A DFT calculations are carried out at UB3LYP/6-311＋＋G (3df, 2p) levels of theory to study electro... more A DFT calculations are carried out at UB3LYP/6-311＋＋G (3df, 2p) levels of theory to study electrocyclic thermal cleavage of four (R) derivatives of unsaturated bicyclic diaziridines, 1 X-R , to produce corresponding (Z) and (E) azomethine imides (2 X-Z , 2 X-E , 3 X-Z and 3 X-E), where X＝H, Me, t-Bu and Ph. Cleavage of 1 X-R series to form the most stable 3 X-Z product, (path 2) is found the favored procedure because of delocalized negative charge on five atoms and lower steric effect in related transition state. According to IRC calculations in paths 1 and 2, C 6-N 1 bond is cleaved before the rate determinating step (transition state). The stability of unsaturated bicyclic diaziridines and their corresponding (Z) and (E) azomethine imides is in the following order in gas phase and chloroform, tetrahydrofuran, and acetone solvents: 3 X-Z ＜3 X-E ＜2 X-Z ＜2 X-E ＜1 X-R ＜1 X-S .
We have used density functional theory to investigate the possibility of using graphyne nanotubes... more We have used density functional theory to investigate the possibility of using graphyne nanotubes for the detection of toxic gases such as formaldehyde and hydrogen sulfide. The effect of these gases on the electronic properties of zigzag nanotubes formed based on α-graphyne is studied. The large adsorption distance, small adsorption energy, and small charge transfer indicate physisorption of formaldehyde and hydrogen sulfide on the graphyne nanotubes. It is found a considerable effect on the electronic properties of graphyne nanotubes due to charge transfer from the molecules to the nanotubes. The zigzag α-graphyne nanotubes with semiconducting properties become n-type semiconductors with the adsorption of formaldehyde and hydrogen sulfide. Our results show that the α-graphyne nanotubes are promising materials for the detection of toxic gases.
The influence of electric field on the electronic properties of bilayer and trilayer graphyne has... more The influence of electric field on the electronic properties of bilayer and trilayer graphyne has been studied using the density functional theory. We have investigated alpha graphyne due to its analogous to graphene. The bilayer and trilayer graphyne with different stacking style configurations have been considered. Our results indicate that the electronic properties of alpha graphyne are insensitive to the number of graphyne layer and configuration. The bilayer and trilayer graphyne are semimetal similar to the monolayer graphyne. It is found that applying a uniform electric field perpendicular to the graphyne sheet changes the electronic properties of AB-stacked bilayer and ABC-stacked trilayer graphyne so that they become semiconductor. The band gaps of the bilayer and trilayer graphyne with these configurations are enhanced by increasing strength of the electric field. Therefore, possibility of controlling the electronic properties of graphyne by applying electric field makes graphyne as a good candidate for next generation nanoelectronic devices.
The purpose of this study was to evaluate the effect of educational mobile game based on theories... more The purpose of this study was to evaluate the effect of educational mobile game based on theories of learning and educational psychology for the subject of the periodic table and also the effect of this method on students' academic achievements in the tenth grade of high school chemistry. The population of this study included all female students in the field of mathematics and experimental science in the tenth grade of high school who studied in Shahed and Fath Al-Mubin high schools in the city of Rey in the academic year of 2016-2017. Multi-stage cluster sampling method was used to select the sample. There were two groups of mathematics and experimental science in each of these schools. 20 students from the experimental school were randomly selected. They were presented and Q&A sessions were conducted online for the other group. In this study, finally, 20 people were randomly selected from the experimental group and 19 people from the control group due to the fall of the subjec...
Educational Measurement and Evaluation Studies, 2021
Objective: The aim of this study is to evaluate the chemistry questions of university entrance ex... more Objective: The aim of this study is to evaluate the chemistry questions of university entrance exam (concur) in 2017 by using item-response theory. Methods: This is an applied, descriptive research. 5,000 answer sheets of participants in Empirical Science group, were selected randomly as sample. All parameters were calculated with NOHARM and IRTPRO and EXCEL softwares. Results: First the initial assumptions of IRT theory (unidimensionality and local Independence) were investigated. The parameters of each questions such as difficulty and discrimination coefficient, were calculated based on the classic and the item response theories. The results showed that 7 questions show a good fit with one and two parameter models and 21 questions are also compatible with three-parameter model and 13 questions don’t fit with any IRT models. The analysis with 3-PL-IRT showed the discrimination coefficient of 26 questions are strong (a> 1.3), 6 are moderate and 3 are weak (a <0.65). Also 11 questions were very difficult (b> 1.2) and 24 questions were appropriate (-1.2 Conclusion: The results showed that 3-PL IRT model has a better fit with the test. All questions are efficient in terms of discrimination coefficient and have a high level of difficulty and also guessing parameter is high in this test. The test’s questions have the highest Information and the least error for a high level of ability (range -1 to 2).
A DFT calculations are carried out at UB3LYP/6-311＋＋G (3df, 2p) levels of theory to study electro... more A DFT calculations are carried out at UB3LYP/6-311＋＋G (3df, 2p) levels of theory to study electrocyclic thermal cleavage of four (R) derivatives of unsaturated bicyclic diaziridines, 1 X-R , to produce corresponding (Z) and (E) azomethine imides (2 X-Z , 2 X-E , 3 X-Z and 3 X-E), where X＝H, Me, t-Bu and Ph. Cleavage of 1 X-R series to form the most stable 3 X-Z product, (path 2) is found the favored procedure because of delocalized negative charge on five atoms and lower steric effect in related transition state. According to IRC calculations in paths 1 and 2, C 6-N 1 bond is cleaved before the rate determinating step (transition state). The stability of unsaturated bicyclic diaziridines and their corresponding (Z) and (E) azomethine imides is in the following order in gas phase and chloroform, tetrahydrofuran, and acetone solvents: 3 X-Z ＜3 X-E ＜2 X-Z ＜2 X-E ＜1 X-R ＜1 X-S .
We have used density functional theory to investigate the possibility of using graphyne nanotubes... more We have used density functional theory to investigate the possibility of using graphyne nanotubes for the detection of toxic gases such as formaldehyde and hydrogen sulfide. The effect of these gases on the electronic properties of zigzag nanotubes formed based on α-graphyne is studied. The large adsorption distance, small adsorption energy, and small charge transfer indicate physisorption of formaldehyde and hydrogen sulfide on the graphyne nanotubes. It is found a considerable effect on the electronic properties of graphyne nanotubes due to charge transfer from the molecules to the nanotubes. The zigzag α-graphyne nanotubes with semiconducting properties become n-type semiconductors with the adsorption of formaldehyde and hydrogen sulfide. Our results show that the α-graphyne nanotubes are promising materials for the detection of toxic gases.
The influence of electric field on the electronic properties of bilayer and trilayer graphyne has... more The influence of electric field on the electronic properties of bilayer and trilayer graphyne has been studied using the density functional theory. We have investigated alpha graphyne due to its analogous to graphene. The bilayer and trilayer graphyne with different stacking style configurations have been considered. Our results indicate that the electronic properties of alpha graphyne are insensitive to the number of graphyne layer and configuration. The bilayer and trilayer graphyne are semimetal similar to the monolayer graphyne. It is found that applying a uniform electric field perpendicular to the graphyne sheet changes the electronic properties of AB-stacked bilayer and ABC-stacked trilayer graphyne so that they become semiconductor. The band gaps of the bilayer and trilayer graphyne with these configurations are enhanced by increasing strength of the electric field. Therefore, possibility of controlling the electronic properties of graphyne by applying electric field makes graphyne as a good candidate for next generation nanoelectronic devices.
The purpose of this study was to evaluate the effect of educational mobile game based on theories... more The purpose of this study was to evaluate the effect of educational mobile game based on theories of learning and educational psychology for the subject of the periodic table and also the effect of this method on students' academic achievements in the tenth grade of high school chemistry. The population of this study included all female students in the field of mathematics and experimental science in the tenth grade of high school who studied in Shahed and Fath Al-Mubin high schools in the city of Rey in the academic year of 2016-2017. Multi-stage cluster sampling method was used to select the sample. There were two groups of mathematics and experimental science in each of these schools. 20 students from the experimental school were randomly selected. They were presented and Q&A sessions were conducted online for the other group. In this study, finally, 20 people were randomly selected from the experimental group and 19 people from the control group due to the fall of the subjec...
Educational Measurement and Evaluation Studies, 2021
Objective: The aim of this study is to evaluate the chemistry questions of university entrance ex... more Objective: The aim of this study is to evaluate the chemistry questions of university entrance exam (concur) in 2017 by using item-response theory. Methods: This is an applied, descriptive research. 5,000 answer sheets of participants in Empirical Science group, were selected randomly as sample. All parameters were calculated with NOHARM and IRTPRO and EXCEL softwares. Results: First the initial assumptions of IRT theory (unidimensionality and local Independence) were investigated. The parameters of each questions such as difficulty and discrimination coefficient, were calculated based on the classic and the item response theories. The results showed that 7 questions show a good fit with one and two parameter models and 21 questions are also compatible with three-parameter model and 13 questions don’t fit with any IRT models. The analysis with 3-PL-IRT showed the discrimination coefficient of 26 questions are strong (a> 1.3), 6 are moderate and 3 are weak (a <0.65). Also 11 questions were very difficult (b> 1.2) and 24 questions were appropriate (-1.2 Conclusion: The results showed that 3-PL IRT model has a better fit with the test. All questions are efficient in terms of discrimination coefficient and have a high level of difficulty and also guessing parameter is high in this test. The test’s questions have the highest Information and the least error for a high level of ability (range -1 to 2).
Uploads
Papers by Alireza Karami
Methods: This is an applied, descriptive research. 5,000 answer sheets of participants in Empirical Science group, were selected randomly as sample. All parameters were calculated with NOHARM and IRTPRO and EXCEL softwares.
Results: First the initial assumptions of IRT theory (unidimensionality and local Independence) were investigated. The parameters of each questions such as difficulty and discrimination coefficient, were calculated based on the classic and the item response theories. The results showed that 7 questions show a good fit with one and two parameter models and 21 questions are also compatible with three-parameter model and 13 questions don’t fit with any IRT models. The analysis with 3-PL-IRT showed the discrimination coefficient of 26 questions are strong (a> 1.3), 6 are moderate and 3 are weak (a <0.65). Also 11 questions were very difficult (b> 1.2) and 24 questions were appropriate (-1.2 Conclusion: The results showed that 3-PL IRT model has a better fit with the test. All questions are efficient in terms of discrimination coefficient and have a high level of difficulty and also guessing parameter is high in this test. The test’s questions have the highest Information and the least error for a high level of ability (range -1 to 2).
Methods: This is an applied, descriptive research. 5,000 answer sheets of participants in Empirical Science group, were selected randomly as sample. All parameters were calculated with NOHARM and IRTPRO and EXCEL softwares.
Results: First the initial assumptions of IRT theory (unidimensionality and local Independence) were investigated. The parameters of each questions such as difficulty and discrimination coefficient, were calculated based on the classic and the item response theories. The results showed that 7 questions show a good fit with one and two parameter models and 21 questions are also compatible with three-parameter model and 13 questions don’t fit with any IRT models. The analysis with 3-PL-IRT showed the discrimination coefficient of 26 questions are strong (a> 1.3), 6 are moderate and 3 are weak (a <0.65). Also 11 questions were very difficult (b> 1.2) and 24 questions were appropriate (-1.2 Conclusion: The results showed that 3-PL IRT model has a better fit with the test. All questions are efficient in terms of discrimination coefficient and have a high level of difficulty and also guessing parameter is high in this test. The test’s questions have the highest Information and the least error for a high level of ability (range -1 to 2).