The nonadiabatic dynamics of methyl nitrate(CH_(3)ONO_(2))is studied with the on-the-fy trajectory surface hopping dynamics at the ADC(2)level.The results confirmed the existence of the ultrafast nonadiabatic decay to...The nonadiabatic dynamics of methyl nitrate(CH_(3)ONO_(2))is studied with the on-the-fy trajectory surface hopping dynamics at the ADC(2)level.The results confirmed the existence of the ultrafast nonadiabatic decay to the electronic ground state.When the dynamics starts from S_(1) and S_(2),the photoproducts are CH_(3)O+NO_(2),consistent with previous results obtained from the experimental studies and theoretical dynamics simulations at more accurate XMS-CASPT2 level.The photolysis products are CH_(3)O+NO_(2) at the ADC(2)level when the dynamics starts from S3,while different photolysis products were obtained in previous experimental and theoretical works.These results demonstrate that the ADC(2)method may still be useful for treating the photolysis mechanism of CH_(3)ONO_(2) at the long-wavelength UV excitation,while great caution should be paid due to its inaccurate performance in the description of the photolysis dynamics at the short-wavelength UV excitation.This gives valuable information to access the accuracy when other alkyl nitrates are treated at the ADC(2)level.展开更多
Viscosities of uranium solutions in H2O and 3 mol/L HNO3 medium were measured by Ubbelhode flow vis-cometer in the concentration range of 0.5%3.0% from 10 篊 to 30 篊 at 5 篊 interval. Viscosity data were interpreted ...Viscosities of uranium solutions in H2O and 3 mol/L HNO3 medium were measured by Ubbelhode flow vis-cometer in the concentration range of 0.5%3.0% from 10 篊 to 30 篊 at 5 篊 interval. Viscosity data were interpreted in terms of an empirical equation; h =aoexp(boM+coM2). Values of coefficients ao, bo and co were calculated for all the three systems studied. Flow activation energies and thermodynamic parameters were also evaluated.展开更多
Aquaculture plays a major role in providing the needed protein. However, there have been reports of negative impacts of shrimp farming which include environmental pollution. Therefore, shrimp pond effluent had to be r...Aquaculture plays a major role in providing the needed protein. However, there have been reports of negative impacts of shrimp farming which include environmental pollution. Therefore, shrimp pond effluent had to be retained for treatment. Treatment in tanks showed good improvement in water quality but in sedimentation ponds it may not be the case. Therefore, the objective of this study was to determine the water quality of effluent retained in sedimentation pond for a duration of 76 hours. Results show that water quality at 1/3 depth was better than 2/3 depth. There was an improvement in water quality with reductions of TSS, BOD5, COD, nitrate-N, nitrite-N, SRP and TP ranging from 25-52% except for DO and TAN. In addition, there was fluctuation of each parameter during the duration of study. It is important to monitor the water quality prior to the release of effluent so that it coincides with low nutrients and acceptable DO and partial release of the top 1/3 portion is recommended. There is a limit on the reduction achievable by sedimentation ponds likely due to processes occurring in the sediment. For higher reductions, other methods of effluent management and recovery of nutrients have to be considered.展开更多
Spent fuel reprocessing plays a pivotal role in achieving efficient recycling of nuclear fuel.Among thedifferent forms of failure encountered in spent fuel reprocessing,tribocorrosion stands out as a critical concern....Spent fuel reprocessing plays a pivotal role in achieving efficient recycling of nuclear fuel.Among thedifferent forms of failure encountered in spent fuel reprocessing,tribocorrosion stands out as a critical concern.Herein,the tribocorrosion behavior,as well as the corrosion behavior,of 304L stainless steel(SS)in high-temperatureconcentrated nitric acid was investigated.The results indicated that 304L SS formed a thin(1.54 nm)and stable passivefilm on the surface,imparting high resistance to nitric acid corrosion.Meanwhile,it was found that the synergistic effectbetween corrosion and wear accounted for a high total tribocorrosion weight loss of over 85%,implying the dominantrole of the synergistic effect in the tribocorrosion process.Furthermore,the wear of 304L SS in deionized water revealedboth abrasive and adhesive wear characterizations,whereas the tribocorrosion in nitric acid only exhibited abrasive wearfeature.Eventually,the tribocorrosion and corrosion models of 304L SS in hot concentrated nitric acid were proposedbased on the comprehensive experimental findings.展开更多
The properties of dissolution in different solvents,the specific heat capacity and thermal decomposition process under the non-isothermal conditions for energetic triazole ionic salts 1,2,4-triazolium nitrate(1a),1,2,...The properties of dissolution in different solvents,the specific heat capacity and thermal decomposition process under the non-isothermal conditions for energetic triazole ionic salts 1,2,4-triazolium nitrate(1a),1,2,3-triazolium nitrate(1b),3,4,5triamino-1,2,4-triazolium nitrate(2a),3,4,5-triamino-1,2,4-triazolium dinitramide(2b)were precisely measured using a Calvet Microcalorimeter.The thermochemical equation,differential enthalpies of dissolution(△difH m ),standard molar enthalpies of dissolution(△difH m ),apparent activation energy(E),pre-exponential constant(A),kinetic equation,linear relationship of specific heat capacity with temperature over the temperature range from 283 to 353 K,standard molar heat capacity(C p,m)and enthalpy,entropy and Gibbs free energy at 283–353 K,taking 298.15 K as the benchmark for 1a,1b,2a and 2b were obtained with treating experimental data and theoretical calculation method.The kinetic and thermodynamic parameters of thermal decomposition reaction,critical temperature of thermal explosion(Tb),self-accelerating decomposition temperature(TSADT)and adiabatic time-to-explosion(t)of 1a,1b,2a and 2b were calculated.Their heat-resistance abilities were evaluated.Information was obtained on the relation between molecular structures and properties of 1a,1b,2a and 2b.展开更多
基金supported by the National Natural Science Foundation of China(No.21933011,No.21873112)。
文摘The nonadiabatic dynamics of methyl nitrate(CH_(3)ONO_(2))is studied with the on-the-fy trajectory surface hopping dynamics at the ADC(2)level.The results confirmed the existence of the ultrafast nonadiabatic decay to the electronic ground state.When the dynamics starts from S_(1) and S_(2),the photoproducts are CH_(3)O+NO_(2),consistent with previous results obtained from the experimental studies and theoretical dynamics simulations at more accurate XMS-CASPT2 level.The photolysis products are CH_(3)O+NO_(2) at the ADC(2)level when the dynamics starts from S3,while different photolysis products were obtained in previous experimental and theoretical works.These results demonstrate that the ADC(2)method may still be useful for treating the photolysis mechanism of CH_(3)ONO_(2) at the long-wavelength UV excitation,while great caution should be paid due to its inaccurate performance in the description of the photolysis dynamics at the short-wavelength UV excitation.This gives valuable information to access the accuracy when other alkyl nitrates are treated at the ADC(2)level.
文摘Viscosities of uranium solutions in H2O and 3 mol/L HNO3 medium were measured by Ubbelhode flow vis-cometer in the concentration range of 0.5%3.0% from 10 篊 to 30 篊 at 5 篊 interval. Viscosity data were interpreted in terms of an empirical equation; h =aoexp(boM+coM2). Values of coefficients ao, bo and co were calculated for all the three systems studied. Flow activation energies and thermodynamic parameters were also evaluated.
文摘Aquaculture plays a major role in providing the needed protein. However, there have been reports of negative impacts of shrimp farming which include environmental pollution. Therefore, shrimp pond effluent had to be retained for treatment. Treatment in tanks showed good improvement in water quality but in sedimentation ponds it may not be the case. Therefore, the objective of this study was to determine the water quality of effluent retained in sedimentation pond for a duration of 76 hours. Results show that water quality at 1/3 depth was better than 2/3 depth. There was an improvement in water quality with reductions of TSS, BOD5, COD, nitrate-N, nitrite-N, SRP and TP ranging from 25-52% except for DO and TAN. In addition, there was fluctuation of each parameter during the duration of study. It is important to monitor the water quality prior to the release of effluent so that it coincides with low nutrients and acceptable DO and partial release of the top 1/3 portion is recommended. There is a limit on the reduction achievable by sedimentation ponds likely due to processes occurring in the sediment. For higher reductions, other methods of effluent management and recovery of nutrients have to be considered.
基金Projects(52101105,52373321)supported by the National Natural Science Foundation of ChinaProject(2023-PY03)supported by the IMR Innovation Fund,ChinaProject(CNNC-LCKY-202274)supported by the LingChuang Research Project of China National Nuclear Corporation。
文摘Spent fuel reprocessing plays a pivotal role in achieving efficient recycling of nuclear fuel.Among thedifferent forms of failure encountered in spent fuel reprocessing,tribocorrosion stands out as a critical concern.Herein,the tribocorrosion behavior,as well as the corrosion behavior,of 304L stainless steel(SS)in high-temperatureconcentrated nitric acid was investigated.The results indicated that 304L SS formed a thin(1.54 nm)and stable passivefilm on the surface,imparting high resistance to nitric acid corrosion.Meanwhile,it was found that the synergistic effectbetween corrosion and wear accounted for a high total tribocorrosion weight loss of over 85%,implying the dominantrole of the synergistic effect in the tribocorrosion process.Furthermore,the wear of 304L SS in deionized water revealedboth abrasive and adhesive wear characterizations,whereas the tribocorrosion in nitric acid only exhibited abrasive wearfeature.Eventually,the tribocorrosion and corrosion models of 304L SS in hot concentrated nitric acid were proposedbased on the comprehensive experimental findings.
基金supported by the National Natural Science Foundation of China (20573098)the Science and Technology Foundation of National Key Lab of Science and Technology on Combustion and Explosion in China (9140C3503030805)
文摘The properties of dissolution in different solvents,the specific heat capacity and thermal decomposition process under the non-isothermal conditions for energetic triazole ionic salts 1,2,4-triazolium nitrate(1a),1,2,3-triazolium nitrate(1b),3,4,5triamino-1,2,4-triazolium nitrate(2a),3,4,5-triamino-1,2,4-triazolium dinitramide(2b)were precisely measured using a Calvet Microcalorimeter.The thermochemical equation,differential enthalpies of dissolution(△difH m ),standard molar enthalpies of dissolution(△difH m ),apparent activation energy(E),pre-exponential constant(A),kinetic equation,linear relationship of specific heat capacity with temperature over the temperature range from 283 to 353 K,standard molar heat capacity(C p,m)and enthalpy,entropy and Gibbs free energy at 283–353 K,taking 298.15 K as the benchmark for 1a,1b,2a and 2b were obtained with treating experimental data and theoretical calculation method.The kinetic and thermodynamic parameters of thermal decomposition reaction,critical temperature of thermal explosion(Tb),self-accelerating decomposition temperature(TSADT)and adiabatic time-to-explosion(t)of 1a,1b,2a and 2b were calculated.Their heat-resistance abilities were evaluated.Information was obtained on the relation between molecular structures and properties of 1a,1b,2a and 2b.
