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The effects of the mycotoxin patulin on the thermodynamics and kinetics of the transition of bovine serum albumin (BSA) in aqueous solution were studied by Differential Scanning Calorimetry and Photoluminescence methods. Results show that in the presence of patulin, the free enthalpy change during the transition of BSA was decreased by an average of ∼ 46 kJ/mol, the free energy change was decreased by ∼ 4 kJ/mol, and the activation energy fell from ∼ 1546 to ∼ 840 kJ/mol. These results indicate that the bioactivity of patulin is based on the kinetic rather than on the thermodynamic properties of the transition. This is the first evidence of the direct interaction of patulin with the free thiol-containing BSA, a process which could contribute to the adverse cyto- and genotoxic effects induced by patulin.

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in the remaining bulk melt. Before ordering can commence, the positive free enthalpy barrier of a critical nucleus must be overcome by random fluctuations. A common method to assess homogeneous nucleation is to study ordering in sufficiently small

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Abstract  

Phase diagrams for the systems AgCl-CoCl2 and AgBr-CoBr2 were determined by differential scanning calorimetry. The systems are of the eutectic type. Eutectic points are at 271±2 K, 19.5 mol% CoCl2 and 653±2 K, 17.0 mol% CoBr2, respectively. The solid solubility does not exceed 2 and 4 mol% in the systems AgCl-CoCl2 and AgBr-CoBr2, respectively. Thermodynamic activities of components in molten mixtures and molar free enthalpies of mixing were determined for both systems on the basis of liquidus curves. Deviations from ideality were not found to be considerable.

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Geometries and energies of isolated CaC2O4H2O, CaC2O4, CaCO3, CaO, H2O, CO and CO2 were determined at the ab initio level using effective core potential valence basis sets of doublezeta quality, supplemented with polarization functions. The effects of electron correlation were taken into account at the second order Mller-Plesset level of theory. For CaC2O4H2O, the correlation for the basis set superposition error was also included. Common routines were employed to evaluate entropies, heat capacities, as well as enthalpies and free enthalpies of formation of all entities. The enthalphies and free enthalpies of consecutive dehydration of CaC2O4H2O, decarbonylation of CaC2O4 and decomposition of CaCO3 towards CaO and CO2 were determined on the basis of avialable data from the literature or those predicted thoretically. Assuming that upon all the above mentioned processes the system maintains equilibrium, the fractions reacted, enthalpy changes and differential dependencies of thesevs. temperature were derived and compared with experimental thermoanalytical data.

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Abstract  

The object of this work is the quantitative explanation of linear correlation between activation energy (E), initial decomposition temperature (T i) and ionic potential (V i), observed for thermal degradation of some complexes of transitional metals. The proposed model allowed the evaluation of characteristic parameter proportional to the activation free enthalpy and also the variation of effective electrical charge (ΔQ *) of ligand, in the formation process of the activated complex. These results are satisfactory, taking into account that we utilized many simple hypotheses for deduction of Arrhenius equation.

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The vaporization of samples of different chemical and phase compositions in the systems CsCl-LnCl3 (Ln=Ce, Nd) was investigated in the temperature range between 850 and 1050 K by the use of Knudsen effusion mass spectrometry. The gaseous species CsCl, Cs2Cl2, LnCl3, Ln2Cl6 and CsLnCl4 were identified in the vapour and their partial pressures were determined. The thermodynamic activities of CsCl, and LnCl3 and the free enthalpies of formation for the phases Cs3LnCl6(s) were determined at 950 K in the two phase fields {liquid+Cs3LnCl6(s)}. The correlations between the condensed phase equilibria and the partial pressures of the vapour components at the phase boundaries are discussed and illustrated with the present experimental data.

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In this research, a new composite, poly (hydroxyethylmethacrylate-hydroxyapatite) [P(HEMA-Hap)], was synthesized and its adsorptive features for natural radionuclides (TI+, Ra2+, Bi3+and Ac3+ in a leaching solution) were investigated at differing initial pH, concentration and temperature ranges. The natural radionuclides were counted by gamma spectrometer using a type NAI (Tl) detector. The adsorption data obtained were well represented by Langmuir and Freundlich type isotherms. The magnitude of determined monolayer adsorption capacities (X L) for the adsorbed radionuclides were TI+ = Ac3+ > Ra2+ = Bi3+. These results demonstrated that P(HEMA-Hap) had high affinity to the natural radionuclide. The thermodynamic parameters indicated that the adsorption mechanisms were spontaneous (ΔG < 0) in terms of adsorption free enthalpy, and changes in the enthalpy and entropy values showed that the overall adsorption process was endothermic (ΔH > 0), thus increasing entropy (ΔS > 0).

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The model of regular solutions, that may be applied to binary alloys (e.g. Au−Pt, Si−Ge) has been compared to binary societies: blacks—non-blacks in the US, catholics—non-catholics, foreigners—German citizen. The excellent agreement of phase diagrams and intermarriage data encourages a calculation of the multicultural society by functions of thermodynamics: Solubility corresponds to integration, miscibility gap to segregation, free enthalpy to happiness and temperature to tolerance of a society. Only a high level of tolerance will integrate ghettos and lead to a peaceful multicultural society.

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Abstract  

Composite of polyacrylamide-bentonite (PAA-B) was prepared by direct polymerization in a suspension of bentonite (B), the composite was then modified by phytic acid (PAA-B-Phy). The parameters related to adsorption of UO2 2+ in absence and presence of 0.01M CaCl2 and of natural radionuclides (Tl+, Pb2+, Ra2+ and Ac3+ in a leaching solution) onto PAA-B and PAA-B-Phy, and thermodynamics of the adsorption were investigated. Adsorption isotherms were of L and H types for the adsorption of UO2 2+ onto PAA-B and PAA-B-Phy, whilst for Tl+, Pb2+, Ra2+ and Ac3+ they were of C type for both adsorbents. Langmuir equilibrium constants for the adsorption of all studied ions onto PAA-B-Phy were significantly higher than those found for PAA-B. The thermodynamic parameters indicated that adsorption reactions are spontaneous in terms of adsorption free enthalpy. The composite of PAA-B and its modification by Phy have been used for the first time in this study. It is concluded that the composites can be practically used for adsorption and applied as adsorbent of radionuclides.

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This paper presents a structural model of complex materials that are partly or entirely of cellular structure, and a new model of thermodynamics, which can be applied to the processes taking place in complex materials. Since the complex materials always contain cellular fraction, the supposition of cellular equilibrium is real. The complex materials are characterized by polyagent behaviour. Therefore, new concepts such as principal variables, redundancy, macroscopic/microscopic uncertainty are defined, moreover, the application of chemical thermodynamics is limited to micro processes only, and the free energy (F) and the free enthalpy (G) function cannot be generally applied to calculations concerning the bulk amount. Temperature as only a local intensive variable can be discussed. The first law of thermodynamics is expressed in the traditional way. The second law applied to the processes taking place both in open and in adiabatically closed systems is formulated as in words as an equation of stability, completed by the relations to first and second differential of entropy. In connection with the second law the Damköhler balance equation system, the Rabinowitsch–Mooney equation, and the application of dimensional analysis are presented. Only the apparent thermal capacities can be used for complex materials in general. The data of specific thermal capacity of complex materials in the proximity of absolute zero temperature are not sufficient for drawing conclusions on their entropy. The concept ‘shelf-life’ is essential in food science and practice, a Monte-Carlo method is presented for its calculation.

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