Crystal Structure and Local Dynamics in Tetrahedral Proton-Conducting La1-xBa1+xGaO4

La1-xBa1+xGaO4-0 (LBG) compounds, based on unconnected GaO4 moieties, were recently proposed as proton conductors. Protonic defects in the lattice are inserted through self-doping with Ba2+, to create oxygen vacancies subsequently filled by hydroxyl ions. We present a combined structural analysis on self-doped LBG using X-ray diffraction (XRD) and X-ray absorption (EXAFS): these results unravel the finer structural details on the short-range and long-range scales, and they are correlated with the dynamical properties of protonic conduction coming from vibrational spectroscopy. The structure of the GaO4 groups is independent of the oxide composition. On hydration, an array of short intertetrahedral hydrogen bonds is formed, producing a contraction of the a axis. On the basis of thermogravimetric analysis, EXAFS, XRD and infrared spectroscopy (IR) results, we propose that the stiffness of the GaO4 tetrahedra hinders the intratetrahedral proton transfer, while the noticeable fraction of protons involved in strong hydrogen bonds limit the proton reorientational freedom

Indium doping of proton-conducting solid oxides

Solid oxides protonic conductors are prepared by doping the pure matrix compounds with cationic species. Barium cerate and barium zirconate are perovskite-like compounds, characterized by a network of corner-sharing MeO6 octahedra (Me=Ce, Zr). Barium lies in the cavities between octahedra. Insertion of trivalent species in the octahedral site involves the formation of charge- compensating oxygen vacancies, that can be filled by hydroxyls coming from dissociative water absorption. Then, proton delocalization among structural oxygens ensures conductivity. The most effective conductors are obtained by yttrium doping that, on the other hand, enters only in limited amounts in both BaZrO3 and BaCeO3, thus involving limited carrier concentration. Perovskites are affected by different drawbacks: barium cerate compounds are very sensitive to the acidic components present in the environment and in particular to CO2 that induces decomposition in barium carbonate and cerium oxide; barium zirconate, notwithstanding a very high bulk conductivity, is biased by high grain boundary resistivity. A possible alternative to perovskite-like compounds is constituted by fergusonite-type lanthanum niobate and lanthanum tantalate compounds, characterized by a tetrahedral coordination of Nb and Ta. These oxides present a very high chemical stability but very low carrier concentration, usually induced by Ca-doping the lanthanum site [1]. Among the different trivalent dopants, it was demonstrated by X-ray absorption spectroscopy that indium is able to enter in any composition in the perovskite network, thus providing a very high carrier concentration, even if with lower proton mobility. This property of indium was ascribed to its electronic structure and in particular to the low Pearson hardness, allowing this cation to fit in a hosting matrix with the least structural strain [2]. A preliminar attempt of exploiting indium for enhancing the carrier concentration of lanthanum niobate was carried out. The solid state synthesis involved amounts of the reactant simple oxides suitable to force indium doping of the niobium site. X-ray diffraction do not show significant amounts of secondary oxide phases

Multibody parameter estimation: A comprehensive case-study for an innovative rear suspension

Numerical and virtual simulation of mechanical systems is a standard part of product development in the automotive sector, and multibody techniques are a consolidated tool to describe vehicle dynamics, elasto- kinematic behavior, handling, and comfort. To achieve high precision results as output of simulations, it is essential to provide the system with reliable data as input, and to accurately describe the vehicle and its subsystems. The task of gathering objective parameters to fully describe a vehicle can seem trivial to the stakeholders directly connected to a project, that can access detailed design data and a plethora of schemes and datasheets covering all subsystems of a vehicle. However, whenever this task regards benchmarking, prototyping, research projects or niche/low-volume products, data availability decreases drastically, and alternative forms of data acquisition become essential. This paper proposes a comprehensive overview of data gathering and experimental procedures used to reliably extract parameters of an existing vehicle using quick and accessible strategies. The analysis is based on a case-study project of an A-segment vehicle mounted with an innovative rear suspension scheme, whose behavior should be described by a dedicated elasto- kinematic multibody model as well as a full vehicle model for dynamic validation. The multibody model is based on Adams/Car with the inclusion of flexible elements, which is briefly described, while a closer focus is given to the experimental extraction of key features, such as: total mass, longitudinal and lateral position of the center of gravity, CoG height, wheel travel and wheel rate, shock-absorber damping coefficient, steering ratio, components inertia and flexible elements strain. The results obtained in the static and dynamic experimental validation suggest a good outcome from the methodology, that can be replicated on many kinds of vehicle modelling activities as an approachable and affordable experimental methodology for small projects

Composite Control Arm Design: A Comprehensive Workflow

This paper presents a complete overview of the computational design of an advanced suspension control arm constructed of composite material for light weighting purposes. The proposed methodology presented in detail is split into 3 phases. Phase 1 or Vehicle Performance Simulation, in which basic modelling and a sensibility study is performed to better understand the advantages of unsprung mass reduction (compared to sprung mass reduction) with respect to the vehicle's vertical dynamics. It followed by the development and utilization of a multibody approach to evaluate the full-vehicle response to different dynamic maneuvers, such as harsh road imperfections, sine sweep steering, and double lane change tests. The impact of the improved suspension control arm is highlighted in detail, and the loads to which it is subjected are computed to serve as inputs for the successive phases. Phase 2 or Design and Calculation Phase, where a closer look is given to the structural side of the component, understanding the specific behavior of composite materials and performing modelling of the control arm, followed by fine tuning with Finite Element Method optimization techniques. This phase consists of a topology optimization, followed by composite topography free size, size, and shuffle optimizations to arrive upon the ideal part-layup, and guarantee the desired mechanical characteristics of the component. Lastly, Phase 3 or the Production Preparation closes the design process by generating the production processes, steps, constraints, and tooling for the correct realization of the innovative control arm in a real-world application. The tools presented in this paper were created to allow the design to be completed rapidly, thus defining a blueprint for a full workflow, from engineering request to product delivery, which can be applied to different vehicles and customer requests, representing an essential step forward to the consolidation of the use of composite materials for structural suspension components

Validation of a numerical-experimental methodology for structural health monitoring on automotive components

In the recent years, the materials composing the traditional of aircrafts are being progressively replaced with lower density materials, as the Reinforced Plastics. The same trend has been highlighted in the Automotive field to assess the reduction of fuel consumption and CO2 emission. In order to achieve an optimization of maintenance a variety of on-board systems has been applied for on-line SHM based on piezoelectric transducers earned a particularly high interest for continuous monitoring on metallic and composite structures. The application of this system in automotive could enhance passenger safety, through the monitoring of the vehicle composite material structure health status. In this paper, six mathematical models for evaluating the electrical response of piezoelectric sensors have been implemented, with the aim of selecting the most effective model for damage identification. Experimental tests were carried out on three types of simpler specimens of different geometries made of different materials (steel, aluminum and carbon fiber). A correlation study has been carried on in order to support the positioning of sensors. The proposed numerical-experimental methodology is an essential foundation for the introduction of monitoring systems based on piezoelectric transducers in the Automotive sector

Low glycemic index diet in children and young adults with refractory epilepsy: first Italian experience.

This is the report on the first Italian experience with the low glycemic index diet (LGIT) in a group of children, adolescents and young adults with refractory epileptic encephalopathies. A retrospective chart review was performed on patients initiating the LGIT in an outpatient setting from 2005 to 2010. Demographic and clinical information including seizure type, baseline seizure frequency, medications, blood chemistry, side effects, and anthropometrics were collected. Patients were educated and followed by a dietician to restrict foods with high glycemic index and to limit total daily carbohydrates to 40-60g. Change in seizure frequency was assessed at each 3-month follow-up intervals in the first year and then at each 6-month intervals. Fifteen consecutive patients (13 males and 2 females, aged between 11.3 years and 22 years), almost all affected by generalized cryptogenic or symptomatic refractory epilepsy, were enrolled in the study. After a mean follow-up period of 14.5±6.5 months (median 12.0; range 1-60 months), 6 patients (40%) had a 75-90% seizure reduction, while seizures decreased by 50% in other 2 (13.3%) and were unchanged in 7 (46.7%). The diet was discontinued in 4 patients within the first 5 months. No adverse events occurred during the diet. In conclusion, this initial experience confirms that some refractory patients may improve on the LGIT, even as first dietary option

Feasibility study on piezoelectric actuated automotive morphing wing

Active aerodynamics is a promising technology to improve vehicle performance and efficiency, but so far in the automotive field the actuation methods suffer with several drawbacks that jeopardize its functioning and broad implementation. Morphing wings represent a technology already studied for aerospace applications that could help overcoming some of those issues. This paper proposes a piezoelectric transducer actuation for a composite material automotive wing and seeks to validate it through virtual models and physical tests. Experimental validation with a 3D-printed simplified wing profile confirms the feasibility of the technology and helps determining the best position for the piezo actuator. Furthermore, a FEM model is presented, where the piezo effect is simulated through a thermal analogy. An optimization of the composite stacking sequence is performed to maximize the trailing edge displacements, and its results are compared with the deflection caused by aerodynamic loads observed in the wing. The displacement of the trailing edge is in the order of tenths of a millimeter, even though further investigations are necessary to improve overall impact of the solution the preliminary results are promising

Signal transduction of mineralocorticoid and angiotensin ii receptors in the central control of sodium appetite: A narrative review

Sodium appetite is an innate behavior occurring in response to sodium depletion that induces homeostatic responses such as the secretion of the mineralocorticoid hormone aldosterone from the zona glomerulosa of the adrenal cortex and the stimulation of the peptide hormone angiotensin II (ANG II). The synergistic action of these hormones signals to the brain the sodium appetite that represents the increased palatability for salt intake. This narrative review summarizes the main data dealing with the role of mineralocorticoid and ANG II receptors in the central control of sodium appetite. Appropriate keywords and MeSH terms were identified and searched in PubMed. References to original articles and reviews were examined, selected, and discussed. Several brain areas control sodium appetite, including the nucleus of the solitary tract, which contains aldosterone‐sensitive HSD2 neurons, and the organum vasculosum lamina terminalis (OVLT) that contains ANG II‐sensitive neurons. Furthermore, sodium appetite is under the control of signaling proteins such as mitogen‐activated protein kinase (MAPK) and inositol 1,4,5‐thriphosphate (IP3). ANG II stimulates salt intake via MAPK, while combined ANG II and aldosterone action induce sodium intake via the IP3 signaling pathway. Finally, aldosterone and ANG II stimulate OVLT neurons and suppress oxytocin secretion inhibiting the neuronal activity of the paraventricular nucleus, thus disinhibiting the OVLT activity to aldosterone and ANG II stimulation