Studies of InGaN∕GaN multiquantum-well green-light-emitting diodes grown by metalorganic chemical vapor deposition

InGaN(3nm)∕GaN(5nm) three period multiquantum green-light-emitting diodes(LEDs) grown by the metalorganic chemical vapor deposition technique have been studied using high-resolution transmission electron microscopy (HRTEM), double crystal high resolution x-ray diffraction (HRXRD) and low temperature photoluminescence. HRTEM analysis showed that the defect density gradually decreased in the growth direction with increasing thickness. Self-assembled quantum dot-likestructures in the wells and black lumps between the well and barrier due to In segregation and strain contrast were observed, respectively. The HRXRD spectrum of the green LEDstructure was simulated using the kinematical theory method to obtain the composition and thickness of the well and barrier. The quantum-well (QW) green emission peak 2.557eV at 10K showed “S” shaped shift like a red–blue–red shift with variation of the temperature in the photoluminescence spectra due to potential fluctuations caused by inhomogeneous alloy distribution in the wells. The activation energy of 49meVobtained from the QW green emission line indicated deepening of the localization of the carriers

Ni 30 Ti 50 Pt 20 High Temperature Shape Memory Alloy (HTSMA) Wires: Processing Related Issues

Abstract There is a growing demand for high temperature shape memory alloys (HTSMAs) for applications in areas such as aeroengines, chemical industries, and nuclear power plants, where the ambient temperature is relatively high (150-350°C). Platinum addition to binary NiTi, with Pt substituting for Ni, has been found to raise the transformation temperatures of the alloy with the advantage of retaining the transformation hysteresis in the range 25-35°C. In the present study, a NiTiPt alloy was selected for processing into the wire form for applications in the range 200-250°C. Addition of Pt of about 20 at.% to binary NiTi was required to raise the transformation temperatures of the alloy above 200°C. It was found that Pt addition significantly changed the processing characteristics of the NiTiPt alloy from those of binary NiTi alloys. For successful processing of the NiTiPt wires, it was necessary to modify the process usually followed for binary NiTi alloys. Also, additional steps were incorporated to overcome the problems inherent to this alloy system. Some of these aspects related to processing of this alloy in wire form are discussed in this paper

Studies on sandal spike. Part VI. A study of the amino-acid make-up and some organic acids of sandal (Santalum album L.) in health and disease

The following amino-acids have been detected in the healthy and the diseased tissues of sandal (green foliage): alanine, arginine, aspartic acid, cysteine, glutamic acid, histidine leucine, isoleucine, lysine, methionine, ornithine, phenylalanine, proline, hydroxy proline, serine, threonine, valine and α-aminobutyric acid. Quantitative estimations have been made of alanine, aspartic acid and glutamic acid as also those of the corresponding ketocarboxylic acids, namely, pyruvic, oxalacetic and α-ketoglutaric acids which are involved in the aminoacid and carbohydrate metabolisms, respectively. Distinct differences have been noticed in regard to the quantities of these acids present in the healthy and diseased tissues and their significance has been discussed

Phylogenetic relations in section Arachis based on seed protein profile

Seed protein profiles of nine diploid species (2n = 20), ten tetraploid accessions, two synthetic amphidiploids and two autotetraploids (2n = 40) were studied using SDS-polyacrylamide gel electrophoresis. While the general profiles suggested considerable homology among these taxa in spite of speciation and ploidy differences, appreciable genetic differences were present to support the existing genomic divisions and sub-divisions in the section Arachis. A high degree of relationship was indicated between the two diploid species (A. duranensis containing the A genome and A. batizocoi (ICG 8210) containing the B genome) and tetraploids A. monticola/A. hypogaea (2n = 40) containing AABB genome. Similar relationships were recorded between the AABB synthetic amphidiploid and the profile obtained from the mixture of protein of A. duranensis and A. batizocoi, suggesting that these two diploid species were the donors of the A and B genome, respectively, to tetraploid A. monticola/A. hypogaea

Effect of C∕Si ratio on deep levels in epitaxial 4H–SiC

Changing the ratio of carbon to silicon during the epitaxial 4H–SiC growth is expected to alter the dominant deep level trap, which has been attributed to a native defect. The C∕Si ratio was changed from one to six during epitaxialgrowth of SiC. Diodes fabricated on the epitaxial layer were then characterized using current-voltage and deep level transient spectroscopy. The single peak at 340K (Z1/Z2 peak), was deconvolved into two traps, closely spaced in energy. The concentration of one of the Z1/Z2 traps decreased with increasing C∕Si ratio. This result opposes theoretical predictions of carboninterstitial components, and supports assignment to a silicon antisite or carbonvacancy relationship. The concentration of the second component of the peak at 340K did not depend on the C∕Si ratio, which would indicate an impurity in an interstitial site

The Economic Benefits Resulting from the First 8 Years of the Global Programme to Eliminate Lymphatic Filariasis (2000–2007)

Lymphatic filariasis (LF), commonly known as ‘elephantiasis’, is one of the world's most debilitating infectious diseases. In 83 countries worldwide, more than 1.3 billion people are at risk of infection with an estimated 120 million individuals already infected. A recent publication reviewing the health impact of the first 8 years of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) demonstrated the enormous health benefits achieved in populations receiving annual mass drug administration (MDA), as a result of infection prevented, disease progression halted, and ancillary treatment of co-infections. To date, however, no studies have estimated the economic value of these health benefits, either to the individuals or the societies afflicted with LF. Our study estimates that US$21.8 billion will be gained among individuals benefitting from just the first 8 years of the Global Programme, and an additional US$2.2 billion will be saved by the health systems of endemic countries. Treating endemic populations is possible at very low cost – particularly because of the generous drug donations from two pharmaceutical companies – but results in enormous economic benefits. Findings from this study yield a much clearer understanding the GPELF's full economic impact and strengthen the conviction that it is a ‘best buy’ in global health

Sources and Mechanisms of Resistance to Sorghum Head Bug, Eurystylus-Immaculatus Odh in West-Africa

Sorghum is one of the most important cereal crops in West Africa, and the head bug, Eurystylus immaculatus Odh. (Hemiptera: Miridae) is the key pest of grain sorghum in this region. A range of sorghum genotypes were evaluated for resistance to sorghum head bug at Sotuba (Mali) and Kamboinse (Burkina Faso). Genotypes CSM 388, IS 14332, Malisor 84-7, Sakoika. S 29 and Kamboinse local were resistant to head bugs. both under natural and headcage screening. Head bug resistant genotypes had a lower percentage of head bug damaged grain. The food quality of head bug damaged grain was very poor and unacceptable. Cultivar non-preference was identified as a component of resistance to head bugs. and CSM 388 was nonpreferred compared to E 35-1. Panicle compactness was positively associated with head bug numbers and grain damage. However, genotypes with loose panicles were also susceptible to bugs. Long glumes (>5 mm), days to glume opening (>20 days after anthesis), >50% covering of the grain by the glumes, and grain hardness contribute towards resistance to Eurystylus immaculatus. This information will be useful for developing a programme to breed for resistance to this insect in West Africa