Hardness determination of bio-ceramics using Laser-Induced Breakdown Spectroscopy

Laser-Induced Breakdown Spectroscopy (LIBS) was applied to the analysis of bio-ceramic samples. The relationship between sample hardness and LIBS plasma properties was investigated, with comparison to conventional Vickers hardness measurements. The plasma excitation temperature T_e was determined using the line-to-continuum ratio for the Si (I) 288.16 nm emission line; we have demonstrated a linear relationship between sample surface hardness and plasma temperature. Results indicate that hardness determination based on measurements of T_e offers greater reproducibility than Vickers hardness measurements, under the conditions considered here. The validity of spectroscopic diagnostics based on LTE was confirmed.     

Synthesis,structural aspects and nonlinear optical properties of novel phthalimide derivatives: theoretical and experimental approach

Novel phthalimides ( 1 , 2 , 3 ) possessing variability of cyclic amines have been synthesized and characterized by analytical and spectroscopic techniques. Phthalimide 1 and 2 crystallized in a triclinic system with space group Pī; however, an orthorhombic system with a chiral space group of P2₁2₁2₁ was observed for 3 possessing piperidine cyclic amine. The hydrogen atoms attached to the central chiral carbon were oriented anti to each other resulting in minimum steric repulsion. The occurrence of C–H···O hydrogen bonds in 1 , 2 , 3 enabled the building of several supramolecular structures. Hyperpolarizability 197.6096 Debye Ų calculated for 1 was found to be higher than the hyperpolarizabilities, 138.0836 and 165.2521 Debye Ų measured for 2 and 3 , respectively. Subsequently, phthalimides ( 1 , 2 , 3 ) were assessed for second harmonic generation (SHG) response, and a negligible response was recorded for 1 and 2 ; however, 3 showed a significant response of 14.2 mV. In addition to acentric structure, helical structural motifs identified in 3 could be responsible for its enhanced SHG response. Copyright © 2014 John Wiley & Sons, Ltd.     

Rationalizing fragment based drug discovery for BACE1: insights from FB-QSAR,FB-QSSR,multi objective (MO-QSPR) and MIF studies

The ability to identify fragments that interact with a biological target is a key step in FBDD. To date, the concept of fragment based drug design (FBDD) is increasingly driven by bio-physical methods. To expand the boundaries of QSAR paradigm, and to rationalize FBDD using In silico approach, we propose a fragment based QSAR methodology referred here in as FB-QSAR. The FB-QSAR methodology was validated on a dataset consisting of 52 Hydroxy ethylamine (HEA) inhibitors, disclosed by GlaxoSmithKline Pharmaceuticals as potential anti-Alzheimer agents. To address the issue of target selectivity, a major confounding factor in the development of selective BACE1 inhibitors, FB-QSSR models were developed using the reported off target activity values. A heat map constructed, based on the activity and selectivity profile of the individual R-group fragments, and was in turn used to identify superior R-group fragments. Further, simultaneous optimization of multiple properties, an issue encountered in real-world drug discovery scenario, and often overlooked in QSAR approaches, was addressed using a Multi Objective (MO-QSPR) method that balances properties, based on the defined objectives. MO-QSPR was implemented using Derringer and Suich desirability algorithm to identify the optimal level of independent variables (X) that could confer a trade-off between selectivity and activity. The results obtained from FB-QSAR were further substantiated using MIF (Molecular Interaction Fields) studies. To exemplify the potentials of FB-QSAR and MO-QSPR in a pragmatic fashion, the insights gleaned from the MO-QSPR study was reverse engineered using Inverse-QSAR in a combinatorial fashion to enumerate some prospective novel, potent and selective BACE1 inhibitors.     

Supramolecular hydrogen‐bonding patterns in two cocrystals of the N(7)–H tautomeric form of N6‐benzoyladenine: N6‐benzoyladenine–3‐hydroxypyridinium‐2‐carboxylate (1/1) and N6‐benzoyladenine–DL‐tartaric acid (1/1)

Two novel cocrystals of the N(7)—H tautomeric form of N⁶‐benzoyladenine (BA), namely N⁶‐benzoyladenine–3‐hydroxypyridinium‐2‐carboxylate (3HPA) (1/1), C₁₂H₉N₅O·C₆H₅NO₃, (I), and N⁶‐benzoyladenine–DL‐tartaric acid (TA) (1/1), C₁₂H₉N₅O·C₄H₆O₆, (II), are reported. In both cocrystals, the N⁶‐benzoyladenine molecule exists as the N(7)—H tautomer, and this tautomeric form is stabilized by intramolecular N—H...O hydrogen bonding between the benzoyl C=O group and the N(7)—H hydrogen on the Hoogsteen site of the purine ring, forming an S(7) motif. The dihedral angle between the adenine and phenyl planes is 0.94 (8)° in (I) and 9.77 (8)° in (II). In (I), the Watson–Crick face of BA (N6—H and N1; purine numbering) interacts with the carboxylate and phenol groups of 3HPA through N—H...O and O—H...N hydrogen bonds, generating a ring‐motif heterosynthon [graph set R₂²(6)]. However, in (II), the Hoogsteen face of BA (benzoyl O atom and N7; purine numbering) interacts with TA (hydroxy and carbonyl O atoms) through N—H...O and O—H...O hydrogen bonds, generating a different heterosynthon [graph set R₂²(4)]. Both crystal structures are further stabilized by π–π stacking interactions.     

Study of effects of polishing and etching processes on Cd1−xZnxTe surface quality

The effect of surface preparation on CdZnTe properties was investigated. Surface etching using bromine solutions enhances Te elemental composition, resulting in a Te rich surface layer that is prone to oxidize. This oxidation degrades the performance of the fabricated CZT gamma detector. Roughness results were identical for samples polished with 1 and 3 μm and subsequently etched in 2% Br-MeOH. The optimal concentration of etching was 2% Br-MeOH.     

Copper‐Mediated Coupling of 1,1‐Dibromo‐1‐alkenes with Nitrogen Nucleophiles: A General Method for the Synthesis of Ynamides

Mild reaction conditions are the advantage of the title reaction, which allows straightforward entry to a variety of ynamides starting from readily available 1,1‐dibromo‐1‐alkenes, which act as attractive alkynylating agents (see scheme; EWG=electron‐withdrawing group, DMF=N,N‐dimethylformamide).

     

Raman spectral analysis of phenoxyacetic acid and some chloro substituted phenoxyacetic acids

Raman spectra of phenoxyacetic acid and chlorine substituted phenoxyacetic acids viz., o-chlorophenoxyacetic acid, p-chlorophenoxyacetic acid and 2,6-dichlorophenoxyacetic acid have been analysed with the aid of abinitio theoretical calculations. The effect of chlorine substituents on the Raman spectra of phenoxyacetic acid have also been analysed by considering some important vibrational modes.     

Interlaboratory study to improve the quality of trace element determinations in rainwater

This is the first publication which describes the development of a reference material (RM) for the determination of 11 trace elements (Cu, Pb, Mn, Ni, Zn, Fe, Cd, Co, V, As and Al) in rainwater at microgram per liter concentrations. An interlaboratory comparison study for the determination of trace elements in rainwater was carried out for material performance studies to establish analyte concentrations with a stated uncertainty. Fifteen reputed laboratories from Asia, Europe and North America participated in the study. These laboratories used their regular in-house methods to analyze the rainwater samples. The aim of this study is to establish concentration levels of trace elements in rainwater based on interlaboratory study results. Details of the production, homogeneity and stability of the reference sample are given in this article. The organization of the study and the quality assurance measures undertaken at the organizer's laboratory are described. The analytical results obtained from individual laboratories and the analytical methods used for the determination of trace elements in rainwater are discussed. Based on the results obtained from the intercomparison study, certified values as well as informative values are assigned to the 11 trace elements in rainwater.     

Inventory models with a mixture of backorders and lost sales under fuzzy cost

Continuous review and periodic review inventory models in which a fraction of demand is backordered and the remaining fraction is lost during the stockout period are considered under fuzzy environment. Fuzziness is introduced by allowing the cost components imprecise and vague to certain extent. Trapezoidal fuzzy numbers are used to represent these characteristics. The optimum policies of these models under fuzzy costs are derived. Numerical results highlighting the sensitivity in the decision variables are also described.     

Preparation and surface charge studies of bio-magnetoelectrets of l-serine

This paper reports the study of surface charge characteristics of bio-magnetoelectrets of amino acid l-serine. Electrets were prepared under the combined effect of heat and magnetic field. Three different forming temperatures and five different magnetic fields were used for the study. The bio-magnetoelectrets prepared this way were observed to have a surface charge of the order of 10^?9 C. The decay of surface charge was studied continuously for 20 days and corresponding time constant was calculated. The comparative studies of surface charge characteristics were done by preparing bio-magnetoelectrets using homogeneous and inhomogeneous magnetic fields.