Search results for "Scanning"
showing 10 items of 1808 documents
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…
Preparation and characterization of gels with garnet structure: A3B2C3O12, using ‘non-classical’ solvents
1992
Abstract Synthesis and characterization of some crystalline garnets by sol-gel techniques is described. The effects of emthanol, dimethyl sulfoxide (DMSO), CH2Cl2 and toluene solvents on gelation of TEOS are considered. Multicomponent gel formation in systems with stoichiometries 3CaO·Cr2O3·3SiO2 and 3CaO·Al2O2 was studied using DMSO, a polar solvent, and toluene, an apolar solvent. The dried gel was thermally treated and the powder was characterized by X-ray diffraction, differential thermal analysis/thermogravimetric analysis and scanning electron microscopy.
Development and characterization of co-loaded curcumin/triazole-halloysite systems and evaluation of their potential anticancer activity.
2014
Abstract Positively charged halloysite nanotubes functionalized with triazolium salts (f-HNT) were employed as a carrier for curcumin molecules delivery. The synthesis of these f-HNT new materials is described. Their interaction with curcumin was evaluated by means dynamic light scattering (DLS) and UV–vis spectroscopy in comparison with pristine unmodified HNT (p-HNT). The curcumin load into HNT was estimated by thermogravimetric analysis (TGA) measurements, while the morphology was investigated by scanning electron microscopy (SEM) techniques. Release of curcumin from f-HNT, at three different pH values, by means of UV–vis spectroscopy was also studied. Furthermore, different cancer cell …
Thermal and X-ray powder diffraction studies of aliphatic polyester dendrimers
2004
The syntheses and thermal and X-ray powder diffraction analyses of three sets of aliphatic polyester dendrimers based on 2,2-bis(hydroxymethyl)propionic acid as a repeating unit and 2,2-dimethyl-1,3-propanediol, 1,5-pentanediol, and 1,1,1-tris(hydroxymethyl)ethane as core molecules are reported. These dendritic polyesters were prepared in high yields with the divergent method. The thermal properties of these biodendrimers were evaluated with thermogravimetric analysis and differential scanning calorimetry. The thermal decomposition of the compounds occurred around 250 °C for the hydroxyl-ended dendrimers and around 150 °C for the acetonide-protected dendrimers. In addition, the crystallinit…
Structure and performance properties of environmentally-friendly biocomposites based on poly(ɛ-caprolactone) modified with copper slag and shale dril…
2018
The potential application of two types of industrial wastes, drill cuttings (DC) and copper slag (CS), as silica-rich modifiers of poly(ɛ-caprolactone) (PCL) was investigated. Chemical structure and physical properties of DC and CS fillers were characterized using X-ray diffractometer, X-ray fluorescence spectroscopy, particle size and density measurements. PCL/DC and PCL/CS composites with a variable content of filler (5 to 50 parts by weight) were prepared by melt compounding in an internal mixer. It was observed that lower particle size of DC filler enhanced processing of biocomposites comparing to CS filler. Smaller particles of DC filler and thus the higher specific surface area, enabl…
Synthesis, thermal properties and X-ray structural study of weak C–H⋯OC hydrogen bonding in aliphatic polyester dendrimers
2004
Dendritic polyester compounds based on polyol with three, four and six reactive hydroxy groups as a molecular core, chloroacetyl chloride (or bromoacetyl bromide) and sodium metal enolate were prepared by a simple two-step synthetic procedure. The compounds were characterised by using the NMR and MS techniques, and the thermal properties were measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The structures of the crystalline compounds were determined by X-ray single crystal diffraction. Detailed analysis of the structures showed that the self-complementarity of the molecules together with a multitude of weak C-H⋯O=C hydrogen bonding results in crystal…
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…
MCM-41 silica effect on gel polymer electrolytes based on thermoplastic polyurethane
2012
Abstract Polymer electrolytes were prepared from thermoplastic polyurethane with addition of mixture of N-ethyl(methylether)-N-methylpyrrolidinium trifluoromethanesulfonimide (PYRA12O1TFSI) ionic liquid, lithium bis(trifluoromethanesulfoneimide) salt and propylene carbonate. MCM-41 mesoporous silica was added in proportions ranging from 5 to 20 wt.% with respect to TPU. The electrolytes were characterized by thermogravimetric analysis, differential scanning calorimetry, linear voltammetry and impedance spectroscopy. The MCM-41 addition to the system was found to improve the electrochemical stability of the membranes and to reduce the gel electrolyte/metallic Li interfacial resistance. The f…