Agricultural and forest residues obtained after harvesting are promising renewable sources, suitable as a source of pulp for cellulose nanocrystal manufacturing. Cavitation-assisted softening of the lignin-carbohydrate matrix offers sample opportunity for cellulose fibril liberation and degradation of amorphous cellulose. The present work addresses cavitation assisted cellulose fibril and crystal liberation and film forming properties of the supernatant phase of treated agricultural and forest residues. The effectiveness of this method has been evaluated according to crystallinity indices and hydrogen bond energies, as measured by FT-IR analysis. It has been observed that the use of cavitation increased the crystallinity and caused partial removal and degradation of the lignin matrix. Overall, it appears that considerable improvement of crystallinity can be obtained from agricultural and forest residues through the use of cavitation.
In this chapter we briefly discuss the concept of forest taking into account the provision of different goods and services. We provide some technical information on the forest classification systems adopted in Europe which are then reflected in the different roles and meanings that Europeans give to forests. We give a special emphasis to urban forests considering their origins, typologies and indicators. The importance of urban forests is analyzed including the role that forest areas and green spaces can play in contemporary (sustainable) cities. Different citizens' attitudes towards urban environment are also discussed considering the cultural differences existing at European level. The effects of urban forests on urban environments (i.e., hydrology climate, air quality, biodiversity) and human health are finally discussed. This chapter considers the social role of urban forest and the relationship existing between forests and communities through emerging approaches such as community forests.
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