Gold nanoparticle–polypyrrole composite modified TiO<Subscript>2</Subscript> nanotube array electrode for the amperometric sensing of ascorbic acid

Titanium dioxide (TiO₂) nanotubes were fabricated by anodisation of titanium foil in 0.15 M ammonium fluoride in an aqueous solution of glycerol (90 % v/v). Electropolymerisation of pyrrole and deposition of gold nanoparticles on to the TiO₂ nanotube array electrode were carried out by cyclic voltammetry (CV). Electrochemical characterization of the sensor was performed by CV and electrochemical impedance spectroscopy. The morphology of the electrode was studied after every step of modification using field emission scanning electron microscope and atomic force microscope. The sensor was tested for AA and other biomolecules in phosphate buffered saline solution of pH 7 using CV, differential pulse voltammetry and amperometry. The sensor exhibited very high sensitivity of 63.912 μA mM^?1 cm^?2 and excellent selectivity to ascorbic acid (AA) in the presence of other biomolecules such as uric acid, dopamine, glucose and para-acetaminophen. It also showed very good linearity (R = 0.9995) over a wide range (1 μM–5 mM) of detection. The sensor was tested for AA in lemon and found its concentration to be 339 mg ml^?1.     

Facile Hydrogen Evolution Reaction on WO3 Nanorods

Tungsten trioxide nanorods have been generated by the thermal decomposition (450 °C) of tetrabutylammonium decatungstate. The synthesized tungsten trioxide (WO₃) nanorods have been characterized by XRD, Raman, SEM, TEM, HRTEM and cyclic voltammetry. High resolution transmission electron microscopy and X-ray diffraction analysis showed that the synthesized WO₃ nanorods are crystalline in nature with monoclinic structure. The electrochemical experiments showed that they constitute a better electrocatalytic system for hydrogen evolution reaction in acid medium compared to their bulk counterpart.     

Gamma-radiation induced grafting of acrylonitrile onto guar gum: Influence of reaction conditions on the properties of the grafted and saponified products

In the gamma-radiation induced grafting of acrylonitrile onto guar gum, the influence of different concentration of the monomer acrylonitrile on the PAN add-on, the number average molecular weight of the PAN side chains, and the grafting frequency of the PAN side chains are reported. At 0.3 Mard dosage, the PAN add-on were 32.4, 48.5, and 66.2% and the number average molecular weight of the PAN side chains were 59,700, 132,200, and 238,900, respectively, at three different reaction conditions. The frequency of grafting also showed considerable variation at 0.2 Mrad dosage, for all three sets of samples. The viscosity of the aqueous dispersions of the saponified samples at different concentrations are also reported. The water absorbency of the saponified samples were evaluated and the values were around 250 g/g. The fall in viscosity of the aqueous dispersions on storage were also evaluated. The observed fall in viscosity was lower in the case of the product with higher PAN content. © 1993 John Wiley & Sons, Inc.     

Acidity of heteropoly compounds from XPS measurements

The changes in the partial charges on oxygens in the various heteropoly salts as a result of the acidity differences have been exploited for probing the oxygen 1s and W 4f lines. The gradation of the acidity thus obtained is compared to that of the conventional method.     

Joint space-time interpolation for distorted linear and bistatic array geometries

This paper presents a new joint space-time interpolation technique (STINT) to improve the small sample support performance of space-time adaptive processing (STAP) with distorted linear monostatic arrays and linear bistatic array configurations. Brennan's rule for the space-time clutter covariance matrix rank is extended to monostatic linear arrays with arbitrary intersensor spacing, distorted linear arrays and bistatic geometries. It is shown that both distortion in the array geometry and bistatic operation increase the clutter rank and cause the space-time clutter covariance matrix to become range dependent. This results in lower output signal-to-interference-plus-noise ratio (SINR) for the same number of adaptive degrees of freedom and reduced available sample support. This motivates the development of the STINT technique aimed at compensating for the clutter rank inflation, while also making the clutter statistics appear more stationary across range. More specifically, a linear transformation is designed that maps the received clutter across space and time to that which would be received by a "virtual" monostatic side-looking ULA. By mapping the data to form a reduced rank clutter covariance matrix, fewer snapshots are needed for a statistically stable matrix inversion as required in STAP, thereby improving the short observation time performance. Simulation results for a typical airborne radar scenario indicate up to 10-dB SINR improvement can be obtained using STINT with limited sample support.     

Optical properties of Eu<Superscript>3+</Superscript> activated SrLa<Subscript>2</Subscript>O<Subscript>4</Subscript> red-emitting phosphors for WLED applications

The SrLa_2?xO₄:xEu³⁺ phosphors are synthesized through high-temperature solid-state reaction method at 1473 K with various doping concentration. Their phase structures, absorption spectra, and luminescence properties are investigated by X-ray diffraction (XRD), UV–Vis spectrophotometer and photoluminescence spectrometry. The intense absorption of SrLa_2?xO₄:xEu³⁺ phosphors have occurred around 400 nm. The prominent luminescence spectra of the prepared phosphors exhibited bright red emission at 626 nm. The doping concentration 0.12 mol% of Eu³⁺ is shown to be optimal for prominent red emission and chromaticity coordinates are x?=?0.692, y?=?0.3072. Considering the high colour purity and appropriate emission intensity of Eu³⁺ doped SrLa₂O₄ can be used as red phosphors for white light emitting diodes (WLEDs).     

Numerical and Physical Simulation of the Fluid Flow in a Beam Blank Mold Fed Through the Center of the Web

Metallurgical and Materials Transactions B - Fluid flow inside a beam blank mold fed through a three-port SEN (two lateral ports and one bottom port), positioned at the center of the mold, has been...     

Conduction studies in anthraquinone derivatives. VI

Contrary to the results of the early 1960s, it has been found that the anthraquinone (AQ) and its derivatives can be made photoconductive (I _ph/I_D 10³) by substituting suitable donors in the periphery of the benzenoid rings. The conductivity of the AQ derivatives, generally speaking, are not as good as those of the charge transfer kind. The darkcurrent in the case of AQ derivatives ranges from 10^–14–10^–12 for 9,10-AQ to 10^–10–10^–8 for 1,4,5,8-tetra amino AQ. The AQs are n-type semiconductors with electrons being the majority charge carriers. In the present article, we describe the charge carrier generation and transport processes in three di-substituted AQ derivatives whose spectral properties have been well studied. The magnetic field effect has been observed for the first time in these compounds.     

Allicin May Promote Reversal of T-Cell Dysfunction in Periodontitis via the PD-1 Pathway

We evaluated the role of allicin in periodontitis using an in silico and in vitro design. An in silico docking analysis was performed to assess the plausible interactions between allicin and PD-L1. The cytokine profile of gingival crevicular fluid (GCF) samples obtained from periodontitis patients was estimated by cytometric bead array. CD3+ lymphocytes isolated from the peripheral blood were sorted and characterized using immunomagnetic techniques. Cultured and expanded lymphocytes were treated with the GCF samples to induce T-cell exhaustion. Optimum concentrations of allicin were added to exhausted lymphocytes to compare the expression of TIM-3 and LAG-3 gene expression at baseline and post-treatment. Allicin was found to bind to the PD-L1 molecule as revealed by the in-silico experiment, which is possibly an inhibitory interaction although not proven. GCF from periodontitis patients had significantly higher concentrations of TNF-α, CCL2, IL-6, IFN-γ, and CXCL8 than controls. GCF treatment of CD3+ lymphocytes from the periodontitis patients significantly increased expression of T-cell exhaustion markers TIM-3 and LAG-3. Allicin administration with GCF treatment resulted in significant lowering of the expression of exhaustion markers. Allicin may exert an immunostimulatory role and reverse immune-destructive mechanisms such as T-cell exhaustion.