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31.
Abstract

For the first time a systematic study was performed for the phosphorylation of 1,2,3-triols with total amides of phosphorous acid. The initial-matrix-structure dependence of phospholane-phospholane bicyclophosphites was found and investigated. The introducing of terminal substituents into a triol molecule was shown to essentially increase their stability.  相似文献   
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Spin glass is the simplest disordered system that preserves the full range of complex collective behavior of interacting frustrating elements. In the paper, we propose a novel approach for calculating the values of thermodynamic averages of the frustrated spin glass model using custom deep neural networks. The spin glass system was considered as a specific weighted graph whose spatial distribution of the edges values determines the fundamental characteristics of the system. Special neural network architectures that mimic the structure of spin lattices have been proposed, which has increased the speed of learning and the accuracy of the predictions compared to the basic solution of fully connected neural networks. At the same time, the use of trained neural networks can reduce simulation time by orders of magnitude compared to other classical methods. The validity of the results is confirmed by comparison with numerical simulation with the replica-exchange Monte Carlo method.  相似文献   
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The dynamics of finite dimension open quantum systems is studied with the help of the simplest possible form of projection operators, namely the ones which project only onto one-dimensional subspaces. The simplicity of the action of the projection operators always leads to an analytical solution of the dynamical master equation, even in the non-Markovian case, in any perturbative order. The analytical solution correctly reproduces the short-time dynamics, and can be used to recursively recover the dynamics for an arbitrary time interval with arbitrary precision. The necessary number of relevant degrees of freedom to completely characterise an open quantum system is , where n is the dimension of the Hilbert space of the open system. The method is illustrated by two examples, the relaxation of a qubit in a thermal bath and the dynamics of two interacting qubits in a common environment.https://doi.org/10.1209/0295-5075/113/20004  相似文献   
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An approach to the synthesis of spirocyclic diazirines from cyclic ketones was examined on a series of carbo- and heterocyclic substrates containing the amine or carboxylic acid moiety. A mini-library of stereochemically diverse functionalized spirocyclic diazirines was synthesized on a multigram scale with 30–81 % yield.  相似文献   
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The formation of amyloid fibrils is one of the variants of the self-organization of polypeptide chains. For the amyloid aggregation, the solution must be oversaturated with proteins. The interface of the liquid (solution) and solid (vessel walls) phases can trigger the adsorption of protein molecules, and the resulting oversaturation can initiate conformational transitions in them. In any laboratory experiment, we cannot exclude the presence of surfaces such as the walls of vessels, cuvettes, etc. However, in many works devoted to the study of amyloid formation, this feature is not considered. In our work, we investigated the behavior of the Aβ 1-40 peptide at the water–glass, water–quartz, and water–plastic interface. We carried out a series of simple experiments and showed that the Aβ 1-40 peptide is actively adsorbed on these surfaces, which leads to a significant interaction and aggregation of peptides. This means that the interface can be the place where the first amyloid nucleus appears. We suggest that this effect may also be one of the reasons for the difficulty of reproducing kinetic data when studying the aggregation of the amyloid of the Aβ 1-40 peptide and other amyloidogenic proteins  相似文献   
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The ternary Tb2–xNdxZn17–yNiy (x = 0.5, y = 4.83) disordered phase belongs to the structural family based on the rhombohedral Th2Zn17 structure type. The structure is maximally disordered since all the sites are occupied by statistical mixtures of atoms. The Tb/Nd mixture of atoms occupies the 6c site (site symmetry 3m). The statistical mixtures Ni/Zn consisting of more Ni atoms are located in the 6c and 9d (symmetry .2/m) sites. In the following 18f (site symmetry .2) and 18h (site symmetry .m) sites are located Zn/Ni statistical mixtures which consist of more Zn atoms. Zn/Ni atoms form three-dimensional networks with hexagonal channels that fill statistical mixtures of Tb/Nd and Ni/Zn. The Tb2–xNdxZn17–yNiy compound belongs to the family of intermetallic phases capable of absorbing hydrogen. In the structure, there are three types of voids, namely, 9e (site symmetry .2/m), 3b (site symmetry m) and 36i (site symmetry 1), in which hydrogen can be inserted, and the maximum total absorption capacity can reach 1.21 wt% H2. Electrochemical hydrogenation shows that the phase absorbs 1.03% of H2, which indicates partial filling of the voids with H atoms.  相似文献   
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Polymer composites of a segregated network structure are dielectric polymer granules coated with electrically conductive nanoparticles at a low content, the quantity of the junctions between the granules determines the composites' mechanical properties, and the percolation network formed by the nanoparticles determines the electrical conductivity. Here, the morphology and electron-transport properties in reduced graphene oxide (rGO)-filled composites with a segregated structure based on polyvinyl chloride (PVC), poly(vinylidene fluoride-co-tetrafluoroethylene) (P(VDF-TFE)), and ultrahigh-molecular-weight polyethylene (UHMWPE) are studied. Optical and electron microscopies study of the microtome-formed cross sections have shown the morphology to be dependent on the polymer—the thinnest rGO layers are in UHMWPE-based composites, the thicker rGO layers are in PVC- and P(VDF-TFE)-based ones. The electrical conduction of the composites and the rGO-paper occurs through the same hopping conduction mechanisms within the wide temperature range, which allows to use the composites in applications where pure rGO is considered. Owing to thicker rGO layers open to the environment, PVC- and P(VDF-TFE)-based composites are more attractive, rather than the UHMWPE ones, in applications where layered materials are needed, for example, in lithium-ion batteries or supercapacitors. The UHMWPE-based composites look more promising as electrically conductive materials when mechanical strength is important.  相似文献   
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