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The solid-liquid phase behaviour of the system {(1-x) mol L-limonene + x mol D-limonene} has been studied by means of adiabatic calorimetry. The system is polymorphic and the thermodynamic behaviour of mixtures of D- and L-limonen...
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The solid-liquid phase behaviour of the system {(1-x) mol L-limonene + x mol D-limonene} has been studied by means of adiabatic calorimetry. The system is polymorphic and the thermodynamic behaviour of mixtures of D- and L-limonene during temperature cycles has been investigated. The thermodynamic behaviour can be looked upon as the superposition of two phase diagrams. One phase diagram depicts the equilibrium between liquid and stable solid, and the other the equilibrium between liquid and metastable solid. The stable case corresponds to the formation of a racemic compound. The metastable case corresponds to a series of mixed crystals. [References: 21]
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The low-temperature heat capacity of Dy2O3 center dot 2ZrO(2) and Ho2O3 center dot 2ZrO(2) has been determined by adiabatic calorimetry in the temperature range 10-340 K. The results have been used to calculate the entropy, enthal...
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The low-temperature heat capacity of Dy2O3 center dot 2ZrO(2) and Ho2O3 center dot 2ZrO(2) has been determined by adiabatic calorimetry in the temperature range 10-340 K. The results have been used to calculate the entropy, enthalpy increment, and reduced Gibbs energy of the zirconates without taking into account their low-temperature magnetic transformations.
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The heat capacity of yttrium orthotantalate has been determined as a function of temperature by adiabatic calorimetry in the temperature range 0-340 K. Smoothed heat capacity data have been used to calculate the thermodynamic func...
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The heat capacity of yttrium orthotantalate has been determined as a function of temperature by adiabatic calorimetry in the temperature range 0-340 K. Smoothed heat capacity data have been used to calculate the thermodynamic functions of yttrium orthotantalate.
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We have employed high-resolution calorimetric techniques in order to investigate the unresolved issue of the existence of a nematic phase for the liquid crystal dodecylcyanobiphenyl. Various heating and cooling runs were performed...
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We have employed high-resolution calorimetric techniques in order to investigate the unresolved issue of the existence of a nematic phase for the liquid crystal dodecylcyanobiphenyl. Various heating and cooling runs were performed on dodecylcyanobiphenyl samples of different origin and their analysis did not reveal any signature of a nematic phase. The calorimetric results are presented in detail and they are additionally supported by optical polarising microscopy observations.
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Calorimetric data can provide a basis for determining potential hazards in reactions, storage, and transportation of process chemicals. This work provides calorimetric data for the thermal decompo- sition behavior in air of 50 wt....
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Calorimetric data can provide a basis for determining potential hazards in reactions, storage, and transportation of process chemicals. This work provides calorimetric data for the thermal decompo- sition behavior in air of 50 wt./100 hydroxylamine/water (HA), both with and without added stabiliz- ers, which was measured in closed cells with an automatic pressure tracking adiabatic calorimeter (APTAC).
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The heat capacity of natural mineral, pyromorphite Pb5(PO 4)3Cl, was measured over the temperature range 4.2-320 K using low-temperature adiabatic calorimetry. An anomalous temperature dependence of heat capacity with a maximum at...
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The heat capacity of natural mineral, pyromorphite Pb5(PO 4)3Cl, was measured over the temperature range 4.2-320 K using low-temperature adiabatic calorimetry. An anomalous temperature dependence of heat capacity with a maximum at 273.24 K was observed between 250 and 290 K. The heat capacity, entropy, enthalpy, and reduced thermodynamic potential of pyromorphite were calculated and tabulated over the temperature range 5-320 K. The standard thermodynamic functions of the mineral are C p298.15o = 414.98 ± 0.44 J/(mol K), S 298.15o = 585.31 ± 0.99 J/(mol K), H 298.15o - H 0o = 80.90 ± 0.08 kJ/mol, and Φ 298.15o = 313.97 ± 0.84 J/(mol K).
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The heat capacities of cerium and lanthanum zirconate (Ce_2Zr_2O_7 and La_2Zr_2O_7) were measured from 4 to 4000 K by adiabatic calorimetry. The derived thermodynamic functions, H°, S° and {G°-H°(o)}/T were calculated. The sta...
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The heat capacities of cerium and lanthanum zirconate (Ce_2Zr_2O_7 and La_2Zr_2O_7) were measured from 4 to 4000 K by adiabatic calorimetry. The derived thermodynamic functions, H°, S° and {G°-H°(o)}/T were calculated. The standard molar entropies at 298.15K were determined as 230.21±0.46 J/mol. K and 238.53±0.48J/mol. K. Enthalpy increments relative to 298.15 K were measured by drop calorimery from 500 to 900 K. From These data the thermodynamic functions, including the enthalpy and Gibbs free energy of formation of the Two compounds were derived for temperatures up to 1000k.
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The crystallisation of 1-carvone was followed under adiabatic conditions. In separate experiments, the enthalpy curves of the sample and the vessel were measured with the sample in the liquid state and with the sample in the solid...
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The crystallisation of 1-carvone was followed under adiabatic conditions. In separate experiments, the enthalpy curves of the sample and the vessel were measured with the sample in the liquid state and with the sample in the solid state. From these data the growth speed as a function of temperature is calculated. [References: 3]
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Recent work performed at DERA (now QinetiQ) has shown how accelerating rate calorimetry (ARC) can be used to obtain time to maximum rate curves using larger samples of energetic materials. The use of larger samples reduces the inf...
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Recent work performed at DERA (now QinetiQ) has shown how accelerating rate calorimetry (ARC) can be used to obtain time to maximum rate curves using larger samples of energetic materials. The use of larger samples reduces the influence of thermal inertia, permitting experimental data to be gathered at temperatures closer to those likely to be encountered during manufacture, transportation or storage of an explosive device. However, in many cases, extrapolation of the time to maximum rate curve will still be necessary. Because of its low detection limit compared to the ARC, heat conduction calorimetry can be used to obtain data points at, or below, the region where an explosive system might exceed its temperature of no return and undergo a thermal explosion. Paired ARC and heat conduction calorimetry experiments have been conducted on some energetic material samples to explore this possibility further. Examples of where both agreement and disagreement are found between the two techniques are reported and the significance of these discussed. Ways in which combining ARC and heat conduction calorimetry experiments can enhance, complement and validate the results obtained from each technique are examined. (C) 2003 Elsevier Science B.V. All rights reserved. [References: 7]
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The low-temperature heat capacities of berberine hydrochloride were measured over the temperature range from 78 to 350 K by an adiabatic calorimeter. The thermodynamic functions H_T - H_(298.15) and S_T - S_(298.15) were derived f...
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The low-temperature heat capacities of berberine hydrochloride were measured over the temperature range from 78 to 350 K by an adiabatic calorimeter. The thermodynamic functions H_T - H_(298.15) and S_T - S_(298.15) were derived from the heat capacity data. The results showed that the structure of berberine hydrochloride was stable over the temperature range from 78 to 350 K. The thermal stability of the compound was further tested by DSC and TG measurements. The results were in agreement with those obtained from adiabatic calorimetry experiment. The standard molar enthalpy of formation in the crystalline state of berberine hydrochloride was obtained from the standard molar energies of combustion in oxygen at T = 298.15 K, measured by a rotating-bomb combustion calorimeter.
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