86 research outputs found
GROUPING AND NUMERIC CONVERTION AS WAY TO BOOST PERFORMANCE
The purpose of this study was to suggest that the way to boost physical education performance in elementary school by “grouping” and “numeric conversion” on physical
education. In this study, 40m-hurdles and running long jump were selected as educational materials. 15 elementary school students were divided into 3 groups. Baselines were determined for each individual. Students practice in a group, with the measurement records being carried out in the P.E. class and compared against those for other groups. This way shows their goal and growth as relative numerical values. By
keeping score collaboratively, students acquired new perspective when observing others. In addition, they took know-how or facture of movement into their hearts
Strong covalent bonding between two graphene layers
We show that two graphene layers stacked directly on top of each other (AA
stacking) form strong chemical bonds when the distance between planes is 0.156
nm. Simultaneously, C-C in-plane bonds are considerably weakened from partial
double-bond (0.141 nm) to single bond (0.154 nm). This polymorphic form of
graphene bilayer is meta-stable w.r.t. the one bound by van der Waals forces at
a larger separation (0.335 nm) with an activation energy of 0.16 eV/cell.
Similarly to the structure found in hexaprismane, C forms four single bonds in
a geometry mixing 90^{0} and 120^{0} angles. Intermediate separations between
layers can be stabilized under external anisotropic stresses showing a rich
electronic structure changing from semimetal at van der Waals distance, to
metal when compressed, to wide gap semiconductor at the meta-stable minimum.Comment: tar gzip latex 4 pages 4 figure
Fermi surfaces of single layer dielectrics on transition metals
Single sheets of hexagonal boron nitride on transition metals provide a model
system for single layer dielectrics. The progress in the understanding of h-BN
layers on transition metals of the last 10 years are shortly reviewed.
Particular emphasis lies on the boron nitride nanomesh on Rh(111), which is a
corrugated single sheet of h-BN, where the corrugation imposes strong lateral
electric fields. Fermi surface maps of h-BN/Rh(111) and Rh(111) are compared. A
h-BN layer on Rh(111) introduces no new bands at the Fermi energy, which is
expected for an insulator. The lateral electric fields of h-BN nanomesh violate
the conservation law for parallel momentum in photoemission and smear out the
momentum distribution curves on the Fermi surface.Comment: 14 pages, 6 figures, 1 table, 1 equation, Accepted for publication in
the Special Surface Science issue in honor of Gerhard Ertl's Nobel Priz
A hybrid MBE-based growth method for large-area synthesis of stacked hexagonal boron nitride/graphene heterostructures
Van der Waals heterostructures combining hexagonal boron nitride (h-BN) and graphene offer many potential advantages, but remain difficult to produce as continuous films over large areas. In particular, the growth of h-BN on graphene has proven to be challenging due to the inertness of the graphene surface. Here we exploit a scalable molecular beam epitaxy based method to allow both the h-BN and graphene to form in a stacked heterostructure in the favorable growth environment provided by a Ni(111) substrate. This involves first saturating a Ni film on MgO(111) with C, growing h-BN on the exposed metal surface, and precipitating the C back to the h-BN/Ni interface to form graphene. The resulting laterally continuous heterostructure is composed of a top layer of few-layer thick h-BN on an intermediate few-layer thick graphene, lying on top of Ni/MgO(111). Examinations by synchrotron-based grazing incidence diffraction, X-ray photoemission spectroscopy, and UV-Raman spectroscopy reveal that while the h-BN is relaxed, the lattice constant of graphene is significantly reduced, likely due to nitrogen doping. These results illustrate a different pathway for the production of h-BN/graphene heterostructures, and open a new perspective for the large-area preparation of heterosystems combining graphene and other 2D or 3D materials
Vibrational properties of single-wall nanotubes and monolayers of hexagonal BN
We report a detailed study of the vibrational properties of BN single-walled
nanotubes and of the BN monolayer. Our results have been obtained from a
well-established Tight-Binding model complemented with an electrostatic model
to account for the long-range interactions arising from the polar nature of the
material, and which are not included in the Tight-Binding model. Our study
provides a wealth of data for the BN monolayer and nanotubes, such as phonon
band structure, vibrational density of states, elastic constants, etc. For the
nanotubes we obtain the behavior of the optically active modes as a function of
the structural parameters, and we compare their frequencies with those derived
from a zone-folding treatment applied to the phonon frequencies of the BN
monolayer, finding general good agreement between the two.Comment: 14 pages with 10 postscript figures, to appear in PRB, January 15th
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Study on phonons in lanthanum hexaboride surfaces and monolayer h-BN films
制度:新 ; 文部省報告番号:甲1372号 ; 学位の種類:博士(理学) ; 授与年月日:1999-03-15 ; 早大学位記番号:新2810 ; 理工学図書館請求番号:2355早稲田大
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