Investigation of atomic structure ahead of crack tip by STM and AFM

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ORCAD器件库文件结构分析

对ORCAD软件的器件库文件进行了详细的分析,并具体讨论了器件库文件的五大组成部分:文件头;定位指针表;器件名称表;器件索引数据区和器件位图数据区 通过分析,笔者能够调用ORCAD器件库文件,完成电路图的设计和仿真     

论国民经济运行中的控制力

从我国国民经济运行中的控制力这个理论问题入手,借鉴国外对本国经济运行中控制理论具体运用的经验,系统分析了我国过去国有经济在整个国民经济中主导作用的理论上认识的一些误区及其实践效果,阐述了对国有经济主导作用的重新认识的一些理论观点,提出了国有经济主导作用即控制力的具体运用方法、重点及原则。     

机器人手部速度和输出力波动控制的多目标优化方法

本文提出了降低机器人手部速度波动和输出力波动是提高其作业精度重要途径的观点．建立了解决彼动的数学模型，运用多目标优化理论和ｍｉｎ—ｍａｘ方法成功地获得了解点．     

Structural and Electric Properties of Sol–Gel-Derived Ba0.9Sr0.1TiO3 Multilayers

Crack-free Ba_0.9Sr_0.1TiO₃ (BST) and Mn-doped Ba_0.9Sr_0.1TiO₃ (BSTM) multilayers with thickness over 2 μm have been prepared by chemical solution deposition based on one single precursor. Both multilayers exhibit good performance as Bragg reflectors. Mn doping tends to suppress the leakage current in BST multilayers effectively by smoothing the layers and the reduction of the charge carries. The Mn-doped BST multilayer displays an excellent ferroelectric property, with an average remnant polarization ( P _r⁺– P _r⁻)/2 of 12.69 μC/cm² and an average coercive field ( E ⁺ – E ⁻ )/2 of about 72.95 kV/cm under an applied field of 440 kV/cm.     

提高丁醇产品纯度的研究

在我国丁醇有着较好的市场,目前国内丁醇厂家20余家,随着生产厂家的每年增加,对丁醇纯度的要求也逐渐提高。本文结合化工实际生产对影响丁醇纯度的要素进行阐述,并针对如何提高正丁醇纯度提出了一些建议。     

Improving toughness of ultra-high molecular weight polyethylene with ionic liquid modified carbon nanofiber

Ionic liquids (ILs) with long alkyl substituted groups, including 1-docosanyl-3-methylimidazolium bromide (IL-1) and 1-docosanyl-3-methylimidazolium hexafluorophosphate (IL-2), were synthesized and used to modify the surface of carbon nanofibers (CNF). The nanocomposite film prepared by solution-blending of ionic liquid modified CNF (i-CNF) and ultrahigh molecular weight polyethylene (UHMWPE) displayed better toughness when compared with pure UHMWPE even at very low concentrations (e.g. 0.4 wt%). The effect of ionic liquids on the elongation-to-break ratio of this nanocomposite system was investigated. The ionic liquid with hexafluorophosphate as the anion was more efficient to increase the toughness of UHMWPE due to the improved compatibility of IL with UHMWPE in the polymer matrix than that of the bromide. The rheological behavior of molten nanocomposites revealed that the storage modulus and the complex viscosity decreased with increasing ionic liquid content in the high frequency region. However, a reverse trend was observed when the frequency was less than 0.05 s⁻¹. In-situ monitoring in the change of crystallinity of the nanocomposite during tensile deformation suggested a mechanism of sliding between UHMWPE crystal regions and the surface of carbon nanofibers.     

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed (RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid–solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid–solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid–solid mass transfer coefficient (k_LS) have been investigated. The correlation for predicting k_LS was proposed, and the deviation between the experimental and predicted values was within ± 12%. The liquid–solid volumetric mass transfer coefficient (k_LSa_LS) ranged from 0.04–0.14 1⁻¹, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.     

Preparation of nano-zeolite tubular membrane for ethylbenzene separation from ternary mixed xylene by microwave functional coating method

The ethylbenzene separation from mixed xylene is one of the critical issues in the chemical industry. In this study, separation of ethylbenzene from ternary xylene mixtures system [ethylbenzene (EB), para-xylene (PX) and meta-xylene (MX)] was performed using a nano-zeolite coated tubular membrane system. Nano-zeolite membranes with different Si/Al ratios (Si/Al = 30, 100 and ∞) were prepared by a microwave hydrothermal method and the separation performance was compared. MFI-type nano-zeolite membranes were synthesized on alumina tubes from the randomly oriented seed layers by dip coating and functional coating using 3-chloropropyltrimethoxysilane, respectively. After the microwave-assisted secondary growth, it was observed that thinner layers of nano-zeolites were prepared by functional coating (3–4 μm) compared to the typical dip coating (6–8 μm). Ethylbenzene separation tests were performed using a comparatively high EB-containing ternary mixture feed (EB/PX/MX = 80/5/15 molar ratio). The silicalite-1 (Si/Al ratio = ∞) membrane with a functional layer shows the best ethylbenzene separation factor of 3.11 from the high EB-containing ternary mixture feed (ethylbenzene flux: 1,010.6 mol/m² s Pa ×10^?10).     

Comprehensive Alcohol-/Ion-Responsive Properties of Poly(N-Isopropylacrylamide-co-Benzo-18-Crown-6-Acrylamide) Copolymers

abstract In this paper, we report on the comprehensive alcohol-/ion-responsive properties of a smart copolymer poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)). The orthogo...