Mechanical,dielectric and microwave absorption properties of carbon black (CB) incorporated SiO<Subscript>2f</Subscript>/PI composites

Structural and functional integrated absorbing materials have received extensive attention in recent years. Single-layer absorbing material composites in X and Ku bands (8.2–18 GHz) were prepared by using different proportion of carbon black (CB) incorporated quartz glass fiber reinforced polyimide resin (SiO_2f/PI). The morphology, mechanical, dielectric and microwave absorbing properties of the composites were investigated. Different contents of CB with different distributions were observed according to the fractural morphology of the composites. When the CB content is up to 8 wt%, the flexural strength of the composite reaches a maximum value of 705?±?5 MPa. The real and imaginary parts of complex permittivity both show an increasing trend with the CB content increase. Meanwhile, the real and imaginary parts decrease with the increase of frequency, exhibiting frequency-dependent dielectric response. The reflection loss of the composite was calculated based on the transmission line theory, which is in a good agreement with the experiment.     

Selective CO2 Capture and High Proton Conductivity of a Functional Star‐of‐David Catenane Metal–Organic Framework

Network structures based on Star‐of‐David catenanes with multiple superior functionalities have been so far elusive, although numerous topologically interesting networks are synthesized. Here, a metal–organic framework featuring fused Star‐of‐David catenanes is reported. Two triangular metallacycles with opposite handedness are triply intertwined forming a Star‐of‐David catenane. Each catenane fuses with its six neighbors to generate a porous twofold intercatenated gyroid framework. The compound possesses exceptional stability and exhibits multiple functionalities including highly selective CO₂ capture, high proton conductivity, and coexistence of slow magnetic relaxation and long‐range ordering.     

Positive Charge Holes Revealed by Energy Band Theory in Multiphase TixO2x-1 and Exploration of its Microscopic Electromagnetic Loss Mechanism

Although numerous experimental investigations have been carried out on the problem of defect engineering in semiconductor absorbers, the relationship among charge carrier, defects, heterointerfaces, and electromagnetic (EM) wave absorption has not been established systematically. Herein, the new thermodynamic and kinetic control strategy is proposed to establish multiphase Ti_xO_2x−1 (1 ≤ x ≤ 6) through a hydrogenation calcination. The TiOC-900 composite shows the efficient EM wave absorption capability with a minimum reflection loss (RL_min) of −69.6 dB at a thickness of 2.04 mm corresponding to an effective absorption bandwidth (EAB) of 4.0 GHz due to the holes induced conductance loss and heterointerfaces induced interfacial polarization. Benefiting from the controllable preparation of multiphase Ti_xO_2x−1, a new pathway is proposed for designing high-efficiency EM wave absorbing semiconducting oxides. The validity of the method for adopting energy band theory to explore the underlying relations among charge carriers, defects, heterointerfaces, and EM properties in multiphase Ti_xO_2x−1 is demonstrated for the first time, which is of great importance in optimizing the EM wave absorption performance by electronic structure tailoring.     

Vortex Matter in a Two-Band SQUID-Shaped Superconducting film

In the present work, we studied the magnetization, vorticity, Cooper pairs density, and the spatial distribution of the local magnetic field in a three-dimensional superconductor with a SQUID geometry (a square with a central hole connected to the outside vacuum through a very thin slit). Our investigation was carried out in both the Meissner-Ochsenfeld and the Abrikosov state solving the two-band Ginzburg-Landau equations considering a Josephson coupling between the bands. We found a non-monotonic vortex behavior and the respective generation of vortex clusters due to the Josephson coupling used between condensates.

     

基于滑模控制的转炉炉口微差压控制系统研究

转炉烟气净化与煤气回收系统中,炉口微差压的精确控制至关重要。介绍炉口微差压控制系统工作原理,提出了基于趋近律的滑模变结构微差压控制系统设计方案和控制策略。     

少量乙醇对L沸石合成的影响

以白炭黑和偏铝酸钾为原料,添加少量乙醇合成L沸石.产物用XRD和SEM进行表征.系统研究了晶化时间、晶化温度、合成原料配比等参数对产物纯度和结晶度的影响.发现在合成体系中添加少量乙醇有利于合成纯度高、粒径较大、结晶度较高的L沸石.优化的晶化温度是130～150℃,更高的温度容易生成杂晶.延长晶化时间、提高硅铝比有利于提高产品的结晶度,但提高合成的碱度则使产品结晶度降低.     

MD4：一种综合的跨本体实体语义相似度计算方法*

面向广域分布环境下信息资源共享与服务的需要,设计了基于本体的元数据模型,并在MD3模型的基础上给出了一种基于该元数据模型的跨本体的语义相似度计算方法——MD4模型。MD4充分利用本体对实体的描述信息,重点讨论了实体名称、实体属性、实体语义环境以及实体实例等相似度的计算,把MD3模型扩展到MD4模型,使得信息资源实体间语义相似度的计算更全面、精确。     

浅谈沥青路面罩面维修中平整度的控制

由于旧路的固有特点,沥青路面罩面维修工程的平整度控制不同于新建路面的平整度控制。其影响因素及其处治方式更加复杂。文中分析了导致路面不平整的各种因素,并针对不同的情况提出了在路面维修中的处治措施。     

浅析721型分光光度计故障及其排除

列举了７２１型分光光度计常见的小故障，分析了故障产生的原因，介绍了排除故障的方法。     

掺盐沥青胶浆性能试验研究

盐蚀环境对沥青路面耐久性的劣化作用具有普遍性和直接性.采用掺盐加速侵蚀试验,以针入度、软化点、延度、布氏黏度与抗剪强度等为评价指标,研究不同种类盐分对沥青性能影响规律;借助SEM和红外光谱微观分析手段,探讨盐分劣化沥青性能作用机理.结果表明,在较短盐蚀龄期内,内掺氯盐与硫酸盐使沥青胶结料呈硬化趋势,而内掺醋酸盐则呈软化趋势;盐分-沥青界面以物理作用为主.研究成果可为富盐地区沥青混合料材料组成设计提供有益参考.