Grain mobility

By far the most work on the control of enzymes responsible for the mobilization of stored reserves has been carried out on cereal grains and some of the possible reasons for the preferential use of this material should become clear in this chapter. Discussion of this topic inevitably involves a consideration of the effects of plant hormones on cell metabolism and, more specifically, of their actions in non-growing storage tissue. The reason for this is that in the best-understood system—the cereal grain—mobilization of food reserves is quite clearly under hormonal control. The major part of this chapter is therefore devoted to regulation in these grains, especially barley and wheat, but we conclude with an account of control processes in other seeds. 

From polarization curves the protectiveness of a passive film in a certain environment can be estimated from the passive current density in figure C2.8.4 which reflects the layer s resistance to ion transport tlirough the film, and chemical dissolution of the film. It is clear that a variety of factors can influence ion transport tlirough the film, such as the film s chemical composition, stmcture, number of grain boundaries and the extent of flaws and pores. The protectiveness and stability of passive films has, for instance, been based on percolation arguments [67, 681, stmctural arguments [69], ion/defect mobility [56, 57] and charge distribution [70, 71]. 

As in chemical sensitization, spectral sensitization is usually done after precipitation but before coating, and usually is achieved by adsorbing certain organic dyes to the silver haUde surfaces (47,48,212—229). Once the dye molecule is adsorbed to the crystal surface, the effects of electromagnetic radiation absorbed by the dye can be transferred to the crystal. As a result of this transfer, mobile electrons are produced in the conduction band of the silver haUde grain. Once in the conduction band, the electrons are available to initiate latent-image formation. 

The mobility, M, is a function of the substance, and obeys an AiThenius expression M — Mq exp —(AE/RT) where AE is the energy of transfer across the grain boundary. 

The mobility of grain boundaries is substantially reduced by the presence of the pores and the resn aiiiiiig force may be calculated simply to have a maximum value. 

Leicht-fiussigkeit,/. easy fusibility easy lique-flability high fluidity mobility, -frucht,/ light grain (as oats, emmer). leichtglaublg, a. credulous. 

The interpretation of the relationships obtained here is based on the same principles of polyfunctional interaction between CP and organic ions which are considered in sections 3.1-3.3. The dispersion of CP grains to a certain size (1-10 pm) yields particles retaining the ability of polyfunctional interaction with organic ions. Simultaneously with increasing dispersion, the mobility of elements of the crosslinked structure also increases, which favors additional interaction. Further dispersion of CP (d 0.1 pm) gives so weak networks that the spatial effect of polyfunctional interaction with organic ions drastically decreases similar to linear polyelectrolytes [64]. 

The commonly used catalyst today is a vanadia on a titania support, which is resistant to the high SO2 content. Usually the titania is in the anatase form since it is easier to produce with large surface areas than the rutile form. Several poisons for the catalyst exist, e.g. arsenic and potassium. The latter is a major problem with biomass fuel. In particular, straw, a byproduct from grain production, seems to be an attractive biomass but contains potassium, which is very mobile at reaction tern-... 

An important result of this study is the conclusion of a particle-size-dependent COads surface mobility. The value obtained for large Ft particles is significantly smaller than Deo at a solid/gas interface. However, Kobayashi and co-workers, using solid state NMR, performed measurements of the tracer diffusion coefficient Deo at the solid/electrolyte interface and for Ft-black particles (about 5nm grain... 

---