Mobility transport system

Medical mobile transport systems for the transport of medications, supplies, meals, and equipment, e. g. in the hospital between departments and wards, ro-... 

The atmosphere of the world cannot continue to accept greater and greater amounts of emissions from mobile sources as our transportation systems expand. The present emissions from all transportation sources in the United States exceed 50 biUion kg of carbon monoxide per year, 20 billion kg per year of unbumed hydrocarbons, and 20 billion kg of oxides of nitrogen. If presently used power sources cannot be modified to bring their emissions to acceptable levels, we must develop alternative power sources or alternative transportation systems. All alternatives should be considered simultaneously to achieve the desired result, an acceptable transportation system with a minimum of air pollution. 

All of the transport systems examined thus far are relatively large proteins. Several small molecule toxins produced by microorganisms facilitate ion transport across membranes. Due to their relative simplicity, these molecules, the lonophore antibiotics, represent paradigms of the mobile carrier and pore or charmel models for membrane transport. Mobile carriers are molecules that form complexes with particular ions and diffuse freely across a lipid membrane (Figure 10.38). Pores or channels, on the other hand, adopt a fixed orientation in a membrane, creating a hole that permits the transmembrane movement of ions. These pores or channels may be formed from monomeric or (more often) multimeric structures in the membrane. 

Carriers and channels may be distinguished on the basis of their temperature dependence. Channels are comparatively insensitive to membrane phase transitions and show only a slight dependence of transport rate on temperature. Mobile carriers, on the other hand, function efficiently above a membrane phase transition, but only poorly below it. Consequently, mobile carrier systems often show dramatic increases in transport rate as the system is heated through its phase transition. Figure 10.39 displays the structures of several of these interesting molecules. As might be anticipated from the variety of structures represented here, these molecules associate with membranes and facilitate transport by different means. 

To this point, we have emphasized that the cycle of mobilization, transport, and redeposition involves changes in the physical state and chemical form of the elements, and that the ultimate distribution of an element among different chemical species can be described by thermochemical equilibrium data. Equilibrium calculations describe the potential for change between two end states, and only in certain cases can they provide information about rates (Hoffman, 1981). In analyzing and modeling a geochemical system, a decision must be made as to whether an equilibrium or non-equilibrium model is appropriate. The choice depends on the time scales involved, and specifically on the ratio of the rate of the relevant chemical transition to the rate of the dominant physical process within the physical-chemical system. 

Pipeless plants are an alternative to the traditional recipe-driven multipurpose batch plants with fixed piping between the units. In this production concept, the batches of material are moved around between stationary processing stations in mobile vessels. The processing steps are performed at different single purpose or multipurpose stationary units but the material remains in the same vessel throughout the production process. The transportation of the mobile vessels can be realized by a transportation system that is fixed to the vessels or by automated guided vehicles (AGV) that pick up the vessels only to perform a transfer order [1]. 

The microbial cycling of phosphorus does not alter its oxidation state. Most phosphorus transformations mediated by microorganisms can be viewed as inorganic to organic phosphate transfers or as transfers of phosphate from insoluble, immobilized forms to soluble or mobile compounds. Various microorganisms have evolved transport systems for the regulated acquisition of phosphate from the environment. 

General advantages of facilitated transport membranes are improved selectivity, increased flux and, especially if compared with membrane contactors, the possibility to use expensive carriers. The specific prerequisites, advantages and disadvantages connected the mobile carriers, are reported in Table 7.1. So far, mainly conventional liquid membranes have been loaded with different mobile carrier systems to obtain facilitated transport properties [3]. Problems encountered are (evaporative) loss of solvent and carrier, temperature limitations, a too large membrane thickness and therefore too low permeabilities as weU as a limited solubility of the carrier in the liquid medium. The low fluxes achieved have, untU now, limited their application... 

Table 7.1 The specific requirements, advantages and disadvantages connected to mobile carrier systems with respect to their selective gas transport properties...

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