Atmospheric pressure plasma jet for surface texturing of C/SiC

C/SiC composites are materials to be used in harsh environments overcoming the limits imposed by the intrinsic brittleness of their ceramic constituents while providing both high mechanical performances at high-temperature temperatures and low weight. In order to manufacture the final component, joining C/SiC, to itself or to other materials, is often necessary, and it is critical to maximize the strength of the joints (similar or dissimilar) in order to meet reliability criteria. In the present work, a pre-joining treatment based on an atmospheric pressure plasma jet (APPJ) was proposed to introduce a brush-like texture on the surface via the selective removal of carbon fibers. The investigation of treated surfaces via electron microscopy and confocal 3D-profilometry confirmed that the treatment was effective in introducing a brush-like texture and in increasing the available contact area. Wettability test and inspection of cross-section of CB4 wetted samples were then carried out. The latter confirmed the formation of anchoring points given by the brush-like texture. Finally, the effectiveness of the treatment in improving the joint strength was assessed by comparing the apparent shear strength of CB4 brazed composites, with and without the APPJ pre-treatment. The joints with plasma pre-treated C/SiC showed a shear strength of about 66 MPa, 44% more than the strength of joints produced with untreated C/SiC

Torsion Test vs. Other Methods to Obtain the Shear Strength of Elastic-Plastic Adhesives

Nowadays adhesive joints are more and more used; therefore, a precise and reliable shear strength measurement of these joints is necessary to design and predict a final components’ performance. This work aimed to assess the shear strength value of adhesively joined ceramics (SiC, Si3N4) and steel in the case of an elasto‐plastic (ductile) joining material (Loctite EA 9321 AERO) by an experimental campaign and associated analytical modelling. The joined samples were tested using a single lap offset test in compression (SLO), an asymmetrical 4‐point bending test (A4PB, ASTM C1469), and by torsion on fully joined hourglass shaped samples (THG). A simple model based on the elastic‐plastic response in shear was proposed to fit the torque‐rotation curve measured in the torsion tests. The results showed that, with the adopted test methods and conditions, and by using the model, consistent values of shear strength could be obtained by torsion tests

Local lymph node involvement in pediatric renal cell carcinoma: A report from the Italian TREP project

Background. One of the most important adverse prognostic factors for adult renal cell carcinoma (RCC) is the retroperitoneal lymph node involvement. The aim of this article is to study the prognostic significance of local lymph node involvement in pediatric RCC and the role of retroperitoneal lymph node dissection (RLND) at diagnosis. Procedure. The series included 16 patients with RCC and lymph nodes involvement registered in the Italian Rare Tumors Pediatric Age (TREP) project, accounting for 26.2% of 61 pediatric RCC observed at AIEOP centers. Results. A radical nephrectomy was performed in all cases: at diagnosis in 12 cases, after preoperative chemotherapy (CT) in 4 cases. As a part of the same procedure 9 patients underwent RLND, and 7 received a more limited lymph nodes resection. Five (31.2%) developed disease recurrence 2-34 months after diagnosis (median, 6 months) plus 1 developed progression; 6 patients died, 1 of them from secondary leukemia. Among the nine patients receiving RLND, eight are alive and disease free. This compares with only one patient surviving among the seven receiving a more limited lymph nodes resection. The estimated 25-year PFS and OS rates for all patients were 61.4% (95% CI 33.2-80.5) and 50.8% (95% CI 16.5-77.5), respectively. Conclusions. Lymph node involvement is an unfavorable prognostic factor in children with RCC. RLND appears to be a critical factor to improve the outcome. However, when compared to similar adult patients, the outcome in children appears to be better, suggesting that pediatric RCC, or the host, may be critical differences. © 2008 Wiley-Liss, Inc

Analisi della evoluzione delle tecnologie hardware per il calcolo scientifico

Gli esperimenti della fisica HEP avranno bisogno, nel prossimo decennio, di strumenti di calcolo di enorme potenza, che le tecnologie attuali non potranno soddisfare. Questo lavoro è un'analisi dell'evoluzione delle tecnologie di CPU, di storage e di rete, volta a valutare alcuni degli indicatori (prestazioni, consumi) su cui poter basare la progettazione di un centro di calcolo valida per i prossimi 10 anni. Previsioni sull'evoluzione tecnologica di tale durata sono facilmente soggette ad errori di valutazione anche macroscopici: roadmap valide solo per tre-quattro anni, inaspettati balzi tecnologici, imprevedibili mutamenti di andamento del mercato, possono facilmente cambiare o anche ribaltare previsioni così a lungo protratte nel futuro, ed invalidare estrapolazioni per quanto accurate. Ciononostante, un'analisi della situazione e di quello che oggi può essere detto in relazione all'evoluzione di queste tecnologie è un punto di partenza senza il quale non sarebbe possibile fare alcun tipo di ipotesi

L'EREDITA' PEDAGOGICA DI DON MILANI (a cura di Dario De Salvo)

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XIPE: the X-ray Imaging Polarimetry Explorer

X-ray polarimetry, sometimes alone, and sometimes coupled to spectral and temporal variability measurements and to imaging, allows a wealth of physical phenomena in astrophysics to be studied. X-ray polarimetry investigates the acceleration process, for example, including those typical of magnetic reconnection in solar flares, but also emission in the strong magnetic fields of neutron stars and white dwarfs. It detects scattering in asymmetric structures such as accretion disks and columns, and in the so-called molecular torus and ionization cones. In addition, it allows fundamental physics in regimes of gravity and of magnetic field intensity not accessible to experiments on the Earth to be probed. Finally, models that describe fundamental interactions (e.g. quantum gravity and the extension of the Standard Model) can be tested. We describe in this paper the X-ray Imaging Polarimetry Explorer (XIPE), proposed in June 2012 to the first ESA call for a small mission with a launch in 2017 but not selected. XIPE is composed of two out of the three existing JET-X telescopes with two Gas Pixel Detectors (GPD) filled with a He-DME mixture at their focus and two additional GPDs filled with pressurized Ar-DME facing the sun. The Minimum Detectable Polarization is 14 % at 1 mCrab in 10E5 s (2-10 keV) and 0.6 % for an X10 class flare. The Half Energy Width, measured at PANTER X-ray test facility (MPE, Germany) with JET-X optics is 24 arcsec. XIPE takes advantage of a low-earth equatorial orbit with Malindi as down-link station and of a Mission Operation Center (MOC) at INPE (Brazil).Comment: 49 pages, 14 figures, 6 tables. Paper published in Experimental Astronomy http://link.springer.com/journal/1068

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson