On the number of generators of the module of derivations and multiplicity of certain rings

The present paper studies the module of derivations of certain rings and the multiplicity of certain rational surface singularities. We also consider some relation between these two for 2-dimensional quotient singularities. We conjecture a relation between the multiplicity of a rational surface singularity and the order of the divisor class group of the singularity and verify the same for several cases.     

Kinetics and mechanism of oxidation of aliphatic alcohols by tetrabutylammonium tribromide

Oxidation of nine primary aliphatic alcohols by tetrabutylammonium tribromide (TBATB) in aqueous acetic acid leads to the formation of the corresponding aldehydes. The reaction is first order with respect to TBATB. Michaelis-Menten type kinetics is observed with respect to alcohols. The reaction failed to induce the polymerization of acrylonitrile. Tetrabutylammonium chloride has no effect on the reaction rate. The proposed reactive oxidizing species is the tribromide ion. The oxidation of [1,1-²H₂]ethanol exhibits a substantial kinetic isotope effect. The effect of solvent composition indicates that the rate increases with increase in the polarity of the solvent. The reaction is susceptible to both polar and steric effects of substituents. A mechanism involving transfer of a hydride ion in the rate-determining step has been proposed.     

Preparation of biomolecule-ligated polystyrene cuvets and their applications in diagnostics

Activated polystyrene cuvet is used for the determination of oxalate in urine sample and immunoglobulin in human sera. Polystyrene cuvet was activated by introducing active functional group onto its surface by coating the surface with a heterobifunctional photolinker, 1-fluoro-2-nitro-4-azidobenzene and exposing to UV light at 365 nm. Modified cuvet was active enough to covalently link oxalate oxidase in just 45 min at 50 °C without any additional catalyst or reagent. Remarkable reduction of time was achieved when immobilization was carried out by microwave irradiation. It took only 50 s to immobilize oxalate oxidase in the activated cuvet when exposed to microwaves in a domestic microwave oven. Immobilized-oxalate oxidase was stable, reusable and conveniently used for determination of urinary oxalate for diagnosis of primary hyperoxaluria and calcium oxalate nephrolithaiasis. Detection of human IgG involving ELISA in antihuman IgG-immobilized cuvet showed the feasibility of the cuvet in other immunoassays.     

Spectroscopic investigations on kidney stones using Fourier transform infrared and X‐ray fluorescence spectrometry

Kidney stone is the most painful and prevalent urological disorder of the urinary system throughout the world. Thus, analysis of kidney stones is an integral part in the evaluation of patents having stone disease. Spectroscopic investigations of stones provide an idea about the pathogenesis of stones for its better cure and treatment. Hence, the present work targets multispectroscopic investigations on kidney stones using Fourier transform infrared (FTIR) and wave dispersive X‐ray fluorescence (WD‐XRF) spectroscopy which are the most useful analytical methods for the purpose of bio‐medical diagnostics. In the present study, FTIR spectral method is used to investigate the chemical composition and classification of kidney stones. The multicomponents of kidney stones such as calcium oxalate, hydroxyl apatite, phosphates, carbonates, and struvite were investigated and studied. Qualitative and quantitative determination of major and trace elements present in the kidney stones was performed employing WD‐XRF spectroscopy. The wide range of elements determined in the kidney stones were calcium (Ca), magnesium (Mg), phosphorous (P), sodium (Na), potassium (K), chlorine (Cl), sulfur (S), silicon (Si), iodine (I), titanium (Ti), iron (Fe), ruthenium (Ru), zinc (Zn), aluminum (Al), strontium (Sr), nickel (Ni), copper (Cu), and bromine (Br). For the first time, ruthenium was detected in kidney stone samples employing WD‐XRF in very low concentration. Our results revealed that the presence and relative concentrations of trace elements in different kinds of stones are different and depend on the stone types. From the experiments carried out on kidney stones for trace elemental detection, it was found that WD‐XRF is a robust analytical tool that can be useful for the diagnosis of urological disorders. We have also compared our findings with the results reported using XRF technique. The results obtained in the present paper show interesting prospects for FTIR and WD‐XRF spectrometry in nephrolithiasis. Copyright © 2017 John Wiley & Sons, Ltd.     

Mesomorphism dependence on molecular rigidity and substitution of same functional group on lateral or terminal position of tailed phenyl ring

Novel liquid crystal materials (LCs) of low temperature range (53°C to 75°C) have been synthesized through a series of chalconyl derivatives consisting of two phenyl rings bonded through a –CH?CH?CO? central bridge to study the effect of molecular structure on LC properties in general and with a focus on molecular rigidity. The novel homologues series (C₁ to C₁₈) consists of thirteen homologues with general formula RO?C₆H₄?CH?CH?CO?C₆H₄?OC₁₀H₂₁(n) (meta). The C₁, C₂, C₃ homologues are nonliquid crystals (NLC) and the rest of the homologues (C₄ to C₁₈) are either monotropic or enantiotropic liquid crystals. C₄ to C₆ homologues are enantiotropicnematic and the rest of the mesomorphic homologues are (C₇ to C₁₈) monotropicsmectic in addition to monotropicnematic character. Transition and melting temperatures including textures of homologues were determined by an optical polarizing (POM) microscopy equipped with a heating stage. Textures of a nematic phase are threaded or Schlieren, and that of the smectic phase are of the type Smectic A or C as judged directly from the heating top of the microscope. Thermal stability for smectic is very poor and of the nematic is (N-I) 69.3°C whose, total mesophase length ranges between 07.0 to 14.0°C at C₈ and C₄ homologues respectively.     

Mg–Al LDH reinforced PMMA nanocomposites: a potential material for packaging industry

Poly-methylmethacrylate/Mg–Al layered double hydroxide (PMMA/LDH) based nanocomposites have successfully been synthesised with varying LDH content by in situ polymerisation technique and systematically studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT IR), UV-Visible spectroscopy and microscopic (FE SEM and HR TEM) analysis. In particular, thermogravimetric analysis (TGA) and gas barrier properties measurement were carried out to assess the suitable application of these materials. The thermal property of PMMA/LDH composites was compared with neat PMMA and an enhancement in thermal stability was noticed with gradual increase in LDH content in the composite. Gas permeability measurement data showed significant decrease in oxygen permeability value of the PMMA/LDH nanocomposites in comparison to the pristine PMMA. Enhancement in thermal stability along with significant reduction in oxygen permeability of PMMA upon composite formation indicate the possible application of these materials in packaging industries.     

Lithium-enriched polypyrrole as a prospective cathode material for Li-ion cells

Lithium substitution in polypyrrole can be accomplished by a variety of approaches and the present work introduces one of the cost-effective techniques using a relatively less expensive lithium salt, n-butyllithium in hexanes (n-BuLi), as the dopant. Chemical oxidative polymerization method is employed to synthesize polypyrrole (PPy) using anhydrous ferric chloride as the oxidant and it is dedoped using NH₄OH solution in the fully reduced state. The dedoped polypyrrole is treated with n-butyllithium in hexanes (n-BuLi) in an argon-filled glove box to get the lithiated form of polypyrrole (PPyL) and the concentration of n-BuLi is varied to improve metalation. The lithiated PPy is characterized by FTIR spectroscopy, XRD, FESEM, and TEM techniques to understand the structural and the morphological details. The lithium content in the lithiated samples is estimated using ICP-AES analysis. The thermal studies using the TGA technique show that the lithiated polypyrrole has good thermal stability. Coin cells are assembled in the argon-filled glove box using Li-substituted polypyrrole as the cathode, lithium metal foil as the anode, and lithium hexafluorophosphate (LiPF₆) as the electrolyte. The assembled cells are electrochemically characterized using cyclic voltammetry and charge–discharge cycling techniques and it is seen that the Li-substituted polypyrrole-based Li-ion cells are electrochemically active.     

Covariant holographic entanglement negativity

We propose a covariant holographic conjecture for the entanglement negativity of bipartite mixed states in \((1+1)\)-dimensional conformal field theories dual to bulk non static \(AdS_{3}\) configurations. Application of our conjecture to \((1+1)\)-dimensional conformal field theories dual to bulk non extremal and extremal rotating BTZ black holes exactly reproduce the corresponding entanglement negativity obtained through the replica technique, in the large central charge limit. We briefly discuss the issue of the generalization of our conjecture to higher dimensions.     

Effect of H irradiation on the optical properties of vacuum evaporated AgInSe2 thin films

We prepared polycrystalline AgInSe₂ thin films by vacuum evaporation on glass substrate at a high temperature using the stoichiometric powder. The thin films were characterized by X-ray diffraction and UV-vis-NIR spectroscopy. The samples were subjected to the irradiation of 1.26 MeV protons (H⁺). The effect of irradiation on the optical properties has been investigated for different doses of H⁺. It is observed that the band gap of silver indium selenide thin films decreases gradually with ion irradiation dose.