Search Results (2,119)

Rock bolt reinforcement governs underground excavation stability through the combined effects of embedment depth, installation pattern, and interaction with the evolving stress and structural environment. Despite substantial advances across mechanistic, empirical, numerical, discontinuum, dynamic, and field-based research traditions, no unified framework currently integrates these approaches across geological and stress regimes. Current practice, therefore, relies on design methods calibrated within specific contexts, producing optimisation outcomes that are model-dependent, metric-sensitive, and not reliably transferable across site conditions. This review critically synthesises evidence from 30 peer-reviewed studies organised into six analytical categories: mechanistic confinement frameworks, empirical classification systems, numerical parametric investigations, discontinuum- and discrete fracture network (DFN)-based optimisation studies, high-stress and dynamic performance analyses, and field-based performance evaluations. The synthesis establishes three principal findings. First, optimal bolt embedment is stress-regime-dependent; plastic-radius-based design logic is appropriate under moderate static conditions but becomes insufficient under high stress or dynamic loading, where energy absorption capacity and controlled yielding govern performance. Second, in discontinuous rock masses, joint geometry and spacing dominate reinforcement effectiveness, shifting optimisation from uniform length selection toward pattern-specific alignment and multi-length configurations that outperform equal-length grids under DFN-controlled conditions. Third, numerical optimisation outcomes are sensitive to the choice of objective metric and modelling paradigm, such that bolt length and spacing recommendations cannot be transferred across analytical frameworks without explicit mechanism comparison. To integrate these findings, a unified conceptual framework is proposed based on regime classification using three dimensionless indicators: the bolt penetration ratio (Π₁ = L/r_p), which relates embedment to plastic zone radius; the structural interception ratio (Π₂ = S/S_j), which relates bolt spacing to dominant joint spacing; and the stress intensity ratio (Π₃ = σ_in situ/σ_cm), which relates in situ stress to rock mass compressive strength. These indicators identify whether confinement-dominated, structure-dominated, or stress-dominated behaviour governs stability, and direct design logic accordingly. The framework does not prescribe universal geometric thresholds; rather, it provides a structured classification pathway that integrates mechanistic and empirical evidence into a coherent and transferable design logic. Probabilistic validation incorporating geological variability, stochastic fracture network modelling, and iterative field calibration is identified as the necessary development path toward a statistically robust optimisation methodology. Full article

To enhance the mechanical properties of carbon-fiber-reinforced polymer composites (CFRPs), this study devised a novel three-dimensional web-like “rigid–flexible” surface modification strategy. The synergistic incorporation of carbon nanotubes (CNTs), polydopamine (PDA), and cellulose nanofibers (CNFs) constructed a “three-dimensional nanospider web” modulus transition layer. The modified carbon-fiber (CF-0.1%CNT-PDA-CNF) surface exhibits a three-dimensional network structure, with significantly increased surface roughness. The surface energy increased by 128.60% compared to the desized carbon fiber, thereby improving the wettability of the carbon-fiber surface. The results of both PeakForce-Quantitative Nanomechanical Mapping (PF-QNM) and EDS analyses indicate that a transition layer of a certain thickness initially formed at the interface. At the interface, the modulus exhibits a gradual gradient decrease from carbon fiber to epoxy resin, achieving more efficient stress transfer. The interfacial shear strength (IFSS, 95.71 MPa), interlaminar shear strength (ILSS, 73.19 MPa), tensile strength (701.08 MPa), and flexural strength (934.41 MPa) of the CF-0.1%CNT-PDA-CNF/EP composite material increased by 38.39%, 54.93%, 51.74%, and 64.98%, respectively, compared to the composite material made from desized carbon fiber. Through hydrogen bonding, covalent bonding, and π-π interactions, CNTs, CNFs and PDA formed a “rigid–flexible” transition layer with a modulus gradient at the CF-epoxy interface, achieving a significant enhancement in the mechanical properties of the composite material. Full article

Synthesis and characterization of porous polymeric monoliths as high-performance adsorbents for the removal of Acid Blue 113 dye from aqueous solutions is reported. High internal phase emulsion (HIPE) polymerization process was employed for the synthesis of polymeric-HIPEs (polyHIPEs) using 4-vinylbenzyl chloride (VBC) and divinylbenzene (DVB) as co-monomers. To optimize their adsorption properties by inducing micro/meso porosity and introducing cationic functionalities, the polyHIPEs were post-modified via a two-step procedure. The first step involves the Friedel–Crafts hypercrosslinking reaction using FeCl₃ as a catalyst, leading to high-surface-area materials, followed by cationic modification of residual chloromethyl groups with triethylamine to incorporate positively charged ammonium functionalities. The prepared polyHIPEs were characterized by Attenuated Total Reflectance-Fourier-Transform Infrared (ATR-FTIR), X-ray Photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller surface area analysis (BET), and Scanning Electron Microscopy (SEM). BET analysis verified the huge surface area enhancement from 10.1 to 614.5 m² g⁻¹ due to hypercrosslinking. The modified cationic adsorbent showed higher adsorption capacity (280.1 mg g⁻¹) compared to the non-functionalized analogue (110 mg g⁻¹) for anionic dye Acid Blue 113. Adsorption followed pseudo-second-order kinetics, suggesting chemisorption as the dominant mechanism. The adsorption mechanism was investigated via XPS, revealing that electrostatic interactions along with hydrogen bonding and π-π interactions are major contributors to this process. Full article

The extensive use of pesticides in modern agriculture has resulted in their persistent accumulation in environmental systems, posing significant risks to ecosystems and human health. Consequently, the development of integrated strategies for the sensitive detection and efficient removal of pesticide residues has become critically important. In this context, fluorescent inorganic–organic hybrid nanoparticles have emerged as versatile platforms owing to their tunable physicochemical properties and distinctive optical behavior. This review provides a comprehensive overview of recent advances in these hybrid nanomaterials for pesticide sensing and remediation. Particular emphasis is placed on the underlying photophysical mechanisms governing detection, including fluorescence quenching, Förster resonance energy transfer (FRET), inner filter effect (IFE), and photoinduced electron transfer (PET). In parallel, the role of interfacial interactions such as hydrogen bonding, electrostatic attraction, and π–π stacking in adsorption processes is critically discussed. Furthermore, these hybrid systems exhibit high adsorption capacities and rapid removal kinetics, enabling efficient pesticide elimination using both adsorption and catalytic degradation pathways. Overall, this review underscores the potential of fluorescent inorganic–organic hybrid nanoparticles as next-generation materials for sustainable environmental monitoring and remediation of pesticide contaminants. Full article

The co-occurrence of microplastics and antibiotics in aquatic environments has raised increasing concern because their interactions remain poorly understood. This study investigated the interactions between two co-existing aquatic pollutants, antibiotics and microplastics, by evaluating the adsorption of nine commonly detected antibiotics onto PET, PP, and HDPE microplastics. The microplastics were considered environmentally contaminants rather than adsorbents intended for water treatment. Adsorption kinetics, equilibrium isotherms, and multi-component competitive models were employed, while the effects of the microplastic size, dosage, and water matrix composition were also studied. The adsorption kinetics for most antibiotics were best described by the pseudo-second order model (R² > 0.90), with the modelling suggesting contributions from film diffusion. The Freundlich and multi-component Sheindorf–Rebuhn–Sheintuch (SRS) models represented the equilibrium adsorption, indicating heterogeneous and competitive adsorption behaviour. PET exhibited the highest adsorption capacity, reaching 0.80 mg/g for doxycycline and 0.75 mg/g for oxytetracycline at 2000 mg/L microplastic. The competitive adsorption suggested that aromatic and moderately hydrophobic antibiotics showed greater adsorption, while highly polar antibiotics exhibited weaker adsorption and greater displacement. Potential interactions included electrostatic interactions, hydrogen bonding, and π–π interactions. These findings provide insights into antibiotic–microplastic interactions and emphasise the roles of the polymer type, molecular structure, and environmental conditions in influencing antibiotic fate and transport in aquatic environments. Full article

To explore an alternative detection approach for the pesticide imidacloprid (IMI), this study repurposed the quinoline-benzimidazole fluorescent probe DQBM-B—previously developed for Co²⁺ recognition—and investigated its detection performance and interaction mechanism toward IMI in the aggregated state. The optimal working conditions of the probe were determined by optimizing key detection parameters, and the sensing performance and matrix compatibility were evaluated through selectivity tests and proof-of-concept spiked cucumber extract analysis. The DQBM-B aggregates interact with IMI synergistically through intermolecular hydrogen bonding and π–π stacking, which enrich IMI at the aggregate surface to create a local enrichment layer. The observed fluorescence quenching arises from the synergistic contribution of static quenching (due to ground-state complex formation) and the inner filter effect (IFE). Under the optimal conditions, the system exhibited a detection limit of 0.75 μmol L⁻¹ for IMI with favorable anti-interference ability. The matrix effect evaluation in cucumber extract demonstrated good recovery and precision, demonstrating the feasibility of the aggregation-regulated IFE strategy in complex food matrices. This study expands the application scope of the DQBM-B probe from metal-ion sensing to pesticide detection and provides a metal-free, aggregation-regulated strategy for the fluorescence detection of neonicotinoid pesticides. Full article

The sturdy and stable unique polyhedral structure of FeOOH nanoparticles facilitates stress and load transfer, thereby forming a tighter mechanical interlock at the carbon fiber–matrix interface. In this work, the FeOOH nanocrystal layer in situ grown on flexible carbon fiber cloth was rationally designed and fabricated through hydrothermal synthesis. Then, the non-covalent cation–π bond was constructed at the interface between the iron ion-loaded FeOOH nanoparticles and indole-based poly(hexahydrotriazine) (In-PHT). Owing to the collaborative effects of physical anchoring and chemical bonding, the resultant composite exhibited an outstanding tensile strength of 322 MPa, and the friction coefficient significantly decreased by 63% compared with the composites without FeOOH nanoparticles. Moreover, the resultant worn composite showed an excellent self-healing property owing to the introduction of polyethylene wax (PEW) with a low melting point, and the healed friction coefficient remained almost unchanged. Extensive analyses verify that the phase-separated structure and Fe³⁺–π interactions across multiscale interfaces achieve the combined advantages of wear resistance and durability for recyclable carbon fiber-reinforced poly(hexahydrotriazine) composites (PHT-CFRPs). Full article

The efficient development of heavy oil reservoirs is challenged by the high viscosity and poor mobility of heavy oil. Although multicomponent thermal fluid technologies involving heat, gas, and chemical agents have demonstrated potential advantages over conventional steam-based recovery methods, the microscopic synergistic mechanisms responsible for viscosity reduction remain insufficiently understood. Therefore, this study investigates the synergistic mechanisms by which heat, an alkane solvent (C₁₁H₂₄), and CO₂ reduce heavy-oil viscosity. Heavy oil from the Shengli Oilfield was selected as the research object, and rheological experiments were combined with molecular dynamics simulations to systematically analyze viscosity variations and their underlying microscopic mechanisms under different conditions. The experimental results demonstrate that increasing temperature significantly reduces heavy oil viscosity, and a characteristic transition in viscosity reduction behavior occurs at approximately 100 °C. At 90 °C, the addition 5 wt% oil-soluble viscosity reducer C₁₁H₂₄ decreases the heavy oil viscosity to 442.2 mPa·s, corresponding to a reduction rate of 83%. The solubility of CO₂ increases markedly with pressure, and at 30 MPa, the viscosity reduction exceeds 99%. The combined effects of these three factors exhibit superior viscosity-reduction performance. Molecular dynamics simulation results indicate that CO₂ and the viscosity reducer synergistically weaken the π-π stacking interactions of asphaltenes and resins in heavy oil, transforming heavy components from locally aggregated states into more uniformly dispersed configurations. Meanwhile, the intermolecular interaction energy and cohesive energy density decrease, indicating weakened molecular interactions and enhanced diffusion behavior. These results demonstrate that the synergistic viscosity-reduction mechanism of heat–gas–agent systems is mainly associated with structural disaggregation, interaction weakening, and diffusion enhancement. This study provides molecular-level insights into multicomponent thermal fluid-assisted heavy oil recovery and offers theoretical support for improving heavy oil development efficiency. Full article

Nonlinear optical (NLO) active chromophores and their applications in photothermal therapy (PTT) demonstrate great potential in modern theragnostics, owing to their efficient light–matter interactions. A recognized D–π–A chromophore, FTC-3f, which is reported to exhibit a high photothermal conversion efficiency (~51.11%), was structurally modified with various spacers and acceptors to elucidate enhanced PTT and NLO behavior through DFT and TD-DFT simulations. Molecular geometries were optimized at the B3LYP/6-31G (d, p) level. Their electronic properties, charge separation, and efficient transition pathways were analyzed using frontier molecular orbitals (FMOs), density of states (DOS), UV–visible spectroscopy, photon-induced electron transfer (PET), and transition density matrix (TDM) analysis. Among all the derivatives, D4 exhibited the smallest HOMO–LUMO energy gap (1.701 eV). The highest first-order hyperpolarizability (β) values are found for D4 (1.50 × 10⁵ in the gas phase, 7.40 × 10⁵ in water, 3.06 × 10⁵ in benzene solvent). The β_HRS is found to be in the range 5.11 × 10⁴ to 2.97 × 10⁴ and DR (3.65 × 10⁵ to 4.53 × 10⁴) supports the strong NLO response and strong synergistic donor–acceptor interactions. The designed chromophores exhibit much higher SHG and EOPE responses at 532, 1907.21, and 1064 nm than FTC-3F, indicating great potential for the synthesis of effective NLO nanomedicine. Molecular docking with bovine serum albumin (PDB ID: 4F5S) and Bcl-2 (PDB ID: 2W3L) suggested favorable binding conformations, consistent with a potential for transport and apoptotic-targeting behavior. All 3D molecular descriptor parameters indicate that the designed chromophores have potential for preferential targeting in PTT. This study investigates how structural modifications of donor–π–acceptor chromophores influence their electronic, optical, nonlinear optical, and theragnostic properties, providing insights into molecular design strategies for advanced NLO-based nanomedicine applications. Full article

Hydrogels are highly hydrated polymeric soft materials that closely mimic the mechanical characteristics of biological soft tissues, offering immense promise for biomedical applications such as tissue engineering, drug delivery, flexible electronics, and wound repair. Conventional hydrogels crosslinked by static covalent bonds suffer from irreversible network disruption upon mechanical damage and lack active responsiveness to environmental stimuli, severely limiting their practical use. Incorporating both dynamic covalent bonds and dynamic non-covalent interactions endows hydrogels with intelligent features, including self-healing, injectability, and stimuli responsiveness. A single dynamic crosslinking mode often fails to achieve an optimal balance between mechanical robustness and rapid dynamic reversibility, whereas the synergistic integration of multiple dynamic bonds—exploiting their complementarity in kinetics, energy dissipation, and stimuli-responsiveness—has emerged as a cutting-edge strategy to overcome this limitation. Using dynamic non-covalent interactions as the classification framework, this review systematically summarizes recent advances in hydrogels crosslinked by combinations of dynamic non-covalent interactions with dynamic covalent bonds, covering hydrogen bonds, host–guest interactions, metal–ligand interactions, electrostatic interactions, hydrophobic interactions, π–π stacking interactions, and other emerging multiple dynamic crosslinking systems. The design principles, synergistic mechanisms, multifunctional applications, and key challenges and future directions of each system are discussed and prospected. Full article

Herein, we report an unexpected pseudo-multicomponent transformation discovered during attempts to selectively nitrate the pyridine core of 3-acetyl-2,4,6-trimethylpyridine (3). Despite employing standard nitration conditions, including KNO₃–H₂SO₄ and HNO₃–H₂SO₄ mixtures, electrophilic substitution of the aromatic ring did not occur. Instead, the reaction sequence promoted an in situ nitrozation, dehydration to nitrile oxide intermediates, and subsequent [3+2]-cycloaddition involving two substrate molecules. This process yielded a novel, highly functionalized furoxan derivative, precisely identified as 3,4-bis(2,4,6-trimethylnicotinoyl)-1,2,5-oxadiazole 2-oxide (5). The molecular architecture of compound 5 was established by ¹H and ¹³C NMR spectroscopy, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction (XRD) analysis. To elucidate the stereochemical and electronic features governing compound 5, DFT calculations were performed at the ωB97X-D/6-311++G(d,p) level of theory. The experimental crystallographic disorder of the N-oxide oxygen atom was computationally rationalized by the thermodynamic near-degeneracy (ΔG < 0.63 kcal/mol) of two orientational isomers (5a and 5b). Furthermore, frontier molecular orbital analysis within the framework of perturbation theory accounted for the head-to-tail regioselectivity during cyclization, while wide energy gaps (ΔE = 8.13–8.27 eV) and high chemical hardness (η = 4.07–4.14 eV) underscored the kinetic stability of the heterocycle. Phenotypic and target-specific in silico profiling using PASS Online identified Matrix Metalloproteinase-9 (MMP-9) as a relevant target for potential hemorheological and cardioprotective applications. Validated molecular docking simulations across three human MMP-9 crystallographic domains (PDB: 8K5Y, 6ESM, 4XCT) demonstrated competitive binding affinities and balanced Ligand Efficiency metrics (LE = 0.26–0.29 kcal/mol/heavy atom), anchoring compound 5 within the catalytic pocket via conventional hydrogen bonds and π-mediated interactions. Finally, in vitro evaluations using a blood hyperviscosity model confirmed significant hemorheological efficacy, as compound 5 effectively prevented the rise in blood viscosity, outperforming the reference drug pentoxifylline. The convergence of computational insights and experimental functional activity establishes this novel bis(nicotinoyl)furoxan framework as a promising candidate for further hemorheological and cardioprotective applications. Full article

Low-cost adsorbents derived from agricultural and livestock waste offer a sustainable approach to wastewater remediation. In this study, a material derived from cow dung ash (SMCDA) was prepared through a simple waste-valorization route without chemical activation and evaluated for the removal of methylene blue (MB) from aqueous solution. X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller analysis, and zeta-potential measurements were used to characterize the mineral composition, surface functional groups, morphology, pore structure, and surface charge of SMCDA. Batch adsorption experiments examined the effects of solution pH, adsorbent dosage, initial MB concentration, contact time, and temperature. The highest removal efficiency, 97.33%, was obtained at pH 8 with an SMCDA dosage of 1000 mg L⁻¹. Equilibrium data were fitted using seven isotherm models and evaluated using multiple statistical criteria and Multi-Objective Optimization by Ratio Analysis (MOORA). The Freundlich model achieved the highest MOORA ranking and predicted an equilibrium adsorption capacity of 13.944 mg g⁻¹ at the highest concentration investigated, which is close to the experimental value of 14.425 mg g⁻¹. The results are consistent with heterogeneous adsorption involving electrostatic attraction, possible π–π interactions, hydrogen bonding, and pore filling. These findings demonstrate the potential of cow dung ash as a low-cost adsorbent prepared without hazardous chemical activating agents. Full article

Silver complexes are potential antimicrobial agents that trigger destructive processes in bacterial cells, leading to their death. Their ability to simultaneously stimulate tissue regenerative properties also makes them promising components in the development of medical materials. A common complication arising from the treatment of bone tissue damage is hospital-acquired infection, requiring repeated revision surgeries. The use of bone grafts with antibacterial properties can help solve this problem. New pyridine complexes of silver(I) with thiophenecarboxylic (Htph) and nitric acid anions have been synthesized: [Ag(tph)(py)₂]_n·nHtph (1, py—pyridine) and [Ag(bpy)]_n·nNO₃ (2, bpy—4,4′-bipyridine), the structures of which have been determined using X-ray analysis. Despite the fact that 2 is a known structure, we were able to obtain new cell parameters by conducting an X-ray diffraction analysis at a lower temperature of 100 K. According to X-ray diffraction data, both compounds are polymers in which the cationic part is formed by linear fragments (CN_Ag = 2) [Ag(py)₂]⁺ (1)/[Ag(bpy)₂]⁺ (2), and acid anions act as counterions. The presence of intermolecular and non-valent π-π interactions provides additional stabilization of supramolecular levels. Aqueous solutions 1 and 2 are stable for two weeks, according to UV-Vis data. Incubation of crosslinked resorbable polymer matrices functionalized separately with complex 1 or 2 in saline solution revealed a sustained, prolonged release of silver ions over 14 days. Evaluation of the antimicrobial potential of 1 and 2 against Gram-positive/Gram-negative species and fungi demonstrated moderate, controlled bacteriostatic growth inhibition broadly across tested strains, confirming the bifunctionality of the crosslinked hybrid matrix systems—moderate suppression of bacterial growth while simultaneously stimulating tissue regeneration. An increase in cell viability, expressed in their active proliferation under the influence of complexes 1 and 2 up to 156%, as well as calcium deposition, indicates the high cytocompatibility and pro-mineralization capacity of the new compounds. Full article

In this study, we prepared a magnetic University of Oslo-66 (UiO-66) composite material, Fe₃O₄@SiO₂@UiO-66, and applied it as an adsorbent for the effective removal of benzoic acid from wastewater. The resulting magnetic MOF composite retained the structural and property characteristics of MOFs, along with magnetic separation capabilities, allowing for swift recovery from water through external magnetic fields. A potential synergistic effect between magnetic particles and UiO-66 was observed, leading to enhanced benzoic acid adsorption. The adsorption capacity per Zr₆ cluster unit in Fe₃O₄@SiO₂@UiO-66 measured 569.5 g/mol, surpassing that of UiO-66 by more than 26%. We conducted investigations into adsorption properties as a function of initial concentration, contact time, and pH values. The adsorption of magnetic UiO-66 composites was well described by pseudo-second-order and Langmuir models, indicating predominant chemisorption on the homogeneous surface. Thermodynamic studies of adsorption revealed a spontaneous exothermic process. Furthermore, we analyzed possible mechanisms of benzoic acid adsorption, highlighting the contributions of electrostatic interactions, coordination interactions, and π–π stacking interactions. Magnetic UiO-66 exhibited remarkable adsorption capacity, along with reliable regeneration performance and convenient magnetic separation capabilities, making it an exceptional adsorbent for industrial applications in the removal of benzoic acid. Full article

A composite based on humic acid (HA) and reduced graphene oxide (rGO) was synthesized to evaluate the effect of rGO on the structural, functional, thermal, and preliminary phenol adsorption properties of humic acid. The incorporation of rGO increased the carbon content from 47.34 to 55.61 wt.% and decreased the oxygen content from 48.31 to 40.79 wt.%. At the same time, the total content of carboxyl and phenolic hydroxyl groups increased from 5.00 to 5.47 mmol/g, indicating improved accessibility of oxygen-containing functional sites. FTIR spectroscopy confirmed the retention of the main functional groups of the initial components after composite formation. Thermogravimetric analysis showed enhanced thermal stability, with the residual mass at 1000 °C increasing from 59.21 to 70.03%. Electron microscopy revealed the formation of a developed wrinkled surface morphology. Preliminary phenol adsorption experiments showed that the HA-rGO composite exhibited higher adsorption capacity than the initial HA and rGO. This improvement was attributed to the combined contribution of oxygen-containing functional groups and the aromatic carbon structure of rGO, which may promote hydrogen bonding and π–π interactions with phenol molecules. Full article