Studies on nucleation kinetics of InxGa1−xN/GaN heterostructures

Nucleation kinetics during the growth of In_xGa_1−xN on a GaN substrate have been studied. The behavior of nonequilibrium between the In_xGa_1−xN and the GaN substrate has been analyzed, and hence, the expression derived for the stress-induced supercooling/superheating has been numerically evaluated. The maximum amount of stress-induced supercooling is found to be 1.017 K at x=0.12. These values are incorporated in the classical heterogeneous nucleation theory. Using the regular solution model, the interfacial tension between the nucleus and substrate and, hence, the interfacial tension between nucleus and mother phase and thermodynamical potential of the compounds have been calculated. The amount of driving force available for the nucleation has been determined for different compositions and degrees of supercooling. It has been shown that the value of the interaction parameter of InN-GaN plays a dominant role in nucleation and growth kinetics of In_xGa_1−xN on a GaN substrate. These values have been used to evaluate the nucleation parameters. It is shown that the nucleation barrier for the formation of a In_xGa_1−xN nucleus on a GaN substrate is minimum in the range of x=0.12 to x=0.17, and it has been qualitatively proved that good quality In_xGa_1−xN on GaN can be grown only in the range 0<x≤0.2.     

Valency of copper in 123 oxides

The valency of copper in freshly prepared as well asin situ high-temperature oxygen-treated 123 oxides was analysed by X-ray photoelectron spectroscopy. The results suggest the presence of Cu²⁺ and Cu³⁺ along with Cu⁺. This observation is supported by cyclic voltammograms of 123 oxides recorded in a formamide medium. The valence band of 1 23 oxides was probed using X-ray (MgK ) and ultraviolet (He-I) sources. It was observed that the Cu-O hybridized orbital in YBa₂Cu₃O_7–x responsible for conduction decreases with time in an ultrahigh vacuum and increases with oxygen treatment temperature.     

Beyond Single-Page Web Search Results

Given a user keyword query, current Web search engines return a list of individual Web pages ranked by their "goodness" with respect to the query. Thus, the basic unit for search and retrieval is an individual page, even though information on a topic is often spread across multiple pages. This degrades the quality of search results, especially for long or uncorrelated (multitopic) queries (in which individual keywords rarely occur together in the same document), where a single page is unlikely to satisfy the user's information need. We propose a technique that, given a keyword query, on the fly generates new pages, called composed pages, which contain all query keywords. The composed pages are generated by extracting and stitching together relevant pieces from hyperlinked Web pages and retaining links to the original Web pages. To rank the composed pages, we consider both the hyperlink structure of the original pages and the associations between the keywords within each page. Furthermore, we present and experimentally evaluate heuristic algorithms to efficiently generate the top composed pages. The quality of our method is compared to current approaches by using user surveys. Finally, we also show how our techniques can be used to perform query-specific summarization of Web pages.     

Analyzing the efficacy of using digital ink devices in a learning environment

There has been increased interest on the impact of mobile devices such as PDAs and Tablet PCs in introducing new pedagogical approaches and active learning experiences. We propose an intelligent system that efficiently addresses the inherent subjectivity in student perception of note taking and information retrieval. We employ the idea of cross indexing the digital ink notes with matching electronic documents in the repository. Latent Semantic Indexing is used to perform document and page level indexing. Thus for each retrieved document, the user can go over to the relevant pages that match the query. Techniques to handle problems such as polysemy (multiple meanings of a word) in large databases, document folding and no match for query are discussed. We tested our system for its performance, usability and effectiveness in the learning process. The results from the exploratory studies reveal that the proposed system provides a highly enhanced student learning experience, thereby facilitating high test scores.

Polyhydroxy propionate-co-hydroxy dodecanoate-co-hydroxy octadecanoate for in vitro cell culture

This study is novel to report the utilization of molasses for the production of polyhydroxy propionate-co-hydroxy dodecanoate-co-hydroxy octadecanoate from Pseudomonas sp. LDC-5 as prospective biomaterial. Thermal analysis revealed its potential for thermal permanence and melt processing. 3T3 fibroblasts were cultured on these different scaffolds and their proliferation was compared. Giemsa and acridine orange/ethidium bromide staining revealed that there was no distinct change in morphology. Polyhydroxyalkanoate:poly ethylene glycol blend was found to be the most promising for extracellular matrix secretion, a key thrust function of 3D culture. Lactate dehydrogenase assay indicated the membrane integrity. DNA fragmentation analysis showed that the scaffold did not damage DNA. Thus the prepared scaffold can serve as a promising biomaterial.     

Nitrites Derived From Foneiculum Vulgare (Fennel) Seeds Promotes Vascular Functions

Abstract: Recent evidence has demonstrated that nitrites play an important role in the cardiovascular system. Fennel (Foneiculum vulgare) seeds are often used as mouth fresheners after a meal in both the Indian sub‐continent and around the world. The present study aims to quantify the nitrite and nitrates in fennel seeds as well as elucidating the effect of fennel derived‐nitrites on vascular functions. Results from our study show that fennel seeds contain significantly higher amount of nitrites when compared to other commonly used post‐meal seeds. Furthermore our study confirmed the functional effects of fennel derived‐nitrites using in vitro and ex vivo models that describe the promotion of angiogenesis, cell migration, and vasorelaxation. We also showed that chewing fennel seeds enhanced nitrite content of saliva. Thus our study indicates the potential role of fennel derived‐nitrites on the vascular system. Practical Application: This study is focused on determining the effect of fennel‐derived nitrites on angiogenesis (the formation of new blood vessels from pre‐existing ones), cell migration, and vasorelaxation (dilation of blood vessels) thereby preserving cardiovascular health.     

Synthesis and characterisation of CuS nanomaterials using hydrothermal route

Copper sulphide (CuS) nanomaterials with interesting morphology were synthesised using copper nitrate trihydrate, thiourea and water as a solvent by a simple hydrothermal route. A systematic investigation was carried out to investigate the effect of reaction time (5, 16 and 24?h) at 150°C on the morphology of the materials. Without the use of any template or additives, shape controlled synthesis of CuS nanocrystallites were achieved. The possible mechanism for the formation of the various nanostructures of CuS in this system is discussed. The prepared materials were characterised by X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and DRS-UV–Vis absorption analysis. The UV–Vis spectrum shows that it is the promising material which can absorb in the visible region and hence could be used for photocatalytic applications. In addition, the electrochemical characteristic of the synthesised material was investigated by cyclic voltammetric analysis, which shows that CuS could be used for electrocatalytic applications.     

Effects of Drying Temperature and Particle Size on Hydration Properties of Dietary Fiber Powder from Lime and Cabbage By-Products

The use of by-products from fruit and vegetable processing plants as sources of dietary fiber and bioactive agents is currently of interest, both from the waste management and from the production of value-added products points of view. This work aimed at studying the use of lime residues and outer leaves of white cabbage to produce dietary fiber powder, which included the study of the product pretreatment and preparation, drying, and grinding dried residues into powder. Dietary fiber content during each processing step was determined to calculate the loss of functionality of the products through the process. Hydration properties, i.e., water holding capacity (WHC) and swelling capacity (SWC), of the two residues were also determined after hot air drying at 60–80°C. The effect of particle size of dietary fiber powder, which was obtained by grinding dried residues, in the range of 63–450 μm, on the hydration properties was also evaluated and discussed.