Journal of Physical and Theoretical Chemistry
Volume:18 Issue: 2, Summer 2021

QSAR investigations of lipophilicity (XLOGP3) and biological activity (IC50) values of some Doxazolidine derivatives were conducted using combinations of multiple linear regression (MLR) and artificial neural network (ANN) modeling methods and three different optimization techniques including simulated annealing (SA), genetic algorithm (GA) and Imperialist Competitive algorithm (ICA). In addition CORAL software was used to correlate the lipophilicity and biological activity to the structural parameters of the drugs. The obtained results were compared and GA-ANN and ICA-MLR combinations showed the best performance with regard to the correlation coefficient (R2) and root-mean-square error (RMSE). The most effective descriptors extracted from lipophilicity and biological activity studies were presented and discussed. From GA-ANN method, the most important physico-chemical descriptors were found to be minimum value in atomic Sanderson electronegativities and maximum value in Squared Moriguchi Octanol-Water partition coeff.(log P ˆ2) descriptors.ICA-MLR method suggests the maximum value in polarizibility, electrotopological state and atom van der Walls volume as the most important physicochemical descriptors.It was concluded that QSAR study and Monte Carlo method can lead to a more comprehensive understanding of the relation between physico-chemical, structural or theoretical molecular descriptors of drugs to their biological activities and Lipophilicity.

In this work, we investigated the structural and dynamical properties of water on nickel nanosheet. The interaction of water molecules on a nickel surface was studied using reactive force field molecular dynamics (ReaxFF-MM). The results showed that water molecules near the nickel surface change in terms of structure and dynamics. The water molecules form a two-layer structure close to the nickel surface. In addition, intense stratification effects near the nickel surfaces are visible.To do so, calculations were first performed using ReaxFF in order to reproduce certain well-known properties of pure nickel and nickel-water systems. We calculated both the density profile and the radial distribution function (RDF) of the water layers from the nickel surface. The atomic probability density profile shows that water is strongly adsorbed on the nickel cristobalite surface, while the RDF indicates differently adsorbed water molecules in the first adsorption layer.

The dipole moments and polarizabilities in various excited states of o-, m- and p-nitroanilines were estimated using Linder’s variant of Abe solvatochromic model. The ground and excited state dipole moments of these molecules were computed from experimental and theoretical studies using solvatochromic technique and Density Functional Theory (DFT) respectively. The trend observed for the various excited states dipole moments of the o-, m- and p- isomers of nitroaniline follow the order ortho>meta>para. The excited state polarizabilities obtained for the electronic transitions in each of the compounds are reflective of the oscillator strength f values for these transitions. Also, the excited singlet-state dipole moments obtained were higher than the calculated ground state dipole moments which shows that the excited singlet-state is more polar than the ground state for all the compounds studied. The effects of solvent manifest in form of enhancement to the electronic intensities. The results of the present analysis show internal consistency and agree reasonably with Abe’s theory.

Imidazole is compound with a wide range of biological activities and imidazole derivatives are the basis of several groups of drugs.In this study the relationship between molecular descriptors and the thermal energy (Eth kJ/mol), and heat capacity (Cv J/mol) of imidazole derivatives is studied. The chemical structures of 85 Imidazole derivatives were optimized at HF/6-311G* level with Gaussian 98 software.Molecular descriptors were calculated for selected compound by using the Dragon software.The Genetic algorithm- multiple linear regression (GA-MLR) and backward methods were used to select the suitable descriptors and also for predicting the thermodynamic properties of imidazole derivatives.The obtained models were evaluated by statistical parameters, such as correlation coefficient (R2adj), Fisher ratio (F), Root Mean Square Error (RMSE), Durbin-Watson statistic (D) and significance (Sig).The predictive powers of the GA- MLR models are studied using leave-one-out (LOO) cross-validation and external test set. The predictive ability of the GA-MLR models with two-three selected molecular descriptors was found to be satisfactory. The developed QSPR models can be used to predict the property of compounds not yet synthesized.

Inconel 738 superalloy was aluminized using laser cladding technique. The objective of the recent research was to investigate the effect of main process parameters of laser cladding of Al on a gas turbin blade; such as laser power, laser scanning speed and powder feeding rate on geometry of single clad track and find processing window. Height, width and depth of penetration were measured using imageJ software. It was found that the height of the clad track was related to combined parameter as (P/S) 2/3(F/S) 1/5. The width of the clad track was independent of the feed rate. Depth of penetration is impressed by all three main process parameters with PS2/3F-2/3. Dilution and wetting angle were calculated and the processing window was obtained for having proper limitations for dilution and wetting angle to achieve a qualified coating and can be used as a guideline for aluminizing of In738 via laser cladding technology.

The applicability of the synthesized CM-β-CD-Fe3O4NPs as a novel adsorbent for eliminating Crystal Violet (CV) dye from aqueous media was investigated. This paper focuses on the development of an effective methodology to obtain the optimum removal conditions assisted by ultrasonic to maximize removal of (CV) dye onto CM-β-CD-Fe3O4NPs in aqueous solution using response surface methodology (RSM). This novel material was characterized by different techniques such as FT-IR, XRD and SEM. The influences of variables such as initial (CV) dye concentration (X1), pH (X2), adsorbent dosage (X3), sonication time (X4) investigated by central composite design (CCD) under response surface methodology. The process was empirically modeled to reveal the significant variables and their possible interactions. The optimization conditions were set as: 10.0 mg L-1, 6.0, 5 min and 0.025 g, for ultrasound time, pH, adsorbent mass, (CV) dye concentration respectively. Finally, it was shown that the adsorption of (CV) dye removal by adsorbent was at pH 6.0. This issue that the sorption of (CV) dye conforms to the pseudo-second-order rate equation and the Langmuir model explains equilibrium data was clearly proven. The maximum monolayer capacity (qmax) was found to be 100.0 mgg-1 for (CV) dye at optimum conditions. The application of Isotherms in obtaining the thermodynamic parameters like free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) of adsorption were confirmed. The exothermicity of the process was proven by negative value of (ΔGo, ΔHo and ΔSo) which showed the affinity of CM-β-CD-Fe3O4NPs synthesis for Crystal Violet (CV) dye deletion.

Monte Carlo and Multiple Linear Regression (MLR) and Imperialist Competitive Algorithm (ICA) were used to select the most appropriate descriptors. Examining the quality of the model by comparing the mean squared error (MSE) and correlation coefficient (R2), indicated that 140 is the most appropriate number of empires for the gas phase . In the Monte Carlo method, CORAL software was used and the data were randomly divided into training, calibration, and test subsets in three splits. The correlation coefficient (R2), cross-validated correlation coefficient (Q2) and standard error of the model were calculated to be respectively 0.9301, 0.7377, and 0.595 for the test set with an optimum threshold of 4. It was concluded that simultaneous utilization of MLR-ICA and Monte Carlo method can lead to a more comprehensive understanding of the relation between physico-chemical, structural or theoretical molecular descriptors of drugs to their biological activities and facilitate designing of new drugs.