Magnetic suppression of convection in protein crystal growth processes

Magnetization force caused by a magnetic field gradient (F-m) is a body for ce and can cause buoyancy. We numerically simulate the natural convection a rising from the depletion of protein concentration around a growing protein crystal when an upward magnetization force acts on the solution, The numer ical predictions reveal that an upward magnetization force can damp convect ion. When a magnetic field gradient mu H-2(0)(dH/dz) = -685 T-2/m is applie d, the maximum flow velocity is reduced by about 50% and the velocity in th e vicinity of the crystal is reduced by about 24%. Due to the low electric conductivity of the solution, the contribution of the Lorentz force is negl igible. When mu H-2(0)(dH/dz) = -1370 T-2/m, the upward magnetization force (F-m approximate to pg) damps convection completely. Our study shows a new method of controlling convection in the process of protein crystal formati on. (C) 2001 Elsevier Science B.V. All rights reserved.