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Abstract  

Selenite was boiled in KCl solutions of different concentrations at the respective boiling temperatures and atmospheric pressure. The products were subjected to X-ray diffraction analysis, qualitative infrared analysis, differential thermal analysis and microscopic examination. The product obtained in 1.0 M KCl solution was the -form of calcium sulphate hemihydrate (-CaSO4·0.5H2O). In more concentrated KCl solution (1.5, 2.0, 2.5, 3.0, 3.5 or 4.0 M), the -form of calcium sulphate hemihydrate (-CaSO4·0.5H2O) was formed, and a reaction took place between KCl and CaSO4, which gave a double salt: potassium pentacalcium sulphate monohydrate (K2SO4·5CaSO4·H2O).

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Abstract  

MgO was incorporated into montmorillonite (MMT) though the controlled formation of Mg(OH)2 followed by calcination. The evidence for Mg2+ in MMT before calcination was concluded from TG curves where two different temperature ranges for Mg(OH)2 dehydroxylation suggested that the location of Mg2+ at its internal and external surfaces. FTIR by diffuse reflectance technique of calcined sample showed a typical MgO band. XRD indicated a decrease in structural order and no collapse of clay structure. The organic compounds adsorption to MMT modified with MgO as suggested by increased degradation temperatures occurred at internal and external clay surfaces besides in an area formed probably by MgO and MMT layers.

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Abstract  

Ammonium uranate was precipitated from uranyl nitrate solution using gaseous ammonia, then filtered, washed with demineralized water and dried. The influence of pH and ammonia flow rate on their composition and structure were examined by X-ray diffraction analysis, making use of additional information obtained from infrared analysis.

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Abstract  

The decomposition of AU, UO3, and U3O8 has been studied at different heating rates and calcining temperatures at atmospheric pressure with pure carbon monoxide, in the temperature range of 350 to 1000°C. X-ray powder patterns and infrared analysis of samples revealed that the final products depend upon the nature of the precursor and its thermal treatment.

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Abstract  

The synthesis of hydroxylammonium uranyl acetate is described. The identity of the synthesized compound was confirmed by chemical and infrared analysis. The intermediates and final products of the thermal decomposition were identified by means of thermogravimetric analysis, differential thermal analysis and X-ray diffraction. The thermal decomposition of hydroxylammonium uranyl acetate involves several steps. Two of them are due to decomposition of this compound to UO2 via UO2(CH3COO)2, and the third to the partial oxidation of UO2 to UO3 and the formation of U2O8 in the solid state at higher temperature.

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Abstract  

This work focuses on the “3 + 1” mixed ligands of 99mTc labeled Gabapentin as α2δ receptor imaging agents in the brain. Gabapentin 1-(aminomethyl)cyclohexanacetic acid as monodentate and two tridentates: tridentate A; 3-(2-imino-thiozolidin-4-one)-quinozoline-4-(3H)-one and tridentate B; N-(4-chlorophenyl)-2-imino-2H-chromene-3-Carbothioamide which were synthesized and characterized by infrared analysis (IR), 1H nuclear magnetic resonance (NMR), and mass spectrum. 99mTc-complexes were prepared by the “3 + 1” mixed ligand approach. The labeling conditions were optimized and the complexes was extracted by chloroform and purified by high performance liquid chromatography. 99mTc-complexs were lipophilic and stable for at least 8–12 h at room temperature. The biodistribution of the 99mTc-complexes was evaluated in mice. The brain uptake was 4.5% and 3.5% ID/g (percentage of the injected dose per gram) at 5 min, and the retention was 1.5% and 1.7% ID/g at 120 min for 99mTc-complex A and 99mTc-complex B, respectively.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Villetti, J. Crespo, M. Soldi, A. Pires, R. Borsali, and V. Soldi

Abstract  

The thermal degradation of sodium hyaluronate, xanthan and methylcellulose was evaluated by thermogravimetric and infrared analysis. Kinetic parameters such as activation energy and pre-exponential factor were determined considering the Ozawa and Freeman–Carroll methods. The results suggest changes in the degradation mechanism with the fraction of mass loss for both the studied polysaccharides. The activation energy values determined by the Freeman–Carroll method are higher than those obtained by the Ozawa method under the same conditions, probably because in the first method a first order reaction was assumed and the thermal history effects were eliminated since only one TG curve was used to determine the kinetic parameters. Low thermal stability was observed for polyanions e.g. sodium hyaluronate (Na-Hy) and xanthan(XT) in comparison with methylcellulose (MC) which is a neutral polysaccharide. By infrared spectroscopy, it was observed that at low temperatures there occured only the scission of the exocyclic groups for both polysaccharides and that the scission of strong links in the backbone occurred at high temperatures, in agreement with the kinetic parameters determined for the degradation reaction.

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Abstract

The influences of nanosized CaCO3 on the thermal and optical properties embedded in poly(methyl methacrylate) (PMMA) and polystyrene (PS) were investigated. Calcium carbonate nanoparticles were synthesized by in situ deposition technique, and its nano size (32–35 nm) was confirmed by scanning electron microscope (SEM) and X-ray studies. Nanocomposites samples of PMMA/CaCO3 and PS/CaCO3 were prepared with different filler loading (0–4 wt%) of CaCO3 nanoparticles by solution mixing technique. The Fourier transform infrared analysis confirmed that CaCO3 nanoparticles were present in the polymers matrices. The morphology and elemental composition of nanocomposites were evaluated by SEM and energy dispersive X-ray spectroscopy. The thermal properties of nanocomposites were characterized by differential scanning calorimetric, thermogravimetric, and differential thermogravimetry analysis, and the results indicate that the incorporation of CaCO3 nanoparticles could significantly improve the thermal properties of PMMA/CaCO3 and PS/CaCO3 nanocomposites. The glass transition temperature (T g) and decomposition temperature (T d) of nanocomposites with 4 wt% of CaCO3 nanoparticles were increased by 30 and 24 K in case of PMMA/CaCO3 and 32 and 15 K in the case of PS/CaCO3 nanocomposites, respectively. The obtained transparent nanocomposites films were characterized using UV–Vis spectrophotometer which shows the transparencies of nanocomposites are almost maintained in visible region while the intensity of absorption band in ultraviolet (UV) region is increased with CaCO3 nanoparticles contents and these composites particles could enhance the UV-shielding properties of polymers.

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The authors' hypothesis is that the members of the tricarboxylic acid cycle (TCA cycle) such as citrate decrease in association with increased ketone body formation. To prove this hypothesis the connection between ketone bodies and citrate formation of milk was studied. A fluorimetric method was used to determine citrate and a headspace sampling gas chromatographic (GC) method was developed for determination of ketone bodies. Under real conditions of milk sampling, transport and storage, preserved milk samples of 119 clinically healthy dairy cows obtained in the 48 hours after milking were investigated. A low level of acetoacetate (ACAC) was found in all samples. This fact can be explained by the spontaneous decarboxylation of acetoacetate during sample storage (previously decarboxylised acetoacetate = pdACAC) and, consequently, the majority of the amount of acetoacetate in the samples (AC+pdACAC) appeared in the measured acetone concentrations. Based on the measured acetone concentration of milk samples two groups were formed retrospectively: HA (high-acetone) group (n = 41) with an AC+pdACAC concentration of ≯ 0.4 mmol/l and a LA (low-acetone) group (n = 78) with an AC+pdACAC level of ≤ 0.4 mmol/l. In the milk of cows of Group HA a positive correlation (r = +0.623) and linear connection between acetone (AC+pdACAC) and β-hydroxybutyrate (BOHB) levels was found [BOHB = 2.491 + 0.586 × (pdAC + ACAC)]. Furthermore, in this group a negative correlation between citrate and BOHB and AC+pdACAC was also established (r = -0.579). Focusing on the results of this group the authors found a significant drop of AC+pdACAC and citrate during the metabolically critical first 1-4 weeks of lactation. For this reason they suggest that simple, easy, automated methods (i.e. flow injection analysis, Fourier transformation infrared analysis) should be introduced for the simultaneous determination of acetone and citrate concentration in milk to make the evaluation of the energy status of high-producing dairy cows easier and more certain.

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(Eds) Handbook of Near-Infrared Analysis, Marcel Dekker, New York, 2001. Handbook of Near-Infrared Analysis 2001

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