Development of the instrumentation of the botafoc breakwater nº 8 caisson

Balearic Port Authority has developed an instrumentation system for the #8 caisson of the Botafoc breakwater that integrates 12 pressure sensors located at three surfaces, two in contact with the sea water and another with the bottom. This design was completed with an inertial system that measures the angular velocities and the accelerations over the three Cartesian axes. Consequently, the system measures actions (pressures) and reactions (movements and accelerations) experimented by the caisson, due to sea waves and/or other service loads. R+D department of the Port Authority and Polytechnic University of Madrid are working on two directions, the development of new theories on vertical breakwater design that go beyond Goda and Sainflou, and on the creation of a real-time critical structure alarm system, based on the instrumentation installed. This alarm system has two main parts: the instrumentation itself that collects data and processes it on real-time (the data processing compares the pressure law suffered by the caisson in every step process with the design critical state of the caisson, in this case the Goda pressure law for a 6.5 m wave), giving a security coefficient that points out the risk level on real-time; and the alarm system consisting of a monitoring panel located in the Port Control Center that shows the risk level and advises in case of an incidental evacuation of this critical portuary installation

Fresnel coefficients as hyperbolic rotations

We describe the action of a plane interface between two semi-infinite media in terms of a transfer matrix. We find a remarkably simple factorization of this matrix, which enables us to express the Fresnel coefficients as a hyperbolic rotation.Comment: 6 pages, 3 figure

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

Ni-YSZ (yttria stabilized zirconia) cermets are the most widespread composite materials to be used as SOFC fuel electrodes. These materials are generally fabricated by the reduction of NiO to Ni in a NiO-YSZ composite, where the reducing conditions have a great effect in the final microstructure of the electrode. In the present work, several reducing conditions were explored in order to find the most suitable microstructure for anode-supported microtubular solid oxide fuel cells (SOFCs). Samples were firstly reduced in either pure or diluted H (dry or humidified), at temperatures ranging from 400 to 800 °C while their DC conductivity was monitored. The highest conductivity value was measured for the sample reduced in pure humidified hydrogen at 800 °C. However, this sample experienced conductivity degradation in comparison with samples reduced under dry conditions. For the studied temperature range, nucleation of nano-porous nickel particles is firstly formed during reduction. However, from our experiments it was concluded that those nanoparticles are not stable with time, at least at temperatures between 600 °C and 800 °C. Electrochemical characterization of complete microtubular cells under real wet conditions was also performed under current load, confirming that the microstructure of the Ni-YSZ cermet is still evolving during operation.Authors would like to thank the project MAT2015-68078-R, financed by the Spanish Government (Ministerio de Economía y Competitividad) and the Feder program of the European Union.Peer Reviewe

Highly stable microtubular cells for portable solid oxide fuel cell applications

In this work, extruded support tubes based on Nickel Oxide-YSZ (yttria stabilized-zirconia) were manufactured by Powder Extrusion Moulding (PEM). An YSZ layer is then deposited by dip coating as the electrolyte and subsequently, standard La0.8Sr0.2MnO3-δ (LSM)/YSZ composites were deposited by dip coating as oxygen electrodes. Microstructure of the anode support was optimized in order to achieve the maximum fuel utilization and as a consequence, a high performance of the cells. Experiments as a function of the fuel composition showed power densities above 500 mWcm−2 at 800 °C at 0.7 V, with high fuel utilization (∼75%). Long-term durability studies were also performed for a period above 1000 hours. The experiment was conducted at 800 °C using pure humidified hydrogen at a fixed voltage of 0.8 V. It was observed that the current density of the cell is significantly evolving during the initial period of about 100 hours, as a consequence of reconditioning of nickel particles at the anode support. Once the system is stabilized, no degradation was observed up to 1000 hours under operating conditions, obtaining current densities in the range of 400 mAcm−2 at 0.8 V and 800 °C.The project MAT2015-68078-R, financed by the Spanish Government (Ministerio de Economía y Competitividad) and the Feder program of the European Union, is also acknowledged.Peer Reviewe

The influence of reduction conditions on a Ni-YSZ SOFC anode microstructure and evolution

Ni-YSZ cermets are the most widespread material used as SOFC anodes. These materials are generally fabricated through the reduction of a NiO-YSZ composite, but the reduction conditions have a great effect in the final microstructure of the electrode. In the present work several conditions were explored to reduce microtubular anode supports produced via extrusion in order to find a suitable microstructure for SOFC anodes. Samples were reduced in pure and diluted H2, either dry or humidified at temperatures ranging from 400 to 800°C while their DC conductivity was being monitored. The highest value of peak conductivity was measured in the sample reduced in humidified pure hydrogen at 800°C, but it experienced more severe conductivity degradation that other samples. The best value for the duration of the test was obtained for the sample reduced in dry diluted hydrogen at 800°C.Authors would like to thank the project MAT2012-30763, financed by the Spanish Government (Ministerio de Economía y Competitividad) and the Feder program of the European Union.Peer Reviewe

Morphological changes of glia in prion and a prion-like disorder.

Several neurodegenerative diseases such as Alzheimer’s, Parkinson’s and Huntington’s are considered to be prion-like disorders in that they are all proteinopathies where in aberrant proteins spread throughout the brain during disease progression, and thus they may share molecular basis and mechanisms of propagation. Therefore, studies elucidating mechanisms of prion propagation may be relevant to other neurodegenerative diseases. While substantial progress has been made, the pathogen- esis of these neurodegenerative diseases is still largely unknown, and as consequence, to date no truly effective treatments that prevent onset or delay progression of these diseases have been identified. In addition to propagation of misfolded proteins, these diseases all induce a host response that includes activation of astrocytes and microglial cells. However, in our opinion, the glial response in each of these diseases has not been well-defined. Since a role for glial response in prion disease has been clearly demonstrated in a previous study concerning Scrapie in sheep, a similar approach to analysis of astrocytic gliosis has been taken here for Creutzfeldt-Jakob (CJD) and Alzheimer’s Diseases (AD). Here, morphological analysis of glial cells in cerebella from CJD and AD patients (as the most common prion and prion-like disorders, respectively) was performed. The results presented in this study support the involvement of glial cells not only in the pathogenesis of CJD, but also of AD. A relationship between intensity and morphology is observed in astroglia from the molecular layer in both pathologies. By contrast, the involvement of microgliosis in AD-affected samples showed a lower relevance from that observed in CJD, since reactive microglia were much more abundant in prion disease. Further analysis of the role of gliosis in CJD and AD, as well as other neurodegenerative diseases, may well advance knowledge of the mechanisms underlying these diseases and may also provide new targets for therapeutic intervention

Morphological changes of glia in prion and a prion-like disorder

Several neurodegenerative diseases such as Alzheimer’s, Parkinson’s and Huntington’s are considered to be prion-like disorders in that they are all proteinopathies where in aberrant proteins spread throughout the brain during disease progression, and thus they may share molecular basis and mechanisms of propagation. Therefore, studies elucidating mechanisms of prion propagation may be relevant to other neurodegenerative diseases. While substantial progress has been made, the pathogenesis of these neurodegenerative diseases is still largely unknown, and as consequence, to date no truly effective treatments that prevent onset or delay progression of these diseases have been identified. In addition to propagation of misfolded proteins, these diseases all induce a host response that includes activation of astrocytes and microglial cells. However, in our opinion, the glial response in each of these diseases has not been well-defined. Since a role for glial response in prion disease has been clearly demonstrated in a previous study concerning Scrapie in sheep, a similar approach to analysis of astrocytic gliosis has been taken here for Creutzfeldt-Jakob (CJD) and Alzheimer’s Diseases (AD). Here, morphological analysis of glial cells in cerebella from CJD and AD patients (as the most common prion and prion-like disorders, respectively) was performed. The results presented in this study support the involvement of glial cells not only in the pathogenesis of CJD, but also of AD. A relationship between intensity and morphology is observed in astroglia from the molecular layer in both pathologies. By contrast, the involvement of microgliosis in AD-affected samples showed a lower relevance from that observed in CJD, since reactive microglia were much more abundant in prion disease. Further analysis of the role of gliosis in CJD and AD, as well as other neurodegenerative diseases, may well advance knowledge of the mechanisms underlying these diseases and may also provide new targets for therapeutic intervention

Constructing Fresnel reflection coefficients by ruler and compass

A simple and intuitive geometical method to analyze Fresnel formulas is presented. It applies to transparent media and is valid for perpendicular and parallel polarizations. The approach gives a graphical characterization particularly simple of the critical and Brewster angles. It also provides an interpretation of the relation between the reflection coefficients for both basic polarizations as a symmetry in the plane

Iwasawa Effects in Multi-layer Optics

There are many two-by-two matrices in layer optics. It is shown that they can be formulated in terms of a three-parameter group whose algebraic property is the same as the group of Lorentz transformations in a space with two space-like and one time-like dimensions, or the $Sp(2)$ group which is a standard theoretical tool in optics. Among the interesting mathematical properties of this group, the Iwasawa decomposition drastically simplifies the matrix algebra under certain conditions, and leads to a concise expression for the S-matrix for transmitted and reflected rays. It is shown that the Iwasawa effect can be observed in multi-layer optics, and a sample calculation of the S-matrix is given.Comment: RevTex 10 pages including 1 psfi