Synthesis of poly(vinyl propionate) from poly(vinyl alcohol) in nonaqueous medium using ethyl nitrate dimethyl sulfoxide as a catalyst

Poly(vinyl alcohol) (PVA) can be dissolved in a nonaqueous medium in the presence of catalytic concentration of ethyl nitrate dimethyl sulfoxide, C₂H₅ONO₂·DMSO. From the PVA solution, poly(vinyl propionate), PVPR was prepared by the homogeneous esterification of PVA with propionic acid. The ester thus formed contained some unconverted hydroxyl group. The formation of the ester was confirmed by the IR and ¹H‐NMR spectra. The molecular weight of the ester was determined by GPC and intrinsic viscosity (η) was determined by viscometric method. Glass transition temperature, T_g, was obtained from differential scanning calorimetric (DSC) analysis. Thermal stabilities of the ester were checked by thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) analysis. The efficiency of the ester as a flow improver of crude oil was also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5675–5679, 2006     

Nanostructured Zn-Fe2O3 thin film modified by Fe-TiO2 for photoelectrochemical generation of hydrogen

Nanostructured semiconductor thin films of Zn-Fe₂O₃ modified with underlying layer of Fe-TiO₂ have been synthesized and studied as photoelectrode in photoelectrochemical (PEC) cell for generation of hydrogen through water splitting. The Zn-Fe₂O₃ thin film photoelectrodes were designed for best performance by tailoring thickness of the Fe-TiO₂ film. A maximum photocurrent density of 748 μA/cm² at 0.95 V/SCE and solar to hydrogen conversion efficiency of 0.47% was observed for 0.89 μm thick modified photoelectrode in 1 M NaOH as electrolyte and under 1.5 AM solar simulator. To analyse the PEC results the films were characterized for various physical and semiconducting properties using XRD, SEM, EDX and UV–Visible spectrophotometer. Zn-Fe₂O₃ thin films modified with Fe-TiO₂ exhibited improved visible light absorption. A noticeable change in surface morphology of the modified Zn-Fe₂O₃ film was observed as compared to the pristine Zn-Fe₂O₃ film. Flatband potential values calculated from Mott–Schottky curves also supported the PEC response.     

Preclinical Anticancer Activity of DNA-based Cleavage Molecules

ABSTRACT

Deoxyribozymes (DNAzymes) are DNA residue-based molecules capable of specific cleavage of complementary mRNA. As such, they are more stable counterparts for the earlier discovered ribozymes. A handful of studies have shown the potential of DNAzymes against cancer both in cell culture and importantly in vivo models. This relatively new molecular entity may progress to clinical trials provided that more extensive testing is carried out at the preclinical stage. While a significant amount of work has gone into chemically stabilizing the molecule, delivery is one area that needs particular attention.     

Lattice Boltzmann Simulation of Two- and Three-Dimensional Incompressible Thermal Flows

This work is concerned with the application of the thermal lattice Boltzmann method (TLBM) to compute incompressible two- and three-dimensional flows in cavities. Two convection test cases, namely, the laminar flow in a differentially heated square cavity and a cubic cavity, are numerically analyzed through TLBM. The internal energy density distribution function approach with two three-dimensional particle velocity models, namely, the 15-velocity and the 19-velocity, and a two-dimensional model, namely, the nine-velocity, have been used in the present work. Computations are carried out for laminar flows in a differentially heated square cavity and a cubical cavity (Rayleigh numbers = 10³ to 10⁵). The boundary conditions used are stable and of good accuracy. To lend credibility to the thermal lattice Boltzmann model square cavity results, they are further compared with those obtained from a finite-difference-based code developed for this purpose.     

Excess Molar Volumes and Viscosities of Mixtures of Diethylene Glycol Dibutyl Ether with Dialkyl Carbonates at 298.15, 308.15, and 318.15 K

Excess molar volumes,V ^E _m, and viscosities,, were measured as a function of composition for the binary mixtures of diethylene glycol dibutyl ether+dimethyl carbonate, +diethyl carbonate, and +propylene carbonate at temperatures of 298.15, 308.15, and 318.15 K and atmospheric pressure over the whole range of mixture compositions. From the experimental results, deviations in the viscosity,ln, and excess free energies of activation of viscous flow,G*^E, were calculated. The experimental results were correlated using the Redlich–Kister equation. The experimental and calculated quantities were used to analyze the mixing behavior of the components. Furthermore, activation enthalpies,H*, and entropies,S*, of viscous flow were evaluated and their variation with concentration is discussed.     

Effect of skin or muscle incisions or the loss of blood on serum leucogenenol level

It has been found that damage to a tissue of a rabbit or a rat, such as results from a skin incision or an incision through the skin and muscles into the abdominal cavity, is followed 24 hr later by a significant increase in the concentration of leucogenenol in the animal's serum. Likewise, loss of approximately one-quarter to one-half of the blood in the circulation of rabbits or rats causes an increase 24 hr later in the animals' serum leucogenenol concentration.     

Tuberculosis of the pyriform fossa--a rare entity

Tuberculosis of the pharynx is less common than tuberculosis of the larynx. We present a rare case of tuberculosis of the pyriform fossa which clinically masqueraded as a malignancy. Our patient showed a prompt improvement in symptoms after commencing antitubercular treatment.