Abstract: A post attachment device for connecting a helmet to a head and neck support. The device includes a post anchor having a base, a button, a resilient member, a post, a retainer and a catch having a slot with a larger first section connected by a channel to a smaller second section. The button is positioned in an indention in the base with the resilient member positioned therebetween. The post extends through the button, the base and the helmet. The retainer is secured on the post adjacent the inner surface of the helmet. To secure the post attachment device, the catch is orientated over the post. The button is then depressed into the base while the catch is moved backwards to move the post into the second section of the slot.

Abstract: An x-ray sedimentation particle size analyzer in which data is taken only at particular positions along the sedimentation cell, and each such position is individually calibrated. Presentation of the data in the form of a particle size distribution curve can be accomplished very accurately using interpolation techniques. The sedimentation cell design is free of the effects of undesirable density gradients, capable of detecting and removing bubbles, capable of attaining a highly uniform dispersion of sample prior to sedimentation, and including a safety interlock device for blocking x-ray projection when the cell is being accessed.

Abstract: An x-ray sedimentation particle size analyzer in which data is taken only at particular positions along the sedimentation cell, and each such position is individually calibrated. Presentation of the data in the form of a particle size distribution curve can be accomplished very accurately using interpolation techniques. The sedimentation cell design is free of the effects of undesirable density gradients, capable of detecting and removing bubbles, capable of attaining a highly uniform dispersion of sample prior to sedimentation, and including a safety interlock device for blocking x-ray projection when the cell is being accessed.