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Abstract  

Differential Scanning Calorimetry combined with Fourier transform infrared spectroscopy, was applied to the study of a number of fulvic and humic acids extracted from soils, peat, river and seawater. The thermal patterns obtained were related to the nature and origin of samples. The low-temperature endotherms were attributed to dehydration and loss of peripheral polysaccharide chains. The endotherm at 250°C observed for soil FA was ascribed to partial decarboxylation of more labile surface COOH groups, whereas the high-temperature exotherms at about 500°C were related to the degree of polycondensation of the aromatic network of the humic molecules.

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Abstract  

A critical thermodynamic analysis of differential thermal calorimetry is reported herein to gain further insight into the phenomena leading to the reported differences between kinetic parameters extracted from isothermal DSC methods and those from dynamic DSC methods. The sources have been identified for the variations observed in the total heat of reaction as a function of the heating rate in dynamic DSC experiments. The analysis clearly indicates that these variations are, in fact, to be anticipated. The relationships necessary for extracting kinetic data from both isothermal and dynamic experiments are derived rigorously by resorting to classical thermodynamics.

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Differential scanning calorimetry was applied in studies of the effect of gamma irradiation on the potato starch and wheat flour. Essential differences were noticed between endothermal effects observed in concentrated suspensions of the initial and irradiated potato starch and wheat flour heated at a rate of 2.5C min-1, while only small differences were noticed between gelatinization thermal effects recorded for ca. 20% suspensions of the initial and irradiated potato starch samples heated at a rate 10C min-1. Moreover, in the case of wheat flour, a decrease of decomposition temperature of the amylose-lipid complex was concluded.

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The glass formation and devitrification of GaF3-based glasses were studied by differential scanning calorimetry. A comparison of various simple quantitative methods to assess the level of stability of multicomponent fluoride glass systems is presented. Most of these methods are based on critical temperatures. In this paper a new parameter k b(T) is added to the stability criteria. The stability of several GaF3-based glasses were experimentally evaluated and correlated with the activation energies of crystallization via this new kinetic criterion and compared with those evaluated by other criteria.

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Volatile organic compounds (VOCs) are the main factors involved in pollution control and global warming in industrialized nations. Various treatment methods involving incineration, adsorption, etc., were employed to reduce VOCs concentration. Various absorbents, such as activated carbon, zeolite, silica gel or alumina, and so on were broadly used to adsorb VOCs in various industrial applications. Differential scanning calorimetry (DSC) was handled to analyze the thermal characteristics of absorbents. Typically, a scanning electron microscope (SEM) has been used to evaluate the structure variation of absorbents under high temperature situations. In view of pollution control and loss prevention, versatility and analysis of recycled adsorbents are necessary and useful for various industrial applications.

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Abstract  

A modulated-temperature differential scanning calorimetry (M-TDSC) method for the analysis of interphases in multi-component polymer materials has been developed further. As examples, interphases in a polybutadiene-natural rubber (50:50 by mass) blend, a poly(methyl methacrylate)-poly(vinyl acetate) (50:50 by mass) structured latex film, a polyepichlorohydrinpoly(vinyl acetate) bilayer film, and polystyrene-polyurethane (40:60 by mass) and poly(ethyl methacrylate)-polyurethane (60:40 by mass) interpenetrating polymer networks were investigated. The mass fraction of interphase and its composition can be calculated quantitatively. These interphases do not exhibit clear separate glass transition temperatures, but occur continually between the glass transition temperatures of the constituent polymers.

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Abstract  

In several current important problems in different areas of soft matter physics, controversy persists in interpreting the molecular dynamics observed by various spectroscopies including dielectric relaxation, light scattering, nuclear magnetic resonance, and neutron scattering. Outstanding examples include: (1) relaxation of water in aqueous mixtures, in molecular sieves and silica-gel nanopores, and in hydration shell of proteins; and (2) dynamics of each component in binary miscible polymer blends, in mixtures of an amorphous polymer with a small molecular glassformer, and in binary mixtures of two small molecular glassformers. We show the applications of calorimetry to these problems have enhanced our understanding of the dynamics and eliminated the controversies.

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The purpose of this study was to further characterize the altered metabolism spondylolisthesis that promotes disease progression. Degenerative human cartilage (intervertebral disc, facet joint and vertebral end-plate) was obtained during 15 posterior lumbar spine interbody fusion procedures performed at the University of Szeged. The thermal properties of samples were determined by differential scanning calorimetry (Mettler-Toledo DSC 821e). Greatest change in the enthalpy was observed in the intervertebral disc samples: −1600.78 J g−1. Denaturation caused by heating in the normal human hyaline cartilage needed −1493.31 J g−1 energy. Characterization of the altered metabolism that promotes disease progression should lead to future treatment options.

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The decomposition processes of a carburised Fe–C alloy, a Fe–C, a Fe–Cr–C and commercial SAE 52100 cast alloys (with a C content of about 1 mass%) have been studied by means of differential scanning calorimetry and dilatometry. The combination of these two experimental techniques is very powerful and allows the identification of all the stages occurring during tempering. Activation energies have been obtained by performing a Kissinger-like analysis and were used to infer the rate-determining step for each stage of decomposition. This parallel investigation allowed to determine the effect of the alloying elements on the different stages of tempering.

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Abstract  

In this study, the use of differential scanning calorimetry (DSC) is demonstrated as a powerful technique that can provide accurate thermodynamic property values of environmental contaminants such as polycyclic aromatic hydrocarbons (PAHs). In total, 47 high purity PAH certified reference materials were selected and analysed by DSC. Their onset melting temperature, enthalpy of fusion and eutectic purity were calculated from the obtained melting endotherms. In addition, the entropy of fusion, which was calculated from the onset melting temperature and enthalpy of fusion, is presented. All measurements were evaluated in a metrologically rigorous manner, including measurement uncertainties.

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