Basic Investigation of Built-Up-Edge

The formation of a built-up-edge has been differentiated into two mechanisms, that is, adhesion or nucleation of built-up-edge and growth of adhered metal. As to adhesion, the affinity between tool and work material has been investigated experimentally. The findings are that the position of a metal in the periodic table and the solubilities of the mating metals are substantially associated with the strength of adhesion. Although the temperature at the interface is primarily significant to accelerate the adhesion, the effect of relative velocity has been revealed to be negligible. Theoretical analogy and experimental analysis have led to a conclusion that work-hardenability is a requisite condition for the existence and growth of built-up-edge.

A tongue retaining device and sleep-state genioglossus muscle activity in patients with obstructive sleep apnea

To define the effect of a tongue retaining device (TRD) on genioglossus (GG) muscle activity in seven obstructive sleep apnea subjects, two overnight sleep studies were carried out with two TRDs. TRD-A had no anterior bulb and incorporated two electrodes to record GG electromyographic (EMG) activity. TRD-B had a bulb and it had electrodes similar to those in TRD-A. Episodes of apnea/hypopnea (AH) were analyzed during both rapid eye movement (REM) and non-REM (NREM) sleep. The peak GG muscle activity was measured for the breath immediately before the AH (pre-AH), for the first (first-E) and last (last-E) inspiratory efforts during the AH, and for the first breath after the AH (post-AH). The time lag between the peak GG EMG activity and the maximum inspiratory effort was calculated. The AH index decreased with both TRDs. The peak GG EMG activity preceded the maximum inspiratory effort throughout the periods, however the time lag changed considerably with TRD-A. The time lags with TRD-A and TRD-B differed significantly for the first-E and the last-E during NREM sleep and for the first-E during REM sleep. The TRD reduces AH severity, normalizes the time lag, and counteracts fluctuating GG EMG activity observed when no bulb is present.