2,619 research outputs found

    Scalable Recovery-based Adaptation on Quadtree Meshes for Advection-Diffusion-Reaction Problems

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    We propose a mesh adaptation procedure for Cartesian quadtree meshes, to discretize scalar advection-diffusion-reaction problems. The adaptation process is driven by a recovery-based a posteriori estimator for the L2(Ω)L^2(\Omega)-norm of the discretization error, based on suitable higher order approximations of both the solution and the associated gradient. In particular, a metric-based approach exploits the information furnished by the estimator to iteratively predict the new adapted mesh. The new mesh adaptation algorithm is successfully assessed on different configurations, and turns out to perform well also when dealing with discontinuities in the data as well as in the presence of internal layers not aligned with the Cartesian directions. A cross-comparison with a standard estimate--mark--refine approach and with other adaptive strategies available in the literature shows the remarkable accuracy and parallel scalability of the proposed approach

    Biochar Amended Soils and Water Systems: Investigation of Physical and Structural Properties

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    There are significant regional differences in the perception of the problems posed by global warming, water/food availability and waste treatment recycling procedures. The study illustrates the effect of application of a biochar (BC) from forest biomass waste, at a selected application rate, on water retention, plant available water (PAW), and structural properties of differently standard textured soils, classified as loamy sand, loam and clay. The results showed that soil water retention, PAW, and aggregate stability were significantly improved by BC application in the loamy sand, confirming that application of BC to this soil was certainly beneficial and increased the amount of macropores, storage pores and residual pores. In the loam, BC partially improved water retention, increasing macroporosity, but decreased the amount of micropores and improved aggregate stability and did not significantly increase the amount of PAW. In the clay, the amount of PAW was increased by BC, but water retention and aggregate stability were not improved by BC amendment. Results of the BET analysis indicated that the specific surface area (BET-SSA) increased in the three soils after BC application, showing a tendency of the BET-SSA to increase at increasing PAW. The results obtained indicated that the effects of BC application on the physical and structural properties of the three considered soils were different depending on the different soil textures with a BET-SSA increase of 950%, 489%, 156% for loamy sand, loam and clay soil respectively. The importance of analysing the effects of BC on soil water retention and PAW in terms of volumetric water contents, and not only in terms of gravimetric values, was also evidenced

    Influence of grape transport and destemming systems on the quality of Chardonnay wines

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    The winemaking technology plays a very important role in enology as it directly influences the characteristics of wine.  In particular, grape transport and destemming are critical steps in winemaking for the wine quality.  The aim of this study was to compare two different processing lines of Chardonnay grapes to evaluate their effects on the quality of the final product. In particular, grapes receiving, transporting and destemming were performed using different machines in order to evaluate their influence on the quality of Chardonnay wines.  The use of a receiving hopper equipped with a belt conveyor, followed by a destemmer equipped with partially coated rubber beaters, allowed to obtain Chardonnay wines of overall higher quality than using a receiving hopper equipped with a screw conveyor, followed by a destemmer equipped with steel beaters. The results were supported by chemical analyses on musts and wines and by the sensory analysis of the wines

    Primary Coronary Embolism as an Unusual Manifestation of Nonbacterial Thrombotic Endocarditis in a Patient with Gastric Cancer

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    Nonbacterial thrombotic endocarditis (NBTE) is a rare clinical condition characterized by the presence of sterile vegetations on valvular leaflets Gross and Friedberg (1936). The most frequent cause of NBTE is antiphospholipid syndrome Hughson and et al. (1993); malignancy, through an intrinsic condition of hypercoagulability, is the second most common cause Thomas (2001). Systemic thromboembolic complications are frequently associated with this condition, but coronary embolism is not common. We report the case of a patient with NBTE secondary to gastric adenocarcinoma with clinical symptoms of coronary and systemic emboli

    Degradation of long-chain n-alkanes in soil microcosms by two actinobacteria

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    The ability of two recently isolated actinobacteria, that degrade medium and long chain n-alkanes in laboratory water medium, was investigated in soil microcosms using different standard soils that were artificially contaminated with n-alkanes of different length (C12- C20- C24- C30). The two strains, identified as Nocardia sp. SoB and Gordonia sp. SoCp, revealed a similar high HC degradation efficiency with an average of 75% alkane degraded after 28 days incubation. A selectivity of bacteria towards n-alkanes of different length was detected as well as a consistent effect of soil texture and other soil physical chemical characteristics on degradation. It was demonstrated the specific aptitude of these selected strains towards specific environmental conditions

    Emergency surgery in a severe penetrating skull base injury by a screwdriver: case report and literature review

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    BACKGROUND: Very few cases of severe penetrating injuries to the skull base with a seemingly innocuous object have been described in the literature. Of the cases reported, only ten involve a penetrating screwdriver. However, the choice of therapeutic management, whether it be emergency surgical or non-surgical removal of the penetrating object as well as the selected surgical approach remain quite controversial. CASE PRESENTATION: The authors describe the case of a severe penetrating skull base injury caused by a screwdriver, following an accidental fall from a ladder. The patient was admitted in Glasgow Coma Scale (GCS) 11 with a cerebrospinal fluid (CSF) leak in the right maxillary area. The tri-dimensional computerized tomography (3-D CT) scan revealed an oblique trajectory of the screwdriver shank through the skull base. The authors opted for an emergency surgical extraction of the object. A contra-lateral pterional approach was successfully performed and a two-year follow-up showed no neurological deficits. CONCLUSION: The reported case supports the choice of emergency surgical removal of the object in penetrating skull base injuries involving the anterior skull base with neurovascular lesions. Surgical aspects of the pterional approach, and in particular the left pterional approach as well as other cranio-facial approaches in severe penetrating skull base injuries are discussed

    A system to control the atmosphere in the headspace of the malaxation machine to improve the fatty acid composition of extra virgin olive oils

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    In recent years, oxygen content regulation during malaxation has been noted as a process parameter. As concluded by many studies, the presence of oxygen during malaxation has a key role in for improving the quality of Extra Virgin Olive Oil (EVOO) in terms of volatile and phenolic components. There are, however, very few studies of the influence of oxygen in the malaxation machine headspace on the fatty acid composition of Extra Virgin Olive Oil (EVOO). The aim of this study is to evaluate the influence of oxygen in the malaxation machine headspace on Nocellara del Belice EVOO fatty acids. During of the malaxation process, the atmosphere inside the malaxation machine was modified by blowing pure oxygen from cylinders at specific stages of the process (i.e. 15, 25, and 35 minutes after the start of malaxation), using a system which ensures the automatic and continuous maintenance of a known amount of oxygen into the headspace at a given moment throughout the malaxation process. The results show that the amount of saturated and unsaturated fatty acids present in EVOO depends specifically on the timepoint of the malaxation process when oxygen is blown into the head space of the machine and much less on the amount of oxygen. The study confirms that monitoring and controlling the atmosphere inside the malaxation machine is necessary to obtain high quality EVOO with strong nutraceutical properties

    Efficiency of biochar for reducing mobility of inorganic contaminants

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    Anthropogenic activities have produced numerous sites with extensive contamination close to residential areas. Several physicochemical and biological remediation methods exist for remediation of metal contaminated soils and lands, such as soil washing, soil flushing, phytoremediation, and electrokinetics. Biochar (biologically derived charcoal) is produced by pyrolysis of biomasses under low oxygen conditions, and it can be applied for recycling organic waste in soils. The main objectives of the present study were to determine the possible use of biochar from forest ersidues (Populus nigra) in order to achieve a stabilization of inorganic contaminants by adsorption processes. Adsorption of copper by biochar from dilute solutions showed a closer agreement with the Langmuir isotherm in a concentration range 25-500 mM. The decontamination by biochar is very suitable because the treatment is passive and does not require specialized equipment or extensive labor as compared to other remediation methods. Moreover, biochar is also a possible carbon sink due to its long term storage in environment, thereby favouring mitigation of the anthropic impact on environment

    Nature of Interactions at the Interface of Two Water-Saturated Commercial TiO2 Polymorphs

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    Two commercial TiO2 samples, a 100% anatase and a 100% rutile, were used for the fast field cycling NMR experiments. The results showed a different behavior between the different samples. In particular, water molecules were unbonded to the solid surface for the rutile sample, whereas they appeared to chemically interact with the surface through H-bond formation with the anatase sample. The above findings accord with the generally lower activity of rutile with respect to anatase reported in literature for photocatalytic oxidation reactions in water. The difficulty of water to interact with rutile surface, indeed, could hinder the formation of OH radicals, which are the most important oxidant species

    Diffuse Supravalvular Aortic Stenosis: Surgical Repair in Adulthood

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    We present the case of a 54-year-old woman in which a diffuse congenital supravalvular aortic stenosis (SVAS) was associated with a severe aortic valve incompetence and heavy calcification of the aortic annulus. Repair consisted in resection of the ascending aorta, patch augmentation of the hypoplastic aortic root and annulus, placement of a 20 mm Dacron tubular graft (Vascutek, Renfrewshire, UK) and aortic valve replacement with a mechanical prosthesis (Sorin, Turin, Italy). Follow-up echocardiography demonstrated normal prosthetic valve function and a postoperative three-dimensional computed tomographic scan showed a normal shape of the reconstructed ascending aorta
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