EXPERIMENTAL VALIDATION OF A CAPPILARY TUBE SIMULATION MODEL WITH REFRIGERANT MIXTURES FLOW

This paper presents the experimental validation of a simulation model for refrigerant mixtures flow through capillary tubes. To perform such validation it was built an experimental apparatus using a blow-down process. It was carried out preliminary tests for characterization of experimental parameters: actual capillary tube diameters; relative roughness; and the heat losses in subcooling/quality control system. It was obtained almost 200 experimental points for R-407C (a zeotropic mixture) and R-410A (a near azeotropic mixture). Complete data set for each point consists of the measured pressure and temperature profiles, mass flow rate and mixture composition, as well as subcooling/quality control system inlet and outlet temperatures and heater electric power consumption for tests with two-phase flow capillary tube inlet conditions. Comparison of simulation and experimental data show a good agreement. Main deviations are connected with the delay of vaporization phenomenon occurrence, experimentally verified by the authors

The Thermodynamics of Intracellular Ice Nucleation in the Freezing of Erythrocytes,"

A theoretical model describing the thermodynamics of intracellular ice nucleation is developed for red blood cells as a model biomaterial. Analytical expressions based on current theories of ice nucleation by both homogeneous and heterogeneous nucleation processes are coupled with a thermodynamic model for the loss of intracellular water during freezing. Numerical solutions for both modes of nucleation identify two cooling regionshigh cooling rates and low cooling rates-separated by a sharp demarcation zone. The nucleation temperature for high cooling rates is approximately 20°K higher than the nucleation temperature for low cooling rates and is essentially independent of cooling rate in each region. The nucleation temperatures for heterogeneous nucleation are approximately 30°K higher than the nucleation temperatures for homogeneous nucleation in the two regions. For the case of heterogeneous nucleation, it is possible to increase the nucleation temperature by packing of catalysts via the concentration polarization effect. If the cell suspension is allowed to supercool before nucleation occurs in the extracellular medium, the sharp transition from low cooling rates to high cooling rates for heterogeneous nucleation shifts to much lower cooling rates. The dependence of the transition cooling rate on the degree of supercooling has been established for a typical freezing situation

Terapia cognitiva : aplicações de uma técnica para qualidade de vida e saúde

Esta pesquisa teve por objetivo geral aplicar e avaliar uma técnica específica de terapia cognitiva - organizada em 12 sessões grupais e denominada Tomada de Decisão e Qualidade de Vida -, destinada a promover saúde e incrementar qualidade de vida. No total, participaram 18 servidores de uma instituição pública de ensino superior. Nas etapas de admissão e de encerramento, aplicaram-se : Questionário de Qualidade de Vida, Inventário Beck de Ansiedade e Inventário Beck de Depressão. Foram identificadas melhoras significativas nos domínios físico, psicológico, meio ambiente, geral e saúde, relacionados à qualidade de vida. Não se verificaram alterações significantes nos escores de ansiedade (p=0,26). Em contrapartida, os escores de depressão indicaram melhora (p=0,02). Os resultados sugerem que a técnica pode ser empregada para promover saúde e qualidade de vida.In this study we implemented and assessed a specific cognitive therapy technique - Decision Making and Quality of Life, which is used to promote health and improve quality of life. Eighteen employees from a higher education institution participated in the study, which was organized into 12 group sessions. At the admission and concluding phases, we asked participants to complete the World Health Organization Quality of Life - Bref Questionnaire, the Beck Anxiety Inventory and the Beck Depression Inventory. Results showed significant improvement in five of the domains that measure quality of life: physical, psychological, environmental, general, and health. There were no significant changes (p=0.26) in anxiety scores. In contrast, the depression scores got significantly better (p=0.02). The results suggest that the proposed technique is conducive to health promotion and quality of life