348 research outputs found
A geometric analysis of hallux valgus: correlation with clinical assessment of severity
<p>Abstract</p> <p>Background</p> <p>Application of plane geometry to the study of bunion deformity may represent an interesting and novel approach in the research field of hallux valgus. For the purpose of contributing to development of a different perspective in the assessment of hallux valgus, this study was conducted with three objectives: a) to determine the position on the intersection point of the perpendicular bisectors of the longitudinal axes of the first metatarsal and proximal phalanx (IP), b) to correlate the location of this point with hallux valgus deformity according to angular measurements and according to visual assessment of the severity carried out by three independent observers, and c) to assess whether this IP correlated with the radius of the first metatarsophalangeal arc circumference.</p> <p>Methods</p> <p>Measurements evaluated were intermetatarsal angle (IMA), hallux valgus angle (HVA), and proximal phalangeal articular angle (PPAA). The Autocad<sup>Âź </sup>program computed the location of the IP inside or outside of the foot. Three independent observers rated the severity of hallux valgus in photographs using a 100-mm visual analogue scale (VAS).</p> <p>Results</p> <p>Measurements of all angles except PPAA showed significantly lower values when the IP was located out of the foot more distantly and vice versa, significantly higher values for severe deformities in which the IP was found inside the foot (<it>p </it>< 0.001). The IP correlated significantly with VAS scores and with the length of the radius of the circle that included the first metatarsophalangeal arc circumference (<it>p </it>< 0.001)</p> <p>Conclusion</p> <p>The IP is a useful indicator of hallux valgus deformity because correlated significantly with IMA and HVA measurements, VAS scores obtained by visual inspection of the degree of deformity, and location of the center of the first metatarsophalangeal arc circumference.</p
Comparison of microstructure and mechanical properties at different length scales of WC-Co hardmetals consolidated by binder jetting 3D printing and hip
Additive Manufacturing (AM) is rapidly growing as a revolutionary technique. It provides an interesting ability to produce complex geometries, a key feature for enhancing performance and widening application fields of hardmetal components, limited characteristic for traditional processing techniques. Within this context, it is necessary to study the mechanical integrity of samples produced by AM [AMed] where it is expected to find characteristics linked to the shaping route followed, and study if they will have influence on the final behaviour regarding the mechanical properties expect for a specimen process by a traditional manufacturing route. This work aims to study the final microstructure, mechanical properties and layer assemblage at different length scales for a 12%wtCoâ WC grade hardmetals of medium grain size consolidated by binder jetting 3DP and subsequent SinterHIP. In addition, compare this results with the ones obtained from a 12%wtCoâWC specimens process by means of a traditional technique like Hot Isostatic Pressing (HIP) using the same raw material like in the AMed specimens. Hardness Vickers at macro- and microlength scale as well as scratch tests, using different loads and indenter tips, are conducted on both type of samples. The results are analysed and discussed in terms of oriented layer-like material assemblage effects on microstructural variability, mechanical response determined by intrinsic physical behaviour of the material and feedstock used
Preuves dâextensions flexurales dans lâavant-pays rifain : le bassin du Rharb-Mamora (Nord Maroc)
Le bassin du Rharb reprĂ©sente lâavant-pays de la CordillĂšre du Rif. La Mamora (nord du Maroc) correspond Ă
la bordure méridionale de ce bassin entre les nappes pré-rifaines alpines au nord et la Meseta hercynienne au sud.
La Mamora, largement couverte par des formations actuelles, lâanalyse du potentiel des ressources naturelles, leur
exploitation et leur gestion cohérente nécessitent une bonne connaissance des diverses formations et de leurs structures.
Lâanalyse et lâinterprĂ©tation de profils sismiques, de forages hydrogĂ©ologiques et pĂ©troliers ont permis de prĂ©ciser
les structures majeures de la Mamora, largement recouvertes par des sédiments néogÚnes.
La structure de cette région est contrÎlée par des failles au moins hercyniennes, bien connues dans le substratum
palĂ©ozoĂŻque. Les deux grandes familles, NE-SW et NW-SE, ont contrĂŽlĂ© lâĂ©volution palĂ©ogĂ©ographique (rĂ©partition des
faciĂšs et variations de la puissance des formations). La faille majeure dans cette rĂ©gion est la faille KĂ©nitra â Sidi-Slimane
(FK2S) [Zouhri et al., 2001]. Cette faille N110oE, à fort pendage N, est localisée au S du front de la nappe pré-rifaine
dont lâamortissement est aveugle. Elle se traduit par un effondrement progressif vers le N. Il pourrait sâagir dâune
rĂ©plique de la faille Rabat â Tiflet. La Mamora apparaĂźt ainsi comme une charniĂšre entre le Rharb subsident et la Meseta
marocaine stable depuis le MĂ©sozoĂŻque
Carbonaceous catalysts from orange pulp for limonene oxidation
The possibility of orange pulp utilization for nanoporous carbons production was investigated. Moreover, processing the obtained materials as limonene oxidation catalysts was studied as well. Limonene was separated from orange pulp obtained from fragmented orange peelsâthe waste from industrial fruits processingâby means of simple distillation. After the sepa-ration of limonene from the biomass, the dried orange pulp was converted to three types of nanoporous carbon catalysts: without activating agent, with NaOH, and with KOH. The catalysts were characterized by XRD, SEM, EDX, AFM, and sorption of N2 methods. The activities of the obtained catalysts were tested in the oxidation of limonene to perillyl alcohol (the main product), carveol, carvone, and 1,2-epoxylimonene and its diol. In the oxidation processes, hydrogen peroxide was used as the oxidizing agent. This work has shown for the first time that nanoporous carbons obtained from orange pulp waste, after separation of limonene, are active catalysts for limonene oxidation to industrially important value-added productsPeer ReviewedPostprint (published version
Intrinsic hardness of constitutive phases in WCâCo composites:Nanoindentation testing, statistical analysis, WC crystal orientation effectsand flow stress for the constrained metallic binder
The intrinsic hardness of the constitutive phases in WCâCo composites is investigated by combining experimental and statistical analysis nanoindentation techniques. It is done on the basis of considering the cemented carbide material as effectively heterogeneous at the microstructure scale, i.e. consisting of three phases defined by either different chemical nature (carbides and binder) or distinct carbide crystal orientation (i.e. with surface normal perpendicular to either basal or prismatic planes). As main outcome, experimentally measured and statistically significant intrinsic hardness values for the defined phases (WC and constrained metallic binder) are analyzed and determined. Besides the evidence of crystal anisotropy for the WC phase, they permit to identify and account the expected strengthening of the plastic-constrained metallic binder, a critical input parameter for hardness and toughness modelling as well as for microstructural design optimization of ceramic composites reinforced by ductile metallic ligamentsPeer ReviewedPostprint (author's final draft
Influence of copper on nickel-based catalysts in the conversion of glycerol
The catalytic transformation of glycerol to value-added compounds was investigated over bimetallic Ni-Cu/gamma-Al2O3 catalysts with Ni/Cu atomic ratios of 8/1, 4/1, 2/1, 1/1, 1/2, 1/4, and 1/8. XPS analysis revealed that the surface composition of the catalyst exhibited progressive enrichment of Cu as its content in the catalyst increased. H-2-chemisorption indicated that the total number of exposed Ni atoms decreased as the Cu content increased. As a result, deep hydrogenolysis to produce CH4 was inhibited by the addition of Cu to the Ni catalyst, yielding higher selectivity toward the dehydration products of glycerol such as hydroxyacetone.; FTIR spectra of adsorbed CO reveal that Cu asserts both geometric and electronic effects on the adsorption properties of Ni. The geometrical effect is visualized by the progressive disappearance of the bridge bound adsorbed CO on metallic Ni by the incorporation of Cu. This suggests that the deep hydrogenolysis of glycerol to CH4 formation requires an ensemble of adjacent active Ni atoms. The electronic effect of Cu on Ni is indicated by the red shift of the IR peak of adsorbed CO as the Cu content increases. The electronic interaction between Cu and Ni species was also substantiated by XANES results. HTREM revealed metal particles very well distributed on the support with particle size of 1.5 to 5 nm. The Ni Cu samples were not a total intermetallic alloys. (C) 2014 Elsevier B.V. All rights reserved.Postprint (published version
Intrinsic hardness of constitutive phases in WC-Co composites: Nanoindentation testing, statistical analysis, WC crystal orientation effects and flow stress for the constrained metallic binder
The intrinsic hardness of the constitutive phases in WC-Co composites is investigated by combining experimental and statistical analysis nanoindentation techniques. It is done on the basis of considering the cemented carbide material as effectively heterogeneous at the microstructure scale, i.e. consisting of three phases defined by either different chemical nature (carbides and binder) or distinct carbide crystal orientation (i.e. with surface normal perpendicular to either basal or prismatic planes). As main outcome, experimentally measured and statistically significant intrinsic hardness values for the defined phases (WC and constrained metallic binder) are analyzed and determined. Besides the evidence of crystal anisotropy for the WC phase, they permit to identify and account the expected strengthening of the plastic-constrained metallic binder, a critical input parameter for hardness and toughness modelling as well as for microstructural design optimization of ceramic composites reinforced by ductile metallic ligaments. (C) 2015 Elsevier Ltd. All rights reserved.Postprint (published version
Ligand migration from cluster to support: a crucial factor for catalysis by Thiolate-protected gold clusters
Thiolate
protected
metal
clusters
are valuable
precursors
for the
design
of tailored
nanosized
catalysts.
Their
performance
can
be tuned
precisely
at atomic
level,
e.g. by the configuration/
type
of ligands
or by partial/complete
removal
of the ligand
shell
through
controlled
pre-treatment
steps.
However,
the
interaction
between
the ligand
shell
and
the oxide
support,
as
well
as ligand
removal
by oxidative
pre-treatment,
are
still
poorly
understood.
Typically,
it was
assumed
that
the thiolate
ligands
are simply
converted
into
SO
2
, CO
2
and
H
2
O. Herein,
we
report
the first
detailed
observation
of sulfur
ligand
migration
from
Au to the oxide
support
upon
deposition
and
oxidative
pre-treatment,
employing
mainly
S K-edge
XANES.
Conse-
quently,
thiolate
ligand
migration
not only
produces
clean
Au
cluster
surfaces
but
also
the
surrounding
oxide
support
is
modified
by sulfur-containing
species,
with
pronounced
effects
on catalytic
propertiesPeer ReviewedPostprint (published version
Tectonic evolution of the Eastern Moroccan Meseta: from Late Devonian foreâarc sedimentation to Early Carboniferous collision of an Avalonian promontory
This study was founded by the Ministerio de Economia y Competitividad (MINECO) of Spain through the project PANGEATOR (CGL2015-71692-P) and the Doctoral scholarship BES-2016-078168. GeoHistory Facility instruments were funded via an Australian Geophysical Observing System grant provided to AuScope Pty Ltd. by the AQ44 Australian Education Investment Fund program. The NPII multicollector was obtained via funding from the Australian Research Council LIEF program (LE150100013). The authors want to express their gratitude to Dr. Manuel Francisco Pereira (University of Evora, Portugal) and Dr. Michel Villeneuve (Centre Europeen de Recherche et d'Enseignement des Geosciences de l'Environnement, France) for their constructive reviews that helped to improve the quality of the original manuscript. Special thanks to Brad McDonald (Curtin University, Australia) for technical assistance regarding LA-ICPMS and Hf analyses, Profs. Abdelfatah Tahiri (University Mohammed V of Rabat, Morocco) and Hassan El Hadi (University Hassan II of Casablanca, Morocco) for their support during field work, Prof. Yvette Kuiper (Colorado School of Mines, USA) for her precious hints about the interpretation of Hf data, and Dr. Lorenzo Valetti for proofreading the manuscript. Supporting information can be obtained in Mendeley Data: https://doi.org/10.17632/b8fdbykmbx.1 (https://data.mendeley.com/datasets/b8fdbykmbx/draft?a=eaae2da0-8e224056-861b-4824984f1c10).The deformed Paleozoic succession of the Eastern Moroccan Meseta crops out in relativelysmall and isolated inliers surrounded by Mesozoic and Cenozoic rocks. Two of the largest inliers(Mekkam and Debdou) are characterized by a monotonous succession of slates and greywackes affected bypolyphasic folding that occurred at lowâto very low grade metamorphic conditions. New UâPb ages ondetrital zircon grains from the DebdouâMekkam metasediments constrain the maximal depositional age asLate Devonian, interpreted to be close to the true sedimentation age. Furthermore, theΔHfvalues of theDevonian detrital zircons, together with the presence of a series of scattered zircon grains with ages betweenc. 0.9 and c. 1.9 Ga, suggest provenance from a subductionârelated magmatic arc located on the Avalonianmargin. The DebdouâMekkam massif is characterized by an Early Carboniferousfirst deformationalevent (D1), which gave way to a pervasive cleavage (S1) associated with plurikilometricâscale, tight toisoclinal, overturned to recumbent folds. Later events (Dc) occurred at Late Carboniferous time andgenerated variably developed crenulation cleavages (Sc) associated with variously oriented metricâtokilometricâscale folds, which complicate the pattern of both D1 intersection lineations (L1) and axial traces.The restoration of this pronounced curved pattern yields originally SWâNEâoriented D1 fold axes withregional SEâvergence. This important Early Carboniferous shortening and SEâdirected tectonic transport canbe explained by closure of the Rheic Ocean and thefirst phases of the collision between the northern passivemargin of Gondwana and an Avalonian promontory.Ministerio de Economia y Competitividad (MINECO) of Spain
CGL2015-71692-P
BES-2016-078168Australian Geophysical Observing SystemAustralian Education Investment Fund program
AQ44Australian Research Council
LE15010001
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