Structural Differences Between Lignin Model Polymers Synthesized from Various Monomers

In a plant cell wall, lignin is synthesized from several monomeric precursors, combined in various ratios. The variation in monomer type and quantity enables multifunctional role of lignin in plants. Thus, it is important to know how different combinations of lignin monomers impact variability of bond types and local structural changes in the polymer. Lignin model polymers are a good model system for studies of relation between variations of the starting monomers and structural variations within the polymer. We synthesized lignin model polymers from three monomers, CF??based on coniferyl alcohol and ferulic acid in monomer proportions 5:1 and 10:1 (w/w), CP??based on coniferyl alcohol and p-coumaric acid in proportion 10:1 (w/w) and CA??based on pure coniferyl alcohol. We studied structural modifications in the obtained polymers, by combining fluorescence microscopy and spectroscopy, FT-IR and Raman spectroscopy, in parallel with determination of polymers?? molecular mass distribution. The differences in the low M _w region of the distribution curves of the 10:1 polymers in comparison with the CA polymer may be connected with the increased content of C=C bonds and decreased content of condensed structures, as observed in FT-IR spectra and indicated by the analysis of fluorescence spectra. The 5:1 CF polymer contains a different type of structure in comparison with the 10:1 CF polymers, reflected in its simpler M _w distribution, higher homogeneity of the fluorescence emitting structures and in the appearance of a new high-wavelength emission component. We propose that this component may originate from ??-conjugated chains, which are longer in this polymer. The results are a contribution to the understanding of the involvement of structural variations of lignin polymers in the cell wall structural plasticity.     

To reduce and not to reduce resource consumption? That is two questions

Recent research shows that because they rely on separate goals, cognitions about not performing a behaviour are not simple opposites of cognitions about performing the same behaviour. Using this perspective, two studies (N = 758 & N = 104) examined the psycho-social determinants of reduction in resource consumption. Results showed that goals associated with reducing versus not reducing resource consumption were not simple opposites (Study 1). Additionally, the discriminant validity of the Theory of Planned Behaviour constructs associated with reducing versus not reducing resource consumption was demonstrated (Study 1 & 2). Moreover, results revealed the incremental validity of both Intentions (to reduce and to not reduce resource consumption) for predicting a series of behaviours (Study 1 & 2). Finally, results indicated a mediation role for the importance of ecological dimensions on the effect of both Intentions on a mock TV choice and a mediation role for the importance of non ecological dimensions on the effect of Intention of not reducing on the same TV choice. Discussion is organized around the consequences, at both theoretical and applied levels, of considering separate motivational systems for reducing and not reducing resource consumption.