Structural,optical and electrical properties of ZnTe<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> thin films

ZnTe_1−x Se _x films were deposited on glass substrates kept at 200 °C by the electron beam evaporation technique. These films exhibited cubic structure and the lattice parameter increased with increase of Tellurium concentration in the films which confirmed the solid solution formation. The grain size is found to increase with Te content. The dislocation density and lattice strain show a decreasing trend with increasing of Te content. Band gap values of 2.73 eV, 2.63 eV, 2.52 eV and 2.41 eV have been calculated for the films of composition ‘x’ = 0.2, 0.4, 0.6 and 0.8, respectively, which confirmed the formation of solid solution between ZnSe and ZnTe. Refractive index of the films increased from 2.535 to 2.826 as the concentration of Te increased. All the films showed high resistivity values. Laser Raman spectral studies of ZnTe_1−x Se _x revealed LO phonon frequencies whose values are located in between the LO phonon frequencies of ZnSe and ZnTe.     

Functions of Hydrotropes in Solutions

Hydrotropes affect a several‐fold increase of the solubility of sparingly soluble solutes under normal conditions. Their water‐solubility can significantly enhance the solubility of organic solutes such as esters, alcohols, aldehydes, ketones, hydrocarbons, and fats. While the study of hydrotropes is pioneered by a biochemist, greater appreciation of their role and applicability has happened rather in chemistry and chemical engineering than in biology. Hydrotropes are widely used in drug solubilization, as extraction agents for fragrances, as agents to increase the rate of heterogeneous reactions, and for separation of close‐boiling liquid mixtures through extractive distillation and liquid‐liquid extraction. Applications of hydrotropy and its mechanism are discussed and the scope for future work is presented in this review.     

Breathing‐in/breathing‐out approach to preparing nanosilver‐loaded hydrogels: Highly efficient antibacterial nanocomposites

The key objective of developing novel materials for hygienic living conditions is to lower the risk of transmitting diseases and biofouling. To this end, a number of silver–hydrogel nanocomposite systems are under development. In this study, we attempted a unique strategy to prepare silver‐nanoparticle‐loaded poly(acrylamide‐co‐N‐vinyl‐2‐pyrolidone) hydrogel composites. To load nanosilver particles into such a nonionic hydrogel, a novel breathing‐in/breathing‐out (BI–BO) approach was employed. As the number of BI–BO cycles increased, the amount of the silver nanoparticles loaded into these hydrogels also increased. This behavior was obvious and was confirmed by ultraviolet–visible spectroscopy and thermal analysis. Furthermore, the hydrogel–silver‐nanoparticle composites were confirmed with Fourier transform infrared spectroscopy and transmission electron microscopy studies. Antibacterial studies of these hydrogel–silver nanocomposites showed excellent results against Escherichia coli. The antibacterial activity increased with the number of BI–BO cycles, and samples that underwent three BI–BO cycles showed optimal bactericidal activity. The degree of crosslinking and the silver content had a great influence on the antibacterial efficacy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Flash evaporated cadmium sulfide films

Cadmium sulfide (CdS) thin films were deposited by the flash evaporation technique onto glass substrates kept at temperatures in the range 30–300 °C. The source material was CdS powder synthesized in the laboratory. The films exhibited hexagonal structure with dislocation density and the stress decreased as the substrate temperature increased. An optical band gap of 2.39 eV was obtained for the films deposited at 300 °C. Raman spectra exhibited peaks corresponding to Longitudinal Optical phonons of CdS with the full width at half maximum decreasing with increase of substrate temperature. Room temperature resistivity values are lower than earlier reports on chemically deposited CdS films.     

A New Biodegradable Flexible Composite Sheet from Poly(lactic acid)/Poly(ε‐caprolactone) Blends and Micro‐Talc

The influence of talc loading on phase morphology of PLA/PCL/talc composites and improvement in resulting properties are reported. Talc‐based composites of PLA/PCL blends were prepared by melt blending. SEM analysis demonstrates that PLA appears as discrete domain phase, while PCL acts as a bulk phase in the blend. Talc addition decreases PLA domain sizes and voids in the matrix. This results in significant improvement of oxygen and water vapor barrier properties of composite by 33 and 25%, respectively, at 3 wt.‐% talc loading. DSC shows that talc acted as nucleating agent for PCL phase in the composite and improves its crystallinity. Various theoretical models based on dispersion and filler geometry are used to predict the tensile modulus and oxygen permeability.

     

Hydrogel–silver nanoparticle composites: A new generation of antimicrobials

Design of consistant and eco‐friendly methods for the synthesis of silver nanoparticles (AgNPs) is a significant forward direction in the field of application of antibacterial bionanotechnology. One among the available options is hydrogel templates, which are highly useful to achieve this goal. This investigation involves the development of poly(acrylamide)/poly(vinyl alcohol) hydrogel–silver nanocomposites (HSNCs) to achieve AgNPs of ～2–3 nm size in gel networks. The nanocomposite synthesis process is quite convenient, direct, and very fast, and the obtained hydrogel AgNP composites can be used for antibacterial and wound dressing applications. All the nanocomposite aqueous solutions have shown absorption peaks at 420 nm in UV–visible absorption spectrum corresponding to the Plasmon absorbance of AgNPs. X‐ray diffraction spectrum of the HSNC exhibited 2θ values matching with silver nanocrystals. Transmission electron microscopy images of nanocomposites represent discrete AgNPs throughout the gel networks in the range of 2–3 nm. The developed nanocomposites were evaluated for antibacterial application on E. coli. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Prototype development and field-test results of an adaptive multiresolution PANOPTES imaging architecture

The design, development, and field-test results of a visible-band, folded, multiresolution, adaptive computational imaging system based on the Processing Arrays of Nyquist-limited Observations to Produce a Thin Electro-optic Sensor (PANOPTES) concept is presented. The architectural layout that enables this imager to be adaptive is described, and the control system that ensures reliable field-of-view steering for precision and accuracy in subpixel target registration is explained. A digital superresolution algorithm introduced to obtain high-resolution imagery from field tests conducted in both nighttime and daytime imaging conditions is discussed. The digital superresolution capability of this adaptive PANOPTES architecture is demonstrated via results in which resolution enhancement by a factor of 4 over the detector Nyquist limit is achieved.     

Development of fish gelatin edible films using extrusion and compression molding

Fish gelatin was plasticized with 20% and 25% glycerol (w/w of gelatin) and used to develop edible films by twin-screw extrusion at 110 and 120 °C followed by compression molding at 80 °C. Tensile and moisture barrier properties and glass transition temperature were then measured and compared with solution-cast films. The films extruded at 110 °C and with 25% glycerol had the highest percent elongation at break of 293 ± 27%. The water vapor permeability values of extruded films (the highest value being 2.9 ± 0.2 g mm h⁻¹ cm⁻² Pa⁻¹) were higher than those of solution-cast films while the glass transition temperatures (T_g) of the extruded films were generally lower than those of solution-cast films. Films with 25% glycerol that were extruded at 110 °C had the lowest T_g (2.10 ± 0.31 °C). This investigation showed that extrusion processing followed by compression molding is a feasible method to produce fish gelatin films for commercial applications in a wide range of food products.