关键词： graphene   molecular dynamics   nitrogen   tensile strength  

摘要： We investigated the mechanical properties of nitrogen-containing graphene under tensile loading via molecular dynamics (MD) simulations. In the MD simulation, we used three types of potential functions: the second-generation reactive empirical bond order (REBO) potential for covalent C-C bonds, the Tersoff potential for covalent C-N bonds, and the Lennard-Jones potential for the interlayer interaction of graphite. We studied the effects of nitrogen content and different distributions of nitrogen atoms in graphene on its properties. It was found that nitrogen content of up to 4% had little effect on the mechanical properties of graphene, except when two nitrogen atoms contained in graphene adjoined each other.

关键词： Leaves   Carboxylation   Photosynthesis   Carbon dioxide   Light   Conifers   Plant respiration   Solar radiation  

摘要： Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles;however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO2 concentration. To account for this known variability in nitrogen-photosynthesis relationships, we develop a mechanistic nitrogen allocation model based on a trade-off of nitrogen allocated between growth and storage, and an optimization of nitrogen allocated among light capture, electron transport, carboxylation, and respiration. The developed model is able to predict the acclimation of photosynthetic capacity to changes in CO2 concentration, temperature, and radiation when evaluated against published data of V-c,V-max (maximum carboxylation rate) and J(max) (maximum electron transport rate). A sensitivity analysis of the model for herbaceous plants, deciduous and evergreen trees implies that elevated CO2 concentrations lead to lower allocation of nitrogen to carboxylation but higher allocation to storage. Higher growing-season temperatures cause lower allocation of nitrogen to carboxylation, due to higher nitrogen requirements for light capture pigments and for storage. Lower levels of radiation have a much stronger effect on allocation of nitrogen to carboxylation for herbaceous plants than for trees, resulting from higher nitrogen requirements for light capture for herbaceous plants. As far as we know, this is the first model of complete nitrogen allocation that simultaneously considers nitrogen allocation to light capture, electron transport, carboxylation, respiration and storage, and the responses of each to altered environmental conditions. We expect this model could potentially improve our confidence in simulations of carbon-nitrogen interactions and the vegetation feedback

关键词： flow cytometry   high-throughput   cytology   mechanophenotype  

摘要： Cell state is often assayed through measurement of biochemical and biophysical markers. Although biochemical markers have been widely used, intrinsic biophysical markers, such as the ability to mechanically deform under a load, are advantageous in that they do not require costly labeling or sample preparation. However, current techniques that assay cell mechanical properties have had limited adoption in clinical and cell biology research applications. Here, we demonstrate an automated microfluidic technology capable of probing single-cell deformability at approximately 2,000 cells/s. The method uses inertial focusing to uniformly deliver cells to a stretching extensional flow where cells are deformed at high strain rates, imaged with a high-speed camera, and computationally analyzed to extract quantitative parameters. This approach allows us to analyze cells at throughputs orders of magnitude faster than previously reported biophysical flow cytometers and single-cell mechanics tools, while creating easily observable larger strains and limiting user time commitment and bias through automation. Using this approach we rapidly assay the deformability of native populations of leukocytes and malignant cells in pleural effusions and accurately predict disease state in patients with cancer and immune activation with a sensitivity of 91% and a specificity of 86%. As a tool for biological research, we show the deformability we measure is an early biomarker for pluripotent stem cell differentiation and is likely linked to nuclear structural changes. Microfluidic deformability cytometry brings the statistical accuracy of traditional flow cytometric techniques to label-free biophysical biomarkers, enabling applications in clinical diagnostics, stem cell characterization, and single-cell biophysics.

关键词： 建设工程   施工设备   建筑机械   液压设备  

标准号: GB/T 28391-2012

摘要： 本标准规定了人力移动式液压动力站（以下简称动力站）的范围、分类、要求、试验方法和检验规则。 本标准适用于以中小型发动机为动力源、通过手推或手拉来进行移动的液压动力站。该类液压动力站主要用于驱动手持式液压破碎镐等手持式液压施工工具（以下简称液压工具）。

关键词： 割草机   林业设备   农机具   林业机械  

标准号: GB/T 14176-2012

摘要： 本标准规定了以汽油机为动力的便携式割灌机和割草机的术语和定义、技术要求、试验方法、检验规则、标志、使用说明书、包装、运输和贮存。 本标准适用于以汽油机为动力的便携式割灌机和割草机，其他以内燃机为动力的割灌机和割草机亦可参照使用。

关键词： 研究与开发   动力机械   技术创新战略   农业装备产业   “十一五”   科技支撑   洛阳市   河南省  

摘要： 4月20日，五征承担的“可变地隙与轮距动力机械研究与开发”课题在河南省洛阳市顺利通过农业装备产业技术创新战略联盟的验收，这是五征承担的第二个“十一五”国家科技支撑计划。

关键词： 工程机械行业   后处理系统   菲亚特   SCR   科技   国际   巴黎   低NOx  

摘要： 菲亚特动力科技（F阳）的展台位于菲亚特工业集团3600m。的展区内，展示了为工程机械行业所用的F5、NEF和Cursor系列发动机。通过采用单一的SCR后处理系统，菲亚特发动机可有效降低NOx达95％以上。

关键词： 温室   机器人   3P3R机械臂   Kane方法   动力学分析  

摘要： 针对温室等设施农业环境,设计了一种具有3P3R机械臂结构的机器人,为了分析机械臂的操作性能并实现精确运动控制,对机械臂进行了运动学和动力学分析;采用Kane方法和旋量理论分析方法建立了机器人的操作臂运动学和动力学模型,利用该模型,针对原理样机的具体结构,在Mathematica环境下研究了机械臂的操作性能,得到在一定作业任务规划下,末端执行器的位姿变化规律,以及按照该规划轨迹运动时各关节的驱动力;结果表明,结合了Kane方法和旋量理论的动力学模型具有准确、简单、有效等特点,能够满足机械臂的运动学、动力学分析的要求。

关键词： 学生   工程学院   辅导   机械   大学   河南   护航   成才  

摘要： 他们,忠诚于党的教育事业,模范履行辅导员职责,善于用思想去影响学生、用行动去感染学生,用大爱演绎出一幕幕青春的华彩乐章,被称为学生健康成长的＂指导者＂。

关键词： 虚拟样机   动力学分析   轻量化   静力学仿真   动力学仿真  

摘要： 针对老人服务机器人机械臂的功能要求,提出了一种老人服务机器人的串联型六关节机械臂轻量化的设计方法。建立了机械臂的牛顿-欧拉动力学方程,并利用动力学方程的分析结果,选择了机械臂的直流伺服电机和减速系统等部件。在虚拟样机的基础上对机械臂进行了轻量化设计,包括利用CAD软件设计机械臂机构,利用CAE仿真软件对机械臂进行了静力学和动力学仿真,校验分析结果,选择能够实现机械臂轻量化的机械臂构架的材料,优化构架的结构。