目的通过脉冲噪声分别对豚鼠进行30、15次的暴露,分析比较豚鼠的听力学变化,探索建立隐性听力损失模型的适合条件。同时给予氢气,探究其对隐性听力损失的预防作用。方法选取ABR听阈正常的豚鼠16只,随机分为4组:空白对照组、脉冲噪声30...目的通过脉冲噪声分别对豚鼠进行30、15次的暴露,分析比较豚鼠的听力学变化,探索建立隐性听力损失模型的适合条件。同时给予氢气,探究其对隐性听力损失的预防作用。方法选取ABR听阈正常的豚鼠16只,随机分为4组:空白对照组、脉冲噪声30次组、脉冲噪声15次组、氢气吸入+脉冲噪声15次组。脉冲噪声压力峰值为163 dB SPL,脉宽为0.25ms,间隔时间为6.5s。分别于脉冲噪声暴露前及暴露后24h进行听性脑干反应测定。结果通过统计学分析发现,豚鼠在30次脉冲噪声暴露24h后,其ABR短声阈值及短纯音(16 kHz 70 dB SPL)Ⅰ波幅值产生明显改变,具有统计学意义;15次脉冲噪声暴露组豚鼠其各项听力学指标都发生显著改变;氢气预处理组同单纯脉冲噪声暴露15次组的暴露24h后听力学指标相比,其ABR短声阈值及短纯音(16 kHz 70 dB SPL)Ⅰ波幅值存在统计学差异。结论本研究中脉冲噪声暴露30次及15次均对豚鼠听力产生显著影响。其中脉冲噪声暴露15次的豚鼠,其各项听力学指标都符合隐性听力损失的听力学特点,脉冲噪声暴露15次是建立隐性听力损失动物模型的可行条件。此外,氢气防护组较单纯脉冲噪声暴露组,听力学指标存在显著差别,表明氢气对隐性听力损失具有预防作用,为进一步的分子机制研究提供直接实验依据。展开更多
The rheology of rocks at depth remains a key point in earth sciences. Deformation of high-temperature–highpressure rocks from the subduction zone has not been fully studied; in particular, the deformation behavior of...The rheology of rocks at depth remains a key point in earth sciences. Deformation of high-temperature–highpressure rocks from the subduction zone has not been fully studied; in particular, the deformation behavior of eclogites remains poorly understood. This research is focused on the microstructure and fabric of retrograded eclogites from the Hongqiyingzi Complex in Chicheng, north Hebei, China, based on photomicrography, scanning electron microscopy(SEM) and electron backscattered diffraction(EBSD) analysis. The analytical results show that plastic deformation occurred in the garnets during exhumation, but they do not show an obvious lattice preferred orientation(LPO). This can be interpreted as being caused by the simultaneous activation of multiple slip systems in the garnets during deformation by dislocation creep. The plagioclases have a special fabric; the(001) LPO presents a maximum in Z direction which can be correlated with a new [100](001) slip system. The misorientation angle distribution(MAD) of the plagioclases in the deformed retrograded garnet augens shows a special bimodal distribution with peaks in both a low-angle range(<40?) and a high-angle range(>140?). In the retrograded garnet augens(i.e. "white eye socket" garnets) the maximum peak moves from a high-angle range to a low-angle range when we analyze only those plagioclases surrounding the residual garnet porphyroclast. Deformation behavior is controlled by the crystallographic orientation of the host grain and the grain boundary sliding process. Hornblendes in different layers and the retrograded garnet augens show almost the same strong LPO patterns, which are correlated with the [001](010) slip system; and MAD diagrams show a peak in a low-angle range(<40?). Integrating recent studies on metamorphism and geochronology, we argue that ductile deformation occurred during the exhumation periods together with retrograded metamorphism.展开更多
Gyirong basin and its adjacent area are located at a special position in the Himalayan orogen, where the south Tibetan detachment system (STDS) and N-S trending rift converged. The north Himalayan orogen here can be d...Gyirong basin and its adjacent area are located at a special position in the Himalayan orogen, where the south Tibetan detachment system (STDS) and N-S trending rift converged. The north Himalayan orogen here can be divided into five petrologic-tectonic units successively from south to north: 1) the Greater Himalayan crystalline complex (GHC); 2) the STDS shear zone; 3) the Tethyan Himalayan sedimentary sequence (THS); 4) the late Cenozoic sedimentary basins, such as Gyirong and Oma basins; and 5) the Malashan gneiss dome. Structural studies show that this area experienced four stages of deformation: 1) the earlier south-directed thrusting, preserved both in the GHC and THS; 2) top-down-to-north slip along the STDS, normal faults related to this slip formed the early controlling structures of the Cenozoic basins,and the tilted pattern of the blocks between the basins indicated a north-directed slip; 3) east-west extension, the resultant N-S trending normal fault formed the eastern boundary of the basins; and 4) late gravitational collapse. Zircon SHRIMP U-Pb dating on the syn-deformational (leuco-) granite along the STDS indicates that the major activity of the STDS occurred at ca. 26 Ma, but its onset may have begun as early as ca. 36 Ma.展开更多
文摘目的通过脉冲噪声分别对豚鼠进行30、15次的暴露,分析比较豚鼠的听力学变化,探索建立隐性听力损失模型的适合条件。同时给予氢气,探究其对隐性听力损失的预防作用。方法选取ABR听阈正常的豚鼠16只,随机分为4组:空白对照组、脉冲噪声30次组、脉冲噪声15次组、氢气吸入+脉冲噪声15次组。脉冲噪声压力峰值为163 dB SPL,脉宽为0.25ms,间隔时间为6.5s。分别于脉冲噪声暴露前及暴露后24h进行听性脑干反应测定。结果通过统计学分析发现,豚鼠在30次脉冲噪声暴露24h后,其ABR短声阈值及短纯音(16 kHz 70 dB SPL)Ⅰ波幅值产生明显改变,具有统计学意义;15次脉冲噪声暴露组豚鼠其各项听力学指标都发生显著改变;氢气预处理组同单纯脉冲噪声暴露15次组的暴露24h后听力学指标相比,其ABR短声阈值及短纯音(16 kHz 70 dB SPL)Ⅰ波幅值存在统计学差异。结论本研究中脉冲噪声暴露30次及15次均对豚鼠听力产生显著影响。其中脉冲噪声暴露15次的豚鼠,其各项听力学指标都符合隐性听力损失的听力学特点,脉冲噪声暴露15次是建立隐性听力损失动物模型的可行条件。此外,氢气防护组较单纯脉冲噪声暴露组,听力学指标存在显著差别,表明氢气对隐性听力损失具有预防作用,为进一步的分子机制研究提供直接实验依据。
基金supported by the National Natural Science Foundation of China(Grant No.41430207)the National Basic Research Program of China(Grant No.2013CB429804)the Special Fund for Basic Research of Central Universities(Grant No.310827161010)
文摘The rheology of rocks at depth remains a key point in earth sciences. Deformation of high-temperature–highpressure rocks from the subduction zone has not been fully studied; in particular, the deformation behavior of eclogites remains poorly understood. This research is focused on the microstructure and fabric of retrograded eclogites from the Hongqiyingzi Complex in Chicheng, north Hebei, China, based on photomicrography, scanning electron microscopy(SEM) and electron backscattered diffraction(EBSD) analysis. The analytical results show that plastic deformation occurred in the garnets during exhumation, but they do not show an obvious lattice preferred orientation(LPO). This can be interpreted as being caused by the simultaneous activation of multiple slip systems in the garnets during deformation by dislocation creep. The plagioclases have a special fabric; the(001) LPO presents a maximum in Z direction which can be correlated with a new [100](001) slip system. The misorientation angle distribution(MAD) of the plagioclases in the deformed retrograded garnet augens shows a special bimodal distribution with peaks in both a low-angle range(<40?) and a high-angle range(>140?). In the retrograded garnet augens(i.e. "white eye socket" garnets) the maximum peak moves from a high-angle range to a low-angle range when we analyze only those plagioclases surrounding the residual garnet porphyroclast. Deformation behavior is controlled by the crystallographic orientation of the host grain and the grain boundary sliding process. Hornblendes in different layers and the retrograded garnet augens show almost the same strong LPO patterns, which are correlated with the [001](010) slip system; and MAD diagrams show a peak in a low-angle range(<40?). Integrating recent studies on metamorphism and geochronology, we argue that ductile deformation occurred during the exhumation periods together with retrograded metamorphism.
基金Supported by National Natural Science Foundation of China (Grant Nos. 40821002, 40572115)
文摘Gyirong basin and its adjacent area are located at a special position in the Himalayan orogen, where the south Tibetan detachment system (STDS) and N-S trending rift converged. The north Himalayan orogen here can be divided into five petrologic-tectonic units successively from south to north: 1) the Greater Himalayan crystalline complex (GHC); 2) the STDS shear zone; 3) the Tethyan Himalayan sedimentary sequence (THS); 4) the late Cenozoic sedimentary basins, such as Gyirong and Oma basins; and 5) the Malashan gneiss dome. Structural studies show that this area experienced four stages of deformation: 1) the earlier south-directed thrusting, preserved both in the GHC and THS; 2) top-down-to-north slip along the STDS, normal faults related to this slip formed the early controlling structures of the Cenozoic basins,and the tilted pattern of the blocks between the basins indicated a north-directed slip; 3) east-west extension, the resultant N-S trending normal fault formed the eastern boundary of the basins; and 4) late gravitational collapse. Zircon SHRIMP U-Pb dating on the syn-deformational (leuco-) granite along the STDS indicates that the major activity of the STDS occurred at ca. 26 Ma, but its onset may have begun as early as ca. 36 Ma.
