Influence of bi content on the temperature of the formation of the hard magnetic MnBi phase: simultaneous irreversible drop of resistance

Pulsed laser-deposited (PLD) MnBi films were fabricated by alternating deposition of Mn and Bi layers. In order to obtain the ferromagnetic MnBi phase, heat treatments were performed on the samples. Simultaneously, the resistance of the samples was monitored as a function of the temperature. Thus, on increasing the temperature, a steep decrease in the resistance of the films was observed, simultaneous to the onset of the formation of the MnBi phase. At room-temperature, these annealed samples showed a ferromagnetic behavior, as well as the presence of the characteristic LT-MnBi phase diffraction peaks in the X-ray diffraction patterns. The temperature of the generation of the MnBi phase depended on the relative concentration of Mn and Bi in the different samples: on increasing the Bi atomic concentration, the temperature of the generation of the MnBi phase decreased

Los efectos de la práctica del fútbol sala en el estado óseo de futbolistas adolescentes medidos a través de ultrasonometría cuantitativa: un estudio comparativo.

La actividad física mejora la calidad y la densidad de la masa ósea como consecuencia de la carga mecánica que generan los impactos. Los deportes de alto impacto (fuerzas de reacción contra el suelo), como el fútbol, están relacionados con un mayor contenido mineral óseo, una mayor densidad ósea y una mejora de la geometría del hueso. El fútbol sala, un deporte, similar al fútbol, pero con características especiales en cuanto al impacto, no ha sido estudiado en detalle. Nuestro objetivo es el de, mediante ultrasonometría cuantitativa del calcáneo, determinar si existen diferencias significativas entre jugadores de fútbol sala y sujetos control en sus valores óseos. Los sujetos utilizados fueron 18 futbolistas (16,67±1,85 años) y 16 chicos sedentarios (16,19±1,47 años). Las medidas ultrasonométricas fueron tomadas en el calcáneo de la pierna no dominante mediante el equipo de ultrasonidos Achilles InSight. Se obtuvo así la atenuación del sonido de banda ancha (BUA) y la velocidad del sonido (SOS), así como el índice de rigidez (SI). La altura fue tomada con un tallímetro y el peso, la masa grasa y los porcentajes de grasa con un analizador de composición corporal Tanita BC 420 S MA. Se utilizó un modelo lineal general univariante para evaluar la significación de la diferencia entre las distintas comparaciones entre grupos a través del programa de análisis estadístico SPSS 15.0. Encontramos diferencias significativas entre el porcentaje de masa grasa de controles y futbolistas. No existen diferencias significativas entre los parámetros de ultrasonometría entre controles y futbolistas en ninguno de los casos (p>0,05). Sin embargo, en la comparación entre controles y futbolistas menores de 17 años por un lado, y mayores o iguales de 17 años por el otro, vemos que el SI es parejo en el caso del grupo de menor edad (Controles (113,48±6,28) vs Futbolistas (113,67±5,48)) y aumenta a favor de los futbolistas en el caso del grupo de mayor edad, reduciéndose en los controles (Controles (110,11±8,66), Futbolistas (119,36±8,66)). Esto muestra indicios no estadísticamente significativos de que la práctica de fútbol sala podría mejorar, con el paso del tiempo, la calidad ósea en adolescentes de entre 14 y 19 años y la empeora cuando esos adolescentes son sedentarios. Otros estudios teniendo en cuenta el mayor número de variables posibles, así como con mayores rangos de edad y de evolución temporal serán necesarios para aportar mayores evidencias

Generating and measuring the anisotropic elastic behaviour of Co thin films with oriented surface nano-strings on micro-cantilevers

In this research, the elastic behaviour of two Co thin films simultaneously deposited in an off-normal angle method was studied. Towards this end, two Si micro-cantilevers were simultaneously coated using pulsed laser deposition at an oblique angle, creating a Co nano-string surface morphology with a predetermined orientation. The selected position of each micro-cantilever during the coating process created longitudinal or transverse nano-strings. The anisotropic elastic behaviour of these Co films was determined by measuring the changes that took place in the resonant frequency of each micro-cantilever after this process of creating differently oriented plasma coatings had been completed. This differential procedure allowed us to determine the difference between the Young's modulus of the different films based on the different direction of the nano-strings. This difference was determined to be, at least, the 20% of the Young's modulus of the bulk Co

Magnetic anisotropy in isotropic and nanopatterned strongly exchange-coupled nanolayers

UPNa. Departamento de Física. Laboratorio de MagnetismoIn this study, the fabrication of magnetic multilayers with a controlled value of the in-plane uniaxial magnetic anisotropy field in the range of 12 to 72 kA/m was achieved. This fabrication was accomplished by the deposition of bilayers consisting of an obliquely deposited (54A degrees) 8-nm-thick anisotropic Co layer and a second isotropic Co layer that was deposited at a normal incidence over the first layer. By changing the thickness value of this second Co layer (X) by modifying the deposition time, the value of the anisotropy field of the sample could be controlled. For each sample, the thickness of each bilayer did not exceed the value of the exchange correlation length calculated for these Co bilayers. To increase the volume of the magnetic films without further modification of their magnetic properties, a Ta spacer layer was deposited between successive Co bilayers at 54A degrees to prevent direct exchange coupling between consecutive Co bilayers. This step was accomplished through the deposition of multilayered films consisting of several (Co8 nm-54A degrees/Co (X nm-0A degrees)/Ta6 nm-54A degrees) trilayers.This work was partially supported by the Spanish government under project MAT2007-66252

H2S biosynthesis and catabolism: new insights from molecular studies

Hydrogen sulfide (H2S) has profound biological effects within living organisms and is now increasingly being considered alongside other gaseous signalling molecules, such as nitric oxide (NO) and carbon monoxide (CO). Conventional use of pharmacological and molecular approaches has spawned a rapidly growing research field that has identified H2S as playing a functional role in cell-signalling and post-translational modifications. Recently, a number of laboratories have reported the use of siRNA methodologies and genetic mouse models to mimic the loss of function of genes involved in the biosynthesis and degradation of H2S within tissues. Studies utilising these systems are revealing new insights into the biology of H2S within the cardiovascular system, inflammatory disease, and in cell signalling. In light of this work, the current review will describe recent advances in H2S research made possible by the use of molecular approaches and genetic mouse models with perturbed capacities to generate or detoxify physiological levels of H2S gas within tissue

Tailoring Magnetic and Transport Anisotropies in Co_100−x–Cu_x Thin Films through Obliquely Grown Nano-Sheets

The magnetic and transport properties of pulsed laser-deposited Co100−x–Cux thin films were tailored through their nano-morphology and composition by controlling for the deposition geometry, namely normal or oblique deposition, and their Cu content. All films were composed of an amorphous Co matrix and a textured growth of Cu nanocrystals, whose presence and size d increased as x increased. For x = 50, all films were superparamagnetic, regardless of deposition geometry. The normally deposited films showed no in-plane magnetic anisotropy. On the contrary, controllable in-plane uniaxial magnetic anisotropy in both direction and magnitude was generated in the obliquely deposited films. The magnetic anisotropy field Hk remained constant for x = 0, 5 and 10, Hk ≈ 35 kAm−1, and decreased to 28 and 26 kAm−1 for x = 20 and 30, respectively. This anisotropy had a magnetostatic origin due to a tilted nano-sheet morphology. In the normally deposited films, the coercive field Hc increased when x increased, from 200 (x = 0) to 1100 Am−1 (x = 30). In contrast, in obliquely deposited films, Hc decreased from 1500 (x = 0) to 100 Am−1 (x = 30) as x increased. Activation energy spectra corresponding to structural relaxation phenomena in obliquely deposited films were obtained from transport property measurements. They revealed two peaks, which also depended on their nano-morphology and composition