STRONTIUM DISTRIBUTION IN UPPER DEVONIAN CONODONT ELEMENTS: A PALAEOBIOLOGICAL PROXY

Conodonts are an extinct group of marine animals possessing debated affinities. The conodont elements are composed of calcium phosphate [apatite (CaF)] and collagen-like proteins. Distribution of Sr in the bioapatite of albid, lamellar and paralamellar tissues of some Upper Devonian conodont element crowns from NW Russia was studied by microprobe. The calcium phosphate of the lamellar and paralamellar tissues demonstrates periodical oscillation of Sr contents across the lamellae (0.4-0.5 wt% in the outer part of lamella, and 0.2 wt% in the inner part). The albid tissue contains Sr of less than 0.4 wt%. It is suggested that oscillations of Sr concentrations reflect the periodic growth of the lamellae, and the average Ca/Sr ratio can be a proxy of the growth rate

OPTIMIZATION OF MECHANICAL STRENGTH OF ROTARY-VANE ENGINE

The article discusses a rotory-vane heat engine with a lever-cam mechanism motion conversion (an engine may be an internal combustion or external combustion). The output shaft of the engine adds drive torque from the working fluid pressure forces acting on the blade and the inertial moment of the forces of inertia of engine components. The mechanical strength of the motor is dependent on the magnitude and phase of these two torque. The purpose of the article is to determine the conditions under which mechanical strength is minimized

Life Has Become More Joyous, Comrades : the construction of the Soviet consumer culture

En este artículo, el objetivo es el de describir el origen y construcción de la cultura del consumo en la Unión Soviética, prestando atención particular a uno de sus ejemplos icónicos, como es la cultura alimentaria. Nuestro texto se dividirá en tres secciones. En la primera, haremos referencia a la peculiar y original construcción de la sociedad de consumo soviética, en pleno estalinismo. En la segunda, nos concentraremos en el espacio concreto del consumo alimentario, con referencia en particular a dos cuestiones: el desarrollo de los servicios de restauración y algunos de los bienes asociados a esta nueva cultura de consumo, como el champán. Finalmente, la última sección de conclusiones se hará una valoración crítica de esta peculiar forma de sociedad de consumo.Peer reviewe

DETERMINATION OF CHAMBER AND PISTON GEOMETRY FOR A ROTARY TYPE EXPANSION MACHINE

The article deals with the determination of chamber and piston geometry for a rotary expansion machine. Analytical expressions for the working surface area of piston and for chamber volume are derived. Three defining parameters of the expansion machine were obtained: gas dynamic machine constant Cp; constant M0 connecting torque and Cp; the main dimensionless parameter of the machine Q0, which relates the volume of the chamber and the torque

CONSTRUCTION OF PISTON OUTER PROFILE FOR ROTARY TYPE EXPANSION MACHINE

The article discusses methods for constructing piston outer profile for the rotary type expansion machine in order to reduce unwanted (parasitic) volumes and offers options for constructing outer profile of piston using analytical and geometric methods

SYNTHESIS OF A LEVER-CAM MOTION TRANSDUCER FOR A ROTARY VANE PUMP

The article solves problem of synthesizing a lever-cam motion transducer that converts rotary motion of input shaft of a rotary pump into motion of its vanes required for volumetric pumping of gases and liquids. Analytical expressions for theoretical profile of cam of lever-cam transducer of the movement of rotary vane pump are obtained. The cam profile was built according to analytical expressions.

Ab initio calculations of optical constants of GaSe and InSe layered crystals

The dielectric functions, refractive indices, and extinction coefficients of GaSe and InSe layered crystals have been calculated within the density functional theory. The calculations have been performed for the values of theoretical structural parameters optimized using the exchange-correlation functional, which allows one to take into account the dispersion interactions. It has been found that optical functions are characterized by the most pronounced polarization anisotropy in the range of photon energies of ∼4–7 eV. The frequency dependences for InSe compound in the range up to 4 eV demonstrate the more pronounced anisotropy as compared to GaSe. The results obtained for GaSe crystal agree better with the experimental data as compared to the previous calculations

Thermal equation of state and stability of (Mg_(0.06)Fe_(0.94))O

We present the pressure-volume-temperature (P-V-T) equation of state of polycrystalline (Mg_(0.06)Fe_(0.94))O (Mw94) determined from laser-heated x-ray diffraction experiments up to 122 GPa and 2100 K, conditions approaching those of the deep mantle. We conducted two sets of experiments, one with an in situ Fe metal oxygen fugacity buffer and one without such a buffer. The internal pressure markers used in these experiments were B2-NaCl and hcp-Fe in the buffered experiment and B2-NaCl in the unbuffered experiment. In the sampled P-T range of the high temperature part of this study, only the B1 structure of Mw94 was observed, indicating that the addition of Mg to FeO stabilizes the B1 phase with respect to the B8 phase at these conditions. Both datasets were fit to a Birch-Murnaghan and Mie-Grüneisen-Debye thermal equation of state using a new open-source fitting routine, also presented here. Analysis of these data sets using the same internal pressure marker shows that the P–V–T data of Mw94 obtained in the unbuffered experiment are well explained by the equation of state parameters determined from the buffered data set. We have also compared the thermal equation of state of Mw94 with that of wüstite and conclude that Mw94 has measurably distinct thermoelastic properties compared with those of wüstite. We use the results obtained in the buffered experiment to determine the density and bulk sound velocity of Mw94 at the base of the mantle and compare these values to geophysical observations of ultralow-velocity zones

All-Glass Single-Mode Leakage Channel Microstructured Optical Fibers with Large Mode Area and Low Bending Loss

The paper presents the results of theoretical and experimental studies of all-glass leakage channel microstructured optical fibers (MOFs) with a large mode area and low bending losses. These MOFs contain two layers of fluorine-doped silica glass elements with a reduced refractive index, different diameters, and different distances between them. A numerical analysis of the properties of these MOFs was performed using the finite element method. The leakage losses for the fundamental and higher-order modes were calculated in the spectral range from 0.65 μm to 1.65 μm. Simulation results show that the proposed MOF design allows for single-mode guidance in the spectral range from 0.92 μm to 1.21 μm with a bending radius of down to 0.08 m. The measured losses of the fabricated MOF with a core diameter of 22.5 μm and a bending radius of 0.1 m were less than 0.1 dB/m in the spectral range from 0.9 μm to 1.5 μm. It is demonstrated that the segments of this MOF longer than 5 m are single-mode