13,688 research outputs found

    Computation of incompressible, three-dimensional turbulent boundary layers and comparison with experiment

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    Incompressible three dimensional, turbulent boundary layer (3DTBL) experiments were simulated numerically by integrating the boundary layer equations together with an algebraic eddy viscosity turbulence model. For the flow treated, the downstream portion, where the crossflow was large, was not predicted with the present computational method; the flow was significantly influenced by elliptic flow field effects. Departures from the boundary layer concept are indicated. Calculations agreed reasonably well with the mean flow development up to separation. In one experiment the normal pressure gradients were found to be neligible in regions with large skewing and allowed testing turbulence models using the boundary layer equations. The simulation of this flow compared favorably with the experimental data throughout the flow field and suggested the applicability of algebraic eddy viscosity models for 3DTBLs

    On the Angular Dependence of the Radiative Gluon Spectrum

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    The induced momentum spectrum of soft gluons radiated from a high energy quark produced in and propagating through a QCD medium is reexamined in the BDMPS formalism. A mistake in our published work (Physical Review C60 (1999) 064902) is corrected. The correct dependence of the fractional induced loss R(θcone)R(\theta_{{\rm cone}}) as a universal function of the variable θcone2L3q^\theta^2_{{\rm cone}} L^3 \hat q where LL is the size of the medium and q^\hat q the transport coefficient is presented. We add the proof that the radiated gluon momentum spectrum derived in our formalism is equivalent with the one derived in the Zakharov-Wiedemann approach.Comment: LaTex, 5 pages, 1 figur

    Structural and thermodynamic characterization of the adrenodoxin-like domain of the electron-transfer protein Etp1 from Schizosaccharomyces pombe

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    The protein Etp1 of Schizosaccharomyces pombe consists of an amino-terminal COX15-like domain and a carboxy-terminal ferredoxin-like domain, Etp1(fd), which is cleaved off after mitochondrial import. The physiological function of Etp1(fd) is supposed to lie in the participation in the assembly of iron-sulfur clusters and the synthesis of heme A. In addition, the protein was shown to be the first microbial ferredoxin being able to support electron transfer in mitochondrial steroid hydroxylating cytochrome P450 systems in vivo and in vitro, replacing thereby the native redox partner, adrenodoxin. Despite a sequence similarity of 39% and the fact that fission yeast is a mesophilic organism, thermodynamic studies revealed that Etp1(fd) has a melting temperature more than 20°C higher than adrenodoxin. The three-dimensional structure of Etp1(fd) has been determined by crystallography. To the best of our knowledge it represents the first three-dimensional structure of a yeast ferredoxin. The structure-based sequence alignment of Etp1(fd) with adrenodoxin yields a rational explanation for their observed mutual exchangeability in the cytochrome P450 system. Analysis of the electron exchange with the S. pombe redox partner Arh1 revealed differences between Etp1(fd) and adrenodoxin, which might be linked to their different physiological functions in the mitochondria of mammals and yeast

    Charged currents, color dipoles and xF_3 at small x

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    We develop the light-cone color dipole description of highly asymmetric diffractive interactions of left-handed and right-handed electroweak bosons. We identify the origin and estimate the strength of the left-right asymmetry effect in terms of the light-cone wave functions. We report an evaluation of the small-x neutrino-nucleon DIS structure functions xF_3 and 2xF_1 and present comparison with experimental data.Comment: 11 pages, 3 figures, misprints correcte

    Scalable Synthesis of Microsized, Nanocrystalline Zn0.9_{0.9}Fe0.1_{0.1}O-C Secondary Particles and Their Use in Zn0.9_{0.9}Fe0.1_{0.1} O-C/LiNi0.5_{0.5}Mn1.5_{1.5}O4_{4} Lithium-Ion Full Cells

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    Conversion/alloying materials (CAMs) are a potential alternative to graphite as Li‐ion anodes, especially for high‐power performance. The so far most investigated CAM is carbon‐coated Zn0.9_{0.9}Fe0.1_{0.1}O, which provides very high specific capacity of more than 900 mAh g1^{-1} and good rate capability. Especially for the latter the optimal particle size is in the nanometer regime. However, this leads to limited electrode packing densities and safety issues in large‐scale handling and processing. Herein, a new synthesis route including three spray‐drying steps that results in the formation of microsized, spherical secondary particles is reported. The resulting particles with sizes of 10–15 μm are composed of carbon‐coated Zn0.9_{0.9}Fe0.1_{0.1}O nanocrystals with an average diameter of approximately 30–40 nm. The carbon coating ensures fast electron transport in the secondary particles and, thus, high rate capability of the resulting electrodes. Coupling partially prelithiated, carbon‐coated Zn0.9_{0.9}Fe0.1_{0.1}O anodes with LiNi0.5_{0.5}Mn1.5_{1.5}O4_{4} cathodes results in cobalt‐free Li‐ion cells delivering a specific energy of up to 284 Wh kg1^{-1} (at 1 C rate) and power of 1105 W kg−1 (at 3 C) with remarkable energy efficiency (>93 % at 1 C and 91.8 % at 3 C)
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