Structural characterization Composition ratio 2 Etching 2 Etching process 2 Etching technique 2 Fuel additives 2 Hydrofluoric acid 2 Morphology 2 Porous silicon 2 Silica 2 X ray diffraction 2 biomass 2 Aldehydes 1 Alkali extraction 1 Alumina 1 Aluminum 1 Aluminum oxide 1 Amorphous silicon 1 Anisotropic magnetoresistance 1 Anisotropic magnetoresistance (AMR) 1 Bending vibrations 1 Biodiesel 1 Catalytic esterification 1 Catalytic performance 1 Cellulose 1 Cellulose and hemicellulose 1 Chemical etching 1 Co phase 1 Cobalt 1 Cocksfoot grass 1