Heteroatom doping has emerged as a powerful strategy to optimize the catalytic and adsorption abilities of electrocatalysts by regulating the electronic structure,thereby enabling the development of efficient electroc...Heteroatom doping has emerged as a powerful strategy to optimize the catalytic and adsorption abilities of electrocatalysts by regulating the electronic structure,thereby enabling the development of efficient electrocatalysts for lithium-sulfur(Li-S)batteries.However,the correlation between the properties of doped atoms and adsorptio n-catalytic ability,as well as the interconnection between adsorption strength and catalytic activity,remains underexplored.Herein,we employed halogen atoms(F,Cl,and Br)with different electronegativities to dope nickel phosphide(Ni_(2)P),aiming to modulate the adsorption properties toward lithium polysulfides(LiPSs).We systematically explored the relationship between the electronegativity of the doping atoms and the adsorption strength,followed by exploring the connection between adsorption and catalytic capabilities.Combined experimental and theoretical analyses reveal that doping halogen atoms effectively strengthens d-p orbital hybridization between Ni atoms and S atoms,thereby enhancing LiPSs anchoring and conversion.Specifically,the chemical adsorption capability is enhanced as the electronegativity of the doped atoms increases.Moreover,the catalytic activity presents a volcano-like trend with the enhancement of adsorption performance,wherein the activity initially increases and subsequently diminishes.Therefore,Cl-doped Ni_(2)P with moderate chemisorption ability exhibits optimal redox kinetics in bidirectional sulfur conversion.Consequently,the Li-S batteries with Cl-Ni_(2)P-separators deliver a high-rate capacity of 790 mAh g^(-1)at 5 C and achieve a remarkable areal capacity of 7.36 mAh cm^(-2)under practical conditions(sulfur loading:7.10 mg cm^(-2);electrolyte/sulfur(E/S)ratio:5μL mg^(-1)).This work uncovers the significance of achieving a balance between adsorption and catalytic capabilities,offering insights into designing efficient electrocatalysts for lithium-sulfur batteries.展开更多
We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group e...We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group electronegativity, and atomic charge. The ionization potential of alkanes and mono-substituted alkanes, the chemical shift of 1H NMR, and the gas phase proton affinity of aliphatic amines, alcohols, and ethers were estimated. All the expressions have good correlations. Moreover, the Sanderson method and Bratsch method were modified on the basis of the valence electrons equilibration theory. The modified Sanderson method and modified Bratsch method are more effective than their original methods to estimate these properties.展开更多
The density distributions related to gas electronegativity for c-C4Fs gas, including negative ion, electron number and electron energy densities in the discharge process, are derived theoretically in both plane-to-pla...The density distributions related to gas electronegativity for c-C4Fs gas, including negative ion, electron number and electron energy densities in the discharge process, are derived theoretically in both plane-to-plane and point-to-plane electrode geometries. These calculations have been performed through the Boltzmann equation in the condition of a steady-state Townsend （SST） experiment and a fluid model in the condition of both uniform and non-uniform electric fields. The electronegativity coefficients a = n-/ne of c-C4Fs and SF6 are compared to further describe the electron affinity of c-C4Fs. The result shows that c-C4Fs represents an obvious electron-attachment performance in the discharge process. However, c-C4Fs still has much weaker gas electronegativity than SF6, whose electronegativity coefficient is lower than that of SF6 by at least three orders of magnitude.展开更多
Rare earth catalysts possessing characteristics of cation-anion ion pair show advantages of adjusting electronegativity and steric hindrance of metal active sites, which can control the catalytic performance and stere...Rare earth catalysts possessing characteristics of cation-anion ion pair show advantages of adjusting electronegativity and steric hindrance of metal active sites, which can control the catalytic performance and stereoselectivity better than those of traditional metallocene and Ziegler-Natta catalysts in diene polymerization. In this work, a series of neodymium organic sulfonate complexes,Nd(CF_3SO_3)_3·x H_2O·y L(x, y: the coordination number; L refers to an organic electron donating ligand, such as acetylacetone(acac), isooctyl alcohol(IAOH), tributyl phosphate(TBP), etc.), have been synthesized to form the cationic active species in the presence of alkylaluminum such as Al(i-Bu)_3, AlEt_3, and Al(i-Bu)_2H, which display high activities and distinguishing cis-1,4 selectivities(up to99.9%) for the polymerization of butadiene. The microstructures, yield, molecular weight, and molecular weight distribution of the resulting polymer are well controlled by adjusting electronegativity/steric hindrance of the complexes. In addition, the kinetics, active species, and the possible process of polymerization are also discussed in this article.展开更多
Excited-state intramolecular proton transfer(ESIPT)is favored by researchers because of its unique optical properties.However,there are relatively few systematic studies on the effects of changing the electronegativit...Excited-state intramolecular proton transfer(ESIPT)is favored by researchers because of its unique optical properties.However,there are relatively few systematic studies on the effects of changing the electronegativity of atoms on the ESIPT process and photophysical properties.Therefore,we selected a series of benzoxazole isothiocyanate fluorescent dyes(2-HOB,2-HSB,and 2-HSe B)by theoretical methods,and systematically studied the ESIPT process and photophysical properties by changing the electronegativity of chalcogen atoms.The calculated bond angle,bond length,energy gap,and infrared spectrum analysis show that the order of the strength of intramolecular hydrogen bonding of the three molecules is 2-HOB<2-HSB<2-HSe B.Correspondingly,the magnitude of the energy barrier of the potential energy curve is 2-HOB>2-HSB>2-HSe B.In addition,the calculated electronic spectrum shows that as the atomic electronegativity decreases,the emission spectrum has a redshift.Therefore,this work will offer certain theoretical guidance for the synthesis and application of new dyes based on ESIPT properties.展开更多
One of the novel phenomena of Ar/O_(2)inductively coupled plasma,the delta negative ions density profile is discovered by the fluid simulation at very low electronegativity.The anions delta is found to be formed by th...One of the novel phenomena of Ar/O_(2)inductively coupled plasma,the delta negative ions density profile is discovered by the fluid simulation at very low electronegativity.The anions delta is found to be formed by the collaboration of successive plasma transport phases.The plasma transport itself is affected by the delta,exhibiting many new phenomena.A new type of Helmholtz equation is devised to mathematically explain the delta forming mechanism.For revealing the physics behind,a revised spring oscillator dynamic equation has been constructed according to the Helmholtz equation,in a relevant paper[Zhao S X and Li J Z(2021)Chin.Phys.B 30055202].The investigation about the anions delta distribution is a nice prediction of new phenomenon in low temperature electronegative plasmas,waiting for the validation of related experiments.展开更多
This paper presents the evolution of the electronegativity with the applied power during the E to H mode transition in a radio frequency(rf)inductively coupled plasma(ICP)in a mixture of Ar and O2.The densities of the...This paper presents the evolution of the electronegativity with the applied power during the E to H mode transition in a radio frequency(rf)inductively coupled plasma(ICP)in a mixture of Ar and O2.The densities of the negative ion and the electron,as well as their ratio,i.e.,the electronegativity,are measured as a function of the applied power by laser photo-detachment combined with a microwave resonance probe,under different pressures and O2 contents.Meanwhile,the optical emission intensities at Ar 750.4 nm and O 844.6 nm are monitored via a spectrograph.It was found that by increasing the applied power,the electron density and the optical emission intensity show a similar trench,i.e.,they increase abruptly at a threshold power,suggesting that the E to H mode transition occurs.With the increase of the pressure,the negative ion density presents opposite trends in the E-mode and the H-mode,which is related to the difference of the electron density and energy for the two modes.The emission intensities of Ar 750.4 nm and O 844.6 nm monotonously decrease with increasing the pressure or the O2 content,indicating that the density of high-energy electrons,which can excite atoms,is monotonically decreased.This leads to an increase of the negative ion density in the H-mode with increasing the pressure.Besides,as the applied power is increased,the electronegativity shows an abrupt drop during the E-to H-mode transition.展开更多
Polychlorinated dibenzothiophenes（PCDTs） are classified as persistent organic pollutants in the environment,so the analysis of PCDTs by their gas chromatographic behaviors is of great significance.Quantitative struc...Polychlorinated dibenzothiophenes（PCDTs） are classified as persistent organic pollutants in the environment,so the analysis of PCDTs by their gas chromatographic behaviors is of great significance.Quantitative structure-retention relationship（QSRR） analysis is a useful technique capable of relating chromatographic retention time to the molecular structure.In this paper,a QSRR study of 37 PCDTs was carried out by using molecular electronegativity distance vector（MEDV） descriptors and multiple linear regression（MLR） and partial least-squares regression（PLS） methods.The correlation coefficient R of established MLR,PLS models,leave-one-out（LOO） cross-validation（CV）,Q2ext were 0.9951,0.9942,0.9839（MLR） and 0.9925,0.9915,0.9833（PLS）,respectively.Results showed that the model exhibited excellent estimate capability for internal sample set and good predictive capability for external sample set.By using MEDV descriptors,the QSRR model can provide a simple and rapid way to predict the gas-chromatographic retention indices of polychlorinated dibenzothiophenes in conditions of lacking standard samples or poor experimental conditions.展开更多
The electronegativity and the hardness are two popular and useful theoretical descriptors of chemistry and physics successfully used by both physicists and chemists in correlating chemico-physical properties of atoms,...The electronegativity and the hardness are two popular and useful theoretical descriptors of chemistry and physics successfully used by both physicists and chemists in correlating chemico-physical properties of atoms, molecules and condensed matter physics. We have tried to explore the fundamental nature of the hardness and electronegativity of atoms and have observed that their fundamental nature is basically lying in electrostatics and manifest as the electron attracting power emanating from the nucleus of the atom. We have tried to correlate the periodic nature of variation of the electronegativity and the hardness to the electron attracting power of the nucleus from which they are originated and developed. We have developed the formulae for evaluating both electronegativity and hardness and found that they have the direct correlation with the effective nuclear charge of the atoms and hence their periodicity.展开更多
MRGPRX2 antagonists possess the potential for the treatment of allergic rhinitis,atopic dermatitis,and chronic urticaria.Previously,we identified a class of diaryl urea(DPU)MRGPRX2 antagonists with sub-micromolar IC50...MRGPRX2 antagonists possess the potential for the treatment of allergic rhinitis,atopic dermatitis,and chronic urticaria.Previously,we identified a class of diaryl urea(DPU)MRGPRX2 antagonists with sub-micromolar IC50 values in vitro.However,the structureeactivity relationship remains unclear.Herein,we adopted a“relative symmetry with electronegativity of different key-groups”strategy for further modification of DPUs to achieve a promising MRGPRX2 antagonist with higher activity and safety.Electrostatic potential energy analysis and biological evaluation revealed that B-1023 and B-5023,that possess relatively symmetric electron-withdrawing substituents,remarkable inhibited mast cell degranulation at a sub-micromolar IC50 in vitro and alleviated anaphylactic symptoms.Furthermore,B-1023,mitigated antigen-induced pulmonary inflammation(AIPI)in mice and competitively bonded to MRGPRX2.In summary,the“relative symmetry with electronegativity of different keygroups”strategy provided a drug design pattern for MRGPRX2 antagonists and identified promising antiallergic precursors for AIPI treatment.展开更多
This study investigated the effect of surface electronegativity and calcium release from human enamel on the adsorption and lubrication of salivary proteins from the perspective of interfacial water using three model ...This study investigated the effect of surface electronegativity and calcium release from human enamel on the adsorption and lubrication of salivary proteins from the perspective of interfacial water using three model substrates:calcium-releasing electronegative hydroxyapatite(which represents enamel),calciumfree electronegative silica,and calcium-free electropositive zirconia.The interfacial water layer was probed using attenuated total reflection-infrared(ATR-IR)spectroscopy,and the adsorption and lubrication of salivary proteins were examined using atomic force microscopy(AFM),quartz crystal microbalance with dissipation(QCM-D),and nanoindentation/scratch techniques.The strong affinity of electropositive substrates for water contributed to a thick interfacial water layer,which served as a physical barrier to weaken electrostatic attraction to salivary proteins.Thus,the proteins randomly adsorbed,forming a pellicle without a multilayered structure and good lubricity.The interfacial water layer on electronegative substrates tends to be thin.Driven by strong electrostatic interactions,salivary proteins are adsorbed through self-assembly to form a pellicle with a two-layered structure.While the hydrated calcium ions caused by substrate calcium release thickened the interfacial water layer,they served as a bridge to connect proteins.Consequently,a two-layered pellicle,both stiff and viscoelastic,formed to provide excellent lubricating action.In summary,the surface electronegativity and calcium release of enamel benefit the adsorption and lubrication of salivary proteins by regulating interfacial water.展开更多
Developing dielectric capacitors with both excellent recoverable energy storage density(Wrec)and high dielectric breakdown strength(DBS)are highly desired for pulsed power electronic systems.Although glass ceramics ar...Developing dielectric capacitors with both excellent recoverable energy storage density(Wrec)and high dielectric breakdown strength(DBS)are highly desired for pulsed power electronic systems.Although glass ceramics are known to potentially possess simultaneously a high DBS and a relatively high dielectric constant(εr),it is still a long-standing challenge to obtain high energy storage performance in glass ceramics.In this work,based on the consideration of electronegativity and its effects on the degree of polymerization,SnO_(2)addictive was introduced to reconstitute the parent glass network structure and thereby an ultra-high DBS value of 2809 kV/cm was achieved in the SnO_(2)-doped parent glass.After crystallization of the SnO_(2)-doped parent glass,an ultrahigh Wrec of 10.13 J/cm^(3)with an efficiency(η)of 85.5%and a superb discharge energy storage density(Wd)of 9.09 J/cm^(3)at 1500 kV/cm were obtained in the BaTiO_(3)-based glass ceramic.Meanwhile,this BaTiO_(3)-based glass ceramic displays a good thermal stability over a wide temperature range of 30-120℃,with the Wrec only decreasing by 3.0%and Wd dropping from 4.40 J/cm^(3)to 3.53 J/cm^(3)at 800 kV/cm.Furthermore,it also exhibits high optical transmittance(about 60%)in the visible light spectrum.These features indicate that the BaTiO_(3)-based glass ceramic studied in this work has a great potential not only for high-pulsed power applications but also for optical applications,making it a truly multifunctional material.展开更多
On the basis of a more precise expression of the atomic effective electronegativity deduced from the density functional theory and electronegativity equalization principle, a new scheme for calculating the group elect...On the basis of a more precise expression of the atomic effective electronegativity deduced from the density functional theory and electronegativity equalization principle, a new scheme for calculating the group electronegativity and the atomic charges in a group is proposed and programed, and various parameters of electronegativity and hardness are given for some common atoms. Through calculation, analysis and comparison of more than one hundred groups, it is shown that the results from this scheme are reasonable and may be extended.展开更多
On the basis of electronegativity expressed in density functional theory and electronegativity equalization principle, a new scheme for calculating the atomic charges in a molecule has been proposed and designed, whic...On the basis of electronegativity expressed in density functional theory and electronegativity equalization principle, a new scheme for calculating the atomic charges in a molecule has been proposed and designed, which gives a new scale of the atomic electronegativity and hardness in a certain molecular environment and takes the harmonic mean electronegativity as a reference value of the molecular electronegativity so that the multiple-regression and nonuniform parameters in the original method are avoided. This approach can be easily and widely applied to the calculation of atomic charges for a big molecule and quite good results of atomic charges in some illustrated molecules are obtained as compared with those from the ab initio STO-3G SCF calculations.展开更多
Based on the density functional theory and partitioning the molecular electron density ρ(r) into atomic electronic densities and bond electronic densities,the expressions of the total molecular energy and the "e...Based on the density functional theory and partitioning the molecular electron density ρ(r) into atomic electronic densities and bond electronic densities,the expressions of the total molecular energy and the "effective electronegativity" of an atom or a bond in a molecule are obtained.The atom bond electronegativity equalization model is then proposed for the direct calculation of the total molecular energy and the charge distribution of large molecules.Practical calculations show that the atom bond electronegativity equalization model can reproduce the corresponding ab initio values of the total molecular energies and charge distributions for a series of large molecules with a very satisfactory accuracy.展开更多
Based on the density functional theory and the atom-bond electronegativity equalization model (ABEEM), a method is proposed to construct the softness matrix and to obtain the electron population normal modes (PNMs) fo...Based on the density functional theory and the atom-bond electronegativity equalization model (ABEEM), a method is proposed to construct the softness matrix and to obtain the electron population normal modes (PNMs) for a closed system. Using this method the information about the bond charge polarization in a molecule can be obtained easily. The test calculation shows that the PNM obtained by this method includes all the modes about the bond charge polarization explicitly. And the bond charge polarization mode characterized by the biggest eigenvalue, which is the softest one of all modes related with chemical bonds, can describe the charge polarization process in a molecule as exquisitely as the corresponding ab initio method.展开更多
A method which combines electronegativity difference,CALculation of PHAse Diagrams(CALPHAD) and machine learning has been proposed to efficiently screen the high yield strength regions in Co-Cr-Fe-Ni-Mo multi-componen...A method which combines electronegativity difference,CALculation of PHAse Diagrams(CALPHAD) and machine learning has been proposed to efficiently screen the high yield strength regions in Co-Cr-Fe-Ni-Mo multi-component phase diagram.First,the single-phase region at a certain annealing temperature is obtained by combining CALPHAD method and machine learning,to avoid the formation of brittle phases.Then high yield strength points in the single-phase region are selected by electronegativity difference.The yield strength and plastic deformation behavior of the designed Co_(14)Cr_(30)Ni_(50)Mo_(6)alloy are measured to evaluate the proposed method.The validation experiments indicate this method is effective to predict high yield strength points in the whole compositional space.Meanwhile,the interactions between the high density of shear bands and dislocations contribute to the high ductility and good work hardening ability of Co_(14)Cr_(30)Ni_(50)Mo_(6)alloy.The method is helpful and instructive to property-oriented compositional design for multi-principal element alloys.展开更多
Only from the primary structures of peptides, a new set of descriptors called the molecular electro-negativity edge-distance vector (VMED) was proposed and applied to describing and characterizing the molecular struct...Only from the primary structures of peptides, a new set of descriptors called the molecular electro-negativity edge-distance vector (VMED) was proposed and applied to describing and characterizing the molecular structures of oligopeptides and polypeptides, based on the electronegativity of each atom or electronic charge index (ECI) of atomic clusters and the bonding distance between atom-pairs. Here, the molecular structures of antigenic polypeptides were well expressed in order to propose the auto-mated technique for the computerized identification of helper T lymphocyte (Th) epitopes. Furthermore, a modified MED vector was proposed from the primary structures of polypeptides, based on the ECI and the relative bonding distance of the fundamental skeleton groups. The side-chains of each amino acid were here treated as a pseudo-atom. The developed VMED was easy to calculate and able to work. Some quantitative model was established for 28 immunogenic or antigenic polypeptides (AGPP) with 14 (1― 14) Ad and 14 other restricted activities assigned as "1"(+) and "0"(-), respectively. The latter comprised 6 Ab(15-20), 3 Ak(21-23), 2 Ek(24-26), 2 H-2k(27 and 28) restricted sequences. Good results were obtained with 90% correct classification (only 2 wrong ones for 20 training samples) and 100% correct prediction(none wrong for 8 testing samples); while con-trastively 100% correct classification (none wrong for 20 training samples) and 88% correct classification (1 wrong for 8 testing samples). Both stochastic samplings and cross valida-tions were performed to demonstrate good performance. The described method may also be suitable for estimation and prediction of classes I and II for major histocompatibility an-tigen (MHC) epitope of human. It will be useful in immune identification and recognition of pro-teins and genes and in the design and devel-opment of subunit vaccines. Several quantitative structure activity relationship (QSAR) models were developed for various oligopeptides and polypeptides including 58 dipeptides and 31 pentapeptides with angiotensin converting enzyme (ACE) inhibition by multiple linear regression (MLR) method. In order to explain the ability to characterize molecular structure of polypeptides, a molecular modeling investigation on QSAR was performed for functional prediction of polypeptide sequences with anti-genic activity and heptapeptide sequences with tachykinin activity through quantitative se-quence-activity models (QSAMs) by the molecular electronegativity edge-distance vector (VMED). The results showed that VMED exhibited both excellent structural selectivity and good activity prediction. Moreover, the results showed that VMED behaved quite well for both QSAR and QSAM of poly-and oli-gopeptides, which exhibited both good estimation ability and prediction power, equal to or better than those reported in the previous references. Finally, a preliminary conclusion was drwan: both classical and modified MED vectors were very useful structural descriptors. Some suggestions were proposed for further studies on QSAR/QSAM of proteins in various fields.展开更多
基金supported by the Beijing Institute of Technology Research Fund Program for Young Scholars and 21C Innovation Laboratory Contemporary Amperex Technology Co.,Limited,Ninde,352100,China(21C-OP-202314)。
文摘Heteroatom doping has emerged as a powerful strategy to optimize the catalytic and adsorption abilities of electrocatalysts by regulating the electronic structure,thereby enabling the development of efficient electrocatalysts for lithium-sulfur(Li-S)batteries.However,the correlation between the properties of doped atoms and adsorptio n-catalytic ability,as well as the interconnection between adsorption strength and catalytic activity,remains underexplored.Herein,we employed halogen atoms(F,Cl,and Br)with different electronegativities to dope nickel phosphide(Ni_(2)P),aiming to modulate the adsorption properties toward lithium polysulfides(LiPSs).We systematically explored the relationship between the electronegativity of the doping atoms and the adsorption strength,followed by exploring the connection between adsorption and catalytic capabilities.Combined experimental and theoretical analyses reveal that doping halogen atoms effectively strengthens d-p orbital hybridization between Ni atoms and S atoms,thereby enhancing LiPSs anchoring and conversion.Specifically,the chemical adsorption capability is enhanced as the electronegativity of the doped atoms increases.Moreover,the catalytic activity presents a volcano-like trend with the enhancement of adsorption performance,wherein the activity initially increases and subsequently diminishes.Therefore,Cl-doped Ni_(2)P with moderate chemisorption ability exhibits optimal redox kinetics in bidirectional sulfur conversion.Consequently,the Li-S batteries with Cl-Ni_(2)P-separators deliver a high-rate capacity of 790 mAh g^(-1)at 5 C and achieve a remarkable areal capacity of 7.36 mAh cm^(-2)under practical conditions(sulfur loading:7.10 mg cm^(-2);electrolyte/sulfur(E/S)ratio:5μL mg^(-1)).This work uncovers the significance of achieving a balance between adsorption and catalytic capabilities,offering insights into designing efficient electrocatalysts for lithium-sulfur batteries.
文摘We take the contribution of all valence electrons into consideration and propose a new valence electrons equilibration method to calculate the equalized electronegativity including molecular electronegativity, group electronegativity, and atomic charge. The ionization potential of alkanes and mono-substituted alkanes, the chemical shift of 1H NMR, and the gas phase proton affinity of aliphatic amines, alcohols, and ethers were estimated. All the expressions have good correlations. Moreover, the Sanderson method and Bratsch method were modified on the basis of the valence electrons equilibration theory. The modified Sanderson method and modified Bratsch method are more effective than their original methods to estimate these properties.
基金supported by National Natural Science Foundation of China (No.51337006)
文摘The density distributions related to gas electronegativity for c-C4Fs gas, including negative ion, electron number and electron energy densities in the discharge process, are derived theoretically in both plane-to-plane and point-to-plane electrode geometries. These calculations have been performed through the Boltzmann equation in the condition of a steady-state Townsend （SST） experiment and a fluid model in the condition of both uniform and non-uniform electric fields. The electronegativity coefficients a = n-/ne of c-C4Fs and SF6 are compared to further describe the electron affinity of c-C4Fs. The result shows that c-C4Fs represents an obvious electron-attachment performance in the discharge process. However, c-C4Fs still has much weaker gas electronegativity than SF6, whose electronegativity coefficient is lower than that of SF6 by at least three orders of magnitude.
基金the National Natural Science Foundation of China(Nos.51473156 and 51873203)Key Projects of Jilin Province Science and Technology Development Plan(Nos.2018020108GX and 20160204028GX)
文摘Rare earth catalysts possessing characteristics of cation-anion ion pair show advantages of adjusting electronegativity and steric hindrance of metal active sites, which can control the catalytic performance and stereoselectivity better than those of traditional metallocene and Ziegler-Natta catalysts in diene polymerization. In this work, a series of neodymium organic sulfonate complexes,Nd(CF_3SO_3)_3·x H_2O·y L(x, y: the coordination number; L refers to an organic electron donating ligand, such as acetylacetone(acac), isooctyl alcohol(IAOH), tributyl phosphate(TBP), etc.), have been synthesized to form the cationic active species in the presence of alkylaluminum such as Al(i-Bu)_3, AlEt_3, and Al(i-Bu)_2H, which display high activities and distinguishing cis-1,4 selectivities(up to99.9%) for the polymerization of butadiene. The microstructures, yield, molecular weight, and molecular weight distribution of the resulting polymer are well controlled by adjusting electronegativity/steric hindrance of the complexes. In addition, the kinetics, active species, and the possible process of polymerization are also discussed in this article.
基金supported by the National Natural Science Foundation of China(No.21773238)the Fundamental Research Funds of Shandong University(2019GN025)。
文摘Excited-state intramolecular proton transfer(ESIPT)is favored by researchers because of its unique optical properties.However,there are relatively few systematic studies on the effects of changing the electronegativity of atoms on the ESIPT process and photophysical properties.Therefore,we selected a series of benzoxazole isothiocyanate fluorescent dyes(2-HOB,2-HSB,and 2-HSe B)by theoretical methods,and systematically studied the ESIPT process and photophysical properties by changing the electronegativity of chalcogen atoms.The calculated bond angle,bond length,energy gap,and infrared spectrum analysis show that the order of the strength of intramolecular hydrogen bonding of the three molecules is 2-HOB<2-HSB<2-HSe B.Correspondingly,the magnitude of the energy barrier of the potential energy curve is 2-HOB>2-HSB>2-HSe B.In addition,the calculated electronic spectrum shows that as the atomic electronegativity decreases,the emission spectrum has a redshift.Therefore,this work will offer certain theoretical guidance for the synthesis and application of new dyes based on ESIPT properties.
基金supported by the foundation of project DUT19LK59
文摘One of the novel phenomena of Ar/O_(2)inductively coupled plasma,the delta negative ions density profile is discovered by the fluid simulation at very low electronegativity.The anions delta is found to be formed by the collaboration of successive plasma transport phases.The plasma transport itself is affected by the delta,exhibiting many new phenomena.A new type of Helmholtz equation is devised to mathematically explain the delta forming mechanism.For revealing the physics behind,a revised spring oscillator dynamic equation has been constructed according to the Helmholtz equation,in a relevant paper[Zhao S X and Li J Z(2021)Chin.Phys.B 30055202].The investigation about the anions delta distribution is a nice prediction of new phenomenon in low temperature electronegative plasmas,waiting for the validation of related experiments.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11675039,11875101,and 11935005)the Fundamental Research Founds for the Central Universities,China(Grant Nos.DUT18TD06 and DUT20LAB201).
文摘This paper presents the evolution of the electronegativity with the applied power during the E to H mode transition in a radio frequency(rf)inductively coupled plasma(ICP)in a mixture of Ar and O2.The densities of the negative ion and the electron,as well as their ratio,i.e.,the electronegativity,are measured as a function of the applied power by laser photo-detachment combined with a microwave resonance probe,under different pressures and O2 contents.Meanwhile,the optical emission intensities at Ar 750.4 nm and O 844.6 nm are monitored via a spectrograph.It was found that by increasing the applied power,the electron density and the optical emission intensity show a similar trench,i.e.,they increase abruptly at a threshold power,suggesting that the E to H mode transition occurs.With the increase of the pressure,the negative ion density presents opposite trends in the E-mode and the H-mode,which is related to the difference of the electron density and energy for the two modes.The emission intensities of Ar 750.4 nm and O 844.6 nm monotonously decrease with increasing the pressure or the O2 content,indicating that the density of high-energy electrons,which can excite atoms,is monotonically decreased.This leads to an increase of the negative ion density in the H-mode with increasing the pressure.Besides,as the applied power is increased,the electronegativity shows an abrupt drop during the E-to H-mode transition.
基金supported by the Foundation of Returned Scholars (Main Program) of Shanxi Province (200902)
文摘Polychlorinated dibenzothiophenes（PCDTs） are classified as persistent organic pollutants in the environment,so the analysis of PCDTs by their gas chromatographic behaviors is of great significance.Quantitative structure-retention relationship（QSRR） analysis is a useful technique capable of relating chromatographic retention time to the molecular structure.In this paper,a QSRR study of 37 PCDTs was carried out by using molecular electronegativity distance vector（MEDV） descriptors and multiple linear regression（MLR） and partial least-squares regression（PLS） methods.The correlation coefficient R of established MLR,PLS models,leave-one-out（LOO） cross-validation（CV）,Q2ext were 0.9951,0.9942,0.9839（MLR） and 0.9925,0.9915,0.9833（PLS）,respectively.Results showed that the model exhibited excellent estimate capability for internal sample set and good predictive capability for external sample set.By using MEDV descriptors,the QSRR model can provide a simple and rapid way to predict the gas-chromatographic retention indices of polychlorinated dibenzothiophenes in conditions of lacking standard samples or poor experimental conditions.
文摘The electronegativity and the hardness are two popular and useful theoretical descriptors of chemistry and physics successfully used by both physicists and chemists in correlating chemico-physical properties of atoms, molecules and condensed matter physics. We have tried to explore the fundamental nature of the hardness and electronegativity of atoms and have observed that their fundamental nature is basically lying in electrostatics and manifest as the electron attracting power emanating from the nucleus of the atom. We have tried to correlate the periodic nature of variation of the electronegativity and the hardness to the electron attracting power of the nucleus from which they are originated and developed. We have developed the formulae for evaluating both electronegativity and hardness and found that they have the direct correlation with the effective nuclear charge of the atoms and hence their periodicity.
基金supported by the National Natural Science Foundation of China(grant Nos.81930096 and 82373830).
文摘MRGPRX2 antagonists possess the potential for the treatment of allergic rhinitis,atopic dermatitis,and chronic urticaria.Previously,we identified a class of diaryl urea(DPU)MRGPRX2 antagonists with sub-micromolar IC50 values in vitro.However,the structureeactivity relationship remains unclear.Herein,we adopted a“relative symmetry with electronegativity of different key-groups”strategy for further modification of DPUs to achieve a promising MRGPRX2 antagonist with higher activity and safety.Electrostatic potential energy analysis and biological evaluation revealed that B-1023 and B-5023,that possess relatively symmetric electron-withdrawing substituents,remarkable inhibited mast cell degranulation at a sub-micromolar IC50 in vitro and alleviated anaphylactic symptoms.Furthermore,B-1023,mitigated antigen-induced pulmonary inflammation(AIPI)in mice and competitively bonded to MRGPRX2.In summary,the“relative symmetry with electronegativity of different keygroups”strategy provided a drug design pattern for MRGPRX2 antagonists and identified promising antiallergic precursors for AIPI treatment.
基金supported by the National Natural Science Foundation of China(Nos.52305217,52075459,and 51675449).
文摘This study investigated the effect of surface electronegativity and calcium release from human enamel on the adsorption and lubrication of salivary proteins from the perspective of interfacial water using three model substrates:calcium-releasing electronegative hydroxyapatite(which represents enamel),calciumfree electronegative silica,and calcium-free electropositive zirconia.The interfacial water layer was probed using attenuated total reflection-infrared(ATR-IR)spectroscopy,and the adsorption and lubrication of salivary proteins were examined using atomic force microscopy(AFM),quartz crystal microbalance with dissipation(QCM-D),and nanoindentation/scratch techniques.The strong affinity of electropositive substrates for water contributed to a thick interfacial water layer,which served as a physical barrier to weaken electrostatic attraction to salivary proteins.Thus,the proteins randomly adsorbed,forming a pellicle without a multilayered structure and good lubricity.The interfacial water layer on electronegative substrates tends to be thin.Driven by strong electrostatic interactions,salivary proteins are adsorbed through self-assembly to form a pellicle with a two-layered structure.While the hydrated calcium ions caused by substrate calcium release thickened the interfacial water layer,they served as a bridge to connect proteins.Consequently,a two-layered pellicle,both stiff and viscoelastic,formed to provide excellent lubricating action.In summary,the surface electronegativity and calcium release of enamel benefit the adsorption and lubrication of salivary proteins by regulating interfacial water.
基金supported by National Natural Science Foundation of China(52162001)Guangxi Natural Science Foundation(2021GXNSFAA220020)+4 种基金Guangxi Science&Technology Planning Project(AD21220138)the Innovation Project of Optics Valley Laboratory(Grant No.OVL2023ZD001)the Dongguan Key Research&Development Program,China(No.20221200300032)the Natural Sciences&Engineering Research Council of Canada(NSERC,Discovery Grant No.RGPIN-2023-04416)the Innovation Project of GUET Graduate Education(2023YCXS147).
文摘Developing dielectric capacitors with both excellent recoverable energy storage density(Wrec)and high dielectric breakdown strength(DBS)are highly desired for pulsed power electronic systems.Although glass ceramics are known to potentially possess simultaneously a high DBS and a relatively high dielectric constant(εr),it is still a long-standing challenge to obtain high energy storage performance in glass ceramics.In this work,based on the consideration of electronegativity and its effects on the degree of polymerization,SnO_(2)addictive was introduced to reconstitute the parent glass network structure and thereby an ultra-high DBS value of 2809 kV/cm was achieved in the SnO_(2)-doped parent glass.After crystallization of the SnO_(2)-doped parent glass,an ultrahigh Wrec of 10.13 J/cm^(3)with an efficiency(η)of 85.5%and a superb discharge energy storage density(Wd)of 9.09 J/cm^(3)at 1500 kV/cm were obtained in the BaTiO_(3)-based glass ceramic.Meanwhile,this BaTiO_(3)-based glass ceramic displays a good thermal stability over a wide temperature range of 30-120℃,with the Wrec only decreasing by 3.0%and Wd dropping from 4.40 J/cm^(3)to 3.53 J/cm^(3)at 800 kV/cm.Furthermore,it also exhibits high optical transmittance(about 60%)in the visible light spectrum.These features indicate that the BaTiO_(3)-based glass ceramic studied in this work has a great potential not only for high-pulsed power applications but also for optical applications,making it a truly multifunctional material.
基金Project supported by the National Natural Science Foundation of Chinathe Foundation of State Education Commission of China
文摘On the basis of a more precise expression of the atomic effective electronegativity deduced from the density functional theory and electronegativity equalization principle, a new scheme for calculating the group electronegativity and the atomic charges in a group is proposed and programed, and various parameters of electronegativity and hardness are given for some common atoms. Through calculation, analysis and comparison of more than one hundred groups, it is shown that the results from this scheme are reasonable and may be extended.
基金Project supported by the National Natural Science Foundation of China.
文摘On the basis of electronegativity expressed in density functional theory and electronegativity equalization principle, a new scheme for calculating the atomic charges in a molecule has been proposed and designed, which gives a new scale of the atomic electronegativity and hardness in a certain molecular environment and takes the harmonic mean electronegativity as a reference value of the molecular electronegativity so that the multiple-regression and nonuniform parameters in the original method are avoided. This approach can be easily and widely applied to the calculation of atomic charges for a big molecule and quite good results of atomic charges in some illustrated molecules are obtained as compared with those from the ab initio STO-3G SCF calculations.
文摘Based on the density functional theory and partitioning the molecular electron density ρ(r) into atomic electronic densities and bond electronic densities,the expressions of the total molecular energy and the "effective electronegativity" of an atom or a bond in a molecule are obtained.The atom bond electronegativity equalization model is then proposed for the direct calculation of the total molecular energy and the charge distribution of large molecules.Practical calculations show that the atom bond electronegativity equalization model can reproduce the corresponding ab initio values of the total molecular energies and charge distributions for a series of large molecules with a very satisfactory accuracy.
基金This project is supported by the National Natural Science Foundation of China(Grant No.29873021).
文摘Based on the density functional theory and the atom-bond electronegativity equalization model (ABEEM), a method is proposed to construct the softness matrix and to obtain the electron population normal modes (PNMs) for a closed system. Using this method the information about the bond charge polarization in a molecule can be obtained easily. The test calculation shows that the PNM obtained by this method includes all the modes about the bond charge polarization explicitly. And the bond charge polarization mode characterized by the biggest eigenvalue, which is the softest one of all modes related with chemical bonds, can describe the charge polarization process in a molecule as exquisitely as the corresponding ab initio method.
基金supported by the National Natural Science Foundation of China (Grant No.51701061)the Natural Science Foundation of Hebei Province (Grant Nos.E2019202059, E2020202124)the foundation strengthening program (Grant No. 2019-JCJQ-142)。
文摘A method which combines electronegativity difference,CALculation of PHAse Diagrams(CALPHAD) and machine learning has been proposed to efficiently screen the high yield strength regions in Co-Cr-Fe-Ni-Mo multi-component phase diagram.First,the single-phase region at a certain annealing temperature is obtained by combining CALPHAD method and machine learning,to avoid the formation of brittle phases.Then high yield strength points in the single-phase region are selected by electronegativity difference.The yield strength and plastic deformation behavior of the designed Co_(14)Cr_(30)Ni_(50)Mo_(6)alloy are measured to evaluate the proposed method.The validation experiments indicate this method is effective to predict high yield strength points in the whole compositional space.Meanwhile,the interactions between the high density of shear bands and dislocations contribute to the high ductility and good work hardening ability of Co_(14)Cr_(30)Ni_(50)Mo_(6)alloy.The method is helpful and instructive to property-oriented compositional design for multi-principal element alloys.
基金Supported by National High-Tech R&D Programme of China (863) (Grant No. 2006AA02Z312)National 111 Programme Introducing Talents of Discipline to Universities (Grant No. 0507111106)+6 种基金National Chunhui Project (Grant No. 990404+00307)State New Drug Project (Grant No. 1996ND1035A01)Fok YingTung Educational Foundation (Grant No. 980706)State Key Laboratory of Chemo/Biosensing and Chemometrics Foundation (KCBCF0501201)Chongqing University Innovation Fund (CUIF030506)Chongqing Municipality Applied Science Fund (Grant No. CASF01-3-6)Momentous Juche Innovation Fundfor Tackle Key Problem Items (MJIF 03-5-6+04-10-10)
文摘Only from the primary structures of peptides, a new set of descriptors called the molecular electro-negativity edge-distance vector (VMED) was proposed and applied to describing and characterizing the molecular structures of oligopeptides and polypeptides, based on the electronegativity of each atom or electronic charge index (ECI) of atomic clusters and the bonding distance between atom-pairs. Here, the molecular structures of antigenic polypeptides were well expressed in order to propose the auto-mated technique for the computerized identification of helper T lymphocyte (Th) epitopes. Furthermore, a modified MED vector was proposed from the primary structures of polypeptides, based on the ECI and the relative bonding distance of the fundamental skeleton groups. The side-chains of each amino acid were here treated as a pseudo-atom. The developed VMED was easy to calculate and able to work. Some quantitative model was established for 28 immunogenic or antigenic polypeptides (AGPP) with 14 (1― 14) Ad and 14 other restricted activities assigned as "1"(+) and "0"(-), respectively. The latter comprised 6 Ab(15-20), 3 Ak(21-23), 2 Ek(24-26), 2 H-2k(27 and 28) restricted sequences. Good results were obtained with 90% correct classification (only 2 wrong ones for 20 training samples) and 100% correct prediction(none wrong for 8 testing samples); while con-trastively 100% correct classification (none wrong for 20 training samples) and 88% correct classification (1 wrong for 8 testing samples). Both stochastic samplings and cross valida-tions were performed to demonstrate good performance. The described method may also be suitable for estimation and prediction of classes I and II for major histocompatibility an-tigen (MHC) epitope of human. It will be useful in immune identification and recognition of pro-teins and genes and in the design and devel-opment of subunit vaccines. Several quantitative structure activity relationship (QSAR) models were developed for various oligopeptides and polypeptides including 58 dipeptides and 31 pentapeptides with angiotensin converting enzyme (ACE) inhibition by multiple linear regression (MLR) method. In order to explain the ability to characterize molecular structure of polypeptides, a molecular modeling investigation on QSAR was performed for functional prediction of polypeptide sequences with anti-genic activity and heptapeptide sequences with tachykinin activity through quantitative se-quence-activity models (QSAMs) by the molecular electronegativity edge-distance vector (VMED). The results showed that VMED exhibited both excellent structural selectivity and good activity prediction. Moreover, the results showed that VMED behaved quite well for both QSAR and QSAM of poly-and oli-gopeptides, which exhibited both good estimation ability and prediction power, equal to or better than those reported in the previous references. Finally, a preliminary conclusion was drwan: both classical and modified MED vectors were very useful structural descriptors. Some suggestions were proposed for further studies on QSAR/QSAM of proteins in various fields.
