The failure analyses on ZnO varistors used in high tension devices

The main purpose of this work is to evaluate the failure caused by electrical discharge on commercial ZnO varistor doped with oxide of Bi, Sb, Si, Cr, Co utilized in electric transmission systems. In order to observe the effect of electrical discharge over the microstructure and electrical properties of the varistors, two kinds of pulses were applied: long pulse (2000 ms) and short pulse (8/20 mu s). In both cases, a decrease in grain size and increase in micropores and leakage current were observed. The degraded samples present oxygen defficiency mainly in the grain boundary and phase tranformation from the bismuth oxide phase. (c) 2005 Springer Science+ Business Media, Inc.

Etude electromyographique des muscles trapezius (partie moyenne) et rhomboideus major sousmis a tension isometrique

The participation of the trapezius (middle portion) and rhomboideus major muscles submitted to an isometric tension (holding downward dumbells of 11, 15 and 19 kg) was analysed in 40 young adult male vounteers. A 2 channel TECA TE4 electromyograph connected with single coaxial needle electrodes was used. In the initial phase of the test, holding downward, generally the trapezius and rhomboideus major muscles showed activity and no activity, respectively. In the cases where activity was present during the downward positions it was reduced gradually until complete rest.

The respiratory responses of an amphibious snail Pomacea lineata (spix, 1827), to temperature and oxygen tension variations

1. 1. The respiratory responses of Pomacea lineata to short-term (or acute) exposure to temperature and oxygen tension variations were investigated in animals acclimated to 25°C. 2. 2. The respiratory rates increased with rising temperatures; this increase was sharper between 15 and 25°C than at any other temperature interval; a tendency to a plateau in the RT curve was recorded between 25 and 35°C. 3. 3. All animals survived well to 1 hr exposure to the extreme temperatures used (5 and 40°C). 4. 4. In two different experimental approaches, the animals showed ability to regulate the respiratory rate in declining oxygen tensions, at least down to 10% (70.8 mmHg) oxygen. 5. 5. After 1 hr exposure to hypoxic conditions, P. lineata exhibited the pattern of underpayment of the oxygen debt acquired. 6. 6. Six out of ten animals survived after 40 days in anoxia (100% nitrogen). © 1987.

Is coronary sinus blood oxygen tension behavior determined by myocardial oxygen tension variation during cardiac reperfusion?

The relationship between coronary sinus blood oxygen tension (CSPO 2) and myocardial oxygen tension (MPO 2) variations during cardiac ischemia and reperfusion was studied in anesthetized open-chest dogs. Oxygen tension was measured by a polarographic method. Ischemia resulted in a slightly decreased CSPO 2 and a more pronounced reduction of MPO 2. After reperfusion the CSPO 2 rose rapidly and transiently before it returned gradually to the control level. By contrast, during the recovery period, the MPO 2 increased slowly, with recovery occurring long after the peak of CSPO 2. These data suggest that during the reperfusion phase, the CSPO 2 variation is probably due to opening of the myocardial arteriovenous shunts instead of an increase of flow through the myocardial capillary bed.

The tension as perturbative parameter in string theory

The author proposes an approach to string theory where the zero-order theory is the null string. An explicit form of the propagator for the null string in the momentum space is found. Considering the tension as a perturbative parameter, the perturbative series is completely summable and the propagator of the bosonic open string with tension T is found.

Social stratification under tension in a globalized era

Includes bibliography

Sistema de estadísticas de servicio en planificación de la familia - SIDES; notas sobre su aplicación en el Programa Nacional de Planificación y Educación Sexual, Costa Rica

Incluye Bibliografía

Avaliação da reabsorção radicular após a movimentação dentária induzida com forças contínua e contínua interrompida: análise histomorfométrica em ratos

Pós-graduação em Odontologia - FOA

Avaliação da influência da força de mordida na prótese parcial removível classe I mandibular associada ao implante osseointegrado, pelo método dos elementos finitos

Pós-graduação em Odontologia - FOA

Conservação de energia em sistemas de iluminação pública e os seus efeitos na rede elétrica de distribuição

Pós-graduação em Engenharia Mecânica - FEG

Grander system: A new technology to reduce surface tension of adhesive systems in dentistry

Background. Reduced surface tension of liquids results in higher surface wetting ability and diffusivity by the substrate. Objectives. The objective of this study was to evaluate the influence of the Grander Technology in reducing the surface tension of adhesive systems. Methods. Two adhesive systems (self-etch and total-etch) were modified by physical contact with the Grander system Flexible unit to revitalize water, for 48 h. Surface tension of adhesive systems and water in normal and grander-modified conditions was measured with a goniometer. Results. The results showed a reduction of surface tension for all conditions grander-modified between 3-15%. Conclusions. Grander Technology was effective in reducing the surface tension of the Single Bond and Clearfil SE Bond adhesive systems. Clinical significance. Grander technology was employed to restructure the molecular structure of water-based adhesive systems, which can increase their wetness capacity and therefore ensure a greater diffusibility.

Regular bulk solutions and black strings from dynamical braneworlds with variable tension

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Conexão cultura: um projeto de revitalização e reestruturação da estação ferroviária de Guaratinguetá

This work presents an intervention at the Guaratinguetá Railway Station and its surroundings, including this area in the urban context, at this moment isolated of the activities and citizen attentions, offering new activities on this commercial area. The selected area finds itself in a state of neglect and forgetfulness from the urban relations. Located between the periphery of the commercial center and the Paraiba do Sul River, the correlation is tension between the advancement of shops, the railway line, and the natural barrier of the Paraiba River. On the context of these limits, the railroad and the river stand as barriers for the center expansion and the flows that connect the old part of the town with the new part, which is growing and is called “post-city river”. These barriers have relegating properties around them to isolation, despite being located in the center. The area choice and this intervention seeks to break this isolation and the barrier flow, linking areas of opposite sides to form a leak through the barrier of the railway line. The pedestrian flow is prioritized in the project, this flow will be attracted by the program offered and by the new created areas, increasing the space utilization by users and breaking the isolation of urban activities. And entering the area in the context of life of city residents. The attraction of these new flows will be through the implementation of a Cultural Center, supplying a lack of city by spaces that offer this type of activity. Its implementation aims to attract and modify the activities of these spaces and the surrounding areas, one side facing the commercial center, and another facing the river, linking this two sides at the same time that this link provides the expansion of distance traveled and known