Nanostructured PVDF membrane for MD application by an O₂ and CF₄ plasma treatment

Jeong, Seongpil,Shin, Bongsu,Jo, Wonjin,Kim, Ho-Young,Moon, Myoung-Woon,Lee, Seockheon Elsevier 2016 Desalination Vol.399 No.-

<P><B>Abstract</B></P> <P>Recently, various nanotechnologies have been utilized with regard to membrane modification due to their high activities and the low cost of the nanomaterials involved. In order to enhance the hydrophobicity of the membrane surface for membrane distillation applications by decreasing the surface energy, a radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) process is suggested with surface nanostructuring and a subsequent hydrophobic coating step. In this research, a commercial PVDF membrane was modified by plasma treatments with the two different gases of O<SUB>2</SUB> and CF<SUB>4</SUB>. The water contact angles of the active layers increased from 73 to 117 and 101° and the fluxes of the treated membranes increased to 63 and 27.9% as compared to a virgin PVDF membrane when the feed used was D.I. water by the O<SUB>2</SUB> and CF<SUB>4</SUB> plasma modifications, respectively. Defluorination at the long exposure time (120min) of the plasma treatment and increase of the overall hydrophobicity (the decrease of the contact angle hysteresis) by the HMDSO coating were the reasons of the flux variations for the plasma modified membranes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The PVDF membranes were modified by plasma treatments with O<SUB>2</SUB> and CF<SUB>4</SUB> gases. </LI> <LI> The modified membrane have an enhanced flux and hydrophobicity after the plasma treatment. </LI> <LI> The pore-size and porosity at the membrane surface increased after the plasma treatment. </LI> <LI> The hairy structure was formed at the membrane surface by the HMDSO coating. </LI> <LI> The O<SUB>2</SUB> plasma treatment with HMDSO coating increased the receding contact angle. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

CF₄ plasma-modified omniphobic electrospun nanofiber membrane for produced water brine treatment by membrane distillation

Chul Woo, Yun,Chen, Ying,Tijing, Leonard D.,Phuntsho, Sherub,He, Tao,Choi, June-Seok,Kim, Seung-Hyun,Kyong Shon, Ho Elsevier 2017 Journal of membrane science Vol.529 No.-

<P><B>Abstract</B></P> <P>This study describes the development and performance of an omniphobic poly(vinylidene fluoride) (PVDF) membrane by electrospinning and CF<SUB>4</SUB> plasma surface modification for air gap membrane distillation (AGMD). The effect of different duration of plasma treatment on the nanofiber membrane characteristics was investigated. The AGMD performance of the membranes was evaluated using real reverse osmosis (RO) brine produced from coal seam gas (CSG) water that was added with low surface tension liquid (surfactant) as feed solution. Results indicated the formation of new CF<SUB>2</SUB>-CF<SUB>2</SUB> and CF<SUB>3</SUB> bonds after plasma treatment, which lowered the surface energy of the membrane, providing omniphobic property, as indicated by its wetting resistance to different low surface tension liquids such as methanol, mineral oil and ethylene glycol. Though no appreciative changes in morphology of the membrane were observed after plasma treatment, optimal treatment condition of 15min (i.e., P/CF-15 membrane) exhibited lotus effect membrane surface with increased liquid entry pressure of 187 kPa compared to 142 kPa for neat membrane. AGMD performance showed stable normalized flux (initial flux of 15.3L/m<SUP>2</SUP>h) and rejection ratio (100%) for P/CF-15 even with the addition of up to 0.7mM sodium dodecyl sulfate surfactant to the RO brine from CSG produced water feed, while commercial PVDF membrane suffered membrane wetting after 0.3mM of surfactant addition. Based on the results, the present omniphobic membrane has good potential for producing clean water from challenging waters containing high salinity and organic contaminants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PVDF electrospun nanofiber membranes are modified by CF<SUB>4</SUB> plasma treatment. </LI> <LI> Omniphobic nanofiber membrane was obtained after CF<SUB>4</SUB> plasma treatment. </LI> <LI> CF<SUB>4</SUB> plasma modified membrane exhibited stable water flux and salt rejection. </LI> <LI> CF<SUB>4</SUB> plasma modified membranes showed good potential for CSG RO brine treatment. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Deciphering the molecular mechanisms underlying the plasma membrane targeting of PRMT8

( Sang-won Park ),( Yong-woo Jun ),( Ha-eun Choi ),( Jin-a Lee ),( Deok-jin Jang ) 생화학분자생물학회 2019 BMB Reports Vol.52 No.10

Arginine methylation plays crucial roles in many cellular functions including signal transduction, RNA transcription, and regulation of gene expression. Protein arginine methyltransferase 8 (PRMT8), a unique brain-specific protein, is localized to the plasma membrane. However, the detailed molecular mechanisms underlying PRMT8 plasma membrane targeting remain unclear. Here, we demonstrate that the N-terminal 20 amino acids of PRMT8 are sufficient for plasma membrane localization and that oligomerization enhances membrane localization. The basic amino acids, combined with myristoylation within the N-terminal 20 amino acids of PRMT8, are critical for plasma membrane targeting. We also found that substituting Gly-2 with Ala [PRMT8(G2A)] or Cys-9 with Ser [PRMT8(C9S)] induces the formation of punctate structures in the cytosol or patch-like plasma membrane localization, respectively. Impairment of PRMT8 oligomerization/dimerization by Cterminal deletion induces PRMT8 mis-localization to the mitochondria, prevents the formation of punctate structures by PRMT8(G2A), and inhibits PRMT8(C9S) patch-like plasma membrane localization. Overall, these results suggest that oligomerization/dimerization plays several roles in inducing the efficient and specific plasma membrane localization of PRMT8. [BMB Reports 2019; 52(10): 601-606]

Development of a highly-permeable thin-film-based nanofiltration membrane by using surface treatment with Air-Ar plasma

Zeynab Kiamehr,Bijan Farokhi,Sayed Mohsen Hosseini 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.1

Surface modification of thin-film nanofiltration membranes was carried out to produce high water permeable NF membranes by Air-Ar plasma treatment. The effect of composition of used gases on membrane properties was investigated. Results showed that the plasma treatment decreased the water contact angle obviously from 80.4o to 6.5o, which in turn would increase the membrane surface hydrophilicity. The results of FTIR spectra decisively confirmed the formation of hydrophilic nitrogen and oxygen compounds on the membrane surface. The SEM images of membrane surface also showed significant changes after plasma treatment. AFM analysis indicated smoother surface for the modified membranes compared to pristine membrane; the roughness declined from 55.85 nm for virgin membrane to 28.33 nm for modified membranes. The salt rejection was 90% for pristine membrane and 76.35% to 92.45% for the plasma treated membranes. The water flux for modified membrane treated by 50% Air-50% Ar plasma increased ~1,446.1% compared to the virgin membrane, whereas the selectivity declined only ~15.1%.

Identification of Phospholipase C Activated by $GTP{\gamma}S$ in Plasma Membrane of Oat Cell

Kim, Hyae-Kyeong,Park, Moon-Hwan,Chae, Quae Korean Society for Biochemistry and Molecular Biol 1995 Journal of biochemistry and molecular biology Vol.28 No.5

In order to investigate whether phospholipase C (PLC) activity in oat celIs is regulated by Gprotein, we have characterized PLC in plasma membranes of oat tissues. To identify the purified plasma membrane, $K^+$-stimulated, $Mg^{2+}$-dependent ATPase activity was measured. The activity of ATPase was shown to be proportional to the concentration of membrane protein. To examine the PLC activity regulated by G-protein, we used the inside-out and outside-out plasma membrane mixture isolated from the oat cells. The plasma membrane mixture showed higher PLC activity than the one of the outside-out plasma membrane. This suggests that PLC activity is located at the cytoplasmic surface of plasma membrane. PLC activity in plasma membrane mixture was dependent on $Ca^{2+}$ with maximum activity at 100 ${\mu}m$ $Ca^{2+}$ and it was inhibited by 1 mM EGTA. Using Sep-pak $Accell^{TM}$ Plus QMA chromatography, we found that inositol 1,4,5-trisphosphate ($IP_3$) was produced in the presence of 10 ${\mu}m$ $Ca^{2+}$. The PLC activity in the membrane was enhanced by an activator of G-protein ($GTP{\gamma}S$) and not by an inhibitor ($GDP{\beta}S$). This indicates that a G-protein is involved in the activation of PLC in the plasma membrane of oat cells.

부탄올 분리용 투과증발 복합막 제조

김성수,김현영 한국막학회 2009 멤브레인 Vol.19 No.1

부탄올을 투과증발 공정으로 분리하기 위하여 복합공정에 의하여 투과증발막을 제조하였다. 상업용 poly(dime-thylsiloxane) (PDMS) 막을 plasma 처리시키거나, polysulfone, poly(ether imide) 막을 지지체로 사용하여 plasma 처리 및 PDMS 코팅의 복합공정을 적용하였다. 헥산계열과 실란계열 유기 화합물을 사용하여 PDMS막을 plasma 처리하였을 경우 막 표면의 소수성을 증가시켜서 부탄을 선택도가 12.56까지 향상되었다. 반면에 투과량은 막 표면의 소수성 증대와 free volume의 변화로 인해 1.15 kg/m 2 ·hr까지 감소되어 선택도와 반대의 성향을 나타내었다. 막의 소수성이 증가함에 따라 접촉각과 상대적 sorption 비가 증가하였고, 부탄을 선택도도 향상되었다. PDMS 코팅 용액에서 prepolymer의 함량이 높을수록 부탄올 선택도가 증가하였다. PDMS 코팅과 plasma 처리 공정의 순서에 따른 영향을 조사하였다. 부탄올과 노르말 헥산으로 plasma 처리할 경우 plasma처리, PDMS 코팅 순으로 제조된 막의 분리 성능이 우수하였고 hexamethyldisilane과 hex-amethyldisilazane을 사용한 경우에는 역순으로 제조된 막의 분리 성능이 더 우수한 것으로 나타났다. Pervaporation membrane for butanol separation was prepared by hybrid process. Plasma treatment of commercial poly(dimethylsiloxane) (PDMS) membrane was attempted and combination of plasma treatment and PDMS solution coating on polysulfone, poly(ether imide) supports were also performed. Plasma treatment of PDMS membrane with hexane and silane group compounds was performed to increase the hydrophobicity of the surface, which enhanced the separation factor upto 12.5 at the expense of flux decrease down to 1.15 kg/m 2 ·hr. Contact angle and relative sorption ratio were also related with hydrophobicity of the memrbane. Increase of PDMS prepolymer composition resulted in dense structure of coating layer with better separation factor. Effects of sequence of PDMS coating vs. plasma treatment were examined. It was found that plasma treatment with butanol and n-hexane plasma followed by PDMS coating showed better performance and vice versa for plasma treatment with hexamethyldisilane and hexamethyldisilazane.

Performance enhancement of membrane electrode assemblies with plasma etched polymer electrolyte membrane in PEM fuel cell

Cho, Yong-Hun,Bae, Jin Woo,Cho, Yoon-Hwan,Lim, Ju Wan,Ahn, Minjeh,Yoon, Won-Sub,Kwon, Nak-Hyun,Jho, Jae Young,Sung, Yung-Eun Elsevier 2010 International journal of hydrogen energy Vol.35 No.19

<P><B>Abstract</B></P><P>In this work, a surface modified Nafion 212 membrane was fabricated by plasma etching in order to enhance the performance of a membrane electrode assembly (MEA) in a polymer electrolyte membrane fuel cell. Single-cell performance of MEA at 0.7V was increased by about 19% with membrane that was etched for 10min compared to that with untreated Nafion 212 membrane. The MEA with membrane etched for 20min exhibited a current density of 1700mAcm<SUP>−2</SUP> at 0.35V, which was 8% higher than that of MEA with untreated membrane (1580mAcm<SUP>−2</SUP>). The performances of MEAs containing etched membranes were affected by complex factors such as the thickness and surface morphology of the membrane related to etching time. The structural changes and electrochemical properties of the MEAs with etched membranes were characterized by field emission scanning electron microscopy, Fourier transform-infrared spectrometry, electrochemical impedance spectroscopy, and cyclic voltammetry.</P>

Effects of Surface Modification of the Membrane in the Ultrafiltration of Waste Water

Cho Dong Lyun,Kim Sung-Hyun,Huh Yang Il,Kim Doman,Cho Sung Yong,Kim Byung-Hoon The Polymer Society of Korea 2004 Macromolecular Research Vol.12 No.6

An ultrafiltration membrane (polyethersulfone, PM 10) was surface-modified by treating it with low-tem­perature plasmas of oxygen, acrylic acid (AA), acetylene, diaminocyolohexane (DACH), and hexamethyldisiloxane (HMDSO). The effects that these modifications have on the filtration efficiency of a membrane in waste water treat­ment were investigated. The oxygen, AA, and DACH plasma-treated membranes became more hydrophilic. The water contact angles ranged from < $10^{\circ}\;to\;55^{\circ}$ depending on the type of plasma and the treatment conditions. The oxygen plasma-treated membranes displayed a higher initial flux $(312-429\%),$ but lower rejection $(6-91\%),$ than did an untreated membrane. The AA plasma-treated membranes displayed lower or higher initial flux $(42-156\%),$ depending upon the treatment conditions, but higher rejection $(224-295\%)$ in all cases. The DACH plasma-treated membranes displayed lower initial flux. All of them, especially the AA plasma-treated membrane, displayed improved fouling resistance with either a slower or no flux decline. Acetylene and HMDSO plasma-treated membranes became more hydrophobic and displayed both lower initial flux and lower fouling resistance.

Fabrication Nafion membrane with coupled effect of Plasma etching and Annealing for Polymer Electrolyte Membrane Fuel Cell

Tuyet Anh Pham,Le Vu Nam,Segeun Jang(장세근),Sang Moon Kim(김상문) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4

In polymer electrolyte membrane fuel cells (PEMFCs), a thin electrolyte membrane is highly preferable due to its reduced ohmic resistance which leads to enhanced kinetics of electrochemical reactions. On the other aspect, the mechanical properties of the thin membrane get significantly lowered which restricts the thickness of the membrane. In this work, we propose a simple process that combines plasma etching and annealing (E-T) process to fabricate thin Nafion® membranes with enhanced mechanical characteristics. The fabricated membranes are characterized through a tensile test, field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and Fourier transform infrared spectrometry (FT-IR). The plasma etching process effectively reduces the membrane thickness, while generating nano-roughness on the surface. Furthermore, the roughened surface gets flattened during the annealing process, which also increases the tensile stress of the membrane by up to ~30 %. After constructing fuel cells with the fabricated membranes, the device performances are measured. Thanks to E-T process, the 15 µm-thick membrane shows maximum power density of 22.5 % higher in the condition of 70 ℃ and 92% relative humidity (RH), and 19.3 % higher in the condition of 89.5 ℃ and 45% RH, compared to that of a 25 µm-thick conventional membrane.

Comparative Study on Components and Activities of Sperm Head Plasma Membrane in Active and Hibernating Animals

오영근,안병식,최인호,정노팔,신형철,곽병주,Oh, Yung-Keun,Ahn, Byung-Sik,Choi, In-Ho,Jung, Noh-Pal,Shin, Hyung-Cheul,Kwak, Byoung-Ju Korean Society of Electron Microscopy 1999 Applied microscopy Vol.29 No.2

북부 온대지방에 서식하는 박쥐는 그 대부분이 동면을하며, 그 생식유형은 특이하여 가을에 교미하여 사정된 정자는 자성생식도내에 긴 동면기간 동안 저장되어 있는 것으로 알려져 있다(예: 한국큰관박쥐). 환언하면 저장되어 있던 정자는 이듬해 봄에 배란되는 난자와 수정하여 초여름에 출산하게 된다. 본 연구는 월동하는 정자 두부 Plasma membrane의 성분과 활성 등 형태적 및 기능적 특성을 관찰 분석함으로써, 인공임신율을 높일 수 있는 보다 효과적인 한냉온도 정자저장방법을 모색하기 위하여 시도되었다. 동면하는 한국큰관박쥐와 햄스타 및 비동면동물(마우스)의 정자 Plasma membrane이, 실온과 한냉온도(박쥐-동면온도)에서, 생존율, 첨체반응을, 단백질분포, 능동수송에 관여되는 효소$(Na^+-K^+-ATPase)$의 활성 및 주사전자현미경적 조직화학상을 분석하였다. 본 연구에서 얻은 실험결과에 의거하면, 동면동물인 한국큰관박쥐와 햄스타 및 비동면동물인 마우스 정자의 생존율과 첨체반응율은, 실온과 한냉(박쥐-동면)온도간에 의의있는 차이를 발견할 수 없었고, 단백질 분포와 $Na^+-K^+-ATPase$ 효소활성 및 주사전자현미경적 조직화학적 소견에 있어서도 두 온도간에 의의있는 차이는 없었다. 이와 같이 실온과 한냉온도 간에 형태적 기능적 차이가 없다고 하는 사실은, 동면동물이든 비동면동물이든 Spermatozoa plasma membrane이 동면중 또는 동면 이후에 안정적인 수정을 보장해 주는 형태적 및 기능적 보호구조임을 시사해 준다. Fertilization pattern of north temperate bats is known to be unique for their sperm storage in the female reproductive tract during hibernation (e.g. Korean greater horseshoe bats). They copulate in fall but their ejaculated spermatozoa survive until the next spring. In another words they can persist to survive during long hibernation under the cold condition $(8\sim13^{\circ}C)$ and are to be fertilized with the ovum ovulated in the next spring, so called delayed fertilization. The present study was designed to observe morphological and functional changes of spermatozoa plasma membrane of the bats, hamsters which are hibernators, and mice which are non-hibernators in the room and the cold (bat-hibernation) temperatures and to confirm influence of the temperature on spermatozoa; survival rate, acrosome reaction rate, protein distribution, $Na^+-K^+-ATPase$ activities and scanning electron microscopic histochemistry. Based on the experimental results obtained in the present study, there were no significant morphological and functional differences in the spermatozoa plasma membrane in both the room and cold (bat-hibernation) temperatures and such an absence of difference suggests that the spermatozoa plasma membrane might play a pertinent role as a protector for consistent fertilization during and after hibernation.