Solid Freeform Fabrication of Functional Silicon Nitride Ceramics by Laminated Object Manufacturing 1

The processing of silicon nitride (Si3N4) structural ceramics by Laminated Object Manufacturing (LOM) using ceramic tape preforms was investigated. The key processing stages involved green shape formation (which used the LOM process), followed by the burnout of all organics, and final densification by pressureless sintering. Two material systems were considered. These were a) monolithic Si3N4 and b) a preceramic polymer infiltrated Si3N4. The raw materials for the process were tape preforms of Si3N4, which were fabricated by standard tape casting techniques. Mechanical property data obtained for the LOM processed Si3N4 showed high strength and fracture toughness values. The room temperature and high temperature (1260 o C) flexural strengths were in the range of 700-900 MPa and 360-400 MPa, respectively. The fracture toughness averaged from 5.5-7.5 MPa.m1/2. These strength and fracture toughness values are comparable to those reported for conventionally prepared Si3N4 ceramics. Thus, this research demonstrated that the LOM technique is a viable method for preparing functional Si3N4 ceramics with good physical and mechanical properties.Mechanical Engineerin

O significado da filosofia da humanitude, no contexto dos cuidados de enfermagem à pessoa dependente e vulnerável

Revisão sistemática seguindo a metodologia dos sete passos do Cochrane Handbook, formulando a seguinte questão: Qual o significado do conceito integrador de humanitude, no contexto dos complexos e delicados cuidados que os enfermeiros prestam, a pessoas doentes vulneráveis e dependentes? No processo de resposta à questão, seguindo a metodologia sistemática, com base numa estratégia de pesquisa refinada e exaustiva a bases de dados relevantes, não se obtiveram respostas aos descritores relacionados com cuidados de enfermagem, que intersectem o conceito humanitude. No entanto, através de motores de busca e contacto com investigadores nacionais e estrangeiros, foi possível recolher um pequeno acervo de documentos, que revelam a pertinência da questão de investigação e indicam a existência de trabalho avançado na aplicação da filosofia da humanitude aos cuidados de enfermagem. O trabalho mais relevante é o método de Gineste e Marescotti, no cuidado a doentes dependentes e vulneráveis, desde 1975. Com este estudo de revisão, observa-se uma nova oportunidade de investigação, através da implementação e monitorização do método, com uma população de pessoas doentes dependentes, em Portugal

Spatial characteristics of observed precipitation fields: A catalog of summer storms in Arizona, Volume 1

Eight years of summer raingage observations are analyzed for a dense, 93 gage, network operated by the U. S. Department of Agriculture, Agricultural Research Service, in their 150 sq km Walnut Gulch catchment near Tucson, Arizona. Storms are defined by the total depths collected at each raingage during the noon to noon period for which there was depth recorded at any of the gages. For each of the resulting 428 storms, the 93 gage depths are interpolated onto a dense grid and the resulting random field is anlyzed. Presented are: storm depth isohyets at 2 mm contour intervals, first three moments of point storm depth, spatial correlation function, spatial variance function, and the spatial distribution of total rainstorm depth