Chiral Separation of 4-Iminoflavan Derivatives on Several Polysaccharide-Based Chiral Stationary Phases by HPLC

The HPLC enantiomeric separation of seven 4-iminoflavans was successfully accomplished in the normal phase mode using six polysaccharide-based chiral stationary phases namely, Chiralcel^®OD-H, Chiralcel^®OD, Chiralcel^®OJ, Chiralpak^®AD, Chiralpak^®IA and Chiralpak^®IB under normal and polar organic phase modes. The resolution depended on nature and concentration of alcoholic modifier. The results demonstrate clearly that the chromatographic system based on the coated and immobilized type Chiralpak^®IB and Chiralcel^®OD-H CSPs provide a powerful analytical tool for enantiomeric separation of all the 4-iminoflavans used in this study.     

Urinary phenylethylamine excretion: gas chromatographic assay with electron-capture detection of the pentafluorobenzoyl derivative

Phenylethylamine was extracted into n-hexane from alkaline urine saturated with sodium chloride, and back-extracted into dilute acid. The extract was freeze-dried and the residue converted to a pentafluorobenzoyl derivative for analysis by gas chromatography on a column of OV-225 with electron-capture detection. Quantification was achieved by adding an internal standard of tolylethylamine to each sample prior to extraction. Output values in normal subjects and in some patients with phenylketonuria and hyperphenylalaninaemia were in agreement with those in some other recent reports.     

A DFT study of inclusion complexes of the antituberculosis drugs pyrazinamide and isoniazid with cucurbit[7]uril

A photoactive system, (2E)-3-{3-[(Z)-naphthalen-1-yldiazenyl] phenyl} prop-2-enoic acid, was synthesized and incorporated on to beta-cyclodextrin (β-CD) core through esterification of the hydroxyl groups of β-CD with the free carboxyl moiety of the chromophoric system by DCC coupling. The silver nanoparticle was synthesized by the reduction reaction executed on silver acetate in presence of dodecyl amine. The silver nano particles were dispersed in β-CD aggregates modified with photoactive system by phase transfer mechanism. The products were characterized by elemental analysis, melting point determination, UV–visible, FT-IR and NMR (¹H and ¹³C) spectral methods and SEM and TGA-DTG thermal studies. The thermal studies shows that the silver nanoparticle dispersed functionally modified beta cyclodextrin exhibited enhanced thermal stability compared to the functionalised β-CD.     

Synthesis and characterization of the new pyrochlore Bi1.5Sb1.5−xNbxMnO7 solid solution

The solid solution with formula Bi_1.5Sb_1.5−xNb_xMnO₇ has been synthesized using the ceramic method at 1000 °C. This solid solution was crystallized in the pyrohlore structure in cubic lattice with Fd-3 m space group. The cell parameter increases linearly with increase in the niobium concentration. The magnetic susceptibility measurements achieved between 4 and 300 K show a paramagnetic behaviour with an effective moment 5.84 μ_β for Bi_1.5Sb_1.5MnO₇ compound (x = 0) and 5.61 μ_B for Bi_1.5Nb_1.5MnO₇ compound (x = 1.5) indicating “ + 2” oxidation state for manganese ion. The electric conductivity measured using the complex impedance spectroscopy method put in evidence an increase of the electric conductivity with the temperature, and the antimony compound is slightly more conductor than the niobium compound; results indicate electronic conductivity with semi-conducting behaviour.     

Numerical simulation of the continuous operation of a tribo-aero-electrostatic separator for mixed granular solids

Numerical simulation has proved to be a powerful tool in the research and development of new electrostatic processes. In a previous paper, the authors have introduced a simple mathematical model for simulating the outcome of a novel tribo-aero-electrostatic separation process for binary mixtures of granular materials. The mathematical model assumed that the probability of a granule to be separated can be expressed as a function of the number of impacts with granules belonging to the other class of materials. The process is characterized by the fact that the charging of the granules is produced in a fluidized bed device, in the presence of an electric field. The aim of the present paper is to simulate the continuous operation of such a device at various feed rates. The evolution in time of the mass of granules collected at the electrodes has been computed for various compositions of the granular mixture. The effect of the walls was taken into account. The computed results were in good agreement with the experiments. They demonstrate that open-loop continuous operation of the separator is possible for a range of feed-rates that depends on the composition of the materials to be separated.     

Electron states,effective masses and transverse effective charge of InAs quantum dots

The electron energy levels, direct energy band gaps, electron and hole effective masses as well as the transverse effective charge of InAs spherically shaped quantum dots have been studied as a function of the quantum dot radius considered as varying from 1 to 10 nm. The direct energy band-gap as well as the electron and heavy hole effective masses decrease non-linearly with increasing the quantum dot radius. Nevertheless, the transverse effective charge is found to increase with increasing the quantum dot radius. It is concluded that the quantum confinement has a strong influence on all the studied physical quantities for quantum dot radius below 6 nm. The results of the present contribution show that more opportunities can be offered to tailor desired optoelectronic properties surpassing those presented by bulk InAs materials.     

Chiral Separation of 4-Iminoflavan Derivatives on Several Polysaccharide-Based Chiral Stationary Phases by HPLC

The HPLC enantiomeric separation of seven 4-iminoflavans was successfully accomplished in the normal phase mode using six polysaccharide-based chiral stationary phases namely, Chiralcel^®OD-H, Chiralcel^®OD, Chiralcel^®OJ, Chiralpak^®AD, Chiralpak^®IA and Chiralpak^®IB under normal and polar organic phase modes. The resolution depended on nature and concentration of alcoholic modifier. The results demonstrate clearly that the chromatographic system based on the coated and immobilized type Chiralpak^®IB and Chiralcel^®OD-H CSPs provide a powerful analytical tool for enantiomeric separation of all the 4-iminoflavans used in this study.