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Bernstein Jonasson posted an update 8 days ago
Characteristics of a beam-shaping assembly that utilizes photo-neutrons from irradiation of a tungsten target by electrons from an accelerator were examined to produce a beam of neutrons suitable for boron neutron capture therapy. The epithermal neutron flux per kilowatt of electron-beam power almost increased to a maximum as the energy of the initial electrons was increased to 42.5 MeV, but the fast-neutron dose and the photon dose per epithermal neutron hardly changed on varying the energy of the initial electrons.This paper presents three new materials composed of TiXV0,035XCuX-1,035 (X = 2, 4 and 6%), is proposed as Linear Accelerator target. Its response to electron beam based on photoneutron production, is assessed by MC simulation and nuclear track-etch methodology. The outcome is compared to a tungsten target irradiated by energetic 16 MeV electron beam. Photoneutron yield, of two energy groups (thermal and epithermal) were determined via converter matter 10B (98%) and Cd-filter by PADC-track density comparison. The multi-metal Ti2V0,07Cu97.93 target related to therapy beam quality, resulted advantageous in comparison to that provided by W-target, commonly used in the LINAC.Vitreomacular traction (VMT) syndrome has only been surgically treated for a long time. Recently, enzymatic vitreolysis with ocriplasmin has emerged as a possible option to release VMT and, in some cases, close full thickness macular holes (FTMHs). Despite its clinical relevance, gathering information about the ocriplasmin-induced alterations of the Inner Limiting Membrane (ILM) of the retina in a clinical study is a complex task, mainly because of the inter-individual variability among patients. PMX-53 concentration To obtain more insights into the mechanism underlying the drug action, we studied in-vitro the mechanical and morphological changes of the ILM using Atomic Force Microscopy (AFM). To this aim, we measured the ILM average Young’s modulus (YM), hysteresis (H) and adhesion work (A) over time under ocriplasmin treatment. Our data unveil a time-dependent increase in the membrane YM of 19% of its initial value, along with changes in its adhesive and dissipative behavior. Such modifications well correlate with the morphological alterations detected in the AFM imaging mode. Taken all together, the results here presented provide more insights into the mechanism underlying the ocriplasmin action in-vivo, suggesting that it is only able to alter the top-most layer of the vitreal side of the membrane, not compromising the inner ILM structure.The biomechanics of bone-tooth and bone-implant interfaces affects the outcomes of several dental treatments, such as implant placement, because bone, tooth and periodontal ligament are living tissues that adapt to the changes in mechanical stimulations. In this work, mechanical testing coupled with micro-CT was performed on human cadaveric mandibular bone-tooth and bone-implant constructs. Using digital volume correlation, the 3D full-field strain in bone under implant loading and tooth loading was measured. Concurrently, bone morphology and bone-implant and bone-tooth contact were also measured through the analysis of micro-CT images. The results show that strain in bone increased when a tooth was replaced by a dental implant. Strain concentration was observed in peri-implant bone, as well as in the buccal bone plate, which is also the clinically-observed bone resorption area after implant placement. Decreasing implant stability measurements (resonance frequency analysis and torque test) indicated increased peri-implant strain, but their relationships may not be linear. Peri-implant bone strain linearly increased with decreasing bone-implant contact (BIC) ratio. It also linearly decreased with increasing bone-tooth/bone-implant contact ratio. The high strain in the buccal bone plate linearly increased with decreasing buccal bone plate thickness. The results of this study revealed 3D full-field strain in bone-tooth and bone-implant constructs, as well as their several morphological influential factors.Ti alloys, generally made via wrought metallurgy, are commonly used as biomedical materials. The manufacturing of such alloys via powder metallurgy offers the possibility to reduce the cost as well as to develop innovative compositions not otherwise achievable. The aim of this study is to understand the effect that the progressive addition of Al has on the physical and mechanical behaviour of the low-cost powder metallurgy Ti-5Fe alloy for structural biomedical implants. Specifically, Ti-5Fe-xAl (x = 1-6 w.%) alloys were developed combining blending elemental and cold pressing plus vacuum sintering to further limit the manufacturing costs as Al is lighter and cheaper than Ti. This investigation demonstrates that the amount of Al added significantly changes the thermodynamics of the sintering process and induces microstructural modifications such as grain refinement. These effects jointly with the Al solid solution strengthening leads to progressively stronger and harder (but less ductile) α+β Ti alloys characterised by the typical α+β lamellar microstructure with mechanical behaviour suitable for a variety of structural biomedical implants.The hierarchical architecture of the collagen fibril is well understood, involving non-integer staggering of collagen molecules which results in a 67 nm periodic molecular density variation termed D-banding. Other than this variation, collagen fibrils are considered to be homogeneous at the micro-scale and beyond. Interestingly, serial kink structures have been shown to form at discrete locations along the length of collagen fibrils from some mechanically overloaded tendons. The formation of these kinks at discrete locations along the length of fibrils (discrete plasticity) may indicate pre-existing structural variations at a length scale greater than that of the D-banding. Using a high velocity nanomechanical mapping technique, 25 tendon collagen fibrils, were mechanically and structurally mapped along 10 μm of their length in dehydrated and hydrated states with resolutions of 20 nm and 8 nm respectively. Analysis of the variation in hydrated indentation modulus along individual collagen fibrils revealed a micro-scale structural variation not observed in the hydrated or dehydrated structural maps.