Esterification with orthophosphoric acid of cellulose samples with different extents of structural heterogeneity

Modification of cellulose samples with different extents of structural heterogeneity by esterification with orthophosphoric acid in the temperature range 140?C160??C was studied. The reaction yielded cellulose phosphates containing 3.2?C6.0 wt % P, with the ion-exchange capacity of 2.2?C3.0 mg-equiv g^?1. Introduction of phosphorus into cellulose leads to a slight decrease in the structural heterogeneity. The polymer with the lower ordering index is characterized by the higher phosphorus content, which suggests that the reaction mainly occurs in the amorphous part of the polymer.     

Nuclear relativistic hartree-fock approximation with effective pions

The effect of an interaction between the ??- and ??-meson fields, as well as that of the mixture of pseudoscalar (PS) and pseudovector (PV) couplings for the ??N vertex on the shell structure of finite nuclei are analyzed in the framework of different nonlinear nuclearmodels based on the relativistic Hartree-Fock approximation. For the case of a dominant ??N PV coupling, it is found that if the ??-?? interaction generates an effective pion mass increasing with the nuclear density, the unrealistic effect of pions on the shell structure can be strongly reduced, keeping, roughly, the contribution of pions to the total binding energy. The ??N PS coupling increases slightly the spin-orbit splittings and the binding energy of the single-particle levels.