目的通过比较噪声暴露后基底膜不同区域内毛细胞(IHCs)带状突触损伤差异,探讨带状突触损伤易感性的相关因素。方法将28只C57BL/6J雄性小鼠随机分为噪声暴露组和对照组,每组14只。噪声暴露组小鼠给予强度103 dB SPL、频率2~20 kHz、持续...目的通过比较噪声暴露后基底膜不同区域内毛细胞(IHCs)带状突触损伤差异,探讨带状突触损伤易感性的相关因素。方法将28只C57BL/6J雄性小鼠随机分为噪声暴露组和对照组,每组14只。噪声暴露组小鼠给予强度103 dB SPL、频率2~20 kHz、持续2 h的宽带噪声暴露,对照组小鼠则饲养于安静环境中。噪声暴露前及噪声暴露后第一天进行ABR测试及毛细胞带状突触免疫荧光染色实验。使用全细胞膜片钳技术比较不同区域IHCs的钙离子流入。通过免疫荧光染色比较噪声暴露后的耳蜗基底膜顶回、中回、底回IHCs钙蛋白酶(Calpain)表达水平,并用蛋白质印迹实验验证钙蛋白酶对IHCs带状突触蛋白CtBP2的损伤作用。结果噪声暴露后一天,噪声暴露组在11.3、16.0、22.6、32.0 kHz的ABR阈值较对照组显著上升(均为P<0.001),中回、底回IHCs带状突触数量明显减少(P<0.05)。全细胞膜片钳实验结果表明耳蜗基底膜中回IHCs有较多的钙离子通道(P<0.01),但其单通道电流较小(P<0.01),顶回、中回IHCs钙离子通道开放率无显著差异(P>0.05)。噪声暴露后,耳蜗基底膜中回、底回IHCs的Calpain表达水平显著高于顶回(P<0.001),蛋白质印迹实验结果表明Calpain以钙离子依赖的方式降解带状突触蛋白CtBP2。结论钙蛋白酶是基底膜高频区内毛细胞带状突触噪声损伤易感的重要因素。展开更多
Aiming at the issue of crystallization and blockage of drainage system due to the massive calcium loss from the tunnel shotcrete,a selfdesigned tunnel seepage crystallization modelling system was developed.This system...Aiming at the issue of crystallization and blockage of drainage system due to the massive calcium loss from the tunnel shotcrete,a selfdesigned tunnel seepage crystallization modelling system was developed.This system was produced in conjunction with the initial tunnel support shotcrete construction and drainage pipe installation,and is capable of simulating both the seepage process of groundwater in the shotcrete and the process of crystallization in the drainage pipe.Based on three different mechanisms of anti-crystallization,which include absorbing free calcium,reducing the porosity and increasing hydrophobicity,antialkali agent,nano-calcium carbonate,and silane were selected to test,respectively.Firstly,the suitable dosing ranges of these three external admixtures for resisting calcium loss in shotcrete were determined by single factor tests,which were 7%–11%,4%–8%,and 0.3%–0.5%,respectively.Thereafter,the response surface method was employed to evaluate the interaction of antialkali agent,nano-calcium carbonate and silane on calcium loss in shotcrete,and to establish the relationship between them,and thus to determine the admixture ratio that can effectively reduce calcium loss crystallization in shotcrete,with the optimal admixture amounts of antialkali agent being 9.242%,nano-calcium carbonate 4.889%and silane 0.366%.Lastly,the reliability of the model test results was verified by the microscopic analysis,and the results showed that the total amount of calcium dissolution in the optimized group could be reduced by 75%compared with the blank control group,and was basically consistent with that derived from the response surface regression model,validating the high accuracy of the buildup response surface regression model.The present study can provide some ideas and references for reducing the seepage crystallization behavior of groundwater in the initial tunnel support shotcrete.展开更多
以笼状低聚倍半硅氧烷(POSS)为有机/无机杂化组分,以丙烯酰胺(AM)、2-丙烯酰胺-2甲基丙磺酸(AMPS)、十八烷基二甲基烯丙基氯化铵为反应单体,通过乳液聚合法制备了一种有机/无机复合降滤失剂PAAD,并分析了PAAD在高温高钙环境下对膨润土...以笼状低聚倍半硅氧烷(POSS)为有机/无机杂化组分,以丙烯酰胺(AM)、2-丙烯酰胺-2甲基丙磺酸(AMPS)、十八烷基二甲基烯丙基氯化铵为反应单体,通过乳液聚合法制备了一种有机/无机复合降滤失剂PAAD,并分析了PAAD在高温高钙环境下对膨润土基浆流变性和滤失性的影响。研究表明,降滤失剂PAAD结构中POSS与聚合物基质相容性好,在水溶液中可形成交联网状结构,热分解温度超过300℃,200℃下其水溶液仍具有较高黏度。PAAD在膨润土基浆中具有增黏降滤失作用,在10%CaCl2含量下,2.0%PAAD可使膨润土基浆在150℃下老化16 h后的滤失量由150 m L降低至15.4 mL,且形成了致密滤饼。微观分析表明PAAD屏蔽了高温高钙对膨润土颗粒的不利影响,有效维持膨润土颗粒的分散稳定性。POSS粒子研究前景广阔,未来可进一步探究改性POSS粒子对聚合物抗高温性能的影响。展开更多
基金funding provided by the Project of Yunnan Provincial Department of Transportation(Grant No.yjkjb[2019]No.59)the Fundamental Research Funds for the Central Universities,CHD(Grant No.300102212706).
文摘Aiming at the issue of crystallization and blockage of drainage system due to the massive calcium loss from the tunnel shotcrete,a selfdesigned tunnel seepage crystallization modelling system was developed.This system was produced in conjunction with the initial tunnel support shotcrete construction and drainage pipe installation,and is capable of simulating both the seepage process of groundwater in the shotcrete and the process of crystallization in the drainage pipe.Based on three different mechanisms of anti-crystallization,which include absorbing free calcium,reducing the porosity and increasing hydrophobicity,antialkali agent,nano-calcium carbonate,and silane were selected to test,respectively.Firstly,the suitable dosing ranges of these three external admixtures for resisting calcium loss in shotcrete were determined by single factor tests,which were 7%–11%,4%–8%,and 0.3%–0.5%,respectively.Thereafter,the response surface method was employed to evaluate the interaction of antialkali agent,nano-calcium carbonate and silane on calcium loss in shotcrete,and to establish the relationship between them,and thus to determine the admixture ratio that can effectively reduce calcium loss crystallization in shotcrete,with the optimal admixture amounts of antialkali agent being 9.242%,nano-calcium carbonate 4.889%and silane 0.366%.Lastly,the reliability of the model test results was verified by the microscopic analysis,and the results showed that the total amount of calcium dissolution in the optimized group could be reduced by 75%compared with the blank control group,and was basically consistent with that derived from the response surface regression model,validating the high accuracy of the buildup response surface regression model.The present study can provide some ideas and references for reducing the seepage crystallization behavior of groundwater in the initial tunnel support shotcrete.
文摘以笼状低聚倍半硅氧烷(POSS)为有机/无机杂化组分,以丙烯酰胺(AM)、2-丙烯酰胺-2甲基丙磺酸(AMPS)、十八烷基二甲基烯丙基氯化铵为反应单体,通过乳液聚合法制备了一种有机/无机复合降滤失剂PAAD,并分析了PAAD在高温高钙环境下对膨润土基浆流变性和滤失性的影响。研究表明,降滤失剂PAAD结构中POSS与聚合物基质相容性好,在水溶液中可形成交联网状结构,热分解温度超过300℃,200℃下其水溶液仍具有较高黏度。PAAD在膨润土基浆中具有增黏降滤失作用,在10%CaCl2含量下,2.0%PAAD可使膨润土基浆在150℃下老化16 h后的滤失量由150 m L降低至15.4 mL,且形成了致密滤饼。微观分析表明PAAD屏蔽了高温高钙对膨润土颗粒的不利影响,有效维持膨润土颗粒的分散稳定性。POSS粒子研究前景广阔,未来可进一步探究改性POSS粒子对聚合物抗高温性能的影响。
