Influence of the mineral staggering on the elastic properties of the mineralized collagen fibril in lamellar bone

In this work, a three-dimensional finite element model of the staggered distribution of the mineral within the mineralized collagen fibril has been developed to characterize the lamellar bone elastic behavior at the sub-micro length scale. Minerals have been assumed to be embedded in a collagen matrix, and different degrees of mineralization have been considered allowing the growth of platelet-shaped minerals both in the axial and the transverse directions of the fibril, through the variation of the lateral space between platelets. We provide numerical values and trends for all the elastic constants of the mineralized collagen fibril as a function of the volume fraction of mineral. In our results, we verify the high influence of the mineral overlapping on the mechanical response of the fibril and we highlight that the lateral distance between crystals is relevant to the mechanical behavior of the fibril and not only the mineral overlapping in the axial direction.The authors acknowledge the Ministerio de Economia y Competitividad the financial support given through the project DPI2013-46641-R and to the Programme Prometeo 2012/023.Vercher Martínez, A.; Giner Maravilla, E.; Arango Villegas, C.; Fuenmayor Fernández, FJ. (2015). Influence of the mineral staggering on the elastic properties of the mineralized collagen fibril in lamellar bone. Journal of the Mechanical Behavior of Biomedical Materials. 42:243-256. https://doi.org/10.1016/j.jmbbm.2014.11.022S2432564

Rainfall characteristics in León in 2016 and 2017

Ponencia presentada en: XXXV Jornadas Científicas de la AME y el XIX Encuentro Hispano Luso de Meteorología celebrado en León, del 5 al 7 de marzo de 2018.Nowadays, air pollution is one of the principal risk to human health and rain is the main sink of aerosol particles in the atmosphere, since it is the main process to mitigate pollution. Furthermore, the study of rainfall characteristics is crucial because it can provide information about present and future risks in an area, related to rain amount or intensity. In order to know the characteristics of the precipitation in the city of León, rain was sampled during 2016 and 2017 using a Laser Precipitation Monitor (LPM) of Thies Clima which registered drops between 0.125 and 8 mm in 22 channels. Furthermore, a Circulation Weather Types (CWTs) classification was carried out based on Lamb (1972), to identify the weather type related to a peculiar synoptic situation in days with rain. Focusing on rain characteristics in the city of León, 3.23·109 drops m-2 have fallen in 2016 with a mean size of 0.36±0.20 mm and 1.06·109 drops m-2 in 2017 with a mean size of 0.35±0.19 mm. The rain characteristic according to Lamb Weather Types during rain events will be analyzed.This work was partially supported by the Spanish Ministry of Economy and Competitiveness (Grant TEC2014-57821-R), the University of Leon (Programa Propio 2015/00054/001) and the AERORAIN project (Ministry of Economy and Competitiveness, Grant CGL2014-52556-R, ERDF co-financed)

Pensamiento espacial a través del doblado del papel

Se presenta un trabajo en el que se presentarecoge una metodología de enseñanza mediante el doblado del papel para el tratamiento de la geometría en el aula

Numerical modelling of the mechanical behaviour of an osteon with microcracks

In this work, we present two strategies for the numerical modelling of microcracks and damage within an osteon. A numerical model of a single osteon under compressive diametral load is developed, including lamellae organized concentrically around the haversian canal and the presence of lacunae. Elastic properties have been estimated from micromechanical models that consider the mineralized collagen fibrils reinforced with hydroxyapatite crystals and the dominating orientation of the fibrils in each lamella. Microcracks are simulated through the node release technique, enabling propagation along the lamellae interfaces by application of failure criteria initially conceived for composite materials, in particular the Brewer and Lagace criterion for delamination. A second approach is also presented, which is based on the progressive degradation of the stiffness at the element level as the damage increases. Both strategies are discussed, showing a good agreement with experimental evidence reported by other authors. It is concluded that interlaminar shear stresses are the main cause of failure of an osteon under compressive diametral load.The authors wish to thank the Ministerio de Economia y Competitividad for the support received in the framework of the projects DPI2010-20990 and DPI2013-46641-R and to the Generalitat Valenciana, Programme PROMETEO 2012/023. The authors also thank Mr. Carlos Pons Gomez for his help in the development of some of the numerical models.Giner Maravilla, E.; Arango Villegas, C.; Vercher Martínez, A.; Fuenmayor Fernández, FJ. (2014). Numerical modelling of the mechanical behaviour of an osteon with microcracks. Journal of the Mechanical Behavior of Biomedical Materials. 37:109-124. https://doi.org/10.1016/j.jmbbm.2014.05.006S1091243

Complications of transvaginal radiofrequency ablation of fibroids: A 5-year experience

Introduction: Transvaginal radiofrequency ablation is a relatively noninvasive approach for the treatment of fibroids in patients who do not wish to undergo conventional surgery. Information on potential complications of this novel technique is very scarce. Methods: Retrospective, descriptive, epidemiological study of 115 patients who underwent transvaginal radiofrequency ablation of fibroids and for whom complications were recorded. Results: We performed 115 transvaginal radiofrequency ablation procedures, we recorded a total of 11 complications (9.6%; 95% CI, 3.8-14.8). Of these, 8 (7.0%) were classified as Clavien-Dindo type I, 1 (0.9%,) as type II, and 2 (1.7%) as type IIIb (severe). No other complications were recorded in a year follow-up. Conclusion: Transvaginal radiofrequency ablation is a treatment option that malees it possible to treat fibroids that are difficult to manage using other techniques. Few associated complications have been described, and most of them are mild

Estudio cinético de la gasificación de residuos de la industria azucarera

Se estudió la cinética de la gasificación de los productos sólidos resultantes de la pirólisis del bagazo y los residuos agrícolas de la caña de azúcar, en el rango de temperaturas de 623 a 823 K con aire diluido (10% de O₂). Los datos cinéticos obtenidos mediante análisis termogravimétrico isotérmico se representaron considerando una reacción de una sola etapa global con un número reducido de parámetros. El modelo aplicado ajusta satisfactoriamente los resultados experimentales en el rango de temperaturas estudiado.Facultad de Arquitectura y Urbanism

Bagazo de caña de azúcar: ensayos preliminares para su empleo en la producción de carbón activado

Se estudia la preparación de carbones activados empleando bagazo de caña de azúcar, como materia prima, mediante pirólisis y activación con bajas concentraciones de oxígeno, diferentes temperaturas y tiempos de activación. Se analizan las características de los adsorbentes preparados en las distintas condiciones de operación, a partir de la evaluación de su capacidad de adsorción. Con este propósito, se determinan las isotermas de adsorción de nitrógeno a 77 K y se calculan las áreas específicas. Las condiciones de activación afectan la calidad del producto obtenido.Facultad de Arquitectura y Urbanism

Preparación de carbón activado a partir de residuos agrícolas de la caña de azúcar y distintos agentes activantes

Los carbones activados son cada día más utilizados para el mejoramiento del medio ambiente por su elevada capacidad de adsorción, la cual los hace apropiados para eliminar diversos contaminantes de efluentes líquidos y/o gaseosos. En este trabajo, se estudia la preparación de carbones activados a partir de residuos agrícolas de la caña de azúcar (RAC) mediante pirólisis y posterior gasificación parcial empleando comparativamente bajas concentraciones de O₂ o CO₂, a diferentes temperaturas y tiempos de activación. Se analizan las características de los adsorbentes preparados en las distintas condiciones de operación a partir de la evaluación de su capacidad de adsorción. Con este propósito, se determinan las isotermas de adsorción de nitrógeno a 77 K y se calculan las áreas específicas aplicando el procedimiento de BET. Se encuentra que la activación de estos residuos con O₂ o CO₂ resulta adecuada para obtener carbones activados de áreas específicas moderadas. Los carbones activados obtenidos utilizando CO₂ presentan una mayor capacidad de adsorción, pero su preparación con este agente activante involucra temperaturas considerablemente superiores.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Extravascular hemolysis and complement consumption in Paroxysmal Nocturnal Hemoglobinuria patients undergoing eculizumab treatment

Los datos asociados con este artículo están disponibles en: http://dx.doi.org/10.1016/j.imbio.2016.09.002.Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia characterized by complement-mediated intravascular hemolysis that is effectively treated with eculizumab. However, treatment responses are reported heterogeneous with some patients presenting residual hemolysis and requiring RBC transfusions. Recent reports have shown that both extravascular hemolysis and incomplete C5 blockade can explain these suboptimal hematological responses. Here we have tested our eculizumab-treated PNH patients (n = 12) for signs of hemolysis and assessed complement biomarkers. Patients were also genotyped for complement receptor 1 (CR1, CD35) and C5 polymorphisms and evaluated for free eculizumab in plasma. We report that 10 patients (83%) present parameters suggesting persistent hemolysis, although they did not require additional transfusions. Seven of them (58%) become direct Coombs-test positive as a consequence of treatment, including all patients carrying the low-expression CR1-L allele. CH50 and sC5b-9 assays demonstrate that the persistent low-level hemolysis identified in our treated patients is not a consequence of incomplete C5 blockade, supporting that this hemolysis, as has been suggested previously, results from the extravascular removal of C3 opsonized PNH erythrocytes. We also show that continuous alternative pathway activation in eculizumab-treated individuals carrying the CR1-L allele results in abnormally decreased levels of C3 in plasma that could, potentially, increase their susceptibility to bacterial infections. Finally, we encourage a routine evaluation of free eculizumab levels and terminal pathway activity to personalize eculizumab administrationIn this study S.R de C. is supported by the Spanish “Ministerio de Economía y Competitividad” (SAF2011-26583) and the Autonomous Region of Madrid (S2010/BMD-2316

Tipos de tiempo y calidad del aire en tres estaciones de fondo del NW peninsular

Ponencia presentada en: XXXV Jornadas Científicas de la AME y el XIX Encuentro Hispano Luso de Meteorología celebrado en León, del 5 al 7 de marzo de 2018.La contaminación atmosférica se ha incrementado principalmente por el desarrollo de actividades industriales y económicas. Además, hay que tener en cuenta no sólo la contaminación atmosférica generada cerca de las fuentes, sino también la que se ha transportado hacia zonas alejadas, conocidas como regiones de fondo. En este trabajo se estudia la evolución de las concentraciones de los contaminantes atmosféricos en tres estaciones de fondo de la Península Ibérica y se buscan las posibles relaciones entre la concentración de contaminantes atmosféricos y las condiciones meteorológicas en dichas estaciones.Este trabajo ha sido parcialmente financiado por el Ministerio de Economía y Competitividad (TEC2014-57821-R), la Universidad de León (Programa Propio 2015/00054/001) y el proyecto AERORAIN (Ministerio de Economía y Competitividad, CGL2014-52556-R, cofinanciado con fondos FEDER)