Micro/nanostructured crystals with controlled architectures are desirable for many applications in optics, electronics, biology, medicine, and energy conversions. Low-temperature, aqueous chemical routes have been wid...Micro/nanostructured crystals with controlled architectures are desirable for many applications in optics, electronics, biology, medicine, and energy conversions. Low-temperature, aqueous chemical routes have been widely investigated for the synthesis of particles, and arrays of oriented nanorods and nanotubes. In this paper, based on the ideal crystal shapes predicted by the chemical bonding theory, we have developed some potential chemical strategies to tune the microstructure of functional materials, ZnS and Nb205 nanotube arrays, MgO wiskers and nestlike spheres, and cubic phase Cu2O microcrystals were synthesized here to elucidate these strategies. We describe their controlled crystallization processes and illustrate the detailed key factors controlling their growth by examining various reaction parameters. Current results demonstrate that our designed chemical strategies for tuning microstructure of functional materials are applicable to several technologically important materials, and therefore may be used as a versatile and effective route to the controllable synthesis of other inorganic functional materials.展开更多
The molecular geometries and dissociation energies of AnO (An = Bk–Lr) molecules were first obtained at thecoupled-cluster single-, double-, and perturbative triple-excitations [CCSD(T)] level of theory. Four hybrid ...The molecular geometries and dissociation energies of AnO (An = Bk–Lr) molecules were first obtained at thecoupled-cluster single-, double-, and perturbative triple-excitations [CCSD(T)] level of theory. Four hybrid functionals,B3LYP, M06-2X, TPSSh, and PBE0, were also employed in the calculations for the sake of comparison. In comparison ofthe CCSD(T) results, B3LYP, TPSSh, and PBE0 functionals can obtain more appropriate results than M06-2X and MP2.The analyses on molecular orbitals show that the 7s, 6d, and 5f atomic orbitals of actinide (An) atoms participate in thebonding of An–O bonds. The partial covalent nature between An and O atoms is revealed by QTAIM analyses.展开更多
The interfacial defects and energy barrier are main reasons for interfacial nonradiative recombination.In addition,poor perovskite crystallization and incomplete conversion of PbI_(2) to perovskite restrict further en...The interfacial defects and energy barrier are main reasons for interfacial nonradiative recombination.In addition,poor perovskite crystallization and incomplete conversion of PbI_(2) to perovskite restrict further enhancement of the photovoltaic performance of the devices using sequential deposition.Herein,a buried interface stabilization strategy that relies on the synergy of fluorine(F)and sulfonyl(S=O)functional groups is proposed.A series of potassium salts containing halide and non-halogen anions are employed to modify SnO_(2)/perovskite buried interface.Multiple chemical bonds including hydrogen bond,coordination bond and ionic bond are realized,which strengthens interfacial contact and defect passivation effect.The chemical interaction between modification molecules and perovskite along with SnO_(2) heightens incessantly as the number of S=O and F augments.The chemical interaction strength between modifiers and perovskite as well as SnO_(2) gradually increases with the increase in the number of S=O and F.The defect passivation effect is positively correlated with the chemical interaction strength.The crystallization kinetics is regulated through the compromise between chemical interaction strength and wettability of substrates.Compared with Cl−,all non-halogen anions perform better in crystallization optimization,energy band regulation and defect passivation.The device with potassium bis(fluorosulfonyl)imide achieves a tempting efficiency of 24.17%.展开更多
Density functional theory（DFT） and coupled cluster theory（CCSD（T）） calculations were employed to investigate the structural and electronic properties of Nb S6^- and Nb S6 clusters. Generalized Koopmans＇ theorem...Density functional theory（DFT） and coupled cluster theory（CCSD（T）） calculations were employed to investigate the structural and electronic properties of Nb S6^- and Nb S6 clusters. Generalized Koopmans＇ theorem was applied to predict the vertical detachment energies and simulate the photoelectron spectra（PES）. The current study indicated that various types of sulfur ligands（i.e., S^（2-）, S^（2-）, S2^（2-） and S3^（2-）） were presented in the lowest-energy structures of Nb S6^（-/0）. The ground-state structure of Nb S6^- is shown to be Cs（~1A＇） symmetry with a terminal S^（2-）, a side-on bound S2^（2-） and a S3^（2-） ligands. Molecular orbital analyses were performed to analyze the chemical bonding in NbS6^（-/0） clusters and elucidate their structural and electronic properties.展开更多
Chemical bond parameters, that is, bond covalency, bond valence, macroscopic linear susceptibility, and oxidation states of elements in Sr3MRhO6(M-Sm, Eu, Tb, Dy, Ho, Er, Yb) have been calculated. The results indicat...Chemical bond parameters, that is, bond covalency, bond valence, macroscopic linear susceptibility, and oxidation states of elements in Sr3MRhO6(M-Sm, Eu, Tb, Dy, Ho, Er, Yb) have been calculated. The results indicate that the bond covalency of M-O decreases sharply with the decrease of ionic radius of M3+ from Sm to Yb, while no obvious trend has been found for Rh-O and Sr-O bonds. The global instability index indicates that the crystal structures of Sr3MrhO6(M=Sm, Eu, Tb, Dy, Ho) have strained bonds.展开更多
Steady-state absorption and fluorescence spectra, and time-resolved fluorescence spectra of coumarin 343 （C343） were measured in different solvents. The effect of the solvent on the spectral properties and dipole mo...Steady-state absorption and fluorescence spectra, and time-resolved fluorescence spectra of coumarin 343 （C343） were measured in different solvents. The effect of the solvent on the spectral properties and dipole moment of the lowest excited state of C343 were investigated. It was found that the absorption and fluorescence spectra red-shifted slightly and strongly with increasing solvent polarity, respectively, because the charge distribution of the excited state leaded to the increasing difference between the absorption and fluorescence spectra with increasing solvent polarity. The dipole moment of the lowest excited state of C343 was determined from solvatochromic measurements and the quantum chemical calculation, and the results obtained from these two methods were fully consistent. Investigations of the time-resolved fluorescence of C343 in different solvents indicated that the fluorescence lifetimes increased nearly linearly with 4.45 ns in water. This can be ascribed between C343 and hydrogen donating increasing solvent polarity from 3.09 ns in toluene to to the intermolecular hydrogen bonding interactions solvents展开更多
Using ab initio density functional theory calculations, the electron localization function (ELF) of typical transition metal carbide TiC and nitride TiN were computed and analyzed to reveal their nature of the chemica...Using ab initio density functional theory calculations, the electron localization function (ELF) of typical transition metal carbide TiC and nitride TiN were computed and analyzed to reveal their nature of the chemical bonds. The ELF approach was initially validated through typical examples of covalent-bonding Diamond (C) and ionic-bonding sodium chloride NaCl. Our results clearly demonstrate the dominantly ionic bonding characteristics of TiC and TiN. It is also suggested that the high mechanical hardness of TiC and TiN can be explained without evoking strong covalence.展开更多
The lowest total energy crystal structure of Li2MgN2H2 was identified by the first principle calculation with RPBE exchange-correlation function. Furthermore, the fine structure parameters of this crystal structure we...The lowest total energy crystal structure of Li2MgN2H2 was identified by the first principle calculation with RPBE exchange-correlation function. Furthermore, the fine structure parameters of this crystal structure were calculated with PBE and PW91 exchange-correlation function. In a further step, the density of states, electron density, charge density difference on (0 0 1) plane and heat of formation of Li2MgN2H2 hydrogenation were computed with PW91 exchange-correlation function. Consequently, the electronic structures and chemical bonds in this compound were analyzed and discussed, and then the thermodynamic character of Li2MgN2H2 for hydrogen storage was evacuated.展开更多
The results of an expert system of lanthanide intermetallic compounds using artificial neural networks and chemical bond parameter method were reported. Two pattern recognition neural models, one for prediction of the...The results of an expert system of lanthanide intermetallic compounds using artificial neural networks and chemical bond parameter method were reported. Two pattern recognition neural models, one for prediction of the occurrence of 1 : 1 lanthanide intermetallic compounds with CsClstructure and the other for prediction of congruent or incongruent melting types, were developed. Four regression neural models were also developed for prediction of melting point of these compounds. In order to get rid of overfitting, cross-vahdation method was used for the neural models. And satisfactory results were obtained in all of the neural models in this paper.展开更多
The partial replacement of durum wheat semolina with local flours such as soybeans and yam reduces the dependence of durum wheat semolina for the production of pasta</span><span style="font-family:Verdan...The partial replacement of durum wheat semolina with local flours such as soybeans and yam reduces the dependence of durum wheat semolina for the production of pasta</span><span style="font-family:Verdana;">.</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">The</span><span style="font-family:""><span style="font-family:Verdana;"> main objective of this study is to develop yam flour (A) from Dioscorea alata in the manufacture of pasta made with durum wheat semolina (B) and soy flour (C) (raw materials). The methodology adopted consists first of all in the characterization of yam, soybean </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> durum wheat semolina. An experimental design was developed to bring out the balanced mixing plan in well-defined proportions with ten (10) tests. Chemical and functional analyzes were carried out on the pastes obtained from these formulations. The functional properties allowed us to determine the optimal mixing plan using a mathematical model. The sensory properties of the optimal compound dough were estimated in comparison with the control doughs. The results on the chemical properties of raw materials A, B </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> C obtained on the water content vary from 10.29% to 12.29%;those of ashes vary from 0.91% to 5.74% and those of proteins vary from 3.24% to 20.17%. The results of the chemical and functional parameters of compound pasta gave very diverse values. We find that the water content, the ash content, the protein content </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> the acidity rate of the series of 10 tests are respectively from 6.60% to 14.97%, from 0.97% to 1.67%, from 7.15% to 12.10% </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> from 1.35% to 3.60%. Regarding the optimal cooking time for this series of 10 tests, it varies from 15 min to 20 min with a swelling index which is between 59.70% and 107.12%. Statistical tests (test F) from the different models indicate that the main regression effects are not significant with a p-value probability greater than 0.05. The models obtained were significant with a good value for the coefficient of determination R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">. The sensory test approved that optimal compound pasta has good overall acceptability compared to 100% durum wheat pasta. The 20.40% yam flour mixture (102.020 g);55.19% of durum wheat semolina (275.982 g) and 24.39% of soy flour (121.998 g) has good potential in the preparation of compound pasta.展开更多
The artificial neural network method is utilized to study the correlation between the overall hydrogen- bond basicity ( ) values of 231 diverse compounds and their quantum chemical parameters. There are nonlinear rela...The artificial neural network method is utilized to study the correlation between the overall hydrogen- bond basicity ( ) values of 231 diverse compounds and their quantum chemical parameters. There are nonlinear relationships of the values with the quantum chemical parameters. The BP neural networks can predict the values when the neural units of the input layers are the quantum chemical parameters. The structures of the BP neural networks or the quantum chemical parameters are different when the compounds belong to different classes.展开更多
基金the financial support of the program for the New Century Excellent Talents in University(Grant No.NCET-05-0278)the National Natural Science Foundation of China(Grant No.20471012)+1 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No.200322)the Research Fund for the Doctoral Program of Higher Education(Grant No.20040141004).
文摘Micro/nanostructured crystals with controlled architectures are desirable for many applications in optics, electronics, biology, medicine, and energy conversions. Low-temperature, aqueous chemical routes have been widely investigated for the synthesis of particles, and arrays of oriented nanorods and nanotubes. In this paper, based on the ideal crystal shapes predicted by the chemical bonding theory, we have developed some potential chemical strategies to tune the microstructure of functional materials, ZnS and Nb205 nanotube arrays, MgO wiskers and nestlike spheres, and cubic phase Cu2O microcrystals were synthesized here to elucidate these strategies. We describe their controlled crystallization processes and illustrate the detailed key factors controlling their growth by examining various reaction parameters. Current results demonstrate that our designed chemical strategies for tuning microstructure of functional materials are applicable to several technologically important materials, and therefore may be used as a versatile and effective route to the controllable synthesis of other inorganic functional materials.
基金Project supported by the Education Department in Sichuan Province,China(Grant No.15ZB0006).
文摘The molecular geometries and dissociation energies of AnO (An = Bk–Lr) molecules were first obtained at thecoupled-cluster single-, double-, and perturbative triple-excitations [CCSD(T)] level of theory. Four hybrid functionals,B3LYP, M06-2X, TPSSh, and PBE0, were also employed in the calculations for the sake of comparison. In comparison ofthe CCSD(T) results, B3LYP, TPSSh, and PBE0 functionals can obtain more appropriate results than M06-2X and MP2.The analyses on molecular orbitals show that the 7s, 6d, and 5f atomic orbitals of actinide (An) atoms participate in thebonding of An–O bonds. The partial covalent nature between An and O atoms is revealed by QTAIM analyses.
基金supported by the Defense Industrial Technology Development Program(JCKY2017110C0654)National Natural Science Foundation of China(11974063,61904023,62274018)+1 种基金Chongqing Special Postdoctoral Science Foundation(cstc2019jcyj-bsh0026)Fundamental Research Funds for the Central Universities(2021CDJQY-022).
文摘The interfacial defects and energy barrier are main reasons for interfacial nonradiative recombination.In addition,poor perovskite crystallization and incomplete conversion of PbI_(2) to perovskite restrict further enhancement of the photovoltaic performance of the devices using sequential deposition.Herein,a buried interface stabilization strategy that relies on the synergy of fluorine(F)and sulfonyl(S=O)functional groups is proposed.A series of potassium salts containing halide and non-halogen anions are employed to modify SnO_(2)/perovskite buried interface.Multiple chemical bonds including hydrogen bond,coordination bond and ionic bond are realized,which strengthens interfacial contact and defect passivation effect.The chemical interaction between modification molecules and perovskite along with SnO_(2) heightens incessantly as the number of S=O and F augments.The chemical interaction strength between modifiers and perovskite as well as SnO_(2) gradually increases with the increase in the number of S=O and F.The defect passivation effect is positively correlated with the chemical interaction strength.The crystallization kinetics is regulated through the compromise between chemical interaction strength and wettability of substrates.Compared with Cl−,all non-halogen anions perform better in crystallization optimization,energy band regulation and defect passivation.The device with potassium bis(fluorosulfonyl)imide achieves a tempting efficiency of 24.17%.
基金supported by the National Natural Science Foundation of China(21301030,21371034 and 21373048)the Natural Science Foundation of Fujian Province for Distinguished Young Investigator(2013J06004)Foundation of Fuzhou University(2012-XY-6)
文摘Density functional theory（DFT） and coupled cluster theory（CCSD（T）） calculations were employed to investigate the structural and electronic properties of Nb S6^- and Nb S6 clusters. Generalized Koopmans＇ theorem was applied to predict the vertical detachment energies and simulate the photoelectron spectra（PES）. The current study indicated that various types of sulfur ligands（i.e., S^（2-）, S^（2-）, S2^（2-） and S3^（2-）） were presented in the lowest-energy structures of Nb S6^（-/0）. The ground-state structure of Nb S6^- is shown to be Cs（~1A＇） symmetry with a terminal S^（2-）, a side-on bound S2^（2-） and a S3^（2-） ligands. Molecular orbital analyses were performed to analyze the chemical bonding in NbS6^（-/0） clusters and elucidate their structural and electronic properties.
文摘Chemical bond parameters, that is, bond covalency, bond valence, macroscopic linear susceptibility, and oxidation states of elements in Sr3MRhO6(M-Sm, Eu, Tb, Dy, Ho, Er, Yb) have been calculated. The results indicate that the bond covalency of M-O decreases sharply with the decrease of ionic radius of M3+ from Sm to Yb, while no obvious trend has been found for Rh-O and Sr-O bonds. The global instability index indicates that the crystal structures of Sr3MrhO6(M=Sm, Eu, Tb, Dy, Ho) have strained bonds.
文摘Steady-state absorption and fluorescence spectra, and time-resolved fluorescence spectra of coumarin 343 （C343） were measured in different solvents. The effect of the solvent on the spectral properties and dipole moment of the lowest excited state of C343 were investigated. It was found that the absorption and fluorescence spectra red-shifted slightly and strongly with increasing solvent polarity, respectively, because the charge distribution of the excited state leaded to the increasing difference between the absorption and fluorescence spectra with increasing solvent polarity. The dipole moment of the lowest excited state of C343 was determined from solvatochromic measurements and the quantum chemical calculation, and the results obtained from these two methods were fully consistent. Investigations of the time-resolved fluorescence of C343 in different solvents indicated that the fluorescence lifetimes increased nearly linearly with 4.45 ns in water. This can be ascribed between C343 and hydrogen donating increasing solvent polarity from 3.09 ns in toluene to to the intermolecular hydrogen bonding interactions solvents
文摘Using ab initio density functional theory calculations, the electron localization function (ELF) of typical transition metal carbide TiC and nitride TiN were computed and analyzed to reveal their nature of the chemical bonds. The ELF approach was initially validated through typical examples of covalent-bonding Diamond (C) and ionic-bonding sodium chloride NaCl. Our results clearly demonstrate the dominantly ionic bonding characteristics of TiC and TiN. It is also suggested that the high mechanical hardness of TiC and TiN can be explained without evoking strong covalence.
文摘The lowest total energy crystal structure of Li2MgN2H2 was identified by the first principle calculation with RPBE exchange-correlation function. Furthermore, the fine structure parameters of this crystal structure were calculated with PBE and PW91 exchange-correlation function. In a further step, the density of states, electron density, charge density difference on (0 0 1) plane and heat of formation of Li2MgN2H2 hydrogenation were computed with PW91 exchange-correlation function. Consequently, the electronic structures and chemical bonds in this compound were analyzed and discussed, and then the thermodynamic character of Li2MgN2H2 for hydrogen storage was evacuated.
文摘The results of an expert system of lanthanide intermetallic compounds using artificial neural networks and chemical bond parameter method were reported. Two pattern recognition neural models, one for prediction of the occurrence of 1 : 1 lanthanide intermetallic compounds with CsClstructure and the other for prediction of congruent or incongruent melting types, were developed. Four regression neural models were also developed for prediction of melting point of these compounds. In order to get rid of overfitting, cross-vahdation method was used for the neural models. And satisfactory results were obtained in all of the neural models in this paper.
文摘The partial replacement of durum wheat semolina with local flours such as soybeans and yam reduces the dependence of durum wheat semolina for the production of pasta</span><span style="font-family:Verdana;">.</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">The</span><span style="font-family:""><span style="font-family:Verdana;"> main objective of this study is to develop yam flour (A) from Dioscorea alata in the manufacture of pasta made with durum wheat semolina (B) and soy flour (C) (raw materials). The methodology adopted consists first of all in the characterization of yam, soybean </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> durum wheat semolina. An experimental design was developed to bring out the balanced mixing plan in well-defined proportions with ten (10) tests. Chemical and functional analyzes were carried out on the pastes obtained from these formulations. The functional properties allowed us to determine the optimal mixing plan using a mathematical model. The sensory properties of the optimal compound dough were estimated in comparison with the control doughs. The results on the chemical properties of raw materials A, B </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> C obtained on the water content vary from 10.29% to 12.29%;those of ashes vary from 0.91% to 5.74% and those of proteins vary from 3.24% to 20.17%. The results of the chemical and functional parameters of compound pasta gave very diverse values. We find that the water content, the ash content, the protein content </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> the acidity rate of the series of 10 tests are respectively from 6.60% to 14.97%, from 0.97% to 1.67%, from 7.15% to 12.10% </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> from 1.35% to 3.60%. Regarding the optimal cooking time for this series of 10 tests, it varies from 15 min to 20 min with a swelling index which is between 59.70% and 107.12%. Statistical tests (test F) from the different models indicate that the main regression effects are not significant with a p-value probability greater than 0.05. The models obtained were significant with a good value for the coefficient of determination R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">. The sensory test approved that optimal compound pasta has good overall acceptability compared to 100% durum wheat pasta. The 20.40% yam flour mixture (102.020 g);55.19% of durum wheat semolina (275.982 g) and 24.39% of soy flour (121.998 g) has good potential in the preparation of compound pasta.
文摘The artificial neural network method is utilized to study the correlation between the overall hydrogen- bond basicity ( ) values of 231 diverse compounds and their quantum chemical parameters. There are nonlinear relationships of the values with the quantum chemical parameters. The BP neural networks can predict the values when the neural units of the input layers are the quantum chemical parameters. The structures of the BP neural networks or the quantum chemical parameters are different when the compounds belong to different classes.
