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31.
Even by Russian standards, the country’s northwestern territories contouring the White and Barents seas are vast, remote, and sparsely populated. Yet for seven centuries that faraway province has served as a nursery of religious and intellectual freedom and as a primary entry point for Western civilization and trade, containing several scientific landmarks of interest to the physical tourist. This article is intended as a concise guide to the scientifically relevant attractions in the city of Arkhangelsk and in relatively “nearby” locations that can be reached within reasonable time and with reasonable convenience; these include Mikhail Lomonosov’s birthplace on Kholmogory and the Solovetsky islands. We will also briefly mention relevant facts for the somewhat more remote—but still within 1000 km—territories of Kola peninsula and the Novaya Zemlya islands. 相似文献
32.
Marat Gafurov Vasyl Denysenkov Mark J. Prandolini Thomas F. Prisner 《Applied magnetic resonance》2012,43(1-2):119-128
The temperature dependence of the water-proton dynamic nuclear polarization (DNP) enhancement from Fremy’s salt nitroxide radicals was measured in a magnetic field of 9.2?T (corresponding to 260?GHz microwave (MW) and 392?MHz NMR frequencies) in the temperature range of 15–65?°C. The temperature could be determined directly from the proton NMR line shift of the sample. Very high DNP enhancements of ?38 (signal integral) or ?81 (peak intensity) could be achieved with a high-power gyrotron MW source. The experimental findings are compared with classical Overhauser theory for liquids, which is based on the translational and rotational motion of the molecules and with molecular dynamics calculations of the coupling factor. 相似文献
33.
Ivan S. Chaschin Timofei E. Grigorev Marat O. Gallyamov Alexei R. Khokhlov 《European Polymer Journal》2012,48(5):906-918
Chitosan and its derivatives are promising materials for coating medical devices because this procedure improves their bio- and haemocompatibility. It is known that supercritical carbon dioxide attracts significant scientific interest in biomedical applications as well. Coatings deposited directly from solutions in supercritical carbon dioxide are expected to have particularly smooth and uniform morphology that should enhance their stability. We have tested the possibility of obtaining chitosan films using direct deposition from solutions in this fluid. In order to reveal benefits of this approach we modelled and studied the initial stage of formation of chitosan coatings with prototype system of depositing pioneer single polymer chains directly from such solutions on a model ultrasmooth mica substrate. We estimated achievable solubility of the chitosan materials in supercritical carbon dioxide and performed conformational analysis of the deposited chitosan chains on a substrate. AFM imaging directly demonstrated that the pioneer macromolecules adsorb as rather extended 2D coils from such solutions. 相似文献
34.
Murdachaew G Valiev M Kathmann SM Wang XB 《The journal of physical chemistry. A》2012,116(9):2055-2061
Alkali metal cations often show pronounced ion-specific interactions and selectivity with macromolecules in biological processes, colloids, and interfacial sciences, but a fundamental understanding about the underlying microscopic mechanism is still very limited. Here we report a direct probe of interactions between alkali metal cations (M(+)) and dicarboxylate dianions, (-)O(2)C(CH(2))(n)CO(2)(-) (D(n)(2-)) in the gas phase by combined photoelectron spectroscopy (PES) and ab initio electronic structure calculations on nine M(+)-D(n)(2-) complexes (M = Li, Na, K; n = 2, 4, 6). PES spectra show that the electron binding energy (EBE) decreases from Li(+) to Na(+) to K(+) for complexes of M(+)-D(2)(2-), whereas the order is Li(+) < Na(+) ≈ K(+) when M(+) interacts with a more flexible D(6)(2-) dianion. Theoretical modeling suggests that M(+) prefers to interact with both ends of the carboxylate -COO(-) groups by bending the flexible aliphatic backbone, and the local binding environments are found to depend upon backbone length n, carboxylate orientation, and the specific cation M(+). The observed variance of EBEs reflects how well each specific dicarboxylate dianion accommodates each M(+). This work demonstrates the delicate interplay among several factors (electrostatic interaction, size matching, and strain energy) that play critical roles in determining the structures and energetics of gaseous clusters as well as ion specificity and selectivity in solutions and biological systems. 相似文献
35.
EM Chainikova RL Safiullin LV Spirikhin MF Abdullin 《The journal of physical chemistry. A》2012,116(31):8142-8147
The electronic spectra were measured and the unimolecular decay kinetics of the isomeric forms (cis and trans) of 4-methoxyphenylnitroso oxide in acetonitrile, benzene, and hexane was studied using flash photolysis. The cis form absorbed in a shorter wavelength region and was more labile than the trans form. The difference between the reactivity of the two species increased on going from hexane to acetonitrile. The temperature dependences of reaction rate constants were studied for both isomeric forms. The analysis of products of flash photolysis of 4-methoxyphenyl azide in the presence of oxygen allowed for understanding the mechanism of thermal decay of nitroso oxides. It was shown that the trans nitroso oxide is converted into cis nitroso oxide. The latter undergoes an unusual ring cleavage reaction to form 4-methoxy-6-oxohexa-2,4-dienenitrile N-oxide derivative. We conclude that the nitro- and nitrosobenzenes, which are the main products of the steady-state photolysis of aromatic azides in the presence of oxygen, are formed by the photochemical transformation of the nitroso oxides. 相似文献
36.
Ilshat M. Sakhautdinov Rauilya N. Malikova Yulya N. Biglova Rail A. Khusnutdinov Aynur M. Gumerov Edvard M. Khamitov Sergey P. Ivanov Marat S. Yunusov 《Journal of the Iranian Chemical Society》2018,15(9):1975-1985
New cyclopentene-fused [C60]-fullerene derivatives containing terpene moieties have been synthesized by [3?+?2]-addition to fullerene C60. All obtained products were fully characterized by 1H- and 13C-NMR, IR, and MS. The electrochemical properties have been studied by cyclic voltammograms (CV), combined with absorption spectra, which are consistent with those obtained from density functional theory (DFT) calculations. It was found that all fulleropyrrolidines showed very similar absorption spectra, orbital energies, in which electron densities in both the LUMO and HOMO are mainly located on the fullerene cage, suggesting that C60 act as the acceptor. All the compounds exhibited good thermal stability. All determined characteristics of fullerene conjugates were compared to [6,6]-phenyl-C61-butyric acid methyl ester ([60]PCBM), a popular fullerene-containing compound. 相似文献
Graphical abstract
37.
Inside Cover: Square‐Planar Ruthenium(II) Complexes: Control of Spin State by Pincer Ligand Functionalization (Chem. Eur. J. 2/2015) 下载免费PDF全文
Dr. Bjorn Askevold Dr. Marat M. Khusniyarov Dr. Wolfgang Kroener Dr. Klaus Gieb Prof. Paul Müller Dr. Eberhardt Herdtweck Dr. Frank W. Heinemann Dr. Martin Diefenbach Prof. Max C. Holthausen Veacheslav Vieru Prof. Liviu F. Chibotaru Prof. Sven Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):474-474
38.
Siberian Mathematical Journal - We study the $ p $ -reducibility of numberings which was introduced and first studied by Degtev. $ p $ -Reducibility is an effectively bounded version of the $ e $... 相似文献
39.
We extend the limitwise monotonicity notion to the case of arbitrary computable linear ordering to get a set which is limitwise monotonic precisely in the non‐computable degrees. Also we get a series of connected non‐uniformity results to obtain new examples of non‐uniformly equivalent families of computable sets with the same enumeration degree spectrum. 相似文献
40.
Marat V. Markin 《Applicable analysis》2013,92(3-4):573-606
For the evolution equation y' ′(t)=Ay(t) with a normal operator A in a Hilbert space, conditions on A are found which are necessary and sufficient for all weak solutions of the equation to be strongly differentiable. Certain effects of smoothness improvement of the weak solutions are analyzed. The strong infinite differentiability of weak solutions of the equation with a symmetric operator is proved. 相似文献