The damage behaviors of a titanium matrix composite shaft under torsion loading were monitored using the acoustic emission technique. The composite shaft with SiC fibers at ±45° orientations was prepared by ...The damage behaviors of a titanium matrix composite shaft under torsion loading were monitored using the acoustic emission technique. The composite shaft with SiC fibers at ±45° orientations was prepared by the solid-state fabrication process. Both the torsional rigidity and torsional strength of the TMC shaft were improved by SiC fibers. The acoustic emission responses during the loading-unloading-reloading, under quasi-static and cyclic torsion tests were investigated. Multiple acoustic emission signals were grouped as mechanical noise, matrix deformation, interface debonding and fiber fracture using amplitude, waveform shape and frequency centroid parameters. A substantial reduction of signals generated by matrix deformation was found in the reloading test. During the quasi-static torsion test, interface debonding and progressive breaks of SiC fibers occurred. According to different acoustic emission behaviors, the failure process in the torsion fatigue test can be divided into three stages: the initial stage, the fiber fracture stage and the fast fracture stage.展开更多
Following intrathecal injection of fluorescent tracers,ex vivo imaging of brain vibratome slices has been widely used to study the glymphatic system in the rodent brain.Tracer penetration into the brain is usually qua...Following intrathecal injection of fluorescent tracers,ex vivo imaging of brain vibratome slices has been widely used to study the glymphatic system in the rodent brain.Tracer penetration into the brain is usually quantified by image-processing,even though this approach requires much time and manual operation.Here,we illustrate a simple protocol for the quantitative determination of glymphatic activity using spectrophotofluorometry.At specific time-points following intracisternal or intrastriatal injection of fluorescent tracers,certain brain regions and the spinal cord were harvested and tracers were extracted from the tissue.The intensity of tracers was analyzed spectrophotometrically and their concentrations were quantified from standard curves.Using this approach,the regional and dynamic delivery of subarachnoid CSF tracers into the brain parenchyma was assessed,and the clearance of tracers from the brain was also determined.Furthermore,the impairment of glymphatic influx in the brains of old mice was confirmed using our approach.Our method is more accurate and efficient than the imaging approach in terms of the quantitative determination of glymphatic activity,and this will be useful in preclinical studies.展开更多
文摘The damage behaviors of a titanium matrix composite shaft under torsion loading were monitored using the acoustic emission technique. The composite shaft with SiC fibers at ±45° orientations was prepared by the solid-state fabrication process. Both the torsional rigidity and torsional strength of the TMC shaft were improved by SiC fibers. The acoustic emission responses during the loading-unloading-reloading, under quasi-static and cyclic torsion tests were investigated. Multiple acoustic emission signals were grouped as mechanical noise, matrix deformation, interface debonding and fiber fracture using amplitude, waveform shape and frequency centroid parameters. A substantial reduction of signals generated by matrix deformation was found in the reloading test. During the quasi-static torsion test, interface debonding and progressive breaks of SiC fibers occurred. According to different acoustic emission behaviors, the failure process in the torsion fatigue test can be divided into three stages: the initial stage, the fiber fracture stage and the fast fracture stage.
基金the National Natural Science Foundation of China(31871167 and 81920108016)China Postdoctoral Science Foundation(2016M601882)+2 种基金Suzhou Science and Technology Research Project(SYS201669 and SYS201709)Postdoctoral Science Foundation of Jiangsu Province,China(1601083C)Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Following intrathecal injection of fluorescent tracers,ex vivo imaging of brain vibratome slices has been widely used to study the glymphatic system in the rodent brain.Tracer penetration into the brain is usually quantified by image-processing,even though this approach requires much time and manual operation.Here,we illustrate a simple protocol for the quantitative determination of glymphatic activity using spectrophotofluorometry.At specific time-points following intracisternal or intrastriatal injection of fluorescent tracers,certain brain regions and the spinal cord were harvested and tracers were extracted from the tissue.The intensity of tracers was analyzed spectrophotometrically and their concentrations were quantified from standard curves.Using this approach,the regional and dynamic delivery of subarachnoid CSF tracers into the brain parenchyma was assessed,and the clearance of tracers from the brain was also determined.Furthermore,the impairment of glymphatic influx in the brains of old mice was confirmed using our approach.Our method is more accurate and efficient than the imaging approach in terms of the quantitative determination of glymphatic activity,and this will be useful in preclinical studies.
