Migration deficits

Gauthier et al. [38] studied radial migration of spherical particles with a concentration of 5% by volume in the mixture for the following values of parameters a = 0.019 cm R = 0.4 cm V = 0.127 cm3/s, n = 0.64. At the start of the time period, a particle deficit was observed at the channel walls, three minutes later the particles were uniformly distributed in the channel, ten minutes later 75 % of particles... 

Minematsu K, Yamaguchi T, Omae T (1992) Spectacular shrinking deficit rapid recovery from a major hemispheric syndrome by migration of an embolus. Neurology 42 157-162... 

Min WK, Park KK, Kim YS et al (2000) Atherothrombotic middle cerebral artery territory infarction. Topographic diversity with common occurrence of concomitant small cortical and subcortical infarcts. Stroke 31 2055-2061 Minematsu K, Yamaguchi T, Omae T (1992) Spectacular shrinking deficit rapid recovery from a major hemispheric syndrome by migration of an embolus. Neurology 42 157-162... 

While this offers further support for prefrontal and inferior parietal dysfunction in the deficit syndrome, other areas of the brain have not been examined. However, it prompts interesting theories of the deficit syndrome being related to failure of normal neuronal migration. 

As discussed earlier, NiO is ap-type cation-deficit semiconductor and, therefore, the cations will migrate with electrons from the scale-metal interface to the scale-gas interface during oxidation. Correspondingly, there will be a flow of defects, cation vacancies and electron holes, in the opposite direction. Consequently, the driving force for the reaction will be reflected by the concentration gradient of cation vacancies across the scale. The nickel vacancies are formed according to Equation (4.2),... 

Cobalt forms two oxides, CoO and C03O4, of NaCl and spinel structures, respectively CoO is a p-type cation-deficit semiconductor through which cations and electrons migrate over cation vacancies and electron holes. In addition to the usual extrinsic defects, due to deviations from stoichiometry above 1050 °C, intrinsic Frenkel-type defects are also present. The variations of oxidation-rate constant with oxygen partial pressure and with temperature are, therefore, expected to be relatively complex. Consequently, it is important to ensure that very accurate data are obtained for the oxidation reactions, over a wide range of oxygen pressure and temperature. 

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