Corrosion of Steel in Concrete Seen through Neutron and X-Ray Tomography

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Experimental study of inelastic deformation at the micro scale in cemented granular materials: some recent results

A novel thermomechanical constitutive model for cemented granular materials has been recently introduced. An essential ingredient of the model is the use of measurable and micro-mechanics based internal variables describing the evolution of dominant inelastic processes. In this paper, discuss about the model ability to reproduce material behaviour at specimens scale starting from a few physically meaningful parameters. These parameters link the macroscopic mechanical behaviour to the statistically averaged evolution of the micro structure. However, to fully justify this statement and given the bottom-up hierarchy in the model development, it is also important to check the model’s capability to capture the statistically averaged evolution of the micro structure embedded at its base. For that purpose we have used high resolution x-ray tomography to scan artificially cemented granular materials under a variety of loading conditions. X-Ray Tomography has been chosen for its capability to track inelastic processes in granular materials non destructively with a high spatial resolution (a few microns, in this study). The main objective of this work is to introduce the key features of the constitutive model and to report some recent results on the experimental quantification of the evolution of the microscopic internal variables in cemented granular materials

Fast vapour migration next to a depressurizing interface: A possible driving mechanism of explosive spalling revealed by neutron imaging

When exposed to high temperatures, concrete is prone to explosive spalling, resulting in the projection of concrete flakes and the reduction of the structural element cross-section. Elastic energy alone cannot justify the explosive nature of the process: accumulated thermal energy serves as a supplementary source, together with the water in the pores, which can generate kinetic energy through vaporization. The objective of this paper is to study the fast thermal and hygral transients occurring upon depressurization of an internal interface, emulating a crack developing in hot moist concrete. One possible mechanism that could justify this contribution is the flash vaporization of water. This paper presents a new experimental approach to directly measure flash vaporization through rapid-neutron imaging. Additionally, a thermo-hygral model assesses key parameters influencing fasttransient phenomena. Experimental observations reveal moisture loss in a 1-mm-thick layer, equating to a 90 degrees C temperature drop, justifying a significant amount of released energy

Unilaterale ulzerationen der fingerspitzen [Unilateral finger tip ulcerations]

none5Eine 56-jährige Frau stellte sich vor mit seit 4 Monaten bestehenden chronisch-rezidivierenden bullösen nekrotischen Läsionen an den Endgliedern des Zeige- und Mittelfi ngers der linken Hand. An denselben Fingern litt sie unter Taubheitsgefühl, Lähmung, nachts verstärktem Schmerz sowie Verlust des Feingefühls. Die Behandlung mit topischen Antibiotika und Kortikosteroiden sowie systemischem Ibuprofen und Prednison führte nicht zur Besserung. Die Patientin hatte keine weiteren Erkrankungen, war Nichtraucherin und verneinte eine Verletzung bei der Arbeit oder im Haushalt [Carpal tunnel syndrome (CTS) is caused by the compression of the median nerve throughout the carpal tunnel. CTS usually presents with the classic triad of nocturnal pain, thenar atrophy and hypoesthesia [1], but other common neurologic symptoms include numbness, unrelenting pins and needles paresthesia, loss of sensitivity and motor defi cits [2]. Moreover, CTS may show cutaneous involvement of the distal phalanges of the second and third fi ngers of the hand [1], as in our patient, who had no thenar atrophy. There are few reports that describe this cutaneous variant [2]]openSavoia F.; Tengattini V.; Valenti L.; Gaddoni G.; Patrizi A.Savoia F.; Tengattini V.; Valenti L.; Gaddoni G.; Patrizi A

A two-stage study of steel corrosion and internal cracking revealed by multimodal tomography

Modeling of corrosion-induced cracking is limited by lacking knowledge on the behavior of corrosion products. In this work, the corrosion and cracking processes were experimentally investigated in 3D at two different stages. The processes were measured at micro-structural scale, applying nondestructive neutron and X-ray computed tomography in two scans at different stages in the corrosion process. A method to evaluate the average volumetric strain of the compressed corrosion layer was proposed and displacements in the concrete matrix were measured. Strain localization revealed cracks not directly visible in the images. Multimodal tomography demonstrated to be an effective method for investigating steel corrosion in reinforced concrete

A suspicious dark lesion in a boy.

The presence of history of hyperpigmented crust in a patient with a history of adequate hygiene is typical of terra firma\u2010forme dermatosis. The treatment is the rubbing of the skin with isopropyl alcohol (removal of the hyperpigmented brown crust, confirming the diagnosis). Physicians should be aware because early diagnosis avoid unnecessary treatment

Creation and characterization of He-related color centers in diamond

Diamond is a promising material for the development of emerging applications in quantum optics, quantum information and quantum sensing. The fabrication and characterization of novel luminescent defects with suitable opto-physical properties is therefore of primary importance for further advances in these research fields. In this work we report on the investigation in the formation of photoluminescent (PL) defects upon MeV He implantation in diamond. Such color centers, previously reported only in electroluminescence and cathodoluminescence regime, exhibited two sharp emission lines at 536.5 nm and 560.5 nm, without significant phonon sidebands. A strong correlation between the PL intensities of the above-mentioned emission lines and the He implantation fluence was found in the 10^15-10^17 cm^{-2} fluence range. The PL emission features were not detected in control samples, i.e. samples that were either unirradiated or irradiated with different ion species (H, C). Moreover, the PL emission lines disappeared in samples that were He-implanted above the graphitization threshold. Therefore, the PL features are attributed to optically active defects in the diamond matrix associated with He impurities. The intensity of the 536.5 nm and 560.5 nm emission lines was investigated as a function of the annealing temperature of the diamond substrate. The emission was observed upon annealing at temperatures higher than 500{\deg}C, at the expenses of the concurrently decreasing neutral-vacancy-related GR1 emission intensity. Therefore, our findings indicate that the luminescence originates from the formation of a stable lattice defect. Finally, the emission was investigated under different laser excitations wavelengths (i.e. 532 nm and 405 nm) with the purpose of gaining a preliminary insight about the position of the related levels in the energy gap of diamond

Red wine polyphenols prevent cyclosporine-induced nephrotoxicity at the level of the intrinsic apoptotic pathway

Flavonoids, polyphenol derivatives of plant origin, possess a broad range of pharmacological properties. A number of studies have found both pro/anti-apoptotic effects for many of these compounds. For these reasons we investigated whether Provinols flavonoids obtained from red wine, have anti-apoptotic properties. The investigations have been carried out in rats treated with Cyclosporine A (CsA). In particular, four groups of rats have been treated for 21 days with either olive oil (control group), with CsA, with Provinols, or with CsA and Provinols simultaneously. Oxidative stress, systolic blood pressure, body weight, biochemical parameters and different markers of pro/anti-apoptotic pathway were measured. CsA produced an increase of systolic blood pressure, a decrease in body weight, serum creatinine levels, urinary total protein concentration and creatinine clearance. Moreover, CsA induced renal alterations and the translocation of Bax and cytochrome c from cytoplasm to mitochondria and vice versa. These changes activated the caspase cascade pathway, that leads to morphological and biochemical features of apoptosis. Provinols restored morphological and biochemical alterations and prevented nephrotoxicity. In conclusion, this study may augment our current understanding of the controversial pro-/anti-apoptotic properties of flavonoids and their molecular mechanisms