Potentially toxic elements (PTE) in soils on the megaprofile Eastern Donbass – Azov sea

An expedition was carried out to take soil samples of Eastern Donbass and other districts of the Rostov region. The main goal was to study the distribution of potentially toxic elements (PTE) in soils. The total content of mineral components in solid-phase samples was determined by using the X-ray fluorescence method. It was found that, according to the average concentrations, PTE`s line up in the following series: Fe>Mn>Zn>Cr>V>Cu>Ni>Pb>Co. The contents of Zn and Cu in the soil were compared by seasons. It was determined that PTE concentrations in the upper layer of soils were higher in winter than in summer. Geochemical spectra were constructed. They demonstrated that the concentration Clarks of Cr, Cu, Zn, Co, Pb exceeded the Clarks of these elements in the Earth’s crust. Against this background, Pb stands out with contrast, the concentration in the soil of which exceeds those in the earth’s crust by 2.8 times. The tightness of the relationship between the content of PTE in soil samples was calculated, which turned out to be a high straight line

Electrophysical Characteristics of a Polymer Composite Based on Ultrahigh Molecular Weight Polyethylene with CuO Nanoparticles

Методом импедансной спектроскопии исследованы электрофизические свойства композитного материала на основе сверхвысокомолекулярного полиэтилена с ограниченной массовой концентрацией 0,5 мас.% оксида меди CuO в диапазоне частот от 102 до 108 Гц. Предполагается, что введение в состав полимера малых концентраций наночастиц способствует более равномерному их осаждению на поверхностях полимерных гранул. Это позволяет в процессе тестирования таких образцов выявить наиболее вероятные механизмы их поляризации и протекания электрического тока в относительно однородном ансамбле наночастиц в полимерной матрице. Установлено, что внедряемые в полимерную матрицу наночастицы незначительно влияют на процессы электрической поляризации, но приводят к появлению частотно-зависимой проводимости в широком диапазоне частот. Этот процесс сопровождается существенным возрастанием диэлектрических потерь. Электрофизические характеристики полученных композитов обсуждаются с учётом переноса электрических зарядов (ионов или электронов) как по внутренней, так и по поверхностной структуре наночастиц CuOThe electrophysical properties of a composite material based on ultrahigh molecular weight polyethylene with a limited mass concentration of 0.5 wt% copper oxide CuO in the frequency range from 102 to 108 Hz were studied by impedance spectroscopy. It is assumed that the introduction of low concentrations of nanoparticles into the polymer composition contributes to their more uniform deposition on the surfaces of polymer granules. This makes it possible to reveal the most probable mechanisms of their polarization and the flow of electric current in a relatively homogeneous ensemble of nanoparticles in a polymer matrix during testing of such samples. It has been established that nanoparticles introduced into the polymer matrix have little effect on the processes of electric polarization, but lead to the appearance of frequency-dependent conductivity in a wide frequency range. This process is accompanied by a significant increase in dielectric losses. The electrophysical characteristics of the resulting composites are discussed taking into account the transfer of electric charges (ions or electrons) both along the internal and surface structures of CuO nanoparticle

Modelling human choices: MADeM and decision‑making

Research supported by FAPESP 2015/50122-0 and DFG-GRTK 1740/2. RP and AR are also part of the Research, Innovation and Dissemination Center for Neuromathematics FAPESP grant (2013/07699-0). RP is supported by a FAPESP scholarship (2013/25667-8). ACR is partially supported by a CNPq fellowship (grant 306251/2014-0)

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

The use of chemical and instrumental methods in the study of the forms of occurrence of sulfides in bottom sediments

On the example of the estuary of the Mius River - the mouth of the Mius River, the Mius estuary, the Taganrog Bay of the Azov Sea, a complex of chemical and instrumental methods was applied, including those developed by the authors. This made it possible to study the physicochemical parameters, the content of total hydrogen sulphide, the form of occurrence of sulfides, the total content of iron and their behavior in the bottom sediments of early diagenesis. Bottom sediments were formed at negative Eh values. Sulfides in bottom sediments are mainly in the form of molecular hydrogen sulfide and acid-soluble iron sulfides. The content of total hydrogen sulfide varied within wide limits, reaching 3.2 mg/g of wet weight, and of gross iron - from 25.4 to 45.1 mg/g dry weight. A significant relationship was found between the content of sulfide sulfur and gross iron. The presence of hydrotroilite was identified by the typical smell of hydrogen sulfide, black color, oily sludge, lack of magnetic properties and by visual study of its formations using electron microscopy. Under a microscope, images of coacervates (colloidal accumulations) of hydrotroilite of a round-ellipsoidal shape (lenticular), from gray to black, mercury-like, were obtained in a wet preparation. It was established for the first time that hydrotroilite exists in the natural environment as a gel-like substance capable of moving in the bottom of sediments. Upon collision, small formations coalesced into larger globules. The important role of hydrotroilite as a mercury accumulator in the early diagenesis of bottom sediments is shown

Physical and chemical properties, elemental and material snow composition in Rostov-on-Don

To study the current distribution of the heavy metals (HM) levels and iron in the atmospheric precipitation in Rostov-on-Don, an expedition was conducted aimed at simultaneous river water and snow sampling in the Don River, the roadside and park areas. The pH values of the melt-water were characterized by a slightly acidic reaction, and the stale snow in the park had lower values in comparison with the fresh snow. The river water was slightly alkaline, and the concentrations of dissolved migration forms of Pb, Cd, Zn, Ni, Cr, Mn, and Fe did not exceed the MPC. The exception was the Cu content, which exceeded the MPC by 2.4 times. The contents of the dissolved migration forms of Pb, Cd, Zn, Cu, Ni, and Fe in snow exceeded their contents in river waters. The HM and Fe percentage in suspended form in river water and different snow states is calculated and the sequence series are constructed. The analysis showed that in melt-water, in comparison with river water, there is a higher percentage of the HM and iron in the solution. That may be due to the slightly acidic reaction of the snow water medium, which, as is known, promotes the HM and Fe mobilization from the suspension and their transition to the dissolved state. Using electron microscopy and X-ray phase analysis, the suspension composition in the snow of the park zone was studied, which is mainly represented by aggregates of clay minerals, quartz grains, water silicates, feldspars, and organic matter clumps

Calculation of ¹⁵N and ³¹P NMR Chemical Shifts of Azoles, Phospholes, and Phosphazoles: A Gateway to Higher Accuracy at Less Computational Cost

A number of computational schemes for the calculation of ¹⁵N and ³¹P NMR chemical shifts and shielding constants in a series of azoles, phospholes, and phosphazoles was examined. A very good correlation between calculated at the CCSD­(T) level and experimental ¹⁵N and ³¹P NMR chemical shifts was observed. It was found that basically solvent, vibrational, and relativistic corrections are of the same order of magnitude and alternate in sign, being, on average, of about 2–3 ppm in absolute value but, being much larger (up to 14 ppm) in the case of solvent molecules explicitly introduced into computational space. At the DFT level, the performance of nine exchange–correlation functionals including six conventional gradient functionals and three hybrid functionals was studied. The most accurate results were reached with the OLYP and Keal–Tozer’s family of functionals, KT1, KT2, and KT3, while the most popular B3LYP and PBE0 functionals showed the most unreliable results. On the basis of these data, we highly recommend OLYP and KT2 functionals for the computation of ¹⁵N and ³¹P NMR chemical shifts at the DFT level in the diverse series of nitrogen- and phosphorus-containing heterocycles. Benchmark calculations of ¹⁵N and ³¹P NMR chemical shifts in a series of larger nitrogen- and phosphorus-containing heterocycles were performed at the DFT level in comparison with experiment and revealed the OLYP functional in combination with the aug-pcS-3/aug-pcS-2 locally dense basis set scheme as the most effective computational scheme

Large spin splitting of metallic surface-state bands at adsorbate-modified gold/silicon surfaces

Finding appropriate systems with a large spin splitting of metallic surface-state band which can be fabricated on silicon using routine technique is an essential step in combining Rashba-effect based spintronics with silicon technology. We have found that originally poor structural and electronic properties of the [Image: see text] surface can be substantially improved by adsorbing small amounts of suitable species (e.g., Tl, In, Na, Cs). The resultant surfaces exhibit a highly-ordered atomic structure and spin-split metallic surface-state band with a momentum splitting of up to 0.052 Å(−1) and an energy splitting of up to 190 meV at the Fermi level. The family of adsorbate-modified [Image: see text] surfaces, on the one hand, is thought to be a fascinating playground for exploring spin-splitting effects in the metal monolayers on a semiconductor and, on the other hand, expands greatly the list of material systems prospective for spintronics applications