Non-destructive testing on aramid fibres for the long-term assessment of interventions on heritage structures

High strength fibre reinforced polymers (FRPs) are composite materials made of fibres such as carbon, aramid and/or glass, and a resin matrix. FRPs are commonly used for structural repair and strengthening interventions and exhibit high potential for applications to existing constructions, including heritage buildings. In regard to aramid fibres, uncertainties about the long-term behaviour of these materials have often made the designers reluctant to use them in structural engineering. The present study describes simple and non-destructive nonlinearity tests for assessing damage or degradation of structural properties in Kevlar fibres. This was obtained by using high precision measurements to detect small deviations in the dynamic response measured on fibres and ropes. The change in dynamic properties was then related to a damage produced by exposure of the sample to UV rays for a defined time period, which simulated long-term sun exposure. In order to investigate the sensitivity of such an approach to damage detection, non-linearity characterisation tests were conducted on aramid fibres in both damaged and undamaged states. With the purpose of carrying out dynamic tests on small fibre specimens, a dedicated instrumentation was designed and built in cooperation with the Metrology Laboratory of the Department of Electronics at the Politecnico di Torino

Mitochondrial calcium uptake and release mechanisms as key regulators of cell life or death

Mitochondria are cellular organelles that play a key role in several physiological processes, including cell proliferation, differentiation, cell death and the regulation of cellular calcium (Ca2+) homeostasis. Increases in mitochondrial Ca2+ activate several dehydrogenases and carriers, inducing enhance in the respiratory rate, H+ extrusion, and ATP production necessary for the correct energy state of the cell. The mitochondrial Ca2+ uptake and release mechanisms are based on the utilization of gated channels for Ca2+ uptake and exchangers for release that are dependent upon the negative mitochondrial membrane potential, which represents the driving force for Ca2+ accumulation in the mitochondrial matrix. In this thesis, the attention was focused on two mechanisms in particular, the mitochondrial Ca2+ influx system by the activity of Mitochondrial Calcium Uniporter (MCU) complex, and the high-conductance channel mitochondrial Permeability Transition Pore (mPTP), responsible for a state of non-selective permeability of the inner mitochondrial membrane (IMM); its opening in non-physiological conditions leads to Ca2+ release from mitochondria and triggers cell death mechanisms. Thus the maintenance of the mitochondrial Ca2+ homeostasis is essential for a proper balance between cell life or death. In particular it will be discussed the possible involvement of MCU in the cell cycle, as the Ca2+ accumulation by MCU is important for the regulation of cell life and energy production. It will be shown that MCU is mainly expressed in specific phases of the cell cycle and this expression positive correlates with the mitochondrial membrane potential. MCU overexpression instead does not alter cell cycle phases. It will also described the role of the c subunit of Fo ATP synthase in mitochondrial permeability transition (MPT) and it will be demonstrated to be a critical component of the mPTP complex. Finally it will be discussed the role of mPTP in mitochondrial Ca2+ efflux and it will be shown that it is a dispensable element for mitochondrial Ca2+ efflux in non-pathological conditions

Mitochondrial calcium uptake and release mechanisms as key regulators of cell life or death

Mitochondria are cellular organelles that play a key role in several physiological processes, including cell proliferation, differentiation, cell death and the regulation of cellular calcium (Ca2+) homeostasis. Increases in mitochondrial Ca2+ activate several dehydrogenases and carriers, inducing enhance in the respiratory rate, H+ extrusion, and ATP production necessary for the correct energy state of the cell. The mitochondrial Ca2+ uptake and release mechanisms are based on the utilization of gated channels for Ca2+ uptake and exchangers for release that are dependent upon the negative mitochondrial membrane potential, which represents the driving force for Ca2+ accumulation in the mitochondrial matrix. In this thesis, the attention was focused on two mechanisms in particular, the mitochondrial Ca2+ influx system by the activity of Mitochondrial Calcium Uniporter (MCU) complex, and the high-conductance channel mitochondrial Permeability Transition Pore (mPTP), responsible for a state of non-selective permeability of the inner mitochondrial membrane (IMM); its opening in non-physiological conditions leads to Ca2+ release from mitochondria and triggers cell death mechanisms. Thus the maintenance of the mitochondrial Ca2+ homeostasis is essential for a proper balance between cell life or death. In particular it will be discussed the possible involvement of MCU in the cell cycle, as the Ca2+ accumulation by MCU is important for the regulation of cell life and energy production. It will be shown that MCU is mainly expressed in specific phases of the cell cycle and this expression positive correlates with the mitochondrial membrane potential. MCU overexpression instead does not alter cell cycle phases. It will also described the role of the c subunit of Fo ATP synthase in mitochondrial permeability transition (MPT) and it will be demonstrated to be a critical component of the mPTP complex. Finally it will be discussed the role of mPTP in mitochondrial Ca2+ efflux and it will be shown that it is a dispensable element for mitochondrial Ca2+ efflux in non-pathological conditions

The mitochondrial permeability transition pore is a dispensable element for mitochondrial calcium efflux

AbstractThe mitochondrial permeability transition pore (mPTP) has long been known to have a role in mitochondrial calcium (Ca2+) homeostasis under pathological conditions as a mediator of the mitochondrial permeability transition and the activation of the consequent cell death mechanism. However, its role in the context of mitochondrial Ca2+ homeostasis is not yet clear. Several studies that were based on PPIF inhibition or knock out suggested that mPTP is involved in the Ca2+ efflux mechanism, while other observations have revealed the opposite result.The c subunit of the mitochondrial F1/FO ATP synthase has been recently found to be a fundamental component of the mPTP. In this work, we focused on the contribution of the mPTP in the Ca2+ efflux mechanism by modulating the expression of the c subunit. We observed that forcing mPTP opening or closing did not impair mitochondrial Ca2+ efflux. Therefore, our results strongly suggest that the mPTP does not participate in mitochondrial Ca2+ homeostasis in a physiological context in HeLa cells

A new testing machine for the dynamic characterization of high strength low damping fiber materials

This work describes a novel method for measuring the damping, the elastic modulus and the non-linear behavior of high strength low damping fiber materials such as para-aramids, silicon carbide (SiC) and carbon. The method is based on resonant response characterization of a spring-mass system excited by a sine-wave forcing term which is applied as a vertical force to the suspended mass. The damping is obtained from the measured resonance quality factor Q, the elasticity modulus is calculated from the resonance frequency, and the non-linear coefficient is obtained with the backbone approach from resonance profile variations as a function of the forcing term amplitude. It is argued that the method is very sensitive, to the point that a maximum excitation amplitude of the order of a few percent of resistance is sufficient to obtain an estimate of the non-linear coefficient. This claim is supported by experimental results. A testing machine is also discussed, which provides the necessary sensitivity at such small excitation amplitudes and the capability of evaluating very small damping values, as expected in high strength low damping fiber materials. The sensitivity is guaranteed by an optical position sensor with sub-micron resolution. To evaluate small damping values, particular care has been taken to ensure that energy dispersions in the generator are much smaller than energy dispersions in the fibers themselves. Examples of dynamic characterization are shown for para-aramid, silicon carbide, and carbon fibers

ESASky v.2.0: all the skies in your browser

With the goal of simplifying the access to science data to scientists and citizens, ESA recently released ESASky (http://sky.esa.int), a new open-science easy-to-use portal with the science-ready Astronomy data from ESA and other major data providers. In this presentation, we announced version 2.0 of the application, which includes access to all science-ready images, catalogues and spectra, a feature to help planning of future JWST observations, the possibility to search for data of all (targeted and serendipitously observed) Solar System Objects in Astronomy images, a first support to mobile devices and several other smaller usability features. We also discussed the future evolution of the portal and the lessons learnt from the 1+ year of operations from the point of view of access, visualization and manipulation of big datasets (all sky maps, also called HiPS) and large catalogues (like e.g. the Gaia DR1 catalogues or the Hubble Source Catalogue) and the design and validation principles for the development of friendly GUIs for thin layer web clients aimed at scientists.Comment: 4 pages, 2 figures, ADASS 2017 conference proceeding

Risk of Cancer in Connective Tissue Diseases in Northeastern Italy over 15 Years

Objective: To evaluate cancer risk among individuals with connective tissue disease (CTD) in Friuli Venezia Giulia, northern Italy. Methods: A population-based cohort study was conducted based on data from health records available in the regional healthcare database. Demographic characteristics, hospital discharges, exemption from medical charges, drug prescriptions, were individually matched with data from the population-based cancer registry. Cancer risk was assessed in people diagnosed with the following diseases: systemic lupus erythematosus (SLE), Sjögren’s syndrome (SS), systemic sclerosis (SSc), polymyositis (PM), and dermatomyositis (DM). Results: In all, 2504 patients were followed for a total of 18,006 person-years (median follow-up: 6.8 years). After 5 and 10 years of follow-up, the cumulative cancer incidence was 2.6% and 8.5%, respectively. The most common cancers were breast (n = 34), lung (n = 24), colon–rectum–anus (n = 20), and non-Hodgkin lymphomas (NHL) (n = 20). Overall, no excess cancer risk was noted (SIR = 0.87), whereas the number of observed NHL cases was more than two-fold significantly higher than expected (SIR = 2.52). The subgroup analysis showed a higher risk of NHL among SS patients (SIR = 3.84) and SLE patients (SIR = 2.69). Conversely, the study population showed a decreased risk for breast cancers (SIR = 0.61) and corpus uteri (SIR = 0.21). Conclusions: The incidence of NHL was higher among patients with SS and SLE. Careful surveillance for hematological malignancies in these patients is recommended

Clues to the star formation in NGC 346 across time and space

We have studied the properties of the stellar populations in the field of the NGC 346 cluster in the Small Magellanic Cloud, using the results of a novel self-consistent method that provides a reliable identification of pre-main sequence (PMS) objects actively undergoing mass accretion, regardless of their age. The 680 identified bona-fide PMS stars show a bimodal age distribution, with two roughly equally numerous populations peaked respectively at ~1 Myr, and ~20 Myr. We use the age and other physical properties of these PMS stars to study how star formation has proceeded across time and space in NGC 346. We find no correlation between the locations of young and old PMS stars, nor do we find a correspondence between the positions of young PMS stars and those of massive OB stars of similar age. Furthermore, the mass distribution of stars with similar age shows large variations throughout the region. We conclude that, while on a global scale it makes sense to talk about an initial mass function, this concept is not meaningful for individual star-forming regions. An interesting implication of the separation between regions where massive stars and low-mass objects appear to form is that high-mass stars might not be "perfect" indicators of star formation and hence a large number of low-mass stars formed elsewhere might have so far remained unnoticed. For certain low surface density galaxies this way of preferential low-mass star formation may be the predominant mechanism, with the consequence that their total mass as derived from the luminosity may be severely underestimated and that their evolution is not correctly understood.Comment: 12 pages, 6 figures, accepted for publication in The Astrophysical Journa