Nb和时效时间对热轧中锰TRIP钢中P偏聚的影响

热轧态中锰TRIP钢首先经650 ℃退火2 h,随后在550 ℃进行等温时效热处理,采用场发射扫描电镜(FE-SEM)研究该钢中P的偏聚和时效析出行为的变化情况。结果表明,中锰TRIP钢中P在晶界的偏聚是一种非平衡偏聚现象,临界时间约为50 h,与理论计算结果48 h较为吻合。在局部偏聚区域内,C与P存在共偏聚的关系,即P偏聚量高的地方,C含量也高。而合金元素Nb具有抑制P偏聚的效果,在20~70 h时效时间内,可以相对降低6.57%~19.5%的最大P偏聚量。根据电子背散射衍射(EBSD)菊池线分析,P偏聚量低于2.28at%时,P为固溶状态,高于2.28at.%时,P为析出状态。     

声表面波可程序抽头延迟线研究

报道声表面波可程序抽头延迟线的研制情况。对该器件的总体结构，电路原理框图、声表面波可程序抽头延迟线结构作了一个扼要的概念。同时分别报道了我所研制的各类声表面波可程序抽头延迟线器件性能指标及相应的图片说明，最后对该器件仍存在的一些问题作了探讨。     

31位低频声表面波可程序匹配滤波器

报道了３１位声表面波可程序匹配滤波器的结构、设计和性能参数。声表面波可程序抽头延迟线是近年来快速发展的直扩技术广泛应用的一种器件。它的强大信号处理能力和极高的运算速度，使得直扩序列信号的快速同步及匹配滤波较传统的技术大为简化。文章报道的３１位声表面波低频可程序抽头延迟线是一种用于扩频抗干扰通信系统所用的关键信号处理器件。在研制过程中，采用的ＣＯＭＳ／ＳＯＳ等新技术以及分裂抽头等新设计，使器件的时钟速率和主旁瓣比关键技术指标获得了较大的提高，完全满足系统要求     

Deriving phosphorus atomic chains from few-layer black phosphorus

Phosphorus atomic chains,the narrowest nanostructures of black phosphorus (BP),are highly relevant to the in-depth development of BP-based one-dimensional (1D) nano-electronics components.In this study,we report a top-down route for the preparation of phosphorus atomic chains via electron beam sculpturing inside a transmission electron microscope (TEM).The growth and dynamics (i.e.,rupture and edge migration) of 1D phosphorus chains are experimentally captured for the first time.Furthermore,the dynamic behavior and associated energetics of the as-formed phosphorus chains are further investigated by density functional theory (DFT) calculations.It is hoped that these 1D BP structures will serve as a novel platform and inspire further exploration of the versatile properties of BP.     

Polymer nanoparticles as adjuvants in cancer immunotherapy

Immunotherapy is a promising strategy to inhibit cancer progression via activation of the immune system. In immunotherapy, adjuvants as immunologic stimulants or delivery systems play a critical role in inducing the antitumor immune response and decreasing the side effects of immune stimulants. Polymer nanoparticles have attracted increasing attention as an indispensable component of immunotherapy, owing to their favorable properties, such as excellent biocompatibility and biodegradability, flexible size, high activity as immune stimulants, large surface area for binding multivalent immune ligands, and high loading capacity for immune-related components. In cancer immunotherapy, polymer nanoparticles can protect cargo from the surrounding milieu, deliver the antigens and immunostimulatory molecules to antigen-presenting cells, or stimulate robust T cell response. This review summarizes the current advancements in polymer nanoparticle adjuvants for cancer immunotherapy and predicts their prospects in fundamental and clinical studies.

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基于Pro/E的曲柄活塞机构的运动仿真分析

基于Pro/E软件的建模和仿真模块,构建曲柄滑块机构的机械模型,并进行运动仿真。结合机械原理,对曲柄活塞机构的运动进行研究;并从理论角度运用数理方法建立运动方程,借助MATLAB函数编辑器绘制函数曲线。对比两者结果表明,运用Pro/E进行模拟比用数值理论方法更具优越性。     

碱法麦草浆木聚糖酶处理后木质素及碳水化合物的变化

采用UV光谱、凝胶色谱、X—射线衍射及扫描电镜等技术对碱法麦草浆的酶解浆和酶解液进行分析,探讨了木聚糖酶对碱法麦草浆处理后浆中木质素和碳水化合物的变化情况。研究认为,木聚糖酶对碱法麦草浆漂白作用主要是因为木聚糖酶降解了浆中部分木聚糖和残余木质素中的LCC结构,从而使后序漂白中漂液更易渗透,木质素的溶出更多、更易。     

Maintaining Views in Object-Relational Databases

View materialization is an important way of improving the performance of query processing. When an update occurs to the source data from which a materialized view is derived, the materialized view has to be updated so that it is consistent with the source data. This update process is called view maintenance. The incremental method of view maintenance, which computes the new view using the old view and the update to the source data, is widely preferred to full view recomputation when the update is small in size. In this paper we investigate how to incrementally maintain views in object-relational (OR) databases. The investigation focuses on maintaining views defined in OR-SQL, a language containing the features of object referencing, inheritance, collection, and aggregate functions including user-defined set aggregate functions. We propose an architecture and algorithms for incremental OR viewmaintenance. We implement all algorithms and analyze the performance of them in comparison with full view recomputation. The analysis shows that the algorithms significantly reduce the cost of updating a vieww hen the size of an update to the source data is relatively small. Received 23 May 2000 / Revised 27 March 2001 / Accepted in revised form 30 April 2001 Correspondence and offprint requests to: Jixue Liu, School of Computer and Information Science, University of South Australia, Mawson Lakes, Adelaide SA5084, Australia. Email: jixue.liu@unisa.edu.auau     

Irrelevant updates and self-maintainability in transitive closure database views

Irrelevant updates in a database are updates to source data that do not affect a view defined over the source data. Self-maintainable updates are ones for which the view can be updated, without having to access source data, when the source data from which the view is derived is updated. In this paper we derive necessary and sufficient conditions for an update to be irrelevant or self-maintainable when the source data is a graph and the view is defined to be the transitive closure of the graph.