Computation of Oxidation Potentials of Solvated Nucleobases by Static and Dynamic Multilayer Approaches

The determination of the redox properties of nucleobases is of paramount importance to get insight into the charge-transfer processes in which they are involved, as those occurring in DNA-inspired biosensors. Although many theoretical and experimental studies have been conducted, the value of the one-electron oxidation potentials of nucleobases is not well defined. Moreover, the most appropriate theoretical protocol to model the redox properties has not been established yet. In this work, we have implemented and evaluated different static and dynamic approaches to compute the one-electron oxidation potentials of solvated nucleobases. In the static framework, two thermodynamic cycles have been tested to assess their accuracy against the direct determination of oxidation potentials from the adiabatic ionization energies. Then, the introduction of vibrational sampling, the effect of implicit and explicit solvation models, and the application of the Marcus theory have been analyzed through dynamic methods. The results revealed that the static direct determination provides more accurate results than thermodynamic cycles. Moreover, the effect of sampling has not shown to be relevant, and the results are improved within the dynamic framework when the Marcus theory is applied, especially in explicit solvent, with respect to the direct approach. Finally, the presence of different tautomers in water does not affect significantly the one-electron oxidation potentials.

Self-schemes Among Postgraduate Students

1- Recognizing the level of self-schemes of postgraduate students. 2- Identifying the differences in the level of self-schemes among postgraduate students according to the variables (gender, specialization and stage . The research sample (construction and application) consisted of (400) male and female students in the faculties of the University of Al-Qadisiyah, they were chosen randomly according to the Department of postgraduate Studies at the University of Al-Qadisiyah, with (156) males, (174) females from the master’s degree, and (38) males, (32) PhD female. The researcher used a research tool, which is building a self-scheme scale. first: The scale of the self-schemes that the researcher built according to Marcus theory (Markus, 1977), which consisted of (45) declarative paragraphs, under which five alternatives fall, and each alternative represents a degree of the self-schemes degrees The psychometric properties of the scale were verified from the apparent validity, construct validity and stability by the method of analysis of variance (Cronbach's alpha) and halving, where the statistical means were used (percentage, t-test for two independent samples, Pearson correlation coefficient, Spearman-Brown equation, variance, standard deviation, skewness ) .