Ghost chain

Fig. 1.12 Osmotic pressure JlV/k T plotted vs. volume fraction 4>, for the athermal bond fluctuation model on the simple cubic lattice, N = 20. Open squares are obtained by Deutsch and Dickman with the repulsive wall method full squares are based on thermodynamic integration over a variable excluded volume interaction between the inserted ghost chain and the other chains. Curve shows the pressure according to the Generalized Flory equation of state of Ref. 172, H , )lkiT- < >], where v N) is the exclusion volume of an iV-mer. (From Muller and Paul. )...

In the years following the rise of polymer characterization (the late 0 s and early 50 s), many scientists began to study apparent relations between the properties of linear polymer molecules and the networks obtainable therefrom. This search was also stimulated by the wide range of applications of polymer networks in commercial elastomers thermosets and coatings. Frequently these data were confidently matched with curves obtained from statistically describable models of networks of ghost chains uniformly distributed in space. 

FIG. 11 Order parameter variation along acyl chains in red cell ghosts ( ), small unilamellar vesicles of egg phosphatidylcholine (V), and paraffin oil (+), as determined by the fluorescence anisotropy decay of the w-anthroyloxy fatty acid probes. (Reprinted by permission from Ref. 12.)... 

From the experiments it is clear that poly electrolyte is adsorbed on the surface of the black lipid film. This applies both to the experiments with gelatin and bovine serum albumin, which gave no decrease of film resistance, and to the experiments with bovine erythrocyte ghost protein and polyphosphate. The adsorption of protein on the phospholipid-water interface may be controlled independently by investigating the electrophoretic behavior of emulsion droplets, stabilized by phospholipid, in a protein solution, as a function of pH. In this way Haydon (3) established protein adsorption on the phospholipid-water interface. If the high resistance (107 ohms per sq. cm.) of black lipid films is to be ascribed to the continuous layer of hydrocarbon chains in the interior of the film, as is generally done, an increase in film conductivity is not expected from adsorption without penetration. 

For biological membranes the situation is more complex. The results from erythrocyte ghosts and lipids (13) suggest nonpolar association through lipid hydrocarbon chains. As a test of the technique a membrane in which the bilayer conformation has been demonstrated by some independent technique is desirable. I have argued earlier from calorimetric evidence that the membrane of M. laidlawii is such a system. NMR spectra of M. laidlawii membranes taken in this laboratory do not, however, show discernible hydrocarbon proton resonance. We must consider, then, why the two techniques of calorimetry and NMR do not agree. 

Synthesis of /x-chain only was first found in tissue culture lines grown from human lymphoma cells (Tl). The patient later described (B3) is just like a typical case of Bence Jones only myelomatosis, with amyloidosis, except that a fast-migrating component reacting only with anti- was also found. This was not visible on serum electrophoresis. It might just represent a ghost of memory of the IgM type of immunoglobulin the original plasma cell precursor should have made. 

These effects are not specific for dipalmitoyl glycerophosphocholine thus, unsaturated phosphatidylcholines and the lipid extract of human erythrocyte ghosts exhibit similar behaviour. The explanation for this behaviour is that addition of cholesterol to the lipid-water system causes a reduction in the cohesive forces between adjacent ordered hydrocarbon chains of the hpid preventing chain crystallisation leading to an increase in fluidity of the lipid chains. The presence of water is also of prime importance in this interaction and cholesterol is precipitated when most of the water is removed. 

Spectrin - elongated molecules made up of 012/ 2 tetramers. The tetramers form a chainlike structure that links the many components of the ghost and the skeleton. Spectrins contain a large portion of their structure in the form of an oi-helix and appear to be linked at their ends through short chains of actin molecules, together with band 4.1 protein and adducin. 

At liquid-like densities, the configurational-bias ghost particle approach is reliable only for chain molecules of intermediate length [71]. This limitation can be partially overcome by applying other techniques, such as the method of expanded ensembles. 

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