Responsive Polyelectrolyte Multilayers Assembled at High Ionic Strength with an Unusual Collapse at Low Ionic Strength

Responsive polyelectrolyte multilayers (PEMs) of poly(diallyl dimethyl ammonium chloride) (PDADMAC) and poly(styrene sodium sulfonate) (PSS) with thicknesses between 350 and 400 nm for 11 deposited polyelectrolyte layers were fabricated assembling the polyelectrolytes at 3 M NaCl. When the 3 M NaCl bulk solution is replaced by water, the PEMs release water, approximately a 46% of the total mass, and experience a thickness reduction of more than 200 nm. Changes in thickness and water content are fully reversible. The film recovers its original thickness and water content when it is exposed again to a 3 M NaCl solution. A responsive polymer film is achieved with the capability of swelling at high ionic strength and collapsing in water with variations in thickness of hundred of nanometers.     

实用智能卡操作系统的认证系统

阐述了一种实用的智能卡操作系统MAXCOS的认证系统,包括对持卡人的身份认证、卡与读写设备之间的认证、安全报文传送,对这几种认证机制进行了详细的阐述和分析．     

智能卡操作系统中RSA算法的实现与应用

讨论了RSA算法在IC卡中的应用,以及在Ic卡中实现RsA算法的一种途径,即利用中国剩余定理(cRT)来简化大数乘方取模运算．该方法在Ic卡芯片上已经成功实现．测试结果表明,在Ic卡中运用这种方法实现的RsA算法其解密速度与同等条件下的Des算法的加解密速度相当.     

High Pressure Induced Coil-Globule Transitions of Smart Polymers

Summary: In current work time-resolved optical spectroscopy (TROS) has been used to study coil-globule transitions monitored by the local segmental dynamics of anthracene labeled poly (N-isopropymethacrylamide), PNIPMAM as a function of pressure (0.1 MPa–200 MPa) over a temperature range of 283 K to 333 K. The positions of temperature-induced transition were observed to be independent on molecular weight of polymer at low pressures. The positions of pressure-induced transition were observed to be dependent on molecular weight of polymer at temperatures below LCST at atmospheric pressure. Double globule-coil-globule transition was observed to occur with pressure increasing at temperatures nearly above LCST. All these results along with values of intrinsic viscosity evaluated from values of correlation times measured for globules formed at different pressure/temperature conditions suggest the different mechanisms of compactisation governed by pressure and temperature and, correspondently, the different types of final structures. At low pressures with temperature increasing the compact, well-packed globules are forming via initial interactions between neighboring parts of polymer chain and further collapse. Relatively loosened particles are forming with pressurizing at low temperatures. Interaction between remote along the chain units takes part from the first stage of globule formation. And finally, rather solvated and irregularly twisted particles are forming at high pressure and high temperatures, i.e. at conditions, when both processes are involved.     

Hamilton等参元与智能叠层板的半解析法

根据压电材料修正后的Hellinger-Reissner(H-R)变分原理,建立了各向异性压电材料4节点Hamilton等参元的一般形式．为智能叠层板自由振动问题和带有压电块的叠层悬臂梁的瞬态响应等问题提出了一种新的半解析法．数学模型的基本步骤:将压电层和主体层看成独立的三维体,在平面内离散各层,分别建立各层的方程;根据主体层和压电层在连接界面上广义应力和广义位移的连续条件,联立主体层和压电层的方程得到全结构的控制方程．等参元不限制智能板侧面的几何边界形状、板的厚度和层数,有广泛的应用领域．     

智能板模态传感与控制的数值分析

智能结构技术对空间大型柔性结构 振动控制问题具有重要意义,采用独立模态空间控制技术对压电智能板进行主动振动控制是一种常用方法,以前对这一问题的研究仅限于解析的方法,本文采用有限单元法,设计了新的压电模态传感器与致动器,该方法能够适用于形状及边界条件较为复杂的智能板,算例分析证明了该方法的正确性。     

Trusted Threat Intelligence Sharing in Practice and Performance Benchmarking through the Hyperledger Fabric Platform

Historically, threat information sharing has relied on manual modelling and centralised network systems, which can be inefficient, insecure, and prone to errors. Alternatively, private blockchains are now widely used to address these issues and improve overall organisational security. An organisation’s vulnerabilities to attacks might change over time. It is utterly important to find a balance among a current threat, the potential countermeasures, their consequences and costs, and the estimation of the overall risk that this provides to the organisation. For enhancing organisational security and automation, applying threat intelligence technology is critical for detecting, classifying, analysing, and sharing new cyberattack tactics. Trusted partner organisations can then share newly identified threats to improve their defensive capabilities against unknown attacks. On this basis, organisations can help reduce the risk of a cyberattack by providing access to past and current cybersecurity events through blockchain smart contracts and the Interplanetary File System (IPFS). The suggested combination of technologies can make organisational systems more reliable and secure, improving system automation and data quality. This paper outlines a privacy-preserving mechanism for threat information sharing in a trusted way. It proposes a reliable and secure architecture for data automation, quality, and traceability based on the Hyperledger Fabric private-permissioned distributed ledger technology and the MITRE ATT&CK threat intelligence framework. This methodology can also be applied to combat intellectual property theft and industrial espionage.     

Advances in Asymmetric Wettable Janus Materials for Oil–Water Separation

The frequent occurrence of crude oil spills and the indiscriminate discharge of oily wastewater have caused serious environmental pollution. The existing separation methods have some defects and are not suitable for complex oil–water emulsions. Therefore, the efficient separation of complex oil–water emulsions has been of great interest to researchers. Asymmetric wettable Janus materials, which can efficiently separate complex oil–water emulsions, have attracted widespread attention. This comprehensive review systematically summarizes the research progress of asymmetric wettable Janus materials for oil–water separation in the last decade, and introduces, in detail, the preparation methods of them. Specifically, the latest research results of two-dimensional Janus materials, three-dimensional Janus materials, smart responsive Janus materials, and environmentally friendly Janus materials for oil–water separation are elaborated. Finally, ongoing challenges and outlook for the future research of asymmetric wettable Janus materials are presented.     

复合材料层合板面内压阻效应层合理论研究

应用经典层合板理论和静电学理论,研究了正交异性介质的电导率,压导系数和压阻系数的特性,导出了Ｃａｕｃｈｙ应变空间中压阻系数与压导系之间的关系;建立了平面应力状态下层合板面内压阻效应的层合理论。     

Stimuli-Responsive Particle-Based Amphiphiles as Active Colloids Prepared by Anisotropic Click Chemistry

Amphiphiles alter the energy of surfaces, but the extent of this feature is typically constant. Smart systems with amphiphilicity as a function of an external, physical trigger are desirable. As a trigger, the exposure to a magnetic field, in particular, is attractive because it is not shielded in water. Amphiphiles like surfactants are well known, but the magnetic response of molecules is typically weak. Vice-versa, magnetic particles with strong response to magnetic triggers are fully established in nanoscience, but they are not amphiphilic. In this work colloids with Janus architecture and ultra-small dimensions (25 nm) have been prepared by spatial control over the thiol-yne click modification of organosilica-magnetite core–shell nanoparticles. The amphiphilic properties of these anisotropically modified particles are proven. Finally, a pronounced and reversible change in interfacial stabilization results from the application of a weak (<1 T) magnetic field.