Dynamic mechanical properties of poly-ether-urethane elastomers with chain-extended or chain-folded molecularly uniform poly (N-alkylurethane) hard segment domains

Segmented polyetherurethanes with distinctively different morphologies, i.e., with chain-extended or chain-folded crystallized hard segments, could be created by small constitutional changes in the hard segment architecture. The different superstructure was achieved by building-in specially designed constitutional units in the middle of the otherwise regularly built hard segment which for flexibility or sterical reasons allowed an adjacent reentry chain-folded and/or chain-extended crystallization of the hard phase forming polyurethane segments. The material properties of the thermoplastic elastomers correlated systematically with the hard domain superstructure which was determined by the primary structure of the macromolecule and could be reversibly altered by the thermal history in the case of the flexible center unit. The softening temperature was determined by the hard domain height of the chain-folded lamellar or the chain-extended cylindrical domains; variation of the modulus in the elastomeric region could be related to imperfections in the hard segment packing which affected the effective hard domain filler.     

Enhanced pseudotargeted analysis using a segment data dependent acquisition strategy by liquid chromatography–tandem mass spectrometry for a metabolomics study of liquiritin in the treatment of depression

An enhanced pseudotargeted method using a segment data‐dependent acquisition mode based on ultra‐high performance liquid chromatography–tandem mass spectrometry was developed. This segment data dependent acquisition‐based pseudotargeted method could improve the detection of co‐eluted ions and extend the coverage of analytes. A set of 502 multiple reaction monitoring channels were obtained by this segment strategy, which was twice the number created by the traditional data‐dependent acquisition mode. Compared with the untargeted method, the pseudotargeted profiling demonstrated higher sensitivity and higher precision. More than 90% of the metabolites detected by the enhanced pseudotargeted method had relative standard deviations less than 15%. The segment data dependent acquisition‐based pseudotargeted method was successfully applied to the metabolomics study of the depressed rats with the treatment of liquiritin. Forty‐seven differential metabolites were screened and five metabolic pathways were found to be related to depression including retinol metabolism, phenylalanine, tyrosine, and tryptophan biosynthesis, phenylalanine metabolism, terpenoid backbone biosynthesis, and lysine degradation. The segment data dependent acquisition‐based pseudotargeted method widened the coverage of metabolites with good sensitivity and precision, which exhibited great potential in the discovery of differential metabolites in metabolomics studies.     

Spanning 3-ended trees in k-connected K 1,4-free graphs

A tree with at most m leaves is called an m-ended tree.Kyaw proved that every connected K1,4-free graph withσ4(G)n-1 contains a spanning 3-ended tree.In this paper we obtain a result for k-connected K1,4-free graphs with k 2.Let G be a k-connected K1,4-free graph of order n with k 2.Ifσk+3(G)n+2k-2,then G contains a spanning 3-ended tree.     

一种基于分层的人类动作识别和定位算法研究

人类动作识别在视频自动分析、视频检索等领域获得广泛应用,是目前的研究热点。然而现有的动作识别方法重点关注视频的非静态部分而忽略大部分静态部分,从而影响了动作识别和定位的效果。本文提出一种新的分层空间-时间分段表示法,以分层方式实现部位和整个身体的多分辨率表示,可用于运动识别和定位。该算法分为3个步骤。第一步,首先对每个视频帧进行分层分段,以得到一组分段树,每颗树是身体分段树的候选。第二步,利用视频的轮廓、接合对象结构、全局前景色等信息对候选分段树进行修剪。第三步,在时域上对剩余分段层的每个分段进行前向和后向跟踪。我们以难度较大的UCF-Sports和HighFive数据集为实验对象,对本文方法进行性能评估,实验结果表明,本文方法的性能要优于当前最新运动检测算法性能,运动定位性能与当前最新算法相当。     

柔性铰链机构柔节疲劳寿命的设计及研究

围绕基于迈克尔逊干涉仪傅里叶变换光谱仪的动镜支撑机构——柔性铰链机构的柔节疲劳寿命问题,先通过相关公式计算选取出机构柔节的各个参数,并由这些参数建立机构的有限元模型;然后再根据材料属性参数,利用疲劳分析软件msc.fatigue,通过拟合疲劳寿命S-N曲线来对机构的柔节参数进行仿真验证.从分析结果可知:柔节破坏点的寿命...     

新一代遥测网络系统及其传输组网方式研究分析

新一代遥测网络系统(TmNS)包括试验对象端(TAS)和地面站端(GSS)两大部分,在对这两部分的功能结构,包括系统组成,各组成单元功能关系进行研究的基础上,依据飞行试验遥测传输需求,对新一代遥测网络系统的传输与组网方式进行研究分析。     

多肽酰肼连接法合成C端香豆素修饰的泛素

C端用香豆素修饰的泛素分子（Ub-AMC）是研究蛋白质泛素化过程的重要探针.该探针分子的制备目前主要依靠生物表达结合化学修饰的方法,合成效率较低.本文使用多肽酰肼连接反应,发展出化学全合成Ub-AMC分子的新路线.该方法通过N到C顺序两次连接实现了目标分子的组装,再通过自由基脱硫反应得到天然结构的Ub-AMC分子,有望实现较大量的合成.通过酶学活性实验,证实了通过新方法合成的Ub-AMC具有预期的生物活性.     

4×2×3阵列式放大器参数测量系统优化设计

采用软边光阑和多级空间滤波器组合技术实现了光束的空间整形和等像面传输,利用Fresnel光束传输计算程序对4×2×3阵列式放大器参数测量系统进行了优化设计,分析了空间滤波器中小孔尺寸对光束波面传输的影响,并对优化设计结果进行了分析和讨论,所用方法和所得结论对高功率固体激光放大系统的设计有应用意义。