Crystal growth and characterization of N-hydroxyphthalimide (C8H5NO3) crystal

Single crystals of N-hydroxyphthalimide (NHPH) were obtained from saturated aqueous solutions of methanol and acetonitrile by slow cooling method. The grown crystals were bright and transparent. From the crystal structure analysis it can be inferred that the crystal belongs to monoclinic system. The grown crystals were subjected to FTIR analysis for vibrational assignments. The optical transmission spectra showed excellent transmittance from 200 to 1100nm. The thermal stability and thermal decomposition of NHPH crystal have been investigated by means of thermogravimetric analysis and differential thermal analysis.     

Design of a "new motif" with beta-amino acids and alpha-aminoxy acids: synthesis of hybrid peptides with 12/10-helix

Hybrid peptides are prepared from a C-linked carbo-beta-amino acid ester (R-beta-Caa) and an alpha-aminoxy acid (R-Ama) derived from S-lactic acid. Extensive NMR (in CDCl 3 solution), CD, and MD studies on the tetra- and hexapeptides led to identification of robust 12/10-mixed helices. The dipeptide repeat having an R-beta-Caa and an R-Ama thus provides a "new motif" to realize a 12/10-mixed helix, for the first time, in oligomers containing R-Ama. To understand the impact of side chains in the mixed helix formation, R-beta-Caa/Ama (with no substitution in Ama) and S-beta-hAla/R-Ama oligomers were investigated. NMR studies revealed the existence of 12/10-helices in these hybrid peptides, and the side chains of monomers were found to have a profound influence on their stabilities. These observations imply that the propensity of beta-amino acid to prefer a mixed 12/10-helix governs the structural behavior in these peptides. The structural consequences of the lone-pair repulsion between nitrogen and oxygen atoms result in a new and interesting structural motif which behaves like "pseudo" beta (3),beta(2)-peptides in generating 12/10-mixed helices.     

Dielectric and conduction mechanism studies of Ni doped LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> synthesized by solution combustion method

In the present work, structural, morphological, dielectrical, and electrochemical properties of LiNi_xMn_(2-x)O₄ (where x?=?0, 0.1,0.3, 0.5 mol%) prepared by solution combustion method were reported. X-ray diffraction studies confirmed the formation of cubic spinel structure without any impurity phases. Scanning electron micrographs revealed grains of micrometer range with a spherical like morphology and narrow size distribution. Dielectric parameters such as dielectric constant, dielectric loss, impedance, and electrical modulus were found to depend on temperature, frequency, and dopant concentration. AC conductivity was found to increase with increase in temperature exhibiting negative temperature co-efficient of resistance (NTCR) property in the material. Complex impedance and electrical modulus studies revealed the existence of temperature-dependent electrical relaxation in the material. The Correlated Barrier Hopping (CBH) model of conduction mechanism was confirmed by the decrease in s parameter with increase in temperature. Charge-discharge studies revealed the stabilization of spinel lattice by Ni ions, contributing to better capacity retention.     

Fission in the reaction of12C with209Bi at 73.4 and 84.2 MeV

Fission product yield studies in the reaction of 73,4 and 84.2 MeV¹²C with²⁰⁹Bi have been carried out using gamma-ray spectrometry. The cross sections for the production of fission products have been determined. The yield distribution of fission products is found to be symmetric and broad with FWHM around 25 mass units and peak near mass 107.7 and 107.0. The average number of neutrons emitted per fission have been found to be around 5.5 at 73.4 MeV and 7.1 at 84.2 MeV, respectively.     

Determination of Defect Depth and Size Using Virtual Heat Sources in Pulsed Infrared Thermography

The determination of defect depth and size using Pulsed Infrared Thermography is a critical problem. The problem of defect depth estimation has been previously studied using 1D heat conduction models. Unfortunately, 1D heat conduction based models are generally inadequate in predicting heat flow around defects. In this study, a novel approach based on virtual heat sources is proposed to model heat flow around defects accounting for 2D axisymmetric heat conduction. The proposed approach is used to quantitatively determine the defect depth and size. The validity of the model is established using experiments performed on a stainless steel plate specimen with flat bottom holes at different depths.     

Metabolite profiling of arginase inhibitor activity guided fraction of Ficus religiosa leaves by LC–HRMS

Cardiovascular disease is one of the major causes of deaths worldwide. Increased arginase activity is associated with cardiovascular disease. The literature shows that plants are a good source of arginase inhibitors. Hence in the present work arginase inhibitor activity is studied from Ficus religiosa leaves. A fine powder of F. religiosa leaves was serially extracted in various solvents, viz. hexane, chloroform, ethyl acetate and methanol. Out of those four solvent extracts, the one showing highest arginase inhibitor activity was loaded onto the column for further fractionation. Among the collected fractions, the one showing the highest activity was subjected to identification of metabolites by using LC–HRMS. Total compounds including acipimox, edoxudine, levulinic acid, hydroxyhydroquinone, ramiprilglucuronide, berberine, antimycin A, swietenine and some short peptides were identified from the fraction showing the highest arginase inhibitory activity. Identification of these metabolites from F. religiosa and their biological importance may help to promote its use as medicinal plant. Further purification and characterization of therapeutically novel molecules will be the subject of future work.     

Measurement of alpha-decay constant to fission cross section ratio for actinides using solid state nuclear track detectors

A simple technique based on the measurement of the ratio of alpha-decay constant to neutron induced fission cross section for pure actinides using solid state nuclear track detectors (SSNTDs) is developed for the identification of the actinides in trace levels in pure solutions. The alpha-decay constant to fission cross section ratios for depleted U,²³⁸Pu and²⁴⁰Pu have been measured for the epicadmium neutron induced fission of these actinides. The measured values are (6.19±0.34)·10⁶, (6.95±0.26)·10¹², (2.12±0.95)·10⁹ and (2.18±1.58)·10¹¹ sec⁻¹·cm⁻², respectively. These ratios can be used for the trace level identification of pure actinides.     

Determination of palladium by chemical neutron activation analysis using low energy photon spectrometry

A chemical neutron activation analysis method to determine trace amounts of palladium present in the uranium ores has been developed. Palladium was concentrated on an anionic exchanger to purify from large amounts of uranium, iron and copper that were present in the ore. The resin in which Pd was adsorbed was neutron irradiated and the activation product¹⁰⁹Pd was assayed through its daughter^109mAg by low energy photon spectrometry to estimate palladium. Both the 88 keV gamma-line and the 22 keV X-ray line (arising out of the internal transition of^109mAg) were used to arrive at the concentration values by a standard comparison technique. A thin window Si(Li) detector and an HPGe detector were used for the radioactive assay. Detection limits and the advantage of using the X-ray line of Ag over that of the gamma-line were discussed. An absolute detection limit of 0.12·10⁻⁹ g could be arrived at by the use of the 22.10 keV X-ray line in an interference-free condition.     

Analytical and semi‐preparative enantioresolution of (RS)‐ketorolac from pharmaceutical formulation and in human plasma by HPLC

An efficient, simple, validated, analytical and semi‐preparative HPLC method has been developed for direct enantioresolution of (RS)‐Ketorolac (Ket) using monochloro‐methylated derivatives of cellulose and amylose, i.e. cellulose (tris‐3‐chloro‐4‐methylphenylcarbamate) and amylose (tris‐5‐chloro‐2‐methylphenylcarbamate) as chiral stationary phases (CSPs) with photo diode array detection at 320 nm. Enantioresolution was carried out in samples of human plasma spiked with (RS)‐Ket under normal and reversed‐phase elution modes with suitable mobile phase compositions. The effect of nature of alcohols (MeOH, EtOH, PrOH and n‐BuOH) and other solvents (MeCN and MeOH) as organic modifiers in the mobile phase was investigated on the separation performance of two CSPs in terms of retention and separation of enantiomers. The best resolution was observed on cellulose‐based CSP using EtOH, while using 2‐PrOH (15%) and amylose‐based CSP obtained the highest retention. Under reversed‐phase elution mode the best enantioseparation was observed using 30% MeCN with ammonium formate buffer. The elution order of enantiomers was ascertained by determining specific rotations. The limit of detection and quantitation values were 5 and 15.5 ng/mL for each enantiomer of (RS)‐Ket, respectively. Copyright © 2016 John Wiley & Sons, Ltd.