Helium dilution for ram accelerator operation

Experimental detonation characteristics (detonability limits and detonation velocities) of methane-oxygen-helium mixtures at initial pressures of up to 5 MPa were measured in a 90 mm caliber, 11.7 m long (130 calibers) smooth-bore detonation tube. Stoichiometric as well as fuel-rich mixtures were investigated in order to provide performance data for ram accelerator applications. The experimental results were used to adjust and validate calculations of the Chapman-Jouguet detonation characteristics by means of a thermochemical code based on various real gas equations of state. On the basis of the detonation velocity data, a series of intermolecular parameters involved in the thermochemical code was determined. Furthermore, the investigation enabled to determine of the upper detonable area of these dense ternary mixtures under the present experimental conditions. Received 25 February 2000 / Accepted 24 January 2001     

Convenient Method for the Preparation of Heterodialkyl‐H‐phosphonates from Diphenyl‐H‐phosphonate

A procedure for the introduction of two different alkyl chains (myristyl, oleyl and phytanyl) leading to heterodialkyl‐H‐phosphonates is reported, based on two successive transesterification reactions of commercially available diphenyl‐H‐phosphonate with the corresponding alcohols.     

New terms in binaries phase diagram

Some cases and reactions in binary isobaric phase diagram presenting variation of temperature and composition have no names; we propose to attribute names for some cases and reaction that we identified. The names of the invariant reactions are issued from Greek language as eutectic but concerning the curves of separation between domains, they have a Latin origin. We have respected these choices.     

Polymorphic and Thermodynamic Study of Indomethacin

Indomethacin is known to exhibit polymorphism. As a consequence the various forms have different solubilities and may have different bioavailabilities. This study has been carried out with the following techniques: calorimetry, differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray diffraction and thermomicroscopy. Two solid forms have been prepared and studied: their melting temperature and their enthalpy of fusion are determined. The heat capacity and heat content were measured vs. the temperature for these two solid forms and for the liquid phase. This is fundamental for the determination of the stable form. More of this, with a view to study phase diagrams of indomethacin with another compound (solvent or not), the knowledge of the C _p of the various forms is necessary for calculation of the liquidus curve, this allows to minimize the number of experiments. This revised version was published online in August 2006 with corrections to the Cover Date.     

Acquisition et traitement de donnees microcalorimetriques

This paper describes a Basic language program for use with an APPLE II microcomputer on line in a microcalorimetric set. Automatic area measurements, permanent control of physical parameters of manipulations and calculations lead to enthalpy values defined with an accuracy better than one per cent.     

Importance of heat capacity determination in homogeneous nucleation: application to progesterone

Progesterone is known to exist under different crystallographic forms in the solid state. The thermodynamic stable form (I), melts at 129.2 °C (402.35 K) under atmospheric pressure. After melting and cooling a metastable form (II) can be obtained which melts at 122 °C (395.15 K). This uncommon behaviour can be explained with the theory of nucleation, only if heat capacity of the different forms are known.     

An investigation of the thermal behavior of heterobimetallic species containing copper(II) and tetracyanopalladate(II)

Synthesis, characterization and thermal behavior of four compounds that have the general formula [Cu{Pd(CN)₄}(L)_x]_n, in which en=1,2-diaminoethane and pn=1,3-diaminopropane (L=en, x=1 (I); L=pn, x=1 (II); L=en, x=2 (III); L=pn, x=2 (IV)) were described in this work. The complexes were studied by elemental analysis, infrared spectroscopy (IR), differential thermal analysis (DTA) and thermogravimetry (TG) and the residues of the thermal decomposition were characterized by X-ray powder diffraction and found as a mixture of CuO and PdO. The stoichiometry of the compounds was established via thermogravimetric and elemental analyses and their structures were proposed as coordination polymers based on their infrared spectra. The following thermal stability sequence was found: IV<I=II<III.     

Etude du systeme binaire selenium-tellure

Integral heats of mixing have been measured at 738 K by drop calorimetry. Liquidus and solidus temperaturesT ₉ and recrystallisation temperatures have been measured by thermal analysis.

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Zusammenfassung Integrale Mischungswärmen wurden bei 738 K kalorimetrisch gemessen. Liquidus-, Solidus- and Rekristallisationstemperaturen sowieT ₉ wurden thermoanalytisch bestimmt.

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738 . , _g .