TJ Mechanical engineering and machinery 7 TD Environmental technology. Sanitary engineering 5 Chemical engineering 3 Soils. Soil science. Including soil surveys, soil chemistry, soil structure, soil-plant relationships 3 Biodiesel fuels 2 Miscellaneous motors and engines.Including gas, gasoline, diesel engines 2 Acids 1 Algorithms 1 Animal feeds and feed mills. Pet food industry 1 Biotechnology 1 Computer engineering. Computer hardware 1 Electronics 1 Energy conservation 1 Enviromental management 1 Environmental engineering 1 Environmental protection 1 Extraction (Chemistry) 1 Food processing and manufacture 1 Medical botany (General) 1 Municipal refuse. Solid wastes 1 Nanoparticles 1 Power resources 1 Processes, operations, and techniques 1 Rural and farm sanitary engineering 1 SB Plant culture 1 Sewage disposal systems 1 Sewerage 1 Soil dynamics 1 TK Electrical engineering. Electronics. Nuclear engineering 1 TP Chemical technology 1