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991.
On the basis of quantum-chemical calculation of methane, methylaluminum and methylindium, it is shown that essentially the non-divided 2s2-electron pair of the carbon atom has the ability to take part in specific intermolecular interaction. Thermodynamic analysis of structural changes in solutions of the Al(CH3)3–In(CH3)3, Al(CH3)3–In(C2H5)3 systems substantiated the formation of solvate structures in which four types of interaction were involved. It is shown that specific intermolecular interaction with the participation of pentacoordinated carbon atom is approximately twice higher than the energy of the hydrogen bond in liquid ammonia. 相似文献
992.
Irina Ryzhkova 《Journal of Mathematical Analysis and Applications》2004,294(2):462-481
We discuss the problem of nonlinear oscillations of a clamped plate in the presence of thermal effects in a subsonic gas flow. The dynamics of the plate is described by von Kármán system in the presence of thermal effects, in which rotational inertia is accounted for. To describe influence of the gas flow we apply the linearized theory of potential flows. Our main result states that each weak solution of the problem considered tends to the set of the stationary points of the problem. 相似文献
993.
Christian Amatore Alexander Oleinick Oleksiy V Klymenko Laurent Thouin Laurent Servant Irina Svir 《Chemphyschem》2007,8(11):1664-1676
A realistic theoretical model describing the outcome of confocal microscopic imaging of electrochemiluminescence (ECL) light emission is derived for a two parallel band microelectrodes assembly operated under steady state. The model takes into account the experimental distortions ensuing from a) the specific finite shape of the sampling volume in confocal microscopy, b) the light arising directly from out-of-focus area but transmitted through the microscope diaphragm or c) transmitted after reflection from the polished platinum band electrodes. The model is based on a detailed optical, physico-mathematical and numerical analysis of the problem at hand, and on simulations of the concentration distribution of the species giving rise to the ECL generation. Its outcome allows the reconstruction of the real spatial distribution of ECL light emission based on the confocal microscopy measurements upon correcting for the effect of experimental distortions using numerical fitting procedure. 相似文献
994.
Pavel Arsenyan Kira Rubina Irina Shestakova Edgars Abele Ramona Abele Ilona Domracheva Alena Nesterova Juris Popelis Edmunds Lukevics 《应用有机金属化学》2003,17(11):825-830
New hydroselenites of the different silylalkylthio‐substituted N‐heterocycles have been prepared by the reaction of selenium dioxide with N‐heterocycles in an aqueous medium. Their structure was confirmed by 1H, 13C, and 77Se NMR data. Most of these silylalkylthio‐substituted N‐heterocycles and their hydroselenites have an expressed cytotoxic activity on the MG‐22A (mouse hepatoma), HT‐1080 (human fibrosarcoma), B16 (mouse melanoma), and Neuro 2A (mouse neuroblastoma) cell lines. Some of the hydroselenites exhibit free‐radical protection simultaneously with a high cytotoxic effect. The substances studied were also active in vivoagainst sarcoma S‐180. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
995.
Irina Gouzman 《Surface science》2006,600(4):773-781
Combining functional organic self-assembled monolayers (SAMs) with conventional semiconductor materials is a key step in the development of integrated electronics-based devices. T-BAG (Tethering by Aggregation and Growth) has been shown to be a simple and reliable method to grow SAMs of alkylphosphonates on oxide surfaces. However, distinguishing SAMs from ultra-thin multilayers is a challenge for most conventional surface characterization techniques.Self-assembled films of octadecylphosphonic acid (ODPA) were deposited on oxide-covered silicon coupons, converted to the corresponding phosphonates, and characterized by high resolution angularly resolved X-ray photoelectron spectroscopy (XPS). It was our goal to distinguish among different bonding configurations for phosphorous in the phosphonate head groups, namely, mono-dentate, bi-dentate or tri-dentate interactions with the oxide surface, as well as to assess quantitatively the near-surface layer composition.We also present an innovative method that allows us to distinguish between monolayer and multilayer films of ODPA on silicon oxide surfaces. This method is based on differential surface charging effects in XPS. It was found that variation in the ODPA film thickness causes differential responses of various spectral characteristics to an electrical bias applied to the sample during XPS measurements. Both positive and negative applied biases were found to affect the carbon core-level (C1s) line-shape and intensity in the case of the multilayer ODPA film, whereas line-shapes and intensities of all XPS lines measured for the monolayer film were unaffected by the application of a dc bias in the ±30 V range. 相似文献
996.
Irina Kmit 《Journal of Mathematical Analysis and Applications》2007,335(1):355-370
This paper concerns hyperbolic systems of two linear first-order PDEs in one space dimension with periodicity conditions in time and reflection boundary conditions in space. The coefficients of the PDEs are supposed to be time independent, but allowed to be discontinuous with respect to the space variable. We construct two scales of Banach spaces (for the solutions and for the right-hand sides of the equations, respectively) such that the problem can be modeled by means of Fredholm operators of index zero between corresponding spaces of the two scales. 相似文献
997.
The thermal resistance of a crystal lattice with a monatomic unit cell due to three-phonon scattering processes is investigated in detail theoretically. A general expression for the lattice thermal conductivity is derived from a combined analysis based on: (i) the Boltzmann equation and (ii) data on the heat current autocorrelation function obtained via molecular dynamics simulations in conjunction with the Green–Kubo formalism. It is argued that the phonon gas in a monatomic lattice conducts heat as if it consisted of two distinct parts (two ‘thermal fluids’), so that the lattice thermal conductivity can be decomposed into contributions from these two parts. The origin of the behaviour of the phonon gas, which is explored in the present work, is due to an intrinsic interplay between Umklapp and normal three-phonon scattering processes. New insight into the nature of the lattice thermal conductivity is demonstrated and the results of the present work are in agreement with previous studies in this area. 相似文献
998.
Dr. Sergey V. Ovsyannikov Dr. Maxim Bykov Dr. Sergey A. Medvedev Dr. Pavel G. Naumov Dr. Anton Jesche Dr. Alexander A. Tsirlin Dr. Elena Bykova Dr. Irina Chuvashova Dr. Alexander E. Karkin Dr. Vadim Dyadkin Dr. Dmitry Chernyshov Prof. Dr. Leonid S. Dubrovinsky 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(14):5681-5685
Functional oxides whose physicochemical properties may be reversibly changed at standard conditions are potential candidates for the use in next-generation nanoelectronic devices. To date, vanadium dioxide (VO2) is the only known simple transition-metal oxide that demonstrates a near-room-temperature metal–insulator transition that may be used in such appliances. In this work, we synthesized and investigated the crystals of a novel mixed-valent iron oxide with an unconventional Fe5O6 stoichiometry. Near 275 K, Fe5O6 undergoes a Verwey-type charge-ordering transition that is concurrent with a dimerization in the iron chains and a following formation of new Fe−Fe chemical bonds. This unique feature highlights Fe5O6 as a promising candidate for the use in innovative applications. We established that the minimal Fe−Fe distance in the octahedral chains is a key parameter that determines the type and temperature of charge ordering. This model provides new insights into charge-ordering phenomena in transition-metal oxides in general. 相似文献
999.
Dr. Gerard T. Ducharme Zane LaCasse Tanya Sheth Prof. Irina V. Nesterova Prof. Evgueni E. Nesterov 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8518-8522
Simple, sensitive, and selective detection of specific biopolymers is critical in a broad range of biomedical and technological areas. We present a design of turn-on near-infrared (NIR) fluorescent probes with intrinsically high signal-to-background ratio. The fluorescent signal generation mechanism is based on the aggregation/de-aggregation of phthalocyanine chromophores controlled by selective binding of small-molecule “anchor” groups to a specific binding site of a target biopolymer. As a proof-of-concept, we demonstrate a design of a sensor for EGFR tyrosine kinase—an important target in cancer research. The universality of the fluorescent signal generation mechanism, as well as the dependence of the response selectivity on the choice of the small-molecule “anchor” group, make it possible to use this approach to design reliable turn-on NIR fluorescent sensors for detecting specific protein targets present in the low-nanomolar concentration range. 相似文献
1000.
2‐Nitroveratryl as a Photocleavable Thiol‐Protecting Group for Directed Disulfide Bond Formation in the Chemical Synthesis of Insulin 下载免费PDF全文
John A. Karas Dr. Denis B. Scanlon Prof. Briony E. Forbes Dr. Irina Vetter Prof. Richard J. Lewis Dr. James Gardiner Prof. Frances Separovic Prof. John D. Wade Dr. Mohammed A. Hossain 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9549-9552
Chemical synthesis of peptides can allow the option of sequential formation of multiple cysteines through exploitation of judiciously chosen regioselective thiol‐protecting groups. We report the use of 2‐nitroveratryl (oNv) as a new orthogonal group that can be cleaved by photolysis under ambient conditions. In combination with complementary S‐pyridinesulfenyl activation, disulfide bonds are formed rapidly in situ. The preparation of Fmoc‐Cys(oNv)‐OH is described together with its use for the solid‐phase synthesis of complex cystine‐rich peptides, such as insulin. 相似文献