有机物单层分散在相关材料制备中的应用

与无机氧化物和盐类在载体表面自发单层分散相类似, 许多有机物也可以在载体表面自发单层分散.有机物在载体表面单层分散行为和分散后的存在状态与有机物分子形状和结构特点及载体表面性质和孔结构有关. 利用有机物在载体表面的单层分散, 可以设计制备具有优异性能的材料. 本文简要综述了近年来这方面研究工作取得的相关进展, 主要介绍了有机物单层分散在碳/氧化物复合物、氧化物和薄壁中孔碳材料的制备和织构调控方面的一些应用实例. 单层分散的有机物热分解后可在载体表面形成均匀的薄碳层, 以无机多孔氧化物为载体可制备出包覆均匀碳薄层的碳/氧化物复合物, 这种碳/氧化物复合物在染料吸附、催化剂载体和光催化方面显现出好的性能. 以溶胶-凝胶法制备氧化物时, 分散的有机物可以隔离溶胶颗粒, 从而制备出高比表面积的氧化物并可对孔容进行调控, 以此方法制备的γ-氧化铝比表面积可达506 m²·g^-1. 在惰性气氛中加热上述碳/氧化物复合物, 碳层可抑制氧化物的相变; 而在氧气中, 碳层燃烧发热会促进相变, 由此可快速制备超细α-氧化铝. 包覆均匀碳薄层的氧化物载体对碳起支撑作用, 在将氧化物溶解去除后, 可便捷制得高比表面积、大孔容、高中孔率的薄壁中孔碳材料, 碳材料的形貌、孔径分布等可通过选用不同织构的氧化物载体进行调控.     

中国传统学术视阈中的历史与历史哲学

从中国传统学术的视阈入手，梳理与辨析历史和历史哲学的内涵与外延。考察历史一词的多重含义；指出西方历史哲学乃根据对历史的两分法，即历史事实和历史著述，而有“思辨的历史哲学”和“分析的历史哲学”两大流派；进而指出中国古代对历史有一三分法，即史事、史文、史义，认为史义即为中国的历史哲学，同时史义又包含有“历史之大义”与“吾心之精义”两部分内容。     

电气线路互联系统线缆抗高空核电磁脉冲耦合效应

高空核电磁脉冲（HEMP）对电子设备的耦合途径主要有两方面：一方面是通过装备（产品）上的天线耦合通道进入到电子系统内的“前门耦合”方式;另一方面则是“后门耦合”,即通过装备（产品）上的壳体、电源线、电缆、机箱的缝隙、孔洞等途径进行耦合。主要研究电气线路互联系统(EWIS)线缆抗高空核电磁脉冲耦合效应,通过研究HEMP干扰的特征、能量分布,搭建HEMP数学模型,采用控制变量法,改变EWIS线缆类型、离地高度等要素,通过在CST上建立仿真模型以及开展试验,分析HEMP对电子设备造成的影响程度,得到HEMP耦合效应的一般性结论与规律。     

一种蓝色荧光材料的合成

本文设计和合成了一种带有吡唑啉侧链基因的低聚酰胺,可用作蓝色荧光材料。分子中特殊的氢键序列(AADADD)及芳酰胺链可与制着器件所用的高分子基材分子之间的形成较强的作用力,从而将发光基团“铆定”在功能膜中。     

Light-off Performance of Three-Way Catalysts Before and After Accelerated Aging Test with an Engine-Dynamometer

This study demonstrates the reaction behavior during the purification of model automotive exhaust gases over Pd catalysts before and after thermal degradation. In particular, to investigate the relationship between the Pd state and the reaction behavior of Pd/Al₂O₃ and Pd/CeO₂−ZrO₂ (CZ), operando X-ray absorption spectroscopy measurements were performed during purifying exhaust gases over real and model catalysts mimicking the degradation of Pd particles and CZ supports after accelerated aging tests. The NO reduction activity of the aggregated Pd metal species was as high as that of the highly dispersed Pd species, but hydrocarbon (HC) poisoning was significantly enhanced by the aggregation of Pd metal particles caused by thermal aging. The existence of a three-phase boundary (TPB) between the CZ, the Pd particles, and the gas phase strongly affected the catalytic activity at low temperatures, and the presence of a sufficient TPB facilitated the combustion of unburned HCs owing to the oxygen storage performance of CZ. Thus, the TPB reduced the poisoning of the precious metal surface by HC species at low temperatures. Therefore, the findings of this study will facilitate the development of next-generation gas purification catalysts with high activity and durability.     

Soft microswimmers: Material capabilities and biomedical applications

In the last decades, microrobotics has attracted much attention of researchers due to the unique characteristics of shapes, propulsion mechanisms, and potential applications in the biomedical field. Recently, the research of microrobots has shifted to soft microrobots owing to their softness, elasticity and reconfigurability benefiting to interact with the complex channels in the human body compared to their rigid counterparts. There is significant progress on soft microswimmers and that encourages us to review this field timely to promote the development. In this review, we mainly highlight the progress of the soft microswimmers in recent years. The materials with softness, deformability and shape-morphing characteristics are surveyed as well as biocompatibility, followed by standard fabrication methods. Additionally, the locomotion based on self-propelled and external-field-driven mechanisms has been compared and discussed. Finally, the biomedical applications in imaging, targeted drug delivery and therapy, and microsurgery are highlighted followed by addressing the perspectives.     

A material force method for inelastic fracture mechanics

A material force method is proposed for evaluating the energy release rate and work rate of dissipation for fracture in inelastic materials. The inelastic material response is characterized by an internal variable model with an explicitly defined free energy density and dissipation potential. Expressions for the global material and dissipation forces are obtained from a global balance of energy-momentum that incorporates dissipation from inelastic material behavior. It is shown that in the special case of steady-state growth, the global dissipation force equals the work rate of dissipation, and the global material force and J-integral methods are equivalent. For implementation in finite element computations, an equivalent domain expression of the global material force is developed from the weak form of the energy-momentum balance. The method is applied to model problems of cohesive fracture in a remote K-field for viscoelasticity and elastoplasticity. The viscoelastic problem is used to compare various element discretizations in combination with different schemes for computing strain gradients. For the elastoplastic problem, the effects of cohesive and bulk properties on the plastic dissipation are examined using calculations of the global dissipation force.     

中国的百岁老人研究Ⅲ.百岁老人聚居区——中国长寿之乡的成因和评定

探讨了中国长寿之乡的成因,提出了评定中国长寿之乡的四项指标和六项衡量标准。主张中国长寿之乡应由有资质的学术团体经过认真调查和核实后认定,被命名的长寿之乡应是相当于县(市)或大城市区一级以上的地域,总人口应在10万人以上;该地区每百万人口中应有70位以上百岁老人;并应有反映后备力量和发展速度的指标。