A New Lactam from Cannabis sativa

Chemistry of Natural Compounds - A new lactam, 5-hydroxy-1-[(4-hydroxyphenyl)methyl]-2-pyrrolidinone (1), was isolated from the ethyl acetate extract of Cannabis sativa L. The structure was...     

Investigation on the Interaction of Dy(Ш)/Rutin Complexes with Bovine Serum Albumin by Spectroscopic Methods

Journal of Solution Chemistry - The interaction between Dy(Ш)/Rutin complexes and bovine serum albumin (BSA) was studied by fluorescence, ultraviolet (UV) absorption, three-dimensional...     

Synthesis and bioevaluation of radioiodated nitroimidazole-based hypoxia imaging agents containing different charged substituents

Journal of Radioanalytical and Nuclear Chemistry - In this work, a series of radiolabeled 2-nitroimidazole-based iodotriazoles containing positively charged, negatively charged, or neutral...     

Monitoring the kappa number of bleached pulps based on FT-Raman spectroscopy

Cellulose - A new strategy was proposed to determine the Kappa number of bleached Eucalyptus globulus kraft pulps based on FT-Raman spectroscopy. Before modeling, smoothing (Savitzky-Golay),...     

伪可变体系的几何构造分析

伪可变体系几何可变性的研究，对轻型结构的设计分析已变得十分重要。本文先分析能量与平衡之间的普遍关系，进而得出判定体系可变性的能量准则。通过拉格朗日乘子的引入，建立能量泛函，得出判定极值的二次型。然后证明了乘积力法与能量法的一致性，并讨论了宜于计算机分析实现的矩阵表示方法。结果表明，若二次型确定，则体系伪可变；当半确定时，体系部分伪可变部分可变；否则体系含二阶以上的无穷小机构。     

Study on Deformation of Polycrystalline Aluminum Alloy Using Moiré Interferometry

Polycrystalline aluminum alloy is manufactured by annealing, compared to the width of the specimen, the size of the grains can not be omitted, which makes the specimen anisotropic. Under uniaxial tension, the deformation field is inhomogeneous. In this study, moiré interferometry is successfully applied to measure the deformation of the polycrystalline specimen. The experimental results presented the stress versus strain responses of the marked grains in different orientations and different shapes. By using fringe centering method, the strain distributions under certain load in the centers and on the boundaries of the grains are analyzed.     

An efficient method for structural optimization

Based on the dual theory of nonlinear mathematical programming and the second order Taylor series expansions of functions, an efficient algorithm for structural optimum design has been developed. The main advantages of this method are the generality in use, the efficiency in computation and the capability in identifying automatically the set of active constraints. On the basis of the virtual work principle, formulas in terms of element stresses for the first and second order derivatives of nodal displacement and stress with respect to design variables are derived. By applying the Saint-Venant's principle, the computational efforts involved in the Hessian matrix associated with the iterative expression can be significantly reduced. This method is especially suitable for optimum design of large scale structures. Several typical examples have been optimized to test its uasefulness.     

Experimental investigation of creep-crack-tip deformation using moiré interferometry

High-temperature moiré interferometry was applied to obtain full-field creep-crack-tip displacements of a three-point bend Al 2024-T4 specimen uner constant temperature of 200°C up to 720 hr.C ^* was evaluated by the moiré data obtained at discrete time intervals. Test results indicate that under steady-state creep condition, the creepcrack-tipv-displacement rate agrees with the asymptotic solution based on theC ^* integral. However, no creeping behavior was observed for the crack-tipu-displacement field aftert=276 hr. This discrepancy may be due to the initial large creep-crack-tip blunting and cavitation damage which alter the creep-crack-tip singular field such that theC ^* integral is no longer applicable to characterize the steady-state creep-crack-tip field. Postmortem studies of the tested specimen also revealed transgranular fracture path with the ordered grain boundaries perpendicular to the crack line, which may relate to the existence of the substantial crack-tip blunting and noncreeping behavior of theu-displacement field, i.e., the size and shape of material grain boundaries play an important role in the crack-tip-creeping behavior of the material.Paper was preseted at the 1991 SEM Spring Conference on Experimental Mechanics held in Milwaukee, WI on June 9–13.     

有限元法在三轴转台机械系统设计中的应用

本文探讨了三轴转台机械系统的设计与计算问题，以惯性三轴测试转台和三轴模拟台为例，确定了多种运转状态下的有限元法计算模型，并对其进行了静、动态特性计算，比较分析了计算结果，为合理结构的设计提供了重要数据，说明了在三轴转台机械系统设计中有限元法的重要性     

阻抗式和简单调压室甩荷时水位波动的显式计算方法

目前对调压室水位波动的研究主要有图解法和数值计算。尚未看到考虑阻力项后调压室水位波动随时间变化的显函数计算方法。本文从调压室的基本微分方程出发，采用泰勒级数展开式推导了阻抗式和简单式调压室甩荷时水位波动的显式计算方法。运用这种方法不仅可以计算调压室水位波动的过程，而且可以方便的计算调压室的最高涌浪和第二振幅。