Experimental determination of the relaxation modulus of a linear-isotropic-viscoelastic material

It is well known that the relaxation modulus of a linear-isotropic-viscoelastic material under uniaxial load is the stress history of a unit-step strain history. A unit-stepped strain function cannot be obtained with the common instron testing machine. Instead, an easily obtainable strain function is described from which the relaxation modulus is derived. Experiments were conducted to illustrate this method. Experimental-data-reduction techniques are described. Experimentally measured output stress vs. time is fitted by a ‘smooth’ polynomial using a least-square criterion. Then by differentiation of this polynomial at proper times, the relaxation function is obtained.     

Measurement of spectrum with particle image velocimetry

The purpose of this paper is to show that the measurement of turbulent spectrum using wholefield velocity techniques such as particle image velocimetry (PIV) is possible. Toward this end, data from the axial plane of a self-similar turbulent axisymmetric jet, at a Reynolds number, based on Taylor microscale of 30 has been analyzed. The two-dimensional velocity data are first high-pass filtered, which educes the vortices. An automated method is then used to identify the vortices and measure their properties. By directly measuring the energy of the vortices, it is possible to plot the turbulence spectrum. The spectrum presented here shows the presence of energy containing and inertial regimes. However, the smallest scales have not been resolved in the measurements. The slope of the spectrum in the inertial subrange is about −1.6. The number of vortices in the two regimes have also been measured. The number of vortices in the energy containing regime is substantially smaller than those in the inertial subrange. The technique has been verified by analyzing another dataset. These results show that the direct measurement of vortex properties with reasonable confidence is possible using PIV and an appropriate vortex eduction technique.     

Blending type approximation by q‐generalized Boolean sum of Durrmeyer type

This paper is in continuation of the work performed by Kajla et al. (Applied Mathematics and Computation 2016; 275 : 372–385.) wherein the authors introduced a bivariate extension of q‐Bernstein–Schurer–Durrmeyer operators and studied the rate of convergence with the aid of the Lipschitz class function and the modulus of continuity. Here, we estimate the rate of convergence of these operators by means of Peetre's K‐functional. Then, the associated generalized Boolean sum operator of the q‐Bernstein–Schurer–Durrmeyer type is defined and discussed. The smoothness properties of these operators are improved with the help of mixed K‐functional. Furthermore, we show the convergence of the bivariate Durrmeyer‐type operators and the associated generalized Boolean sum operators to certain functions by illustrative graphics using Maple algorithm. Copyright © 2017 John Wiley & Sons, Ltd.     

Electro organic synthesis and characterization of phenol–aniline based copolymers

A new series of copolymers of phenol and aniline poly(PHE-co-ANI) was synthesized at platinum electrode through electro-oxidative polymerization in acetonitrile in the presence of lithium perchlorate as supporting electrolyte. Electro-polymerization was studied by cyclic voltammetry. The resultant copolymers were characterized by UV–Vis, IR, ¹³C and ¹H NMR spectroscopy; surface morphology of the copolymers was investigated by scanning electron microscopy.     

Carboxymethylpsyllium (CMPsy)/poly(acrylamide)(poly(AAm)) hydrogels for oral delivery of anti-diabetic drug Gliclazide

In this work, controlled release of anti-diabetic drug Gliclazide (Glz) from the carboxymethylpsyllium (CMPsy)/poly(acrylamide) (poly (AAm)) semi-interpenetrating networks (Semi-IPN) has been studied under physiological conditions. The semi-IPN was characterized by TGA, XRD and FTIR analysis. The release of drug Glz was observed to increase with concentration of drug entrapped in the hydrogels but varied inversely with the degree of crosslinking of the semi-IPN. The release data were analyzed using various kinetic models. Finally, the in-vivo investigation of efficacy of Gliclazide–loaded semi-IPN was carried out on Albino wistar rats. The formulation demonstrated fair effectiveness in reducing the glucose level, even at an oral administration frequency of once every alternate day.     

Al-induced electroless deposition and characterization of Ni–Sn film anode for Li-ion battery

Journal of Solid State Electrochemistry - Nickel–Tin (Ni–Sn) film was fabricated by aluminum (Al) induced electroless process on copper foils as a current collector. This film was...     

Dissociative Adsorption of H2S on Li(110) Surface Using Density Functional Theory Calculations and Car-Parrinello Molecular Dynamics Simulations

The information concerning dissociative adsorption of H₂S on Li surface is inadequate and the mechanistic insight for its complete dissociation is yet to be explored. The present investigation aims to scrutinize the dissociative adsorption of H₂S on Li(110) surface using density functional theory calculations. The climbing image nudged elastic band calculation was employed to unveil the relative energy profiles for S−H dissociation. To elucidate the components of interaction energy responsible for stabilizing the adsorbed moieties on the surface, periodic energy decomposition analysis was performed. A Car-Parrinello molecular dynamics (CPMD) simulation was performed to understand the dynamic behaviour of H₂S on Li(110). Results vividly demonstrates: (i) partially dissociated product with perpendicular S−H is comparatively stable than the parallel SH, (ii) completely dissociated moieties H/H/S are the most stable among all, (iii) dissociation of first S−H is barrierless and the second S−H dissociation is a low energy barrier reaction, (iv) complete dissociation of H₂S occurs in a stepwise manner, (v) orbital and electrostatic contributions of the interaction energy plays a vital role in stabilizing the dissociated moieties, and (vi) stepwise dissociation of H₂S was further reinforced by CPMD.     

Tuning the size,concaveness, and aspect ratio of concave cubic gold nanoparticles produced with high reproducibility

Reproducible fabrication of concave cubic gold nanoparticles with precise control over size, concaveness, and aspect ratio is important because the nanoscale structural characteristics can influence their plasmonic and catalytic properties. However, this is particularly challenging because the number of synthetic parameters involved in the fabrication strategy adds complexity to the reaction mechanism. Here, we introduce a simplified seed-mediated method and uncover the unknown conceptual insights on how the different halides and their concentration influence the surface structure and stability of underpotential silver monolayer deposited on the high energy facets of nanoparticles. The results reveal that adding Br^? and I^? ions to growth solution offers a predominant way to control the reaction kinetics and engineering nanoparticles with a predefined size, morphology, concaveness, aspect ratio, and plasmonic properties. Using spectroscopy and microscopy techniques, we shed new light on the reaction kinetics of concave cubic gold nanoparticles using the combined influence of silver underpotential deposition and halides. The strategy developed here can be expanded to fabricate gold nanoparticles of complex geometries. The results from our electromagnetic calculations suggest that the self-assembled superstructure of concave cubic gold nanoparticles can be more appealing for developing an ultra-sensitive sensing platform than to self-assembled superstructures of truncated cubic gold nanoparticles.     

Enhanced Charge Separation Efficiency in Pyridine‐Anchored Phthalocyanine‐Sensitized Solar Cells by Linker Elongation

A series of zinc phthalocyanine sensitizers ( PcS22 – 24 ) having a pyridine anchoring group are designed and synthesized to investigate the structural dependence on performance in dye‐sensitized solar cells. The pyridine‐anchor zinc phthalocyanine sensitizer PcS23 shows 79 % incident‐photon to current‐conversion efficiency (IPCE) and 6.1 % energy conversion efficiency, which are comparable with similar phthalocyanine dyes having a carboxylic acid anchoring group. Based on DFT calculations, the high IPCE is attributed with the mixture of an excited‐state molecular orbital of the sensitizer and the orbitals of TiO₂. Between pyridine and carboxylic acid anchor dyes, opposite trends are observed in the linker‐length dependence of the IPCE. The red‐absorbing PcS23 is applied for co‐sensitization with a carboxyl‐anchor organic dye D131 that has a complementary spectral response. The site‐selective adsorption of PcS23 and D131 on the TiO₂ surface results in a panchromatic photocurrent response for the whole visible‐light region of sun light.