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Low-temperature Conditions (low-temperature + condition)
Selected AbstractsSilicone-based impact modifiers for poly(vinyl chloride), engineering resins, and blendsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2004Akira Yanagase Abstract Silicone-based impact modifiers were prepared in a previous study. The modifiers were composed of silicone/acrylic rubber cores and grafted acrylic shells. They improved the toughness of poly(vinyl chloride) (PVC) and poly(methyl methacrylate). The silicone emulsion that was used to produce the silicone-based impact modifiers was prepared via two routes: emulsion polymerization and bulk polymerization of octamethyltetracyclosiloxane. Many silicone-based impact modifiers were produced that had different silicone/acrylic rubber characteristics. Through a toughness examination of modified PVC, the best composition of the silicone-based impact modifiers was obtained, and the silicone content in the rubber composition was 25 wt %. The morphology of the silicone-based impact modifiers, determined by transmission electron microscopy, was as follows: core and second shell polymers were mainly poly(butyl acrylate), and the first shell polymer was silicone. The silicone-based impact modifiers were blended with engineering resins such as PVC, polycarbonate (PC), poly(butylene terephthalate) (PBT), and PC/PBT mixtures. The impact strength under standard conditions and after weathering test conditions for blends of the silicone-based impact modifiers were investigated with respect to two commercially available acrylic and methyl methacrylate/butadiene/styrene impact modifiers. The results showed good weatherability and good toughness under low-temperature conditions for the silicone-based impact modifiers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1112,1119, 2004 [source] Crystalline Transition from H2Ti3O7 Nanotubes to Anatase Nanocrystallines Under Low-Temperature Hydrothermal ConditionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2006Ning Wang In this paper, we first reported the crystalline transition from H2Ti3O7 nanotubes to anatase TiO2 nanocrystallines under low-temperature hydrothermal conditions (,140°C). A newly proposed mechanism for the crystalline transition from H2Ti3O7 nanotubes to anatase TiO2 nanocrystallines under low-temperature conditions is discussed in detail, which is supported by X-ray diffraction, high-resolution transmission electronic microscope, selected-area electron diffraction, and crystal structure models. [source] Structural changes, chemical composition and antioxidant activity of cherry tomato fruits (cv. Micro-Tom) stored under optimal and chilling conditionsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2009Perla Gómez Abstract BACKGROUND: Cherry tomato fruits cv. Micro-Tom, a model plant for tomato genetics, were analysed in order to determine the main structural and chemical changes under optimal and chilling storage conditions. The comparison of Micro-Tom to standard tomato cultivars will give an insight into suitability of this dwarf cultivar as a model for studying the influence of low-temperature conditions on tomato fruits. RESULTS: During chilling, fruit tissue was progressively destroyed due to the collapse of the deep layers of the pericarp. Chilling lowered the typical tomato kinetics of ripening in sugars (glucose, fructose, sucrose), organic acids (tartaric, malic, citric, ascorbic and succinic) and the antioxidants phenol and lycopene, while carotenoid synthesis seemed to be blocked. Glutathione level was elevated and the activity of ROS scavenging enzymes was altered. Essentially, Micro-Tom fruits showed a quality evolution that was similar to that described for standard tomato cultivars. CONCLUSION: The cherry tomato cultivar Micro-Tom could be used as a model for studying the influence of low temperature on biochemical and structural changes taking place during chilling injury conditions. Copyright © 2009 Society of Chemical Industry [source] AtCHIP functions as an E3 ubiquitin ligase of protein phosphatase 2A subunits and alters plant response to abscisic acid treatmentTHE PLANT JOURNAL, Issue 4 2006Jinhua Luo Summary CHIP proteins are E3 ubiquitin ligases that promote degradation of Hsp70 and Hsp90 substrate proteins through the 26S proteasome in animal systems. A CHIP-like protein in Arabidopsis, AtCHIP, also has E3 ubiquitin ligase activity and has important roles to play under conditions of abiotic stress. In an effort to study the mode of action of AtCHIP in plant cells, proteins that physically interact with it were identified. Like its animal orthologs, AtCHIP interacts with a unique class of ubiquitin-conjugating enzymes (UBC or E2) that belongs to the stress-inducible UBC4/5 class in yeast. AtCHIP also interacts with other proteins, including an A subunit of protein phosphatase 2A (PP2A). This PP2A subunit appears to be a substrate of AtCHIP, because it can be ubiquitylated by AtCHIP in vitro and because the activity of PP2A is increased in AtCHIP -overexpressing plants in the dark or under low-temperature conditions. Unlike the rcn1 mutant, that has reduced PP2A activity due to a mutation in one of the A subunit genes of PP2A, AtCHIP -overexpressing plants are more sensitive to ABA treatment. Since PP2A was previously shown to be involved in low-temperature responses in plants, the low-temperature-sensitive phenotype observed in AtCHIP -overexpressing plants might be partly due to the change in PP2A activity. These data suggest that the E3 ubiquitin ligase AtCHIP may function upstream of PP2A in stress-responsive signal transduction pathways under conditions of low temperature or in the dark. [source] | ||||||||||