Physical Chemistry Research
Volume:10 Issue: 1, Winter 2022

Glasses with molar compositions 40Na2O - 10SrO - (20-x)TiO2 - xSiO2 - 30P2O5 (0 ≤ x ≤ 10), corresponding to the chemical formula Na4Sr0.5Ti(1-y)Siy(PO4)3 ( 0 ≤ y ≤ 0.5) with O/P = 4, have been prepared by the classical melt - quenching technique and structurally characterized by XRD, DSC, FTIR, Raman, NMR and density measurements. The introduction of SiO2 in the phosphate glass weakens slightly the glass network, as shown by the low increase of the molar volume (VM) and the decrease of the glass transition temperature (Tg). This behaviour is due to the existence of more ionic P-O-Si bonds than the P-O-P bonds. Spectroscopy studies reveal that SiO2 behaves as network former like P2O5 oxide and the glass structure contains P-O, P-O-P, Si-O, Si-O-Si, Ti-O, Ti-O-Ti, P-O-Ti and P-O-Si linkages. The preliminary results of the in vitro bioactivity tests show the existence of ionic exchanges between the SBF solution and the studied glasses. X-ray powder diffraction and FTIR spectroscopy confirmed the formation of Ca-P layer on the surfaces of the tested compositions.

An electroanalytical technique, cyclic voltammetry, has been carried out to understand the electrochemical behavior of Memantine hydrochloride and to evaluate the overall response of the drug. The solution variables such as concentration of the drug and instrumental variables such as scan rate have been studied. Functional groups present in the drug can bind to transitional metal ions present in the human body which are found to be more potent than the parent drug. In the present study, four transitional metal complexes of Memantine hydrochloride viz. Fe, Cu, Ni and Co complexes have been prepared. Characterization of transitional metal complexes is carried out using IR and Atomic Absorption Spectroscopy and the redox properties are investigated using cyclic voltammetry.

The temperature and the electrode thickness are among the important parameters which affect the performance of photovoltaic cells. Based on a diffusion model defined in the literature, these effects have been investigated by using MATLAB. This model is mainly characterized by the diffusion of electrons in the semiconductor porous film (TiO2). As a result, the increase of temperature has no effect on the density of the photocurrent. Moreover, when the thickness increases, the current density increases but after a certain value (15 µm) it decreases. The increase of the thickness results to a decrease in power and fill factor (FF), due to the internal resistance of the cell. In addition, the power conversion efficiency (PCE) is proportional to the temperature, as well as the thickness, except that the PCE starts to decrease from a certain value of the thickness (d = 5 µm). The simulation shows that the optimal electrode thickness is 5 µm.

In this work, a quantitative structure-activity relationship (QSAR) for some tacrine derivatives inhibitors of acetylcholinesterase was modeled using ligand-receptor interconnection interaction space. The descriptors were obtained by multivariate image analysis (MIA) of each molecule. Docking studies were performed to determine the best conformers of inhibitors. In the first step, the best pose of all the ligands was selected. Afterward, an MIA-QSAR model using ligand-receptor interconnection data was developed. The pool of descriptors was compressed by principal component analysis (PCA). Variable selection was carried out by genetic algorithm (GA) followed by model building using the support vector machine (SVM) regression method. The validation of the model's predictive ability was studied by a validation set containing 11 individual compounds. The Q2, r2 and, ∆r_m^2 test prediction values for PCA-GA-SVM model were 0.62, 0.89 and 0.145, respectively. After validating the results with all statistical data, three new molecules were designed by the MIA-QSAR model. Afterward, new molecules docked in the AChE active site. Docking studies were showed the amino acids TYR70, TYR121, TYR334, TRP279, PHE288, PHE290, TRP84, TRP334, and SER286 are active amino acids in the complex. Finally, the ADMET parameters of the new compounds were calculated and were in acceptable ranges.

The hard-sphere system is the reference fluid for most versions of the statistical associating fluid theory (SAFT) equation of state (EoS). In the SAFT-type equations of state, the hard-sphere equation directly affects the reference term and through the radial distribution function, indirectly affects the chain and association terms. Although there are various EoSs for describing the thermodynamic behavior of the hard-sphere fluid, the Carnahan-Starling EoS has traditionally been used to express the hard-sphere contribution in SAFT-type models. In this work, we integrated eight hard-sphere EoS in the simplified SAFT EoS and parameterized the resulting EoS with pressure-density-temperature data. Then, using modified versions of the simplified SAFT (SSAFT), we calculated the thermodynamic properties including pressure, density, temperature, saturated vapor-pressure, isochoric heat capacity, isobaric heat capacity, and speed of sound, for ethane, butane, hexane, and hexatriacontane, and compared the results. In general, the results of calculations show that although the modified Carnahan-Starling, Kolafa, and Carnahan-Starling EoSs have had the best results, considering the simplicity and straightforwardness of the Carnahan-Starling EoS, this EoS is a reasonable choice for developing SAFT-type equations of state.

In the oil refinery, the large amount of the output of fluid catalytic cracking units is the light cycle oil. The light cycle oil usually contains high percentage levels of sulfur compounds such as thiophene and dibenzothiophene. In this work, sulfur removal was made with catalytic oxidative desulfurization. The effect of oxidant, catalyst content, time and temperature of the oxidative desulfurization process was studied. Before evaluation these parameters, the mesoporous 5%Ni10%Mo/γ-Al2O3 catalyst was prepared by incipient wetness impregnation method. The prepared catalysts were characterized by X-Ray Diffraction, N2adsorption/desorption, Inductively Coupled Plasma Mass Spectrometry, Scanning Electron Microscopy and NH3-Temperature Programmed Desorption. The catalytic activity was measured with catalytic oxidative desulfurization setup and light cycle oil was as feed with 13000 ppm total sulfur. In order to reach the optimum conditions of the oxidative desulfurization process, different amount of oxidant, catalyst, time and temperature in oxidative desulfurization process were investigated. The optimum condition of the oxidative desulfurization process was 1g 5%Ni10%Mo/γ-Al2O3 catalyst, 1mL H2O2 as an oxidant, 30 ℃ and 120 min. At this optimum condition the total sulfur of light cycle oil reached from 13000 to 623 ppm.

The present work aims to study the theoretical chemistry applied to organic systems such as host / guest inclusion complexes. In literature different molecular modeling computation methods have been used to study the complexation of the host β-cyclodextrin molecule, with the guest (S) -2-Isopropyl-1- (o-nitrophenyl) sulfonyl) aziridine molecule, as semi-empirical PM3 and DFT (Density Functional Theory) calculations in gas and aqueous phases. The present paper focus on complexation, interaction and deformation energies determination, besides geometries, electronic structure, and chemical reactivity in order to describe the changes that AZ during encapsulation in two phases and two orientations. The results obtained with the Long-range corrected hybrid functional (WB97X-D / Base 6-31G (d))clearly indicate that the formed complex is energetically preferred in both phases, and the inclusion complex in the orientation A is more favorable than in the orientation B and shows good compatibility with the experimental results. NBO and NCI analysis were performed on the β - CD / AZ complex to understand the different interactions. The 1H nuclear magnetic resonance (NMR) of the complex was studied using the Gauge-Including Atomic Orbital (GIAO).

In the present study, the capability of B12P12 nanocage to detect and deliver prothionamide (PA) drug in the presence of static electric field (SEF=0.005 to SEF=0.075 a.u.) and Be+2, Mg+2 ,and Ca+2 ions encapsulated inside B12P12 nanocage are investigated at cam-B3LYP/ 6-31G (d, p) level of theory by using Gaussian 09 package. The electrical, quantum, thermodynamic parameters, QTAIM (The quantum theory of atoms in molecules), UV-visible, IR spectra, and RDG (Reduced density gradient) of all considered systems are calculated. The AIM, RDG, LOL (Localized orbital locator) and ELF (Electron localization function) results show that the type of bonding between the drug and the nanocage is a sigma bond and electrostatic. The Be+2 ion has the greatest effect on the electrical behavior of nanocage and increases the conductivity, activity, and electron affinity of nanocage, which is very important in the interaction of nanocage with drugs. The Eads, ΔG and ΔH values of PA drug adsorption on the surface of Be+2@B12P12 nanocage are more than other models. The calculation results show that the static electric field does not play a significant role in the conductivity properties of nanocage and the preparation of a suitable drug sensor.

Density Functional Theory calculations, in the ground state of 2-Phenylbenzofuran, were carried out using the GGA-PBE, PBV86 and meta-GGA-TPSS hybrid functionals with 6-31G (d, p) as a basis set. First, theoretical calculations were performed using these functionals to obtain the stable conformer of the molecule. In addition, Mulliken population natural population and natural bond orbital analyses were calculated. The molecular electrostatic potential, band gap energies, global, local chemical reactivity descriptors and non-linear optical (NLO) properties were studied. Additionally, the NLO properties of 2-Phenylbenzofuran and those of its derivatives were investigated by GGA-PBE/6-31G (d,p) level of theory. The first-order hyperpolarizability value of all 2-Phenylbenzofuran derivatives was found within the range extending from 4.00 × 10-30 to 43.57 × 10-30 (esu). It indicated that they possess remarkable NLO properties. In addition, a multiple linear regression procedure was used to envisage the relationships between molecular descriptors and the activity of 2-Phenylbenzofuran derivatives; the quantitative structure-activity relationship (QSAR) studies were performed on them using quantum descriptors. The QSAR was applied to determine a correlation between the various physico-chemical parameters of the studied compounds and their biological activities. The statistical quality of the QSAR models was assessed using statistical parameters, i.e. R2, R2adj and R2cv.

Organic solvent or molecule directly interacts with water molecule then it shows a significant change in the stability of such solvent-water system. Polar organic solvent/molecule shows strong hydrogen bonding interaction in aqueous phase whereas nonpolar solvent shows very weak interaction. In organic solvent-water complexes, solvent plays very important role in the stability of such system, sometimes the solvent will interact with water molecule as proton donor or sometimes it will interact as proton acceptor mode. In gas phase, some common organic solvents may interact with water molecule through different ways and we try to investigate the relative stability and actual mode of interaction of such organic solvent(OS)-water complexes by using computational method. Solvent polarity also plays an important role in such organic solvent (OS)-water complexes; therefore, the effect of polarity on the interacting counterpart need to study by changing the dielectric constant of the solvent system and thus it is necessary to analyze the effect of solvent on such OS-water systems. The minute details of electron transfer pathway and donor-acceptor mechanism of such OS-water complexes have been studied by calculating single point energy and Natural Bond Orbital (NBO) analysis using MP4 methods.

In this work, graphene oxide/activated clay/Gelatin (GO/AC/G) composite blends were prepared by a simple solution mixing method. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were investigated to study the novelty in the structural characterization of the samples. The thermal stability was pursued by thermogravimetric analysis (TGA).The obtained results showed a homogeneous mixture was able to be formed between AC, GO, and G. XRD indicated a successful intercalated structure was created in the composites. The disappearance of montmorillonite and GO peaks at 2 = 8.1° and at 2 =13.5° respectively was observed, indicating the homogenous distribution of GO sheets onto activated clay structure. The interlayer spacing increased from 19.4 to 23.5 Å due to the insertion of gelatin molecules into the sheets of clay.The IR spectrum of (GO/AC/G) composite revealed the presence of C-O-C bonds, C=C bending, C-OH vibration, and C=O bending. These results suggested that GO had been composited with AC structure. Further, an intense band of N-H at 3419 cm-1 of gelatin was ameliorated through combination with absorption bonds of O-H, indicating the interaction of gelatin with the clay.A comparison of the thermograms of GO/AC and GO/AC/G showed that the thermal stability had been improved.

This study examines a kinetic model estimating the geranyl geranyl pyrophosphate (GGPP) concentration in the carotenoid pathway in tomatoes (Solanum lycopersicun). Kinetics of bioformation of carotenoids in tomatoes of different cultivars (Cherry-Nasmata, VAR-10, and 4-lobes) at different ripening stages and conditions was used to evaluate the GGPP concentration in the kinetic model. Physicochemical parameters, lycopene and beta-carotene contents were assessed and compared under the two ripening conditions using standard laboratory procedures. The solid contents in the three cultivars of tomato were in the range of 5.61% to 6.85% and 5.83% to 7.16% at field and ambient temperature ripening, respectively; the pH values were all in the acidic region. Highest lycopene and beta-carotene concentrations were observed in 4-lobes cultivar at field ripening. The obtained data from the empirical and kinetic modeling showed the exponential models as first-order kinetics for both lycopene and beta-carotene bioformation in Cherry-Nasmata and 4-lobes cultivars. This suggests that beta-carotene bioformation depends on the pathway of lycopene in the tomato cultivars. The quality parameters of the tomato cultivars showed that ripening conditions influenced the quality of tomato contents. Also the GGPP concentrations of some of the tomatoes were successfully estimated using the kinetic model.