160 research outputs found

    The Minimum Mass of the First Stars and the Anthropic Principle

    Get PDF
    The lower limit of the mass of the first stars suggested recently may imply the formation of massive stars of mass greater than 8 solar mass irrespective of the details of the initial mass function. The production of heavy metals from the first stars will ensure a requisite for the existence of life without the anthropic principle.Comment: 3 Pages, to be published in Progress of Theoretical Physics 1997 January issu

    FILM COATING ONTO COHESIVE FINE PARTICLES BY A NOVEL ROTATING FLUIDIZED BED COATER

    Get PDF
    In this study, film coating onto cohesive fine particles was conducted by using a novel rotating fluidized bed coater (RFBC). In order to avoid the formation of agglomeration, baffle plates were equipped inside the RFBC. Coating experiments were conducted under various operating conditions and the coated particles were evaluated based on their physical properties. As a result, coated particles having extremely small degree of agglomeration and favorable prolonged release property of a tracer material could be obtained

    Synthesis of Nitrogen-Doped Carbon Nanocoils with Adjustable Morphology using Ni–Fe Layered Double Hydroxides as Catalyst Precursors

    Get PDF
    Nitrogen-doped carbon nanocoils (CNCs) with adjusted morphologies were synthesized in a one-step catalytic chemical vapour deposition (CVD) process using acetonitrile as the carbon and nitrogen source. The nickel iron oxide/nickel oxide nanocomposites, which were derived from nickel–iron layered double hydroxide (LDH) precursors, were employed as catalysts for the synthesis of CNCs. In this method, precursor-to-catalyst transformation, catalyst activation, formation of CNCs, and nitrogen doping were all performed in situ in a single process. The morphology (coil diameter, coil pitch, and fibre diameter) and nitrogen content of the synthesized CNCs was individually adjusted by modulation of the catalyst composition and CVD reaction temperature, respectively. The adjustable ranges of the coil diameter, coil pitch, fibre diameter, and nitrogen content were confirmed to be approximately 500±100 nm, 600±100 nm, 100±20 nm, and 1.1±0.3 atom%, respectively

    Fragmentation of the Primordial Gas Clouds and the Lower Limit on the Mass of the First Stars

    Get PDF
    We discuss the fragmentation of primordial gas clouds in the universe after decoupling. Comparing the time scale of collapse with that of fragmentation, we obtain the typical mass of a fragment both numerically and analytically. It is shown that the estimated mass gives the minimum mass of a fragment which is formed from the primordial gas cloud and is essentially determined by the Chandrasekhar mass.Comment: Astrophysical Journal Letters, in press (accepted 4 Oct 1996), 10 pages, Latex, 1 fi

    Spatial resolved high-energy particle diagnostic system using time-of-flight neutral particle analyzer in Large Helical Device

    Get PDF
    The time-of-flight-type neutral particle analyzer has an ability of horizontal scanning from 40 to 100° of the pitch angle. The information from the spatially resolved energy spectrum gives not only the ion temperature but also the information of the particle confinement and the electric field in plasmas. We have been studying the energy distributions at various magnetic configurations in the neutral beam injection (NBI) plasma. The spatially resolved energy spectra can be observed during long discharges of the NBI plasma by continuous scanning of the neutral particle analyzer. The shape of spectra is almost similar from 44° to 53°. However, the spectra from 55° are strongly varied. They reflect the injection pitch angle of the beam. The pitch angle scanning experiment during the long discharge of NBI plasma has also been made under the reversal of the magnetic field direction. NBI2 becomes counter injected with the reversal. We can easily observe the difference between co- and counter injections of NBI. During the electron cyclotron heating in the low-density plasma for the formation of the internal thermal barrier, large neutral particle increase or decease can be observed. The degree of the increase/decrease depends on the energy and the density. The reason for the variation of the particle flux is that the orbit of the trapped particle changes due to the electric field formed by the strong electron cyclotron heating

    Quasi-Drugs Developed in Japan for the Prevention or Treatment of Hyperpigmentary Disorders

    Get PDF
    Excess production of melanin or its abnormal distribution, or both, can cause irregular hyperpigmentation of the skin, leading to melasma and age spots. To date, various quasi-drugs that prevent or improve hyperpigmentary disorders have been developed and officially approved by the Ministry of Health, Labor and Welfare of Japan. Many of these inhibit the activity of tyrosinase, an enzyme required for melanin synthesis, for example, by competitive or non-competitive inhibition of its catalytic activity, by inhibiting its maturation, or by accelerating its degradation. In this review, we categorize the quasi-drugs developed in Japan to prevent or treat hyperpigmentary disorders, or both, and discuss perspectives for future development

    Applicability of radiocolloids, blue dyes and fluorescent indocyanine green to sentinel node biopsy in melanoma

    Get PDF
    Patients with primary cutaneous melanoma underwent sentinel node (SN) mapping and biopsy at 25 facilities in Japan by the combination of radiocolloid with gamma probe and dye. Technetium-99m (99mTc)-tin colloid, 99mTc-phytate, 2% patent blue violet (PBV) and 0.4% indigo carmine were used as tracers. In some hospitals, 0.5% fluorescent indocyanine green, which allows visualization of the SN with an infrared camera, was concomitantly used and examined. A total of 673 patients were enrolled, and 562 cases were eligible. The detection rates of SN were 95.5% (147/154) with the combination of tin colloid and PBV, 98.9% (368/372) with the combination of phytate and PBV, and 97.2% (35/36) with the combination of tin colloid or phytate and indigo carmine. SN was not detected in 12 cases by the combination method, and the primary tumor was in the head and neck in six of those 12 cases. In eight of 526 cases (1.5%), SN was detected by PBV but not by radiocolloid. There were 13 cases (2.5%) in which SN was detected by radiocolloid but not by PBV. In 18 of 36 cases (50%), SN was detected by radiocolloid but not by indigo carmine. Concomitantly used fluorescent indocyanine green detected SN in all of 67 cases. Interference with transcutaneous oximetry by PVB was observed in some cases, although it caused no clinical trouble. Allergic reactions were not reported with any of the tracers. 99mTc-tin colloid, 99mTc-phytate, PBV and indocyanine green are useful tracers for SN mapping.ArticleJOURNAL OF DERMATOLOGY. 39(4):336-338 (2012)journal articl
    corecore