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  • 1
    Publication Date: 2016-04-29
    Description: 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 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, by operating the cells at higher temperatures without external humidification, the membrane is self-humidified with water generated by electrochemical reactions. 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉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, Michael D -- Lee, Young Moo -- England -- Nature. 2016 Apr 28;532(7600):480-3. doi: 10.1038/nature17634.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Energy Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea. ; Department of Life Science, College of Natural Science, Hanyang University, Seoul 133-791, South Korea. ; School of Mechanical Engineering, College of Engineering, Hanyang University, Seoul 133-791, South Korea. ; Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, Victoria 3168, Australia. ; State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China. ; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27121841" target="_blank"〉PubMed〈/a〉
    Keywords: Biomimetic Materials/chemistry ; Biomimetics ; Cactaceae/metabolism ; Desiccation ; Dialysis ; Electrochemistry ; Humidity ; Hydrophobic and Hydrophilic Interactions ; *Membranes, Artificial ; *Nanotechnology ; Plant Stomata/metabolism ; Polymers/*chemistry ; Protons ; Surface Properties ; Temperature ; Water/*analysis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    ISSN: 1617-4623
    Keywords: Key wordsnrd ; Ribonucleoside diphosphate reductase ; IciA ; DnaA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The E. coli nrd operon contains the genes encoding the two subunits of ribonucleoside diphosphate reductase. We found that the IciA protein binds specifically to the AT-rich upstream region of nrd promoter. In vivo overexpression of IciA increases the expression of nrd gene by four- to five-fold, suggesting that IciA functions as a transcriptional activator for the nrd gene.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1617-4623
    Keywords: Key words Replication initiation ; iciA ; Phosphate regulon ; PhoB ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The IciA protein from Escherichia coli has been shown specifically to inhibit the in vitro initiation of chromosomal DNA replication. However, the in vivo role of IciA has not yet been established. In order to investigate the in vivo function of this protein, expression of the iciA gene was studied by monitoring the β-galactosidase activity specified by an iciA promoter-lacZ fusion inserted into the chromosome. Among the conditions tested (carbon starvation, the stringent response, phosphate starvation, and the SOS response), only phosphate depletion increased iciA expression. Supplementation of phosphate-depleted cultures with inorganic phosphate reduced the β-galactosidase activity to basal levels. Enhanced expression of iciA-lacZ was dependent upon the PhoB protein. PhoB is known to be a transcriptional activator of the Pho regulon, expression of which is activated during phosphate starvation. It was also found that the iciA promoter contains a PhoB protein-binding sequence, termed the Pho box, which is necessary for the activation of genes of the Pho regulon. These results suggest that the iciA gene is a member of the Pho regulon.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 653-655 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have developed a technique to form Si microstructures at preassigned positions on Si substrates. The key element of this technique is resistless patterning of ultrathin SiO2 mask layers by direct electron-beam exposure. Selective-area growth of Si was accomplished by two different chemistries: flow-modulated plasma-enhanced chemical vapor deposition (CVD) at 473 K or ultra-high-vacuum CVD at 853 K. Epitaxial deposition was achieved by the latter growth method when a mask layer with minimum thickness for deposition selectivity (approximately 0.2 nm) was employed. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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