In the present work we elucidate the thermodynamic mechanisms of femtosecond(fs)laser ablation of amorphous polystyrene by means of molecular dynamics(MD)simulations.The effects of extrinsic parameter of laser pulse i...In the present work we elucidate the thermodynamic mechanisms of femtosecond(fs)laser ablation of amorphous polystyrene by means of molecular dynamics(MD)simulations.The effects of extrinsic parameter of laser pulse intensity and intrinsic parameter of molecular architecture on the laser ablation are further studied.Simulation results show that the laser ablation-induced polymeric material removal is achieved by evaporation from the surface and expansion within the bulk.Furthermore,inter-chain sliding and intra-chain change also play important roles in the microscopic deformation of the material.It is found that both the laser pulse intensity and the arrangement of phenyl groups have significant influence on the fs laser ablation of polystyrene.展开更多
Sulfur dioxide （SO2） and nitrogen oxide （NOx） in flue gas can be removed by combining microwave induced catalysis and adsorption on activated carbon. The reaction mechanisms of desulfurization and denitrification ...Sulfur dioxide （SO2） and nitrogen oxide （NOx） in flue gas can be removed by combining microwave induced catalysis and adsorption on activated carbon. The reaction mechanisms of desulfurization and denitrification by microwave irradiation were analyzed based on the measurement of reaction products. Thermodynamic parameters for desulfurization and denitrification by thermal-carbon reduction were predicted according to the principles of thermodynamics. The experimental results indicated that the desulfurization and denitrification reaction processes include three reaction stages： slow reaction zone, transitional zone and rapid reaction zone. In high temperature zone, activation energies for the reduction of SO2 and nitrogen monoxide （NO） are 30.69 and 24.06 kJ mo1-1, respectively. This study shows that microwave can effectively enhance the removal of pollutants through its heating effect and the induced catalysis.展开更多
Affected by structural uplift, the Ordovician carbonate rockbed in the Tarim Basin, China, was exposed to dissolution and reformation of atmospheric precipitation many times, and formed a large quantity of karst caves...Affected by structural uplift, the Ordovician carbonate rockbed in the Tarim Basin, China, was exposed to dissolution and reformation of atmospheric precipitation many times, and formed a large quantity of karst caves serving as hydrocarbon reser- voir. However, drilling in Tahe area showed that many large karst caves, small pores and fractures are filled by calcite, result- ing in decrease in their reservoir ability. Calcite filled in the karst caves has very light oxygen isotopic composition and STSr/S（＇Sr ratio. Its c^OpDB ranges from -21.2%o to 13.3%o with the average of -16.3%e and its 87Sr/86Nr ratio ranges from 0.709561 to 0.710070 with the average of 0.709843. The isotope composition showed that calcite is related to atmospheric precipitation. Theoretic analyses indicated that the dissolving and filling actions of the precipitation on carbonate rocks are controlled by both thermodynamic and kinetic mechanisms. Among them, the thermodynamic factor determines that the pre- cipitation during its flow from the earth surface downward plays important roles on carbonate rocks from dissolution to satura- tion, further sedimentation, and finally filling. In other words, the depth of the karstification development is not unrestricted, but limited by the precipitation beneath the earth surface. On the other hand, the kinetic factor controls the intensity, depth, and breadth of the karstification development, that is, the karstification is also affected by topographic, geomorphologic, climatic factors, the degree of fracture or fault, etc. Therefore, subject to their joint effects, the karstification of the precipitation on the Ordovician carbonate rocks occurs only within a certain depth （most about 200 m） under the unconformity surface, deeper than which carbonate minerals begin to sedimentate and fill the karst caves that were formed previously.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51275114 and 51006093)the Laboratory of Precision Manufacturing Technology in China Academy of Engineering Physics(Grant No.zz13010)the Fundamental Research Funds for the Central Universities,China(Grant No.HIT.NSRIF.2013050)
文摘In the present work we elucidate the thermodynamic mechanisms of femtosecond(fs)laser ablation of amorphous polystyrene by means of molecular dynamics(MD)simulations.The effects of extrinsic parameter of laser pulse intensity and intrinsic parameter of molecular architecture on the laser ablation are further studied.Simulation results show that the laser ablation-induced polymeric material removal is achieved by evaporation from the surface and expansion within the bulk.Furthermore,inter-chain sliding and intra-chain change also play important roles in the microscopic deformation of the material.It is found that both the laser pulse intensity and the arrangement of phenyl groups have significant influence on the fs laser ablation of polystyrene.
基金supported by the National Natural Science Foundation of China (Grant No. 50976035)
文摘Sulfur dioxide （SO2） and nitrogen oxide （NOx） in flue gas can be removed by combining microwave induced catalysis and adsorption on activated carbon. The reaction mechanisms of desulfurization and denitrification by microwave irradiation were analyzed based on the measurement of reaction products. Thermodynamic parameters for desulfurization and denitrification by thermal-carbon reduction were predicted according to the principles of thermodynamics. The experimental results indicated that the desulfurization and denitrification reaction processes include three reaction stages： slow reaction zone, transitional zone and rapid reaction zone. In high temperature zone, activation energies for the reduction of SO2 and nitrogen monoxide （NO） are 30.69 and 24.06 kJ mo1-1, respectively. This study shows that microwave can effectively enhance the removal of pollutants through its heating effect and the induced catalysis.
基金sponsored by the National Basic Research Program of China(Grant No.2012CB214802)National Natural Science Foundation of China(Grant Nos.41002037,41102075,41230312)
文摘Affected by structural uplift, the Ordovician carbonate rockbed in the Tarim Basin, China, was exposed to dissolution and reformation of atmospheric precipitation many times, and formed a large quantity of karst caves serving as hydrocarbon reser- voir. However, drilling in Tahe area showed that many large karst caves, small pores and fractures are filled by calcite, result- ing in decrease in their reservoir ability. Calcite filled in the karst caves has very light oxygen isotopic composition and STSr/S（＇Sr ratio. Its c^OpDB ranges from -21.2%o to 13.3%o with the average of -16.3%e and its 87Sr/86Nr ratio ranges from 0.709561 to 0.710070 with the average of 0.709843. The isotope composition showed that calcite is related to atmospheric precipitation. Theoretic analyses indicated that the dissolving and filling actions of the precipitation on carbonate rocks are controlled by both thermodynamic and kinetic mechanisms. Among them, the thermodynamic factor determines that the pre- cipitation during its flow from the earth surface downward plays important roles on carbonate rocks from dissolution to satura- tion, further sedimentation, and finally filling. In other words, the depth of the karstification development is not unrestricted, but limited by the precipitation beneath the earth surface. On the other hand, the kinetic factor controls the intensity, depth, and breadth of the karstification development, that is, the karstification is also affected by topographic, geomorphologic, climatic factors, the degree of fracture or fault, etc. Therefore, subject to their joint effects, the karstification of the precipitation on the Ordovician carbonate rocks occurs only within a certain depth （most about 200 m） under the unconformity surface, deeper than which carbonate minerals begin to sedimentate and fill the karst caves that were formed previously.
