Kinetics of the formation of graphite oxide

The retention of ethylene glycol and X-ray-induced photo-electron spectroscopy (XPS) have been used to follow the oxidation process of two different types of graphite, a natural based and an artificial one. From both methods it is apparent that the oxidation process is almost complete by about 24–32 hr. The specific velocity of the oxidation process has been calculated from both methods, giving values in reasonable agreement; consequently it appears that these methods are consistent when the oxidation kinetics are deduced. In all cases the amount of oxygen and the specific velocity in graphite oxide from the artificial graphite is higher than that in graphite oxide from the natural based one.     

A severe outbreak of bovine mastitis assoicated with Mycoplasma bovigenitalium and Acholeplasma laidlawii

An outbreak of clinical mastitis is described in which 75 cows of a herd of 200 Friesian cows were affected in one or more quarters over a period of three months. Sixty animals failed to return to normal despite various intramammary and systemic antibiotic treatments. Heifers, dry cows and lactating animals were affected. The milk of 15 out of 53 animals tested yielded mixed cultures of Mycoplasma bovigenitalium and Acholeplasma laidlawii. Thirteen of 34 sera showed evidence of antibodies to A laidlawii.     

Use of cancellation techniques in the measurement of atmospheric crosspolarisation

Some of the errors implicit in atmospheric crosspolarisation-measurement systems are given, together with their limitations on the accuracy of the resultant measurements. A cancellation technique is described that allows the `clear-weather? performance of measurement links to be considerably improved. The limitations due to rainfall of such a cancellation system on the accuracy of crosspolarisation measurements are investigated, and the system is shown to be preferable to a conventional one.     

The use of continuous ion exchange (CIX) in copper recovery problems

Solid ion exchange using commercially available resins is suggested as a method for recovering copper directly from the slimes streams in copper recovery operations. The presence of slimes often reduces the efficiency of vat leach operations and the slimes are therefore separated and treated in a separate sulphuric acid leach stream. A similar pre-leach separation of sands and slimes is suggested in flowsheets where a fine ore grind results in the necessity to wash the leached ore in large counter-current washing and thickening units with a resulting dilution of the leach stream. Separation of the slimes, with CIX recovery of copper directly from the slimes stream, greatly reduces the size of the leached ore washing units and results in lower flows of more concentrated solution. Copper specific resins are not required in these flowsheets as the high sulphuric acid CIX eluate is passed to the sands leach unit as make up acid and all the copper may then be recovered by a copper specific solvent extraction step in the sands leach stream. Conventional equipment may be used for all the unit operations suggested. A laboratory investigation has shown that commercially available resins with suitable properties are available. Techniques of estimating a CIX process design from laboratory scale tests, for any process situation, have been developed by Davy Powergas Research and Development Division for the resins examined.     

Studies in gas-solid reactions: Part II. An experimental study of nickel oxide reduction with hydrogen

Experiments are reported on the rate of reduction of nickel oxide pellets with hydrogen over the temperature range 200° to 900°C. Measurements were also made of the pore size distribution of the reacted and unreacted specimens, by mercury porosimetry. In addition, the size of the individual grains was also determined by X-ray diffraction techniques and by electron microscopy. These physical measurements supplied most of the information required for the comparison of reduction rates with the predictions made in Part I of this study. It was found that the trends predicted by the structural model were consistent with measurements, thus the, structural model shows promise both for the interpretation of experimental data and for the semiquantitative prediction of experimental behavior.