Ismahene Ben Khemis

An advanced theory based on statistical physics was applied to microscopically investigate androstenone adsorption and its relationship with olfactory perception in chimpanzees and gorillas. For this purpose, dose–response curves of androstenone on olfactory receptors of chimpanzee OR7D4 and gorilla OR7D4 were analyzed by statistical physics. The two‐energy adsorption model fits the chimpanzee data well, and the gorilla data are best fit by the one‐energy adsorption model. The stereographic parameter analysis indicated that the studied pheromones were docked in a nonparallel manner in both species via a multimolecular mechanism. The analysis showed that the molecules interacted with different amino acid residues, resulting in distinct olfactory responses. The positive values of the molar adsorption energies indicate that an exothermic and physisorption process occurred in both olfactory systems. The docking analysis revealed that androstenone binds to the olfactory receptors of chimpanzees and gorillas through specific interactions with amino acid residues in the binding pockets. The docking results indicated distinct binding modes in each species, involving van der Waals, alkyl, and C–H interactions, which corroborated the energy trends predicted by the statistical physics model. These findings provided insights into the molecular mechanisms underlying the differential olfactory responses in chimpanzees and gorillas. Statistical physics was an excellent tool for evaluating and interpreting the interactions between androstenone and olfactory receptors.

Humans perceived rosy odorants, as well as other odorant molecules, through olfactory receptors that belong to the family of seven-transmembrane GPCRs. However, characterizing olfactory receptors remains a major challenge, largely due to the lack of X-ray crystallographic structures with high resolution. In this work, a theoretical statistical physics simulation and analysis, validated with molecular docking calculations, was applied to obtain deeper insight into human olfactory perception function by reducing the docking process to an adsorption one. Fitting results showed that human OR2A25 responded selectively to rosy odorants such as phenyl alcohol, geraniol, and citronellol. From a microscopic perspective, an advanced statistical physics characterization, based on a monolayer model with one adsorption energy (MM1E), provided a high degree of precision in characterizing and understanding the docking mechanism that cannot be obtained by experimental methods. Indeed, docking simulations revealed that the adsorption process involves binding energies 12.13 kJ/mol for phenyl alcohol-OR2A25, 10.04 kJ/mol for geraniol-OR2A25, and 8.78 kJ/mol for citronellol-OR2A25. Thus, these docking energy values obtained by molecular docking simulation were found to be slightly close to molar adsorption energies obtained by statistical physics modeling. From a macroscopic perspective, four thermodynamic functions, governing the mechanism of adsorption, were examined. The evolution of disorder during the proposed adsorption process was assessed through analysis of the configurational entropy. Moreover, the adsorption process involved in the three tested olfactory systems was found to be exothermic and spontaneous, as indicated by the values of the internal energy, enthalpy, and Gibbs free energy.

A monolayer model with three energies, developed based on statistical physics, was applied to analyze the adsorption mechanisms of sotolone and abhexone on the human olfactory receptor OR8D1. The first type of binding site played a dominant role in this food odorant mechanism, with OR8D1 binding sites arranged in non-parallel orientations, indicating a multimolecular process. Molar adsorption energies associated with the three types of binding sites, ranging from 23.75 to 32.97 kJ mol ^− 1 , demonstrated that the food odorants were physically and exothermically adsorbed on the human OR8D1 receptor.

The widespread use of antibiotics has globally become a significant concern due to their health and environmental impacts. Since the usual wastewater treatment methods are often ineffective for removing the majority of antibiotic residuals, other treatments are gaining considerable attention. This innovative study applies two theoretical approaches based on statistical physics modeling and density functional theory (DFT) to microscopically interpret the removal of amoxicillin (AXC) and sulfachloropyridazine (SCP) from aqueous solutions using an electrolytic carbon (EC) sample for water detoxification. Experimental data points are analyzed within the framework of two distinct theoretical models: real and ideal gas monolayer models. Based on modeling findings, model parameters have been successfully estimated and applied to investigate the details of the docking process of these antibiotics on EC at four temperatures (25, 35, 45, and 55 °C). Stereographic analysis revealed that the adsorbent pores preferentially capture the attached species with n > 1 at specific temperatures, suggesting a multimolecular mechanism with significant aggregation. The saturation adsorbed quantities of the EC adsorbent, determined by the monolayer models, are found to be 49.58-65.87 mg/g for amoxicillin and 33.28-71.52 mg/g for sulfachloropyridazine. These findings suggest that the adsorption performance of EC for the tested antibiotics is highly temperature-dependent, where the adsorbed quantities increase with the increase of this operating variable. Energetic analysis confirms the physisorption mechanism and the exothermic nature of the AXC/SCP on the EC surface, considering that the removal of these contaminants involves physical interactions. Both statistical physics and DFT theories show that at high temperatures the interactions of EC with SCP are higher than those with AXC. Overall, applying both theoretical approaches provides a consistent interpretation of the mechanism of adsorption at high temperatures.

To comprehend the olfaction process at a microscopic level, further elucidation of its multiple stages was essential. The content of this study served as an initial step towards achieving this goal via the examination of the adsorption of geosmin molecules on polar bear and camel olfactory receptors. The tested odorant, which is a common volatile sesquiterpenoid produced by microorganisms, was responsible for degrading the quality of various beverages, foods, and drinking water due to its unpleasant "earthy/musty" off-flavor. Indeed, the statistical physics modeling using the single layer model with two types of cavities was crucial to theoretically analyze the responsiveness of polar bear Ursus maritimus umOR11A1 and camel Camelus ferus cfOR11A1 to geosmin molecules. Indeed, fitting findings indicated that the values of the numbers of geosmin per binding cavity type 1 or 2 were lower than 1 for umOR11A1 (mixed orientations) and higher than 1 for cfOR11A1 (non-parallel orientations). The values of the molar adsorption energies relative to the two types of cavities, ranging from 10.97 to 21.69 kJ/mol, showed that process of adsorption was physical and exothermic. In addition, statistical physics modeling was also applied to theoretically characterize the two mammalian olfactory systems and quantitatively investigate the olfactory sensitivity. Additionally, a density functional theory (DFT) calculation incorporating the quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) have been conducted to enhance our understanding of the nature and types of forces contributing to the stability of the geosmin ligand. A docking study has been employed to elucidate the interaction mechanism between geosmin and both target receptors, Ursus maritimus umOR11A1 and Camelus ferus cfOR11A1, including a comparative description.

In this study, the experimental adsorption isotherms of 2,4-dichlorophenoxyacetic acid (2,4-DA) on peanut skin treated with sulfuric acid were analyzed under different temperatures and characterized by Fourier transform infrared spectroscopy. The adsorption mechanism was interpreted based on statistical physics theory using the homogeneous double-layer model with one energy (HDLM1E). The modeling results indicated that the removal of 2,4-DA molecules occurred through a multi-interactive adsorption mechanism at temperatures of 25, 35, and 45 °C (0.76 < n < 0.99). In comparison, at 55 °C, a monomolecular adsorption mechanism was observed (n = 1.00). At 25 °C, the adsorbent demonstrated excellent performance in the 2,4-DA removal, with a maximum capacity of 244.33 mg/g. The increase in temperature reduced the adsorbent’s performance in removing 2,4-DA molecules because it increased thermal collisions, which harmed the system. From an energetic point of view, the adsorbent showed less effectiveness in removing the herbicide at high temperatures, indicating an exothermic adsorption process. The surface adsorption energies ranged from 4.72 to 6.06 kJ/mol, indicating the predominance of a physisorption mechanism. Therefore, the adsorption process at low temperatures is essential for industrial applications to ensure efficient wastewater treatment. This result is possible using an adsorbent from peanut skin subjected to acid treatment. Finally, the creation of an adsorbent from acid-treated peanut (Arachis hypogaea) skin presents an excellent alternative, yielding exceptional results in removing the 2,4-DA herbicide.

Context This article suggests that the olfaction process can be simplified to an adsorption mechanism by utilizing the Machilis hrabei olfactory receptor MhOR5 as a biological adsorbent. The odorant molecules such as geosmin, linalool, and o-cresol were used as adsorbates. The aim of the present study is to provide new insights into the docking process of the tested odorants on MhOR5 using numerical simulation via an advanced statistical physics model to fit the corresponding response curves. Methods In the present work, an advanced theory based on statistical physics formalism is applied to understand and analyze the experimental dose-olfactory response curves of three odorant molecules on the Machilis hrabei olfactory receptor. Indeed, a monolayer model with four energy levels developed using the grand canonical ensemble was successfully applied to analyze the adsorption mechanism of geosmin, linalool, and o-cresol on MhOR5 through the interpretation of the different fitted parameters. Stereographically, it was found that geosmin, linalool, and o-cresol molecules were docked on MhOR5 binding pockets with nonparallel orientations (multi-molecular process) since all the numbers of the studied odorants adsorbed on one binding pocket were superior to 1. Energetically, the values of the molar adsorption energies ΔE_i (i = 1, 2, 3, and 4) related to the four types of binding pockets (varied between 6.18 and 18.43 kJ/mol) demonstrated that the three odorants were exothermically and physically docked on MhOR5 since all values of ΔE_i were positive and inferior to 40 kJ/mol. The proposed model may also be applied to calculate and interpret two thermodynamic potentials: the internal energy E_int and adsorption entropy S_a. Additionally, the physicochemical parameters may be used to stereographically and energetically characterize the heterogeneity of the insect MhOR5 surface. The docking simulation results demonstrated that the estimated binding affinities or energy score values (varied between 6.27 and 18.40 kJ/mol) were slightly similar to molar adsorption energy values and were included in the adsorption energy bands of the three adsorption energy distributions (AEDs).