Intracellular release of recombinant green fluorescent protein (gfp uv ) from Escherichia coli

The recombinant green fluorescent protein (gfp _uv ) was expressed by Escherichia coli DH5-α cells transformed with the plasmid pGFPuv. The gfp _uv was selectively permeabilized from the cells in buffer solution (25 mM Tris-HCl, pH 8.0), after freezing (−70°C for 15 h), by four freeze (−20°C)/thaw cycles interlaid by sonication. The average content of released gfp _uv (experiment 2) was 7.76, 34.58, 39.38, 12.90, and 5.38%, for the initial freezing (−70°C) and the first, second, third and fourth freeze/thaw cycles, respectively. Superfusion on freezing was observed between −11°C and −14°C, after which it reached −20°C at 0.83°C/min.     

Assessment of CaCl2, NaNO3 and NH4NO3 extraction procedures for the study of Cd, Cu, Pb and Zn extractability in contaminated soils

The variety of extraction procedures used in environmental studies makes it very difficult to compare the results obtained; therefore, harmonisation and standardisation is required. The extraction of heavy metals from soil by un-buffered salt solutions is a method used to estimate soil contamination and trace metal availability to plants. The present study assesses three of these methods. All the three methods are standardised or is undergoing standardisation in Europe: 0.01 mol l⁻¹ CaCl₂ (The Netherlands), 0.1 mol l⁻¹ NaNO₃ (Switzerland) and 1 mol l⁻¹ NH₄NO₃ (Germany). The soil-reference material BCR CRM 483, with indicative values for CaCl₂, NaNO₃, NH₄NO₃ extractable metals, was analysed for quality control purposes. The three methods were also applied to 10 contaminated soils and the extracted metals (Cd, Cu, Pb, and Zn) were determined. The procedures were found to be precise (typically <10%) for all metals, taking into account the low metal concentrations extracted. The metal extraction efficiency obtained with each procedure was slightly different, and the three methods provided equivalent information while predicting the relative trace-metal mobility (Cd>Zn>Cu>Pb) in the soils studied. From the experience obtained, the 0.01 mol l⁻¹ CaCl₂ extraction procedure seems to be the most suitable method for performing a harmonisation process, since this procedure combines an appropriate extraction capacity for this type of studies with the lowest salt concentration in the extracts and, consequently, with a more simple matrix for metal determination.     

Some problems in adsorption and calorimetric studies of the steps of catalytic processes

Principal side factors as well as technical and procedural peculiarities capable of distorting the results of measurements of adsorbed and desorbed amounts, of falsifying the nature of the processes proceeding in the systems under study, and of promoting artifacts in calorimetric and other studies of gas chemisorption on powders are considered. Modified techniques and procedures allowing the elimination of sources of side phenomena and artifacts and freeing traditional glass static adsorption apparatuses and experimental procedures from undesirable factors and peculiarities are proposed. Some available chemisorption and calorimetric data representing artifacts and also some data that are not artifacts but,due to imperfections of chemisorption techniques, show up as artifacts are presented and discussed. Several applications of the improved techniques and procedures to calorimetric and adsorption studies of the steps of catalytic processes proceeding on the basis of natural gas and of products of its processing are presented and discussed.     

石油产品常压蒸馏特性测定法处理程序的编制

自行开发了适用于标准《石油产品常压蒸馏特性测定法》的结果计算程序,可自动实现校准数据引入、测试结果数据计算、测试结果超差判断、报表打印页生成等工作.     

On the construction of irredundant coverings of an integer matrix

New estimates are derived for the computational complexity of the problem of constructing irredundant coverings of an integer matrix (search for maximal conjunctions of a special logical function).     

Gun tunnel flow calibration: defining input conditions for hypersonic flow computations

The procedures used to calibrate a hypersonic gun tunnel nozzle flow are described. The values obtained using these methods are then used as input conditions for computations of hypersonic flow over a long slender test body. Only by completely specifying the flow field, including the effects of nozzle flow angularity, can the best agreement between experiment and computations be achieved. Received 18 February 2000 / Accepted 7 July 2000     

Highly accurate algorithms endowing with boundary functions for solving a nonlinear beam equation involving an integral term

In this paper, the problem of a nonlinear beam equation involving an integral term of the deformation energy, which is unknown before the solution, under different boundary conditions with simply supported, 2‐end fixed, and cantilevered is investigated. We transform the governing equation into an integral equation and then solve it by using the sinusoidal functions, which are chosen both as the test functions and the bases of numerical solution. Because of the orthogonality of the sinusoidal functions, we can find the expansion coefficients of the numerical solution that are given in closed form by using the Drazin inversion formula. Furthermore, we introduce the concept of fourth‐order and fifth‐order boundary functions in the solution bases, which can greatly raise the accuracy over 4 orders than that using the partial boundary functions. The iterative algorithms converge very fast to find the highly accurate numerical solutions of the nonlinear beam equation, which are confirmed by 6 numerical examples.     

相机内参量及像差系数与外参量的解耦标定方法

基于无穷远点与相机内参量关系,提出了一种相机内参量及像差系数与外参量解耦标定方法.首先,根据平面单应计算绝对二次曲线在像面的投影方程,线性求解相机内参量;然后,将重投影像点视为理想像点线性求解像差系数,并计算像点重投影误差;最后,将序列图像的平面单应作为待优化参量,以最小化像点重投影误差为目标函数,重复上述过程,输出最优的相机内参量和像差系数.在相同配置下,分别对本文方法和张正友平面靶板标定方法的标定准确度进行仿真与对比分析.基于不同姿态和位置的27幅棋盘格图片,分别利用这两种方法对相机内参量进行标定实验.实验结果表明:与张正友平面靶板标定方法相比,本文方法的标定准确度提高了至少1％;在实物实验中,张正友平面靶板标定方法和本文方法的重投影残差分别为0.064像素和0.008像素.     

Resolución numérica de las ecuaciones del movimiento de edificios de varias plantas con no linealidades severas

This paper presents a new algorithm for solving the equations of motion of multi-storey buildings that incorporate frictional energy dissipators as seismic protection. The behavior of the dissipators is represented by Coulomb dry friction models; they introduce severe nonlinearities in the dynamic behavior of the structure every time that the contact conditions (stick or slip) change in the dissipators. These nonlinearities complicate the resolution of the equations of motion as it usually is described by lumped masses models whose degrees of freedom are the displacements of the floors and, as the stick or slip conditions change, the degrees of freedom must be modified: for blocking conditions they are only the displacements of the storeys while under sliding conditions the displacements of the dissipators have to be also considered. In previous articles the accuracy of the proposed algorithm has been verified by comparison with experimental results; as well, the computational efficiency of the algorithm has been confirmed by comparing the required resources (in terms of computation time and of memory allocation) with those of other algorithms. The objectives of this paper are to describe in detail the numerical solution of the equations of motion and present representative examples confirming the ability of the algorithm to reproduce the dynamic behavior of buildings with friction dissipators and reporting preliminarily about the usefulness of such devices to reduce the oscillations of the structure to be protected.     

基于镜像焦面检测对准标记的套刻性能原位测量技术

套刻性能是现代高精度步进扫描投影光刻机的重要性能指标之一。提出了一种基于镜像焦面检测对准标记(简称“镜像焦面检测对准标记”)的光刻机套刻性能原位测量技术。该技术通过对曝光在硅片上的镜像焦面检测对准标记图形进行光学对准,利用标记图形对准位置与理想位置偏差实现套刻性能的原位检测。实验结果表明该技术在进行套刻误差的精确测量的同时还可以全面、定量地计算影响光刻机单机套刻误差的场内参量及场间参量。与目前套刻性能原位测量技术相比,该技术有效地避免了测量精度对轴向像质限制的依赖,简化了光刻机整机性能检测的过程。