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A technique to measure the dynamic mechanical properties of human skin in vivo is described. The technique measures the propagation and attenuation of shear waves in skin tissue over a range of frequencies (8-1016 Hz). Results show that both the propagation velocity and attenuation of shear waves in skin are highly dependent upon the water content of the stratum corneum. The technique was used to measure the dynamic mechanical properties of the skin on the back of the left hand for a group of 16 men ranging in age from 24-63 years. The results suggest that aged skin has a lower water content than the skin of younger men.

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High and uniform absorbency of cotton fabrics is a desirable quality in nearly every wet- finishing operation and in many finished fabrics; yet absorbency-measuring tests which have been employed up to the present time are largely inadequate and arbitrary. A test method is described here which is more suitable in that it meets the requirements of wetting the fabric quickly from one side while it is under pressure and allowing the comparison of different fabrics in a readily understandable manner. Using a glass filtering funnel to provide a wet porous plate and a flowmeter for measuring rates, the apparatus is easily assembled and calibrated. The test is simple and rapid and per mits numerical evaluation of both rate of absorption and total or ultimate absorption, largely independently of apparatus characteristics. The separate evaluation of these absorbency factors and the elimination of timing procedures set this test apart from those previously published. The method is readily adaptable to the investigation of many liquid-absorbent relationships. Application of the test to the evaluation of absorbency of purified cotton fabrics has led to a plausible explanation of their absorption behavior as being due largely to spaces within the fabric rather than to absorption characteristics of the fiber itself.

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