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101.
Boris Vertman 《Annals of Global Analysis and Geometry》2012,41(1):61-90
The formula for analytic torsion of a cone in even dimensions is composed of three terms. The first two terms are well understood
and given by an algebraic combination of the Betti numbers and the analytic torsion of the cone base. The third “singular”
contribution is an intricate spectral invariant of the cone base. We identify the third term as the metric anomaly of the
analytic torsion coming from the non-product structure of the cone at its regular boundary. Hereby we filter out the actual
contribution of the concial singularity and identify the analytic torsion of an even-dimensional cone purely in terms of the
Betti numbers and the analytic torsion of the cone base. 相似文献
102.
103.
104.
Boris A. Trofimov Ludmila A. Oparina Lidiya N. Parshina Marina Ya. Khil’ko Anatolii P. Tantsyrev Galina P. Aleksandrova 《Cellulose (London, England)》2013,20(3):1201-1214
Diverse celluloses including non-mercerized and mercerized ones have been successfully vinylated with acetylene in the superbase catalytic systems MOH/DMSO and MOH/THF (M = Na, K) at 85–140 °C. Depending on the reaction conditions, degree of substitution of the hydroxyl groups by highly reactive polymerazable vinyloxy groups ranges 0.11–1.22, the yields of vinylated celluloses (insoluble in water, but soluble in DMSO) being 41–89 %. Vinylated celluloses are easily decomposed under the action of white rot fungi: Phanerochaete chrysosporium, Trametes versicolor and Trametes hirsutus, and can constitute a basis for the preparation of biodegradable polymer materials (due to polymerization or polyaddition at the vinyloxy group). 相似文献
105.
Li Zhang Dr. Julie Jung Dr. Peng Zhang Mei Guo Dr. Lang Zhao Prof. Dr. Jinkui Tang Prof. Dr. Boris Le Guennic 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1392-1398
Elaborate chemical design is of utmost importance in order to slow down the relaxation dynamics in single‐molecule magnets (SMMs) and hence improve their potential applications. Much interest was devoted to the study of distinct relaxation processes related to the different crystal fields of crystallographically independent lanthanide ions. However, the assignment of the relaxation processes to specific metal sites remains a challenging task. To address this challenge, a new asymmetric Dy2 SMM displaying a well‐separated two‐step relaxation process with the anisotropic centers in fine‐tuned local environments was elaborately designed. For the first time a one‐to‐one relationship between the metal sites and the relaxation processes was evidenced. This work sheds light on complex multiple relaxation and may direct the rational design of lanthanide SMMs with enhanced magnetic properties. 相似文献
106.
Mikhail N. Feofanov Boris A. Lozhkin Maksim V. Anokhin Alexey D. Averin Irina P. Beletskaya 《Mendeleev Communications》2018,28(4):429-430
Magnesium iodide-catalyzed addition of electron-rich (het)arenes to ethyl glyoxylate proceeds at room temperature with high chemoselectivity to afford ethyl 2-(het)aryl- 2-hydroxyacetates in yields up to 95%. 相似文献
107.
Ludmila A. Oparina Oksana V. Vysotskaya Lidiya N. Parshina Nina K. Gusarova Boris A. Trofimov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2087-2093
Under acid- or base-catalyzed conditions, thiols add regio- and chemos-electively either to vinyloxy or methacrylate group of vinyloxyalkyl-methacrylates to give polyfunctional methacrylates or polyfunctional vinyl ethers, respectively. 相似文献
108.
Nina Gusarova Lambert Brandsma Svetlana Malysheva Svetlana Arbuzova Boris Trofimov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Nucleophilic addition of phosphide anions generated from phosphorus red or phosphine to ethenes and ethynes in the presence of super bases to afford organylphosphines and -oxides has been performed. 相似文献
109.
Dr. Jessica Flores Gonzalez Vincent Montigaud Dr. Vincent Dorcet Dr. Kevin Bernot Dr. Boris Le Guennic Dr. Fabrice Pointillart Prof. Olivier Cador 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(39):10160-10168
Single-Molecule Magnet (SMM) property is by essence molecular, while commonly measured in solid crystalline state. Solvent crystallization molecules are usually neglected in the analysis and interpretation of solid-state properties. The solvation/desolvation process in the polyoxometalate(POM)-based Na9[Er(W5O18)2] ⋅ 35 H2O SMM demonstrates that the dehydrated form relaxes more than 1000 times faster than the initial state, while the rehydration process allows the quasi complete recovering of the initial magnetic behaviour. This dehydration process is monitored by thermogravimetric analysis (TGA) and temperature-dependent X-ray powder diffraction, and rationalized by periodic quantum chemical calculations evidencing the tremendous role of the labile water molecules in the stability of the edifice. Ab-initio calculations highlight that sodium ions localization in the structure drive the magnetic responses. Isotopic enrichment with nuclear spin free (166Er, I=0) ErIII ions shows that the relaxation dynamics in the quantum regime depends on the nuclear spin. 相似文献
110.
This paper considers the formation of dead zones in the porous catalyst pellets due to the chemical reaction and diffusion. We established and investigated the model with nonisothermal reaction of fractional order and activated temperature-dependent diffusivity. The effects of process parameters, catalyst shape, and reaction and diffusion parameters on the formation of the dead zone are studied numerically and characterized by the critical Thiele modulus. The lower bounds for the critical Thiele modulus are derived analytically in terms of process parameters for exothermic and endothermic reactions and verified numerically. The critical Thiele modulus increases with increasing Arrhenius number for diffusion and decreasing Arrhenius number for reaction in the case of exothermic reactions, whereas the opposite trends hold for the endothermic reactions. The critical Thiele modulus also increases with increasing fractional reaction order as well as with decreasing energy generation function, and increasing Biot numbers for heat and mass transfer. Moreover, the critical Thiele modulus is the highest for spherical pellets and the lowest for pellets with planar shape. 相似文献