Dataset Information

Calorimetric Studies of Magnesium-Rich Mg-Pd Alloys.

ABSTRACT: Solution calorimetry with liquid aluminum as the bath was conducted to measure the enthalpy of a solution of magnesium and palladium as well as the standard formation enthalpies of selected magnesium-palladium alloys. These alloys were synthesized from pure elements, which were melted in a resistance furnace that was placed in a glove box containing high-purity argon and a very low concentration of impurities, such as oxygen and water vapor. A Setaram MHTC 96 Line evo drop calorimeter was used to determine the energetic effects of the solution. The enthalpies of the Mg and Pd solutions in liquid aluminum were measured at 1033 K, and they equaled -8.6 ± 1.1 and -186.8 ± 1.1 kJ/mol, respectively. The values of the standard formation enthalpy of the investigated alloys with concentrations close to the Mg₆Pd, ?, Mg₅Pd₂, and Mg₂Pd intermetallic phases were determined as follows: -28.0 ± 1.2 kJ/mol of atoms, -32.6 ± 1.6 kJ/mol of atoms, -46.8 ± 1.4 kJ/mol of atoms, and -56.0 ± 1.6 kJ/mol of atoms, respectively. The latter data were compared with existing experimental and theoretical data from the literature along with data calculated using the Miedema model.

SUBMITTER: Debski A

PROVIDER: S-EPMC7867242 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Calorimetric Studies of Magnesium-Rich Mg-Pd Alloys.

Dębski Adam A Terlicka Sylwia S Gąsior Władysław W Gierlotka Wojciech W Pęska Magda M Dworecka-Wójcik Julita J Polański Marek M

Materials (Basel, Switzerland) 20210202 3

Solution calorimetry with liquid aluminum as the bath was conducted to measure the enthalpy of a solution of magnesium and palladium as well as the standard formation enthalpies of selected magnesium-palladium alloys. These alloys were synthesized from pure elements, which were melted in a resistance furnace that was placed in a glove box containing high-purity argon and a very low concentration of impurities, such as oxygen and water vapor. A Setaram MHTC 96 Line evo drop calorimeter was used t ...[more]

PMID: 33540597

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Project description:Calorimetric and fluorescence techniques were used to characterize the binding of aminoglycosides-neomycin, paromomycin, and ribostamycin, with 5'-dA(12)-x-dT(12)-x-dT(12)-3' intramolecular DNA triplex (x = hexaethylene glycol) and poly(dA).2poly(dT) triplex. Our results demonstrate the following features: (1) UV thermal analysis reveals that the T(m) for triplex decreases with increasing pH value in the presence of neomycin, while the T(m) for the duplex remains unchanged. (2) The binding affinity of neomycin decreases with increased pH, although there is an increase in observed binding enthalpy. (3) ITC studies conducted in two buffers (sodium cacodylate and MOPS) yield the number of protonated drug amino groups (Deltan) as 0.29 and 0.40 for neomycin and paromomycin interaction with 5'-dA(12)-x-dT(12)-x-dT(12)-3', respectively. (4) The specific heat capacity change (DeltaC(p)) determined by ITC studies is negative, with more negative values at lower salt concentrations. From 100 mM to 250 mM KCl, the DeltaC(p) ranges from -402 to -60 cal/(mol K) for neomycin. At pH 5.5, a more positive DeltaC(p) is observed, with a value of -98 cal/(mol K) at 100 mM KCl. DeltaC(p) is not significantly affected by ionic strength. (5) Salt dependence studies reveal that there are at least three amino groups of neomycin participating in the electrostatic interactions with the triplex. (6) FID studies using thiazole orange were used to derive the AC(50) (aminoglycoside concentration needed to displace 50% of the dye from the triplex) values. Neomycin shows a seven fold higher affinity than paromomycin and eleven fold higher affinity than ribostamycin at pH 6.8. (7) Modeling studies, consistent with UV and ITC results, show the importance of an additional positive charge in triplex recognition by neomycin. The modeling and thermodynamic studies indicate that neomycin binding to the DNA triplex depends upon significant contributions from charge as well as shape complementarity of the drug to the DNA triplex Watson-Hoogsteen groove.

Dataset Information

Calorimetric Studies of Magnesium-Rich Mg-Pd Alloys.

Publications

Calorimetric Studies of Magnesium-Rich Mg-Pd Alloys.

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