Membrane potential overview

Electric field sensitive dyes respond to changes in electrical membrane potential by a variety of different mechanisms with widely varying response times depending on their chemical structure and their interaction with the membrane. An understanding of the mechanisms of dye response and their response mechanisms is important for an appropriate choice of a probe for a particular application. The purpose of this chapter is, therefore, to provide an overview of the dyes presently available, how they respond to voltage changes, and give some examples of how they have been applied. Finally, because there is still scope for the development of new dyes with improved properties, some directions for future research will be discussed. 

Figure 2 Schematic overview of membrane potential-based strategies for the targeted delivery of bioactive molecules to mitochondria in living mammalian cells.

Figure 4.10. Overview of nerve impulse transmission in chemical synapses. The action potential in the presynaptic nerve cell induces release of the nemotransmitter (e.g., acetylcholine) into the synaptic cleft. The transmitter binds to its receptor, e.g. the nicotinic acetylcholine receptor (NAR). The NAR is a hgand-gated channel it will open and become permeable to both and Na. This will move the membrane potential toward the average of the two respective equilibrium potentials however, in the process, the firing level of adjacent voltage-gated sodium charmels will be exceeded, and a full action potential will be triggered (inset).

Fig. 19.8. Overview of energy transformations in oxidative phosphorylation. The electrochemical potential gradient across the mitochondrial membrane is represented by ApH, the proton gradient, and A F, the membrane potential. The role of the electrochemical potential in oxidative phosphorylation is discussed in more depth in Chapter 21.

This chapter has given an overview of the structure and dynamics of lipid and water molecules in membrane systems, viewed with atomic resolution by molecular dynamics simulations of fully hydrated phospholipid bilayers. The calculations have permitted a detailed picture of the solvation of the lipid polar groups to be developed, and this picture has been used to elucidate the molecular origins of the dipole potential. The solvation structure has been discussed in terms of a somewhat arbitrary, but useful, definition of bound and bulk water molecules. 

The present work will mainly focus on biochemical membrane reactors operate at the production scale and give an overview of systems of potential interest studied at the laboratory level. 

Figure 1 Overview of the synaptic vesicle cycle, (a) Within the presynaptic terminal, synaptic vesicles are filled with neurotransmitter by the action of specific vesicular neurotransmitter transporters, (b) Neurotransmitter-filled vesicles translocate to the active-zone membrane where they undergo docking, (c) Docked vesicles transition to a release-competent state through a series of priming or prefusion reactions, (d) Invasion of an action potential into the presynaptic terminal and subsequent calcium influx induces rapid fusion of the synaptic vesicle membrane with the terminal membrane, which thereby releases the neurotransmitter into the synaptic cleft, (e) Spent vesicles are internalized by clathrin-mediated endocytosis and are recycled for reuse, which thus completes the synaptic vesicle cycle. SV, synaptic vesicle CCV, clathrin-coated vesicle EE, early endosome. NOTE The use of arrows indicates a temporal sequence of events. Physical translocation of synaptic vesicles is unlikely to occur between the docking and fusion steps.

More specifically in the area of this overview, zeolite materials constitute the main group of microporous membranes with regard to their potential membrane-reactor apphcations. The wide variety of existing zeolite structures, together with the possibility of modifying their adsorption and catalytic properties, provides us with a working material of high flexibihty. As a... 

This volume provides a vast overview of the physico-chemical and synthetic aspects of artificial membranes. Numerous membrane models are described, including their properties (i.e. swelling, drying, lateral mobility, stability, electrical conductivity, etc.), advantages, and drawbacks. The potential applications of these models are discussed and supported by real examples. 

This book provides an extensive overview of current thinking on applications, materials issues, and scale-up considerations related to dense oxygen and hydrogen transport membranes. For a broad outlook, international contributions have been obtained from researchers in academia, industry and national laboratories. Readers new to the field should find ample information on membrane fundamentals. Advanced researchers should find many previously unpublished concepts and research results to help forward their work. Readers will be aided by the large number of references to the membrane literature and especially by the extensive references to the patent literature, which reflect the potential commercial applications of membranes. 

This chapter presents an overview of different membrane processes and a description of all of the chapters presented in this edition. Chapter 2 focuses on updated information of utility to UF and NF membrane research and development, particularly in the preparation of new types of UF/NF membranes with improved performances. Chapter 3 presents a comprehensive review on RO membrane, the latest developments in the field, important installations demonstrating this technology, and future scope of RO processes. Chapter 4 presents the potential of membrane contactors, especially hollow fiber contactors in the field of chemical and nuclear industry along with their applications, performance, and current challenges faced by indnstry. This chapter also gives an introduction to membrane contactors, their principles of operation and associated mechanisms (where chemical reactions are involved), and fntnre scope of these contactors. 

ETFE-foils as a fluorine-polymer material differ fundamentally from textile membrane materials in terms of their thermal-mechanical as well as building-physics behaviour. This chapter first introduces the construction forms and variants of ETFE-foil structures and provides an overview of the development of ETFE-foil constructions from an architectural perspective. Subsequently, the morphological structure of ETFE and the manufacturing process as well as the material behaviour and load-bearing characteristics of ETFE-foils are outlined. The final section discusses future development potentials and the future use of ETFE-foil constructions in structural engineering. 

Palladium-based Membranes Overview and Potential for Hydrogen Purification... 

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