Surface-Enhanced Raman Spectroscopy of Tribochemically Formed Boundary Films of Refined and Unrefined Canola Oils

The paper reports the investigation of tribochemically formed boundary films of canola oils usingsurface-enhanced Raman spectroscopy. This is the first time that metallic surfaces lubricated by plant oils have been studied using this technique. The results of this work provided strong evidence that fatty acids were liberated from the triglyceride structure during sliding to form a fatty acid soap layer on the silver surface. The study also revealed that the fatty acid chains of the unrefined canola oil were more disordered and most likely in a gauche conformation, while that of the refined canola oil weretightly packed and oriented perpendicular to the surface. It is believed that the greater presence of polar minor components in the unrefined oil, such as phospholipids, interfered with the ability of free fatty acids to form a tightly packed monolayer on the silver surface

Engineering tribology

As with the previous edition, the third edition of Engineering Tribology provides a thorough understanding of friction and wear using technologies such as lubrication and special materials. Tribology is a complex topic with its own terminology and specialized concepts, yet is vitally important throughout all engineering disciplines, including mechanical design, aerodynamics, fluid dynamics and biomedical engineering. This edition includes updated material on the hydrodynamic aspects of tribology as well as new advances in the field of biotribology, with a focus throughout on the engineering a

Fractal Analysis of Surface Topography by the Directional Blanket Covering Method

A new method, called directional blanket covering (DBC) method, was developed in this study to quantify the roughness of surfaces in a multi-scale manner. Unlike the ASME and ISO standards on surface texture that provide a single fractal dimension (FD, roughness measure) for the entire surface, the new method calculates FDs at individual scales and directions. Also, it is invariant to affine transformations of grey-scale levels of surface image. The method calculates FDs using slopes of lines fitted to data point subsets of log-log plots of relative surface areas (differences between surface volumes) against scales of calculation. The scales are ranking from an instrument spatial resolution to 1/10 of the image shortest size. Each FD calculated has its individual scale corresponding to the centre of the subset. A flat surface criterion based on the relative areas was proposed. Using the criterion, a flat surface was identified in computer images of circle, sine wave and fractal surface. The DBC method was applied to computer-generated fractal surfaces with increasing roughness and microscope images of isotropic (sandblasted) and anisotropic (ground) surfaces of steel plates. Results showed that the method is accurate in the measurement of surface roughness and the detection of minute changes in roughness of the steel surfaces over a wide range of scales

Novel Directional Blanket Covering Method for Surface Curvature Analysis at Different Scales and Directions

The curvature of surface topography is quantified in this study using a newly developed directional blanket covering curvature (DBCC) method. The novel method addresses a long-standing problem of a measurement of a local surface curvature at individual scales and directions. The curvature data are obtained using the first and second derivations of the quadratic polynomial fitted to the local surface profile extracted from the surface height image data at individual scale and direction. The range of scales is set between an instrument spatial resolution and 1/10 of the image shortest size. Using the surface curvature data, three parameters, i.e. curvature, peak and valley dimensions, are calculated as the slopes of lines fitted to data point subsets of log–log plots of surface areas (differences between dilated and eroded surface curvature matrices) against scales of calculation. The dimensions quantify directional changes in the overall curvature and the curvature of peaks and valleys at individual scales. The scale corresponds to the centre of the subset. A flat surface criterion based on the surface areas was also proposed. Using the criterion, a flat surface was identified in computer images of dome, corrugated plate and fractal surface. The DBCC method was applied to computer-generated fractal surfaces with increasing curvature complexity, sine waves with decreasing curvature at single scale and microscope images of isotropic (sandblasted) and anisotropic (ground) surfaces of titanium plates. Results showed that the method is accurate in the measurement of surface curvature and the detection of minute changes occurring in the curvature of real surfaces over a wide range of scales

Directional fractal signature analysis of self-structured surface textures

Currently available directional fractal signature (DFS) methods are not suited for self-structured surface textures since they base on the assumption of Brownian fractal or they do not use the entire image data in calculation. To address these difficulties, two new DFS methods were developed in this study, i.e., an augmented blanket with rotating grid (ABRG) method and a blanket with shearing image (BSI) method. The performance of these methods in measuring surface roughness and directionality, the capacity for quantifying multi-patterned textures, and the ability to detect differences between textures of self-structured surfaces were evaluated. The methods were compared against a blanket with rotating grid (BRG) method. Computer-generated images of self-structured surface textures with different roughness, directions and patterns, and atomic force microscope images of real self-structured surfaces were used. The computer texture images were generated using a specially developed motif-based texture generator. Results obtained showed that the ABRG method is more accurate and reliable than the BRG and BSI methods

Knee strength and knee adduction moments following arthroscopic partial meniscectomy

Purpose: This study investigated the relationship between muscular strength about the knee and knee joint moments during gait in patients who had undergone arthroscopic partial meniscectomy (APM) Methods: One hundred and two APM patients and 42 age-matched nonoperated controls underwent strength testing and three-dimensional gait analysis. Patients were divided into weak and normal subgroups and compared with controls for spatiotemporal, kinematic, and kinetic gait parameters. Results: Spatiotemporal parameters, kinematics, and sagittal plane kinetics were similar between APM patients and controls. The APM group displayed weaker concentric knee extension and flexion strength compared with controls. The weak APM subgroup had an increased average and peak knee adduction moments over stance compared with the APM subgroup with normal strength levels and controls. The normal strength APM subgroup had a larger peak knee adduction moment in early stance compared with controls. Conclusion: Achieving normal lower limb muscle strength following APM appears important to resume normal frontal plane loading of the knee while walking