Origin and geochemical evolution of the Madeira-Tore Rise (eastern North Atlantic)

The Madeira-Tore Rise, located ∼700 km off the NW African coast, forms a prominent ridge in the east Atlantic. The age and origin of the rise are controversial. This study presents major and trace element, Sr, Nd, Pb, Hf isotope and 40Ar/39Ar age determinations from volcanic rocks dredged from different sites along the rise. In addition, isotopic compositions of rock samples from Great Meteor Seamount in the central Atlantic are presented. The new radiometric and paleontologically constrained ages identify two major episodes of volcanism: The first is the base of the rise (circa 80 to >95 Ma) and the second is seamounts on the rise (0.5–16 Ma). It is proposed that interaction of the Canary hot spot with the Mid-Atlantic spreading center formed the deep basement of the Madeira-Tore Rise and the J-Anomaly Ridge west of the Atlantic spreading center in the Mid-Cretaceous. Age and geochemical data and plate tectonic reconstructions suggest, however, that the recovered Late Cretaceous volcanic rocks represent late stage volcanism from the time when the Madeira-Tore Rise was still close to the Canary hot spot. Long after moving away from the influence of the Canary hot spot, the Madeira-Tore Rise was overprinted by late Cenozoic volcanism. Miocene to Pleistocene volcanism at the northern end of the rise can be best explained by decompression mantle melting beneath extensional sectors of the Azores-Gibraltar Fracture Zone (African-Eurasian plate boundary). The geochemical compositions of these volcanic rocks suggest that the magmas were variably contaminated by enriched material within or derived by melting of enriched material underplated at the base of the lithosphere, possibly originating from the Cretaceous Canary plume. Alternatively, these late Cenozoic volcanic rocks may have derived from decompression melting of enriched pyroxenitic/eclogitic material in the upper mantle. Isotopically more depleted Pliocene to Pleistocene volcanism at the southern end of the Madeira-Tore Rise may be related to the nearby Madeira hot spot

Osteoconductive properties of carbon fibre implants used in surgery of spine injuries and disorders (case report)

Purpose To assess osteoconductive properties of carbon fibre implants used in surgery of spine injuries and disorders. Materials and methods Two clinical cases from a multicentre prospective study on nanostructured carbon fibrous implants applied for a variety of spinal pathology are presented. Results The usage of highly porous carbon fibre implant resulted in bone and carbon fusion in the clinical instances whereas implants with a residual porosity of 7–12 % showed no fusion between bone and carbon. The patients had satisfactory clinical condition and quality of life. Discussion Carbon fibrous implant characteristics are close to those of bone tissue, being inert and osteoconductive along with high mechanical strength that ensure bone and carbon fibrous fusion with highly porous implan

Multifrequency optimization method of measurement the frequency dependency of electrophysical parameters of dielectric and magnetodielectric coatings

The issues of experimental determination of electrodynamic parameters of existing and new synthesized materials and coatings used in the microwave range are highlighted. Problems arising from measurements of the electrophysical and geometric parameters of dielectric and magnetodielectric coatings, taking into account their placement on a metal substrate, by radio wave methods are considered. We present the new radio wave method of joint measurements of the frequency dependence of the complex permittivity, the frequency dependence of the complex magnetic permeability, and the thickness of plane-layered samples of dielectric and magnetodielectric coatings on a metal substrate. Determination of electrophysical and geometric parameters of the coating in the proposed method is reduced to minimizing the objective function constructed based on the discrepancy between the experimental and design theoretical values of the attenuation coefficients of surface electromagnetic wave fields on a grid of discrete frequencies. The simulation model of measurements is shown, implemented on the basis of the electrodynamic modeling system CST Microwave studio (Simulia corporation, USA) and the Matlab system. The results of simulation are presented to determine the frequency dependences of the electrophysical parameters and the thickness of a sample of a radio-absorbing coating on a metal substrate. Errors in the estimates of permittivity and permeability in the measurement frequency band 9–13.5 GHz, which are no more than 10 % with a confidence level of 0.95 with a mean square deviation of the noise level of 0.006, have been obtained. The proposed method can be in demand in various science-intensive areas – microelectronic, aerospace, mechanical engineering, etc.</jats:p