Anisotropy transport

The flow velocity, pressure and dynamic viscosity are denoted u, p and fj and the symbol (...) represents an average over the fluid phase. Kim et al. used an extended Darcy equation to model the flow distribution in a micro channel cooling device [118]. In general, the permeability K has to be regarded as a tensor quantity accounting for the anisotropy of the medium. Furthermore, the description can be generalized to include heat transfer effects in porous media. More details on transport processes in porous media will be presented in Section 2.9. 

Apart from the tunable color emission covering the full visible range, there are several other aspects supporting the interest in PTs for PLEDs. PTs are examples of classical conjugated polymers with intrinsic one-dimensionality of the polymer chain. Alignment can induce anisotropy in macroscopic properties such as electron transport or optical properties. Polarized... 

Vamavski OP, Ostrowski JC, Sukhomlinova L, Twieg RJ, Bazan GC, Goodson T (2002) Coherent effects in energy transport in model dendritic structures investigated by ultrafast fluorescence anisotropy spectroscopy. J Am Chem Soc 124 1736-1743... 

Homotransfer does not cause additional de-excitation of the donor molecules, i.e. does not result in fluorescence quenching. In fact, the probability of de-excitation of a donor molecule does not depend on the fact that this molecule was initially excited by absorption of a photon or by transfer of excitation from another donor molecule. Therefore, the fluorescence decay of a population of donor molecules is not perturbed by possible excitation transport among donors. Because the transition dipole moments of the molecules are not parallel (except in very rare cases), the polarization of the emitted fluorescence is affected by homotransfer and information on the kinetics of excitation transport is provided by the decay of emission anisotropy. 

The two cationic dyes, Py+ as a donor and Ox" as an acceptor, were found to be very versatile for demonstrating photonic antenna functionalities for light harvesting, transport, and capturing, as illustrated in Fig. 7. They can be incorporated into zeolite L by means of ion exchange, where they are present as monomers because of the restricted space. In this form they have a high fluorescence quantum yield and favourable spectral properties. The insertion of the dyes can be visualised by means of fluorescence microscopy. The fluorescence anisotropy of Ox -loaded zeolite L has recently been investigated in detail by conventional and by confocal microscopy techniques [15],... 

It allows also to explain, from covalency effects, the anisotropy of transport properties ... 

Chauvin, R Brand, L. Roseman, S. Sugar transport by the bacterial phosphotransferase system. Characterization of the Escherichia coli enzyme I monomer/dimer transition kinetics by fluorescence anisotropy. J. Biol. Chem., 269, 20270-20274 (1994)... 

Fixed framework-flexible adsorbate calculations were also reported by Dumont and Bougeard (68, 69). The diffusion coefficient calculated from a 42-ps calculation of 4 molecules per unit cell at 300 K was 1.60 x 10 8 m2/s. Once again the anisotropy of the diffusive process was calculated to be strong transport through the straight channel was found to be twice as fast as through the sinusoidal channel and an order of magnitude faster than motion parallel to the z-axis. 

The pronounced anisotropy of the electrical conductivity in layered compounds (8,15) suggests that the charge carriers move, on their way to the surface, predominantly within the layers, i.e. parallel to the main surface as shown in Fig. 14 (in which the relative path of the charge carriers within the layers is compressed). The random character of interlayer charge transport due to extrinsic conduction leads to a variety of possible paths, two of which are represented in Fig. 14. 

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