Biotechnology research profile of India

Summary The study explores the chronological growth of Indian Biotechnology. Applicability of Lotka's law has been examined for the authorship pattern. Productivity of authors is analyzed and a list of 35 authors publishing more than 10 publications is given. Bradford's law of scattering is used to identify the core journals which cover most of the research and development output of Indian Biotechnology. The study also shows the active authors, institutions and statewise distributions of Indian Biotechnology research output.     

Biotechnology in gold processing

The applicability of a biotechnological approach for extracting gold from lean grade and refractory ores and from tailings is analysed. Microbiological as well as physicochemical characteristics of various leaching bacteria are outlined. Technological aspects of bioleaching of refractory gold-bearing concentrates in specially designed bioreactors are illustrated with emphasis on control parameters and use of metal and temperature-tolerant strains. Commercial operations prevalent across the world are detailed and the relevance of biomineral technology for augmentation of gold production in India brought out.     

生物技术在食品检验中的应用

随着经济社会的发展,人们生活质量的提高,食品质量的安全问题也日益受到人们的关注,而高效准确的食品检验方法是保障食品安全的重要前提,本文详尽的介绍了几种常见且简单高效的生物检测技术在食品检验方法中的应用及研究进展,并进行了较为全面的分析,以供参考。     

Biotechnology and its public

The author provides a perspective on three key areas of biotechnology: the public debate over hazards, the commercialization of the technology, and ethical issues that are arising in terms of application of genetic therapy to humans. He reviews the history of the recombinant DNA research debate beginning at Asilomar in 1975, when the molecular biologists called for a temporary moratorium on certain experiments, so the NIH might develop guidelines to govern this research. The author then characterizes the lobbying activities of the biologists against proposed regulation at the federal, state and local level. Despite the lobbying, he concludes that Congress did not enact legislation because of the exemplary behavior of the biologists, beginning with their meeting at Asilomar. The author next describes the impact commercialization of this technology will have on academic biologists who traditionally have not been involved in that process (as have chemists and physicists). He also comments on the ethics of biotechnology, concluding that the more powerful biology becomes, the more its uses and some control of those uses will be debated.     

Biotechnology and the lawmakers

The author reviews the origins of the public policy debate concerning recombinant DNA technology and Congressional consideration of legislation to regulate recombinant DNA research. He notes especially his successful attempts to urge delay in passing legislation until there was complete evaluation of data — studies that ultimately resulted in noting that potential hazards were not as great as originally conceived. The author comments that strict regulation of recombinant DNA research, as proposed by some legislators, would have inhibited many of the great benefits that society is now receiving from this research. The author then raises a number of questions concerning government regulation and funding priorities on scientific and technological innovation, as well as government practices regarding basic and applied research in industrial and academic laboratories. A major concern of his is the government's ability to assess and manage risk. The author reviews one legislative proposal, which would have established risk analysis demonstration projects, and outlines a number of legislative initiatives that could impact the biotechnology industry and university-based research. He concludes by discussing opportunities for industrial applications of this technology and possible roles for Congress.     

铝合金型材拉弯成形回弹的有限元模拟

对回弹进行有效预测与控制是提高型材弯曲件精度的关键.为了分析轴向作用力对拉弯制件回弹的影响,采用动力显式有限元仿真软件Pam-Stamp2000对中空矩形截面铝型材AA6082(T5)转臂式拉弯成形过程进行了数值模拟,并与实验结果进行了对比.结果表明:增加预拉可以减小制件的回弹,但预拉达到一定水平后,继续加大预拉力对减小回弹将基本不起作用;当预拉不充分时,增加补拉同样有利于减小制件的回弹,但过大的补拉力对于减小回弹几乎没有任何帮助.可见,型材拉弯成形制件的回弹不仅与加载顺序及加载程度密切相关,同时也受到材料应变硬化特性的制约.     

Broadened X-ray-diffraction profile analysis of cold-rolled aluminium-magnesium alloys

A cold-rolled, commercial pure aluminium and three aluminium-magnesium alloys (containing, respectively, 1 wt%, 3 wt% and 5 wt% magnesium) were studied by X-ray-diffraction (XRD) profile analysis. The investigated equivalent plastic deformations of the materials were ranged between 0.1 and 5.0. With increases in the amounts of magnesium, the diffraction peaks widened. For each alloy, the peak width (which gives first information from the analysis) increased for low deformation ratios and reached a maximum value, ds _max and then it decreased or stabilized. The ds _max value increased with increases in the amount of magnesium in the alloys and ranges for equivalent deformation and 1.5. The results of the X-ray profile analysis have been correlated with previous observations by transmission electron microscopy (TEM), and they have been successfully used to quantify the microstructural features of the alloys.     

X-ray diffraction line profile analysis of nanocrystalline graphite

The structure evolution to nanocrystalline graphite produced by ball milling in n-dodecane has been studied by Fourier analysis of broadened X-ray diffraction line profiles according to double-Voigt method. The Fourier analysis gave size and strain distributions of the coherently diffracting domains (X-ray crystallite size) and root-mean-square-strain (rmss) and their average values. The precursor graphite was defined by average crystal sizes of about hundreds of nanometers, measured along the in-plane and out-of-plane directions, and low rmss value of 0.38 × 10⁻³. During milling, the average crystallite sizes of graphite decreased to about 6 and 43 nm along the out-of-plane and in-plane directions, respectively. Correspondingly, the rmss of milled graphite increased to 6.54 × 10⁻³. Analysis of the out-of-plane to in-plane crystallite size ratios showed that the crystallites became progressively thinner and flatter. A linear relationship between rmss and reciprocal crystallite size along the stacking axis revealed that size of disordered boundary regions gradually increased at the expense of ordered crystalline regions. A model describing crystalline–nanocrystalline transformation of graphite along different crystallographic axis was formulated and used to discuss the experimental data. It was concluded that a distortion-controlled process is responsible for the crystalline–nanocrystalline transformation of graphite milled in n-dodecane.     

Determination of kinetic parameters in layer-by-layer growth from RHEED profile analysis

Layer-by-layer growth in Fe/Fe(1 0 0) is studied by scanning tunneling microscopy and reflection-high-energy-electron-diffraction (RHEED). In out-of-phase conditions, satellite structures are observed in the room temperature deposition diffraction patterns. With increasing deposition temperature, these satellites are no longer resolved and only contribute to the broadening of the linewidth. They are interpreted in terms of diffuse scattering associated with island distribution on the surface. Their positions directly reflect the average island separation. As a consequence, the temperature dependence of the RHEED profile can then be used to estimate diffusion parameters.     

Coordinate methods of determining average-circle parameters in actual surface profile analysis

Practical methods are considered for finding the center coordinates and radius of the mean circle in analyzing the profile geometry of cylindrical surfaces of large bodies. A general method of constructing formulas is proposed for deriving these parameters for small eccentricities. A method is given for obtaining the center coordinates and radius of the mean circle with high accuracy by iteration, which is recommended when the profile coordinates are measured for small and large eccentricities and also when the points are unevenly distributed on the profile.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 22–25, October, 1995.     

X-ray diffraction line profile analysis of diffusional homogenization in powder blends

A new nondestructive method — based on computer simulation of X-ray diffraction line profiles — is proposed to characterize homogenization in compacted binary powder blends. As a parameter to characterize the stage of homogenization the relative peak position is proposed. This parameter is easy to determine in practice: during homogenization the position of an X-ray diffraction maximum is traced. As compared to other methods the present one has the following advantages: (i) it is fast and simple and (ii) it allows a more severe test of the model of interdiffusion applied. Experiments were performed with compacted blends of copper and nickel powders at 800, 900 and 1000° C. At the start of homogenization diffusion was very fast. Experiments at lower temperatures revealed that this was due to surface diffusion at the contact places between the copper and nickel particles with an activation energy of about 12 kcal mol^–1. Because of the sensitivity of the relative peak position to the interdiffusion model adopted it was shown that the generally accepted concentric sphere model: nucleus of nickel and shell of copper, should be modified to include a pre-alloyed shell at the copper/nickel interface at t=0. Then good correspondence between theory and experiment is obtained. Finally it was found that in the temperature range applied one diffusion mechanism is dominant with an activation energy of 32 kcal mol^–1, indicating grain boundary diffusion.     

Spiral profile design and parameter analysis of flexure spring

Universal design method of spiral flexure spring has been generalized firstly. Through adjusting the space location of spiral arms together with parameters of individual spiral profile including base radius, involute pitch, involute angle, start angle of involute, width of slot, various spiral flexure springs with different performances can be obtained respectively. Then the finite element program, whose validity has been verified by experimental data, is used to analyze the performance of the flexure spring. Furthermore experimental study of the spring assembly reveals the superimposed effect of stiffness and the antitorque characteristic of spring stack, which had been ignored previously. Finally, in order to get the general relation between the axial stiffness, natural frequency of flexure spring and its geometry parameters, the theoretical model, which is based on the mechanics of material and vibration, has been set up and subsequently solved. The validity of derived expressions has been proved by finite element program and published experiment data respectively. Those induced expressions are more convenient and direct than finite element method and can be served as the guide to designation of flexure spring.     

Characterization of nanocrystalline materials by X-ray line profile analysis

X-ray line profile analysis is shown to be a powerful tool to characterize the microstructure of nanocrystalline materials in terms of grain and subgrain size, dislocation structure and dislocation densities and planar defects, especially stacking faults and twin boundaries. It is shown that the X-ray method can provide valuable complementary information about the microstructure, especially when combined with transmission electron microscopy and differential scanning calorimetry.     

Depth profile analysis of electrodeposited nanoscale multilayers by SNMS

As early as 10 years after the discovery of the giant magnetoresistance (GMR) the magnetic/non-magnetic multilayers found their first application in the read-out units of magnetic recording media, and the hard disk drives with GMR-based sensors since gained a dominating market share. In spite of the large number of works published on nanoscale multilayers, data on the depth profile of electrodeposited multilayer samples are very scarce. This work deals with the depth profile analysis of electrodeposited CoNiCu/Cu and Co/Cu multilayers films. Commercial Cu sheet and a Cr/Cu layer evaporated onto Si (1 1 1) surface were used as substrates with high and low roughness, respectively. The Secondary Neutral Mass Spectrometry (SNMS) depth profile analysis clearly revealed the layered structure of the samples. The resolution of the individual layers varied with the initial roughness of the substrate. The SNMS spectra showed that the oxygen incorporation into the layers is insignificant. When both Ni and Co are present in the magnetic layer, the composition of the samples is influenced by both the anomalous codeposition properties of the iron-group elements and the mass transport of the corresponding ions in the electrolyte. This observation draws the attention to the possible inhomogeneity of the magnetic layers in electrodeposited samples.