The effect of tungsten additive on the surface characteristics of amorphous Ni-P alloy

The variation of surface compositions on amorphous Ni80.4W1.5P18.1 alloy by O-2 oxidation and H-2 reduction treatments have been studied by XPS, UPS and ISS. It shows that addition of tungsten in the amorphous Ni-P alloy leads to dramatic changes of the relating component distributions in the surface layers before and after these treatments. Oxidation of a Ni80.4W1.5P18.1 amorphous alloy in 1 bar of oxygen at 513 K caused a significant segregation of nickel in different oxide states at the surface. The subsequent reduction of the oxidized surface with I bar hydrogen at 553 K resulted in only a small portion of Ni and P being reduced into elemental states, while most of them was found to combine to form a kind of nickel phosphate compound. On the other hand, under the same conditions, the oxidation and reduction of a Ni80P20 alloy gave rise to metallic Ni and elemental P as the predominate species on the alloy surface. The addition of W in the amorphous alloy might act as nuclei for a favorable formation of the phosphate structure which was proposed to be an active species for hydrogen-relating catalytic reactions. (C) 1999 Elsevier Science B.V. All rights reserved.

Surface Perception from Local Analysis of Texture and Contour

The visual analysis of surface shape from texture and surface contour is treated within a computational framework. The aim of this study is to determine valid constraints that are sufficient to allow surface orientation and distance (up to a multiplicative constant) to be computed from the image of surface texture and of surface contours.

Characteristics of elution profile in radial chromatography under linear conditions

Based on the mass balance equations of solute transfer in the radial chromatographic column, the theoretical expression to describe the column efficiency and shape of elution profile is obtained under linear isotherm case. Moreover, the tendency for the variation of column efficiency and symmetry of peak profile is systematically discussed. The results showed that in radial chromatography the relationship between the column efficiency and volumetric flow rate is similar with that relationship in axial chromatography; relatively high column efficiency still can be obtained under high flow rate in radial chromatography. Accompanying the increase of retention factor of solutes and injection time, the column efficiency decreases monotonously. The effect of column diameter and column length on the column efficiency interfere with each other. It is more advantageous to increase the column efficiency by applying columns with larger column diameter and shorter column length. According to the discussion of the effect of diffusion on the column efficiency, radial chromatography is proved to be suitable for the separation of samples with relatively high diffusion coefficient, which predicts its obvious advantage in the preparative separation of samples such as proteins and DNA.

Changes in the mechanical characteristics of the knee musculature in professional female volleyball players

The technical efficiency in volleyball is closely related to the ability to perform displacements or jump (1). Therefore, it is necessary that precise, individualized, and localized evaluation of the muscles frequently involved in volleyball practice be studied (2,3). The aim of this study was to analyze the neuromuscular changes of the knee musculature in professional volleyball players using Tensiomyography (TMG) and jump tests.

Characteristics of preferred gait patterns: considerations for exercise prescription

Gait patterns have been widely studied in different fields of science for their particular characteristics. A dynamic approach of human locomotion considers walking and running as two stable behaviors adopted spontaneously under certain levels and natures of constraints. When no constraints are imposed, people naturally prefer to walk at the typical speed (i.e., around 4.5 km.h-1) that minimizes metabolic energy cost. The preferred walking speed (PWS) is also known to be an indicator of mobility and an important clinical factor in tracking impairements in motor behaviors. When constrained to move at higher speeds (e.g., being late), people naturally switch their preference to running for similar optimization reasons (e.g., physiological, biomechanical, perceptual, attentionnal costs). Indeed, the preferred transition speed (PTS) marks the natural seperation between walking and running and consistently falls within a speed range around 7.5 km.h-1. This chapter describes the constraint-dependant spontaneous organisation of the locomotor system, specifically on the walk-to-run speed continuum. We provide examples of the possibility of long-term adaptations of preferred behaviors to specific constraints such as factors related to traditional clothing or practice. We use knowledge from studies on preferred behaviors and on the relationship between affect and exercise adherence as a backdrop to prescribing a walk exercise program with an emphasis on populations with overweight or obesity.