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Abstract  

A heat conduction microcalorimeter with a sensitivity of 103 V mW-1 and a vessel of 3 cm3 has been designed. The device is equipped with an automatic dosimeter, an original system for injection in titration experiments, and a PC for control, data recording and data analysis. The software allows the determination of (i) overall heat effects, (ii) thermokinetics, and (iii) changes in enthalpy and equilibrium constants in titration experiments.

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Abstract  

A novel microcalorimeter based on a miniature liquid-in-glass thermometer is described. Heat is transduced into an optical, rather than electrical, signal, facilitating a future array format. The instrument performs batch analysis (drop mixing) with a 2 μL sample volume. Energy changes of 4 μJ produced by a dilution of sulfuric acid are resolvable. The effect of evaporation, and measures taken to limit it, are discussed.

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Journal of Thermal Analysis and Calorimetry
Authors: Benigno Barbés, Ricardo Páramo, Francisco Sobrón, Eduardo Blanco, and Carlos Casanova

performed our measurements with the steady-state coaxial cylinders method, using a Setaram C80D microcalorimeter, equipped with calorimetric vessels suitable for thermal conductivities of liquids, also developed by Setaram. This method has the drawback that

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Summary Isothermal titration microcalorimeters are submerged in an ambience at constant temperature and, this is the reason why there should not be variations in the baseline; but the experimental measures show that, in some cases, it is produced a jump in the baseline after the liquid injection. In this paper, it is studied the origin of this variation of the baseline in order to avoid it, if it is possible, or correct it and thus, to determine with the minimum error the amounts of energy or power developed in the energetic process that is being studied. The experimental results that are shown support the hypothesis that states that the cause of the baseline jump in an isothermal microcalorimeter is the variation of the thermal coupling between the content of the mixture cell and the axis of the stirrer, which is coupled, at the same time, with an area with a temperature slightly lower (in this case) than the thermostat temperature. This jump is independent from the dissipation and it always has the same sign. The magnitude of the baseline jump is variable and it mainly depends on the volume that the liquid content in a cell reaches and the placement of the stirrer within the cell, that can be changed in the handling process.

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A second generation twin double microcalorimeter

Measurements of sorption isotherms, heats of sorption and sorption kinetics

Journal of Thermal Analysis and Calorimetry
Authors: I. Wadsö and L. Wadsö

Abstract  

A calorimetric method for the study of solid-vapor interactions is described. In one calorimetric chamber a vapor evaporates; in a second calorimetric chamber the vapor is absorbed by a sample. The two chambers are connected by a tube and form part of a double twin microcalorimeter. As vapor is sorbed by the sample the vapor pressure in the sorption chamber will increase from a low value to near saturation. The flow rate of the vapor is governed by diffusion through the tube between the vessels. From the thermal power measured in the vaporization calorimeter it is possible to evaluate the sorption isotherm, and using information from both calorimeters the heat of sorption may be calculated as a function of equilibrium vapor pressure. By conducting experiments with different sized samples it is also possible to study the kinetics of the sorption process. The paper describes some recent improvements of the technique and gives examples of its use.

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Abstract  

The signal processing of the experimental output produced by simultaneous injection of two liquids in a flow microcalorimeter allows, besides the determination of the mixture energy, to obtain information about the mixture thermokinetics. Starting from this information, a model of space-time behaviour of the mixture dissipation is proposed. The simulations carried out explain that an increase of the injection flow produces an increase in the dissipation length which could be located out of the detection zone.

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Abstract  

A high-resolution energy-dispersive X-ray spectrometer (EDS) based on cryogenic microcalorimeter X-ray detectors has been developed for use in X-ray microanalysis. With an energy resolution of 3 eV at 1.5 keV, count rate of 500 s–1, and an effective collection area of 5 mm2 (using polycapillary X-ray optics), the microcalorimeter EDS combines many of the favorable qualities of commercially-available wavelength dispersive spectrometers (WDS) and semiconductor EDS. After describing the spectrometer system, we present several applications of microcalorimeter EDS to important microanalysis problems.

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Abstract  

This work discusses thermal behavior of Ni/MH battery with experimental methods. The present work not only provides a new way to get more exactly parameters and thermal model, but also concentrates on thermal behavior in discharging period. With heat generation rate gained by experiments with microcalorimeter, heat transport equations are set up and solved. The solutions are compared with experiment results and used to understand the reactions inside the battery. Experiments with microcalorimeter provide more reliable data to create precise thermal model.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: A. Hoover, M. Bacrania, N. Hoteling, P. Karpius, M. Rabin, C. Rudy, D. Vo, J. Beall, D. Bennett, W. Doriese, G. Hilton, R. Horansky, K. Irwin, J. Ullom, and L. Vale

Abstract  

Microcalorimeter detectors provide superior energy resolution for the detection of X-rays and gamma-rays. The technology utilizes a cryogenic transition-edge sensor (TES) coupled to a tin bulk absorber. We are working on fabrication methods for the production of arrays with many sensors. In this paper, we present data collected with an array of microcalorimeters using as many as 26 sensor elements simultaneously. Advances in sensor design have extended the useful dynamic range to photon energies up to ∼200 keV, while providing resolution performance in the 80–90 eV FWHM range, significantly better than planar high-purity germanium. These sensor arrays have applications in the measurement of nuclear materials. We present data collected from 153Gd, a highly-enriched uranium sample, and a plutonium isotopic standard source. We also demonstrate clean separation of the 235U 185.715 keV peak from the ubiquitous 226Ra 186.211 keV background peak interference.

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Journal of Thermal Analysis and Calorimetry
Authors: V. García-Cuello, J. Moreno-Pirajan, L. Giraldo-Gutiérrez, K. Sapag, and G. Zgrablich

Abstract  

This work shows the results obtained to determine the noise in the baseline of a specially designed Tian Calvet-Type adsorption microcalorimeter. The results show that noise levels vary from 0.5 to 10 μV, which were evaluated varying the electrical work and the micro calorimeter surrounding temperature. Relationships can be seen between the variables employed in the observation of stability, temperature, potency levels and generated noise.

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