Tribological performance of sulfonamide derivatives as lubricating oil additives in the diester

The load‐carrying capacity, anti‐wear and friction reduction properties of two sulfonamide derivatives added to a synthetic lubricant (diester) were evaluated using a four‐ball test machine. The results indicate that both additives possess good load‐carrying capacities and excellent anti‐wear and friction reduction properties. The surface topography of the rubbed surface was investigated by scanning electron microscopy, and the chemical nature of the anti‐wear films generated on the steel counter‐face was investigated by X‐ray photoelectron spectroscopy. Surface analysis results show that a stable lubricating film consisting of the reaction layer and adsorption layer was formed on the worn surface. Copyright © 2006 John Wiley & Sons, Ltd.     

Quantitative x‐ray microanalysis of model biological samples in the SEM using remote standards and the XPP analytical model

It is shown that accurate x‐ray microanalysis of frozen‐hydrated and dry organic compounds, such as model biological samples, is possible with a silicon drift detector in combination with XPP (exponential model of Pouchou and Pichoir matrix correction) software using ‘remote standards’. This type of analysis is also referred to as ‘standardless analysis’. Analyses from selected areas or elemental images (maps) were identical. Improvements in x‐ray microanalytical hardware and software, together with developments in cryotechniques, have made the quantitative analysis of cryoplaned frozen‐hydrated biological samples in the scanning electron microscope a much simpler procedure. The increased effectiveness of pulse pile‐up rejection renders the analysis of Na, with ultrathin window detectors, in the presence of very high concentrations of O, from ice, more accurate. The accurate analysis of Ca (2 mmol kg^?1) in the presence of high concentrations of K is possible. Careful sublimation of surface frost from frozen‐hydrated samples resulted in a small increase in analysed elemental concentrations. A more prolonged sublimation from the same resurfaced sample and other similar samples resulted in higher element concentrations.