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Transport Properties and Processes
Published in S. L. Soo, Particulates and Continuum, 2018
Erosion and attrition. A mode of mass transfer by particle-wall interaction is erosion of the wall or attrition of the particles depending on their properties and the dynamic of impact. The properties include hardness, yield strength, and surface roughness of each. The dynamics of impact are related to the kinetic energy of the particles, angle of impact, and friction coefficient of the surfaces. Attrition is usually a short term concern of the condition of the particles after handling while erosion is a cumulative phenomenon relating to the maintenance and replacement cost of equipment. Erosion is a major concern of, for instance, a coal handling system. Attrition, however, is a major concern in grain handling.
Types of Surface Damage and Wear
Published in J. Blau Peter, Tribosystem Analysis: A Practical Approach to the Diagnosis of Wear Problems, 2017
The study of tribocorrosion has seen a growing interest in recent years with the publication of several books [60,61] and the introduction of a new journal (Journal of Bio- and Tribo-Corrosion, Springer Publications). Dental research has used the term tribochemical wear as a synonym for “dental erosion,” emphasizing the interplay of erosion, 3-body abrasion, and attrition in tooth wear. A review of methods to apply such combinations was published by Lambrechts et al. [62]. These authors point out that the apparati used to simulate the tooth/tooth, tooth/ restorative, and restorative/restorative tribosystems have taken a variety of forms, some of which simulate multiple forms of wear, and some, more simple geometries and motions.
Natural aggregate sources and production
Published in Mark Alexander, Sidney Mindess, Aggregates in Concrete, 2005
Mark Alexander, Sidney Mindess
a Physico/mechanical destructive processes such as freezing and thawing, heating and cooling, and mechanical erosion and attrition. Tectonic stresses and earth movements can cause fracturing and jointing of rock masses, which may influence quarrying and crushing. b Hydrochemically destructive processes such as wetting and drying, oxidation and hydration, leaching due to percolating waters, and direct chemical attack from groundwaters containing organic or inorganic compounds. Examples are conversion of feldspars to clay minerals, and dissolution of limestone and dolomite by acidic groundwaters and acid rain.
Clinical findings and self-reported oral health status of biathletes and cross-country skiers in the preseason – a cohort study with a control group
Published in Research in Sports Medicine, 2022
Cordula Leonie Merle, Theresa Rott, Nadia Challakh, Gerhard Schmalz, Tanja Kottmann, Tom Kastner, Katharina Blume, Bernd Wolfarth, Rainer Haak, Dirk Ziebolz, Jan Wüstenfeld
Dental Findings: Decayed (D: reasonably suspected or clearly visible cavity reaching the dentine layer), missing (M: probably due to caries, not because of trauma, agenesis or orthodontic extraction) and filled (F: dental restorations as fillings or crowns) teeth (-T) were quantified using the DMF-T (Supplementary Tab. 1). Basic erosive wear examination (BEWE) recorded non-carious tooth wear due to erosion, abrasion and/or attrition (Supplementary Tab. 1). Maximum tooth wear per sextant was scored as 0 (no tooth wear), 1 (initial loss of surface texture), 2 (marked defect) and 3 (≥50% of the area). Severity was classified by the cumulative BEWE score (BEWE sum) of all sextants as none (0–2), low (3–8), medium (9–13) or high (≥14). Third molars were only included in the examinations if they occupied a more anterior position. The status of the wisdom teeth was clinically assessed per subject (having/not having partially erupted wisdom teeth).
The Dunedin Multidisciplinary Health and Development Study: oral health findings and their implications
Published in Journal of the Royal Society of New Zealand, 2020
Chuen Lin Hong, Jonathan M. Broadbent, W. Murray Thomson, Richie Poulton
Current dental-related Dunedin Study research includes detailed characterisation of dental plaque and with advances in bacterial genetics, the study has begun to investigate the bacteria collected from different intra-oral sites from age 32. The study can provide insights into the composition of the human plaque, the ecological role that species have in modulating human plaque, and provide a glimpse of its effect in the progression from healthy to periodontitis. Further work is being conducted on the microbiology of dental plaque and how it may affect caries risk and periodontal disease. Digital 3D scans of the Study members’ dentitions at age 45 years enable investigation of occlusal features and temporomandibular joint dysfunction, along with dental aesthetics. In future, the digital scans will provide insights into changes to the ageing dentition including crowding and attrition (tooth wear).
Experimental hydrodynamic and bed characteristics of co-current gas-liquid-solid three phase semifluidization with liquid as the continuous phase
Published in Particulate Science and Technology, 2020
Subrata Biswas, Tushar Kanti Sen, Bhim Charan Meikap
The semifluidization phenomenon first introduced by Fan et al. in 1959 to investigate the mass transfer between solid-liquid in a semifluidized bed system (Fan, Yang, and Wen 1959). In a semifluidized bed reactor, the formation of both the fluidized bed and packed bed takes place. Therefore, a semifluidized bed has the benefit of both the fluidized bed as well as the packed bed (Fan and Wen 1961). The three-phase gas-liquid-solid semifluidized bed can be described as a system in which a bed of solid material is partially fixed across the top restraining plate and the rest of the bed materials are suspended or fluidized with the upward liquid/gas flow. Such a system can create substantial intimate contact between the gas-liquid and solid particles and provide significant advantages for the physical-chemical and biological processing operation. The difficulties of fluidized beds, such as solid back-mixing, particle attrition and erosion of surfaces, and those of packed bed system, like non-uniform bed temperatures, solid’s isolation, and channeling, are reduced in a semifluidized bed system (Schubert and Larachi 2009). There are basically two models of gas-liquid-solid semifluidized bed operation that has been reported so far in the literature as co-current and counter-current mode operation. Among them, the co-current three-phase system is most prominent with upward gas and liquid flow system. However, this type of three-phase semifluidized bed may offer high-pressure drop due to the presence of a packed section at the top and results in higher gas hold up and the higher interfacial area in the bed (Jena, Roy, and Meikap 2009).