Abstract: A propulsion system for a manually-operated mobility device includes a hand rim configured to receive a propulsion force from a user of the manually-operated mobility device, a wheel hub fixedly attached to a wheel for the manually-operated mobility device, and a planetary gear system including a sun gear, a ring gear, and one or more planetary gears disposed between the sun gear and the ring gear. The one or more planetary gears are supported by a planet carrier. One of the sun gear and the ring gear is fixedly coupled to the hand rim and the other of the sun gear and the ring gear is fixedly coupled to the wheel hub.

Abstract: An X-ray diffraction apparatus provides analysis in either transmission or reflective mode and easy conversion between the two modes. An X-ray source and X-ray detector are each connected to a different circle of a goniometer. The two circles may be rotated independently to position the source and detector on the same side of a sample library for reflection mode operation, or on opposite sides of the sample library for transmission mode operation. The sample library has a horizontal orientation that allows open sample containers of the library to maintain the sample without spillage, and it connects to an XYZ stage that can move in three dimensions. The system may use a beamstop, and the goniometer and XYZ stage be motorized and controlled for automated sample analysis.