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Abstract  

The comprehensive analysis of volatile β-diketonate compound—ruthenium(III) trifruoroacetylacetonate (Ru(tfac)3)—was carried out. By means of flow method in quasi-equilibrium conditions and static method the temperature dependencies of saturated vapor pressure have been measured over solid and liquid cis- and trans-modifications of Ru(tfac)3 and isomer mixture. The thermodynamic characteristics of sublimation, evaporation, melting, and phase conversion have been calculated for structural isomers. Also by differential-scanning calorimetry the temperature meanings and the thermodynamic characteristics of melting have been determined for individual isomers of Ru(tfac)3 and their mixtures. By XRD the structures for cis- and trans-modifications have been determined. Both structures consist of neutral molecules arranged in pseudo layers.

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deintercalation processes were not investigated. In this study, we studied the effect of the composition (structure) of the C 2 F x matrix (0.49 < x < 0.92) on the thermodynamic characteristics of the processes of thermal deintercalation of FGIC-1 to

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Abstract  

The enthalpies of dissolution of ZrCl4, ZrBr4, HfCl4 and HfBr4 in water in weakly acidic and alkaline solutions were measured at 25C in a calorimeter provided with an isothermal cover. The standard enthalpies of formation of Zr(OH)4 and Hf(OH)4 in solution were measured. The thermodynamic characteristics of the reactions which resulted in the formation of tetrahydroxy complexes of Zr and Hf in aqueous solution were also determined.

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Abstract

Methylcellulose (MC) is a thermo-reversible physical hydrogel. This study investigates the thermodynamic characteristics of gelation mechanism for MC. The relative and absolute specific heat capacity values of the hydrogel system were modeled using an empirical formulation to facilitate calculation of thermodynamic parameters. Experiments verifying the assumptions for the model formulation were conducted and are discussed. Parameters such as enthalpy, entropy, and changes in their magnitude as a function of temperature were calculated and their trends were studied. The implications of these observations on the various stages of the gel formation process and the associated mechanisms are evaluated. The studies revealed that the gelation of MC is a temperature- driven process rather than only driven by the heat input, and it attains a state of equilibrium under isothermal conditions. During gelation, the entropy of the overall (MC+water) system increases due to an increase in the disorderliness of the MC system.

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Journal of Thermal Analysis and Calorimetry
Authors: Kseniya V. Zherikova, Ludmila N. Zelenina, Natalia B. Morozova, and Tamara P. Chusova

-scanning calorimetry (DSC) melting points and the thermodynamic characteristics of melting were determined for Ru(acac) 3 , Ru(hfac) 3 , and Ru(mdhd) 3 . Results are listed in Table 1 . The data calculated from static method experiments for Ru(hfac) 3 are also listed

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Abstract  

Complexes of ruthenium(III) with the following beta-diketones: 2,4-pentanedione (Ru(acac)3), 1,1,1-trifluoro-2,4-pentanedione (Ru(tfac)3), 2,2,6,6-tetramethyl-3,5-heptanedione (Ru(thd)3), 2,2,6,6–tetramethyl-4-fluoro-3,5-heptanedione (Ru(tfhd)3) and 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (Ru(ptac)3) were synthesized and identified by means of mass spectrometry. By effusion Knudsen method with mass spectrometric registration of gas phase composition the temperature dependencies of saturated vapor pressure were measured for ruthenium(III) compounds and the thermodynamic characteristics of vaporization processes enthalpy ΔH T* and entropy
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of this complexes were determined.
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Abstract  

The osteoporosis is regarded as a widespread disease all over the world. In the prevention therapy of this disease there is a primary role of the daily calcium intake with the proper Ca:P ratio (1:1–1:2). The primary source of Ca for people the dairy products are implied, from which only the processed cheeses have inadequate ratio of Ca:P. In cheeses processed without peptization developed in the Hungarian Dairy Research Institute (HDRI) the Ca:P ratio meets the requirements (1.5:1), moreover these products can be enriched with Ca. In this study we used both processing technologies. The electronmicroscopic photographs demonstrate the differences clearly. The traditionally processed cheese (with peptization) has a 'spongy’ structure well known from literature, while a space-net can be seen resulting from the casein-filamentous hydrocolloid interaction in the structure of heat-treated cheese without peptization. DSC curves are the same in the temperature range 0–40C, showing endotherm melting process in two well-distinguished temperature interval (0–20 and 22–40C). They are different in the temperature interval 40–100C: in the case of processed cheese with peptization the gel-sol transformation gives a higher endotherm peak in a narrow temperature range, while for heat-treated cheese without peptization this temperature range is wider with a lower endotherm peak. Both electronmicroscopic and DSC investigations have proved that contrary to the traditionally processed cheese where the structure is formed by the linked peptized protein, in the heat- processed cheese without peptization the frame-forming element is the huge hydrocolloid molecule interacted with the protein. The enthalpy change is substantially lower at the disintegration of the latter structure.

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using fermentative or synthetic capabilities of microbial, animal, or plant cells, will be important components of these technologies. In developing these, a clear understanding of the energy exchanges and of the thermodynamic characteristics of such

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aqueous solutions thermodynamic characteristics of the diclofenac salt on the basis of these parameters. Fig. 1 Structural formula of potassium diclofenac salt Material

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