Vertically Aligned GaAs Nanowires on Graphite and Few-Layer Graphene: Generic Model and Epitaxial Growth

By utilizing the reduced contact area of nanowires, we show that epitaxial growth of a broad range of semiconductors on graphene can in principle be achieved. A generic atomic model is presented which describes the epitaxial growth configurations applicable to all conventional semiconductor materials. The model is experimentally verified by demonstrating the growth of vertically aligned GaAs nanowires on graphite and few-layer graphene by the self-catalyzed vapor-liquid-solid technique using molecular beam epitaxy. A two-temperature growth strategy was used to increase the nanowire density. Due to the self-catalyzed growth technique used, the nanowires were found to have a regular hexagonal cross-sectional shape, and are uniform in length and diameter. Electron microscopy studies reveal an epitaxial relationship of the grown nanowires with the underlying graphitic substrates. Two relative orientations of the nanowire side-facets were observed, which is well explained by the proposed atomic model. A prototype of a single GaAs nanowire photodetector demonstrates a high-quality material. With GaAs being a model system, as well as a very useful material for various optoelectronic applications, we anticipate this particular GaAs nanowire/graphene hybrid to be promising for flexible and low-cost solar cells.     

A Novel Non-Invasive Method for Extraction of Geometrical and Texture Features of Wood

Non invasive feature detection in wood based application requires exact discrimination between geometrical edges and texture. It has been found that traditional edge detection algorithms are highly sensitive to noise and texture and produces inferior results with wood. The present work encompasses a micro level reconstruction of Palash and Rosewood by using micro X-rays CT scanner. It also encompasses a new edge detection algorithm using newly constructed Chebyshev polynomial based fractional order differentiator. Transform based method has been used for reconstruction purpose. Newly designed fractional order filter has been applied on these reconstructed images. Chebyshev polynomial based fractional order differentiator has been used for filtering operation. Quadrature Mirror Filter (QMF) concept has been used for design of high pass filter and low pass filter. Preprocessing has been performed by using this filter. Canny edge detection algorithm has been used on this preprocessed image. The algorithm has been tested on two different test cases of wood images a) Palash and b) Rosewood. The effect of relaxation coefficient has also been presented and discussed.     

Anti-myeloma activity of pamidronate in vivo

Two patients with progressive myeloma were treated with pamidronate disodium every 2-4 weeks. Pamidronate therapy resulted in a significant reduction of marrow plasmacytosis and plasma cell labelling index (PCLI), together with durable (> or = 20 months) stabilization of immunoglobulin (Ig) levels and an increase in bone mineral density in the first patient and > 50%, reduction in Ig levels and bone marrow plasmacytosis in the second. This, to our knowledge, is the first report of an anti-myeloma effect of bisphosphonates in humans and provides evidence that a therapeutic intervention largely directed at the myeloma microenvironment may alter the natural history of the disease.     

Inactivation of rice bran lipase with metal ions

The inactivation of rice bran lipase was studied in vitro and in vivo using metal ions in methanol or HCl. Lipase was extracted from rice bran in 0.1 M potassium phosphate buffer, pH 7.0 and purified by ammonium sulphate fractionation. The 25–55% ammonium sulphate fraction was subjected to DEAE-cellulose ion exchange chromatography and the fraction (F6) eluted at V_e/V_o of 14.37 was purified about 333-fold. In-vitro studies on F6 lipase showed that Fe³⁺ and Ni²⁺ completely inhibited the lipase activity at 5 × 10^?5 M concentration, while Zn²⁺ and Cu²⁺ did so at 2.5 × 10^?4 M. The results on in-vivo inactivation of rice bran lipase showed that Fe³⁺ and Ni²⁺ at 200 μg g^?1 significantly checked the release of free fatty acids (FFA) from rice bran for 6 days of storage when compared with using concentrated HCl (2%, v/w) only. The triglyceride content of oil was also maximum with Fe³⁺ and Ni²⁺ treatment at 200 μg g^?1. The present results suggest that Fe³⁺ and Ni²⁺ could be effectively used to arrest the release of FFA in rice bran and thus contribute to improving the edible quality of rice bran oil.     

Separation of palladium from high level liquid waste of PUREX origin by solvent extraction and precipitation methods using oximes

Separation of palladium from high level liquid waste (HLLW) solution originated from the reprocessing of spent fuel by PUREX process is carried out by solvent extraction and precipitation methods using oximes. In solvent extraction, palladium is extracted from the waste using 1.1×10⁻²M α-benzoin oxime in Solvesso 100 as extractant. The loaded organic phase is scrubbed with water prior to the stripping of palladium using the strippants 0.05 M thiourea in 0.1 M HNO₃ and 4 M NH₄OH separately. The recovery of the method is found to be >99.5%. The method has been used to recover Pd in sub mg quantities from actual waste solution originated from the reprocessing of spent fuel from pressurised heavy water reactor (PHWR-HLLW). Studies are also carried out for the separation of palladium using an aqueous solution of sodium salt of dimethyl glyoxime (0.1% w/v) as precipitant. Various parameters which influence the precipitation of palladium such as concentration of the precipitant, concentration of nitric acid in the feed and the behaviour of uranium, plutonium and other fission products at the concentration level encountered in the waste are studied in detail. Under the optimized precipitation conditions separation of Pd is carried out from a synthetic PHWR-HLLW and the recovery is found to be >99.9%. The palladium product obtained from both the methods show high decontamination factors with respect to other fission products and constituents of the waste. Based on these results a scheme has been proposed for the recovery of palladium from HLLW.