387 research outputs found

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

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    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

    Mercury's geochronology revised by applying Model Production Functions to Mariner 10 data: geological implications

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    Model Production Function chronology uses dynamic models of the Main Belt Asteroids (MBAs) and Near Earth Objects (NEOs) to derive the impactor flux to a target body. This is converted into the crater size-frequency-distribution for a specific planetary surface, and calibrated using the radiometric ages of different regions of the Moon's surface. This new approach has been applied to the crater counts on Mariner 10 images of the highlands and of several large impact basins on Mercury. MPF estimates for the plains show younger ages than those of previous chronologies. Assuming a variable uppermost layering of the Hermean crust, the age of the Caloris interior plains may be as young as 3.59 Ga, in agreement with MESSENGER results that imply that long-term volcanism overcame contractional tectonics. The MPF chronology also suggests a variable projectile flux through time, coherent with the MBAs for ancient periods and then gradually comparable also to the NEOs.Comment: Accepted by Journal Geophysical Research Letter

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

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    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

    Get PDF
    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

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    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

    Il partenariato come risorsa: l’integrazione socio-educativa e sanitaria come prospettiva per far fronte ai bisogni dei minori d’età e le famiglie in situazione di fragilità

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    This research paper analyses the manner in which institution work together in order to meet the educational and development needs of children and families. The contribution presents a survey regarding the ways that the Integrated University Health Authority of Trieste and the Municipality of Trieste work together to develop a partnership for the joint care of vulnerable children. The methodology used is intended to investigate how the above-mentioned services have worked to integratethemselves. We employed documentation produced by the two institutions as well as in-depth interviews with the relevant individuals. The interviewees have expressed the positive results obtained thus far and the critical issues still to be addressed.This research paper analyses the manner in which institution work together in order to meet the educational and development needs of children and families. The contribution presents a survey regarding the ways that the Integrated University Health Authority of Trieste and the Municipality of Trieste work together to develop a partnership for the joint care of vulnerable children. The methodology used is intended to investigate how the above-mentioned services have worked to integratethemselves. We employed documentation produced by the two institutions as well as in-depth interviews with the relevant individuals. The interviewees have expressed the positive results obtained thus far and the critical issues still to be addressed

    Il partenariato come risorsa: l\u2019integrazione socio-educativa e sanitaria come prospettiva per far fronte ai bisogni dei minori d\u2019et\ue0 e le famiglie in situazione di fragilit\ue0

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    This research paper analyses the manner in which institution work together in order to meet the educational and development needs of children and families. The contribution presents a survey regarding the ways that the Integrated University Health Authority of Trieste and the Municipality of Trieste work together to develop a partnership for the joint care of vulnerable children. The methodology used is intended to investigate how the above-mentioned services have worked to integrate themselves. We employed documentation produced by the two institutions as well as in-depth interviews with the relevant individuals. The interviewees have expressed the positive results obtained thus far and the critical issues still to be addressed

    Mild to moderate bleeding: diagnostic and therapeutic paths

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    We consider mild to moderate bleedings all bleeding events that do not meet the criteria proposed by the International Society of Thrombosis and Haemostasis (ISTH) for the definition of major bleeding. As regards the approach to the bleeding patient, the first step is undoubtedly an accurate collection of clinical history and overall physical examination. Then, the etiological diagnosis of a bleeding disorder uses a series of laboratory investigations, divided into first level tests, which are intended to identify the altered phase of the hemostatic process, and second level ones, i.e. more specific tests used if screening tests are negative or to better characterize the alteration identified by them. For the treatment of a bleeding disorder there are several approaches, all strictly dependent on the etiologic diagnosis of this disorder

    Environmental impact assessment of hemp cultivation and its seed-based food products

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    Introduction: Hemp is a crop cultivated in Europe since ancient times, with a variety of purposes and products. Despite being known for its positive environmental effects on ecosystems, the impacts of hemp-based food products have not been sufficiently investigated yet. This paper contributed to deepen the knowledge of the hemp industry by focusing on the potential environmental impact of the cultivation phase (under three different agronomic practices in Italy: organic outdoor and conventional outdoor, and indoor) and the production of selected hemp-based goods (seed oil and flour for food purposes and flowers for therapeutic uses). Methods: The impact was quantified utilizing the life cycle assessment within different impact categories, such as carbon footprint (CF), eutrophication (EP), acidification (AP), and water footprint (WF). For a carbon offset assessment, the carbon storage capability (i.e., the carbon fixed in crop residues left in the field) of hemp was also investigated through the guidelines provided by the Intergovernmental Panel on Climate Change (IPCC). Results and Discussion: The cultivation phase contributed to a CF that ranged from 1.2 (organic outdoor) to 374 (indoor) kg per kg of grains (conventional outdoor). These results were in line with the literature. Sensitivity scenarios based on hotspot analysis were also presented for CF mitigation for each kind of cultivation. On the other hand, the ability of hemp to sequester carbon in the soil due to crop residues left in the field (i.e., carbon storage) was evaluated (-2.7 kg CO2 (ha year)-1), showing that the CF was fully compensated (-0.27 kg CO2 (ha year)-1 for conventional outdoor and -1.07 kg CO2 (ha year)-1 for organic outdoor). Regarding hemp-based products, only dried flowers showed a negative balance (-0.99 kg CO2 per kg dry flower), while hemp oil and flour reported 31.79 kg CO2 per kg flour) when carbon storage was accounted. The results support the idea that the production chain can be sustainable and carbon-neutral only when all the different parts of the plant (flowers, seeds, fibers, leaves, and all residues) were used to manufacture durable goods according to the framework of the circular economy
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