Cooperative structures

The value of EM for a cooperative self-assembled structure provides a measure of the monomer concentration at which trivial polymeric structures start to compete, and therefore EM represents the upper limit of the concentration range within which the cooperative structure is stable (Scheme 2). The lower limit of this range is called the critical self-assembly concentration (csac) and is determined by the stoichiometry of the assembly and the strength of the non-covalent binding interactions weaker interactions and larger numbers of components raise the csac and narrow the stability window of the assembly (8). Theoretical treatments of the thermodynamics of the self-assembly process have been reported by Hunter (8), Sanders (9), and Mandolini (10). The value of EM is lowered by enthalpic contributions associated with... 

Morama domestication on a certain scale seems to be the sole solution if a market for these means is supposed to reach broader boundaries (such as the national and the international level). Communal land would be best suited for morama domestication, by involving mostly poor populations within their already existent representative and cooperative structures. Processing industries should be developed at the local level and inscribed within existing local infrastructures in order to benefit and employ the poorer sections of the population. 

Positive cooperativity is a basic characteristic of molecular amplification devices, since once initiated, the subsequent steps of the assembly are facilitated. It represents a non-linear process and confers features of an error filter, only the correct input will in principle lead to the cooperative structure generation. 

Nelson MR, Thulin E, Fagan PA, Forsen S, Chazin WJ. 2002. The EF-hand domain a globally cooperative structural unit. Protein Sci 11 (2) 198—205. 

The Gibbs energy difference of the denatured and native states corresponds to the work required for the transition of a system from the native to the denatured state, i.e., the work of disruption of the native cooperative structure. Therefore, this quantity is usually considered as a measure of the stability of the cooperative structure, i.e., the stability of a small globular protein or cooperative domain. As for the large proteins, their stability cannot be expressed by a single value, but only by a set of values specifying the stability for each domain within these molecules and the interaction between the domains. 

Biltonen RL. A statistical-thermodynamic view of cooperative structural-changes in phospholipid-bilayer membranes-Their potential role in biological function. J. Chem. Thermodyn. 1990 22 1-19. 

Because lipid bilayers are held together by many reinforcing, noncovalent interactions (predominantly hydrophobic), they are cooperative structures. These hydrophobic interactions have three significant biological consequences (1) lipid bilayers have an inherent tendency to be extensive (2) lipid bilayers will tend to close on themselves so that there are no edges with exposed hydrocarbon chains, and so they form compartments and (3) lipid bilayers are self-sealing because a hole in a bilayer is energetically unfavorable. 

Membrane lipids spontaneously form extensive bimolecular sheets in aqueous solutions. The driving force for membrane formation is the hydrophobic interactions among the fatty acid tails of membrane lipids. The hydrophilic head groups interact with the aqueous medium. Lipid bilayers are cooperative structures, held together by many weak bonds. These lipid bilayers are highly impermeable to ions and most polar molecules, yet they are quite fluid, which enables them to act as a solvent for membrane proteins. 

S.J. Weigel, S.C. Weston, A.K. Cheetham, and G.D. Stucky, Cooperative Structure Direction in the Synthesis of Microporous Materials Preparation and Crystal Structure of TREN-GaPO. Chem. Mater., 1997, 9, 1293-1295. 

We argue that the above features of star dynamics are generic for soft systems of the core-shell type for which stars serve as prototype. Support for this comes from the dynamic light scattering (DLS) investigation of large block copolymer micelles, where all three relaxation modes, i.e., cooperative, structural and selfdiffusion are observed [188]. In particular, the star model discussed above applies to core-shell particles with a small spherical core relative to the chain (shell) dimensions. For a surface number density a = f / (47i r ) the polymer layer thickness under good solvent conditions is L ... 

This kind of direct cooperation between organizations resembles a graphlike network cooperation structure in a peer-to-peer mode which is not supported in the former delegation-based concept of AHEAD Both subcontractors cannot cooperate with each other directly but only through their common contractor, the chemical company (shown in the left part of the Figure). In this way, only tree-like cooperation structures are possible. Although this delegation-based process decomposition approach is sufficient in many situations, often direct cooperation between all partners of a cooperative network of companies is needed as well. 

Fig. 6.12. Energies of cooperative structure rearrangements versus the number of non-coincident sites m...

We have developed an automated parallel synthesis methodology that permits the rapid and detailed Investigation of hydrothermal systems. The general procedure is as follows automatic dispensing of reagents into autoclave blocks followed by synthesis, product isolation and automated structure analysis with X-ray diffractometry. Here we describe the application of this technique to the exploration of the aluminophosphate synthesis field. The effects of template, template concentration, A1 sources as well as mixed template systems are investigated. Emphasis is put on the study of cooperative structure direction effects. 

Most transitions in the secondary structures of biomacromolecules fall somewhere between the cooperative none-or-all and the noncooperative models. Many of these transitions can be described by the zipper model, which dissects the structural transition of a polymeric chain into a number of discrete steps (Figure 9.1). The model is a special case of the cooperative structural transition of biomacromolecules. In the zipper model, the initiation of the transition is harder than extension (propagation) and therefore low probability. This initiation step is of high energy and provides a nucleation point for the transition. The subsequent extension steps occur by a series of lower energy and consequently higher probability. 

The cooperative structural rearrangement of the network associated with the continuous swelling of the hypercrosslinked sorbent with all the examined organic vapors is indicated by the hysteresis loops always extending throughout the entire range of relative pressures, down to zero (Fig. 10.7). This basically differs from the hysteresis loops caused by capillary condensation in the mesopores of adsorbents with rigid structure in the latter case, the loop closes toward low vapor pressures. 

Rapid product development (RPD) shortens the feedback control cycles concerned with product data generation and the associated management processes. RPD exploits the potential of modem information and communication tools in order to support the necessary dynamic cooperation structures. Development times are systematically shortened by means of a holistic integration of man, organization, and technology. The learning processes can be systematically relocated to early product development phases. As a result of generative methods of production and virtual reality, physical and virtual prototypes can be made quickly available. 

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