No abstract

Monotonic compressive loading and bending tests are conducted for solid polypropylene (PP) under constant or time‐varying strain‐rates and temperatures of 10, 25, 40°C. The observed compressive stress‐strain responses under constant conditions have revealed that the inelastic deformation behavior is remarkably dependent on loading rates and temperatures of normal use. The examination of such inelastic behavior has indicated that the strain‐rate effects correspond with the temperature effects based on the concept of time‐temperature equivalence. The viscoplastic constitutive theory based on overstress (VBO) has successfully reproduced the experimental responses with stress‐jumping phenomena using the equivalent time. Four‐point bending tests are performed under monotonic loading and holding for PP beams at three different temperatures. The observed deformation behavior has shown that the Bernoulli‐Euler hypothesis is valid. The VBO model and beam bending theory has generated the basic equations for PP beams, showing an analogy with the uniaxial one. In the numerical analysis, the equations are transformed into nonlinear ordinary differential equations with use of Gaussian quadrature for the spatial integrals. The comparison of numerical and experimental results has suggested some modifications for actually loaded moment taking the effect of deflection and friction into consideration. Finally, the numerical calculation has simulated the experimental time‐histories of curvatures fairly well.

The effects of neonatal asphyxia on the serotonin neuron system were examined using the immunoperoxidase method. Male mice, 2 days of age, were exposed to total asphyxia (100% C0₂) for 30 min. Mice that spontaneously survived were perfused transcardially with a fixative at 15, 30 and 60 days of age. Quantitative immunohistochemical analysis at 60 days of age demonstrated a significant decrease in the numbers of serotonin-immunoreactive cell bodies in the nucleus raphe dorsalis, the nucleus raphe pontis, the sub-pyramidal region, the total raphe system and the whole brain, while no significant reduction in the number of serotonin-immunoreactive cell bodies was observed in the caudal raphe system. Presumably degenerative changes in serotonin-immunoreactive fibers were observed in various parts of the brain of mice subjected to total asphyxia at 15 days of age, and the numbers of degenerated fibers decreased in almost all parts of the brain, the exception being the caudal portion of the brainstem, at 30 and 60 days of age. These results suggested that neonatal asphyxia induced permanent changes in the serotonin neuron system, with regional differences.

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We introduced thoracoscopic esophagectomy with extended lymphadenectomy for reduction of respiratory dysfunction and less surgical intervention in July 1995. In this study, we investigated the changes in serum interleukin-6 (IL-6) and interleukin-1 receptor antagonist (IL-1ra) levels in 8 patients (TS Group) who underwent thoracoscopic esophagectomy with extended lymphadenectomy and compared them with the changes in patients who underwent conventional thoracotomy (CT Group). The duration of the operation and intrathoracic procedure in the TS group were significantly longer than in the CT group. However, the amount of blood loss and intrathoracic blood loss of the TS group were not significantly higher than in the CT group. The number of dissected lymph nodes was not significantly larger. The serum IL-6 levels reached maximum levels 3 hours from the end of operation. In the TS group, the changes in IL-6 levels were significantly larger (p < 0.05). On the other hand, the changes in CRP levels were also significantly larger (p < 0.01). Significant correlation was observed between the duration of the intrathoracic procedure and the maximum levels of IL-6. On the other hand, serum IL-1ra levels were not significantly. At present, these results suggest that the surgical intervention of thoracoscopic esophagectomy are more larger than that of conventional thoracotomy. We think that the length of intrathoracic procedure of thoracoscopic esophagectomy may make more large surgical stress.