404 research outputs found
Structural investigation on GexSb10Se90âx glasses using x-ray photoelectron spectra
The structure of GeâSbââSeââËâ glasses (xâ=â7.5, 10, 15, 20, 25, 27.5, 30, and 32.5 at. %) has been investigated by x-ray photoelectron spectroscopy (XPS). Different structural units have been extracted and characterized by decomposing XPS core level spectra, the evolution of the relative concentration of each structural unit indicates that, the relative contributions of Se-trimers and Se-Se-Ge(Sb) structure decrease with increasing Ge content until they become zero at chemically stoichiometric glasses of Geââ
SbââSeââ
, and then the homopolar bonds like Ge-Ge and Sb-Sb begin to appear in the spectra. Increase of homopolar bonds will extend band-tails into the gap and narrow the optical band gap. Thus, the glass with a stoichiometric composition generally has fewer defective bonds and larger optical bandgap
The `excess' of primary cosmic ray electrons
With the accurate cosmic ray (CR) electron and positron spectra (denoted as
and , respectively) measured by AMS-02
collaboration, the difference between the electron and positron fluxes (i.e.,
), dominated by the propagated
primary electrons, can be reliably inferred. In the standard model, the
spectrum of propagated primary CR electrons at energies GeV softens
with the increase of energy. The absence of any evidence for such a continuous
spectral softening in strongly suggests a significant `excess' of
primary CR electrons and at energies of GeV the identified excess
component has a flux comparable to that of the observed positron excess.
Middle-age but `nearby' supernova remnants (e.g., Monogem and Geminga) are
favored sources for such an excess.Comment: 13 pages, 2 figures, Phys. Lett. B, in pres
Coordination of carbon assimilation, allocation, and utilization for systemic improvement of cereal yield
The growth of yield outputs is dwindling after the first green revolution, which cannot meet the demand for the projected population increase by the mid-century, especially with the constant threat from extreme climates. Cereal yield requires carbon (C) assimilation in the source for subsequent allocation and utilization in the sink. However, whether the source or sink limits yield improvement, a crucial question for strategic orientation in future breeding and cultivation, is still under debate. To narrow the knowledge gap and capture the progress, we focus on maize, rice, and wheat by briefly reviewing recent advances in yield improvement by modulation of i) leaf photosynthesis; ii) primary C allocation, phloem loading, and unloading; iii) C utilization and grain storage; and iv) systemic sugar signals (e.g., trehalose 6-phosphate). We highlight strategies for optimizing C allocation and utilization to coordinate the sourceâsink relationships and promote yields. Finally, based on the understanding of these physiological mechanisms, we envisage a future scenery of âsmart cropâ consisting of flexible coordination of plant C economy, with the goal of yield improvement and resilience in the field population of cereals crops
Magnetic Properties of YBa_2Cu_3O_{7-\delta} in a self-consistent approach: Comparison with Quantum-Monte-Carlo Simulations and Experiments
We analyze single-particle electronic and two-particle magnetic properties of
the Hubbard model in the underdoped and optimally-doped regime of \YBCO by
means of a modified version of the fluctuation-exchange approximation, which
only includes particle-hole fluctuations. Comparison of our results with
Quantum-Monte Carlo (QMC) calculations at relatively high temperatures () suggests to introduce a temperature renormalization in order to
improve the agreement between the two methods at intermediate and large values
of the interaction .
We evaluate the temperature dependence of the spin-lattice relaxation time
and of the spin-echo decay time and compare it with the results
of NMR measurements on an underdoped and an optimally doped \YBCO sample. For
it is possible to consistently adjust the parameters of the Hubbard
model in order to have a good {\it semi-quantitative} description of this
temperature dependence for temperatures larger than the spin gap as obtained
from NMR measurements. We also discuss the case , which is more
appropriate to describe magnetic and single-particle properties close to
half-filling. However, for this larger value of the agreement with QMC as
well as with experiments at finite doping is less satisfactory.Comment: Final version, to appear in Phys. Rev. B (sched. Feb. 99
Aptamer–drug conjugate: targeted delivery of doxorubicin in a HER3 aptamer-functionalized liposomal delivery system reduces cardiotoxicity
Boosting Superior Lithium Storage Performance of AlloyâBased Anode Materials via Ultraconformal Sb CoatingâDerived Favorable SolidâElectrolyte Interphase
Alloy materials such as Si and Ge are attractive as highâcapacity anodes for rechargeable batteries, but such anodes undergo severe capacity degradation during dischargeâcharge processes. Compared to the overâemphasized efforts on the electrode structure design to mitigate the volume changes, understanding and engineering of the solidâelectrolyte interphase (SEI) are significantly lacking. This work demonstrates that modifying the surface of alloyâbased anode materials by building an ultraconformal layer of Sb can significantly enhance their structural and interfacial stability during cycling. Combined experimental and theoretical studies consistently reveal that the ultraconformal Sb layer is dynamically converted to Li3Sb during cycling, which can selectively adsorb and catalytically decompose electrolyte additives to form a robust, thin, and dense LiFâdominated SEI, and simultaneously restrain the decomposition of electrolyte solvents. Hence, the Sbâcoated porous Ge electrode delivers much higher initial Coulombic efficiency of 85% and higher reversible capacity of 1046 mAh gâ1 after 200 cycles at 500 mA gâ1, compared to only 72% and 170 mAh gâ1 for bare porous Ge. The present finding has indicated that tailoring surface structures of electrode materials is an appealing approach to construct a robust SEI and achieve longâterm cycling stability for alloyâbased anode materials
Laboratory observation of ion acceleration via reflection off laser-produced magnetized collisionless shocks
Fermi acceleration by collisionless shocks is believed to be the primary
mechanism to produce high energy charged particles in the Universe,where
charged particles gain energy successively from multiple reflections off the
shock front.Here,we present the first direct experimental evidence of ion
energization from reflection off a supercritical quasi perpendicular
collisionless shock,an essential component of Fermi acceleration in a laser
produced magnetized plasma. We observed a quasi monoenergetic ion beam with 2,4
times the shock velocity in the upstream flow using time of flight method. Our
related kinetic simulations reproduced the energy gain and showed that these
ions were first reflected and then accelerated mainly by the motional electric
field associated with the shock. This mechanism can also explain the quasi
monoenergetic fast ion component observed in the Earth's bow shock
Clinical Use of Mood Stabilizers With Antidepressants in Asia Report From the Research on Asian Psychotropic Prescription Patterns for Antidepressants (REAP-AD) Projects in 2004 and 2013
Abstract
Objective: As most reports concerning treatment with combinations of mood stabilizer (MS) with antidepressant (AD) drugs are based in the West, we surveyed characteristics of such cotreatment in 42 sites caring for the mentally ill in 10 Asian countries.
Methods: This cross-sectional, pharmacoepidemiologic study used 2004 and 2013 data from the REAP-AD (Research Study on Asian Psychotropic Prescription Patterns for Antidepressants) to evaluate the rates and doses of MSs given with ADs and associated factors in 4164 psychiatric patients, using standard bivariate methods followed by multivariable logistic regression modeling.
Results: Use of MS + AD increased by 104% (5.5% to 11.2%) between 2004 and 2013 and was much more associated with diagnosis of bipolar disorder than major depression or anxiety disorder, as well as with hospitalization > outpatient care, psychiatric > general-medical programs, and young age (all P < 0.001), but not with country, sex, or AD dose.
Conclusions: The findings provide a broad picture of contemporary use of MSs with ADs in Asia, support predictions that such treatment increased in recent years, and was associated with diagnosis of bipolar disorder, treatment in inpatient and psychiatric settings, and younger age
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