Abstract: A method is disclosed for purifying aluminum nitride produced by carbothermal reaction of aluminum oxide, carbon and nitrogen. Precursor pellets including aluminum oxide and carbon are exposed to nitrogen under conditions sufficient to carbothermally produce aluminum oxide, thereby producing aluminum nitride pellets having surface portions relatively rich in thermal conductivity-lowering and color-causing impurities compared to core portions of the aluminum nitride pellets. Significant amounts of the surface portions are thereafter removed to thereby significantly increase the purity of the aluminum nitride pellets.

Abstract: A semiconductor image sensor comprises an array of charge collection elements buried within the semiconductor for collecting charge photogenerated in response to the image. This sensor is easily configured to discern changes in an image. One or more charge transfer devices (CTD's) of an array are associated with each column of charge collection elements. For readout, the charge collected by each charge collection element is transferred to an associated storage cell of an array CTD associated with the column in which that charge collection element is disposed.For discernment of moving targets or image changes, a difference between the charge collected by a given charge collection element during a first frame and a second frame is determined.

Abstract: An overhead transportation system comprising for a depending and longitudinally traversible vehicle an overhead trackway as a pair of longitudinally slottedly vented tubular conduits maintained above the earth's surface with a series of pillars and having an overlying protective shield. The vehicle powering means comprises a pair of co-traversible jet engines situated within respective conduits and connected to the underlying vehicle with a dual-arms hangar means along which arms the engines' fuel-line extends. The trackway is lubricated from a longitudinally extending lubeline with syncronizeably operated nozzles spaced therealong and communicating with the conduit innerwall, and a longitudinally extending troughline collects the liquid lubricant, there being provision for re-cycling the lubricant for high-pressure re-injection into the conduits through said lubeline nozzles.