Influence of Cr doping on the phase composition of Cr,Ca:YAG ceramics by solid state reaction sintering

In the present work, the influence of Cr and Ca co-additives on the phase formation under conditions emulated the real sintering process of Cr⁴⁺:YAG ceramics is studied. The XRD analysis of the treated samples revealed the difference in formation rates of intermediate phases between the samples with and without the Cr₂O₃ additive. The formation of intermediate phases in the solid-state reaction between Y₂O₃ and Al₂O₃ is observed to shift toward higher temperatures (ie, toward the stage of fast shrinkage) if the mixture of Cr₂O₃ and CaO is added. The reason for such shift is the appearance of new intermediate, which contains Cr⁴⁺ ions in perovskite structure, as has been established by optical absorption and luminescent investigations. It is found that the Cr,Ca:YAG ceramics prepared by vacuum solid state reaction sintering at 1750°C, 10 hours possesses better optical transparency than Ca:YAG ceramics prepared under the same conditions.     

3D Electrophoresis‐Assisted Lithography (3DEAL): 3D Molecular Printing to Create Functional Patterns and Anisotropic Hydrogels

The ability to easily generate anisotropic hydrogel environments made from functional molecules with microscale resolution is an exciting possibility for the biomaterials community. This study reports a novel 3D electrophoresis‐assisted lithography (3DEAL) platform that combines elements from proteomics, biotechnology, and microfabrication to print well‐defined 3D molecular patterns within hydrogels. The potential of the 3DEAL platform is assessed by patterning immunoglobulin G, fibronectin, and elastin within nine widely used hydrogels and characterizing pattern depth, resolution, and aspect ratio. Furthermore, the technique's versatility is demonstrated by fabricating complex patterns including parallel and perpendicular columns, curved lines, gradients of molecular composition, and patterns of multiple proteins ranging from tens of micrometers to centimeters in size and depth. The functionality of the printed molecules is assessed by culturing NIH‐3T3 cells on a fibronectin‐patterned polyacrylamide‐collagen hydrogel and selectively supporting cell growth. 3DEAL is a simple, accessible, and versatile hydrogel‐patterning platform based on controlled molecular printing that may enable the development of tunable, chemically anisotropic, and hierarchical 3D environments.     

A reservoir radial-basis function neural network in prediction tasks

A reservoir radial-basis function neural network, which is based on the ideas of reservoir computing and neural networks and designated for solving extrapolation tasks of nonlinear non-stationary stochastic and chaotic time series under conditions of a short learning sample, is proposed in the paper. The network is built with the help of a radial-basis function neural network with an input layer, which is organized in a special manner and a kernel membership function. The proposed system provides high approximation quality in terms of a mean squared error and a high convergence speed using the second-order learning procedure. A software product that implements the proposed neural network has been developed. A number of experiments have been held in order to research the system’s properties. Experimental results prove the fact that the developed architecture can be used in Data Mining tasks and the fact that the proposed neural network has a higher accuracy compared to traditional forecasting neural systems.     

Generation of novel landomycins M and O through targeted gene disruption

Two genes from Streptomyces cyanogenous S136 that encode the reductase LanZ4 and the hydroxylase LanZ5, which are involved in landomycin A biosynthesis, were characterized by targeted gene inactivation. Analyses of the corresponding mutants as well as complementation experiments have allowed us to show that LanZ4 and LanZ5 are responsible for the unique C-11-hydroxylation that occurs during landomycin biosynthesis. Compounds accumulated by the lanZ4/Z5 mutants are the previously described landomycin F and the new landomycins M and O.     

Broadening of neutral analyte band in electroosmotic flow through slit channel with different zeta potentials of the walls

The study is concerned with addressing hydrodynamic dispersion of an electroneutral non-adsorbed solute being transported by electroosmotic flow through a slit channel formed by walls with different zeta potentials. The analysis is conducted in terms of the plate height which, using the Van Deemter equation, can be expressed through the cross-sectional mean flow velocity, the solute molecular diffusion coefficient and a length scale parameter having meaning of the minimum achievable plate height and depending on the velocity distribution within the channel cross-section. The minimum plate height is determined by substituting distribution of electroosmotic velocity into the preliminary derived integral expression that is valid for any given velocity distribution within a slit channel cross-section. The electroosmotic velocity distribution within the slit channel cross-section is obtained by solving one-dimensional version of the Stokes equation accounting for electric force exerted on the local equilibrium electric space charge. The major obtained result is an analytical expression which represents the minimum plate height normalized by half of channel width as a function of two dimensionless parameters, namely, half of channel width normalized by the Debye length, and the ratio of the wall zeta potentials. The obtained result reveals a substantial increase in the minimum plate height compared with the case of equal wall zeta potentials. Different limiting cases of the obtained relationships are analyzed and possible applications are discussed.     

Physical and Mechanical Aspects of Corrosion Damage of Distribution Gas Pipelines After Long-Term Operation

The fractographic analysis of the corrosion damage of the pipe surface of the distribution gas pipeline after 40 and 56 years of operation is performed. The mechanisms of formation of corrosion pits, laminations, and deep crack-like defects are systematized. On the basis of laboratory studies, which simulate operation conditions of a distribution gas pipeline in corrosive medium, the basic regularities in general corrosion of steel St. 3 in neutral chloride electrolytes are determined, depending on the value of the current density and chemical composition of the medium.     

What makes a nano-channel? A limiting-current criterion

It is shown theoretically that the occurrence of limiting currents at micro-/nano-interfaces critically depends on the ratio of nano-channel height (nano-pore size) and the Debye screening length. If this ratio is sufficiently large (>ca.6 for slit-like nano-channels, for example), the limiting-current phenomenon is suppressed due to the electroosmotic transfer of salt toward the polarized micro-/nano-interface. Therefore, not too narrow nano-channels effectively behave like micro-channels in the limiting-current terms. It is suggested that this qualitative change in the behavior can be used as a signature of “genuine” nano-channels. It is also shown that some recent experimental findings on the concentration polarization of joined micro-/nano-fluidic systems can be explained by using this criterion.     

Rheological Properties of Russian Crude Oil

Russia has 7.2 billion tons of difficult to produce, high-viscosity (over 30) crude oils. The reserves of these crudes are concentrated in 267 fields [1]. The Russian field located within the Polar circle — in the Gas Region of the Yamal-Nenets Autonomous District in Tyumen Oblast', is one of the largest. This field, opened in 1968, has total crude oil reserves of up to 1.5 billion tons. Its industrial exploitation has not yet begun.     

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