Faulting, small particles

A more serious fault in White s derivation is the lack of appreciation of the stochastic nature of the charge acquisition process. For example, Eq. 12.12 indicates that for small particles and short charging times, fractions of charges are possible. This is clearly an impossibility. Thus results computed from these equations should be considered to represent average rather than specific values (Boisdron and Brock, 1969 Natanson, 1960). 

Black Speck. A fault, in glass, particularly in the form of a small inclusion of chrome ore. On pottery-ware the fault is generally caused by small particles of iron or its compounds. In vitreous enamelware also, the fault is caused by contamination. 

From a structural point-of-view the bulk metallic state, that is, fee lattice (with varying densities of defects such as twins and stacking faults) is generally established in gold nanoparticles of about 10 nm diameter and upwards. However, such particles still display many unusual physical properties, primarily as the result of their small size. Shrinking the size of gold particles has an important effect it increases both the relative proportion of surface atoms and of atoms of even lower coordination number, such as edge atoms [49] and these atoms in turn are relatively mobile and reactive. 

On any calender line there are several possible sources of contamination, the first being the raw materials used. In most resins there will be a small number of discoloured grains, which are accepted up to a specified level. On occasions a manufacturer s equipment fails and produces resin with more than normal contamination of this kind. Some particles may not be discoloured but may fail to disperse and so cause small lumps in the film (known in clear films as fish eyes ). On the other hand, lumps may not necessarily be attributable to faults in the resin—they can arise also from poor dispersion of plasticizer, or from degradation taking place at some stage in the process. 

Methods based on sedimentation rates (Micromerograph) or flotation (Roller Analyzer) aim to offer the actual particle-size distribution. Optical microscopy is qualitatively informative but its faults lie the extreme smallness of the sample, the tediousness of size tabulation if numerical results are desired, and the inability to discriminate in some cases between discrete particles and agglomerates. 

The attempts to separate our artificial radium isotopes from barium in this way were unsuccessful, Hahn would explain in his Nobel Prize lecture no enrichment of the radium was obtained. It was natural to ascribe this lack of success to the exceptionally low intensity of our preparations. It was always a question of merely a few thousands of atoms, which could only be detected as individual particles by the Geiger-Muller counter. Such a small number of atoms could be carried away by the great excess of inactive barium without any increase or decrease being perceptible. To check that possibility they retrieved from storage a known radium isotope they often worked with, the isotope they called mesothorium. They diluted it to match the pale radioactivity of their few thousand atoms of Ra-III, then ran it through barium precipitation and fractionation. It separated away cleanly from the barium. Their technique was not at fault. 

Stone. A crystalline inclusion present as a fault in glass stones may result from incomplete reaction of particles of batch or from the pick-up of small fragments of the refractory lining of the pot or furnace in which the glass is melted. The most common constituents of stones are carnegieite, corundum, cristobalite, mullite, nephelite, tridymite and zirconia. See also china stone. 

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