A Strength–Porosity Relation Involving Different Pore Geometry and Orientation

A number of empirical and semiempirical expressions which relate the strength of brittle polycrystalline materials to the total porosity have been proposed by various investigators. The present study demonstrates from a purely theoretical point of view that not only the total porosity but the pore shape and orientation are important factors affecting the strength. A strength-porosity relation is derived that takes pore shape and orientation into account. Examples of how various types of pores should affect the strength are presented.     

Antitumor Effects of Vitamin D Analogs on Hamster and Mouse Melanoma Cell Lines in Relation to Melanin Pigmentation

Deregulated melanogenesis is involved in melanomagenesis and melanoma progression and resistance to therapy. Vitamin D analogs have anti-melanoma activity. While the hypercalcaemic effect of the active form of Vitamin D (1,25(OH)₂D₃) limits its therapeutic use, novel Vitamin D analogs with a modified side chain demonstrate low calcaemic activity. We therefore examined the effect of secosteroidal analogs, both classic (1,25(OH)₂D₃ and 25(OH)D₃), and novel relatively non-calcemic ones (20(OH)D₃, calcipotriol, 21(OH)pD, pD and 20(OH)pL), on proliferation, colony formation in monolayer and soft-agar, and mRNA and protein expression by melanoma cells. Murine B16-F10 and hamster Bomirski Ab cell lines were shown to be effective models to study how melanogenesis affects anti-melanoma treatment. Novel Vitamin D analogs with a short side-chain and lumisterol-like 20(OH)pL efficiently inhibited rodent melanoma growth. Moderate pigmentation sensitized rodent melanoma cells towards Vitamin D analogs, and altered expression of key genes involved in Vitamin D signaling, which was opposite to the effect on heavily pigmented cells. Interestingly, melanogenesis inhibited ligand-induced Vitamin D receptor translocation and ligand-induced expression of VDR and CYP24A1 genes. These findings indicate that melanogenesis can affect the anti-melanoma activity of Vitamin D analogs in a complex manner.     

涂装密封线常见涂胶工具概述

介绍了车身焊缝形式及涂装密封工艺,概述了密封线所使用的涂胶工具及日常维护措施。     

塑料挤出生产线集散控制系统的研究

设计了塑料挤出生产线集散控制系统,它是基于西门子S7-200系列可编程控制器PLC、计算机PC和 WinCC人机界面设计工具的基础上,实现塑料挤出生产线集中管理,分散控制及在线远程自动监控。设计的控制系统包括塑料挤出生产过程中的3个必要工序:各段温度控制、电机驱动控制和计量加料控制,根据对象特性提出不同的控制方案,控制其工艺参数,使塑料挤出生产线运行更加灵活、稳定、安全,用户管理更加简单方便,并进一步提高控制精度和生产效率。     

浅谈涂装生产线空调选配

以国内某设计年产15万辆中档轿车涂装生产线空调配置及使用情况为例,浅谈空调选配过程中需考虑的问题,避免涂装生产线设计初期无必要的投资及长期生产运行过程中造成资源、能源的浪费。进而阐明合理选用设备有效利用率的重要性,要做到设计适用、功能不过剩,避免大马拉小车的现象。     

A Viscosity-Temperature Relation for Glass

A theory for the viscosity and structure of glass as a function of temperature and composition had been advanced, proposing that at a few critical temperatures silicate glasses undergo structural transformations. Between these transformation temperatures, the activation energy and lattice coefficient are constant. A series of special glasses were melted and viscosity was measured to test this theory. The results indicate that the viscosity-temperature behavior of glass does not conform to the previously proposed model. The activation energy appears to vary continuously over the entire temperature range studied. However, a critical temperature does exist at which the temperature coefficient of the activation energy changes. This discovery represents a more subtle change than that previously envisaged.     

Amino Acid Profiles of 44 Soybean Lines and ACE‐I Inhibitory Activities of Peptide Fractions from Selected Lines

Soybeans are cultivated in the United States chiefly for cooking oil, while the residue after oil extraction (soybean meal) is mostly used in animal feed formulations. High protein content in the defatted soybean meals led to the extraction of pure protein and its application in food products. We selected 44 soybean lines to determine their moisture and protein contents, and their amino acid composition was investigated. Soybean lines with high protein content, one high yielding (R95‐1705), and two high oleic acid (N98‐4445A, S03‐543CR), were selected for protein isolate preparation, hydrolysis using alcalase and gastro‐intestinal (GI) resistance. Furthermore, the GI resistant hydrolysates were fractionated and tested for angiotensin‐I‐converting enzyme (ACE‐I) inhibition activity. The amino acid analysis showed high methionine in the high protein and fatty acid lines (R05‐4494 and R05‐5491), and high cysteine content in one of the high oleic acid soybean line CRR05‐188 in comparison to the check lines (UA‐4805 and 5601‐T). The protein isolate with the highest purity (90–93 %) was derived from the selected lines N98‐4445A and S03‐543CR, and hydrolyzed using alcalase enzyme. The protein hydrolysates (500 µg/mL) showed inhibition of the ACE‐I by 49 %. The results from this study will promote the use of high oleic acid soybeans as a source of protein and peptides with functional activities.     

Syringolin A Selectively Labels the 20 S Proteasome in Murine EL4 and Wild‐Type and Bortezomib‐Adapted Leukaemic Cell Lines

The natural product syringolin A (SylA) is a potent proteasome inhibitor with promising anticancer activities. To further investigate its potential as a lead structure, selectivity profiling with cell lysates was performed. At therapeutic concentrations, a rhodamine‐tagged SylA derivative selectively bound to the 20 S proteasome active sites without detectable off‐target labelling. Additional profiling with lysates of wild‐type and bortezomib‐adapted leukaemic cell lines demonstrated the retention of this proteasome target and subsite selectivity as well as potency even in clinically relevant cell lines. Our studies, therefore, propose that further development of SylA might indeed result in an improved small molecule for the treatment of leukaemia.     

一种聚氨酯板材的多流水线集中控制系统方案

结合一些聚氨酯工业设备制造企业的实际需求,围绕多生产线集中控制的先进思想,开发了一套基于西门子S7-400系列PLC的自动化集中控制系统方案。介绍了单生产线的控制原理和多生产线集中控制系统。实践表明,该系统性能优异、自动化程度高,节约了生产成本,提升了生产效率。     

Determination of the R-Curve from the Strength—Indentation Load Relation

Strength as a function of indentation load has been measured to evaluate toughness versus crack size curves (i.e., R -curves) of ceramics. In the past, this evaluation is achieved by generating a family of global stress intensity versus crack size curves (i.e., K -curves) at each indentation load and its corresponding strength, and then fitting an envelope of tangency points to these curves. This envelope yields the R -curve. A methodology is proposed in the present study to define the point in the K -curve at which the R -curve intersects. This methodology complements the conventional "tangency condition" approach in determining the R -curve from the experimental strength-indentation load relation.     

涂装线建设投资与运行费用控制的探讨

汽车车身涂装线在汽车制造业中是属于复杂性很高的生产线。涂装材料、涂装工艺、涂装设备、涂装厂房及公用动力设施、涂装管理等都是直接影响涂装线的投资与降低运行费用的因素,必须依靠高质量的工程设计和施工管理来保证涂装线投资的合理性与降低运行费用。由于车身涂装线工艺技术复杂,与其他生产线相比投资较大,     

注塑件熔接痕的研究进展

介绍了注塑件熔接痕的形成机理,分析了影响熔接痕强度的各种因素,从注塑工艺参数设定、模具结构设计等方面给出了消除熔接痕或提高熔接痕强度的措施。     

生产氯代环己烷的工艺研究

苯部分加氢生产氯代环己烷,经济,安全,无环境污染,从理论上探讨了采用苯部分加氢制环己烯,再由环己烯与氯化氢加成生产氯代环己烷工艺的可行性及反应条件。同时考察了所得产品的分离方法,以及在分离过程中的影响因素：温度、压力、回流比、加热量等,发现采用变回流比时,操作所得产品最理想。     

葛洲坝水泥厂三条生产线的优化设计

葛洲坝水泥厂三条生产线的设计,广泛汲取了最新设计和技术成果,在确保生产可靠的前提下,简化工艺流程,最大程度地降低工程造价,并取得了预想的效果。     

Dimensionless Load—Displacement Relation and Its Application to Crack Propagation Problems

The dimensionless load (     ) and load-point displacement (û) are introduced to discuss crack propagation problems. The     −ũ relation for the case of equilibrium crack propagation in any linear elastic material is demonstrated to lie on a single universal fracture curve independent of the material. The concept of the universal     −ũ relation is extended to yield a direct and simple form of the dimensionless total energy (     _eq (α)) which is applicable to many types of instability problems for crack extension, when the shape factor ( Y ) of the specimen is known as a function of crack length ( a ). In addition, by applying the deviation of the experimentally observed     —ũ curve and the theoretical universal fracture curve, the evaluation of the nonlinear fracture resistance parameter of a polycrystalline graphite material, as an example, was demonstrated.