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The influence of Al(2)O(3) nanoparticles on the curing of an epoxy thermoset based on diglycidyl ether of bisphenol A was investigated using temperature-modulated differential scanning calorimetry (TMDSC) and rheology. Diethylene triamine was used as a hardener. TMDSC not only allows for a systematic study of the kinetics of cure but simultaneously gives access to the evolution of the specific heat capacities of the thermosets. The technique thus provides insight into the glass transition behaviour of the nanocomposites and hence makes it possible to shed some light on the interaction between the nanoparticles and the polymer matrix. The Al(2)O(3) fillers are shown to accelerate the growth of macromolecules upon isothermal curing. Several mechanisms which possibly could be responsible for the acceleration are described. As a result of the faster network growth chemical vitrification occurs at earlier times in the filled thermosets and the specific reaction heat decreases with increasing nanoparticle concentration. Rheologic measurements of the zero-shear viscosity confirm the faster growth of the macromolecules in the presence of the nanoparticles.

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In 40 patients with normal liver function total hepatic blood flow (HBF) was determined by the indocyanine-green clearance method simultaneously with haemodynamic parameters, including cardiac output by means of the noninvasive thoracic electrical bioimpedance method. Furthermore, the influence of halothane, enflurane or isoflurane on HBF and the interaction with haemodynamic parameters was studied. HBF and the cardiocirculatory parameters were determined under normal conditions (waking state) and the 40 patients were then divided into 4 groups (each n = 10). After standardised induction of anaesthesia (0.3 mg/kg etomidate and 2 micrograms/kg fentanyl) and tracheal intubation (1.5 mg/kg suxamethonium chloride) an inhalation anaesthesia in O2/air under control of normal end tidal carbon dioxide concentration was performed by intermittent positive pressure ventilation. Anaesthesia was maintained in the 4 groups either with 1 MAC halothane, 1 MAC enflurane, 1 MAC isoflurane or 1.3 MAC isoflurane. The measurements were repeated at a steady of the desired end expiratory concentration of the respective volatile anaesthetic. All three anaesthetics produced a significant and comparable decrease of cardiac output and arterial blood pressure. Differences between halothane, enflurane and isoflurane in respect of haemodynamic parameters were only minimal. Contrariwise, marked differences could be seen in the effects of the anaesthetics on HBF. In the presence of halothane and enflurane HBF dropped to 58% and 56% resp. of the control value, whereas during isoflurane anaesthesia HBF remained unchanged. Furthermore, only during halothane anaesthesia a significant correlation between arterial blood pressure and HBF could be observed indicating a loss of autoregulation of the hepatic blood flow.

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