The ring-polymer molecular dynamics(RPMD)was used to calculate the thermal rate coefficients of the multi-channel roaming reaction H+MgH→Mg+H_(2).Two reaction channels,tight and roaming,are explicitly considered.This...The ring-polymer molecular dynamics(RPMD)was used to calculate the thermal rate coefficients of the multi-channel roaming reaction H+MgH→Mg+H_(2).Two reaction channels,tight and roaming,are explicitly considered.This is a pioneering attempt of exerting RPMD method to multichannel reactions.With the help of a newly developed optimization-interpolation protocol for preparing the initial structures and adaptive protocol for choosing the force constants,we have successfully obtained the thermal rate coefficients.The results are consistent with those from other theoretical methods,such as variational transition state theory and quantum dynamics.Especially,RPMD results exhibit negative temperature dependence,which is similar to the results from variational transition state theory but different from the ones from ground state quantum dynamics calculations.展开更多
The ab initio calculations of electron-impact resonant excitation rate coefficients from the ground level to 54 fine-structure levels of 3d94l (1 = s, p, d, f) configurations of Ni-like tantalum ion are performed by...The ab initio calculations of electron-impact resonant excitation rate coefficients from the ground level to 54 fine-structure levels of 3d94l (1 = s, p, d, f) configurations of Ni-like tantalum ion are performed by using a fully relativistic distorted-wave approximation. The configuration-interaction effects are taken into account. The decays to autoionizing levels possibly followed by autoionization cascades are also included in the calculation. The contributions from doubly-excited intermediate states of Cu-like 31^17n′l′n′l″ (n′ = 4, 5; n″ = 5 - 15) are calculated explicitly, and the contributions from high Rydberg states (n″〉 15) are taken into account by using n-3 scaling law. The present results should be more accurate than the existent calculations.展开更多
This paper calculates the electron impact excitation rate coefficients from the ground term 2s^22p^2 3p to the excited terms of the 2s^22p^2, 2s^2p^3, 2s^22p3s, 2s^22p3p, and 2s^22p3d configurations of N II. In the ca...This paper calculates the electron impact excitation rate coefficients from the ground term 2s^22p^2 3p to the excited terms of the 2s^22p^2, 2s^2p^3, 2s^22p3s, 2s^22p3p, and 2s^22p3d configurations of N II. In the calculations, multiconfiguration Dirac-Fork wave functions have been applied to describe the target-ion states and relativistic distorted-wave calculation has been performed to generate fine-structure collision strengths. The collision strengths are then averaged over a Maxwellian distribution of electron velocities in order to generate the effective collision strengths. The calculated rate coefficients are compared with available experimental and theoretical data, and some good agreements are found for the outer shell electron excitations. But for the inner shell electron excitations there are still some differences between the present calculations and available experiments.展开更多
The prototype tetra-atomic reaction F+H2O→HF+OH plays a significant role in both atmospheric and astronomical chemistry.In this work,thermal rate coefficients of this reaction are determined with the ring polymer mol...The prototype tetra-atomic reaction F+H2O→HF+OH plays a significant role in both atmospheric and astronomical chemistry.In this work,thermal rate coefficients of this reaction are determined with the ring polymer molecular dynamics(RPMD)method on a full-dimensional potential energy surface(PES).This PES is the most accurate one for the title reaction,as demonstrated by the correct barrier height and reaction energy,compared to the benchmark calculations by the focal point analysis and the high accuracy extrapolated ab initio thermochemistry methods.The RPMD rate coefficients are in excellent agreement with those calculated by the semiclassical transition state theory and a two-dimensional master equation technique,and some experimental measurements.As has been found in many RPMD applications,quantum effects,including tunneling and zero-point energy effects,can be efficiently and effectively captured by the RPMD method.In addition,the convergence of the results with respect to the number of beads is rapid,which is also consistent with previous RPMD applications.展开更多
A method based upon the weighted total cross section (WTCS) theory is proposed to calculate the photo-ionisation cross sections and the radiative recombination rate coefficients between the fundamental level of CO a...A method based upon the weighted total cross section (WTCS) theory is proposed to calculate the photo-ionisation cross sections and the radiative recombination rate coefficients between the fundamental level of CO and the main electronic states of its corresponding ion. Total photo-ionisation cross sections and radiative recombination rate coefficients are determined from the calculation of elementary vibrational photo-ionisation cross sections. Transitions be- tween CO+(X, A and B) and CO(X) are considered. Total photo-ionisation cross sections and recombination coefficients are computed in the temperature interval 500-15000 K.展开更多
Fusion power output is proportional not only to the fuel particle number densities participating in reaction but also to the fusion reaction rate coefficient (or reactivity), which is dependent on reactant velocity ...Fusion power output is proportional not only to the fuel particle number densities participating in reaction but also to the fusion reaction rate coefficient (or reactivity), which is dependent on reactant velocity distribution functions. They are usuMly assumed to be dual Maxwellian distribution functions with the same temperature for thermal nuclear fusion circumstances. However, if high power neutral beam injection and minority ion species ICRF plasma heating, or multi-pinched plasma beam head-on collision, in a converging region are required and investigated in future large scale fusion reactors, then the fractions of the injected energetic fast ion tail resulting from ionization or charge exchange will be large enough and their contribution to the non-Maxwellian distribution functions is not negligible, hence to the fusion reaction rate coefficient or calculation of fusion power. In such cases, beam-target, and beam-beam reaction enhancement effect contributions should play very important roles. In this paper, several useful formulae to calculate the fusion reaction rate coefticient for different beam and target combination scenarios are derived in detail展开更多
Background Previous studies have suggested that nomogram can simplize complicated calculations of several varibles. A simple nomogram was constructed to estimate absorption rate coefficient (k a) by using the peak t...Background Previous studies have suggested that nomogram can simplize complicated calculations of several varibles. A simple nomogram was constructed to estimate absorption rate coefficient (k a) by using the peak time (t peak ) and the elimination rate coefficient (k e) of drugs administered orally Methods The nomogram was based on the plasma concentration-time (C-T) curve equation and the function relation between t peak , k a and k e A mathematical analysis was presented for the construction of single chart nomogram To check the degree of accuracy of the developed nomogram, we used it to analyze retrospective profiles of 46 drugs and compared the k a values obtained graphically and those calculated by numerically solving the descriptive equation In addition, we measured the carbocisteine concentration of 18 healthy volunteers by HPLC with fluorescence detection To analyze performance error, the measured carbocisteine concentrations were compared with predicted concentrations by the k a obtained from the nomograms along with the other pharmacokinetic parameters Results The estimated of k a values from nomograms were in very close proximity with the numerical values The performance error was as follows: median performance error (MDPE) and median absolute performance error (MDAPE) were 1 32% and 18 15%, respectively Conclusions The developed nomogram is accurate and reliable The size of performance error meets the demand of clinical pharmacokinetics Therefore, the nomograms can offer another convenient and easy method for rational individualized dosage regimens展开更多
The Rb(5Dj)+H2→RbH+H photochemical reaction has been studied. Rb vapor mixed with H2 is irradiated in a glass cell with 778-nm pulses which populate one of the 52D states by two-photon absorption. Measurements fo...The Rb(5Dj)+H2→RbH+H photochemical reaction has been studied. Rb vapor mixed with H2 is irradiated in a glass cell with 778-nm pulses which populate one of the 52D states by two-photon absorption. Measurements for the relative intensities of the atomic fluorescence and the absorption of the RbH product near the axis of the cell yield the rate coefficients for the Rb(5D3/2)+H2 and Rb(5D5/2)+H2 reactions, which are (3.6±1.3) ×10^-11 and (1.7±0.6)×10^-11 cm^3/s, respectively. The relative reactivity with H2 for Rb(5D3/2) is higher than that for Rb(5D5/2).展开更多
The ring-polymer molecular dynamics(RPMD)was used to calculate the thermal rate coefficients and kinetic isotope effects of the heavy-light-heavy abstract reaction Cl+XCl→XCl+Cl(X=H,D,Mu).For the Cl+HCl reaction,the ...The ring-polymer molecular dynamics(RPMD)was used to calculate the thermal rate coefficients and kinetic isotope effects of the heavy-light-heavy abstract reaction Cl+XCl→XCl+Cl(X=H,D,Mu).For the Cl+HCl reaction,the excellent agreement between the RPMD and experimental values provides a strong proof for the accuracy of the RPMD theory.And the RPMD results are also consistent with results from other theoretical methods including improved-canonical-variational-theory and quantum dynamics.The most novel finding is that there is a double peak in Cl+MuCl reaction near the transition state,leaving a free energy well.It comes from the mode softening of the reaction system at the peak of the potential energy surface.Such an explicit free energy well suggests strongly there is an observable resonance.And for the Cl+DCl reaction,the RPMD rate coefficient again gives very accurate results compared with experimental values.The only exception is at the temperature of 312.5 K,results from RPMD and all other theoretical methods are close to each other but slightly lower than the experimental value,which indicates experimental or potential energy surface deficiency.展开更多
The reactive collisions of nitrogen ion with hydrogen and its isotopic variations have great significance in the field of astrophysics.Herein,the state-to-state quantum time-dependent wave packet calculations of N^(+)...The reactive collisions of nitrogen ion with hydrogen and its isotopic variations have great significance in the field of astrophysics.Herein,the state-to-state quantum time-dependent wave packet calculations of N^(+)(3P)+HD→NH^(+)/ND^(+)+D/H reaction are carried out based on the recently developed potential energy surface[Phys.Chem.Chem.Phys.2122203(2019)].The integral cross sections(ICSs)and rate coefficients of both channels are precisely determined at the state-to-state level.The results of total ICSs and rate coefficients present a dramatic preference on the ND+product over the NH^(+)product,conforming to the long-lived complex-forming mechanism.Product state-resolved ICSs indicate that both the product molecules are difficult to excite to higher vibrational states,and the ND^(+)product has a hotter rotational state distribution.Moreover,the integral cross sections and rate coefficients are precisely determined at the state-to-state level and insights are provided about the differences between the two channels.The present results would provide an important reference for the further experimental studies at the finer level for this interstellar chemical reaction.The datasets presented in this paper,including the ICSs and rate coefficients of the two products for the title reaction,are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00034.展开更多
The low-energy mutual neutralization(MN)reactions Na^(+)+H^(-)→Na(nl)+H have been studied by employing the full quantum-mechanical molecular-orbital close-coupling(QMOCC)method over a wide energy range of 10^(-3)-10^...The low-energy mutual neutralization(MN)reactions Na^(+)+H^(-)→Na(nl)+H have been studied by employing the full quantum-mechanical molecular-orbital close-coupling(QMOCC)method over a wide energy range of 10^(-3)-10^(3) e V/u.Total and state-selective cross sections have been investigated and compared with the available theoretical and experimental data,and the state-selective rate coefficients for the temperature range of 100-10000 K have been obtained.In the present work,all the necessary highly excited states are included,and the influences of rotational couplings and 10 active electrons are considered.It is found that in the energy below 10 e V/u,the Na(4s)state is the most dominant exit state with a contribution of approximately 78%to the branch fraction,which is in best agreement with the experimental data.For energies above 10 e V/u,the MN total cross section is larger than those obtained in other theoretical calculations and shows a slow decreasing trend because the main exit states change,when the energy is above 100 e V/u,the dominant exit state becomes the Na(3p)state,while the Na(4s)state becomes the third most important exit state.The datasets presented in this paper,including the potential energy curve,the radial and rotational couplings,the total and state-selective cross sections,are openly available at https://doi.org/10.57760/sciencedb.j00113.00112.展开更多
X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic r...X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic recombination, collisional ionization and resonance excitation from the neighbouring ion (Al^9+ and Al^11+ ) charge states of the target ion (Al^10+) are considered in the model. In addition, the contributions of different atomic processes to the x-ray spectrum are analysed. The results show that dielectronic recombination, radiative recombination, collisional ionization and resonance excitation, other than direct collisional excitation, are very important processes.展开更多
When radionuclides migrate in porous media with water serving as carrier, the mechanism of sorption and desorption is not negligible. nonequilibrium conditions exist in sorption and desorption. In this paper,a numeric...When radionuclides migrate in porous media with water serving as carrier, the mechanism of sorption and desorption is not negligible. nonequilibrium conditions exist in sorption and desorption. In this paper,a numerical model of radionuclide migration with nonequilibrium sorption was developed.The algorithm of numerical descretizing and direct substituting was adopted in coupling of the convective-dispersive equation and the nonequilibrium sorption isotherm in this model ,and this makes it easier to solve the model numerically.A quantitative analysis is made for the first time that the influence of nonequilibrium sorption, represented by the rate coefficient which shows how quickly the nonequilibrium condition in sorption and desorption reaches equilibrium on the migration of radionuclide,and results show that it affects the migration perceptibly. Finally the model was verified by using the observed data of radionuclide migration test conducted in the field, and which clarified its availability.展开更多
The KLn dielectronic recombination processes of trapped highly charged B-like through He-like Cu ions are studied theoretically, and the theoretical results are used to analyse our previous experimental data at Heidel...The KLn dielectronic recombination processes of trapped highly charged B-like through He-like Cu ions are studied theoretically, and the theoretical results are used to analyse our previous experimental data at Heidelberg electron beam ion trap (EBIT). The theoretical resonant positions agree with the experimental resonant positions to a precision of 0.4%, in comparison with the resonant positions of those highest peaks between theory and experiment. The experimental spectra are then fitted using a formula with the theoretical resonant energies and strengths, the result shows good overall agreement between theory and experiment over a wide electron energy range. The distribution of highly charged states is obtained from the fitting parameters.展开更多
Based on the multi-configuration Dirac-Fock method, theoretical calculations are carried out for the dielectronic recombination (DR) rate coefficients and the collision excitation rate coefficients of Sn^10+ ions. ...Based on the multi-configuration Dirac-Fock method, theoretical calculations are carried out for the dielectronic recombination (DR) rate coefficients and the collision excitation rate coefficients of Sn^10+ ions. It is found that the total DR rate coefficient has its maximum value between 10eV and 100eV and is greater than either the radiative recombination or three-body recombination rate coefficients (the number of free electrons per unit is 10^21 cm^3) for the ease of Te 〉 1 eV. Therefore, DR can strongly influence the ionization balance of laser produced multi-charged tin ions. The related dieleetronie satellite cannot be ignored at low temperature Te 〈 5 eV.展开更多
The kinetics mechanism of the dissociation reactions in a NO/SO2/N2/O2 system was investigated in consideration of energetic electrons' impacts on a non-thermal plasma. A model was derived from the Boltzmann equation...The kinetics mechanism of the dissociation reactions in a NO/SO2/N2/O2 system was investigated in consideration of energetic electrons' impacts on a non-thermal plasma. A model was derived from the Boltzmann equation and molecule collision theory to predict the dissociation reaction rate coefficients. Upon comparison with available literature, the model was confirmed to be acceptably accurate in general. Several reaction rate coefficients of the NO/SO2/N2/O2 dissociation system were derived according to the Arrhenius formula. The activation energies of each plasma reaction were calculated by quantum chemistry methods. The relation between the dissociation reaction rate coefficient and electron temperature was established to describe the importance of each reaction and to predict relevant processes of gaseous chemical reactions. The sensitivity of the mechanism of NO/SO2/N2/O2 dissociation reaction in a non-thermal plasma was also analysed.展开更多
A systematic study is carried out on the angular distribution and polarization of photons emitted following radiative-recombination of bare and He-like ions of Ne, At, Ni and Mo with a unidirectional electron beam. In...A systematic study is carried out on the angular distribution and polarization of photons emitted following radiative-recombination of bare and He-like ions of Ne, At, Ni and Mo with a unidirectional electron beam. In order to incorporate the screening effect due to inner-shell electrons, a distorted wave method is used. Scaling rules for polarization of the photon following radiative recombination to both bare and He-like ions are given for the incident energy regions up to six times the ionization threshold energy of the final state.展开更多
Ring polymer molecular dynamics(RPMD)calculations for the C(^(1)D)+H_(2)reaction are performed on the Zhang-Ma-Bian ab initio potential energy surfaces(PESs)recently constructed by our group,which are unique in very g...Ring polymer molecular dynamics(RPMD)calculations for the C(^(1)D)+H_(2)reaction are performed on the Zhang-Ma-Bian ab initio potential energy surfaces(PESs)recently constructed by our group,which are unique in very good descriptions of the regions around conical intersections and of van der Waals(vdW)interactions.The calculated reaction thermal rate coefficients are in very good agreement with the latest experimental results.The rate coefficients obtained from the ground˜a^(1)A′ZMB-a PES are much larger than those from the previous RKHS PES,which can be attributed to that the vdW saddles on our PESs have very different dynamical effects from the vdW wells on the previous PESs,indicating that the RPMD approach is able to include dynamical effects of the topological structures caused by vdW interactions.The importance of the excited˜b^(1)A′′ZMB-b PES and quantum effects in the title reaction is also underscored.展开更多
Ab initio calculation of the total dielectronic recombination (DR) rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration inter...Ab initio calculation of the total dielectronic recombination (DR) rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration interaction. The contributions to the total DR rate coefficients are explicitly calculated from the complexes of Ni-like tantalum:3s^23p^63d3/2^33d5/2^6n′l′,3s^23p^53d^10n′l′,3s3p^63d^10n′l′,3s^23p^63d^84ln′l′,3s^23p^53d^94ln′l′ and 3s3p^63d^94ln′l′ with n′≤25, and 3s^23p^63d^85ln′l′ with n′≤9.The l′and n′ dependences of partial DR rate coefficients are investigated. The contributions from higher n^complexes are evaluated by a level-by-level extrapolation method. The total DR rate coefficients mainly come from the complex series 3s^23p^63d^84ln′l′,3s^23p^53d^94ln′l′and are fitted to an empirical formula with high accuracy. Comparison of the present results with those of other works shows that the previously published data underestimate significantly the DR rates of Co-like tantalum.展开更多
CF3CF=CF2 is a potential source of atmospheric trifluoroacetic acid(CF3C(O)OH).The kinetics of the reaction of the simplest Criegee intermediate(CH2OO)with CF3CF=CF2 was studied by using the OH laser-induced fluoresce...CF3CF=CF2 is a potential source of atmospheric trifluoroacetic acid(CF3C(O)OH).The kinetics of the reaction of the simplest Criegee intermediate(CH2OO)with CF3CF=CF2 was studied by using the OH laser-induced fluorescence method.At 10 torr,the rate co-efficients were measured to be(1.45±0.14)×10^-13,(1.18±0.11)×10^-13,(1.11±0.08)×10^-13,and(1.04±0.08)×10^-13·cm^3·molecule^-1·s^-1 at 283,298,308 and 318 K,respectively.The activation energy of(-1.66±0.21)kcal/mol was derived from the Arrhenius equation.No obvious pressure dependence was observed.展开更多
基金supported by the National Natural Science Foundation of China(No.21503130 and No.11674212,and No.21603144)supported by the Young Eastern Scholar Program of the Shanghai Municipal Education Commission(QD2016021)+1 种基金the Shanghai Key Laboratory of High Temperature Superconductors(No.14DZ2260700)supported by Shanghai Sailing Program(No.2016YF1408400).
文摘The ring-polymer molecular dynamics(RPMD)was used to calculate the thermal rate coefficients of the multi-channel roaming reaction H+MgH→Mg+H_(2).Two reaction channels,tight and roaming,are explicitly considered.This is a pioneering attempt of exerting RPMD method to multichannel reactions.With the help of a newly developed optimization-interpolation protocol for preparing the initial structures and adaptive protocol for choosing the force constants,we have successfully obtained the thermal rate coefficients.The results are consistent with those from other theoretical methods,such as variational transition state theory and quantum dynamics.Especially,RPMD results exhibit negative temperature dependence,which is similar to the results from variational transition state theory but different from the ones from ground state quantum dynamics calculations.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10574029 and No 10434050, the Chinese Association of Atomic and Molecular Data and National High-Tech ICF Committee in China.
文摘The ab initio calculations of electron-impact resonant excitation rate coefficients from the ground level to 54 fine-structure levels of 3d94l (1 = s, p, d, f) configurations of Ni-like tantalum ion are performed by using a fully relativistic distorted-wave approximation. The configuration-interaction effects are taken into account. The decays to autoionizing levels possibly followed by autoionization cascades are also included in the calculation. The contributions from doubly-excited intermediate states of Cu-like 31^17n′l′n′l″ (n′ = 4, 5; n″ = 5 - 15) are calculated explicitly, and the contributions from high Rydberg states (n″〉 15) are taken into account by using n-3 scaling law. The present results should be more accurate than the existent calculations.
基金supported by the National Natural Science Foundation of China (Grant Nos.10774122 and 10876028)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No.20070736001)the Technology and Innovation Program of Northwest Normal University (Grant No.NWNU-KJCXGC-03-21)
文摘This paper calculates the electron impact excitation rate coefficients from the ground term 2s^22p^2 3p to the excited terms of the 2s^22p^2, 2s^2p^3, 2s^22p3s, 2s^22p3p, and 2s^22p3d configurations of N II. In the calculations, multiconfiguration Dirac-Fork wave functions have been applied to describe the target-ion states and relativistic distorted-wave calculation has been performed to generate fine-structure collision strengths. The collision strengths are then averaged over a Maxwellian distribution of electron velocities in order to generate the effective collision strengths. The calculated rate coefficients are compared with available experimental and theoretical data, and some good agreements are found for the outer shell electron excitations. But for the inner shell electron excitations there are still some differences between the present calculations and available experiments.
基金supported by the National Natural Science Foundation of China(No.21573027)
文摘The prototype tetra-atomic reaction F+H2O→HF+OH plays a significant role in both atmospheric and astronomical chemistry.In this work,thermal rate coefficients of this reaction are determined with the ring polymer molecular dynamics(RPMD)method on a full-dimensional potential energy surface(PES).This PES is the most accurate one for the title reaction,as demonstrated by the correct barrier height and reaction energy,compared to the benchmark calculations by the focal point analysis and the high accuracy extrapolated ab initio thermochemistry methods.The RPMD rate coefficients are in excellent agreement with those calculated by the semiclassical transition state theory and a two-dimensional master equation technique,and some experimental measurements.As has been found in many RPMD applications,quantum effects,including tunneling and zero-point energy effects,can be efficiently and effectively captured by the RPMD method.In addition,the convergence of the results with respect to the number of beads is rapid,which is also consistent with previous RPMD applications.
基金the "Comite Mixté Franco-Tunisien pour la Coopération Universitaire(Partenariat Hubert Curien,Utique,Tunisie)"for its financial support in the achievement of this work
文摘A method based upon the weighted total cross section (WTCS) theory is proposed to calculate the photo-ionisation cross sections and the radiative recombination rate coefficients between the fundamental level of CO and the main electronic states of its corresponding ion. Total photo-ionisation cross sections and radiative recombination rate coefficients are determined from the calculation of elementary vibrational photo-ionisation cross sections. Transitions be- tween CO+(X, A and B) and CO(X) are considered. Total photo-ionisation cross sections and recombination coefficients are computed in the temperature interval 500-15000 K.
基金Supported by the International Thermonuclear Experimental Reactor Project of China under Grant No 2013GB114003the National Natural Science Foundation of China under Grant No 11275135
文摘Fusion power output is proportional not only to the fuel particle number densities participating in reaction but also to the fusion reaction rate coefficient (or reactivity), which is dependent on reactant velocity distribution functions. They are usuMly assumed to be dual Maxwellian distribution functions with the same temperature for thermal nuclear fusion circumstances. However, if high power neutral beam injection and minority ion species ICRF plasma heating, or multi-pinched plasma beam head-on collision, in a converging region are required and investigated in future large scale fusion reactors, then the fractions of the injected energetic fast ion tail resulting from ionization or charge exchange will be large enough and their contribution to the non-Maxwellian distribution functions is not negligible, hence to the fusion reaction rate coefficient or calculation of fusion power. In such cases, beam-target, and beam-beam reaction enhancement effect contributions should play very important roles. In this paper, several useful formulae to calculate the fusion reaction rate coefticient for different beam and target combination scenarios are derived in detail
文摘Background Previous studies have suggested that nomogram can simplize complicated calculations of several varibles. A simple nomogram was constructed to estimate absorption rate coefficient (k a) by using the peak time (t peak ) and the elimination rate coefficient (k e) of drugs administered orally Methods The nomogram was based on the plasma concentration-time (C-T) curve equation and the function relation between t peak , k a and k e A mathematical analysis was presented for the construction of single chart nomogram To check the degree of accuracy of the developed nomogram, we used it to analyze retrospective profiles of 46 drugs and compared the k a values obtained graphically and those calculated by numerically solving the descriptive equation In addition, we measured the carbocisteine concentration of 18 healthy volunteers by HPLC with fluorescence detection To analyze performance error, the measured carbocisteine concentrations were compared with predicted concentrations by the k a obtained from the nomograms along with the other pharmacokinetic parameters Results The estimated of k a values from nomograms were in very close proximity with the numerical values The performance error was as follows: median performance error (MDPE) and median absolute performance error (MDAPE) were 1 32% and 18 15%, respectively Conclusions The developed nomogram is accurate and reliable The size of performance error meets the demand of clinical pharmacokinetics Therefore, the nomograms can offer another convenient and easy method for rational individualized dosage regimens
基金supported by the National Natural Science Foundation of China under Grant No.10664003
文摘The Rb(5Dj)+H2→RbH+H photochemical reaction has been studied. Rb vapor mixed with H2 is irradiated in a glass cell with 778-nm pulses which populate one of the 52D states by two-photon absorption. Measurements for the relative intensities of the atomic fluorescence and the absorption of the RbH product near the axis of the cell yield the rate coefficients for the Rb(5D3/2)+H2 and Rb(5D5/2)+H2 reactions, which are (3.6±1.3) ×10^-11 and (1.7±0.6)×10^-11 cm^3/s, respectively. The relative reactivity with H2 for Rb(5D3/2) is higher than that for Rb(5D5/2).
基金This work was supported by the National Nature Science Foundation of China(No.21503130 and No.11674212 to Yong-le Li,and No.21603144 to Jia-ning Song)Yong-le Li is also supported by the Young Eastern Scholar Program of the Shanghai Municipal Education Commission(No.QD2016021)+1 种基金the Shanghai Key Laboratory of High Temperature Superconductors(No.14DZ2260700)Jia-ning Song is also supported by Shanghai Sailing Program(No.2016YF1408400).
文摘The ring-polymer molecular dynamics(RPMD)was used to calculate the thermal rate coefficients and kinetic isotope effects of the heavy-light-heavy abstract reaction Cl+XCl→XCl+Cl(X=H,D,Mu).For the Cl+HCl reaction,the excellent agreement between the RPMD and experimental values provides a strong proof for the accuracy of the RPMD theory.And the RPMD results are also consistent with results from other theoretical methods including improved-canonical-variational-theory and quantum dynamics.The most novel finding is that there is a double peak in Cl+MuCl reaction near the transition state,leaving a free energy well.It comes from the mode softening of the reaction system at the peak of the potential energy surface.Such an explicit free energy well suggests strongly there is an observable resonance.And for the Cl+DCl reaction,the RPMD rate coefficient again gives very accurate results compared with experimental values.The only exception is at the temperature of 312.5 K,results from RPMD and all other theoretical methods are close to each other but slightly lower than the experimental value,which indicates experimental or potential energy surface deficiency.
基金Project supported by the National Natural Science Foundation of China(Grant No.11774043).
文摘The reactive collisions of nitrogen ion with hydrogen and its isotopic variations have great significance in the field of astrophysics.Herein,the state-to-state quantum time-dependent wave packet calculations of N^(+)(3P)+HD→NH^(+)/ND^(+)+D/H reaction are carried out based on the recently developed potential energy surface[Phys.Chem.Chem.Phys.2122203(2019)].The integral cross sections(ICSs)and rate coefficients of both channels are precisely determined at the state-to-state level.The results of total ICSs and rate coefficients present a dramatic preference on the ND+product over the NH^(+)product,conforming to the long-lived complex-forming mechanism.Product state-resolved ICSs indicate that both the product molecules are difficult to excite to higher vibrational states,and the ND^(+)product has a hotter rotational state distribution.Moreover,the integral cross sections and rate coefficients are precisely determined at the state-to-state level and insights are provided about the differences between the two channels.The present results would provide an important reference for the further experimental studies at the finer level for this interstellar chemical reaction.The datasets presented in this paper,including the ICSs and rate coefficients of the two products for the title reaction,are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00034.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12204288,11934004,and 12203106)。
文摘The low-energy mutual neutralization(MN)reactions Na^(+)+H^(-)→Na(nl)+H have been studied by employing the full quantum-mechanical molecular-orbital close-coupling(QMOCC)method over a wide energy range of 10^(-3)-10^(3) e V/u.Total and state-selective cross sections have been investigated and compared with the available theoretical and experimental data,and the state-selective rate coefficients for the temperature range of 100-10000 K have been obtained.In the present work,all the necessary highly excited states are included,and the influences of rotational couplings and 10 active electrons are considered.It is found that in the energy below 10 e V/u,the Na(4s)state is the most dominant exit state with a contribution of approximately 78%to the branch fraction,which is in best agreement with the experimental data.For energies above 10 e V/u,the MN total cross section is larger than those obtained in other theoretical calculations and shows a slow decreasing trend because the main exit states change,when the energy is above 100 e V/u,the dominant exit state becomes the Na(3p)state,while the Na(4s)state becomes the third most important exit state.The datasets presented in this paper,including the potential energy curve,the radial and rotational couplings,the total and state-selective cross sections,are openly available at https://doi.org/10.57760/sciencedb.j00113.00112.
文摘X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic recombination, collisional ionization and resonance excitation from the neighbouring ion (Al^9+ and Al^11+ ) charge states of the target ion (Al^10+) are considered in the model. In addition, the contributions of different atomic processes to the x-ray spectrum are analysed. The results show that dielectronic recombination, radiative recombination, collisional ionization and resonance excitation, other than direct collisional excitation, are very important processes.
文摘When radionuclides migrate in porous media with water serving as carrier, the mechanism of sorption and desorption is not negligible. nonequilibrium conditions exist in sorption and desorption. In this paper,a numerical model of radionuclide migration with nonequilibrium sorption was developed.The algorithm of numerical descretizing and direct substituting was adopted in coupling of the convective-dispersive equation and the nonequilibrium sorption isotherm in this model ,and this makes it easier to solve the model numerically.A quantitative analysis is made for the first time that the influence of nonequilibrium sorption, represented by the rate coefficient which shows how quickly the nonequilibrium condition in sorption and desorption reaches equilibrium on the migration of radionuclide,and results show that it affects the migration perceptibly. Finally the model was verified by using the observed data of radionuclide migration test conducted in the field, and which clarified its availability.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10774026 and 10574029, the Programme for New Century Excellent Talents in University (NCET), and the Shanghai Leading Academic Discipline Project under Grant No B107.
文摘The KLn dielectronic recombination processes of trapped highly charged B-like through He-like Cu ions are studied theoretically, and the theoretical results are used to analyse our previous experimental data at Heidelberg electron beam ion trap (EBIT). The theoretical resonant positions agree with the experimental resonant positions to a precision of 0.4%, in comparison with the resonant positions of those highest peaks between theory and experiment. The experimental spectra are then fitted using a formula with the theoretical resonant energies and strengths, the result shows good overall agreement between theory and experiment over a wide electron energy range. The distribution of highly charged states is obtained from the fitting parameters.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10434100 and 10774122, the Foundation of China/Ireland Science and Technology Collaboration Research under Grant No CI-2004-07, the Specialized Research Fund for the Doctoral Programme of Higher Education of China under Grant No 20070736001, and the Foundation of Northwest Normal University under Grant No NWNU-KJCXGC-03-21.
文摘Based on the multi-configuration Dirac-Fock method, theoretical calculations are carried out for the dielectronic recombination (DR) rate coefficients and the collision excitation rate coefficients of Sn^10+ ions. It is found that the total DR rate coefficient has its maximum value between 10eV and 100eV and is greater than either the radiative recombination or three-body recombination rate coefficients (the number of free electrons per unit is 10^21 cm^3) for the ease of Te 〉 1 eV. Therefore, DR can strongly influence the ionization balance of laser produced multi-charged tin ions. The related dieleetronie satellite cannot be ignored at low temperature Te 〈 5 eV.
文摘The kinetics mechanism of the dissociation reactions in a NO/SO2/N2/O2 system was investigated in consideration of energetic electrons' impacts on a non-thermal plasma. A model was derived from the Boltzmann equation and molecule collision theory to predict the dissociation reaction rate coefficients. Upon comparison with available literature, the model was confirmed to be acceptably accurate in general. Several reaction rate coefficients of the NO/SO2/N2/O2 dissociation system were derived according to the Arrhenius formula. The activation energies of each plasma reaction were calculated by quantum chemistry methods. The relation between the dissociation reaction rate coefficient and electron temperature was established to describe the importance of each reaction and to predict relevant processes of gaseous chemical reactions. The sensitivity of the mechanism of NO/SO2/N2/O2 dissociation reaction in a non-thermal plasma was also analysed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10125520 and 10434050, and the Swedish Research Council (VR) under the Swedish Research Links Programme.
文摘A systematic study is carried out on the angular distribution and polarization of photons emitted following radiative-recombination of bare and He-like ions of Ne, At, Ni and Mo with a unidirectional electron beam. In order to incorporate the screening effect due to inner-shell electrons, a distorted wave method is used. Scaling rules for polarization of the photon following radiative recombination to both bare and He-like ions are given for the incident energy regions up to six times the ionization threshold energy of the final state.
基金supported by the National Natural Science Foundation of China(No.21773251 and No.21973098)the Youth Innovation Promotion Association CAS(No.2018045)the Beijing National Laboratory for Molecular Sciences。
文摘Ring polymer molecular dynamics(RPMD)calculations for the C(^(1)D)+H_(2)reaction are performed on the Zhang-Ma-Bian ab initio potential energy surfaces(PESs)recently constructed by our group,which are unique in very good descriptions of the regions around conical intersections and of van der Waals(vdW)interactions.The calculated reaction thermal rate coefficients are in very good agreement with the latest experimental results.The rate coefficients obtained from the ground˜a^(1)A′ZMB-a PES are much larger than those from the previous RKHS PES,which can be attributed to that the vdW saddles on our PESs have very different dynamical effects from the vdW wells on the previous PESs,indicating that the RPMD approach is able to include dynamical effects of the topological structures caused by vdW interactions.The importance of the excited˜b^(1)A′′ZMB-b PES and quantum effects in the title reaction is also underscored.
基金supported by the National Natural Science Foundation of China (Grant No 10574029)the Chinese Association of Atomic and Molecular Data and National High-Tech ICF Committee in Chinasupported by Shanghai Leading Academic Discipline Project (Grant No B107)
文摘Ab initio calculation of the total dielectronic recombination (DR) rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration interaction. The contributions to the total DR rate coefficients are explicitly calculated from the complexes of Ni-like tantalum:3s^23p^63d3/2^33d5/2^6n′l′,3s^23p^53d^10n′l′,3s3p^63d^10n′l′,3s^23p^63d^84ln′l′,3s^23p^53d^94ln′l′ and 3s3p^63d^94ln′l′ with n′≤25, and 3s^23p^63d^85ln′l′ with n′≤9.The l′and n′ dependences of partial DR rate coefficients are investigated. The contributions from higher n^complexes are evaluated by a level-by-level extrapolation method. The total DR rate coefficients mainly come from the complex series 3s^23p^63d^84ln′l′,3s^23p^53d^94ln′l′and are fitted to an empirical formula with high accuracy. Comparison of the present results with those of other works shows that the previously published data underestimate significantly the DR rates of Co-like tantalum.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (No.XDB17000000)the National Natural Science Foundation of China (No.21873098)+2 种基金International Partnership Program of Chinese Academy of Sciences (No.121421KYSB20170012)the Chemical Dynamics Research Center (No.21688102)the Liaoning Revitalization Talents Program (No.XLYC1807248).
文摘CF3CF=CF2 is a potential source of atmospheric trifluoroacetic acid(CF3C(O)OH).The kinetics of the reaction of the simplest Criegee intermediate(CH2OO)with CF3CF=CF2 was studied by using the OH laser-induced fluorescence method.At 10 torr,the rate co-efficients were measured to be(1.45±0.14)×10^-13,(1.18±0.11)×10^-13,(1.11±0.08)×10^-13,and(1.04±0.08)×10^-13·cm^3·molecule^-1·s^-1 at 283,298,308 and 318 K,respectively.The activation energy of(-1.66±0.21)kcal/mol was derived from the Arrhenius equation.No obvious pressure dependence was observed.