Channel modeling

Quack M and Tree J 1974 Specific rate constants of unimolecular processes. II. Adiabatic channel model Ber. Bunsenges. Phys. Chem. 78 240-52... 

Quack M and Troe J 1998 Statistical adiabatic channel model Encyclopedia of Computational Chemistry vo 4, ed P von Rague Schleyer et a/(New York Wiley) pp 2708-26... 

Quack M and Troe J 1975 Complex formation in reactive and inelastic scattering statistical adiabatic channel model of unimolecular processes III Ber. Bunsenges. Phys. Chem. 79 170-83... 

Rather than using transition state theory or trajectory calculations, it is possible to use a statistical description of reactions to compute the rate constant. There are a number of techniques that can be considered variants of the statistical adiabatic channel model (SACM). This is, in essence, the examination of many possible reaction paths, none of which would necessarily be seen in a trajectory calculation. By examining paths that are easier to determine than the trajectory path and giving them statistical weights, the whole potential energy surface is accounted for and the rate constant can be computed. 

SACM (statistical adiabatic channel model) method for computing reaction rates... 

II The Channel Mechanism of Ion Transport The Gramicidin Channel Model 181... 

We refer to channel models satisfying Eqs. (4-3) and (4-4) as discrete memoryless channels. 

This class of channel models appears rather restrictive at first, but it can be applied to many channels whose inputs and outputs are functions of time simply by quantizing in time and amplitude. This problem is discussed in more detail in Section 4.8 where the results that we derive for discrete memoryless channels are extended to a more general class of channels. 

Continuous Memoryless Channels.—The coding theorem of the last section will be extended here to the following three types of channel models channels with discrete input and continuous output channels with continuous input and continuous output and channels with band limited time functions for input and output. Although these models are still somewhat crude approximations to most physical communication channels, they still provide considerable insight into the effects of the noise and the relative merits of various transmission and detection schemes. 

Communication systems, channel models of discrete memoryless, 194,208 discrete, 192 models, 193 random process, 193 source models, 193 discrete memoryless, 194 Compatibility table for magnetic groups, 742... 

The most likely way for pardaxin molecules to insert across the membrane in an antiparallel manner is for them to form antiparallel aggregates on the membrane surface that then insert across the membrane. We developed a "raft"model (data not shown) that is similar to the channel model except that adjacent dimers are related to each other by a linear translation instead of a 60 rotation about a channel axis. All of the large hydrophobic side chains of the C-helices are on one side of the "raft" and all hydrophilic side chains are on the other side. We postulate that these "rafts" displace the lipid molecules on one side of the bilayer. When two or more "rafts" meet they can insert across the membrane to form a channel in a way that never exposes the hydrophilic side chains to the lipid alkyl chains. The conformational change from the "raft" to the channel structure primarily involves a pivoting motion about the "ridge" of side chains formed by Thr-17, Ala-21, Ala-25, and Ser-29. These small side chains present few steric barriers for the postulated conformational change. 

For highly exothermic SN2 reactions, which have a central barrier significantly lower in energy than that of the reactants, association of the reactants may be the rate controlling step in TST.1 The SN2 rate constant can then be modeled by a capture theory9 such as VTST,10 average dipole orientation (ADO) theory,11 the statistical adiabatic channel model (SACM),12 or the trajectory capture model.13... 

Because T -> V energy transfer does not lead to complex formation and complexes are only formed by unoriented collisions, the Cl" + CH3C1 -4 Cl"—CH3C1 association rate constant calculated from the trajectories is less than that given by an ion-molecule capture model. This is shown in Table 8, where the trajectory association rate constant is compared with the predictions of various capture models.9 The microcanonical variational transition state theory (pCVTST) rate constants calculated for PES1, with the transitional modes treated as harmonic oscillators (ho) are nearly the same as the statistical adiabatic channel model (SACM),13 pCVTST,40 and trajectory capture14 rate constants based on the ion-di-pole/ion-induced dipole potential,... 

Figure 2. The geometry of the Lorentz gas channel model. The two heat reservoirs at temperatures Tl and Tr are indicated.

Recanatini, M., Cavalli, A. and Masetti, M. (2005) In silico modelling-pharmacophores and hERG channel models. Novartis Foundation Symposium, 266171—181, discussion 181—175. 

The simple water charmel models can explain the ionomer peak and the small-angle upturn in the scattering data of fhe unoriented samples as well as of the oriented films. Interestingly, the helical structure of backbone segments is responsible for fhe sfabilify of fhe long cylindrical charmels. The self-diffusion behavior of wafer and protons in Nation is well described by the water channel model. The existence of parallel wide channels af high wafer uptake favors large hydrodynamic confributions to electro-osmotic water transport and hydraulic permeation. 

The original cluster-network model proposed by Gierke et al. (also referred to as the cluster-channel model) has been the most widely referenced model in the history of perfluorosulfonate ionomers. Despite the very large number of papers and reports that have strictly relied on this model to explain a wide variety of physical properties and other characteristics of Nafion, this model was never meant to be a definitive description of the actual morphology of Nafion, and the authors recognized that further experimental work would be required to completely define the nature of ionic clustering in these iono-mers. For example, the paracrystalline, cubic lattice... 

As shown in Figure 16b, the 2-D rib models deal with how the existence of a solid rib affects fuel-cell performance. They do not examine the along-the-channel effects discussed above. Instead, the relevant dimensions deal with the physical reality that the gas channeFdiffusion media interfaces are not continuous. Instead, the ribs of the flow-channel plates break them. These 2-D models focus on the cathode side of the fuel-cell sandwich because oxygen and water transport there have a much more significant impact on performance. This is in contrast to the along-the-channel models that show that the underhumidification of and water transport to the anode are more important than those for the cathode. 

Cosconati S, Marinelli L, Lavecchia A, Novellino E. (2007) Characterizing the 1,4-dihydropyridines binding interactions in the L-type Ca channel Model constrnction and docking calcnlations. J Med Chem 50 1504-1513. 

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