Search Results (822)

Wormlike micelles (WLMs) of surfactants are widely used as smart thickeners in various applications, including enhanced oil recovery. However, their thickening ability needs to be improved both at ambient and elevated temperatures. In the present paper, we propose to enhance the viscoelastic properties of surfactant solutions by incorporating carboxymethylated cellulose nanocrystals (CNCs). Upon addition of CNCs, dilute solutions of short WLMs acquire viscoelasticity and then transition into a viscoelastic solid state. This process is accompanied by an increase in the viscosity and storage modulus by up to five and four orders of magnitude, respectively. The observed effect of CNCs on the storage modulus and viscosity is greater than that of any of the previously studied WLM-CNC systems. It is attributed to the formation of a network of fibrillar-like aggregates composed of WLMs and CNCs, which was confirmed by cryo-TEM data. To our knowledge, such kind of aggregates have not been observed before. When CNCs are added to a transient network of long entangled WLMs, the viscoelastic solution transitions into a viscoelastic solid state, which results in an increase in the viscosity and storage modulus by up to two orders of magnitude. CNCs provide the WLM solution with greater resistance to heating, such that the storage modulus remains almost unchanged when the temperature increases from 20 to 70 °C. Moreover, a heat-induced gelation was observed. It was shown that higher concentrations of nanocrystals lower the critical gel temperature, indicating that they promote the gelation of the mixture. SANS data revealed that the local structures of both micelles and nanocrystals are preserved in the mixed system upon heating. According to ITC data, at room temperature, the interaction between surfactant ions and similarly charged nanocrystals is governed by both enthalpy and entropy, which suggests that hydrogen bonding plays a major role in this process, although hydrophobic interactions may also be involved. When the temperature increases to 60 °C, the aggregation becomes entropy-driven, indicating that hydrophobic interactions begin to dominate. The results obtained can expand the range of practical applications of WLMs as thickening agents, in particular, to higher-temperature conditions in deeper oil wells. Full article

In this study, phenol adsorption from aqueous solutions was investigated using a carbonized adsorbent derived from a 1:1:1 mixture of banana, carrot, and potato peels, representing a major fraction of municipal bio-waste in Serbia. The material (CARB_BCP) was characterized by pH_pzc, SEM, FTIR, and BET analyses. The results indicated a highly porous structure with developed micro- and mesoporosity and a high specific surface area (S_BET = 483 m²/g). FTIR confirmed the formation of a stable aromatic carbon structure, while the high pH_pzc value (10.55) suggested a limited role of electrostatic interactions. Adsorption experiments performed at an initial phenol concentration of 1858 mg/L, room temperature, and an adsorbent dose of 0.1 g achieved a removal efficiency of 20.5%. The Langmuir model provided the best fit, indicating monolayer adsorption, with good agreement between theoretical (≈187 mg/g) and experimental (≈190 mg/g) capacities. Kinetic analysis followed the pseudo-second-order model, suggesting chemisorption as the rate-controlling step. The adsorption mechanism was mainly governed by π–π interactions, hydrophobic effects, and hydrogen bonding. These results demonstrate that CARB_BCP, derived from biodegradable waste, is a promising low-cost adsorbent for wastewater treatment. Full article

Vanadium tailings-based ceramsite (VT-Ceramsite), a type of porous ceramsite synthesized from vanadium tailings, was employed for the adsorption of fluoride ions from high-fluoride wastewater. This approach not only mitigates environmental pollution caused by industrial solid waste but also effectively removes fluoride contaminants from wastewater. The effects of vanadium tailings content, sintering temperature, and sintering time on the adsorption performance of the VT-Ceramsite were systematically investigated. Comprehensive characterizations via XRD, SEM, BET, and adsorption modeling reveal that fluoride sequestration by VT-Ceramsite is governed by the synergy between physical diffusion and chemical interactions. While the porous architecture provides essential transport pathways, the chemically active sites facilitate stable bonding. Future research will prioritize surface functionalization and tailoring strategies to augment the density of these active sites, thereby maximizing the adsorption potential for treating complex industrial effluents. The optimal preparation conditions were determined to be a ratio of 6.5:2.5:1 for vanadium tailings, fly ash, and kaolin, with a preheating temperature of 300 °C for 20 min and a sintering temperature of 900 °C for 20 min. In these conditions, the adsorption capacity for fluorine ions can reach 43.59 mg/g. VT-Ceramsite exhibited a specific surface area of 3.61 m²/g, hydrochloric acid solubility of 1.2%, and a void fraction of 48.68%, all parameters met national industrial standards. In addition, the leaching concentrations of heavy metals were found to be well below the limits specified in CJ/T 299-2008, indicating that the material poses no risk of secondary pollution. The study provides an economical, safe, and environmentally friendly route for the utilization of solid waste, and it offers a promising adsorbent for treating high-fluoride wastewater. Full article

Basalt fiber-reinforced polymer (BFRP) composites are increasingly considered as a sustainable alternative to traditional FRP systems for the strengthening of reinforced concrete (RC) structures, owing to their favorable mechanical properties, durability, and lower environmental impact. This study investigates the effectiveness of externally bonded BFRP strips for the strengthening of RC beam–column joints, with particular attention to the influence of strengthening layout on the structural response. An experimental program was carried out on full-scale RC beam–column joint specimens subjected to monotonic loading with load–unload cycles of increasing amplitude. Each specimen was first tested in its original configuration to induce controlled damage and subsequently strengthened using BFRP strips arranged according to two different layouts. This approach enabled a direct comparison between the behaviour of pre-damaged and retrofitted specimens and allowed the contribution of the BFRP reinforcement to be clearly identified. BFRP strengthening markedly improves joint performance, enhancing strength, ductility, and energy dissipation while limiting stiffness degradation. The results underline the critical role of the strengthening layout in governing the effectiveness of the composite system, as well as the influence of substrate cracking in the activation of the BFRP reinforcement. Full article

In this work, three 3-carboxamidecoumarin derivatives (3b, 3c, and 4) were synthesized and characterized by NMR, IR, and single-crystal X-ray. All compounds maintain an essentially planar coumarin scaffold stabilized by an intramolecular N–H⋯O hydrogen bond (S(6) motif), though compound 4 exhibits a more complex bifurcated S₃²(11)[S(6)S(6)S(5)] network that enhances its conformational rigidity. The crystal packing analysis reveals that while all derivatives form one-dimensional (1D) supramolecular tapes through C–H⋯O interactions, their 3D architectures differ significantly: 3b and 3c rely on a diverse combination of π⋯π stacking and lone pair⋯π contacts, whereas 4 is governed by highly directional stacking between the pyran and pyridine rings. Hirshfeld surface analysis and CE-B3LYP energy framework calculations quantified the balance between intermolecular forces, showing that 3b is dispersion-dominated (H⋯H, 43.5%), while 3c achieves a balanced electrostatic–dispersion regime due to the nitro group, which increases O⋯H/H⋯O contacts to 37.1% and yields the highest stabilization energy (−69.1 kJ/mol). These results demonstrate that the electronic nature of the substituents at the 3- and 6-positions drastically modulates the hierarchy of non-covalent interactions, providing key insights for the crystal engineering of coumarin-based supramolecular systems. Full article

This study investigates how the adhesive curing state before riveting influences material flow during riveting, joint formation, and the mechanical performance of CFRP/aluminum hybrid joints. Hybrid joints were fabricated in a single-lap configuration using electromagnetic self-piercing riveting (E-SPR) at curing times of 0, 20, 40, 60, and 80 min, and the adhesive distribution, joint geometry, load–displacement behavior, energy absorption, and failure mode were examined. As curing time increased, adhesive squeeze-out decreased and adhesive displacement during riveting was progressively restricted, leaving more adhesive near the contact point. Consequently, the head height increased from 0.12 to 0.21 mm, whereas the interlock distance decreased from 0.67 to 0.54 mm. In the bonded region, the peak load increased with curing time, and a peak load of 11.15 kN was observed at 40 min, indicating an increased contribution of the adhesive layer. In contrast, the load in the riveted region decreased at 60 and 80 min because the increased resistance of the adhesive interlayer limited the rivet deformation and mechanical interlocking. A maximum energy absorption of 32.13 J was observed at 40 min, where the joint exhibited relative contributions of the adhesive and the rivet. Failure analysis showed bearing failure at 40 min, whereas rivet pull-out was observed at 60 min, consistent with the curing-dependent changes in joint formation. These results indicate that curing-induced changes in adhesive behavior govern the interaction between adhesive flow and rivet deformation, thereby influencing joint formation and mechanical performance. Full article

Interactions between resveratrol and biological or carrier systems play a key role in determining its bioavailability, stability, and delivery performance. These interactions involve proteins, lipids, cyclodextrins, nucleic acids, polysaccharides, and other formulation matrices, and are governed by noncovalent forces such as hydrogen bonding, hydrophobic interactions, π–π stacking, and desolvation effects. This review examines how complementary spectroscopic, calorimetric, structural, and computational techniques are used to characterize resveratrol interactions. Fluorescence, UV–visible spectroscopy, circular dichroism, FTIR, NMR, ITC, DSC, X-ray diffraction, molecular docking, and molecular dynamics simulations are discussed according to their contribution to binding analysis, conformational assessment, thermodynamic interpretation, structural organization, and complex stability. By integrating these approaches, this review provides a technique-oriented framework for understanding resveratrol binding and guiding the development of more stable resveratrol-based carrier systems and bioactive formulations. Full article

This study evaluates β-cyclodextrin (β-CD) and malonic acid functionalized pine sawdust biochar for organic pollutant removal, benchmarking efficacy against commercial Norit GSX activated carbon for sustainable water treatment. Characterization revealed that β-CD modification successfully developed porous structures, with Sawdust Activated Carbon (SDAC) and Norit GSX Activated Carbon (GSXAC) achieving Brunauer–Emmett–Teller (BET) surface areas of 438.36 m²/g and 1223.79 m²/g, respectively. Adsorption kinetics and isotherm studies demonstrated the superiority of β-CD-modified materials over traditional acid-functionalized variants. The adsorption kinetics were exceptionally well-described by the Pseudo-Second-Order model R² > 0.99, indicating that the process is governed by chemical interactions rather than simple physical attachment. In contrast, the Pseudo-First-Order and Elovich models provided poor descriptions of the system (R² = 0.54 and 0.11, respectively). An isotherm analysis further confirmed the heterogeneous nature of the SDAC surface, with the Freundlich model exhibiting an excellent fit (R² > 0.99) and an n value of 0.79. For GSXAC, the Freundlich model also outperformed the Langmuir model, yielding a K_F of 441.72 mg/g and n = 0.77, reflecting high adsorption intensity on a heterogeneous surface. The comparative advantage of β-CD is in line with its unique truncated cone structure, which is consistent with guest–host inclusion complex formation, multi-modal hydrogen bonding, and enhanced pH resilience. These findings validate β-CD-modified sawdust-derived adsorbents as potential, sustainable, high-capacity alternatives to industrial-grade carbons. Full article

Climate finance has become a major means of fostering sustainability in the construction industry, which encounters higher pressures to mitigate its environmental footprint without sacrificing economic viability. In line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, this study employs a hybrid approach, integrating a systematic literature review (SLR) and bibliometric analysis, to provide a comprehensive overview of the role and mechanisms of climate finance for sustainable practices in the construction industry. From 2019 to 2025, 176 papers were identified in the Scopus (73) and Web of Science (103) databases. The SLR enables both systematic collection and qualitative analysis of financial instruments, policy frameworks, and sustainability performance metrics, and bibliometric analysis provides a report of publication behavior, geographic distribution, and thematic network. Findings suggest intense clustering of research in countries, with India, China, and the United States as key focus areas, and that construction firms predominantly accessed climate finance on instruments including green bonds, sustainability-linked loans, public–private partnerships, and multilateral climate funds. Sustainability performance is commonly assessed using indicators such as carbon emissions, energy efficiency, lifecycle costs, and environmental, social, and governance (ESG) metrics. The findings also highlight the critical role of public policies, such as green procurement, carbon pricing, and fiscal incentives, in enabling sustainable construction practices. From a theoretical perspective, this study contributes to the understanding of how financial mechanisms, policy frameworks, and sustainability metrics interact to drive sectoral transformation. Future research should focus on standardizing sustainability metrics, evaluating financing impacts, and expanding studies in emerging economies. Full article

Wire laser cladding (WLC) of bronze on stainless steel offers a promising approach for combining the structural strength of steel with the superior tribological and corrosion properties of copper alloys. In this study, the influence of key process parameters, including wire preheating current, deposition speed, laser power, and wire feed speed on melt pool temperature and clad geometry was investigated using response surface methodology (RSM). Experiments were performed using a robot-assisted coaxial wire feeding laser cladding system, and real-time thermal monitoring was conducted using an infrared camera. The results showed that defect-free bronze clads with good metallurgical bonding and limited dilution were achieved across the investigated parameter range. Statistical analysis revealed that melt pool temperature is primarily governed by laser power and deposition speed, with a significant interaction between these parameters. Clad height was mainly influenced by wire feed speed and deposition speed, whereas clad width was controlled by laser power and deposition speed. The side angle was affected by deposition speed, laser power, and wire feed speed, reflecting the balance between vertical buildup and lateral spreading. Overall, the study demonstrates that stable and high-quality clads can be achieved by properly balancing energy input and material supply. The developed models provide valuable insight for optimizing process parameters in wire laser cladding of bronze on stainless steel. Full article

The conventional view of the renewable energy transition treats democratic governance and the rule of law as upstream drivers, yet across emerging markets, the empirical direction of these relationships is contested. Drawing on 19 emerging economies over 2010–2021, this paper documents an unexpected directional ordering, with renewable energy adoption Granger-preceding democratic and legal consolidation rather than the reverse. The empirical strategy combines bootstrap panel Granger-causality testing (Emirmahmutoğlu–Köse), Westerlund cointegration testing, and a system GMM identification check (Blundell–Bond). Renewable energy consumption Granger-predicts both democratisation and the rule of law, with reverse panel directions showing no predictive content; predictive spillovers extend further to industrial composition and trade openness. The predictive pattern is consistent with integrated rather than sequenced policy framings in emerging markets, in which renewable energy promotion and rule of law and anti-corruption efforts may operate as complementary rather than substitute channels. Full article

Chitosan-based copper composites have attracted considerable interest for biomedical and antimicrobial uses due to their biocompatibility, adjustable dielectric characteristics, and ion-mediated antimicrobial effectiveness. In this study, chitosan films doped with Cu(NO₃)₂, containing 3, 6, and 9 wt% of copper nitrate were produced using a solution-casting method at room temperature. This was done to explore the relationship between structural interactions, dielectric relaxation, optical properties, and antimicrobial efficacy. The resulting composite has been investigated physically using FTIR, XRD, optical analysis, and dielectric spectroscopy, and biologically for its antimicrobial activity. FTIR revealed the molecular structure of Cs-Cu(NO₃)₂ and changes resulting from new bond(s) formation and/or decomposition. XRD indicated that there are no peaks assigned for CuO, which weakens the composite antimicrobial activity. Optical analysis showed an increase in the band gap with copper (II) nitrate concentration over 3%. Additionally, the electrical impedance of the resulting composite increased by approximately one decade. A detailed electrical analysis of the charge-carrier types is provided. Moreover, the antimicrobial activity of chitosan is slightly enhanced by the additive copper (II) nitrate in a dose-dependent manner. The current research offers a mechanistic understanding of the structure–property relationships that govern the behavior of Cu(NO₃)₂–chitosan composites, emphasizing the significant influence of processing conditions on adapting of their dielectric and biological properties. Full article

The construction sector’s drive for sustainability has increased the use of Cross-Laminated Timber (CLT), yet its structural reliability is governed by the integrity of the adhesive bond line. This study evaluates the influence of three one-component polyurethane (PUR) formulations (R1, R2, R3) on the adhesion performance of maritime pine CLT. To isolate adhesive-related effects, lamellas were mechanically classified by modulus of elasticity (MOE) and randomly allocated within stiffness classes. Adhesive characterization through ABES, FTIR, and DSC revealed that R3 exhibited slower cure kinetics (t₀ = 5482 s) but higher thermal stability. Mechanical testing showed that all formulations developed structurally effective dry bonds with shear strengths exceeding 7.1 MPa, with R3 achieving significantly higher dry shear and interlaminar strength. However, 24 h water immersion caused a catastrophic strength reduction exceeding 95% across all formulations, shifting the failure mode from the wood substrate to the adhesive layer. DSC analysis identified glass transition temperatures between 28 °C and 32 °C, which are consistent with the potential for moisture-induced plasticization near service temperatures. These results indicate that while slower-curing formulations like R3 enhance bond quality in dense softwoods due to improved interphase formation, all evaluated PUR systems showed significant vulnerability to saturated conditions, suggesting that adequate moisture protection is essential for maritime pine CLT applications. Full article

This study involved a numerical parametric assessment of reinforced concrete (RC) T-beams strengthened with bonded steel wire ropes (SWRs), with the aim of evaluating the effectiveness of this strengthening system in terms of improving flexural performance. Since extensive experimental investigations are costly and time-consuming, a three-dimensional finite element model was constructed to represent the structural response of strengthened RC T-beams. This numerical model was verified using earlier experimental data to ensure its predictive capability for the flexural behavior of strengthened members. Following validation, the model was applied in a comprehensive parametric study to examine the effects of key design variables on structural performance. These variables included the SWR diameter, the compressive strength of the bonding mortar, and the strength of the bonding material. Their effects on load-carrying capacity, stiffness, deformation behavior, and energy absorption were systematically evaluated. The results indicated that SWR diameter was the dominant parameter, increasing ultimate load up to 1.93 times, with stiffness and energy absorption reaching 1.48 and 1.74 times those of the control beam, respectively. In contrast, higher concrete compressive strength provided moderate gains, with load capacity and stiffness increasing by up to 16% and 21%, while having a limited influence on ductility. Variations in bonding material strength showed minimal impact and negligible changes in stiffness. Strength and stiffness enhancements were accompanied by reduced ductility, indicating a trade-off between capacity and deformation. These findings confirmed that SWR efficiency was governed primarily by reinforcement size, while other parameters exhibited diminishing returns beyond threshold levels. Full article

Background/Objectives: Supramolecular hydrogels formed by low-molecular-weight gelators present a chemically heterogeneous transport environment whose molecular-scale dynamics remain poorly understood. This study aimed to investigate how drug physicochemistry governs transport within a liquid-crystalline C18ADPA hydrogel at the molecular scale. Methods: Pulsed-field gradient NMR spectroscopy was used to measure self-diffusion coefficients of five model drugs (5-fluorouracil, acetylcholine, paracetamol, prednisolone, and amphotericin B) spanning a broad range of size, polarity, and charge state, in both free solution and the hydrogel matrix at pH 5.37. Results: Observed drug diffusion coefficients deviated substantially from classical obstruction theory predictions, demonstrating that transport is governed by host–guest chemical affinity rather than molecular size. The three water-soluble drugs exhibited bimodal diffusion, with relative amplitudes providing a direct estimate of bound and free drug fractions. Prednisolone co-diffused with the gelator scaffold, consistent with hydrophobic bilayer partitioning, while amphotericin B diffused at rates consistent with the structured interfacial water layer. The gel pH (5.37) emerged as an active determinant of transport: drug charge states at this pH from permanent cation (acetylcholine) to near-zwitterion (amphotericin B) correlated directly with the observed transport behavior. The near-zwitterionic character of amphotericin B at pH 5.37, arising from its carboxyl pKa (~5.5), suggests a previously unreported electrostatic interfacial trapping mechanism. Conclusions: The liquid-crystalline bilayer architecture creates chemically distinct microdomains that selectively recruit drugs based on hydrophobicity, hydrogen-bonding capacity, and pH-dependent charge state, providing a molecular-scale framework for rational formulation design in supramolecular drug delivery. Full article