Mineralogy, Three Dimensional Structure, and Oxygen Isotope Ratios of Four Crystalline Particles from Comet 81P/Wild 2

Preliminary examinations of small dust particles from comet 82P/Wild 2 revealed many expected and unexpected features. Among them the most striking feature is the presence of abundant crystalline material in the comet. Synchrotron radiation X-ray diffraction and microtomography are the most efficient methods to detect and describe bulk mineralogical features of crystalline cometary particles. In the present study, in addition to these two non-destructive techniques, electron microscopy and ion-probe mass spectrometry were carried out on the four crystalline particles

Morphology of supported polymer electrolyte ultra-thin films: a numerical study

Morphology of polymer electrolytes membranes (PEM), e.g., Nafion, inside PEM fuel cell catalyst layers has significant impact on the electrochemical activity and transport phenomena that determine cell performance. In those regions, Nafion can be found as an ultra-thin film, coating the catalyst and the catalyst support surfaces. The impact of the hydrophilic/hydrophobic character of these surfaces on the structural formation of the films has not been sufficiently explored yet. Here, we report about Molecular Dynamics simulation investigation of the substrate effects on the ionomer ultra-thin film morphology at different hydration levels. We use a mean-field-like model we introduced in previous publications for the interaction of the hydrated Nafion ionomer with a substrate, characterized by a tunable degree of hydrophilicity. We show that the affinity of the substrate with water plays a crucial role in the molecular rearrangement of the ionomer film, resulting in completely different morphologies. Detailed structural description in different regions of the film shows evidences of strongly heterogeneous behavior. A qualitative discussion of the implications of our observations on the PEMFC catalyst layer performance is finally proposed

Downregulation of SAV1 plays a role in pathogenesis of high-grade clear cell renal cell carcinoma

<p>Abstract</p> <p>Background</p> <p>Clinical outcome of patients with high-grade ccRCC (clear cell renal cell carcinoma) remains still poor despite recent advances in treatment strategies. Molecular mechanism of pathogenesis in developing high-grade ccRCC must be clarified. In the present study, we found that SAV1 was significantly downregulated with copy number loss in high-grade ccRCCs. Therefore, we investigated the SAV1 function on cell proliferation and apoptosis in vitro. Furthermore, we attempted to clarify the downstream signaling which is regulated by SAV1.</p> <p>Methods</p> <p>We performed array CGH and gene expression analysis of 8 RCC cell lines (786-O, 769-P, KMRC-1, KMRC-2, KMRC-3, KMRC-20, TUHR4TKB, and Caki-2), and expression level of mRNA was confirmed by quantitative RT-PCR (qRT-PCR) analysis. We next re-expressed SAV1 in 786-O cells, and analyzed its colony-forming activity. Then, we transfected siRNAs of SAV1 into the kidney epithelial cell line HK2 and renal proximal tubule epithelial cells (RPTECs), and analyzed their proliferation and apoptosis. Furthermore, the activity of YAP1, which is a downstream molecule of SAV1, was evaluated by western blot analysis, reporter assay and immunohistochemical analysis.</p> <p>Results</p> <p>We found that SAV1, a component of the Hippo pathway, is frequently downregulated in high-grade ccRCC. SAV1 is located on chromosome 14q22.1, where copy number loss had been observed in 7 of 12 high-grade ccRCCs in our previous study, suggesting that gene copy number loss is responsible for the downregulation of SAV1. Colony-forming activity by 786-O cells, which show homozygous loss of SAV1, was significantly reduced when SAV1 was re-introduced exogenously. Knockdown of SAV1 promoted proliferation of HK2 and RPTEC. Although the phosphorylation level of YAP1 was low in 786-O cells, it was elevated in SAV1-transduced 786-O cells. Furthermore, the transcriptional activity of the YAP1 and TEAD3 complex was inhibited in SAV1-transduced 786-O cells. Immunohistochemistry frequently demonstrated nuclear localization of YAP1 in ccRCC cases with SAV1 downregulation, and it was preferentially detected in high-grade ccRCC.</p> <p>Conclusions</p> <p>Taken together, downregulation of SAV1 and the consequent YAP1 activation are involved in the pathogenesis of high-grade ccRCC. It is an attractive hypothesis that Hippo signaling could be candidates for new therapeutic target.</p

Microstructure of Catalyst Layers in PEM Fuel Cells Redefined: A Computational Approach

This work comprises an extensive coarse-grained molecular dynamics study of self-organization processes that define the mesoscopic structure of catalyst layers used in polymer electrolyte fuel cells. The detailed structural analysis focuses on agglomeration of Pt-decorated primary particles of graphitized carbon black, formation of ionomer domains, emergence of the porous network, and formation of interfaces between the distinct phases. Insights obtained enable us to decisively redraw the existing structural picture of the catalyst layer. As a key result, we found that ionomer forms a thin adhesive film, which partially covers agglomerates of Pt/carbon. Densely arranged charged side chains of ionomer form a highly ordered array on the ionomer film surface. The preferential orientation of these charged side chains depends on the surface wetting properties of the agglomerates. As a major consequence, results on ionomer structure and distribution, presented in this work, seem to invalidate the classical electrolyte-flooded agglomerate model that has been widely applied to catalyst layers in polymer electrolyte fuel cells. Instead, the structural analysis provided defines a need for novel models of proton transport, water distribution, and Pt effectiveness that account for the thin-film morphology of ionomer and the specific arrangement of surface groups. \ua9 2011 Springer Science+Business Media, LLC.Peer reviewed: YesNRC publication: Ye

60 GHz Radiation Detection Using Electro-Optic Effect of DAST Crystal

Coherent detection using electro-optic effect is an attractive method for high frequency electric field measurement. Organic crystals have the advantages of a large electro-optic coefficient and a small dielectric constant for the high speed detection. We demonstrate for the first time the coherent detection of freely propagating 60 GHz millimeter wave by using organic DAST crystal

Freshwater phytoplankton: biotransformation of inorganic arsenic to methylarsenic and organoarsenic

© 2019, The Author(s). The biotransformation and detoxification mechanisms of arsenic (As) species have been active research topics because of their significance to environmental and human health. Biotransformation of As in phytoplankton has been extensively studied. However, how different growth phases of phytoplankton impact As biotransformation in them remains uncertain. This study investigated the biotransformation of As species in freshwater phytoplankton at different growth phases to ascertain at which growth phase different types of biotransformation occur. At the logarithmic growth phase, arsenate (AsV) (>90%) and arsenite (AsIII) (>80%) predominated in culture media when phytoplankton were exposed to 20 nmol L−1 and 1.0 µmol L−1 of AsV, respectively, and methylarsenic (methylAs) species were not detected in them at all. Intracellular As was mainly present in inorganic forms (iAs) at the logarithmic phase, while substantial amounts of organoarsenic (orgAs) species were detected at the stationary phase. At the stationary phase, AsV comprised the majority of the total As in culture media, followed by AsIII and methylAs, although the methylation of AsV occurred slowly at the stationary phase. Biotransformation of AsV into AsIII and As methylation inside phytoplankton cells occurred mainly at the logarithmic phase, while the biotransformation of As into complex orgAs compounds occurred at the stationary phase. Phytoplankton rapidly released iAs and methylAs species out of their cells at the logarithmic phase, while orgAs mostly remained inside their cells

Long-range-transported bioaerosols captured in snow cover on Mount Tateyama, Japan: impacts of Asian-dust events on airborne bacterial dynamics relating to ice-nucleation activities

The westerly wind travelling at high altitudes over eastern Asia transports aerosols from the Asian deserts and urban areas to downwind areas such as Japan. These long-range-transported aerosols include not only mineral particles but also microbial particles (bioaerosols), that impact the ice-cloud formation processes as ice nuclei. However, the detailed relations of airborne bacterial dynamics to ice nucleation in high-elevation aerosols have not been investigated. Here, we used the aerosol particles captured in the snow cover at altitudes of 2450 m on Mt Tateyama to investigate sequential changes in the ice-nucleation activities and bacterial communities in aerosols and elucidate the relationships between the two processes. After stratification of the snow layers formed on the walls of a snow pit on Mt Tateyama, snow samples, including aerosol particles, were collected from 70 layers at the lower (winter accumulation) and upper (spring accumulation) parts of the snow wall. The aerosols recorded in the lower parts mainly came from Siberia (Russia), northern Asia and the Sea of Japan, whereas those in the upper parts showed an increase in Asian dust particles originating from the desert regions and industrial coasts of Asia. The snow samples exhibited high levels of ice nucleation corresponding to the increase in Asian dust particles. Amplicon sequencing analysis using 16S rRNA genes revealed that the bacterial communities in the snow samples predominately included plant associated and marine bacteria (phyla Proteobacteria) during winter, whereas during spring, when dust events arrived frequently, the majority were terrestrial bacteria of phyla Actinobacteria and Firmicutes. The relative abundances of Firmicutes (Bacilli) showed a significant positive relationship with the ice nucleation in snow samples. Presumably, Asian dust events change the airborne bacterial communities over Mt Tateyama and carry terrestrial bacterial populations, which possibly induce ice-nucleation activities, thereby indirectly impacting climate change