5,039 research outputs found
Phonon Softening and Direct to Indirect Bandgap Crossover in Strained Single Layer MoSe2
Motivated by recent experimental observations of Tongay et al. [Tongay et
al., Nano Letters, 12(11), 5576 (2012)] we show how the electronic properties
and Raman characteristics of single layer MoSe2 are affected by elastic biaxial
strain. We found that with increasing strain: (1) the E' and E" Raman peaks
(E1g and E2g in bulk) exhibit significant red shifts (up to 30 cm-1), (2) the
position of the A1' peak remains at 180 cm-1 (A1g in bulk) and does not change
considerably with further strain, (3) the dispersion of low energy flexural
phonons crosses over from quadratic to linear and (4) the electronic band
structure undergoes a direct to indirect bandgap crossover under 3% biaxial
tensile strain. Thus the application of strain appears to be a promising
approach for a rapid and reversible tuning of the electronic, vibrational and
optical properties of single layer MoSe2 and similar MX2 dichalcogenides.Comment: http://link.aps.org/doi/10.1103/PhysRevB.87.12541
A novel index in healthy infants and children — subarachnoid space: ventricle ratio
Background: The subarachnoid space (SAS) and ventricular width (VW) in normalinfants and children were studied with ultrasonography to provide the objectivemeasurement and define a normal range for these measurements. The additional aim was to determine the stable ratio as a SAS/VW.Materials and methods: A total of 100 healthy subjects, including 48 males and52 females, were studied. The cases were divided into 3 age groups: 0–6 months(n = 65), 7–12 months (n = 24) and > 13 months (n = 11). Transfontanel ultrasonography was performed in all the cases. SAS, VW and the SAS/VW ratios were calculated. The study was approved by the ethical committee. All parents wereinformed about the sonographic examination and their approvals were taken.Results: SAS was calculated as 3.1 (0.5–6) mm and VW was calculated as 3.6(1.3–5) mm. SAS/VW ratio was 0.9 ± 0.3. There was no statistically significant difference among SAS, VW and SAS/VW ratios in 3–97 percentile group (p > 0.05).Conclusions: Ultrasonography can be used as a practicable and reproducible modalityin the measurement of SAS and VW in healthy children. It is a non-invasivemethod and allows for serial follow-up. SAS/VW ratio can be used as an index inhealthy children
EXPERIMENTAL STUDIES OF SOLUBILITY OF ELEMENTAL SULPHUR IN SUPERCRITICAL CARBON DIOXIDE BETWEEN 10 AND 40 MPA
International audienc
Energy-loss magnetic chiral dichroism (EMCD): Magnetic chiral dichroism in the electron microscope
A new technique called energy-loss magnetic chiral dichroism (EMCD) has recently been developed [P. Schattschneider, et al. Nature 441, 486 (2006)] to measure magnetic circular dichroism in the transmission electron microscope (TEM) with a spatial resolution of 10 nm. This novel technique is the TEM counterpart of x-ray magnetic circular dichroism, which is widely used for the characterization of magnetic materials with synchrotron radiation. In this paper we describe several experimental methods that can be used to measure the EMCD signal [P. Schattschneider, et al. Nature 441, 486 (2006); C. Hébert, et al. Ultramicroscopy 108(3), 277 (2008); B. Warot-Fonrose, et al. Ultramicroscopy 108(5), 393 (2008); L. Calmels, et al. Phys. Rev. B 76, 060409 (2007); P. van Aken, et al. Microsc. Microanal. 13(3), 426 (2007)] and give a review of the recent improvements of this new investigation tool. The dependence of the EMCD on several experimental conditions (such as thickness, relative orientation of beam and sample, collection and convergence angle) is investigated in the transition metals iron, cobalt, and nickel. Different scattering geometries are illustrated; their advantages and disadvantages are detailed, together with current limitations. The next realistic perspectives of this technique consist of measuring atomic specific magnetic moments, using suitable spin and orbital sum rules, [L. Calmels, et al. Phys. Rev. B 76, 060409 (2007); J. Rusz, et al. Phys. Rev. B 76, 060408 (2007)] with a resolution down to 2 to 3 n
Measurement of Neutrino-Electron Scattering Cross-Section with a CsI(Tl) Scintillating Crystal Array at the Kuo-Sheng Nuclear Power Reactor
The elastic scattering cross-section was measured with
a CsI(Tl) scintillating crystal array having a total mass of 187kg. The
detector was exposed to an average reactor flux of
at the Kuo-Sheng Nuclear Power
Station. The experimental design, conceptual merits, detector hardware, data
analysis and background understanding of the experiment are presented. Using
29882/7369 kg-days of Reactor ON/OFF data, the Standard Model(SM) electroweak
interaction was probed at the squared 4-momentum transfer range of . The ratio of experimental to SM cross-sections
of was measured. Constraints on
the electroweak parameters were placed, corresponding to a weak
mixing angle measurement of \s2tw = 0.251 \pm 0.031({\it stat}) \pm
0.024({\it sys}) . Destructive interference in the SM \nuebar -e process was
verified. Bounds on anomalous neutrino electromagnetic properties were placed:
neutrino magnetic moment at \mu_{\nuebar}< 2.2 \times 10^{-10} \mu_{\rm B}
and the neutrino charge radius at -2.1 \times 10^{-32} ~{\rm cm^{2}} <
\nuchrad < 3.3 \times 10^{-32} ~{\rm cm^{2}}, both at 90% confidence level.Comment: 18 Figures, 7 Tables; published version as V2 with minor revision
from V
Potential use of pepper waste and microalgae Spirulina sp. for bioelectricity generation
The research aimed to generate bioelectricity using pepper waste and the microalgae Spirulina sp by a double-chamber microbial fuel cell (dcMFC). A dcMFC was constructed with Cu and Zn electrodes, where organic waste and microalgae were placed in the anodic and cathodic chambers, respectively. Also, electrochemical parameters were measured for 35 days. Finally, possible electrogenic microorganisms were isolated and identified. It was possible to generate maximum values of current (6.04414 ± 0.2145 mA) and voltage (0.77328 ± 0.213 V). The maximum conductivity value was 134.1636 ± 7.121 mS/cm, while the internal resistance value was 83.784
. The values of power and current density reached were 584.45 ± 19.14 mW/cm 2 and 5.983 A/cm 2, respectively. The optimal operating pH was 4.59 ± 0.14. From the microbial growth on the anode, the yeast Yarrowia phangngaensis (1) and Pseudomonas stutzeri (2) were identified, which may be involved in the transfer of electrons to the electrode. In conclusion, it was possible to generate clean energy in a laboratory-scale dcMFC when pepper waste and Spirulina sp. were used. These results are promising because organic waste can generate sustainable and environmentally friendly energy
The Minimal Supersymmetric Standard Model: Group Summary Report
CONTENTS: 1. Synopsis, 2. The MSSM Spectrum, 3. The Physical Parameters, 4.
Higgs Boson Production and Decays, 5. SUSY Particle Production and Decays, 6.
Experimental Bounds on SUSY Particle Masses, 7. References.Comment: 121 pages, latex + epsfig, graphicx, axodraw, Report of the MSSM
working group for the Workshop "GDR-Supersym\'etrie",France. Rep. PM/98-4
Energy Linearity and Resolution of the ATLAS Electromagnetic Barrel Calorimeter in an Electron Test-Beam
A module of the ATLAS electromagnetic barrel liquid argon calorimeter was
exposed to the CERN electron test-beam at the H8 beam line upgraded for
precision momentum measurement. The available energies of the electron beam
ranged from 10 to 245 GeV. The electron beam impinged at one point
corresponding to a pseudo-rapidity of eta=0.687 and an azimuthal angle of
phi=0.28 in the ATLAS coordinate system. A detailed study of several effects
biasing the electron energy measurement allowed an energy reconstruction
procedure to be developed that ensures a good linearity and a good resolution.
Use is made of detailed Monte Carlo simulations based on Geant which describe
the longitudinal and transverse shower profiles as well as the energy
distributions. For electron energies between 15 GeV and 180 GeV the deviation
of the measured incident electron energy over the beam energy is within 0.1%.
The systematic uncertainty of the measurement is about 0.1% at low energies and
negligible at high energies. The energy resolution is found to be about 10%
sqrt(E) for the sampling term and about 0.2% for the local constant term
Constraints on Non-Standard Neutrino Interactions and Unparticle Physics with Neutrino-Electron Scattering at the Kuo-Sheng Nuclear Power Reactor
Neutrino-electron scatterings are purely leptonic processes with robust
Standard Model (SM) predictions. Their measurements can therefore provide
constraints to physics beyond SM. The \nuebar-e data taken at the Kuo-Sheng
Reactor Neutrino Laboratory were used to probe two scenarios: Non-Standard
Neutrino Interactions (NSI) and Unparticle Physics. New constraints were placed
to the NSI parameters (\el,\er) and (\etl,\etr) for the Non-Universal
and Flavor-Changing channels, respectively, as well as to the coupling
constants for scalar () and vector () unparticles to the
neutrinos and electrons.Comment: 8 pages, 6 figures, 1 table ; Published Version in V2 with minor
revision
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