944 research outputs found
When primordial black holes from sound speed resonance meet a stochastic background of gravitational waves
Theoretical Physic
Combining nano-silicon with oxide glass in anodes for Li-ion batteries
Vanadium-tellurite glasses (VT) have emerged as promising anode materials for lithium-ion batteries (LIBs). Despite this, the Li-ion storage capacity of the VT glass anode is still insufficient to meet the demands for the next generation of advanced LIBs. Silicon (Si) anode has ultrahigh theoretical capacity but suffers from significant volume expansion during lithiation and delithiation. In this work, we combined Si nanoparticles with VT glass to prepare Si@VT composite anode for LIBs. The composite was produced through heat-treatment at different temperatures, some of which were hot-pressed under the isostatic pressure of 100 MPa. The Si@VT composite exhibited a synergistic effect that integrated the strengths of both VT glass and Si, resulting in a substantial enhancement of its electrochemical performance. The systematic characterizations of the composite-based anodes revealed the optimal conditions for fabricating the high-performance Si@VT composite: a silicon fraction of 10 wt% and a hot-pressing temperature of 620 K. This composite stood out as the optimal choice, exhibiting a capacity of 353 mA h g−1 at 1 A g−1 after 1000 cycles. This capacity surpasses that of VT glass anode by over threefold and that of pure Si anode by twelvefold.</p
Magnetotransport Mechanisms in Strongly Underdoped YBa_2Cu_3O_x Single Crystals
We report magnetoresistivity measurements on strongly underdoped YBa_2Cu_3O_x
(x=6.25, 6.36) single crystals in applied magnetic fields H || c-axis. We
identify two different contributions to both in-plane and out-of-plane
magnetoresistivities. The first contribution has the same sign as the
temperature coefficient of the resistivity \partial ln(\rho_i)/\partial T
(i={c,ab}). This contribution reflects the incoherent nature of the
out-of-plane transport. The second contribution is positive, quadratic in
field, with an onset temperature that correlates to the antiferromagnetic
ordering.Comment: 4 pages, 3 figure
Indications of coherence-incoherence crossover in layered transport
For many layered metals the temperature dependence of the interlayer
resistance has a different behavior than the intralayer resistance. In order to
better understand interlayer transport we consider a concrete model which
exhibits this behavior. A small polaron model is used to illustrate how the
interlayer transport is related to the coherence of quasi-particles within the
layers. Explicit results are given for the electron spectral function,
interlayer optical conductivity and the interlayer magnetoresistance. All these
quantities have two contributions: one coherent (dominant at low temperatures)
and one incoherent (dominant at high temperatures).Comment: 6 pages, 4 figures, REVTEX
Novel D-hordein-like HMW glutenin sequences isolated from Psathyrostachys juncea by thermal asymmetric interlaced PCR
New high-molecular-weight glutenin (HMW glutenin) sequences isolated from six Psathyrostachys juncea accessions by thermal asymmetric interlaced PCR differ from previous sequences from this species. They showed novel modifications in all of the structural domains, with unique C-terminal residues, and their N-terminal lengths were the longest among the HMW glutenins reported to date. In their repetitive domains, there were three repeatable motif units: 13-residue [GYWH(/I/Y)YT(/Q)S(/T)VTSPQQ], hexapeptide (PGQGQQ), and tetrapeptide (ITVS). The 13-residue repeats were restricted to the current sequences, while the tetrapeptides were only shared by D-hordein and the current sequences. However, these sequences were not expressed as normal HMW glutenin proteins because an in-frame stop codon located in the C-termini interrupted the intact open reading frames. A phylogenetic analysis supported different origins of the P. juncea HMW glutenin sequences than that revealed by a previous study. The current sequences showed a close relationship with D-hordein but appeared to be more primitive
A new method to determine the mixing state of light absorbing carbonaceous using the measured aerosol optical properties and number size distributions
In this paper, the mixing state of light absorbing carbonaceous (LAC) was investigated with a two-parameter aerosol optical model and in situ aerosol measurements at a regional site in the North China Plain (NCP). A closure study between the hemispheric backscattering fraction (HBF) measured by an integrating nephelometer and that calculated with a modified Mie model was conducted. A new method was proposed to retrieve the ratio of the externally mixed LAC mass to the total mass of LAC (rext-LAC) based on the assumption that the ambient aerosol particles were externally mixed and consisted of a pure LAC material and a core-shell morphology in which the core is LAC and the shell is a less absorbing material. A Monte Carlo simulation was applied to estimate the overall influences of input parameters of the algorithm to the retrieved rext-LAC. The diurnal variation of rext-LAC was analyzed and the PartMC-MOSAIC model was used to simulate the variation of the aerosol mixing state. Results show that, for internally mixed particles, the assumption of core-shell mixture is more appropriate than that of homogenous mixture which has been widely used in aerosol optical calculations. A significant diurnal pattern of the retrieved rext-LAC was found, with high values during the daytime and low values at night. The consistency between the retrieved rext-LAC and the model results indicates that the diurnal variation of LAC mixing state is mainly caused by the diurnal evolution of the mixing layer
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Aerosol optical properties in the North China Plain during HaChi campaign: An in-situ optical closure study
The largest uncertainty in the estimation of climate forcing stems from atmospheric aerosols. In early spring and summer of 2009, two periods of in-situ measurements on aerosol physical and chemical properties were conducted within the HaChi (Haze in China) project at Wuqing, a town between Beijing and Tianjin in the North China Plain (NCP). Aerosol optical properties, including the scattering coefficient (σsp), the hemispheric back scattering coefficient (σbsp), the absorption coefficient (σap), as well as the single scattering albedo (ω), are presented. The diurnal and seasonal variations are analyzed together with meteorology and satellite data. The mean values of σsp, 550 nm of the dry aerosol in spring and summer are 280±253 and 379±251 Mm−1, respectively. The average σap for the two periods is respectively 47±38 and 43±27 Mm−1. The mean values of ω at the wavelength of 637 nm are 0.82±0.05 and 0.86±0.05 for spring and summer, respectively. The relative high levels of σsp and σbsp are representative of the regional aerosol pollution in the NCP. Pronounced diurnal cycle of $σsp, σap and ω are found, mainly influenced by the evolution of boundary layer and the accumulation of local emissions during nighttime. The pollutants transported from the southwest of the NCP are more significant than that from the two megacities, Beijing and Tianjin, in both spring and summer. An optical closure experiment is conducted to better understand the uncertainties of the measurements. Good correlations (R>0.98) are found between the values measured by the nephelometer and the values calculated with a modified Mie model. The Monte Carlo simulation shows an uncertainty of about 30 % for the calculations. Considering all possible uncertainties of measurements, calculated σsp and σbsp agree well with the measured values, indicating a stable performance of instruments and thus reliable aerosol optical data
Measurements of the observed cross sections for exclusive light hadrons containing at , 3.650 and 3.6648 GeV
By analyzing the data sets of 17.3, 6.5 and 1.0 pb taken,
respectively, at , 3.650 and 3.6648 GeV with the BES-II
detector at the BEPC collider, we measure the observed cross sections for
, , ,
and at the three energy
points. Based on these cross sections we set the upper limits on the observed
cross sections and the branching fractions for decay into these
final states at 90% C.L..Comment: 7 pages, 2 figure
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