouling resistant low-pressure RO membranes were investigated for the treatment of seasonally brackish surface water with high organic content (${\approx}24mg/L$). The membranes investigated are LFC-1 (Hydranautics), X20 (Trisep), BW30FR1 (FilmTec), SG (Osmonics), and BE-FR (Saehan). The results of surface characterization revealed that each of these membranes has one or two unique surface characteristics to minimize the adherence of the fouling materials to the membrane. Specifically, the LFC1 membrane features a neutral or low negative surface to minimize electrostatic interactions with charged foulants. The X20, on the other hand, shows a highly negatively charged surface, and thus, is expected to perform well with feed waters containing negatively charged organics and colloids. The BW30FR1 exhibits a relatively neutral and hydrophilic surface, which could be beneficial for lessening organic and/or biofouling. The SG membrane has a smooth surface that makes it quite resistant to fouling, particularly for colloidal deposition. Lastly, BE-FR membrane demonstrated a medium surface charge and a slightly higher hydrophobicity. In the pilot study, all of the four membranes experienced a gradual increase in MTC (water mass transfer coefficient or specific flux) over time, indicating no fouling occurred during the pilot study. The deterioration of permeate water quality such as TDS was also observed over time, suggesting that the integrity of the membranes was compromised by the monochloramine used for biofouling control.

• 한국물환경학회지
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• 제29권4호
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• pp.559-567
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• 2013

In recent years, NF (nanofiltration) membrane has been receiving great attention for hardness removal and has begun to replace traditional lime soda ash softening process, particularly in Florida, USA, mainly due to less sludge production and easy operation. This study aimed to provide detailed surface characteristics of various commercial NF membranes by performing sophisticated surface analysis, which would help more fundamentally understand the performance of NF membranes. More specifically, a total of 7 NF membranes from top NF/RO manufacturers in the world were examined for basic performance tests, surface analysis, and fouling potential assessment. The results demonstrated that NF membranes are classified into two groups in terms of surface zeta potential; they are highly negatively charged ones, and neutral and/or less negatively charged ones. Their hydrophobicities, measured by contact angle, varied from hydrophilic to slightly hydrophobic ones. The AFM measurements showed various surface roughness, ranging from 23 nm (smooth) to 162 nm (rough) of average peak height. Lab-scale fouling experiments were performed using feedwater obtained from conventional water treatment plants in the province of Korea, and their results attempted to correlate to surface characteristics of NF membranes. However, unlike typical RO membranes, no clear correlation was found in this study, indicating that fouling mechanisms of NF membrane may be different from those of typical RO membranes, and both cake deposition and pore blocking mechanisms should be considered simultaneously.

• Korean Membrane Journal
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• 제2권1호
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• pp.56-59
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• 2000

The surface charge properties of a polymeric NF and a ceramic UF membranes were characterized in terms of zeta potential and acidity. Both the negative zeta potential and acidity values increased as pH increases due to ionizable acidic functional groups. Increased ionic strength reduced the acidity of the negatively-charged membrane surface as anticipated. Through these results, it can be envisioned are used to reject solutes with ionizable functional groups. Fouling of the negatively-charged membrane with natural organic matter (NOM) having a negative charge density was also investigated with respect to the surface charge. The surface charge of the NF membrane increased negatively when greater NOM adsorption onto the membrane surface occured.

• 멤브레인
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• 제15권1호
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• pp.34-43
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• 2005

Poly(vinyl alcohol) (PVA)이 폴리술폰 한외여과 막, 술폰화된 폴리에테르술폰, 폴리아미드 나노 막 위에 코팅된 나노 복합막을 가압법에 의해서 제조되었다. PVA는 글루터알데하이드 수용액으로 가교되었다. 모든 지지층위에 PVA 희박용액이 성공적으로 코팅되어 나노복합막이 제조되었다. 지지막 위의 친수화도가 높아짐에 따라 수투과 유량이 증가하였다. 특히 음하전을 띠는 폴리아미드 나노 복합막의 제타전위는 PVA로 코팅함으로서 감소되었다. 막 오염 실험은 양이온을 띠는 계면활성제, 휴민산, 휴민산과 칼슘이온 복합체 및 bovine serum albumin을 사용하여 실행하였다. PVA로 코팅되지 않은 폴리아미드 나노복합막은 각각의 오염물질에 의해서 심하게 오염되었다. 휴민산과 단백질에 의한 오염은 오염물질의 등전점에서 가장 심하게 발생하였다. 휴민산에 이가 양이온을 첨가함으로서 오염이 심각하게 일어났다. PVA 수용액으로 폴리아미드 나노 복합막을 코팅함으로서 막 오염이 감소되었다. PVA로 코팅된 폴리아미드 나노 복합막은 산, 염기용액에 대해 저항성을 보였다.

• 한국수산과학회지
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• 제46권1호
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• pp.46-52
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• 2013

After an outbreak of viral disease in an aquafarm, release of virus (es) from infected fish into environmental seawater has been suspected. In the present study, we utilized a negatively charged membrane (HA type) as an efficient method for concentration and detection of fish pathogenic viruses, specifically, megalocytivirus and viral hemorrhagic septicemia virus (VHSV) present in field-collected seawater samples or inoculated into seawater artificially. Positively charged viruses adsorbed onto the negatively charged membrane and were eluted with 1 mM NaOH (pH 10.5) following rinsing with 0.5 mM $H_2SO_4$ (pH 3.0). Megalocytivirus and VHSV particles isolated using anegatively charged HA membrane from seawater inoculated with each virus at a concentration of 10 viral particles/mL were of sufficient quantity to show positive results in atwo-step PCR (or RT two-step PCR); however, despite it being negatively charged, a cellulose acetate (CA) membraneshowed negative results. In quantitative PCR, the detection limits of the HA membrane for megalocytivirus and VHSV in seawater were 1.20E+00 viral particles/mL and 1.22E+01 viralparticles/mL, respectively. The calculated mean recovery yields from 1 L seawater spiked with known concentrations of megalocytivirus and VHSV particles were 28.11% and 23.00%, respectively. The concentrate of a 1-L sample of culturing seawater from the aquatank of flounder suffering from VHSV showed clear positive results in PCR when isolated with an HA, but not a CA, membrane. Thus, viral isolation using an HA membrane is a practical and reliable method for detection of fish pathogenic viruses in seawater.

• Membrane and Water Treatment
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• 제4권3호
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• pp.157-174
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• 2013

The present study is devoted to the validation of a new method for in line electrokinetic characterisation of deposits on membrane surfaces. This method is based upon simultaneous measurements of transversal streaming potential and permeates flux at constant pressure before and during the deposit formation. Dead-end filtration experiments were conducted with negative flat membranes forming a narrow slit channel, negative hollow fiber membranes and mono-dispersed suspensions of (negatively charged) polystyrene latex and (positively charged) melamine particles at various concentrations. It was observed that the overall streaming potential coefficient increased in absolute value with the deposited latex quantity, whereas it decreased and changed of sign during the filtration of melamine suspensions. By considering a resistance-in-series model, the streaming potential coefficient of the single deposit ($SP_d$) was deduced from the electrokinetic and hydraulic measurements. The independence of $SP_d$ with respect to growth kinetics validates the measurement method and the reliability of the proposed procedure for calculating $SP_d$. It was found that $SP_d$ levelled off much more quickly when filtration was performed through the slit channel. This different behaviour could result from a non-uniform distribution of the deposit thickness along the membrane given that the position of measuring electrodes is different between the two cells.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.880-888
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• 2006

Pleurocidin, an $\alpha$-helical cationic antimicrobial peptide, was isolated from skin mucosa of winter flounder (Pleuronectes americamus). It had strong antimicrobial activities against Gram-positive and Gram-negative bacteria, but had very weak hemolytic activity. The Gly$^{13,17}\rightarrow$Ala analog (pleurocidin-AA) showed similar antibacterial activities, but had dramatically increased hemolytic activity. The bacterial cell selectivity of pleurocidin was confirmed through the membrane-disrupting and membrane-binding affinities using dye leakage, tryptophan fluorescence blue shift, and tryptophan quenching experiments. However, the non-cell-selective antimicrobial peptide, pleurocidin-AA, interacts strongly with both negatively charged and zwitterionic phospholipid membranes, the latter of which are the major constituents of the outer leaflet of erythrocytes. Circular dihroism spectra showed that pleurocidin-AA has much higher contents of $\alpha$-helical conformation than pleurocidin. The tertiary structure determined by NMR spectroscopy showed that pleurocidin has a flexible. structure between the long helix from $Gly^3$ to $Gly^{17}$ and the short helix from $Gly^{17}$ to $Leu^{25}$. Cell-selective antimicrobial peptide pleurocidin interacts strongly with negatively charged phospholipid membranes, which mimic bacterial membranes. Structural flexibility between the two helices may play a key role in bacterial cell selectivity of pleurocidin.