Mechanochemical synthesis and thermal stability of phases in the Y2O3–Yb2O3 system

Substitutional, continuous solid solution of the general formula Y_2–xYb_xO₃ was obtained from the mixture of Y₂O₃ and Yb₂O₃ oxides, for the first time by the mechanochemical method in a high-energy ball milling. The monophasic samples of nanocrystalline solid solution for x?>?0.00 and x?<?2.00 were examined by the methods: XRD, DTA, SEM, IR and UV–Vis–DR. As follows from the results, the solid solution crystallizes in cubic system and is isostructural with Y₂O₃ and Yb₂O₃. The solution is stable in the air atmosphere up to at least 900°C, and its decomposition temperature decreases with the increase in x, that is, with decreasing number of Yb³⁺ ions replacing Y³⁺ ions in the crystal lattice of Y₂O₃. The energy band gap estimated for the solid solution varies from?~?5.30 eV for x?=?0.50 to?~?4.90 eV for x?=?1.50, which means that it is an insulator.

     

Allosteric Modulation of the CB1 Cannabinoid Receptor by Cannabidiol—A Molecular Modeling Study of the N-Terminal Domain and the Allosteric-Orthosteric Coupling

The CB₁ cannabinoid receptor (CB₁R) contains one of the longest N termini among class A G protein-coupled receptors. Mutagenesis studies suggest that the allosteric binding site of cannabidiol (CBD) involves residues from the N terminal domain. In order to study the allosteric binding of CBD to CB₁R we modeled the whole N-terminus of this receptor using the replica exchange molecular dynamics with solute tempering (REST2) approach. Then, the obtained structures of CB₁R with the N terminus were used for ligand docking. A natural cannabinoid receptor agonist, Δ⁹-THC, was docked to the orthosteric site and a negative allosteric modulator, CBD, to the allosteric site positioned between extracellular ends of helices TM1 and TM2. The molecular dynamics simulations were then performed for CB₁R with ligands: (i) CBD together with THC, and (ii) THC-only. Analyses of the differences in the residue-residue interaction patterns between those two cases allowed us to elucidate the allosteric network responsible for the modulation of the CB₁R by CBD. In addition, we identified the changes in the orthosteric binding mode of Δ⁹-THC, as well as the changes in its binding energy, caused by the CBD allosteric binding. We have also found that the presence of a complete N-terminal domain is essential for a stable binding of CBD in the allosteric site of CB₁R as well as for the allosteric-orthosteric coupling mechanism.     

Phase Relations in The V2O5–MoO3–α-Sb2O4 System in The Solid State in Air Atmosphere

The phase equilibria established in the V₂O₅–MoO₃–α-Sb₂O₄ system in the solid state in an air atmosphere were examined by using XRD and DTA methods. The obtained results allowed us to find that in this system a novel compound is formed involving three oxides. Its formula can be written as Sb₃V₂Mo₃O₂₁. The synthesis of this compound requires picking up the atmospheric oxygen. X-ray characteristics of this compound were determined and it was found that it melted incongruently at 740°C. The results obtained until now allow us to divide the investigated V₂O₅–MoO₃–α-Sb₂O₄ system into five partial subsystems. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and Properties of The Solid Solutions Formed in The Fe2V4O13–Cr2V4O13 System

DTA and XRD studies of the Fe₂V₄O₁₃–Cr₂V₄ O₁₃ system have shown that continuous solid solutions of a Fe_2–xCr_xV₄O₁₃ type, bearing a Fe₂ V₄ O₁₃ structure, are formed in the system. With the increasing degree of the Cr3+ ion incorporation into the Fe₂ V₄ O₁₃ structure, a contraction of the solid solution crystal lattice develops. Solid solutions of a Fe_2–x Cr_x V₄ O₁₃ type melt incongruently, their melting temperature increasing from 953 to 1003 K with increase in the degree of the Cr³⁺ ion incorporation. The solid product of melting Fe_2–x Cr_x V₄ O₁₃ solid solutions for 0.2<x >1.2 is the Fe_1–x Cr_x VO₄ solution phase, and for x ≤0.2 and x ≥1.4 – the Fe_1–x Cr_x VO₄ phase as well as FeVO₄ or CrVO₄ , respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Phase equilibria up to the solidus line in the V2O5-CrVMoO7 system

The phase equilibria being established in the V₂O₅-CrVMoO₇ system in the solid state and the whole component concentration range have been studied by the X-ray powder diffraction and thermal analysis methods. The measurements have shown that the V₂O₅-CrVMoO₇ system is not a real two-component system in the subsolidus area.

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Zusammenfassung Mittels Thermoanalyse und Debye-Scherrer-Verfahren wurde das Phasengleichgewicht im Feststoffsystem V₂O₅-CrVMoO₇ im gesamten Konzentrationsbereich untersucht. Die Messungen zeigen, daß es sich bei dem System V₂O₅-CrMoO₇ im Bereich unter Solidus um kein echtes Zweikomponentensystem handelt.

     

The FeVO4-MoO3 system

A phase diagram of the FeVO₄-MoO₃ system has been constructed from the results of DTA and X-ray analysis. The components of the system form a compound FeVMoO₇. This compound melts incongruently at 680±5 °C, with separation of the solid Fe₄V₂Mo₃O₂₀.     

EDS X-Ray Investigation of Interdiffusion in Au–Ni Micro- and Nanolayers

The interdiffusion process in thin and thick (500nm–60µm) Au–Ni layers deposited on different substrates is studied using the EDS technique. In-depth X-ray analysis based on the Pouchou and Pichoir method is applied for obtaining the concentration profiles in nanometre scale multi-layers. A theoretical analysis using the Darken method is employed for modelling interdiffusion in the Au–Ni system. Computer simulations, where intrinsic diffusivities of the Au and Ni are functions of composition, are presented and compared with experimental results.     

Mechanistic Studies on the Stereoselectivity of the Serotonin 5‐HT1A Receptor

G‐protein‐coupled receptors (GPCRs) are involved in a wide range of physiological processes, and they have attracted considerable attention as important targets for developing new medicines. A central and largely unresolved question in drug discovery, which is especially relevant to GPCRs, concerns ligand selectivity: Why do certain molecules act as activators (agonists) whereas others, with nearly identical structures, act as blockers (antagonists) of GPCRs? To address this question, we employed all‐atom, long‐timescale molecular dynamics simulations to investigate how two diastereomers (epimers) of dihydrofuroaporphine bind to the serotonin 5‐HT_1A receptor and exert opposite effects. By using molecular interaction fingerprints, we discovered that the agonist could mobilize nearby amino acid residues to act as molecular switches for the formation of a continuous water channel. In contrast, the antagonist epimer remained firmly stabilized in the binding pocket.     

Active and passive structural acoustic control of the smart beam

Structural noise and vibrations control can be achieved using two strategies: active - with feed-forward controller, a sensor and an actuator [1-3] or passive, by piezoelectric shunt damping [4-8], when a piezoelectric transducer will act as a sensor and an actuator. Potential applications of these structures are investigated. Two numerical (FEM) models based on the active and passive damping strategies are compared. The numerical solutions were confirmed experimentally.