共查询到2条相似文献,搜索用时 0 毫秒
1.
Maya Bar-Dolev Yeliz Celik J. S. Wettlaufer Peter L. Davies Ido Braslavsky 《Journal of the Royal Society Interface》2012,9(77):3249-3259
Antifreeze proteins (AFPs) evolved in many organisms, allowing them to survive in cold climates by controlling ice crystal growth. The specific interactions of AFPs with ice determine their potential applications in agriculture, food preservation and medicine. AFPs control the shapes of ice crystals in a manner characteristic of the particular AFP type. Moderately active AFPs cause the formation of elongated bipyramidal crystals, often with seemingly defined facets, while hyperactive AFPs produce more varied crystal shapes. These different morphologies are generally considered to be growth shapes. In a series of bright light and fluorescent microscopy observations of ice crystals in solutions containing different AFPs, we show that crystal shaping also occurs during melting. In particular, the characteristic ice shapes observed in solutions of most hyperactive AFPs are formed during melting. We relate these findings to the affinities of the hyperactive AFPs for the basal plane of ice. Our results demonstrate the relation between basal plane affinity and hyperactivity and show a clear difference in the ice-shaping mechanisms of most moderate and hyperactive AFPs. This study provides key aspects associated with the identification of hyperactive AFPs. 相似文献
2.
Basavaraj Angadi V. M. Jali M. T. Lagare N. S. Kini A. M. Umarji 《Bulletin of Materials Science》2002,25(3):191-196
The low thermal expansion ceramic system, Ca1-xSr{x}Zr4P6O24, for the compositions with x = 0, 0.25, 0.50, 0.75 and 1 was synthesized by solid-state reaction. The sintering characteristics
were ascertained by bulk density measurements. The fracture surface microstructure examined by scanning electron microscopy
showed the average grain size of 2.47 μm for all the compositions. The thermal expansion data for these ceramic systems over
the temperature range 25–800°C is reported. The sinterability of various solid solutions and the hysteresis in dilatometric
behaviour are shown to be related to the crystallographic thermal expansion anisotropy. A steady increase in the amount of
porosity and critical grain size with increase in x is suggested to explain the observed decrease in the hysteresis. 相似文献