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Equalized Electronegativity Based on the Valence Electrons and Its Application 被引量:2
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作者 武亚新 曹晨忠 袁华 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2011年第1期31-39,I0003,共10页
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
关键词 electronegativity equalization Valence electrons equilibration method Molecular electronegativity Group electronegativity Atomic charge
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The Electronegativity Analysis of c-C_4F_8 as a Potential Insulation Substitute of SF_6 被引量:7
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作者 赵小令 焦俊韬 +1 位作者 李冰 肖登明 《Plasma Science and Technology》 SCIE EI CAS CSCD 2016年第3期292-298,共7页
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
关键词 electronegativity c-C4Fs electron attachment density distribution
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Halodemetallation of (Z)-1-[2-(Triarylstannyl)vinyl]-cyclooctanol and Correlation of Proton Chemical Shift with Electronegativity 被引量:1
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作者 REN Yu-jie YU Li-mei +2 位作者 YANG Xue-feng CHEN Hui-lin BAI Ri-xia 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2002年第3期372-374,共3页
关键词 ORGANOTIN Halodemetallation CORRELATION Chemical shift electronegativity
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Regulation of Excited-State Intramolecular Proton Transfer Process and Photophysical Properties for Benzoxazole Isothiocyanate Fluorescent Dyes by Changing Atomic Electronegativity
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作者 Hongling Zhang Qingtong Liu +2 位作者 Yiying Wang Zhe Tang Panwang Zhou 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第2期331-337,I0011-I0025,I0003,共23页
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
关键词 Excited-state intramolecular proton transfer Photophysical properties Energy barrier electronegativity
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Quasi-delta negative ions density of Ar/O_(2)inductively coupled plasma at very low electronegativity
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作者 Shu-Xia Zhao 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第5期460-483,共24页
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
关键词 inductively coupled plasma Ar/O_(2)discharge very low electronegativity delta distribution of anions
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Measurement of electronegativity during the E to H mode transition in a radio frequency inductively coupled Ar/O2 plasma
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作者 Peng-Cheng Du Fei Gao +2 位作者 Xiao-Kun Wang Yong-Xin Liu You-Nian Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第3期371-377,共7页
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
关键词 electronegativity E to H mode transition radio frequency inductively coupled plasma
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Quantitative Structure-retention Relationship Study of Polychlorinated Dibenzothiophenes by Molecular Electronegativity Distance Vector(MEDV)
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作者 李美萍 张生万 陈婷 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2012年第3期429-437,共9页
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
关键词 molecular electronegativity distance vector(MEDV) polychlorinated dibenzothio-phenes(PCDTs) quantitative structure-retention relationship(QSRR) retention indices(RI)
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ELECTRONEGATIVITY TOPOLOGICAL INDEX AND ITS APPLICATION IN CORRELATION WITH MX,MX_2,MX_3,MX_4 MOLECULAR PROPERTIES
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作者 Yong DING Shihua WANG Dalian Institute of Chemical Physics,Academia Sinica,Dalian,116012 《Chinese Chemical Letters》 SCIE CAS CSCD 1991年第1期89-90,共2页
A New electronegativity topological index is defined and used to correlate with properties of MX,MX_2,MX_3,MX_4.
关键词 MX electronegativity TOPOLOGICAL INDEX AND ITS APPLICATION IN CORRELATION WITH MX MX2 MX3 MX4 MOLECULAR PROPERTIES ITS
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The Electronegativity and the Global Hardness Are Periodic Properties of Atoms
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作者 Nazmul Islam Dulal C. Ghosh 《Journal of Quantum Information Science》 2011年第3期135-141,共7页
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
关键词 Effective Nuclear CHARGE electronegativity HARDNESS Chemical Periodicity.
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Composition design of high yield strength points in single-phase Co-Cr-Fe-Ni-Mo multi-principal element alloys system based on electronegativity,thermodynamic calculations,and machine learning 被引量:1
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作者 Jiao-Hui Yan Zi-Jing Song +6 位作者 Wei Fang Xin-Bo He Ruo-Bin Chang Shao-Wu Huang Jia-Xin Huang Hao-Yang Yu Fu-Xing Yin 《Tungsten》 EI CSCD 2023年第1期169-178,共10页
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
关键词 High entropy alloys Multi-principal element alloys Yield strength electronegativity difference CALculation of PHAse Diagrams Machine learning
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Tailoring MXene Thickness and Functionalization for Enhanced Room‑Temperature Trace NO_(2) Sensing 被引量:2
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作者 Muhammad Hilal Woochul Yang +1 位作者 Yongha Hwang Wanfeng Xie 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第5期71-86,共16页
In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing performance.Utilizing a hybrid method... In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing performance.Utilizing a hybrid method involving high-pressure processing,stirring,and immiscible solutions,sub-100 nm MXene flake thickness is achieved within the MXene film on the Si-wafer.Functionalization control is achieved by defunctionalizing MXene at 650℃ under vacuum and H2 gas in a CVD furnace,followed by refunctionalization with iodine and bromine vaporization from a bubbler attached to the CVD.Notably,the introduction of iodine,which has a larger atomic size,lower electronegativity,reduce shielding effect,and lower hydrophilicity(contact angle:99°),profoundly affecting MXene.It improves the surface area(36.2 cm^(2) g^(-1)),oxidation stability in aqueous/ambient environments(21 days/80 days),and film conductivity(749 S m^(-1)).Additionally,it significantly enhances the gas-sensing performance,including the sensitivity(0.1119Ωppm^(-1)),response(0.2% and 23%to 50 ppb and 200 ppm NO_(2)),and response/recovery times(90/100 s).The reduced shielding effect of the–I-terminals and the metallic characteristics of MXene enhance the selectivity of I-MXene toward NO2.This approach paves the way for the development of stable and high-performance gas-sensing two-dimensional materials with promising prospects for future studies. 展开更多
关键词 Controlled MXene thickness Gaseous functionalization approach Lower electronegativity functional groups Enhanced MXene stability Trace NO_(2)sensing
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Dipole polarization modulating of vinylene-linked covalent organic frameworks for efficient photocatalytic hydrogen evolution
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作者 Ming Wang Yaling Li +6 位作者 Dengxin Yan Hui Hu a Yujie Song Xiaofang Su Jiamin Sun Songtao Xiao Yanan Gao 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第10期103-112,共10页
Photocatalytic hydrogen(H_(2))evolution using covalent organic frameworks(COFs)is an attractive and promising avenue for exploration,but one of its big challenges is low photo-induced charge separation.In this study,w... Photocatalytic hydrogen(H_(2))evolution using covalent organic frameworks(COFs)is an attractive and promising avenue for exploration,but one of its big challenges is low photo-induced charge separation.In this study,we present a straightforward and facile dipole polarization engineering strategy to enhance charge separation efficiency,achieved through atomic modulation(O,S,and Se)of the COF monomer.Our findings demonstrate that incorporating atoms with varying electronegativities into the COF matrix significantly influences the local dipole moment,thereby affecting charge separation efficiency and photostability,which in turn affects the rates of photocatalytic H_(2) evolution.As a result,the newly developed TMT-BO-COF,which contains highly electronegative O atoms,exhibits the lowest exciton binding energy,the highest efficiency in charge separation and transportation,and the longest lifetime of the active charges.This leads to an impressive average H_(2) production rate of 23.7 mmol g^(−1) h^(−1),which is 2.5 and 24.5 times higher than that of TMT-BS-COF(containing S atoms)and TMT-BSe-COF(containing Se atoms),respectively.A novel photocatalytic hydrogen evolution mechanism based on proton-coupled electron transfer on N in the structure of triazine rings in vinylene-linked COFs is proposed by theoretical calculations.Our findings provide new insights into the design of highly photoactive organic framework materials for H_(2) evolution and beyond. 展开更多
关键词 Covalent organic framework Vinylene linkage electronegativity Dipole polarization Photocatalytic hydrogen evolution
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Molecular electronegativity in density functional theory (II) --Direct calculation of group electronegativity and the atomic charges in a group 被引量:7
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作者 杨忠志 沈尔忠 《Science China Chemistry》 SCIE EI CAS 1996年第1期20-28,共9页
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
关键词 density functional theory etectronegativity EQUALIZATION principle GROUP electronegativity ATOMIC CHARGES in a group.
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Molecular electronegativity in density functional theory (I)——Direct calculation of atomic charges in a molecule via electronegativity equalization principle 被引量:5
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作者 杨忠志 沈尔忠 《Science China Chemistry》 SCIE EI CAS 1995年第5期521-528,共8页
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
关键词 density functional theory electronegativity EQUALIZATION PRINCIPLE harmonic MOLECULAR electronegativity charge distribution in a big molecule.
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Molecular electronegativity in density functional theory (VI) --Atom-bond electronegativity equalization model 被引量:5
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作者 杨忠志 王长生 唐敖庆 《Science China Chemistry》 SCIE EI CAS 1998年第3期331-336,共6页
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
关键词 DENSITY functional theory electronegativity EQUALIZATION method electronic DENSITY CHARGE distribution total MOLECULAR energy.
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Molecular electronegativity in density functional theory(Ⅷ)——Charge polarization modes in a closed system 被引量:2
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作者 杨忠志 王长生 《Science China Chemistry》 SCIE EI CAS 2000年第2期187-195,共9页
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
关键词 atom-bond electronegativity EQUALIZATION model closed system SOFTNESS matrix electron population normal mode BOND CHARGE polarization.
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Neodymium Organic Sulfonate Complexes: Tunable Electronegativity/Steric Hindrance and Application in Controlled Cis-1,4-polymerization of Butadiene 被引量:1
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作者 Jian-Yun He Long Cui +2 位作者 Yan-Long Qi Quan-Quan Dai Chen-Xi Bai 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2019年第3期208-215,共8页
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
关键词 NEODYMIUM catalysts ORGANIC sulfonate complexes Tunable electronegativity and steric hindrance Cis-1 4-polymerization BUTADIENE
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Structural parameterization and functional prediction of antigenic polypeptome sequences with biological activity through quantitative sequence-activity models (QSAM) by molecular electronegativity edge-distance vector (VMED) 被引量:1
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作者 LI ZhiLiang1,2, WU ShiRong1,2, CHEN ZeCong1,2, YE Nancy1,2, YANG ShengXi1,2, LIAO ChunYang1,2, ZHANG MengJun1,2,3, YANG Li1,2, MEI Hu1,2,4, YANG Yan1,2, ZHAO Na1,2, ZHOU Yuan1,2, ZHOU Ping1,2, XIONG Qing1,2, XU Hong1,2, LIU ShuShen1,2, LING ZiHua1,2, CHEN Gang1,2,4 & LI GenRong1,2 1 College of Chemistry and Chemical Engineering/Key Laboratory for Chemobiomedical Science and Engineering under Chongqing Municipality, College of Life Science and Biological Engineering/Key Laboratory for Biomechanics and Tissue Engineering under Ministry of Education, Chongqing University, Chongqing 400044, China 2 State Key Laboratory for Chemobiosensors and Chemobiometrics under MOST at Hunan University, Changsha 410012, China +1 位作者 3 Department of Medical Analysis/PLA Center of Bioinformatics Immunology, Surgeon Third University, Chongqing 400031, China 4 Technology Centre for Life Sciences, Singapore Polytechnic, 500 Dover Road, Singapore 139651, Singapore 《Science China(Life Sciences)》 SCIE CAS 2007年第5期706-716,共11页
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
关键词 MOLECULAR electronegativity distance-edge vector (VMED) antigenic polypeptide (AGPP) sequences bioactive OLIGOPEPTIDE (BAOP) chains QUANTITATIVE sequence-activity MODELS (QSAM) theoretically computational descriptors (TCD)
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Influences of Brnsted Acidic Sites in HZSM-5 on Polarization and Electronegativity of Ethene Studied by Molecular Dynamics 被引量:1
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作者 樊建芬 肖鹤鸣 +1 位作者 王秋霞 夏其英 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2002年第7期638-643,共6页
Molecular dynamics simulation has been performed for studying thepolarization and electronegativity of ethene molecules near Broensted acidic sites in H[Al] ZSM-5.The result shows that the molecules are polarized most... Molecular dynamics simulation has been performed for studying thepolarization and electronegativity of ethene molecules near Broensted acidic sites in H[Al] ZSM-5.The result shows that the molecules are polarized most at the edges of intersections and least atthe segments of channels. On the contrary, the highest global molecular electronegativity is foundat the centers of channel segments. Al substitution slightly increases the molecular dipole moment,but hardly affects the molecular electronegativity. Broensted acidic proton decreases the dipolemoment of guest molecule, but increases the molecular elec-tronegativity. 展开更多
关键词 molecular dynamics simulation ETHENE POLARIZATION electronegativity H[Al]ZSM-5 broensted acidic sites
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Peculiarities of the dependences of the dielectric properties of solid solutions of multicomponent systems on the electronegativity of their constituent cations
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作者 Andryushin Konstantin Dudkina Svetlana +5 位作者 Shilkina Lidiya Sahoo Sushrisangita Moysa Maksim Andryushina Inna Verbenko Iliya Reznichenko Larisa 《Journal of Advanced Dielectrics》 CAS 2022年第4期18-23,共6页
Solid solutions(SS)of 3-and 4-component systems based on lead titanate-zirconate were prepared by the method of solid-phase reactions and uniaxial hot pressing.The dependences of the relative permittivity of polarized... Solid solutions(SS)of 3-and 4-component systems based on lead titanate-zirconate were prepared by the method of solid-phase reactions and uniaxial hot pressing.The dependences of the relative permittivity of polarized samples on the electronegativity(EN)of their constituent cations have been studied.The ferro-hardness of the SS(the stability of the domain structure to external influences)is shown to be directly dependent on the EN of elements B in the corresponding oxidation states,i.e.,the degree of covalence of the B-O bond.The deviation from this dependence in SS with Ni and Cd is explained by their individual features,which result in changes in the degree of bond covalence in both cationic sublattices.The conducted crystal-chemical analysis made it possible to choose promising SS when creating ferroelectric materials,including textured piezoelectric ceramic materials for piezoelectric transducers for various purposes:Piezotransformers,piezoelectric motors,ultrasonic emitters,filter devices,ultrasonic flaw detectors,accelerometers,etc. 展开更多
关键词 Solid solutions multicomponent systems lead titanate-zirconate electronegativity dielectric properties
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