The effect of relative humidity on tensile strength and water vapor permeability in chitosan, fish gelatin and transglutaminase edible films

Abstract Composite films of chitosan, fish gelatin and microbial transglutaminase (MTgase) were developed. Films were produced by the casting method and dried at room temperature for 30 h, conditioned for 7 days at 30 °C at a relative humidity (RH) from 11 to 90%, and characterized. Chitosan:fish gelatin films in different proportions (100:0, 75:25, 50:50) with MTgase, were subjected to tensile properties and water vapor transmission (WVT) testing. The results showed that tensile strength decreased with an increase in RH and with an increase in gelatin content. Percent of elongation also increased with increasing RH and gelatin concentration. Water vapor transmission showed an increase proportional to an increase in RH with the presence of gelatin being unfavorable for reducing WVT. Results in this work allowed studying the effect of relative humidity on tensile and water vapor properties of chitosan and fish gelatin films.

Um modelo macrodinâmico pós-keynesiano de simulação

A post-keynesian macro-dynamic model of simulation. The objective of this article is to present the structure and the simulation results of a one-sector macro-dynamic model that embeds some elements of the post-keynesian theory. The computational simulation of the model replicates some important features of capitalist dynamics as the phenomenon of cyclical growth, the long-run stability of the profit rate and functional distribution of income, the maintenance of idle-capacity in the long-run and the occurrence of a single episode of deep fall in real economic activity, which is in accordance with the rarity character of great crashes in the history of capitalism. Moreover, the simulation results show that a great reduction in inflation rate will be followed by an increase of financial fragility, increasing the like-hood of a great depression. As a policy advice derived from the simulation results, we can state that the Central Bank should never promote big reductions in inflation rate.

Torricelli, energia a vapor e o sentido tecnológico da Revolução Científica

Starting from Evangelista Torricelli's pneumatic discoveries, we try to show that the crucial discoveries in pure science associated with the Scientific Revolution, although they may not have found immediate practical applications, have markedly impelled technological progress in the medium term - contrary to the diffused notion which states that the links between science and technology during the modern period have been tenuous, at best. Torricelli's ideas have turned into one of the privileged research areas for then newborn experimental program, actively participating in a process of reformulation in scientific research's epistemological base, which have culminated in steam power productive application.