The Effect of AlI3 Nanoadditive on the Thermal Behavior of PMMA Subjected to Thermoanalytical Py-GC-MS Technique

Thermal degradation of polymethylmethacrylate (PMMA) was studied by using inorganic salt of aluminum triiodide (AlI3). The composites of PMMA were prepared with AlI3 by changing the concentration of the AlI3 additive from 2% to 10% (w/w). The PMMA composites with AlI3 were characterized by TGA, DTG, SEM, FTIR, HBT, and Py-GC-MS techniques. The FTIR peaks of PMMA composite at 1316, 786, and 693 cm−1 justify the chemical association between PMMA and AlI3. TGA study shows that the stability of PMMA is enhanced by the addition of the AlI3 additive. SEM analysis represented that there is a relationship between polymer and additive when they are mixed at the molecular level. The horizontal burning test (HBT) also confirmed that the AlI3 additive produced the flame retarding properties in PMMA polymer. The burning rate of composite with 10% of AlI3 additive decreases five times as much as compared to pure PMMA polymer. Py-GC-MS analysis deduced that PMMA composite produced less toxic and environment-friendly substances (CO2) by the influence of AlI3 additive as compared to neat PMMA.

Hygienic assessment of personnel working conditions in underground uranium mining

The aim of the study is to assess the main radiation-hazardous factors that determine the effective dose of personnel during underground uranium mining at the Priargunsky Industrial Mining and Chemical Association, and to summarize the data of the radiation control of the enterprise for 2016-2020. The main factors that create personnel dose loads are: the volume activity of short-lived daughter products of radon decay in the air, the dose rate of external gamma radiation, and the volume activity of long-lived alpha-emitting radionuclides of the uranium-radium series in industrial dust. Information on the structure and values of individual effective doses of workers is presented. Recommendations for improving the radiation monitoring system are given.

Ideal Gas Reference for Association and Dissociation Reactions: I. Basic Concepts

Starting with a distance-based definition of molecules consisting of non-interacting atoms, which is in line with IUPAC terminology, we construct an ideal gas reference for chemical association and dissociation reactions. The corresponding ideal equations for equilibria and kinetics reveal the mathematical structure, known for real systems, in comprehensible clarity. The ideal gas reference corresponds to the limit of an entirely flat potential energy surface of the system where chemical equilibria and kinetics are determined by "unspecific" particle number combinatorics according to the reaction stoichiometry. The ideal equilibrium and rate constants provide a reference for the definition of excess equilibrium and rate constants of real reactions that quantify all "system-specific" contributions resulting from the particular shape of the potential energy surface. The ideal gas reference therefore enables a distinction between unspecific and system-specific aspects in the equilibria and kinetics of chemical association/dissociation reactions. Whereas conventional equilibrium and rate constants suffer from incompatibility between reactions of different stoichiometry, excess equilibrium and rate constants can be consistently compared across different reaction orders. Furthermore, whereas the conventional treatment requires an arbitrary specification of reference concentrations, e.g. at standard conditions, the ideal gas framework introduces an intrinsic concentration scale that is equal to the inverse of a molecular volume.

Direct H-He chemical association in superionic FeO2H2He at Deep-Earth conditions

Hydrogen and helium were known to play crucial roles in geological and astrophysical environments; however, they are inert toward each other across wide pressure-temperature (P-T). Given their prominent presence and influence on the formation and evolution of celestial bodies, it is of fundamental interest to explore the nature of interactions between hydrogen and helium. Using an advanced crystal structure search method, we have identified a quaternary compound FeO2H2He stabilized in a wide range of P-T conditions. Ab initio molecular dynamics simulations further reveal a novel superionic state of FeO2H2He hosting liquid-like diffusive hydrogen in the FeO2He sublattice, creating a conducive environment for H-He chemical association, at P-T conditions corresponding to the Earth's lowest mantle regions. This surprising chemically facilitated coalescence of otherwise immiscible molecular species highlights a promising avenue for exploring this long-sought but hitherto unattainable state of matter. This finding raises strong prospects for exotic H-He mixtures inside Earth and possibly also in other astronomical bodies.

Formation of the Company's Corporate Brand As a Sign of Its Recognition in the Labor Market

The paper shows the main signs of the company's recognition, the relevance of which is quite obvious in the formation of the employer's brand, and is presented by the high rate of development of modern markets with growing competition on the example of the mining enterprise PJSC Priargunsky Industrial Mining and Chemical Association. The company's tactics, aimed at attracting, developing and promoting personnel, is a key element not only of the management system, but of the entire positioning and foreign policy of the company in the labor market.

Modeling of filtration processes of technological solutions in block underground leaching

PAO “Priargunsky Production Mining and Chemical Association” has been working on reserves of uranium deposits of the Streltsovsky ore field for more than 50 years. During this period, most of the rich ores have been worked out by traditional mining and physical technology. The share of poor and ordinary ores remains significant, but traditional technology does not provide the necessary level of profitability. Therefore, the widespread introduction of physicochemical technology: underground block (BPV) and heap leaching (KV) can be a decisive moment in the continuation of the operation of these deposits. The applied technology of underground block leaching has one significant drawback – a low rate of uranium recovery into a productive solution, which significantly reduces the effectiveness of this technology in the development of poor uranium deposits. To increase the yield of uranium into the productive solution, it is necessary to analyze the entire preparation and leaching process and establish the main reasons for the low rates of transition of uranium to a mobile state. For this purpose, it is proposed to simulate the underground leaching process by building visual models of halos spreading of solutions along shrinked ore mining mass accumulated in an underground chamber. During the simulation, it was found that the distribution of the size classes of the broken ore pieces in the chamber can be predicted at the stage of drilling and blasting operations, and when determining the line of least resistance W and the distance between the ends of the wells, take into account the diameter of the controlled crushing zone R_p. At the same time, 3 zones of granulometric compositions are formed: a re-grinding zone, an optimum zone and a non-carbarite exit zone. The flow of solutions through these zones will differ the more significantly, the higher the height of the chamber. In a zone with larger crushing, an almost steep distribution of the solution spreading front is expected. Accordingly, the smaller the fraction, the lower the front to the horizontal is. The following functions are offered to simulate filtering processes: – it is possible to control the flow of working solutions to the fan of irrigation wells in order to achieve optimal leaching parameters, i.e. to quickly control the process; – knowledge of the law of distribution of irrigation flares makes it possible to select the optimal grid of location of single sprinklers

Using weapons instead of perfume – chemical association strategies of the myrmecophilous bug Scolopostethus pacificus (Rhyparochromidae)

A vast diversity of parasites associate with ants. Living in and around ant nests these organisms must overcome ant colony defenses. As ant defensive behavior is mainly mediated by species-specific cuticular hydrocarbons (CHCs) or alarm pheromones, ant-associated parasites can either crack their hosts chemical communication code by modifying their own CHC-profiles or use pro-active strategies like chemical weaponry for distraction and repellency. While the chemical nature of ant-parasite interactions has been intensively studied for highly host specific parasites, the chemical-deceptive strategies of the rather rare ant-resembling Heteropterans are unknown. To gain insight into this system, I studied the bug Scolopostethus pacificus (Barber 1918) which can be found near the nests of the ecologically dominant and aggressive velvety tree ant (Liometopum occidentale, Emery 1895). Using behavioral, chemical and molecular approaches I disentangled the relationship of S. pasificus and its host ant. Chemical profiling of the bug and the ant revealed that the bug does not make use of CHC insignificance or mimicry, but instead uses a cocktail of volatile compounds released from its metathoracic glands that likely moderates encounters with its aggressive host. Feeding trials with armed and artificially disarmed bugs revealed a defensive function of the gland exudates. Targeted molecular gut barcoding showed that S. pasificus does not feed on L. occidentale. These results suggest that chemical weaponry, rather than a chemical code-cracking CHC matching or chemical insignificance, enables S. pasificus to get along with and live in close proximity to its host ant.

SPECIATION OF METALS IN SEDIMENTS FROM DAMS AND RIVERS ALONG GOLD MINING VICINITIES IN ZAMFARA STATE

Sediments samples from three dams and rivers in Zamfara State were analyzed for chemical association of the metals (Zn, Cd, Cr, Pb and Hg) using sequential extraction method to determine the amount of the heavy metals available for absorption. The concentrations were determined in four fractions. The concentration of heavy metals in the food crop (tomatoes) was also determined using atomic absorption spectrometry (AAS). The sequential extraction was carried out using (1.0 g) of powder sample weighed into a glass centrifuge (60 ml) and fractions were obtained. Comparing the way the metals were bound to the different fractions in the sediments, it showed clearly that the metals in the sediments are bound to different fractions with different strength. Cd and Cr were primarily in the carbonate bound fraction while Zn and Hg appear mainly in the residual phase. Pb was found in carbonate, exchangeable and water soluble fractions. The distribution of the five metals studied revealed their differences in mobility. From the five elements studied, Cd (14.739- 39.931%) and Pb (0.105- 9.832%) appeared to be the most readily solubilized, thus making these elements the most potentially bioavailable. This may present a real threat as Cd and Pb are transferred into the food chain from soil contaminated by these metals. Zn and Cr levels in the tomatoes, were within international standard while Cd (0.1022 mg/l), Pb (0.2104 mg/l) and Hg (1.8818 mg/l) levels were far above (0.01, 0.01 and 0.001mg/l) USEPA standard for drinking water. Two indices such as contamination

Invisible Gold Paragenesis and Geochemistry in Pyrite from Orogenic and Sediment-Hosted Gold Deposits

LA-ICPMS analysis of pyrite in ten gold deposits is used to determine the precise siting of invisible gold within pyrite, and thus the timing of gold introduction relative to the growth of pyrite and related orogenic events. A spectrum of invisible gold relationships in pyrite has been observed which suggests that, relative to orogenic pyrite growth, gold introduction in some deposits is early at the start of pyrite growth; in other deposits, it is late toward the end of pyrite growth and in a third case, it may be introduced at the intermediate stage of orogenic pyrite growth. In addition, we report a distinct chemical association of invisible gold in pyrite in the deposits studied. For example, in the Gold Quarry (Carlin type), Mt Olympus, Macraes and Konkera, the invisible gold is principally related to the arsenic content of pyrite. In contrast, in Kumtor and Geita Hill, the invisible gold is principally related to the tellurium content of pyrite. Other deposits (Golden Mile, Bendigo, Spanish Mountain, Witwatersrand Carbon Leader Reef (CLR)) exhibit both the Au-As and Au-Te association in pyrite. Some deposits of the Au-As association have late orogenic Au-As-rich rims on pyrite, which substantially increase the value of the ore. In contrast, deposits of the Au-Te association are not known to have Au-rich rims on pyrite but contain nano- to micro-inclusions of Au-Ag-(Pb-Bi) tellurides.