966 research outputs found

    Nonflammable Lithium Metal Full Cells with Ultra-high Energy Density Based on Coordinated Carbonate Electrolytes

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    Coupling thin Li metal anodes with high-capacity/high-voltage cathodes such as LiNi0.8Co0.1Mn0.1O2 (NCM811) is a promising way to increase lithium battery energy density. Yet, the realization of high-performance full cells remains a formidable challenge. Here, we demonstrate a new class of highly coordinated, nonflammable carbonate electrolytes based on lithium bis(fluorosulfonyl)imide (UFSI) in propylene carbonate/fluoroethylene carbonate mixtures. Utilizing an optimal salt concentr ation (4 M LiFSI) of the electrolyte results in a unique coordination structure of Li+-FSI-solvent cluster, which is critical for enabling the formation of stable interfaces on both the thin Li metal anode and high-voltage NCM811 cathode. Under highly demanding cell configuration and operating conditions (Li metal anode = 35 mu m, areal capacity/charge voltage of NCM811 cathode = 4.8 mAh cm(-2)/4 .6 V, and anode excess capacity [relative to the cathode] = 0.83), the Li metal-based full cell provides exceptional electrochemical performance (energy densities = 679 Wh kg(cell)(-1)/1,024 Wh L-cell(-1)) coupled with nonflammability

    Discrete Symmetries on the Light Front and a General Relation Connecting Nucleon Electric Dipole and Anomalous Magnetic Moments

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    We consider the electric dipole form factor, F_3(q^2), as well as the Dirac and Pauli form factors, F_1(q^2) and F_2(q^2), of the nucleon in the light-front formalism. We derive an exact formula for F_3(q^2) to complement those known for F_1(q^2) and F_2(q^2). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F_2(q^2) and F_3(q^2), Fock state by Fock state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo the isospin structure of the anomalous magnetic moments, kappa^n ~ - kappa^p.Comment: 25 pages, 1 figure. Published version. Ref. adde

    Chiral-Odd Fragmentation Functions in Single Pion Inclusive Electroproduction

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    We consider a sub-leading twist chiral-odd pion fragmentation function and explore its contribution in single pion semi-inclusive electroproduction. We evaluate the single beam-spin azimuthal asymmetry ALUA_{LU} and the double spin asymmetry ALTA_{LT} in polarized electroproduction of pions from an unpolarized and transversely polarized nucleon respectively. The beam asymmetry is expressed as the product of chiral-odd, and TT-odd and even distribution and fragmentation functions. The double spin asymmetry contains information on the quark's transversity distribution. In a quark diquark-spectator framework we estimate these asymmetries at 6GeV6 {\rm GeV}, 12GeV 12 {\rm GeV}, and 27.5GeV27.5 {\rm GeV} energies.Comment: 10 pages, 4 eps figures, elsart.cls, typos corrected. To be published in Physics Letters

    UKIRT Widefield Infrared Survey for Fe+

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    The United Kingdom Infrared Telescope (UKIRT)Widefield Infrared Survey for Fe+ (UWIFE) is a 180 deg2 imaging survey of the first Galactic quadrant (7° < l < 62° |b| <1°.5) that uses a narrow-band filter centred on the [Fe II] 1.644-μm emission line. The [Fe II] 1.644-μm emission is a good tracer of dense, shock-excited gas, and the survey will probe violent environments around stars: star-forming regions, evolved stars, and supernova remnants, among others. The UWIFE survey is designed to complement the existing UKIRTW idefield Infrared Survey for H2 (UWISH2). The survey will also complement existing broad-band surveys. The observed images have a nominal 5Ï? detection limit of 18.7 mag for point sources, with a median seeing of 0.83 arcsec. For extended sources, we estimate a surface brightness limit of 8.1 Ã? 10-20 W m-2 arcsec-2. In this paper, we present an overview and some preliminary results of this survey. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

    A Fast Track towards the `Higgs' Spin and Parity

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    The LHC experiments ATLAS and CMS have discovered a new boson that resembles the long-sought Higgs boson: it cannot have spin one, and has couplings to other particles that increase with their masses, but the spin and parity remain to be determined. We show here that the `Higgs' + gauge boson invariant-mass distribution in `Higgs'-strahlung events at the Tevatron or the LHC would be very different under the J^P = 0+, 0- and 2+ hypotheses, and could provide a fast-track indicator of the `Higgs' spin and parity. Our analysis is based on simulations of the experimental event selections and cuts using PYTHIA and Delphes, and incorporates statistical samples of `toy' experiments.Comment: 18 pages, 9 pdf figure

    Decay Constants and Semileptonic Decays of Heavy Mesons in Relativistic Quark Model

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    We investigate the BB and DD mesons in the relativistic quark model by applying the variational method with the Gaussian wave function. We calculate the Fermi momentum parameter pFp_{_F}, and obtain pF=0.500.54p_{_F} = 0.50 \sim 0.54 GeV, which is almost independent of the input parameters, αs\alpha_s, mbm_b, mcm_c and mspm_{sp}. We then calculate the ratio fBf_B/fDf_D, and obtain the result which is larger, by the factor of about 1.3, than MD/MB\sqrt{M_D / M_B} given by the naive nonrelativistic analogy. This result is in a good agreement with the recent Lattice calculations. We also calculate the ratio (MBMB)(M_{B^*}-M_{B})/(MDMD)(M_{D^*}-M_{D}). In these calculations the wave function at origin ψ(0)\psi (0) is essential. We also determine pFp_{_F} by comparing the theoretical prediction of the ACCMM model with the lepton energy spectrum of BeνXB \rightarrow e \nu X from the recent ARGUS analysis, and find that pF=0.27 ± 0.270.22p_{_F}=0.27~\pm~^{0.22}_{0.27} GeV, when we use mc=1.5m_c=1.5 GeV. However, this experimentally determined value of pFp_{_F} is strongly dependent on the value of input parameter mcm_c.Comment: 15 pages (Latex) (uses epsfig.sty, 1 figure appended as a uuencoded compressed ps-file

    Double primary malignancies associated with colon cancer in patients with situs inversus totalis: two case reports

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    Situs inversus totalis (SIT) is not itself a premalignant condition, however, rare synchronous or metachronous multiple primary malignancies have been reported. Herein we present a case of synchronous transverse and sigmoid colon cancers and a case of metachronous rectosigmoid colon and gastric cancers in patients with SIT

    Magnetic Field Dependence of Macroscopic Quantum Tunneling and Coherence of Ferromagnetic Particle

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    We calculate the quantum tunneling rate of a ferromagnetic particle of 100A˚\sim 100 \AA diameter in a magnetic field of arbitrary angle. We consider the magnetocrystalline anisotropy with the biaxial symmetry and that with the tetragonal symmetry. Using the spin-coherent-state path integral, we obtain approximate analytic formulas of the tunneling rates in the small ϵ(=1H/Hc)\epsilon (=1- H/H_c)-limit for the magnetic field normal to the easy axis (θH=π/2\theta_H = \pi/2), for the field opposite to the initial easy axis (θH=π\theta_H = \pi), and for the field at an angle between these two orientations (π/2<<θH<<π\pi/2 << \theta_H << \pi). In addition, we obtain numerically the tunneling rates for the biaxial symmetry in the full range of the angle θH\theta_H of the magnetic field (π/2<θHπ\pi/2 < \theta_H \leq \pi), for the values of \epsilon =0.01 and 0.001.Comment: 25 pages of text (RevTex) and 4 figures (PostScript files), to be published in Phys. Rev.

    Combinatorial Polymer Electrospun Matrices Promote Physiologically-Relevant Cardiomyogenic Stem Cell Differentiation

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    Myocardial infarction results in extensive cardiomyocyte death which can lead to fatal arrhythmias or congestive heart failure. Delivery of stem cells to repopulate damaged cardiac tissue may be an attractive and innovative solution for repairing the damaged heart. Instructive polymer scaffolds with a wide range of properties have been used extensively to direct the differentiation of stem cells. In this study, we have optimized the chemical and mechanical properties of an electrospun polymer mesh for directed differentiation of embryonic stem cells (ESCs) towards a cardiomyogenic lineage. A combinatorial polymer library was prepared by copolymerizing three distinct subunits at varying molar ratios to tune the physicochemical properties of the resulting polymer: hydrophilic polyethylene glycol (PEG), hydrophobic poly(ε-caprolactone) (PCL), and negatively-charged, carboxylated PCL (CPCL). Murine ESCs were cultured on electrospun polymeric scaffolds and their differentiation to cardiomyocytes was assessed through measurements of viability, intracellular reactive oxygen species (ROS), α-myosin heavy chain expression (α-MHC), and intracellular Ca2+ signaling dynamics. Interestingly, ESCs on the most compliant substrate, 4%PEG-86%PCL-10%CPCL, exhibited the highest α-MHC expression as well as the most mature Ca2+ signaling dynamics. To investigate the role of scaffold modulus in ESC differentiation, the scaffold fiber density was reduced by altering the electrospinning parameters. The reduced modulus was found to enhance α-MHC gene expression, and promote maturation of myocyte Ca2+ handling. These data indicate that ESC-derived cardiomyocyte differentiation and maturation can be promoted by tuning the mechanical and chemical properties of polymer scaffold via copolymerization and electrospinning techniques

    Average Kinetic Energy of Heavy Quark in Semileptonic B Decay

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    Within the ACCMM model the average kinetic energy of heavy quark in a heavy-light meson is calculated as p2=32pF2\langle {\bf p}^2 \rangle = {3 \over 2} {p_{_F}}^2, solely from the fact that the Gaussian momentum probability distribution has been taken in the ACCMM model. Therefore, the Fermi momentum parameter pFp_{_F} of the ACCMM model is not a truly free parameter, but is closely related to the average kinetic energy of heavy quark, which is theoretically calculable in principle. In this context, we determine pFp_{_F} by comparing the theoretical prediction of the ACCMM model with the model independent lepton energy spectrum of BeνXB \rightarrow e \nu X from the recent CLEO analysis, and find that pF=0.54 ± 0.150.16p_{_F}=0.54~\pm~^{0.16}_{0.15} GeV. We also calculate pFp_{_F} in the relativistic quark model by applying the quantum mechanical variational method, and obtained pF=0.50.6p_{_F}=0.5\sim 0.6 GeV. We show the correspondences between the relativistic quark model and the heavy quark effective theory. We then clarify the importance of the value of pFp_{_F} in the determination of Vub/Vcb|V_{ub}/V_{cb}|.Comment: 23 pages(LaTeX), 2 Postscript figures, uses aps.st
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