Department of Botany, University of Toronto, Toronto, Canada M5S 1A1.
Plant Physiol. 1984 Apr;74(4):1046-9. doi: 10.1104/pp.74.4.1046.
An improved method of counting acoustic emission (AE) events from water-stressed stems of cedar (Thuja occidentalis L.) is presented. Amplified AEs are analyzed on a real time basis by a microcomputer. The instrumentation counts AE events in a fashion nearly analogous to scintillation counting of radioactive materials.The technique was applied to measuring ultrasonic AEs from the stems of cedar inside a pressure bomb. The shoots were originally fully hydrated. When the shoots are dehydrated in the bomb by application of an overpressure very few AEs were detected. When the bomb pressure is reduced after dehydration of the shoot, AE events could be detected. We conclude that ultrasonic AEs are caused by cavitation events (= structural breakdown of water columns in the tracheids of cedar) and not by the breaking of cellulose fibers in the wood.
提出了一种改良的方法，用于计算受水分胁迫的雪松（Thuja occidentalis L.）茎中的声发射（AE）事件。通过微机对放大的 AE 进行实时分析。该仪器的计数方式与放射性材料的闪烁计数非常相似。该技术应用于在压力弹内测量雪松茎的超声 AE。最初，嫩枝是完全水合的。当通过施加过压使嫩枝在弹内脱水时，检测到的 AE 事件很少。当嫩枝脱水后降低弹内压力时，可以检测到 AE 事件。我们得出结论，超声 AE 是由空化事件（= 雪松管胞中的水柱结构破裂）引起的，而不是由木材中的纤维素纤维断裂引起的。
