Optical cross section information obtained

The evaluation of the electronic wave functions of Eq. (34) has been neglected in this section this aspect was not required for our classification of papers in Section lOd. Information on this topic can be obtained from reviews (such as, Stoneham, 1975 Pantelides, 1978 Jaros, 1980), or from some of the papers discussed in Section lOd. Additionally, we discuss some parts of this problem in Section 12 in connection with evaluation of optical cross sections. 

From the 1970s, a large number of imaging studies of non-Brownian suspensions flowing in mm- to cm-sized channels have been performed via Laser Doppler Veiocimetry [120-123] and NMRI [124,125], but little information has been obtained at the single-particle level. Optical microscopy experiments on channel flows of colloids have only recently started to appear, often in relation to microfluidics applications [126]. To avoid image distortions, channels witli square or rectangular cross sections are preferred to cylindrical capillaries. 

The detailed results of the photochemical models are dependent on the adopted UV radiation field as well as on the photodissociation and photoionisation cross-sections, which in principle can be obtained by laboratory or theoretical studies, and on the nature of the dust particles for which the chemical composition, size and hence optical properties are poorly known. In the absence of definitive information, detailed models of the photochemistry have relied on some rather simplistic approaches to the radiative transfer of UV photons through the envelope. Nejad and Millar (1987,1988) have used the approach developed by Jura and Morris (1981) which assumes that the dust grains absorb but do not scatter and leads to a numerically simple equation for the intensity of UV radiation at any point in the envelope. On the other hand, Glassgold and co-workers have used a formalism devised by Gerola and Glassgold (1978) in which the scale-length, dp for photodissociation of any species is used to diminish the intensity incident on the CSE, that is, the intensity is reduced by a quantity exp(-d(/r). These authors have also included the effects of both continuum and line self-shielding in their calculations. 

Direct information on membrane porous structure and sublayer structure is obtained with microscopical methods. The most commonly applied methods are SEM and AFM because the resolution of the microscopes is good enough for characterization of ultra- and nano-hltration membranes and even RO membranes. In rough surface characterization conventional optical microscopy can also be used. The resolution of CSLM is sufficient only for characterization of microhltration membranes. However, the advantage of CSLM is that information on the membrane bulk structure can be obtained without physical sample cross sectioning. 

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