Effects of strain rate on the microstructure evolution and thermal stability of1050commercial pure aluminum processed by means of split Hopkinson pressure bar(SHPB)and Instron?3369mechanical testing machine were inves...Effects of strain rate on the microstructure evolution and thermal stability of1050commercial pure aluminum processed by means of split Hopkinson pressure bar(SHPB)and Instron?3369mechanical testing machine were investigated.Samples in the deformed state and after various annealing treatments at423?523K(150?250°C)for1h were characterized by TEM and hardness test.The result reveals that the samples in the deformed state were mainly composed of elongated subgrains/cells with high density of dislocations.Microstructures of the quasi-static compressed aluminum were quite stable throughout the temperature range studied,and no significant grain growth was observed.However,for the dynamic impacted one,recrystallized grains with an average grain size of4.7μm were evolved after annealing at523K(250°C)for1h.It is suggested that the annealing behavior of this dynamic deformed aluminum is a continuous process of grain coarsening,rather than the traditional discontinuous recrystallization for the quasi-static compressed aluminum.展开更多
To determine the solubility of CO_(2)in n-dodecane at T=303.15-353.15 K,P≤11.00 MPa,an integrated fused silica capillary and in-situ Raman spectroscopy system was built.The Raman peak intensity ratio(I_(CO_(2))/IC-H)...To determine the solubility of CO_(2)in n-dodecane at T=303.15-353.15 K,P≤11.00 MPa,an integrated fused silica capillary and in-situ Raman spectroscopy system was built.The Raman peak intensity ratio(I_(CO_(2))/IC-H)between the upper band of CO_(2)Fermi diad(I_(CO_(2)))and the C-H stretching band of n-dodecane(IC-H)was employed to determine the solubility of CO_(2)in n-dodecane based on the calibrated correlation equation between the known CO_(2)molality in n-dodecane and the I_(CO_(2))/IC-Hratio with R^(2)=0.9998.The results indicated that the solubility of CO_(2)decreased with increasing temperature and increased with increasing pressure.The maximum CO_(2)molality(30.7314 mol/kg)was obtained at 303.15 K and7.00 MPa.Finally,a solubility prediction model(lnS=(P-A)/B)based on the relationship with temperature(T in K)and pressure(P in MPa)was developed,where S is CO_(2)molality,A=-8×10^(-6)T^(2)+0.0354T-8.1605,and B=0.0405T-10.756.The results indicated that the solubilities of CO_(2)derived from this model were in good agreement with the experimental data.展开更多
The widespread use of organophosphorus pesticides(OPs) poses a great threat to human health and has made the detection of OP residues in food an important task,especially in view of the fact that easy and rapid detect...The widespread use of organophosphorus pesticides(OPs) poses a great threat to human health and has made the detection of OP residues in food an important task,especially in view of the fact that easy and rapid detection methods are needed.Because OPs have inhibitory effects on the activity of α-naphthyl acetate esterase(ANAE) in plants,in this work we evaluated the possibility of detecting OPs in vegetables with ANAE extracted from commercial flour.The limits of detection(LODs) obtained for methamidophos,dichlorvos,phoxim,dimethoate,and malathion in lettuce samples with crude ANAE were 0.17,0.11,0.11,0.96,and 1.70 mg/kg,respectively.Based on the maximum residue limits(MRLs) for OPs in food stipulated by Chinese laws which are 0.05,0.20,0.05,1.00,and 8.00 mg/kg for methamidophos,dichlorvos,phoxim,dimethoate,and malathion,respectively,the esterase inhibition method with crude ANAE had sufficient sensitivity to detect the residues of dichlorvos,dimethoate,and malathion in lettuce,but it could not be used to guarantee the safety of the same samples if methamidophos or phoxim residue was present.The sensitivity of the method was improved by the use of esterase purified by ammonium sulfate salting-out.The LODs obtained for methamidophos and phoxim with purified esterase were lower than the MRLs for these OPs in food.This is a very promising method for the detection of OP residues in vegetables using crude or purified esterase because of its cheapness,sensitivity,and convenience.展开更多
基金Projects(51274245,51574290,U1330126) supported by the National Natural Science Foundation of ChinaProject supported by the Opening Fund of State Key Laboratory of Nonlinear Mechanics,China
文摘Effects of strain rate on the microstructure evolution and thermal stability of1050commercial pure aluminum processed by means of split Hopkinson pressure bar(SHPB)and Instron?3369mechanical testing machine were investigated.Samples in the deformed state and after various annealing treatments at423?523K(150?250°C)for1h were characterized by TEM and hardness test.The result reveals that the samples in the deformed state were mainly composed of elongated subgrains/cells with high density of dislocations.Microstructures of the quasi-static compressed aluminum were quite stable throughout the temperature range studied,and no significant grain growth was observed.However,for the dynamic impacted one,recrystallized grains with an average grain size of4.7μm were evolved after annealing at523K(250°C)for1h.It is suggested that the annealing behavior of this dynamic deformed aluminum is a continuous process of grain coarsening,rather than the traditional discontinuous recrystallization for the quasi-static compressed aluminum.
基金supported by the National Key Research and Development Program of China(2019YFE0117200)the Natural Science Foundation of China(41977304)
文摘To determine the solubility of CO_(2)in n-dodecane at T=303.15-353.15 K,P≤11.00 MPa,an integrated fused silica capillary and in-situ Raman spectroscopy system was built.The Raman peak intensity ratio(I_(CO_(2))/IC-H)between the upper band of CO_(2)Fermi diad(I_(CO_(2)))and the C-H stretching band of n-dodecane(IC-H)was employed to determine the solubility of CO_(2)in n-dodecane based on the calibrated correlation equation between the known CO_(2)molality in n-dodecane and the I_(CO_(2))/IC-Hratio with R^(2)=0.9998.The results indicated that the solubility of CO_(2)decreased with increasing temperature and increased with increasing pressure.The maximum CO_(2)molality(30.7314 mol/kg)was obtained at 303.15 K and7.00 MPa.Finally,a solubility prediction model(lnS=(P-A)/B)based on the relationship with temperature(T in K)and pressure(P in MPa)was developed,where S is CO_(2)molality,A=-8×10^(-6)T^(2)+0.0354T-8.1605,and B=0.0405T-10.756.The results indicated that the solubilities of CO_(2)derived from this model were in good agreement with the experimental data.
基金Project supported by the National Basic Research Program (973) of China (No.2009CB119000)the National Natural Science Foundation of China (Nos.20707022,41073090,and 30771255)the Zhejiang Provincial Natural Science Foundation of China (No.Y507220)
文摘The widespread use of organophosphorus pesticides(OPs) poses a great threat to human health and has made the detection of OP residues in food an important task,especially in view of the fact that easy and rapid detection methods are needed.Because OPs have inhibitory effects on the activity of α-naphthyl acetate esterase(ANAE) in plants,in this work we evaluated the possibility of detecting OPs in vegetables with ANAE extracted from commercial flour.The limits of detection(LODs) obtained for methamidophos,dichlorvos,phoxim,dimethoate,and malathion in lettuce samples with crude ANAE were 0.17,0.11,0.11,0.96,and 1.70 mg/kg,respectively.Based on the maximum residue limits(MRLs) for OPs in food stipulated by Chinese laws which are 0.05,0.20,0.05,1.00,and 8.00 mg/kg for methamidophos,dichlorvos,phoxim,dimethoate,and malathion,respectively,the esterase inhibition method with crude ANAE had sufficient sensitivity to detect the residues of dichlorvos,dimethoate,and malathion in lettuce,but it could not be used to guarantee the safety of the same samples if methamidophos or phoxim residue was present.The sensitivity of the method was improved by the use of esterase purified by ammonium sulfate salting-out.The LODs obtained for methamidophos and phoxim with purified esterase were lower than the MRLs for these OPs in food.This is a very promising method for the detection of OP residues in vegetables using crude or purified esterase because of its cheapness,sensitivity,and convenience.