Experimental study on sound absorption of hollow glass beads with inner closed cavities under low-frequency vertical vibration.

Normal incidence sound absorption coefficients α of hollow glass beads were measured under a sinusoidal vertical vibration of 10 Hz. It was found that α depends on the vibrational displacement amplitude. As the displacement amplitude increased, the frequency width of the peak extended toward low frequencies.

Effect of acoustically-induced elastic softening on sound absorption coefficient of hollow glass beads with inner closed cavities.

This study investigated the effects of sound wave magnitude on the sound absorption characteristics of granular materials. The normal incidence sound absorption coefficients of the hollow glass bead packings were measured with different incident sound pressure levels. The measurement results exhibited spectral peaks of sound absorption coefficients at several frequencies, implying that the first peak was caused by the resonance of the hollow glass beads as a layer.

Effect of casing on sound absorption characteristics of fine spherical granular material.

To determine sound absorption coefficients of fine granular materials, the materials must be cased to suppress their flowability. In this study, effects of casing on the sound absorption coefficients of fine granular materials were investigated. The normal incidence sound absorption coefficients of cased hollow glass beads were measured using cylindrical impedance tubes.

Relationship between body iron stores and diquat toxicity in male Fischer-344 rats.

The effects of body iron stores on diquat (DQ)-induced toxicity were examined in male Fischer-344 rats, which are sensitive to this herbicide. The rats (5 weeks old) were fed diets containing 40 (lower iron storage [LIS] group) or 320 ppm iron (higher iron storage [HIS] group) for 5 weeks. The concentrations of nonheme iron and ferritin in the liver and kidney were significantly higher in the HIS group than in the LIS group (P<0.