Phase Composition and Defect Substructure of Strengthening Layer Surfaced on Low Alloyed Steel

The microstructure and microhardness distribution in surface of low carbon Hardox 450 steel coated with alloyed powder wires of different chemical compositions are studied. It is shown that the microhardness of 6-8 mm thickness surfaced layer exceeds that of base metal by more than 2 times. The increased mechanical properties of surfaced layer are caused by the submicro and nanoscale dispersed martensite, containing the niobium carbides Nb2C, NbC and iron borides Fe2B. In the bulk plates a dislocation substructure of the net-like type with scalar islocation density of 10^11 cm^-2 is observed. The layer surfaced with the wire containing B possesses the highest hardness. The possible mechanisms of niobium and boron carbides formation in surfacing are discusse

The contrasting oceanography of the Rhodes Gyre and the Central Black Sea

The Rhodes Gyre, a prominent feature of the oceanography of the eastern Mediterranean, is modelled as a vertical, continuous flow, cylindrical reactor illuminated during the day at its upper end. If the Gyre is supposed to be in a steady state whilst the concentrations, C, of a chemical are being measured, the nett rate of formation or consumption of the chemical is given by -w d C/d z + u d C/d r, where w is the upward velocity of the water in the vertical, z , direction and u is the velocity of the water in the radial, r, direction. The behaviour of w and u is analysed to show that the Gyre may be used as a field laboratory in which rates of chemical change may be derived from depth profiles together with values of the surface velocities of the Gyre waters. In contrast, the central Black Sea is modelled as an ideal, strongly stratified sea in which the nett rates of formation or consumption of chemicals under steady state conditions are given by Ds d2C/ds 2, where s is the water density and Ds is an eddy diffusion coefficient. Computations reveal that, given better knowledge of its eddy diffusion coefficients, the Black Sea can also be treated as a field laboratory where rates of reaction mediated by bacteria may be derived from depth profiles

R-Functions and WA-Systems of Functions in Modern Information Technologies

The review report consists of five parts. It describes the main physical applications of atomic, WA-systems and R-functions

Fatigue life of silumin treated with a high-intensity pulsed electron beam

The regularities of the formation of the structure of silumin irradiated with a high-intensity electron beam in different modes are revealed using optical and scanning electron microscopy. The optimum irradiation mode that allows one to increase the fatigue life of this material by a factor of up to 3.5 is determined. The probable causes of the observed effect are investigated

Fatigue variation of surface properties of silumin subjected to electron-beam treatment

The analysis of structure-phase states modification of silumin subjected to electron beam treatment with the following fatigue loading up to the failure is carried out by methods of transmission electron diffraction microscopy. The tribology and strength properties of silumin surface after electron beam treatment and fatigue tests are studied and hardness decrease, wear coefficient and friction coefficient increase with the growth of cycles number are revealed. The possible reasons of the tribology and strength properties of silumin surface layers decrease are discussed

Observation of Crossover from Ballistic to Diffusion Regime for Excimer Molecules in Superfluid 4^4He

We have measured the temperature dependence of the time of flight of helium excimer molecules He2* in superfluid 4He and find that the molecules behave ballistically below 100mK and exhibit Brownian motion above 200 mK. In the intermediate temperature range the transport cannot be described by either of the models.Comment: 8 pages, 6 figures, submitted to the Proceedings of the International Conference on Quantum Fluids and Solids 201

Sym28, a gene controlling stem architecture and nodule number, is localized on linkage group V

Garden pea (Pisum sativum L.) represents one of the most important models for studying plant developmental genetics. This species serves as a model object for most investigations on the genetic control of formation of compound inflorescence, compound leaf and of symbiotic interaction with nitrogen-fixing bacteria (nodulation). The latter phenomenon is typical for most legumes and is of significant theoretical and practical interest. By now, multiple genes involved in the genetic control of nodulation have been identified (for review see (2)). One of the key processes in plant development is the regulation of stem apical meristem (SAM) activity. Studies on the model plant Arabidopsis thaliana (L.) Heynh. (Brassicaceae) demonstrated that equilibrium between SAM proliferation and keeping its volume stable is reached via the CLAVATA-WUSCHEL regulatory feedback loop. Expression of the gene WUSCHEL (WUS) maintains the meristematic condition of cells and activates expression of the CLAVATA (CLVI, CLV2 and CLV3) gene family. CLV proteins negatively regulate expression of WUS thus limiting its expression pool (14). Mutations in CLV genes lead to abnormal enlargement of the WUS-expressing zone resulting in flower and stem fasciation. Genes of the FASCIATA (FAS! and FAS2) family also serve as negative regulators of WUS (5)

A gene for stem fasciation is localized on linkage group III

Fasciation is one of the most widespread abnormalities of higher plant development. An understanding of the inheritance of the trait is very important, not only for theoretical purposes dealing with genetic control of meristem activity but also for practical use. Stem and fruit fasciation is used as an agriculturally valuable trait in selection of many species including pea (Pisum sativum L). The peculiarities of genetic control of fasciation in pea are still being discussed

Fractography of the fatigue fracture surface of silumin irradiated by high-intensity pulsed electron beam

The surface modification of the eutectic silumin with high-intensity pulsed electron beam has been carried out. Multi-cycle fatigue tests were performed and irradiation mode made possible the increase in the silumin fatigue life more than 3.5 times was determined. Studies of the structure of the surface irradiation and surface fatigue fracture of silumin in the initial (unirradiated) state and after modification with intense pulsed electron beam were carried out by methods of scanning electron microscopy. It has been shown, that in mode of partial melting of the irradiation surface the modification process of silicon plates is accompanied by the formation of numerous large micropores along the boundary plate/matrix and microcracks located in the silicon plates. A multi-modal structure (grain size within 30-50 μm with silicon particles up to 10 μm located on the boundaries) is formed in stable melting mode, as well as subgrain structure in the form of crystallization cells from 100 to 250 μm in size). Formation of a multi-modal, multi-phase, submicro- and nanosize structure assisting to a significant increase in the critical length of the crack, the safety coefficient and decrease in step of cracks for loading cycle was the main cause for the increase in silumin fatigue life