ABSTRACT
High-power ultrasound has been known to promote penetration of liquids into porous materials. This work presents results of experimental investigations of the influence of 40 kHz high-power ultrasound on wetting processes of papers. Wetting was monitored by the measurement of the attenuation of 0.5-9 MHz ultrasound transmitted through the immersed sample. The samples were sized papers with contact angles 40 degrees, 70 degrees and 110 degrees, and the immersion liquids were isopropanol-water mixtures of 0-100% isopropanol concentration. The investigation showed that application of high-power ultrasound resulted in faster sorption processes. However, the absolute reduction in time to reach the stationary state was not very great.
ABSTRACT
The ultrasound examination was carried out by means of a crystal with a 40 degrees sector scan, which was pressed either against the eyelid or directly against the sclera. The real-time display was obtained by either A-mode, B-mode or combined A/B-mode scanning. In clinical applications, both the resolution capacity and the sensitivity of the device were good. A-mode scanning gave the greatest accuracy in amplitude measurement, while the A/B-mode yielded the most concrete topographic picture of the target.
Subject(s)
Eye Diseases/diagnosis , Ultrasonography , Humans , Methods , Ultrasonics/instrumentationABSTRACT
The construction and imaging capabilities of a scanning high resolution ultrasonic microscope are considered in this paper. Theoretical expressions for the resolution limits of the microscope and some of the most important properties of the ultrasonic lenses are given. Ultrasonic through-transmission and back-scattering images of different objects are presented and a quasi-three-dimensional display mode is introdued. A resolution of about 4 micron is demonstrated at 300 MHZ by the present ultrasonic microscope.
