58 research outputs found

    Microstructure and mechanical behavior of Ti-25Nb-25Zr alloy prepared from pre-alloyed and hydride-mixed elemental powders

    Full text link
    A study has been undertaken on the feasibility of the powder-metallurgy manufacturing process to fabricate β-type Ti-25Nb-25Zr alloy (mass%) for biomedical applications. The Ti-25Nb-25Zr alloy was fabricated from a mixture of TiH2 with constituent elemental powders, and from a pre-alloyed Plasma Rotating Electrode Processed (PREP) Ti-25Nb-25Zr powder, separately. It is shown that different processing methods led to different microstructures and mechanical properties. The Ti-25Nb-25Zr compact prepared by pre-alloyed powder exhibits poor strength whereas TiH2 processed Ti-25Nb-25Zr compact exhibits comparatively ultra-fine grained microstructure with significantly improved strength. The proposed fabrication method may have several opportunities to fabricate metallic alloys with enhanced mechanical properties.Sharma B., Vajpai S.K., Kawabata M., et al. Microstructure and mechanical behavior of Ti-25Nb-25Zr alloy prepared from pre-alloyed and hydride-mixed elemental powders. Materials Transactions 61, 562 (2020); https://doi.org/10.2320/matertrans.MT-MK2019001

    Peculiar microstructural evolution and tensile properties of β-containing γ-TiAl alloys fabricated by electron beam melting

    Get PDF
    The microstructure and tensile properties of β-containing Ti–44Al–4Cr alloy rods additively manufactured by electron beam melting (EBM) process were examined as a function of input energy density determined by the processing parameters. To the best of our knowledge, this is the first report to demonstrate that two types of fine microstructures have been obtained in the β-containing γ-TiAl alloys by varying the energy density during the EBM process. A uniform α2/β/γ mixed structure containing an α2/γ lamellar region and a β/γ dual-phase region is formed at high energy density conditions. On the other hand, a lower energy density leads to the formation of a peculiar layered microstructure perpendicular to the building direction, consisting of a ultrafine α2/γ lamellar grain layer and a α2/β/γ mixed structure layer. The difference in the microstructures originates from the difference in the solidification microstructure and the temperature distribution from the melt pool, which are dependent on the energy density. Furthermore, it was found that the strength of the alloys is closely related to the volume fractions of the β phase and the ultrafine α2/γ lamellar grains which originates from the massive α grains formed by rapid cooling under low energy density conditions. The alloys with high amounts of these peculiar microstructures exhibit high strength comparable to and higher than the conventional β-containing γ-TiAl at room temperature and 1023 K, respectively.Cho K., Kawabata H., Hayashi T., et al. Peculiar microstructural evolution and tensile properties of β-containing γ-TiAl alloys fabricated by electron beam melting. Additive Manufacturing, 46, 102091. https://doi.org/10.1016/j.addma.2021.102091

    Trends in Head and Neck Cancer Mortality from 1999 to 2019 in Japan : An Observational Analysis

    Get PDF
    The number of cases of head and neck cancer (HNC) and related deaths has recently increased worldwide. To the best of our knowledge, few studies have examined crude or age-adjusted HNC mortality rates in Japan. Therefore, this study aimed to determine the trends in crude and age-adjusted mortality rates for HNC per million individuals in Japan from 1999 to 2019. In Japan, the number of HNC-related deaths increased 1.48-fold. Age-adjusted mortality rates for HNC were four times higher in men than in women, and the rates for both men and women decreased over the 21-year period. This study clarifies the changes in age-adjusted mortality rates of HNC in Japan over time and will aid in developing targeted screening and prevention programs for HNC.Globally, the numbers of head and neck cancer (HNC) cases and related deaths have recently increased. In Japan, few studies have examined crude or age-adjusted HNC mortality rates. Therefore, this study aimed to determine the trends in crude and age-adjusted mortality rates for HNC per million individuals in Japan from 1999 to 2019. Data on HNC-associated deaths were extracted from the national death certificate database using the International Classification of Diseases, Tenth Revision (n = 156,742). HNC mortality trends were analysed using joinpoint regression models to estimate annual percentage change (APC) and average APC (AAPC). Among men, no significant change was observed in the age-adjusted death rate trend from 1999 to 2014; however, a marked decrease was observed from 2014 to 2019. No changing point was observed in women. Age-adjusted mortality rates continuously decreased over the 21-year period, with an AAPC of −0.7% in men and −0.6% in women. In conclusion, the overall trend in age-adjusted rates of HNC-associated deaths decreased, particularly among men, in the past 5 years. These results will contribute to the formulation of medical policies to develop targeted screening and prevention programmes for HNC in Japan and determine the direction of treatment strategies

    Polarimetric calibration of a spectropolarimeter instrument with high precision: Sunrise chromospheric infrared spectropolarimeter (SCIP) for the sunrise iii balloon telescope

    Get PDF
    The Sunrise chromospheric infrared spectropolarimeter (SCIP) installed in the international balloon experiment sunrise iii will perform spectropolarimetric observations in the near-infrared band to measure solar photospheric and chromospheric magnetic fields simultaneously. The main components of SCIP for polarization measurements are a rotating wave plate, polarization beam splitters, and CMOS imaging sensors. In each of the sensors, SCIP records the orthogonal linearly polarized components of light. The polarization is later demodulated on-board. Each sensor covers one of the two distinct wavelength regions centered at 770 and 850 nm. To retrieve the proper circular polarization, the new parameter , defined as the 45° phase shifted component of Stokes in the modulation curve, is introduced. SCIP is aimed at achieving high polarization precision (1<3×10−4 of continuum intensity) to capture weak polarization signals in the chromosphere. The objectives of the polarization calibration test presented in this paper are to determine a response matrix of SCIP and to measure its repeatability and temperature dependence to achieve the required polarization precision. Tolerances of the response matrix elements were set after considering typical photospheric and chromospheric polarization signal levels. We constructed a feed optical system such that a telecentric beam can enter SCIP with the same -number as the light distribution instrument of the sunrise iii telescope. A wire-grid linear polarizer and achromatic wave plate were placed before SCIP to produce the known polarization. The obtained response matrix was close to the values expected from the design. The wavelength and spatial variations, repeatability, and temperature dependence of the response matrix were confirmed to be smaller than tolerances. © 2022 Optica Publishing Group.Japan Society for the Promotion of Science KAKENHI (JP18H05234); Max Planck Foundation; National Aeronautics and Space Administration (#80NSSC18K0934); ISAS/JAXA Small Mission-of Opportunity Program; Spanish Research Agency (RTI2018-096886-B-C5); Centro de Excelencia Severo Ochoa Program (SEV-2017-0709).Peer reviewe

    SPGCam: A specifically tailored camera for solar observations

    Get PDF
    This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Designing a new astronomical instrument typically challenges the available cameras on the market. In many cases, no camera can fulfill the requirements of the instrument in terms of photon budget, speed, and even interfaces with the rest of the instrument. In this situation, the only options are to either downgrade the performance of the instrument or design new cameras from scratch, provided it is possible to identify a compliant detector. The latter is the case of the SPGCams, the cameras developed to be used with the Tunable Magnetograph (TuMag) and the Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) for the Sunrise iii mission. SPGCams have been designed, developed, and built entirely in-house by the Solar Physics Group (SPG) at the Instituto de Astrofísica de Andalucía (IAA-CSIC). We report here on the scientific rationale and system engineering requirements set by the two instruments that drove the development, as well as on the technical details and trade-offs used to fulfill the specifications. The cameras were fully verified before the flight, and results from the assembly and verification campaign are presented as well. SPGCams share the design, although some parametric features differentiate the visible cameras (for TuMag) and the IR ones (for SCIP). Even though they were specifically developed for the Sunrise iii mission, the robust and careful design makes them suitable for different applications in other astronomical instruments. © 2023 Orozco Suárez, Álvarez García, López Jiménez, Balaguer Jiménez, Hernández Expósito, Labrousse, Bailén, Bustamante Díaz, Bailón Martínez, Aparicio del Moral, Morales Fernández, Sánchez Gómez, Tobaruela Abarca, Moreno Mantas, Ramos Más, Pérez Grande, Piqueras Carreño, Katsukawa, Kubo, Kawabata, Oba, Rodríguez Valido, Magdaleno Castelló and Del Toro Iniesta.This work was funded by the Spanish MCIN/AEI, under projects RTI 2018-096886-B-C5, PID 2021-125325OB-C5, and PCI 2022-135009-2, and co-funded by European FEDER funds, “A way of making Europe,” under grants CEX 2021-001131-S and 10.13039/501100011033.Peer reviewe

    The JCMT BISTRO Survey: Studying the Complex Magnetic Field of L43

    Get PDF
    We present observations of polarized dust emission at 850 μm from the L43 molecular cloud, which sits in the Ophiuchus cloud complex. The data were taken using SCUBA-2/POL-2 on the James Clerk Maxwell Telescope as a part of the BISTRO large program. L43 is a dense (NH 10 22 2 ~ –1023 cm−2) complex molecular cloud with a submillimeter-bright starless core and two protostellar sources. There appears to be an evolutionary gradient along the isolated filament that L43 is embedded within, with the most evolved source closest to the Sco OB2 association. One of the protostars drives a CO outflow that has created a cavity to the southeast. We see a magnetic field that appears to be aligned with the cavity walls of the outflow, suggesting interaction with the outflow. We also find a magnetic field strength of up to ∼160 ± 30 μG in the main starless core and up to ∼90 ± 40 μG in the more diffuse, extended region. These field strengths give magnetically super- and subcritical values, respectively, and both are found to be roughly trans-Alfvénic. We also present a new method of data reduction for these denser but fainter objects like starless cores

    DOCK2 is involved in the host genetics and biology of severe COVID-19

    Get PDF
    「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target

    The JCMT BISTRO Survey: Revealing the Diverse Magnetic Field Morphologies in Taurus Dense Cores with Sensitive Submillimeter Polarimetry

    Get PDF
    Abstract: We have obtained sensitive dust continuum polarization observations at 850 μm in the B213 region of Taurus using POL-2 on SCUBA-2 at the James Clerk Maxwell Telescope as part of the B-fields in STar-forming Region Observations (BISTRO) survey. These observations allow us to probe magnetic field (B-field) at high spatial resolution (∼2000 au or ∼0.01 pc at 140 pc) in two protostellar cores (K04166 and K04169) and one prestellar core (Miz-8b) that lie within the B213 filament. Using the Davis–Chandrasekhar–Fermi method, we estimate the B-field strengths in K04166, K04169, and Miz-8b to be 38 ± 14, 44 ± 16, and 12 ± 5 μG, respectively. These cores show distinct mean B-field orientations. The B-field in K04166 is well ordered and aligned parallel to the orientations of the core minor axis, outflows, core rotation axis, and large-scale uniform B-field, in accordance with magnetically regulated star formation via ambipolar diffusion taking place in K04166. The B-field in K04169 is found to be ordered but oriented nearly perpendicular to the core minor axis and large-scale B-field and not well correlated with other axes. In contrast, Miz-8b exhibits a disordered B-field that shows no preferred alignment with the core minor axis or large-scale field. We found that only one core, K04166, retains a memory of the large-scale uniform B-field. The other two cores, K04169 and Miz-8b, are decoupled from the large-scale field. Such a complex B-field configuration could be caused by gas inflow onto the filament, even in the presence of a substantial magnetic flux
    corecore