溴取代苯甲酰胺类衍生物的合成及其应用

以氯虫苯甲酰胺(KC)为先导,以烯丙胺为原料,在不饱和双键上引入溴原子,设计并合成了一系列结构新颖的邻氨基苯甲酰胺类衍生物,其结构均经核磁共振氢谱确证。初步杀虫活性测试结果表明,在质量浓度为1μg·mL-1时,部分化合物对小菜蛾(Plutella xylostella)有杀虫活性。     

苯胺类缓蚀剂的量子化学研究

用量子化学半经验计算方法CNDO/2程序,研究了苯胺类缓蚀剂的电子性质与缓蚀性能的关系。结果表明质子化的胺基是苯胺衍生物与金属作用的活性部位。提出了该类分子作为酸性介质中金属缓蚀剂在铁表面形成吸附膜的作用机理。     

A tree approach to options pricing under regime-switching jump diffusion models

A simple, efficient tree is developed to price options in a very general regime-switching jump diffusion model. Under this model, the switching rates of the switching process depend on the underlying stock price process. Sufficient conditions that guarantee the positivity of branch probabilities are provided. Using the regime-switching tree, we approximate Heston's stochastic volatility model with an additional jump component. Finally, we illustrate the effectiveness of the tree method by several numerical examples.     

A pseudo-spectral scheme for the approximate solution of a time-fractional diffusion equation

We consider an initial-boundary-value problem for a time-fractional diffusion equation with initial condition u₀(x) and homogeneous Dirichlet boundary conditions in a bounded interval [0, L]. We study a semidiscrete approximation scheme based on the pseudo-spectral method on Chebyshev–Gauss–Lobatto nodes. In order to preserve the high accuracy of the spectral approximation we use an approach based on the evaluation of the Mittag-Leffler function on matrix arguments for the integration along the time variable. Some examples are presented and numerical experiments illustrate the effectiveness of the proposed approach.     

A new high accuracy method for two-dimensional biharmonic equation with nonlinear third derivative terms: application to Navier–Stokes equations of motion

In this paper, we propose a new compact fourth-order accurate method for solving the two-dimensional fourth-order elliptic boundary value problem with third-order nonlinear derivative terms. We use only 9-point single computational cell in the scheme. The proposed method is then employed to solve Navier–Stokes equations of motion in terms of streamfunction–velocity formulation, and the lid-driven square cavity problem. We describe the derivation of the method in details and also discuss how our streamfunction–velocity formulation is able to handle boundary conditions in terms of normal derivatives. Numerical results show that the proposed method enables us to obtain oscillation-free high accuracy solution.     

Controllability of Fractional Order Stochastic Differential Inclusions with Fractional Brownian Motion in Finite Dimensional Space

In this paper, sufficient conditions are formulated for controllability of fractional order stochastic differential inclusions with fractional Brownian motion (fBm) via fixed point theorems, namely the Bohnenblust-Karlin fixed point theorem for the convex case and the Covitz-Nadler fixed point theorem for the nonconvex case. The controllability Grammian matrix is defined by using Mittag-Leffler matrix function. Finally, a numerical example is presented to illustrate the efficiency of the obtained theoretical results.      

Recent Progress of Bismuth Effect on All-Inorganic Lead-Free Metal Halide Derivatives: Crystals Structure,Luminescence Properties,and Applications

Bismuth (Bi³⁺)-included lead-free metal halide (LFMH) materials attract much attention in lighting, display, photodetectors, X-ray detectors, and photovoltaic fields, due to the tunable luminescence and optoelectronic performance in response to crystal and electronic structure, morphology, and particle sizes. This review summarizes Bi³⁺-included LFMH materials about their preparation approach, crystal and electronic structure properties, luminescence performance, and emerging applications. Notably, Bi³⁺ ions not only can act as framework cation to construct stable LFMH structure, but can also incorporate into LFMH materials as activators or sensitizers to generate remarkable luminescence tuning and band engineering. The Bi³⁺ effect on the luminescence and optoelectronic properties of LFMH materials, including, promotion of exciton localization, enhancement of light absorption in near-ultraviolet region, action as sensitizer ions to transfer energy to rare earth or transition metal ions and emission of highly-efficient light is systematically summarized. The proposed structure-luminescence relationship offers guidance for the optimization of current Bi³⁺-included LFMH materials and the exploitation of new LFMH derivatives.     

新型咔唑衍生物密度泛函理论的研究

运用量子化学中的密度泛函和含时密度泛函理论法,计算1种新型咔唑衍生物,以探讨其几何构型、电子结构、前线分子轨道和电子光谱性质。计算结果表明当2-(4-吡啶基)乙烯基的反式构型与咔唑环作用时比顺式稳定,引入取代基后使化合物的HOMO和LUMO之间的能隙降低,吸收光谱红移。电子被激发时,电子从咔唑环向吡啶环转移,说明新型咔唑类化合物具有很好的光学性能,可以作为空穴传输材料。     

面向控制的分数阶微分模型的快速数值计算

求解分数阶控制系统的关键在于如何快速精确地计算分数阶微分.针对短记忆法和变步长记忆法的计算精度和计算复杂性顾此失彼的矛盾,本文提出了一种恒权重记忆法,它不舍弃历史数据,而是采用常值权重后全部记忆.在每个后继的采样周期,只需把新的数据简单叠加到历史数据上来考虑,从而极大地提高了计算精度和降低了计算复杂性,且有效地化解了两...