Calculating the inter-layer ion diffusion barrier, a crucial metric for evaluating the rate performance of 2D electrode materials, is time-consuming using the transition state search approach. A novel electrostatic po...Calculating the inter-layer ion diffusion barrier, a crucial metric for evaluating the rate performance of 2D electrode materials, is time-consuming using the transition state search approach. A novel electrostatic potential distribution image (EPDI) transfer learning method has been proposed to efficiently and accurately predict the lithium diffusion barriers on metal element-doped transition metal dichalcogenide (TMD) surfaces. Through the analysis of the mean electrostatic potential (MEP) around binding sites, a positive correlation between binding energy and MEP in VIB-TMDs was identified. Subsequently, transfer learning techniques were used to develop a DenseNet121-TL model for establishing a more accurate mapping between the binding energy and electrostatic potential distribution. Trained on training sets containing 33% and 50% transition state search calculation results, which save 66% and 50% of the calculation time, respectively, the model achieves accurate predictions of the saddle point binding energy with mean absolute errors (MAEs) of 0.0444 and 0.0287 eV on the testing set. Based on the prediction of saddle point binding energies, we obtained a diffusion minimum energy profile with an MAE of 0.0235 eV. Furthermore, by analyzing the diffusion data, we observed that the diffusion barrier was lowered by 10% on V-doped TiS2 compared to the stoichiometric surface. Our findings are expected to provide new insights for the high-throughput calculation of ion diffusion on 2D materials.展开更多
The electrostatic potential energy model of hydrotalcites was based on the theory of crystallography. The anionic potential energy of MgAl-hydrotalcites, with 20 layers and 2107 anions per layer, was calculated, and t...The electrostatic potential energy model of hydrotalcites was based on the theory of crystallography. The anionic potential energy of MgAl-hydrotalcites, with 20 layers and 2107 anions per layer, was calculated, and the anionic stability of the hydrotalcites was investigated. The charge density of the layer and the distance between the adjacent anions varied with the molar ratio of Al^3＋/（Mg^2＋ ＋ Al^3＋）. Anionic potential energy depended on the charge and size of the anions. Calculation results remained consistent with thermal stability and the ion exchange ability reported. This model is able to predict anionic stability of the hydrotalcites.展开更多
Polychlorinated dibenzo-p-dioxins（PCDDs） are a group of important persistent organic pollutants.They are highly toxic and persistent in environment.In the present study,geometrical optimization and electrostatic pot...Polychlorinated dibenzo-p-dioxins（PCDDs） are a group of important persistent organic pollutants.They are highly toxic and persistent in environment.In the present study,geometrical optimization and electrostatic potential calculations have been performed for 75 PCDD congeners and dibenzo-p-dioxin（DD） at the HF/6-31G＊ level of theory.A number of statistically based parameters have been extracted.Linear relationships between vapor pressures（logpL）,aqueous solubilities（logSw）,n-octanol/water partition coefficients（logKow） of PCDDs and structural descriptors have been established by stepwise linear regression analysis.The result shows that the quantities derived from the surface electrostatic potentials Vmin,Π,and Vs,av＋,together with Vmc（the molecular volume） and ELUMO（the energy of the lowest unoccupied molecular orbital） can be well used to express the quantitative structure-property relationships of PCDDs.Predictive capabilities of the models have also been demonstrated by leave-one-out cross-validation with the cross-validated correlation coefficient（Rcv） above 0.97.Based on these QSPR models,the predicted values have been presented for those PCDD congeners whose experimentally determined physicochemical properties are unavailable.展开更多
Density functional theory （DFT） was applied at the B3LYP/6-31G^＊ level to investigate the relative stability of the five fullerene isomers as well as the anions of C78. Full geometry optimization was carried out an...Density functional theory （DFT） was applied at the B3LYP/6-31G^＊ level to investigate the relative stability of the five fullerene isomers as well as the anions of C78. Full geometry optimization was carried out and distributions of electrostatic potential were calculated. The results showed that the C78（D3h′） cage was the most stable for C78^q-（ q = 2, 4, 6）, and the potential minimum Vmin（r） inside the sphere of C78（Dzh′） was the biggest one among the five isomers of C78. So C78（Dzh′） were electrons from the scandium atoms that were easier to accept than the other four isomers. On the other hand, MEP maps inside the sphere of C78（Dzh′） had three minima near the three vertexes. Each vertex was formed by the intersection of the three hexagons. Our results allowed a possible explanation for the bonding between the scandium atoms and the fullerene cage.展开更多
The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecul...The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecular surface electrostatic potentials VS(r).While there is an ambiguous relationship between the VS,max values and FS values,the decrease of FS is connected(more or less) with increase in VS,min values.展开更多
In the present study,geometrical optimization and electrostatic potential calcula-tions have been performed for 22 nitroaromatic compounds at the HF/6-31G level of theory.A number of statistically based parameters hav...In the present study,geometrical optimization and electrostatic potential calcula-tions have been performed for 22 nitroaromatic compounds at the HF/6-31G level of theory.A number of statistically based parameters have been obtained.Linear relationship between the decomposition enthalpy（taken as a macroscopic property related to explosibility） of nitroaromatic compounds and the structural descriptors have been established by multiple regression method.The result shows that the quantities derived from electrostatic potentialsΣ V sind＋,,Vsind- and Vs,max can be well used to express the quantitative structure-decomposition enthalpy relationship of nitroa-romatic compounds,which proves the general applicability of this parameter set to a great extent.Good predictive capabilities have also been demonstrated.展开更多
Density functional theory （DFT） calculations on three lower energy isomers of C50 were carried out at the B3LYP/6-31G＊ level. Of the three isomers, two have D5h symmetry （a singlet state and a triplet state） and ...Density functional theory （DFT） calculations on three lower energy isomers of C50 were carried out at the B3LYP/6-31G＊ level. Of the three isomers, two have D5h symmetry （a singlet state and a triplet state） and the other one has D3 symmetry. The optimized configurations and electrostatic potential distributions have been obtained. The calculated results show that potential minima Vmin（r） inside the sphere occur at the center of the sphere. The most negative value of the effective Mulliken atomic charge and the largest regions with the most negative MEP outside the sphere are localized in the neighborhood of pentagon-pentagon vertex fusions. They constitute the most probable active sites in chemical reactions. Our results offer a possible explanation for protonation and alkylation of C50 fullerene.展开更多
A method has been developed for separation of 20 kinds of aromatic carboxylic acid using anion-exchange chromatography. A Dionex IonPac AS9-HC guard column （250mm×2mm） was used with a 9mmol/L sodium carbonate s...A method has been developed for separation of 20 kinds of aromatic carboxylic acid using anion-exchange chromatography. A Dionex IonPac AS9-HC guard column （250mm×2mm） was used with a 9mmol/L sodium carbonate solution containing 50% （v/v） acetonitrile as eluent. A set of retention time data has been obtained using a conductivity detector DS6. Furthermore, geometrical optimization and electrostatic potential calculation of 20 kinds of aromatic carboxylic acid have been performed at the HF/6-31G＊ level of theory. A number of statistically-based parameters derived from molecular surface electrostatic potential have been obtained. Linear relationship between retention time and structural parameters has been established by multiple regression method. The result shows that parameters derived from electrostatic potential Vs ＋, Vs -, П together with the dipole moment μ can be well used to express the quantitative structure-retention time of this kind of aromatic carboxylic acid. Good predictive capability has also been demonstrated. The result has provided a framework which further proves the general applicability of this electrostatic potential parameter set to a great extent,and with which the ion chromatographic adsorption mechanism can be investigated.展开更多
A heavy ion beam probe （HIBP） using a 3-MV tandem accelerator has been installed on large helical device （LHD）. Electrostatic potential in core plasma can be measured under the toroidal magnetic field strength of ...A heavy ion beam probe （HIBP） using a 3-MV tandem accelerator has been installed on large helical device （LHD）. Electrostatic potential in core plasma can be measured under the toroidal magnetic field strength of up to 3 T. By using the HIBP, the transition of potential profiles from electron-root to ion^root is observed in core plasmas during ramp-up of the electron density. Potential fluctuations are also measured electron cyclotron current drive （ECCD）. Two kind of characteristic fluctuations are observed. One is a reversed-shear-induced Alfv^n eigenmode （RSAE）, whose frequency varies during the evolution of the rotational transform profile, and the other is with a constant geodeisc acoustic mode （GAM） frequency.展开更多
The effect of mutation of strongly conserved porelining residues in the chloride channel EcClC on the electrostatic potential and binding free energy of the chloride ion was studied using explicit protein-membrane str...The effect of mutation of strongly conserved porelining residues in the chloride channel EcClC on the electrostatic potential and binding free energy of the chloride ion was studied using explicit protein-membrane structures. Electrostatic potential distribution and binding free energy of the chloride ion at different binding sites in the wild-type and mutated EcClC were calculated with APBS. The potential data reveal that the electrostatic potential around the selectivity filter, especially around the site Sext and Scen becomes more negative as the residue R147 was mutated to C147. The electrostatic binding free energy shows that the binding free energy of the chloride ion at all binding sites becomes more positive as R147 was mutated. It follows that mutation of R147 decreases ion stabilization at binding sites and affects channel＇s gating.展开更多
Polychlorinated dibenzofurans (PCDFs) represent an important kind of serious pollutant. They are highly toxic and persistent in environment. In this paper, geometrical optimizations and subsequent calculations o...Polychlorinated dibenzofurans (PCDFs) represent an important kind of serious pollutant. They are highly toxic and persistent in environment. In this paper, geometrical optimizations and subsequent calculations of electrostatic potentials (ESPs) on molecular surface have been performed for all 135 PCDF congeners at the HF/6-31G* level. The effects of substitution value and variation of substitution position upon the surface ESPs have been discussed. A series of statistic-based structural descriptors derived from the surface ESPs have been calculated. For some PCDF congeners, linear relationships between aryl hydrocarbon receptor (AhR) biding affinity and aryl hydrocarbon hydroxylase (AHH) induction potency as well as theoretical descriptors have been established by multiple linear regression method. It appears that the quantities derived from the surface ESPs, Vs,min, Vs , VS +, σ+ and Nvmin, 2 together with the molecular surface area and the energy gap between HOMO and LUMO can be well used to express the quantitative structure-toxicity relationships of PCDFs.展开更多
Based on the relationship between the quantitative structure and property（QSPR） of organic compounds, the surface electrostatic potential parameters of 29 polychlorinated diphenyl sulfides（PCDPSs） with experimenta...Based on the relationship between the quantitative structure and property（QSPR） of organic compounds, the surface electrostatic potential parameters of 29 polychlorinated diphenyl sulfides（PCDPSs） with experimental values were calculated and extracted, and Multiple Linear Regression（MLR） was used to model the linear relationship between the physicochemical properties（octanol/water partition coefficient, high performance liquid chromatography capacity factor） and molecular structure parameters of PCDPSs. The result shows that the main factors that affect the n-octanol/water partition coefficient and high performance liquid chromatography capacity factor are respectively the number of chlorin atoms substituted on the benzene ring（NCl） and the lowest unoccupied molecular orbital energy（ELUMO）. Secondly, there are also molecular surface electrostatic potentials. This indicates that the molecular surface electrostatic potentials can effectively express the quantitative relationship between the physicochemical properties of PCDPSs and their molecule descriptions. The QSPR models established have strong stability and predictive ability. This also has proved the applicability of molecular surface electrostatic potential parameters in QSPR of PCDPSs.展开更多
We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vec...We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vector potential and electrostatic potential can decisively shift Dirac point in a different way, which may be an efficient way to achieve electron or hole filter. We a/so find that applying modulated parallel and anti-parallel magnetic vector potential to the electrons can efficiently change electronic states between pass and stop states, which can be useful in designing electron or hole switches and lead to large magneto-resistance.展开更多
Artemisinins tested against W-2 strains of malaria falciparum are investigated with molecular electrostatic potential (MEP), in an attempt to identify key features of the compounds that are necessary for their activit...Artemisinins tested against W-2 strains of malaria falciparum are investigated with molecular electrostatic potential (MEP), in an attempt to identify key features of the compounds that are necessary for their activities, as well as to investigate likely interactions with the receptor in a biological process and to use that information to propose new molecules. In order to discover the best geometry involving the ligand-receptor complexes (heme) studied and help in the proposition of the new derivatives, molecular simulations of interactions between the most negative charged region around the peroxide and heme locates (the ones around the Fe2+ ion) were carried out. In addition, PCA (principal components analysis), HCA (hierarchical cluster analysis), SDA (stepwise discriminant analysis), and KNN (K-nearest neighbor) multivariate models were employed to investigate which descriptors are responsible for the classification between the higher and lower antimalarial activity of the compounds, and also this information was used to propose new potentially active molecules. The information accumulated in studies of MEP, molecular docking, and multivariate analysis supported the proposal of new structures with potential antimalarial activities. The multivariate models constructed were applied to the new structures and indicated numbers 19 and 20 as the most prominent for syntheses and biological assays.展开更多
Revealing the charge generation is a crucial step to understand the organic photovoltaics. Recent development in non-fullerene organic solar cells （OSCs） indicates efficient charge separation even with negligible en...Revealing the charge generation is a crucial step to understand the organic photovoltaics. Recent development in non-fullerene organic solar cells （OSCs） indicates efficient charge separation even with negligible energetic offset between the donor and acceptor materials. These new findings trigger a critical question concerning the charge separation mechanism in OSCs, traditionally believed to result from sufficient energetic offset between the polymer donor and fullerene acceptor. We propose a new mechanism, which involves the molecular electrostatic potential, to explain efficient charge separation in non-fullerene OSCs. Together with the new mechanism, we demonstrate a record efficiency of -12% for systems with negligible energetic offset between donor and acceptor materials. Our analysis also rationalizes different requirement of the energetic offset between fullerene-based and non-fullerene OSCs, and paves the way for further design of OSC materials with both high photocurrent and high photovottage at the same time.展开更多
Ionic liquids(ILs),recognized for their negligible vapor pressure,thermal stability,and structural tailorability,offer targeted inhibition of clay expansion.Compared to ILs,polyionic liquids(PILs)possess stronger mech...Ionic liquids(ILs),recognized for their negligible vapor pressure,thermal stability,and structural tailorability,offer targeted inhibition of clay expansion.Compared to ILs,polyionic liquids(PILs)possess stronger mechanical properties and adsorption capabilities,showing even greater potential in inhibiting clay swelling.In this work,we synthesized and characterized an imidazole-based ionic liquid(IL-NH_(2)),a polyionic liquid(PIL-ABHIm),and a PIL/IL combination.Their inhibitory performance was rigorously evaluated under simulated drilling conditions through immersion tests,linear swelling tests,among others.Additionally,the mechanisms underlying their interaction with clay minerals were elucidated through contact angle measurements,Fourier-transform infrared spectroscopy,X-ray diffraction(XRD),Zeta potential analysis,and molecular electrostatic potential(MEP)analysis.This work demonstrates that IL-NH_2inhibits osmotic hydration by altering the interlayer structure of the clay,while PIL-ABHIm reduces surface hydration by forming a hydrophobic barrier on the clay surface.PIL/IL combines both mechanisms,significantly enhancing the stability of clay through the dual mechanisms of cation exchange and hydrophobic barriers.These findings reveal an innovative mechanism by which PIL/IL combination inhibits clay hydration and swelling,providing a scientific foundation for their application in drilling fluids.展开更多
The stacking of multiple defect-rich grain boundaries(GBs)along the long transportation path(~3μm)of charge carriers in printable mesoscopic perovskite solar cells(p-MPSCs)impedes their power conversion efficiency(PC...The stacking of multiple defect-rich grain boundaries(GBs)along the long transportation path(~3μm)of charge carriers in printable mesoscopic perovskite solar cells(p-MPSCs)impedes their power conversion efficiency(PCE).Organic Lewis bases are widely utilized for defect passivation at GBs,but how their passivation efficiency affects energy loss remains unclear.Here we employed triphenylphosphine(TPP)and triphenylphosphine oxide(TPPO)as the model passivators in p-MPSCs.TPPO has a more negatively charged center than TPP,which enables its stronger coordination with one of the most common and detrimental defects at the GBs—undercoordinated lead.When added into the perovskite with the same ratio,TPPO passivates defects more significantly and thus less TPPO remaining inactive compared with TPP.Inactive organic passivators accumulated at the GBs could impose barriers to charge carrier transportation.Indeed,TPPO improves the device performance more significantly with a champion PCE of 20.54%achieved.Besides,the TPPO devices demonstrate excellent stability with 95%of initial PCE remaining after 600 h of maximum power point tracking at(55±5)℃.展开更多
This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7-（salicylidene amino） coumarin（C17H13NC3） using high resolution x-ray diffraction data. The experim...This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7-（salicylidene amino） coumarin（C17H13NC3） using high resolution x-ray diffraction data. The experimental results are compared with those obtained theoretically from calculation type ab initio. The experimental investigation is carried out using the molecular electron charge density distribution based on the multipolar model of Hansen and Coppens. However the theoretical calculations are conducted by using the molecular orbital B3 LYP method and the Hartree-Fock（HF） approximation with the basis set 6-31G（d,p） implemented in the Gaussian program. In addition to the structural analysis,the thermal agitation is also analyzed in terms of rigid blocks to ensure a better precision of the results. Subsequently, the electrostatic atomic and molecular properties such as the net charges, the molecular dipolar moment to highlight the nature of charge transfer existing within the molecule studied are derived. Moreover, the obtained electrostatic potential enables the localization of the electropositive and the electronegative parts of the investigated molecule. The present work reports in detail the obtained electrostatic properties of this biologically important molecule.展开更多
The reactivity and stability of seventeen (17) imidazo [1,2-a]pyridine N-acylhydrazone derivatives were investigated using density functional theory at the B3LYP/6-31+ G (d, p) level. Analysis of the molecular electro...The reactivity and stability of seventeen (17) imidazo [1,2-a]pyridine N-acylhydrazone derivatives were investigated using density functional theory at the B3LYP/6-31+ G (d, p) level. Analysis of the molecular electrostatic potential (MEP) and determination of the dual descriptor revealed that in most cases, the nitrogen atoms of the 6-πelectron conjugation, the oxygen, and the sulfur atom are nucleophilic site. Chemical reactivity of the compounds was assessed through analysis of frontier molecular orbitals (HOMO and LUMO), energy gap (Δℰ), chemical hardness (η), and the softness (S). Consequently, the compound 9e exhibited the lowest reactivity, least electron donating, and the highest stability. This comprehensive study offers valuable insights into the chemical behavior of these derivatives, crucial for further exploration and potential applications.展开更多
Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 hal...Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 halogenated anisoles at the HF/6-31 G^＊ level. A number of statistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time （RRT） and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials （ESPs） together with the molecular volume （Vmc） could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51974056 and 51474047)the Foundation of the Supercomputing Center of Dalian University of Technology,and the Foundation of the Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province),China.
文摘Calculating the inter-layer ion diffusion barrier, a crucial metric for evaluating the rate performance of 2D electrode materials, is time-consuming using the transition state search approach. A novel electrostatic potential distribution image (EPDI) transfer learning method has been proposed to efficiently and accurately predict the lithium diffusion barriers on metal element-doped transition metal dichalcogenide (TMD) surfaces. Through the analysis of the mean electrostatic potential (MEP) around binding sites, a positive correlation between binding energy and MEP in VIB-TMDs was identified. Subsequently, transfer learning techniques were used to develop a DenseNet121-TL model for establishing a more accurate mapping between the binding energy and electrostatic potential distribution. Trained on training sets containing 33% and 50% transition state search calculation results, which save 66% and 50% of the calculation time, respectively, the model achieves accurate predictions of the saddle point binding energy with mean absolute errors (MAEs) of 0.0444 and 0.0287 eV on the testing set. Based on the prediction of saddle point binding energies, we obtained a diffusion minimum energy profile with an MAE of 0.0235 eV. Furthermore, by analyzing the diffusion data, we observed that the diffusion barrier was lowered by 10% on V-doped TiS2 compared to the stoichiometric surface. Our findings are expected to provide new insights for the high-throughput calculation of ion diffusion on 2D materials.
文摘The electrostatic potential energy model of hydrotalcites was based on the theory of crystallography. The anionic potential energy of MgAl-hydrotalcites, with 20 layers and 2107 anions per layer, was calculated, and the anionic stability of the hydrotalcites was investigated. The charge density of the layer and the distance between the adjacent anions varied with the molar ratio of Al^3＋/（Mg^2＋ ＋ Al^3＋）. Anionic potential energy depended on the charge and size of the anions. Calculation results remained consistent with thermal stability and the ion exchange ability reported. This model is able to predict anionic stability of the hydrotalcites.
基金supported by the Analysis and Measurement Planning Project of Zhejiang Province (2007F70053)
文摘Polychlorinated dibenzo-p-dioxins（PCDDs） are a group of important persistent organic pollutants.They are highly toxic and persistent in environment.In the present study,geometrical optimization and electrostatic potential calculations have been performed for 75 PCDD congeners and dibenzo-p-dioxin（DD） at the HF/6-31G＊ level of theory.A number of statistically based parameters have been extracted.Linear relationships between vapor pressures（logpL）,aqueous solubilities（logSw）,n-octanol/water partition coefficients（logKow） of PCDDs and structural descriptors have been established by stepwise linear regression analysis.The result shows that the quantities derived from the surface electrostatic potentials Vmin,Π,and Vs,av＋,together with Vmc（the molecular volume） and ELUMO（the energy of the lowest unoccupied molecular orbital） can be well used to express the quantitative structure-property relationships of PCDDs.Predictive capabilities of the models have also been demonstrated by leave-one-out cross-validation with the cross-validated correlation coefficient（Rcv） above 0.97.Based on these QSPR models,the predicted values have been presented for those PCDD congeners whose experimentally determined physicochemical properties are unavailable.
基金Project supported by the Department of Education of Liaoning Province (2024201057)
文摘Density functional theory （DFT） was applied at the B3LYP/6-31G^＊ level to investigate the relative stability of the five fullerene isomers as well as the anions of C78. Full geometry optimization was carried out and distributions of electrostatic potential were calculated. The results showed that the C78（D3h′） cage was the most stable for C78^q-（ q = 2, 4, 6）, and the potential minimum Vmin（r） inside the sphere of C78（Dzh′） was the biggest one among the five isomers of C78. So C78（Dzh′） were electrons from the scandium atoms that were easier to accept than the other four isomers. On the other hand, MEP maps inside the sphere of C78（Dzh′） had three minima near the three vertexes. Each vertex was formed by the intersection of the three hexagons. Our results allowed a possible explanation for the bonding between the scandium atoms and the fullerene cage.
基金the project of the Ministry of Education,Youth and Sports of the Czech Republic No.MSM 0021627501
文摘The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecular surface electrostatic potentials VS(r).While there is an ambiguous relationship between the VS,max values and FS values,the decrease of FS is connected(more or less) with increase in VS,min values.
基金Supported by the National Natural Science Foundation of China(No.20502022)the Natural Science Foundation of Ningbo (No.2004A610010)
文摘In the present study,geometrical optimization and electrostatic potential calcula-tions have been performed for 22 nitroaromatic compounds at the HF/6-31G level of theory.A number of statistically based parameters have been obtained.Linear relationship between the decomposition enthalpy（taken as a macroscopic property related to explosibility） of nitroaromatic compounds and the structural descriptors have been established by multiple regression method.The result shows that the quantities derived from electrostatic potentialsΣ V sind＋,,Vsind- and Vs,max can be well used to express the quantitative structure-decomposition enthalpy relationship of nitroa-romatic compounds,which proves the general applicability of this parameter set to a great extent.Good predictive capabilities have also been demonstrated.
基金The project was supported by the Department of Education of Qinghai Province (No. 2002-G-102)
文摘Density functional theory （DFT） calculations on three lower energy isomers of C50 were carried out at the B3LYP/6-31G＊ level. Of the three isomers, two have D5h symmetry （a singlet state and a triplet state） and the other one has D3 symmetry. The optimized configurations and electrostatic potential distributions have been obtained. The calculated results show that potential minima Vmin（r） inside the sphere occur at the center of the sphere. The most negative value of the effective Mulliken atomic charge and the largest regions with the most negative MEP outside the sphere are localized in the neighborhood of pentagon-pentagon vertex fusions. They constitute the most probable active sites in chemical reactions. Our results offer a possible explanation for protonation and alkylation of C50 fullerene.
基金Supported by the Project of Analysis and Detection of Zhejiang Province in 2009 (No. 2009F7044)
文摘A method has been developed for separation of 20 kinds of aromatic carboxylic acid using anion-exchange chromatography. A Dionex IonPac AS9-HC guard column （250mm×2mm） was used with a 9mmol/L sodium carbonate solution containing 50% （v/v） acetonitrile as eluent. A set of retention time data has been obtained using a conductivity detector DS6. Furthermore, geometrical optimization and electrostatic potential calculation of 20 kinds of aromatic carboxylic acid have been performed at the HF/6-31G＊ level of theory. A number of statistically-based parameters derived from molecular surface electrostatic potential have been obtained. Linear relationship between retention time and structural parameters has been established by multiple regression method. The result shows that parameters derived from electrostatic potential Vs ＋, Vs -, П together with the dipole moment μ can be well used to express the quantitative structure-retention time of this kind of aromatic carboxylic acid. Good predictive capability has also been demonstrated. The result has provided a framework which further proves the general applicability of this electrostatic potential parameter set to a great extent,and with which the ion chromatographic adsorption mechanism can be investigated.
基金MEXT Japan under Grant-in-Aid for Young Scientists (Nos.16760674,18760640)the JSPS-CAS Core-University program in the field of Plasma and Nuclear FusionNIFS/NINS under the project of Formation of International Network for Scientific Collaborations and NIFS07ULBB505
文摘A heavy ion beam probe （HIBP） using a 3-MV tandem accelerator has been installed on large helical device （LHD）. Electrostatic potential in core plasma can be measured under the toroidal magnetic field strength of up to 3 T. By using the HIBP, the transition of potential profiles from electron-root to ion^root is observed in core plasmas during ramp-up of the electron density. Potential fluctuations are also measured electron cyclotron current drive （ECCD）. Two kind of characteristic fluctuations are observed. One is a reversed-shear-induced Alfv^n eigenmode （RSAE）, whose frequency varies during the evolution of the rotational transform profile, and the other is with a constant geodeisc acoustic mode （GAM） frequency.
基金Supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China(200525)the Science and Technology Program of Wuhan City(20067003111-07)
文摘The effect of mutation of strongly conserved porelining residues in the chloride channel EcClC on the electrostatic potential and binding free energy of the chloride ion was studied using explicit protein-membrane structures. Electrostatic potential distribution and binding free energy of the chloride ion at different binding sites in the wild-type and mutated EcClC were calculated with APBS. The potential data reveal that the electrostatic potential around the selectivity filter, especially around the site Sext and Scen becomes more negative as the residue R147 was mutated to C147. The electrostatic binding free energy shows that the binding free energy of the chloride ion at all binding sites becomes more positive as R147 was mutated. It follows that mutation of R147 decreases ion stabilization at binding sites and affects channel＇s gating.
基金Supported by the Ph.D. Fund of Ningbo (No. 2004A610010)
文摘Polychlorinated dibenzofurans (PCDFs) represent an important kind of serious pollutant. They are highly toxic and persistent in environment. In this paper, geometrical optimizations and subsequent calculations of electrostatic potentials (ESPs) on molecular surface have been performed for all 135 PCDF congeners at the HF/6-31G* level. The effects of substitution value and variation of substitution position upon the surface ESPs have been discussed. A series of statistic-based structural descriptors derived from the surface ESPs have been calculated. For some PCDF congeners, linear relationships between aryl hydrocarbon receptor (AhR) biding affinity and aryl hydrocarbon hydroxylase (AHH) induction potency as well as theoretical descriptors have been established by multiple linear regression method. It appears that the quantities derived from the surface ESPs, Vs,min, Vs , VS +, σ+ and Nvmin, 2 together with the molecular surface area and the energy gap between HOMO and LUMO can be well used to express the quantitative structure-toxicity relationships of PCDFs.
基金Supported by the Natural Science Foundation of Zhejiang Province(LY12B07013)the Education Research Project of Zhejiang Provincial Department(Y201329851)
文摘Based on the relationship between the quantitative structure and property（QSPR） of organic compounds, the surface electrostatic potential parameters of 29 polychlorinated diphenyl sulfides（PCDPSs） with experimental values were calculated and extracted, and Multiple Linear Regression（MLR） was used to model the linear relationship between the physicochemical properties（octanol/water partition coefficient, high performance liquid chromatography capacity factor） and molecular structure parameters of PCDPSs. The result shows that the main factors that affect the n-octanol/water partition coefficient and high performance liquid chromatography capacity factor are respectively the number of chlorin atoms substituted on the benzene ring（NCl） and the lowest unoccupied molecular orbital energy（ELUMO）. Secondly, there are also molecular surface electrostatic potentials. This indicates that the molecular surface electrostatic potentials can effectively express the quantitative relationship between the physicochemical properties of PCDPSs and their molecule descriptions. The QSPR models established have strong stability and predictive ability. This also has proved the applicability of molecular surface electrostatic potential parameters in QSPR of PCDPSs.
基金Supported by the Key Program of the National Natural Science Foundation of China under Grant No. 10832005
文摘We investigated the electronic energy band and transport features of graphene superlattice with periodically modulated magnetic vector potential and electrostatic potential. It is found that both parallel magnetic vector potential and electrostatic potential can decisively shift Dirac point in a different way, which may be an efficient way to achieve electron or hole filter. We a/so find that applying modulated parallel and anti-parallel magnetic vector potential to the electrons can efficiently change electronic states between pass and stop states, which can be useful in designing electron or hole switches and lead to large magneto-resistance.
文摘Artemisinins tested against W-2 strains of malaria falciparum are investigated with molecular electrostatic potential (MEP), in an attempt to identify key features of the compounds that are necessary for their activities, as well as to investigate likely interactions with the receptor in a biological process and to use that information to propose new molecules. In order to discover the best geometry involving the ligand-receptor complexes (heme) studied and help in the proposition of the new derivatives, molecular simulations of interactions between the most negative charged region around the peroxide and heme locates (the ones around the Fe2+ ion) were carried out. In addition, PCA (principal components analysis), HCA (hierarchical cluster analysis), SDA (stepwise discriminant analysis), and KNN (K-nearest neighbor) multivariate models were employed to investigate which descriptors are responsible for the classification between the higher and lower antimalarial activity of the compounds, and also this information was used to propose new potentially active molecules. The information accumulated in studies of MEP, molecular docking, and multivariate analysis supported the proposal of new structures with potential antimalarial activities. The multivariate models constructed were applied to the new structures and indicated numbers 19 and 20 as the most prominent for syntheses and biological assays.
基金J. Hou acknowledge financial support from National Natural Science Foundation of China （91633301, 51673201, 91333204）, the Ministry of Science and Technology of China （2014CB643501） and the Chinese Academy of Sciences （XDB12030200）. F. Gao and D. Qian would like to acknowledge the Swedish Research Council VR （Grant No. 2017-007444 the Swedish Energy Agency Ener- gimyndigheten （2016-010174）, the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University （Faculty Grant No. SFO-Mat-LiU #2009- 00971）.
文摘Revealing the charge generation is a crucial step to understand the organic photovoltaics. Recent development in non-fullerene organic solar cells （OSCs） indicates efficient charge separation even with negligible energetic offset between the donor and acceptor materials. These new findings trigger a critical question concerning the charge separation mechanism in OSCs, traditionally believed to result from sufficient energetic offset between the polymer donor and fullerene acceptor. We propose a new mechanism, which involves the molecular electrostatic potential, to explain efficient charge separation in non-fullerene OSCs. Together with the new mechanism, we demonstrate a record efficiency of -12% for systems with negligible energetic offset between donor and acceptor materials. Our analysis also rationalizes different requirement of the energetic offset between fullerene-based and non-fullerene OSCs, and paves the way for further design of OSC materials with both high photocurrent and high photovottage at the same time.
基金funding from the National Natural Science Foundation of China(Nos.51991361 and 52288101)the Young Scientists Fund of the National Natural Science Foundation(No.52204023)。
文摘Ionic liquids(ILs),recognized for their negligible vapor pressure,thermal stability,and structural tailorability,offer targeted inhibition of clay expansion.Compared to ILs,polyionic liquids(PILs)possess stronger mechanical properties and adsorption capabilities,showing even greater potential in inhibiting clay swelling.In this work,we synthesized and characterized an imidazole-based ionic liquid(IL-NH_(2)),a polyionic liquid(PIL-ABHIm),and a PIL/IL combination.Their inhibitory performance was rigorously evaluated under simulated drilling conditions through immersion tests,linear swelling tests,among others.Additionally,the mechanisms underlying their interaction with clay minerals were elucidated through contact angle measurements,Fourier-transform infrared spectroscopy,X-ray diffraction(XRD),Zeta potential analysis,and molecular electrostatic potential(MEP)analysis.This work demonstrates that IL-NH_2inhibits osmotic hydration by altering the interlayer structure of the clay,while PIL-ABHIm reduces surface hydration by forming a hydrophobic barrier on the clay surface.PIL/IL combines both mechanisms,significantly enhancing the stability of clay through the dual mechanisms of cation exchange and hydrophobic barriers.These findings reveal an innovative mechanism by which PIL/IL combination inhibits clay hydration and swelling,providing a scientific foundation for their application in drilling fluids.
基金financial support from the National Natural Science Foundation of China(Grant numbers 22439001,52172198,51902117)the China Postdoctoral Science Foundation(Grant number BX20240123)the Fundamental Research Funds for the Central Universities(Grant number HUST:2024JYCXJJ043)。
文摘The stacking of multiple defect-rich grain boundaries(GBs)along the long transportation path(~3μm)of charge carriers in printable mesoscopic perovskite solar cells(p-MPSCs)impedes their power conversion efficiency(PCE).Organic Lewis bases are widely utilized for defect passivation at GBs,but how their passivation efficiency affects energy loss remains unclear.Here we employed triphenylphosphine(TPP)and triphenylphosphine oxide(TPPO)as the model passivators in p-MPSCs.TPPO has a more negatively charged center than TPP,which enables its stronger coordination with one of the most common and detrimental defects at the GBs—undercoordinated lead.When added into the perovskite with the same ratio,TPPO passivates defects more significantly and thus less TPPO remaining inactive compared with TPP.Inactive organic passivators accumulated at the GBs could impose barriers to charge carrier transportation.Indeed,TPPO improves the device performance more significantly with a champion PCE of 20.54%achieved.Besides,the TPPO devices demonstrate excellent stability with 95%of initial PCE remaining after 600 h of maximum power point tracking at(55±5)℃.
文摘This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7-（salicylidene amino） coumarin（C17H13NC3） using high resolution x-ray diffraction data. The experimental results are compared with those obtained theoretically from calculation type ab initio. The experimental investigation is carried out using the molecular electron charge density distribution based on the multipolar model of Hansen and Coppens. However the theoretical calculations are conducted by using the molecular orbital B3 LYP method and the Hartree-Fock（HF） approximation with the basis set 6-31G（d,p） implemented in the Gaussian program. In addition to the structural analysis,the thermal agitation is also analyzed in terms of rigid blocks to ensure a better precision of the results. Subsequently, the electrostatic atomic and molecular properties such as the net charges, the molecular dipolar moment to highlight the nature of charge transfer existing within the molecule studied are derived. Moreover, the obtained electrostatic potential enables the localization of the electropositive and the electronegative parts of the investigated molecule. The present work reports in detail the obtained electrostatic properties of this biologically important molecule.
文摘The reactivity and stability of seventeen (17) imidazo [1,2-a]pyridine N-acylhydrazone derivatives were investigated using density functional theory at the B3LYP/6-31+ G (d, p) level. Analysis of the molecular electrostatic potential (MEP) and determination of the dual descriptor revealed that in most cases, the nitrogen atoms of the 6-πelectron conjugation, the oxygen, and the sulfur atom are nucleophilic site. Chemical reactivity of the compounds was assessed through analysis of frontier molecular orbitals (HOMO and LUMO), energy gap (Δℰ), chemical hardness (η), and the softness (S). Consequently, the compound 9e exhibited the lowest reactivity, least electron donating, and the highest stability. This comprehensive study offers valuable insights into the chemical behavior of these derivatives, crucial for further exploration and potential applications.
基金This work was supported by the National Natural Science Foundation of China (No. 20502022) and the Ph.D. Fund of Ningbo ( No. 2004A610010)
文摘Halogenated methyl-phenyl ethers （anisoles） are ubiquitous organic compounds in the environment. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 42 halogenated anisoles at the HF/6-31 G^＊ level. A number of statistically based parameters have been obtained. By multiple regression method, linear relationships between the gas-chromatographic relative retention time （RRT） and structural descriptors have been established for the training set of 32 halogenated anisoles. The result showed that the parameters derived from electrostatic potentials （ESPs） together with the molecular volume （Vmc） could be well used to express the quantitative structure-RRT relationships of halogenated anisoles. The best two-variable regression model gives a correlation coefficient of 0.980 and a standard deviation of 0.07, and the leave-one-out cross-validated correlation coefficient is 0.975. The goodness of the model has been further validated through exploring the predictive power for the testing set of 10 halogenated anisoles.
