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151.
Dr. Dinar Abdullin Dr. Hideto Matsuoka Dr. Maxim Yulikov Nico Fleck Dr. Christoph Klein Dr. Sebastian Spicher Dr. Gregor Hagelueken Prof. Dr. Stefan Grimme Prof. Dr. Arne Lützen Prof. Dr. Olav Schiemann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(37):8820-8828
Pulsed EPR dipolar spectroscopy (PDS) offers several methods for measuring dipolar coupling and thus the distance between electron-spin centers. To date, PDS measurements to metal centers were limited to ions that adhere to the high-field approximation. Here, the PDS methodology is extended to cases where the high-field approximation breaks down on the example of the high-spin Fe3+/nitroxide spin-pair. First, the theory developed by Maryasov et al. (Appl. Magn. Reson. 2006 , 30, 683–702) was adapted to derive equations for the dipolar coupling constant, which revealed that the dipolar spectrum does not only depend on the length and orientation of the interspin distance vector with respect to the applied magnetic field but also on its orientation to the effective g-tensor of the Fe3+ ion. Then, it is shown on a model system and a heme protein that a PDS method called relaxation-induced dipolar modulation enhancement (RIDME) is well-suited to measuring such spectra and that the experimentally obtained dipolar spectra are in full agreement with the derived equations. Finally, a RIDME data analysis procedure was developed, which facilitates the determination of distance and angular distributions from the RIDME data. Thus, this study enables the application of PDS to for example, the highly relevant class of high-spin Fe3+ heme proteins. 相似文献
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Hirzinger Benjamin Adam Christoph Salcher Patrick Oberguggenberger Michael 《Meccanica》2019,54(9):1385-1402
Meccanica - The scope of this paper is to evaluate the performance and computational efficiency of various stochastic simulation methods for a stochastic based reliability assessment of railway... 相似文献
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Tino Zaehle Pascale Sandmann Jeremy D Thorne Lutz Jäncke Christoph S Herrmann 《BMC neuroscience》2011,12(1):2
Background
Transcranial direct current stimulation (tDCS) is a technique that can systematically modify behaviour by inducing changes in the underlying brain function. In order to better understand the neuromodulatory effect of tDCS, the present study examined the impact of tDCS on performance in a working memory (WM) task and its underlying neural activity. In two experimental sessions, participants performed a letter two-back WM task after sham and either anodal or cathodal tDCS over the left dorsolateral prefrontal cortex (DLPFC). 相似文献158.
159.
Association and Dissociation of Grignard Reagents RMgCl and Their Turbo Variant RMgCl⋅LiCl 下载免费PDF全文
Christoph Schnegelsberg Sebastian Bachmann Marlene Kolter Thomas Auth Dr. Michael John Prof. Dr. Dietmar Stalke Prof. Dr. Konrad Koszinowski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7752-7762
Grignard reagents RMgCl and their so‐called turbo variant, the highly reactive RMgCl?LiCl, are of exceptional synthetic utility. Nevertheless, it is still not fully understood which species these compounds form in solution and, in particular, in which way LiCl exerts its reactivity‐enhancing effect. A combination of electrospray‐ionization mass spectrometry, electrical conductivity measurements, NMR spectroscopy (including diffusion‐ordered spectroscopy), and quantum chemical calculations is used to analyze solutions of RMgCl (R=Me, Et, Bu, Hex, Oct, Dec, iPr, tBu, Ph) in tetrahydrofuran and other ethereal solvents in the absence and presence of stoichiometric amounts of LiCl. In tetrahydrofuran, RMgCl forms mononuclear species, which are converted into trinuclear anions as a result of the concentration increase experienced during the electrospray process. These trinuclear anions are theoretically predicted to adopt open cubic geometries, which remarkably resemble structural motifs previously found in the solid state. The molecular constituents of RMgCl and RMgCl?LiCl are interrelated via Schlenk equilibria and fast intermolecular exchange processes. A small portion of the Grignard reagent also forms anionic ate complexes in solution. The abundance of these more electron‐rich and hence supposedly more nucleophilic ate complexes strongly increases upon the addition of LiCl, thus rationalizing its beneficial effect on the reactivity of Grignard reagents. 相似文献
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Thomas Weymuth Moritz P. Haag Karin Kiewisch Sandra Luber Stephan Schenk Christoph R. Jacob Carmen Herrmann Johannes Neugebauer Markus Reiher 《Journal of computational chemistry》2012,33(27):2186-2198
We present the software package MO VI PAC for calculations of vibrational spectra, namely infrared, Raman, and Raman Optical Activity (ROA) spectra, in a massively parallelized fashion. MO VI PAC unites the latest versions of the programs SNF and AKIRA alongside with a range of helpful add‐ons to analyze and interpret the data obtained in the calculations. With its efficient parallelization and meta‐program design, MO VI PAC focuses in particular on the calculation of vibrational spectra of very large molecules containing on the order of a hundred atoms. For this purpose, it also offers different subsystem approaches such as Mode‐ and Intensity‐Tracking to selectively calculate specific features of the full spectrum. Furthermore, an approximation to the entire spectrum can be obtained using the Cartesian Tensor Transfer Method. We illustrate these capabilities using the example of a large π‐helix consisting of 20 (S)‐alanine residues. In particular, we investigate the ROA spectrum of this structure and compare it to the spectra of α‐ and 310‐helical analogs. © 2012 Wiley Periodicals, Inc. 相似文献