Free Energy Values Research Articles

Exploring the potent corrosion inhibition properties of phenolic Schiff bases on mild steel in acidic environments, part A: coupling experimental and theoretical investigations.

In this study, we conduct a comparative investigation into the corrosion inhibition properties of two Schiff base compounds, namely 4,4'-((1E,1'E)-(ethane-1,2 diylbis(azaneylylidene))bis(methaneylylidene))diphenol (PSB5) and (1E,1'E)-N,N'-(ethane-1,2 diyl)bis(1-(4-nitrophenyl)methanimine) (PSB6), on mild steel in an acidic environment. The inhibitory efficiency and adsorption behavior of the inhibitors were assessed through electrochemical and gravimetric analyses. The inhibitors' deposition was further verified by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The findings of electrochemical tests demonstrate that these chemical compounds are potent inhibitors, with 96.5% inhibition provided by PSB5 at 10-3M. Therefore, PSB5 and PSB6 inhibitors are likely of mixed-form, as evidenced by changes in their Ecorr values of 59.8 mV and 33.0 mV, respectively when compared to the blank solution. Furthermore, the adsorption of these inhibitors onto the MS surface, as determined by the Langmuir adsorption isotherm, yielded free energy values of - 38.40 kJ mol-1 for PSB5 and - 35.20 kJ mol-1 for PSB6. These findings highlight a robust and spontaneous adsorption process for both inhibitors. Surface analysis using SEM-EDS revealed the preservation of the mild steel surface morphology and the adsorption of inhibitors. Theoretical investigations utilizing density functional theory (DFT) and molecular dynamics (MD) simulations supported and complemented the experimental findings. This research enhances the understanding of the corrosion protection potential of Schiff base compounds and their potential applications in various industries.

플라보노이드류의 하위 그룹을 구성하는 기본 분자들에 대한 양자 화학적 연구

A quantum study was carried out the structure and the characteristics of the basic molecules that constituting the subgroup of flavonoid i.e. flavan, flavanone, flavonol, anthocyanidine, flavone, isoflavone, and flavonol. We have reported and discussed the stable structure of isomers and physical quantities associated with the frontier energy, which are HOMO-LUMO energy difference, electronegativity, chemical potential, molecular hardness, softness, electrostatic potential, electrophilicity, electrodonating power and electro-accepting power. And we also have presented and discussed the physical quantities associated with the frontier orbital, such as frontier orbital figure, electrostatic potential diagram, polarizability, dipole moments etc., and also the values of free energy and entropy of each molecule obtained as a result of the vibration-rotation analysis The physical quantities reported and discussed are considered important data for understanding the reactivity, biological, pharmacological activity, and antioxidant properties of molecules belonging to flavonoid in the future

Argon Ion Implantation as a Method of Modifying the Surface Properties of Wood–Plastic Composites

Wood–plastic composites (WPCs) combine the properties of plastics and lignocellulosic fillers. A particular limitation in their use is usually a hydrophobic, poorly wettable surface. The surface properties of materials can be modified using ion implantation. The research involved using composites based on polyethylene (PE) filled with sawdust or bark (40%, 50%, and 60%). Their surfaces were modified by argon ion implantation in three fluencies (1 × 1015, 1 × 1016, and 1 × 1017 cm−2) at an accelerating voltage of 60 kV. Changes in the wettability, surface energy, and surface colour of the WPCs were analysed. It was shown that argon ion implantation affects the distinct colour change in the WPC surface. The nature of the colour changes depends on the filler used. Implantation also affects the colour balance between the individual variants. Implantation of the WPC surface with argon ions resulted in a decrease in the wetting angle. In most of the variants tested, the most significant effect on the wetting angle changes was the ion fluence of 1 × 1017 cm−2. Implantation of the WPC surface also increased the surface free energy of the composites. The highest surface free energy values were also recorded for the argon ion fluence of 1 × 1017 cm−2.

Appraising the corrosion inhibitory efficacy and adsorption mechanism of leaf extract of Datura discolor on low-carbon steel in low pH media via gravimetric experiments and AFM analysis

BackgroundThe study investigated the inhibitory action of Datura discolor leaf extract against the corrosion of low-carbon steel in 0.5 M solutions of three acids. The purpose was to ascertain the effect of extract concentration, immersion time and temperature variation on corrosion inhibitory efficiency, and to relate to existing reports which show that organic molecules in most plant extracts inhibit corrosion. Extraction of the leaves was done by maceration using methanol, and solvent was removed by evaporation to dryness. Classical gravimetric (mass loss) experiments were used, and experimental data were fitted to adsorption isotherm models to ascertain the best approximation. Surface examination of the low-carbon steel substrates was carried out using the atomic force microscope.ResultsInhibitory protective efficiency of extract was found to appreciate with increasing Datura discolor leaf extract concentration at a fixed temperature, with values ranging 77.6–88.8%, 91.35–98.08% and 19.64–44.64% in H2SO4, HCl and HNO3 solutions respectively at 27 °C. Elevation of temperature was found to depreciate the inhibitor efficiency at constant inhibitor concentration. Best isotherm model fitting was obtained with Langmuir model both at 27 °C and 60 °C and in all the hostile media, while Temkin model gave good approximation only at 60 °C and in H2SO4 and HCl solutions only. The negative values of free energy of adsorption (ΔGads0)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\Delta G_{{{\ ext{ads}}}}^{0} )$$\\end{document} suggested that the adsorptive interaction of the inhibitor with the substrate surface was very spontaneous. Values of ΔGads0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta G_{{{\ ext{ads}}}}^{0}$$\\end{document} were all consistent, fluctuating between − 16.35 and − 17.63 kJ mol−1 in both H2SO4 and HCl solutions, and between − 9.76 and − 10.25 kJ mol−1 in HNO3 solution, and this suggests that adsorption of the inhibitor molecules occurred via physisorption. Values of the activation energy of the corrosion reaction (Eact)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(E_{{{\ ext{act}}}} )$$\\end{document} are all < 40 kJ mol−1, suggesting that the inhibition occurred by a physical adsorption mechanism.ConclusionsThe study concludes that Datura discolor crude leaf extract suppressed the corrosion reactions, and the inhibition was found to arise from the physisorptive interaction of the organic molecules with the substrate/solution interface, forming a stabilize inhibitor film on the substrate surface as revealed by the atomic force micrographs.

Utilising date palm fibres as a permeable reactive barrier to remove methylene blue dye from groundwater: a batch and continuous adsorption study.

This study aimed to utilise cheap and abundantly available date palm fibre (DPF) wastes for the remediation of methylene blue (MLB) dye-contaminated groundwater. The DPF adsorbents were first prepared, followed by various characterisation analyses, including surface morphology, functional groups, and material structure. Subsequently, the DPF adsorbents were applied in the batch and continuous adsorption studies to assess the MLB dye removal from aqueous environments. The batch adsorption study achieved 98% maximum removal efficiency with a contact time, adsorbents dosage, initial pH, temperature, particle size, initial dye concentration, and agitation speed of 105min, 3g/L, 7.0, 45°C, 0.075mm, 50mg/L, and 150rpm, respectively. Langmuir was the best-fitted isotherm model depending on a higher correlation coefficient (R2 = 0.985), with a maximum monolayer dye adsorption capacity (qmax) of 54.204mg/g. Additionally, the second order was the best-fitted kinetic model (R2 = 0.990), indicating that MLB dye was removed through chemisorption. Besides, the positive enthalpy change (ΔH°) and negative Gibb's free energy (ΔG°) values verified the endothermic process and spontaneous adsorption. According to the impact analysis of initial dye concentrations and flow rates on the permeable reactive barrier (PRB) performance in the continuous adsorption study using the Thomas, Belter, and Yan models, the experimental results and predicted breakthrough curves reflected an excellent agreement (R2 ≥ 0.8767) and a sum of squared errors (SSE) ≤ 0.4834. In short, the results demonstrated DPF as an effective adsorbent material in PRB technology.

A Synergistic Interaction Between Citrus Hystrix Peel Essential Oil and Tetracycline and Evaluation of their Antibacterial Mechanism of Action in Vitro and in Silico Against Escherichia Coli.

Citrus hystrix essential oil (CHEO) have shown various pharmacological properties including antibacterial activity. This EO also possessed antibacterial effect against foodborne pathogens. There is less information available about the synergy interaction between CHEO and tetracycline, as well as their mechanism of action. Therefore, this study was conducted to evaluate the synergistic effect of CHEO and tetracycline against clinical isolate of Escherichia coli. Antibiofilm, bacteriolytic, and efflux pump inhibitor activities were also performed. The chemical composition of CHEO was analysed using GC-MS. Three major compounds, D-limonene (25.02 %), β-pinene (23.37 %), and β-sabinene (22.20 %) were identified. CHEO exhibited moderate antibacterial activity with MIC value of 250 μg/mL. The combination of CHEO (7.8 μg/mL) and tetracycline (62.5 μg/mL) produced a synergistic effect on E. coli with fractional inhibitory concentration index of 0.5. This mixture inhibited biofilm formation in E. coli. The combination of 7.8 μg/mL CHEO and 62.5 μg/mL tetracycline demonstrated bacteriolytic activity. In addition, the CHEO at 250 μg/mL showed a significant effect in inhibiting efflux pump. D-limonene has a binding free energy value of -20.13 kcal/mol with ompA transmembrane domain of E. coli. This finding indicates that CHEO has a potency to be developed as natural antibacterial against E. coli.

Adsorption Performance of Fe-Mn Polymer Nanocomposites for Arsenic Removal: Insights from Kinetic and Isotherm Models.

Global concern over arsenic contamination in drinking water necessitates innovative and sustainable remediation technologies. This study evaluates the adsorption performance of Fe-Mn binary oxide (FMBO) nanocomposites developed by coating polyethylene (PE) and polyethylene terephthalate (PET) with FMBO for the removal of As(III) and As(V) from water. Adsorption kinetics were rapid, with equilibrium achieved within 1-4 h depending on the material and pH. PET-FMBO and FMBO exhibited faster rates and higher arsenic removal (up to 96%) than PE-FMBO. Maximum As(III) adsorption capacities ranged from 4.76 to 5.75 mg/g for PE-FMBO, 7.2 to 12.0 mg/g for PET-FMBO, and up to 20.8 mg/g for FMBO, while capacities for As(V) ranged from 5.20 to 5.60 mg/g, 7.63 to 18.4 mg/g, and up to 46.2 mg/g, respectively. The results of the Dubinin-Radushkevich isotherm model, with free energy (Ea) values exceeding 16 kJ/mol, suggest chemisorption is the dominant mechanism, which is supported by the kinetics data. Given the effective removal of As(III), chemisorption likely proceeds through ligand exchange during the Mn oxide-mediated oxidation of As(III) and complexation with hydroxyl groups on the nanocomposite. These findings highlight the strong potential of Fe-Mn polymer nanocomposites, particularly PET-FMBO, for efficient arsenic removal during practical water treatment applications.

Reduction of carbon dioxide to methane and ethanol on the surface of graphyne-like boron nitride (BNyen) monolayer: A DFT study

Recently, scientists have created a novel type of boron nitride material known as BNyen. This material is similar in structure to Graphyne and has a higher N:B ratio than traditional boron nitride due to the addition of boron and nitrogen connecting segments within its units. This material has been studied for its potential as a photocatalyst for reduction of CO2 using DFT approaches. Optical and electronic attributes of BNyen suggest that it has a wider visible-light range and a band gap of 5.69 eV. By adding boron to BNyen, patial distributions of LUMO and HOMO indicate that π network has been extended, resulting in significantly greater photocatalytic efficiency. Upon the adsorption of CO2 on BNyen monolayer, the band gap significantly decreases, indicating a strong interaction between the BNyen and CO2. DFT computations were employed to explore the mechanism of CO2 reduction to a single carbon product catalyzed by BNyen. Based on the ΔG values, the optimized pathway for this reduction is from CO2 to CH4. Additionally, the potential formation of di-carbon products was considered, and based on the free energy values, CH3CH2OH is identified as the final di-carbon product. The Gibbs free energies for potential CO2 reaction pathways on BNyen were calculated, revealing that CO2 can be reduced to CH4 with a low limiting potential of −0.37 V and to CH3CH2OH with a low limiting potential of −0.57 V, both processes being powered by solar energy. In CO2RR, the competing hydrogen evolution reaction (HER) must be considered. The free energy of HER (ΔG = 0.96 eV) is significantly higher than the ΔG of the rate-determining steps for the mono-carbon product (0.37 eV) and the di-carbon product (0.57 eV) on BNyen. Therefore, BNyen effectively suppresses HER during the CO2RR process. This research can serve as a valuable guide for developing novel types of BNyen as appropriate photocatalysts for CO2 reduction reactions (CO2RR).

Adsorption of Chromium (VI) and Lead (II) in Synthetic Solutions Using Tamarindus Indica Fruit Peel

The problem of water pollution persists and, in some cases, has been getting worse since many of the industries that are currently installed in developing countries do not comply with established standards. In order to reduce water pollution, various environmental standards have been established that aim to regulate the introduction of contaminating agents into water and, thereby, control the degree of alteration of the quality of the vital liquid. Adsorption allows minimizing the generation of toxic waste and the recovery of the metal. The objective of the work was to study the bioadsorption of Cr (VI) and Pb (II) using the dry peel of &amp;lt;i&amp;gt;Tamarindus indica&amp;lt;/i&amp;gt;. We worked at different pH values and concentration levels. The determination of the chemical-physical parameters was carried out at the Empress Geominera Oriente. Adsorption isotherms were performed using the Langmuir, Freundlich and Dubinin-Radushkevich models, resulting in the maximum bioadsorption capacity of Cr (VI) and Pb (II) by biomass being 3.83 and 15.63 mg/g, respectively. reaching maximum removal percentages of 90.8%. The values of mean free energy of adsorption obtained from the Dubinin-Radushkevich model in Cr (VI) and Pb (II) were 10,000 kJ/mol, respectively, showing that, for these experimental conditions, the adsorption process is of a chemical nature.

Evaluation of tamoxifen analogues as potential estrogen receptor alpha inhibitors for breast cancer treatment: A computational approach

Estrogen receptors, particularly ERα, play a key role in breast cancer progression, making them prime targets for therapeutic intervention. Tamoxifen (TAM), a selective estrogen receptor modulator (SERM), has been widely used for the treatment of ER+ breast cancer; however, its clinical application is limited by side effects and the emergence of resistance. This study aims to identify and evaluate TAM analogues with improved efficacy and reduced side effects by employing molecular docking and molecular dynamics (MD) simulations. Droloxifene, endoxifen, and afimoxifene emerged as promising candidates, exhibiting strong binding affinities with ERα, as indicated by highly negative binding energy (BE) values in docking simulations. MD simulations further validated the stability of the complexes formed between these analogues and ERα, with low root mean square deviation (RMSD) values and stable radius of gyration (Rg) profiles. Root mean square fluctuation (RMSF) analysis revealed balanced flexibility, with droloxifene and afimoxifene showing optimized flexibility for stable binding. Hydrogen bond analysis indicated more stable interactions between these analogues and ERα compared to TAM, suggesting enhanced binding affinity. MM/GBSA binding free energy analysis confirmed the high affinity of these analogues, with droloxifene displaying the most effective binding free energy (ΔGtotal) value. ADMET profiling suggests that droloxifene and endoxifen have superior pharmacokinetic properties relative to TAM. Overall, droloxifene, endoxifen, and afimoxifene represent promising alternatives to TAM, with the potential for further clinical development in breast cancer treatment. Experimental validation in cell-based and in vivo models will be crucial in future studies to confirm their efficacy and safety profiles.

Nanoporous Metatitanic acid on γ-Al2O3 aerogel for higher CO2 adsorption capacity and lower energy consumption

Carbon dioxide capture has become an important issue in reducing atmospheric heat these days. In this study, adsorption of carbon dioxide by aerogel Gamma Alumina-Metatitanic Acid has been investigated and optimized. Morphological and structural analyses such as BET, FESEM, FT-IR, and XRD have also been conducted. In addition, Response surface methodology has been applied in order to achieve the optimal conditions, using a five-level Central composite design. The highest amount of adsorption, 12.874 (mmol/g), was recorded at a temperature of 20 (°C), pressure of 7 (bar), and 25 (%wt) of Metatitanic Acid. This was approximately 11.46% and 4.84% higher than those of mesoporous MgO and 4Azeolite, respectively. Regeneration of the adsorbent was also studied at different temperatures and process durations. Metatitanic acid, as a catalyst, reduces the temperature and regeneration time of the adsorbent by creating active sites and surface hydroxyl groups. It also lowers the required activation energy and enhances the thermal conductivity of the composite material. The optimal result was achieved at a temperature of 100 (°C) and a duration of 30 (min). Finally, isothermal and thermodynamic experiments were conducted to establish the most accurate predictive model and conditions, including Enthalpy, Entropy, and Gibbs free energy. The results indicate that the Freundlich model aligned well with the laboratory findings. Additionally, the negative values of Enthalpy, Entropy, and Gibbs free energy suggested that the adsorption process was physical, exothermic, and spontaneous.

Exploration of Pharmacological Mechanism of Cinnamomum tamala Essential Oil in Treating Inflammation based on Network Pharmacology, Molecular Modelling, and Experimental Validation.

Cinnamomum tamala (Buch.-Ham.) T.Nees & Eberm., also known as Indian Bay leaf, holds a distinctive position in complementary and alternative medicinal systems due to its anti-inflammatory properties. However, the active constituents and key molecular targets by which C. tamala essential oil (CTEO) exerts its anti-inflammatory action remain unclear. The present study used network pharmacology and experimental validation to investigate the mechanism of CTEO in the treatment of inflammation. GC-MS analysis was used to identify the constituents of CTEO. The key constituents and core targets of CTEO against inflammation were obtained by network pharmacology. The binding mechanism between the active compounds and inflammatory genes was ascertained by molecular docking and molecular dynamics simulation analysis. The pharmacological mechanism predicted by network pharmacology was verified in lipopolysaccharide-stimulated murine macrophage (RAW 264.7) cell lines. Forty-nine constituents were identified by GC-MS analysis, with 44 constituents being drug-like candidates. A total of 549 compounds and 213 inflammation-related genes were obtained, revealing 68 overlapping genes between them. Compound target network analysis revealed cinnamaldehyde as the core bioactive compound with the highest degree score. PPI network analysis demonstrated Il-1β, TNF-α, IL8, IL6 and TLR4 as key hub anti-inflammatory targets. KEGG enrichment analysis revealed a Toll-like receptor signalling pathway as the principally regulated pathway associated with inflammation. A molecular docking study showed that cinnamaldehyde strongly interacted with the Il-1β, TNF-α and TLR-4 proteins. Molecular dynamics simulations and MMPBSA analysis revealed that these complexes are stable without much deviation and have better free energy values. In cellular experiments, CTEO showed no cytotoxic effects on RAW 264.7 murine macrophages. The cells treated with LPS exhibited significant reductions in NO, PGE2, IL-6, TNF-α, and IL-1β levels following treatment with CTEO. Additionally, CTEO treatment reduced the ROS levels and increased the antioxidant enzymes such as SOD, GSH, GPx and CAT. Immunofluorescence analysis revealed that CTEO inhibited LPS-stimulated NF-κB nuclear translocation. The mRNA expression of TLR4, MyD88 and TRAF6 in the CTEO group decreased significantly compared to the LPS-treated group. The current findings suggest that CTEO attenuates inflammation by regulating TLR4/MyD88/NF- κB signalling pathway.

An innovative guanidinium-based ionic covalent organic frameworks with abundant aromatic rings for high-efficiency naproxen removal: Adsorption behavior, mechanisms, and density functional theory calculations

In recent years, naproxen (NPX) has raised significant environmental concerns requiring urgent attention. This study presents an innovative guanidinium-based ionic covalent organic framework (TFPB-TgCl), containing abundant aromatic rings, which was successfully synthesized via Schiff base reaction for the efficient and selective removal of NPX. Remarkably, TFPB-TgCl manifested a maximal NPX adsorption capacity of 308 mg/g at pH = 5. The adsorption on the active site (AOAS) model highlighted the simultaneous occurrence of both physical and chemical adsorption during the NPX uptake. The coefficients of the physical adsorption rates (5.6479, 1.9224, and 1.9224 min−1 for NPX concentrations of 20, 50, and 100 mg/L, respectively) were significantly higher than those of the chemical adsorption rates (0.1759, 0.0681, and 0.0567 g·mg−1·min−1 for the same concentrations), indicating the predominance of physical adsorption. Furthermore, the multilayer adsorption (MLA) model suggested that an adsorption site can interact with more NPX molecules, benefiting from various electrostatic and π-π interactions. The negative values of enthalpy change (ΔH° = −11.956 kJ/mol) and Gibbs free energy (ΔG < 0) confirmed the exothermic and spontaneous nature of the adsorption process. Additionally, in the optimal adsorption configuration (−131.57 kcal/mol), the Independent Gradient Model based on Hirshfeld partition (IGMH) was utilized to identify interaction sites between the guanidinium group of TFPB-TgCl and the carboxyl group of NPX, with subsequent electrostatic potential (ESP) analysis emphasizing their crucial role in electrostatic adsorption. Overall, the adsorption mechanism of electrostatic and π-π interactions in TFPB-TgCl highlights the significant contribution of its guanidinium and aromatic rings in facilitating NPX adsorption.

Insights into the Adsorption Mechanism of Chlorpyrifos on Activated Carbon Derived from Prickly Pear Seeds Waste: An Experimental and DFT Modeling Study

The removal of chlorpyrifos (CPF) from water was achieved using activated carbon (AC) derived from prickly pear seeds (PPS) wastes, developed through chemical activation with phosphoric acid. Several physico-chemical characterization methods were employed. The determination of surface functions using the Boehm assay indicated that the processed AC predominantly possesses acidic functions. The results obtained from the Boehm assay were corroborated by the pH value of the point of zero charge (pHpzc), which was equal to 2.5. Specific area calculation by the BET (Brunauer Emmett Teller) method revealed a large specific area (SBET) of 1077.66 m2 g⁻1. Adsorption experiments of CPF on AC demonstrated that the pseudo-second order (PSO) model and the Freundlich model were the most suitable for kinetic and isothermal modeling, respectively. The maximum CPF adsorption capacity of the PPS AC was found to be approximately 35 mg g⁻1. A theoretical study employing the density functional theory (DFT) was conducted using the B3LYP/6-311G (d, p) method. The most reliable adsorption energy (Eads) and Gibbs free energy (ΔGads) values between CPF and the functional groups on the AC surface were calculated. Results indicated a strong interaction between the lactone group of AC and CPF (ΔGads = -7.15 kcal mol⁻1, ΔEads = -21.55 kcal mol⁻1) and the hydroxyl group (ΔGads = -6.61 kcal mol⁻1, ΔEads = -20.66 kcal mol⁻1). This study demonstrates that activated carbon possesses significant adsorption power, making it highly effective for depolluting water contaminated by pesticides. The application of the theoretical DFT method enhances the understanding of the adsorption phenomenon of CPF on AC.

Применение моделей адсорбции при исследовании поглощения ионов никеля почвой

The aim of the presented work is to study the absorption of nickel ions by soils of the Udmurt Republic using four sorption models. Humus horizons (0–20 cm) of Albeluvisols Umbric, Leptosols Rendzinic and Phaeozems Albic soils widely distributed in Udmurtia were selected as objects of nickel adsorption research. According to the Langmuir model, good sorbents are characterized by high Amax values and low – KL, therefore, the best sorbent of nickel ions is Albeluvisols Umbric (Amax=0.0562 mol/kg, KL=2075.19 dm3/mol), and a weaker absorber is Phaeozems Albic (Amax=0.0192 mol/kg, KL=19474.48 dm3/mol), Leptosols Rendzinic occupies an intermediate position (Amax=0.0289 mol/kg, KL=14766.47 dm3/mol). The negative value of the Gibbs energy (∆G=–17.97 kJ/mol for Albeluvisols Umbric, –22.59 kJ/mol for Leptosols Rendzinic and –23.24 kJ/mol for Phaeozems Albic) indicates the spontaneous nickel adsorption by soil absorbing complex (SAC). In accordance with the Freundlich model, in all types of studied soils, the nickel ion – SAC binding energy decreases as the surface is filled, herewith the studied soils are characterized by heterogeneity of sorption centers. The approximation coefficient of the Temkin model is in the range of 0.80–0.85, therefore, the discrepancy between the experimental data of the theoretical model indicates the absence of interaction between the adsorbed particles. The Dubinin – Radushkevich model allows us to determine the nature of adsorption forces, as well as the value of the average free energy of adsorption: E=8,325 kJ/mol in Albeluvisols Umbric, 9.5477 kJ/mol in Leptosols Rendzinic and 9.6296 kJ/mol in Phaeozems Albic. Consequently, chemisorption is characteristic of all soils, and proceeds by an ion-exchange mechanism.

Studi Molecular Docking dan Evaluasi Farmakokinetik Senyawa Analog Pirazol Turunan Benzen-Sulfonilurea sebagai Inhibitor Enzim Aldose Reduktase and α-Glukosidase Menggunakan Pendekatan In Silico

The pyrazole scaffold modification in various chemical structures on several studies has shown various biopharmacological activities. This study aims to predict the potential inhibition of pyrazole analogs derived benzene-sulfonylurea (4A, 4B, 4E, 5A, 5C, 5D) against the α-glucosidase (3A4A) and aldose reductase (3RX2) enzymes based on a molecular docking approach using Molecular Operating Environment (MOE) 2020.0102 software and evaluate pharmacokinetic profile (ADMET). In this study, the six test compounds were obtained from previous studies that have been proven antihyperglycemic. The results showed that all the 3,5-disubstituted benzene-sulfonylurea derivative pyrazole analogs are predicted to have low inhibitory activity against the α-glucosidase enzyme. Further, all compounds showed good aldose reductase inhibitor activity and had lower binding free energy values ​​than tolrestat as the positive control (-6.82 kcal/mol). Compound 5C has the best potential inhibitory activity against the aldose reductase enzyme compared to the other test compounds, because it has the lowest binding free energy value (-8.76 kcal/mol) and interacts with important residues on the receptor forming four hydrogen bonds, namely the carbonyl group of SO2 with residues Trp111 and His110, and the carbonyl group of the amide with residues His110 and Tyr48, as well as 3 hydrophobic bonds, namely a pyrazole ring with residues Leu300, Trp219 and a furan ring with Phe122. ADMET properties of the compounds are also predicted. This information provides an opportunity for a 5C compound as an aldose reductase inhibitor agent to develop drug candidates with better and safer activities.

Network Pharmacology Integrated With Quantum‐Polarized Ligand Docking and Molecular Simulation Revealed the Anti‐Diabetic Potential of Curcumin

AbstractDiabetes mellitus is a chronic metabolic disorder affecting millions of people worldwide and causes serious complications such as diabetic nephropathy. Curcumin, a natural polyphenol derived from turmeric, has demonstrated antidiabetic, anti‐inflammatory, and antioxidant properties. However, the molecular mechanisms underlying curcumin's anti‐diabetic effects remain incompletely understood. This study employed network pharmacology, molecular docking, and simulation techniques to explore the potential targets, and key pathways of curcumin in the treatment of diabetes. Using SwissTarget prediction and Superpred databases, we predicted the molecular targets for curcumin, while diabetes‐associated genes were obtained from DisGeNet. We identified 60 common targets for curcumin in diabetes. Protein‐protein interaction (PPI) analysis revealed three sub‐networks and ten hub genes with AKT1, TNF‐α, EGFR, and STAT3 identified as key hub genes that could serve as potential biomarkers. Gene enrichment analysis indicated that these genes primarily regulate insulin resistance and other metabolic pathways. Quantum‐polarized ligand docking (QPLD) showed that curcumin establishes multiple hydrogen and hydrophobic interactions with the essential amino acids of these hub targets. Molecular simulation results demonstrated stable dynamic behavior, a compact structure, and variations in residue flexibility. Binding free energy calculations using MM/GBSA and MM/PBSA methods validate curcumin's strong binding to the potential targets. Total binding free energy using MM/GBSA ranged from −21.35 to −30.94 kcal/mol while MM/PBSA calculations showed total binding free energy values between −19.80 and −26.66 kcal/mol. Altogether, this study provides valuable insights into the molecular targets of curcumin in diabetes and lays the foundation for future advancements in diabetes treatment.

Nucleic acid binding affinity and antioxidant activity of N-m-Tolyl-4-Chlorophenoxyacetohydroxamicacid.

Hydroxamic acids represent a group of weak organic acids, both naturally occurring and synthetically derived, characterized by the general formula RC(= O)N(R'OH). In this study, we investigated the binding behavior of N-m-tolyl-4-chlorophenoxyaceto hydroxamic acid with calf thymus DNA (ct-DNA) and torula yeast RNA (t-RNA) through a combination of techniques including UV-visible spectroscopy, fluorescence emission analysis, viscometry, and computational simulations using AutoDock4 software. Our findings reveal that the mode of binding between the compound and the nucleic acids is consistent with intercalation. Competitive binding experiments demonstrated that the complex competes effectively with ethidium bromide (EB) for binding to ct-DNA/t-RNA, displacing EB from its binding sites. Additionally, the introduction of the compound into the DNA-EB system resulted in a quenching of fluorescence emission peaks. Analysis of absorption spectra indicated a red shift and hypochromic shift when the compound interacted with DNA, further supporting the intercalative binding mode. The calculated binding constant (Kb) value for the compound is 6.62 × 104M-1 and 5.40 × 103M-1 indicating a strong interaction with ct-DNA and t-RNA respectively. We determined the Stern-Volmer constants for ct-DNA and t-RNA as 9.96 × 104M-1 and 8.13 × 105M-1, respectively. The binding free energy values for ct-DNA/t-RNA were calculated to be -3.741 × 107 and -5.425 × 108kcal/mol, respectively. Viscometric studies corroborated the UV results, showing a continuous increase in relative viscosity of ct-DNA/t-RNA solutions with the addition of the optimal hydroxamic acid concentration. Furthermore, we assessed the antioxidant activity of the compound using DPPH-radical scavenging and β-carotene linoleic acid assays. Gel electrophoresis results demonstrated the compound's remarkable efficacy in preventing DNA damage. Collectively, all experimental evidence supports the conclusion that N-m-tolyl-4-chlorophenoxyaceto hydroxamic acid binds to ct-DNA/t-RNA through an intercalative mechanism, which is consistent with our molecular docking simulations.

A Method for Treating Significant Conformational Changes in Alchemical Free Energy Simulations of Protein-Ligand Binding.

Relative binding free energy (RBFE) simulation is a rigorous approach to the calculation of quantitatively accurate binding free energy values for protein-ligand binding in which a reference binder is gradually converted to a target binder through alchemical transformation during the simulation. The success of such simulations relies on being able to accurately sample the correct conformational phase space for each alchemical state; however, this becomes a challenge when a significant conformation change occurs between the reference and target binder-receptor complexes. Increasing the simulation time and using enhanced sampling methods can be helpful, but effects can be limited, especially when the free energy barrier between conformations is high or when the correct target complex conformation is difficult to find and maintain. Current RBFE protocols seed the reference complex structure into every alchemical window of the simulation. In our study, we describe an improved protocol in which the reference structure is seeded into the first half of the alchemical windows, and the target structure is seeded into the second half of the alchemical windows. By applying information about the relevant correct end point conformations to different simulation windows from the beginning, the need for large barrier crossings or simulation prediction of the correct structures during an alchemical simulation is in many cases obviated. In the diverse cases we examine below, the simulations yielded free energy predictions that are satisfactory as compared to experiment and superior to running the simulations utilizing the conventional protocol. The method is straightforward to implement for publicly available FEP workflows.

Application of sewage sludge derived hydrochar as an adsorbent for removal of methylene blue

Hydrothermal pretreatment (HTP) is used to convert biomass into hydrochar (HC) through the application of heat and pressure in a water-based medium. The HC has emerged as a promising material for various environmental applications including wastewater treatment, soil amendment, and carbon sequestration. In this study, the applicability of sewage sludge (SS) derived HC was tested as an adsorbent for methylene blue (MB) dye removal from wastewater. The HC was also subjected to chemical activation with KOH before the adsorption study. The HC samples were characterized for structural morphology and molecular functionalities using instrumental analysis. All the HC samples exhibited almost similar adsorption capacity (∼190 mg/g) for MB after 24 h of contact time (MB concentration = 200 mg/L, solution pH = 7 and adsorbent dose = 1 g/L). The equilibrium data could be adequately fit in Langmuir model equation. The negative value of free energy indicated favorable MB adsorption process. The study demonstrated that the SS derived HC can be recycled as adsorbent in wastewater treatment plant which is not only an environment-friendly approach but also may reduce cost of tertiary treatment at sewage treatment plant often required to remove emerging contaminants.