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Micropitting is a form of surface contact fatigue encounteredin bearingsa nd gears, under lubricating conditions, which lead to their premature failure. All gears are susceptible to micropitting, including spur, helical and bevel. Micropitting can occur with all heatt reatmentsa ppliedt o gearsa nd with both, synthetica nd mineral lubricants. It can occur after a relatively short period of operation and, after a certain number of cycles,g earsn eedt o be replacedd ue to the increasedn oisea nd vibrations causedb y the deviations of the tooth profile. Continuing operation of affected gears can lead to a catastrophic type of failure (i. e., tooth breakage). These considerations explain the increasing current interest in micropitting. It has been reported that micropitting in bearings is associated with a specific microstructural transformation in steel, i. e. martensite decay. However, to the authoes knowledge, this transformation has not been reported in gears. In the present work, extensive metallurgical investigations have been carried out and they revealed that the same transformation occurs in gears. The aim of this project was to describe the mechanism of micropitting by taking into account the influence of several controlling factors such as, material, surface finish, lubricant, load, temperature,s peeda nd, slide-to-roll ratio. Their influence is assessed with a fractional factorial experimentadl esign.S everaln on-destructivete chniquesh ave been used in order to monitor the specimen condition during and after running, such as X-ray diffraction, optical profilometry, light microscopy. The mechanical properties of the products of martensite decay, known as dark etching regions, white etching bands and butterflies are highly relevant to the fatigue behaviour of the steel. Nanoindentation and AFM techniquesh aveb eenu sedt o determinet hesep roperties. A micropitting mechanism correlated with the mechanism of martensite decay in gears is suggestedb asedo n thesea nalyses.

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The Western Boreal Forest exhibits complex hydrogeology juxtaposed with rapid resource development. Predicting surface water chemistry to assess the influence of landuse and climate change is needed. The research purpose was to test if a global model (Gibbs), used to assess water chemistry relative to precipitation, geologic and evaporative processes can be applied to mid-continental locations; and test if regional to local scale controls of surface-groundwater interactions can be used to refine predictions where geologic processes dominate water chemistry. The global model applied to many ponds, but failed in dilute and saline ponds. Caution is necessary, as the model assumes chloride-dominated precipitation, and continental to regional scale groundwater systems influence water chemistry, independent of evaporative processes. Bedrock geology influenced ion composition, TDS and pH via mineral dissolution and scale of flow. Surficial geology influenced TDP, TDN, DOC, pH and TDS, and wetland connection influenced TDP, TDN and DOC via flowpath. To assess water chemistry and the influence of landuse and climate change, regional to local controls of surface-groundwater interactions prove valuable over the global assessment of chemistry in heterogeneous and complex landscapes. / Ecology

A common complication associated with medical implants is the infectious bio-film, which can cause chronic infection that is difficult to control. Grain boundaries (GBs) in materials of medical implants are often preferential locations for bacteria to congregate, which could be attributed to higher affinity of grain boundaries for bacterial bio-films. In this study, the molecular interaction of the Pseudomonas aeruginosa receptor binding domain, a self-folding domain of 17 amino acid residues derived for the PilA structural protein, which can represents properties of Pseudomonas aerginosa biofilm, with microcrystalline stainless steel surfaces was examined with atomic force microscopy (AFM) both at grain boundaries and within grains. Adherence of Pseudomonas aeruginosa biofilm to nanocrystallized stainless steel surface was also determined using AFM. Results indicate that adherence of biofilm adherence at grain boundaries of microcrystalline surface is 2-fold higher than that of inside grains. Nanocrytalline surface is more resistant to biofilm than the microcrystalline one due to the formation of a strong oxidation film after annealing and thermal oxidation process. Surface nanocrystallization for enhanced corrosion resistance of Ag-incorporated 304 stainless steel surface was also studied. It is demontstrated that nanocrystallization of the antibacterial agent-incorporated stainless steel surface also provides an effective approach to control the corrosion problem resulting from the typical galvanic effect of multiphase alloys.