The microdomain structures and crystallization behavior of the binary blends of poly(methyl methacrylate)-b-poly(pentafluorostyrene)-b-poly(methyl methacrylate) (PMMA-PPFS-PMMA) triblock copolymer with a low molecular weight poly(vinylidene fluoride) (PVDF) were investigated by small-angle X-ray scattering (SAXS), small-angle light scattering (SALS), transmission electron microscopy (TEM), optical microscopy, and differential scanning calorimetry (DSC). A symmetric, PMMA-PPFS-PMMA triblock copolymer with a PPFS weight fraction of 33% was blended with PVDF in N,N-dimethylacetamide (DMAc). In the wide range of PVDF concentration between 10.0 and 30.0 wt%, PVDF was completely incorporated within the PMMA microdomains of PMMA-PPFS-PMMA without further phase separation on a micrometer scale. The addition of PVDF altered the phase morphology of PMMA-PPFS-PMMA from well-defined lamellar to disordered. The crystallization of PVDF significantly disturbed the domain structure of PMMA-PPFS-PMMA in the blends, resulting in a poorly-ordered morphology. PVDF displayed unique crystallization behavior as a result of the space constraints imposed by the domain structure of PMMA-PPFS-PMMA. The pre-existing microdomain structures restricted the lamellar orientation and favored a random arrangement of lamellar crystallites.
The gas (oxygen and nitrogen) transport characteristics of the IPN membranes of polyurethane/polysturene were studied. The effect of synthesis temperature, composition, and crosslink density of the IPN membranes were analyzed. Polyurethane was prepared thermally and polystyrene was prepared by photolytic polymerization methods at various temperatures. The degree of intermixing between component polymers in the IPN membrane increased with decreasing synthesis temperature from 50°C to −10°C. The PS phase Tg was shifted inwardly up to 12°C. The permeability coefficient decreased and ideal separation factor increased also with decreasing the synthesis temperature due to the increase of miscibility. The permeability coefficient of oxygen and nitrogen ranged in the 10−10 and 10−10 order of magnitude. The permeability coefficient showed the minimum value and the ideal separation factor showed the maximum value at about 40 wt% polyrethane composition. The permeability data agreed well with the simple free volume model proposed by Lee [18].
Inositol 1,4,5-triphosphate receptor type 1 (IP3R1) is a Ca 2+ release channel that responds to the second messenger IP3 and that modulates diverse cellular functions such as contraction/excitation, secretion, gene expression and cellular growth. We discovered single nucleotide polymorphisms (SNPs) within IP3R1 gene and analyzed associations between gene polymorphisms and carcass traits in Korean cattle (Hanwoo) in order to develop novel DNA markers at genomic level. Three SNPs were detected at the position of g.1428617A>G, g.1418843C>T and g.1414377C>T with 24 unrelated Hanwoo samples by direct sequencing of the PCR products. We found that genotype of g.1414377C>T SNP was associated with live weight (P<0.05) and carcass weight (P<0.01) using the general linear model of SAS package. These results suggest that polymorphism of IP3R1 gene was associated with weight-related traits in Hanwoo.
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