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11.
12.
Kyrylo Klimenko Victor Kuz'min Liudmila Ognichenko Leonid Gorb Manoj Shukla Natalia Vinas Edward Perkins Pavel Polishchuk Anatoly Artemenko Jerzy Leszczynski 《Journal of computational chemistry》2016,37(22):2045-2051
A model developed to predict aqueous solubility at different temperatures has been proposed based on quantitative structure–property relationships (QSPR) methodology. The prediction consists of two steps. The first one predicts the value of k parameter in the linear equation , where Sw is the value of solubility and T is the value of temperature. The second step uses Random Forest technique to create high‐efficiency QSPR model. The performance of the model is assessed using cross‐validation and external test set prediction. Predictive capacity of developed model is compared with COSMO‐RS approximation, which has quantum chemical and thermodynamic foundations. The comparison shows slightly better prediction ability for the QSPR model presented in this publication. © 2016 Wiley Periodicals, Inc. 相似文献
13.
V. M. Bzhezovskii N. N. Il’chenko M. B. Chura L. G. Gorb L. M. Yagupol’skii 《Russian Journal of General Chemistry》2005,75(1):86-93
The potential functions of internal rotation around the C
-S bond in the C6H5S(O)CH3 and C6H5S(O)CF3 molecules were obtained by ab initio MP2(full)/6-31+G* calculations. The stationary points were identified by solving the vibrational problems. The structures in which the plane of the C
-S-C
bonds is approximately perpendicular to the benzene ring plane correspond to the energy minimum. The barriers to rotation around the C
-S bond, corrected for the zero-point vibration energy, are 21.29 [C6H5S(O)CH3] and 28.98 [C6H5S(O)CF3] kJ mol−1. The bond angles (deg) are as follows: 95.7 (CSC), 107.1 (C
SO), 106.3 (C
SO) in C6H5S(O)CH3; 93.5 (CSC), 108.2 (C
SO), 105.2 (C
SO) in C6H5S(O)CF3. The bond lengths are as follows (Å): 1.520 (S=O), 1.804 (C
-S), 1.810 (C
-S) in C6H5S(O)CH3; 1.507 (S=O), 1.799 (C
-S), 1.870 (C
-S) in C6H5S(O)CF3. According to the results of NBO calculations, the formally double S=O bond consists of a strongly polarized covalent σ bond (S→O) and an almost ionic bond. An increase in the S=O bond multiplicity relative to a single bond is mainly due to hyperconjugation by the mechanism n(O)→σ*(C
-S) and n(O)→σ*(C
-S) and, to a lesser extent, by interaction of the oxygen lone electron pairs with the Rydberg orbitals of the S atoms, characterized by a large contribution of the d component.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 96–104.Original Russian Text Copyright © 2005 by Bzhezovskii, Il’chenko, Chura, Gorb, Yagupol’skii. 相似文献
14.
Close DM Crespo-Hernández CE Gorb L Leszczynski J 《The journal of physical chemistry. A》2005,109(41):9279-9283
In the present study the ionization energy thresholds (IET's) of uracil and thymine have been calculated (with the B3LYP, PMP2, and P3 levels of theory using the standard 6-31++G(d,p) basis set) with one to three water molecules placed in the first hydration shell. Then (B3LYP) polarizable continuum model (PCM) calculations were performed with one to three waters of the hydration shell included. Calculations show there is a distinct effect of microhydration on uracil and thymine. For uracil, one added water results in a decrease in the IET of about 0.15 eV. The second and third water molecules cause a further decrease by about 0.07 eV each. For thymine, the first water molecule is seen to decrease the IET by about 0.1 eV, while the second and third water molecules cause a further decrease of less than 0.1 eV each. The changes in IET calculated here for thymine with one to three waters of hydration are smaller than the experimental values determined by Kim et al. (Kim, S. K.; Lee, W.; Herschbach, D. R. J. Phys. Chem. 1996, 100, 7933). Preliminary results presented here indicate that the experimental results may involve keto-enol tautomers of thymine. The results of placing the microhydrated structures of uracil and thymine in a PCM cavity was seen to make very little difference in the IET when compared to the IET of ordinary uracil or thymine in a PCM cavity. The implications are that accurate calculations of the IET's of uracil and thymine can be obtained by simply considering long-range solvation effects. 相似文献
15.
Evgeniya V. Polyakova Olga V. Shuvaeva Olga S. Koshcheeva Yuliya E. Tyutereva Ivan P. Pozdnyakov 《Electrophoresis》2021,42(6):719-724
Arsenic aromatic compounds including p-arsanylic acid (pASA) are still widely used in a number of countries as the feed additives in animal breeding resulting in its entering the environment. Under the influence of oxidizing agents or UV radiation, pASA undergoes transformations leading to generation of inorganic arsenic species that are more mobile and toxic than organic ones. On the one hand, an approach based on the treatment of contaminated waters by UV irradiation seems perspective for their detoxification, but the feasibility of this approach depends on the composition of the products forming as a result of photodegradation. In the present work, a CZE was applied for the study of the pASA degradation process during stationary (308 nm) photolysis in the presence of Fe(III)-oxalate complex. A developed assay allowed controlling the parent compounds and also As-containing products of pASA degradation, presented mainly by arsenate and arsenite ions. It was found that the main inorganic derivatives of the pASA photolytic conversions are presented by arsenate and arsenite ions whose ratio depends on the initial amount of pASA and reaction conditions. 相似文献
16.
17.
Valeriy Hrygorovych Samoylenko Yuliya Ivanivna Samoylenko 《Journal of Mathematical Sciences》2014,200(3):358-373
The paper deals with constructing the asymptotic solution to the singularly perturbed Korteweg–de Vries equation with variable coefficients. The notion of an asymptotic multiphase Σ-solution is proposed, and an algorithm of its construction in a neighborhood of the point t = 0 is given. Some theorems concerning the exactness, with which such local asymptotic solution satisfies the equation under study are proved. 相似文献
18.
19.
In the present paper we consider and study numerically two systems based on model FitzHugh–Nagumo neurons, where in the presence of periodic modulation of parameters it is possible to implement chaotic dynamics on the attractor in the form of a Smale–Williams solenoid in the stroboscopic Poincaré map. In particular, hyperbolic chaos characterized by structural stability occurs in a single neuron supplemented by a time-delay feedback loop with a quadratic nonlinear element. 相似文献
20.
Marco?Dozzi Yuriy?Kozachenko Yuliya?Mishura Kostiantyn?RalchenkoEmail authorView authors OrcID profile 《Statistical Inference for Stochastic Processes》2018,21(1):21-52
We construct the least-square estimator for the unknown drift parameter in the multifractional Ornstein–Uhlenbeck model and establish its strong consistency in the non-ergodic case. The proofs are based on the asymptotic bounds with probability 1 for the rate of the growth of the trajectories of multifractional Brownian motion (mBm) and of some other functionals of mBm, including increments and fractional derivatives. As the auxiliary results having independent interest, we produce the asymptotic bounds with probability 1 for the rate of the growth of the trajectories of the general Gaussian process and some functionals of it, in terms of the covariance function of its increments. 相似文献