The theoretical calculation of LaNi4Co, in which Co substituted for Ni at various sites, was performed by adopting the method of total energy based on the Density Functional Theory. The augmented plane wave function w...The theoretical calculation of LaNi4Co, in which Co substituted for Ni at various sites, was performed by adopting the method of total energy based on the Density Functional Theory. The augmented plane wave function was selected as a basis set in combination with Ultra-soft Pseudopotential technology. The geometry of LaNi5 was optimized and the parameters and properties of the structure were given. The theoretical results accord well with experiments. This method provides a theoretical approach for the structure prediction of such alloy. The calculations of total energy, electronic density of states and Mulliken population of LaNi4Co were carried out. The electronic structure of LaNi4Co and the change of the electronic structure due to the Co-substitution in LaNi5 alloy were analyzed from the calculated results. The stability of the alloy in which Ni was partially substituted by Co at various sites was compared and the factors controlling stability were discussed. The theoretical value of formation heat was calculated.展开更多
Inverse halogen bonds interactions involving Br in the electronic deficiency systems of CH3+...Br-Y (Y=H, CCH, CN, NC) have been investigated by B3LYP/6- 311++G(d, p) and MP2/6-311++G(d, p) methods. The cal...Inverse halogen bonds interactions involving Br in the electronic deficiency systems of CH3+...Br-Y (Y=H, CCH, CN, NC) have been investigated by B3LYP/6- 311++G(d, p) and MP2/6-311++G(d, p) methods. The calculated interaction energies with basis set super-position error correction of the four IXBs complexes are 218.87, 219.48, 159.18, and 143.05kJ/mol (MP2/6-311++G(d, p)), respectively. The relative stabilities of the four complexes increased in the order: CH3+ … BrCN〈CH3+…- BrNC〈CH3+… BrH≈CH3+ …BrCCH. Natural bond orbital theory analysis and the chemical shifts calculation of the related atoms revealed that the charges flow from Br-Y to CH3e. Here, the Br of Br-Y acts as both a halogen bond donor and an electron donor. Therefore, compared with conventional halogen bonds, the IXBs complexes formed between Br-Y and CH3+. Atoms-in-molecules theory has been used to investigate the topological properties of the critical points of the four IXBs structures which have more covalent content.展开更多
The fractal dimensions in different topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating different kinds of humic acids (HA) water at different initial pH (9.0, 7.0, 5.0) a...The fractal dimensions in different topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating different kinds of humic acids (HA) water at different initial pH (9.0, 7.0, 5.0) and PFC dosages, were calculated by effective densitymaximum diameter, image analysis, and N2 absorption-desorption methods, respectively. The mass fractal dimensions (De) of PFC-HA floes were calculated by bi-logarithm relation of effective density with maximum diameter and Logan empirical equation. The Df value was more than 2.0 at initial pH of 7,0, which was 11% and 13% higher than those at pH 9.0 and 5.0, respecively, indicating the most compact flocs formed in flocculated HA water at initial pH of 7.0. The image analysis for those flocs indicates that after flocculating the HA water at initial pH greater than 7.0 with PFC flocculant, the fractal dimensions of D2 (logA vs. logdL) and D3 (logVsphere vs. logdL) of PFC-HA floes decreased with the increase of PFC dosages, and PFC-HA floes showed a gradually looser structure. At the optimum dosage of PFC, the D2 (logA vs. logdL) values of the flocs show 14%-43% difference with their corresponding Dr, and they even had different tendency with the change of initial pH values. However, the D2 values of the floes formed at three different initial pH in HA solution had a same tendency with the corresponding Df. Based on fractal Frenkel-Halsey-HiU (FHH) adsorption and desorption equations, the pore surface fractal dimensions (Ds) for dried powders of PFC-HA flocs formed in HA water with initial pH 9.0 and 7.0 were all close to 2.9421, and the Ds values of flocs formed at initial pH 5.0 were less than 2.3746. It indicated that the pore surface fractal dimensions of PFC-HA floes dried powder mainly show the irregularity from the mesopore-size distribution and marcopore-size distribution.展开更多
In order to solve the problems of too large mass,too complex structure and poor flexibility of the 6 DOF manipulator,the topological optimization theory based on variable density method is applied to the 6-DOF manipul...In order to solve the problems of too large mass,too complex structure and poor flexibility of the 6 DOF manipulator,the topological optimization theory based on variable density method is applied to the 6-DOF manipulator,the topology optimization of the main structural components of the manipulator is carried out with the help of the finite element software ANSYS,and the optimized structure is simplified according to the density distribution of the units and the requirements of manufacturability.the results are compared and analysed by static mechanics.It shows that the whole mass of the 6-DOF manipulator is reduced by 47.23%without changing the original mechanical properties after topological optimization,and the optimized model can meet the requirements of manufacturability,the optimization effect is signifcant,which can be used as a reference for the structure optimization of the 6-DOF manipulator.展开更多
In this perspective,we review the chemical information encoded in electron density and other ingredients used in semilocal functionals.This information is usually looked at from the functional point of view:the exchan...In this perspective,we review the chemical information encoded in electron density and other ingredients used in semilocal functionals.This information is usually looked at from the functional point of view:the exchange density or the enhancement factor are discussed in terms of the reduced density gradient.However,what parts of a molecule do these 3D functions represent? We look atthese quantities in real space,aiming to understand the electronic structure information they encode and provide an insight from the quantum chemical topology(QCT).Generalized gradient approximations(GGAs) provide information about the presence of chemical interactions,whereas meta-GGAs can differentiate between the different bonding types.By merging these two techniques,we show new insight into the failures of semilocal functionals owing to three main errors:fractional charges,fractional spins,and non-covalent interactions.We build on simple models.We also analyze the delocalization error in hydrogen chains,showing the ability of QCT to reveal the delocalization error introduced by semilocal functionals.Then,we show how the analysis of localization can help understand the fractional spin error in alkali atoms,and how it can be used to correct it.Finally,we show that the poor description of GGAs of isodesmic reactions in alkanes is due to 1,3-interactions.展开更多
The thermodynamic properties of dibenzofurans (DFs), xanthones (XTs) and an-thraquinones (AQs) with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were...The thermodynamic properties of dibenzofurans (DFs), xanthones (XTs) and an-thraquinones (AQs) with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were calculated at the B3LYP/6-311G^* level using Gaussian 03 program. The isodesmic reactions were designed to calculate the standard free energy of formation (△fG^θ). Three types of hydrogen bonds exist in the three kinds of chemicals and their bond energies were ascertained as 7-15, 15-23 and 49-58 kJ·mo1^-1 respectively by comparing the △fG^θ values. Electronic density topology analysis was applied to validate the strength of bond.展开更多
We study the electronic band structure, density distribution, and transport of a Bi2Se3 nanoribbon, We find that the density distribution of the surface states is dependent on not only the shape and size of the transv...We study the electronic band structure, density distribution, and transport of a Bi2Se3 nanoribbon, We find that the density distribution of the surface states is dependent on not only the shape and size of the transverse cross section of the nanoribbon, but also the energy of the electron. We demonstrate that a transverse electric field can eliminate the coupling between surface states on the walls of the nanoribbon, remove the gap of the surface states, and restore the quantum spin Hall effects. In addition, we study the spin-dependent transport property of the surface states transmitting from top and bottom surfaces (x-y plane) to the side surfaces (z-x plane) of a Bi2Se3 nanoribbon. We find that transverse electric fields can open two surface channels for spin-up and -down Dirac electrons, and then switch off one channel for the spin-up Dirac electron. Our results may provide a simple way for the design of a spin filter based on topological insulator nanostructures.展开更多
In this research, the hydrogen bonds Y···H-X (X = C, N; Y = N, O) of thymine and uracil have been theoretically studied. The results show that hydrogen bond leads to bond length elongation and stretch...In this research, the hydrogen bonds Y···H-X (X = C, N; Y = N, O) of thymine and uracil have been theoretically studied. The results show that hydrogen bond leads to bond length elongation and stretches the frequency red-shift of N-H···Y. Meanwhile, the C-H···O bonds shorten and stretch the frequency blue-shift. They all belong to traditional hydrogen bonds. The intermolecular charge transfer caused by the intermolecular hyperconjugation s*(N–H) → n(Y) and intramolecular charge redistribution by intramolecular hyperconjugation σ(C-H) →σ*(C-N) play important roles in the formation of hydrogen bonds. According to thejudgment standards proposed by Bader and Popelier, these hydrogen bonds have typical electron density topological properties. Electrostatic surface potential (ESP) is a useful physicochemical property of a molecule that provides insights into inter- and intramolecular associations, as well as the prediction of likely sites of electrophilic and nucleophilic metabolic attack.展开更多
The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G(d,p) and MP2(Full)/6-311G(d,p). The computational results show that the reaction has three channels and proceeds by the ...The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G(d,p) and MP2(Full)/6-311G(d,p). The computational results show that the reaction has three channels and proceeds by the addition of fluorine atoms on carbon or sulfur sites of CH2SH, forming initial intermediates. The calculated results show that the channel, in which fluorine attaches to the carbon atom to form CH2S and HF, is the most likely reaction pathway. Topological analysis of electron density was carried out for the three channels. The change trends of the chemical bonds on the reaction paths were discussed. The energy transition states and the structure transition regions (states) of the three channels were found. The calculated results show that the structure transition regions are broad in unobvious exothermic reactions or unobvious endothermic reactions, and are narrow in obvious exothermic reactions or obvious endothermic reactions.展开更多
Plasma photonic crystals designed in this paper are composed of gas discharge tubes to control the flow of electromagnetic waves.The band structures calculated by the finite element method are consistent with the expe...Plasma photonic crystals designed in this paper are composed of gas discharge tubes to control the flow of electromagnetic waves.The band structures calculated by the finite element method are consistent with the experimental results which have two distinct attenuation peaks in the ranges of 1-2.5 GHz and 5-6 GHz.Electromagnetic parameters of the plasma are extracted by the Nicolson-Ross-Weir method and effective medium theory.The measured electron density is between 1×1011 cm-3 and1×1012 cm-3,which verifies the correctness of the parameter used in the simulation,and the collision frequency is near 1.5×1010 Hz.As the band structures are corroborated by the measured scattering parameters,we introduce the concept of photonic topological insulator based on the quantum Valley Hall effect into the plasma photonic crystal.A valley-dependent plasma photonic crystal with hexagonal lattice is constructed,and the phase transition of the valley K(K’)occurs by breaking the spatial inversion symmetry.Valley-spin locked topological edge states are generated and excited by chiral sources.The frequency of the non-bulk state can be dynamically regulated by the electron density.This concept paves the way for novel,tunable topological edge states.More interestingly,the Dirac cone is broken when the electron density increases to 3.1×1012 cm-3,which distinguishes from the methods of applying a magnetic field and changing the symmetry of the point group.展开更多
The geometries,electronic structure,IR spectrum and other properties of hydrogen interaction between 5-fluorouracil and glycine were studied at the B3LYP/6-31+G* level.Single point energy calculations were executed ...The geometries,electronic structure,IR spectrum and other properties of hydrogen interaction between 5-fluorouracil and glycine were studied at the B3LYP/6-31+G* level.Single point energy calculations were executed at the B3LYP/6-311++G** and B3LYP/aug-cc-pvdz levels,and natural bond orbital (NBO) analysis was carried out at the B3LYP/6-31+G* level.Finally,the hydrogen bonds were discussed via AIM electronic density topology analysis.展开更多
In this study, we investigated the effects of mobile phone radiation on spatial learning, reference memory, and morphology in related brain regions. After the near-field radiation (0.52 1.08 W/kg) was delivered to 8...In this study, we investigated the effects of mobile phone radiation on spatial learning, reference memory, and morphology in related brain regions. After the near-field radiation (0.52 1.08 W/kg) was delivered to 8-week-old Wistar rats 2 hours per day for 1 month, behavioral changes were examined using the Morris water maze. Compared with the sham-irradiated rats, the irradiated rats exhibited impaired performance. Morphological changes were investigated by examining synaptic ultrastructural changes in the hippocampus. Using the physical dissector technique, the number of pyramidal neurons, the synaptic profiles, and the length of postsynaptic densities in the CA1 region were quantified stereologically. The morphological changes included mitochondrial degenerations, fewer synapses, and shorter postsynaptic densities in the radiated rats. These findings indicate that mobile phone radiation can significantly impair spatial learning and reference memory and induce morphological changes in the hippocampal CA1 region.展开更多
The title compound of isonicotinato lead(Ⅱ) [Pb(C5H4NCOO)2] has been optimized at B3LYP/LANL2DZ level of theory and calculated results show that the lead(Ⅱ) ion adopts 4-coordinate geometry. Atomic charge dist...The title compound of isonicotinato lead(Ⅱ) [Pb(C5H4NCOO)2] has been optimized at B3LYP/LANL2DZ level of theory and calculated results show that the lead(Ⅱ) ion adopts 4-coordinate geometry. Atomic charge distributions indicate that during forming the title compound, each isonicotinic acid ion transfers -0.452 e to lead(Ⅱ) ion. The electronic spectra calculations show that there exist two absorption bands and the electronic transitions are mainly derived from the contribution of intraligand π→π^* transition and ligand-to-metal charge transfer (LMCT) transition. The thermodynamic properties of the title compound at different temperatures have been calculated and corresponding relations between property and temperature have also been obtained. The calculation of the second order optical nonlinearity was carried out, and the molecular hyperpolarizability was 3.62365^*10^-30 esu.展开更多
文摘The theoretical calculation of LaNi4Co, in which Co substituted for Ni at various sites, was performed by adopting the method of total energy based on the Density Functional Theory. The augmented plane wave function was selected as a basis set in combination with Ultra-soft Pseudopotential technology. The geometry of LaNi5 was optimized and the parameters and properties of the structure were given. The theoretical results accord well with experiments. This method provides a theoretical approach for the structure prediction of such alloy. The calculations of total energy, electronic density of states and Mulliken population of LaNi4Co were carried out. The electronic structure of LaNi4Co and the change of the electronic structure due to the Co-substitution in LaNi5 alloy were analyzed from the calculated results. The stability of the alloy in which Ni was partially substituted by Co at various sites was compared and the factors controlling stability were discussed. The theoretical value of formation heat was calculated.
基金This work was supported by the National Natural Science Foundation of China (No.51063006 and No.50975273) and the "QingLan" Talent Engineering Funds of Tianshui Normal University.
文摘Inverse halogen bonds interactions involving Br in the electronic deficiency systems of CH3+...Br-Y (Y=H, CCH, CN, NC) have been investigated by B3LYP/6- 311++G(d, p) and MP2/6-311++G(d, p) methods. The calculated interaction energies with basis set super-position error correction of the four IXBs complexes are 218.87, 219.48, 159.18, and 143.05kJ/mol (MP2/6-311++G(d, p)), respectively. The relative stabilities of the four complexes increased in the order: CH3+ … BrCN〈CH3+…- BrNC〈CH3+… BrH≈CH3+ …BrCCH. Natural bond orbital theory analysis and the chemical shifts calculation of the related atoms revealed that the charges flow from Br-Y to CH3e. Here, the Br of Br-Y acts as both a halogen bond donor and an electron donor. Therefore, compared with conventional halogen bonds, the IXBs complexes formed between Br-Y and CH3+. Atoms-in-molecules theory has been used to investigate the topological properties of the critical points of the four IXBs structures which have more covalent content.
基金supported by the National Natural Science Foundation of China (No. 20407004, 50578012, 50178009)the High-Tech Research and Development Program (863) of China (No. 2007AA06Z301)+2 种基金the Fok Ying Tung Education Foundation of National Education Ministry of China (No. 91078)the Beijing Municipal Commission of Education Project, Program for New Cen- tury Excellent Talents in University (No. NCET-06-0120)the Beijing Nova of Science and Technology, Beijing Key Subject (No. XK100220555).
文摘The fractal dimensions in different topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating different kinds of humic acids (HA) water at different initial pH (9.0, 7.0, 5.0) and PFC dosages, were calculated by effective densitymaximum diameter, image analysis, and N2 absorption-desorption methods, respectively. The mass fractal dimensions (De) of PFC-HA floes were calculated by bi-logarithm relation of effective density with maximum diameter and Logan empirical equation. The Df value was more than 2.0 at initial pH of 7,0, which was 11% and 13% higher than those at pH 9.0 and 5.0, respecively, indicating the most compact flocs formed in flocculated HA water at initial pH of 7.0. The image analysis for those flocs indicates that after flocculating the HA water at initial pH greater than 7.0 with PFC flocculant, the fractal dimensions of D2 (logA vs. logdL) and D3 (logVsphere vs. logdL) of PFC-HA floes decreased with the increase of PFC dosages, and PFC-HA floes showed a gradually looser structure. At the optimum dosage of PFC, the D2 (logA vs. logdL) values of the flocs show 14%-43% difference with their corresponding Dr, and they even had different tendency with the change of initial pH values. However, the D2 values of the floes formed at three different initial pH in HA solution had a same tendency with the corresponding Df. Based on fractal Frenkel-Halsey-HiU (FHH) adsorption and desorption equations, the pore surface fractal dimensions (Ds) for dried powders of PFC-HA flocs formed in HA water with initial pH 9.0 and 7.0 were all close to 2.9421, and the Ds values of flocs formed at initial pH 5.0 were less than 2.3746. It indicated that the pore surface fractal dimensions of PFC-HA floes dried powder mainly show the irregularity from the mesopore-size distribution and marcopore-size distribution.
基金supported in part by China intelligent robot project of firm-universities cooperative R&D under Grant No.2021JQR021the Anhui Provincial Teaching Demonstration Course Project under Grant No.2020SJJXSFK0330+9 种基金the demonstration experiment training center project of Anhui Polytechnic University under Grant No.2020sysx02the Overseas Visiting and Research Project for Outstanding Young Backbone Talents in Universities of Anhui Province under Grant No.gxgwfx2019041the Innovation Project for Returned Overseas Students in Anhui Province under Grant No.2020LCX013Key Research and Development Projects of Anhui Province under Grant No.202004b11020006Scientific Research Foundation of Anhui Polytechnic University under Grant No.2020YQQ010Anhui Polytechnic University Research Initiation Fund for Introducing Talents under Grant No.2019YQQ004Anhui Polytechnic University Research Project under Grant No.Xjky019201905Industrial Collaborative Innovation Fund of Anhui Polytechnic University and Jiujiang District under Grant No.2021cyxtb9Open Project of Anhui Provincial Engineering Laboratory on Information Fusion and Control of Intelligent Robot under Grant No.IFCIR2020001Open project of Key Laboratory of industrial equipment quality big data Ministry of industry and information technology under Grant No.2021-IEQBD-05.
文摘In order to solve the problems of too large mass,too complex structure and poor flexibility of the 6 DOF manipulator,the topological optimization theory based on variable density method is applied to the 6-DOF manipulator,the topology optimization of the main structural components of the manipulator is carried out with the help of the finite element software ANSYS,and the optimized structure is simplified according to the density distribution of the units and the requirements of manufacturability.the results are compared and analysed by static mechanics.It shows that the whole mass of the 6-DOF manipulator is reduced by 47.23%without changing the original mechanical properties after topological optimization,and the optimized model can meet the requirements of manufacturability,the optimization effect is signifcant,which can be used as a reference for the structure optimization of the 6-DOF manipulator.
基金supported partially by the Framework of CALSIMLAB under the Public Grant ANR-11-LABX-0037-01 Overseen by the French National Research Agency(ANR) as Part of the "Investissements d’Avenir" Program(reference:ANR-11-IDEX-0004-02)the National Science Foundation(CHE-1362927)the National Institute of Health(R01-GM061870),USA
文摘In this perspective,we review the chemical information encoded in electron density and other ingredients used in semilocal functionals.This information is usually looked at from the functional point of view:the exchange density or the enhancement factor are discussed in terms of the reduced density gradient.However,what parts of a molecule do these 3D functions represent? We look atthese quantities in real space,aiming to understand the electronic structure information they encode and provide an insight from the quantum chemical topology(QCT).Generalized gradient approximations(GGAs) provide information about the presence of chemical interactions,whereas meta-GGAs can differentiate between the different bonding types.By merging these two techniques,we show new insight into the failures of semilocal functionals owing to three main errors:fractional charges,fractional spins,and non-covalent interactions.We build on simple models.We also analyze the delocalization error in hydrogen chains,showing the ability of QCT to reveal the delocalization error introduced by semilocal functionals.Then,we show how the analysis of localization can help understand the fractional spin error in alkali atoms,and how it can be used to correct it.Finally,we show that the poor description of GGAs of isodesmic reactions in alkanes is due to 1,3-interactions.
文摘The thermodynamic properties of dibenzofurans (DFs), xanthones (XTs) and an-thraquinones (AQs) with one and two positions substituted with hydroxyls in the ideal gas state at 298.15 K and 1.013×10^5 pa were calculated at the B3LYP/6-311G^* level using Gaussian 03 program. The isodesmic reactions were designed to calculate the standard free energy of formation (△fG^θ). Three types of hydrogen bonds exist in the three kinds of chemicals and their bond energies were ascertained as 7-15, 15-23 and 49-58 kJ·mo1^-1 respectively by comparing the △fG^θ values. Electronic density topology analysis was applied to validate the strength of bond.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11547051 and 11274018)
文摘We study the electronic band structure, density distribution, and transport of a Bi2Se3 nanoribbon, We find that the density distribution of the surface states is dependent on not only the shape and size of the transverse cross section of the nanoribbon, but also the energy of the electron. We demonstrate that a transverse electric field can eliminate the coupling between surface states on the walls of the nanoribbon, remove the gap of the surface states, and restore the quantum spin Hall effects. In addition, we study the spin-dependent transport property of the surface states transmitting from top and bottom surfaces (x-y plane) to the side surfaces (z-x plane) of a Bi2Se3 nanoribbon. We find that transverse electric fields can open two surface channels for spin-up and -down Dirac electrons, and then switch off one channel for the spin-up Dirac electron. Our results may provide a simple way for the design of a spin filter based on topological insulator nanostructures.
基金Supported by the National Natural Science Foundation of China(20873103)
文摘In this research, the hydrogen bonds Y···H-X (X = C, N; Y = N, O) of thymine and uracil have been theoretically studied. The results show that hydrogen bond leads to bond length elongation and stretches the frequency red-shift of N-H···Y. Meanwhile, the C-H···O bonds shorten and stretch the frequency blue-shift. They all belong to traditional hydrogen bonds. The intermolecular charge transfer caused by the intermolecular hyperconjugation s*(N–H) → n(Y) and intramolecular charge redistribution by intramolecular hyperconjugation σ(C-H) →σ*(C-N) play important roles in the formation of hydrogen bonds. According to thejudgment standards proposed by Bader and Popelier, these hydrogen bonds have typical electron density topological properties. Electrostatic surface potential (ESP) is a useful physicochemical property of a molecule that provides insights into inter- and intramolecular associations, as well as the prediction of likely sites of electrophilic and nucleophilic metabolic attack.
基金This work was supported by the National Natural Science Foundation of China (No.20573032),the Natural Science Foundation of Hebei Province (No.B2006000137), the Education Department Foundation of Hebei Province (No.2007123), and the Doctoral Foundation of Hebei Normal University (No.L2005B12).
文摘The reaction of CH2SH radical with fluorine atom was studied at the levels of B3LYP/6-311G(d,p) and MP2(Full)/6-311G(d,p). The computational results show that the reaction has three channels and proceeds by the addition of fluorine atoms on carbon or sulfur sites of CH2SH, forming initial intermediates. The calculated results show that the channel, in which fluorine attaches to the carbon atom to form CH2S and HF, is the most likely reaction pathway. Topological analysis of electron density was carried out for the three channels. The change trends of the chemical bonds on the reaction paths were discussed. The energy transition states and the structure transition regions (states) of the three channels were found. The calculated results show that the structure transition regions are broad in unobvious exothermic reactions or unobvious endothermic reactions, and are narrow in obvious exothermic reactions or obvious endothermic reactions.
基金supported by National Natural Science Foundation of China(No.12175050)。
文摘Plasma photonic crystals designed in this paper are composed of gas discharge tubes to control the flow of electromagnetic waves.The band structures calculated by the finite element method are consistent with the experimental results which have two distinct attenuation peaks in the ranges of 1-2.5 GHz and 5-6 GHz.Electromagnetic parameters of the plasma are extracted by the Nicolson-Ross-Weir method and effective medium theory.The measured electron density is between 1×1011 cm-3 and1×1012 cm-3,which verifies the correctness of the parameter used in the simulation,and the collision frequency is near 1.5×1010 Hz.As the band structures are corroborated by the measured scattering parameters,we introduce the concept of photonic topological insulator based on the quantum Valley Hall effect into the plasma photonic crystal.A valley-dependent plasma photonic crystal with hexagonal lattice is constructed,and the phase transition of the valley K(K’)occurs by breaking the spatial inversion symmetry.Valley-spin locked topological edge states are generated and excited by chiral sources.The frequency of the non-bulk state can be dynamically regulated by the electron density.This concept paves the way for novel,tunable topological edge states.More interestingly,the Dirac cone is broken when the electron density increases to 3.1×1012 cm-3,which distinguishes from the methods of applying a magnetic field and changing the symmetry of the point group.
基金supported by the Foundation Study Fund of Tangshan Normal College (No.07C22)Education Committee Fund of Hebei Province (No.Z2007204,No.Z2007205)+1 种基金Application Foundation Study Fund of Tangshan City (No.06234501A-10)Science Study Fund of Tangshan Normal College (No.06D08)
文摘The geometries,electronic structure,IR spectrum and other properties of hydrogen interaction between 5-fluorouracil and glycine were studied at the B3LYP/6-31+G* level.Single point energy calculations were executed at the B3LYP/6-311++G** and B3LYP/aug-cc-pvdz levels,and natural bond orbital (NBO) analysis was carried out at the B3LYP/6-31+G* level.Finally,the hydrogen bonds were discussed via AIM electronic density topology analysis.
基金supported by the Natural Science Foundation of Hebei Province,No. C2007000921
文摘In this study, we investigated the effects of mobile phone radiation on spatial learning, reference memory, and morphology in related brain regions. After the near-field radiation (0.52 1.08 W/kg) was delivered to 8-week-old Wistar rats 2 hours per day for 1 month, behavioral changes were examined using the Morris water maze. Compared with the sham-irradiated rats, the irradiated rats exhibited impaired performance. Morphological changes were investigated by examining synaptic ultrastructural changes in the hippocampus. Using the physical dissector technique, the number of pyramidal neurons, the synaptic profiles, and the length of postsynaptic densities in the CA1 region were quantified stereologically. The morphological changes included mitochondrial degenerations, fewer synapses, and shorter postsynaptic densities in the radiated rats. These findings indicate that mobile phone radiation can significantly impair spatial learning and reference memory and induce morphological changes in the hippocampal CA1 region.
基金This work was supported by the Natural Science Foundation of Shandong Province (No. Y2002B06)
文摘The title compound of isonicotinato lead(Ⅱ) [Pb(C5H4NCOO)2] has been optimized at B3LYP/LANL2DZ level of theory and calculated results show that the lead(Ⅱ) ion adopts 4-coordinate geometry. Atomic charge distributions indicate that during forming the title compound, each isonicotinic acid ion transfers -0.452 e to lead(Ⅱ) ion. The electronic spectra calculations show that there exist two absorption bands and the electronic transitions are mainly derived from the contribution of intraligand π→π^* transition and ligand-to-metal charge transfer (LMCT) transition. The thermodynamic properties of the title compound at different temperatures have been calculated and corresponding relations between property and temperature have also been obtained. The calculation of the second order optical nonlinearity was carried out, and the molecular hyperpolarizability was 3.62365^*10^-30 esu.