We give a lower bound on the diffusion coefficient of a polymer chain in an entanglement network with kinematic disorder, which is obtained from an exact calculation in a modified Rubinstein–Duke lattice gas model with periodic boundary conditions. In the limit of infinite chain length we show the diffusive motion of the polymer to be slowed down by kinematic disorder by the same factor as for ...

sodium salt of n-acetyl-dl-tryptophan (at) and octanoic acid (caprylic acid ca) individually and in combination were studied as thermal stabilizer with different concentrations in heat treatment of human albumin solution. hplc protein profiles before pasteurization of albumin showed less than 1% polymer. in free stabilizer albumin solution during pasteurization visible clot was formed. but by u...

We have studied the effects of grain boundary adhesion and grain size on the ductility of thin metal films well bonded to polymer substrates, using a finite element method. It is shown that the ductility of polymer-supported metal films increases approximately linearly as the grain boundary adhesion increases, and as the grain size decreases. A rule-of-thumb estimate of the ductility of polymer...

The type of prosthetic restoration used in implant rehabilitation greatly contributes to the recovery of masticatory function as well as quality of life in patients. Frameworks for implant-supported prostheses are typically made by casting metal or milling either titanium or zirconia. Recently, nonmetal, polymer-type materials were suggested as framework materials. Polyetherketoneketone (PEKK),...

Flow instabilities occur in a variety of commercial polymer processing operations including extrusion, film blowing, fiber spinning and coating. During the extrusion of molten polymer through capillary or slit die geometries, a transition from a smooth surface to a nearly periodic ridge-like surface distortion has been observed at a critical shear rate or wall shear stress (Petrie and Denn 1976...

Regarding the importance of the prevention of hazards and adverse environmental impacts in industrial and populated areas such as southern parts of Tehran city, the response of impulsive period ground-supported tanks were assessed. Having considered the study area's soil properties, the response of ground-supported tanks was modelled. Regarding the soil properties of southern parts of Tehran, t...

A method of patterning surfaces for liquid-crystal alignment using a polarization holography exposure on a linear photopolymerizable polymer alignment layer is demonstrated. Three configurations are demonstrated which include registered planar-periodic surface boundary conditions on both surfaces true polarization gratings , planar-periodic and uniform planary surface boundary conditions, and p...

An efficient method for the synthesis of mono and bulky 1,8-dioxooctahydroxanthenes was developed by the reaction of dimedone or 1,3-cyclohexadione and aldehydes or some bisaldehydes in the presence of polyvinylpolypyrrolidone supported oxalic acid (PVPP-OXA) as a new polymeric catalyst in ethanol at room temperature. Polyvinylpolypyrrolidone supported oxalic acid was characterized by FT-IR, an...

Regarding the importance of the prevention of hazards and adverse environmental impacts in industrial and populated areas such as southern parts of Tehran city, the response of impulsive period ground-supported tanks were assessed. Having considered the study area's soil properties, the response of ground-supported tanks was modelled. Regarding the soil properties of southern parts of Tehran, t...

The methodology involves preparing polyvinyl sulfuric acid as a solid acid by simple mixing ofpolyvinyl alcohol with chlorosulfonic acid in CH2Cl2 at room temperature. The catalytic ability ofthe solid acid was investigated for the facile conversion of benzylic alcohols to the unsymmetricalethers with aliphatic alcohols in the presence of the solid acid. Results show that the solid acid isan ap...