Strain-Rate Sensitivity of a Pultruded E-Glass/Polyester Composite

Structural analysis of composite structures subjected to dynamic loads requires detailed knowledge of the mechanical behavior of component materials under high strain-rates. This paper presents the results of tests to investigate the tensile dynamic behavior of a pultruded E-glass/polyester composite used in a steel-less blast protection barrier. The described activity is part of the Security of Airport Structures research project, focusing on structural protection of airport infrastructures against disruptive action. Modified Hopkinson bars and hydropneumatic machine devices were used to conduct strain-rate controlled tensile failure tests on glass fiber-reinforced polymer specimens. The results are discussed and then implemented within a viscoplasticity constitutive model and a strain-rate-dependent failure criterion in order to simulate the exhibited mechanical behavior.     

Wind energy in the world: Reality and prospects

This report presents an overview of the various aspects of the use of wind energy for the production of electricity with special regard to: available resources; the state-of-the art of the technology; the worldwide wind energy applications; the present situation and foreseeable development of the world wind energy market in the next two decades; the economics of wind-generated electricity. Possible restraints to and benefits from wind plant integration in utility systems are also considered.     

Modeling Parkinson’s Disease Neuropathology and Symptoms by Intranigral Inoculation of Preformed Human α-Synuclein Oligomers

The accumulation of aggregated α-synuclein (αSyn) is a hallmark of Parkinson’s disease (PD). Current evidence indicates that small soluble αSyn oligomers (αSynOs) are the most toxic species among the forms of αSyn aggregates, and that size and topological structural properties are crucial factors for αSynOs-mediated toxicity, involving the interaction with either neurons or glial cells. We previously characterized a human αSynO (H-αSynO) with specific structural properties promoting toxicity against neuronal membranes. Here, we tested the neurotoxic potential of these H-αSynOs in vivo, in relation to the neuropathological and symptomatic features of PD. The H-αSynOs were unilaterally infused into the rat substantia nigra pars compacta (SNpc). Phosphorylated αSyn (p129-αSyn), reactive microglia, and cytokine levels were measured at progressive time points. Additionally, a phagocytosis assay in vitro was performed after microglia pre-exposure to αsynOs. Dopaminergic loss, motor, and cognitive performances were assessed. H-αSynOs triggered p129-αSyn deposition in SNpc neurons and microglia and spread to the striatum. Early and persistent neuroinflammatory responses were induced in the SNpc. In vitro, H-αSynOs inhibited the phagocytic function of microglia. H-αsynOs-infused rats displayed early mitochondrial loss and abnormalities in SNpc neurons, followed by a gradual nigrostriatal dopaminergic loss, associated with motor and cognitive impairment. The intracerebral inoculation of structurally characterized H-αSynOs provides a model of progressive PD neuropathology in rats, which will be helpful for testing neuroprotective therapies.     

First international Competition on Runtime Verification: rules,benchmarks, tools,and final results of CRV 2014

International Journal on Software Tools for Technology Transfer - The first international Competition on Runtime Verification (CRV) was held in September 2014, in Toronto, Canada, as a satellite...     

Dynamic behavior of a Mediterranean natural stone under tensile loading

Historical buildings are important structures commonly occurring in Mediterranean cities. The behavior of their constituent materials under high dynamic loads is fundamental to investigate the vulnerability of such structures under extreme dynamic events. The main aim of our investigation was to study the effect of high dynamic loading conditions on a classical porous natural stone from the Naples area, namely yellow tuff, used in hundreds of historical buildings and monuments in Naples and other Mediterranean cities. Hence, dynamic characterization was performed through high strain-rate failure tensile tests. A wide range of strain-rates was investigated, from 10^?5 s^?1 to 50 s^?1. The obtained data were processed to obtain stress–strain relationships at different strain-rate levels. The results reveal that Neapolitan yellow tuff presents a significantly strain-rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain-rate, up to about three times that from quasi-static conditions in the case of very high strain-rates. Dynamic increase factors (DIFs) vs. strain-rate curves for tensile failure stress were also evaluated and discussed.     

Aqueous atmospheric chemistry: formation of 2,4-dinitrophenol upon nitration of 2-nitrophenol and 4-nitrophenol in solution

Field studies have shown that the powerful phytotoxic agent 2,4-dinitrophenol is very likely to form in the atmospheric aqueous phase upon nitration of 2-nitrophenol or 4-nitrophenol. However, until now, the nitration pathway and the relative importance of the two mononitrophenols as sources of 2,4-dinitrophenol were not known. The present study shows that 2,4-dinitrophenol formation from mononitrophenols can take place upon photolysis and photooxidation of nitrite/nitrous acid (NO2-/HONO) and that nitrogen dioxide plays a key role in the process. A possible pathway might be the reaction between light-excited mononitrophenols (both 2- and 4-isomers) and nitrogen dioxide, in the presence of oxygen. As an alternative, nitration might involve *NO3 + *NO2. Possible sources of nitrogen dioxide in the atmospheric aqueous phase are dissolution from the gas phase and oxidation of NO2-. In the latter case, however, it is necessary that NO2- oxidation is faster than the oxidation of mononitrophenols. This would happen, for instance, in the presence of hematite under irradiation. Radiation absorption and scattering by hematite would also inhibit the direct photolysis of nitrophenols. The formation rate and the yield of 2,4-dinitrophenol are slightly higher when starting from 2-nitrophenol than those from 4-nitrophenol, but they are compensated by the higher concentration of 4-nitrophenol in the atmospheric aqueous phase.     

Fatigue and healing properties of bituminous mastics reinforced with nano-sized additives

The research work described in the paper focused on fatigue and healing properties of bituminous mastics reinforced with nano-sized additives.Commercially available multiwall carbon nanotubes (CNTs) and montmorillonite nanoclay (NC) were combined with a single base bitumen and a standard mineral filler to produce bituminous mastics. These blends were prepared in the laboratory by making use of a technique consisting in simple shear mixing followed by sonication.Fatigue behaviour of mastics under repeated loading was investigated by means of time sweeps performed in the strain-controlled mode at various amplitudes. Healing potential was assessed by adopting a testing protocol specifically conceived to discriminate between recovery of damage induced by fatigue loading and other artefact phenomena which may affect material response. All rheological measurements were carried out with a dynamic shear rheometer in the parallel plates geometry.Outcomes of the experimental investigation were found to be highly dependent on the nature of additive type, as a result of the key role played by interaction mechanisms that nano-particles can establish within the bituminous mastic.