Characterisation of microstructure, defect and high-cycle-fatigue behaviour in a stainless steel joint processed by brazing

We report the characterisation of microstructures and high-cycle-fatigue (HCF) properties of Type 304 stainless steel joints processed by brazing. Pure copper was applied as the filler metal for brazing at 1120 °C. A two-phase microstructure was obtained within the joint region: the star-shaped precipitates and copper matrix. The precipitates with an average size of 0.43 μm were rich in iron and chromium. A fixed orientation relationship was found between the precipitates and copper matrix. The joint exhibited much higher tensile strength and HCF life when compared to pure copper. The strength enhancement can be attributed to the presence of precipitates. Furthermore, the effect of joint interface roughness as well as defects was critically investigated. The joint interface roughness showed little influence on the HCF lives. Post-examinations revealed that fatigue crack initiation and propagation occurred entirely within the joint region, hence being consistent with the similar HCF lives regardless of the pre-defined interface roughness conditions. In addition, it was found that the HCF lives decreased exponentially with the increase of initial defect area. Fractography analysis revealed that fatigue striation spacings near the crack initiation zone increased with the increase of defect area, suggesting that the larger defects result in higher crack growth rate, hence shorten the overall fatigue life.</div

Effective use of Pupil Premium Plus to improve educational outcomes for looked after children

This publication reports on research funded by the National Association of Virtual School Heads and presents insights into the use of Pupil Premium Plus (PP+) to support educational outcomes for looked after children. Using data generated from Virtual School Heads, Designated Teachers and other stakeholder professionals, supported by available academic and policy texts, these insights together with emerging evidence of gaps in guidance and support inform a set of recommendations for stakeholders to consider to support educational outcomes for looked after children; specifically relating to: 1) The guidance and support available for effective use of PP+; 2) How PP+ is used and allocated; and 3) How impact of PP+-funded interventions is evidenced

Oxygen diffusion in Sr_0.75Y_0.25CoO_2.625: a molecular dynamics study

Oxygen diffusion in Sr0.75Y0.25CoO2.625 is investigated using molecular dynamics simulations in conjunction with an established set of Born model potentials. We predict an activation energy of diffusion for 1.56 eV in the temperature range of 1000-1400 K. We observe extensive disordering of the oxygen ions over a subset of lattice sites. Furthermore, oxygen ion diffusion both in the a-b plane and along the c axis requires the same set of rate-limiting ion hops. It is predicted that oxygen transport in Sr0.75Y0.25CoO2.625 is therefore isotropic

Irrigação por inundação intermitente para culturas em rotação ao arroz em áreas de várzea do Rio Grande do Sul.

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Drenagem superficial para diversificação do uso de solos de várzea do Rio Grande do Sul.

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Residual stresses in amorphous alumina films synthesized by ion beam assisted deposition

A set of experiments was conducted to determine the origin of residual stresses in amorphous Al2O3 films formed by ion beam assisted deposition. Samples were deposited during bombardment by Ne, Ar, or Kr over a narrow range of energies, E, and a wide range of ion‐to‐atom arrival rate ratios, R. Films were characterized in terms of composition, thickness, density, crystallinity, microstructure, and residual stress. Film composition was independent of ion beam parameters and residual stress was independent of thickness over the range 200–1200 nm. Stress varied strongly with ion beam parameters and gas content. Residual stress and gas content saturated at a normalized energy of ∼20 eV/atom or an R of ∼0.05. Where residual stress varied linearly with RE1/2, results are consistent with an atom peening model, but saturation at high R or RE1/2 is inconsistent with such a model. Stress due to gas pressure in existing voids explains neither the functional dependence on gas content nor the magnitude of the observed stress. A probable explanation for the behavior of stress is gas incorporation into the matrix, where the amount of incorporated gas is controlled by trapping. © 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70865/2/JAPIAU-77-7-3029-1.pd

Molecular markers for grape characterization

Research NoteFive cultivars and 9 Pinot noir clones were used to test the usefulness of RFLP and RAPD markers and determine whether clonal selections could be differentiated

A newly discovered antler flint-knapping hammer and the question of their rarity in the Palaeolithic archaeological record: Reality or bias?

The use of soft (bone, antler, tooth and wood) hammers and retouchers is a key innovation in early stone tool technology, first appearing in the archaeological record with Lower Palaeolithic handaxe industries (e.g. Boxgrove, UK ~ 500 kya). Although organic knapping tools were undoubtedly a component of early human toolkits and are essential, for example, for the manufacture of finely-flaked handaxes, Mousterian scrapers and Upper Palaeolithic blades tools, such archaeological finds are exceptionally rare. In this study, we present qualitative and quantitative analyses (focus variation optical microscope, scanning electron microscope, micro-CT scanning and energy dispersive X-ray spectroscopy), to characterise use-damage on an antler base from Laugerie-Haute West (France). This specimen was originally identified as a waste-product from splinter manufacture, and the use-damage appears to have been missed. The new analysis shows that prior to being used as a flint-knapping percussor, the red deer antler had been further modified to reduce the length of its beam and to remove the tines. Although minimally used, characteristic use-damage includes attrition (pits and scores), compression of the antler matrix and flint chips embedded within some of the percussion features on the base of the burr. An AMS radiocarbon date of 12385 ± 55 BP (12647 ± 335 BC calibrated) confirms a Magdelanian context for the hammer. The fact that the Laugerie Haute knapping hammer went unrecognised in a well-studied and accessible collection for almost 200 years since its discovery, suggests that antler hammers may be more common than generally assumed. Only further re-examination of prehistoric antlers in museum collections will confirm whether the apparent rarity of antler hammers during the Lower and Middle Palaeolithic is real phenomenon or the result of analytical biases

The evaluation of Eudragit microcapsules manufactured by solvent evaporation using USP Apparatus 1

The objectives of this study were to prepare microcapsules containing verapamil and propranolol and to evaluate the kinetics and mechanism of drug release from the microcapsules using USP Apparatus 1. The effects of polymer concentration and polymer type on the cumulative amount of drug released were evaluated. The microcapsules were manufactured using Eudragit RS and RL polymers by solvent evaporation with the ultimate aim of prolonging drug release. Twenty-four formulations were prepared using different drug/polymer ratios. The effects of polymer type and polymer/drug ratios on the size, flow properties, surface morphology, and the release characteristics of the microcapsules were examined. The effects of drug inclusion methods on drug loading, encapsulation efficiency, and release properties of the complex microcapsules were also investigated. The formulations containing drug/polymer ratio 1:4 (w/w) were the most appropriate with respect to encapsulation efficiency (70%), flow properties (HR = 1.2), drug loading (15–20%), and drug release characteristics, in all cases. The release kinetics from the different formulations followed mainly a diffusion-controlled mechanism

Potencial de produção do híbrido de milho BRS 1001, em solos hidromórficos do Rio Grande do Sul.

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