Transporte de Materia con Reducción de Volumen en el Interior de Sólidos Paralelepípedos

Se describe un modelo matemático tridimensional transitorio aplicado al fenómeno de difusión de agua en el interior de sólidos paralelepípedos. Se utilizó el método de los volúmenes finitos considerando propiedades térmica y mecánicas constantes, equilibrio en la superficie y reducción de volumen del material. El modelo fue utilizado para estudiar el proceso de secado de un ladrillo de cerámica. Se muestran los resultados de la cinética de secado y la distribución del contenido de humedad en varios planos, para un determinado tiempo y para dos coeficientes de encogimiento. Los resultados muestran que el fenómeno de reducción de volumen afecta considerablemente la tasa de secado del sólido, así como la distribución del contenido de humedad en el interior del mismo. Se encuentra también que los gradientes más altos del contenido de humedad se sitúan en las proximidades del vértice del sólido, en cualquier instante de tiempo. El conocimiento de las diferencias de humedad y la cinética de secado permiten optimizar este proceso y aumentar la calidad del producto final

Processamento da casca de mandioca na alimentação de ovinos: desempenho, características de carcaça, morfologia ruminal e eficiência econômica Processing of cassava peel in sheep feeding: performance, carcass characteristics, ruminal morphology and economic efficiency

Avaliou-se o efeito de diferentes formas de processamento da casca de mandioca na alimentação sobre o desempenho e as características de carcaça, a morfologia ruminal e a viabilidade técnico-econômica da criação de ovinos. Foram utilizados 20 ovinos machos da raça Santa Inês, desmamados, com peso inicial de 19,02±0,21 kg e 90 dias de vida. O delineamento experimental foi inteiramente casualizado com cinco repetições por dieta. Durante o período experimental de 84 dias, incluindo 14 dias de adaptação, os animais foram mantidos em sistema de semiconfinamento em pastagem de Brachiaria decumbens. Foram avaliadas quatro formas de processamento da casca de mandioca: desidratada triturada em peneira de 12 ou de 5 mm; úmida triturada e ensilada; e úmida triturada e hidrolisada com 0,5% de cal virgem (óxido de cálcio - CaO). O peso médio ao abate foi 30,72±1,46 kg. Não houve influência do tipo de processamento da casca sobre as características de desempenho analisadas, as características quantitativas de carcaça e a morfologia ruminal, sendo influenciado somente o rendimento de paleta. A casca de mandioca hidrolisada foi a que promoveu melhor eficiência econômica. Os tipos de processamento da casca de mandioca não alteram o desempenho, as características de carcaça, os rendimentos de corte e a morfologia ruminal dos ovinos Santa Inês.<br>The objective of this trial was to evaluate the effect of different forms of processing of cassava peel in sheep feeding on performance traits, carcass, morphology and rumen and economic technical feasibility. Twenty non-castrated male Santa Ines lambs of 19.02±0.21 kg of initial body weight and 90 days of age at the beginning of the study were used in this trial. The design was completely randomized design with five replications per treatment. During the experimental period of 84 days, including 14 days of adaptation, animals were kept in semi-confinement on Brachiaria decumbens. Four forms of cassava peel processing were evaluated: dried cassava peel ground through 12-mm sieve; dried cassava peel ground through 5-mm sieve; ground and ensiled cassava peel, and wet, ground hydrolyzed with 0.5% lime (calcium oxide - CaO). The average weight at slaughter was 30.72±1.46 kg. There was no influence of the type of processing on the performance variables analyzed, quantitative carcass characteristics or ruminal morphology; only the values of width and leg yield palette were influenced. Hydrolyzed cassava peel showed the best economic efficiency between treatments. The different methods of processing cassava peel do not affect performance, carcass characteristics, yield cuts or rumen morphology of Santa Ines sheep

The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications

Background: The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications. Methods: ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery. Results: The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784. Conclusions: This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance. © 2018 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.Medical Research Council of South Africa gran