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.
A number of novel 2,3,4,5-tetrahydro1,3diazepino1,2-abenzimidazole derivatives 2 were obtained by alkylation mainly in the 1H-tautomeric form of 2,3,4,5-tetrahydro1,3diazepino1,2-abenzimidazole or ...its 8,9-dimethyl-substituted analog 4-chlorobenzyl bromide, 4-chloroacetic acid fluoroanilide, and 4-tert-butylphenacyl bromide in neutral medium. Compounds 3 were cyclized and synthesized earlier with 11-phenacyl-substituted diazepino1,2-abenzimidazoles upon heating in conc. HBr. The chemical structures of the compounds were clarified by using the 1H Nuclear Magnetic Resonance Spectroscopy (1H-NMR) technique. Anxiolytic properties were evaluated using the elevated plus maze (EPM) and open field (OF) tests. The analgesic effect of compounds was estimated with the tail flick (TF) and hot plate (HP) methods. Besides, possible the influence of the test compounds on motor activities of the animals was examined by the Grid, Wire, and Rotarod tests. Compounds 2d and 3b were the most active due to their prominent analgesic and anxiolytic potentials, respectively. The results of the performed in silico analysis showed that the high anxiolytic activity of compound 3b is explained by the combination of a pronounced interaction mainly with the benzodiazepine site of the GABAA receptor with a prominent interaction with both the specific and allosteric sites of the 5-HT2A receptor.
The elucidation of the reaction rate-determining step nature in intercalation processes is essential for the development of approaches for the precise control of rate-limiting factors. In this work, ...we explore the kinetic patterns of lithium-ion intercalation into two model cathode materials (LiCoO2 and LiMn2O4) and develop criteria for distinguishing between Butler-Volmer slow charge transfer and slow chemical steps. A numerical model for the rate-limiting ion desolvation step is developed and the predictions of the model are compared with the experimental voltammetric and electrochemical impedance spectroscopy data. We show that slow desolvation step results in essential changes in the shape of both cyclic voltammetry and impedance responses with the kinetic resistance vs. potential dependencies being highly informative for the reaction rate control diagnostics. The consideration of the intercalation kinetics in four solvents (water, propylene carbonate, acetonitrile and dimethyl sulfoxide) allows concluding on the influence of the resistivity of surface layer/electrode material interface on the reaction slow step nature.
•Charge transfer rate vs. potential dependence is defined by the slow step nature.•Charge transfer rates depend sharply on the presence of SEI layers.•In SEI-free systems charge transfer rates are exceedingly fast.•Desolvation step results in a weak charge transfer rate vs. potential dependence.•Ion desolvation limiting step induces asymmetry in voltammetric responses.
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.
The rational homology group of the order complex of non-even partitions of a finite set is calculated. A twisted version of Goresky–MacPherson approach to similar homology calculations is proposed.
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.
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•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.
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.
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•Thermodynamic modeling of the system Cu-In-Zn.•Calculation of five vertical sections and two isothermal sections.•Calculated liquidus surface projection.
Context. The Cherenkov Telescope Array (CTA) represents the most advanced facility designed for Cherenkov Astronomy. ASTRI SST-2M has been developed as a demonstrator for the Small Size Telescope in ...the context of the upcoming CTA. Its main innovation consists in the optical layout which implements the Schwarzschild-Couder configuration and is fully validated for the first time. The ASTRI SST-2M optical system represents the first qualified example of a two-mirror telescope for Cherenkov Astronomy. This configuration permits us to (i) maintain high optical quality across a large field of view; (ii) demagnify the plate scale; and (iii) exploit new technological solutions for focal plane sensors. Aims. The goal of the paper is to present the optical qualification of the ASTRI SST-2M telescope. The qualification has been obtained measuring the point spread function (PSF) sizes generated in the focal plane at various distances from the optical axis. These values have been compared with the performances expected by design. Methods. After an introduction on Gamma-ray Astronomy from the ground, the optical design of ASTRI SST-2M and how it has been implemented is discussed. Moreover, the description of the set-up used to qualify the telescope over the full field of view is shown. Results. We report the results of the first–light optical qualification. The required specification of a flat PSF of ~ 10 arcmin in a large field of view (~ 10°) has been demonstrated. These results validate the design specifications, opening a new scenario for Cherenkov Gamma-ray Astronomy and, in particular, for the detection of high-energy (5–300 TeV) gamma rays and wide-field observations with CTA.
We theoretically and experimentally demonstrate that the light shift of the coherent population trapping resonance frequency depends on the buffer gases pressure. The light shift suppression becomes ...impossible when a certain value of the buffer gases pressure is exceeded. We estimate the minimal dimensions of an atomic cell at which the zero light shift and the lowest ground-state relaxation rate can be achieved simultaneously. A new technique of the light shift cancellation by means of a feedback utilizing the RF power modulation is proposed.
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