Análise de vinte genótipos de sorgo (Sorghum bicolor (L.) Moench), de portes médio e alto, pertencentes ao ensaio nacional Analysis of twenty genotypes of sorghum (Sorghum bicolor (L.) Moench) of medium and high status from the national assay

Os vinte genótipos de sorgo estudados foram cultivados e ensilados aos 104 dias de idade, em estádio de grão pastoso, em silos de laboratório de "PVC", com 10 cm de diâmetro e 40 cm de comprimento. Os silos foram abertos aos 150 dias após a ensilagem. O delineamento adotado foi o inteiramente casualizado. No material estudado (verde e ensilado), foram determinados os valores de fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), hemicelulose, celulose, lignina, cinzas totais, matéria seca (MS), proteína bruta (PB) e carboidratos solúveis em álcool, que apresentaram valores médios de 61,8; 34,2; 27,5; 29,5; 4,6; 3,8; 25,7; 7,7; e 8,5% no material original e de 55,9; 32,6; 23,3; 28,5; 3,9; 4,0; 27,5; 8,6; e 0,8% nas silagens, respectivamente. Os valores de hemicelulose e celulose diminuíram com a ensilagem, indicando que tais frações forneceram carboidratos adicionais para a fermentação. Os teores de carboidratos solúveis do material original foram altos para todos os genótipos, sendo intensamente consumidos no silo, garantindo bom padrão de fermentação. Nas silagens, os valores de pH foram, em média, 3,5 e os teores de nitrogênio amoniacal, inferiores a 8%, em todos os genótipos. As silagens estudadas apresentaram-se iguais para todas as características pesquisadas.<br>The twenty studied genotypes of sorghum were cultivated and ensiled at 104 days of age, at dough grain phase, using "PVC" lab silos, presenting 10 cm diameter and 40 cm length. The silos were opened at 150 days after ensiling. A completely randomized experimental design was used. In the studied material (fresh and ensiled) the values of neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, cellulose, lignin, total ash, dry matter (DM), crude protein (CP) and alcool soluble carbohydrates were determined. The mean values were of 61.8, 34.2, 27.5, 29.5, 4.6, 3.8, 25.7, 7.7 and 8.5% in the fresh matter and of 55.9, 32.6, 23.3, 28.5, 3.9, 4.0, 27.5, 8.6 and 0.8% in the silages, respectively. The hemicellulose and cellulose values decreased with ensiling, indicating that those fractions contributed with additional carbohydrates for the fermentation. The soluble carbohydrates values of the fresh material were higher for all genotypes, being intensively used in the silo, supplying a good fermentation standard. In the silages, the pH values were 3.5 and ammoniacal nitrogen (N-NH3) contents were inferior to 8.0% in all genotypes. The studied silages showed similar for all evaluating characteristics

Glass transition under confinement-what can be learned from calorimetry

Calorimetry is an effective analytical tool to characterize the glass transition and phase transitions under confinement. Calorimetry offers a broad dynamic range regarding heating and cooling rates, including isothermal and temperature modulated operation. Today 12 orders of magnitude in scanning rate can be covered by combining different types of calorimeters. The broad dynamic range, comparable to dielectric spectroscopy, is especially of interest for the study of kinetically controlled processes like crystallization or glass transition. Accuracy of calorimetric measurements is not very high. Commonly it does not reach 0.1% and often accuracy is only a few percent. Nevertheless, calorimetry can reach high sensitivity and reproducibility. Both are of particular interest for the study of confined systems. Low addenda heat capacity chip calorimeters are capable to measure the step in heat capacity at the glass transition in nanometer thin films. The good reproducibility is used for the study of glass forming materials confined by nanometer sized structures, like porous glasses, semicrystalline structures, nanocomposites, phase separated block copolymers, etc. Calorimetry allows also for the frequency dependent measurement of complex heat capacity in a frequency range covering several orders of magnitude. Here I exclusively consider calorimetry and its application to glass transition in confined materials. In most cases calorimetry reveals only a weak dependence of the glass transition temperature on confinement as long as the confining dimensions are above 10 nm. Why these findings contradict many other studies applying other techniques to similar systems is still an unsolved problem of glass transition in confinement