Surface modification of Ti-6Al-4V powder during recycling in EBM process

Electron beam melting is an additive manufacturing technology in vacuum that suits Ti-6Al-4V parts, which has a high affinity with oxygen. Since the high cost of the feedstock powder, the un-melted powder is often recycled in the subsequent process. In this study, the influence of powder reuse on the surface characteristics of Ti-6Al-4V powder is examined using a variety of technology including scanning electron microscopy, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The modification of surface morphology and chemistry either generally or locally are revealed and discussed, which helps the creation of powder recycling strategy. Compared with fresh virgin powder, “worn” and rougher powder particles are observed after recycling. Meanwhile, the average oxide thickness is slightly increased, and less Al enrichment was found at the surface. Locally varied chemistry/oxide thickness on different powder particles or different location on the same particle is observed.     

Kinetic evaluation of sorption and desorption

Sorption is often quantified by a distribution coefficient, K _d , which is the equilibrium ratio between species sorbed to the rock and species in solution. Traditionally K _d -values are determined in batch experiments from equilibrium concentrations.     

Hydrogen oxidation reaction on thin platinum electrodes in the polymer electrolyte fuel cell

A method for measuring the kinetics of the hydrogen oxidation reaction (HOR) in a fuel cell under enhanced mass transport conditions is presented. The measured limiting current density was roughly 1600 mA cm_Pt^? 2, corresponding to a rate constant of the forward reaction in the Tafel step of 0.14 mol m^? 2 s^? 1 at 80 °C and 90% RH. The exchange current density for the HOR was determined using the slope at low overvoltages and was found to be 770 mA cm_Pt^? 2. The high values for the limiting and exchange current densities suggest that the Pt loading in the anode catalyst can be reduced further without imposing measurable voltage loss.     

Rapid affinity purification of erythropoietin from biological samples using disposable monoliths

Identification of post-translational modifications of proteins in biological samples often requires access to preanalytical purification and concentration methods. In the purification step high or low molecular weight substances can be removed by size exclusion filters, and high abundant proteins can be removed, or low abundant proteins can be enriched, by specific capturing tools. In this paper is described the experience and results obtained with a recently emerged and easy-to-use affinity purification kit for enrichment of the low amounts of EPO found in urine and plasma specimens. The kit can be used as a pre-step in the EPO doping control procedure, as an alternative to the commonly used ultrafiltration, for detecting aberrantly glycosylated isoforms. The commercially available affinity purification kit contains small disposable anti-EPO monolith columns (6 μL volume, Ø7 mm, length 0.15 mm) together with all required buffers. A 24-channel vacuum manifold was used for simultaneous processing of samples. The column concentrated EPO from 20 mL urine down to 55 μL eluate with a concentration factor of 240 times, while roughly 99.7% of non-relevant urine proteins were removed. The recoveries of Neorecormon (epoetin beta), and the EPO analogues Aranesp and Mircera applied to buffer were high, 76%, 67% and 57%, respectively. The recovery of endogenous EPO from human urine was 65%. High recoveries were also obtained when purifying human, mouse and equine EPO from serum, and human EPO from cerebrospinal fluid. Evaluation with the accredited EPO doping control method based on isoelectric focusing (IEF) showed that the affinity purification procedure did not change the isoform distribution for rhEPO, Aranesp, Mircera or endogenous EPO. The kit should be particularly useful for applications in which it is essential to avoid carry-over effects, a problem commonly encountered with conventional particle-based affinity columns. The encouraging results with EPO propose that similar affinity monoliths, with the appropriate antibodies, should constitute useful tools for general applications in sample preparation, not only for doping control of EPO and other hormones such as growth hormone and insulin but also for the study of post-translational modifications of other low abundance proteins in biological and clinical research, and for sample preparation prior to in vitro diagnostics.     

The role of annoyance in the relation between transportation noise and children's health and cognition

On the basis of this study it cannot be ruled out that the appraisal of the noise affects the association between air and road traffic noise exposure and children's health and cognition. However, the conclusion is limited due to the relatively small group of annoyed children, which may have influenced our group comparisons. Furthermore, the observed relation between annoyance and perceived health is possibly biased due to the fact that both were measured within the same questionnaire. These are the main conclusions of a cross-sectional multi-center study carried out among 2,844 schoolchildren (age 9-11 years) attending 89 primary schools around three European airports. The aim was to investigate how annoyance affects the relation between air and road traffic noise exposure and children's health and cognition. Different, sometimes competing, working mechanisms of how noise affects children's health are suggested. Some effects are supposed to be precipitated through (chronic) stress, while others may arise directly. There is still no theory that can adequately account for the circumstances in which noise will affect cognitive performance.     

Well-Posedness, Instabilities, and Bifurcation Results for the Flow in a Rotating Hele�CShaw Cell

We study the radial movement of an incompressible fluid located in a Hele–Shaw cell rotating at a constant angular velocity in the horizontal plane. Within an analytic framework, local existence and uniqueness of solutions is proved, and it is shown that the unique rotationally invariant equilibrium of the flow is unstable. There are, however, other time-independent solutions: using surface tension as a bifurcation parameter we establish the existence of global bifurcation branches consisting of stationary fingering patterns. The same results can be obtained by fixing the surface tension while varying the angular velocity. Finally, it is shown that the equilibria on a global bifurcation branch converge to a circle as the surface tension tends to infinity, provided they stay suitably bounded.     

A self-polishing platinum ring voltammetric sensor and its application to complex media

A self-polishing voltammetric sensor was recently developed and has been applied to samples of urea, milk and sewage water. The polishing device continuously grinds a platinum ring electrode, offering a reproducible and clean electrode surface. Principal component analysis (PCA) and partial least squares (PLS) techniques were applied to interpret the data and to build prediction models. In an evaluation of samples with different urea concentrations, the grinding step allows for repeatable measurements, similar to those after electrochemical cleaning. Furthermore, for the determination of sewage water concentrations in drinking water and for the evaluation of different fat contents in milk samples, the polishing eliminates sensor drift produced by electrode fouling. The results show that the application of a self-polishing unit offers a promising tool for electrochemical studies of difficult analytes and complex media.     

Steady Water Waves with Multiple Critical Layers: Interior Dynamics

We study small-amplitude steady water waves with multiple critical layers. Those are rotational two-dimensional gravity-waves propagating over a perfect fluid of finite depth. It is found that arbitrarily many critical layers with cat’s-eye vortices are possible, with different structure at different levels within the fluid. The corresponding vorticity depends linearly on the stream function.     

Synthesis,Evaluation and Proposed Binding Pose of Substituted Spiro-Oxindole Dihydroquinazolinones as IRAP Inhibitors

Insulin-regulated aminopeptidase (IRAP) is a new potential macromolecular target for drugs aimed for treatment of cognitive disorders. Inhibition of IRAP by angiotensin IV (Ang IV) improves the memory and learning in rats. The majority of the known IRAP inhibitors are peptidic in character and suffer from poor pharmacokinetic properties. Herein, we present a series of small non-peptide IRAP inhibitors derived from a spiro-oxindole dihydroquinazolinone screening hit (pIC₅₀ 5.8). The compounds were synthesized either by a simple microwave (MW)-promoted three-component reaction, or by a two-step one-pot procedure. For decoration of the oxindole ring system, rapid MW-assisted Suzuki-Miyaura cross-couplings (1 min) were performed. A small improvement of potency (pIC₅₀ 6.6 for the most potent compound) and an increased solubility could be achieved. As deduced from computational modelling and MD simulations it is proposed that the S-configuration of the spiro-oxindole dihydroquinazolinones accounts for the inhibition of IRAP.