73 research outputs found
Effect of Dy substitution in the giant magnetocaloric properties of HoB
Recently, a massive magnetocaloric effect near the liquefaction temperature
of hydrogen has been reported in the ferromagnetic material HoB. Here we
investigate the effects of Dy substitution in the magnetocaloric properties of
HoDyB alloys ( = 0, 0.3, 0.5, 0.7, 1.0). We
find that the Curie temperature () gradually increases upon
Dy substitution, while the magnitude of the magnetic entropy change || at = decreases from 0.35 to 0.15
J cm K for a field change of 5 T. Due to the presence of two
magnetic transitions in these alloys, despite the change in the peak magnitude
of ||, the refrigerant capacity () and
refrigerant cooling power () remains almost constant in all
doping range, which as large as 5.5 J cm and 7.0 J cm for a field
change of 5 T. These results imply that this series of alloys could be an
exciting candidate for magnetic refrigeration in the temperature range between
10-50 K.Comment: 19 pages, 5 figures, 2 table
Incidence of sexually transmitted hepatitis C virus infection among men who have sex with men in Japan from 2009 to 2023
Although the prevalence of hepatitis C virus (HCV) infection has decreased significantly with the advent of direct-acting antiviral agents, HCV is known to spread as a sexually transmitted disease among men who have sex with men (MSM), and this study aims to provide a perspective on the future prevalence of HCV in Japan. We examined incidence in two groups of MSM with HIV attending our institution in this retrospective cohort study, from 2009 to 2019 and from 2020 to May 2023 and investigated their background factors. Twenty-two cases were newly confirmed to be HCV infection in 2009-2019 and a total of 9 cases in 2020-2023, with an incidence rate of 5.04 per 1000 person-years in 2009-2019 and 5.55 per 1000 person-years in 2020-2023. All of them were diagnosed at routine outpatient visits for HIV, and few cases were considered to have symptoms of suspected hepatitis that led to a visit to the hospital and a diagnosis of HCV. Although HCV is still prevalent among MSM in Japan, it is possible that it would not have been diagnosed without testing at regular visits as in the case of people with HIV, and that the true prevalence rate among MSM, including non-HIV-infected persons, may be much higher
Data-driven Exploration of New Pressure-induced Superconductivity in PbBiTe with Two Transition Temperatures
Candidates compounds for new thermoelectric and superconducting materials,
which have narrow band gap and flat bands near band edges, were exhaustively
searched by the high-throughput first-principles calculation from an inorganic
materials database named AtomWork. We focused on PbBiTe which has the
similar electronic band structure and the same crystal structure with those of
a pressure-induced superconductor SnBi2Se4 explored by the same data-driven
approach. The PbBiTe was successfully synthesized as single crystals
using a melt and slow cooling method. The core level X-ray photoelectron
spectroscopy analysis revealed Pb2+, Bi3+ and Te2- valence states in
PbBiTe. The thermoelectric properties of the PbBiTe sample were
measured at ambient pressure and the electrical resistivity was also evaluated
under high pressure using a diamond anvil cell with boron-doped diamond
electrodes. The resistivity decreased with increase of the pressure, and two
pressure-induced superconducting transitions were discovered at 3.4 K under
13.3 GPa and at 8.4 K under 21.7 GPa. The data-driven approach shows promising
power to accelerate the discovery of new thermoelectric and superconducting
materials
Direct Patterning of Boron-doped Amorphous Carbon Using Focused Ion Beam-assisted Chemical Vapor Deposition
The deposition of boron-doped amorphous carbon thin films on SiO2 substrate
was achieved via a focused ion beam-assisted chemical vapor deposition of
triphenyl borane (C18H15B) and triphenyl borate (C18H15BO3). The existence of
boron in the deposited film from triphenyl borane, with a precursor temperature
of 90 {\deg}C, was confirmed by a core level X-ray photoelectron spectroscopy
analysis. The film exhibited a semiconducting behavior with a band gap of 285
meV. Although the band gap was decreased to 197 meV after an annealing process,
the film was still semiconductor. Additionally, a drastic reduction of the
resistance on the deposited film by applying pressures was observed from an
in-situ electrical transport measurements using a diamond anvil cell
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