Absorption of ultrasonic longitudinal waves in the nematic liquid crystal 1-(trans4-hexylcyclohexyl)-4-isothiocyanatobenzene (6CHBT) was measured in the temperature (24-56oC) and frequency (3.2-100 MHz) ranges. In the region of the phase transition the anomalous absorption has been observed. This absorption rapidly increases when the frequency of the ultrasonic wave decreases. The experimental ...

The error resulting from heat conduction i the measurement ofthe ultrasonic absorption coeffcient using the transient thermoelectric method is studied analytically. An expression for the temperature increase in a tissue specimen of finite dimensions, irradiated by a focused ultrasonic transducer, isgiven as a function of spatial coordinates, time, radial and axial beam dimensions, and absorptio...

The Laser ultrasonic technique (LUT) is an interesting method to perform inspection of large aeronautical panels of complex shapes. Its non-contact feature avoids coupling problems and could improve the efficiency of the NDT inspection in the composite manufacturing industry. If the ultrasound generation process is well understood in metallic samples, the application of the technique in composi...

-The ultrasonic absorption was determined, by the transient thermoelectric method, for brain, heart, kidney, liver, tendon, and testis from cat, mouse, pig and beef. Comparison of these absorption {a) values with published values of attenuation (A) shows: (1) that the a and A coefficients have nearly the same frequency dependencies in the range 0.5-7 MHz, (2) that the magnitudes of a and A diff...

Reflection-mode photoacoustic microscopy with dark-field laser pulse illumination and high-numerical-aperture ultrasonic detection is designed and implemented in noninvasively imaged blood vessels in the skin in vivo. Dark-field optical illumination minimizes the interference caused by strong photoacoustic signals from superficial structures. A high-numerical-aperture acoustic lens provides hig...

Ultrasonic absorption measurements in the range 0.5--56 MHz, and measurements of velocity at 8.87 MHz, were made in collagen suspensions in which molecular integrity was preserved, in a range of concentrations 0.07--0.7% by weight, at 10 and 20 degrees C. Absorption and velocity values, per unit concentration, exhibited by collagen are much greater in magnitude than those exhibited by globular ...