Some Elements of Biologization in Crops Production on Radioactively Contaminated Areas

The modern environmental and biological approaches to the selection of field agricultural crops for cultivation at contaminated areas are considered. It is established that the satiation of rotations with agricultural crops differed by potentially low capacity to accumulate 13Cs can significantly extend the areal of radioactively contaminated lands use for the production of safe products. The influence of arbuscular mycorrhizal fungi on radiocaesium uptake by plants is analyzed. The ability of arbuscular mycorrhiza to modify significantly radiocaesium accumulation by agricultural crops is found

Methodological bases of studying the dispersion composition of mine coal dust

The methodology of investigating the dispersion composition of mine dust is presented. The methodology is based on modern science-intensive methods such as the method of scanning microscopy and simple methods such as the method of sieve granulometric analysis. Today, the granulometric analysis is given great attention aimed to study the dimensions and aerodynamic characteristics of mine dust particles. The methods are applied separately from each other. Therefore, the paper discusses the most popular science methods gives recommendations on their joint application on the basis of the author's research on the dispersion composition of mine dust. Methods of scanning ectronic and optical microscopy are briefly described. Laser diffraction and sieve granulometric analyzes used to study the composition of coal mine dust are considered. That is chosen to use mine coal dust collected from the surface of hydraulic support racks of cleaning faces and coal dust obtained by the method of forced grinding of hard coal samples of different grades and anthracite as the samples for study. Samples of coal are taken from the working space of the mines of the Pechora, Kuznetsk and Donbass coal basins. Based on a comprehensive study of methods and analysis of results of studying the dispersion composition, their main advantages and disadvantages are given. The research methodology is based on physical methods for studying the dispersion characteristics of mine dust. In connection with the fact that one or another method is implemented in one device (installation), then in order to obtain complex data it is proposed to combine them into knowledge-intensive pairs. The combination in pairs of the equipment allows to study thoroughly both the dispersion composition and morphology of the dust particles, including the surface structure of dust particles if such a task is posed. Selection of samples and processes of preparing samples for research are in the basis of all methods used for obtaining qualitative and reliable scientific results. As a result of the experimental work carried out to prevent endogenous fires and explosions in the coal mine area, the author proposes to use a comprehensive approach consisting in applying synchronous thermal analysis methods together with methods for studying the dispersion composition of coal dust

Centrosome positioning in interphase cells

The position of the centrosome is actively maintained at the cell center, but the mechanisms of the centering force remain largely unknown. It is known that centrosome positioning requires a radial array of cytoplasmic microtubules (MTs) that can exert pushing or pulling forces involving MT dynamics and the activity of cortical MT motors. It has also been suggested that actomyosin can play a direct or indirect role in this process. To examine the centering mechanisms, we introduced an imbalance of forces acting on the centrosome by local application of an inhibitor of MT assembly (nocodazole), and studied the resulting centrosome displacement. Using this approach in combination with microinjection of function-blocking probes, we found that a MT-dependent dynein pulling force plays a key role in the positioning of the centrosome at the cell center, and that other forces applied to the centrosomal MTs, including actomyosin contractility, can contribute to this process

Switching of membrane organelles between cytoskeletal transport systems is determined by regulation of the microtubule-based transport

Intracellular transport of membrane organelles occurs along microtubules (MTs) and actin filaments (AFs). Although transport along each type of the cytoskeletal tracks is well characterized, the switching between the two types of transport is poorly understood because it cannot be observed directly in living cells. To gain insight into the regulation of the switching of membrane organelles between the two major transport systems, we developed a novel approach that combines live cell imaging with computational modeling. Using this approach, we measured the parameters that determine how fast membrane organelles switch back and forth between MTs and AFs (the switching rate constants) and compared these parameters during different signaling states. We show that regulation involves a major change in a single parameter: the transferring rate from AFs onto MTs. This result suggests that MT transport is the defining factor whose regulation determines the choice of the cytoskeletal tracks during the transport of membrane organelles

Cargo Transport at Microtubule Crossings: Evidence for Prolonged Tug-of-War between Kinesin Motors

AbstractIntracellular transport of cargos along microtubules is often complicated by the topology of the underlying filament network. The fundamental building blocks for this complex arrangement are filament intersections. The navigation of cargos across microtubule intersections remains poorly understood. Here, we demonstrate that kinesin-driven cargos are engaged in a tug-of-war at microtubule intersections. Tug-of-war events result in long pauses that can last from a few seconds to several minutes. We demonstrate that the extent of the tug-of-war and the duration of pauses change with the number of motors on the cargo and can be regulated by ionic strength. We also show that dwell times at intersections depend on the angle between crossing microtubules. Our data suggest that local microtubule geometry can regulate microtubule-based transport

Analyzing the Technology of Using Ash and Slag Waste from Thermal Power Plants in the Production of Building Ceramics

The work describes the problem of impounding and storing ash and slag waste at coal thermal power plants in Russia. Recovery and recycling of ash and slag waste are analyzed. Activity of radionuclides, the chemical composition and particle sizes of ash and slag waste were determined; the acidity index, the basicity and the class of material were defined. The technology for making ceramic products with the addition of ash and slag waste was proposed. The dependencies relative to the percentage of ash and slag waste and the optimal parameters for baking were established. The obtained materials were tested for physical and mechanical properties, namely for water absorption, thermal conductivity and compression strength. Based on the findings, future prospects for use of ash and slag waste were identified

Dispersion of the G-type coal dust of the Vorgashorskoe field and its influence on the thermal destruction process

Results of a comprehensive study of coal dust obtained from the G-type coal of Vorgashorskoe field are presented. The main research methods used in the work are granulometric, thermogravimetric and differential thermal analysis. The granulometric sieving carried out confirmed the heterogeneity of the sample with size of 0-200 μm fraction for a technical analysis. It is established that fractions of less than 100 μm size account for more than 50 % of the total sample mass. The results obtained suggested that result can be different depending on the content of a fraction in the overall technical sample sent for an analysis. However, this is probably acceptable in a technical analysis of coal dust samples but not for determination of explosive and fire hazard indicators. In order to study the effect of the dispersion composition of dust on a pyrolysis process in the air (oxidizing) medium for each of the fractions of 0-200 μm and additionally for larger fractions studies were carried out using thermogravimetry and a differential thermal analysis. The thermogravimetric analysis confirmed the hypothesis about the ambiguous behavior of coal dust during its pyrolysis depending on the dispersion composition. Two fractions showed the same behaviont during the thermal pyrolysis. The fraction of 63-94 μm is the boundary one between 0-45 and 45-63 μm and remaining fractions of larger than 94 μm in size. That fact indicates that during determination of the explosive fire hazard properties it is necessary to investigate dust samples of dispersive composition from 0 to 100 μm, i.е. a narrower fraction than in the technical analysis of samples from 0 to 200 μm. Express analysis of the obtained data of differential thermal analysis showed a difference in thermal degradation between the fractions of interest at the initial stage (250-330 °C). The results obtained allowed to draw a conclusion about the expediency of the study of coal dust of dispersive composition from 0-100 μm. It also showed the necessity of using methods considered in the paper for a detailed study of physical and chemical parameters of coal dust and an assessment of its explosive and fire hazard properties

Regulation of microtubule-based transport by MAP4

Microtubule (MT)-based transport of organelles driven by the opposing MT motors kinesins and dynein is tightly regulated in cells, but the underlying molecular mechanisms remain largely unknown. Here we tested the regulation of MT transport by the ubiquitous protein MAP4 using Xenopus melanophores as an experimental system. In these cells, pigment granules (melanosomes) move along MTs to the cell center (aggregation) or to the periphery (dispersion) by means of cytoplasmic dynein and kinesin-2, respectively. We found that aggregation signals induced phosphorylation of threonine residues in the MT-binding domain of the Xenopus MAP4 (XMAP4), thus decreasing binding of this protein to MTs. Overexpression of XMAP4 inhibited pigment aggregation by shortening dynein-dependent MT runs of melanosomes, whereas removal of XMAP4 from MTs reduced the length of kinesin-2–dependent runs and suppressed pigment dispersion. We hypothesize that binding of XMAP4 to MTs negatively regulates dynein-dependent movement of melanosomes and positively regulates kinesin-2–based movement. Phosphorylation during pigment aggregation reduces binding of XMAP4 to MTs, thus increasing dynein-dependent and decreasing kinesin-2–dependent motility of melanosomes, which stimulates their accumulation in the cell center, whereas dephosphorylation of XMAP4 during dispersion has an opposite effect