European actions for High-Performance Computing: PRACE, DEISA and HPC-Europa

Between e-Infrastructures, ESFRI has identified in FP7 High- Performance Computing a strategic priority for Europe. In order to have the highest return from the associated massive economical and political commitment, HPC resources must be exploited at the highest level. Their access must be effective and capillary, their services must allow more and more people to use the resources, regardless their geographical location. Projects like PRACE, DEISA and HPC-Europa have been supported by the EU to cope with such issues providing the best solutions for the European research community

Carpal Tunnel Syndrome Associated with Bifid Median Nerve and Palmaris Profundus - Case Report and Literature Review

The anatomic variations of the median nerve and of the muscles of the wrist have been widely reported in literature. It is essential for the surgeon to be familiar with these variations in order to avoid accidental injury to the nerve during surgery. We report a rare case of bifid median nerve accompanied by an anomalous tendon of palmaris profundus discovered during the surgical release of carpal tunnel. The transverse carpal ligament was dissected and the anomalous tendon was left in situ because any direct compression over the median nerve was noticed intraoperatively. The patient was evaluated one year postoperatively clinically and radiologically (with MRI). At the follow up the resolution of symptoms was complete and the sleep disturbance was solved. The patient achieved a postoperative QuickDASH score of 9.1 and a Michigan Hand Questionnaire outcome score of 90 points

Role of the chemical homogenization on the microstructural and mechanical evolution of prolonged heat-treated laser powder bed fused Inconel 625

Ni-based superalloy components for high-temperature applications rely on the long term stability of the microstructure and mechanical properties at service temperatures. Nowadays, the production of such types of components is frequently performed via Additive Manufacturing (AM) technologies. Nevertheless, few studies are dedicated to understanding the behavior of AM Ni-based superalloys upon prolonged exposure to high temperatures. This work aims at studying the effect of prolonged thermal exposures on the microstructure and mechanical properties of Inconel 625 processed by laser powder bed fusion. Thermal exposures within the range of 600 °C and 900 °C for 200 h were performed on this material. The as-built and solution annealed Inconel 625 conditions were selected. The solution annealed state implies a complete chemical homogenization, typically recommended for working at high temperatures, whereas the initial as-built state is characterized by segregations and fine dendritic structures. Upon the studied prolonged thermal exposures, the peculiar as-built microstructure formed a higher quantity of phases with smaller dimensions with respect to the solution annealed condition under thermal exposures. The smaller phases of the as-built state resulted in similar mechanical properties evolution under different temperatures. Differently, the prolonged heat-treated solution annealed conditions exhibited more marked mechanical properties variations due to coarser phases

Net shape HIPping of a Ni-superalloy: A study of the influence of an as-leached surface on mechanical properties

Hot Isostatic Pressing (HIP) is a net-shape powder metallurgy technique where powders densification is achieved through the application of high temperature and pressure at the same time. Powders are allocated into a hollow steel mold called capsule or canister which gives the final shape to the particles. This technique is particularly useful for manufacturing complex components made of materials which are extremely difficult to process via forging or casting. Thus, HIP is particularly indicated to handle superalloy powders such as Astroloy, which is the object of the following study. One of the most attractive peculiarities of HIP is the low material waste obtained since the overstock is limited to the layers immediately beneath the steel capsule. At the end of the HIP cycle, the canister is typically removed using an acid leaching bath which is responsible for the alteration of the outermost layers of the final product. Only a little number of research papers deal with the optimization of the removal of these layers; Consequently, manufacturers often apply a very conservative approach by eliminating more material than is actually needed with a final machining procedure. This paper aims to optimize this procedure by systematically assessing the total thickness of the altered layer of material deriving from the HIPping and leaching process together. To achieve this goal, a set of samples were prepared by removing progressively thicker layers of material and then they were bend tested. Finally, the recorded mechanical properties were compared with those obtained with the samples machined from the core material. One of the main findings is that the removal of 500 μm of material is enough to recover mechanical properties which are comparable with those observed in samples coming from the core. More specifically, by eliminating the first 100 μm material, all the corroded layer is removed, which results in an overall increase of all the mechanical properties except for ductility. This property strongly depends on the number of prior particle boundaries arising from the HIPping process itself. Thus, the correct amount of overstock material must include both these layers

Starburst-induced gas-stars kinematic misalignment

A kinematic misalignment of the stellar and gas components is a phenomenon observed in a significant fraction of galaxies. However, the underlying physical mechanisms are not well understood. A commonly proposed scenario for the formation of a misaligned component requires any pre-existing gas disc to be removed, via fly-bys or ejective feedback from an active galactic nucleus. In this Letter, we study the evolution of a Milky Way mass galaxy in the FIREbox cosmological volume that displays a thin, counter-rotating gas disc with respect to its stellar component at low redshift. In contrast to scenarios involving gas ejection, we find that pre-existing gas is mainly removed via the conversion into stars in a central starburst, triggered by a merging satellite galaxy. The newly-accreted, counter-rotating gas eventually settles into a kinematically misaligned disc. About 4.4 (8 out of 182) of FIREbox galaxies with stellar masses larger than 5e9 Msun at z=0 exhibit gas-star kinematic misalignment. In all cases, we identify central starburst-driven depletion as the main reason for the removal of the pre-existing co-rotating gas component, with no need for feedback from, e.g., a central active black hole. However, during the starburst, the gas is funneled towards the central regions, likely enhancing black hole activity. By comparing the fraction of misaligned discs between FIREbox and other simulations and observations, we conclude that this channel might have a non-negligible role in inducing kinematic misalignment in galaxies.Comment: 9 pages; 3 figures; submitted to ApJ Letter

Effects of the solution and first aging treatment applied to as-built and post-HIP CM247 produced via Laser Powder Bed Fusion (LPBF)

In this work CM247LC, a low weldable Ni-Based alloy, was produced using selective laser melting (SLM). Despite the initial process parameter optimization, the low defect volume fraction was still uncompliant with manufacturing standards. This condition is principally caused by the high γ’ volume fraction which strongly affects the alloy weldability. Nonetheless, a crack free condition was eventually achieved applying a γ’-sub-solvus Hot Isostatic Pressing Cycle (HIP) which lowered the defects fraction down to 0.04%. The HIP cycle also demonstrated to play an important role in the stabilization of the microstructure, considerably limiting the carbides coarsening during the following heat treatment. Apart from the effectiveness of the healing process brought by HIP, the material microstructure still needs an optimization process which will be described along this paper. In fact, the Initial microstructure obtained after the printing process (the as-built condition) as well as the one obtained after HIP (post-HIP) won’t meet the desired requirements. Namely, the dendritic and γ’ free microstructure of the asbuilt material or the one with coarse and disordered particles obtained right after HIP, still need a tailored homogenization process. This paper will show how the combined effect of the solution and first aging treatment will profoundly alter the γ’ precipitation. More specifically, here, a new heat treatment recipe was developed to promote the precipitation of ordered cuboidal primary γ’ so as to improve creep and high temperature fatigue resistance. Moreover, the use of a γ’ super-solvus temperature allowed to achieve a γ’ volume fraction as high as 73% reducing its average size to 520 nm. At the same time, such heat treatment caused a profound alteration of the crystalline structures of the material promoting a general grain coarsening and the formation of equiaxial grain

Manufacturing of PAV-ONE, a Permeator against Vacuum Mock-Up with Niobium Membrane

The Permeator Against Vacuum (PAV) is one of the proposed technologies for the Tritium Extraction System of the WCLL BB (Water-Cooled Lithium-Lead Breeding Blanket) of the EU DEMO reactor. In this paper, the manufacturing of the first PAV mock-up with a niobium membrane with a cylindrical configuration is presented. This work aimed to demonstrate the possibility of manufacturing a relevant-size PAV to be later tested in the TRIEX-II facility. The adopted prototypical solutions are described in detail, starting with the methodology developed to join the Nb tubes with a 10CrMo9-10 (A182 F22) plate. Dedicated manufacturing and welding procedures, based on vacuum brazing with a nickel-based brazing alloy, were developed to solve the problem. This new kind of brazing was first analyzed to check the morphology of the joint and then tested to check its capability to withstand the TRIEX-II operative conditions. In parallel, the compatibility with a lithium-lead environment was analyzed by exposing samples of niobium and 10CrMo9-10 (A335 P22) to a flow of the eutectic alloy at 500 °C up to 4000 h. Finally, the PAV mock-up was installed in the TRIEX-II facility

Major vascular traumas to the neck, upper limbs, and chest: Clinical presentation, diagnostic approach, and management strategies

Major vascular traumas to the neck, upper limbs, and chest may arise from penetrating and/or blunt mechanisms, resulting in a range of clinical scenarios. Lesions to the carotid arteries may also lead to neurologic complications, such as stroke. The increasing use of invasive arterial access for diagnostic and/or interventional purposes has increased the rate of iatrogenic injuries, which usually occur in older and hospitalized patients. Bleeding control and restoration of perfusion represent the two main goals of treatment for vascular traumatic lesions. Open surgery still represents the gold standard for most lesions, although endovascular approaches have increasingly emerged as feasible and effective options, particularly for management of subclavian and aortic injuries. In addition to advanced imaging (including ultrasound, contrast-enhanced cross-sectional imaging, and arteriography) and life support measures, multidisciplinary care is required, particularly in the setting of concomitant injuries to the bones, soft tissues, or other vital organs. Modern vascular surgeons should be familiar with the whole armamentarium of open and endovascular techniques needed to manage major vascular traumas safely and promptly

A contribution to the knowledge of Quadraseta brasiliensis Goff and Gettinger, 1989 (Trombidiformes: Trombiculidae), with description of the deutonymph instar

In the Neotropical region the genus Quadraseta Brennan, 1970, includes 14 species, with ectoparasitic habits during the larval stage. Quadraseta brasiliensis Goff and Gettinger, 1989, was described from larvae collected on the rodent Hylaeamys megacephalus (Fisher), cited as Oryzomys capito (Olfers). According to these authors, the holotype was deposited in the Museu de Zoologia da Universidade de São Paulo and the paratypes were deposited in three other collections: Bernice Pauahi Bishop Museum, Sam Noble Oklahoma Museum of Natural History and United States National Museum of Natural History, however, no type specimens were found in any of these museums. Here we redescribe the larva, describe the deutonymph instar obtained from field-collected larvae, and report new hosts and localities for this species in Brazil. In addition we provide sequences of the 18S ribosomal RNA gene for this species