Zwitterionic comb-like lipid polymers encapsulating linalool for increasing the fragrance retention time

Fragrances are widely used in cosmetics,apparel and detergents.However,the rapid evaporation of the aro ma shortens the useful life of the aromatic product.Therefore,improving the fragrance retention time of aromatic products and prolonging the service life of aromatic products are the key scientific problems that need to be solved in current aromatic products.In this study,zwitterionic comb-like lipid polymers were synthesized to encapsulate the fragrance molecule linalool.The results showed that the zwitterionic comb lipid molecules were capable of encapsulating more linalool than linear lipid molecules.At the same time,the zwitterionic comb-like lipid molecules also limited the slow release rate of the aroma,thereby increasing the fragrance retention time of the nano-fragrance.     

过渡态理论在化学体系中的2个应用实例*

在大学本科一二年级的物理化学教学中,化学动力学章节的学习涉及到对不同时间尺度的认识。本文利用过渡态理论得到的速率常数表达公式,以乙烷分子碳/碳单键旋转和水分子氢键交换的动力学过程为例,对这2个应用实例的动力学过程所发生的时间尺度做出估算。这些时间尺度的估算对于学生理解不同动力学过程的物理图像至关重要,同时也有助于加强学生对重要公式的理解并能够将这些公式在化学体系中灵活运用。     

实时直接分析高分辨质谱技术研究碳硼烷类化合物

该文运用高分辨质谱技术对实时直接分析(Direct analysis in real time,DART)离子化条件下碳硼烷化合物的质谱行为进行了研究,对碳硼烷化合物DART高分辨质谱中所得到的同位素峰簇进行了表征与归属。研究结果表明,选取的碳硼烷化合物在DART负离子条件下均能得到较好的质谱信号,这可能与硼笼结构的“缺电性”有关。含10个B原子的碳硼烷化合物形成的离子同位素峰簇信号中,通常情况下相对丰度最高的同位素峰中含2个10B以及8个11B。将碳硼烷化合物高分辨质谱分析的精确m/z数据信息与图谱中同位素峰轮廓分析相结合,是碳硼烷化合物有效的质谱定性分析与表征策略。     

N_2-DART-Orbitrap中的特征气相离子反应及在西药快速检测中的应用

采用实时直接分析(DART)离子源串联高分辨质谱Orbitrap技术(DART-Orbitrap MS),对8种市售常见西药进行有效成分分析,建立了一种快速、简便、准确测定西药中有效成分的方法.对DART离子源的离子化温度、扫描模式、操作气体种类、辅助溶剂种类及其酸碱性等实验条件进行了优化,得到最佳实验条件.实验结果表明,正谱条件下,采用N_2气作为操作气体时,待测组分准分子离子峰[M+H]+同样具有较高的灵敏度和谱图辨识度.因此,N2气可以替代昂贵的He气作为DART离子源的操作气体用于8种药物有效成分的现场实时检测.该方法具备成本低、快速和操作简便的特点.通过分析待测组分的特征碎片离子,发现了N2-DART离子源中的特征离子反应,包括氧化反应和重排反应.根据获得的特征碎片离子对N_2-DART-MS中发生的反应机理进行推导,并结合理论计算对其进行验证.N_2-DART-MS技术有望应用于复杂基质混合物的现场快速检测中.     

Effect of fluorination on the phase sequence,dielectric and electro-optical properties of ferroelectric and antiferroelectric mixtures

Four multicomponent room temperature mixtures were formulated using a pyrimidine-based achiral matrix as host and four terphenyl-based ester chiral compounds as dopants. Among the four mixtures, two exhibit antiferroelectric and two other exhibit ferroelectric phases at room temperature. Dopant molecules differ from each other by position and number of fluorine atom substitution at the benzoate group of the molecular rigid core. Number and location of fluorine atoms in the dopant structure show significant effect on the phase sequences as well as on different physical properties. All the mixtures found to have moderate spontaneous polarisation, high tilt angle, very fast switching time and low viscosity which are important for liquid crystal-based display applications.     

A fast discontinuous finite element discretization for the space‐time fractional diffusion‐wave equation

In this article, we study fast discontinuous Galerkin finite element methods to solve a space‐time fractional diffusion‐wave equation. We introduce a piecewise‐constant discontinuous finite element method for solving this problem and derive optimal error estimates. Importantly, a fast solution technique to accelerate Toeplitz matrix‐vector multiplications which arise from discontinuous Galerkin finite element discretization is developed. This fast solution technique is based on fast Fourier transform and it depends on the special structure of coefficient matrices. In each temporal step, it helps to reduce the computational work from required by the traditional methods to log , where is the size of the coefficient matrices (number of spatial grid points). Moreover, the applicability and accuracy of the method are verified by numerical experiments including both continuous and discontinuous examples to support our theoretical analysis.© 2017 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 2043–2061, 2017     

The mean of the running maximum of an integrated Gauss–Markov process and the connection with its first-passage time

We find explicit formulae for the mean of the running maximum of conditional and unconditional Brownian motion; they are used to obtain the mean, a(t), of the running maximum of an integrated Gauss–Markov process. Then, we deal with the connection between the moments of its first-passage-time and a(t). As explicit examples, we consider integrated Brownian motion and integrated Ornstein–Uhlenbeck process.     

A stochastic portfolio optimization model with complete memory

In this article, we consider a portfolio optimization problem of the Merton’s type with complete memory over a finite time horizon. The problem is formulated as a stochastic control problem on a finite time horizon and the state evolves according to a process governed by a stochastic process with memory. The goal is to choose investment and consumption controls such that the total expected discounted utility is maximized. Under certain conditions, we derive the explicit solutions for the associated Hamilton–Jacobi–Bellman (HJB) equations in a finite-dimensional space for exponential, logarithmic, and power utility functions. For those utility functions, verification results are established to ensure that the solutions are equal to the value functions, and the optimal controls are also derived.     

Continuity in law with respect to the Hurst index of some additive functionals of sub-fractional Brownian motion

In this article, first, we prove some properties of the sub-fractional Brownian motion introduced by Bojdecki et al. [Statist. Probab. Lett. 69(2004):405–419]. Second, we prove the continuity in law, with respect to small perturbations of the Hurst index, in some anisotropic Besov spaces, of some continuous additive functionals of the sub-fractional Brownian motion. We prove that our result can be obtained easily, by using the decomposition in law of the sub-fractional Brownian motion given by Bardina and Bascompte [Collect. Math. 61(2010):191–204] and Ruiz de Chavez and Tudor [Math. Rep. 11(2009):67–74], without using the result of Wu and Xiao [Stoch. Proc. Appl. 119(2009):1823–1844] by connecting the sub-fractional Brownian motion to its stationary Gaussian process through Lamperti’s transform. This decomposition in law leads to a better understanding and simple proof of our result.     

Error and stability analysis of numerical solution for the time fractional nonlinear Schrödinger equation on scattered data of general‐shaped domains

In present work, a kind of spectral meshless radial point interpolation (SMRPI) technique is applied to the time fractional nonlinear Schrödinger equation in regular and irregular domains. The applied approach is based on erudite combination of meshless methods and spectral collocation techniques. The point interpolation method with the help of radial basis functions is used to construct shape functions which play as basis functions in the frame of SMRPI. It is proved the scheme is unconditionally stable with respect to the time variable in and also convergent by the order of convergence , . In the current work, the thin plate spline are used as the basis functions and to eliminate the nonlinearity, a simple predictor‐corrector (P‐C) scheme is performed. It is shown that the SMRPI solution, as a complex function, is suitable one for the time fractional nonlinear Schrödinger equation. The results of numerical experiments are compared to analytical solutions to confirm the reliable treatment of these stable solutions. © 2016 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 1043–1069, 2017