Short-chain-length

R N. The exponent v = 0.588 has been calculated using renonnalization group teclmiques [9, 10], enumeration teclmiques for short chain lengths and Monte Carlo simulations [13]. 

These compounds show a nematic and smectic C phase for relatively short chain lengths (n 7-10) and a hexagonal (columnar) phase for longer chains. 

There have been notable successes in the replacement of individual peptide residues by peptoid monomers with retention of in vitro activity and enhancement of specificity. Unfortunately, attempts to completely transform those bioactive peptides that function via specific peptide-protein binding events into entirely pep-toid-based ohgomers have so far proven successful only at short chain lengths (e.g. [23]). It remains to be seen whether any general strategy can be developed in... 

Fig. 5.3. Log-log plot of the self-diffusion constant D of polymer melts vs. chain length N. D is normalized by the diffusion constant of the Rouse limit, DRoUse> which is reached for short chain lengths. N is normalized by Ne, which is estimated from the kink in the log-log plot of the mean-square displacement of inner monomers vs. time [gi (t) vs. t]. Molecular dynamics results [177] and experimental data on PE [178] are compared with the MC results [40] for the athermal bond fluctuation model. From [40]...

Keywords. Bacterial polyester, Medium-chain-length poly(3-hydroxyalkanoates), Pseudomonas oleovorans, Pseudomonas putida, Functional poly(3-hydroxyalkanoates), Short-chain-length poly(3-hydroxyalkanoates)... 

Short-Chain-Length Poly(3-hydroxyalkanoates) [poly(HASCL)s]. . 56... 

Short-Chain-Length-PHAs Containing Repeating Units other than... 

First, the short chain length PHAs, poly(HASCL), are composed of monomeric units containing up to 5 carbon atoms. The most well-known representatives are poly(3-hydroxybutyrate) (PHB), and its copolymers with hydroxyvalerate. Of all the PHAs, PHB is by far the most commonly encountered in nature [18]. It is the simplest PHA with respect to chemical structure, having a methylene (-CH3) group as the pendent R-unit in Fig. 1. Owing to its enzymatic synthesis, PHB has an exceptional stereochemical regularity. The chains are linear and the chiral centers all are in the R-stereochemical conformation, which implies that this polymer is completely isotactic. 

Applications from Short Chain Length PHAs... 

Unfortunately, only a few short-chain-length poly(HA)s [poly(HASCL)], namely poly(3HB), its copolymers with 3-hydroxyvalerate, and poly(3-hy-droxyvaleric acid) [poly(3HV)], can be prepared as a milky suspension of de-... 

A rate of production analysis shows that radical production occurs primarily via 0(xD)+H20, but with a significant contribution to HO2 from HCHO photolysis. OH reacts mainly with CO and CH4, followed by HCHO, H2, O3 and CH3OOH with minor contributions from NMHCs. At the low NO concentrations encountered on these clean days, radical-radical reactions dominate the loss of peroxy-radicals resulting in a reduced chain propagation via CH3O2+NO and HO2+NO and in a very short chain length ( 0.14), calculated as the rate of HC>2 OH conversion divided by the total radical production rate. 

It is usual to convert fatty acids to their methyl ester derivatives before separation by GLC, although it may be possible to analyse those with short chain lengths (two to eight carbon atoms) as the free fatty acids. Polar or non-polar stationary phases can be used and capillary (open-tubular) or SCOT columns will separate positional and geometric isomers. The cis isomers have shorter retention times than the corresponding trans isomers on a non-polar phase and visa versa on a polar phase. 

PHAscl (short chain length monomer unit consisting of up to five carbon atoms)... 

The difference suggests that at least one group was encountering uncorrected difficulties with short chain lengths. 

Gaseous paraffins and olefins with low molecular weight and short chain length have relatively high critical compression ratios. Their octane numbers must all be well above 100. Normal paraffins have the lowest octane numbers of any of the members of their... 

Almost pure cellulose is found in pith, absorbent cotton in some filter papers. Pure cellulose is most readily obtd from cotton by treating it with dil alkalies acids and thoroughly washing, with water. Another source of cellulose is wood(mostly coniferous) which contains 50-60% cellulose and strawfmostly cereal) which contains 30-40%. A common classification of celluloses is based on their solubilities in aq alkalies If cellulose is treated with NaOH soln of ca 18% at 20°, it will swell and much of the material, which is of short chain length, will dissolve. The residue from this treatment is called alpha cellulose. 

The short chain length is due to the high water concentration the intermediate carbocation loses a proton to water before it can react with another alkene molecule. 

There have been a number of computer simulations of block copolymers by Binder and co-workers (Fried and Binder 1991a,ft), and this work was reviewed in Binder (1994). Although computer simulations are limited due to the restriction on short chain lengths that can be studied, finite size effects and equilibration problems at low temperatures, the advantages are that the models are perfectly well characterized and ideal (monodisperse, etc.) and microscopic details of the system can be computed (Binder 1994). In the simulations by Binder and co-workers, diblocks were modelled as self- and mutually-avoiding chains on a simple cubic lattice, with chain lengths N = 14 to 60 for/ = 1.A purely repulsive pairwise interaction between A and B segments on adjacent sites was assumed. A finite volume fraction of vacancies was included to speed the thermal equilibration process (Binder 1994). 

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