Effect of cracks on the service life of RC structures exposed to chlorides

To move towards a more sustainable concrete, the enhancement of its durability is strongly encouraged and, dealing in particular with reinforced concrete (RC), this mainly means to prevent the damage due to environmental actions, e.g. due to chloride-induced corrosion. Therefore, there is the need of models aimed at designing durable structures. Usually the service life design models consider concrete in uncracked condition. In real structures, however, several phenomena can generate cracks on concrete surface, leading to an acceleration of the corrosion of steel rebar. A number of studies have been recently carried out in order to evaluate the influence of cracks on reinforced concrete durability in chloride-contaminated environment, however the knowledge of the effect of cracks on the initiation and propagation periods is still lacking. Furthermore, few studies have considered additional protection strategies, such as the use of stainless steel rebar. In this work, experimental results are presented concerning the influence of cracks on the service life of reinforced concrete structures in order to evaluate if cracks lead to an earlier corrosion initiation induced by chlorides. Prismatic specimens, reinforced with carbon steel and 304L stainless steel bars, were longitudinally cracked and exposed to ponding with 3.5% NaCl solution. The monitoring of corrosion behaviour showed that when cracks reached the steel surface corrosion initiated immediately

EXAFS and XANES structural characterization of bimetallic AuPd vapor derived catalysts

Using an innovative procedure known as metal vapor synthesis (MVS) to prepare bimetallic catalysts, starting from Au and Pd vapors, [AuPd] co-evaporated and [Au][Pd] separately evaporated bimetallic catalysts were achieved. After being tested, the catalytic activity and selectivity of the [AuPd] catalyst turned out to be higher than the [Au][Pd] ones. Using EXAFS spectroscopy it was shown that, in the [AuPd] samples, small bimetallic AuPd nanoparticles were present, having an Au rich core surrounded by an AuPd alloyed shell while in the [Au][Pd] sample there was the presence of monometallic Au and Pd nanoparticles showing some alloying only in the boundary regions. The EXAFS results were also qualitatively conrmed by the XANES spectra

Photocatalytic activity of ZnO nanostructures grown by vapour and solution

Zinc oxide (ZnO) is one of the most studied functional materials in the last years because it matches the opportunity to be easily synthesized in nanocrystalline form (with different morphologies and by different growth techniques) with a very large number of possible applications in different fields (optoelectronics, photovoltaics, piezoelectric devices, gas-sensing and bio-sensing, photocatalysis, spintronics, nano power generators, cantilever production, etc.). In the present contribution we report on ZnO nanocrystalline structures, with the same wurtzite structure but different morphologies, synthesized by vapour-phase and by solution growth techniques. More in detail, ZnO nanotetrapods and nanopowders with different size have been obtained by a combination of metallic Zn thermal evaporation and controlled oxidation in a non-standard CVD (chemical vapour deposition) reactor where temperature have been set in the 450?C-650?C range. Other ZnO multi-branched nanostructures, resulting from aggregation or twinning of nanosized crystals, have been grown in aqueous solution of zinc salts and hexamine, in slightly alkaline medium below 100?C. Moreover, ZnO nanopowders have been obtained by thermal decomposition of a metallorganic gel precursor, resulting from dehydration of a zinc citrate solution. Different nanopowders samples have been prepared with different decomposition processes (time, temperature). ZnO nanostructures have been later on deposited on a photocatalysis-inert substrate (glass) from an alcoholic suspension at room temperature by forcing solvent evaporation and surface cleaning for a few minutes at 200?C in low vacuum. The obtained specimens are about 50 cm2 in size. All the ZnO nanostructure films are characterized by high porosity and high surface-to-volume ratios, which are generally basic requirements for the application in photocatalysis of gaseous species. The samples have been characterised by scanning electron microscopy and tested for photocatalytic degradation activity of airborne pollutant using a stirred flow photoreactor irradiated with UV-A. The measurements were carried out using ethylbenzene as organic target pollutant at concentration level typically found in ambient conditions. The samples demonstrated a good photocatalytic activity in the degradation of ethylbenzene in air

Electrochemical synthesis of nanowires electrodes and their application in energy storage devices

In this work, an electrochemical approach to synthesize Metal-MetalOxide/Hydroxide core-shell nanowires electrodes (NWE) is illustrated. NWE electrodes were obtained by electrodeposition of a targeted metal into the nanopores of nanoporous alumina templates generated by one-step anodization of aluminum. Following metal electrodeposition, the alumina template was selectively etched to obtain an array of free-standing metal nanowires. The imposed electrodeposition conditions allowed directly attaining a core-shell nanostructure, with a metal core covered by a thin metal oxide/hydroxide film. NWE electrodes produced by the proposed synthesis route were tested for the application as electrodes in lithium batteries and supercapacitors. To this purpose, an array of cobalt nanowires (CoNWs) supported by a nanostructured copper current collector was produced by sequential electrodeposition of cobalt and copper, and it was employed as anode in a lithium battery, while a NWE based on Ni-NiO/OH2 (NiNWs) was obtained by nickel electrodeposition and tested as electrode in a supercapacitor. A thorough analysis and characterization of the produced electrodes were performed. The experiments with the lithium cell evidenced the positive effect of metallic core on stability, while the electrochemical characterization of the supercapacitor showed the presence of both NiO and NiOH2 leading, when cycled, to a capacity close to the best literature value

Photocatalytic activity of nanotubular TiO2films obtained by anodic oxidation: A comparison in gas and liquid phase

The availability of immobilized nanostructured photocatalysts is of great importance in the purification of both polluted air and liquids (e.g., industrial wastewaters). Metal-supported titanium dioxide films with nanotubular morphology and good photocatalytic efficiency in both environments can be produced by anodic oxidation, which avoids release of nanoscale materials in the environment. Here we evaluate the effect of different anodizing procedures on the photocatalytic activity of TiO2nanostructures in gas and liquid phases, in order to identify the most efficient and robust technique for the production of TiO2layers with different morphologies and high photocatalytic activity in both phases. Rhodamine B and toluene were used as model pollutants in the two media, respectively. It was found that the role of the anodizing electrolyte is particularly crucial, as it provides substantial differences in the oxide specific surface area: nanotubular structures show remarkably different activities, especially in gas phase degradation reactions, and within nanotubular structures, those produced by organic electrolytes lead to better photocatalytic activity in both conditions tested

Do methadone and buprenorphine have the same impact on psychopathological symptoms of heroin addicts?

<p>Abstract</p> <p>Background</p> <p>The idea that the impact of opioid agonist treatment is influenced by the psychopathological profile of heroin addicts has not yet been investigated, and is based on the concept of a specific therapeutic action displayed by opioid agents on psychopathological symptoms. In the present report we compared the effects of buprenorphine and methadone on the psychopathological symptoms of 213 patients (106 on buprenorphine and 107 on methadone) in a follow-up study lasting 12 months.</p> <p>Methods</p> <p>Drug addiction history was collected by means of the Drug Addiction History Rating Scale (DAH-RS) and psychopathological features were collected by means of the Symptom Checklist-90 (SCL-90), using a special five-factor solution. Toxicological urinalyses were carried out for each patient during the treatment period.</p> <p>Results</p> <p>No statistically significant differences were detected in psychopathological symptoms, including 'worthlessness-being trapped', 'somatization', and 'panic-anxiety'. Methadone proved to be more effective on patients characterized by 'sensitivity-psychoticism', whereas buprenorphine was more effective on patients displaying a 'violence-suicide' symptomatology.</p> <p>Conclusions</p> <p>Heroin-dependent patients with psychiatric comorbidities may benefit from opioid agonist treatment not only because it targets their addictive problem, but also, precisely due to this, because it is effective against their mental disorder too.</p

Sex differences and rehabilitation needs after hospital discharge for COVID-19: an Italian cross-sectional study

COVID-19 can result in persistent symptoms leaving potential rehabilitation needs unmet. This study aims to describe persistent symptoms and health status of individuals hospitalised for COVID-19 according to the International Classification of Functioning, Disability and Health domains of impairments, limitations in activity, and participation restrictions

Standard Model updates and new physics analysis with the Unitarity Triangle fit

We present here the update of the Unitarity Triangle (UT) analysis performed by the UTfit Collaboration within the Standard Model (SM) and beyond. Continuously updated flavour results contribute to improving the precision of several constraints and through the global fit of the CKM parameters and the SM predictions. We also extend the UT analysis to investigate new physics (NP) effects on $\Delta F=2$ processes. Finally, based on the NP constraints, we derive upper bounds on the coefficients of the most general $\Delta F=2$ effective Hamiltonian. These upper bounds can be translated into lower bounds on the scale of NP that contributes to these low-energy effective interactions.Comment: Proceedings of the 8th International Workshop on the CKM Unitarity Triangle (CKM 2014), Vienna, Austria, September 8-12, 201

Study of shock waves generation, hot electron production and role of parametric instabilities in an intensity regime relevant for the shock ignition

We present experimental results at intensities relevant to Shock Ignition obtained at the sub-ns Prague Asterix Laser System in 2012 . We studied shock waves produced by laser-matter interaction in presence of a pre-plasma. We used a first beam at 1ω (1315 nm) at 7 × 10 13 W/cm 2 to create a pre-plasma on the front side of the target and a second at 3ω (438 nm) at ∼ 10 16 W/cm 2 to create the shock wave. Multilayer targets composed of 25 (or 40 μm) of plastic (doped with Cl), 5 μm of Cu (for Kα diagnostics) and 20 μm of Al for shock measurement were used. We used X-ray spectroscopy of Cl to evaluate the plasma temperature, Kα imaging and spectroscopy to evaluate spatial and spectral properties of the fast electrons and a streak camera for shock breakout measurements. Parametric instabilities (Stimulated Raman Scattering, Stimulated Brillouin Scattering and Two Plasmon Decay) were studied by collecting the back scattered light and analysing its spectrum. Back scattered energy was measured with calorimeters. To evaluate the maximum pressure reached in our experiment we performed hydro simulations with CHIC and DUED codes. The maximum shock pressure generated in our experiment at the front side of the target during laser-interaction is 90 Mbar. The conversion efficiency into hot electrons was estimated to be of the order of ∼ 0.1% and their mean energy in the order ∼50 keV. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributio