RESUMO
The underthrusting of continental crust during mountain building is an issue of debate for orogens at convergent continental margins. We report three-dimensional seismic anisotropic tomography of Taiwan that shows a nearly 90° rotation of anisotropic fabrics across a 10- to 20-kilometer depth, consistent with the presence of two layers of deformation. The upper crust is dominated by collision-related compressional deformation, whereas the lower crust of Taiwan, mostly the crust of the subducted Eurasian plate, is dominated by convergence-parallel shear deformation. We interpret this lower crustal shearing as driven by the continuous sinking of the Eurasian mantle lithosphere when the surface of the subducted plate is coupled with the orogen. The two-layer deformation clearly defines the role of subduction in the formation of the Taiwan mountain belt.
RESUMO
PVA-AA, an esterification product of poly(vinyl alcohol) and acryloyl chloride, was synthesized and tested for its dentine bonding ability as an additive to 2-hydroxyethyl methacrylate (HEMA). The dentine bonding strength increased significantly by increasing the concentration of PVA-AA in HEMA. The dentine tensile bonding strength attained by the mixture of 10 wt% PVA-AA in HEMA is about 38% higher than that of HEMA or Gluma bonding agent. The dentine shear bonding strength also increased by increasing the acrylate content of the PVA-AA up to about 30%. Test results of cell culturing indicate that no toxic substance is released from PVA-AA to inhibit the cell growth.
