Nanocomposites of cassava starch reinforced with waxy starch nanocrystals were prepared. They showed a 380% increase of the rubbery storage modulus (at 50 °C) and a 40% decrease in the water vapor permeability. X‐ray spectra show that the composite was more amorphous than the neat matrix, which was attributed to higher equilibrium water content in the composites. TGA confirmed this result and its thermal derivative suggested the formation of hydrogen bonding between glycerol and the nanocrystals. The reinforcing effect of starch nanocrystals was attributed to strong filler/matrix interactions due to the hydrogen bonding. The decrease of the permeability suggests that the nanocrystals were well dispersed, with few filler/filler interactions.
Belief change and spread have been studied in many disciplines—from psychology, sociology, economics and philosophy, to biology, computer science and statistical physics—but we still do not have a firm grasp on why some beliefs change more easily and spread faster than others. To fully capture the complex social-cognitive system that gives rise to belief dynamics, we first review insights about structural components and processes of belief dynamics studied within different disciplines. We then outline a unifying quantitative framework that enables theoretical and empirical comparisons of different belief dynamic models. This framework uses a statistical physics formalism, grounded in cognitive and social theory, as well as empirical observations. We show how this framework can be used to integrate extant knowledge and develop a more comprehensive understanding of belief dynamics. 相似文献
Growth and survival of bacteria depend on homeostasis of membrane lipids, and the capacity to adjust lipid composition to
adapt to various environmental stresses. Membrane fluidity is regulated in part by the ratio of unsaturated to saturated fatty
acids present in membrane lipids. Here, we studied the effects of high growth temperature and salinity (NaCl) stress, separately
or in combination, on fatty acids composition and de novo synthesis in two peanut-nodulating Bradyrhizobium strains (fast-growing TAL1000 and slow-growing SEMIA6144). Both strains contained the fatty acids palmitic, stearic, and
cis-vaccenic + oleic. TAL1000 also contained eicosatrienoic acid and cyclopropane fatty acid. The most striking change, in both
strains, was a decreased percentage of cis-vaccenic + oleic (≥80% for TAL1000), and an associated increase in saturated fatty acids, under high growth temperature or
combined conditions. Cyclopropane fatty acid was significantly increased in TAL1000 under the above conditions. De novo synthesis
of fatty acids was shifted to the synthesis of a higher proportion of saturated fatty acids under all tested conditions, but
to a lesser degree for SEMIA6144 compared to TAL1000. The major adaptive response of these rhizobial strains to increased
temperature and salinity was an altered degree of fatty acid unsaturation, to maintain the normal physical state of membrane
lipids. 相似文献
The relationship between the norm square of the standardized cumulative distribution and the chi-square statistic is examined using the form of the covariance matrix as well as the projection perspective. This investigation enables us to give uncorrelated components of the chi-square statistic and to provide interpretation of these components as innovations standardizing the cumulative distribution values. The norm square of the standardized difference between empirical and theoretical cumulative distributions is also examined as an objective function for parameter estimation. Its relationship to the chi-square distance enables us to discuss the large sample properties of these estimators and a difference in their properties in the cases that the distribution is evaluated at fixed and random points. 相似文献
Male goats (“Criolla Argentina” breed), castrated at 45 days of age, showed altered lipid metabolism 180 days after castration
as compared to control goats. Subcutaneous, perirenal and omental adipose tissues of castrated goats showed increases in fatty
acid synthetase, glucose-6-phosphate dehydrogenase and NADP-isocitrate dehydrogenase activities. Castration increased the
amount of total lipids and triglycerides, but did not modify the amount of cholesterol, phospholipid and protein in the three
types of adipose tissue. The incorporation of [1-14C]acetate into fatty acids of subcutaneous and perirenal adipose tissue was increased in castrated goats in relation to noncastrated
goats. Our results suggest that removal of gonadal steroids increases significantly the rate of lipogenesis in adipose tissue
of male goats. 相似文献