Water models for interfacial water simulations

Interfacial water is of fundamental importance in many technological fields, such as biological processes, chemical reactions and lubrications. A prevalent way to study the structure and dynamics of interfacial water is carrying out molecular dynamics simulations with empirical potential water models. However, discrepant results have been reported due to their different charge geometries and target properties. Here we investigated the interfacial water structures on smooth surfaces of varying hydrophobicity at low temperatures by comprehensive molecular dynamics simulations with the prevailing water models. It is shown that the choice of the water model can significantly change the water structure on the hydrophilic surface, while has a minor effect on the contact angle on a hydrophobic surface. Furthermore, zero-dimensional ice pyramids and one-dimensional icicles were formed under the regulation of external charges injected to the substrate or imposed electric field, respectively. These results offer new insights into the water structures on different surfaces and reasonable choice of parameters in molecular simulations, and the development of water models.     

A promising parenting intervention in foster care.

The purpose of this study was to evaluate the effectiveness of a 2-component intervention for biological and foster parent (pairs) to improve parenting practices, co-parenting, and child externalizing problems. Participants were biological and foster parents (N = 128) of primarily neglected children (ages 3 to 10 years) placed in regular foster homes. Biological and foster parents were randomly assigned in pairs to the intervention (n = 80) or a usual care (n = 48) condition. Intervention families received a 12-week parenting course (Incredible Years) and a newly developed co-parenting component. Key findings included significant gains in positive parenting and collaborative co-parenting for both biological and foster parents at the end of the intervention. At follow-up, intervention parents sustained greater improvement in positive parenting, showed gains in clear expectations, and reported a trend for fewer child externalizing problems. Findings supported the feasibility of offering joint parenting training to meet the needs of participating families and demonstrated that the co-parenting construct applied to families in the foster care system was amenable to intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functionalizations of boron nitride nanostructures

Boron nitride(BN) nanomaterials share the same atomic structures as their carbon counterparts, with mechanical and thermal properties second only to carbon counterparts. Especially, the iconicity of B-N bonds results in exceptionally high thermal stability and corrosion resistance, making BN nanomaterials a compelling contender for fabricating devices that can operate under harsh environments. However, all pristine BN nanomaterials are electric insulators and lack semiconductive functionality.How to efficiently regulate the electronic properties of BN nanomaterials has impeded the way of delivering their potential into applications. Here, we report an overview of key progress in functionalizing BN nanostructures by means of multi-physical-field coupling at nanoscale. In particular, we present how the chemical doping, electric fields, elastic strains and interfaces can modify the band structures and hence lead to narrowed bandgap and even magnetism in various BN nanostructures. We also discuss the effect of these modulation methods on charge carrier motility as well as potential challenges of their experimental implementation. Without applied doping, strain and electric field, employing inherent BN polarity to form electrically polarized interfaces is proposed to functionalize BN nanostructures towards controlled electronic properties combined with high carrier motility. We finally discuss recent progress of experimental synthesis of quality h-BN samples in large area.     

一个组播分布式访问控制系统

鉴于简单公钥基础设施技术在授权方面所具备的优点,提出了基于简单公钥基础设施技术的组播分布式访问控制系统,设计了组播分布式访问控制系统鉴别和授权协议,并进行了模拟仿真实验及性能评价。与其他方案相比,组播分布式访问控制系统具备分布式、支持非对称组播、授权委托和隐私保护、边缘路由器计算开销小等特性。