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601.
602.
Environment‐Sensitive Behavior of DCNP in Solvents with Different Viscosity,Polarity and Proticity
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Dr. Olaf Morawski Prof. Dr. Boleslaw Kozankiewicz Prof. Dr. Andrzej Miniewicz Prof. Dr. Andrzej L. Sobolewski 《Chemphyschem》2015,16(16):3500-3510
A pyrazoline derivative, 3‐(1,1‐dicyanoethenyl)‐1‐phenyl‐4,5‐dihydro‐1H‐pyrazole (DCNP), is studied by using optical spectroscopy methods in several solvents at room and at low temperatures. The DCNP molecule reveals a complex photophysics behavior, which is sensitive to solvent polarity, proticity, temperature and viscosity and arises from the presence of two rotational degrees of freedom of the dicyanovinyl group—the torsion around the double C=C bond and the s‐trans–s‐cis isomerization around the single C?C bond—that differently behave in various environmental conditions. The fluorescence yield of a few percent and sub‐nanosecond decay times observed at room temperature make the compound useful for optical studies of liquid environments. The proticity of polar solvents can be detected with two‐exponential fluorescence decays. At low temperatures, DCNP can be used as solvent viscosity or temperature fluorescent sensor. 相似文献
603.
604.
We give the structures of a cyclic code over ring
R = F2 + uF2 + u^2F2 = {0, 1,u, u^2,v, v^2,uv, v^3},
where u^3 = 0, of odd length and its dual code. For the cyclic code, necessary and sufficient conditions for the existence of self-dual code are provided. 相似文献
R = F2 + uF2 + u^2F2 = {0, 1,u, u^2,v, v^2,uv, v^3},
where u^3 = 0, of odd length and its dual code. For the cyclic code, necessary and sufficient conditions for the existence of self-dual code are provided. 相似文献
605.
我们在本文中引入了Abel范畴的右双-Giraud粘合定义.我们证明了右双-Giraud粘合与余遗传和遗传的挠对存在着双射对应.此外,我们通过模范畴中特定的幂等理想刻画了这类挠对. 相似文献
606.
Based on the AMBER polarizable model (ff02), we have re-optimized the parameters related to the main-chain (Phi, Psi) torsion angles by fitting to the Boltzmann-weighted average quantum mechanical (QM) energies of the important regions (i.e., beta, P(II), alpha(R), and alpha(L) regions). Following the naming convention of the AMBER force field series, this release will be called ff02pol.rl The force field has been assessed both by energetic comparison against the QM data and by the replica exchange molecular dynamics simulations of short alanine peptides in water. For Ace-Ala-Nme, the simulated populations in the beta, P(II) and alpha(R) regions were approximately 30, 43, and 26%, respectively. For Ace-(Ala)(7)-Nme, the populations in these three regions were approximately 24, 49, and 26%. Both were in qualitative agreement with the NMR and CD experimental conclusions. In comparison with the previous force field, ff02pol.rl demonstrated good balance among these three important regions. The optimized torsion parameters, together with those in ff02, allow us to carry out simulations on proteins and peptides with the consideration of polarization. 相似文献
607.
D. Vassiliev 《Annalen der Physik》2005,14(4):231-252
We consider spacetime to be a connected real 4‐manifold equipped with a Lorentzian metric and an affine connection. The 10 independent components of the (symmetric) metric tensor and the 64 connection coefficients are the unknowns of our theory. We introduce an action which is (purely) quadratic in curvature and study the resulting system of Euler–Lagrange equations. In the first part of the paper we look for Riemannian solutions, i.e. solutions whose connection is Levi‐Civita. We find two classes of Riemannian solutions: 1) Einstein spaces, and 2) spacetimes with pp‐wave metric of parallel Ricci curvature. We prove that for a generic quadratic action these are the only Riemannian solutions. In the second part of the paper we look for non‐Riemannian solutions. We define the notion of a “Weyl pseudoinstanton” (metric compatible spacetime whose curvature is purely of Weyl type) and prove that a Weyl pseudoinstanton is a solution of our field equations. Using the pseudoinstanton approach we construct explicitly a non‐Riemannian solution which is a wave of torsion in a spacetime with Minkowski metric. We discuss the possibility of using this non‐Riemannian solution as a mathematical model for the neutrino. 相似文献
608.
Shazed Aziz Sina Naficy Javad Foroughi Hugh R. Brown Geoffrey M. Spinks 《Journal of Polymer Science.Polymer Physics》2016,54(13):1278-1286
Large‐scale torsional actuation occurs in twisted fibers and yarns as a result of volume change induced electrochemically, thermally, photonically, and other means. A quantitative relationship between torsional actuation (stroke and torque) and volume change is here introduced. The analysis is based on experimental investigation of the effects of fiber diameter and inserted twist on the torsional stroke and torque measured when heating and cooling nylon 6 fibers over the temperature range of 26–62 °C. The results show that the torsional stroke depends only on the amount of twist inserted into the fiber and is independent of fiber diameter. The torque generated is larger in fibers with more inserted twist and with larger diameters. These results are successfully modeled using a single‐helix approximation of the twisted fiber structure. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1278–1286 相似文献
610.
Leonid Positselski 《Mathematische Nachrichten》2023,296(2):811-839
Let R be a commutative ring and a finitely generated ideal. We discuss two definitions of derived I-adically complete (also derived I-torsion) complexes of R-modules, which appear in the literature: the idealistic and the sequential ones. The two definitions are known to be equivalent for a weakly proregular ideal I; we show that they are different otherwise. We argue that the sequential approach works well, but the idealistic one needs to be reinterpreted or properly understood. We also consider I-adically flat R-modules. 相似文献