950 research outputs found

    Q-band electron nuclear double resonance (ENDOR) and X-band EPR of the sulfobetaine 12 heat-treated cytochrome c oxidase complex

    Get PDF
    Heat treatment of the bovine cytochrome c oxidase complex in the zwitterionic detergent sulfobetaine 12 (SB-12) results in loss of subunit III and the appearance of a type II copper center as characterized by electron paramagnetic resonance (EPR) spectroscopy. Previous authors (Nilsson, T., Copeland, R. A., Smith, P. A., and Chan, S. I. (1988) Biochemistry 27, 8254-8260) have interpreted this type II copper center as a modified version of the CuA site. By using electron nuclear double resonance spectroscopy, it is found that the CuA proton and nitrogen resonances remain present in the SB-12 heat-treated enzyme and that three new nitrogen resonances appear having hyperfine coupling constants consistent with histidine ligation. These hyperfine coupling constants correlate well with those recently found for the CuB histidines from the cytochrome aa3-600 quinol oxidase from Bacillus subtilis (Fann, Y. C., Ahmed, I., Blackburn, N. J., Boswell, J. S., Verkhovskaya, M. L., Hoffman, B. M., and Wikström, M. (1995) Biochemistry 34, 10245-10255). In addition, the total EPR-detectable copper concentration per enzyme molecule approximately doubles upon SB-12 heat treatment. Finally, the observed type II copper EPR spectrum is virtually indistinguishable from the EPR spectrum of CuB of the as-isolated cytochrome bo3 complex from Escherichia coli. These data indicate that the type II copper species that appears results from a breaking of the strong antiferromagnetic coupling of the heme a3-CuB binuclear center

    Coordinate-Space Hartree-Fock-Bogoliubov Solvers for Superfluid Fermi Systems in Large Boxes

    Full text link
    The self-consistent Hartree-Fock-Bogoliubov problem in large boxes can be solved accurately in the coordinate space with the recently developed solvers HFB-AX (2D) and MADNESS-HFB (3D). This is essential for the description of superfluid Fermi systems with complicated topologies and significant spatial extend, such as fissioning nuclei, weakly-bound nuclei, nuclear matter in the neutron star rust, and ultracold Fermi atoms in elongated traps. The HFB-AX solver based on B-spline techniques uses a hybrid MPI and OpenMP programming model for parallel computation for distributed parallel computation, within a node multi-threaded LAPACK and BLAS libraries are used to further enable parallel calculations of large eigensystems. The MADNESS-HFB solver uses a novel multi-resolution analysis based adaptive pseudo-spectral techniques to enable fully parallel 3D calculations of very large systems. In this work we present benchmark results for HFB-AX and MADNESS-HFB on ultracold trapped fermions.Comment: Conference on Computational Physics (CCP 2011) Proceedin

    Review of morphology dependent charge carrier mobility in MEH-PPV

    Get PDF
    Charge carrier mobility in poly(2-methoxy,5(2'-ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV) films were measured as a function of temperature and electric field parallel and perpendicular to the substrate for devices prepared from different solvents and under different processing conditions Bulk structural morphology was characterized by various X-ray diffraction measurements such as wide angle, small angle and X-ray reflection. Surface morphology was characterized using various scanning probe microscopic techniques Mobilities were found to follow Gaussian disorder model (GDM) and to be highly anisotropic not only depending on the solvents used but also on the film preparation method such as spin-coating or drop-casting While no direct correlation was found between charge carrier mobility and photoluminescence, charge transport parameters were correlated with structural morpholog

    On the kinks and dynamical phase transitions of alpha-helix protein chains

    Full text link
    Heuristic insights into a physical picture of Davydov's solitonic model of the one-dimensional protein chain are presented supporting the idea of a non-equilibrium competition between the Davydov phase and a complementary, dynamical- `ferroelectric' phase along the chainComment: small latex file with possible glue problems, just go on !, no figures, small corrections with respect to the published text, follow-up work to cond-mat/9304034 [PRE 47 (June 1993) R3818

    Nonequilibrium Magnetization Dynamics of Nickel

    Full text link
    Ultrafast magnetization dynamics of nickel has been studied for different degrees of electronic excitation, using pump-probe second-harmonic generation with 150 fs/800 nm laser pulses of various fluences. Information about the electronic and magnetic response to laser irradiation is obtained from sums and differences of the SHG intensity for opposite magnetization directions. The classical M(T)-curve can be reproduced for delay times larger than the electron thermalization time of about 280 fs, even when electrons and lattice have not reached thermal equilibrium. Further we show that the transient magnetization reaches its minimum approx. 50 fs before electron thermalization is completed.Comment: 8 pages, 5 figures, revte

    The role of occupied d states in the relaxation of hot electrons in Au

    Get PDF
    We present first-principles calculations of electron-electron scattering rates of low-energy electrons in Au. Our full band-structure calculations indicate that a major contribution from occupied d states participating in the screening of electron-electron interactions yields lifetimes of electrons in Au with energies of 1.0−3.0eV1.0-3.0 {\rm eV} above the Fermi level that are larger than those of electrons in a free-electron gas by a factor of ∼4.5\sim 4.5. This prediction is in agreement with a recent experimental study of ultrafast electron dynamics in Au(111) films (J. Cao {\it et al}, Phys. Rev. B {\bf 58}, 10948 (1998)), where electron transport has been shown to play a minor role in the measured lifetimes of hot electrons in this material.Comment: 4 pages, 2 figures, to appear in Phys. Rev.

    Coordinate-Space Hartree-Fock-Bogoliubov Description of Superfluid Fermi Systems

    Full text link
    Properties of strongly interacting, two-component finite Fermi systems are discussed within the recently developed coordinate-space Hartree-Fock-Bogoliubov (HFB) code {\hfbax}. Two illustrative examples are presented: (i) weakly bound deformed Mg isotopes, and (ii) spin-polarized atomic condensates in a strongly deformed harmonic trap.Comment: 4 pages, 2 figures, ENAM 2008 conference proceedings (EPJA

    DOP17 Identification of biomarkers and mechanistic insight for upadacitinib in ulcerative colitis: Analysis of serum inflammatory mediators in the phase 2b U-ACHIEVE study

    Get PDF
    Abstract Background The U-ACHIEVE trial evaluated upadacitinib (UPA), an oral JAK1 selective inhibitor, in patients with moderately to severely active ulcerative colitis (UC). Patient-reported and endoscopic outcomes improved after UPA treatment. This analysis used pharmacodynamic profiling to link changes in serum biomarkers to changes in UC disease activity, and to assess the UPA mechanism of action in UC. Methods U-ACHIEVE (NCT02819635) was a randomised, double-blind, placebo (PBO)-controlled phase 2b clinical trial. Adults with an inadequate response, loss of response, or intolerance to corticosteroids, immunosuppressants, or biologic therapies were randomised to receive 7.5, 15, 30, or 45 mg UPA once daily or PBO for 8 weeks (weeks). Serum samples (baseline [BL], weeks 2, 4, and 8) were analysed by OLINK® inflammation panel (92 proteins) and by Singulex immunoassay for interleukin-1b (IL-1b), IL-17A, IL-17F, and IL-22. Protein-level changes were analysed by a mixed-effect model; BL protein level was adjusted as a covariate; treatment group, time point, and their interaction were included as fixed effects. Spearman rank-correlation coefficients were used to determine the relationship between changes of serum biomarker levels and improvements in adapted Mayo scores and endoscopic subscores. Multiplicity adjusted P values were calculated using 1000 runs of random permutations. Results Paired BL and week 8 serum samples were available from 114 patients (PBO, n = 17; UPA 7.5 mg, n = 21; UPA 15 mg, n = 21; UPA 30 mg, n = 29; UPA 45 mg, n = 26). UPA treatment reduced expression of pro-inflammatory mediators associated with immune cell migration, type I/II IFN responses, T-cell responses, macrophage and dendritic cell activity and increased expression of biomarkers associated with haematopoiesis, neuroprotection and mucosal repair in a dose-dependent manner. Improvements in adapted Mayo score, endoscopic subscore, and stool frequency correlated with increases in CX3CL1, DNER and FLt3L (p < 0.05 for all). Endoscopic improvements correlated with reductions in OSM, and improvements in fatigue correlated with increases in CCL25 and NT-3. There was a substantial overlap in biomarkers modulated by UPA in patients with UC and Crohn's disease (Figure). Conclusion UPA modulated expression of serum pro-inflammatory mediators found in pathways associated with the pathogenesis of UC, including immune cell migration, type I/II IFN responses, T-cell responses, macrophage and dendritic cell activity, haematopoiesis, neuroprotection, and mucosal repair. Consistent correlations were observed between changes in biomarker expression and improvements in disease activity and symptoms of UC
    • …
    corecore