Electrodeposition and Corrosion Properties of Zn-V2O5 Composite Coatings

Composite coatings were obtained by electrochemical codeposition of V₂O₅ nanoparticles with zinc, from an additive free acid sulfate bath. The corrosion behavior of electrodeposited Zn and Zn-V₂O₅ composite coatings was investigated in 3.5% NaCl solution using polarization and electrochemical impedance spectroscopy (EIS). The decrease in I _corr values and an increase in R _ct values show the higher corrosion resistant nature of Zn-V₂O₅ coatings. The observed textural modifications of composite coatings are associated with the specific structural modification of Zn crystallites provoked by the adsorption-desorption phenomena occurring on the metal surface, induced by the presence of V₂O₅ nanoparticles. It has been observed that the presence of V₂O₅ nanoparticles favors the [1 0 2] and [1 1 2] texture of zinc matrix. Moreover, the codeposition of V₂O₅ nanoparticles with zinc was found to be favored at pH 3.5 and applied current density 4?A?dm^?2. A considerable grain refinement of the deposit occurred due to incorporation of V₂O₅ nanoparticles and hence improved the preferred orientation of the zinc crystallites.     

Investigation of ethanol gas sensing properties of Dy-doped SnO<Subscript>2</Subscript> nanostructures

In this paper we report doping induced enhanced sensor response of SnO₂ based sensor towards ethanol at a working temperature of 200 °C. Undoped and dysprosium-doped (Dy-doped) SnO₂ nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD and Raman results verified tetragonal rutile structure of the prepared samples. It has been observed that crystallite size reduced with increase in dopant concentration. In addition, the particle size has been calculated from Raman spectroscopy using phonon confinement model and the values match very well with results obtained from TEM and X-ray diffraction investigations. Dy-doped SnO₂ sensors exhibited significantly enhanced response towards ethanol as compared to undoped sensor. The optimum operating temperature of doped sensor reduced to 200 °C as compared to 320 °C for that of undoped sensor. Moreover, sensor fabricated from Dy-doped SnO₂ nanostructures was highly selective toward ethanol which signifies its potential use for commercial applications. The gas sensing mechanism of SnO₂ and possible origin of enhanced sensor response has been discussed.     

High pressure hermetic compression seals for embedding elastomeric membrane microvalves in polymer microfluidic devices

The application of elastomeric membrane microvalves with polymeric microfluidic devices is currently impeded by bonding methods which limit operating pressures. A novel compression sealing approach is presented for embedding elastomeric membranes between polymeric microchannel laminae through the use of sealing bosses. Sealing bosses are used effectively to concentrate clamping forces producing compression seals with higher operating pressures. The technique is capable of integrating elastomeric membrane microvalves within a wider variety of materials. Further, compression seals allow devices to be disassembled allowing for cleaning and analysis. Finite element methods are used to investigate the effects of sealing boss size and location on valve deformation as a function of clamping pressure. Experimental results are in good agreement with the model and show that the device can be configured to withstand operating pressure beyond 689 kPa.     

Design of variable elliptical filters with direct tunability in 2D domain

Multidimensional Systems and Signal Processing - This paper proposes the design of transformation based two dimensional (2D) elliptical filters using multi-objective artificial bee colony (MOABC)...     

Modified Metaheuristic Algorithms for the Optimal Design of Multiplier-Less Non-uniform Channel Filters

Reconfigurable non-uniform channel filters are now being widely used in software define radio (SDR). The hardware implementation of these filters requires low complexity, low chip area and low power consumption. The frequency response masking (FRM) approach is proved to be a good candidate for the realization of a sharp digital finite impulse response (FIR) filter with low complexity. To reduce the complexity further, this paper gives an optimal design method which makes the channel filters totally multiplier-less. This is done in two steps. The channel filters are designed using the FRM approach with continuous filter coefficients. To obtain multiplier-less design, these filter coefficients are converted to finite-precision coefficients using signed power of two (SPT) space and the filter coefficients are synthesized in the canonic signed-digit (CSD) format. But this may lead to degradation of the filter performance. Hence the filter coefficients synthesis in the CSD format is formulated as an optimization problem. Several meta-heuristic algorithms like Differential Evolution (DE), Artificial Bee Colony (ABC), Harmony Search Algorithm (HSA) and Gravitational Search Algorithm (GSA) are modified and deployed and the best one is selected.     

Effect of plant growth regulators on production of alpha-linolenic acid from microalgae <Emphasis Type="Italic">Chlorella pyrenoidosa</Emphasis>

The effect of various plant growth regulators (6-benzylaminopurine (BAP), 6-furfurylaminopurine (Kinetin), gibberellic acid (GA3), 1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA)) on the yields of biomass and an essential free fatty acid (alpha-linolenic acid from Chlorella pyrenoidosa) were studied. NAA and BAP showed significant increase of 2.2- (0.2905 to 0.6497 g/L) and 1.26-fold (0.2905 to 0.3727 g/L) in biomass yield, respectively. The only plant growth regulators belonging to the group cytokinins (BAP and kinetin) showed prominent rise in the yields of alpha-linolenic acid. BAP and kinetin resulted in 2.94- (371.83 to 1105.93 µg/mL) and 3.03-fold (371.83 to 1128.25 µg/mL) increase in ala yields, respectively, compared with that of control.     

Metaheuristic algorithms for the design of multiplier-less non-uniform filter banks based on frequency response masking

In this paper, multiplier-less nearly perfect reconstruction tree structured non-uniform filter banks (NUFB) are proposed. When sharp transition width filter banks are to be implemented, the order of the filters and hence the complexity will become very high. The filter banks employ an iterative algorithm which adjusts the cut off frequencies of the prototype filter, to reduce the amplitude distortion. It is found that the proposed design method, in which the prototype filter is designed by the frequency response masking method, gives better results when compared to the earlier reported results, in terms of the number of multipliers when sharp transition width filter banks are needed. To reduce the complexity and power consumption for hardware realization, a design method which makes the NUFB totally multiplier-less is also proposed in this paper. The NUFB is made multiplier-less by converting the continuous filter bank coefficients to finite precision coefficients in the signed power of two space. The filter bank with finite precision coefficients may lead to performance degradation. This calls for the use of suitable optimization techniques. The classical gradient based optimization techniques cannot be deployed here, because the search space consists of only integers. In this context, meta-heuristic algorithm is a good choice as it can be tailor made to suit the problem under consideration. Thus, this design method results in near perfect NUFBs which are simple and multiplier-less and have linear phase and sharp transition width with very low aliasing. Also, different non-uniform bands can be obtained from the tree structured filter bank by rearranging the branches.     

Structural,Thermal and Luminescence Study of Ceria Nanocrystals Dispersed in Silica Matrix

Silicon - Ceria (CeO2) nanocrystals dispersed in silica were prepared by sol-gel, a very suitable method for large-scale production. The formation of cubic fluorite structure of CeO2 nanocrystals...     

Black-body radiation shifts and theoretical contributions to atomic clock research

A review of theoretical calculations of black-body radiation (BBR) shifts in various systems of interest to atomic clock research is presented. Calculations for monovalent systems, such as Ca⁺, Sr⁺, and Rb are carried out using a relativistic all-order single-double method, where all single and double excitations of the Dirac-Fock wave function are included to all orders of perturbation theory. A recently developed method for accurate calculations of BBR shifts in divalent atoms such as Sr is discussed. This approach combines the relativistic all-order method and the configuration interaction method. The evaluation of uncertainties in theoretical values of BBR shifts is discussed in detail.