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The small-angle X-ray scattering (SAXS) curves on ultra-long n-alkanes obtained by Ungar and Keller at different times after reaching the crytallization temperature have been Fourier analysed and the correlation curves so obtained at different temperatures and different annealing times reflect sensitively all those morphological features which are broadly characteristic of the scattering curves. In addition the correlation curves beautifully show a transition from a non-integer-fraction (NIF) length to extended (E) chain structure. Some other parameters characterizing the kinetics of morphological features, which are not easily observable in SAXS, such as crystalline and amorphous lengths, degree of order and halfwidths of correlation peaks are also reported.

Poly N e ( p -bromo benzoyl-L-ornithine) is one of the few biopolymers existing in rare ω helical (four-fold) conformation which can be obtained from α form through an irreversible heat treatment. A study of its normal modes and dispersive behaviour shows several interesting features such as \lqcrossing over\rq, \lqrepulsion with character exchange\rqand Von Hove type \lqsingularities\rqwhich lead to a fuller interpretation of infrared (i.r.) spectra. The existence of alternately different side chain conformations which makes the phonon problem too large has been taken into account by considering the vibrations of the PBrBO chains with two independent conformations. Detailed study of skeletal, amide and side chain modes has been reported.

Zimm and Bragg theory of helix\(\rightleftharpoons\) coil transition has been modified to explain order\(\rightleftharpoons\) order transition in polynucleotides, in particular \(B\rightleftharpoons Z\rightleftharpoons \psi (-)\rightleftharpoons\) coil transitions in poly (dG-dC) and poly (dG-me 5 dC). Lambda anomaly in specific heat measurements around the transition point have also been explained by a further modification of the same theory. Theoretical results are found to be in good agreement with the experimental data. The Nucleation parameter which determines the sharpness of transition and depends on the extent and strength of cooperativity, is consistent with the stabilization/destabilization of the ordered states under various environmental conditions, e.g. methylation of cytosine residue at C5 position or change in the cationic concentration of the solvent.

The theory of cell model for diffuse phase transition has been applied to explain charge induced helix coil transitions in polyglutamic acid and leucineglutamic acid copolymers in aqueous solutions. The experimental data of Snipp, Miller and Nylund have been utilized. Uninterrupted sequence lengths in the helical and random coil regions have also been calculated.