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The effect of a static magnetic field, B, on the electrolysis of copper in aqueous solution is investigated using linear sweep voltammetry, impedance spectroscopy, chronoamperometry, rotating disk voltammetry, and analysis of fractal growth patterns. Data are obtained in fields of up to 6 T. There is a large enhancement of the electrodeposition rate (up to 300%) from concentrated CuSO4 solution (c ~1 M) when pH ≤ 1. The effect of the magnetic field is equivalent to that achieved by rotating the electrode. From the pH, viscosity, field direction and concentration dependence of the field effect, the influence of field on the complex impedance, and the equivalence of field and electrode rotation, it is established that the magnetic field influences mass transport by forced convection. Convective flow is modified on a microscopic scale in the boundary layer close to the working electrode. There is no influence on the electrode kinetics. Turbulence sets in for our cell geometry when the product of field and current density exceeds a critical value of about 1000 N/m³. The competition between gravitational and magnetic forces is dramatically exhibited by the morphology and fractal dimensionality of planar electrodeposits in a flat circular cell. Quantitative comparison is made of the magnitude of various magnetic body forces inducing convection in typical experimental conditions. The results are discussed both in terms of Aogaki's model of a streamline boundary layer, which predicts that the excess limiting current varies as B^1/3c^4/3, as observed experimentally, and in terms of the electrokinetic effect.

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Buckling loads and modes of flat composite laminates were measured and compared with theory. Laminates were subjected to simply supported boundary conditions and biaxial loading. Displacements were measured both mechanically using dial gages and optically using shadow moiré. Predictions were obtained numerically using the Galerkin method. Buckling loads were measured during 49 tests. Overall, measurements confirmed expected trends. Buckling loads increased with an increase in transverse tensile loading as predicted. Measured buckling modes were also well predicted, including an observed increase in mode number with an increase in transverse tensile loading. Measured buckling loads were not as well predicted, and substantial error was encountered during individual tests. Discrepancies between measurement and prediction are reported in terms of the percentage error in prediction. The average and standard deviation in percentage error for 49 measurements was 1.6 percent ±15.4 percent. These discrepancies are thought to be due to specimen imperfections, difficulties in simulating truly “simply supported” boundary conditions and/or nonuniform loading of the composite panels.

Red blood cell magnesium concentrations were measured in samples from 89 patients who fulfilled the diagnostic criteria for chronic fatigue syndrome and the results compared to those found in an age and sex matched group selected from the normal population. No significant difference was found. Six patients were further investigated using a magnesium loading test to determine if there was any evidence of magnesium deficiency associated with this disorder. None was found. There is therefore no indication for the use of magnesium therapy in the management of this condition.

IN NATURE of January 14, A. D. Crow and W. E. Grimshaw have discussed our method of analysing some of their experimental results, and offer the following criticisms :