116 research outputs found

    Kinetic Characteristics of Electrochemical Reduction of SiO₂ Granules in Molten CaCl₂

    Get PDF
    The kinetic characteristics of electrochemical reduction of SiO₂ granules in molten CaCl₂ were investigated to develop a new process for producing solar-grade silicon. The reduction rate was evaluated based on the time dependence of the reduction fractions measured from the growth of the reduced Si layer and the weight change of the samples during electrolysis. The samples were prepared by potentiostatic electrolysis of SiO₂ granules in molten CaCl₂ at 1123 K. The results indicated that the reduction was fast at the initial stage of electrolysis, and gradually slowed as the reaction progressed. The apparent current density reached 0.7 A cm⁻² at the initial stage, which was comparable to the commercial Hall-Héroult process for aluminum production

    Significance of common variants on human chromosome 8q24 in relation to the risk of prostate cancer in native Japanese men

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Common variants on human chromosome 8q24, rs1447295 (C/A) and rs6983267 (T/G), have been recently linked to the prevalence of prostate cancer in European and American populations. Here, we evaluated whether the single-nucleotide polymorphisms rs1447295 and rs6983267 were associated with the risk of sporadic prostate cancer as well as latent prostate cancer in a native Japanese population.</p> <p>Results</p> <p>We analyzed genomic DNA samples from 391 sporadic prostate cancer patients, 323 controls who had died from causes unrelated to cancer and 112 Japanese men who were diagnosed as having latent prostate cancer based on autopsy results. The polymorphisms were determined by allelic discrimination using a fluorescent-based TaqMan assay. The A allele of rs1447295 was significantly associated with the risk of sporadic prostate cancer (<it>p </it>= 0.04; age-adjusted OR, 1.34), while the G allele of rs6983267 showed a trend towards being a high-risk allele (<it>p </it>= 0.06; age-adjusted OR, 1.27). No significant difference between these two polymorphisms and the risk of latent prostate cancer was observed in the present Japanese population.</p> <p>Conclusion</p> <p>Known variants on human chromosome 8q24 may be risk factors for sporadic prostate cancer in native Japanese men.</p

    Fabrication of photo-electrochemical biosensors for ultrasensitive screening of mono-bioactive molecules: the effect of geometrical structures and crystal surfaces

    Get PDF
    The controlled design of biosensors based on the photo-electrochemical technique with high selectivity, sensitivity, and rapid response for monitoring of mono-bioactive molecules, particularly dopamine (DA) levels in neuronal cells is highly necessary for clinical diagnosis. Hierarchical carbon-, nitrogen-doped (CN) nickel oxide spear thistle (ST) flowers associated in single-heads (S), and symmetric and asymmetric-double heads (D and A, respectively) that are tightly connected through a micrometric dipole-like rod or trunk were fabricated by using a simple synthetic protocol. The CN-ST flower heads were decorated with dense nano-tubular like hedgehog needle skins in vertical alignments. These designated architectures are key features for creating biosensor surface electrodes for photo-electrochemical, ultrasensitive screening of mono-bioactive molecules. The exceptional electrode designs produced numerous catalytically active sites, large surface area, and high electron-transfer mobility. The active coating of carbon–nitrogen nanospheres significantly enhanced the photo-electrocatalytic activity of the prepared biosensor electrodes and prevented leakage of photocatalytic activity under long-term exposure to irradiation. Among all photo-electrochemical assays, the biosensors showed significant sensitivity and selectivity for DA in the presence of interfering molecules such as ascorbic acid (AA), uric acid (UA), adrenaline (A), and noradrenaline (NA). The photo-electrochemical property of the CN-SST-{110} crystal surface electrode showed significant sensing performance for DA in terms of unimpeded diffusion pathways, a wide concentration-detection range, and a low detection limit, even in the presence of potentially interfering molecules compared with other electrode-modified CN-DST-{111} and CN-AST-{101} crystal surfaces. Furthermore, the CN-SST photo-biosensor electrode shows potential in the selective and sensitive determination of DA in real samples, such as human serum and secreted DA from living cells. This finding indicates that the hierarchical ST biosensor may enable analytical discrimination and monitoring of DA and can be employed for clinical diagnosis application

    Fabrication of a 64-Pixel TES Microcalorimeter Array with Iron Absorbers Uniquely Designed for 14.4-keV Solar Axion Search

    Full text link
    If a hypothetical elementary particle called an axion exists, to solve the strong CP problem, a 57Fe nucleus in the solar core could emit a 14.4-keV monochromatic axion through the M1 transition. If such axions are once more transformed into photons by a 57Fe absorber, a transition edge sensor (TES) X-ray microcalorimeter should be able to detect them efficiently. We have designed and fabricated a dedicated 64-pixel TES array with iron absorbers for the solar axion search. In order to decrease the effect of iron magnetization on spectroscopic performance, the iron absorber is placed next to the TES while maintaining a certain distance. A gold thermal transfer strap connects them. We have accomplished the electroplating of gold straps with high thermal conductivity. The residual resistivity ratio (RRR) was over 23, more than eight times higher than a previous evaporated strap. In addition, we successfully electroplated pure-iron films of more than a few micrometers in thickness for absorbers and a fabricated 64-pixel TES calorimeter structure.Comment: 5 pages, 5 figures, published in IEEE Transactions on Applied Superconductivity on 8 March 202

    NMR and mutational identification of the collagen-binding site of the chaperone Hsp47.

    Get PDF
    Heat shock protein 47 (Hsp47) acts as a client-specific chaperone for collagen and plays a vital role in collagen maturation and the consequent embryonic development. In addition, this protein can be a potential target for the treatment of fibrosis. Despite its physiological and pathological importance, little is currently known about the collagen-binding mode of Hsp47 from a structural aspect. Here, we describe an NMR study that was conducted to identify the collagen-binding site of Hsp47. We used chicken Hsp47, which has higher solubility than its human counterpart, and applied a selective (15)N-labeling method targeting its tryptophan and histidine residues. Spectral assignments were made based on site-directed mutagenesis of the individual residues. By inspecting the spectral changes that were observed upon interaction with a trimeric collagen peptide and the mutational data, we successfully mapped the collagen-binding site in the B/C β-barrel domain and a nearby loop in a 3D-homology model based upon a serpin fold. This conclusion was confirmed by mutational analysis. Our findings provide a molecular basis for the design of compounds that target the interaction between Hsp47 and procollagen as therapeutics for fibrotic diseases
    corecore