Flow Microcalorimetric Measurements

The integral exchange enthalpy isotherm calculated from the flow microcalorimetric measurements is shown in Fig. 12. The course of the isotherm - in case of a U-shaped adsorption excess isotherm - is determined by the composition of the interfacial phase ( ) according to the following equation[45-47] ... 

Tian-Calvet heat flow equipment (Setaram) was used for microcalorimetric measurements. Every sample was evacuated (10 Pa) overnight at 673 K before the successive introduction of small doses of the probe gas (ammonia or carbon dioxide). The equilibrium pressure relative to each adsorbed amount was measured by means of a differential pressure gauge (Datametrics). The run was stopped at a final equilibrium pressure of 133.3 Pa. The adsorption temperature was maintained at 353 K, in order to limit physisorption. After overnight outgassing at the same temperature, a second run was carried out up to 133.3 Pa. The adsorption and calorimetric isotherms were obtained from each adsorption/readsorption... 

If the immersion experiment is repeated at different solution concentrations, the enthalpy isotherm of immersion, A Hvs. Ci, is obtained. For immersion calorimetry, the presentation of the results is often more appropriate in terms of the relative enthalpy of immersion, AnH, which, for dilute solutions, is equal to the integral enthalpy of displacement A2 Hi, more generally obtained Ifom batch or flow sorption microcalorimetric measurements. The relative enthalpy of immersion is defined as the enthalpy of immersion in the solution minus the enthalpy of immersion in pure solvent 2 ... 

Studies in different laboratories have shown increased heat production in leukocytes [58,59] from hyperthyroid patients. In the former study [58] heat production was measured with a flow microcalorimeter in the whole leukocyte population In the latter investigation [59] microcalorimetric measurements were carried out in the lymphocyte population using a static ampoule calorimeter. The results showed a qualitative agreement between the two studies, although the two investigations are not comparable since the former... 

Therefore, using moisture sorption, microcalorimetric, IGC, molecular modelling and other techniques, the consequences of the particle size reduction process can be assessed. Moreover, surface energetics can be measured directly and predictions made about the nature of the surface, which ultimately could affect properties such as the flow of powders or adhesion of particles (Podczeck et al. 1996b). 

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