INTRODUCTION Photo-induced polymerization'-6 is concerned with absorption of ultraviolet radiation to produce an unstable excited species. Subsequent formation of a free radical by rearrangement, fragmentation or energy transfer, followed by attack upon a monomer, leads to polymerization. Yamamoto and Oster7 have indicated that photo-induced polymerization resembles polymerization initiated by ...

WAVE/SCAR has long been known to activate the actin-nucleating Arp2/3 complex in a Rac-dependent manner. Recent biochemical and genetic studies have revealed important roles for four WAVE-associated proteins in regulating WAVE function.

SCAR--also known as WAVE--is a key regulator of actin dynamics. Activation of SCAR enhances the nucleation of new actin filaments through the Arp2/3 complex, causing a localized increase in the rate of actin polymerization . In vivo, SCAR is held in a large regulatory complex, which includes PIR121 and Nap1 proteins, whose precise role is unclear. It was initially thought to hold SCAR inactive ...

graft polymerization of acrylic acid (aa) and ethyl methacrylate (ema) onto starch (st) were carried out in aqueous solution using ceric ammonium nitrate (can) as redox system under n2 atmosphere. the effect of ph, reaction time, temperature, concentrations of can, st, and monomers on the graft yield was investigated. monomer reactivity was in the following order: aa>ema.the kinetics of the gra...

Exfoliated poly (Chloromethyl styrene-co-styrene)-g-polyacrylonitryle/organo- modified montmorillonite [P(CMSt-co-St)-g-PAN/O-MMT] nanocomposite was synthesized through solution intercalation method by using atom transfer and nitroxide mediated radical polymerization. At first, poly (chloromethyl styrene-costyrene) copolymer was synthesized by nitroxide - mediated “living” free radical polyme...

A considerable amount of the worldwide industrial production of synthetic polymers is currently based on radical polymerization methods. The steadily increasing demand on high performance plastics and tailored polymers which serve specialized applications is driven by the development of new techniques to enable control of polymerization reactions on a molecular level. Contrary to conventional r...

Regulation of actin polymerization is essential for cell functioning. Here, we predict a novel phenomenon-the force-driven polymerization of actin filaments mediated by proteins of the formin family. Formins localize to the barbed ends of actin filaments, but, in contrast to the standard capping proteins, allow for actin polymerization in the barbed direction. First, we show that the mechanism ...

background and aims. newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. the aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. materials and methods. sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. occlusal surfaces of all teet...

the stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining ticl4 or ticl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...

The slurry polymerization of ethylene was studied by employing a (TiCl4/Mg(OEt)2/TEA) catalyst system in hexane. The effects of triethylaluminum concentration and temperature on polymer yield and polymer viscosity average molecular weight, Mv, were investigated. The maximum polymer yield was obtained at an Al/Ti molar ratio of 124. The highest yield and Mv were achieved at 60 °C. The concentrat...