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The effect of ultra-fine precipitated calcium carbonate (PCC), with a primary particle size of 50 nm, on the fusion behavior and mechanical properties of Ca/Zn stabilized poly(vinyl chloride) PVC has been investigated. The optimum concentration of PCC was determined and, in addition, experimental design was used to examine possible synergies between PCC and two important additives in an unplasticized PVC (PVC-U) formulation: namely, the processing aid and impact modifier. Dry blends were extruded and tested by differential scanning calorimetry, tensile testing, and Charpy impact testing. The results confirm that ultra-fine PCC can give rise to large improvements in single notch impact strengths. Control values of 8 kJ/[m.sup.-2] were increased to 79 kJ/[m.sup.-2] through the addition of ultra-fine PCC. There was also found to be a significant increase in fusion levels but no effect on the tensile strength of the samples. It is concluded that PCC behaves as both a processing aid and impact modifier in PVC-U formulations, and the reasons for this are discussed. POLYM. ENG. SCI., 52:2369-2374, 2012. [C] 2012 Society of Plastics Engineers, INTRODUCTION Synthetic calcium carbonate, known as precipitated calcium carbonate (PCC), has the advantages of a very fine particle size, narrow particle size distribution, and high purity. Typical primary particle sizes [...]

[beta]-Carotene biochemistry is a fundamental process in mammalian biology. Aberrations either through malnutrition or potentially through genetic variation may lead to vitamin A deficiency, which is a substantial public health burden. In addition, understanding the genetic regulation of this process may enable bovine improvement. While many bovine QTL have been reported, few of the causative genes and mutations have been identified. We discovered a QTL for milk [beta]-carotene and subsequently identified a premature stop codon in bovine [beta]-carotene oxygenase 2 (BCO2), which also affects serum [beta]-carotene content. The BCO2 enzyme is thereby identified as a key regulator of [beta]-carotene metabolism. DOI: 10.1534/genetics.109.101741

The effect of talc on the crystallinity and mechanical properties of a series of poly(lactic acid) (PLA)/talc composites has been investigated. The composites were prepared by melt blending followed by compression molding. It was found that talc acted as a nucleating agent and increased the crystallinity of the PLA from 2% to 25%. There was significant improvement in Young's modulus of the composites with increasing talc addition and these results were found to fit the Halpin Tsai model. Thermo-mechanical tests confirmed that the combination of increased crystallinity and storage modulus leads to improvement in the heat distortion properties. POLYM. ENG. SCI., 54:64-70, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]