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Abstract  

The solubility of NiSeO3–SeO2–H2O system in the temperature region 298–573 K was studied. The compounds of the three-component system were identified by the Schreinemakers’ method. The phase diagram of nickel(II) selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, NiSeO32H2O, α-NiSeO31/3H2O, β-NiSeO31/3H2O, NiSeO3 and NiSe2O5 were obtained. The different phases were proved and characterized by chemical, powder X-ray diffraction and thermal analyses as well as IR spectroscopy.

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Abstract  

The thermal behavior of montmorillonite and organically modified montmorillonite, both treated with heavy metal cations [Cu(II), Cd(II) and Hg(II)], was characterized via thermal analyses (TG, DTG and DTA) combined with evolved species gas mass spectrometry (MS-EGA), and X-ray diffraction at in situ controlled temperature (HTXRD). The reactions involving Cu(II)- and Cd(II)-montmorillonite samples are mostly related to H2O and OH loss, unlike Hg(II)-montmorillonite, where effects associated to Hg(II) loss are also present. Finally reactions related to dehydration, dehydroxylation and to organic matter decomposition can be observed in montmorillonite samples treated with cysteine.

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Abstract  

The solubility of MnSeO3-SeO2-H2O system was studied in the temperature region 25–300°C. The compounds of the three-component system were identified by the Schreinemaker’s method. The phase diagram of manganese(II) selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, MnSeO3·H2O, MnSeO3·3/4H2O, MnSeO3·l/3H2O and MnSe2O5 were obtained. The different phases were proven and characterized by chemical, powder X-ray diffraction and thermal analyses, as well as IR spectroscopy. The kinetics of dehydration and decomposition of MnSeO3·H2O was studied under non-isothermal heating. Based on 4 calculation procedures and 27 kinetic equations, the values of activation energy and pre-exponential factor in Arrhenius equation were calculated for both processes.

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Journal of Thermal Analysis and Calorimetry
Authors: Simone Pereira da Silva Ribeiro, Luciana Rocha de Moura Estevão, Csaba Novák, and Regina Sandra Veiga Nascimento

samples were pulverized in a cryogenic mill before submitting the material to the thermal analyses. Physical mixtures of APP, PER, and clays were also prepared to observe the synergistic action between these three additives without the interference of the

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, magnetic moment and reflectance spectra, and thermal analyses (TGA and DTA). Biological activities of the complexes are studied. The structure of the drug is given in Fig. 1 . Fig. 1 Structure of MCNZ drug

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Modulated Differential Scanning Calorimetry

The effect of experimental variables

Journal of Thermal Analysis and Calorimetry
Authors: F. Cser, F. Rasoul, and E. Kosior

Abstract  

The reproducibility and reliability of the TA Instruments Modulated Differential Scanning Calorimeter (MDSC) was tested over a range of conditions. The equipment base line was found to be fairly constant with a very small fluctuation (10 μW), which means a 0.1 % fluctuation on the scale of a normal polymer MDSC curve. The excellent stability of the base line and the reasonable reproducibility of the curves (5%) suggest that frequent calibration is not required. The heat capacities calculated from the modulated response to the variable temperature depend on the frequency for a given cell constant. The heat capacity cell constant is a unique function of the modulation frequency:k c=K c o p/(p−6.3) wherep is the time of the periodicity expressed in seconds and Kc o is the heat capacity cell constant measured on a standard material and reduced to zero frequency. The cell constants depend on the flow rate of the helium according to:K(He)=K o(1.298−0.004424He+1.438·10−5 He 2) whereHe is the flow rate of helium in ml min−1 andK o represents a constant at 100 cm3 min−1. There is a strong dependence of cell constant on the flow rate ranges from 10 to 80 cm3 min−1, while above this rate (up to 135 ml min−1) the cell constant approaches a plateau.

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Abstract  

Thermal behaviors of two mixed-ligand complexes, [Ni(PMPP-SAL)(Py)3] and [Cu(PMPP-SAL)Py]·MeOH, (PMPP-SAL=1-phenyl-3-methyl-4-(salicylidene hydrazide)-propenylidene-pyrazolone-5, Py=pyridine), were studied by TG-DTG-DTA in dynamic air atmosphere. The complexes show the loss of pyridine molecule is followed by the decomposition of the PMPP-SAL anion and give respective metal oxides as residues. Meanwhile, the Ozawa-Flynn-Wall model-free analyses and multivariate non-linear regressions were applied to perform single and overall steps optimization. Kinetic parameters were given and the most probable mechanism functions were suggested in this study.

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analyses techniques. The colors, yields, magnetic moments, UV–Vis, and elemental analyses data are given in Table 1 . The IR and thermal analyses data are collected in Tables 2 and 3 , respectively. Table 1 Colors

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