40 research outputs found
Comparison study on the properties of the CaP coatings formed by RF-magnetron sputtering of the Mg- and Sr-substituted ß-tricalcium phosphate and hydroxyapatite
This article describes the influence of Mg and Sr substitutions in the structure of -tricalcium phosphate and hydroxyapatite powder targets on the deposition rate of coatings formed via RF-magnetron sputtering and their properties. It was revealed that even low doses of ionic substitutions in -tricalcium phosphate significantly affect deposition rate, morphology and physico-chemical properties of respective coatings. Similar doses of these substitutions in hydroxyapatite are not enough to influence the deposition rate, but they affect coating properties
Composite biphase coatings formed by hybrid technology for biomedical applications
Calcium-phosphate (CaP) coatings were formed via combining methods of microarc oxidation (MAO) and radiofrequency magnetron sputtering (RFMS). SEM, XPS, XRD and nanoindentation methods were used to study physico-chemical and mechanical properties of the coatings. It was revealed that the upper CaP layer changes the morphology of the coatings at the microscale and increases the Ca/P ratio of biphasic coatings
Influence of magnesium and strontium substitutions in the structure of hydroxyapatite lattice on the deposition rate and properties of the CaP coatings formed via RF-sputtering of the powder targets
This work is dedicated to studying of the properties of the calcium phosphate (CaP) coatings deposited on Ti substrates by radio-frequency magnetron sputtering (RFMS) of three hydroxyapatite-based powder targets: pure hydroxyapatite (HA), Mg-substituted HA (Mg-HA, Mg = 0.93 ± 0.13 at.%) and Sr-substituted HA (Sr-HA, Sr ∼ 0.47 at.%). The influence of ionic substitutions in the structure of the sputtered targets on the surface morphology, physicochemical properties of the coatings and their wettability were studied. It is revealed that Mg and Sr ionic substitutions in the crystal lattice of HA at these concentrations don't affect deposition rate, however, it influences morphology, wettability and elemental and phase composition of deposited coatings
Analytic approach to bifurcation cascades in a class of generalized H\'enon-Heiles potentials
We derive stability traces of bifurcating orbits in H\'enon-Heiles potentials
near their saddlesComment: LaTeX revtex4, 38 pages, 7 PostScript figures, 2 table
Analytical perturbative approach to periodic orbits in the homogeneous quartic oscillator potential
We present an analytical calculation of periodic orbits in the homogeneous
quartic oscillator potential. Exploiting the properties of the periodic
Lam{\'e} functions that describe the orbits bifurcated from the fundamental
linear orbit in the vicinity of the bifurcation points, we use perturbation
theory to obtain their evolution away from the bifurcation points. As an
application, we derive an analytical semiclassical trace formula for the
density of states in the separable case, using a uniform approximation for the
pitchfork bifurcations occurring there, which allows for full semiclassical
quantization. For the non-integrable situations, we show that the uniform
contribution of the bifurcating period-one orbits to the coarse-grained density
of states competes with that of the shortest isolated orbits, but decreases
with increasing chaoticity parameter .Comment: 15 pages, LaTeX, 7 figures; revised and extended version, to appear
in J. Phys. A final version 3; error in eq. (33) corrected and note added in
prin
Occurrence of periodic Lam\'e functions at bifurcations in chaotic Hamiltonian systems
We investigate cascades of isochronous pitchfork bifurcations of
straight-line librating orbits in some two-dimensional Hamiltonian systems with
mixed phase space. We show that the new bifurcated orbits, which are
responsible for the onset of chaos, are given analytically by the periodic
solutions of the Lam\'e equation as classified in 1940 by Ince. In Hamiltonians
with C_ symmetry, they occur alternatingly as Lam\'e functions of period
2K and 4K, respectively, where 4K is the period of the Jacobi elliptic function
appearing in the Lam\'e equation. We also show that the two pairs of orbits
created at period-doubling bifurcations of touch-and-go type are given by two
different linear combinations of algebraic Lam\'e functions with period 8K.Comment: LaTeX2e, 22 pages, 14 figures. Version 3: final form of paper,
accepted by J. Phys. A. Changes in Table 2; new reference [25]; name of
bifurcations "touch-and-go" replaced by "island-chain