以高哌啶为主要原料,采用两步法制备了对甲苯磺酸叔铵盐离子液体1-(丙酸基)高哌啶对甲苯磺酸盐[HMILS]OTs和双-(1-高哌啶)亚丁基双对甲苯磺酸盐HMIBL[OTs]2,用FT-IR、1 H NMR、元素分析和热分析等方法对合成的两种离子液体进行了表征,...以高哌啶为主要原料,采用两步法制备了对甲苯磺酸叔铵盐离子液体1-(丙酸基)高哌啶对甲苯磺酸盐[HMILS]OTs和双-(1-高哌啶)亚丁基双对甲苯磺酸盐HMIBL[OTs]2,用FT-IR、1 H NMR、元素分析和热分析等方法对合成的两种离子液体进行了表征,并用于催化柠檬酸和正丁醇的酯化反应。结果表明:合成的HMIBL[OTs]2其催化活性高于[HMILS]OTs和H2SO4,在n(正丁醇)∶n(柠檬酸)∶n(HMIBL[OTs]2)=5∶1∶0.07、120℃、反应时间3.5h的条件下,HMIBL[OTs]2对柠檬酸的转化率和檬酸三丁酯的选择性分别为98.2%和98.6%,合成的离子液体催化剂使用后可以回收,且重复使用8次后催化活性无明显降低。展开更多
The spatial resolution of conventional distributed fiber optic sensors is 1 m at best, which is inadequate to locate the damage precisely. We adopt an improved sensing technique based on the Brillouin optical time-dom...The spatial resolution of conventional distributed fiber optic sensors is 1 m at best, which is inadequate to locate the damage precisely. We adopt an improved sensing technique based on the Brillouin optical time-domain analysis （BOTDA）. The stepped pump light is input to stimulate the phonon so that the spatial resolution can be increased to centimeter order and the strain accuracy of 25 micro-strains is obtained. The feasibility of this sensing technique is demonstrated through strain measurement of three concrete box-girders in bending. Experimental results show that the improved BOTDA measurement can provide a comprehensive description on the strain distribution of steel rebar or concrete. Compared with the conventional strain gauges, the improved BOTDA measurement is more stable. By virtue of higher spatial resolution and better measurement accuracy, it has become possible to perform crack detection and localization for concrete structures.展开更多
文摘以高哌啶为主要原料,采用两步法制备了对甲苯磺酸叔铵盐离子液体1-(丙酸基)高哌啶对甲苯磺酸盐[HMILS]OTs和双-(1-高哌啶)亚丁基双对甲苯磺酸盐HMIBL[OTs]2,用FT-IR、1 H NMR、元素分析和热分析等方法对合成的两种离子液体进行了表征,并用于催化柠檬酸和正丁醇的酯化反应。结果表明:合成的HMIBL[OTs]2其催化活性高于[HMILS]OTs和H2SO4,在n(正丁醇)∶n(柠檬酸)∶n(HMIBL[OTs]2)=5∶1∶0.07、120℃、反应时间3.5h的条件下,HMIBL[OTs]2对柠檬酸的转化率和檬酸三丁酯的选择性分别为98.2%和98.6%,合成的离子液体催化剂使用后可以回收,且重复使用8次后催化活性无明显降低。
基金supported by the National Natural Science Foundation of China (Nos.50725828 and 50608017)the Sustentation Fund for Young Teachers of Southeast University
文摘The spatial resolution of conventional distributed fiber optic sensors is 1 m at best, which is inadequate to locate the damage precisely. We adopt an improved sensing technique based on the Brillouin optical time-domain analysis （BOTDA）. The stepped pump light is input to stimulate the phonon so that the spatial resolution can be increased to centimeter order and the strain accuracy of 25 micro-strains is obtained. The feasibility of this sensing technique is demonstrated through strain measurement of three concrete box-girders in bending. Experimental results show that the improved BOTDA measurement can provide a comprehensive description on the strain distribution of steel rebar or concrete. Compared with the conventional strain gauges, the improved BOTDA measurement is more stable. By virtue of higher spatial resolution and better measurement accuracy, it has become possible to perform crack detection and localization for concrete structures.
