Search results for "melting"
showing 10 items of 238 documents
A real-time PCR assay for detection and quantification of 2-branched (1,3)-β-D–glucan producing lactic acid bacteria in cider
2010
28 p.-1 fig.-4 tab.
Recent advances on ionic liquid uses in separation techniques
2018
International audience; The molten organic salts with melting point below 100°C, commonly called ionic liquids (ILs) have found numerous uses in separation sciences due to their exceptional properties as non molecular solvents, namely, a negligible vapor pressure, a high thermal stability, and unique solvating properties due to polarity and their ionic character of molten salts. Other properties, such as viscosity, boiling point, water solubility, and electrochemical window, are adjustable playing with which anion is associated with which cation. This review focuses on recent development of the uses of ILs in separation techniques actualizing our 2008 article (same authors, J. Chromatogr. A…
A snapshot of the transition from monogenetic volcanoes to composite volcanoes: Case study on the Wulanhada Volcanic Field (northern China)
2022
The transition processes from monogenetic volcanoes to composite volcanoes are poorly understood. The Late Pleistocene to Holocene intraplate monogenetic Wulanhada Volcanic Field (WVF) in northern China provides a snapshot of such a transition. Here we present petrographic observations, mineral chemistry, bulk rock major and trace element data, thermobarometry, and a partial melting model for the WVF to evaluate the lithology and partial melting degree of the mantle source, the crystallization conditions, and pre-eruptive magmatic processes occurring within the magma plumbing system. The far-field effect of India–Eurasia collision resulted in a relatively high degree (10 %–20 %) of partial …
Melting of tantalum at high pressure determined by angle dispersive x-ray diffraction in a double-sided laser-heated diamond-anvil cell
2003
The high pressure and high temperature phase diagram of Ta has been studied in a laser-heated diamond-anvil cell (DAC) using x-ray diffraction measurements up to 52 GPa and 3800 K. The melting was observed at nine different pressures, being the melting temperature in good agreement with previous laser-heated DAC experiments, but in contradiction with several theoretical calculations and previous piston-cylinder apparatus experiments. A small slope for the melting curve of Ta is estimated (dTm/dP = 24 K/GPa at 1 bar) and a possible explanation for this behaviour is given. Finally, a P-V-T equation of states is obtained, being the temperature dependence of the thermal expansion coefficient an…
X-ray study of LB multilayers of cadmium soaps in the vicinity of the break up point
1991
Temperature dependent SAXS measurements were carried out on multilayers of two different salts, cadmium palmitate (hexadecanoate) and behenate (docosanoate). The pattern characteristic of layer structure disappears at a transition temperature well below the bulk melting point in both cases. Examination by means of optical microscopy shows that the LB films break up at a temperature close to this transition. Measurements in its vicinity demonstrate that over a certain temperature range just below the transition a second set of peaks arises in the diffraction pattern. During this transition region of about 3 °C width two d-spacings for both salts were found, suggesting the simultaneous existe…
Thermal, spectroscopic and crystallographic analysis of mannose-derived linear polyols
2018
The major diastereomer formed in the Barbier-type metal-mediated allylation of D-mannose has previously been shown to adopt a perfectly linear conformation, both in solid state and in solution, resulting in the formation of hydrogen-bonded networks and subsequent aggregation from aqueous solution upon stirring. Here, a comprehensive study of the solid state structure of both the allylated D-mannose and its racemic form has been conducted. The binary melting point diagram of the system was determined by differential scanning calorimetry analysis, and the obtained results, along with structure determination by single crystal X-ray diffraction, confirmed that allylated mannose forms a true rac…
In situ characterization of the high pressure – high temperature melting curve of platinum
2019
AbstractIn this work, the melting line of platinum has been characterized both experimentally, using synchrotron X-ray diffraction in laser-heated diamond-anvil cells, and theoretically, using ab initio simulations. In the investigated pressure and temperature range (pressure between 10 GPa and 110 GPa and temperature between 300 K and 4800 K), only the face-centered cubic phase of platinum has been observed. The melting points obtained with the two techniques are in good agreement. Furthermore, the obtained results agree and considerably extend the melting line previously obtained in large-volume devices and in one laser-heated diamond-anvil cells experiment, in which the speckle method wa…
Density variations in liquid tellurium: Roles of rings, chains and cavities
2010
Liquid tellurium has been studied by density-functional/molecular-dynamics simulations at 560, 625, 722, and 970 K and by high-energy x-ray diffraction (HEXRD) at 763 K and 973 K. The HEXRD measurements agree very well with earlier neutron-scattering data of Menelle et al. The density maximum near the melting point (722 K) reflects the competition between twofold and threefold local coordination, which results in chain formation and changed ring statistics at lower $T$, and the variation with $T$ of the volume of cavities ($26--35\text{ }\mathrm{%}$ of the total). A higher-order gradient expansion of the exchange-correlation functional is needed to describe structural details. Changes in th…
Melting curve and phase diagram of vanadium under high-pressure and high-temperature conditions
2019
Melting curve and phase diagram of vanadium under high-pressure and high-temperature conditions We report a combined experimental and theoretical study of the melting curve and the structural behavior of vanadium under extreme pressure and temperature. We performed powder x-ray-diffraction experiments up to 120 GPa and 4000 K, determining the phase boundary of the body-centered cubic-to-rhombohedral transition and melting temperatures at different pressures. Melting temperatures have also been established from the observation of temperature plateaus during laser heating, and the results from the density-functional theory calculations. Results obtained from our experiments and calculations a…
X-ray Studies of Debye Temperature of Some ABO 3 Perovskites
2002
Debye temperatures T D of some perovskite compounds are determined by X-ray diffraction. Correlation between T D determined at T=180 °C, mean square displacements of atoms, quasi-elastic coupling, and melting temperature of the perovskite compounds is analysed.