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Thermal curve interpretation by spectral resolution into a basic set of rectangular pulse curves

II. Modification of the algorithm and analysis of the efficiency of the method

Journal of Thermal Analysis and Calorimetry
Authors: L. Adamowicz and W. Zielenkiewicz
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Abstract  

A new-design conduction microcalorimeter is described, which has been used to measure the heat of cement hydration evolved in the initial period of hydration. The calorimeter is 30 cm3 in volume; the heat loss coefficient is 27.2700.015 W V–1, the time constant is 300 s.

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Evaluation of thermodynamic functions relative to cavity formation in aqueous solutions

Comparison of the results calculated from Scaled Particle Theory and Sinanoglu's theory for 2-alkyl-9-methyladenines

Journal of Thermal Analysis and Calorimetry
Authors: W. Zielenkiewicz, P. Zielenkiewicz, and P. Lapshov

Abstract  

The results of calculation of free Gibbs energy and enthalpy of cavity formation were described using the Scaled Particle and Sinanoglu's theories.

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Abstract  

Calorimetric and volumetric investigations of ovalbumin salting by sodium chloride, lithium chloride, potassium chloride, lithium sulfate and ammonium sulfate buffered solutions in the range of concentrations of about 0.2–1.2 M of salts are reported. The evolution of enthalpies and apparent molar volumes vs. salts concentration was investigated using ITC MicroCal titration microcalorimeter and Anton Paar DMA 60/602 digital densimeter. It was found that the changes in enthalpies of salting and apparent molar volumes follow a similar trend. Conclusions about the ability of salts: to precipitate ovalbumin solution are presented.

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Abstract  

The enthalpy changes of salting process of hen-egg white lysozyme in buffer acetate solutions (pH=4.25) as a function of concentration of following electrolytes: LiCl, KCl, K2SO4, Li2 SO4 and (NH4)2SO4 are determined. Obtained data according to McMillan and Mayer’s approach, has been analyzed in the terms of the enthalpic pairwise interaction coefficients: lysozyme – lysozyme h xx, and lysozyme – salt h xy. The ability of cations to precipitate lysozyme solution in relation to the concentration of cations can be seen from the series as follows: Li+> Na+>K+>NH4++

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Abstract  

Thermal power accompanying the hydrolysis of mono- and bi-acylated acyclonucleosides:(R,S)-1-N-(1-O-acetyl-3-hydroxypropoxymethyl)-thymine (ThL),1-N-(1,3-di-O-acetylpropoxymethyl)-thymine (ThAc), and1-N-(1,3-di-O-acetylpropoxymethyl)-5-fluorouracil (FAc), catalysed by lipase from Candida Cylindracea (Rugosa) was investigated by isothermal heat conduction microcalorimetry. Changes of the thermal power in time and the total heat effects were determined in long-lasting measurements. Hydrolysis of these compounds was examined also by TLC. For all three esters the thermal power curves reveal both a relatively intensive and slow heat evolutions. It is suggested that this complexity results from a superposition of: (i) a stereospecific hydrolysis of the ester bond connected to the heterocyclic moiety by a chain endowed with an appropriate chirality, and (ii) a non-specific hydrolysis of another ester bond. A partial chemical degradation of reactants in the buffer was also observed.

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Abstract  

2′3′-dideoxyinosine (ddI) and 2′3′-dideoxyadenosine (ddA) are known to exhibit relatively selective activityvs. HIV strains in cell cultures and low toxicityin vivo; ddI has been approved for the treatment of HIV infection in humans. It is therefore interesting to determine the thermodynamic properties of aqueous solutions of these compounds. For this purpose, we determined their apparent molar volumesV ϕ and heat capacitiesC . The preliminary measurements of interaction of these compounds with peptides were made. The volume and molar heat capacities of transfer of ddI and ddA from aqueous solutions to glycyl-glycine (Gly-Gly) ones were calculated. For both compounds the significant values ofC Pϕ3,tr which depended on the concentration of Gly-Gly were observed.

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Abstract  

Temperature dependences of solubility, saturated vapour pressure and crystal heat capacity of [4-(Benzyloxy)phenyl]acetic acid were determined. The solubility of this compound was investigated in n-hexane, buffered water solutions with pH 2.0 and 7.4 and n-octanol. The enthalpy of sublimation and vaporization as well as the fusion temperature were determined. Solvation and solubility processes have been analyzed. The thermodynamics of transfer processes from one buffer to another (protonation process), from buffers to 1-octanol (partitioning process), and from n-hexane to the applied solvents (specific interaction) have been calculated and compared to those of other NSAIDs. The relevant shares of specific and non-specific interactions in the process of solvation have been investigated and discussed.

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