Site Of Attack Research Articles

Novel Small Molecule Derived from Hydroxy Naphthaldhyde as Potential Anti-Leukemia Agents: Spectroscopic, DFT, Docking Molecular and ADME/T Investigations

New ligand derived from hydroxy naphthaldhyde (LCAT1) was synthetized and the structure of the formed Schiff base was confirmed by various analytical and spectroscopic methods. Elemental analysis, mass spectrometry and NMR studies confirmed the structure of the ligand. Theoretical calculations (DFT) were performed to study the molecular structure, chemical reactivity and electronic properties of this ligand. This study shows good agreement with the experimental results obtained using infrared spectrometry and UV-visible spectrophotometry. The optimized structure has been used to perform the molecular docking studies. The homology modeling and molecular docking were investigated in order to check their anti-leukemia activities toward several leukemia cells. In addition, in silico ADME/T modeling was employed to evaluate absorption, distribution, metabolism, and excretion pharmacological parameters of the ligand. The DFT study indicates that the evaluated parameters, such as Mulliken charges and molecular orbitals, as well as the MEP results, are consistent with the localization of electrophilic and nucleophilic attack sites. Furthermore, the data indicate significant chemical reactivity associated with low kinetic stability of the ligand. In accordance with the principle of a 90% critical assessment, the homological modeling model used is considered to be the most appropriate. The molecular docking results indicated that our molecule has a strong affinity for DNA by forming hydrogen bonds with the donor’s groups and exhibits a good leukemia activity against cell lines through the formation of strong interaction with their receptors. The results showed high binding energy and remarkable inhibition constants toward receptors 5VOM (−8.03 Kcal/mol, 1. 31 µM), 1NJS (−7.68 Kcal/mol, 2.35 µM), 7JXU. In silico ADME/T modeling showed that the properties of the synthesized ligand are similar to those of the drugs. The predicted toxicity of the ligand reveals that LCAT1 is nontoxic, with no hepatotoxicity, no mutagenicity and no carcinogenicity.

Intermolecular interactions of Guanosine/β-Cyclodextrine and Guanosine-hydroxypropyl/β-Cyclodextrin inclusion complexes using DFT calculation

In this work the study investigates intermolecular interactions in Guanosine (Guo) into β-cyclodextrin (β-CD) and their derivatives, such as hydroxypropyl-βCD (HPβCD) inclusion complexes using Density Functional Theory including dispersion correction (DFT-D3) method using the following functional, B3LYP/6-31G basis set in both gaz and aqueous phases. These complexes geometries were optimized and the final results were examined and contrasted. The global chemical reactivity descriptors, the Fukui function, and the HOMO and LUMO energies were calculated. The TD-DFT method was used to determine the complexes absorption spectra.To forecast the reactive sites for electrophilic and nucleophilic attack, the molecular electrostatic potential was computed. The interaction bonds were investigated and the formation of conventional hydrogen bonds was detected by AIM analysis. The nature of the interactions was further elucidated using the method of non-covalent interactions (NCI). This showed that hydrogen bonds and van der Waals interactions contribute significantly to the formation of the inclusion complex. To gain more insight into the absorption and emission energies of the investigated complex, the gap energy (EHOMO-ELUMO) was calculated.

N, P co-doped graphite felt cathode for efficient removal of ciprofloxacin in an ascorbic acid-coupled electro-Fenton process: Simultaneously enhancing H2O2 generation and Fe3+/Fe2+ cycling.

To enhance the contaminant removal efficiency of the electro-Fenton (E-Fenton) process, a nitrogen and phosphorus co-doped graphite felt (NPGF) cathode was synthesized using an anodic oxidation technique. An ascorbic acid-coupled NPGF E-Fenton system was then established for the degradation of ciprofloxacin (CIP). The NPGF cathode featured abundant oxygen-containing functional groups (such as -COOH and -OH), which enhanced the selectivity of oxygen reduction and facilitated the formation of H2O2. The introduction of N and P doping disrupted the charge balance within the carbon framework, accelerating electron transfer. Together, the NPGF electrode and ascorbic acid enhanced the cycling of Fe3+/Fe2+ while preventing the formation of iron sludge. Under optimal conditions (ascorbic acid concentration of 0.3mM, current density of 2.0mAcm-2, pH of 3.0, aeration rate of 0.6Lmin-1, and Fe2+ concentration of 0.2mM), CIP was completely removed within 20min. The NPGF electrode exhibited excellent stability, maintaining 95.35% CIP removal even after 8 cycles. Analysis revealed that singlet oxygen primarily mediated the degradation of CIP, with its concentration measured at 1.23×10-7M. Density functional theory was used to analyze the characteristics and potential attack sites of CIP, enabling the proposal of plausible degradation pathways. Toxicity simulations and Escherichia coli growth inhibition experiments demonstrated a reduction in the toxicity of CIP and its intermediate products. This study offers a valuable reference for improving the efficiency of E-Fenton technology in antibiotic wastewater treatment.

Reactivity of three pyrimidine derivatives, potential analgesics, by the DFT method and study of their docking on cyclooxygenases-1 and 2

Three pyrimidine derivatives, namely 4-[4-(dimethylamino)phenyl]-6-(pyridin-4-yl)pyrimidin-2-amine (DMPN), 4-(4-aminophenyl)-6-[4-(dimethylamino)phenyl]pyrimidin-2-ol (DMPO) and 4-(4-aminophenyl)-6-[4-(dimethylamino)phenyl]pyrimidine-2-thiol (DMPS), with analgesic properties established by a QSAR study, were subjected to reactivity parameter studies using the DFT method, at the B3LYP/6-311++G(d,p) level of theory. Studies of the docking of these molecules to cyclooxygenases 1 (PDB ID: 5U6X) and 2 (PDB ID: 5F19) were also carried out using the CB-Dock online program. Reactivity parameter calculations revealed that the three derivatives are less stable to internal electron transfer, with the lowest energy gap ∆E ranging from 3.63 eV to 3.88 eV, compared with 6.03 eV for ibuprofen (IBP). These derivatives possess the lowest chemical hardnesses η from 1.81eV to 1.94eV versus 3.02eV for IBP and are better electrophiles than IBP with chemical electrophilicity index values ω from 3.20eV to 3.88eV versus 2.64eV for IBP. These derivatives possess greater chemical reactivity than ibuprofen. All three derivatives also feature electrophilic and nucleophilic attack sites. The docking results show that all three derivatives react with cyclooxygenases in the same areas of reactivity as most NSAIDs. These ligands are more active on COX-2 than COX-1, according to complex stability scores which are stronger with COX-2 than with COX-1. In addition, all three derivatives are more active on COX-2 than ibuprofen, with stability score values of -8.6 kcal/mol for DMPN, -9.2 kcal/mol for DMPO, -8.9 kcal/mol for DMPS and -7.6 kcal/mol for IBP. The DMPO ligand forms the most stable complex with COX-2. These three derivatives thus appear to be selective COX-2 inhibitors, with higher stability scores than ibuprofen. All three derivatives also have good absorption, distribution, metabolism and toxicity properties. They can therefore be used as drugs.

A Comprehensive Study of the Degradation of Veterinary Antibiotics by Non-Thermal Plasma: Computational, Experimental, and Biotoxicity Assessments

Water quality is threatened by numerous pollutants, among which antibiotics are of great concern due to their widespread use and unaltered excretion, leading to water contamination and fostering antibiotic resistance. To comprehensively address sustainable water remediation, herein, the susceptibility to non-thermal plasma degradation of two veterinary antibiotics (Oxytetracycline (OTC) and Lincomycin (LNC)) are compared in an integral approach, including computational analyses, plasma irradiation assays, and a byproduct toxicity assessment. The computational assessment was performed by evaluating the ionization potential (IP) obtained from Density Functional Theory calculations and determining the antibiotics’ susceptible sites for radical attack. Plasma irradiation achieved nearly complete degradation (~100%) of both compounds with the initial concentration of 1 mg L−1, while 60% degradation was observed when the starting concentration was 10 mg L−1. The mineralization rates were 21% and 31% for OTC and LNC, respectively. The degradation profiles followed similar trends, as expected from their comparable IP values. After treatment, the solution exhibited lower biotoxicity compared to the original antibiotics. Therefore, this work represents a step forward in addressing one of the key environmental challenges of our time and encourages further extending the analysis towards the remediation of water polluted with many other organic compounds.

Remarkable records of jaguars and Andean bears in northwestern Ecuador: Implications for human-wildlife conflicts

Jaguar populations (Panthera onca) on the Ecuadorian coast are critically endangered, with only a few dozen individuals remaining in the region. In some areas, no records have been documented for decades. Between November 2023 and January 2024, independent camera trap monitoring in northwestern Ecuador yielded evidence of the presence of a jaguar, marking a significant recovery after seven years of absence in Manduriacu and at least 15 years in Junín. The jaguar was observed moving through an area of approximately 25 km, traversing forested and human-altered zones. Furthermore, additional evidence from the Ecominga Foundation and the Cielo Verde community indicated the occurrence of livestock attacks, which aligns with the typical predatory patterns observed in jaguar behavior. The attack site was located approximately 8 km from where the jaguar was initially recorded, suggesting that both events refer to the same individual. In response, local authorities inspected the area and organized community workshops. Furthermore, an Andean bear was recorded in Manduriacu during the same sampling period, confirming the co-occurrence of both species in the area. The documented movement of this jaguar, along with the presence of other species, underscores the imperative need to continue research and conservation initiatives in the region. These initiatives will ensure the protection and coexistence of wildlife and human populations in this highly biodiverse region.

Construction of Cu-doped α-Fe2O3/γ-Fe2O3 hetero-phase junction composite and its photocatalytic performance

Chlortetracycline hydrochloride (CTC), a class of antibiotics, poses a significant environmental hazard, particularly in aquatic ecosystems. The advancement of highly efficient and readily recyclable materials for water treatment remains an important focus of research in environmental remediation. In this study, Cu-doped α-Fe2O3/γ-Fe2O3 hetero-phase junction materials were prepared by a solvothermal method and a controlled calcination process to enhance the photocatalytic degradation of CTC in water by Fe2O3. Experimental results indicate that the composite material has superior magnetic properties, with Cu2-α-Fe2O3/γ-Fe2O3, featuring a high specific surface area and small pores, showing the best CTC adsorption. The α-Fe2O3/γ-Fe2O3′s interlaced energy levels facilitate quick electron transfer, and copper ion addition optimizes electron paths, generating numerous oxygen vacancies. This, combined with the hetero-phase junction, boosts charge separation and migration. Among the samples tested, The Cu2-α-Fe2O3/γ-Fe2O3 composite demonstrated the most efficient photocatalytic performance, with a degradation rate of 90.19 % for CTC achieved under Visible Light Irradiation. The proposed second-order reaction rate constants were approximately 31.99, 10.07, and 4.48 times higher than those for α-Fe2O3, γ-Fe2O3, and α-Fe2O3/γ-Fe2O3, respectively. The material also demonstrates good degradation effects on other antibiotics (such as oxytetracycline, tetracycline hydrochloride, etc.). Moreover, the structural morphology of the sample remains stable after cycling. O2– and h+ are the main active species in the photocatalytic degradation process of CTC, while OH plays a secondary role. The possible degradation pathways were elucidated by calculating predicted free radical attack sites using density-functional theory (DFT) and by analyzing the products of the CTC degradation process. Additionally, the toxicity risk assessment indicates that the intermediate products have low toxicity and pose a minimal potential risk to the aquatic environment.

Determination the Anticorrosive Properties of Trimebutine Maleate for Aluminum Corrosion in 2M HCl Gravimetric and Quantum Chemistry Approaches

The present work evaluated the inhibition properties of (R,S)-2-(dimethylamino)-2-phenylbutyl 3,4,5-trimethoxybenzoate or trimebutine maleate (TM) in aluminum corrosion in 2M hydrochloric acid. Tests were carried out using gravimetric methods and density functional theory (DFT). The results indicate that trimebutine maleate is a good inhibitor of aluminum corrosion in 2M hydrochloric acid at low temperatures. Indeed, the inhibition efficiency of this molecule increases with increasing concentration and decreases with increasing temperature. For an inhibitor concentration of 5.2mM and at 298K, we obtained an inhibition efficiency of 93.61%. The adsorption process is spontaneous, exothermic and follows the Langmuir model. The activation parameters were calculated and analyzed. DFT at the B3LYP/6-311G (d.p) level was used to determine molecular parameters such as EHOMO, ELUMO, ΔE, η, S, μ , A, I, χ, ΔN, ω. These theoretical parameters showed that TM is highly reactive and can both donate and receive electrons from aluminum. They thus confirmed the good inhibition performance of the molecule studied. These parameters were used to explain the inhibition efficiencies obtained. Local selectivity was analyzed using Fukui functions and the dual descriptor to determine possible nucleophilic and electrophilic attack sites.

Solvents and their influence on electronic properties in IEFPCM solvation model, anticancer activity, and docking studies on (E)-2-((4-chlorobenzylidene) amino)phenol

The Schiff base (E)-2-((4-chlorobenzylidene)amino)phenol (4CL2AM) has been synthesized from 4-chlorobenzaldehyde and 2-aminophenol. Spectroscopic techniques like FTIR, Raman, UV, fluorescence, and NMR were used to characterize the synthesized compound. The experimental data well matched with the DFT method (B3LYP/cc-pVDZ basis set). The frontier molecular orbital (FMO), molecular electrostatic potential (MEP), and electronic spectra (UV–visible) analysis were conducted on three different solvents such as gas, DMSO, and water. The frontier molecular orbital (FMO) analysis calculated the HOMO-LUMO energy gap as 4.0109 eV, 4.0406 eV, and 4.0411 eV for the gas phase, DMSO, and water respectively. Molecular electrostatic potential (MEP), localized orbital locator (LOL), and electron localize function (ELF) analysis revealed positions of localized and delocalized orbitals as well as electrophilic and nucleophilic attack sites. The natural bond orbital analysis (NBO) predicted highest stabilization energy was 33.37 kcal/mol. The locations of the covalent and non-covalent interactions were investigated by density overlaps region indicator (DORI), interaction region indicator (IRI), and noncovalent interaction (NCI) analysis. Drug likeness and ADME analysis were investigated. In vitro, anticancer activity studies revealed against MCF-7 breast cancer cell lines. In the molecular docking study, the predicted lowest binding energy is −5.77 kcal/mol for the 6NLV-4CL2AM system.

Linking secretion and cytoskeleton in immunity- a case for Arabidopsis TGNap1.

In plants, robust defense depends on the efficient and resilient trafficking supply chains to the site of pathogen attack. Though the importance of intracellular trafficking in plant immunity has been well established, a lack of clarity remains regarding the contribution of the various trafficking pathways in transporting immune-related proteins. We have recently identified a trans-Golgi network protein, TGN-ASSOCIATED PROTEIN 1 (TGNap1), which functionally links post-Golgi vesicles with the cytoskeleton to transport immunity-related proteins in the model plant species Arabidopsis thaliana. We propose new hypotheses on the various functional implications of TGNap1 and then elaborate on the surprising heterogeneity of TGN vesicles during immunity revealed by the discovery of TGNap1 and other TGN-associated proteins in recent years.

Synthesis of new multi-functionalized Schiff base derivatives based on vanillic acid: Antimicrobial activity, photophysical, DFT calculations and in-silico study

The paper reports the synthesis of novel multi-functional Schiff base derivatives (S1-S7) via Steglich esterification, thoroughly characterized by standard spectroscopic methods (1H NMR, 13C NMR, FT-IR and Mass spectrometry) and elemental analysis technique. Density Functional Theory calculations (including FMOs’, MEP, IR and UV–Visible), photophysical, molecular docking simulations, and in-vitro antimicrobial assays were employed to study the structure and reactivity of synthesized compounds. The study highlights significant antimicrobial activity of certain derivatives, which aligns with computational predictions. UV–Visible study identifies various transitions like π→π*, n→π* occurring in the system aligning with the theoretical absorption spectra. Biological studies reveal that compounds S1, S2 and S5 exhibit significant potency for antimicrobial investigation correlating with the computational study. Further, the calculated HOMO-LUMO band gap for S1-S7 molecules (3.29 eV) suggest their insulating nature. Notably, MEP study shows negative electrostatic potential near nitro group and the positive potential near alkyl groups indicating preferable site for electrophilic and nucleophilic attack, respectively. Moreover, molecular docking was implemented to computationally screen the multi-functionalized Schiff base along with molecular dynamics simulation including MM-PBSA energy calculation in order to discover the reasonable physiological significance ensuring stability of binding interactions of relevant molecules.

Adsorption and removal of herbicide paraquat from aqueous solutions via novel bimetal organic framework: Kinetics, equilibrium and statistical surface modeling

This study examines the adsorption and removal of the herbicide paraquat in relation to a bimetal organic framework known as the Terbium/Palladium Metal-Organic Framework (Tb/Pd-MOF). Analysis of N2 adsorption/desorption isotherms, which were used to assess the properties of the Tb/Pd-MOF, revealed that the absorption of paraquat on Tb/Pd-MOF resulted in a reduction in pore volume, pore size, and surface area. Specifically, the pore volume decreased from 8.25 to 5.68 cm3/g, the pore size decreased from 11.34 nm to 8.92 nm, and the surface area decreased from 1456.61 to 1262.82 m2/g. The pore radius also decreased from 0.96 nm to 0.58 nm. Tb/Pd-MOF’s functional groups were identified through FT-IR, and the structure of the compound was confirmed using XPS. Various adsorption parameters including temperature, adsorbent dosage, pH, paraquat concentration, and contact time were studied. Density functional theory (DFT) was used to understand the electrical properties, reactivity, and morphology of paraquat. Results from the DFT analysis revealed that the electrophilic and nucleophilic attack sites aligned with the molecular orbitals (HOMO and LUMO) and MEP outcomes. The study found that Tb/Pd-MOF demonstrated a significant absorption capacity for paraquat, with adsorption data consistent with the Langmuir isotherm and pseudo-second-order kinetic models. The paraquat adsorption capability of Tb/Pd-MOF was determined to be 574.8 mg/g. Furthermore, chemisorption was identified as the primary form of adsorption, as indicated by the adsorption energy of 26.98 kJ·mol−1. The optimal conditions for achieving a high adsorption capacity were identified as pH 8 and 0.02 g of Tb/Pd-MOF. The temperature-dependent changes in the thermodynamic parameters ΔG°, ΔH°, and ΔS° indicated that the paraquat absorption onto Tb/Pd-MOF occurred spontaneously, was endothermic, and involved random processes. To optimize the absorption process, Response Surface Methodology and Box-Behnken design (RSM, BBD) were employed. These techniques enabled effective removal of paraquat from the Tb/Pd-MOF material. During chemisorption, the adsorbate and adsorbent form chemical bonds, while aromatic rings are involved in π-π bonding. Additionally, pore-filling occurs when the adsorbate fills the pores of the adsorbent, and electrostatic interactions result from the attraction or repulsion of charges between the adsorbate and adsorbent. As a means of eliminating paraquat from wastewater, Tb/Pd-MOF demonstrates significant potential due to its diverse absorption processes and high capacity for adsorption.

Adsorption sites and interactions of pigments in molasses-based distillery effluent on starch-based composites: Ternary competitive adsorption and theoretical calculations

The pigment present in molasses-based distillery effluent constitutes a primary factor influencing its degradation. Adsorption is an effective approach to eliminate pigment from wastewater. In this study, a cationic cassava starch (CCS) magnetic composite (CCS@Fe3O4) was prepared and used as adsorbents for the removal of undesirable pigments. The adsorption behaviors of caffeic acid (CA), gallic acid (GA), and melanoidin (ME) on CCS@Fe3O4 in the wastewater were investigated using single and ternary competitive adsorption systems. The equilibrium adsorption capacities of CA, GA, and ME on CCS@Fe3O4 were 197.04, 195.55, and 623.97 mg/g at the optimized conditions (0.3 mg/mL CCS@Fe3O4 dosage, temperature of 38 °C, and pH of 7). The adsorption kinetic model showed that chemisorption accounted for most of the adsorption of CA, GA, and ME on CCS@Fe3O4. The adsorption mechanisms of pigments on CCS@Fe3O4 were explored at the molecular level through quantum chemical calculations. The electrostatic potentials (ESP), average local ionisation energy (ALIE), and Fukui indices calculation indicated that the quaternary ammonium group in CCS@Fe3O4 was more susceptible to electrophilic reactions. The CC and benzene rings in CA and GA, and the COO- in ME, represent sites of attack for quaternary ammonium during adsorption. Furthermore, the competitive adsorption results, adsorption energy, and electron transfer data demonstrated that the adsorption capacity of CCS@Fe3O4 for pigments followed the order ME>GA>CA. Overall, the competitive adsorption mechanisms of CA, GA, and ME on CCS@Fe3O4 were unveiled, with quantum chemical calculations offering crucial insights into the adsorption process.

Single-atom Ru modified flake g-C3N4 enhances photogenerated electron transport for rapid degradation of tetracycline antibiotics: Non-radical mechanism and ecotoxicity studies

Design of green and low-cost single-atom catalysts (SACs) with high-performance is key to moving photocatalytic degradation of antibiotics toward applications. In order to achieve SACs for large-scale manufacturing, we prepared ultrathin flake carbon nitride (FCN) by low-energy-consuming physical knockout means, and also applied an in situ growth strategy with stable and easy-operating effect to anchor the Ru element on FCN in the form of single atom. Notably, in the PMS/Vis/0.5Ru-FCN system, the degradation rate of tetracycline achieved 100 % in just five minutes, with an apparent rate constant of 0.236 min−1. Ru-FCN exhibits selective and stable determination due to narrow bandgap, unique photoresponsivity and low photogenerated carrier complexation rate. Mechanism investigation reveal that Ru-N4 sites accelerated the electron transfer between Ru-FCN and PMS, while the low oxidation state of Ru elements reduced the risk for metal corrosion. DFT calculations predict the attack sites of reactive oxygen species. This work provides a rational explanation for the charge transfer and resistance to external disturbance by Ru single atom, and it also provides a new direction to enhance the efficiency of water treatment.

Interface and Defect Engineering in 3D Co3O4‐Ov/TiO2 to Boost Simultaneous Removal of BPA and Cr(VI) upon Photoelectrocatalytic/Peroxymonosulfate (PEC/PMS) System

AbstractThe combination of photoelectrocatalytic (PEC) and peroxymonosulfate (PMS) is an innovative strategy for environmental treatment. And fabricating a highly efficient photoelectrode is the most pivotal factor in PEC reactions. This study designs an advanced Co3O4‐Ov/TiO2 photoelectrode by a dual‐modification strategy encompassing interface engineering and defect engineering. The photoelectric characterization validates the synergy of oxygen vacancies and dual heterojunctions. Simulated electron density distribution and Kelvin probe force microscopy (KPFM) elucidate the charge transfer pathway between Co3O4‐Ov and TiO2. 1O2 and SO4 .− are confirmed to be primarily responsible for the BPA oxidation in PEC/PMS system by radical scavenger experiments and the EPR technique. And the attack sites of BPA are precisely identified based on the Fukui index. Furthermore, density functional theory (DFT) calculations testify that Co3O4‐Ov can improve the adsorption capacity of PMS and reduce the energy barrier of the reaction process, while XPS analysis showed Co3+/Co2+ redox couple can accelerate PMS activation. Enhanced anode oxidation can effectively promote cathode reduction and consequently Co3O4‐Ov/TiO2‐PMS/PEC system presents a superior removal of both pollutants within only 15 min with fast kinetics (0.15 min−1 for BPA, 0.29 min−1 for Cr(VI)). This work provides unique insight into designing a highly efficient PMS/PEC system for simultaneous pollutant treatment.

Insight in sulfadiazine degradation by peroxymonosulfate activated by polydopamine-derived nitrogen-doped carbon supported CoFe2O4: Co leaching inhibition and degradation enhancement

Heterogeneous catalyst-mediated sulfate radical-based advanced oxidation processes (SR-AOPs) showed excellent performance during antibiotics degradation. Spinel was a promising catalyst for SR-AOPs, but the secondary contamination due to metal ions leaching needed to be addressed. And the destruction of catalyst structure could lead to the reduction of catalytic activity and the difficulty of recovery. Thus, a novel nitrogen-doped carbon (NC)-supported CoFe2O4 (CoFe2O4@NC) was synthesized as the activator of PMS for sulfadiazine (SDZ) degradation under low Co leaching conditions. The consequences indicated that the CoFe2O4@NC/PMS system exhibited higher PMS decomposition efficiency and reaction stoichiometry efficiency than the bare CoFe2O4/PMS systems (CoFe2O4-180 and CoFe2O4-800), which in turn demonstrated a better SDZ removal performance. Under the condition of CoFe2O4@NC dosage 0.1 g/L, PMS concentration 0.5 mM, solution pH 6.8 and temperature 25°C, SDZ (20 mg/L) was almost completely degraded within 60 min. XPS analysis showed that the NC not only protected and stabilized CoFe2O4, but also provided additional active sites for PMS activation. During SDZ degradation, SO4•−, HO•, •O2− and 1O2 were involved in the reaction, among which SO4• and HO• made the main contribution. Meanwhile, CoFe2O4@NC could be recovered by magnetic separation, and showed great stability (Co leaching 0.852 mg/L) and reusability. In the fifth cycle experiment, 85.02 % SDZ degradation was obtained. Based on the detected intermediates (12 intermediates were identified) and DFT calculations, possible degradation pathways for SDZ in CoFe2O4@NC/PMS were proposed. The condensed dual descriptor indicated that the N7, N11, and C15 atoms on SDZ molecule were the main sites of electrophilic attack, which was consistent with the detected intermediates. The degradation of SDZ involved hydroxylation of NH2, cleavage of S−N and extrusion of SO2. This study explored the improvements made in NC support material to catalytic performance and resistance to dissolution of spinel, providing new insights for subsequent researches.

Effect of impact angle on hot corrosion resistance of abrasive water jet peened Ti-6Al-4V alloy

The effect of peening angle (10° to 40°) on NaCl induced hot corrosion behavior of Ti-6Al-4V alloy was evaluated at 750 °C for 100 h. Peening at higher impact angles progressively increases the surface roughness, number of sub-grains, magnitude of compressive residual stresses and hardness of the alloy. During hot corrosion, the surfaces of Ti-6Al-4Al, irrespective of the peened condition, develops oxide scales that contain oxides of Ti, Al and V. Hot corrosion rate, measured in terms of rate of mass gain and the rate constant, Kp, was highest for the unpeened alloy but decreased for surfaces subjected to AWJ peening. Surfaces peened at increasing impact angles have smaller mass gain rate and the one peened at the impact angle of 30° exhibited the lowest corrosion rate and a lowest Kp of ∼0.08 mg2/cm4/h. The surface peened at 40° is, however, not as corrosion resistant. The mechanism of corrosion was discussed in the context of corrosion products formed and the opposing influences of initial roughness and compressive residual stresses. While higher roughness promotes hot corrosion by facilitating sites for corrosive attack, higher compressive residual stresses retard the diffusion of corrosive species into the Ti-6Al-4V surface. Based on these discussions, the optimum impact angle for AWJ peening for imparting maximum hot corrosion resistance on Ti-6Al-4V was determined to be ∼30°.

Unveiling the Photodegradation Mechanism of Monochlorinated Naphthalenes under UV-C Irradiation: Affecting Factors Analysis, the Roles of Hydroxyl Radicals, and DFT Calculation

Polychlorinated naphthalenes (PCNs) are a new type of persistent organic pollutant (POP) characterized by persistence, bioaccumulation, dioxin-like toxicity, and long-range atmospheric transport. Focusing on one type of PCN, monochlorinated naphthalenes (CN-1, CN-2), this study aimed to examine their photodegradation in the environment. In this work, CN-1 and CN-2 were employed as the model pollutants to investigate their photodegradation process under UV-C irradiation. Factors like the pH, initial concentrations of CN-1, and inorganic anions were investigated. Next, the roles of hydroxyl radicals (•OH), superoxide anion radicals (O2•−), and singlet oxygen (1O2) in the photodegradation process were discussed and proposed via theory computation. The results show that the photodegradation of CN-1 and CN-2 follows pseudo-first-order kinetics. Acidic conditions promote the photodegradation of CN-1, while the effects of pH on the photodegradation of CN-2 are not remarkable. Cl−, NO3−, and SO32− accelerate the photodegradation of CN-1, whereas the effect of SO42− and CO32− is not significant. Additionally, the contributions of •OH and O2•− to the photodegradation of CN-1 are 20.47% and 38.80%, while, for CN-2, the contribution is 16.40% and 16.80%, respectively. Moreover, the contribution of 1O2 is 15.7%. Based on DFT calculations, C4 and C6 of the CN-1 benzene ring are prioritized attack sites for •OH, while C2 and C9 of CN-2 are prioritized attack sites.

Comparative study of CO adsorption on Au, Cu, MoO2 and MoS2 2D Nanoparticles

This study focuses on a comparative analysis of the electronic properties of triangular, irregular hexagonal, and octagonal 2D nanoparticles containing 10, 12, and 14 motifs, made of Au, Cu, MoO2, and MoS2. The investigation was carried out using density functional theory. The formation energies and vibrational frequencies demonstrate that the 2D nanostructure configurations can exist as stable structures. Edge atoms with lower coordination numbers than central atoms, are the preferred sites for CO adsorption. Using orbital-weighting dual descriptors calculated from Fukui functions enabled the identification of a majority nucleophilic attack sites in Au and Cu nanoparticles, while MoO2 and MoS2-based nanoparticles present almost as many electrophilic sites as nucleophilic sites. The charge transferred between the nanostructures and the CO molecule and the redistribution of the projected density of states were used to assess the strength of interfacial bonds and the nature of the fundamental interaction involved in the bonding.

Uncovering a general oxidation model of nitrogen-containing oxidant in N-heterocyclic carbene (NHC) catalyzed oxidative reactions of aldehydes

Predicting how oxidants interact with reactive partners to alter the oxidation mechanism is a significant challenge in carbene catalysis. In this study, we investigated several examples to address this issue. Using density functional theory (DFT), we explored N-heterocyclic carbene (NHC)-catalyzed oxidative [2 + 4] annulations of aliphatic aldehydes with α,β-unsaturated ketones, focusing on the role of nitrogen-containing oxidant. Our computational results reveal that a hydrogen-bonding bridge framework, formed during oxidation, is crucial for facilitating π···π stacking interactions between the oxidant and the NHC catalyst. These interactions significantly lower the oxidation energy barrier, enabling a facile hydride transfer. This mechanism was validated across other reactions involving different nitrogen-containing oxidants. Frontier molecular orbital (FMO) analysis demonstrates how the NHC catalyst lowers the cycloaddition energy barrier by altering the orbital overlap from shoulder-to-head to head-to-head. Additionally, this elucidates the origin of stereoselectivity by highlighting energy differences between two reacting components at cycloaddition transition states. The nucleophilic index further predicts the preferred ketone attack site. This work advances our understanding of oxidation mechanisms involving nitrogen-containing oxidants and offers valuable insights for designing potent organic oxidants in organocatalytic oxidative reactions.