Abrasive, definition

Table 26.7 gives a list of the boundary conditions which define a tire wear test simulation and in fact also an acmal road test. The road surface is the laboratory surface on which the abrasion data for the simulation were obtained. There is as yet no definition of a road surface and even if there were one, it would be of httle use since road surface structures change frequently along the road surface as pointed out earlier. 

From these definitions, it can be seen that the more specific meaning of abrasion is wear by the cutting action of hard asperities. The common practice in the rubber industry of using abrasion as a general term for wear probably results from the fact that most wear tests for rubbers use the action of sharp asperities, for example abrasive paper, to produce wear. 

A definite shortcoming of Scott s method is that it fails to fix an exact quantitative relation between abrasiveness and hardness. Consequently, it can only be used for comparison, giving the strength of a material under operating conditions. 

Innovators. Thinks in risky, unexpected ways. Little respect for past custom - seen as irrelevant. Trades off detail for over-view. Questions definition of problem. Often challenges the rules solves problems despite rule. Can appear insensitive, even abrasive, to group cohesion. Does things differently. Provides dynamics for radical change. 

The mechanism of fluorescein staining of ocular epithelia has been subject to some conjecture. In earlier work it was suggested that staining occurred due to accumulation in intraepithelial spaces rather than direct staining of the cells. However, it has become clear that fluorescein can directly stain diseased human corneal cells and rabbit epithelial cells. Moreover, the hyperfluorescence that probably represents micropunctate clinical staining is likely due to optimum dye concentration and fluorescence within the cell rather than simple pooling. Cellular hyperfluorescence occurred from both mechanical abrasion and chemically induced toxicity, conditions that presumably promote an intracellular concentration that allows definitive clinical visualization. An issue that has received some attention is whether repeated... 

The term tooth wear is commonly used to describe the loss of tooth hard tissue due to non-carious causes [1], This encompasses a variety of both chemical and mechanical causes of both intrinsic and extrinsic origin. The term tooth wear is preferred over some of the more precise definitions of individual hard tissue loss mechanisms, because it acknowledges the fact that wear is usually a multifactorial process one mechanism may dominate, but the overall wear is commonly due to the interaction between two or more wear mechanisms. In dentistry, the terms erosion, abrasion, attrition and abfraction are widely used to describe particular mechanisms of hard tissue loss. 

The mechanisms of tooth wear fall into two distinct types those of chemical origin (e.g. erosion) and those of physical origin (e.g. abrasion, attrition). In any individual, both chemical and physical insults to the tooth hard tissue will be present in some form or other, so tooth wear is the combined effect of these insults. Despite the clear definition of a number of distinct tooth wear mechanisms, it is uncommon to find a single wear mechanism present in the... 

Abrasive protocols alter the reticular dermis and therefore cause a definitive and irreversible skin reaction. The results achieved in each session can therefore be considered definitive, and the rest period of 4-6 weeks is a minimum. 

Very painful abrasion is definitely too deep or the patient is squeamish. 

Data needed include expected variations in conditions costs of materials, labor, equipment, and utilities disposal limitations sources legal definitions and restrictions environmental impact measures and numerical values for the criteria. For all the species involved in the process, we need physical and thermodynamic data, and such reactivity and safety properties as flammability, corrosivity, abrasiveness, and propensity for dust explosions of solids, stability, environmental persistence and health indicators such as the LDjg, carcinogenicity, mutagenicity, and toxicity and those listed in Table 16.16. 

Plowing The OECD definition reads "plastic deformation of the softer component of a rubbing pair" [52], Presumably what is meant is displacement of material without separation, since the basic mechanism of abrasion is also plastic deformation. 

The conditions for conducting the abrasion are not yet standardized and vary from one supplier to another.6 The general approach used is to shake a weighed portion of carbon, e.g., 100 g, with 30 steel balls (recommended sizes range from i to f inch diameter) for a definite length of time, e.g., 30 minutes. 

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