Silver sulfide is a polymorphic material that exists in different crystalline forms including 3D structures with different symmetries, quasi‐2D layers, and 0D quantum dots. The crystal structures of ...identified and characterized to date forms of Ag2S differ, and so do their electronic properties. In the past, two different bulk crystalline phases of Ag2S with the same symmetry have been characterized experimentally. Herein, an empirical relation is proposed, which allows for the identification of these experimentally observed structures of Ag2S as thermodynamically stable and predicts a new, potentially stable, crystalline phase of this material. The band structures of these three phases are investigated using computational quantum methods. The calculations are performed using the hybrid density functional approximation and quasiparticle partially self‐consistent GW method. The effects of crystal structure on the semiconductor properties are discussed based on the results obtained for the three crystalline structures. The findings, reported in this work, can be of significance for technological applications that exploit the electronic properties of crystalline Ag2S.
Using experimental data on two known phases of Ag2S, an empirical relation that has the potential to predict potentially stable structures is proposed. By employing this relation and performing density functional theory based analysis of energetic stability, a new phase of Ag2S is found. The relationships between structure and electronic properties of the three phases of Ag2S are discussed.
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The microbiomes of the soils buried under earthwork structures of different age (burial mounds and defensive earth walls) and of surface soils were investigated. Microbial DNA was analyzed by ...quantitative PCR and sequencing of the 16S rRNA gene amplicons. Both microbial abundance and diversity in buried soils were found to be lower. The taxonomic structure of the buried soil microbiomes differed significantly from that of surface soils: the share of the bacterial phylum
Verrucomicrobia
was very low. The thickness of the earthwork structure should be sufficient to isolate soil from the effect of plant roots; otherwise, the microbiome may exhibit virtually no difference from that of surface soils. The degree of mineralization of stored organic matter (in the absence of inflow of fresh organic compounds) is probably the main factor affecting the structure of microbial communities in buried soils. The study did not reveal any properties of the microbiomes usable as markers of the type of buried soils.
Objectives. The aim is to justify the expediency of a transition en masse to independent connection of heat consumption systems under the conditions of pulse circulation of the coolant through the ...equipment of a heat supply unit in order to increase the overall energy efficiency of district heat supply systems.Methods. The research is based on methodologies for the effective use of technologies providing a means of effecting a pulsed motion of the coolant in the heat supply system. The advantages and disadvantages of known technical solutions are identified and summarised. Hydraulic accumulators or any other devices for damping a hydraulic shock can be used as devices for preventing the propagation of a wave of hydraulic shock into the transport mainline.Results. An analysis of approaches to heat consumption system connection is carried out in order to assess power efficiency; the most effective ways for improving the efficiency of heat and power devices are identified; a synthesis of the technical solution for the implementation of a technological connection of heat consumption systems is performed. The expediency of transition to independent connection of heat consumption systems under the conditions of pulse circulation of coolant in heat supply units is demonstrated. The independent scheme of connection of subscribers to the heat network is indicated as the most appropriate. The factors constraining the en masse transition to independent connection of the heat load are determined. Based on the analysis and scientific research in the field of increasing the energy efficiency of heat and power systems, the transition to pulse circulation of the coolant in the heat supply unit of the independent heat consumption system is selected. The presented technical solutions are confirmed by Russian Federation patents of inventions and utility models.Conclusion. It is shown that the use of pulse coolant circulation in the equipment of heat supply units for independent connection of heat consumption systems will increase the reliability and long-term operation of the recuperative heat exchanger, as well as increase the overall energy efficiency of the heat supply system.
A lidar complex designed at V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences (Tomsk) and used at the Siberian Lidar Station (56.5° N, 85.0° W) for the study of ...ozone dynamics near tropopause and for tracking global ozonosphere changes is presented. It allows measurements of ozone vertical distribution in the upper troposphere–stratosphere when sounding using the differential absorption technique at the wavelength pairs 299/341 and 308/353 nm. The lidar complex covers altitudes from ∼5 to ∼45 km.
Results are provided for calculation of the material and heat balances of cast iron smelting in a Romelt furnace using coal with a different fixed carbon content with addition of natural gas to the ...blast of the lower tuyeres. It is shown that under constant heat flow conditions due to gas combustion in the slag bath an increase in natural gas consumption is accompanied by a reduction in coal consumption. In this case saving coal does not depend on its form and is proportional to natural gas consumption. An increase in natural gas consumption is accompanied by a reduction in oxygen consumption in the lower tuyeres and an increase in the upper tuyeres. Saving oxygen in the Romelt process is at a maximum for coal with a low fixed carbon content. It decreases as there is an increase in fixed carbon content and with ≈ 75% C
fix
saving oxygen is replaced by a small over-consumption.
The simplest stochastic lattice model of an excitable medium is considered. Each lattice cell can be in one of three states: excited, refractory, or quiescent. Transitions between different cell ...states occur with the prescribed probabilities. The model is designed for studying the transfer of excitation in the cardiac muscle and nerve fiber at the cellular and subcellular levels, and also for modeling the spreading of epidemics. Elementary events on the lattice are simulated by the kinetic Monte Carlo method, which consists in constructing a Markov chain of the lattice states corresponding to the solution of the master equation. An effective algorithm for implementing the Kinetic Monte Carlo simulations is suggested. The number of the arithmetic operations at each time step of the proposed algorithm is practically independent of the lattice size, which enables making calculations on two- and three-dimensional lattices of a very large size (more than 10
9
cells). It is shown that the model reproduces the basic spatiotemporal structures (solitary traveling pulses, pulse trains, concentric and spiral waves, and spiral turbulence) characteristic of an excitable medium. The basic properties of traveling pulses and spiral waves for the considered stochastic lattice model are studied and compared with the known properties of deterministic equations of the reaction-diffusion type, which are usually employed for modeling excitable media.
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