List of Articles Superficial gas velocity Open Access Article Abstract Page Full-Text 1 - Comparison of the Performance of Internal and External Loop Air-lift Reactors for Water Treatment by Activated Sludge Mohammad Ali Salehi Nasrin Hakimghiasi 10.22034/jest.2020.22686.3180 Open Access Article Abstract Page Full-Text 2 - Experimental Study of Interfacial Friction Factor and Shear Stress in Counter-current Two-phase Flow in a Vertical Pipe Arash Ghafouri Ashkan Ghafouri Abbas kosarineia Alireza Daneh-Dezfuli