Mobilisation of Al, Fe, and DOM from topsoil during simulated early Podzol development and subsequent DOM adsorption on model minerals

Podzols are characterised by mobilisation of metals, particularly Al and Fe, and dissolved organic matter (DOM) in topsoil horizons, and by immobilisation in subsoil horizons. We mimicked element mobilisation during early podzolisation by irrigating the AE horizon of a Dystric Arenosol with acetic acid at different flow velocities and applying flow interruptions to study rate-limited release in experiments with soil cylinders. We used eluates in batch experiments with goethite and Al-saturated montmorillonite to investigate DOM reactivity towards minerals. Both the flow velocity and flow interruptions affected element release, pointing to chemical non-equilibrium of release and to particles, containing Fe and OM mobilised at larger flow velocity, characteristic of heavy rain or snowmelt. Based on chemical extractions, the source of mobilised Al and Fe, the vast majority of which was complexed by DOM, was no oxide phase, but rather organic. Rate limitation also affected the composition of DOM released. Carboxyl and phenolic species were the most important species adsorbed by both minerals. However, DOM composition affected the extent of DOM adsorption on goethite more distinctly than that on montmorillonite. Our findings evidence that the intensity of soil percolation affects quantitative and qualitative element release during early podzolisation and adsorptive DOM retention in subsoil horizons.

COMBINED METHOD FOR CLEANING PIPES FROM SOIL CORE

The paper is devoted to solving an urgent problem - improving the technology of soil excavation during trenchless pipe laying by vibro-impact pushing with the leading steel casing of the well. A new method for core extraction is proposed, which is based on the effect of its vibration transportation under the influence of combined static-dynamic load. The optimum level of soil moisture is experimentally determined, which contributes to a decrease in lateral friction when it moves along a metal pipe cavity. The results of pilot tests on cleaning a pipe 530 mm in diameter, immersed in soil at full design length of transition using Typhoon-190 pneumatic hammer with a mass of 190 kg are presented. The velocity characteristic of core displacement at changing its moisture content is obtained.

Distribution of cyprinids in the stream during their spring upstream migration

The researches were carry out by stationary and mobile hydroacoustic computerized complexes in the floodplain-riverbed complex of the Irtysh River (Western Siberia, Russian Federation). It was established that during the migration period during the spring flood, patterns of distribution of fish in the stream are observe due to the size-taxonomic characteristics of the fish population and the physiological capabilities of the organism of fish. With an increase in the flow velocity characteristic from the near bank part of the river to its midstream, the proportion of cyprinids in the watercourse decreases, and the proportion of fish with body sizes> 15 cm increases. The number of fish smaller at high-speed sections of the river increases with an increase in water temperature, which in turn indicates the increasing physiological capabilities of representatives of Cyprinidae family. Absolute numerical dominance of migratory fish and the largest proportion of cyprinids were observed in the low velocity section of the river, located closer to the shore. The indicator of the proportion of cyprinids have a direct strong correlative relationship with the temperature factor (0.70-0.73, P<0.05).

Simulating the dynamics of the mechanochemical cycle of myosin-V

The detailed dynamics of the cycle of myosin-V are explored by simulation approaches, examining the nature of the energy-driven motion. Our study started with Langevin dynamics (LD) simulations on a very coarse landscape with a single rate-limiting barrier and reproduced the stall force and the hand-over-hand dynamics. We then considered a more realistic landscape and used time-dependent Monte Carlo (MC) simulations that allowed trajectories long enough to reproduce the force/velocity characteristic sigmoidal correlation, while also reproducing the hand-over-hand motion. Overall, our study indicated that the notion of a downhill lever-up to lever-down process (popularly known as the powerstroke mechanism) is the result of the energetics of the complete myosin-V cycle and is not the source of directional motion or force generation on its own. The present work further emphasizes the need to use well-defined energy landscapes in studying molecular motors in general and myosin in particular.

Approaching Tumor Tissue in Local Blood Vessel for Targeted Drug Delivery by Nanorobots

This paper describes a nanorobot control algorithm designed for approaching tumor tissue in local blood vessel for targeted drug delivery. The algorithm coordinates nanorobots’ movements through use of two types of chemical molecules, an acoustic signal and velocity characteristic of blood fluid. After detecting the chemical molecules released by cancer cells, a nanorobot moves toward the area of higher concentration of the molecule and releases another chemical molecule which alerts others to aggregate to the target. When nanorobots detect acoustic signals emitted by nanorobots reaching target, their paths will be planned according to intensity of acoustic signals and velocity characteristic of blood fluid. The simulations show that compared with the existed approaches, the proposed algorithm results in an increase of nanorobots’ population and a decrease of cost time to reach target site with the help of acoustic signals and velocity characteristic. As a whole, the results obtained suggest that the algorithm presented in this paper is a better strategy for approaching tumor tissue in local blood vessel by nanorobots.