The equilibrium geometrical optimizations and frequency calculation on B2N2 molecule in the singlet have been made at B3LYP/6-311+G*and CCSD/6-311+G*levels,respectively.The seven stable equilibrium structures were obt...The equilibrium geometrical optimizations and frequency calculation on B2N2 molecule in the singlet have been made at B3LYP/6-311+G*and CCSD/6-311+G*levels,respectively.The seven stable equilibrium structures were obtaind. The rhombus D2h structure of BNBN is the most stable and its electronic state is1A.g.展开更多
The unbalance between synaptic(Glu N2 A, mediating the protective pathway) and extrasynaptic NMDA receptors(NMDARs)(Glu N2 B, mediating the excitotoxic pathway) has been found in Alzheimer disease(AD), indicating rest...The unbalance between synaptic(Glu N2 A, mediating the protective pathway) and extrasynaptic NMDA receptors(NMDARs)(Glu N2 B, mediating the excitotoxic pathway) has been found in Alzheimer disease(AD), indicating restoring the balance of Glu N2 A and Glu N2 B should be beneficial for AD therapy. In this study, the Glu N2 B-selective antagonist, ifenprodil, and the non-selective NMDAR agonist, NMDA, had little effects on amyloid-beta(Abeta)-induced long-term potentiation(LTP) deficits.Enhancing the activity of Glu N2 A had a protective effect against Abeta, and specific activation of Glu N2 A and inhibition of Glu N2 B showed a better protective effect. The combination of ifenprodil and D-cycloserine(a co-activator of NMDRs similar to D-serine) led to greater improvement in behavior tests than ifenprodil or D-cycloserine alone, meanwhile, the combination of ifenprodil and D-cycloserine reversed the signal pathway more significantly than ifenprodil or D-cycloserine alone. These results indicate that enhancing synaptic NMDARs and inhibiting extrasynaptic NMDARs concurrently showed protective effects against Abeta-induced neurotoxicity, suggesting that modulation of the balance between Glu N2 A and Glu N2 B might be a good strategy for drug discovery against AD.展开更多
The aromaticity of all possible substituted fullerene isomers of C18N2, C18B2, C18BN, and their molecular ions which originate from the C20 （Ih） cage were studied by the topological resonance energy （TRE） and the ...The aromaticity of all possible substituted fullerene isomers of C18N2, C18B2, C18BN, and their molecular ions which originate from the C20 （Ih） cage were studied by the topological resonance energy （TRE） and the percentage topological resonance energy methods. The relationship between the aromaticity of C18BxNy isomers and the sites where the heteroatoms dope at the C20 （Ih） cage is discussed. Calculation results show that at the neutral and cationic states all the isomers are predicted to be antiaromatic with negative TREs, but their polyvalent anions are predicted to be aromatic with positive TREs. The most stable isomer is formed by heteroatom doping at the 1,11-sites in C18N2. C18B2, and C18BN. Heterofullerenes are more aromatic than C20. The stability order in the neutral states is C18N2〉C18BN〉C18B2〉C20. The stability order in closed-shell is C18B2^8- 〉C20^6- 〉C18BN^6- 〉C18N2^4-. This predicts theoretically that their polyvalent anions have high aromaticity.展开更多
Recently a new molecule, cyanomethamine, has been detected towards Sagittarius B2（N） （Sgr B2（N））. Studying the formation mechanisms of complex interstellar molecules is difficult. Hence, a theoretical quantum ch...Recently a new molecule, cyanomethamine, has been detected towards Sagittarius B2（N） （Sgr B2（N））. Studying the formation mechanisms of complex interstellar molecules is difficult. Hence, a theoretical quantum chemical approach for analyzing the reaction mechanism describing the forma- tion of interstellar cyanomethamine through detected interstellar molecules and radicals （NCCN＋H） is discussed in the present work. Calculations are performed by using quantum chemical techniques, such as Density Functional Theory （DFT） and Mφ11er-Plesset perturbation （MP2） theory with a 6-311G（d,p） basis set, both in the gas phase and in icy grains. The proposed reaction path （NCCN＋H＋H） has exother- micity with no barrier which indicates the possibility of cyanomethamine formation in the interstellar medium.展开更多
文摘The equilibrium geometrical optimizations and frequency calculation on B2N2 molecule in the singlet have been made at B3LYP/6-311+G*and CCSD/6-311+G*levels,respectively.The seven stable equilibrium structures were obtaind. The rhombus D2h structure of BNBN is the most stable and its electronic state is1A.g.
文摘The unbalance between synaptic(Glu N2 A, mediating the protective pathway) and extrasynaptic NMDA receptors(NMDARs)(Glu N2 B, mediating the excitotoxic pathway) has been found in Alzheimer disease(AD), indicating restoring the balance of Glu N2 A and Glu N2 B should be beneficial for AD therapy. In this study, the Glu N2 B-selective antagonist, ifenprodil, and the non-selective NMDAR agonist, NMDA, had little effects on amyloid-beta(Abeta)-induced long-term potentiation(LTP) deficits.Enhancing the activity of Glu N2 A had a protective effect against Abeta, and specific activation of Glu N2 A and inhibition of Glu N2 B showed a better protective effect. The combination of ifenprodil and D-cycloserine(a co-activator of NMDRs similar to D-serine) led to greater improvement in behavior tests than ifenprodil or D-cycloserine alone, meanwhile, the combination of ifenprodil and D-cycloserine reversed the signal pathway more significantly than ifenprodil or D-cycloserine alone. These results indicate that enhancing synaptic NMDARs and inhibiting extrasynaptic NMDARs concurrently showed protective effects against Abeta-induced neurotoxicity, suggesting that modulation of the balance between Glu N2 A and Glu N2 B might be a good strategy for drug discovery against AD.
文摘The aromaticity of all possible substituted fullerene isomers of C18N2, C18B2, C18BN, and their molecular ions which originate from the C20 （Ih） cage were studied by the topological resonance energy （TRE） and the percentage topological resonance energy methods. The relationship between the aromaticity of C18BxNy isomers and the sites where the heteroatoms dope at the C20 （Ih） cage is discussed. Calculation results show that at the neutral and cationic states all the isomers are predicted to be antiaromatic with negative TREs, but their polyvalent anions are predicted to be aromatic with positive TREs. The most stable isomer is formed by heteroatom doping at the 1,11-sites in C18N2. C18B2, and C18BN. Heterofullerenes are more aromatic than C20. The stability order in the neutral states is C18N2〉C18BN〉C18B2〉C20. The stability order in closed-shell is C18B2^8- 〉C20^6- 〉C18BN^6- 〉C18N2^4-. This predicts theoretically that their polyvalent anions have high aromaticity.
基金the University Grant Commission(UGC)supported by a major research project+2 种基金supported by a UGC research awardISRO major research projectthe UGC BSR Meritorious Fellowship
文摘Recently a new molecule, cyanomethamine, has been detected towards Sagittarius B2（N） （Sgr B2（N））. Studying the formation mechanisms of complex interstellar molecules is difficult. Hence, a theoretical quantum chemical approach for analyzing the reaction mechanism describing the forma- tion of interstellar cyanomethamine through detected interstellar molecules and radicals （NCCN＋H） is discussed in the present work. Calculations are performed by using quantum chemical techniques, such as Density Functional Theory （DFT） and Mφ11er-Plesset perturbation （MP2） theory with a 6-311G（d,p） basis set, both in the gas phase and in icy grains. The proposed reaction path （NCCN＋H＋H） has exother- micity with no barrier which indicates the possibility of cyanomethamine formation in the interstellar medium.
