On forward and reverse coupling of vibrating piezoelectric energy harvesters

This document provides information about the analysis of effects coupling the mechanical and the electrical phenomena going on inside a piezoelectric energy har- vester. Two characteristics are exploited in energy harvesting: direct piezoelectric effect where stress is resulting by the application of an electric field and reverse effect showing an electric field resulting by stress application. Piezoelectric patches, bonded on beams free to vibrate under a mechanical stimulus, can be used as active elements. Point-wise material characteristics are described by symmetric matrices coupling together stress and electric field to the strain and the electric polarisation leading to reciprocal direct and reverse effects. Under operating conditions, the stress and electric field values applied to the material patch are not uniform and do not have the same spatial pattern resulting in a non reciprocal interaction. An explanation of this phenomenon is attempted by applying the Euler-Bernoulli beam theory model that allows the computation of two geometrical coefficients for direct and inverse interactions under uniform stress distribution. Com- parisons versus experiments carried out on a Macro Fiber Composite piezoelectric patch show that the model is able to estimate the effect

Aerodynamic Characterization of a Wells Turbine Under Bi-Directional Airflow

Abstract This work deals with the experimental study of the flow in a Wells turbine submitted to an unsteady and bi-directional airflow. The investigations were carried out on an experimental set-up that can simulate the real operating conditions of a wave energy conversion device using a two-dimensional hot-wire anemometer probe to analyse the flow field upstream and downstream of the turbine during its non-stationary operation. In addition to local measurements, the position of the piston that simulates the wave motion, the driving torque and the turbine rotational speed were also measured. These surveys allowed determination of the turbine instantaneous performances by analysing the aerodynamic flow characteristic at mid-span in the blade-to-blade plane downstream of the rotor. The flow distribution was obtained for the phase of inflow and outflow at different values of rotational speed which was kept constant during data acquisition. The results showed asymmetric behaviour for the two phases of intake and exhaust stroke of the piston and during acceleration and deceleration of the flow. The real entity of the hysteresis phenomenon that arose during the phases of acceleration and deceleration of the unsteady flow was evaluated considering velocity distribution in close proximity of the rotor

On the comparison of oxygen and sulfur transfer reactivities in phosphine and phosphorene: the case of R3Sb(X) carriers (X = O or S).

A mediated approach for an efficient metal covalent functionalization of the phosphorene surface is presented through the selective insertion of chalcogen atoms. Electronic and steric requirements have been evaluated in details

Modelling Strategies for the Covalent Functionalization of 2D Phosphorene

The paper is an excursus on potential acid-base adducts formed by an unsaturated main group or transition metal species and P atoms of phosphorene (P n ), which derives from the black phosphorus exfoliation. Various possibilities of attaining a realistic covalent functionalization of the 2D material have been examined via DFT solid state calculations. The distribution of neighbor P atoms at one side of the sheet and the reciprocal directionalities of their lone pairs must be clearly understood to foreshadow the best possible acceptor reactants. Amongst the latter, the main group BH 3 or I 2 species have been examined for their intrinsic acidity, which favors the periodic mono-hapto anchoring at P n atoms. The corresponding adducts are systematically compared with other molecular P donors from a phosphine to white phosphorus, P 4 . Significant variations emerge from the comparison of the band gaps in the adducts and the naked phosphorene with a possible electronic interpretation being offered. Then, the P n covalent functionalization has been analyzed in relation to unsaturated metal fragments, which, by carrying one, two or three vacant hybrids, may interact with a different number of adjacent P atoms. For the modelling, the concept of isolobal analogy is important for predicting the possible sets of external coligands at the metal, which may allow the anchoring at phosphorene with a variety of hapticities. Structural, electronic, spectroscopic and energy parameters underline the most relevant pros and cons of some new products at the 2D framework, which have never been experimentally characterized but appear to be reasonably stable

A Perspective on Recent Advances in Phosphorene Functionalization and its Application in Devices

Phosphorene, the 2D material derived from black phosphorus, has recently attracted a lot of interest for its properties, suitable for applications in material science. In particular, the physical features and the prominent chemical reactivity on its surface render this nanolayered substrate particularly promising for electrical and optoelectronic applications. In addition, being a new potential ligand for metals, it opens the way for a new role of the inorganic chemistry in the 2D world, with special reference to the field of catalysis. The aim of this review is to summarize the state of the art in this subject and to present our most recent results in preparation, functionalization and use of phosphorene and its decorated derivatives. In particular, we discuss several key points, which are currently under investigation: the synthesis, the characterization by theoretical calculations, the high pressure behaviour of black phosphorus, as well as decoration with nanoparticles and encapsulation in polymers. Finally, device fabrication and electrical transport measurements are overviewed on the basis of recent literature and new results collected in our laboratories

The regulation of monoamine oxidase: a gene expression by distinct variable number tandem repeats

The monoamine oxidase A (MAOA) uVNTR (upstream variable number tandem repeat) is one of the most often cited examples of a gene by environment interaction (GxE) in relation to behavioral traits. However, MAOA possesses a second VNTR, 500 bp upstream of the uVNTR, which is termed d- or distal VNTR. Furthermore, genomic analysis indicates that there are a minimum of two transcriptional start sites (TSSs) for MAOA, one of which encompasses the uVNTR within the 5′ untranslated region of one of the isoforms. Through expression analysis in semi-haploid HAP1 cell lines genetically engineered in order to knockout (KO) either the uVNTR, dVNTR, or both VNTRs, we assessed the effect of the two MAOA VNTRs, either alone or in combination, on gene expression directed from the different TSSs. Complementing our functional analysis, we determined the haplotype variation of these VNTRs in the general population. The expression of the two MAOA isoforms was differentially modulated by the two VNTRs located in the promoter region. The most extensively studied uVNTR, previously considered a positive regulator of the MAOA gene, did not modulate the expression of what it is considered the canonical isoform, while we found that the dVNTR positively regulated this isoform in our model. In contrast, both the uVNTR and the dVNTR were found to act as negative regulators of the second less abundant MAOA isoform. The haplotype analysis for these two VNTRs demonstrated a bias against the presence of one of the potential variants. The uVNTR and dVNTR differentially affect expression of distinct MAOA isoforms, and thus, their combined profiling offers new insights into gene-regulation, GxE interaction, and ultimately MAOA-driven behavior

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson