Free Energy Values Research Articles

Физико-химические трансформации сапонитсодержащего материала при его активации измельчением

Structural-phase transformations on the surface of powder systems of saponite-containing material after mechanical dispersion have been studied. The degree of crystallinity, adsorption capacity and specific surface energy depending on the time mode of grinding were used as compared information characteristics. It has been established that, despite the fact of the constancy of the degree of crystallinity, mechanical grinding of saponite-containing raw materials leads to its activation, which is expressed by a proportional increase in the sorption capacity of the obtained powders, an increase in the concentration of active adsorption centers and the value of the specific free surface energy. An increase in the time of mechanical grinding of a saponite-containing material leads to the production of samples with an increased (compared to the initial material) surface hydrophilicity.

Insights from in silico study of receptor energetics of SARS-CoV-2 variants.

The emergence of new variants of the novel coronavirus SARS-CoV-2 with increased infectivity, superior virulence, high transmissibility, and unmatched immune escape has demonstrated the adaptability and evolutionary fitness of the virus. The subject of relative order of the binding affinity of SARS-CoV-2 variants with the human ACE2 (hACE2) receptor is hotly debated and its resolution has implications for drug design and development. In this work, we have investigated the energetics of the binding of receptor binding domain (RBD) of SARS-CoV-2 variants of concern (VOCs): Beta (B.1.351), Delta (B.1.617.2), Omicron (B.1.1.529), variant of interest (VOI): Kappa (B.1.617.1), and Delta Plus (B.1.617.2.1) variant with the human ACE2 receptor by using the umbrella sampling (US) method. Our work indicates that Delta and Delta Plus variants have greater values of the US binding free energy than Wild-type (WT), whereas Beta, Kappa, and Omicron variants have lower values. Further analysis of hydrogen bonding, salt bridges, non-bonded interaction energy, and contact surface area at the RBD-hACE2 interface establish Delta as the variant with the highest binding affinity among these variants.

Sulphur-atom positional engineering in perylenimide: structure-property relationships and H-aggregation directed type-I photodynamic therapy.

An innovative design strategy of placing sulfur (S)-atoms within the pendant functional groups and at carbonyl positions in conventional perylenimide (PNI-O) has been demonstrated to investigate the condensed state structure-property relationship and potential photodynamic therapy (PDT) application. Incorporation of simply S-atoms at the peri-functionalized perylenimide (RPNI-O) leads to an aggregation-induced enhanced emission luminogen (AIEEgen), 2-hexyl-8-(thianthren-1-yl)-1H-benzo[5,10]anthra[2,1,9-def]isoquinoline-1,3(2H)-dione (API), which achieves a remarkable photoluminescence quantum yield (Φ PL) of 0.85 in aqueous environments and established novel AIE mechanisms. Additionally, substitution of the S-atom at the carbonyl position in RPNI-O leads to thioperylenimides (RPNI-S): 2-hexyl-8-phenyl-1H-benzo[5,10]anthra[2,1,9-def]isoquinoline-1,3(2H)-dithione (PPIS), 8-([2,2'-bithiophen]-5-yl)-2-hexyl-1H-benzo[5,10]anthra[2,1,9-def]isoquinoline-1,3(2H)-dithione (THPIS), and 2-hexyl-8-(thianthren-1-yl)-1H-benzo[5,10]anthra[2,1,9-def]isoquinoline-1,3(2H)-dithion (APIS), with distinct photophysical properties (enlarged spin-orbit coupling (SOC) and Φ PL ≈ 0.00), and developed diverse potent photosensitizers (PSs). The present work provides a novel SOC enhancement mechanism via pronounced H-aggregation. Surprisingly, the lowest singlet oxygen quantum yield (Φ Δ) and theoretical calculation suggest the specific type-I PDT for RPNI-S. Interestingly, RPNI-S efficiently produces superoxide (O2˙-) due to its remarkably lower Gibbs free energy (ΔG) values (THPIS: -40.83 kcal mol-1). The non-toxic and heavy-atom free very specific thio-based PPIS and THPIS PSs showed selective and efficient PDT under normoxia, as a rare example.

Enhanced adsorption of carbon sphere by doping with titania nanotubes for crystal violet removal: isotherm, kinetics, and thermodynamic studies.

In this study, the carbon sphere (Cs) has been prepared and modified by titania nanotubes (TNTs) to be utilized as an adsorbent toward crystal violet (CV) dye as a model for cationic dyes from aqueous solution. The prepared TNTs@Cs composites has been characterized by various techniques such as XRD, SEM, and TEM analysis. The adsorption analysis displayed that the adsorption capacity of CV dye onto the modified Cs with TNTs is 92.5 mg g-1, which is much higher than that achieved by pristine Cs (12.5 mg g-1). Various factors that influence the overall adsorption processes, such as pH, contact time, initial CV dye concentration, adsorbent weight, and temperature, were studied. The TNTs@Cs76.7 composite showed the highest removal percentage of 99.00% at optimum conditions. The adsorption isotherm analysis showed that the experimental data of adsorption CV dye fitted better with the Langmuir isotherm model with R 2 of 0.999, and the estimated maximum adsorption capacity was 84.7 mg g-1. On the other hand, the adsorption kinetic study showed that the adsorption of CV follows the pseudo-second order kinetic model with an equilibrium adsorption capacity (q e) of 10.66, 18.622, 47.61, and 48.31 mg g-1 for Cs, TNTs@Cs93, TNTs@Cs86.8, and TNTs@Cs76.7 composites, respectively. The thermodynamic analysis showed negative free energy (ΔG) values, this indicates that the adsorption of CV is a spontaneous and feasible process. Furthermore, the ΔH and ΔS are positive values that indicate an endothermic adsorption process. Furthermore, the prepared TNTs@Cs76.7 composite displayed remarkable adsorption stability and the removal efficiency of CV remains at 96.3% after five cycles.

Transition metal single-atoms supported on hexagonal ZnIn2S4 monolayers for the hydrogen evolution reaction.

Herein, we report a series of 5d transition metal (TM) single atoms supported on ZIS as promising catalysts for the hydrogen evolution reaction using first-principles calculations. The binding behaviors of TMs with the ZIS surface in single-atom catalyst formation are analysed using the adsorption energy (Eads), partial density of states (PDOS), charge density difference (CDD), and crystal orbital Hamilton population (COHP). The TM@ZIS (TM = Ta, W, Re, Os, Ir, and Pt) shows excellent hydrogen evolution performance with the Gibbs free energy (ΔGH*) values from -0.120 to 0.128 eV. The Tafel and Heyrovsky reaction mechanisms to drive H2 formation are also identified.

Cyclodextrin-enhanced photo-induced fluorescence of tau-fluvalinate, molecular modelling of inclusion complexes and determination in natural waters.

The effect of adding organized supramolecular systems such as β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) on the photochemically-induced fluorescence (PIF) spectral properties of tau-fluvalinate (TFV) in aqueous solutions was examined. The influence of pH, UV irradiation time and photoproduct stability on the cyclodextrin-enhanced photochemically-induced fluorescence intensity was also investigated. The spectral changes associated with the inclusion process yielded values for the formation constants of TFV inclusion complexes between 450 and 640 M-1, which were calculated using the nonlinear iterative regression approach least squares. In addition, host-guest interaction was clearly determined by PIF enhancement and a 1 : 1 stoichiometry was found for the β-CD and HP-β-CD complexes formed with TFV. The negative free energy (ΔG°) value indicated that the reaction of TFV with cyclodextrins was thermodynamically favorable. Furthermore, the structures of inclusion complexes of TFV with cyclodextrins were elucidated by 3-21G ab initio calculations. The limits of detection and quantification obtained ranged between 1.3 and 4.0 ng mL-1 and from 4.4 to 13.0 ng mL-1 in β-CD and HP-β-CD media, respectively. The analytical application in tap and river water samples yielded satisfactory mean recoveries ranging from 98.12 to 102.97%. Due to its sensitivity and ease of use, this method can be reliably applied to routine analysis.

Application of central composite design to optimization of Yellow Tartarazine and Methylene Blue environmentally clean adsorption by untreated walnut shells

Climate change poses a real threat to the water security by altering the precipitation patterns and other weather variables, desirability function (df) was used to determine the interactive effects and optimize with the Central Composite Design (CCD) of important variables such as initial dyes concentration (Co : 20–100 mg L–1), solution pH (1.5–11), temperature (20–60 °C) and adsorbent dosage (0.1–1.3 g L–1) for the removal of toxic Yellow Tartarazine (YT) and Methylene Blue (MB) onto Untreated Walnut Shells (UWS). The analysis of variance (ANOVA) was applied for the treatment of experimental data, fitted by a second-order polynomial equation and multiple regression analysis. The ideal conditions optimized according to the response surfaces are initial concentration (COyt = 60 mg L–1, pHYT = 1.5, DYT = 0.7 g L–1 and TYT = 40 °C for YT and (Co MB = 60 mL–1, pHMB = 8.5, DMB= 0.7 g L–1 and TMB = 40 °C for MB). Experimental confirmation allowed to accurately determine the maximum eliminations (76.15) for YT and (76.81%) for MB under optimal conditions. Several error analysis equations were used to measure the goodness of fit. Kinetic studies showed that the adsorption kinetic data are well modeled by a pseudo-second-order model. Among the different models used to fit the experimental isotherms, the Langmuir model gave the best correlation with capacities qmax of 55.55 and 50.00 mg/g, for YT and MB respectively at 40 oC. The effect of temperature on the adsorption isotherms allowed to arrive at the thermodynamic functions, the negative values of free energy ( ΔG°), enthalpy ( ΔH°) and entropy ( ΔS°) indicate a spontaneous and exothermic adsorption of physical nature, confirmed by the activation energy ( Ea) for both dyes. The elimination of pollutants by new-generation adsorbents has proven to be very effective by application of statistical methodology, Central composite design and the desirability function.

INTEGRATIVE BIOINFORMATICS APPROACHES TO THE UNDERSTANDING OF CHRISTININ MOLECULAR MECHANISM AS JANUS KINASE (JAK) INHIBITORS FOR SUPPRESSING HYPERINFLAMMATION IN COVID-19

COVID-19 is a significant worldwide health concern. The exaggerated immune response known as the "cytokine storm" is a key factor in this illness, and there are potential ways to address it. Janus kinase (JAK) inhibitors are a type of medication that might reduce inflammation and improve the body's production of antibodies. Pharmacokinetic profiles, toxicity characteristics, biological activities prediction, and molecular docking simulation will be conducted to discover, assess, and investigate the molecular interactions of Christinin compounds, including Christinin-A, Christinin-B, Christinin-C, and Christinin-D derived from Ziziphus spina-christi leaves as Janus kinase (JAK) inhibitors using bioinformatics approaches. Based on the molecular docking simulation, it can be concluded that the Christinin compound has a molecular interaction with Janus Kinase (JAK). However, Christinin-A and Christinin-C compounds have better affinity than Christinin-B and Christinin-D compounds, with binding free energy values of −7.59 kcal/mol and −5.37 kcal/mol, respectively. Therefore, these two compounds can be used as candidates for Janus Kinase (JAK) inhibitors in preventing hyperinflammation in the COVID-19 infectious disease

Computer-aided drug discovery of natural antiviral metabolites as potential SARS-CoV-2 helicase inhibitors

In our quest to discover effective inhibitors against severe acute respiratory syndrome coronavirus 2 helicase, a diverse set of more than 300 naturally occurring antiviral metabolites was investigated. Employing advanced computational techniques, we initiated the selection process by analyzing and comparing the co-crystallized ligand (VXG) of the severe acute respiratory syndrome coronavirus 2 helicase protein (PDB ID: 5RMM) to identify compounds with structurally similar features and potential for comparable binding. Through structural similarity and pharmacophore research, 13 compounds that shared important characteristics with VXG were pinpointed. Subsequently, these candidates were subjected to molecular docking to identify seven compounds that demonstrated favorable energy profiles and accurate binding to the severe acute respiratory syndrome coronavirus 2 helicase. Among these, mycophenolic acid emerged as the most promising candidate. To ensure the safety and viability of the selected compounds, we conducted ADMET tests, which confirmed the favorable characteristics of mycophenolic acid, and the safety of atropine and plumbagin. Building on these results, we performed additional analyses on mycophenolic acid, including various molecular dynamics simulations. These investigations demonstrated that mycophenolic acid exhibited optimal binding to the severe acute respiratory syndrome coronavirus 2 helicase, maintaining flawless dynamics throughout the simulations. Furthermore, the Molecular Mechanics Poisson–Boltzmann Surface Area tests provided strong evidence that mycophenolic acid successfully formed a stable connection with the severe acute respiratory syndrome coronavirus 2 helicase, with a calculated free energy value of −294 kJ mol−1. These encouraging findings provide a solid foundation for further research, including in vitro and in vivo studies, on the three identified compounds. The potential efficacy of these compounds as treatment options for coronavirus-19 warrants further exploration and may hold significant promise in the ongoing fight against the pandemic.

Modulation of the conformational landscape of the PDZ3 domain by perturbation on a distal non-canonical α3 helix: decoding the microscopic mechanism of allostery in the PDZ3 domain.

While allosteric signal transduction is crucial for protein signaling and regulation, the dynamic process of allosteric communication remains poorly understood. The third PDZ domain (PDZ stands for the common structural domain shared by the postsynaptic density protein (PSD95), Drosophila disc large tumor suppressor (DlgA), and zonula occludens-1 protein (ZO-1)) serves as a classic example of a single-domain allosteric protein, demonstrating a long-range coupling between the C-terminal α helix (known as the α3 helix) and ligand binding. A molecular level understanding of how the α3 helix modulates the ligand binding affinity of the PDZ3 domain is still lacking. In this study, extensive molecular dynamics simulations corroborated with principal component analysis (PCA), ligand binding free energy calculations, energetic frustration analysis and Markov state model analysis are employed to uncover such molecular details. We demonstrate the definite presence of a binding competent closed-like state in the conformational landscape of wild-type PDZ3. The population modulations of this closed state and other binding incompetent states in the landscape due to α3-truncation/mutation of PDZ3 are explored. A correlation between the closed state population and calculated binding free energy is established, which supports the conformation selection mechanism. Covariance analysis identified the presence of correlated motion between two distant loops (β1-β2 and β2-β3) in the wild-type PDZ3 system, which weakened due to truncation/mutation in the distant α3 helix. It has also been observed that whenever the α3 helix was perturbed, the β2-β3 loop got further away from the binding groove and it is found to be correlated with the binding free energy values. Energetic frustration analysis of the PDZ3 domain also showed that the β2-β3 loop is highly frustrated. Finally, MSM analysis revealed a relevant timescale (closed to open state transition), which is similar to the observed experimental signal transduction timescale for the system. These observations led to the conclusion that the distantly located α3 helix plays a pivotal role in regulating the conformational landscape of the PDZ3 domain, determining the ligand binding affinity and resulting in allosteric behavior of the domain.

Tuning the product selectivity of single-atom catalysts for CO2 reduction beyond CO formation by orbital engineering.

Electrochemical CO2 reduction (CO2R) is one of the promising strategies for developing sustainable energy resources. Single-atom catalysts (SACs) have emerged as efficient catalysts for CO2R. However, the efficiency of SACs for the formation of reduction products beyond two-step CO formation is low due to the lower binding strength of the CO intermediate. In this study, we present an orbital engineering strategy based on density functional theory calculations and the fragment molecular orbital approach to tune product selectivity for the CO2R reaction on macrocycle based molecular catalysts (porphyrin and phthalocyanine) and extended SACs (graphene and covalent organic frameworks) with Fe, Co, and Ni dopants. The introduction of neutral axial ligands such as imidazole, pyridine, and trimethyl phosphine to the metal dopants enhances the binding affinity of the CO intermediate. The stability of the catalysts is investigated through the thermodynamic binding energy of the axial ligands and ab initio molecular dynamics simulations (AIMD). The grand canonical potential method is used to determine the reaction free energy values. Using a unified activity volcano plot based on the reaction free energy values, we investigated the catalytic activity and product selectivity at an applied potential of -0.8 V vs. SHE and a pH of 6.8. We found that with the imidazole and pyridine axial ligands, the selectivity of Fe-doped SACs towards the formation of the methanol product is improved. The activity volcano plot for these SACs shows a similar activity to that of the Cu (211) surface. The catalytic activity is found to be directly proportional to the sigma-donating ability of the axial ligands.

Assessing the catalytic potential of novel halogen substituted carbene NHC (F, Cl, Br, I) catalysts in [3 + 2] cycloaddition reactions: A computational investigation.

This study investigated the catalytic behavior of NHC-X ligands (X = F, Cl, Br, I) in cycloaddition reactions, focusing on both mononuclear and binuclear pathways. Using NCI (noncovalent interaction), RDG (reduced density gradient), ELF (electron localization function), and LOL (localized orbital locus) computational analyses, the electronic interactions and stability of the ligands were examined. The results showed that NHC-Cl exhibited the least steric hindrance and strongest transition state stabilization, making it the most efficient catalyst. NHC-F also demonstrated strong stabilization, particularly in the binuclear pathway. In contrast, NHC-Br showed moderate efficiency, whereas NHC-I was the least effective owing to higher Gibbs free energy values and greater steric hindrance, especially in polar solvents such as water and acetonitrile. This study emphasizes the crucial role of solvent effects and thermodynamic factors in influencing the catalytic efficiency. These findings provide a framework for optimizing NHC-based catalysts for chemical transformations.

MW Assisted Synthesis of New 4,6-diaryl-3,4-Didhydropyrimidines-2(1H)-thione Derivatives: Tyrosinase Inhibition, Antioxidant, and Molecular Docking Studies

A number of new methoxy-substituted 4,6-diaryl-3,4-dihydropyrimidine-2(1H)-thiones (DH-Pyr-S, 17-28) were designed and synthesized by the reaction of methoxy-substituted chalcones (1–14) with thiourea using solid-phase microwave method (MW) in view of the structural requirements as suggested in the pharmacophore model for tyrosinase inhibition (TI). Synthesized compounds were assessed for their in vitro TI potential and compounds 16, 17, and 21 exhibited notable tyrosinase inhibitory properties at the concentrations of 31.86 ± 2.45 µM, 44.58 ± 0.46 µM, and 48.47 ± 0.66 µM, respectively. Compounds (16, 17, and 21) were exhibited experimentally more potent TI than the standard used in terms of the IC50 value (Kojic acid, 55.38 ± 2.30 µM; p<0.0001). Additionally, DPPH activity of 15-28 were evaluated and compound 17 showed the moderate DPPH activity (45.64 ± 0.34%). Binding affinities of synthesized molecules to the tyrosinase catalytic core were further investigated through in silico molecular docking studies using AutoDock Vina (version 1.2.5), discovery studio accelyrs (BIOVIA, Dassault Systèmes) and predicting small-molecule pharmacokinetic properties using graph-based signatures (pkCSM) programs were used for ADMET calculations. Among synthesized compounds 15, 21, and 24 revealed high binding affinity to tyrosinase active site with lowest binding free energy (ΔG) values of -7.9 kcal/mol, thereby outperformed kojic acid affinity. In conclusion most modeling results were in agreement with their experimental data, suggesting the TI potential of lead compounds.

Nanocages and nanotubes as catalysts for ORR and OER processes

The capacities, abilities and potential of Ni–C36, Ni–Al18P18, Co–C54, Co–Ge54, Co-CNT(7, 0), Co-GeNT(7, 0), Ni-CNT(10, 0) and Ni-AlPNT(10, 0) to use as catalysts of OER and ORR are examined by theoretical models. The adsorption energy, free Gibbs adsorption energy, overpotential and Gibbs free energy values of ORR and OER on used catalysts are compared with other metal catalysts. The Ni and Co atoms which are doped on nanotubes and nanocages are catalytic positions to adsorb ORR and OER species the and to process the reaction steps of OER and ORR. The Co-GeNT(7, 0) and Ni-AlPNT(10, 0) have lower overpotential than Ni–C36, Ni–Al18P18, Co–C54 and Co–Ge54. Finally, the Co-GeNT(7, 0) and Ni-AlPNT(10, 0) are suggested as catalysts with acceptable stability, high capacity to adsorb the species, lower over-potential and high performances by theoretical models.

Neurotransmitter amino acid adsorption on metal doped boron nitride nanosheets as biosensor: DFT study on neural disease prediagnosis system

In this study, pristine and iron (Fe), copper (Cu) and platinum (Pt) metal doped boron nitride nanosheet (BNNS) structures possibility of biosensor, adsorbent and neural disease prediagnosis system for gama amino butyric acid (GABA) and Glutamate (Glu) molecules were investigated by Density Functional Theory (DFT). Metal atoms were doped to replace both boron (B) and nitrogen (N) atoms of BNNS. All the adsorption energies on the structure were calculated as negative values for all structures after the GABA and Glu adsorption. The lowest adsorption energy and enthalpy values reached to − 42.1 kcal/mol and − 42.7 kcal/mol, respectively. According to Gibbs free energy (∆G) values of adsorption, most of the adsorption reactions can occur spontaneously. The charge transfer during adsorption happened from GABA and Glu molecules to BNNS structures. Based on the results, Fe-doped BNNS and Cu-doped BNNS could be utilized as electronic and work function type biosensors for GABA molecule and Glu molecule respectively. This study may lead to future biosensor studies, adsorption studies of neurotransmitter amino acids other than GABA and Glu, and BN nanostructure studies modified with different metal doping.

Atomic Diffusion Bonding in Air Using Oxide Films

Atomic diffusion bonding (ADB) of wafers is a promising process to achieve room-temperature wafer bonding [1]. For ADB processing, thin films are fabricated on two flat wafer surfaces using sputter deposition, with subsequent bonding of the two films on the wafers in vacuum. In addition to thin metal films [1], both oxide [2] and nitride [3] thin films are useful for bonding.For this study, after demonstrating ADB “in air” using oxide films, we compared the resultant bonding performance to that obtained using ADB “in vacuum” with the oxide films. Table 1 presents the surface free energy values at the bonded interface γ for quartz glass wafers bonded using 5-nm-thick Y2O3 film on each side. Using ADB in vacuum, great bonding strength was achieved for as-bonded wafers: the blade could not be inserted between the wafers. Using ADB in air, γ for as-bonded wafers was small, only 0.25 J/m2, but low-temperature annealing at 150 °C enhanced γ to 1.6 J/m2. At 200 °C, γ becomes greater than 2 J/m2. The annealing was conducted in air using a hot plate. Figure 2 portrays STEM cross-section images of Y2O3(5 nm)/Y2O3(5 nm) films (A) bonded in vacuum (as-bonded) and (B) bonded in air (annealed at 150 °C). The bonded interface is not visible in image (A). However, a slightly low-density bonded interface is partially visible in image (B). The difference of the bonded interface structure is consistent with that of γ presented in Table 1.Various oxide films such as TiO2, ITO, SiO2, and WO3 are useful for ADB in air, as is true also for ADB in vacuum, although post-bonded annealing at a low temperature of 150 °C is necessary for ADB in air to achieve γ greater than 1 J/m2. The bonding process of ADB in air is more convenient to execute than that in vacuum. Moreover, any mirror-polished wafer can be bonded using ADB in air, as is true also using ADB in vacuum. It is likely that H2O gas in air can adsorb on the fresh surface of oxide films efficiently and that well-hydrophilic films surfaces can be obtained easily when the deposited oxide films are removed from the vacuum chambers; in fact, low-temperature annealing at 150 °C enhanced γ remarkably. ADB in air using oxide films is useful for some applications if post-bonded annealing at low temperatures is acceptable for bonding processes. T. Shimatsu and M. Uomoto, ECS Trans., 33 (4), 61 (2010).T. Shimatsu, H. Yoshida, M. Uomoto, T. Saito, T. Moriwaki, N. Kato, Y. Miyamoto, and K. Miyamoto, Proceedings of Seventh LTB-3D 2021. p.51 (2021).M. Uomoto, H. Yoshida, T. Shimatsu, T. Saito, T. Moriwaki, N. Kato, Y. Miyamoto, and K. Miyamoto, Proceedings of Seventh LTB-3D 2021. p.45 (2021). Figure 1

Adhesion of methylene blue and malachite green to the surface of copolymer synthesized by grafting itaconic acid onto cellulose backbone – experimental and computational studies

This report describes the graft copolymerization of itaconic acid onto cellulose isolated from plantain trunk, using ammonium persulfate as initiator. Optimum grafting condition was established at 0.025 mol/L initiator concentration, 60 °C, 60 min grafting time and 3 g monomer mass. Characterization of the bio-materials indicated the success of the cellulose isolation and the grafting processes. At optimum grafting condition, about 34.0% grafting yield was obtained. With 25 mg of the co-polymer (PTC-g-IA), MB and MG uptake were 72.5 and 56.9 mg/g, respectively. These values represent about 2-fold sorption enhancement when compared with ungranted cellulose (PTC). The sorption process was influenced by solution pH, contact time, dye concentration and temperature. Modeling of the adsorption process indicated that the Pseudo-second-order kinetic model with R2 of unity and the Langmuir isothermal model (R2: 0.9622 (MB) and 0.9880 (MG)) best described the sorption process. Thermodynamic study described a feasible, spontaneous and exothermic process. Free energy value of 7.07 kJ/mol, and ΔH° values of < 20 kJ / mol , suggested a physisorption process. This was corroborated by the computational study which indicated non-covalent interactions between atoms in the dyes and the adsorbents. These interactions were stronger with the co-polymer. The interaction energies calculated for the dye-adsorbent interaction (-38.215, −52.868, −47.299 and −57.848 kJ/mol for PTC-MB, PTC-MG, PTC-g-IA-MB and PTC-g-IA-MG, respectively) show stronger interactions between PTC-g-IA and the dye molecules compared to pure cellulose in line with experimental observations. In overall, this study portrays the cellulose-based co-polymer as having the potential of easily removing MB and MG from wastewater.

Stabilization of whey lactoperoxidase using betaine: Spectroscopic and computational approaches

Lactoperoxidase (LPO) is a peroxidase with antibacterial properties. In the present study, lactoperoxidase was isolated and stabilized using betaine. Betaine enhanced optimal pH, enzyme native activity, and enzyme residual activity. Betaine reduced LPO fluorescence using a static quenching mechanism. The results showed that hydrogen bonding and van der Waals interactions were responsible for ligand-LPO binding. The negative values of Gibes free energy indicated that the binding of betaine to the LPO was spontaneous. The circular dichroism studies showed that the secondary and tertiary structures of the enzyme were altered in the presence of betaine. The results of thermal stability studies presented that betaine increased the enzyme Tm. Furthermore, the docking and MD investigations demonstrated that betaine might spontaneously attach to the LPO with hydrogen bonding and van der Waals interactions. Finally, betaine might be employed as an additive to stabilize lactoperoxidase for usage in the food and pharmaceutical industries.

DFT-ONIOM study of ammonia activation by MM'APO-5 (M,M' = Ti, Zr, Co) bimetallic molecular sieves. The influence of the neighboring metal from a theoretical point of view

ONIOM-DFT calculations have been carried out in order to determine how the neighboring metal influences the activation free energies (ΔG≠) and the mechanisms of NH3 activation in a series of mono and disubstituted aluminophosphates MM’APO-5, (M, M’ = Co, Ti Zr). The results revealed that metal clustering is thermodynamically favorable (ΔG < 0) for all MAPO-5s and MM’APO-5s studied here. The aluminophosphates TiAPO-5 and ZrAPO-5 are unable to activate NH3 due to their inability to stabilize the key intermediate MNH2. The calculated activation free energy values (ΔG≠) suggest that CoZrAPO-5 is better suited for NH3 activation, as its values are lower than those of CoTiAPO-5 in the mechanism studied.

Tetra-Coordinated W2 S3 for Efficient Dual-pH Hydrogen Production.

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) have emerged as promising catalysts for the hydrogen evolution reaction (HER) that play a crucial role in renewable energy technologies. Breaking the inherent structural paradigm limitations of 2D TMDs is the key to exploring their fascinating physical and chemical properties, which is expected to develop a revolutionary HER catalyst. Herein, we unambiguously present metallic W2 S3 instead of energetically favorable WS2 via a unique stoichiometric growth strategy. Benefiting from the excellent conductivity and hydrophilicity of the tetra-coordinated structure, as well as an appropriate Gibbs free energy value and an enough low energy barrier for water dissociation, the W2 S3 as catalyst achieves Pt-like HER activity and high long-term stability in both acidic and alkaline electrolytes. For application in proton exchange membrane (PEM) and anion exchange membrane (AEM) electrolysers, W2 S3 as the cathode catalyst yields excellent bifunctionality index (ɳ =1.73 V, ɳ =1.77 V) and long-term stability (471 h@PEM with a decay rate of 85.7 μV h-1 , 360 h@AEM with a decay rate of 27.1 μV h-1 ). Our work provides significant insight into the tetra-coordinated W2 S3 and facilitates the development of advanced electrocatalysts for sustainable hydrogen production.