207 research outputs found

    ON THE EFFECTS OF THE INTERPHASE ON THE DAMPING OF CFRP STRUCTURES: AN EXPERIMENTAL INVESTIGATION

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    The increased adoption of composite laminates in modern engineering requires advancement in the prediction of their dynamic behavior. Damping is a major design constraint in aerospace structures subjected to cyclic loads. While the effects caused by damping are well known, the mechanisms that cause it at the microscopic level are still unclear on a quantitative basis. Testing of these phenomena requires some difficulties to be overcome, like the contribution of spurious sources. The study focuses on the effects that the interphase has on the damping properties of carbon fiber-reinforced polymer (CFRP) composite structures. Three-phase models are employed to investigate the dependence of damping on the interphase mechanical properties, with a focus on the fiber-matrix interfacial shear strength. The experimental campaign confirms the attended results: in particular, a stronger interphase determines a lower damping of the structure

    Agronomical evaluation and chemical characterization of Linum usitatissimum L. as oilseed crop for bio-based products in two environments of Central and Northern Italy

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    In the recent years, new perspectives for linseed (Linum usitatissimum L.) are open as renewable raw material for bio-based products (Bb), due to its oil composition, and the interesting amounts of coproducts (lignocellulosic biomass). Therefore, the possibility to introduce linseed crop in two environments of central and northern Italy, traditionally devoted to cereal cultivation, has been evaluated. Twoyears field trials were carried out in the coastal plain of Pisa (Tuscany region) and in the Po valley (Bologna, Emilia Romagna region), comparing two linseed varieties (Sideral and Buenos Aires). Agronomical evaluation (yield and yield components), seed and oil characterization (oil, protein content, and fatty acid composition), together with carbon (C) and nitrogen (N) content of the residual lignocellulosic biomass were investigated. The two varieties, grown as autumn crop, showed a different percentage of plant survival at the end of winter, with Sideral most resistant to cold. The achieved results showed significant influence of cultivar, location and growing season on yield and yield components, as well as on chemical biomass composition. In particular, Sideral appeared to be the most suitable variety for tested environments, since higher seed yield (3.05 t ha–1 as mean value over years and locations) and above-ground biomass (6.98 t ha–1 as mean value over years and locations) were recorded in comparison with those detected for Buenos Aires (1.93 and 4.48 t ha–1 of seed production and lignocellulosic biomass, respectively). Interestingly, in the northern area, during the 1st year, Buenos Aires was the most productive, despite its low plant survival at the end of winter, which determined a strong reduction in plant density and size. In such conditions, the plants produced a larger number of capsules and, consequently, high seed yield (3.18 t ha–1). Relevant differences were also observed between the two years, due to the variability of climatic characteristics (temperature levels, and moisture regimes). All these findings confirmed as, in linseed, yield and yield components are quantitatively inherited and influenced by both genotype and environment (location and climate). Varietal and environmental effects were also recorded for oil content and yield, and, generally, good oil percentages, for both genotypes, were found (ranging from 44 to 49% on dry matter basis). Oil from the two varieties was characterized by a stable proportion of polyunsaturated fatty acids with a high content of alpha-linolenic acid (more than 57%), that makes this oil suitable to be used in paints, resins, varnishes, linoleum, polymers and oleochemicals. Finally, our results pointed out as above- and below-ground biomasses, were different in terms of quantity, and chemical characteristics (N, C and C/N ratio). Interesting amounts of N and C could return into the soil by crop residues (stem portions and roots), thus underling the possibility to maintain and/or increase the soil organic matter pool

    Effectiveness of chest physiotherapy and pulmonary rehabilitation in patients with non-cystic fibrosis bronchiectasis: a narrative review.

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    Respiratory physiotherapy and rehabilitation are important therapeutic options in non-cystic fibrosis bronchiectasis (NCFB). The aims of this review of clinical trials were to evaluate the safety and the effects on physiologic and clinical outcomes of airway clearance techniques (ACTs) and rehabilitation in NCFB patients, in comparison to usual care. The search was performed on March 2018 by using PubMed and PeDro databases. 33 studies were selected. The use of ACTs for NCFB were effective in increasing sputum volume although no benefit in quality of life (QoL) or pulmonary exacerbations were observed. There were no differences in effectiveness between the several techniques used. Humidification and saline inhalation were able to aid airway clearance. Hypertonic solution (HS) was more effective than isotonic solutions (IS) in improving expectoration and sputum viscosity. Pulmonary rehabilitation (PR) was found to be associated with short term benefits in exercise capacity, dyspnea and fatigue. Exercise training seems to improve quality of life and lower exacerbation rate, but long-term data are not available. Further studies are necessary to identify the most feasible long-term outcomes such as QoL and exacerbation rate

    Environmental assessment of flax straw production for non-wood pulp mills

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    Nowadays, there is an increasing interest for using non-woody fibres as raw materials for production of paper´s pulp. The present work aims to identify and quantify the environmental impacts associated with the production of flax fibres, through 3-year field experiment, carried out in Bologna and Pisa representative of the pedoclimatic characteristics of central Italy. Life Cycle Impact of “a one ton of fibre ready to be processed in a pulp mill” was assessed taking into account: farming, straw process (drying, scutching and baling) and transport. Inventory data for agricultural inputs and outputs were obtained directly from field experimentation and from bibliographic data about heat, transport and electricity consumption on straw processing. An economic allocation approach to assign impacts within flax seed and processed straw has been used. The CML baseline 2000 methodology was selected to quantify the potential environmental impact associated to the crops. Specifically, global warming (GWP), acidification (AP), eutrophication (EP) and photochemical oxidant formation (POP) were evaluated together with energy use (EU). Major impacts contribution arise from fertilizers use and straw processing. Cultivation phase of flax fibre at Pisa reported higher values (approximately 3 times greater) for all the impact categories. The lower impact in the flax cultivation scenario at Bologna was due to no use of mineral fertilizer and the higher flax-straw yield. It resulted also a strong reduction of the impacts with respect to those of hemp pulp in Spain as well as to the impacts of the conventional wood-pulp reported in Simapro. Furthermore, LCA tool aided to identify the materials and process that most affected the impacts: fertilizers use, diesel consumption and straw processing were identified as hot spots in both crops. Finally, non-wood pulp derived from Bologna´s Flax straw represents an opportunity to replace conventional wood pulp in Italian paper industry

    An adaptive stigmergy-based system for evaluating technological indicator dynamics in the context of smart specialization

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    Regional innovation is more and more considered an important enabler of welfare. It is no coincidence that the European Commission has started looking at regional peculiarities and dynamics, in order to focus Research and Innovation Strategies for Smart Specialization towards effective investment policies. In this context, this work aims to support policy makers in the analysis of innovation-relevant trends. We exploit a European database of the regional patent application to determine the dynamics of a set of technological innovation indicators. For this purpose, we design and develop a software system for assessing unfolding trends in such indicators. In contrast with conventional knowledge-based design, our approach is biologically-inspired and based on self-organization of information. This means that a functional structure, called track, appears and stays spontaneous at runtime when local dynamism in data occurs. A further prototyping of tracks allows a better distinction of the critical phenomena during unfolding events, with a better assessment of the progressing levels. The proposed mechanism works if structural parameters are correctly tuned for the given historical context. Determining such correct parameters is not a simple task since different indicators may have different dynamics. For this purpose, we adopt an adaptation mechanism based on differential evolution. The study includes the problem statement and its characterization in the literature, as well as the proposed solving approach, experimental setting and results

    A fully photonics-based coherent radar system

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    The next generation of radar (radio detection and ranging) systems needs to be based on software-defined radio to adapt to variable environments, with higher carrier frequencies for smaller antennas and broadened bandwidth for increased resolution. Today's digital microwave components (synthesizers and analogue-to-digital converters) suffer from limited bandwidth with high noise at increasing frequencies, so that fully digital radar systems can work up to only a few gigahertz, and noisy analogue up- and downconversions are necessary for higher frequencies. In contrast, photonics provide high precision and ultrawide bandwidth, allowing both the flexible generation of extremely stable radio-frequency signals with arbitrary waveforms up to millimetre waves, and the detection of such signals and their precise direct digitization without downconversion. Until now, the photonics-based generation and detection of radio-frequency signals have been studied separately and have not been tested in a radar system. Here we present the development and the field trial results of a fully photonics-based coherent radar demonstrator carried out within the project PHODIR. The proposed architecture exploits a single pulsed laser for generating tunable radar signals and receiving their echoes, avoiding radio-frequency up- and downconversion and guaranteeing both the software-defined approach and high resolution. Its performance exceeds state-of-the-art electronics at carrier frequencies above two gigahertz, and the detection of non-cooperating aeroplanes confirms the effectiveness and expected precision of the system

    AN IN VIVO MODEL OF HYPERACUTE REJECTION: CHARACTERIZATION AND EVALUATION OF THE EFFECT OF TRANSGENIC HUMAN COMPLEMENT INHIBITORS

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    Hyperacute rejection (HAR) occurring after transplantation within phylogenetically distant species is a severe reaction triggered by preexisting xenoreactive antibodies and complement activation, leading to the destruction of the donor organ. Expression of human complement inhibitors in transgenic pig organs prolongs the survival of xenograft in experimental models. Moreover, the extent of protection from hyperacute rejection is dependent on the level and site of expression of the transgenic molecules and, probably, on the combination of different molecules. In this regard a small animal model to test the efficacy of expression vectors and different human molecules could be very advantageous. A murine model developed in our laboratory was characterized by measurement of several parameters characteristic of HAR in the livers of control and transgenic mice expressing transgenic human DAF (CD55) or MCP (CD46) at the end of 2 h of perfusion with human plasma and after 1 day. The parameters studied were heamatological values of hepatic functions (GOT and GPT), induction of pro-inflammatory molecules and histopathological evaluation. Cytokines (IL-1 alpha, IL-1 beta, IL-6) induction and exposure of P-selectin on the endothelial cell surface, was only observed in control animals after 2 h of perfusion, as an early event. GOT and GPT values increase drammatically after 2 h perfusion and 1 day after the treatment according to the histopathological observation of liver damage. On the contrary, the livers of hDAF or hMCP transgenic mice, under the same treatment were significantly protected although the extent of this protection is dependent on the level of expression of transgenic human molecules

    Application and uses of electronic noses for clinical diagnosis on urine samples: A review

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    The electronic nose is able to provide useful information through the analysis of the volatile organic compounds in body fluids, such as exhaled breath, urine and blood. This paper focuses on the review of electronic nose studies and applications in the specific field of medical diagnostics based on the analysis of the gaseous headspace of human urine, in order to provide a broad overview of the state of the art and thus enhance future developments in this field. The research in this field is rather recent and still in progress, and there are several aspects that need to be investigated more into depth, not only to develop and improve specific electronic noses for different diseases, but also with the aim to discover and analyse the connections between specific diseases and the body fluids odour. Further research is needed to improve the results obtained up to now; the development of new sensors and data processing methods should lead to greater diagnostic accuracy thus making the electronic nose an effective tool for early detection of different kinds of diseases, ranging from infections to tumours or exposure to toxic agents
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