ESTIMATION OF BALLISTIC PARAMETERS OF GUN PROPELLANTS THROUGH CLOSED VESSEL EXPERIMENT MODELING

Closed vessels have being used for the regression of lumped ballistic parameters for decades. However, if material and energy balances are coupled with burning rate empirical correlations, several uncorrelated parameters can be estimated, which describe more accurately the thermochemical behavior of the gases generated, even if the chemical composition of the propellant is unknown (as when the propellant is aged, for instance). This research presents such approach leading to a system of differential equations which are integrated to produce a theoretical pressure profile in the vessel, highly dependent on the choice of empirical parameters. Such parameters are manipulated according to the Maximum Likelihood statistical procedure, which leads to the best set of parameters to describe the propellant

Air layering in Caryocar brasiliense: effect of substrate.

The commercial propagation of Caryocar brasiliense Cambess is hindered by several factors, including seed dormancy and low cutting survival rates. Air layering studies are needed to overcome these limitations. Previous studies have reported the influence of substrates on the rooting of air layers for different species. Therefore, the objective of this study was to evaluate the influence of substrates on air layering of Caryocar Brasiliense. An experiment was conducted with eight stock plants located at Embrapa Cerrados, Distrito Federal, Brazil, using different substrates, including Bioplant®, coconut fiber, a mixture of Bioplant® and coconut fiber in 3:1, 1:1, 1:3 proportions, rice husk biochar, vermiculite, sawdust, soil, and sand. Each treatment was replicated four times. After five months, the survival rate, callus formation, rooting percentage, root length, fresh and dry root mass, and rooting vigor were evaluated. The survival and callus formation rates in all substrates were above 95%. Bioplant® substrate provided the highest rooting percentage (77%), fresh and dry root mass (17.08g and 3.16g, respectively), while soil provided the lowest rooting percentage (17%) and fresh and dry root mass (0.1g and 0.02g, respectively). The average root length was 6.63 cm in the 1:1 mixture. Based on the evaluated characteristics, Bioplant® is the most suitable substrate for the propagation of C. brasiliense stock plants by air layering. The results suggest that air layering is a viable alternative to the vegetative propagation of Caryocar brasiliense stock plants

Chemical composition of substrates on the rooting vigor of Caryocar brasiliense air layering.

The definition of vegetative propagation protocols is important for the production of Caryocar brasiliense Cambess plants, for the formation of commercial orchards. Therefore, the objective of this study was to evaluate the substrate’s chemical characteristics influence on Caryocar brasiliense air layering. For this, a randomized block experiment with five substrates was carried out in eight plants. The following substrates were evaluated: Bioplant® commercial substrate; coconut fiber; a mixture of Bioplant® and coconut fiber in (1:1; 1:3; 3:1) proportions. After 150 days, the air layers were cut and evaluations of survival, callusing and rooting percentages, root length, dry and fresh root matter, rooting vigor and lignification were carried out. In laboratory, chemical and physical characterizations of the substrates were undertaken. The results showed that the rooting percentage varied from 40% to 77%. Rooting of Caryocar brasiliense air layers is optimized when phosphorus, calcium, magnesium and CEC in the substrate are above 3.0 mg dm-3, 7.0 cmolc dm-3, 3.5 cmolc dm-3 and 17 cmolc dm-3, respectively. Sodium and sodium saturation of the substrate must be below 1.4 cmolc dm-3 and 6%, respectively. Strong, positive and significant correlations were observed between rooting and P, Ca, Mg and CEC

Avaliação in vitro da qualidade do sêmen de reprodutores caprinos portadores da artrite encefalite caprina (CAE) através de espermograma.

Resumo: Objetivou-se com esse estudo avaliar a qualidade do sêmen de animais portadores do CAEV através de espermograma completo. Foram realizadas 17 coletas alternadas ao longo de cinco meses (março a julho de 2013), utilizando-se de 10 reprodutores caprinos, dos quais quatro da raça Anglo-nubiano e seis Saanen, com idade entre 12 e 24 meses divididos em dois grupos (jovens-negativos e adultos-positivos para CAE) com cinco animais cada, submetidos à coleta artificial de sêmen por meio de vagina artificial, modelo curto, conjugado como uma fêmea com estro induzido. À medida que o sêmen era coletado o mesmo era destinado ao Laboratório de Tecnologia de Sêmen para realização do espermograma, onde se quantificaram os seguintes parâmetros: volume (mL), concentração espermática (x109sptz/mL), motilidade individual progressiva (MIP, 0-100%), e vigor (0-5) de acordo com os critérios preconizados pelo Colégio Brasileiro de Reprodução Animal - CBRA (1998) e os valores devidamente anotados nas fichas de avaliação. O delineamento experimental foi o inteiramente casualizado, considerando os ejaculados como sendo as repetições (N=170) e os grupos (negativo e positivo) os tratamentos. Os resultados dos parâmetros reprodutivos avaliados (volume, concentração, vigor e motilidade) nos dois grupos foram expressos por meio de média e desvio padrão de cada animal e por grupo, sendo tais médias comparadas pelo Teste de T de Student a 5% de significância. Pode-se observar que entre os animais de ambos os grupos não houve diferença significativa (p < 0,05) entre eles, e todos se encontram com as características seminais, exceto o volume no grupo dos jovens negativo, dentro dos padrões do CBRA (1998). Reprodutores caprinos portadores do CAEV não têm suas características seminais interferidas, pois mesmo apresentando a doença encontram-se com sêmen fértil e dentro da normalidade, porém com chances de transmissão da doença