Trace elemental analysis of asbestos with an x-ray fluorescence technique

We have used an X-ray fluorescence spectroscopic technique to quantify the trace elements present in Indian asbestos samples. Elements such as Cr, Mn, Fe, Ni, Cu, Zn and Ba were commonly found in all the asbestos varieties. The differences in the trace element content of Indian samples as compared to other global samples could be attributed to the different geochemical processes involved in the formation of ores at different places. The importance of trace metals has been briefly discussed in relation to their likely adverse biological effects.     

PCI Express的市场、趋势和应用

最终用户需要更多具备多媒体功能的终端，从iPod视频或YouTube这样的博客站点就能看出这一趋势。当用户接收这类数据时，对于有效存储和更高的互连速度的要求变得十分关键。     

Color Generation and Refractive Index Sensing Using Diffraction from 2D Silicon Nanowire Arrays

Tunable structural color generation from vertical silicon nanowires arranged in different square lattices is demonstrated. The generated colors are adjustable using well‐defined Bragg diffraction theory, and only depend on the lattice spacing and angles of incidence. Vivid colors spanning from bright red to blue are easily achieved. In keeping with this, a single square lattice of silicon nanowires is also able to produce different colors spanning the entire visible range. It is also shown that the 2D gratings also have a third grating direction when rotated 45 degrees. These simple and elegant solutions to color generation from silicon are used to demonstrate a cost‐effective refractive index sensor. The sensor works by measuring color changes resulting from changes in the refractive index of the medium surrounding the nanowires using a trichromatic RGB decomposition. Moreover, the sensor produces linear responses in the trichromatic decomposition values versus the surrounding medium index. An index resolution of 10^?4 is achieved by performing basic image processing on the collected images, without the need for a laser or a spectrometer. Spectral analysis enables an increase in the index resolution of the sensor to a value of 10^?6, with a sensitivity of 400 nm/RIU.     

Tool wear, chip formation and workpiece surface issues in CBN hard turning: A review

Steel parts that carry critical loads in everything from automotive drive trains and jet engines to industrial bearings and metal-forming machinery are normally produced by a series of processes, including time-consuming and costly grinding and polishing operations. Due to the advent of super-hard materials such as polycrystalline cubic boron nitride (PCBN) cutting tools and improved machine tool designs, hard turning has become an attractive alternative to grinding for steel parts. The potential of hard turning to eliminate the costs associated with additional finishing processes in conventional machining is appealing to industry. The objective of this paper, is to survey the recent research progress in hard turning with CBN tools in regard of tool wear, surface issues and chip formation. A significant pool of CBN turning studies has been surveyed in an attempt to achieve better understanding of tool wear, chip formation, surface finish, white layer formation, micro-hardness variation and residual stress on the basis of varying CBN content, binder, tool edge geometry, cooling methods and cutting parameters. Further important modeling techniques based on finite element, soft computing and other mathematical approaches used in CBN turning are reviewed. In conclusion, a summary of the CBN turning and modeling techniques is outlined and the scope of future work is presented.     

Simultaneous evaluation of neonicotinoids in cotton seed cake using reverse phase high‐performance liquid chromatography

BACKGROUND: The cotton crop accounts for more than 52% of total insecticide usage in India. Neonicotinoids, being newer insecticides, have found greater use in the northern region. In this study a rapid and sensitive high‐performance liquid chromatography method was developed for measuring neonicotinoid residues in cotton seed cake (CSC). The method involves the extraction of three neonicotinoids from CSC with acetonitrile/water (80:20 v/v), followed by liquid–liquid partitioning and column clean‐up prior to injection. RESULTS: Recoveries at 0.5–2 µg g^?1 spiking levels varied from 95.60 to 79.50% for imidacloprid, from 92.89 to 84.00% for acetamiprid and from 96.96 to 88.36% for thiacloprid. Minimum detectable levels using this method were 5, 10 and 20 ng g^?1 for imidacloprid, acetamiprid and thiacloprid respectively. CONCLUSION: The method developed in this study allows rapid and reliable measurement of the insecticides imidacloprid, acetamiprid and thiacloprid in CSC. Copyright © 2009 Society of Chemical Industry     

Effect of transverse shear and rotatory inertia on the forced axisymmetric response of linearly tapered circular plates

The forced axisymmetric response of linearly tapered circular plates, based on the shear theory is analyzed by the eigenfunction method. Clamped and simply supported plates subjected to constant and half-sine pulse loads, uniformly distributed over a symmetric portion of the plate, are solved as example problems. Numerical results computed for transverse deflection and radial stress of the plate are compared with the corresponding results of classical theory. Results obtained for a plate of constant thickness, as a particular case, are compared with closed form solutions and a very good agreement is found.     

Investigation of thermoluminescence and kinetic parameters of gamma ray exposed LiF: Sm3+, Eu3+ nanophosphors for dosimetric applications

Thermoluminescence (TL) properties of LiF: Sm³⁺ (0.05?mol%) co-doped with Eu³⁺ (0.02, 0.04, 0.06, 0.08?mol%) nanophosphor for the applications of TL dosimetry have been studied. The nanophosphors have been synthesized by chemical co-precipitation method at 8?pH value. The phase purity of the prepared samples has been confirmed by using X-ray diffraction (XRD) data. The XRD peaks broadening revealed the formation of the nanostructure, complemented by the TEM image. For TL studies, the samples have been irradiated with gamma rays using ⁶⁰Co source in the irradiation dose range of 0.1?kGy to 30?kGy. In gamma exposed samples, the TL glow curve consists of single glow peak at 410?K and three shoulder peaks at 475?K, 550?K and 632?K. The dosimetry properties such as the effects of exposure doses, heating rates and fading characteristics have also been studied. The kinetic parameters such as activation energy (E), the frequency factors (s) and order of kinetic (b) of the glow curves have also been calculated by using Chen's peak shape method. The linear behavior of TL intensity with radiation doses and low fading shows that the LiF: Sm³⁺, Eu³⁺ Nanophosphor is a potential candidate for dosimetry applications.     

Transition Metal‐Free Approach to Propynenitriles and 3‐Chloropropenenitriles

A transition metal‐free, facile and efficient one‐pot protocol for the synthesis of propynenitriles from readily available 3‐chloropropenals is disclosed. The reaction conditions have also been optimized for the exclusive formation and isolation of 3‐chloropropenenitriles which are important building blocks in general and are intermediates in the synthesis of propynenitriles. The hallmark of the methodology is the use of non‐toxic reagents, milder, metal‐free and economically benign reaction conditions avoiding a harsh dehydration step while achieving excellent yields.