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"Pietrzyk, B."
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Preliminary Characteristic of Composite Coatings C/Hap Produced Respectively by Rf Pacvd and Sol–Gel Methods
The required high mechanical strength and the reliability of implants on one side and a lack of toxic elements in those materials, on the other side, causes restrictions in use of metal alloys for austenitic steel, alloys of cobalt matrix and even titanium alloys. However, elements harmful to human body structure such as chromium, nickel and vanadium could not have been eliminated so far. An attempt to reduce detrimental effects of above elements on the living organism are surface modifications of materials predicted for implants through the deposition of protective layers. The C/HAp composite coating was prerared by deposition of carbon layer directly on surgical steel with RF PACVD method and manufacturing of hydroxyapatite layer by sol-gel method. It was proved that carbon film significantly increases adhesion of the composite C/HAp coating. It is due to the diffusive character of bonding between carbon layer and metallic substrate not only by adhesion as in the case with hydroxyapatite deposited directly on metal base. Adhesion of both synthesized coatings was determined using nanoindentation technique. X-Ray diffraction was used for phase composition evaluation. Atomic Force Microscope revealed topography of raw, carbon and C/HAp surfaces. Elemental composition of carbon and composite layers was investigated by scanning electron microscope equipped with x-ray energy dispersive spectroscopy detector.
Journal Article
Protective properties of composite oxide coatings deposited by sol-gel method
In this work, we compare the protective properties, morphology, and adhesion of unary and composite, sandwich Al
2
O
3
–TiO
2
coatings deposited on X5CrNi18-9 austenitic stainless steel using the sol-gel method. It is found that the type and sequence of the films in investigated composite sandwich coatings have essential influence on their properties. The best protective properties exhibit coatings in which Al
2
O
3
film is directly on the substrate surface. The best adhesion is revealed in coatings in which TiO
2
film is directly on the steel surface. It is found that composite oxide sol-gel coatings improve the resistance of stainless steel better then unary coatings both in the range of electrochemical and high-temperature corrosion. This improvement can result from mutual influence of titania and alumina films by delay of their crystallization process.
Journal Article
Effect of carbon interlayer on protective properties of hydroxyapatite coating deposited on 316L stainless steel by sol-gel method
Good-quality bilayer coatings with a carbon interlayer and outer carbonate hydroxyapatite layer are obtained on AISI 316L stainless steel substrate using RF PACVD and sol-gel methods. It is found that protective properties of both composite C/HAP coating and HAP coating depend on the temperature of heat treatment. Hydroxyapatite with a carbon interlayer coating annealed at 500°C significantly improves corrosion resistance of the stainless-steel substrate as well as of unary carbon and HAP coatings. The composite C/HAP coating annealed at 500°C exhibits better corrosion resistance in comparison with the HAP coating heated at the same temperature. Stainless-steel substrates with a HAP and C interlayer heated at 700°C have worse corrosion features in comparison with uncoated AISI 316L. The weak corrosion resistance of this sample is due to the formation of metal carbides at this temperature.
Journal Article
Measurement of the J/ψ pair production cross-section in pp collisions at s√=13TeV
The production cross-section of J/ψ pairs is measured using a data sample of pp collisions collected by the LHCb experiment at a centre-of-mass energy of s√=13TeV, corresponding to an integrated luminosity of 279±11pb−1. The measurement is performed for J/ψ mesons with a transverse momentum of less than 10GeV/c in the rapidity range 2.0
Journal Article
Search for the Λb→Λη′ and Λb→Λη decays with the LHCb detector
A search is performed for the as yet unobserved baryonic Λb→Λη′ and Λb→Λη decays with 3fb−1 of proton-proton collision data recorded by the LHCb experiment. The B0→K0Sη′ decay is used as a normalisation channel. No significant signal is observed for the Λb→Λη′ decay. An upper limit is found on the branching fraction of B(Λb→Λη′)<3.1×10−6 at 90% confidence level. Evidence is seen for the presence of the Λb→Λη decay at the level of 3σ significance, with a branching fraction B(Λb→Λη)=(9.3+7.3−5.3)×10−6.
Journal Article
Search for the B0s→η′φ decay
A search for the charmless B0s→η′ϕ decay is performed using pp collision data collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb−1. No signal is observed and upper limits on the B0s→η′ϕ branching fraction are set to 0.82×10−6 at 90% and 1.01×10−6 at 95% confidence level.
Journal Article
Study of the D0p amplitude in Λ0b→D0pπ− decays
An amplitude analysis of the decay Λ0b→D0pπ− is performed in the part of the phase space containing resonances in the D0p channel. The study is based on a data sample corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions recorded by the LHCb experiment. The spectrum of excited Λ+c states that decay into D0p is studied. The masses, widths and quantum numbers of the Λc(2880)+ and Λc(2940)+ resonances are measured. The constraints on the spin and parity for the Λc(2940)+ state are obtained for the first time. A near-threshold enhancement in the D0p amplitude is investigated and found to be consistent with a new resonance, denoted the Λc(2860)+, of spin 3/2 and positive parity.
Journal Article
Observation of the suppressed decay Λ0b→pπ−μ+μ
The suppressed decay Λ0b→pπ−μ+μ−, excluding the J/ψ and ψ(2S)→μ+μ− resonances, is observed for the first time with a significance of 5.5 standard deviations. The analysis is performed with proton-proton collision data corresponding to an integrated luminosity of 3fb−1 collected with the LHCb experiment. The Λ0b→pπ−μ+μ− branching fraction is measured relative to the Λ0b→J/ψ(→μ+μ−)pπ− branching fraction givingB(Λ0b→pπ−μ+μ−)B(Λ0b→J/ψ(→μ+μ−)pπ−)=0.044±0.012±0.007,where the first uncertainty is statistical and the second is systematic. This is the first observation of a b→d transition in a baryonic decay.
Journal Article
Measurement of forward W→eν production in pp collisions at s√=8TeV
A measurement of the cross-section for W→eν production in pp collisions is presented using data corresponding to an integrated luminosity of 2fb−1 collected by the LHCb experiment at a centre-of-mass energy of s√=8TeV. The electrons are required to have more than 20GeV of transverse momentum and to lie between 2.00 and 4.25 in pseudorapidity. The inclusive W production cross-sections, where the W decays to eν, are measured to be _(W)⁺ e⁺ₑ&=1124.4 2.1 21.5 11.2 13.0 pb, _(W)⁻ e⁻ₑ&= 809.0 1.9 18.1 7.0 09.4 pb, where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. Differential cross-sections as a function of the electron pseudorapidity are measured. The W+/W− cross-section ratio and production charge asymmetry are also reported. Results are compared with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. Finally, in a precise test of lepton universality, the ratio of W boson branching fractions is determined to be B(W e)/B(W )=1.020 0.002 0.019, where the first uncertainty is statistical and the second is systematic.
Journal Article
Production of associatedΥand open charm hadrons inppcollisions at√s̅=7and8 TeV via double parton scattering
Associated production of bottomonia and open charm hadrons inppcollisions at√s̅=7and8 TeV is observed using data corresponding to an integrated luminosity of 3 fb⁻¹accumulated with the LHCb detector. The observation of five combinations,Υ(1S)D⁰ ,Υ(2S)D⁰ ,Υ(1S)D⁺ ,Υ(2S)D⁺andΥ(1S)D⁺_(s) , is reported. Production cross-sections are measured forΥ(1S)D⁰andΥ(1S)D⁺pairs in the forward region. The measured cross-sections and the differential distributions indicate the dominance of double parton scattering as the main production mechanism. This allows a precise measurement of the effective cross-section for double parton scattering.
Journal Article