Search results for "melting"
showing 10 items of 238 documents
Oxadiazolyl-pyridines and perfluoroalkyl-carboxylic acids as building blocks for protic ionic liquids: crossing the thin line between ionic and hydro…
2012
A series of 18 samples has been prepared in order to obtain fluorinated materials as Protic Ionic Liquids (PILs). These were synthesized by appropriately mixing 1,2,4-oxadiazoles derivatised with two pyridines, or one pyridine and a fluorinated chain, and perfluoroalkyl-carboxylic acids, either mono- or dicarboxylic, leading to symmetric and non-symmetric materials. Many of them showed low melting points. However, the possibility of classifying the synthesized materials as PILs is discussed in terms of effective ionicity of the systems by the combination of Density Functional Theory (DFT) calculation and IR spectroscopy. The important outcome of our investigation is that the complete proton…
Influence of drying to the structure of lactitol monohydrate
1997
The purpose of this study is to find out the effect of the crystal water content on the crystal structure of lactitol monohydrate. Crystal water was removed by drying over silicagel at 40°C and by using phosphorus pentoxide as drying agent at 20°C. The amouts of water removals were identified by thermogravimetry, the melting points and the heat of fusions were calculated from the results of differential scanning calorimetry measurements and the structure of samples were identified by X-ray powder diffraction method. Over 23 w/w% of total water content could removed by gently drying until significant structural changes could be detected. The melting point of anhydrous lactitol obtained by dr…
Selective Laser Melting of Ti6Al4V: Effects of Heat Accumulation Phenomena Due to Building Orientation
2022
Titanium alloy Ti6Al4V is one of the most utilized alloys in the field of additive manufacturing due to the excellent combination of mechanical properties, density and good corrosion behavior. These characteristics make the use of this material particularly attractive for additively manufacturing components with complex geometry in sectors such as aeronautics and biomedical. Selective Laser Melting (SLM), by which a component is fabricated by selectively melting of stacked layers of powder using a laser beam, is the one of most promising additive manufacturing technologies for Ti6Al4V alloy. Although this technique offers numerous advantages, it has some critical issues related to the high …
Rubidium dimers in paraffin-coated cells
2010
Measurements were made to determine the density of rubidium dimer vapor in paraffin-coated cells. The number density of dimers and atoms in similar paraffin-coated and uncoated cells was measured by optical spectroscopy. Due to the relatively low melting point of paraffin, a limited temperature range of 43-80 deg C was explored, with the lower end corresponding to a dimer density of less than 10^7 cm^(-3). With one-minute integration time, a sensitivity to dimer number density of better than 10^6 cm^(-3) was achieved. No significant difference in dimer density was observed between the cells.
Partial melting of metabasic rocks and the generation of tonalitic–trondhjemitic–granodioritic (TTG) crust in the Archaean: Constraints from phase eq…
2020
Abstract Rocks of tonalitic–trondhjemitic–granodioritic (TTG) composition preserved in Archaean terranes represent fragments of the Earth’s earliest-formed continental crust, and are thought to have formed via partial melting of hydrated metabasalt. The geodynamic environments in which such high-grade metamorphism and anatexis may have occurred in the early Earth is strongly debated. Constraining the pressure ( P ) and temperature ( T ) conditions at which melts of appropriate composition can be derived from protoliths containing plausible mineral assemblages is central to addressing this question. Phase equilibrium modelling has been undertaken for an enriched Archaean tholeiite bulk compo…
Reworking of the Tarim Craton by underplating of mantle plume-derived magmas: Evidence from Neoproterozoic granitoids in the Kuluketage area, NW China
2011
Abstract Most Neoproterozoic granitoids in the Kuluketage area, northern Tarim Craton are characterized by strongly depleted HREE abundances and high Sr/Y and (La/Yb) N ratios, showing typical geochemical features of adakitic rocks. Zircon U–Pb dating of three adakitic plutons yielded Neoproterozoic ages (754 ± 4, 790 ± 3 and 798 ± 3 Ma). The adakitic granitoids exhibit low MgO and TiO 2 contents. Their low Cr, Co and Ni abundances, low ɛ Hf ( t ) values (−21 to −11) and high FeO T /MgO ratios (mostly 2.2–2.9) preclude the possibility of being derived from partial melts of delaminated lower crust. The relatively low ɛ Hf ( t ) values and old Hf two-stage model ages ( T DM 2 = 2 . 42 – 3 .0 …
Comparative Study of Different Methods for the Prediction of Drug–Polymer Solubility
2015
In this study, a comparison of different methods to predict drug-polymer solubility was carried out on binary systems consisting of five model drugs (paracetamol, chloramphenicol, celecoxib, indomethacin, and felodipine) and polyvinylpyrrolidone/vinyl acetate copolymers (PVP/VA) of different monomer weight ratios. The drug-polymer solubility at 25 °C was predicted using the Flory-Huggins model, from data obtained at elevated temperature using thermal analysis methods based on the recrystallization of a supersaturated amorphous solid dispersion and two variations of the melting point depression method. These predictions were compared with the solubility in the low molecular weight liquid ana…
DISORDERING MECHANISMS OF THE Cu(110) SURFACE
1994
We review recent theoretical work on the various disordering mechanisms of the Cu(110) surface. In these studies the properties of the surface, from the onset of enhanced anharmonicity in surface vibrations up to bulk melting point T M , have been studied using molecular dynamics and lattice-gas Monte Carlo methods with many-body interactions derived from the effective medium theory. Well after the onset of enhanced out-of-plane surface vibrations, clustering of surface defects is found to induce a roughening transition at T≈0.81T M , and surface premelting is found to occur at T≈0.97T M . These results suggest, that these transitions can both appear at Cu(110). The general picture of diso…
LFZ growth of (Bi, Pb)–Sr–Ca–Cu–O superconducting fibers
1991
Powder x-ray diffraction, d.c. and a.c. susceptibilities, and SEM have been used to study (Bi1−xPbx)2Sr2Ca2Cu3O10−δ fibers grown by the Laser Floating Zone method. The well-oriented, long-grained superconductor fiber properties are shown to be highly dependent on the partial pressure of oxygen in the growth atmosphere, as well as on fiber pulling rate. Slowly grown fibers contain initially the 2212 (80 K) phase; the 2223 (110 K) phase also appears upon annealing in air. Faster growth rates result in fibers that contain a mixture of the 2212 and 2201 phases and, in this case, long annealing procedures are necessary to observe the 2223 phase.
Cambrian–Ordovician magmatism of the Ikh-Mongol Arc System exemplified by the Khantaishir Magmatic Complex (Lake Zone, south–central Mongolia)
2018
Abstract The Khantaishir Magmatic Complex (KMC) (south–central Mongolia) exposes a section of a magmatic system consisting of deep crustal, ultramafic cumulates (coarse-grained Amp gabbros and hornblendites; c. 0.35–0.5 GPa) to shallower crustal levels dominated by Amp–Bt tonalites ( c. 0.1–0.2 GPa). The magmatic rocks were emplaced during most of the Cambrian ( c. 538–495 Ma) and are mostly geochemically primitive (Mg# ~ 50), Na-rich and metaluminous. The (normal-) calc-alkaline signature and characteristic trace-element enrichment in hydrous-fluid mobile large-ion lithophile elements (LILE) relative to high-field strength elements (HFSE) suggest an origin within a magmatic arc. Multiple i…