The Dust Mass of Supernova Remnants in M31

The dust temperature and mass of the supernova remnants (SNRs) in M31 are estimated by fitting the infrared spectral energy distribution calculated from the images in the Spitzer/IRAC4 and MIPS24, Herschel/PACS70, 100, and 160, and Herschel/SPIRE 250 and 350 μm bands. Twenty SNRs with relatively reliable photometry exhibit an average dust temperature of 20.1 − 1.5 + 1.8 K, which is higher than the surrounding and indicating the heating effect of supernova explosion. The dust mass of these SNRs ranges from about 100 to 800 M ⊙, much bigger than the SNRs in the Milky Way. On the other hand, this yields the dust surface density of 0.10 − 0.04 + 0.07 M ⊙ pc−2, about half of the surrounding area, which implies that about half dust in the SNRs is destroyed by the supernova explosion. The dust temperature, the radius, and thus the dust mass all demonstrate that the studied SNRs are old and very likely in the snowplow or even fade-away phase because of the limitation by the far distance and observation resolution of M31, and the results can serve as a reference to the final effect of supernova explosion on the surrounding dust.

Effect of ion beam current on dust charge fluctuations and ion-acoustic waves in electronegative dusty plasmas

The effects of ion beam current associated with the streaming positive ions on the dust charge fluctuations and ion acoustic wave propagation in quiescent electronegative dusty plasma have been investigated using fluid theory. The dust charging phenomenon and unstable mode of ion waves are modified for two streaming conditions of positive ions which are extended and graphically illustrated. The dependencies of the growing and damping rate of ion waves on dust density and the size of dust grains are studied. The evolution of dust surface potential is found in the negative domain with the increase in concentration of negative ions and the instability rate for ion wave decreases. Furthermore, it is shown that the dust surface potential shifts into positive domain as the electrons are significantly depleted (and the plasma becomes ion-ion plasma) from the electronegative plasma and thus ion waves exhibit a damping phenomenon.

The Issue of Shading Photovoltaic Installation Caused by Dust Accumulation on the Glass Surface

The issue of accumulation of dust and other pollutants on the surface of photovoltaic modules was thoroughly analysed over the years. One of the first surveys in this field of knowledge linked pollutant accumulation on the module surface with transmittance loss of its glass covering, which leads to lessened amount of solar radiation reaching solar cells. First stage of this accumulation process is linear transparency loss, and second stage - molecule agglomeration and settlement some grains on the already existing layer of dust. Additionally, the pace of working parameters reduction for photovoltaic installation is influenced by the type of dust itself. Molecules with smaller grains cover the surface much more densely, therefore limiting the amount of light passing though the top glass layer far more than molecules with bigger grains. The aim of the carried out study was to find the relationship between dust surface density and change in electrical parameters. Such approach makes it possible to compare electrical and physical parameters of different photovoltaic modules. Additionally, glass coverage itself was noted to have a significant impact on the overall decrease in working parameters of PV modules.

The three-phase astrochemical code: modeling of the molecular cloud composition

We describe the implementation of a three-phase astrochemical model (gas + ice surface + bulk) based on the two-phase Presta code (gas + dust surface) and provide results for calculating the molecular cloud composition. The two- and three-phase models produce significantly different chemical compositions. In particular, CO ice abundance in the three-phase model shows good agreement with the observational data, unlike the two-phase model.

REDUCTION OF DUST REMOVAL OFF THE TAILING DUMPS SURFACES AS AN ELEMENT OF PREPERATION FOR RECLAMATION

Purpose. Analysis of issues of fixing the surfaces of sawdust tailings and their preparation for reclamation. Methods. The research is carried out on the basis of system and element-structural approaches with the use of generally accepted universal, specific scientific expert-analytical methods and modern methods of dust surface stabilization, expert-analytical methods and modern methods of dust surface stabilization. Results. The urgency of the problem of pollution of the air basin of Kryvyi Rih due to the removal of dust from the surfaces of tailings of mining and processing plants is considered. A brief description of these man-made neoplasms, such as unique man-made tracts; promising man-made deposits; objects of high potential ecological danger; powerful sources of pollution of environment; factors of degradation, fragmentation, transformation of flora and fauna; factors of formation of occupational risks, occupational and general morbidity of the population of the region. The factors influencing the processes of dust formation and determining the intensity of movement of dust fractions of tails are outlined. The purpose of the work is to analyze the issues of fixing the surfaces of sawdust tailings and their preparation for reclamation. A detailed description, characteristics, performance and disadvantages of the most common modern dust binders are given. The need for further search for long-acting agents that are able to effectively fix the surface of dust formation in all temperature ranges and in conditions of relatively low relative humidity and the surface layer of erosion-hazardous material is indicated. The prospects of using an aqueous solution of peat in order to fix the surfaces of tailings, rock dumps, prevention of dust in the air are determined. The physical, chemical and mechanical properties of the erosion-resistant coating based on the humate peat extract “Ideal” are analyzed. Recommendations on the method of using the tool, cost-effectiveness and advantages of the proposed technology as a component of preparation of man-made lands for reclamation are presented. It is established that the technology of treatment of tailings surfaces with peat-based solutions is able to: reduce the removal of dust into the air; promote the formation of a fertile layer of certain surfaces of tailings; potentiate the processes of natural overgrowth of man-made ecotopes; reduce the required amount of fertile soil during the reclamation of man-made objects after the end of service life, etc. The need for further comprehensive analysis of practical research results with detailing and concretization of basic generalizations is identified. Scientific novelty. The scientific novelty is to adapt the use of an aqueous solution of peat for use in the conditions of GOK Kryvbas in order to reduce air pollution by dust on the one hand and prepare for biological reclamation of disturbed areas. Practical significance. The proposed technology of treatment of tailings surfaces with peat-based solutions can be used in the Kryvyi Rih industrial region and is able to reduce dust removal into the air.

A novel framework for studying the impact of binding energy distributions on the chemistry of dust grains

The evaporation of molecules from dust grains is crucial to understanding some key aspects of the star- and the planet-formation processes. During the heating phase, the presence of young protostellar objects induces molecules to evaporate from the dust surface into the gas phase, enhancing its chemical complexity. Similarly, in circumstellar discs, the position of the so-called snow lines is determined by evaporation, with important consequences for the formation of planets. The amount of molecules that are desorbed depends on the interaction between the species and the grain surface, which is controlled by the binding energy. Recent theoretical and experimental works point towards a distribution of values for this parameter instead of the single value often employed in astrochemical models.We present a new “multi-binding energy” framework to assess the effects that a distribution of binding energies has on the amount of species bound to the grains. We find that the efficiency of the surface chemistry is significantly influenced by this process, with crucial consequences on the theoretical estimates of the desorbed species.