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Soil microbial flora has an important role in the life of plants, providing them with nutrients and other factors. The research was aimed at studying the effect of the long-time fertilizer application on the number and composition of the microbial flora in the soil, involved in the synthesis and decomposition of organic matter. Studies were conducted in the Vth field rotation with a crop alternation: fallow land, winter rye, summer wheat with clover under sow, clover of the first year of use, clover of the second year of use, barley, potato and oat. We studied the effectiveness of various systems of fertilizers (organic, mineral, organic and mineral). Soil of experimental field was sod-podzolic. The use of arable land without fertilizers during five crop rotations (40 years) has led to a significant reduction of humus content, exchangeable potassium, and soil acidification. The use of mineral fertilizer systems also acidifies the soil. Joint application of manure and fertilizers led to an increase humus content in the soil. All the studied fertilizer systems increased the content of mobile phosphorus and exchangeable potassium and significantly changed its biological state of soil. Long-time use of fertilizer systems, compared with the control, helped to increase the total number of microorganisms, nitrogen-fixing and nitrifying bacteria, nitrification and cellulolytic activity of soil and carbon dioxide production. On the basis of conducted studies we have established the feasibility of long-time use of organic and mineral fertilizer system with saturation of arable land with manure of 10 t/ha and with an equivalent amount of mineral fertilizers for improvement of bacteria activity involved in nitrogen regime, soil respiration, processes of decomposition and the replenishment of organic matter that increase soil fertility. [ABSTRACT FROM AUTHOR]

The paper examines agrochemical properties and the nitrogen regimen of sod-podzolic soil under a mixed forest of the Cis-Urals. It has been established that the investigated soil is characterized by a highly acidic reaction throughout the profile. It has a pronounced podzolic horizon 10 cm in thickness depleted of calcium and magnesium cations. The humus content sharply decreases from 4.44% in the eluvial–humus horizon to 0.27% in the parent rock. It has been shown that the total nitrogen content decreases from 3318 mg/kg in the A1 horizon to 644 mg/kg in the A2B horizon and then changes insignificantly. The soil is characterized by a high percentage of nonhydrolyzable (64.91%) and not readily hydrolyzable nitrogen (24.81%) and a low content of mineral nitrogen assimilated by plants (2.36%) in the eluvial–humus horizon. It was revealed that the supply of nitrogen mobile forms in forest soil is high, the content of easily hydrolyzable nitrogen is 267.4 mg/kg, and content of mineral nitrogen is 73.8 mg/kg. [ABSTRACT FROM AUTHOR]

Nowadays, scientists investigate new more efficient materials for creating solar cells. One of such materials is thin films of barium disilicide. In this paper, we describe formation of BaSi2 films on Si(111) by layer-by-layer solid phase epitaxy and study their optical properties in visible and infrared range. [ABSTRACT FROM AUTHOR]

A study was made of the influence of aluminium and magnesium hydroxides on certain physicomechanical, processing, and service properties of plasticised polyvinyl chloride. It was shown that the use of a mixture of aluminium and magnesium hydroxides leads to a considerable increase in thermal stability and to an improvement in a number of fire safety properties. [ABSTRACT FROM AUTHOR]

Formation of calcium silicide on three types of templates: Si(111)7 × 7, 2D Mg2Si, and 3D Mg2Si, was studied during Ca deposition at 120 °C in situ by Auger and electron energy loss spectroscopy, and by differential optical reflectance spectroscopy. A continuous Ca2Si layer is formed on 2D and 3D Mg2Si templates; but, on an atomically clean silicon surface (Si(111)7 × 7), a mixture of Ca2Si with another Ca silicide was found. The growth of a Si cap layer over the Ca silicide layers at about 100 °C studied by in situ methods demonstrated the full embedding of Ca silicide in amorphous silicon, independent of the used template. Transmission electron microscopy, Rutherford backscattering spectrometry, atomic force microscopy, and electrical characterization of Schottky junctions revealed the Ca2Si and Mg2Si nanoparticles and the redistribution of Mg and Ca during the silicon cap growth and its effect on the electronic properties of the structures. Reproduction of the experiments on higher doped and better purity substrates is needed to understand better the role of Mg- and Ca-related defects, and defects of silicon generated by the growth process. [ABSTRACT FROM AUTHOR]

The design of a facility for studying luminescence of cryogenic liquids (nitrogen and helium) is described. Luminescence is excited by ∼0.573-MeV β particles and 0.656-MeV positrons emitted by a radioactive source based on 64Cu radionuclide, which is immersed in a liquid. [ABSTRACT FROM AUTHOR]

The alanine (Ala)-based cluster models of C5, C7, and C10 H-bonds are studied at the DFT/B3LYP level. CPMD/BLYP simulations of the infinite polyalanine α-helix (C13 H-bond) and the two-stranded β-sheets are performed. Combined use of frequency shifts and electron-density features enable us to detect and describe quantitatively the non-covalent interactions (H-bonds) defining the intrinsic properties of Ala-based secondary structures. The energies of the primary N&bond;H$\cdots $O H-bonds are decreasing in the following way: C13 > C5 ≥ C7 > C10. The energies of the secondary N&bond;H$\cdots $O, N-H$\cdots $N, and H$\cdots $H interactions are comparable to those of the primary H-bonds (∼4.5 kcal/mol). Side chain–backbone C&bond;H$\cdots $O interaction is found to be the weakest non-covalent interaction in the considered species. Its energy is ∼0.5 kcal/mol in the infinite polyalanine α-helix. Quantum-topological electron-density analysis is found to be a powerful tool for the detection of secondary non-covalent interactions (C&dbond;O$\cdots $H&bond;C and H$\cdots $H) and bifurcated H-bonds, while the frequency shift study is useful for the identification and characterization of primary or secondary H-bonds of the N&bond;H$\cdots $O type. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]