Electrochemical impedance spectroscopy of oxygen and hydrogen evolution on amorphous alloys in 1 M KOH

The mechanisms of oxygen and hydrogen evolution on amorphous alloys G 14 (Fe₆₀Co₂₀Si₁₀B₁₀) and G 16 (Co₅₀Ni₂₅Si₁₅B₁₀) in 1 M KOH at T = 298 K and 333 K were studied by electrochemical impedance spectroscopy (EIS). Comparative measurements were carried out on polycrystalline Pt electrodes. Impedance spectra in the frequency range 10^?3 Hz ≤ f ≤ 10⁴ Hz were analyzed to determine the kinetic behaviour of amorphous alloys by application of transfer function analysis, using non-linear fit routines. The EIS-data are interpreted in terms of consecutive reaction mechanisms for both oxygen and hydrogen evolution.     

Estimating time to contact and impact velocity when catching an accelerating object with the hand.

To catch a moving object with the hand requires precise coordination between visual information about the target's motion and the muscle activity necessary to prepare for the impact. A key question remains open as to if and how a human observer uses velocity and acceleration information when controlling muscles in anticipation of impact. Participants were asked to catch the moving end of a swinging counterweighted pendulum, and resulting muscle activities in the arm were measured. The authors also simulated muscle activities that would be produced according to different tuning strategies. By comparing data with simulations, the authors provide evidence that human observers use online information about velocity but not acceleration when preparing for impact. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measuring quality of life in after-care of tumor surgery. Methods, problems and applications

The present paper deals with the feasibility and applications of quality of life measurement in the routine of a tumor follow-up clinic. 61 patients filled out the EORTC-30 questionnaire plus additional scales. Filling out the questionnaire constituted no burden for patients. Patients' responses were computed in a way as to allow for graphically presenting individual QL-profiles, as well as to compare different groups of patients. Considerations concerning the role of QL-measurement in clinical practice, in medical decision making, and in future research endeavours were brought forward.     

Phase equilibria and thermodynamic properties of the Cu<Subscript>2</Subscript>O-CaO-Na<Subscript>2</Subscript>O system in equilibrium with copper

The liquidus surfaces of the Cu₂O-CaO, Cu₂O-Na₂O, and Cu₂O-CaO-Na₂O phase diagrams in equilibrium with metallic Cu were measured by thermal analysis at compositions varying from approximately 0 to 35 wt pct Na₂O and 0 to 15 wt pct CaO. Solubilities in the solid binary terminal solutions were also measured by wavelength dispersive X-ray spectrometer analysis. Copper oxide activities in binary liquid slags were determined from the measured oxygen content of the metallic copper equilibrated with the slags. The ternary system is a simple eutectic system. No ternary compounds were observed. The Cu₂O-CaO binary eutectic was measured at 1140 °C±10 °C at 10±1 wt pct CaO and the Cu₂O-Na₂O binary eutectic was measured at 803 °C±15 °C at 28±2 wt pct Na₂O. The liquid slag was thermodynamically modeled with the modified quasi-chemical model, while the solid Cu₂O-rich solution was treated as Henrian ideal. All data from the present work and from the literature (phase diagrams and activities) for the binary systems were evaluated simultaneously by least-squares optimization in order to obtain the best model parameters. With only these binary parameters, the calculated ternary liquidus surface is in very good agreement with the measurements. Finally, using the model, the liquidus projection of the Cu₂O-CaO-Na₂O system in equilibrium with Cu was calculated as well as the oxygen content of the equilibrated Cu as a function of slag composition.     

Creep behavior of TiAl alloys with enhanced high-temperature capability

For high-temperature applications, creep strength is of major concern, in addition to oxidation and corrosion resistance, and determines the application range of titanium aluminide alloys in competition with other structural materials. Thus, this work was aimed at identifying mechanisms of creep deformation and microstructural degradation and at developing alloying concepts with respect to an enhanced high-temperature capability. The analysis shows that dislocation climb controls deformation in the range of the intended operation temperatures. Further, complex processes of phase transformations, recrystallization, and microstructural coarsening were observed, which contribute to microstructural degradation and limit component life in long-term service. By alloying with high contents of Nb, both room- and high-temperature strength properties can be improved as Nb increases the activation energy of diffusion and increases the propensity for twinning at ambient temperature. For alloys with enhanced high-temperature capability, microalloying with carbon is also of particular use, because carbide precipitates effectively hinder dislocation motion and are thought to increase microstructural stability. This article is based on a presentation made in the symposium entitled “Fundamentals of Structural Intermetallics,” presented at the 2002 TMS Annual Meeting, February 21–27, 2002, in Seattle, Washington, under the auspices of the ASM and TMS Joint Committee on Mechanical Behavior of Materials.     

Experimental verification of three-dimensional simulations of LTO layer deposition on structures prepared by anisotropic wet etching of silicon

A simulator for the three-dimensional (3D) simulation of layer deposition has been developed. It allows the prediction of the shape of layers deposited on structured substrates. In this paper, the simulation of low-temperature oxide (LTO) deposition is described. Model parameters reported in the literature were used to simulate LTO deposition at different process conditions. To allow quantitative comparison between experimental data and simulations, specific well-defined pyramidal test structures, which have been generated by anisotropic wet etching of silicon with potassium hydroxide (KOH), were used. The profiles of the concave edges of the topography as observed in the experiments were compared to those predicted by the 3D simulations. Good agreement was observed. This shows that the simulator allows the prediction of the geometry of deposited LTO layers. After implementation and calibration of additional models, further deposition systems can be simulated.