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961.
The ground state hydrogen conformations and vibrational analysis of 3-deazauracil (3DAU) and 6-azauracil (6AU) tautomers (4-enol and 2,4-diol forms) have been calculated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods with 6-311++G(d,p) basis set level. The calculations have shown that the most probably preferential tautomer of 3DAU and 6AU are the 4-enol form, which gives best fit to the corresponding experimental data. The ground state conformer of the 2,4-diol form has two O-H bonds which are oriented externally and internally (to the N-H bond). The vibrational analyses of the ground state conformer of each tautomeric form of 3DAU and 6AU were done and their optimized geometry parameters (bond lengths and bond angles) were given. Furthermore, from the correlations values it was concluded that the B3LYP method is superior to the HF method for both the vibrational frequencies and the geometric parameters. 相似文献
962.
Tatiana A. Kornilova Rafael R. Kostikov Alexander F. Khlebnikov Igor G. Zenkevich 《Journal of Physical Organic Chemistry》2018,31(7)
Rate constants of thermal isomerization of 6‐phenyl‐1,5‐diazabicyclo[3.1.0]hexane into 1‐(benzyl)‐4,5‐dihydro‐1H‐pyrazole at convection and microwave heating in toluene and chlorobenzene (solvents) were determined within the temperature range 90°C to 120°С. These data were used for the calculation of activation parameters of isomerization. It is shown that microwave heating increases the rate constants at the same temperature by a factor of 2 to 2.5 as compared with those using convection heating. The reason is that the effective temperature of microwave heating exceeds that of convection heating by 6°C to 9°С in toluene and by 12°C to 20°С in chlorobenzene as solvent. 相似文献
963.
为了探索影响Bi_2WO_6光催化性能的内在机制,采用密度泛函理论(DFT)计算和实验研究了非化学计量和氧空位对Bi_2WO_6晶体结构、电子结构和显微结构的影响.采用溶剂热法合成了具有氧空位的非化学计量Bi_xWO_6(x=1.81,1.87,1.89,1.92,2.01)光催化剂.DFT计算结果表明,氧空位的存在可显著减小Bi_2WO_6的带隙,有利于光生电子的生成.实验结果表明,当Bi元素的含量小于化学计量比时,Bi_2WO_6的晶体结构发生了微小变形,Bi元素含量对Bi_2WO_6的显微结构影响不大,但会影响产品氧空位的含量和光吸收性能,并有效抑制电子空穴的复合.Bi_(1.89)WO_6产品的光催化性能最佳,可见光照射180 min后,可降解98%的罗丹明B.采用适当方法,使产品具有氧空位和非化学计量是获得高光催化活性材料的一种有效方法. 相似文献
964.
The fluorescence quenching of Rhodamine 6G (R6G) by graphene oxide (GO) was interrogated by R6G fluorescence measurements using a set of controlled GO samples with varied C/O ratios as the quencher.The carbonyl groups on the GO nanosheet turned to play a dominant role in quenching the R6G fluorescence.The quenching in the static regime can be described by the \"sphere of action\" model.The significant absorption of the R6G fluorescence by the ground-state complex formed between R6G and GO was identified to be responsible for the static quenching.This work offers helpful insights into the fluorescence quenching mechanisms in the R6G/GO system. 相似文献
965.
Hongyu Ye 《Mathematical Methods in the Applied Sciences》2017,40(4):1032-1043
In this paper, we consider the following coupled Schrödinger system with critical exponent: where is a smooth bounded domain, λ > 0,μ≥0, and . Under certain conditions on λ and μ, we show that this problem has at least one positive least energy solution. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
966.
In this paper, we study the following generalized quasilinear Schrödinger equation where N≥3, is a C1 even function, g(0) = 1 and g′(s) > 0 for all s > 0. Under some suitable conditions, we prove that the equation has a ground state solution and infinitely many pairs ±u of geometrically distinct solutions. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
967.
Optical vortices as topological objects exist ubiquitously in nature. In this paper, we use the principle of variational method and mountain pass lemma to develop some existence theorems for the stationary vortex wave solution of a coupled nonlinear Schrödinger equations, which describe the possibility of effective waveguiding of a weak probe beam via the cross‐phase modulation‐type interaction. The main goal is to obtain a positive solution, of minimal action if possible, with all vector components not identically zero. Additionally, as demanded by beam confinement, we prove the exponential decay of the soliton amplitude at infinity. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
968.
Ruchi Ruchi Nurhayat Ispir P. N. Agrawal 《Mathematical Methods in the Applied Sciences》2017,40(16):5687-5706
Ren and Zeng (2013) introduced a new kind of q‐Bernstein–Schurer operators and studied some approximation properties. Acu et al. (2016) defined the Durrmeyer modification of these operators and studied the rate of convergence and statistical approximation. The purpose of this paper is to introduce a Kantorovich modification of these operators by using q‐Riemann integral and investigate the rate of convergence by means of the Lipschitz class and the Peetre's K‐functional. Next, we introduce the bivariate case of q‐Bernstein–Schurer–Kantorovich operators and study the degree of approximation with the aid of the partial modulus continuity, Lipschitz space, and the Peetre's K‐functional. Finally, we define the generalized Boolean sum operators of the q‐Bernstein–Schurer–Kantorovich type and investigate the approximation of the Bögel continuous and Bögel differentiable functions by using the mixed modulus of smoothness. Furthermore, we illustrate the convergence of the operators considered in the paper for the univariate case and the associated generalized Boolean sum operators to certain functions by means of graphics using Maple algorithms. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
969.
João Marcos do Ó José Carlos de Albuquerque 《Mathematical Methods in the Applied Sciences》2017,40(18):6864-6879
In this paper, we study the existence of a positive ground state solution to the following coupled system of nonlinear Schrödinger equations: where the nonlinearities f1(x,s) and f2(x,s) are superlinear at infinity and have exponential critical growth of the Trudinger‐Moser type. The potentials V1(x) and V2(x) are nonnegative and satisfy a condition involving the coupling term λ(x), namely, λ(x)2<δ2V1(x)V2(x) for some 0<δ<1. For this purpose, we use the minimization technique over the Nehari manifold and strong maximum principle to get a positive ground state solution. Moreover, by using a bootstrap argument and Lq‐estimates, we get regularity and asymptotic behavior. 相似文献
970.
In this paper, we study constraint minimizers of the following L 2?critical minimization problem: where E (u ) is the Schrödinger‐Poisson‐Slater functional and N denotes the mass of the particles in the Schrödinger‐Poisson‐Slater system. We prove that e (N ) admits minimizers for and, however, no minimizers for N >N ?, where Q (x ) is the unique positive solution of in . Some results on the existence and nonexistence of minimizers for e (N ?) are also established. Further, when e (N ?) does not admit minimizers, the limit behavior of minimizers as N ↗N ? is also analyzed rigorously. 相似文献