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Rationale: Ceria‐based systems are of great interest because of their unique properties. Such systems may be used as anode materials for SOFCs or in oxygen sensors. The exploitation of these materials often requires high temperatures. In such conditions, the partial or complete evaporation of materials is possible. Therefore, knowledge of the values of partial pressures and thermodynamic properties is essential to predict and/or prevent possible consequences and accidents. Methods: Knudsen effusion mass spectrometry was used to determine partial pressures of vapor species over the SrO–CeO2 and CaO‐CeO2 systems. Measurements of partial pressures were performed with a MS‐1301 mass spectrometer. Vaporization was carried out using molybdenum or tungsten effusion cells. A theoretical study of gaseous strontium and calcium cerates was performed by several quantum chemical methods: density functional theory (DFT) M06, DFT PBE0, and MP2. Results: The minimum value of relative electron ionization cross‐section for CeO2 was estimated. In the temperature range of 2218–2249 K above the SrO‐CeO2 system and of 2128–2208 K above the CaO‐CeO2 system, gaseous M, MO, MO, CeO2, O, O2 and MCeO3 (M = Sr, Ca) were found. Energetically favorable structures of gaseous SrCeO3 and CaCeO3 were found, and vibrational frequencies were evaluated in the "rigid rotor‐harmonic oscillator" approximation. On the basis of the equilibrium constants of gaseous reaction MO + CeO2 = MCeO3, the standard formation enthalpy of gaseous SrCeO3 (−913 ± 26 kJ/mol) and of gaseous CaCeO3 (−917 ± 26 kJ/mol) at 298 K were determined. Conclusions: The estimated value of relative electron ionization cross‐section for CeO2 is in agreement with the general rule applicable for dioxides. The stability of SrCeO3 and CaCeO3 gaseous species was confirmed by KEMS. Gas‐phase reactions involving gaseous SrO (CaO) and CeO2 with gaseous SrCeO3(CaCeO3) were studied. Enthalpy of formation reaction of gaseous SrCeO3(CaCeO3) from gaseous SrO (CaO) were evaluated theoretically, and the obtained value is in agreement with the experimental one. [ABSTRACT FROM AUTHOR]

A detailed study on the stages of catalytic reactions involving platinum and platinum-vanadium clusters has been carried out. Minimum energy pathways (MEP) of reactions have been constructed via the DFT/PBE0/def2tzvp method using NEB functional and optimized structures, and points of minima and transition states have been calculated. A two-step process for the conversion of formamide to methylamine under the action of H2 has been considered as a test reaction. The energy barriers of this reaction, not previously described in the literature, have been evaluated. It has been shown that the main changes in the structural characteristics of the reagents, as well as the migration of single H atoms from one metal center of clusters to another or to an organic substrate, are initiated at the molecular level by shifts corresponding to the vectors of normal vibrations of systems in transition states. [ABSTRACT FROM AUTHOR]

To date, nickel(II) complexes have not been practically investigated as catalysts in ring-opening polymerization (ROP) of lactide to produce biodegradable poly(lactic acid), which is in demand in biomedicine and industry. In this study, carboxylate complexes of nickel(II) containing various N-donor ligands with different nuclearity, metal core rigidity and nature of carboxylate ligands were synthesized and studied by infrared spectroscopy, X-ray diffraction, elemental and thermogravimetric analyses. The obtained complexes were examined in the ROP of the rac-lactide in bulk and in toluene solution with and without the addition of a benzyl alcohol initiator. In the series of complexes studied, the complex [Ni(DBED)2(O2CC(CH3)3)2]·(CH3)3CCO2H (DBED is N,N′-dibenzylethylenediamine) was a syndioselective catalyst and showed the highest catalytic ability in the polymerization without the addition of benzyl alcohol. For this complex, according to 1D DOSY 1H NMR spectroscopy and mass spectrometry with electrospray ionization, polymerization is initiated by a free secondary amine, DBED, leaving the metal's inner coordination sphere. Based on the experimental data obtained, a comprehensive density functional theory (DFT) study of the ROP pathways including the initiation and first chain growth cycle steps with a detailed description of the intermediates and evaluation of the energy barriers of the steps was carried out. It was shown that one of the key roles in the reaction process is played by carboxylate ligands, which act as proton carriers from the initiator molecule and have a significant influence on the reactivity of the catalytic metal complexes. [ABSTRACT FROM AUTHOR]

An analysis of the possible effect of long-term stress from radiation exposure on cognitive functioning in 300 children from families evacuated to Kyiv, Ukraine, following the Chornobyl nuclear power plant accident in 1986 indicates that the evacuee children performed as well as their contemporaries in memory, attention and intelligence tests. This was also the case for children who were in utero at the time of the disaster. However, more evacuee mothers reported memory difficulties in their children than classmates' mothers. This is likely to be connected with mothers' anxiety.

The article presents the main results of the monitoring surveys (1992-2003) on inter-ethnic attitudes of Ukrainian population measured according to the social distance scale by Bogardus adapted by the article author in 1990 in Ukraine. The obtained data made it possible to reveal a number of phenomena and paradoxes of the mass inter-ethnic self-consciousness of population. New results confirmed the growing orientations (in the mass consciousness) to the more ethnic distance which promote development of the national and governmental isolation. The author paid a lot of attention to methodology (the social distance scale). [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) and Hartree–Fock (HF) methods have been used to calculate the electronic and geometric structures of cis- and trans-[Pt(NH3)2X2] (X = Cl-, Br-, I-), [cis-Pt(NH3)2(H2O)2]2+ and its deprotonated forms. The thermodynamic parameters ΔH0298, ΔS0298, ΔG0298, and ΔCp = f(T) have been obtained from DFT force fields and normal mode frequencies. It is shown that the greater stability of the trans-isomers is due, at the molecular level, to different interligand interactions. The stability of the cis-isomers is significantly increased by intermolecular Pt…Pt and NH2-H…X nonvalence interactions between mononuclear [cis-Pt(NH3)2X2] moieties, the effect reducing in the row Cl- > Br- > I-. The thermodynamic parameters of possible phases of the hydrolysis of [cis-Pt(NH3)2(H2O)2]2+ have been also derived. Solvent effects have been investigated calculating the equilibrium constants for the proton transfer reactions both in gas phase and water solution. It is shown that in aqueous medium the hydroxobridged platinum dimer [Pt(NH3)2- (μ-OH)]2+2, characterized by a Pt…Pt distance of 3.119 Å, is the preferred hydrolysis product. It is also shown that with short metal–metal interactions, such as those found in [cis-Pt(NH3)2Cl2] and [cis-Pt(NH3)2(H2O)2]2+, the conditions for the formation of linear polynuclear complexes with Pt—Pt bonds (the so-called “platinum blues”) are created. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 [ABSTRACT FROM AUTHOR]

The different stability of S&z.sbnd; and O&z.sbnd; bonded dimethyl sulfoxide Ru(III) and Rh(III) complexes, [MClmL5−m(DMSO)]n, has been studied by the density functional method (B3LYP/6-31 G(d,p)). The calculated binding energies indicate that the S-bonded isomers are more stable than the O-isomers when L is a σ donor ligand, while the stability order is reversed when L is a π accepting ligand. This trend can be rationalized in terms of the absolute electronegativity of the square-pyramidal complex [MClmL5−m]n, rather than in terms of its global softness. S&z.sbnd; and O&z.sbnd; bonding are definitely favored, respectively, by highly negative and highly positive electronegativities. The trend of the M&z.sbnd;S and S&z.sbnd;O distances indicates the absence of significant π back-bonding M→DMSO, even in the case of σ donors, in contrast with the behavior of Ru(II) complexes. [Copyright &y& Elsevier]

Analyzing the potential for and the manifestations of social protest is one of the most important parts of studying and predicting social development and anticipating social conflicts, of which there is a real danger under conditions of economic crisis, growing popular dissatisfaction with living standards and quality of life, and a reorientation of the public mind from overwhelming support for market reforms to increasing nostalgia for administrative methods of regulating the economy. [ABSTRACT FROM AUTHOR]

Rationale: Ceria-based systems are of great interest because of their unique properties. Such systems may be used as anode materials for SOFCs or in oxygen sensors. The exploitation of these materials often requires high temperatures. In such conditions, the partial or complete evaporation of materials is possible. Therefore, knowledge of the values of partial pressures and thermodynamic properties is essential to predict and/or prevent possible consequences and accidents., Methods: Knudsen effusion mass spectrometry was used to determine partial pressures of vapor species over the SrO-CeO 2 and CaO-CeO 2 systems. Measurements of partial pressures were performed with a MS-1301 mass spectrometer. Vaporization was carried out using molybdenum or tungsten effusion cells. A theoretical study of gaseous strontium and calcium cerates was performed by several quantum chemical methods: density functional theory (DFT) M06, DFT PBE0, and MP2., Results: The minimum value of relative electron ionization cross-section for CeO 2 was estimated. In the temperature range of 2218-2249 K above the SrO-CeO 2 system and of 2128-2208 K above the CaO-CeO 2 system, gaseous M, MO, MO, CeO 2 , O, O 2 and MCeO 3 (M = Sr, Ca) were found. Energetically favorable structures of gaseous SrCeO 3 and CaCeO 3 were found, and vibrational frequencies were evaluated in the "rigid rotor-harmonic oscillator" approximation. On the basis of the equilibrium constants of gaseous reaction MO + CeO 2  = MCeO 3 , the standard formation enthalpy of gaseous SrCeO 3 (-913 ± 26 kJ/mol) and of gaseous CaCeO 3 (-917 ± 26 kJ/mol) at 298 K were determined., Conclusions: The estimated value of relative electron ionization cross-section for CeO 2 is in agreement with the general rule applicable for dioxides. The stability of SrCeO 3 and CaCeO 3 gaseous species was confirmed by KEMS. Gas-phase reactions involving gaseous SrO (CaO) and CeO 2 with gaseous SrCeO 3 (CaCeO 3 ) were studied. Enthalpy of formation reaction of gaseous SrCeO 3 (CaCeO 3 ) from gaseous SrO (CaO) were evaluated theoretically, and the obtained value is in agreement with the experimental one., (© 2024 John Wiley & Sons Ltd.)