Preparation of highly ordered growth of single-crystalline Gd2O2S:Eu nanostructures

A simple and facile template-assisted hydrothermal route has been demonstrated for the shape-selective preparation of highly ordered single-crystalline Gd₂O₂S:Eu³⁺ nanostructures, such as nanotubes, nanorods and nanoflowers. These fabricated nanostructures possess desirable atomic structures, surfaces, morphologies and properties to meet the growing demands and specific requirements of new technologies. The concentration of precursor chemicals, the temperature, the reaction time, and the use of a capping agent are key factors in the morphological control of Gd₂O₂S:Eu³⁺ nanostructures. The morphology and the phase composition of the prepared nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy disperse spectroscopy (EDS) and photoluminescence (PL). We believe this technique will be readily adopted in realizing other forms of various nanostructured materials.     

Faster response of NO₂ sensing in graphene-WO₃ nanocomposites

Graphene-based nanocomposites have proven to be very promising materials for gas sensing applications. In this paper, we present a general approach for the preparation of graphene-WO(3) nanocomposites. Graphene-WO(3) nanocomposite thin-layer sensors were prepared by drop coating the dispersed solution onto the alumina substrate. These nanocomposites were used for the detection of NO(2) for the first time. TEM micrographs revealed that WO(3) nanoparticles were well distributed on graphene nanosheets. Three different compositions (0.2, 0.5 and 0.1 wt%) of graphene with WO(3) were used for the gas sensing measurements. It was observed that the sensor response to NO(2) increased nearly three times in the case of graphene-WO(3) nanocomposite layer as compared to a pure WO(3) layer at room temperature. The best response of the graphene-WO(3) nanocomposite was obtained at 250?°C.     

Physical and electrical properties of combustion synthesized NASICON type Na3Cr2(PO4)3 crystallites: Effect of glycine molar ratios

Thermally stable Na₃Cr₂(PO₄)₃ nano-crystallites are synthesized through novel solution combustion technique using glycine fuel in three molar ratios. Effects of fuel molar ratio on structural and electrical properties are investigated. Reaction parameters like fuel molar ratio, flame temperature and number of moles of gases evolved, play a major role in deciding physical and electrical properties. Out of the synthesized samples, one which contains fuel in 1:1 molar ratio shows highest grain conductivity of 2.35 × 10⁻⁶ S cm⁻¹. Improved conductivity is elucidated by least size and highest density of the crystallites, which in turn is decided by the flame temperature. Ac electrical properties are investigated using complex impedance spectroscopy. Activation energies for dc conduction and relaxation are determined and the results are reported.     

Green synthesis of silver nanoparticles using Nervalia zeylanica leaf extract and evaluation of their antioxidant,catalytic, and antimicrobial potentials

ABSTRACT

Here we report a simple, one-pot, inexpensive, and eco-friendly method for the synthesis of silver nanoparticles. The leaf extract of a medicinal plant Nervalia zeylanica was used as reducing and stabilizing agent for the synthesis of nanoparticles by microwave-assisted strategy. The nanoparticles show characteristic surface plasmon peak at 468?nm in UV–vis absorption spectrum. The involvement of phytochemicals in the reduction and stabilization of nanoparticles was confirmed by FTIR analysis. Using X-ray diffraction analysis, the crystalline nature of the nanoparticles was demonstrated. Transmission electron microscopic analysis shows that the nanoparticles were in spherical shape with average particle size of 34.2?nm. The antioxidant studies were performed by the 1,1-diphenyl-2-picryl hydrazyl method. The nanoparticles show excellent scavenging activities than the leaf extract. The IC₅₀ values of silver nanoparticles and the leaf extract, respectively, were 15.20 and 92.83?µg?mL^?1. The catalytic activities of synthesized nanoparticles were examined by using them in the reduction of organic dyes. The nanoparticles show excellent catalytic activities and follow pseudo-first-order kinetics. The antimicrobial activities of nanoparticles were analyzed by an agar well diffusion method against six microbial strains and found that the nanoparticles were highly toxic against all the tested microbial strains.     

Partitioning and gating technique for low-power multiplication in video processing applications

In this paper, we propose a partitioning and gating technique for the design of a high performance and low-power multiplier for kernel-based operations such as 2D convolution in video processing applications. The proposed technique reduces dynamic power consumption by analyzing the bit patterns in the input data to reduce switching activities. Special values of the pixels in the video streams such as zero, repeated values or repeated bit combinations are detected and data paths in the architecture design are disabled appropriately to eliminate unnecessary switching. Input pixels in the video stream are partitioned into halves to increase the possibility of detecting special values. It is observed that the proposed scheme helps to reduce dynamic power consumption in the 2D convolution operations up to 33%.     

Preparation and characterization of CdS nanocrystallites in nafion

Perfluoroethylene sulfonic acid polymer (NAFION) films are subjected to ion exchange in the medium of aqueous solutions of cadmium acetate, followed by ammonia passivation. The films are then treated with hydrogen sulfide gas for prescribed times. X-ray powder diffraction data of these samples have been analyzed for estimating the sizes of the nanocrystallites. The optical absorption spectra of the samples show an absorption edge beginning at 525 nm for the largest size clusters. A broad absorption band appears with a maximum around 410 nm–440 nm in the smaller size clusters.     

A knowledge-based system for improving the consistency between object models and use case narratives

In today’s systems development environments, object models are playing an increasingly important role in contributing to the agility and flexibility expected of the information systems being built. While current computer-aided software engineering tools can aid in creating object models, they do not provide much support in ensuring that the object models created are consistent with the specifications in use case narratives. This paper presents a methodology and a knowledge-based system to facilitate the verification of consistency of a given object model against a set of use case narratives. The methodology is implemented as a prototype knowledge-based extension to an open source CASE tool. The prototype’s ability to reliably extract relevant information from use case narratives and its role in verifying the consistency of object models have been evaluated using a laboratory experiment. By analyzing use case narratives utilizing natural language processing techniques and applying collaboration patterns and heuristics, this methodology can determine missing and invalid model elements to guide the analyst in creating object models that are consistent with the requirements specified in a set of use case narratives. The results from this design science research indicate that the prototype system can be a useful tool to assist in this process.     

A Universal Foreground Segmentation Technique using Deep-Neural Network

Multimedia Tools and Applications - Background subtraction is generally used for foreground segmentation (moving object detection) from video sequences. Several background subtraction methods have...     

Effect of thermal spikes on the structural characteristics of Kevlar fibres

The effect of upto six cumulative exposures to thermal spikes, each of 10 s duration, on Kevlar 49 fibres has been analysed. X-ray data show that exposures to spikes corresponding to T's 400°C cause changes at the level of the crystal lattice. At and above 500°C, severe surface damages such as introduction of longitudinal openings, peel-offs and extraneous material are found to occur. The tensile properties of the spike-exposed fibres manifest changes which conform well with the structural changes. As in the case of prolonged thermal exposures, the spike induced effects are also controlled by two parameters, viz., the temperature and the duration of the cumulative exposure. The data from spike exposed fibres indicate that the thermally induced changes in the structural and tensile characteristics get initiated at the very early stages of thermal exposure viz., of the order of 10 s.     

Some filing schemes based on finite groups of automorphisms

From some families of partialt-designs which have automorphism groups of high transitivity new algebro-algorithmical filing systems permittingt-queries are constructed. Due to the computational properties of the groups used, new bounds for the retrieval times are obtained in several cases.