Corona outer

PBDs may occur on plastic surfaces with no metal substrate, for example the wall of a plastic pipe conveying charged material, in this case the double layer forms between the inner charged wall of the pipe and a countercharge which accumulates on the outer wall via conduction or via corona discharge. in the latter case both layers of charge reside on nonconductive sur-... 

For powders, cp/pp is approximately one-half. If we further assume that the outer edge of the volume will go into corona when exceeds 3 V/micron, which is the normal electrical breakdown strength of a flat surface in air, Table II shows the maximum size containers that can be used for various net levels of particle charging without having the charge lost by corona. 

As to the origin of mass-loss in cool luminous stars, several possibilities have been proposed, but none of them could provide satisfactory answer yet. As noted in Sect.I, the cool wind should originate not in the stellar surface but in outer layer at least several stellar radii above the stellar surface. We already know such a case in the thermally-driven wind from the hot corona of the Sun. However, the difficulty to apply the theory of thermally-driven wind to cool luminous stars has already been recognized at an early time( e.g., Weymann, 1963). More recent discovery of nonexistence of hot transition region( and hence of corona) in these stars by IUE obser-vations(Linsky,Haisch,1979) finally disclosed that the origin of mass-loss in cool luminous stars may be radically different from that in solar type stars. 

Electrical charges are produced on the metal-semiconductor interface and on the outer surface of the semiconductor, by means of a corona discharge (ionization of the air by high voltage). 

The conLguration of the polymers in the micelle has also been studied within the framework of the Daoud-Cotton model (Daoud and Cotton, 1982) for star polymers. However, this model assumes that all the chain ends lie at the outer surface of the corona, therefore overlooking the possibility of a chain-end distribution Marques (1997). 

Fig. 8 Schematic density profile of a block copolymer micelle. Uncharged micelles exhibit a simple core/shell structure whereas polyelectrolyte block copolymer micelles can show phase separation of the corona into a dense interior and a dilute outer domain...

For quite some time, there have been indications for a phase-separation in the shell of polyelectrolyte block copolymer micelles. Electrophoretic mobility measurements on PS-PMAc [50] indicated that a part of the shell exhibits a considerable higher ionic strength than the surrounding medium. This had been corroborated by fluorescence studies on PS-PMAc [51-53] and PS-P2VP-heteroarm star polymers [54]. According to the steady-state fluorescence and anisotropy decays of fluorophores attached to the ends of the PMAc-blocks, a certain fraction of the fluorophores (probably those on the blocks that were folded back to the core/shell interface) monitored a lower polarity of the environment. Their mobility was substantially restricted. It thus seemed as if the polyelectrolyte corona was phase separated into a dense interior part and a dilute outer part. Further experimental evidence for the existence of a dense interior corona domain has been found in an NMR/SANS-study on poly(methylmethacrylate-fr-acrylic acid) (PMMA-PAAc) micelles [55]. 

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