the difficult to handle and store zinc borohydride, zn(bh4)2, is stabilized by supporting it on polyvinylpyridine. this new mild, efficient, selective, and regenerable polymer supported borohydride reducing agent reduces a variety organic compounds such as, aldehydes, a-b-unsaturated carbonyl compounds, acid chlorides, epoxides, disulfides, as well as reductive acetylation of carbonyl compounds...

conclusions retrograde laparoscopic appendicectomy using single polymer clip makes easy access to operating in complicated and non-complicated appendicitis. results four patients (15.4%) were converted to open surgery; three patients in group i and one in group ii. four patients developed postoperative complications; three patients in group i and one in group ii. operative time was less in grou...

this paper describes the impact of the distance and the size of the corona ring, on the magnitude anddistribution of electrical potential across the polymer insulators. the procedure is based on finiteelement method numerical analysis and stochastic optimization algorithm of differential evolution(de). the optimal selection of corona ring has a significant impact on the control of potential and...

Dilute or semidilute solutions of nonintersecting self-avoiding walk ~SAW! polymer chains are mapped onto a fluid of ‘‘soft’’ particles interacting via an effective pair potential between their centers of mass. This mapping is achieved by inverting the pair distribution function of the centers of mass of the original polymer chains, using integral equation techniques from the theory of simple f...

We study theoretically the effect of adding polymer to the dilute lamellar phase of surfactant solutions. The polymer, assumed semidilute and in a good solvent, is taken to have a repulsive or attractive interaction with surfactant bilayers, but has no other effect on their properties. Such polymers can mediate an attractive or repulsive interaction between bilayers which we combine with pre-ex...

thin films of polymer doped with nonlinear optical organic dye, disperse red 1, at thickness of 1 to 2 micrometers, were prepared and studied. in order to induce an axial and orientational alignment of dye molecules within polymer matrix, a contact electric field poling was used. by this process the inherent inversion symmetry in the polymer matrix was eliminated to achieve the desired macrosco...

In order to prevent corrosion, aluminum nanoparticles were coated with a polyurethane polymer. The coverage of the polyurethane polymer was controlled from 0 to 100%, which changed the corrosion rate of the nanoparticles quantitatively. The surface of the polymer coating was investigated by Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM), and the corrosion resistance of...

we introduce a model for prediction the behavior of electrodes which modified withcarbon nanotubes in a polymer medium. these kinds of polymer composites aredeveloped in recent years, and experimental data for its percolation threshold isavailable. we construct a model based on percolation theory and fractal dimensionsand using experimental percolation threshold for calculating the moments of c...

Polymer modified concrete (PMC) consists of Portland cement concrete with a polymer modifier. Its advantages are proper bonding strength to substrate concrete, high tensile and flexural strength and low amount of shrinkage and permeability. Using PMC overlays can be considered as a method for preservation of damaged concrete structures due to their suitable performance and durability. In this r...