关键词： curing of polymers   crosslinking   mechanical properties   resins  

摘要： Dynamics of mechanical, acoustical, and electric properties is studied in the cure of three samples of polymeric compositions produced on the basis of epoxy oligomer with different content of the curing agent. The measurements were made in a parallel mode with an automated measuring complex. Variations in elastic modules, sound speed, attenuation coefficient, relaxation of the shear stress, electric resistance of the samples during the complete cure in the transition from a liquid into a glass state are considered. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 143-147, 2010

关键词： 河北太行机械工业有限公司   中国兵器工业集团   党委委员   总会计师   财务创新   科学发展   董事   文峰  

摘要： “七一”前夕．笔者从北京驱车前往石家庄，采访了优秀共产党员、中国兵器工业集团河北太行机械工业有限公司（简称“河北太行机械工业有限公司”）党委委员、董事、总会计师李文峰。

关键词： 农业机械   配备   小麦生产机械化   能量消耗   实践经验   单位面积   运城市   山西省  

摘要： 本文根据山西省运城市小麦生产机械化多年实践经验和数据．参考有关资料。对小麦生产单位面积能量消耗和以能量消耗配备动力进行了粗浅的研究。

关键词： 伺服驱动技术   直线电机   可编程计算机控制器   运动控制  

摘要： 本文主要分析和综述了全闭环交流伺服驱动技术、直线电机驱动技术、可编程计算机控制器、运动控制卡的基本原理、特点以及应用现状等。

关键词： 机械测试   航天   内蒙   高空模拟试验台   并行数据采集系统   地面试车   固体火箭发动机   调度通讯系统  

关键词： 风湿性心脏病   机械瓣   血流动力学  

摘要： 目的评价不同类型机械瓣对二尖瓣置换术后血流动力学的影响。方法本院行二尖瓣置换术96例,分为双叶瓣及倾斜碟瓣两组,比较手术前后及手术1年后两组间血流动力学的超声参数。结果两组术前二维超声参数:各房室内径及主、肺动脉内径、二尖瓣口面积差异均无统计学意义,血流动力学参数中E峰、A峰、平均跨瓣压差(mean pressure gradi-ent,MPG)、肺动脉收缩压差异均无统计学意义;术后10d内的二维超声参数比较:双叶瓣及倾斜碟瓣两组的E峰速分别为(1.43±0.70)m/s和(1.86±0.65)m/s(P<0.05),有效瓣口面积(effective orifice area,EOA)分别为(2.61±0.61)cm^2、(2.31±0.63)cm^2(P<0.05);肺动脉收缩压(pulmonary artery systolic pressure,PASP)分别为(33.9±14.2)mmHg和(32.8±9.4)mmHg(1mmHg=0.133 kPa,P>0.05);MPG分别为(4.76±2.8)mmHg和(5.2±3.7)mmHg(P>0.05)。手术1年后复查,双叶瓣及倾斜碟瓣两组的E峰速分别为(1.48±0.9)m/s和(1.92±0.4)m/s(P<0.05),EOA为(2.52±0.32)cm^2和(2.01±0.2)cm^2(P<0.05),PASP为(33.4±22.5)mmHg和(36.4±24.7)mmHg(P>0.05)。结论双叶机械瓣对风湿性心脏病二尖瓣置换术后血流动力学的影响强于倾斜碟瓣。

关键词： Heavy metal toxicology   Bioaccumulation   Ligands (Biochemistry)   Effect of water pollution on fishes   Effect of water pollution on aquatic organisms   Physiological effects of heavy metals   Heavy metal absorption & adsorption   Chemical affinity  

摘要： Both biotic ligand models (BLM) and bioaccumulation models aim to quantify metal exposure based on mechanistic knowledge, but key factors included in the description of metal uptake differ between the two approaches. Here, we present a quantitative comparison of both approaches and show that BLM and bioaccumulation kinetics can be merged into a common mechanistic framework for metal uptake in aquatic organisms. Our results show that metal-specific absorption efficiencies calculated from BLM-parameters for freshwater fish are highly comparable, i.e. within a factor of 2.4 for silver, cadmium, copper, and zinc, to bioaccumulation-absorption efficiencies for predominantly marine fish. Conditional affinity constants are significantly related to the metal-specific covalent index. Additionally, the affinity constants of calcium, cadmium, copper, sodium, and zinc are significantly comparable across aquatic species, including molluscs, daphnids, and fish. This suggests that affinity constants can be estimated from the covalent index, and constants can be extrapolated across species. A new model is proposed that integrates the combined effect of metal chemodynamics, as speciation, competition, and ligand affinity, and species characteristics, as size, on metal uptake by aquatic organisms. An important direction for further research is the quantitative comparison of the proposed model with acute toxicity values for organisms belonging to different size classes.

关键词： Mechanical stimulation   Inositol (1,4,5)-trisphosphate   Ca2+ response   FRET   Fluorescent biosensor   Spatial dynamics  

摘要： In the present study, the contribution of inositol (1,4,5)-trisphosphate [Ins(1,4,5)P-3] generation on the mechanical-stimulation-induced Ca2+ response was investigated in HSY-EA1 cells. Mechanical stimulation induced a local increase in the cytosolic concentration of Ins(1,4,5)P-3 ([IP3](i)), as indicated by the Ins(1,4,5)P-3 biosensor LIBRAvIII. The area of this increase expanded like an intracellular Ins(1,4,5)P-3 wave as [IP3](i) increased in the stimulated region. A small transient [IP3](i) increase was subsequently seen in neighboring cells. The phospholipase C inhibitor U-73122 abolished these Ins(1,4,5)P-3 responses and resultant Ca2+ releases. The purinergic receptor blocker suramin completely blocked increases in [IP3](i) and the Ca2+ release in neighboring cells, but failed to attenuate the responses in mechanically stimulated cells. These results indicate that generation of Ins(1,4,5)P-3 in response to mechanical stimulation is primarily independent of extracellular ATP. The speed of the mechanical-stimulation-induced [IP3](i) increase was much more rapid than that induced by a supramaximal concentration of ATP (1 mM). The contribution of the Ins(1,4,5)P-3-induced Ca2+ release was larger than that of Ca2+ entry in the Ca2+ response to mechanical stimulation in HSY-EA1 cells.

关键词： Maize   Mechanistic model   Potassium efficiency   Rhizosphere   Sugar beet   Wheat  

摘要： Plant species differ in nutrient uptake efficiency. With a pot experiment, we evaluated potassium (K) uptake efficiency of maize (Zea mays L.), wheat (Triticum aestivum L.), and sugar beet (Beta vulgaris L.) grown on a low-K soil. Sugar beet and wheat maintained higher shoot K concentrations, indicating higher K uptake efficiency. Wheat acquired more K because of a greater root length to shoot dry weight ratio. Sugar beet accumulated more shoot K as a result of a 3- to 4-fold higher K influx as compared to wheat and maize, respectively. Nutrient uptake model NST 3.0 closely predicted K influx when 250 mg K kg(-1) were added to the soil, but under-predicted K influx under low K supply. Sensitivity analysis showed that increasing soil solution K concentration (C-Li) by a factor of 1.6-3.5 or buffer power (b) 10- to 50-fold resulted in 100% prediction of K influx. When both maximum influx (I-max) and b were increased by a factor of 2.5 in maize and wheat and 25 in sugar beet, the model could predict measured K influx 100%. In general, the parameter changes affected mostly calculated K influx of root hairs, demonstrating their possible important role in plant K efficiency.

关键词： Partial derivative of matrix functions   Kronecker product   Lagrangian equations   Robot dynamics   Mechanism dynamics  

摘要： The partial derivatives of scalar functions, vector functions, and matrix functions with respect to a vector variable have many practical applications in the study of dynamics and control of mechanical systems. The paper firstly presents an overview of the matrix calculus related to Kronecker products. Secondly, two theorems establishing the relationship between the time derivative of a matrix and its partial derivative with respect to a vector, and the partial derivative of the product of two matrices with respect to a vector will be presented. Finally, a new matrix form of Lagrangian equations is developed to demonstrate the usefulness of these theorems in the study of dynamics of mechanical systems. (C) 2010 Elsevier Ltd. All rights reserved.