Research on the relationship between cephalosporin structure,solution clarity,and rubber closure compatibility using volatile components profile of butyl rubber closures

Objective: Establish an effective experimental strategy to determine the compatibility of rubber closures for drugs.

Significance: Various types of rubber closures with different compositions are available for drug packaging. Many additives of rubber closures can be released from rubber closures and may affect the quality of drugs and pose a risk to human health. In this study, we aimed to determine the relationship between cephalosporin structure, solution clarity, and rubber closure compatibility using volatile components profile of butyl rubber closures.

Methods: Two opposite polarity gas chromatography (GC) systems and GC-mass spectrometry (MS) were used to achieve rapid qualitative determination of the main volatile components in rubber closures. Simulated adsorption experiment was performed to investigate the adsorption of main volatile components in rubber closures by cephalosporins with different side chain structures, and to determine the effects of adsorption on solution clarity.

Results: A volatile components screening library of rubber closures was established and the structures of some volatile component were confirmed. The specific adsorption of the structure of cephalosporins on volatile components from rubber closures was studied.

Conclusion: Based on the results of this study, rubber closures with good compatibility for cephalosporins with different side chain structures can be selected rapidly. This experimental strategy not only facilitates the screening of suitable rubber closures more effectively, but also enables the quick determination of volatile components adsorbed by drugs.     

基于凸闭包集的不规则三角网算法研究与实现

不规则三角网是影响土石方量计算的关键问题之一，虽然目前已有大量研究人员对Delaunay三角网进行优化，但仍然缺少对三角网生成速率和计算精度的综合研究。针对此问题，基于VB.NET平台的点、边以及三角形的结构化数据结构设计快速生成凸闭包集形成Delaunay三角网，通过四边形空圆特性以及对角线最短原则对构网结果进行检验和优化。试验计算表明，该算法的计算结果与经典DTM法、方格网法的土方量计算相对误差均在0.30%以内。该方法不仅具有较高的组网效率，并能保持较好的计算精度。     

复杂膨胀性围岩条件下交岔点支护技术研究

针对复杂膨胀性围岩条件下交岔点高应力集中区围岩稳定性控制和支护技术难题，通过对交岔点围岩变形表现形式、交岔点围岩变形机理的研究分析，提出了交岔点支护难点及重点。基于围岩控制理论分析，提出了“有限让压的柔性支护+全断面封闭抗压的刚性支护技术”，前期柔性支护采用“高强、高预应力锚杆+锚索+喷浆”联合支护有限度控制围岩变形，允许围岩在可控范围内释放围岩应力|后期通过架设异形支架与支撑架组成的联合支护体并喷射混凝土对交岔点围岩进行全断面封闭抗压支护，有效控制巷道交岔点围岩的变形。确保了交岔点围岩变形的整体可控性、稳定性，达到了预期支护效果。     

Estimation of fatigue crack growth behavior for small-sized C-shaped inside edge-notched tension (CIET) specimen using compliance technique

Being restricted by the relative larger size requirement, traditional and standard fracture specimens are not applicable for the estimation of fatigue crack growth behavior of some very finite-sized components and precious materials. This study develops a small-sized C-shaped inside edge-notched tension (CIET) specimen which has an advantage of specimen minimization and a wide range of adaptability. A systemic compliance technique for estimating fatigue crack growth behavior of CIET specimen has been successfully constructed and experimentally verified. Groups of fatigue crack propagation rate tests of both CIET specimen and CT specimen for 5083-H112 aluminum alloy were carried out. The resulted da/dN ∼ ΔK curves are heavy affected by specimen configuration and load ratio, and the difference between these da/dN ∼ ΔK curves has been successfully removed by introducing the correction of plasticity-induced crack closure effect. Consequently, the feasibility of CIET specimen for estimating fatigue crack propagation behavior for small-sized components and precious materials has been evidently confirmed.     

Data-driven modeling of mesoscale solids stress closures for filtered two-fluid model in gas–particle flows

This study performs data-driven modeling of mesoscale solids stress closures for filtered two-fluid model (fTFM) in gas–particle flows via an artificial neural network (ANN) based machine learning method. The data used for developing the ANN-based predictive data-driven modeling framework is systematically filtered from fine-grid simulations. The loss function optimization result reveals that coupling two loss functions promotes more accurate predictions of the mesoscale solids stresses than using a single loss function. Further comprehensive assessments of closure markers demonstrate a systematic dependence of the mesoscale solids stresses on the filtered particle velocity and its gradient as additional anisotropic markers, instead of using the conventional isotropic filtered rate of solid phase deformation as a closure marker. An optimal three-marker mesoscale closure is thus proposed. Comparative analysis of the conventional filtered model and present three-marker model shows that the data-driven model can substantially enhance the prediction accuracy.     

主跨602m的杨浦大桥主桥安装施工技术

杨浦大桥主桥结构形式为双塔双索面全漂浮体系迭合梁斜拉桥，主跨６０２ｍ，其钢梁安装，斜索张拉和桥面合龙技术是整个工程的关键。     

油墩港大桥连续箱梁施工控制技术

上海市青浦区油墩港大桥是一座主跨80 m的连续梁大桥,采用挂篮对称悬臂浇筑。介绍了对该桥进行施工控制的目的、控制体系、控制的主要监测内容,提出了施工控制中的注意事项。     

Stochastic response of hysteretic systems

This paper deals with approximate stochastic response of hyseretic structures under white noise excitation, based on It stochastic differential equations. Instead of the original system an equivalent nonlinear system is considered, in which the drift vector is given by a series expansion of the order n 1 in terms of the state variables. n = 1 represents the well-known case of equivalent linearization. Components in the drift vector representing the nonanalytical constitutive equations are replaced by a cubic polynomial expansion. The hierarchy of statistical moment equations is closed by a cumulant neglect closure scheme. The method has been applied to a bilinear single degree-of-freedom system subjected to white noise excitation, for which an equivalent system with a cubic series expansion to the constitutive equation is considered. The results obtained are compared with those of numerical simulation and alternative methods, and they provide substantial improvements compared to equivalent linearization.     

芜湖长江大桥板桁组合结构斜拉桥建造技术

芜湖长江大桥是一座跨越长江的公路、铁路两用大桥。为综合解决长江航道,净空限制和满足公路、铁路行车条件,首次采用大跨度低塔斜拉桥板桁组合结构。为解决设计和建设过程中的关键技术问题,进行了荷载,刚度标准,材料,焊接标准和结构构造等方面的系统研究。本文对这些研究成果作了简要介绍。     

不同截流程度下涡街流量计的流动特性研究

对于涡街流量计的旋涡发生体的仿真研究主要集中在形状和尺寸上,但在现场复杂工况环境的情况下,发生体的位置并不是固定不变的,会存在安装偏差。为了很好的分析发生体安装偏差带来的信号强度发生变化的问题,确定不影响信号强度的最大偏差角度,采用三角柱型发生体,在Ansys＋Workbench＋FLUENT 数值仿真软件平台环境下,根据涡街流量计的实际物理结构尺寸建立仿真模型,并对其进行网格划分、求解,将仿真得到的升、阻力频率相比较,得出阻力频率正好是升力频率的2倍,表明可以利用FLUENT软件对涡街流量计进行三维流场数值仿真。最后利用FL U EN T软件,通过改变管截面与截流面的夹角,在低、中、高速流速下,对其进行取压,将得到的信号强度和频谱分布进行比较分析,得出夹角与信号强度的关系：夹角在1°～7°范围,对信号强度的影响不大,超过7°以后影响变大。