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Nanocrack-regulated self-humidifying membranes
Park, Chi Hoon,Lee, So Young,Hwang, Doo Sung,Shin, Dong Won,Cho, Doo Hee,Lee, Kang Hyuck,Kim, Tae-Woo,Kim, Tae-Wuk,Lee, Mokwon,Kim, Deok-Soo,Doherty, Cara M.,Thornton, Aaron W.,Hill, Anita J.,Guiver, Nature Publishing Group, a division of Macmillan P 2016 Nature Vol.532 No.7600
<P>The regulation of water content in polymeric membranes is important in a number of applications, such as reverse electrodialysis and proton-exchange fuel-cell membranes. External thermal and water management systems add both mass and size to systems, and so intrinsic mechanisms of retaining water and maintaining ionic transport(1-3) in such membranes are particularly important for applications where small system size is important. For example, in proton-exchange membrane fuel cells, where water retention in the membrane is crucial for efficient transport of hydrated ions(1,4-7), by operating the cells at higher temperatures without external humidification, the membrane is self-humidified with water generated by electrochemical reactions(5,8). Here we report an alternative solution that does not rely on external regulation of water supply or high temperatures. Water content in hydrocarbon polymer membranes is regulated through nanometre-scale cracks ('nanocracks') in a hydrophobic surface coating. These cracks work as nanoscale valves to retard water desorption and to maintain ion conductivity in the membrane on dehumidification. Hydrocarbon fuel-cell membranes with surface nanocrack coatings operated at intermediate temperatures show improved electrochemical performance, and coated reverse-electrodialysis membranes show enhanced ionic selectivity with low bulk resistance.</P>
Characteristics of $In_xGa_{1-x}N/GaN$ single quantum well grown by MBE
Kang, T.W.,Kim, C.O.,Chung, G.S,Eom, K.S.,Kim, H.J.,Won, S.H.,Park, S.H.,Yoon, G.S.,Lee, C. M.,Park, C.S.,Chi, C.S.,Lee, H.Y.,Yoon, J.S. The Korean Vacuum Society 1998 Applied Science and Convergence Technology Vol.7 No.1
Structural and optical properties of $In_xGa_{1-X}N$ as well as $In_{0.1}Ga_{0.9}N$/GaN single quantum we11 (SQW) grown on sapphire (0001) substrate with an based GaN using rf-plasma assisted MBE have been investigated. The quality of the InXGal.,N fdm was improved as the growth temperature increased. In PL measurements at low temperatures, the band edge emission peaks of $In_xGa_{1-X}N$ was shifted to red region as an indium cell and substrate temperature increased. For $In_{0.1}Ga_{0.9}N$/GaN SQW, the optical emission energy has blue shift about 15meV in PL peak, due to the confined energy level in the well region. And, the FWHM of the $In_{0.1}Ga_{0.9}N$/GaN SQW was larger than that of the bulk Ino,la.9N films. The broadening of FWHM can be explained either as non-uniformity of Indium composition or the potential fluctuation in the well region. Photoconductivity (PC) decay measurement reveals that the optical transition lifetimes of the SQW measured gradually increased with temperatures.
Seo, Jung Yoon,Jeon, Hwan-Jin,Kim, Jeong Won,Lee, Jiye,Oh, You-Kwan,Ahn, Chi Won,Lee, Jae W. American Chemical Society 2018 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.57 No.5
<P>In an effort to help meet the demand for promising renewable sources of energy, research into innovative downstream processing for microalgae biorefineries is actively underway. In the current work, we used octahedrally shaped ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles for both harvesting and disrupting the cells of microalgae. We were able to use ZnFe<SUB>2</SUB>O<SUB>4</SUB> octahedrons as magnetic flocculants and cell-disruption agents because ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles have both magnetic and photocatalytic properties. The ZnFe<SUB>2</SUB>O<SUB>4</SUB> octahedrons, when simply functionalized with the aminosilane N-[3-(trimethoxysilyl)propyl] ethylenediamine, enabled a rapid and energy-efficient harvesting of microalgae. Furthermore, the ZnFe<SUB>2</SUB>O<SUB>4</SUB> octahedrons, well-known for having photocatalytic properties superior to those of ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles with other morphologies, were used to lyse the algal cell wall with the aid of H<SUB>2</SUB>O<SUB>2</SUB> under simulated sunlight irradiation. We expect microalgae whose cells can be both magnetophoretically separated and lysed by the same ZnFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles to be utilized as bioenergy resources for more efficient downstream processing than is currently available.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/iecred/2018/iecred.2018.57.issue-5/acs.iecr.7b04445/production/images/medium/ie-2017-044455_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ie7b04445'>ACS Electronic Supporting Info</A></P>