The thermodynamic properties of the liquid and solid Ag-In-Sn alloys were determined, using an electromotive force (EMF) method with an eutectic mixture of (KCl + LiCl) as a liquid electrolyte. The ...measurements were performed over the temperature range from 635 K to 856 K along the cross-sections Ag0.5Sn0.5-In, Ag0.5In0.5-Sn and In0.5Sn0.5-Ag. The partial thermodynamic functions of indium and liquidus temperatures of the investigated alloys were found from the obtained EMF values. The integral thermodynamic properties of alloys at 750 K along the Ag0.5Sn0.5-In cross-section were calculated by Gibbs-Duhem integration.
Experimental points E(T) of the Inx(Ag0.5Sn0.5)1-x isopleth; xIn=0.10 (+); 0.20 (□); 0.333(○); 0.40 (△); 0.50 (▽). Display omitted
•The electromotive force method (EMF) with a liquid electrolyte was used to determine the activity of indium in liquid and solid alloys of the Ag-In-Sn system.•The partial thermodynamic functions of indium were calculated from the obtained EMF values.•The Gibbs-Duhem integration was used to calculate the integral thermodynamic properties of alloys at 750 K along the Ag0.5Sn0.5-In cross-section.
Phase equilibria in the Cu-In-Zn system are calculated using a thermodynamic modeling approach. The thermodynamic model parameters for the constituent binaries Cu-In,Cu-Zn and In-Zn are taken from ...earlier assessments. Thermodynamic descriptions of the ternary liquid and copper-based solutions are obtained based on the experimental thermodynamic and phase equilibria data available in literature for the Cu-In-Zn system. The liquidus surface projection, isothermal sections at 373 and 573 K, as well as vertical sections xCu/xIn = 1:2, 1:1, 2:1 and xIn = 0.75, 0.5 are calculated.
Display omitted
•Thermodynamic modeling of the system Cu-In-Zn.•Calculation of five vertical sections and two isothermal sections.•Calculated liquidus surface projection.
Thermodynamic optimization of the Ln
-
Ru (where
Ln
=
Ce and Sm
) binary systems was carried out by means of CALPHAD method. Our approach is based on the critical review of the available experimental ...data published in literature, including both phase equilibria and thermodynamic data. Nine intermediate phases:
Ln
3
Ru
,
Ce
7
Ru
3
,
Ce
16
Ru
9
,
Ce
4
Ru
3
,
Sm
2
Ru
5
,
Ru
25
Sm
44
,
and
LnRu
2
presented in both binary systems, were treated as stoichiometric compounds. The exponential and linear models were used to describe the temperature dependence of the excess quantities of liquid,
(
δ
Ce
)
,
(
γ
Ce
)
,
(
β
Ce
)
,
(
α
Sm
)
,
(
β
Sm
)
,
(
γ
Sm
)
and
(
Ru
)
solid solution phases. They were compared with the combined linear–exponential temperature dependence of the resulting interaction energies. The self-consistent thermodynamic parameters used to describe the Gibbs energies of various phases in the Ln
-
Ru binary systems were obtained through Thermo-Calc software. The obtained calculated results are in excellent agreement with available phase equilibrium and thermodynamic data.
Synthesis of cationic plastoquinone derivatives (SkQs) containing positively charged phosphonium or rhodamine moieties connected to plastoquinone by decane or pentane linkers is described. It is ...shown that SkQs (i) easily penetrate through planar, mitochondrial, and outer cell membranes, (ii) at low (nanomolar) concentrations, posses strong antioxidant activity in aqueous solution, BLM, lipid micelles, liposomes, isolated mitochondria, and cells, (iii) at higher (micromolar) concentrations, show pronounced prooxidant activity, the “window” between anti- and prooxidant concentrations being very much larger than for MitoQ, a cationic ubiquinone derivative showing very much lower antioxidant activity and higher prooxidant activity, (iv) are reduced by the respiratory chain to SkQH₂, the rate of oxidation of SkQH₂ being lower than the rate of SkQ reduction, and (v) prevent oxidation of mitochondrial cardiolipin by OH·. In HeLa cells and human fibroblasts, SkQs operate as powerful inhibitors of the ROS-induced apoptosis and necrosis. For the two most active SkQs, namely SkQ1 and SkQR1, C ₁/₂ values for inhibition of the H₂O₂-induced apoptosis in fibroblasts appear to be as low as 1·10⁻¹¹ and 8·10⁻¹³ M, respectively. SkQR1, a fluorescent representative of the SkQ family, specifically stains a single type of organelles in the living cell, i.e. energized mitochondria. Such specificity is explained by the fact that it is the mitochondrial matrix that is the only negatively-charged compartment inside the cell. Assuming that the Δψ values on the outer cell and inner mitochondrial membranes are about 60 and 180 mV, respectively, and taking into account distribution coefficient of SkQ1 between lipid and water (about 13,000: 1), the SkQ1 concentration in the inner leaflet of the inner mitochondrial membrane should be 1.3·10⁸ times higher than in the extracellular space. This explains the very high efficiency of such compounds in experiments on cell cultures. It is concluded that SkQs are rechargeable, mitochondria-targeted antioxidants of very high efficiency and specificity. Therefore, they might be used to effectively prevent ROS-induced oxidation of lipids and proteins in the inner mitochondrial membrane in vivo.
The calculated vertical section of the Cu–In–Pb system at xCu/xPb=1.
•Thermodynamic modeling of the system Cu–In–Pb.•Calculation of four vertical sections and two isothermal sections.•Calculated ...liquidus surface projection.
Phase equilibria in the Cu–In–Pb system are calculated using a thermodynamic modeling approach. The thermodynamic model parameters for the constituent binaries Cu–In, Cu–Pb and In–Pb are taken from earlier assessments. Thermodynamic description of the ternary liquid phase is obtained based on the phase equilibria data available in literature for the xIn=0.75 vertical section of the Cu–In–Pb system. The liquidus surface projection, isothermal sections at 373 and 573K, as well as vertical sections xCu/xPb=1, xIn=0.75, xIn=0.5, and xIn=0.25 are calculated.
The systematic thermodynamic optimization of the
Ln-Ru
(where
Ln
=
Nd
,
Gd
, and
Dy
) binary systems is performed using the
CALPHAD
approach. Using this approach, experimental information published ...in literature, including both phase equilibria and thermodynamic data, are critically evaluated. The thirteen intermediate phases with stoichiometries, such as
Ln
3
Ru
,
Nd
5
Ru
2
,
Ln
7
Ru
3
,
Nd
5
Ru
3
,
Ln
73
Ru
27
,
Ln
2
Ru
, and
LnRu
2
, which have been reported for the three binary
Ln-Ru
systems are considered as stoichiometric compounds. An exponential and a quadratic model are used to describe the temperature dependence of the excess quantities for the Liquid, (
αNd
), (
βNd
), (
αDy
), (
βDy
), (
αGd
), (
βGd
), and (
Ru
) solution phases. The results were compared with those from a combined quadratic-exponential temperature dependence description of the excess energies. Using the Thermo-Calc software, self-consistent sets of thermodynamic parameters were obtained to describe the Gibbs energies of the numerous phases in the
Ln-Ru
binary systems. The calculated results are in good agreement with the available phase equilibria and thermodynamic data.
Comparison of the standard entropies of pure lanthanides Ln (1) and their compounds Ln0.4Te0.6 (2), Ln0.4Se0.6 (3) and Ln0.4S0.6 (4) vs. N-NGd, where N is the atomic number of lanthanides.
Display ...omitted
•Determination of thermodynamic functions of solid Lu2Te3 by means of electromotive force measurements.•Evaluation of thermodynamic properties of lanthanide chalcogenides.•Application of the tetrad-effect concept for the assessment of thermodynamic properties of lanthanide compounds.
The thermodynamic functions for the formation of solid Lu2Te3 were obtained by means of electromotive force (EMF) measurements. These results were used to demonstrate (taking as an example, the solid lanthanide tellurides (Ln2Te3)) that the combination of the EMF method (this allows us to measure the Gibbs energy for the formation of a compound from its elements with high precision) with low-temperature heat capacity measurements and the tetrad-effect phenomenon (this allows us to find the entropy of compound with a high degree of accuracy) can be an effective tool for determining the thermodynamic functions of lanthanide compounds. The experimental and calculated values for the thermodynamic functions of solid Ln2Te3 phases are given.
Gibbs energies of formation vs. RE atomic numbers in REIn3 Display omitted
•Set of experimental values was collected for REIn3 phases.•Thermodynamic functions of formation were calculated at 298 K ...and 775 K.•Experimental and calculated values were compared.
Nonlinear correlative analyses between thermodynamic and some physico-chemical properties of rare-earth metals (RE) and their alloys with indium are performed for the isostructural phases RE and REIn3. The thermodynamics values (Gibbs energies of formation, enthalpies of formation, and entropies of formation at 298K and 775K and standard entropies) of LnIn3 phases are calculated on the basis of calorimetry and potentiometry results. The proposed correlation between physico-chemical and thermodynamic properties agrees for all the isostructural phases REX (X are others elements of the periodic table). The resulting thermodynamic data are recommended for metallurgical handbook.
The correct mathematical description of heat capacities Cp in a wide range of temperatures is still unsolved problem. A fragmental description of some phases is like a vision of one part of a large ...mosaic picture. A single description of Cp or other property of a phase of any isostructural series does not allow one to see the integrity of the entire ensemble. We propose a special mathematical model to describe Cp in a wide temperature range for a whole large class of isostructural sphalerite phases. In the proposed model, it is believed that an ideal crystal does not have any foreign inclusions, defects, or dislocations. The group IV elements (Si, Ge, α-Sn and diamond-like Pb) were taken as the basis, with flerovium (114Fl) closing this group. There should be no other elements in this group according to the fine structure constant (α) (or the Sommerfeld constant). As a consequence, the limiting value of the heat capacities of phases with a sphalerite structure falls on the element 114 (114Fl) and has a value of Cp = 30.5 ± 0.3 J · mol-at−1 · K−1. This value was obtained as a maximal virtual point Cp of the last element (114Fl) of group IV and corresponds to Ln (Cp/R) = 1.30 ± 0.01 for the isotherms ln (Cp/R) vs Ln(N), where N is an atomic number of an element of group IV or the sum of the atomic numbers of AIIIBV or AIIBVI compounds per mole-atom. The common point of heat capacity attributable to flerovium is obtained from the linear equations Ср/R vs Ln(N) at low temperatures from 25 to 35K. For only pure elements of group IV (Si, Ge, α-Sn and diamond-like Pb), flerovium closes this group, and there are no other elements behind it, according to α. The maximum heat capacity of flerovium can be taken as 30.5 J·mol-at−1·K−1 with an accuracy of 1%. As the temperature decreases, this value slowly decreases (within 1%), and then, when it approaches 0 K, it drops sharply to 0 J·mol-at−1·K−1. To describe the set of the isostructural experimental data Cp(T) for diamond-like phases in solid state as a whole system, here we used a special multi-parameter family of functions. For each substance, the parameters are found by minimizing the discrepancy between the theoretical dependence Cp(T) and corresponding experimental data. The dependence of the heat capacities for elements of group IV (Si, Ge, α-Sn, diamond-like Pb, Fl) at fixed temperatures on Ln(N), where N is the atomic number or the demi sum of the atomic numbers of phases AIIBVI or AIIIBV. In this case, either a break point or an inflection point attributable to germanium is observed for parameter dependencies on Ln(N).
•Experimental data Cp(T) of diamond-like phases are described as a single system.•A multi-parameter family of functions (MPFFs) was used to describe Cp(T).•MPFF coefficients are polynomial equations with N (atomic number of group IV element).•For AIIBVI or AIIIBV phases, N was the demi-sum of atomic numbers.•Unknown MPFF coefficients for Al, Ga, In, Tl and Nh nitrides were interpolated.
Calculated vertical section of the In–Pb–Zn system at In:Zn=1:1. Display omitted
► EMF study and thermodynamic modeling of the system In–Pb–Zn. ► Calculation of three vertical sections. ► Calculated ...liquidus surface projection.
Seven alloys of the In–Pb–Zn ternary system were studied in the range of 660–791K by the method of electromotive forces (EMFs), using the electrochemical cell:
(−) Zn|ZnCl2+KCl+LiCl|In–Pb–Zn (+). Temperature dependencies of EMF (E(T)=a+b⋅T) were obtained for three phase regions: (I) homogeneous liquid, (II) heterogeneous liquid 1+liquid 2 and (III) heterogeneous liquid 3+solid mixtures.
Based on these equations the values of chemical potential of zinc as well as phase transition temperatures were found. On the basis of the obtained and literature data, thermodynamic model of ternary liquid was proposed. The liquidus surface projection and vertical sections In0.5Pb0.5–Zn, In0.5Zn0.5–Pb, Pb0.5Zn0.5–In of the system In–Pb–Zn were calculated.
