Synchrotron XRD study of residual stress in a shot peened Al/SiCp composite

In the present study, residual strain profiles in shot peened specimens of 2124-T4 aluminium alloy matrix composite reinforced with 17vol% particulate silicon carbide (SiCp) were measured by means of synchrotron-based diffraction using monochromatic, high energy X-ray beams. The stress state was considered in relation with the microstructural and morphological modifications induced in the material by shot peening. Strain-induced changes in the lattice parameters were deduced from diffraction measurements made by two detectors mounted in the horizontal and vertical diffraction planes, providing information on lattice strains in two nearly mutually perpendicular in-plane directions. On the basis of these data, residual strain and stress profiles through the specimen thickness were reconstructed for both phases (silicon carbide and aluminium alloy). Microstructural characterization was performed by means of optical and scanning electron microscopy (SEM), and particle distribution and hardness modification were identified. The effect of shot peening on the reinforcement and matrix stress states was evaluated. The findings are discussed in the context of process optimization for fatigue resistance improvement in aluminium alloy-based MMCs

Caratterizzazione microstrutturale e prove di resilienza su giunti Friction Stir Welding e Linear Friction Welding di compositi a matrice metallica

In questo studio sono stati caratterizzati giunti Friction Stir Welding e Linear Friction Welding su compositi a matrice in lega di alluminio e rinforzo particellare ceramico. Il processo FSW è stato applicato a due compositi ottenuti con processo fusorio, quindi estrusi e trattati termicamente T6: AA6061/20%vol.Al2O3p e AA7005/10%vol.Al2O3p. I giunti LFW sono stati invece realizzati su un composito con matrice in lega di alluminio e rinforzo particellare in carburo di silicio, ottenuto mediante metallurgia delle polveri, quindi forgiato e trattato termicamente T4: AA2124/25%vol.SiCp. Sono stati esaminati gli effetti della saldatura sullecaratteristiche microstrutturali dei giunti, avvalendosi di tecniche di microscopia ottica con analisi di immagine e di microscopia elettronica in scansione (SEM) con microsonda a dispersione di energia (EDS). Sono state quindi condotte prove di resilienza con pendolo strumentato Charpy. Lo studio dei meccanismi di danneggiamento è stato effettuato mediante analisi al SEM delle superfici di frattura. Entrambi i processi di saldatura hanno portato a giunti sostanzialmente esenti da difetti. La microstruttura dei cordoni è risultata dipendente sia dalle caratteristiche microstrutturali iniziali dei compositi considerati, sia dalla tipologia di processo di saldatura. Nel caso dei compositi AA6061/20%Al2O3p e AA7005/10%Al2O3p saldati FSW si è osservato un sostanziale incremento di resilienza, rispetto al materiale base, in conseguenza dell’affinamento dei grani della matrice, della riduzione della dimensione media delle particelle di rinforzo e della loro spigolosità, indotte dal processo di saldatura. Il composito AA2124/25%SiCp saldato LFW ha presentato valori di resilienza confrontabili con quelli del materiale base, in conseguenza, soprattutto, dei limitati effetti della saldatura su dimensione e distribuzione delle particelle di rinforzo

First craneal evidence and documented occurrence of Cuniculus paca (Rodentia, Cuniculidae) for the Humid Chaco region of Argentina

Se reporta el primer registro con material de referencia de Cuniculus paca para la provincia de Formosa en la Región Chaqueña Argentina. Este se basa en un cráneo colectado y en 18 fotografías obtenidas con trampas cámaras en la selva en galería del riacho Pilagá (estancia Guaycolec: 25° 58’ S, 58° 11’ O) ubicada en la macrounidad ambiental del Chaco Húmedo. Se caracterizó el patrón de actividad de la especie a partir de los registros horarios de las fotografías. Se observó un patrón de actividad estrictamente nocturno, aparentemente influenciado por el ciclo lunar; no se obtuvo ningún registro fotográfico durante períodos de luna llena o luna nueva. Todas las fotos fueron obtenidas a una distancia máxima de 170 m del río, indicando una fuerte asociación de la especie con los cursos de aguaWe report the first record of Cuniculus paca for the province of Formosa in Argentina and the Argentinean Gran Chaco region based on one skull found close to the river Pilagá (estancia Guaycolec: 25° 58’ S, 58° 11’ W) and on 18 photos taken by camera traps. Since the photos include time-stamps, we were able to evaluate the activity pattern of the paca in that area. Pacas showed strict nocturnal behavior and seemed to be influenced by the lunar cycles; there were no records during full and new moon. All photos were taken at a maximum distance of 170 m to the river, confirming the strong association of the species to watercourses.Fil: Huck, Maren. Deutsches Primatenzentrum; AlemaniaFil: Juárez, Cecilia Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina. Barrio General José de San Martín. Proyecto Mirikiná; ArgentinaFil: Rotundo, Marcelo A.. Barrio General José de San Martín. Proyecto Mirikiná; ArgentinaFil: Fernandez Duque, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Barrio General José de San Martín. Proyecto Mirikiná; Argentina. University of Pennsylvania; Estados Unido

Preliminary Ground Motion Measurements at LNF Site for the Super B Project

TUPEA067International audienceFol­low­ing pre­vi­ous mea­sure­ments, more de­tailed pre­lim­i­nary ground mo­tion mea­sure­ments have been per­formed at the LNF site for the Super B pro­ject site char­ac­ter­i­za­tion. First, re­sults of ver­ti­cal ground mo­tion mea­sure­ments done dur­ing 18 hours are shown in order to get an idea of the evo­lu­tion of the ground mo­tion am­pli­tude with time. Sec­ond­ly, mea­sure­ments of ground mo­tion (in the 3 di­rec­tions of space) were per­formed at dif­fer­ent lo­ca­tions on sur­face in order to eval­u­ate and to com­pare the in­flu­ence of var­i­ous vi­bra­tion sources. Then, re­sults of ground mo­tion co­her­ence mea­sured for dif­fer­ent dis­tances at two lo­ca­tions close to each other but with soft and rigid floor are com­pared. These mea­sure­ments are also com­pared to the ones done in the ATF2 beam line where a spe­cial floor was built for sta­bil­i­ty. By this way, the re­sults re­veal that the LNF is a good site to use ground mo­tion co­her­ence prop­er­ties for sta­bil­i­ty like it has been done for ATF2

Sensory Adaptation of Antennae and Sex Pheromone-Mediated Flight Behavior in Male Oriental Fruit Moths (Leptidoptera: Tortricidae) After Prolonged Exposure to Single and Tertiary Blends of Synthetic Sex Pheromone

Sensory adaptation has been measured in the antennae of male Grapholita molesta (Busck) after 15 min of exposure to its main pheromone compound (Z)-8-dodecen-1-yl acetate (Z8-12:OAc) at the aerial concentration of 1 ng/m(3) measured in orchards treated with pheromone for mating disruption. Exposing males to this aerial concentration of Z8-12:OAc for 15 min, however, had only a small effect on their ability to orientate by flight to virgin calling females in a flight tunnel. Experiments were undertaken to determine if exposure to the main pheromone compound in combination with the two biologically active minor compounds of this species, (E)-8-dodecen-1-yl acetate (E8-12:OAc) and (Z)-8-dodecen-1-ol (Z8-12:OH) would induce greater levels of sensory adaptation and have a greater effect on male sexual behavior. The exposure of male antennae to 0.5 g/m(3) air of one of the three pheromone compounds induced sensory adaptation to this compound and to the other two pheromone compounds demonstrating cross adaptation. Average percentage sensory adaptation to a pheromone compound was similar after 15 min of exposure to 1 ng/m(3) air of Z8-12:OAc, or to 1 ng/m(3) air of a 1:1:1 or 93:6:1 blend of Z8-12:OAc, E8-12:OAc, and Z8-12:OH. The exposure of males to 1 ng/m(3) air of Z8-12:OAc or the two ratios of Z8-12:OAc, E8-12:OAc, and Z8-12:OH for 15 min had no effect on their ability to orientate to a virgin calling female. The implications of these results for the operative mechanisms of sex pheromone-mediated mating disruption of this species are discussed

Ecophysiology and vine performance of cv. “Aglianico” under various training systems

Abstract A 2-year study was conducted to evaluate ecophysiological characteristics and yield±quality performance of cv.``Aglianico'' (Vitis vinifera L.) grapevines trained to three different trellises at the same intrarow vine spacing and bud load per meter of row length. Bilateral guyot (BG) showed the lowest vine capacity and bilateral spur-pruned cordon (BSPC), with a vertical shoot positioning had the highest total leaf area (LA) and pruning weight. Despite very comparable crop levels among trellises, quality decreased considerably in the bilateral free cordon (BFC) vines with respect to the systems with upright shoot growth. BFC vines showed signi®cantly lower sugar concentration (8Brix), anthocyanins and phenols, and higher pH and K according to a pattern frequently associated with excessive within-canopy shading. Shading was aggravated in the BFC vines by canopy rotation, which probably resulted in an increase of LA density per volume unit. Moreover, the BFC canopies had more close-to-horizontal oriented leaves and from veraison onward, placed the most functional median and apical leaves in the lower or less illuminated portion of the canopy. These factors may have combined to diminish total vine photosynthesis in BFC-trained vines. The data also pointed out that the differences among trellises could not have been predicted simply on the basis of widely accepted indicators of crop load (e.g. the yield-to-pruning weight ratio) or canopy density (e.g. leaf area-to-canopy surface area (LA/SA)).