Effects of Cyclic Loading on Velocities of Ultrasonic Waves Propagating Through Wood

The aim of this study was to determine the acoustoelastic phenomenon of wood under cyclic loading-unloading processes. Compression or tension load was repeatedly applied to wood specimens within an elastic range. Ultrasonic waves used in this study were shear and longitudinal waves, and their propagation directions were normal to, and along, the loading directions. The ultrasonic wave velocities were obtained by the sing-around method, which is a method for measuring transit time of ultrasonics. The experimental results revealed that change in the velocity of ultrasonic waves passing through wood under axial stress was a nearly linear function of applied stress level with similar slope for both loading and unloading cycles. The acoustoelastic effect of wood was found to be a repeatable and reversible phenomenon. The acoustoelastic constant seemed to maintain a fixed value regardless of the number of loading cycles. The acoustoelastic technique could be used in the determination of stress conditions of structural components in timber construction

Quadruped and Dermal Bridge Flap for Nipple Reconstruction

Background:. This report describes the authors' novel preferred method of nipple reconstruction over 10 years. Methods:. The procedure was used in 39 patients (unilateral 38, bilateral 1). The circle is designed as the new nipple cap. Then, 4 fan-shapes (one-quarter of the circle) are drawn so that the base portion is in contact with the circumference. These fanshapes are deepithelialized, and their linear portions are cut with full thickness of skin and elevated as dermal flaps. Then, the cross-type flap is elevated with sufficient subcutaneous fat. The two pairs of dermal flaps are sutured to each other on a diagonal line. Double-layer dermal bridge flaps sustain the base of the pocket. As a result, the cross flap becomes a birdcage-like tower. The rolled auricular cartilage is placed into the pocket. Results:. In one early case, the cartilage was exposed. Early postoperatively, the other three cases underwent reoperation during other procedures because the reconstructed nipple was too large or too small. The projection of the flap was designed to be 7–15 mm (average, 9.3 mm). The average follow-up period was 25.7 ± 22.0 months. The reconstructed nipple projection was maintained at 4.4 ± 2.4 mm (maintenance rate, 48.4% ± 27.0%). Conclusions:. All scars were contained within the periareolar region and thus could be completely camouflaged by tattooing. The perfusion of the skin flap is stable because of sufficient circulation from quadruped pedicle. The cartilage supported by the double-layered dermal bridge flaps contributes to nipple projection. We recommend it for patients seeking nipple reconstruction