Structural damage in ZnO bombarded by heavy ions

The effect of implantation parameters on damage build-up in ZnO bombarded with Bi and Er ions is studied by Rutherford backscattering/channelling spectrometry. The results show that the damage accumulation behaviour in ZnO is different dramatically from that in other semiconductors. In particular, a variation of implantation parameters, such as collision cascade density, sample temperature and ion flux, has only a minor influence on the damage accumulation in the crystal bulk for the case of such heavy ions. Moreover, an intermediate damage peak, between the surface and bulk defect peaks, is observed for all the irradiation conditions studied. The cascade density affects the behaviour of this intermediate peak with increasing ion dose.     

Improving the quality of layers deposited on rolling rolls by optimising the composition of flux-cored wires

ABSTRACT

Experiments were carried out to investigate the effect of adding carbon–fluorine compounds (the waste from metallurgical production) and nickel powder to the composition of flux-cored wires of the C–Si–Mn–Cr–W–V and C–Si–Mn–Cr–V–Mo alloying systems. The results show that the addition of these compounds to the composition of the charge for producing the wires of the 35V9Kh3SF and 25Kh5FMS types improves a large number of the characteristics of the deposited layer: reduces the extent of contamination with non-metallic inclusions, increases the hardness of the deposited layer, refines austenite grains and results in the formation of fine-dispersion carbides which in practice may improve the thermal resistance of rolling rolls, and also prevents the formation of a ferrite network which may have a beneficial effect on cracking resistance. The experimental results can be used to develop new compositions of flux-cored wires for hardfacing rolling rolls protected by Russian Federation patents. The hardfacing technologies of the rolls using these flux-cored wires with the C–Si–Mn–Cr–W and C–Si–Mn–Cr–V–Mo alloying systems are now produced by the ElSib company.     

Improvement of predicted fine and total particulate matter (PM) composition by applying several different chemical scenarios: a winter 2005 case study

A new method using several different chemical scenarios is developed to predict chemical composition of fine (PM2.5) and total (PM10) aerosol. This method improves the accuracy of predicted PM concentrations. The Mesoscale Model version 5 (MM5) and a 3-dimensional Eulerian chemical model (CAMx4.2) are used to predict PM2.5 and PM10 concentrations using gridded input emissions (from the "Total" group) over a 48-72 h time period for Christchurch (New Zealand) for winter 2005. The aerosol concentrations are obtained for four different chemical compositions (chemical scenarios) of the input aerosol emissions. PM2.5 chemical compositions are based on previous Christchurch winter studies and from observations in other countries with similar winter pollution problems, and used in CAMx4.2 to model seven winter 2005 heavy pollution episodes. The error between observed and modelled PM2.5 concentrations is based on predictions of fine aerosol that are derived from linear regression with PM10. It is used to find the minimum difference between modelled and observed PM2.5 for an observation site located in the Christchurch residential area. Combination of the chemical scenarios with analysis of the minimum error is used to create a new complex chemical scenario. The new complex scenario is used to re-calculate all pollution episodes to obtain new values of PM with minimum error compared with observed aerosol concentrations. Mean Absolute Error of the calculated PM2.5 (for all pollution episodes) decreased from 21-24 microg m(-3) to 14-16 microg m(-3) compared with observations. The chemical composition of the modelled PM2.5 is also discussed.     

Influence of Working Fluid in the Throttle Channels of Hydraulic Mounts on the Damping Properties

Russian Engineering Research - The influence of the reduced mass of the working fluid in the throttle channels of a hydraulic mount on its motion and damping is considered. The acceleration and...     

Precision calculation of the low-lying excited states of the Rf atom

Precision calculations of the ground and low-lying excited electronic states of the Rf atom (Z = 104) were performed. The relativistic effects were taken into account with the Dirac-Coulomb-Breit Hamiltonian. The finite nucleus size was taken into account in the Fermi model (A = 267). The correlation effects were described by the combined scheme that we suggested previously, which proved to be efficient: The relativistic coupled clusters method with one- and two-particle cluster amplitudes in the Fock space was used for describing the correlations of 44 outer electrons of the Rf atoms in a fairly large atomic basis set, and for the four valence electrons occupying the 7s, 7p, and 6d states, the contributions from three- and four-particle cluster amplitudes were taken into account using the complete configuration interaction method, but in a relatively small basis set. The relativistic configuration and term for the ground state of the Rf atom were refined, and the energies of its excitation to low-lying states were calculated. The accuracy of the calculation by the generalized relativistic effective core potential method was evaluated by comparing the results with those obtained similarly using the Dirac-Coulomb-Breit Hamiltonian.     

Dental enamel hypoplasia in children with combined congenital and hereditary defects in the development of the CNS and the locomotor system (infantile cerebral palsy, spinal cord hernias and myopathies)]

The incidence of hypoplasia in children with congenital and hereditary developmental defects of the central nervous system and the locomotor system is high (44.5 +/- 3.5%), much higher than the incidence of hypoplasia in children without neurological disorders (2.0 +/- 2.0%). This is explained by exposure of the fetus and newborn to numerous intensive factors complicating the biological anamnesis because of profound disturbances of the metabolic processes and largely responsible for the underlying neurological disease and defects of hard dental tissues presenting as hypoplasia of the enamel.     

A Two-Channel Power Amplifier with a Diplexer Output

To sum up the powers of two independent signals from a two-channel amplifier, a diplexer constructed with the use of small-sized directional couplers is used. The level of the intermodulation components of the output spectrum is decreased down to –60 dB. The output power of the signals is 10 and 75 W, respectively; the gain of the channel amplifiers is 40 dB; and the amplified signals are the video and audio signals of the TV channel 12.