[1] Abrasion by bed load is a ubiquitous and sometimes dominant erosional mechanism for fluvial incision into bedrock. Here we develop a model for bedrock abrasion by saltating bed load wherein the wear rate depends linearly on the flux of impact kinetic energy normal to the bed and on the fraction of the bed that is not armored by transient deposits of alluvium. We assume that the extent of al...

OBJECTIVE This in situ study aimed to analyse the impact of different tetrafluorides (TiF(4), ZrF(4) and HfF(4)) and AmF on erosion and erosion plus abrasion of enamel and dentin. DESIGN Ten volunteers took part in this crossover and double-blind study performed in 8 phases of each 3 days. In each phase, 2 bovine enamel and 2 dentin specimens were fixed in intraoral appliances. One enamel and...

Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remin...

The taphonomy of assemblages of disarticulated remains of marine vertebrates is not well studied. Examination of a Middle Pennsylvanian chondrichthyan assemblage from Kohl’s Ranch, Naco Formation, central Arizona, contributes to knowledge of such assemblages and reveals a complex taphonomic history. This vertebrate assemblage is restricted to two thin horizons associated with a concentration of...

The current work deals with the analysis of mechanisms involved during the machining process of titanium alloys. Two different materials were chosen for the study: Ti-6Al-4V and Ti-55531. The objective was to understand the effect of all cutting parameters on the tool wear behavior and stability of the cutting process. The investigations were focused on the mechanisms of the chip formation proc...

A commercially available poly(vinyl butyral) (PVB) coating was modified using a combination of 1–10wt.% bis(trimethoxysilylethyl)benzene and dibutyltin dilaurate as the hydrolysis catalyst. Results of attenuated total reflectance (ATR)–FTIR analysis indicated the modification resulted in a hybrid coating material containing silicate moieties covalently bonded to the PVB polymer chains. Gravimet...