Agglomerated talc was prepared by the wet granulation method using a planetary mixer and a high speed mixer. The effect of the amount of water added and granulation time for the planetary mixer on the physical properties of the agglomerated talc were investigated by a response surface design. The speed of the agitator and granulation time for the high speed mixer were selected as the two independent variables to study the granulation processing using the same statistical design. Several characteristics of the product prepared by a planetary mixer or high speed mixer were well expressed as a quadratic function of the two independent variables studied in coded level. By superimposing contour plots of granule friability and percent fine of granule, a region was obtained where the requirements of friability and percent fines could be satisfied by controlling the processing variables. The optimal granulation condition was chosen from that region. The values of the measured responses of the agglomerated talc produced using the optimal granulation condition agreed well with the predicted values obtained from the regression equations.
Borghi, Alessandro
Castelli, Daniele
Lombardo, Bruno
Visonà, Dario
Granulite-facies garnet-bearing metapelites, metabasics and calc-silicate rocks from the lower metamorphic complex (Kharta Gneiss) of the Greater Himalayan Crystallines in the Kharta region of S Tibet, E Himalaya, preserve textural and chemical evidence for prograde equilibration at temperatures of at least 700-720degreesC and pressures around 8 kbar during the main event of the Himalayan metamorphism. Post-deformational reaction textures include clinopyroxene (+/- orthopyroxene) - plagioclase symplectites after garnet in calc-silicate rocks, and cordierite +/- spinel coronas on sillimanite and garnet in metapelite granulites. These assemblages indicate a decompressional pressure-temperature path that is confirmed by the geothermobarometry of zoned and symplectite minerals as well as by calculated phase equilibria. Isothermal decompression through ca. 3 kbar occurred at temperatures of about 700degreesC, and was followed by further decompression to P similar to 3 kbar, and T similar to 710degreesC. At this point, decompression was replaced by quasi-isobaric cooling ending in the andalusite stability field at P ca. 2.5 kbar. The P-T path of the Kharta Gneiss appears to be similar to those inferred for the lower Greater Himalayan Crystallines exposed in the nearby Dudh Kosi and middle Arun valleys of eastern Nepal. This type of clockwise P-T path, with most of the exhumation occurring at relatively constant metamorphic temperatures, requires a high exhumation rate and suggests that extrusion tectonics of crustal-scale wedges may have been operative during post-collisional exhumation of the Greater Himalayan Crystallines.
Granulite-facies garnet-bearing metapelites, metabasics and calc-silicate rocks from the lower metamorphic complex (Kharta Gneiss) of the Greater Himalayan Crystallines in the Kharta region of S Tibet, E Himalaya, preserve textural and chemical evidence for prograde equilibration at temperatures of at least 700-720degreesC and pressures around 8 kbar during the main event of the Himalayan metamorphism. Post-deformational reaction textures include clinopyroxene (+/- orthopyroxene) - plagioclase symplectites after garnet in calc-silicate rocks, and cordierite +/- spinel coronas on sillimanite and garnet in metapelite granulites. These assemblages indicate a decompressional pressure-temperature path that is confirmed by the geothermobarometry of zoned and symplectite minerals as well as by calculated phase equilibria. Isothermal decompression through ca. 3 kbar occurred at temperatures of about 700degreesC, and was followed by further decompression to P similar to 3 kbar, and T similar to 710degreesC. At this point, decompression was replaced by quasi-isobaric cooling ending in the andalusite stability field at P ca. 2.5 kbar. The P-T path of the Kharta Gneiss appears to be similar to those inferred for the lower Greater Himalayan Crystallines exposed in the nearby Dudh Kosi and middle Arun valleys of eastern Nepal. This type of clockwise P-T path, with most of the exhumation occurring at relatively constant metamorphic temperatures, requires a high exhumation rate and suggests that extrusion tectonics of crustal-scale wedges may have been operative during post-collisional exhumation of the Greater Himalayan Crystallines.
Garnet E. Peck
John E. Christian
Gilbert S. Banker
Abstract A procedure has been developed for the determination of moisture in an organic material by the thermalization of neutrons. The method developed utilized commercially available equipment designed for depth moisture determinations of soils. The moisture content of three series (replications) of water in lactose U.S.P. was determined at various concentration levels by the neutron method and by two official methods (gravimetric and Karl Fischer titration). The number of thermal neutrons produced at the various moisture concentrations prepared were plotted against the corresponding moisture content indicated by each of the two official moisture determination methods. Regression curves were prepared using least squares calculations. With t tests it was shown that the means of the slopes of the three series were estimates of the true slope of the regression curves, and 0.95 confidence limits were also set on the slopes. The applicability of this new method of determining the moisture content of pharmaceutical systems is discussed.