Carrier structure

The device model describes transport in the organic device by the time-dependent continuity equation, with a drift-diffusion form for the current density, coupled to Poisson s equation. To be specific, consider single-carrier structures with holes as the dominant carrier type. In this case,... 

A device model to describe two-carrier structures is basically similar to that used for one carrier structures except that continuity equations for both earner types are solved. The additional process that must be considered is charge carrier recombination. The recombination is bimolecular, R=y(np), where the recombination coefficient is given by 43)... 

In plants, the photosynthesis reaction takes place in specialized organelles termed chloroplasts. The chloroplasts are bounded in a two-membrane envelope with an additional third internal membrane called thylakoid membrane. This thylakoid membrane is a highly folded structure, which encloses a distinct compartment called thylakoid lumen. The chlorophyll found in chloroplasts is bound to the protein in the thylakoid membrane. The major photosensitive molecules in plants are the chlorophylls chlorophyll a and chlorophyll b. They are coupled through electron transfer chains to other molecules that act as electron carriers. Structures of chlorophyll a, chlorophyll b, and pheophytin a are shown in Figure 7.9. 

Fig. 5.59 shows a section through a Piezo-resistive silicon pressure sensor. The ambient pressure is applied from above, while the pressure being measured is applied from below. A silicon membrane that deforms under the pressure is applied to a silicon carrier structure. Piezo-resistive structures are fitted in the membrane, which then change their resistance accordingly when the membrane deforms. A bridge circuit generates an electrical output signal which is proportional to the difference in pressure. 

CA 54, 6833(1960) (Expls of high mechanical strength prepd by working into expls, as carrier structures, organic fibrous substances, especially nitrated ones)... 

The active phase of the Deacon catalyst is usually assumed to be a complex melt of copper or chromium and alkaline metal chlorides under reaction conditions, which is distributed within the pore network of an inert carrier [42]. Such supported liquid-phase catalysts (SLPC) are eminently suitable for adsorbing large amounts of the reacting components as sorption takes place in a bulk phase and is not restricted to only a limited number of suitable surface sites. The periodic expansion and contraction of the melt as a result of (de) sorption imposes considerable strains on the carrier structure hence, special mechanically robust support materials are needed to withstand such strains and prevent the catalyst crumbling away and disintegrating after a few cycles. In addition, even when it is immobilized on the carrier, the melt is extremely aggressive and resistant materials must be used for reactor construction. 

Recently, Pt clusters supported on hydrotaleite-derived magnesia, Mg(Al)0, were shown to catalyze the aromatization of n-hexane as effectively as a Pt/KL catalyst (8). A high surface area basic oxide was chosen to support the metal clusters in order to investigate the influence of carrier structure on aromatization. In that study, significant quantities of cracked products were produced by both the zeolite and non-zeolite catalysts. Since the zeolite catalyst was prepared in a fashion that resulted in residual acidity being present, observation of cracked products is not surprising. However, cracking reactions over Pt/Mg(Al)0 are not as easily explained. 

For the majority of industrial catalysts, the sizes of supported metal particles arc less than the mean free path of the electrons analysed. All the metal in the particles is effectively analysed. For highly dispersed systems, XPS surface analysis and bulk X-ray nuorcsccncc analysis therefore give similar results. Comparing information from these two techniques can be used to show a change in the distribution of metals on the surface due, for example, to sintering or to the inclusion of one of the metals into the carrier structure. 

Major polymer applications aerospace, electronics (mostly films and coatings), photosensitive materials for positive imaging, solar cells, hollow fiber membranes, composites. unclear power plants, space shuttle, microprocessor chip carriers, structural adhesives... 

Decreased film and/or membrane support thicknesses are not the only way to increase diffusion rate. Structural features of phases can themselves alter diffusion. Thus, manipulation of carrier structural features offers minimal benefit for increasing transport rates. 

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