A method is presented for estimating relative mutation rates or relative effective population sizes, under the hypothesis of adaptively neutral allelic variation. This method was applied to seven surveys of electrophoretic variation. It was observed that electrophoretic mutation rates so obtained follow the gamma distribution and, in Drosophila, are positively correlated with the molecular weig...

High molar mass poly(N-vinylcaprolactam) (PVCa) was synthesized by free-radical bulk polymerization. Four narrowly distributed fractions of PVCa were obtained in the tetrahydrofuran/nhexane mixture. A combination of static and dynamic laser light scattering led to a scaling between the translational diffusion coefficient (D) and molar mass (M), D (cm2/s) ) 8.47 × 10Mw, with which we transferred...

HPLC and gel permeation chromatographic (GPC) characterization of complex phenol-formaldehyde resins is described. Reversed-phase HPLC fingerprints the phenolic monomers, dimers and some oligomers. The molecular masses of these phenolic compounds were determined using an ion trap mass spectrometer. GPC analyzes tetrahydrofuran-soluble phenolic polymers beyond HPLC capability. The molecular mass...

fourier transform infrared (ftir) and gel permeation chromatography (gpc) wre respectively utilized in determining the changes in isocyanate (nco) concentration and molecular weight (mw) and its distribution (mwd) in polyurethanes during their cure and postcure stages. samples, originally cured at 45°c, were taken through accelerate aging tests at various temperatures. the ftir and gpc analytic...

Fourier transform infrared (FTIR) and gel permeation chromatography (GPC) wre respectively utilized in determining the changes in isocyanate (NCO) concentration and molecular weight (MW) and its distribution (MWD) in polyurethanes during their cure and postcure stages. Samples, originally cured at 45°C, were taken through accelerate aging tests at various temperatures. The FTIR and GPC anal...

styrene polymerization through frp and atrp methods was carried out at 110oc, while in-depth studies were performed by monte carlo simulation.the changes in monomer conversion, initiator concentration, average molecular weight, and polydispersity index were computed over the course of the polymerization. as the results indicate, compared to atrp, the frp reaches higher conversion in a similar r...

SiO2/MgCl2 (ethoxide type)/TiCl4 Ziegler-Natta catalysts for use in ethylene polymerization and ethylene/1-hexene copolymerization have been prepared using silica with a supported layer of magnesium ethoxide (Mg(OEt)2) as a catalyst precursor, followed by treating with TiCl4 at different Ti/Mg molar ratios, which showed significant effects on the active centers and pore structures of the cataly...

the molecular weight distribution of 4 commercial isotactic polypropylene (ipp) samples was estimated using rheological data. the dynamic moduli data, obtained from rheological measurements in linear viscoelastic region was used for calculation of relaxation time spectrum, h(τ) and then shear relaxation modulus, g(t). finally, applying thimm kernel function and relaxation modulus data in genera...