11,558 research outputs found

    SCINTILLA A European project for the development of scintillation detectors and new technologies for nuclear security

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    Europe monitors transits using radiation detectors to prevent illicit trafficking of nuclear materials. The SCINTILLA project aims to develop a toolbox of innovative technologies designed to address different usage cases. This article will review the scope, approach, results of the first benchmark campaign and future plans of the SCINTILLA project.Comment: To appear on the Proceedings of the 13th ICATPP Conference on Astroparticle, Particle, Space Physics and Detectors for Physics Applications, Villa Olmo (Como, Italy), 23--27 October, 2013, to be published by World Scientific (Singapore

    Investigations on anomalies of ovule development and on pollination in mutated grapevines, cv. Barbera

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    In order to point out the reasons for reduced fertility in tetraploid and 2n-4n periclinal chimera grapevines, ovule development and pollination shown by these plants were investigated.Anomalies in embryo sac formation and non-fertilization, mainly due to difficulties in pollination, were observed and related to fertility

    Autonomous detection and ascent of a step for an electric wheelchair

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    With the number of individuals using a wheelchair on the rise, the issue of removing architectural barriers, or at least overcoming them, has to be faced to improve independence, inclusiveness, and participation of wheelchair users. Some electric wheelchairs can climb and descend stairs and obstacles, however, the actual operations required to do so safely may be complex and may require an experienced or trained user. To overcome this issue, a method to first detect and classify a step and then autonomously climb it safely is proposed here. The same method is then applied and tested on an actual stair-climbing wheelchair prototype to prove its reliability in different conditions

    The phlebological surgery in elderly patients

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    The pathogenesis of the lower limbs varicose veins in the elderly patients is the same one as in the juvenile and adult age. What changes is the severity of the clinical picture, because the disease is a chronic pathology and it is aggravated with the passing of the years in absence of prophylaxis and missed or inadequate therapy. Equally the surgical operations on the superficial venous system of the elderly patients from a technical point of view are the same that are practiced in other ages of life. What changes is the anaesthesiological risk, which is increased, because other chronic pathologies are frequently associated with the old ones. Currently both the use of techniques of peripheral anesthesia, as the blocks of the lower limbs nervous trunks, and the introduction of poor toxic anesthetics for the heart in therapeutical practice allow in an inci¬sive way to submit elderly people to surgical procedures. Above all the out-patient hemodynamic surgery of the superficial chronic venous insufficiency, which requires a careful and meticulous instrumental investigation aimed surgical gestures, but simple, effective, of brief duration, has convinced many surgeons of the possibility to operate on the varicose patients of a more and more advance age. On the other hand the rapid postoperative mobiliza¬tion of those sick, in absence of immediate complica¬tions, means that they can be discharged from the hospital on the same day of the operation. This undoubtedly involves positive reflexes on the sanitary expense and it increases at the same time the compliance in terms of motivation and acceptance of the proposed procedure. The elderly patient, perhaps more than the younger adult, once informed of the new anaesthesiological and surgical techniques, gladly gives his consent to the inter¬vention, pleased to return to his own house and tquickly return to his daily occupations. How much I dictate you is translated in our experi¬ence, that is carried out near the Phlebological Center of the Siena University, in a progressive increase in the last 5 years both in absolute terms (223) and percen¬tages (12%) of the number of subjects older than sixty¬five years old that have been submitted to surgical operations for the venous disease. Of all 223 patients, males are 68 and females are 155; 144of them have an age between 66 and 70 years, 73 belonging to the eighty years of life and 6 subject to the ninty. All patients have been operated in Day Hospi¬tal admission. No mortality has been found. Local post-operative complications was encountered in 1,8% of the cases

    Influence of Biochar on the Properties of Antibacterial PBAT/Carvacrol Films

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    In recent years, there has been an increasing interest in antibacterial biopolymeric films. Among the different approaches for tuning the release kinetic of antibacterial compounds, the use of natural fillers allows for this purpose while optimizing the processability and the mechanical properties of the products. In this work, the effect of three different concentrations of biochar (BC) was investigated on the morphological, rheological, mechanical, and thermal properties of Polybutylene adipate terephthalate/Carvacrol/BC (PBAT/CV/BC) ternary biocomposites. The films were fabricated by means of melt mixing and compression molding and compared to PBAT/BC samples. The carvacrol kinetic release was evaluated as a function of the BC concentration in the ternary system. Results highlighted that BC allows tuning the properties of PBAT and of PBAT/CV samples and modifying the release kinetic of CV. Finally, the antimicrobial analysis revealed that PBAT/CV films exhibited excellent antimicrobial properties against Escherichia coli, Listeria monocytogenes, Salmonella Enteritidis, and Staphylococcus aureus

    Accuracy Characterization of a MEMS Accelerometer for Vibration Monitoring in a Rotating Framework

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    Active and passive vibration control systems are of paramount importance in many engineering applications. If an external load excites a structure’s resonance and the damping is too low, detrimental events, such as crack initiation, growth and, in the worst case, fatigue failure, can be entailed. Damping systems can be commonly found in applications such as industrial machines, vehicles, buildings, turbomachinery blades, and so forth. Active control systems usually achieve higher damping effectiveness than passive ones, but they need a sensor to detect the working conditions that require damping system activation. Recently, the development of such systems in rotating structures has received considerable interest among designers. As a result, the development of vibration monitoring equipment in rotating structures is also a topic of particular interest. In this respect, a reliable, inexpensive and wireless monitoring system is of utmost importance. Typically, optical systems are used to measure vibrations, but they are expensive and require rather complex processing algorithms. In this paper, a wireless system based on a commercial MEMS accelerometer is developed for rotating blade vibration monitoring. The proposed system measurement accuracy was assessed by means of comparison with a reference wired measurement setup based on a mini integrated circuit piezoelectric (ICP) accelerometer adapted for data acquisition in a rotating frame. Both the accelerometers were mounted on the tip of the blade and, in order to test the structure under different conditions, the first four blade resonances were excited by means of piezoelectric actuators, embedded in a novel experimental setup. The frequency and amplitude of acceleration, simultaneously measured by the reference and MEMS sensors, were compared with each other in order to investigate the viability and accuracy of the proposed wireless monitoring system. The rotor angular speed was varied from 0 to 300 rpm, and the data acquisitions were repeated six times for each considered condition. The outcomes reveal that the wireless measurement system may be successfully used for vibration monitoring in rotating blades

    Incompressible viscous flow near the leading edge of a flat plate admitting slip

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    The shear stress at the leading edge, calculated on basis of the Navier-Stokes equations and the no-slip boundary condition, approaches infinity. However, taking into account the mean free path of the molecules, which implies admitting a certain slip, the shear stress becomes inversely proportional to the square root of the Knudsen number κ if κ→0. κ is defined as the ratio between the mean free path and the viscous length. The new boundary condition modifies the shear stress only within the Knudsen region of which the size is of the order of 3 to 4 times the mean free path.
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