Theoretical Evaluation of the Microporosity of Pillared Layered Double Hydroxides

Over the last ten years, the concept of pillaring has frequently been applied on layered double hydroxides (LDHs). Due to the variety of possible anionic pillaring species and the adjustable layer charge density, LDHs offer good perspectives with regard to the creation of porous adsorbents and catalysts. But despite these possibilities, their porosity properties can still not compete with those of industrially applicable materials like zeolites. In this study, theoretical calculations based on geometrical models and performed on both Fe(CN)₆-MgAl-LDHs (A) and [PV₂W¹⁰ O⁴⁰]-ZnAl-LDHs (B) were reported. Properties such as the micropore volume and the interpillar distance were calculated, and compared to experimental data. For a M(II)/M(III) ratio in the layers of 3, the theoretical maximum micropore volumes were 0.3843 cm³/g (A) and 0.1497 cm³/g (B), respectively. By implementing parameters like the stack size, pillars on the outside of the stacks and the possibility of collapse, the model was adjusted in order to create a realistic picture of the microstructure of pillared LDHs. This led to a better understanding of the limiting factors, and gave an explanation for the relatively low micropore volumes of pillared LDHs. For the Fe(CN)₆-MgAl-LDHs, small interpillar distances were responsible for the partial inaccessibility of the interlayer regions by N₂. This effect was the most pronounced for high charge density LDHs. The situation for the [PV₂W¹⁰O⁴⁰]-ZnAl-LDHs is more complex. Probably due to an incomplete pillaring process, the theoretical maximum values are not reached.     

A soft configuration model for wearless sliding friction

A phenomenological model of soft potential configurations is proposed to describe sliding friction in the wearless regime. This model accounts for the static and dynamic behavior. The physical origin of the logarithmic speed or time dependence for the friction coefficient is described. Means to control the friction coefficient by controlling the soft defect density are discussed. This revised version was published online in September 2006 with corrections to the Cover Date.     

Syntactic priming in comprehension: The role of argument order and animacy.

Two visual-world eye-movement experiments investigated the nature of syntactic priming during comprehension--specifically, whether the priming effects in ditransitive prepositional object (PO) and double object (DO) structures (e.g., "The wizard will send the poison to the prince/the prince the poison?") are due to anticipation of structural properties following the verb (send) in the target sentence or to anticipation of animacy properties of the first postverbal noun. Shortly following the target verb onset, listeners looked at the recipient more (relative to the theme) following DO than PO primes, indicating that the structure of the prime affected listeners' eye gazes on the target scene. Crucially, this priming effect was the same irrespective of whether the postverbal nouns in the prime sentences did ("The monarch will send the painting to the president") or did not ("The monarch will send the envoy to the president") differ in animacy, suggesting that PO/DO priming in comprehension occurs because structural properties, rather than animacy features, are being primed when people process the ditransitive target verb. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

自由脱开气圈与倍捻机的优化设计

从自由脱开气圈的角度研究倍捻机气圈，可以得到机构尺寸与气圈形态，张力的系列对应解。文章从储丝盘量大限度调节张力波动以使气圈保持相对稳定的角度，提出了选择倍捻机机构尺寸优化解的方法，并对锭盘形状为例讨论了选择倍捻机各机构尺寸最优化的组合形式。     

下山揭穿近水平近距离煤层群防突技术实践

为了确保下山掘进揭穿近水平煤层群时的安全,根据下山揭近距离近水平煤层群的赋存特点,结合杨柳矿的主井井底检修斜巷揭煤实例,提出了一套较为安全经济的下山揭近水平煤层群的防突技术方法,并顺利揭穿杨柳矿主井井底检修斜巷煤层群,实践证明下山揭近水平煤层群的防突技术方法效果较好.     

液压转向闭式回路动态仿真建模与分析

本文研究了履带车辆液压转向闭式回路建立仿真模型的方法 ,在多个设计参数未明确的情况下 ,利用实验数据修正了仿真模型 .并分析了容积效率、输入转速、负载转矩对液压转向闭式回路动态响应特性的影响 ,这些规律可用于指导液压转向系统的设计与使用     

闭式液压传动在接触网作业车走行系统的应用

论述了闭式液压系统的特点及接触网作业车闭式液压走行系统的工作原理、设计思路,并对存在的问题提出了改进方案和推广建议,指出闭式液压传动方式将会在需要高、低速兼顾的作业施工车辆上得到越来越广泛的应用。     

水滑石类插层组装功能材料

水滑石类(LDHs)化合物是一类典型的阴离子型层状材料。LDHs的构筑单元和结构的可控性和多样性,为此类材料的应用研究提供了广阔前景。以LDHs的层状结构和可插层性为线索,介绍了LDHs的结构特征和制备化学,讨论了阴离子插层LDHs的组装原理和主-客体相互作用,对基于主体层板调控及主-客体相互作用的多种插层LDHs功能材料的制备和应用进行了综述,并对LDHs的结构创新和制备技术的研究方向进行了展望。     

基于PC总线的热继电器自动测试系统设计

本文介绍了利用计算机和VB语言进行的温度继电器自动测试系统的硬件结构和软件程序的实现方法。     

GaAlAs/GaAs双异质结发光管中的深能级

本文用DLTS谱仪和单脉冲瞬态电容技术测量了光通信用GaAlAs/GaAs双异质结发光管中的深能级,对有源区掺Si和掺Ge的相同结构器件,均测得有多子陷阱存在,其能级位置分别为E_C—E_D≈0.29eV和E_T—E_V≈0.42eV。比较了外延系统中氧含量变化对有源区掺Si器件深能级的影响,以及有源区EL图象中的DSD与深能级关系,结果表明外延系统中氧含量对深能级有明显影响,而EL图象中DSD的出现率与深能级无明显关系。