Preparation and characterizations of PVAc/P(VdF-HFP)-based polymer blend electrolytes

A novel group of polymer blend electrolytes based on the mixture of poly(vinyl acetate) (PVAc), poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), and the lithium salt (LiClO₄) are prepared by solvent casting technique. Ionic conductivity of the polymer blend electrolytes has been investigated by varying the PVAc and PVdF-HFP content in the polymer matrix. The maximum ionic conductivity has been obtained as 0.527 × 10⁻⁴ Scm⁻¹ at 303 K for PVAc/PVdF-HFP ((25/75) wt.%)/LiClO₄ (8 wt.%). The complex formations ascertained from XRD and FTIR spectroscopic techniques and the thermal behavior of the prepared samples has been performed by DSC analysis. The surface morphology and the surface roughness are studied using SEM and AFM scanning techniques respectively.     

Bright and dark solitons in a quasi-1D Bose-Einstein condensates modelled by 1D Gross-Pitaevskii equation with time-dependent parameters

We investigate the exact bright and dark solitary wave solutions of an effective 1D Bose-Einstein condensate (BEC) by assuming that the interaction energy is much less than the kinetic energy in the transverse direction. In particular, following the earlier works in the literature Pérez-García et al. (2004) [50], Serkin et al. (2007) [51], Gurses (2007) [52] and Kundu (2009) [53], we point out that the effective 1D equation resulting from the Gross-Pitaevskii (GP) equation can be transformed into the standard soliton (bright/dark) possessing, completely integrable 1D nonlinear Schrödinger (NLS) equation by effecting a change of variables of the coordinates and the wave function. We consider both confining and expulsive harmonic trap potentials separately and treat the atomic scattering length, gain/loss term and trap frequency as the experimental control parameters by modulating them as a function of time. In the case when the trap frequency is kept constant, we show the existence of different kinds of soliton solutions, such as the periodic oscillating solitons, collapse and revival of condensate, snake-like solitons, stable solitons, soliton growth and decay and formation of two-soliton bound state, as the atomic scattering length and gain/loss term are varied. However, when the trap frequency is also modulated, we show the phenomena of collapse and revival of two-soliton like bound state formation of the condensate for double modulated periodic potential and bright and dark solitons for step-wise modulated potentials.     

Alternating copolymerisations of dioxaphospholane and dioxaphosphorinane with γ-butyrolactone and ethylene oxide

Alternating copolymers containing phosphorus were prepared from 2-phenyl-1,3,2-dioxaphospholane, 2-phenyl-4-oxo-5,6-benzo-1,3,2-dioxaphosphorinane with ethylene oxide and γ-butyrolactone. The polymerisations took place without added catalyst. The copolymers were characterised by i.r. and NMR spectroscopy, viscosity measurements and phosphorus estimation. Key intermediates responsible for initiation and propagation of the copolymerisations were isolated and the mechanism of copolymerisation is discussed.     

Chemical diversity and anti-proliferative activity of marine algae

The chemical diversity of three macroalgae (Ulva reticulata, Sargassum wightii, Gracilaria sp) were determined using the GC-MS method with principal component analysis (PCA) and their potential efficacy against human pathogens and cervical carcinoma cells evaluated using MTT bioassay method. Our results showed that >30 metabolites were detected in three seaweeds, among these, steroids and fatty acids are the most dominant chemical group that highly contributes to discriminate this species. The PCA of GC-MS mass spectral variables showed a clear discrimination between three different species based on the phytochemical diversity of seaweeds. The extracts of U. reticulata exhibited anti-microbial activity with Pseudomonas aeruginosa (6.00?mm) and showed potential anti-proliferative activity against the HeLa cells (IC₅₀ 37?µmol/L) at concentration 1–50?µM treatment. Results of this study concluded that PCA analysis of mass spectral variables could be utilized as a reliable tool for species discrimination and chemotaxonomic classification of seaweeds.     

Characterisation of semiconducting V2O5–Bi2O3–TeO2 glasses through ultrasonic measurements

Tellurite containing vanadate (50−x)V₂O₅–xBi₂O₃–50TeO₂ glasses with different bismuth (x=0, 5, 10, 15, 20 and 25 wt%) contents have been prepared by rapid quenching method. Ultrasonic velocities (both longitudinal and shear) and attenuation (for longitudinal waves only) measurements have been made using a transducer operated at the fundamental frequency of 5 MHz in the temperature range from 150 to 480 K. The elastic moduli, Debye temperature, and Poisson’s ratio have been obtained both as a function of temperature and Bi₂O₃ content. The room temperature study on ultrasonic velocities, attenuation, elastic moduli, Poisson’s ratio, Debye temperature and glass transition temperature show the absence of any anomalies with addition of Bi₂O₃ content. The observed results confirm that the addition of Bi₂O₃ modifier changes the rigid formula character of TeO₂ to a matrix of regular TeO₃ and ionic behaviour bonds (NBOs). A monotonic decrease in velocities and elastic moduli, and an increase in attenuation and acoustic loss as a function of temperature in all the glass samples reveal the loose packing structure, which is attributed to the instability of TeO₄ trigonal bipyramid units in the network as temperature increases. It is also inferred that the glasses with low Bi₂O₃ content are more stable than with high Bi₂O₃ content.     

Dynamic pre-strain and inertia effects on the fracture of metals

A combined experimental and theoretical study is described which examines the influence of strain-rate and dynamic pre-strain on the ductile fracture of thin cylinders. The thin-cylinder configuration is particularly important in this case because it allows inertia terms to be directly incorporated into the theory of plastic instability. A series of quasi-static and dynamic tests is conducted on three materials with differing degrees of strain-rate sensitivity and strain-hardening. The experimental observation that fracture is inhibited at high strain-rates is in accord with the theory when inertia can no longer be considered insignificant. It is also shown that dynamic pre-strain has little or no effect on the flow stress or the strain at fracture in materials which-are essentially strain-rate insensitive, but does reduce the fracture strain in the strain-rate sensitive materials.     

Efficient Protocol for Synthesis of Pyrazolo[3,4-a]acridines

A new class of pyrazolo[3,4-a]acridines have been prepared. The synthon acridones were obtained in very good yield by a one-pot reaction of 2-amino-5-chloro or nitro substituted benzophenones with 1,3-cyclic diketones in the presence of freshly prepared Eaton’s reagent without solvent, using Friedländer synthesis. The intermediates were reacted with ethylformate followed by hydrazine hydrate to afford pyrazolo[3,4-a]acridines. All of the compounds were purified by recrystallization only, and no chromatographic workup was required. The structures of the synthesized compounds were deduced by spectroscopic techniques, including single-crystal x-ray diffraction.