11,212 research outputs found
Covert cavitation: Spectral peak suppression in the acoustic emissions from spatially configured nucleations
Dual laser-nucleation is used to precisely configure two cavitation bubbles within a focused ultrasound field of f0 = 692 kHz, in proximity to the tip of a needle hydrophone. With both bubbles responding in the f0/2 sub-harmonic regime, confirmed via ultra-high speed shadowgraphic imaging, an emission spectrum with no sub-harmonic content is demonstrated, for an inter-bubble spacing ≈λ0. A spectral model for periodic shock waves from multiple nucleations demonstrates peak suppressions at nf0/2 when applied to the experiment, via a windowing effect in the frequency domain. Implications for single-element passive detection of cavitation are discussed
A Cephalopod Approach to Rethinking about the Importance of the Bohr and Haldane Effects
This study concerns the physiological implications of the Bohr
and Haldane effects and the buffer values in the blood from the cephalopods
Nautilus pompilius, Octopus macropus, Sepia latimanus, Nototodarus sloani
philippinensis, and Sepioteuthis lessoniana. All species studied except one
(Nautilus) have Bohr and Haldane coefficients numerically higher than unity,
and the two effects were found to be nearly identical in all cases, in accord with
the theoretical prediction of Wyman (1964). However, the functional Haldane
coefficient was significantly lower than the Haldane coefficient in two cases
(Sepia and Sepioteuthis). Buffer values were highest in the two species with the
lowest oxygen requirement (Nautilus and Octopus), whereas the three fast swimmers
studied (Nototodarus, Sepia, and Sepioteuthis) display comparatively low
buffer values. It is concluded that the large Bohr effects seen in four of the five
species may have their primary effect on oxygen loading in the gills
Reinforced carbon-carbon oxidation behavior in convective and radiative environments
Reinforced carbon-carbon, which is used as thermal protection on the space shuttle orbiter wing leading edges and nose cap, was tested in both radiant and plasma arcjet heating test facilities. The test series was conducted at varying temperatures and pressures. Samples tested in the plasma arcjet facility had consistently higher mass loss than those samples tested in the radiant facility. A method using the mass loss data is suggested for predicting mission mass loss for specific locations on the Orbiter
Uncertainty estimation via preflight test procedures for a space stabilized inertial navigation system
Preflight operation and alignment of space stabilized inertial navigation system for vertical takeoff aircraf
Respiratory Properties of Blood and Pattern of Gas Exchange in the Lungfish Neoceratodus forsteri (Krefft)
Blood respiratory properties and gas exchange patterns have been studied in the lungfish Neoceratodus. O2 - Hb dissociation curve reveals a high affinity for O2 (P50 of 11 mm Hg at PCO2 3.5 mm Hg). No Root effect but a pronounced Bohr effect was discernible. Temperature exerted only a minor influence on the affinity for O2. The CO2 dissociation curves conform to the shape observed in other classes of vertebrates and show a steep initial portion. The buffering capacity of the blood was low being 13.3 mMol/1/pH. An increased buffering power upon reduction of Hb was apparent. During rest in well oxygenated water, gill breathing prevailed entirely. Pulmonary arterial blood assumed to represent mixed arterial blood characteristically showed a Pco2 averaging 3.5 mm Hg. PaO2 was 40 mm Hg corresponding to an O2 saturation of 95%. The pulmonary venous blood showed gas partial pressures in equilibrium with those in pulmonary arterial blood and air, documenting the minor importance of the lung as a gas exchanger during these conditions. When the fish was artificially exposed to air PaO2 diminished to 10-15 mm Hg with a concurrent increase in PaCO2 to 20 mm Hg in 30 min. While the lung performed well as an O2 absorber during air exposure it was totally inefficient in eliminating CO2. The data indicate that Neoceratodus is unfit to live out of water for any length of time
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