Abstract: A fluidized bed jet mill for grinding particulate material comprising: a) a grinding chamber having a peripheral wall, a base, and a central axis; b) an impact target with a hollow cavity defined thereby, and with at least three apertures transversing the walls thereof, said target being mounted within said grinding chamber and centered on said central axis of said grinding chamber; and c) a plurality of sources of high velocity gas, said gas sources being mounted in said grinding chamber in said peripheral wall, arrayed symmetrically about said central axis, and oriented to direct high velocity gas along an axis substantially perpendicularly intersecting said central axis within said impact target, each of said sources of high velocity gas comprising a nozzle having an internal diameter; wherein said impact target has a cross section area in a plane parallel to said central axis, and said cross section area is greater than said cross section area of said internal diameter of said nozzle; and wherein the dist

Abstract: A method for obtaining increased flexibility and responsiveness in solid state switching devices to effect a change in voltage or field and a corresponding switching device for obtaining such result, wherein the charge transport component of the photoactivated switch is functionally separate and distinct from the photoconductive charge-generating component, the former being initially selected to provide the necessary changes with respect to voltage or field while simultaneously maintaining constant photoconductive parameters such as dark decay, spectral range, etc. in the latter component.