Search results for "Ultima"
showing 10 items of 396 documents
Impact of electron beam irradiation on fish gelatin film properties
2016
International audience; The objective of this work was to display the effect of electron beam accelerator doses on properties of plasticized fish gelatin film. Electron spin resonance indicates free radical formation during irradiation, which might induce intermolecular cross-linking. Tensile strength for gelatin film significantly increases after irradiation (improved by 30% for 60 kGy). The vapour permeability is weakly affected by irradiation. Surface tension and its polar component increase significantly and are in accordance with the increase of wettability. So, irradiation may change the orientation of polar groups of gelatin at the film surface and crosslink the hydrophobic amino aci…
Biomaterial-Assisted Anastomotic Healing: Serosal Adhesion of Pectin Films
2021
Anastomotic leakage is a frequent complication of intestinal surgery and a major source of surgical morbidity. The timing of anastomotic failures suggests that leaks are the result of inadequate mechanical support during the vulnerable phase of wound healing. To identify a biomaterial with physical and mechanical properties appropriate for assisted anastomotic healing, we studied the adhesive properties of the plant-derived structural heteropolysaccharide called pectin. Specifically, we examined high methoxyl citrus pectin films at water contents between 17–24% for their adhesivity to ex vivo porcine small bowel serosa. In assays of tensile adhesion strength, pectin demonstrated significant…
Estudio experimental in vitro de la unión de dos compuestos híbridos a distintos cementos de resina compuesta
2019
La actual exigencia de máxima conservación de tejido dental sano ha potenciado el uso de restauraciones prostodóncicas parciales frente a las de recubrimiento total. La ausencia de retención mecánica obliga a un cementado adhesivo de dichas restauraciones sobre los dientes. En los últimos años han surgido nuevos materiales, como los compuestos híbridos con intención de mejorar las propiedades mecánicas y estéticas de los materiales utilizados hasta el momento como son las porcelanas y las resinas compuestas. Se presenta una revisión bibliográfica de los materiales sometidos a este estudio: cerámicas dentales, resinas compuestas, cementos de resina compuesta y materiales híbridos. El objetiv…
A new mixed-mode fracture criterion for large-scale lattice models
2014
Abstract. Reasonable fracture criteria are crucial for the modeling of dynamic failure in computational lattice models. Successful criteria exist for experiments on the micro- and on the mesoscale, which are based on the stress that a bond experiences. In this paper, we test the applicability of these failure criteria to large-scale models, where gravity plays an important role in addition to the externally applied deformation. Brittle structures, resulting from these criteria, do not resemble the outcome predicted by fracture mechanics and by geological observations. For this reason we derive an elliptical fracture criterion, which is based on the strain energy stored in a bond. Simulation…
Three single loops enhance the biomechanical behavior of the transtibial pull-out technique for posterior meniscal root repair
2017
Purpose: To investigate the effect of applying an additional suture to enhance the biomechanical behavior of the suture–meniscus construct used during the transtibial pull- out repair technique. Methods: A total of 20 fresh-frozen porcine tibiae with intact medial menisci were used. In one half of all speci- mens (N = 10), two non-absorbable sutures were passed directly over the meniscal root from the tibia side of the meniscus to the femoral side (2SS). In other ten specimens, three sutures were passed over the meniscal root (3SS). All specimens were subjected to cyclic loading followed by load-to-failure testing. Displacement of the construct was recorded at 100, 500, and 1000 cycles. Fur…
Muscle strength characteristics and central bone mineral density in women with recent onset rheumatoid arthritis compared with healthy controls.
1999
Muscle strength and bone mineral density (BMD) at the lumbar spine (BMDspine) and femoral neck (BMDfem) were determined in 20 healthy women and in 20 women with recent onset rheumatoid arthritis (RA). The mean duration of articular symptoms of the patients was eleven months and none of them had used glucocorticoids or disease modifying antirheumatic drugs. BMDs were measured by dual x-ray absorptiometry (DXA). Knee extension, trunk extension, and flexion as well as grip strength were measured with David 200 and Digitest dynamometers. BMDspine (1.17 g/cm2 and 1.20 g/cm2) and BMDfem (0.98 g/cm2 and 0.96 g/cm2) between the women with early RA and healthy women did not differ. However, knee ext…
Analysis and optimization of hybrid double lap aluminum-GFRP joints
2014
In this paper a systematic investigation of the mechanical performance of hybrid double-lap Al-GFRP bonded-bolted joints, has been carried out by using experimental analyses and numerical simulations. In order to detect the optimal geometric configuration, as well as to highlight the contribution of adhesive and bolts, the results relative to hybrid joints have been compared with those of simply adhesively bonded and simply bolted joints. The experimental and numerical results have shown that by using the minimum overlap length provided from theory, the bolt leads to a significant decreasing of both the maximum shear and the maximum peel stresses in the adhesive layer and, consequently, the…
Influence of sutures configuration on the strength of tendon-patch joints for rotator cuff tears treatment
2019
Abstract Purpose Massive rotator cuff tears are common in the aging population. The incidence of failed rotator cuff repairs is still quite high, especially in the treatment of full-thickness tears or revision repairs. In this context, natural and synthetic meshes can be used as augmentation scaffolds or as devices to close the gap between a retracted tendon and the bone. The purpose of this work is to evaluate the ultimate tensile strength of different tendon-patch joints in order to consider their use in the treatment of massive cuff tears. Materials and methods Porcine tendons and a synthetic low-density polypropylene mesh have been used. A preliminary study on the tensile strength of te…
Chapter 5. Overcoming scepticism? Belief and moral responsibility
2006
Este es el capítulo 5 de mi libro Moral Responsibility: the ways of scepticism (Routledge 2006). Los cuatro primeros capítulos son comentarios extensos a un importante argumento escéptico sobre la posibilidad de la responsabilidad moral, que puede reconstruirse o extraerse fácilmente a partir de la bibliografía actual sobre la responsabilidad moral. El argumento, que denomino SMR (por “Scepticism about Moral Responsibility”), puede formularse como sigue: Primera premisa (A): O el determinismo es verdadero o no lo es. Segunda premisa (B): Si el determinismo es verdadero, la responsabilidad moral no es posible. Tercera premisa (C): Si el determinismo no es verdadero, la responsabilidad moral …
Dynamics of hydrofracturing and permeability evolution in layered reservoirs
2015
International audience; A coupled hydro-mechanical model is presented to model fluid driven fracturing in layered porous rocks. In the model the solid elastic continuum is described by a discrete element approach coupled with a fluid continuum grid that is used to solve Darcy based pressure diffusion. The model assumes poro-elasto-plastic effects and yields real time dynamic aspects of the fracturing and effective stress evolution under the influence of excess fluid pressure gradients. We show that the formation and propagation of hydrofractures are sensitive to mechanical and tectonic conditions of the system. In cases where elevated fluid pressure is the sole driving agent in a stable tec…