73 research outputs found

    The genus <i>Acanthochitona</i> (Mollusca: Polylacophora) in the Mediterranean Sea: morphological and molecular data

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    En el presente trabajo se pretende resolver la confusa taxonomía de las especies mediterráneas de los quitones del género Acanthochitona a través de su estudio morfológico (observaciones al SEM de aestetes, rádula y cintura) y molecular (COI, 12S, ITS1). En ambos casos se confirma la validez de las tres especies Acanthochitona fascicularis, A. crinita y A. oblonga, las dos últimas consideradas previamente como sinónimas

    Soft tissue regeneration using leukocyte-platelet rich fibrin after exeresis of hyperplastic gingival lesions: Two case reports

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    Introduction The Leukocyte-PRF (Leukocyte-Platelet Rich Fibrin) belongs to a second generation of platelet concentrates which doesn’t need a biochemical blood manipulation. It is used for tissue healing and regeneration in periodontal and oral-maxillofacial surgery. We report two cases of hyperplastic gingival lesions treated by exeresis and application of PRF membranes in order to improve and accelerate tissue healing. Case Presentation Two patients (one Caucasian female, 78-year-old, and one Caucasian male, 30-year-old) were treated for hyperplastic gingival lesions. They underwent to exeresis of lesions and application of PRF membranes. Tissue healing was clinically evaluated after one, three, seven, fourteen and thirty post-operative days. No recurrences were observed after two years of semiannual follow up. Conclusion We obtained rapid and good healing of soft tissues probably due to the elevated content of leukocytes, platelets and growth factors in the leukocyte-platelet rich fibrin. According to our results we suggest L-PRF employment for wounds covering after exeresis of oral neoformations such as hyperplastic gingival lesions

    Analogies between SARS-CoV-2 infection dynamics and batch chemical reactor behavior

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    The pandemic infection of SARS-CoV-2 presents analogies with the behavior of chemical reactors.Susceptible population (A), active infected population (B), recovered cases (C) and deaths (D) can beassumed to be molecules of chemical compounds and their dynamics seem well aligned with those ofcomposition and conversions in chemical syntheses. Thanks to these analogies, it is possible to generatepandemic predictive models based on chemical and physical considerations and regress their kineticparameters, either globally or locally, to predict the peak time, entity and end of the infection with certainreliability. These predictions can strongly support the emergency plans decision making process. Themodel predictions have been validated with data from Chinese provinces that already underwent com-plete infection dynamics. For all the other countries, the evolution is re-regressed and re-predicted everyday, updating a pandemic prediction database on Politecnico di Milano’s webpage based on the real-timeavailable data

    Transnational agricultural land acquisitions threaten biodiversity in the Global South

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    Agricultural large-scale land acquisitions have been linked with enhanced deforestation and land use change. Yet the extent to which transnational agricultural large-scale land acquisitions (TALSLAs) contribute to—or merely correlate with—deforestation, and the expected biodiversity impacts of the intended land use changes across ecosystems, remains unclear. We examine 178 georeferenced TALSLA locations in 40 countries to address this gap. While forest cover within TALSLAs decreased by 17% between 2000 and 2018 and became more fragmented, the spatio-temporal patterns of deforestation varied substantially across regions. While deforestation rates within initially forested TALSLAs were 1.5 (Asia) to 2 times (Africa) higher than immediately surrounding areas, we detected no such difference in Europe and Latin America. Our findings suggest that, whereas TALSLAs may have accelerated forest loss in Asia, a different mechanism might emerge in Africa where TALSLAs target areas already experiencing elevated deforestation. Regarding biodiversity (here focused on vertebrate species), we find that nearly all (91%) studied deals will likely experience substantial losses in relative species richness (−14.1% on average within each deal)—with mixed outcomes for relative abundance—due to the intended land use transitions. We also find that 39% of TALSLAs fall at least partially within biodiversity hotspots, placing these areas at heightened risk of biodiversity loss. Taken together, these findings suggest distinct regional differences in the nature of the association between TALSLAs and forest loss and provide new evidence of TALSLAs as an emerging threat to biodiversity in the Globa

    Shear-induced pressure changes and seepage phenomena in a deforming porous layer-I

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    We present a model for flow and seepage in a deforming, shear-dilatant sensitive porous layer that enables estimates of the excess pore fluid pressures and flow rates in both the melt and solid phase to be captured simultaneously as a function of stress rate. Calculations are relevant to crystallizing magma in the solidosity range 0.5–0.8 (50–20 per cent melt), corresponding to a dense region within the solidification front of a crystallizing magma chamber. Composition is expressed only through the viscosity of the fluid phase, making the model generally applicable to a wide range of magma types. A natural scaling emerges that allows results to be presented in non-dimensional form. We show that all length-scales can be expressed as fractions of the layer height H, timescales as fractions of H2(nβ'θ+ 1)/(θk) and pressures as fractions of . Taking as an example the permeability k in the mush of the order of magnitude 1015 m2 Pa1 s1, a layer thickness of tens of metres and a mush strength (θ) in the range 108–1012 Pa, an estimate of the consolidation time for near-incompressible fluids is of the order of 105–109 s. Using mush permeability as a proxy, we show that the greatest maximum excess pore pressures develop consistently in rhyolitic (high-viscosity) magmas at high rates of shear ( , implying that during deformation, the mechanical behaviour of basaltic and rhyolitic magmas will differ. Transport parameters of the granular framework including tortuosity and the ratio of grain size to layer thickness (a/H) will also exert a strong effect on the mechanical behaviour of the layer at a given rate of strain. For dilatant materials under shear, flow of melt into the granular layer is implied. Reduction in excess pore pressure sucks melt into the solidification front at a velocity proportional to the strain rate. For tectonic rates (generally 1014 s1), melt upwelling (or downwelling, if the layer is on the floor of the chamber) is of the order of cm yr1. At higher rates of loading comparable with emplacement of some magmatic intrusions (1010 s1), melt velocities may exceed effects due to instabilities resulting from local changes in density and composition. Such a flow carries particulates with it, and we speculate that these may become trapped in the granular layer depending on their sizes. If on further solidification the segregated grain size distribution of the particulates is frozen in the granular layer, structure formation including layering and grading may result. Finally, as the process settles down to a steady state, the pressure does not continue to decrease. We find no evidence for critical rheological thresholds, and the process is stable until so much shear has been applied that the granular medium fails, but there is no hydraulic failure

    Techno-economic feasibility study of acid gas to syngas (AG2STM) technology applied to oil refinery

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    The novelty of AG2STM (Acid Gas to Syngas) technology lies in the capability of producing syngas, a valuable product, from acid gases (H2S and CO2), which are refinery by-products. This work aims to propose and indicate the implementation of such technology as a revamping option of the already-running Claus plant. An applicability range based on industrial data by coupling two different software applications, i.e., Aspen HYSYS and MATLAB®. A comparison study between the two processes were developed, choosing some critical parameters (i.e., furnace inlet temperature, flame temperature, sulfur recovery efficiency, ratio of H2S and CO2 in the feed). The significance of introduced innovations is highlighted, at a technical, economic and environmental level. Due to complete recycle of H2S, relevant reduction of CO2, and syngas production the new technology appears to lean toward environmental and energy improvements and it could be integrated, without major investments, into existing systems, significantly increasing their performance

    Impact of Kinetic Models on Methanol Synthesis Reactor Predictions: In Silico Assessment and Comparison with Industrial Data

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    The reactor is one of the most important equipment to be designed for optimal process operations. An appropriate reactor modeling leads to an efficient and optimal process conceptual design, simulation, and eventually construction. The key for success in this step is mainly related to kinetics. The present work is centered toward process simulation and aims at comparing three different kinetic models for methanol synthesis. The comparison shows how the refitted Graaf model, presented in a previous study, effectively predicts the performance of modern methanol synthesis loops. To pursue this objective, we simulated in Aspen HYSYS three methanol synthesis technologies (the most popular technologies in modern plants) and compared the results with industrial data. The proposed case study demonstrates that the refitted Graaf model is more accurate in output prediction than the well-established original Graaf and Vanden Bussche-Froment models, which are currently considered the industrial benchmark, thus showing how the refitted Graaf model is a potential candidate for future industrial applications
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