Theoretical Analysis of Fully Conservative Difference Schemes with Adaptive Viscosity

For the equations of gas dynamics in Eulerian variables, a family of two-layer in time completely conservative difference schemes with space-profiled time weights is constructed. Considerable attention is paid to the methods of constructing regularized flows of mass, momentum, and internal energy that do not violate the properties of complete conservatism of difference schemes of this class, to the analysis of their amplitudes and the possibility of their use on non-uniform grids. Effective preservation of the balance of internal energy in this type of divergent difference schemes is ensured by the absence of constantly operating sources of difference origin that produce "computational"entropy (including those based on singular features of the solution). The developed schemes can be easily generalized in order to calculate high-temperature flows in media that are nonequilibrium in temperature (for example, in a plasma with a difference in the temperatures of the electronic and ionic components), when, with the set of variables necessary for describing the flow, it is not enough to equalize the total energy balance.

Salt Stress Affects Plastid Ultrastructure and Photosynthetic Activity but Not the Essential Oil Composition in Spearmint (Mentha spicata L. var. crispa “Moroccan”)

High levels of soil salinity affect plant growth, reproduction, water and ion uptake, and plant metabolism in a complex manner. In this work, the effect of salt stress on vegetative growth, photosynthetic activity, and chloroplast ultrastructure of spearmint (Mentha spicata L. var. crispa “Moroccan”) was investigated. After 2 weeks of low concentration treatments (5, 25, and 50 mM NaCl) of freshly cut shoots, we observed that the stem-derived adventitious root formation, which is a major mean for vegetative reproduction among mints, was completely inhibited at 50 mM NaCl concentration. One-week-long, high concentration (150 mM NaCl) salt stress, and isosmotic polyethylene glycol (PEG) 6000 treatments were compared in intact (rooted) plants and freshly cut, i.e., rootless shoots. Our data showed that roots have an important role in mitigating the deleterious effects of both the osmotic (PEG treatment) and specific ionic components of high salinity stress. At 50 mM NaCl or above, the ionic component of salt stress caused strong and irreversible physiological alterations. The effects include a decrease in relative water content, the maximal and actual quantum efficiency of photosystem II, relative chlorophyll content, as well as disorganization of the native chlorophyll-protein complexes as revealed by 77 K fluorescence spectroscopy. In addition, important ultrastructural damage was observed by transmission electron microscopy such as the swelling of the thylakoid lumen at 50 mM NaCl treatment. Interestingly, in almost fully dry leaf regions and leaves, granum structure was relatively well retained, however, their disorganization occurred in leaf chloroplasts of rooted spearmint treated with 150 mM NaCl. This loss of granum regularity was also confirmed in the leaves of these plants using small-angle neutron scattering measurements of intact leaves of 150 mM NaCl-stressed rooted plants. At the same time, solid-phase microextraction of spearmint leaves followed by gas chromatography and mass spectrometry (GC/MS) analyses revealed that the essential oil composition of spearmint was unaffected by the treatments applied in this work. Taken together, the used spearmint cultivar tolerates low salinity levels. However, at 50 mM NaCl concentration and above, the ionic components of the stress strongly inhibit adventitious root formation and thus their clonal propagation, and severely damage the photosynthetic apparatus.

Prediction of Genes That Function in Methanogenesis and CO2 Pathways in Extremophiles

Gaet’ale (GAL) and Mud’ara (MUP) are two hypersaline ponds located in the Danakil Depression recharged by underground water from the surrounding highlands. These two ponds have different pH, salinity, and show variation in the concentration of many ionic components. Metagenomic analysis concludes that GAL is dominated by bacteria as in the case of the other hypersaline and acidic ponds in the Danakil Depression. However, Archaea dominated the ponds of MUP. In the current study, the application of SEED and KEGG helped to map the ordered steps of specific enzyme catalyzed reaction in converting CO2 into cell products. We predict that highly efficient and light-independent carbon fixation involving phosphoenolpyruvate carboxylase takes place in MUP. On the contrary, genes encoding enzymes involved in hydrogenotrophic and acetoclastic methanogenesis appeared solely in ponds of GAL, implying the biological source of the hazardous methane gas in that environment. Based on the investigation of the sources of the genes of interest, it is clear that cooperative interactions between members of the two communities and syntrophic metabolism is the main strategy adapted to utilize inorganic carbon as a carbon source in both MUP and GAL. This insight can be used to design biotechnological applications of microbial communities in production of methane biogas or to minimize CO2 emissions.

Adsorption Characteristics of Combined Sulfhydryl Collector on Chalcopyrite and Arsenopyrite in Flotation of Complex Gold Ores

The paper presents the results of experimental study of the adsorption properties of the combined sulfhydril collecting reagent –a mixed solution of sodium diethyl-dithiocarbamate (DEDTC) and oxypropyl diethyl-dithiocarbamate ester (OPDTC) towardschalcopyrite and arsenopyrite with a view to its application as a selective collector of Au-containing sulfide minerals in flotationof complex refractory ores. Combined diethyl-dithiocarbamate solution (DEDTCc) incorporated a fixed content of anionic andnon-ionic components (DEDTC:OPDTC = 1:1) and occurred variable hydrophobic effect on the surface of the basic gold-bearingsulfide minerals – chalcopyrite and arsenopyrite.The mechanism of adsorption of the components of combined collector on the surface of chalcopyrite and arsenopyrite was identifiedto form characteristic molecular shape of adsorbed collector convex neoplasms and sinter chemically adsorbed film of thereactant, which is firmly anchored on the surface. The newly formed phase of the adsorbed reagent did not dissolve in water at asubsequent washing. In this case, the phase of nonionic ester OPDTC was partially removed by water and the residual adsorbeddroplets changed their shape and became flatter. By X-ray microanalysis C and O bands relating to the structure of the combinedDEDTCc were identified on the surface of arsenopyrite and chalcopyrite. The original technic for analyzing the liner dimension ofsurface images with an application of scanning laser microscopy and the software of the Analyzer was developed and the authorssucceeded to provide a quantitative evaluation of the adsorption of DEDTCc on the surface of chalcopyrite and arsenopyrite.

Na+ and/or Cl− Toxicities Determine Salt Sensitivity in Soybean (Glycine max (L.) Merr.), Mungbean (Vigna radiata (L.) R. Wilczek), Cowpea (Vigna unguiculata (L.) Walp.), and Common Bean (Phaseolus vulgaris L.)

Grain legumes are important crops, but they are salt sensitive. This research dissected the responses of four (sub)tropical grain legumes to ionic components (Na+ and/or Cl−) of salt stress. Soybean, mungbean, cowpea, and common bean were subjected to NaCl, Na+ salts (without Cl−), Cl− salts (without Na+), and a “high cation” negative control for 57 days. Growth, leaf gas exchange, and tissue ion concentrations were assessed at different growing stages. For soybean, NaCl and Na+ salts impaired seed dry mass (30% of control), more so than Cl− salts (60% of control). All treatments impaired mungbean growth, with NaCl and Cl− salt treatments affecting seed dry mass the most (2% of control). For cowpea, NaCl had the greatest adverse impact on seed dry mass (20% of control), while Na+ salts and Cl− salts had similar intermediate effects (~45% of control). For common bean, NaCl had the greatest adverse effect on seed dry mass (4% of control), while Na+ salts and Cl− salts impaired seed dry mass to a lesser extent (~45% of control). NaCl and Na+ salts (without Cl−) affected the photosynthesis (Pn) of soybean more than Cl− salts (without Na+) (50% of control), while the reverse was true for mungbean. Na+ salts (without Cl−), Cl− salts (without Na+), and NaCl had similar adverse effects on Pn of cowpea and common bean (~70% of control). In conclusion, salt sensitivity is predominantly determined by Na+ toxicity in soybean, Cl− toxicity in mungbean, and both Na+ and Cl− toxicity in cowpea and common bean.

The Characteristics and Distribution of Chemical Components in Particulate Matter Emissions from Diesel Locomotives

The use of diesel locomotives in transport is gradually decreasing due to electrification and the introduction of high-speed electric rails. However, in Korea, up to 30% of passenger and cargo transport still relies on diesel locomotives and vehicles. Many studies have shown that the exhaust gas from diesel locomotives poses a threat to human health. This study examined the characteristics of particulate matter (PM) in diesel locomotive engine exhaust. In a previous study, PM emissions were found to increase as the throttle was moved to a higher notch. The use of a portable emission measurement system (PEMS) in this study did not detect the highest emissions at notch 5, as is commonly found in gravimetric analyses. When comparing the mass concentrations, the notch 1 and 5 results were similar. However, at notch 8, there was a large difference between the mass concentrations collected on the filters. Further, to reduce the fine PM emitted from diesel locomotives, the ionic components, which account for the largest proportion of the total materials in fine PM, should be clearly identified. Therefore, in this study, an analysis of the weight, ionic composition, and metal components of fine PM discharged from a diesel locomotive was performed. Based on the results, Na+ (31%), Ca2+ (27%), NO3− (24%), and SO42− (13%), were the main ionic components, and the most abundant metal components being Ca (45%) and S (20%). In this study, the chemical components generated in diesel engines of other sources were compared, and as a result, different results were shown depending on the engine load and material ingredients. For the first time, a PEMS was used to measure PM from diesel vehicles, and a comparison was made with the results obtained by a gravimetric method. This is the first report of measuring PM concentrations by connecting a PEMS to a diesel locomotive, and of the distribution and characteristics of ions and heavy metals contained in the particles collected in the filter analyzed. The results indicate the importance of identifying the characteristics of fine PM emitted from a diesel locomotive and establishing an effective reduction measurement.

Design and basic properties of polyester vitrimers combined with an ionomer concept

The preparation of vitrimers with ionic components was demonstrated to investigate the effects of ion-rich domain formation on vitrimer properties, revealing that the degree of ion aggregation can be a factor in tuning the bond-exchange properties.

“Chemical Triangle” as a modern intellectual basis for digital systematization of energy characteristics of substances

It was shown that sustainable power and mechanical engineering relies primarily on chemical transformation of matter, since a chemical substance (in the form of homo- and heteronuclear compounds of elements) is the most accessible type of substance on Earth. As a result, low-, oligo- and high-molecular and non-molecular (metallic and ionic) chemicals and products (fuels, polymers, alloys, glasses, etc.) are primary raw materials for production of thermal and electrical energy, as well as materials needed for alternative energy production. It was noted that the main drawback of the modern expert system for assessing the energy properties of substances used as fuels is not taking into account the influence of the chemical bond type on its energy and energy characteristics of fuels in general. It was shown that the solution to this problem is possible through the use of the unified model of chemical bond of elements, which considers any chemical bond as an overlay (resonance) of a 100% covalent bond with either metal or metal and ionic components, with a subsequent assessment of the effect of each of them on total energy of the mixed bond. This model is the fundamental basis of the System of chemical bonds and compounds (SCBC) in the form of the “Chemical Triangle”. The possibility of using the “Chemical Triangle” as a modern intellectual basis for digital systematization and creation of a database of energy characteristics of various substances based on homo- and heteronuclear compounds of elements was shown. A computer database was developed to assess the complex impact of composition and chemical bond type on its energy characteristics, structure and properties of substances and materials.

Composition and Pollution Characteristics of Precipitation in Jeju Island, Korea for 1997–2015

This study focuses on the long-range chemical composition and pollution characteristics of precipitation components. Samples were collected from Jeju Island in 1997–2015, and their major ionic components were analyzed. Comparison of ion balance, electrical conductivity, and acid fraction of precipitation samples yielded correlation coefficients in the range of 0.937–0.980. The volume-weighted mean pH and electrical conductivity of the wet precipitation of the Jeju area were 4.81 and 21.7 μS/cm, respectively. Ionic strengths of the wet precipitation samples were within the range of 0.24 ± 0.26 mM, indicating that more than 30% of the total precipitation satisfied the pure precipitation criterion. Of the total precipitation in the Jeju area, 44% exhibited a pH in the range of 4.5–5.0, indicating weak acidity. The composition of sea salts and secondary pollutants in the precipitation were 56.8% and 28.7%, respectively, indicating that the precipitation in the Jeju area was affected by the surrounding coastal area. The acidity contributions by inorganic and organic acids were 92.3% and 7.7%, respectively, whereas, the neutralization factors for ammonia and calcium carbonate were 47.0% and 20.0%, respectively. Clustered back trajectory analysis indicates that the concentrations of most ionic components were higher in the airflow pathways to the Jeju area.