Effect of stable strontium on the tissue alkaline and acid phosphatase activities of rat: feeding studies

The effect of feeding stable strontium (Sr) on the tissue alkaline and acid phosphatase activities was studied in young rats. These activities were reduced in liver and small intestine by 10% to 15% at 2 weeks, 20% to 30% at 4 weeks and in kidney by 20% at 6 weeks only in rats fed 2% Sr diet; bone alkaliine phosphatase activity was, however, increased by 80% to 100% (2-6 weeks) in these rats. Gross lesions like paralysis, hemorrhage, rickets and high mortality were observed after 4 to 6 weeks. Although no such lesions were seen, appreciable changes in enzyme activities as mentioned above were discernible in rats fed 1% Sr diet for 6 weeks. Feeding of a 0.5% Sr diet for a period up to 6 weeks had no deleterious effect. Recovery following consumption of a normal diet for 2 weeks was almost complete in liver and small intestine but not in kidney. The elevated tissue Sr levels do not explain the pronounced losses seen in this investigation as compared to those in the earlier in vitro experiments. This study depicts the possible damage due to prolonged therapeutic use of large amounts of stable Sr for the removal of radiostrontium.     

Empirical pseudo-potential studies on electronic structure of semiconducting quantum dots

Theoretical investigations of electronic structure of quantum dots is of current interest in nanophase materials. Empirical theories such as effective mass approximation, tight binding methods and empirical pseudo-potential method are capable of explaining the experimentally observed optical properties. We employ the empirical pseudo-potential to calculate the gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) as a function of shape and size of the quantum dots. Our studies explain the building up of the bulk band structure when the size of the dot is much larger than the bulk Bohr exciton radius. We present our investigations of HOMO-LUMO gap variation with size, for CdSe, ZnSe and GaAs quantum dots. The calculated excitonic energies are sensitive to the shape and size of quantum dots and are in good agreement with experimental HOMO-LUMO gaps for CdSe quantum dots. The agreement improves as experimentally observed lattice contraction is incorporated in pseudo-potential calculations for ZnSe quantum dots. Electronic structure evolution, as the size of quantum dot increases, is presented for CdSe, ZnSe and GaAs quantum dots.     

Trust Based Detection and Elimination of Packet Drop Attack in the Mobile Ad-Hoc Networks

The mobile ad hoc network (MANET) is communication network of a mobile node without any prior infrastructure of communication. The network does not have any static support; it dynamically creates the network as per requirement by using available mobile nodes. This network has a challenging security problem. The security issue mainly contains a denial of service attacks like packet drop attack, black-hole attack, gray-hole attack, etc. The mobile ad-hoc network is an open environment so the working is based on mutual trust between mobile nodes. The MANETs are vulnerable to packet drop attack in which packets travel through the different node. The network while communicating, the node drops the packet, but it is not attracting the neighboring nodes to drop the packets. This proposed algorithm works with existing routing protocol. The concept of trusted list is used for secure communication path. The trusted list along with trust values show how many times node was participated in the communication. It differentiates between altruism and selfishness in MANET with the help of energy level of mobile components. The trust and energy models are used for security and for the differentiation between altruism and selfishness respectively.     

Fatty Acid Composition of California Grown Almonds

ABSTRACT: Eight almond (Prunus dulcis L.) cultivars from 12 different California counties, collected during crop years 2004 to 2005 and 2005 to 2006, were extracted with petroleum ether. The extracts were subjected to GC‐MS analyses to determine fatty acid composition of soluble lipids. Results indicated palmitic (C16:0), oleic (C18:1), linoleic (C18:2), and α‐linolenic (C18:3) acid, respectively, accounted for 5.07% to 6.78%, 57.54% to 73.94%, 19.32% to 35.18%, and 0.04% to 0.10%; of the total lipids. Oleic and linoleic acid were inversely correlated (r=–0.99, P= 0.05) and together accounted for 91.16% to 94.29% of the total soluble lipids. Statistically, fatty acid composition was significantly affected by cultivar and county.     

The Collagen Suprafamily: From Biosynthesis to Advanced Biomaterial Development

Collagen is the oldest and most abundant extracellular matrix protein that has found many applications in food, cosmetic, pharmaceutical, and biomedical industries. First, an overview of the family of collagens and their respective structures, conformation, and biosynthesis is provided. The advances and shortfalls of various collagen preparations (e.g., mammalian/marine extracted collagen, cell‐produced collagens, recombinant collagens, and collagen‐like peptides) and crosslinking technologies (e.g., chemical, physical, and biological) are then critically discussed. Subsequently, an array of structural, thermal, mechanical, biochemical, and biological assays is examined, which are developed to analyze and characterize collagenous structures. Lastly, a comprehensive review is provided on how advances in engineering, chemistry, and biology have enabled the development of bioactive, 3D structures (e.g., tissue grafts, biomaterials, cell‐assembled tissue equivalents) that closely imitate native supramolecular assemblies and have the capacity to deliver in a localized and sustained manner viable cell populations and/or bioactive/therapeutic molecules. Clearly, collagens have a long history in both evolution and biotechnology and continue to offer both challenges and exciting opportunities in regenerative medicine as nature's biomaterial of choice.     

Crystallographic studies of some mixed thiogallate semiconductors

A crystallographic study has been made of solid solutions of the tetragonal defect chalcopyrites (14), CdGa₂S₄ and CdGa₂Se₄. The compositions may be represented by CdGa₂S₄(1–x)Se_4x wherex = 0.0, 0.25, 0.50, 0.75 and 1.0. A complete solid solubility was observed between these two compounds. Thea-axis values varied linearly with composition, whilstc-axis values initially showed a slower rise forx<0.5 and then a marked rapid rise with increasing selenium content. Single crystals were grown of these compositions by the chemical transport method. Optimum conditions required for the growth of the crystals have been established. The crystals of CdGa₂S₄ and CdGa₂S₃Se had the biggest face parallel to (001) plane whereas crystals of compounds CdGa₂S₂Se₂, CdGa₂SSe₃ and CdGa₂Se₄ were triangular prisms with a face parallel to (112) plane and 110 as the growth axis. The parametersx, y andz for selenium position in CdGa₂Se₄ were obtained by comparing the calculated values ofF ² factors with those obtained from observed intensities. The best match was found forx=y=0.25 andz=0.15.     

Generic personality and emotion simulation for conversational agents

This paper describes a generic model for personality, mood and emotion simulation for conversational virtual humans. We present a generic model for updating the parameters related to emotional behaviour, as well as a linear implementation of the generic update mechanisms. We explore how existing theories for appraisal can be integrated into the framework. Then we describe a prototype system that uses the described models in combination with a dialogue system and a talking head with synchronized speech and facial expressions. Copyright © 2004 John Wiley & Sons, Ltd.     

Characterization of near-surface electrical properties of multi-crystalline silicon wafers

This experiment is concerned with photoconductive decay (PCD) measurements devised specifically for the purpose of characterization of the near-surface region of semiconductor substrates. Specifically, the method is utilized to evaluate the effects of crystallographic orientation, grain boundaries, and surface texturing on the near-surface electrical properties of multi-crystalline silicon (mc-Si) wafers used for solar cell applications. The PCD method is also explored for the purposes of monitoring processes used in the manufacture of mc-Si solar cells. The effect of saw damage and damage removal by wet etching on the near-surface lifetime of minority carriers and carrier mobility in mc-Si wafers is quantitatively determined. The results obtained demonstrate a direct correlation between condition of the mc-Si surface and the electrical parameters measured. It is postulated that the PCD method using temporary contact can be effectively used to monitor the condition of mc-Si surfaces during solar cell manufacturing.