Fig. 4From: Microbial biogas production from hydrolysis lignin: insight into lignin structural changesThe 2D HSQC NMR spectral regions of interest (aliphatic region) for birch samples and the structures of lignin inter-unit linkages. The letters found in the spectra refer to the substructures shown below the spectra. For well-resolved correlation peaks, contours are color coded to match their structures shownBack to article page