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(based on the known enthalpy of water/ice transition) can be determined. In this article, we present a new isothermal heat flow calorimeter suitable for investigation of large-volume specimens typical for highly inhomogeneous systems

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Abstract  

The aim of the action of COST 531 taking into account the eleven elements Ag,Au,Bi,Cu,In,Pb,Sb,Sn,Zr (solder), Ni and Pd (substrate) is the database assessment for candidates of lead free soldering process. We studied four of them forming the ternary systems Ag-Au-Bi and Ag-Au-Sb. First we determined experimentally their phase diagrams, then the integral enthalpy of mixing of the liquid phase along different sections at different temperatures by using a SETARAM device heat flow calorimeter of Tian-Calvet type. All these data were used to optimize the thermodynamic parameters of the different phases of both ternary systems.

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, the description of a thermostated combined calorimetric–manometric apparatus is given, this specific experimental device comprising a Setaram C80 differential heat flow calorimeter coupled with a home-built manometric system can work for pressures from

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Modulated differential scanning calorimetry (MDSC) uses an abbreviated Fourier transformation ≼r the data analysis and separation of the reversing component of the heat flow and temperature signals. In this paper a simple spread-sheet analysis will be presented that can be used to better understand and explore the effects observed in MDSC and their link to actual changes in the instrument and sample. The analysis assumes that instrument lags and other kinetic effects are either avoided or corrected for.

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Modulated differential scanning calorimetry in the glass transition region

VI. Model calculations based on poly(ethylene terephthalate)

Journal of Thermal Analysis and Calorimetry
Authors: B. Wunderlich and I. Okazaki

Abstract  

Temperature-modulated calorimetry (TMC) allows the experimental evaluation of the kinetic parameters of the glass transition from quasi-isothermal experiments. In this paper, model calculations based on experimental data are presented for the total and reversing apparent heat capacities on heating and cooling through the glass transition region as a function of heating rate and modulation frequency for the modulated differential scanning calorimeter (MDSC). Amorphous poly(ethylene terephthalate) (PET) is used as the example polymer and a simple first-order kinetics is fitted to the data. The total heat flow carries the hysteresis information (enthalpy relaxation, thermal history) and indications of changes in modulation frequency due to the glass transition. The reversing heat flow permits the assessment of the first and higher harmonics of the apparent heat capacities. The computations are carried out by numerical integrations with up to 5000 steps. Comparisons of the calculations with experiments are possible. As one moves further from equilibrium, i.e. the liquid state, cooperative kinetics must be used to match model and experiment.

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Modulated differential scanning calorimetry in the glass transition region

II. The mathematical treatment of the kinetics of the glass transition

Journal of Thermal Analysis and Calorimetry
Authors: B. Wunderlich, A. Boller, I. Okazaki, and S. Kreitmeier

Temperature-modulated differential scanning calorimetry (TMDSC) is based on heat flow and represents a linear system for the measurement of heat capacity. As long as the measurements are carried out close to steady state and only a negligible temperature gradient exists within the sample, quantitative data can be gathered as a function of modulation frequency. Applied to the glass transition, such measurements permit the determination the kinetic parameters of the material. Based on either the hole theory of liquids or irreversible thermodynamics, the necessary equations are derived to describe the apparent heat capacity as a function of frequency.

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An isoperibolic heat flow calorimeter is described for the determination of heat production rates during the tethered flight of small insects such as flies, honeybees or hornets. The insects are fixed with their thoraces to one arm of a low-friction carousel. A sensor counts the number of revolutions per time and determines the speed of flight. Wing sound is monitored by a microphone with an audio recorder, so that wing beat frequencies and hence locomotor activities can be determined. Different illumination means are incorporated to guarantee the illumination levels necessary for flight.

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Thermal phenomena at the hydration of calcium sulphate hemihydrate (CaSO4·0.5H2O) are investigated in the paper. Time development of hydration heat of β-calcium sulphate hemihydrate prepared from flue gas desulphurization (FGD) gypsum is determined using two different types of calorimeter, namely the differential calorimeter DIK 04 and the isothermal heat flow calorimeter KC 01, and the differences in measured data analyzed. Then, the effects of plasticizers and hydrophobizers on the hydration process of analyzed gypsum mixtures are studied.

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This study furnished results on the enzymatic detection of phenolic compounds by means of a miniaturized heat-flow calorimeter (IC-calorimeter). Two enzymes were used: tyrosinase and peroxidase. Additionally to the investigations with the IC-calorimeter, measurements were carried out with a classical reaction calorimeter (LKB 8700) for the very slow reactions with tyrosinase. By way of contrast, the reactions with peroxidase are fast and seem more suitable for sensor application. The detection limit for the investigated phenolic compounds is of the order of 1 mmol l−1 .

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Control of bioprocesses requires reliable and robust on- or in-line monitoring tools providing real-time information on process dynamics. Heat generation related to metabolic activity of living systems is currently gaining importance in bioprocess industry due to its non-invasive and essentially instantaneous characteristics. This study deals with monitoring and control of pure aerobic fed-batch cultures of three Crabtree-negative yeast strains, Kluyveromyces marxianus, Candida utilis and Pichia pastoris, based on in-line measured, metabolic heat flow signals. A high resolution biocalorimeter (BioRC1) was developed from a standard bench-scale heat flow calorimeter (RC1). The BioRC1 was equipped with in-line (dielectric spectroscopy, pH probe and dissolved oxygen probe) and at-line (exit gas analyser) sensors to characterise the growth behaviour of the yeast cells. Both metabolic heat flow and biomass profiles exhibited similar behaviour proving the significance of employing heat flow signal as a key-parameter for the system under investigation. A simple estimator for biomass concentration and specific growth rate was formulated based on heat flow values. In order to evaluate the potential of calorimetry as a reliable and powerful process monitoring tool, the robustness, reliability as well as the broad applicability of the developed estimators was assessed through comparison with off-line measurement techniques and showed promising results for general applicability with a wide range of bioprocesses.

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