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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: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Persistent spectra hole burning is observed at room temperature in the excitation spectrum for the 7F0→5D0 transition of the Sm2+ ions that are doped in aluminosilicate glass. Glass having the composition of Sm2+-doped Al2O3⋅9SiO2 has been prepared by the sol-gel processing of metal alkoxides and the reaction with H2 gas at 800 °C. Sol-gel derived glass enables Sm to be doped in the Sm2+ state of which the 4f6 (7F0)→4f55d band does not overlap with the 5D0→7F0 line. The hole width and depth, which are burned by the DCM dye laser, are ∼15 cm−1 and ∼10% of the total intensity, respectively, at 20 °C. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2018-02-09
    Description: DNA copy number variation is associated with many high phenotypic heterogeneity disorders. We systematically examined the impact of Drosophila melanogaster deletions on gene expression profiles to ask whether increased expression variability owing to reduced gene dose might underlie this phenotypic heterogeneity. Indeed, we found that one-dose genes have higher gene expression variability relative to two-dose genes. We then asked whether this increase in variability could be explained by intrinsic noise within cells due to stochastic biochemical events, or whether expression variability is due to extrinsic noise arising from more complex interactions. Our modeling showed that intrinsic gene expression noise averages at the organism level and thus cannot explain increased variation in one-dose gene expression. Interestingly, expression variability was related to the magnitude of expression compensation, suggesting that regulation, induced by gene dose reduction, is noisy. In a remarkable exception to this rule, the single X chromosome of males showed reduced expression variability, even compared with two-dose genes. Analysis of sex-transformed flies indicates that X expression variability is independent of the male differentiation program. Instead, we uncovered a correlation between occupancy of the chromatin-modifying protein encoded by males absent on the first ( mof ) and expression variability, linking noise suppression to the specialized X chromosome dosage compensation system. MOF occupancy on autosomes in both sexes also lowered transcriptional noise. Our results demonstrate that gene dose reduction can lead to heterogeneous responses, which are often noisy. This has implications for understanding gene network regulatory interactions and phenotypic heterogeneity. Additionally, chromatin modification appears to play a role in dampening transcriptional noise.
    Electronic ISSN: 2160-1836
    Topics: Biology
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