a b s t r a c tThe molecular structure of 4-methylpiridine-N-oxide, 4-MePyO, has been studied by gas-phase electron diffraction monitored by mass spectrometry (GED/MS) and quantum chemical (DFT) calculations. Both, quantum chemistry and GED analyses resulted in C S molecular symmetry with the planar pyridine ring. Obtained molecular parameters confirm the hyperconjugation in the pyridine ring and the sp 2 hybridization concept of the nitrogen and carbon atoms in the ring. The experimental geometric parameters are in a good agreement with the parameters for non-substituted N-oxide and reproduced very closely by DFT calculations. The presence of the electron-donating CH 3 substituent in 4-MePyO leads to a decrease of the ipso-angle and to an increase of r(N/O) in comparison with the non-substituted PyO. Electron density distribution analysis has been performed in terms of natural bond orbitals (NBO) scheme. The nature of the semipolar N/O bond is discussed.
This article presents the results of the QSAR study of bisphenol A and its analogs. Molecular-chemical analysis of these substances is performed on base of the Density Functional Theory (DFT), using the function 6-31 + G *. The calculation of the characteristic parameters of the structure is given by optimizing molecular structures, vibrational frequencies, the molecular orbital energies with reasonable accuracy. The obtained quantum parameters and known observable activities are used as input data for constructing the QSAR model, using the classical data processing method in statistical mathematics - the multivariable linear regression. The constructed model QSAR has R2> 0,9; and . The statistical parameters show that the model, constructing by method of multiple linear regression using the parameters of quantum chemistry can be used as a predictive model of the activity of estrogens for unexplored derivatives and BPA analogs with moderate reliability. Keywords Bisphenol A, Estrogen, Density Functional Theory, M06 hybridmeta - GGA functional, Quantitative structure – activity relationship, Multiple linear regression References Rezg R, El-Fazaa S, Gharbi N, Mornagui B (March 2014). "Bisphenol A and human chronic diseases: Current evidences, possible mechanisms, and future perspectives".Environment International 2014, 64, 83–90. [2] Melzer D, Rice NE, Lewis C, Henley WE, Galloway TS (2010). Zhang, Baohong, ed."Association of Urinary Bisphenol a Concentration with Heart Disease: Evidence from NHANES 2003/06". PLoS ONE 5 (1). [3] Manikkam, M.; Tracey, R.; Guerrero-Bosagna, C.; Skinner, M. K. (January 24, 2013). "Plastics derived endocrine disruptors (BPA, DEHP and DBP) induce epigenetic transgenerational inheritance of obesity, reproductive disease and sperm epimutations".PLoS ONE 8 (1). 1–16. [4] D.R. Doerge, N.C. Twaddle, M. Vanlandingham, R.P. Brown, J.W. Fisher, Toxicol. Appl. Pharmacol. 2011, 255, 261.[5] Ho SM, Tang WY, Belmonte de Frausto J, Prins GS (2006). "Developmental exposure to estradiol and bisphenol A increases susceptibility to prostate carcinogenesis and epigenetically regulates phosphodiesterase type 4 variant 4". Cancer Res. 66 (11): 5624–32. [6] Johanna R. Rochester and Ashley L. Bolden (2015 Jul) “Bisphenol S and F: A Systematic Review and Comparison of the Hormonal Activity of Bisphenol A Substitutes”. Environ Health Perspect123(7):643-50.[7] Kelly, P. C., William, A. T., Thomas, E. W., QSAR models of thein vitro estrogen activity of bisphenol A analogs, QSAR Comb.Sci., 2003, 22: 78―88.[8]. Frisch, M. J. T., G. W. et al , Gaussian 09, Revision D.01. Gaussian, Inc., Wallingford CT, 2009.[9]. Zhao, Y.; Truhlar, D., The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals. Theor Chem Account 2008,120 (1-3), 215-241.
Đáp ứng nhu cầu đổi mới giáo dục theo hướng phát triển năng lực, phẩm chất của học sinh, việc áp dụng những phương pháp và kỹ thuật dạy học hiện đại vào dạy học lịch sử là việc rất cần thiết. Kỹ thuật mảnh ghép là kỹ thuật góp phần phát triển năng lực tổng hợp của học sinh thông qua hoạt động nhóm. Nghiên cứu này thực hiện nhằm mục đích đề xuất một số biện pháp nâng cao hiệu quả sử dụng kỹ thuật mảnh ghép trong dạy học lịch sử thế giới lớp 8 ở trường phổ thông. Bài viết đã sử dụng phương pháp nghiên cứu khoa học giáo dục, phương pháp thu thập để nghiên cứu cơ sở lí luận, đề xuất một số biện pháp nâng cao hiệu quả sử dụng kỹ thuật mảnh ghép. Kết quả nghiên cứu đã cho thấy rõ sự khác biệt khi sử dụng kỹ thuật mảnh ghép vào giảng dạy lịch sử ở trường trung học. Các biện pháp đề xuất sẽ góp phần nâng cao hiệu quả bài học lịch sử, tạo hứng thú học tập và góp phần phát triển những kĩ năng cần thiết cho người học khi vận dụng vào thực tiễn. Kết quả của nghiên cứu là tài liệu tham khảo hữu ích cho giáo viên, học sinh trong dạy học lịch sử ở trường phổ thông.
Abstract. This study gives a quantitative structure-activity relationship (QSAR) analysis of the estrogen activities of bisphenol A and analogs. The chemical structures of 23 Bisphenol A analogs have been characterized by quantum-electronic descriptors. The present study was performed using multiple regression analysis (MLR) and artificial neural network (ANN). The quantitative model was accordingly proposed and the toxicity of the compounds was interpreted based on the multivariate statistical analysis. This study shows that the results obtained by MLR were suitable and have served to predict estrogen activities, but compared to the results of the ANN model, we conclude that the prediction achieved by the latter is more effective and better than MLR model. Following to the obtained results, our proposed model may be useful to predict of Estrogen activities and risk assessment of chemicals. Keywords QSAR, Bisphenol A, multiple linear regression, artificial neural network References [1] Rezg R, El-Fazaa S, Gharbi N, Mornagui B (March 2014). "Bisphenol A and human chronic diseases: Current evidences, possible mechanisms, and future perspectives".Environment International 2014, 64, 83–90. [2] Melzer D, Rice NE, Lewis C, Henley WE, Galloway TS (2010). Zhang, Baohong, ed."Association of Urinary Bisphenol a Concentration with Heart Disease: Evidence from NHANES 2003/06". PLoS ONE 5 (1). [3] Manikkam, M.; Tracey, R.; Guerrero-Bosagna, C.; Skinner, M. K. (January 24, 2013). "Plastics derived endocrine disruptors (BPA, DEHP and DBP) induce epigenetic transgenerational inheritance of obesity, reproductive disease and sperm epimutations".PLoS ONE 8 (1). 1–16. [4] D.R. Doerge, N.C. Twaddle, M. Vanlandingham, R.P. Brown, J.W. Fisher, Toxicol. Appl. Pharmacol. 2011, 255, 261.[5] Ho SM, Tang WY, Belmonte de Frausto J, Prins GS (2006). "Developmental exposure to estradiol and bisphenol A increases susceptibility to prostate carcinogenesis and epigenetically regulates phosphodiesterase type 4 variant 4". Cancer Res. 66 (11): 5624–32. [6] Johanna R. Rochester and Ashley L. Bolden (2015 Jul) “Bisphenol S and F: A Systematic Review and Comparison of the Hormonal Activity of Bisphenol A Substitutes”. Environ Health Perspect123(7):643-50.[7] Kelly, P. C., William, A. T., Thomas, E. W., QSAR models of thein vitro estrogen activity of bisphenol A analogs, QSAR Comb.Sci., 2003, 22: 78―88.[8]. Frisch, M. J. T., G. W. et al , Gaussian 09, Revision D.01. Gaussian, Inc., Wallingford CT, 2009.[9]. Zhao, Y.; Truhlar, D., The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other functionals. Theor Chem[10] J. Devillers (1996), Strengths and Weaknesses of the Backpropagation Neural Network in QSAR and QSPR Studies, in: J. Devillers (Ed.) Neural Networks in QSAR and Drug Design, Academic Press, London, pp.1-46.[11] K. Hornik (1991), AppSroximation capabilities of multilayer feedforward networks, Neural Networks, 4 251-257.[12] A. Adad, M. Larif, R. Hmamouchi, M. Bouachrine, T. Lakhlifi, J. Comp. Meth. Mol. Des. 4(3) (2014) 72-83.[13] A. Golbraikh, A. Tropsha, Beware of q2. J. Mol. Graphics Model. 20 (2002) 269–276.
Molecular structures of N-Trifluoroacetylpiperidine 1 and 4-Methylpyridine-N-oxide 2 are studied by gas-phase electron diffraction/mass spectrometry (GED / MS) and quantum chemical (QC) calculations. The strong conjugation of the electron lone pair on the nitrogen atom and the double bond of the carbonyl cause molecule 1 to exist solely in the form of structure whereby the trifluoroacetyl group is in an intermediate position. As regards compound 2, the results of quantum chemical calculations and GED showed that molecule 2 has molecular symmetry in the form of CS with the flat pyridine ring. There were no hydrogen atoms on the flat surface of the pyridine ring. Structure parameters obtained from the experiments are appropriate for the parameters from quantum chemical calculation DFT for irreplaceable Noxide molecule. The presence of the CH3 substituent in 2 results in an increase of electron density and a decrease of the ipso angle, and an increase of r (N-O) in comparison with irreplaceable pyridine-N-oxide.
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