Effect of plasticizer on ionic transport and dielectric properties of PVA-H3PO4 proton conducting polymeric electrolytes

Solid polymer electrolytes have attracted considerable attention due to their wide variety of electrochemical device applications. The present paper is focused on the effect of plasticizer to study the structural, electrical and dielectric properties of PVA-H₃PO₄ complex polymer electrolytes. XRD results show that the crystallinity decreases due to addition of plasticizer up to particular amount of polyethylene glycol (PEG) and thereafter it increases. Consequently, there is an enhancement in the amorphicity of the samples responsible for process of ion transport. This characteristic behavior can be verified by the analysis of the differential scanning calorimetry results. FTIR spectroscopy has been used to characterize the structure of polymer and confirms the complexation of plasticizer with host polymeric matrix. Electrical and dielectric properties have been studied for different wt% of plasticizer and their variations have been observed. The addition of PEG has significantly improved the ionic conductivity. The optimum ionic conductivity value of the plasticized polymer electrolyte film of 30 wt% PEG has been achieved to be of the order of 10⁻⁴ S cm⁻¹ at room temperature and corresponding ionic transference number is 0.98. The minimum activation energy is found to be 0.25 eV for optimum conductivity condition.     

Azomesogens with methoxyethyl tail: Synthesis and characterization

Two new mesogenic homologous series are synthesized from methoxyethyl 4-(4′-hydroxyphenylazo) benzoate. In series I the phenolic -OH group is alkylated, whereas in series II it is esterified with 4-n-alkoxybenzoyl group. In series I, all the nine members synthesized exhibit only enantiotropic smectic A mesophase. In series II, all the twelve homologues exhibit enantiotropic nematic mesophase. Smectic A mesophase appears from then-decyloxy derivative as a enantiotropic phase and persists till the last n-hexadecyloxy member. The mesomorphic properties of both the series are compared with each other and also with the properties of other structurally related series to evaluate the effect of the methoxyethyl tail on mesomorphism.     

Unexpected deviation from diene behaviour of uracil amidine: towards synthesis of some pyrido[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidine derivatives

Condensation products obtained from the treatment of uracil amidine with preformed or in situ generated suitably substituted olefins unexpectedly undergo intramolecular cyclisation during silica gel chromatography to generate pyrido[2,3-d]pyrimidines. Various reaction conditions are studied and the altered nature of the uracil amidine molecule is further explored by reacting it with different suitably substituted alkenes.     

Effect of metamaterial layer on optical surface plasmon resonance sensor

In this paper an optical surface plasmon resonance (SPR) sensor with metamaterial for four and five layered structure is studied. The numerical results presented in this paper leads to a significant properties of metamaterials in sensing field. Computed results of SPR sensors using metamaterial are compared with conventional optical SPR sensors for four and five layered structure. It is seen that wider dynamic range or effective range of measurable refractive index increases when metamaterial layer is used. It is also verified that SPR sensor with metamaterial layer can dramatically enhance the resolution and reduce the reflectivity compared with conventional SPR. Validity of the magnetic field results is proved on the basis of smooth match of the fields in the different layers of the proposed optical SPR sensor.     

Analytical solution of the scalar wave equation for slightly deformed optical Bragg waveguide

Using a simple analytical method, we study the electromagnetic-wave propagation in an optical Bragg waveguide which is slightly deformed at one side. We show the results of computations in the form of dispersion curves and provide a comparison with standard circular Bragg waveguides and step-index circular waveguides. We show that the correspondence between the cutoff V values for the standard step-index fiber and the new Bragg waveguide, which is slightly flattened on one side, is quite close for the lowest mode under the weak guidance condition.     

Effect of magnetic field and radiative condensation on the Jeans instability of dusty plasma with polarization force

The Jeans instability of self-gravitating dusty plasma with polarization force is investigated considering the effects of magnetic field, dust temperature and radiative condensation. The condition of Jeans instability and expression of critical Jeans wave number are obtained which depend upon polarization force and dust temperature but these are unaffected by the presence of magnetic field. The radiative heat-loss functions also modify the Jeans condition of instability and expression of critical Jeans wave number. It is observed that the polarization force and ratio of radiative heat-loss functions have destabilizing while magnetic field and dust temperature have stabilizing influence on the growth rate of Jeans instability.     

A rapid and specific approach for direct measurement of donepezil concentration in human plasma by LC-MS/MS employing solid-phase extraction

A selective, rapid and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is described for assay of donepezil in human plasma using escitalopram as an internal standard. Chromatographic separation was achieved on a Betabasic-C(8), 5 microm, 100 x 4.6 mm column using methanol:water:formic acid (90:9.97:0.03, v/v/v) as mobile phase. Detection of donepezil and internal standard was achieved by ESI MS/MS in positive ion mode using 380.20/91.10 and 325.13/262.00 transitions, respectively. The linearity over the concentration range of 0.15-50 ng/mL for donepezil was obtained and the lower limit of quantification was 0.15 ng/mL. For each level of quality control samples, inter-day and intra-day precisions (RSD) were < or =8.92 and 10.35% and accuracy (%RE) were < or =7.33% and 9.33%, respectively. The recovery was more than 88.50% for both donepezil and internal standard by solid-phase extraction, eliminating evaporation and reconstitution steps.     

Metal–organic frameworks (MOFs) constructed from Zn/Cd-2,2′-bipyridines and polycarboxylic acids: Synthesis,characterization and microstructural studies

Metal–organic frameworks with the compositions [Zn(bpy)(bdc)(H₂O)]_n1, [Zn(bpy)(btec)_1/2(H₂O)]_n2, [Cd(bpy)(bdc)(H₂O)]_n3 and Cd(bpy)(btec)_1/2(H₂O)]_n4 (H₂bdc = 1,4-benzenedicarboxylic acid = terephthalic acid, H₄btec = 1,2,4,5-benzenetetracarboxylic acid and bpy = 2,2′-bipyridine) have been synthesized and characterized using spectroscopic and single-crystal X-ray diffraction techniques. In these complexes, Zn^II/Cd^II-2,2′-bipyridine units and carboxylate anions exists as nodes and spacers respectively. An infinite 1D zig-zag chain structure is observed for both complexes 1 and 3, whereas complexes 2 and 4 display a 3D supramolecular architecture. The complexes are found to be photoluminescent, porous and show significant thermal stability.