Search results for "DIFFERENTIAL SCANNING CALORIMETRY"
showing 10 items of 285 documents
Impact of Si on the high-temperature oxidation of AlCr(Si)N coatings
2022
The resistance of wear protective coatings against oxidation is crucial for their use at high temperatures. Here, three nanocomposite AlCr(Si)N coatings with a fixed Al/Cr atomic ratio of 70/30 and a varying Si-content of 0 at.%, 2.5 at.% and 5 at.% were analyzed by differential scanning calorimetry, thermogravimetric analysis and X-ray in order to understand the oxidation behavior depending on their Si-content. Additionally, a partially oxidized AlCrSiN coating with 5 at.% Si on a sapphire substrate was studied across the coating thickness by depth-resolved cross-sectional X-ray nanodiffraction and scanning trans-mission electron microscopy to investigate the elemental composition, morphol…
Calorimetric study of myoglobin embedded in trehalose-water matrixes
2009
It has been suggested that in ‘dry’ protein–trehalose–water systems, water–mediated hydrogen bond network, whose strength increases by drying, anchors the protein to its surroundings. To further characterize this effect, we performed a DSC study on low-water myoglobin–trehalose systems. The denaturation temperature resulted to increase by decreasing hydration, and linearly correlated to the glass transition temperature of both the ternary protein–water–trehalose and the binary water–trehalose systems. Further measurements are being performed to investigate eventual differences among different saccharides.
Mesophase behaviour of 2,5-dibenzoyloxy-p-benzoquinone derivatives and tetrahydrobenzene tetraesters
1991
Abstract The synthesis of 2,5-dibenzoyloxy-p-benzoquinone derivatives, their products after reduction and tetraesters from tetrahydroxybenzene prepared from those products is described. Their phase behaviour was investigated by differential scanning calorimetry and polarizing microscopy and is discussed in terms of their detailed structure.
Crystal growth and phase transitions of solid solutions in [N(CH3)4]2MX4 isomorph class
1989
Abstract Homogeneous single crystals of tetramethylammonium tetrahalogenometallate solid solutions have been grown: a temperature difference growth method with thermally enforced convection was used during the material transport from an equilibrated feed material to the growing crystals. The smallest crystals were mostly studied by differential scanning calorimetry and X-ray crystallography. Some bigger crystals were available for dielectric measurements and Raman scattering. The temperature-concentration phase diagrams of solid solutions look like the temperature-pressure phase diagrams of pure tetramethylammonium salts. The progressive substitution seems equivalent to a change of the pres…
Thermal Denaturation of Pea Globulins (Pisum sativum L.)—Molecular Interactions Leading to Heat-Induced Protein Aggregation
2013
The heat-induced denaturation and aggregation of mixed pea globulins (8%, w/w) were investigated using differential scanning calorimetry (DSC), SDS-PAGE, and size-exclusion chromatography (SEC-HPLC). DSC data showed that the pea proteins denaturation temperature (T(d)) was heating-rate dependent. The T(d) value decreased by about 4 °C by lowering the heating rate from 10 to 5 °C/min. The SDS-PAGE analysis revealed that protein denaturation upon heating at 90 °C was mainly governed by noncovalent interaction. The SEC-HPLC measurements indicated that low-denatured legumin (≈350-410 kDa) and vicilin/convicilin (≈170 kDa) globulins were heat-denatured and most of their subunits reassociated int…
Study on the thermotropic properties of highly fluorinated 1,2,4-oxadiazolylpyridinium salts and their perspective applications as ionic liquid cryst…
2007
A new series of fluorinated salts, iodides and trifluoromethanesulfonates, was synthesized from perfluoroalkylated 1,2,4-oxadiazolylpyridines. Their thermotropic properties were investigated by combined temperature resolved small angle and wide angle X-ray scattering, differential scanning calorimetry and polarised optical microscopy. The UV–visible and photoluminescence properties were studied for all compounds. The results showed for two compounds the existence of an enantiotropic mesomorphic smectic liquid crystal phase. All iodides showed thermochromism phenomena suggesting prospective applications in optoelectronics.
Rapid synthesis of tin (IV) oxide nanoparticles by microwave induced thermohydrolysis
2008
Abstract Tin oxide nanopowders, with an average size of 5 nm, were prepared by microwave flash synthesis. Flash synthesis was performed in aqueous solutions of tin tetrachloride and hydrochloric acid using a microwave autoclave (RAMO system) specially designed by the authors. Energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, nitrogen adsorption isotherm analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM), were used to characterize these nanoparticles. Compared with conventional synthesis, nanopow…
Extraction–Pyrolytic Method for TiO2 Polymorphs Production
2021
The authors thank V. Kuzovkov, A. Lushchik and M. Lushchik for many useful discussions. The research was (partly) performed in the Institute of Solid State Physics, University of Latvia ISSP UL. ISSP UL as the Center of Excellence is supported through the Framework Program for European universities Union Horizon 2020, H2020-WIDESPREAD-01–2016–2017-TeamingPhase2 under Grant Agreement No. 739508, CAMART2 project.
POSS-tetraalkylammonium salts: A new class of ionic liquids
2012
A series of new polyhedral oligomeric silsesquioxane ionic liquids (POSS-ILs) based on the trimethylpropylammonium dielectric constants, which, conversely, display slight differences originating from the nature of the anions. The long alkyl-chain substituents on the POSS core infer on this series of ILs an overall hydrophobic character and solution properties comparable to those of classic cationic surfactants, resulting in an effective extractant capability of polyanions from aqueous solutions. Their solution diffusion properties, as investigated by room-temperature dynamic light scattering, solution conductivity, density, and osmometric measurements, do not provide evidence for the occurr…
Synthesis and thermal behavior of Janus dendrimers, part 1
2010
Abstract Eight Janus-type dendrimers up to the second generation were synthesized, and their thermal properties were evaluated. Compounds consist of the dendritic bisMPA based polyester moieties, and either 3,4-dihexyloxybenzoic acid or 3,4-dihexadecyloxybenzoic acid moieties, attached to opposite sides of the pentaerythritol core. The structures of the molecules were verified with 1 H NMR, 13 C NMR, ESI TOF mass spectrometry and elemental analysis. The thermal stability was evaluated by thermogravimetric analysis, displaying onset decomposition temperatures ( T d ) ranging from 241 to 308 °C. Phase transitions were studied by differential scanning calorimetry. Based on the performed studie…