The NO2 molecule adsorption on B12N12 nano-cage was investigated using density functional theory calculations in terms of adsorption energy, HOMO/LUMO energy gap （Eg） changes, charge transfer, structural deformation...The NO2 molecule adsorption on B12N12 nano-cage was investigated using density functional theory calculations in terms of adsorption energy, HOMO/LUMO energy gap （Eg） changes, charge transfer, structural deformation, etc. Furthermore, some aspects of stability and properties of B12N12 including calculation of binding electronic and Gibbs free energies, density of states, and molecular electrostatic potential surfaces are investigated. Three possible configurations for NO2 adsorption on the B12N12 nano-cage are energetically found. Interestingly, the results reveals that the Eg of B12N12 cluster is very sensitive to the pres- ence of NO2 molecules as its value reduces from 6.84 eV in free cluster to 3.23 eV in the most stable configuration of NO2/cluster complex. This phenomenon dramatically increases the electrical conductivity of the cluster, suggesting that the B12N12 nano-cluster may be potential sensor for NO2 gaseous molecule detection.展开更多
Using density functional theory （DFT）, the thermodynamic parameters of the CO2 absorp-tion into the aqueous solution of the aliphatic amines including some alkylamines, alka-nolamines, diamines and a type of aminoam...Using density functional theory （DFT）, the thermodynamic parameters of the CO2 absorp-tion into the aqueous solution of the aliphatic amines including some alkylamines, alka-nolamines, diamines and a type of aminoamide were calculated. The geometry optimiza-tion and the calculation of vibrational frequencies in the gas phase were performed at the B3LYP/6-311＋ G（d,p） level of theory. Moreover, the standard solvation free energies of the studied species were computed upon the solution phase optimized geometries through the latest continuum solvation model （SMD/IEF-PCM） at the HF/6-31G（d） level of theory. With this approach, two important properties of the CO2 absorption into the aqueous so-lutions of the studied amines were evaluated： the acid dissociation constant （pKa） of the parent amines and the standard enthalpy change （ΔH^φabs） related to the CO2 absorption process. A roughly linear relationship was observed between pKa and ΔH^φabs. This finding suggests that a raise in the basicity of an amine leads to an increase in the heat released in CO2 absorption and consequently in the required energy for the regeneration of amine.展开更多
Density functional theory calculations are performed to study the structural, electronic and magnetic properties of hexagonal NiAs type and cubic zinc blende type MnSb structure and interface of zinc blende MnSb with ...Density functional theory calculations are performed to study the structural, electronic and magnetic properties of hexagonal NiAs type and cubic zinc blende type MnSb structure and interface of zinc blende MnSb with GaSb（001）. We used generalized gradiant approximation to calculate the exchange-correlation term in bulk and interface determination. The zinc blende structure of MnSb is found to be ferromagnetic half-metal with a total moment of 4 μB per formula unit. Results show that the half-metallicity character is preserved at MnSb/GaSb（001） interface. The magnetic moment of Mn atom in interface is reduced and the magnetic moment of the interface Sb atom is equal to the average of the corresponding bulk values in two sides of the interface. The band alignment properties are also computed and a rather large minority valance band offset of about 1.25 eV is obtained in this heterojunction.展开更多
We have performed a comparative theoretical study on the adsorption of nitric oxide （NO） on Zn12012 and Mgt2012 nanocages in terms of their energetic, geometric, and electronic properties. It has been found that NO ...We have performed a comparative theoretical study on the adsorption of nitric oxide （NO） on Zn12012 and Mgt2012 nanocages in terms of their energetic, geometric, and electronic properties. It has been found that NO adsorption on the MgO nanocage is energetically more favorable than that on the ZnO one. In contrast to the ZnO nanocage, HOMO-LUMO energy gap （Eg） of MgO one is dramatically decreased in the presence of NO molecule so that it is transformed from an intrinsic semiconductor （Eg≈5.00 eV） to a p-type one （Eg≈1.93 eV）. We have predicted that electronic and conductance properties of the Mg12012 nanocage are sensitive toward NO molecule, thus it may be potential candidate in detection of NO molecules.展开更多
The mechanism and regioselectivity of 1,3-dipolar cycloaddition of N-[methyl]-C-[5-nitro-2-furyl] nitrilimine with dimethyl 7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate were investigated using activation energ...The mechanism and regioselectivity of 1,3-dipolar cycloaddition of N-[methyl]-C-[5-nitro-2-furyl] nitrilimine with dimethyl 7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate were investigated using activation energy calculations and density functional theory-based reactivity indexes. The reaction proceeds by an asynchronous concerted mechanism. The calculations are performed at the B3LYP/6-31G（d） level of theory and the obtained results are in agreement with experimental outcome.展开更多
The ability to employ the language as a communicational tool often serves as a measure of one＇s speaking success in the language learning class. This research sought to investigate the effect of learners＇ autonomous...The ability to employ the language as a communicational tool often serves as a measure of one＇s speaking success in the language learning class. This research sought to investigate the effect of learners＇ autonomous textbook selection on the speaking ability of Iranian English as foreign language （EFL） learners. Moreover, finding and analyzing factors considered by the learners in selecting the textbooks were another aim of this research. Sixty Iranian intermediate EFL learners from the Simin Language Institute in Ramsar, Mazandaran, Iran, were selected as the participants of the study based on their scores on Oxford Placement Test. This test determines the level of the students＇ English proficiency. These participants were randomly assigned into the control and experimental groups. An interview procedure was run as their pretest. The experimental group studied from their selected books, besides the researcher＇s teaching in the class. After 16 sessions, a posttest, the same as the pretest, was run as well. The quantitative results indicated the superior performance of the experimental group over the control group. Furthermore, an analysis of the Litz＇s （2000） questionnaire shows that learners considered criteria such as practical considerations, layout and design, activities, skills, language type, subject and content of the selected books.展开更多
This study relies on a contrastive analysis to underscore the functions of stress as a shift in translation, especially when phonological specifications can have an impact on translation. In the original model of tran...This study relies on a contrastive analysis to underscore the functions of stress as a shift in translation, especially when phonological specifications can have an impact on translation. In the original model of translation shifts proposed by Catford, only segmental linguistic elements are taken into consideration, while the model totally ignores stress as a supra-segmental linguistic element. Including stress within the analytic procedures of the model can bring about a new type of shift. This implies that Catford＇s categorization of shifts must be developed in order to increase its applicability, especially when phonological specifications in the source text can have an impact on grammar and lexical items in the target text. As a result of the inclusion of stress into Catford＇s original mode, a revised version of the translation shift model is suggested. The study further emphasizes the various dimensions of stress and the functions it can have in oral aspects of translation and drama translation.展开更多
文摘The NO2 molecule adsorption on B12N12 nano-cage was investigated using density functional theory calculations in terms of adsorption energy, HOMO/LUMO energy gap （Eg） changes, charge transfer, structural deformation, etc. Furthermore, some aspects of stability and properties of B12N12 including calculation of binding electronic and Gibbs free energies, density of states, and molecular electrostatic potential surfaces are investigated. Three possible configurations for NO2 adsorption on the B12N12 nano-cage are energetically found. Interestingly, the results reveals that the Eg of B12N12 cluster is very sensitive to the pres- ence of NO2 molecules as its value reduces from 6.84 eV in free cluster to 3.23 eV in the most stable configuration of NO2/cluster complex. This phenomenon dramatically increases the electrical conductivity of the cluster, suggesting that the B12N12 nano-cluster may be potential sensor for NO2 gaseous molecule detection.
文摘Using density functional theory （DFT）, the thermodynamic parameters of the CO2 absorp-tion into the aqueous solution of the aliphatic amines including some alkylamines, alka-nolamines, diamines and a type of aminoamide were calculated. The geometry optimiza-tion and the calculation of vibrational frequencies in the gas phase were performed at the B3LYP/6-311＋ G（d,p） level of theory. Moreover, the standard solvation free energies of the studied species were computed upon the solution phase optimized geometries through the latest continuum solvation model （SMD/IEF-PCM） at the HF/6-31G（d） level of theory. With this approach, two important properties of the CO2 absorption into the aqueous so-lutions of the studied amines were evaluated： the acid dissociation constant （pKa） of the parent amines and the standard enthalpy change （ΔH^φabs） related to the CO2 absorption process. A roughly linear relationship was observed between pKa and ΔH^φabs. This finding suggests that a raise in the basicity of an amine leads to an increase in the heat released in CO2 absorption and consequently in the required energy for the regeneration of amine.
文摘Density functional theory calculations are performed to study the structural, electronic and magnetic properties of hexagonal NiAs type and cubic zinc blende type MnSb structure and interface of zinc blende MnSb with GaSb（001）. We used generalized gradiant approximation to calculate the exchange-correlation term in bulk and interface determination. The zinc blende structure of MnSb is found to be ferromagnetic half-metal with a total moment of 4 μB per formula unit. Results show that the half-metallicity character is preserved at MnSb/GaSb（001） interface. The magnetic moment of Mn atom in interface is reduced and the magnetic moment of the interface Sb atom is equal to the average of the corresponding bulk values in two sides of the interface. The band alignment properties are also computed and a rather large minority valance band offset of about 1.25 eV is obtained in this heterojunction.
文摘We have performed a comparative theoretical study on the adsorption of nitric oxide （NO） on Zn12012 and Mgt2012 nanocages in terms of their energetic, geometric, and electronic properties. It has been found that NO adsorption on the MgO nanocage is energetically more favorable than that on the ZnO one. In contrast to the ZnO nanocage, HOMO-LUMO energy gap （Eg） of MgO one is dramatically decreased in the presence of NO molecule so that it is transformed from an intrinsic semiconductor （Eg≈5.00 eV） to a p-type one （Eg≈1.93 eV）. We have predicted that electronic and conductance properties of the Mg12012 nanocage are sensitive toward NO molecule, thus it may be potential candidate in detection of NO molecules.
文摘The mechanism and regioselectivity of 1,3-dipolar cycloaddition of N-[methyl]-C-[5-nitro-2-furyl] nitrilimine with dimethyl 7-oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylate were investigated using activation energy calculations and density functional theory-based reactivity indexes. The reaction proceeds by an asynchronous concerted mechanism. The calculations are performed at the B3LYP/6-31G（d） level of theory and the obtained results are in agreement with experimental outcome.
文摘The ability to employ the language as a communicational tool often serves as a measure of one＇s speaking success in the language learning class. This research sought to investigate the effect of learners＇ autonomous textbook selection on the speaking ability of Iranian English as foreign language （EFL） learners. Moreover, finding and analyzing factors considered by the learners in selecting the textbooks were another aim of this research. Sixty Iranian intermediate EFL learners from the Simin Language Institute in Ramsar, Mazandaran, Iran, were selected as the participants of the study based on their scores on Oxford Placement Test. This test determines the level of the students＇ English proficiency. These participants were randomly assigned into the control and experimental groups. An interview procedure was run as their pretest. The experimental group studied from their selected books, besides the researcher＇s teaching in the class. After 16 sessions, a posttest, the same as the pretest, was run as well. The quantitative results indicated the superior performance of the experimental group over the control group. Furthermore, an analysis of the Litz＇s （2000） questionnaire shows that learners considered criteria such as practical considerations, layout and design, activities, skills, language type, subject and content of the selected books.
文摘This study relies on a contrastive analysis to underscore the functions of stress as a shift in translation, especially when phonological specifications can have an impact on translation. In the original model of translation shifts proposed by Catford, only segmental linguistic elements are taken into consideration, while the model totally ignores stress as a supra-segmental linguistic element. Including stress within the analytic procedures of the model can bring about a new type of shift. This implies that Catford＇s categorization of shifts must be developed in order to increase its applicability, especially when phonological specifications in the source text can have an impact on grammar and lexical items in the target text. As a result of the inclusion of stress into Catford＇s original mode, a revised version of the translation shift model is suggested. The study further emphasizes the various dimensions of stress and the functions it can have in oral aspects of translation and drama translation.
