1,367 research outputs found
EFFECTS OF FATIGUE ON THE GROUND REACTION FORCES AND LEG KINEMATICS IN ALL-OUT 600 METERS RUNNING
The purpose of this study was to investigate effects of fatigue on the ground reaction forces and leg kinematics during all-out 600m running, which was performed by eight male middle-distance runners. Their running motion was videotaped (300Hz) and the ground reaction forces were measured (500Hz) at the 150m and 550m marks of the 600m running. From the 150m to 550m mark, running speed significantly decreased (
Superfluidity of He Confined in Nano-Porous Media
We have examined superfluid properties of He confined to a nano-porous
Gelsil glass that has nanopores 2.5 nm in diameter. The pressure-temperature
phase diagram was determined by torsional oscillator, heat capacity and
pressure studies. The superfluid transition temperature
approaches zero at 3.4 MPa, indicating a novel "quantum" superfluid transition.
By heat capacity measurements, the nonsuperfluid phase adjacent to the
superfluid and solid phases is identified to be a nanometer-scale, localized
Bose condensation state, in which global phase coherence is destroyed. At high
pressures, the superfluid density has a -linear term, and is
proportional to the zero-temperature superfluid density. These results strongly
suggest that phase fluctuations in the superfluid order parameter play a
dominant role on the phase diagram and superfluid properties.Comment: 6 Pages, 6 Figures, Submitted to "Helium: 100 years", Special Issue
of Low Temperature Physic
Mekanisme Pelindian PT, Pd dan Rh dari Limbah Katalis Otomotif dalam Sistem Larutan Naclo-hcl-h
MEKANISME PELINDIAN Pt, Pd DAN Rh DARI LIMBAH KATALIS OTOMOTIF DALAM SISTEM LARUTAN NaClO-HCl-H2O2. Kelompok Logam Platinum, KLP (Platinum Group Metals, PGM) merupakan logam mulia penting dalam aplikasi berbagai industri. Oleh karena itu proses daur ulang (recycling) dan perolehan kembali (recovery) logam ini dari sumber sekunder menjadi penting akibat keterbatasan cadangan logam mulia dari cadangan primer (bijih). Untuk memperoleh kembali KLP ini, proses hidrometalurgi berupa pelindian (leaching) dipandang sangat handal. Kajian ini dilakukan untuk mendaur ulang dan memperoleh kembali KLP, seperti platinum (Pt) paladium (Pd) dan rhodium (Rh) dari limbah produksi konverter katalis dengan proses pelindian menggunakan campuran larutan NaClO-HCl-H2O2. Cuplikan limbah konverter katalis, yang sebelumnya telah di giling dan direduksi dengan gas hidrogen, dilindi dengan campuran larutan NaClO-HCl- H2O2 pada 338 K selama 3 jam. Pengaruh beberapa parameter pelindian diamati pula selama proses. Dari pengujian dihasilkan kondisi optimum pelindian Pt, Pd dan Rh pada konsentrasi 3 %(vol) NaClO, 5 M HCl dan penambahan 1 %( vol) H2O2. Perolehan kembali Pt, Pd dan Rh setelah 3 jam pelindian secara berurutan adalah 88%, 99% dan 77%. Mekanisme reaksi pelindian akan dibahas dalam publikasi ini dengan mengamati kinetika reaksinya. Diamati dari hasil pengujian dan perhitungan bahwa mekanisme reaksi pelindian KPL dalam campuran larutan NaClO-HCl-H2O2 adalah mekanisme yang dikontrol oleh difusi (diffusion controlled mechanism)
Trends in antimicrobial-drug resistance in Japan.
Multidrug resistance in gram-positive bacteria has become common worldwide. In Japan until recently, gram-negative bacteria such as Pseudomonas aeruginosa, Klebsiella pneumoniae, and Serratia marcescens were controlled by carbapenems, fluoroquinolones, and aminoglycosides. However, several of these microorganisms have recently developed resistance against many antimicrobial drugs
Electronic Properties of Topological Materials: Optical Excitations in Moebius Conjugated Polymers
Electronic structures and optical excitations in Moebius conjugated polymers
are studied theoretically. Periodic and Moebius boundary conditions are applied
to the tight binding model of poly(para-phenylene), taking exciton effects into
account. We discuss that oligomers with a few structural units are more
effective than polymers for observations of effects of discrete wave numbers
that are shifted by the change in boundary condition. Next, calculations of
optical absorption spectra are reported. Certain components of optical
absorption for an electric field perpendicular to the polymer axis mix with
absorption spectra for an electric field parallel to the polymer axis.
Therefore, the polarization dependences of an electric field of light enable us
to detect whether conjugated polymers have the Moebius boundary.Comment: 10 pages, 6 figures, to be published in J. Phys. Soc. Jpn., Vol. 74
No. 2 (February, 2005), Letter sectio
Quantum dislocations: the fate of multiple vacancies in two dimensional solid 4He
Defects are believed to play a fundamental role in the supersolid state of
4He. We have studied solid 4He in two dimensions (2D) as function of the number
of vacancies n_v, up to 30, inserted in the initial configuration at rho =
0.0765 A^-2, close to the melting density, with the exact zero temperature
Shadow Path Integral Ground State method. The crystalline order is found to be
stable also in presence of many vacancies and we observe two completely
different regimes. For small n_v, up to about 6, vacancies form a bound state
and cause a decrease of the crystalline order. At larger n_v, the formation
energy of an extra vacancy at fixed density decreases by one order of magnitude
to about 0.6 K. In the equilibrated state it is no more possible to recognize
vacancies because they mainly transform into quantum dislocations and
crystalline order is found almost independent on how many vacancies have been
inserted in the initial configuration. The one--body density matrix in this
latter regime shows a non decaying large distance tail: dislocations, that in
2D are point defects, turn out to be mobile, their number is fluctuating, and
they are able to induce exchanges of particles across the system mainly
triggered by the dislocation cores. These results indicate that the notion of
incommensurate versus commensurate state loses meaning for solid 4He in 2D,
because the number of lattice sites becomes ill defined when the system is not
commensurate. Crystalline order is found to be stable also in 3D in presence of
up to 100 vacancies
Superfluidity of ⁴He confined in nanoporous media
We have examined superfluid properties of ⁴He confined to a nanoporous Gelsil glass that has nanopores
2.5 nm in diameter. The pressure–temperature phase diagram was determined by torsional oscillator, heat
capacity and pressure studies. The superfluid transition temperature Tc approaches zero at 3.4 MPa, indicating
a novel quantum superfluid transition. By heat capacity measurements, the nonsuperfluid phase adjacent
to the superfluid and solid phases is identified to be a nanometer-scale, localized Bose condensation state, in
which global phase coherence is destroyed. At high pressures, the superfluid density has a T-linear term, and
Tc is proportional to the zero-temperature superfluid density. These results strongly suggest that phase fluctuations
in the superfluid order parameter play a dominant role on the phase diagram and superfluid properties
Nonmagnetic-Defect-Induced Magnetism in Graphene
It is shown that a strong impurity potential induces short-range
antiferromagnetic (ferrimagnetic) order around itself in a Hubbard model on a
half-filled honeycomb lattice. This implies that short-range magnetic order is
induced in monolayer graphene by a nonmagnetic defect such as a vacancy with
full hydrogen termination or a chemisorption defect.Comment: 5 pages, 8 figure
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