基于荧光猝灭的光纤DNA传感器的构建及其性能研究

以钌(Ⅱ)多吡啶配合物[Ru(bipy)2DAFND](Cl O4)2(Ru-DAFND,bipy=2,2'-联吡啶,DAFND=4,5-二氮杂芴-9-对硝基苯腙)为指示剂,采用锁相放大技术构建了基于荧光猝灭原理的光纤DNA传感器,研究了传感器的性能。以p H 7.1的Tris缓冲溶液为介质,在2.6×10-8~5.4×10-6mol/L范围,ct DNA浓度与传感器光学敏感膜的相对滞后相移(Δφ)有较好的线性关系,检出限为8.4×10-9mol/L,响应时间为70 s。通过研究溶液p H值和干扰物对传感器性能的影响,表明该传感系统具有较好的重复性和稳定性。     

SAXS and WAXD study of periodical structure for polyacrylonitrile fiber during coagulation

Small angle X‐ray scattering (SAXS) and wide angle X‐ray diffraction (WAXD) were adopted to investigate the formation and development of high order structure within polyacrylonitrile (PAN) precursor during coagulation. The scattering signal came from the microvoids and long period structure was separated reasonably by the analog computation method of decomposition of the one‐dimensional profile. Based on the established methodology, the statistic parameters of long period structure, such as length of the long period structure, crystalline region and amorphous region, were obtained by the analysis of correlation function. The results indicated that during the coagulation, the length of long period of the nascent coagulated fiber was 56.1 nm (meridional direction) and 35.6 nm (equatorial direction), respectively. The evolution of the long period during the coagulation was also discussed by combining WAXD data. With the processing of coagulation, the long period was decreased since the crystallinity increased. Copyright © 2014 John Wiley & Sons, Ltd.     

Estimating deflection of a simple beam model using fiber optic bragg-grating sensors

In this paper, we develop a method to estimate the bridge deflection using fiber optic Bragg-grating (FBG) strain sensors. For most structural evaluation of bridge integrity, it is very important to measure the geometric profile, which is a major factor representing the global behavior of civil structures, especially bridges. In the past, because of the lack of appropriate methods to measure the deflection curve of bridges on site, the measurement of deflection has been restricted to just a few discrete points along the bridge, and the measuring points have been limited to the locations installed with displacement transducers. However, by applying classical beam theory, a formula is rearranged to estimate the continuously deflected profile by using strains measured directly from several points. In addition, FBG strain sensors, which are electromagnetic, noise-free and multipoint measurable, are employed to obtain flexural strains more accurately and stably. The regression analysis is performed to obtain a strain function from the measured strain data. Finally, the deflection curve can be estimated by applying the strain function to the formula. An experimental test has also been carried out to verify the developed method.     

Two-dimensional stability problem for two interacting short fibers in a composite: In-line arrangement

A solution is found to a plane problem for a composite material reinforced with two in-line fibers and subjected to longitudinal compression. The problem formulation is based on the piecewise-homogeneous model and the three-dimensional theory of stability. The dependence of the critical strain and buckling mode on the distance between the fibers is studied for various mechanical and geometrical characteristics of the composite components.Translated from Prikladnaya Mekhanika, Vol. 40, No. 9, pp. 65–74, September 2004.     

稀土处理玻璃纤维填充聚四氟乙烯复合材料在油润滑下的摩擦学性能

分别用偶联剂、稀土以及偶联剂 -稀土混合物处理玻璃纤维表面 ,以改善玻璃纤维与聚四氟乙烯之间的界面结合力 ,考察了玻璃纤维填充聚四氟乙烯复合材料在油润滑下的摩擦学性能 .结果表明 :在油润滑条件下 ,表面处理玻璃纤维填充聚四氟乙烯复合材料的摩擦系数比未经处理玻璃纤维填充聚四氟乙烯复合材料的低 ,耐磨性亦较优 ;而稀土处理玻璃纤维填充聚四氟乙烯复合材料具有最低的摩擦系数及最高的耐磨性和极限 pv值 ;未经处理玻璃纤维填充聚四氟乙烯复合材料的磨损形式主要为粘着转移 ,偶联剂处理玻璃纤维填充聚四氟乙烯复合材料和偶联剂与稀土处理玻璃纤维填充聚四氟乙烯复合材料均以磨粒磨损为主 ,而稀土处理玻璃纤维填充聚四氟乙烯复合材料的磨损机理主要为粘着磨损和轻微磨粒磨损     

负温钢纤维混凝土受压损伤过程的实验研究

利用岩石力学试验系统(RMT)对负温下钢纤维混凝土进行了单轴压缩实验,测得了-5℃、-10℃、-15℃、-20℃下钢纤维混凝土的应力-应变曲线、杨氏模量、极限应力、泊松比等。实验结果表明材料的强度、杨氏模量随温度的下降而上升,尤其是当温度由-10℃下降至-15℃时,这些物理量变化特别显著,之后它们将逐渐趋于某一稳定值。本文对钢纤维混凝土力学性能的温度效应进行了分析并对实验结果进行了细观上的讨论。最后针对负温钢纤维混凝土应力-应变曲线的特点,基于塑性力学和损伤力学理论,建立了负温钢纤维混凝土的含损伤本构方程。该方程物理概念清晰,形式简单,具有一定的应用参考价值。     

An experimental study of flow-induced fiber orientation and concentration distributions in a concentrated suspension flow through a slit channel containing a cylinder

Flow-induced fiber orientation and concentration distributions were measured in a concentrated fiber suspension (CFS) and a dilute one (DFS). The channel has a thin slit geometry containing a circular cylinder. In the previous work, many researchers have qualitatively studied fiber orientation and concentration distributions in injection-molded products of fiber-reinforced plastics. In the present work, however, they are quantitatively estimated by direct observation of fibers in the concentrated suspension flow. For the CFS, some fibers rotate in an expansion part between the channel wall and the circular cylinder, and the fiber orientation becomes almost random state. On the other hand, fibers are perfectly aligned along the flow direction owing to the elongational flow near the centerline downstream of the cylinder. The fiber concentration has a flat distribution except near the channel wall and the centerline. For the DFS a minimum in the fiber concentration distribution was clearly observed on the centerline, and two peaks beside the centerline and near the channel wall. This characteristic distribution is caused by the fiber-wall and fiber-cylinder interactions. It is found that the obstacle such as the circular cylinder in the channel significantly affects the fiber orientation downstream of the obstacle for the CFD, while it affects the fiber concentration distribution for the DFS.     

Zur analytischen Beschreibung des Füllstoffeinflusses auf das Fließverhalten von Kunststoff-Schmelzen

From literature some representative equations have been compiled describing the influence of filler on the viscosity of polymer melts. By application of these on the experimental results obtained from GF-SAN it was found that the relative viscosity _R , i.e. the ratio of the viscosities of the filled and unfilled melt, shows a pronounced dependence on the shear rate but not on the shear stress. Defining _R with constant and not with constant (as it is usually done), an analytical approach is possible independent of Further the influence of pressure, temperature and filler content on the zero-shear viscosity of filled polymer melts may be expressed by a modified Arrhenius equation.

     

Theoretical analysis of non-uniform extensional flows in relation to processing rheology and predictions of some constitutive equations

In this paper, a characteristic equation involving the stream function, already given by one of the authors in a previous work for classifying axisymmetric incompressible flows, is re-considered. Non-uniform nearly extensional flows are derived as particular solutions from this equation. Using experimental data in the literature for polymer solutions and melts, it is proved that particular solutions of the characteristic equation lead to kinematics very close to those encountered in the fiber-spinning process. The kinematic equations satisfactorily correlating the fiber-spinning data are used in order to determine the ability of constitutive equations to predict realistic stresses in the flow domain. The rheological parameters of the fluids, obtained from experiments, are used for computation of differential and integral constitutive equations in the spinning conditions. Comparisons with the stress response of adequate constitutive equations are given and discussed.Also affiliated to: Université Joseph Fourier Grenoble I and Institut National Polytechnique de Grenoble, Associé au CNRS (URA 1510)     

纤维墙元模型在剪力墙结构非线性分析中的应用

钢筋混凝土剪力墙是目前高层与超高层建筑中最主要的抗侧力构件，本文在对已有的微观及宏观计算模型进行比较的基础上，基于纤维模型概念，建立了便于高层剪力墙结构非线性分析应用的纤维墙元模型，即由承受轴力及弯矩的纤维子单元与承受剪切变形的剪切子单元相合成的墙元计算模型；同时，对该模型中剪切子单元高度的取值进行了分析，明确了其物理含义；推导了单元的刚度矩阵，并分别建立了纤维子单元及剪切子单元的骨架曲线及滞回规则。另外，应用该计算单元模型，对一栋40层框架剪力墙结构进行了非线性时程分析，计算结果与相应模型的振动台试验结果进行了对比，比较结果表明两者在结构动力特性，位移响应方面等均吻合较好，验证了该计算单元模型的准确性与有效性，可为推广使用提供参考。