Cd(Zn,S)Se quaternary thin films for electrochemical photovoltaic cell application

In this study, Cd_1−xZn_xS_ySe_1−y (0 ≤ x = y ≤ 0.35) photoelectrodes are deposited via inexpensive facile chemical bath deposition. The effects of Zn and S doping on the compositional, microstructural, electrical, and optical properties of thin films were analysed. The electrochemical photovoltaic (EPV) cell of configuration Cd_1−xZn_xS_ySe_1−y/0.25M sulfide/polysulfide/C was assembled to examine the different performance parameters in light and in dark conditions. An EPV cell fabricated with the Cd_1−xZn_xS_ySe_1−y (0 ≤ x = y ≤ 0.075) photoelectrode exhibited a maximum photoconversion efficiency of 3.18%. This performance can be attributed primarily to the enhanced light-absorption ability of the material because of the enhanced rough microstructure and low recombination of photo-injected electrons with the electrolyte. The photovoltaic (PV) performance is significantly enhanced after doping CdSe with Zn and S.     

Development of nanocolloidal gold based immunochromatographic assay for rapid detection of transgenic vegetative insecticidal protein in genetically modified crops

Vegetative insecticidal protein (Vip) is now being used for transgenic expression in several crops; conferring resistance against lepidopteron pests. A rapid, single step, sensitive and specific immunochromatographic (IC) strip test for the detection of recombinant Vip-S protein in the transgenic samples was developed. Polyclonal rabbit anti-Vip-S IgG conjugated to nanocolloidal gold served as a probe to detect Vip protein in test samples. The detection limit for the developed IC strip was 100 ng/ml (100 ppb) and on addition of gold enhancer the sensitivity increased to 1 ng/ml (1 ppb) of Vip-S protein. The assay was validated with transgenic brinjal samples. The assay time was less than 10 min, suitable for rapid on-site testing. No cross-reactivity was observed with other transgenic plant proteins employed for pest and weed management, i.e. Cry1Ac, Cry1Ab, and CP4-EPSPS. This on-site test offers rapid screening for a genetically modified crops having relatively new transgene (vip) entering the global market.     

Extracellular biosynthesis of magnetite using fungi

The development of synthetic processes for oxide nanomaterials is an issue of considerable topical interest. While a number of chemical methods are available and are extensively used, the collaborations are often energy intensive and employ toxic chemicals. On the other hand, the synthesis of inorganic materials by biological systems is characterized by processes that occur at close to ambient temperatures and pressures, and at neutral pH (examples include magnetotactic bacteria, diatoms, and S-layer bacteria). Here we show that nanoparticulate magnetite may be produced at room temperature extracellularly by challenging the fungi, Fusarium oxysporum and Verticillium sp., with mixtures of ferric and ferrous salts. Extracellular hydrolysis of the anionic iron complexes by cationic proteins secreted by the fungi results in the room-temperature synthesis of crystalline magnetite particles that exhibit a signature of a ferrimagnetic transition with a negligible amount of spontaneous magnetization at low temperature.     

Differential Coding for Non-Orthogonal Space-Time Block Codes with Non-Unitary Constellations over Arbitrarily Correlated Rayleigh Channels

In this paper, we propose a maximum likelihood (ML) decoder for differentially encoded full-rank square nonorthogonal space-time block codes (STBCs) using unitary or non-unitary signal constellations, which is also applicable to fullranked orthogonal STBC (OSTBC). As the receiver is jointly optimized with respect to the channel and the unknown data, it does not require any knowledge of channel power, signal power, or noise power to decode the signal, and the decision is purely based on two consecutively received data blocks. We analyze the effect of channel correlation on the performance of the proposed system in Rayleigh fading channels. Assuming a general correlation model, an upper bound of the pair-wise error probability (PEP) of the differential OSTBCs is derived. An approximate bound of the PEP for the differential nonorthogonal STBCs is also derived. We propose a precoder designing criterion for differential STBC over arbitrarily correlated Rayleigh channels. Precoding improves the system performance over the correlated Rayleigh MIMO channels. Our precoded differential codes differ from the previously proposed precoder designs for differential OSTBC in the following ways: 1) We propose a precoder design for arbitrarily correlated Rayleigh channels, whereas the previous work considers only for transmit correlation. 2) The previous work is only applicable to the OSTBCs with PSK constellations, whereas our precoder is applicable to any type of full-rank square STBCs with unitary and non-unitary signal constellations.     

Amperometric Determination of Cerium and Vanadium,and Cerium and Molybdenum in Their Binary Mixtures Using Two Indicator Electrodes

In recent studies in this laboratory, the amperometric method has been applied for the successive determination of cerium and iron [1] and a number of other elements in their binary mixtures [2–3]. In the present investigation this method has been extended for the estimation of mixtures of cerium and vanadium or cerium and molybdenum, using ascorbic acid as titration reagent.     

ML decoder for double-differential diagonal unitary STBC

The maximum-likelihood (ML) decoder is derived for diagonal unitary space-time block code (STBC) matrices based space-time block code based double-differential modulation for multiple-input multiple-output systems. The ML decoder is obtained on the basis of maximising the joint probability density function of three consecutively received data matrices.     

38—THE EFFECT OF SPINNING CONDITIONS ON THE TENSILE PROPERTIES OF CORE-SPUN YARNS

A critical assessment of the merits of core-spinning by means of comparisons of the strength and extension of core-spun yarns with all-staple-fibre yarns forms the basis of this paper. Core-spinning was done by introducing the filament under tension into the drafted strand as the latter entered the front rollers of the ring-frame. A 20-den (2.2-tex) nylon monofilament was used as core, and three types of staple-fibre covering were investigated. The effects of twist, pre-tension, and feeding arrangements on the geometrical disposition and tensile properties of the yarns were examined. Improvements in strength are, in general, realized at low twists by the incorporation of the filament and by further constraining it to occupy the core. The contribution of the components to the yarn strength and the process of breaking were also subjected to a detailed study. The studies reported provide an interesting insight into the extent of cohesion developed between the fibres during the straining of the yarn and its influence on the process of breaking and ultimately on yarn extension.     

Optically Stimulated Artificial Synapse Based on Layered Black Phosphorus

The translation of biological synapses onto a hardware platform is an important step toward the realization of brain‐inspired electronics. However, to mimic biological synapses, devices till?date continue to rely on the need for simultaneously altering the polarity of an applied electric field or the output of these devices is photonic instead of an electrical synapse. As the next big step toward practical realization of optogenetics inspired circuits that exhibit fidelity and flexibility of biological synapses, optically?stimulated synaptic devices without a need to apply polarity?altering electric field are needed. Utilizing a unique photoresponse in black phosphorus (BP), here reported is an all?optical pathway to emulate excitatory and inhibitory action potentials by exploiting oxidation?related defects. These optical synapses are capable of imitating key neural functions such as psychological learning and forgetting, spatiotemporally correlated dynamic logic and Hebbian spike?time dependent plasticity. These functionalities are also demonstrated on a flexible platform suitable for wearable electronics. Such low‐power consuming devices are highly attractive for deployment in neuromorphic architectures. The manifestation of cognition and spatiotemporal processing solely through optical stimuli provides an incredibly simple and powerful platform to emulate sophisticated neural functionalities such as associative sensory data processing and decision making.     

Ambient Protection of Few‐Layer Black Phosphorus via Sequestration of Reactive Oxygen Species

Few‐layer black phosphorous (BP) has emerged as a promising candidate for next‐generation nanophotonic and nanoelectronic devices. However, rapid ambient degradation of mechanically exfoliated BP poses challenges in its practical deployment in scalable devices. To date, the strategies employed to protect BP have relied upon preventing its exposure to atmospheric conditions. Here, an approach that allows this sensitive material to remain stable without requiring its isolation from the ambient environment is reported. The method draws inspiration from the unique ability of biological systems to avoid photo‐oxidative damage caused by reactive oxygen species. Since BP undergoes similar photo‐oxidative degradation, imidazolium‐based ionic liquids are employed as quenchers of these damaging species on the BP surface. This chemical sequestration strategy allows BP to remain stable for over 13 weeks, while retaining its key electronic characteristics. This study opens opportunities to practically implement BP and other environmentally sensitive 2D materials for electronic applications.     

Spatial coherence of the generalized diffraction-filtered resonator copper vapor laser

The results of a study on the spatial coherence of a generalized diffraction-filtered resonator (GDFR) copper vapor laser (CVL) for various magnifications are presented. The coherence width and output power are compared with that of unstable resonators (UR's) of equivalent magnifications. It is established, by use of reversal shear interferometry, that the GDFR CVL beam has better spatial coherence and average power characteristics than the UR CVL beam for equivalent resonator magnifications.