1,891 research outputs found
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
Torsion units in integral group rings of Janko simple groups
Using the Luthar--Passi method, we investigate the classical Zassenhaus
conjecture for the normalized unit group of integral group rings of Janko
sporadic simple groups. As a consequence, we obtain that the Gruenberg-Kegel
graph of the Janko groups , and is the same as that of the
normalized unit group of their respective integral group ring.Comment: 23 pages, to appear in Math.Comp
Search for EC and ECEC processes in Sn
Limits on EC (here EC denotes electron capture) and ECEC processes
in Sn have been obtained using a 380 cm HPGe detector and an
external source consisting of 53.355 g enriched tin (94.32% of Sn). A
limit with 90% C.L. on the Sn half-life of y for
the ECEC(0) transition to the excited state in Cd (1871.0
keV) has been established. This transition is discussed in the context of a
possible enhancement of the decay rate by several orders of magnitude given
that the ECEC process is nearly degenerate with an excited state in the
daughter nuclide. Prospects for investigating such a process in future
experiments are discussed. The limits on other EC and ECEC processes
in Sn were obtained on the level of y at the
90% C.L.Comment: 14 pages, 4 figure
Formation Wear Resistant Coatings on Martensite Steel Hardox 450 by Welding Methods
By methods of modern physical materials science the investigations analysis of phase composition, defect substructure, mechanical and tribological properties of Cr-Nb-C-V containing coatings formed in surfacing on martensitic wear resistant steel Hardox 450 were carried out. It was shown that surfacing resulted in the formation of high strength surface layer 6 mm in thinness. This layer had wear resistance 138 times greater than that of the base and friction coefficient 2.5 times less. Having analyzed the deflected mode of the deposited material in conditions of friction, a conclusion is drawn that plastic shear deformation is localized in the surface layer due to the high friction factor, as the result, scratches are formed. The maximum of tangential stress is deflected deep into the material provided that friction factor is low. On the basis of the investigations by methods of X-ray structural analysis and transmission diffraction electron microscopy it was shown that increase strength and tribological properties of surfacing metal were caused by its phase composition and state of defect substructure, namely, availability of interstitial phases (more than 36%) and martensitic type of a-phase structure
Structure-phase states of silumin surface layer after electron beam and high cycle fatigue
Modification of eutectic silumin surface has been implemented by high-intensity pulsed electron beam. The irradiation mode has been revealed; it allows increasing silumin fatigue life in more than 3.5 times. It has been established that the main reason of this fact is the formation of a multiphase submicro- and nanosized structure. It has been elicited that the most danger stress concentrators are large silicon plates situated on the surface and near-surface layers
Effect of the Frequency of Probiotic Use on the Productivity and Incubation Properties of Eggs of the Meat Production Direction
The use of probiotics Levisel SB Plus and Cellobacterin-T in the amount of 0.50 kg/t of mixed fodder in the diet of young herd replacement of the meat direction during the growing period from 3 to 45 days allowed to get homogeneity by 20.9 and 13.1 % above the analogues of the control group. Probiotic feed additive Levisel SB Plus increased the number of fertilized eggs by 1.96 %, hatchability – by 0.90 %, hatchery waste decreased by 2.7 %, feed costs decreased by 9.6 %. However, the best production results were shown by the group with a similar rate of probiotic Cellobacterin-T introduction, which had these indicators, respectively, of 2.0 %, 1.28, 4.2 and 10.4 %
Grazing-incidence Small-angle X-ray Scattering Technique for Probing Nanostructures and Processes at Nanoscale
The paper presents the grazing-incidence small-angle X-ray scattering technique and its application to the studies of self-assembly and re-assembly effects of colloidal nanoparticles. Two basic cases are exemplified - solvent evaporation driven self-assembly and self-assembly driven by barrier movement in the Langmuir-Blodgett trough. Studies of the nanoparticle re-assembly effects due to the surfactant removal
complete the overview. These examples document strength of GISAXS for an in situ tracking of processes at nanoscale. The results have direct implications for tailored preparation of the self -assembled nanoparticle templates for sensing, plasmonics and other applications
Enthalpies of Sublimation, Solution, and Solvation of N-Arylmaleimides
The enthalpies of sublimation of a series of substituted N-arylmaleimides [H, p-CH3, p-Br, p-CH3O, m-NO2, p-NO2, and p-N(CH3)2] and the enthalpies of their solution in chloroform, dimethylformamide, dioxane, acetonitrile, and carbon tetrachloride at 298 K were determined calorimetrically. The enthalpies of solvation decrease in the above series of solvents. Hydrogen bonding of imides in chloroform contributes much to the enthalpy of solvation; this contribution decreases on passing to arylmaleimides with electron-withdrawing substituents
Solvent effect on the partial molar volume and the enthalpy of solution of gallium chloride
Partial molar volumes and heats of solution were determined for gallium chloride in benzene, toluene, o-xylene, mesitylene, 1,2-dichloroethane, ethyl acetate, acetonitrile, and 1,4-dioxane. A proportionality in changes in these characteristics is observed for weak π,ν-type complexes in alkylbenzene medium. The partial molar volumes of strong n,ν-type complexes approach a limiting value
Excitation-energy dependence of the mechanism for two-photon ionization of liquid H2O and D2O from 8.3to12.4eV
This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/125/4/10.1063/1.2217738.Transient absorption measurements monitor the geminate recombination kinetics of solvated electrons following two-photonionization of liquid water at several excitation energies in the range from 8.3to12.4eV. Modeling the kinetics of the electron reveals its average ejection length from the hydronium ion and hydroxyl radical counterparts and thus provides insight into the ionization mechanism. The electron ejection length increases monotonically from roughly 0.9nm at 8.3eV to nearly 4nm at 12.4eV, with the increase taking place most rapidly above 9.5eV. We connect our results with recent advances in the understanding of the electronic structure of liquid water and discuss the nature of the ionization mechanism as a function of excitation energy. The isotope dependence of the electron ejection length provides additional information about the ionization mechanism. The electron ejection length has a similar energy dependence for two-photonionization of liquid D(2)O, but is consistently shorter than in H(2)O by about 0.3nm across the wide range of excitation energies studied
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