31,351 research outputs found
Interfacial Issues and Modification of Solid Electrolyte Interphase for Li Metal Anode in Liquid and Solid Electrolytes
The high energy density required for the next generation of lithium batteries will likely be enabled by a shift toward lithium metal anode from the conventional intercalation-based anode such as graphite. However, several critical challenges for Li metal originate from its highly reactive nature and the hostless reaction of deposition and stripping impede the practical use of Li metal as an anode. The role of the solid electrolyte interphase (SEI) is very important for the Li metal anode where the SEI must protect the dynamically changing surface of the Li metal. Since the SEI-generating reaction mechanisms for the two different electrolyte systems, liquid and solid, are considerably different, the SEI layers formed between the Li metal and the electrolytes in the two electrolyte systems have substantially different properties, causing different interfacial issues. Inhibition of the interfacial problems requires different strategies to reinforce the SEI layer for each of the electrolyte systems. However, the differences in the two electrolyte systems have not been clearly compared in the prior literature. In this report, the interfacial issues for the two different electrolyte systems are compared and different strategies for SEI modification are provided to overcome the issues
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Gender-based differences in letters of recommendation written for ophthalmology residency applicants.
BACKGROUND:To determine whether gender-based differences may be present in letters of recommendation written for ophthalmology residency applicants. METHODS:All applications submitted through SF Match to the UCLA Stein Eye Institute Residency Training Program from the 2017-2018 application cycle were analyzed using validated text analysis software (Linguistic Inquiry and Word Count (Austin, TX)). The main outcome measures were differences in language use in letters of recommendation by gender of applicant. RESULTS:Of 440 applicants, 254 (58%) were male and 186 (42%) were female. The two gender groups had similar United States Medical Licensing Exam (USMLE) Step 1 scores, undergraduate grade point averages (uGPA's), proportions of underrepresented minority (URM) applicants and Gold Humanism Honor Society members, numbers of academic and service activities listed, and gender distributions of their letter writers (all P values > 0.05). However, letters written for male applicants were determined to use more "authentic" words than those written for female applicants (mean difference, 0.800; 95% CI, 0.001-1.590; P = 0.047). Letters written for male applicants also contained more "leisure" words (mean difference, 0.056; 95% CI, 0.008-0.104; P = 0.023) and fewer "feel" words (mean difference, 0.033; 95% CI, 0.001-0.065; P = 0.041) and "biological processes" words (mean difference, 0.157; 95% CI, 0.017-0.297; P = 0.028). CONCLUSIONS:There were gender differences detected in recommendation letters in ophthalmology consistent with prior studies from other fields. Awareness of these differences may improve residency selection processes
A Labelling Scheme for Higher Dimensional Simplex Equations
We present a succinct way of obtaining all possible higher dimensional
generalization of Quantum Yang-Baxter Equation (QYBE). Using the scheme, we
could generate the two popular three-simplex equations, namely: Zamolodchikov's
tetrahedron equation (ZTE) and Frenkel and Moore equation (FME).Comment: To appear as a Letter to the Editor in J. Phys. A:Math and Ge
Perspective - Structure and Stability of the Solid Electrolyte Interphase on Silicon Anodes of Lithium-ion Batteries
The solid electrolyte interphase (SEI) acts as a protection layer on the surface the anodes of lithium ion batteries to prevent further electrolyte decomposition. Understanding the fundamental properties of the SEI is essential to the development of high capacity silicon anodes. However, the detailed mechanism of the generation of the evolution of the SEI on the silicon anodes is not fully understood. This manuscript reviews our recent investigations of the SEI on silicon anodes. We have studied the fundamental formation mechanism of the SEI on silicon anodes, along with the evolution which occurs to the SEI upon cycling
Landau diamagnetism and magnetization of interacting diffusive conductors
We show how the orbital magnetization of an interacting disordered diffusive
electron gas can be simply related to the magnetization of the non-interacting
system having the same geometry. This result is applied to the persistent
current of a mesoscopic ring and to the relation between Landau diamagnetism
and the interaction correction to the magnetization of diffusive systems. The
field dependence of this interaction contribution can be deduced directly from
the de Haas-van Alphen oscillations of the free electron gas. Known results for
the free orbital magnetism of finite systems can be used to derive the
interaction contribution in the diffusive regime in various geometries.Comment: 4 pages, 2 figure
Quantum Mechanics as a Framework for Dealing with Uncertainty
Quantum uncertainty is described here in two guises: indeterminacy with its
concomitant indeterminism of measurement outcomes, and fuzziness, or
unsharpness. Both features were long seen as obstructions of experimental
possibilities that were available in the realm of classical physics. The birth
of quantum information science was due to the realization that such
obstructions can be turned into powerful resources. Here we review how the
utilization of quantum fuzziness makes room for a notion of approximate joint
measurement of noncommuting observables. We also show how from a classical
perspective quantum uncertainty is due to a limitation of measurability
reflected in a fuzzy event structure -- all quantum events are fundamentally
unsharp.Comment: Plenary Lecture, Central European Workshop on Quantum Optics, Turku
2009
Higher Derivative CP(N) Model and Quantization of the Induced Chern-Simons Term
We consider higher derivative CP(N) model in 2+1 dimensions with the
Wess-Zumino-Witten term and the topological current density squared term. We
quantize the theory by using the auxiliary gauge field formulation in the path
integral method and prove that the extended model remains renormalizable in the
large N limit. We find that the Maxwell-Chern-Simons theory is dynamically
induced in the large N effective action at a nontrivial UV fixed point. The
quantization of the Chern-Simons term is also discussed.Comment: 8 pages, no figure, a minor change in abstract, added Comments on the
quantization of the Chern-Simons term whose coefficient is also corrected,
and some references are added. Some typos are corrected. Added a new
paragraph checking the equivalence between (3) and (5), and a related
referenc
Performance Improvement of Lithium Metal Batteries Enabled By LiBF3CN as a New Electrolyte Additive
A newly synthesized electrolyte additive, lithium trifluoro(cyano) borate (LiBF3CN), has been investigated for electrochemical performance improvement of lithium metal batteries. The LiBF3CN has a structure where one fluorine atom of BF4− is substituted with a cyano group (−CN) prepared by the reaction of boron trifluoride etherate with lithium cyanide. The electrochemical performance in symmetric Li/Li cells and NCM523/Li cells is significantly improved upon the incorporation of LiBF3CN as an electrolyte additive into a carbonate-based electrolyte. Extensive characterization of the deposited lithium metal reveals that a thin (≈20 nm) and robust SEI composed of LiNxOy, Li3N and Li2O is formed by the reductive decomposition of the LiBF3CN additive, which plays an important role in decreasing the resistance and stabilizing lithium deposition/stripping. The insight into the substitution effect of a functional group obtained from this work provides guidance for the design of new electrolyte additives
As NMR of Ba(FeCo)As in High Magnetic Field
The superconducting state of an optimally doped single crystal of
Ba(FeCo)As was investigated by As NMR in high
magnetic fields from 6.4 T to 28 T. It was found that the Knight shift is least
affected by vortex supercurrents in high magnetic fields, T, revealing
slow, possibly higher order than linear, increase with temperature at , with . This is consistent with the
extended s-wave state with symmetry but the precise details of the gap
structure are harder to resolve. Measurements of the NMR spin-spin relaxation
time, , indicate a strong indirect exchange interaction at all
temperatures. Below the superconducting transition temperature vortex dynamics
lead to an anomalous dip in at the vortex freezing transition from which
we obtain the vortex phase diagram up to T.Comment: 13 pages, 9 figure
Observed transition from Richtmyer-Meshkov jet formation through feedout oscillations to Rayleigh-Taylor instability in a laser target
Experimental study of hydrodynamic perturbation evolution triggered by a
laser-driven shock wave breakout at the free rippled rear surface of a plastic
target is reported. At sub-megabar shock pressure, planar jets manifesting the
development of the Richtmyer-Meshkov-type instability in a non-accelerated
target are observed. As the shock pressure exceeds 1 Mbar, an oscillatory
rippled expansion wave is observed, followed by the "feedout" of the
rear-surface perturbations to the ablation front and the development of the
Rayleigh-Taylor instability, which breaks up the accelerated target.Comment: 12 pages, 4 figure
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