A systematic study of Brain Tissue microstructure: from composition to biomechanics and modelling of White Matter

This thesis aims to shed light on the biomechanical knowledge of the brain, in particular of its white matter (WM). An extensive, multidisciplinary and bottom-up research has been carried out to understand its micromechanical response focusing on three areas: Corpus Callosum, Corona Radiata and Fornix. Axons and the surrounding matrix with its accessory cells, the two main components of the tissue, have been analysed via Focused Ion Beam Scanning Electron Microscopy (FIB-SEM). Tissue volumes have been sampled, stained, embedded and imaged to finally be 3D-reconstructed, appearing as unidirectional composite materials. They have been geometrically characterised, creating a location-specific database of: cross-sectional area, diameter, ellipticity and tortuosity of the axons, together with the volume fraction of the volumes. The AFM-enabled nanoindentations investigated the mechanical response of WM. Stress-relaxation experiments have been performed on samples with axons running either parallel or perpendicular to the testing plane. The tissue showed linear viscoelasticity and slight anisotropy at the investigated level. The perpendicular samples showed a higher initial stiffness than parallel samples while the relative change in stiffness after relaxation was higher for the parallel samples than for the perpendicular ones. Finally, micromechanical modelling of the areas was performed. Location-speci c Representative Volume Elements have been created with the geometrical info obtained via FIB-SEM. Via an inverse-modelling approach, using the AFM data, material parameters of the axons and the matrix, the tissue components, have been obtained. The predicted stress-relaxation curves simulated by the finite element analysis showed good agreement with the experimental curves. The acquired knowledge of the microenvironment is fundamental for a comprehensive microscopical characterisation of the white matter. It provides important information to reduce axonal damage during neurosurgery, by predicting the local mechanical response and planning accordingly, and to improve the efficacy and therapeutic reach of Convection Enhanced Delivery, by exploiting the cytoarchitecture, leading to minimal side effects and maximal efficacy of the treatments.Open Acces

Theoretical evidence for efficient p-type doping of GaN using beryllium

Ab initio calculations predict that Be is a shallow acceptor in GaN. Its thermal ionization energy is 0.06 eV in wurtzite GaN; the level is valence resonant in the zincblende phase. Be incorporation is severely limited by the formation of Be_3N_2. We show however that co-incorporation with reactive species can enhance the solubility. H-assisted incorporation should lead to high doping levels in MOCVD growth after post-growth annealing at about 850 K. Be-O co-incorporation produces high Be and O concentrations at MBE growth temperatures.Comment: revised Feb 24 199

Railway Bridge Runability Safety Analysis in a Vessel Collision Event

Abstract: Bridges connecting islands close to the coast and crossing the sea have been attracting the attention of several researchers working in the field of train–bridge interactions. A runability analysis of a bridge during the event of a ship impact with a pier is one of the most interesting and challenging scenarios to simulate. The objective of the present paper is to study the impact on the running safety of a train crossing a sea bridge as a function of different operational factors, such as the train travelling speed, the type of impacting ship, and the impact force magnitude. Considering train–bridge interactions, a focus is also placed on wheel–rail geometrical contact profiles, considering new and worn wheel–rail profiles. This work is developed considering a representative continuous deck bridge with pier foundations located on the sea bed composed of six spans of 80 m. Time-domain simulations of trains running on the bridge during ship impact events were carried out to quantify the effect of different operating parameters on the train running safety. For this purpose, derailment and unloading coefficients, according to railway standards, were calculated from wheel–rail vertical and lateral contact forces. Maps of the safety coefficients were finally built to assess the combined effect of the impact force magnitude and train speed. The present investigation also showed that new wheel–rail contact geometrical profiles represent the most critical case compared to moderately worn wheel–rail profiles

Personalized fruition of Cultural Heritage in a City Environment

Personalized fruition of Cultural Heritage in a City Environmen

Recupero di eptano da una miscela azeotropica

In questo studio si è elaborato un procedimento per il recupero dell'eptano da un soluzione eptano-isopropanolo in un'industria farmaceutica vagliando diverse possibilitoperative e sfruttando le caratteristiche chimico-fisiche del solvente stesso, che lo rendono quasi totalmente immiscibile all'acqua. La sua tendenza a sciogliersi in una fase organica, piuttosto che in quella acquosa, ha permesso di progettare un trattamento alternativo in una colonna di distillazione che ne permettesse la separazioneope

Importancia de las modificaciones post-traduccionales en la estabilidad y tráfico de CAH1 e identificación de N-glicoproteínas en el cloroplasto de Arabidopsis thaliana

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología. Fecha de lectura: 13-06-2014Este trabajo se centra en el análisis de la N-glicosilación, una modificación post-traduccional muy común en proteínas. En concreto, se estudia el papel de la N-glicosilación en la estabilidad, tráfico y funcionalidad de proteínas cloroplásticas de Arabidopsis thaliana. Para ello, se realizan análisis en versiones mutadas de la glicoproteína usada como modelo CAH1, una carbónico anhidrasa codificada en el núcleo de la célula, que se transporta al cloroplasto a través del sistema de endomembranas, siguiendo una ruta diferente a la usada por la mayoría de proteínas importadas por éste orgánulo. En el proceso de transporte se modifica post-traduccionalmente adquiriendo N-glicanos y, potencialmente, un puente di-sulfuro. Se analiza la influencia de dichas modificaciones en el plegamiento y transporte de CAH1, así como la influencia del extremo carboxilo terminal. Por otro lado, el papel fisiológico de los N-glicanos complejos, procesados y madurados al paso de la N-glicoproteína por el aparato de Golgi no está muy claro en plantas. De hecho, mientras mutantes incapaces de generar N-glicanos complejos producen fenotipos patológicos en mamíferos, mutaciones análogas en plantas no parecían presentar un fenotipo alterado. Sin embargo, estudios recientes sugieren la existencia de una relación de las modificaciones en glicosilación que tienen lugar en el aparato de Golgi, con el desarrollo normal de la planta bajo condiciones de estrés abiótico. Para profundizar en este hallazgo, en este trabajo se han utilizado plantas carentes de ciertos residuos glucídicos en sus N-glicanos, crecidas en condiciones de estrés salino, determinando diversos parámetros fisiológicos como el crecimiento de raíces o la capacidad de sintetizar pared celular. Por último, distintos estudios indican que la ruta de transporte al cloroplasto asociada al sistema de endomembranas no es exclusiva CAH1, si no que existen otras proteínas que pueden seguir rutas similares y/o alternativas. Por ello, se planteó la identificación de otras N-glicoproteínas que tuvieran características similares a la ya mencionada CAH1. Esto implicaría no sólo la constatación de la elevada complejidad del sistema de transporte de proteínas dentro de la célula, sino la posibilidad de implementar o adaptar estas rutas de transporte a la producción de proteínas recombinantes de interés farmacéutico y/o industrial. Para ello se procedió a realizar estudios proteómicos empleando como herramienta una serie de mutantes con una ruta de transporte de moléculas al cloroplasto interrumpida. Tanto la N-glicosilación de proteínas cloroplásticas, como los sistemas que rigen el transporte de este tipo de proteínas en plantas, se encuentran aún en estadios muy tempranos de investigación, siendo necesaria una mayor profundización tanto en la caracterización de las funciones de éstos residuos de azúcares en las estructuras proteicas, como en el tipo de sistema y elementos implicados en su transporte.The aim of this work is to analyze the role of N-glycosylation of proteins, a common post-translational modification (PTM), on the stability, traffic and function of plastid proteins from Arabidopsis thaliana. With that aim, it was used as model CAH1, a nuclear encoded α carbonic anhydrase that is transported into the chloroplast via the endomembrane system, a pathway different to the canonical one used for most of the proteins targeted to this organelle. During its transport process to the organelle, CAH1 acquires N-glycans and, potentially, a disulphide bond. The role of these PTMs on folding and transport of CAH1, as well as the influence of C-terminus are analyzed. On the other hand, physiological function of complex N-glycans, those resulting from the N-glycan processing and maturation during the pass of the N-glycoprotein through the Golgi apparatus, are not very well understood in plants. In fact, whereas mutants unable to synthesize complex N-glycans produced pathological phenotypes in mammals, in plants seems to provoke no apparently altered phenotype. However, recent studies have suggested a relationship between N-glycan modifications and normal plant development under abiotic stress conditions. To further explore this finding, we have used plants defective in specific complex N-glycan residues under salt stress conditions, and determined several physiological parameters, as root growth or cell wall formation capacity. Additionally, several studies indicate that the route of chloroplast import of proteins associated to the endomembrane system is not exclusive of CAH1, and that there may be other proteins targeted to the organelle using similar or alternative pathways. Therefore, the identification of other N-glycoproteins sharing some characteristics than the mentioned CAH1 has risen. This finding not only would confirm the high complexity of the transport system of proteins within the cell, but it would allow adapting these routes for the production of recombinant proteins with pharmaceutical and/or industrial interest. For that, we designed a proteomic strategy, based on the use of mutants defective in a route of transport of molecules to the chloroplast. The knowledge of both, N-glycosylation of plastid proteins and transport process of these proteins in plant cells, are still in very preliminary stages. Further research is needed to characterize the function of N-glycan residues in plants as well as the process and the elements involved on their transport to the organell

The AGNULA/DeMuDi Distribution: GNU/linux and Free Software for the Pro Audio and Sound Research Domain

(Abstract to follow

design of a smart system for indoor climate control in historic underground built environment

Abstract The application of sensors-actuators networks in Building Heritage can lead to significant improvement in indoor climate control, with the aim to both reduce energy consumption, and improve conditions for occupants and hosted Heritage. This study proposes the preliminary design of a smart indoor climate control system, based on low-impact application criteria, which can be applied to visited underground built environment. The system is based on the balance of hygrothermal loads. Sensors and actuators requirements are defined, and control algorithm are based on the comparison between real-time monitored and "natural" temperature and hygrometric values (for stationary and transitory conditions)