Ti(C,N)基金属陶瓷中添加成分的研究现状

简要介绍了Ti(C,N)基金属陶瓷的基本结构和组成,重点阐述了各种添加成分的加入方法和加入量对材料组织和性能的影响。     

Mechanism of arsenate coprecipitation at the solid/liquid interface of ferrihydrite: A perspective review

Arsenate (As(V)) is a toxic element in acid mine drainage and has to be removed during the neutralization process. Coprecipitation with ferrihydrite is the main mechanism for As(V) removal from acid mine drainage. To improve treatment efficiency, a quantitative understanding of the coprecipitation mechanism is required. Coprecipitation can incorporate more As(V) into ferrihydrite than adsorption. The results of XRD (X-ray Diffraction) and XANES (X-ray Adsorption Near Edge Structure) analysis confirmed that the formation of poorly crystalline ferric arsenate increased when the initial As/Fe molar ratio increased in the coprecipitation with ferrihydrite. EXAFS (Extended X-ray Adsorption Fine Structure) analysis at the iron K-edge showed that the proportion of octahedral structures in ferrihydrite increased when the initial As/Fe molar ratio increased. Moreover, EXAFS analysis at the arsenic K-edge, assuming three kinds of surface complexes for the AsFe bond, revealed that the coordination number for AsFe with an atomic distance of 2.85 × 10⁻¹⁰ m increased and that for As-Fe with an atomic distance of 3.24 × 10⁻¹⁰ m decreased as the initial As/Fe molar ratio increased. Thus, for more efficient wastewater treatment, active control of coprecipitation phenomena according to mechanistic details is essential.     

Electronic structure of YBa2Cu3O7 and YBa2Cu3O6—charge-self-consistent band structure calculations

Charge self-consistent LCAO band structure (CSCBS) calculations are reported for orthorhombic YBa₂Cu₃O₇ and tetragonal YBa₂Cu₃O₆ assuming ordered vacancy models. The effective atomic charges are used to study the charge transfer. In YBa₂Cu(1)₁Cu(2)₂O₇, the two types of copper atoms have their energy bands almost overlapping with effective valency of each copper as 7/3 (or effective valency of each oxygen as approximately — 13/7), so that electron hopping can take place without any loss or gain of energy while in YBa₂Cu(1)₁Cu(2)₂O₆, Cu(1)₁ is monovalent and Cu(2)₂ are divalent with significant difference in their bands. Therefore, YBa₂Cu₃O₇ should conduct much better compared to YBa₂Cu₃O₆. This corroborates the experimental observations that YBa₂Cu₃O₇ is a (super)conductor while YBa₂Cu₃O₆ is not. The calculated effective charges and DOS support the above view.     

Recent progress in the design and fabrication of multifunctional structures based on metamaterials

Metamaterials, with unconventional properties realized through various ingenious designs of micro-architectures, have become a recent research hotspot in the fields of electromagnetics, acoustics, mechanics, and physics. Since the integration of mechanical features and specific functions is still a challenge, the application of metamaterials has so far been limited. The research in relevant areas has shown a clear trend of incorporating the multifunctional design into a single integrated structure. Here, we review the latest advances in the design and fabrication of multifunctional structures based on metamaterials, covering three main aspects, i.e., the direct design of mechanical metamaterials and their multifunctional structures, the intelligent multifunctional structures with shape-shifting capabilities, the metamaterials-based design to achieve both the load bearing capability and other specific functions. We emphasize the important roles that the mechanics-driven designs play, as well as the mechanisms and other key aspects behind the multifunctional structures. The structure-level innovations could not only improve multifunctional features, but also pave the way to function fusion structures that allow the incorporation of ‘conflicting’ functions into a single structure.     

粘弹性阻尼器控制的框架结构弹塑性地震响应分析

针对框架结构，采用粘弹性阻尼器来控制其地震响应，提出了粘弹性阻尼器的等效刚度矩阵和等效附加粘弹性力向量的概念，推导了子结构平面内的粘弹性阻尼器的有限元计算公式，在此基础上，提出了结构等效附加粘弹性力荷载的概念，采用拟外荷载法对安装了粘弹性阻尼器的框架结构的弹塑性地震响应进行了计算分析，开发了计算受粘弹性阻尼器控制的框架结构的动力特性、受控框架结构的地震弹性响应、受控框架结构的地震弹塑性响应的计算机程序。应用所开发的计算程序对一框架结构在粘弹性阻尼器控制下的地震响应进行了计算，计算表明，粘弹性阻尼器可以有效地控制框架结构的地震响应、采用拟外荷载法可以有效地求解受控结构的运动方程。     

从结构鉴定看照相有机物的发展

本文回顾了近二十几年来感光材料生产技术发展和进步的历程中，在研究开发新型照相有机物方面所取得的重大进展，通过对国外先进彩色胶片中新颖有机物的剖析和结构研究，阐述了当今世界上照相有机物的最新发展动态。     

Microstructure Characteristics of Cathode Materials for Rechargeable Magnesium Batteries

Rechargeable magnesium batteries (RMBs) that use pure Mg or Mg alloy as anode and materials allowing Mg ions to insert/extract as cathode have many advantages such as high energy density, environmental friendliness, low cost, and safety of handling. RMBs are regarded as a promising candidate for portable power sources and heavy load energy devices. However, there are still some technological issues impeding their commercial application. The most important issue is the absence of applicable cathode materials because of the high charge density, strong polarization effect, and very slow insertion/extraction speed of Mg²⁺ ions. In recent years, the research reports on the cathode materials of RMBs have increased significantly. Here, an extensive number of research papers are reviewed in terms of the microstructure characteristics of cathode materials for RMBs. The status and issues of cathode materials are analyzed and discussed in detail. The future development directions and perspectives are prospected for providing an understanding of the related research activities on RMBs.     

闪锌矿结构YB的半金属性的第一性原理研究

采用广义梯度近似加优化的贝克-琼森势作为交换关联势进行第一性原理计算,研究闪锌矿结构YB化合物的电子结构和半金属性。结果表明闪锌矿结构YB是一个典型的半金属铁磁体,其半金属隙为2.7meV,体系的总磁矩为每分子2.00μB。体系的总磁矩主要源于B原子的p轨道电子,B原子的p轨道电子和Y原子的d轨道电子杂化是形成半金属性质的主要原因。稳定的铁磁相、晶格常数压缩稳定性以及负的结合能,都预示着闪锌矿结构YB是具有潜在应用前景的半金属铁磁体。     

高岭石电子结构计算及键络分析

基于"固体与分子经验电子理论(EET)"计算了高岭石的价电子结构,分析了相的空间键络分布,指出了存在的薄弱环节.硅氧四面体中最强键nA=1.37457和次强键nB=1.45692构成了坚固的网状结构;相对而言,铝氧八面体的键合较弱,键强分别为nC=0.38433、nD=0.39188;弱键集中于八面体与四面体的一侧连接上,造成了OI-OⅢ层间键合强度最弱,易于拆散.     

六方硼碳氮制备方法研究进展

B-C-N 材料的提出是由于氮化硼和碳材料具有特殊的优异性能,通过对不同结构 B-C-N 材料的研究发现,组成结构的差异导致其物理化学性能发生很大变化。其中,h-BCN 由于其禁带宽度和半导体特性可调而尤为引人关注。h-BCN 有平面和层状两种结构,基于目前两种结构的 h-BCN 制备方法的最新研究进展,简述了材料的结构、生长机理、性质和应用前景,分析了反应原料、温度和时间对 h-BCN 形成的影响,最后介绍了 h-BCN 亟待解决的问题和发展方向。     

金属滑移面的价电子结构特性

为在价电子结构层次分析和研究A1型与A2型结构滑移面问题，以“固体与分子经验电子理论”为指导，计算了A1型与A2型结构的低指数晶面的价电子结构，提出了表征晶体沿晶面发生滑移难易的价电子结构参数F及其计算方法．研究结果表明，在A1型结构中，{111}面的F值最小，在Az型结构中，{110}面的F值最小，并以此解释了A1型与A2型结构滑移面分别为{111}与{110}这一金属学问题，从而把滑移面的本质追溯到金属平面的价电子结构上．     

双重抗震结构及其设计参数的分析研究

本文根据多道抗震设防概念,对双重抗震结构的设防目标进行了探讨,明确了主、 次结构的功能．文中利用单自由度双重结构分析模型,对主、次结构的合理参数关系进行了 计算分析,提出了有关抗震设计建议。有关结果同样也适用于滞迟型减震控制结构。     

果粒饮料盒中袋灌装阀阀道结构分析与优化

目的为了确定盒中袋灌装阀阀道结构以及阀芯下降高度,对盒中袋灌装阀进行流体流场仿真计算。方法运用Fluent软件对盒中袋灌装机的灌装阀阀道结构进行流场分析,根据流速场以及压力场的分布,找出应力集中区域,进行了结构优化;再运用Fluent软件对阀芯下降不同高度数值后,进行模拟仿真,根据阀芯下降不同高度时流速场与压力场的变化,找出最佳高度。结果得到了优化的结构工艺参数以及合适的阀芯下降高度。结论阀型拐角θ1和θ2为30°,阀芯下降高度为3 mm时,物料在阀道中的流动状态最合适。     

A structural analysis of the measuring signals of the NAVSTAR satellite system

The recording of the nonstationary random process at the output of the measuring channel of the NAVSTAR satellite system is analyzed. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 10–12, March, 2007.     

多相ZrO2几何结构及电子结构第一性原理研究

采用基于第一性原理的密度泛函理论投影缀加平面波,使用广义梯度近似处理交换关联势能,深入研究了弛豫多相 ZrO2几何结构特征及电子结构。研究发现,单斜、四方和立方 ZrO2能带间隙分别约为3.47 eV、3.96 eV 和3.36 eV。近费米能级态密度分析结果表明,多相 ZrO2的基本性质均由 O 2p 态电子和 Zr 4d 态电子决定。     

凝胶化PAN纤维的微结构特征

借助于X射线衍射仪、声速取向度测量仪、扫描电镜、小角X光散射仪等研究了凝胶化聚丙烯腈(PAN)纤维的聚集态结构和形态结构特点。结果表明,与常规高温凝固和低温凝固成型方式得到的PAN纤维相比,凝胶化凝固形成的初生纤维和原丝晶粒尺寸小,在牵伸相同的情况下,凝胶化凝固原丝取向结构最高,表明其结构对张力的响应性较好;凝胶化凝固的PAN初生纤维截面结构致密、内外均匀,表面沟槽深且均匀规则,凝胶化凝固的原丝微孔相对体积含量最小。     

REBaCuO超导体电子结构及其与超导电性的关系

利用量子化学的ＳＣＦ－Ｘα－ＳＷ方法计算了ＲＥＢａＣｕＯ (ＲＥ＝Ｙ,Ｌａ、Ｎｄ．Ｓｍ,Ｅｕ,Ｇｄ;Ｄｙ,Ｅｒ和 Ｔｍ)等氧化物超导体体系的电子结构,计算结果表明:氧化物超导体中存在一种特殊内层轨道耦合作用,它是由ＲＥ的ＳＰ电子轨道与Ｏ的２ｓ电子轨道的空间交叠引起的,内层轨道耦合的大小由两个饱和轨道的空间交叠程度,以及两个轨道能级的接近程度决定．此外,与实验结果对比可以看出,超导临界温度与两个饱和轨道的交叠程度有相似的变化规律,超导临界电流密度与参与耦合的电子数量随ＲＥ原子序数的变化规律类似,因此,内层轨道耦合对高温超导电性的影响是不可忽略的．     

深水环境下潜艇舯部结构撞击强度数值分析

潜艇结构水下碰撞是潜艇的主要事故形式，也是船舶碰撞最为危险的状态之一。文中首先提出潜艇碰撞问题，对碰撞特征进行分析，然后针对某型潜艇舯部典型结构的撞击极限强度特性进行数值计算，结果显示，由于准静压载荷的附连耦合作用，随着静水压力的增加，潜艇舯部耐压壳体结构的防撞能力将大幅下降。而耐压壳体内部平台和舱壁结构将有效提高壳体结构的横向失稳临界应力，改善潜艇结构的径向耐撞能力。     

丸剂药品包装多功能封缄盖的结构设计

针对丸剂药品形状的规则特殊性及回旋挤出状态好的特点,以计量控制为设计中心,设计了一种融显窃启、儿童安全、使用便捷及趣味性高于一体的新型丸剂药品包装瓶的封缄结构。通过选择以可透过环圈为基础的计量控制方案,确定了各功能结构,设计了各主要组件的尺寸参数,绘制了效果展示图和容器整体分解图,展现了各构件的作用。该设计方案结构简单、使用方便、成本较低。