Building and Fire Sciences, U.S. Forest Service, Madison, WI, 53726, USA.
Engineering Mechanics and Remote Sensing Laboratory, U.S. Forest Service, Madison, WI, 53726, USA.
Plant Cell Environ. 2015 Oct;38(10):2088-97. doi: 10.1111/pce.12532. Epub 2015 Apr 29.
The elastic properties of pit membranes are reported to have important implications in understanding air-seeding phenomena in gymnosperms, and pit aspiration plays a large role in wood technological applications such as wood drying and preservative treatment. Here we present force-displacement measurements for pit membranes of circular bordered pits, collected on a mesomechanical testing system. The system consists of a quartz microprobe attached to a microforce sensor that is positioned and advanced with a micromanipulator mounted on an inverted microscope. Membrane displacement is measured from digital image analysis. Unaspirated pits from earlywood of never-dried wood of Larix and Pinus and aspirated pits from earlywood of dried wood of Larix were tested to generate force-displacement curves up to the point of membrane failure. Two failure modes were observed: rupture or tearing of the pit membrane by the microprobe tip, and the stretching of the pit membrane until the torus was forced out of the pit chamber through the pit aperture without rupture, a condition we refer to as torus prolapse.
纹孔膜的弹性特性对理解裸子植物的空气播种现象具有重要意义，而纹孔抽吸在木材技术应用中如木材干燥和防腐处理中起着重要作用。在这里，我们展示了在介观力学测试系统上采集的圆形边缘纹孔膜的力-位移测量结果。该系统由一个附着在微力传感器上的石英微探针组成，微力传感器通过安装在倒置显微镜上的微操纵器进行定位和推进。膜位移通过数字图像分析进行测量。从未干燥的落叶松和松树早材中的非抽吸纹孔以及干燥的落叶松早材中的抽吸纹孔进行测试，以生成力-位移曲线，直至膜破裂为止。观察到两种失效模式：微探针尖端刺破纹孔膜的破裂或撕裂，以及纹孔膜的拉伸，直到环从纹孔室中通过纹孔口被迫脱出而不破裂，我们称之为环脱垂。
