Abstract: Described herein are compositions and methods for the storage and release of hydrogen gas using covalent organic frameworks (COFs). Advantageously, the compositions and methods described herein may be used for the facile and rapid release of hydrogen gas at near ambient temperatures. The described COFs allow for photoactivation, where the release of gas is initiated or the rate of release is increased with the COF is exposed to electromagnetic radiation, for example, UV light.

Abstract: Shock absorber systems include a drive plate having a plurality of removable lugs. The drive plate is connectable to a rotary drive shaft. The shock absorber further includes a driven plate connectable to a rotary driven shaft. A housing may be fixedly secured to either or both of the drive plate and the driven plate. The housing may have an outer wall forming a hollow center portion and a plurality of openings extending through the outer wall to the hollow center portion. Each opening of the plurality of openings may have first and second positive stops formed thereon. The shock absorber further comprises an elastomeric member disposed in the housing between the drive plate and the driven plate. The elastomeric member is configured to absorb vibration from the driven plate. Each removable lug of the plurality of removable lugs has first and second striking faces at a radially distal edge and on circumferentially opposing sides.

Abstract: Shock absorber systems include a drive plate having a plurality of removable lugs. The drive plate is connectable to a rotary drive shaft. The shock absorber further includes a driven plate connectable to a rotary driven shaft. A housing may be fixedly secured to either or both of the drive plate and the driven plate. The housing may have an outer wall forming a hollow center portion and a plurality of openings extending through the outer wall to the hollow center portion. Each opening of the plurality of openings may have first and second positive stops formed thereon. The shock absorber further comprises an elastomeric member disposed in the housing between the drive plate and the driven plate. The elastomeric member is configured to absorb vibration from the driven plate. Each removable lug of the plurality of removable lugs has first and second striking faces at a radially distal edge and on circumferentially opposing sides.

Abstract: A specially designed rotary indexing system and associated operational methods are incorporated in a downhole control device, representatively a sliding sleeve valve, having an outer tubular member in which an annular plug seat is coaxially disposed. The plug seat is resiliently expandable between a first diameter and a larger second diameter and is illustratively of a circumferentially segmented construction. The rotary indexing system is operative to detect the number of plug members that pass through and diametrically expand the plug seat, and responsively preclude passage of further plug members therethrough when such number reaches a predetermined magnitude. Such predetermined magnitude is correlated to the total rotation of an indexing system counter ring portion rotationally driven by axial camming forces transmitted to the rotary indexing system by successive plug member passage-generated diametrical expansions of the plug seat.