关键词： COPD   肺部感染控制窗(PIC窗)   无创血流动力学   序贯性机械通气  

摘要： 目的应用肺部感染控制窗(PIC窗)指导慢性阻塞性肺疾病(COPD)患者序贯机械通气早期有创转无创通气,对比患者达PIC窗时的无创血流动力学,及不同时机转无创通气对疗效的影响。方法选取47例COPD合并呼吸衰竭患者作为研究对象,按序贯机械通气的不同时机转无创通气分为试验组(24例)和对照组(23例)。试验组达PIC窗即拔除气管插管,切换无创机械通气,并测无创血流动力学;对照组达PIC窗后继续有创机械通气并测无创血流动力学,其后按照谨慎指针拔除气管插管,切换无创机械通气支持。比较两组无创血流动力学指标及疗效。结果两组心排量(CO)、每搏外周阻力(SSVR)比较,差异无统计学意义(P>0.05);两组胸液传导性(TFC)比较,差异有统计学意义(P<0.05)。试验组转无创通气成功率低于对照组(P<0.05)。试验组ICU治疗时间明显短于对照组(P<0.05)。两组好转率比较,差异无统计学意义(P>0.05)。结论 COPD患者序贯性机械通气以PIC窗作为参照指标,可以获得一个较早有创-无创通气切换时机,能改善无创血流动力学指标,明显缩短有创机械通气时间及ICU治疗时间。

关键词： 移动并联机械手   移动双串联机械手   多体动力学建模   加权初值法   数值仿真  

摘要： 提出一种用于验证移动并联机械手动力学建模及数值仿真正确性与有效性的方法。该方法先将移动并联系统某处运动副打开,用关节支反力替代运动副约束,从而形成移动双串联机械手,并以多体动力学理论为指导,在笛卡尔坐标系下分别进行移动并联、双串联机械手动力学建模,采用加权初值法对移动双串联机械手系统进行数值仿真。最后通过对移动并联、双串联机械手动力学数值仿真比较,验证系统动力学模型构建和数值仿真的正确性和有效性。

关键词： 下腔静脉扩张指数   急性加重期慢性阻塞性肺病   机械通气   氧合指数  

摘要： 目的探讨下腔静脉扩张指数(dIVC)对急性加重期慢性阻塞性肺病(AECOPD)机械通气患者血流动力学评估的意义。方法选取2015年1月至2017年1月在我院接受治疗AECOPD患者68例,采用随机法把患者分为对照组和研究组,每组患者各34例。对照组患者给予中心静脉压(CVP)对AECOPD机械通气患者进行输液指导,研究组患者给予重症超声测量dIVC评估对AECOPD机械通气患者对进行输液指导。观察并比较两组患者治疗前后的心率、氧合指数(PaO_2/FIO_2)和脑利钠肽前体(NT-proBNP)水平,比较两组患者撤机时间、住ICU时间和不良事件发生率情况。结果两组患者治疗前心率、PaO_2/FIO_2和NT-proBNP水平比较,差异无统计学意义(P>0.05);治疗后两组患者心率和NT-proBNP水平均较治疗前下降,PaO_2/FIO_2较治疗前上升(P<0.05);研究组心率、NT-proBNP水平下降幅度及PaO_2/FIO_2上升幅度均较对照组大(P<0.05)。研究组患者撤机时间(9.14±1.79)d和住ICU时间(8.67±2.02)d,均显著短于对照组患者(P<0.05)。研究组患者重新插管率11.8%、病死率0.0%及呼吸机相关性肺炎(VAP)率2.9%均低于对照组患者(P<0.05)。结论评估下腔静脉扩张指数来指导AECOPD机械通气患者输液,可以降低患者心率及NTproBNP水平,改善PaO_2/FIO_2,缩短住ICU时间、带呼吸机时间,减少不良事件发生率,值得临床推广应用。

关键词： 药物筛选   细胞机械特性   动力学建模   系统辨识  

摘要： 细胞是构成生命体的基本单元，且包含生命体的全部生物学信息。细胞的机械特性与细胞生理状态及生物学行为之间有着密切的联系，比如细胞分裂、细胞生长、细胞分化、细胞迁移等。因此细胞的机械特性可以作为一种反映细胞信息的自然的生物学标记。此外，细胞的机械特性还与人类的某些疾病的产生与发展有关。建立单细胞机械特性的数学模型将对理解单细胞的行为学和某些疾病的产生机理有很大的帮助。然而，单细胞内部却有极其错综复杂的信号传导通路网络。从机理上研究，建立单细胞机械特性的数学模型将非常困难。本文从系统科学的观点出发，利用系统辨识的方法，建立细胞机械特性的数学模型。在此基础上，开展了基于细胞机械特性模型的组合药物优化筛选方法、细胞分类与生理状态表征等研究工作。本文具体开展研究工作如下。\n (1)提出了基于系统科学的单细胞机械特性动力学建模方法:针对传统的单细胞机械特性模型的特点，基于系统辨识的方法，提出了单细胞粘弹性动力学建模方法。\n (2)提出了基于Markov随机过程的组合药物优化筛选方法:在单细胞机械特性模型基础上，提出了针对组合药物筛选的优化算法。并且通过仿真对该算法的准确性和快速性进行验证。\n (3)实验、模型验证与应用:利用原子力显微镜获取单细胞的机械特性曲线，在细胞机械特性动力学模型的基础上进行模型验证。并且利用该模型实现了细胞分类，细胞生理状态表征等应用。\n 综上所述，本文对单细胞机械特性进行了动力学建模与分析，并在此基础上进行了模型验证与应用。本文为单细胞机械特性的研究提供了理论基础，和基于细胞机械特性系统模型的潜在的临床应用。

关键词： Disturbance   Fire management   Functional traits   Habitat accommodation model   Pyrodiversity  

摘要： Models based on functional traits have limited power in predicting how animal populations respond to disturbance because they do not capture the range of demographic and biological factors that drive population dynamics, including variation in trophic interactions. I tested the hypothesis that successional changes in vegetation structure, which affected invertebrate abundance, would influence growth rates and body condition in the early-successional, insectivorous gecko Nephrurus stellatus. I captured geckos at 17 woodland sites spanning a succession gradient from 2 to 48 years post-fire. Body condition and growth rates were analysed as a function of the best-fitting fire-related predictor (invertebrate abundance or time since fire) with different combinations of the co-variates age, sex and location. Body condition in the whole population was positively affected by increasing invertebrate abundance and, in the adult population, this effect was most pronounced for females. There was strong support for a decline in growth rates in weight with time since fire. The results suggest that increased early-successional invertebrate abundance has filtered through to a higher trophic level with physiological benefits for insectivorous geckos. I integrated the new findings about trophic interactions into a general conceptual model of mechanisms underlying post-fire population dynamics based on a long-term research programme. The model highlights how greater food availability during early succession could drive rapid population growth by contributing to previously reported enhanced reproduction and dispersal. This study provides a framework to understand links between ecological and physiological traits underlying post-fire population dynamics.

关键词： POLYMERIC nanocomposites   POLYURETHANES   METHACRYLATES   MULTIWALLED carbon nanotubes   X-ray scattering  

摘要： Nanocomposites based on polyurethane-poly(2-hydroxyethyl methacrylate) semi-interpenetrating polymer network (PU-PHEMA semi-IPN) doped with 0.01, 0.05, 0.1, or 0.25 wt% of non-functionalized multi-walled carbon nanotubes (MWCNTs) were synthesized. Their nanostructure was studied by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) techniques, and their dynamics and properties were characterized over the temperature range from -100 degrees C to 180 degrees C using dynamic mechanical analysis (DMA) and laser-interferometric creep rate spectroscopy (CRS). It was shown that ultra-low MWCNT contents (0.01%-0.1%) substantially modified matrix nanostructure due to the influence of nanofiller on the processes of micro-phase separation and mixing of matrix components, the changes in the molecular packing density, and good dispersion of MWCNTs. The structural changes were somewhat smaller at 0.25% nanotubes where tendency to formation of their aggregates was observed. Accordingly, the strong changes in dynamic behavior, elastic properties and creep resistance in the studied materials were caused by ultra-low MWCNT additives. The strong effect of extraordinary broadening of the PHEMA relaxation peak in the nanocomposites and, simultaneously, the strongly improved creep resistance over the 80 degrees C-160 degrees C temperature range (at 0.1% MWCNTs) were shown that is of importance for the application of these nanocomposites as perspective damping materials. POLYM. COMPOS., 39:263-273, 2018. (c) 2016 Society of Plastics Engineers

关键词： Cellulose nanocrystal   Liquid silicone rubber   Curing kinetics   Mechanical properties   3-Aminopropyltriethoxysilane  

摘要： To prepare liquid silicone rubber (LSR)/cellulose nanocrystal (CNC) nanocomposite, 3-aminopropyltriethoxysilane (APTES) was used to modify the surface of CNC to improve the interfacial interaction between the hydrophilic CNC and the hydrophobic LSR. Fourier transform infrared spectroscopy and energy dispersive spectrometer results demonstrated that APTES modified CNC successfully. It was found that small amount of modified CNC (M-CNC) had better reinforcement than SiO2 in LSR nanocomposites, the tensile strength and the strain at break of LSR increased over 85% and 44% by adding 1.5 wt% M-CNC. However, DSC and rheology tests indicated that APTES modified CNC increased the curing temperature of LSR and limited the addition of CNC, which was attributed to poisoning of Pt catalyst by APTES. Furthermore, small amount of M-CNC improved the thermal stability of LSR, the TGA results showed that the 10% weight loss temperature (T-10%) of LSR increased 56 degrees C with 1.0 wt% addition of M-CNC.

关键词： Monazite   Sintering kinetics   HT-ESEM   Hot pressing   Texture effects   Microhardness  

摘要： This work focuses on the effect of precursor morphology on the microstructural evolution of monazite-type lanthanum-europium phosphate ceramics during sintering, including grain growth rate, as well as correlations between microstructure, texture effects and their mechanical properties. Sintering kinetics of La0.5Eu0.5PO4 powders with two different grain morphologies (needle-shaped and spherical) was studied by an in situ HT-ESEM method at 1340 degrees C. La0.5Eu0.5PO4 pellets with high density (99% of the theoretical density) were obtained for both precursor powders by hot pressing. Analysis of XRD data collected for the hot pressed pellets obtained from needle-shaped precursors revealed preferential orientation of the grains towards the (100) direction. Mechanical properties of the hot pressed pellets were studied by the Vickers indentation method. The dependence of microhardness and fracture toughness on microstructure and texture was investigated.

关键词： Atomic force microscopy  

摘要： Single-molecule force spectroscopy by atomic force microscopy allows us to get insight into the mechanical unfolding of membrane proteins, and a typical experiment exhibits characteristic patterns on the force distance curves. The origin of these patterns, however, has not been fully understood yet. We performed coarse-grained simulation of the forced unfolding of halorodopsin, reproduced the characteristic features of the experimental force distance curves. A further examination near the membrane-water interface indicated the existence of a motif for the force peak formation, i.e., the occurrence of hydrophobic residues in the upper interface region and hydrophilic residues below the lower interface region. (C) 2017 Elsevier B.V. All rights reserved.

关键词： BVOCs   Camphene   OH radical   IRC   Rate constant   Lifetime  

摘要： Present manuscript represents the DFT studies on the oxidation reaction of camphene initiated by OH radical and fate of product radicals using M06-2X functional along with 6-31+G(d,p) basis set. Intrinsic reaction calculation is done for transition states involving OH-addition reactions which proceed via reaction complexes proceeding to the formation of transition states. The rate constant calculated by using canonical transition state theory at 298 K and 1 atm is found to be 5.67 x 10(-11) cm(3) molecule(-1) s(-1) which is in good agreement with the experimental rate constant. The atmospheric lifetime of the titled molecule has also been reported in our work.