Wear Assessment of a Novel Squeeze-Film Artificial Hip Joint

Abstract— This paper investigates the wear characteristics of a novel hip implant design. Key features of the design are elastic elements attached to the cup which provide a mechanical means for ball separation during the swing phase of the gait loading cycle. An Archard-based wear formulation was implemented utilizing the ANSYS finite element analysis program which relates contact pressure and sliding distance to linear wear depth. It is found that low-modulus elastic elements with bonded high-modulus metal coatings offer significant predicted improvement in linear and volumetric wear rates when compared with conventional implant geometries for gait cycle loading and kinematic conditions found in practice

Energy losses of solar neutrinos and the oscillation hypothesis

A formula for the stopping power of neutrinos interacting via the standard weak-interaction model, but incorporating the possibility of neutrino oscillations among the three flavors, is derived. The results are applied to study the solar-neutrino anomaly and it is found that the anomaly cannot be accounted for by many orders of magnitude from consideration of the energy losses of the neutrinos interacting with the solar matter, even if the oscillation hypothesis is found to be valid

SPHERICAL VS CYLINDRICAL ENGINE BEARINGS

ABSTRACT Spherical bearings have been used successfully in engines for some years. The spherical bearing geometry allows a simplified axisymmetric piston design; gradual rotation of the piston and rings results in axisymmetric sidewall wear, temperature distribution and thermal expansion. A previouslydescribed concept engine design incorporating a spherical joint piston was based on an existing production engine with a conventional cylindrical piston pin. Previously-developed finite element lubrication analysis methods are applied to both designs and predictive comparisons made. INTRODUCTION Spherical bearings have been used successfully in engines for some years. The large (400 mm bore) Sulzer Z40 series medium speed 4-stroke Diesel engine has a spherical piston bearing which has been well-documented by its maker The spherical bearing design allows a simplified axisymmetric piston design; gradual rotation of the piston and rings results in axisymmetric sidewall wear, temperature distribution and thermal expansion. Development of a low heat rejection Diesel engine sponsored by the Department of Energy (DOE) and monitored by NASA-Lewis began at Cummins Engine Company in 1989 and ended around 1995 [3-8]. The LE-55 (Low Emission, 55% thermal efficiency) concept engine design incorporating a spherical joint piston was based on an existing Cummins L10 production engine with a conventional cylindrical piston pin. The Cummins L10 was a 10 liter 6 cylinder in-line Diesel engine produced for 15 years ending around 1998. The SCE (Single-Cylinder Engine) L10 version used for test purposes formed the basis for successful life tests of LE-55 hardware

Alternaria dauci, agent causal des brûlures foliaires est pathogène sur différentes espèces végétales

Alternaria dauci, agent causal des brûlures foliaires est pathogène sur différentes espèces végétale

Is quantitative resistance qualitative? An example with two Alternaria Leaf Blight resistant carrot genotypes and four resistance assessment techniques

International audienc

Geochemistry of Precordillera serpentinites, western Argentina : evidence for multistage hydrothermal alteration and tectonic implications for the Neoproterozoic-early Paleozoic

Serpentinites are a powerful tool to evaluate mantle composition and subsequent alteration processes during their tectonic emplacement. Exposures of this type of rocks can be found in the Argentine Precordillera (Cuyania terrane) and Frontal Cordillera, both located in central-western Argentina, within the Central Andes. In these regions a Neoproterozoic to Devonian mafic-ultramafic belt composed of serpentinites, metabasaltic dikes/sills, pillow lavas (with an Enriched to Normal Mid-Ocean Ridge Basalts (E- to N-MORB) geochemical signature) and mafic granulites crop out, spatially associated with marine metasedimentary rocks. The serpentinite bodies consist of lizardite/chrysotile+brucite+magnetite, with scarce pentlandite and anhedral reddish-brown Cr-spinel (picotite, pleonaste and spinel sensu stricto) as relict magmatic phases. The original peridotites were moderately-depleted harzburgites (ultramafic cumulates) with an intermediate chemical signature between a mid-ocean ridge and an arc-related ophiolite. Whole-rock Rare Earth Elements (REE) patterns of serpentinites exhibit enriched REE patterns ((La/Yb)CN=13-59) regarding CI chondrite with positive Eu anomalies. These features are the result of an interaction between hydrothermal fluid and serpentinites, in which moderate temperature (350º-400ºC), CO2-rich, mildly basic hydrothermal fluid was involved and was responsible for the addition of Ca, Sr and REE to serpentinites. The presence of listvenites (silica-carbonate rocks) in the serpentinite margins allow us to infer another fluid metasomatism, where lowtemperatures (<250ºC), highly-oxidized, highly-acid fluid lead to the precipitation of silica. The association of these metasomatized serpentinite bodies with neoproterozoic continental margin sucessions and MORB magmatism at the suture zone of the Cuyania and Chilenia terranes suggests the development of an oceanic basin between them during the Neoproterozoic-early Paleozoic

Is host range of carrot restricted to Alternaria dauci?

International audienc

Evaluation of different methods for the characterization of carrot resistance to the alternaria leaf blight pathogen (Alternaria dauci) revealed two qualitatively different resistances

Alternaria leaf blight (ALB), caused by Alternaria dauci, is one of the most damaging foliar diseases of carrot worldwide. The aim of this study was to compare different methods for evaluating levels of carrot resistance to ALB. Three techniques were investigated by comparison with a visual disease assessment control: in vivo conidial germination, a bioassay based on a drop-inoculation method, and in planta quantification of fungal biomass by quantitative PCR (Q-PCR). Three carrot cultivars showing different degrees of resistance to A. dauci were used, i.e. a susceptible cultivar (Presto) and two partially resistant genotypes (Texto and Bolero), challenged with an aggressive or a very aggressive isolate of A. dauci. Both partially resistant genotypes produced a higher mean number of germ tubes per conidium (up to 3·42±0·35) than the susceptible one (1·26±0·18). The drop-inoculation results allowed one of the partially resistant genotypes (Bolero, log10(S+1) = 1·34±0·13) to be distinguished from the susceptible one (1·90±0·13). By contrast, fungal growth measured by Q-PCR clearly differentiated the two partially resistant genotypes with log10(I) values of 2·77±0·13 compared to the susceptible cultivar (3·65±0·13) at 15 days post-inoculation. This result was strongly correlated (r2 = 0·91) with the disease severity index scored at the same date. Data obtained with the different assessment methods strongly suggest that the Texto and Bolero genotypes have different genetic resistance sources