Aim To develop a concise method for the synthesis of bicyclic azasugar and thiosugar with novel scaffold. Methods The two primary hydroxyl groups of compound 1 were selectively protected with tosyl cloloride in pyridi...Aim To develop a concise method for the synthesis of bicyclic azasugar and thiosugar with novel scaffold. Methods The two primary hydroxyl groups of compound 1 were selectively protected with tosyl cloloride in pyridine, followed by ring-closure with sodium sulfide or primary amine to form the oxy-bridged bicyclic molecules in good yields. Results Two bicyclic azasugars and a thiosugar were produced from L-sorbose in several steps. Conclusion The described procedures provide an efficient method to synthesize bicyclic azasugar and thiosugar with novel scaffold as potential glycosidase inhibitors.展开更多
Based on the analysis of the main failures discovered in pavement on steel deck plate and the demanding service condition of the pavement on steel deck, high-temperature rutting test, low-temperature bending test and ...Based on the analysis of the main failures discovered in pavement on steel deck plate and the demanding service condition of the pavement on steel deck, high-temperature rutting test, low-temperature bending test and controlled stress flexural fatigue test are used to study the performance of asphalt mixtures modified by epoxy resin including high-temperature stability, low-temperature cracking-resistance, and fatigue cracking-resistance, which are served to evaluate the modification effect of epoxy resin of different contents. With the addition of epoxy resin, all the three performances are improved greatly. However, when the amount of epoxy resin added is over a certain value, the modification effect will be stable with no extra benefit detected. Finally, in terms of the properties of the three respects, 20%, 30%, 30% are given separately as the proposal adding contents.展开更多
To investigate the fatigue damage of epoxy asphalt pavement(EAP)under a heavy load and a d temperature load,the load-figure of the heavy load on the steel bridge deck pavement(SBDP)was simulated first,and the temperat...To investigate the fatigue damage of epoxy asphalt pavement(EAP)under a heavy load and a d temperature load,the load-figure of the heavy load on the steel bridge deck pavement(SBDP)was simulated first,and the temperature distribution of SBDP during the temperature-fall period in winter was also calculated.Secondly,t e moving heavy load coupled W t the most unfavorable temperatre load was applied to the SBDP,and the tensile stress on the top of SBDP was calculated.Finally,the fatigue damage of EAP was evaluated considering the extreme situation of heavily overloaded and severe environments.The results show that botte heavy load and the temperature load during t e temperature-fall period c n increase the tensile stress on the top of SBDP significantly.In the exteme situation of heavily overloaded and severe environments,a fatigue crack is easily generated,and thus the SBDP should avoid t e coupling effects of the heavy loadand the temperature load in winter.展开更多
Maintaining both the safety and serviceability of deteriorating highway bridge networks necessitates suitable BMS （bridge maintenance system） tools that can maximize cost effectiveness. Numerous experiments have bee...Maintaining both the safety and serviceability of deteriorating highway bridge networks necessitates suitable BMS （bridge maintenance system） tools that can maximize cost effectiveness. Numerous experiments have been conducted to detect the long-term mechanical properties of the epoxy resin materials used in FRP （fiber reinforced polymers） strengthening and maintenance technique. Experiments were used to develop a short-term test and construct a model that can reliably predict the long-term behavior of epoxy resin. Furthermore, FEA （finite element analysis） models were developed, using the ANSYS software, to simulate three unstrengthened and FRP strengthened prestressed concrete girder bridges of different configurations. Models simulate the original and aged properties of construction and retrofitting materials under the application of AASHTO （American Association of State Highway and Transportation Officials） fatigue truck and a site-specific fatigue truck in different scenarios. These models were used to develop the bridge performance chart for the capacity of the bridge, with and without strengthening interventions, as a BMS tool. The results show an immediate significant improvement in the concrete tensile stress with the intervention of FRP strengthening.展开更多
An efficient and environmentally friendly procedure for the one-pot synthesis of 13-acetyl-9-methyl-ll-oxo-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene from salicylaldehyde, acetylacetone and urea via Bi...An efficient and environmentally friendly procedure for the one-pot synthesis of 13-acetyl-9-methyl-ll-oxo-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene from salicylaldehyde, acetylacetone and urea via Biginelli condensation and intramolecular Michael-addition by using magnesium bromide as an inexpensive and easily available catalyst in a solvent-free condition is described. The structural elucidation of the product is reported by ^1H- and ^13C NMR spectra. The product can also be identified by its EI TOF mass spectrometry based on the molecular ion at m/s 246（10%） and on the fragment ions in which two nitrogen atoms are remained. Three kinds of characteristic fragmentation pathways from the molecular ion were observed. One is the loss of the OH radical to form the dihydropyrimidinone cation at m/z 229（48%）, followed by elimination of a molecular methane forming the pyrimidinone cation at m/z 213（27%）. The second is the cleavage of the C6H4OH radical, and the formation of the dihydropyrimidinone cation at m/z 153（24%）. The third one is the loss of MeC-O radical to afford the oxygen-bridged fragment ion at m/z 203（33%）.展开更多
基金We thank the National Science Foundation of China(NSFC,N0.20372003)for financial support.
文摘Aim To develop a concise method for the synthesis of bicyclic azasugar and thiosugar with novel scaffold. Methods The two primary hydroxyl groups of compound 1 were selectively protected with tosyl cloloride in pyridine, followed by ring-closure with sodium sulfide or primary amine to form the oxy-bridged bicyclic molecules in good yields. Results Two bicyclic azasugars and a thiosugar were produced from L-sorbose in several steps. Conclusion The described procedures provide an efficient method to synthesize bicyclic azasugar and thiosugar with novel scaffold as potential glycosidase inhibitors.
文摘Based on the analysis of the main failures discovered in pavement on steel deck plate and the demanding service condition of the pavement on steel deck, high-temperature rutting test, low-temperature bending test and controlled stress flexural fatigue test are used to study the performance of asphalt mixtures modified by epoxy resin including high-temperature stability, low-temperature cracking-resistance, and fatigue cracking-resistance, which are served to evaluate the modification effect of epoxy resin of different contents. With the addition of epoxy resin, all the three performances are improved greatly. However, when the amount of epoxy resin added is over a certain value, the modification effect will be stable with no extra benefit detected. Finally, in terms of the properties of the three respects, 20%, 30%, 30% are given separately as the proposal adding contents.
基金The National Natural Science Foundation of China(Nos.51378122,51678146)the Scientific Research Foundation of Graduate School of Southeast University(No.YBJJ1680)
文摘To investigate the fatigue damage of epoxy asphalt pavement(EAP)under a heavy load and a d temperature load,the load-figure of the heavy load on the steel bridge deck pavement(SBDP)was simulated first,and the temperature distribution of SBDP during the temperature-fall period in winter was also calculated.Secondly,t e moving heavy load coupled W t the most unfavorable temperatre load was applied to the SBDP,and the tensile stress on the top of SBDP was calculated.Finally,the fatigue damage of EAP was evaluated considering the extreme situation of heavily overloaded and severe environments.The results show that botte heavy load and the temperature load during t e temperature-fall period c n increase the tensile stress on the top of SBDP significantly.In the exteme situation of heavily overloaded and severe environments,a fatigue crack is easily generated,and thus the SBDP should avoid t e coupling effects of the heavy loadand the temperature load in winter.
文摘Maintaining both the safety and serviceability of deteriorating highway bridge networks necessitates suitable BMS （bridge maintenance system） tools that can maximize cost effectiveness. Numerous experiments have been conducted to detect the long-term mechanical properties of the epoxy resin materials used in FRP （fiber reinforced polymers） strengthening and maintenance technique. Experiments were used to develop a short-term test and construct a model that can reliably predict the long-term behavior of epoxy resin. Furthermore, FEA （finite element analysis） models were developed, using the ANSYS software, to simulate three unstrengthened and FRP strengthened prestressed concrete girder bridges of different configurations. Models simulate the original and aged properties of construction and retrofitting materials under the application of AASHTO （American Association of State Highway and Transportation Officials） fatigue truck and a site-specific fatigue truck in different scenarios. These models were used to develop the bridge performance chart for the capacity of the bridge, with and without strengthening interventions, as a BMS tool. The results show an immediate significant improvement in the concrete tensile stress with the intervention of FRP strengthening.
基金This work was supported by the Natural Science Foundation of China （No.20425309）.
文摘An efficient and environmentally friendly procedure for the one-pot synthesis of 13-acetyl-9-methyl-ll-oxo-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene from salicylaldehyde, acetylacetone and urea via Biginelli condensation and intramolecular Michael-addition by using magnesium bromide as an inexpensive and easily available catalyst in a solvent-free condition is described. The structural elucidation of the product is reported by ^1H- and ^13C NMR spectra. The product can also be identified by its EI TOF mass spectrometry based on the molecular ion at m/s 246（10%） and on the fragment ions in which two nitrogen atoms are remained. Three kinds of characteristic fragmentation pathways from the molecular ion were observed. One is the loss of the OH radical to form the dihydropyrimidinone cation at m/z 229（48%）, followed by elimination of a molecular methane forming the pyrimidinone cation at m/z 213（27%）. The second is the cleavage of the C6H4OH radical, and the formation of the dihydropyrimidinone cation at m/z 153（24%）. The third one is the loss of MeC-O radical to afford the oxygen-bridged fragment ion at m/z 203（33%）.
