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
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
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
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
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
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
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
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
A weakly magnetized sheath for a collisionless, electronegative plasma comprising positive ions,electrons, and negative ions is investigated numerically using the fluid approach. The electrons are considered to be non...A weakly magnetized sheath for a collisionless, electronegative plasma comprising positive ions,electrons, and negative ions is investigated numerically using the fluid approach. The electrons are considered to be non-Maxwellian in nature and are described by Tsalli's distribution. Such electrons have a substantial effect on the sheath properties. The study also reveals that non-Maxwellian distribution is the most realistic description for negative ions in the presence of an oblique magnetic field. In addition to the negative ion temperature, the sheath potential is also affected by the nonextensive parameters. The present research finds application in the plasma processing and semiconductor industry as well as in space plasmas.展开更多
A molecular electronegativity distance vector(M_t)based on 13 atomic types has been used to describe the structures of 19 conjugates(LHCc)of levofloxacin-thiadiazole HDAC inhibitor(HDACi)and related inhibitory activit...A molecular electronegativity distance vector(M_t)based on 13 atomic types has been used to describe the structures of 19 conjugates(LHCc)of levofloxacin-thiadiazole HDAC inhibitor(HDACi)and related inhibitory activities(pH_i,i=1,2,6)of LHCc against histone deacetylases(HDACs,such as HDAC1,HDAC2 and HDAC6).The quantitative structure-activity relationships(QSAR)were established by using leaps-and-bounds regression analysis for the inhibitory activities(pH_i)of 19 above compounds to HDAC1,HDAC2 and HDAC6 along with M_t.The correlation coefficients(R^2)and the leave-one-out(LOO)cross validation R_(cv)^(2 )for the pH_1,pH_(2 )and pH_(6 )models were 0.976 and 0.949;0.985 and 0.977;0.976 and 0.932,respectively.The QSAR models had favorable correlations,as well as robustness and good prediction capability by R^2,F,R^2_(cv),A_(IC),F_(IT )and V_(IF )tests.Validated by using 3876 training sets,the models have good external prediction ability.The results indicate that the molecular structural units:–CH_g–(g=1,2),–NH_2,–OH,=O,–O–and–S–are the main factors which can affect the inhibitory activity of pH_1,pH_(2 )as well as pH_(6 )bioactivities of these compounds directly.Accordingly,the main interactions between HDACs inhibitor and HDACs are hydrophobic interaction,hydrogen bond,and coordination with Zn^(2+)to form compounds,which is consistent with the results in reports.展开更多
In Quantum Information Theory(QIT) the classical measures of information content in probability distributions are replaced by the corresponding resultant entropic descriptors containing the nonclassical terms generate...In Quantum Information Theory(QIT) the classical measures of information content in probability distributions are replaced by the corresponding resultant entropic descriptors containing the nonclassical terms generated by the state phase or its gradient(electronic current). The classical Shannon(S[p]) and Fisher(I[p]) information terms probe the entropic content of incoherent local events of the particle localization, embodied in the probability distribution p, while their nonclassical phase-companions, S[ Φ ] and I[ Φ ], provide relevant coherence information supplements.Thermodynamic-like couplings between the entropic and energetic descriptors of molecular states are shown to be precluded by the principles of quantum mechanics. The maximum of resultant entropy determines the phase-equilibrium state, defined by "thermodynamic" phase related to electronic density,which can be used to describe reactants in hypothetical stages of a bimolecular chemical reaction.Information channels of molecular systems and their entropic bond indices are summarized, the complete-bridge propagations are examined, and sequential cascades involving the complete sets of the atomic-orbital intermediates are interpreted as Markov chains. The QIT description is applied to reactive systems R = A―B, composed of the Acidic(A) and Basic(B) reactants. The electronegativity equalization processes are investigated and implications of the concerted patterns of electronic flows in equilibrium states of the complementarily arranged substrates are investigated. Quantum communications between reactants are explored and the QIT descriptors of the A―B bond multiplicity/composition are extracted.展开更多
Carbon surface with large oxygen and carbon ratio(O/C) indicated an outstanding electro-catalytic activity toward L-ascorbic acid oxidation, compared to platinum group metals. However, interrelation of surface functio...Carbon surface with large oxygen and carbon ratio(O/C) indicated an outstanding electro-catalytic activity toward L-ascorbic acid oxidation, compared to platinum group metals. However, interrelation of surface functional groups and its electro-catalytic activity is still unclear. In this paper, we prepared different levels of oxidized carbons by a simple acid treatment and investigated the correlation between the surface oxygen functional groups of acid-treated carbon and electro-catalytic activity in an electrooxidation of L-ascorbic acid. Positively charged carbon was demonstrated by lone pair electron of oxygen from valence band spectra study. It was revealed that the positively charged carbon, especially involved in carbonyl, showed enhanced the electro-catalytic activity through both better adsorption of negatively charged reactants and lowered LUMO by electronegativity of oxygen.展开更多
The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-pha...The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-phase molecules,X,and the electronic stability of MCAs X^(Q-),are discussed.The drawbacks encountered when applying computational and/or conceptual density functional theory(DFT)to MCAs are highlighted.We develop and test a different model based on the valence-state concept.As in DFT,the electronic energy,E(N,v_(ex)),is a continuous function of the average electron number,N,and the external potential,v_(ex),of the nuclei.The valence-state-parabola is a second-order polynomial that allows extending E(N,v_(ex))to dianions and higher MCAs.The model expresses the maximum electron acceptance,Q_(max),and the higher electron affinities,A_Q,as simple functions of the firstelectron affinity,A_1,and the ionization energy,I,of the"ancestor"system.Thus,the maximum electron acceptance is Q_(max,calc)=1+12A_1/7(I-A_1).The ground-state parabola model of the conceptual DFT yields approximately half of this value,and it is termed Q_(max,GS)=?+A_1/(I-A_1).A large variety of molecules are evaluated including fullerenes,metal clusters,super-pnictogens,super-halogens(OF_3),super-alkali species(OLi_3),and neutral or charged transition-metal complexes,AB_(m )L_n^(0/+/-).The calculated second electron affinity A_(2,calc)=A_1-(7/12)(I-A_1)is linearly correlated to the literature references A_(2,lit) with a correlation coefficient R=0.998.A_2 or A_3 values are predicted for further 24 species.The appearance sizes,n_(ap)^(3-),of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.展开更多
Based on theoretical calculation of electronegativity of groups of flotation reagent andmethod of infrared adsorption spectroscopy,the collection and adsorption of α-nitroso-β-naphthol in hematite flotation have bee...Based on theoretical calculation of electronegativity of groups of flotation reagent andmethod of infrared adsorption spectroscopy,the collection and adsorption of α-nitroso-β-naphthol in hematite flotation have been studied.The chemical adsorption seems to bepredominant owing to formation of pentacyclic nitrosyl chelate compound by atoms ofnitrosyl bond in α-nitroso-β-naphthol together with Fe(Ⅲ)on hematite surface.Mean-while,the nonuniform multilayer physical adsorption is also occurred.展开更多
Biofilm formation is essential for the survival and growth of Escherichia coli?in catheter-associated infections. Individuals with type 2 diabetes mellitus can excrete insulin and/or glucose in their urine. This popul...Biofilm formation is essential for the survival and growth of Escherichia coli?in catheter-associated infections. Individuals with type 2 diabetes mellitus can excrete insulin and/or glucose in their urine. This population also has an increased incidence of urinary tract infections. The focus of this study was to determine if the composition of Foley catheter material affects biofilm formation by E. coli in a model system for type 2 diabetes mellitus. Rubber (lubricious-coated), silicon-coated, silver-coated and nitrofurazone-coated catheter segments (5 mm;n = 6) were tested. Catheter segments were added to E. coli ATCC25922 (104 CFU/ml, final concentration) in artificial urine alone, or with insulin (40 μU/ml) and/or glucose (0.1%). After incubation (18 h, 37?C, in air and anaerobically) the level of catheter-associated biofilm was determined by crystal violet staining (Abs550nm). Statistical analysis was done by ANOVA with post-hoc analysis (Tukey). Neither nitrofurazone-coated nor silver-coated catheters supported the formation of E. coli biofilm, regardless of growth condition tested. In contrast, under aerobic biofilm formation on silicon catheters was significantly higher (p E. coli controls. Biofilm formation was also significantly increased展开更多
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.
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 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 the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT)(No. 2021R1I1A1A0105621313, No. 2022R1F1A1074441, No. 2022K1A3A1A20014496, and No. 2022R1F1A1074083)supported by the Ministry of Education Funding (No. RIS 2021-004)supported by the Brain Pool program funded by the Ministry of Science and ICT through the National Research Foundation of Korea (RS-2023-00284318).
文摘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.
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 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.
基金This study was financially supported by the Ministry of Science and Higher Education of the Russian Federation(State task in the field of scientific activity,scientific project No.(0852-2020-0032)/(BAZ0110/20-3-07IF))This report is presented at the 10th Anniversary International Conference on“Physics and Mechanics of New Materials and Their Applications”(PHENMA 2021),Divnomorsk,Russia,May 23-27,2022.
文摘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.
文摘A weakly magnetized sheath for a collisionless, electronegative plasma comprising positive ions,electrons, and negative ions is investigated numerically using the fluid approach. The electrons are considered to be non-Maxwellian in nature and are described by Tsalli's distribution. Such electrons have a substantial effect on the sheath properties. The study also reveals that non-Maxwellian distribution is the most realistic description for negative ions in the presence of an oblique magnetic field. In addition to the negative ion temperature, the sheath potential is also affected by the nonextensive parameters. The present research finds application in the plasma processing and semiconductor industry as well as in space plasmas.
基金supported by the National Natural Science Foundation of China(21473081,21075138)special fund of State Key Laboratory of Structure Chemistry(20160028)
文摘A molecular electronegativity distance vector(M_t)based on 13 atomic types has been used to describe the structures of 19 conjugates(LHCc)of levofloxacin-thiadiazole HDAC inhibitor(HDACi)and related inhibitory activities(pH_i,i=1,2,6)of LHCc against histone deacetylases(HDACs,such as HDAC1,HDAC2 and HDAC6).The quantitative structure-activity relationships(QSAR)were established by using leaps-and-bounds regression analysis for the inhibitory activities(pH_i)of 19 above compounds to HDAC1,HDAC2 and HDAC6 along with M_t.The correlation coefficients(R^2)and the leave-one-out(LOO)cross validation R_(cv)^(2 )for the pH_1,pH_(2 )and pH_(6 )models were 0.976 and 0.949;0.985 and 0.977;0.976 and 0.932,respectively.The QSAR models had favorable correlations,as well as robustness and good prediction capability by R^2,F,R^2_(cv),A_(IC),F_(IT )and V_(IF )tests.Validated by using 3876 training sets,the models have good external prediction ability.The results indicate that the molecular structural units:–CH_g–(g=1,2),–NH_2,–OH,=O,–O–and–S–are the main factors which can affect the inhibitory activity of pH_1,pH_(2 )as well as pH_(6 )bioactivities of these compounds directly.Accordingly,the main interactions between HDACs inhibitor and HDACs are hydrophobic interaction,hydrogen bond,and coordination with Zn^(2+)to form compounds,which is consistent with the results in reports.
文摘In Quantum Information Theory(QIT) the classical measures of information content in probability distributions are replaced by the corresponding resultant entropic descriptors containing the nonclassical terms generated by the state phase or its gradient(electronic current). The classical Shannon(S[p]) and Fisher(I[p]) information terms probe the entropic content of incoherent local events of the particle localization, embodied in the probability distribution p, while their nonclassical phase-companions, S[ Φ ] and I[ Φ ], provide relevant coherence information supplements.Thermodynamic-like couplings between the entropic and energetic descriptors of molecular states are shown to be precluded by the principles of quantum mechanics. The maximum of resultant entropy determines the phase-equilibrium state, defined by "thermodynamic" phase related to electronic density,which can be used to describe reactants in hypothetical stages of a bimolecular chemical reaction.Information channels of molecular systems and their entropic bond indices are summarized, the complete-bridge propagations are examined, and sequential cascades involving the complete sets of the atomic-orbital intermediates are interpreted as Markov chains. The QIT description is applied to reactive systems R = A―B, composed of the Acidic(A) and Basic(B) reactants. The electronegativity equalization processes are investigated and implications of the concerted patterns of electronic flows in equilibrium states of the complementarily arranged substrates are investigated. Quantum communications between reactants are explored and the QIT descriptors of the A―B bond multiplicity/composition are extracted.
基金supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (20153030031720)
文摘Carbon surface with large oxygen and carbon ratio(O/C) indicated an outstanding electro-catalytic activity toward L-ascorbic acid oxidation, compared to platinum group metals. However, interrelation of surface functional groups and its electro-catalytic activity is still unclear. In this paper, we prepared different levels of oxidized carbons by a simple acid treatment and investigated the correlation between the surface oxygen functional groups of acid-treated carbon and electro-catalytic activity in an electrooxidation of L-ascorbic acid. Positively charged carbon was demonstrated by lone pair electron of oxygen from valence band spectra study. It was revealed that the positively charged carbon, especially involved in carbonyl, showed enhanced the electro-catalytic activity through both better adsorption of negatively charged reactants and lowered LUMO by electronegativity of oxygen.
文摘The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-phase molecules,X,and the electronic stability of MCAs X^(Q-),are discussed.The drawbacks encountered when applying computational and/or conceptual density functional theory(DFT)to MCAs are highlighted.We develop and test a different model based on the valence-state concept.As in DFT,the electronic energy,E(N,v_(ex)),is a continuous function of the average electron number,N,and the external potential,v_(ex),of the nuclei.The valence-state-parabola is a second-order polynomial that allows extending E(N,v_(ex))to dianions and higher MCAs.The model expresses the maximum electron acceptance,Q_(max),and the higher electron affinities,A_Q,as simple functions of the firstelectron affinity,A_1,and the ionization energy,I,of the"ancestor"system.Thus,the maximum electron acceptance is Q_(max,calc)=1+12A_1/7(I-A_1).The ground-state parabola model of the conceptual DFT yields approximately half of this value,and it is termed Q_(max,GS)=?+A_1/(I-A_1).A large variety of molecules are evaluated including fullerenes,metal clusters,super-pnictogens,super-halogens(OF_3),super-alkali species(OLi_3),and neutral or charged transition-metal complexes,AB_(m )L_n^(0/+/-).The calculated second electron affinity A_(2,calc)=A_1-(7/12)(I-A_1)is linearly correlated to the literature references A_(2,lit) with a correlation coefficient R=0.998.A_2 or A_3 values are predicted for further 24 species.The appearance sizes,n_(ap)^(3-),of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.
文摘Based on theoretical calculation of electronegativity of groups of flotation reagent andmethod of infrared adsorption spectroscopy,the collection and adsorption of α-nitroso-β-naphthol in hematite flotation have been studied.The chemical adsorption seems to bepredominant owing to formation of pentacyclic nitrosyl chelate compound by atoms ofnitrosyl bond in α-nitroso-β-naphthol together with Fe(Ⅲ)on hematite surface.Mean-while,the nonuniform multilayer physical adsorption is also occurred.
文摘Biofilm formation is essential for the survival and growth of Escherichia coli?in catheter-associated infections. Individuals with type 2 diabetes mellitus can excrete insulin and/or glucose in their urine. This population also has an increased incidence of urinary tract infections. The focus of this study was to determine if the composition of Foley catheter material affects biofilm formation by E. coli in a model system for type 2 diabetes mellitus. Rubber (lubricious-coated), silicon-coated, silver-coated and nitrofurazone-coated catheter segments (5 mm;n = 6) were tested. Catheter segments were added to E. coli ATCC25922 (104 CFU/ml, final concentration) in artificial urine alone, or with insulin (40 μU/ml) and/or glucose (0.1%). After incubation (18 h, 37?C, in air and anaerobically) the level of catheter-associated biofilm was determined by crystal violet staining (Abs550nm). Statistical analysis was done by ANOVA with post-hoc analysis (Tukey). Neither nitrofurazone-coated nor silver-coated catheters supported the formation of E. coli biofilm, regardless of growth condition tested. In contrast, under aerobic biofilm formation on silicon catheters was significantly higher (p E. coli controls. Biofilm formation was also significantly increased
