Diffusion light-induced

El-Shishtawy R.M.A., S. Kawasaki, M. Morimoto (1997) Biological ff2 production using a novel light-induced and diffused photobioreactor. Biotechnol. Techn., 11 403-409... 

Biological membranes fluidity order parameters lipid-protein interactions translational diffusion site accessibility structural changes membrane potentials complexes and binding energy-linked and light-induced changes effects of additives location of proteins lateral organization and dynamics... 

If illumination is started long enough after the end of irradiation that produced etr, then the kinetics of a tunneling reaction in the presence of light-induced electron diffusion and under the condition of random spatial distribution of acceptor particles, provided n N and z < t, can be described by the expression (see Chap. 4, Sect. 4)... 

The primary effect of micelles on light-induced electron transfer involves the intervention of an interfacial region which can significantly influence the radical ion association and dissociation equilibria by a combination of electrostatic and hydro-phobic interactions. Diffusive encounters of reaction partners are controlled within a micelle by the diffusion of one reactant to the highly polar surface, by collision of two reactants confined within the hydrophobic region in the interior of the micelle, and by the reaction of two reactants whose motions are confined to diffusion along the micellar surface. 

Schmidt, J.A., Heitner, C., Kelly, G.P., Wilkinson, F.W., "Observation of Light-Induced Transients in Thermomechanical Pulp Using Diffuse-Reflectance Laser-Flash Photolysis". Proceedings of the 1989 International Symposium on Wood and Pulping Chemistry, Raleigh, N.C., 1989. 

The light-induced creation of recombination centers causes the diffusion length to decrease with exposure time as shown in Fig. 3 (Carlson et al., 1984b). The diffusion length was measured by the surface photovoltage method (Dresner et al., 1980), and similar results were obtained from an analysis of device characteristics (Faughnan et al., 1983). 

Riboflavin occurs as a yellow to orange-yellow, crystalline powder. When dry, it is not affected by diffused light, but when in solution, light induces deterioration. It melts at about 280° with decomposition, and its saturated solution is neutral to litmus. One gram dissolves in 3000 to about 20,000 mL of water, the variations being due to differences in the internal crystalline structure. It is less soluble in alcohol than in water. It is insoluble in ether and in chloroform, but it is very soluble in dilute solutions of alkalies. 

Riboflavin 5 -Phosphate Sodium occurs as a fine, orange-yellow, crystalline powder. One gram dissolves in about 30 mL of water. When dry, it is not affected by diffused light, but when in solution, light induces deterioration rapidly. It is hygroscopic. 

The aimealing kinetics of the light-induced defects are shown in Fig. 6.29. Several hours at 130 °C are needed to anneal the defects completely, but only a few minutes at 200 C. The relaxation is nonexponential, and in the initial measurements of the decay the results were analyzed in terms of a distribution of time constants, Eq. (6.78) (Stutzmann, Jackson and Tsai 1986). The distribution is centered close to 1 eV with a width of about 0.2 eV. Subsequently it was found that the decay fits a stretched exponential, as is shown in Fig. 6.29. The parameters of the decay-the dispersion, p, and the temperature dependence of the decay time, t - are similar to those found for the thermal relaxation data and so are consistent with the same mechanism of hydrogen diffusion. The data are included in Fig. 6.23 which describes the general relation between x and D,. The annealing is therefore the process of relaxation to the equilibrium state with a low defect density. 

---