We have studied the correlation between the elastocaloric effect and the crystallographic direction where a uniaxial stress is applied in a textured polycrystalline Ni-Mn-In-Cr ferromagnetic shape memory alloy; this alloy displays martensitic transformation around room temperature and presents an L21 cubic structure in the austenite phase. The texture in the material was induced by simple arc melting synthesis; using inverse pole figures, a favored grain growth was shown in the direction [001] perpendicular to the cooled surface. The elastocaloric effect was determined by direct measurements of the adiabatic temperature change (ΔTadme), while compressive stress was applied and released; hereby, it has been shown that it is possible to exploit the columnar growth texture in order to obtain a large and reversible elastocaloric effect. The reversible elastocaloric response was measured between 280 and 310 K by applying moderate stresses of 50, 75, and 100 MPa in the [001], [111], and [011] directions. A strong interrelation was found in the cyclic ΔTadme values of −3.9, −2.0, and −1.3 K after unloading a compressive stress of 100 MPa applied mainly in the [001], [111], and [011] directions, respectively.
Significant difference was found between certain screw-angle configurations; however, when compared with simply placing the screws straight in, the difference was never more than 8%. This implies that there is greater freedom in the angle and placement of screws than previously thought. Our results show that there is little change in fixation strength when placing the screw in a different direction.
Evaluar el resultado funcional y la incidencia de complicaciones en una serie de trasplantes renales pediátricos utilizando injertos de donantes infantiles.MATERIAL Y MÉTODO: Se revisa una serie de 34 trasplantes renales en receptores pediátricos realizados de forma consecutiva. De ellos, en 19 casos (55,8%) el riñón procedía de donantes de edad inferior a 3 años (Grupo A). En 15 pacientes (44,2%), los donantes tuvieron una edad ≥ 3-6 años (Grupo B). Analizamos comparativamente el funcionalismo inmediato, complicaciones médicas y quirúrgicas, supervivencia del injerto y del paciente a medio y largo plazo.RESULTADOS: Observamos disfunción inicial del injerto en 9 pacientes del grupo A (47,4%). En el grupo B la incidencia fue del 46,7%. En el grupo A, 7 pacientes sufrieron complicaciones vasculares (36,7%) frente a 3 en el grupo B (20%) (p<0,05). Se produjeron más complicaciones vasculares en los riñones preservados en solución EC (35,3%) frente a UW (23,5%) (p<0,05). En el grupo A la supervivencia actuarial de los injertos a 10 años fue significativamente menor frente al grupo B (35,5%-58,6%, p<0,05). En base al tipo utilizado de solución de preservación, EC ofreció valores de supervivencia actuarial del injerto a 1-5-10 años de 47%-26,8%-26,8%; UW incrementó estas cifras a 82,3%-63%-63% (p<0,001).CONCLUSIONES: La limitación de la edad mínima para aceptación de donantes en Programas de Trasplante Renal Pediátrico en 3 años y la utilización de soluciones de preservación óptimas, resulta en una disminución de las complicaciones vasculares y un aumento de la supervivencia del injerto a largo plazo.
BackgroundScrew length pertains to stability in various orthopedic fixation devices. There is little or no information on the relationship between plate pullout strength and screw length in anterior lumbar interbody fusion (ALIF) plate constructs in the literature. Such a description may prove useful, especially in the treatment of osteoporotic patients where maximizing construct stability is of utmost importance. Our purpose is to describe the influence of screw length on ALIF plate stability in severely and mildly osteoporotic bone foam models.MethodsTesting was performed on polyurethane foam blocks with densities of 0.08 g/cm3 and 0.16 g/cm3. Four-screw, single-level ALIF plate constructs were secured to the polyurethane foam blocks by use of sets of self-tapping cancellous bone screws that were 20, 24, 28, 32, and 36 mm in length and 6.0 mm in diameter. Plates were pulled out at 1 mm/min to failure, as defined by consistently decreasing load despite increasing displacement.ResultsPullout loads in 0.08-g/cm3 foam for 20-, 24-, 28-, 32-, and 36-mm screws averaged 303, 388, 479, 586, and 708 N, respectively, increasing at a mean of 25.2 N/mm. In 0.16-g/cm3 foam, pullout loads for 20-, 24-, 28-, 32-, and 36-mm screws averaged 1004, 1335, 1569, 1907, and 2162 N, respectively, increasing at a mean of 72.2 N/mm.ConclusionsThe use of longer screws in ALIF plate installation is expected to increase construct stability. Stabilization from screw length in osteoporotic patients, however, is limited.
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