Physical Chemistry Research
Volume:11 Issue: 2, Spring 2023

In the present article, a comparative study of the rheological characteristics of nano-lubricants based on Fe2O3, Al2O3 and ZnO nanoparticles is carried out. The base fluid used is 20W40 engine oil. The nanofluid samples were prepared in the solid volume fractions (0.25%; 0.50%; 0.75% and 1%). The measurements have been performed at different temperatures, ranging between 20 °C and 60 °C and at shear rates ranging from 100 s-1 to 300 s-1. The results obtained have shown that nanofluids based on Fe2O3 and ZnO nanoparticles exhibit a non Newtonian shear thinning behaviour while the nanofluid based on Al2O3 nanoparticle exhibit a Newtonian behaviour. The Al2O3/oil nanofluid has a lower dynamic viscosity than Fe2O3/oil and ZnO/oil nanofluids. The increase in temperature leads to a reduction of more than 80% in viscosity for all nanofluids. On the other hand, the increase of the nanoparticles volume concentration clearly improves the dynamic viscosity.

Preparation of the 5%Fe10%Mo/γ-Al2O3 oxidative desulfurization (ODS) catalyst and optimization the ODS operating conditions (the effect of oxidant and catalyst amount, different time and temperature of the ODS activity test) of light oil naphtha are the main targets of this research. At first, the 5%Fe10%Mo /γ-Al2O3 extruded catalyst was prepared by incipient wetness impregnation technique. The FeMo/γ-Al2O3 extruded catalyst was analyzed by N2-adsorption/desorption (BET), X-Ray Diffraction Inductively (XRD), Scanning Electron Microscopy (SEM), NH3-Temperature Programmed Desorption (NH3-TPD) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The ODS activity tests of the FeMo/γ-Al2O3 extruded catalyst was investigated by the ODS setup with light oil naphtha as feed with 250 ppm total sulfur. In order to reach the desired ODS operating conditions, different quantities of oxidant, catalyst, time and temperature of the ODS tests were examined with ODS setup and the total sulfur of each tests were recorded by Rigaku apparatus. The best ODS operating conditions was 1mL H2O2 as an oxidant, 1g FeMo/γ-Al2O3 extruded catalyst, 100 min and 50 ℃. The total sulfur of light oil naphtha reached to 45 from 250 ppm by this catalyst and ODS process

This study aims at the identification and quantitative determination of polycyclic aromatic hydrocarbons (PAHs) adsorbed on soot particles emitted by diesel engines, but also of their nitro derivatives "nitro-PAHs". The challenge is double: develop a Heat-reflux extraction (HRE) technique to selectively and quantitatively extract the targeted pollutants adsorbed on soot, and to analyze them at trace amounts. Extraction results using dichloromethane showed a modest improvement in the extraction of volatile PAHs (more than 80%) and heavy PAHs (10 to 20%). Among the other solvents tested, pyridine proved to be the best extractant, with 50% extraction of the heaviest PAHs. Combined with diethylamine, the extraction efficiency of heavy PAHs reached 90%, which proves the ability of the pyridine-diethylamine mixture to extract quantitatively all PAHs, alkanes and nitro-PAHs. Moreover, pyridine associated with 1% acetic acid allowed the quantitative extraction of heavy nitro-PAHs, which were only partially desorbed with previous solvents. In comparison, when extracting real soot directly from a diesel engine test bench, very high amounts of linear alkanes from C14 to C32 were obtained, but few PAHs : naphthalene, biphenyl, phenanthrene, anthracene and fluorine (0.31-4.84 µg.g-1) and nitrated derivatives: 1-nitronaphtalene, 2-nitrofluorene and 1-nitropyrene (0.97-1.78 µg.g-1).

In this work, we have synthesized new copolymers by modification ofcarboxymethylcellulose (CMC) with acrylamide and / or 4-vinylpyridine. These copolymers have been characterized by different methods namely, Infra-Red Spectroscopy (FTIR), thermogravimetric analysis (ATG) and X-ray diffraction (XRD). They were used as flocculants for the treatment of water suspensions containing bentonite and kaolin particles. Moreover, the effects of several factors, such as the pH, floculants concentration, suspensions concentration, and settling time, were investigated. The obtained results showed that the presence of 4-vinylpyridine (4VP) in the copolymer has a positive effect on the efficiency of turbidity elimination. It is worth indicating that for a settling time of 10 min, and for the CMC-AM-4VP copolymer, this efficiency reached the value of 89% and 75% for bentonite and Kaolin suspensions respectively.

The regularities of the behavior of the electrophysical properties of composite ceramic materials containing micro- and nanoparticles of nickel in the region of the percolation threshold have been studied. Regularities in the dependences of electrical conductivity, dielectric constant, thermal conductivity and thermo-emf of composite ceramic materials on the volume content of nickel particles have been revealed. When approaching the percolation threshold, the experimentally obtained dependences of the conductivity and static dielectric constant on the fractional content of nickel in these materials differ from the dependences calculated within the framework of the percolation theory in the fact that the dependence curve for the dielectric constant is similar to the curve for electrical conductivity. The origin of this discrepancy is explained by the formation of a continuous spatial structure from tunnel-connected conductors.

CdO-FePO4 composite nanopowders (CNPs) with V2O5 ions as dopants are prepared by a sol-gel technique. The as-synthesized CNPs are characterized by peak profile analysis of powder X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The powder XRD analysis reveals that the prepared products are crystalline with the cubic phase of CdO. The Debye-Scherrer’s method and Williamson-Hall (W-H) plot analysis are worn to find out the separate contributions of the size of the crystal lattice and microstrain on the peak broadening of prepared CNPs. The other relevant physical parameters like microstrain and dislocation density values are determined for all the XRD peaks related to the cubic phase of CdO between 10 and 80 degrees of 2-theta values. The morphological analysis and determination of mean crystallite size are done from TEM images. The estimated crystallite size values obtained from the XRD (W-H plot and Debye-Scherrer’s method) and TEM analysis revealed that the results are highly inter-correlated. The EDX spectra confirm the presence of elements Cd, Fe, P, V, and O in the prepared sample. FT-IR study exhibited functional groups related to phosphates and oxides.

The drug nano-vectorization is one of the objective priorities of modern medicine. A DFT study that concerns inclusion complexes between the anticancer drug cisplatin and boron nitrogen nanotubes (BNNTs) whose diameters vary from 7.35 to 12.87Ǻ is presented in this paper. The objective of the first part of the work was to highlight the different quantum phenomena that can control the chemical or physical absorption of cisplatin at the nanometric scale. The second part dealt with Nuclear Magnetic Resonance (NMR) studies that allowed the establishment of a relationship between the chemical shift (δ) of the central platinum (195 Pt) atom of the cisplatin molecule and the diameter of the used BNNT. This result can be used to monitor the concentration of cisplatin during drug filling and delivery. Finally, at a fixed diameter of the nanotube, we studied the influence of encapsulation of several cisplatin molecules and the solvent effect. We hope that this study will help in making an informed decision while choosing the diameter, the type, and length of nanotubes, based on the curative dose to be delivered to minimise drug toxicity.

The effect of substitution on some biologically active di- and tri-coumarins substituted 4-phenyl coumarins was investigated using absorption and fluorescence spectrum profiles. These studies helped in the estimation of excited-state dipole moments (μe) of coumarins by applying two renowned Solvatochromic shift methods Kawaski et al. and Ravi et al. Computational methodology was applied to find the ground state dipole moments (μg) and Onsager cavity of the coumarins from the optimized geometry of the molecules using DFT/B3LYP/6-31++ G(d,p) level of theory. The Mulliken charges, frontier molecular orbitals (FMO), and electrostatic potential surfaces (EPS) were theoretically generated utilizing their optimized geometries to validate the experimental findings. Time Dependent Density Functional Theory (TD-DFT) approach was applied to approximate the excitation energy, dispersion energy, cavitation energy, corresponding wavelengths, oscillator strength for different coumarins in gaseous phase in addition to benzene, ethanol and most polar aqueous medium. The large stoke’s shifts, and high μe values indicate that the intramolecular charge transfer (ICT) process occur in these coumarins which has coerced by an intense S0 → S1 electronic transition. The computational results were matched with the experimental analysis, and revealed characteristics electrical properties of coumarins, as well as confirming the presence of ICT in these coumarins.

In the current work, Thuja Occidentalis leaves carbon blended with Alumnium (TOLC@Al) was chosen as a precursor material for the As(V) adsorption from an aqueous solution. The parameters which influence the adsorption strength viz., pH, TOLC@Al dosage, contact period and initial arsenic concentration were studied. Characterization studies such as FTIR and SEM were performed to know surface morphology. The results demonstrate that TOLC@Al has a potential for the adsorption of arsenic ions (94.1% removal efficiency) at pH 6.00 under room temperature. Langmuir adsorption isotherm (R2= 0.9953) displayed the best fit.The maximum adsorption capacity (Qm) was obtained as 24.44 mg g-1 and adsorption favors uni-layered uptake. Kinetic study demonstrated that the pseudo-second-order model (R2= 0.9959) is the better fit and adsorption takes place through chemisorption. Regeneration studies reveal that the adsorbent is regenerated using sodium hydroxide solution and is reused for the adsorption of As(V). Higher absorption of As(V) ions was recorded with the TOLC@Al when compared to some other standard/ commercial adsorbents. Hence, TOLC@Al adsorbent can be a better material for As(V) ion removal.

Due to their diverse potentials, solar cells based on conjugated polymers have attracted attention over the past decades. In this study, ten poly(3-hexylthiophene) (P3HT) have been studied by performing computations based on density function theory and time-dependent density function theory with the increasing of molecular chains. The effect of the increasing of monomer numbers on the optoelectronic properties has been investigated, including molecular frontier orbitals (FMOs), molecular electrostatic potential (MEP), global reactivity descriptors, dipole moment, charge mobilities, and optical characteristics. The results demonstrate that M(n=3) has a smaller gap energy, best optical properties, and highest charge mobilities. We investigate the photovoltaic characteristics of novel donors using (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor. As a result, compounds M(n=1) to M(n=10) have an efficient electron transport from donor to acceptor. These outcomes suggest the possibility to test these engineered molecules in the laboratory, in order to improve organic solar cells (OSCs).

Nanoparticles materials with good structural properties can serve as an excellent candidate for the remediation of wastewater. In this study, mesoporous gamma-alumina was synthesized from kaolin using polyoxyethylene (40) stearate (PS) surfactant. The XRD diffractogram of the alumina revealed broad peaks that signifies small crystallites, while the FTIR spectrum indicates that the alumina possessed both tetrahedral and octahedral structure. The surface area, average pore diameter, and pore volume obtained from the N2-sorption study are respectively 76.0 m2/g, 4.4 nm, and 0.14 cm3/g. The XRF result revealed up to 98% Al2O3 composition, indicating a very high purity of the alumina. The alumina (Nano-Al) was applied for the adsorption of Eriochrome Black T dye, and the process optimized using RSM analysis by Box-Behnken Design (BBD) model. From the optimization results, the model's R2 (0.8736) value implies 87.36% on the percent dye removal could be due to the variation in the independent variable. While the F-value of 7.68 implies the model is significant. Consequently, 98.2% dye removal was achieved under the optimum conditions. This may be attributed to the enhanced structural properties of the Nano-Al. The experimental data were fitted to Langmuir isotherm, and the adsorption kinetics data were fitted to pseudo-second-order model.

The present work describes the adsorption of brilliant orange textile dye BO on treated clay TC and a new composite TC55 prepared by combining the TC and poly(4-vinylpyridine) (P4VP), a cationic polymer. The net negative structural charge of TC promotes high adsorption capacity toward cationic dyes. The preparation of composites by modification of minerals through compositing with polycations is used to enhance adsorption capacities for anionic dyes. Moreover, several factors’ effects, such as the contact time, pH of dye solution, adsorbent dosage, initial dye concentrations, and temperature, on the adsorption capacity were investigated. The results showed that TC55 fixed more dye molecules than TC. Afterward, the adsorption equilibrium time for TC and TC55 was 60 minutes. In addition, the kinetics of dye adsorption was found to follow the pseudo-second-order model, and the adsorption isotherm was very well described by the Langmuir model for all adsorbents. It is worth indicating that the adsorption capacities of TC and TC55 at 295 K and pH = 4.11 were 178 and 222 mg/g respectively. Indeed, the study of the temperature effect on the adsorption rate indicates that the reaction was endothermic. However, the values of the free energy showed that the adsorption was physisorption.

Sulfhydantoin from glycine or L-valine is used as a precursor via heterocyclic opening reactions. The operating conditions used during electrophilicity tests influence the reactivity of heterocycles, the best control of the electrophilicity of our molecules and consider as well as their use as enzyme inhibitors. The regioselectivity of the reactions carried out in various nucleophilic media leads to three new linear products derived from acetamide and butanamide and which are analogous to the peptide structures. The structures of the synthesized products 3-5 have been elucidated and confirmed by the usual spectroscopic methods. A theoretical study based on the DFT/PW6B95 method combined with the basic set 6–311 G (2d, p) was carried out to determine the structural and electronic parameters such as the energy parameters, the molecular electrostatic potential (MEP), the natural bonding of orbitals (NBO), non-covalent interactions (NCI) and 1H-NMR.

TRPV1 are ion channels capable of sensing different stimuli, integrating and translating them into signal language. TRPV1 antagonists have attracted much attention for the treatment of various diseases related to the management of pain physiology and neurogenic inflammation, such as anti-inflammatory, antineoplastic, and anti-nociceptive effects. Here, we performed a 3D-QSAR, molecular docking, and MD simulations on a novel series of indole triazole derivatives as antagonists of TRPV1. The aim was to design novel potent TRPV1 antagonists with strong inhibitory activity. The significant 3D-QSAR models showed a good correlation between experimental and predicted activity. CoMSIA was used to construct the best 3D QSAR model using the PLS method showing correlative and predictive ability (R2=0.985. Q2=0.788. SEE=0.105). Electrostatic, steric, and hydrophobic fields play an important role in the variation of biological activity. Molecular Docking analysis was used to validate the 3D-QSAR methods and to explain the binding site and interactions between the ligands and the receptor. Based on these results, a novel series of compounds were predicted. The pharmacokinetic properties of predicted compounds were analyzed by drug-likeness and ADMET prediction. The best-docked compounds were subjected to MD simulation to affirm the final candidate molecules' conformational to confirm their dynamic behavior and stability.

In this study, computational approaches were investigated on a thiazole derivatives as biofilm inhibitor agents. The 3D-QSAR model constructed presented a significant predictive capacity with statistical values R2 = 0.925, Q² = 0.538 for the CoMFA, and R2 = 0.905, Q² = 0.593 for CoMSIA. The predictability check was performed by external validation, which shows that the CoMSIA model strongly explains the inhibitory activity against biofilms. Based on the information generated by the CoMSIA model, we propose some candidates as a potent biofilm inhibitor. The mode of interaction was examined by molecular docking. The results obtained highlight the key amino acids involved in the ligand / protein interaction, and showing that the complexes bound to the designed compounds showed the best conformations in the active site. An ADMET study was carried out on the various compounds proposed to ensure their pharmacocentitics and bioavailability in the body. Moreover, the stability of the model was evaluated using MD simulations accompanied by calculating the binding free energy, DFT studies carried out to clearly describe the energy profiles of the studied compounds. All these results build an information base that can be invested in the design of thiazole-based biofilm inhibitors.

The objective of this work is to understand the potential of small natural dietary phytochemicals as inhibitors of cancer target enzymes. In this regard, Density Functional Theory (DFT) study and molecular docking analysis of five potential food phytochemicals e.g. crocetin (Cr), ellagic acid s(Ea), ferulic acid (Fe), dillapiole (Di), shogaol (Sh) have been performed. Also, two FDA approved anticancer drugs afinator and azacitidine were studied along with these molecules for comparison. The preliminary computational studies indicate the strength of these phytochemicals to bind strongly with the cancer target-DNA topoisomerase III beta. DFT studies are performed to understand the electronic structure and probable binding sites of these phytochemicals. Among the chosen five bioactive molecules, Cr is found to have the highest binding energy of -42.43 kcal/mol with DNA topoisomerase III beta. Although afinator drug has higher binding energy (-44.12 kcal/mol) than Cr, it has many side effects. Cr, being a natural compound with similar level of binding energy and less toxicity, is more appealing as a drug. The DFT analysis indicates Cr with lowest ionization energy, as the most reactive molecule

This review summarized the photo-oxidative degradation cause by ultraviolet radiation that led to break in the polymer chains, increases free radical and decreases the molecular weight. This can deteriorate the mechanical properties and affect the predicted life of materials. Although plastic has many benefits, there are many disadvantages including the toxicity of some materials that may leach and affect adversely the living organisms. The additives of the UV stabilizers have been categorized to absorbers or pigments which called UV screeners, hydroperoxide decomposer, excited state deactivators (quencher) and radical scavengers.UV radiation represents a very small proportion of sunlight but is the major cause of photodegradation of PVC and other polymeric materials. Photodegradation is irreversible and leads to permanent changes in the properties and performance of the polymeric materials.

The CuxOy-TiO2 nanocomposite was synthesized by a pulsed plasma-chemical method. Pulsed plasma-chemical synthesis was realized using a laboratory bench, which includes a TEA-500 pulsed electron accelerator and a reaction chamber. The structure of the composite was studied by X-ray phase analysis and transmission electron microscopy. The dependence of the geometric mean size, morphology, and phase composition of the composite on the molar ratio of reagents in the initial mixture, such as a reaction chamber, was revealed. The morphology of the particles of the CuxOy-TiO2 nanocomposite with the core/shell structure changes into spherical particles with a uniform porous structure. The phase composition with a predominant rutile phase changes to a mixture of several crystalline phases (anatase, rutile, copper chloride).

In this paper, ferromagnetic Fe2O3/Mn2O3 nanocomposites (Fe@Mn-1 and Fe@Mn-2) were synthesized and characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), vibration sample magnet (VSM) and transmission electron microscope (TEM). All results confirmed that the successfully synthesis of Fe@Mn-1 and Fe@Mn-2 nanocomposites with ferromagnetic property at room temperature with magnetic saturation of 6.48 and 9.24 emu/g, respectively. In addition, photocatalytic activities of Fe@Mn-1 and Fe@Mn-2 were studied on the degradation of methylene blue (MB) by applying H2O2 under visible light irradiation. The effect of important parameters on the MB degradation were evaluated and the results exhibited the best photocatalytic activity within 45 min owing to the Fe@Mn-1 (98%) and Fe@Mn-2 (97%), due to their very small crystallite sizes.

Biodegradable films for food packaging applications are one of the emerging materials researched extensively. This is due to their low cost, easy processing, inertness, eco-friendly and faster biodegradation. In this study, ZnO nanoparticles (ZnO-NPs) were selected (chemically stable) along with polyvinyl alcohol (PVA) matrix for biodegradable packaging. Here two concentrations of ZnO-NPs were studied i.e., 0.5wt% and 5.0wt%. In addition, the effect of such packaging was observed using grapes (Vitis-vinifera). This was followed by characterization using UV-Vis, SEM, XRD, and fruit quality. Results suggest enhanced stability of biofilms upon the incorporation of ZnO-NPs into PVA biofilms. Mechanical and physical properties were improved significantly. Also, application-wise; the Vitis-vinifera (grapes) were packed into such biofilms and subjected to observations to assess their quality (i.e., physical appearance, freshness, taste, and antimicrobial activity) for 15 days. It appeared very clear that the quality of grapes remained excellent at the designated duration, on the contrary degradation of such grapes was observed in terms of fruit color and decay rates within 3 days of exposure on controlled samples (without packaging at 6°C. However, at 5.0 wt%, the quality of grapes was excellent among all). Extensive discussion is presented on biofilm stability, associated properties, and fruit quality.