The effect of temperature on the development of nanosized nucleus iron-oxygen structures in Fe<Superscript>0</Superscript>-H<Superscript>2</Superscript>O-O<Superscript>2</Superscript> Systems

The formation of nucleus iron-oxygen structures in Fe⁰-H₂O-O₂ systems has been investigated. It has been shown that temperature affects the rate of iron(II) oxidation and, accordingly, the composition of components involved in phase formation. At 10°C, only nucleus structures of protolepidocrocites are formed on the surface; at 20–40°C, structures of protolepidocrocites and ferrihydrite; and at 50–70°C, structures of magnetite and FeO. The analysis of thermodynamic functions has revealed the most probable formation reactions of nucleus iron-oxygen structures and the optimal conditions for the structure formation in morphological series.     

Synergism in combustion processes

The effect of CF₃H, CF₄, and N₂ on the ignition of methane–air mixtures has been investigated. The effect of trifluoromethane is due to its being involved in reaction chain termination. A nonadditive effect of trifluoromethane and nitrogen on the concentration limits of ignition and flame propagation in methane–air mixtures has been predicted and revealed. The synergistic effect arises from the exponential dependence of the rate of the chain process on the concentrations of the initial components.     

A Maximum Entropy Model of Bounded Rational Decision-Making with Prior Beliefs and Market Feedback

Bounded rationality is an important consideration stemming from the fact that agents often have limits on their processing abilities, making the assumption of perfect rationality inapplicable to many real tasks. We propose an information-theoretic approach to the inference of agent decisions under Smithian competition. The model explicitly captures the boundedness of agents (limited in their information-processing capacity) as the cost of information acquisition for expanding their prior beliefs. The expansion is measured as the Kullblack–Leibler divergence between posterior decisions and prior beliefs. When information acquisition is free, the homo economicus agent is recovered, while in cases when information acquisition becomes costly, agents instead revert to their prior beliefs. The maximum entropy principle is used to infer least biased decisions based upon the notion of Smithian competition formalised within the Quantal Response Statistical Equilibrium framework. The incorporation of prior beliefs into such a framework allowed us to systematically explore the effects of prior beliefs on decision-making in the presence of market feedback, as well as importantly adding a temporal interpretation to the framework. We verified the proposed model using Australian housing market data, showing how the incorporation of prior knowledge alters the resulting agent decisions. Specifically, it allowed for the separation of past beliefs and utility maximisation behaviour of the agent as well as the analysis into the evolution of agent beliefs.     

Ion Beam Generation in a Vacuum Arc Ion Source with a Multicomponent Cathode

Russian Physics Journal - Vacuum arc ion sources are widely used for modifying the properties of various surfaces using ion implantation. The use of cathodes consisting of multicomponent compounds...     

Structural and magnetic inhomogeneity, phase transitions, magnetoresonance and magnetoresistive properties of La0.6 − x Pr x Sr0.3Mn1.1O3 (x = 0–0.6)

Ceramic samples of manganite perovskites La_{0.6 ? x} Pr _x Sr_0.3Mn_1.1O₃ (x = 0?0.6) have been studied using the X-ray diffraction, resistive, magnetic (χ_ac, ⁵⁵Mn NMR), microscopic, and magnetoresistive methods. It has been found that an increase in the praseodymium concentration x leads to a transition from the rhombohedral R $\bar 3$ c (x = 0–0.3) to orthorhombic Pbnm (x = 0.4–0.6) perovskite structure. It has been shown that the real perovskite structure contains anion and cation vacancies, whose concentrations increase with an increase in the praseodymium concentration x. A decrease in the metal-insulator phase transition temperature T _mi and the ferromagnetic-paramagnetic phase transition temperature T _c with increasing x correlates with an increase in the concentration of vacancies weakening the high-frequency electronic exchange Mn³⁺ ? Mn⁴⁺. For compositions with x = 0 and 0.1, when the lattice contains not only vacancies but also nanostructured clusters with Mn²⁺ in the A-positions, there is an anomalous hysteresis. An analysis of the asymmetrically broadened ⁵⁵Mn NMR spectra of the compounds has revealed a high-frequency electronic exchange of the ions Mn³⁺ Mn⁴⁺ in the B-positions and a local heterogeneity of their surrounding by other ions (La²⁺, Pr³⁺, Sr²⁺) and vacancies. The phase diagram has demonstrated that there is a strong correlation between the composition, imperfection of the perovskite structure, phase transition temperatures T _mi and T _c , and magnetoresistive properties.     

Vibrations of ribbed shallow rectangular shells on an elastic foundation

A procedure to determine the natural frequencies and modes of ribbed shallow shells with rectangular planform on an elastic foundation is developed. The effect of the radius of curvature and the Winkler and Pasternak coefficients of subgrade reaction on the natural frequencies and modes of a shallow spherical shell with a square planform is analyzed. It is revealed that not only the natural frequencies but also the modes of the shell depend on the coefficients of subgrade reaction     

Synthesis of 4-hetaryl-substituted 5-amino- and 5-sulfanyl-1,3-oxazole derivatives

Previously unknown 5-amino- and 5-sulfanyl-1,3-oxazole derivatives containing a 1,3,4-oxadiazole, 1,3,4-thiadiazole, or 1,2,4-triazole fragment at C⁴ were synthesized from accessible 1,3-oxazole-4-carboxylic acid hydrazides.     

Low-Frequency Spectrum of the Gyrotropic Modes of a Finite Chain of Interacting Ferromagnetic Disks

Technical Physics - The problem of the frequency spectrum of collective gyrotropic modes in a finite linear chain of magnetostatically interacting ferromagnetic disks has been considered. It has...     

Rules governing flame propagation in fuel-deficient hydrogen-air mixtures in cylindrical reactors

The special features of flame propagation in hydrogen-air mixtures with low hydrogen contents in horizontal cylindrical reactors with different diameters were studied. The dependences of the lower concentration limit of flame propagation and flame propagation velocity on the diameter of reactors and the chemical properties of the surface were determined. The character of the dependence of the flame cellular structure on mixture composition and reactor diameter was studied.