Search Results (520)

Fungal decay fundamentally alters moisture transport in wood through complex bio-physical coupling mechanisms that remain poorly understood. Brown-rot fungi such as Coniophora puteana (Schumach.: Fr.) P. Karst. degrade wood through chelator-mediated Fenton (CMF) chemistry, producing hydroxyl radicals that depolymerise cellulose and hemicellulose before significant mass loss. This diffusion-dependent process requires elevated moisture content and leads to structural degradation. However, existing models fail to capture the interaction between boundary-driven fungal colonization, decay-induced property changes, and multi-phase multi-Fickian moisture redistribution, particularly the separate evolution of bound- and free-water phases during decay. Here, we present a transport-response bio-hygrothermal finite element model that couples boundary-driven Monod-type fungal colonization kinetics with multi-phase moisture transport (free water, bound water, vapor) in decaying wood. Although fungal biomass evolution is simulated via a reaction–diffusion equation, decay progression is not derived from biomass–substrate interaction but prescribed independently as an experimentally informed input. The model incorporates decay-modified sorption isotherms, permeability evolution, and boundary-driven biomass influx, along with associated moisture transport, into the governing equations. The model is validated against low-field nuclear magnetic resonance (LF-NMR) measurements of C. puteana decay in Scots pine over 35 days. The model successfully reproduces the experimentally observed moisture evolution: a peak free-water content of 50%–70% during weeks 1–2, followed by a progressive decline, while bound water remains remarkably constant despite advancing decay. Monte Carlo uncertainty quantification demonstrates hierarchical parameter control: bound water is governed solely by thermodynamic factors, while free water responds to interacting biological and physical processes. Time-resolved correlation analysis shows a fundamental transition from colonization-dominated (weeks 1–2) to transport-dominated (weeks 3–5) moisture control, quantitatively explaining the experimentally observed shift from accumulation to depletion. This transport-response framework for analyzing moisture behavior under externally defined decay progression establishes quantitative parameter hierarchies that may inform the development of future substrate-coupled bio-hygrothermal models. Full article

The development of efficient, sustainable, and low-cost catalysts for wastewater treatment remains a major environmental challenge. In this work, Zn-doped CuO nanostructures were successfully synthesized via a green route using Aloysia citrodora leaf extract as a natural reducing and stabilizing agent. The structural and morphological properties of the prepared catalysts were systematically characterized by XRD, Raman spectroscopy, FTIR, SEM, and EDX analyses. The results revealed the formation of highly crystalline monoclinic CuO nanoparticles, whose defect density and surface properties were significantly modified by Zn incorporation. The catalytic performance of the synthesized materials was evaluated through the heterogeneous Fenton-like degradation of Rhodamine B in aqueous solution under dark conditions. The Zn-doped CuO catalyst exhibited outstanding degradation efficiency (~99.97%) within only 30 min, using a low catalyst dosage of 15 mg and a minimal H₂O₂ amount of 25 μL. The enhanced catalytic activity is attributed to the synergistic interaction between Zn-induced lattice defects and the Cu²⁺/Cu⁺ redox cycle, which promotes efficient H₂O₂ activation and •OH radical generation. Radical scavenging experiments confirmed the dominant role of hydroxyl radicals in the degradation process. Compared with previously reported CuO-based catalysts, the present system demonstrates superior performance in terms of reaction rate, oxidant consumption, and energy efficiency. These findings highlight the potential of Zn-doped CuO synthesized via green chemistry as a promising and sustainable catalyst for advanced wastewater treatment applications. Full article

Reaction OH + HI → I + H₂O (1) is an important atmospheric process transforming inactive HI into chemically active iodine atoms. In the present work, the reaction kinetics have been studied in a discharge fast-flow reactor coupled with an electron impact ionization mass spectrometer at nearly 2 Torr total pressure of helium and over a wide temperature range, T = 225–950 K. The reaction rate constant was determined both by a relative rate method (with the OH + Br₂ reaction as a reference) and by absolute measurements carried out under pseudo-first order conditions by monitoring the OH consumption kinetics in excess of hydrogen iodide. U-shaped temperature dependence was observed for the reaction rate constant, negative at low temperatures and positive at high temperatures. Recommended expression over the 225–950 K temperature range: k₁ = 1.13 × 10⁻¹¹ exp(354/T) + 6.93 × 10⁻¹¹ exp(−1010/T) cm³ molecule⁻¹ s⁻¹ or in the form of a modified Arrhenius expression, k₁ = 4.2 × 10⁻¹² × (T/298)^1.36 exp(666/T) cm³ molecule⁻¹ s⁻¹, with a total estimated uncertainty of 15% at all temperatures. The rate constant data obtained in this study are compared with the results of previous experimental works. Full article

Non-thermal plasma-driven advanced oxidation is a promising method for treating organic wastewater, which exhibits rapid reaction kinetics and high pollutant removal and does not need chemical reagents. However, its practical application is often limited by high specific energy consumption and the inefficient mass transfer of short-lived reactive species across the gas–liquid interface. This review summarizes the fundamentals of non-thermal plasma chemistry and the process intensification of plasma multiphase reactors by mass transfer enhancement and waste energy-driven conversion. This review focus on four coupling approaches: microbubble-assisted plasma to expand the reactive interfacial area; plasma coupled with hydraulic cavitation to enhance convection and radical formation; plasma–piezoelectric catalysis coupling to harvest hydraulic energy and promote charge-driven reactions; and plasma-assisted Fenton oxidation to improve the utilization of weakly oxidizing species (H₂O₂). The energy efficiency of various plasma-based oxidation systems is compared and discussed clearly. Key remaining challenges are also discussed, including standardized energy efficiency assessment, scale-up and hydrodynamic control, catalyst stability and fouling, by-product formation and toxicity, and long-term operational reliability. Overall, this review aims to provide guidance for developing efficient plasma-based wastewater treatment systems for large-scale applications. Full article

Ultra-high dose-rate (FLASH) irradiation can transiently deplete oxygen and modulate radical-mediated chemistry in irradiated cells. Cellular antioxidants also contribute to mitigating oxidative damage in a manner dependent on linear energy transfer (LET), as suggested by recent experimental studies. In this work, we employed our multi-track Monte Carlo simulation framework (IONLYS-IRT) to investigate how LET influences transient radiation-induced oxygen depletion (ROD) in a cell-like aqueous environment under FLASH irradiation conditions. FLASH exposures were modeled as single, instantaneous pulses of protons with energies from 300 MeV to 150 keV, corresponding to LET values of ~0.3 to 71 keV/μm. Our simulations revealed a marked decline in oxygen depletion with increasing LET, in agreement with experimental observations. For an intracellular O₂ concentration of 30 μM, the oxygen consumption yield, G(–O₂), decreased from ~4.0 molecules/100 eV at low LET (~0.3 keV/μm) to ~1.6 molecules/100 eV at high LET (~71 keV/μm), representing a ~60% reduction. To assess whether ROD depends solely on LET or is also governed by ion track structure, we systematically compared multiple ion species (protons, ⁴He²⁺, ¹⁰B⁵⁺, ¹²C⁶⁺, ¹⁶O⁸⁺, ²⁰Ne¹⁰⁺, ²⁸Si¹⁴⁺, ³²S¹⁶⁺, and ⁴⁰Ar¹⁸⁺) at comparable LET values. At ~70 keV/μm, heavier ions produced significantly higher G(−O₂) values than protons—though still below those at low LET—suggesting that track structure plays a key role beyond LET alone. These findings highlight the dual importance of LET and ion-specific track structure in modulating ROD under FLASH conditions. Notably, enhanced ROD in surrounding normal tissues (low-LET plateau regions) may contribute to radioprotective effects, whereas reduced ROD in tumor tissues (high-LET Bragg peak regions) would be expected to preserve tumoricidal efficacy. Together, these results provide a mechanistic framework for optimizing proton and heavy-ion approaches in FLASH radiotherapy. Full article

Sulfonamide antibiotics (SAs) are ubiquitous and persistent organic contaminants in aquatic and soil ecosystems due to their extensive application and high structural stability, causing rising environmental hazards. Conventional treatment approaches, generally based on physical adsorption or biological processes, remain limited in achieving efficient and stable removal as well as deep molecular modification of SAs. In recent years, modified biochar has developed as a flexible environmental functional material incorporating adsorption and reaction regulation capabilities, owing to its customizable pore structure, surface chemistry, and electronic characteristics. This study comprehensively highlights current achievements in the adsorption and degradation of sulfonamide antibiotics by modified biochar, with specific emphasis on modification techniques, structural modulation, structure–performance connections, and interfacial reaction processes. Through physical activation, heteroatom doping, defect engineering, and metal integration, biochar has developed from a traditional adsorbent into a carbon-based interfacial reactor capable of pollutant adsorption, molecular activation, and directed transformation. Surface-confined reaction interfaces, where π–π interactions, hydrogen bonding, electrostatic interactions, and metal coordination cooperatively control adsorption and transformation processes, are primarily responsible for the elimination of SAs. Moreover, the dual functions of modified biochar in driving both radical and non-radical pathways are explored, showing the vital importance of interfacial electronic structure modulation and electron-transfer mechanisms in influencing reaction efficiency and selectivity. The impact of sulfonamide molecular configurations, ambient circumstances, and concomitant chemicals on removal performance are also explored. Unlike previous reviews that mainly summarize adsorption efficiency or oxidant activation systems separately, this work integrates structural modulation, interfacial electronic regulation, and bond-selective transformation mechanisms into a unified structure–chemistry–reactivity framework. By correlating sulfonamide molecular configuration with biochar electronic structure, this review provides a mechanistic roadmap for the rational design of next-generation catalytic biochar systems. Finally, key challenges related to structural controllability, long-term stability, and engineering scalability are identified, and future research directions are proposed to support the rational design of high-performance biochar materials and the practical control of sulfonamide antibiotic pollution. Full article

This review presents the covalent chemistry of carbon from the point of the spin-radical concept of electron interaction in the framework of the unrestricted molecular orbitals (UHF MO) theory. Using the language of valence bond trimodality, the regions of classical spinless spin-symmetric covalence and its spin-dependent asymmetric counterpart are defined. Carbon is the only element exhibiting spin covalent chemistry. Classical covalent chemistry of carbon of molecular substances whose valence bond structure includes segregate or chained single sp³$C-C$ bonds meet its spin counterpart only at these bonds breaking. Substances with double sp²$C=C$ and triple sp¹$C\equiv C$ bonds are the subject of spin covalent chemistry of carbon. The mathematical apparatus of the UHF MO allows forming algorithms controlling the chemical modification of carbon substances, polymerization processes, and catalysis involving them, making it possible to supplement the empirical spin covalent chemistry of carbon with its virtual analog. Full article

Visible-light photocatalysis enables the integration of classical electrophile/nucleophile chemistry with radical species (free radicals, radical cations, and radical anions) and metallocomplexes, significantly expanding the scope of organic transformations. Substrates capable of generating radicals via single-electron transfer (SET) are therefore of high value in this field. Among conventional radical precursors, organic peroxides occupy a distinctive position due to their unique reactivity. They can generate both oxygen-centered and carbon-centered radicals through either oxidative or reductive SET pathways. Furthermore, organic peroxides can act as radical precursors, nucleophiles, and oxidants. The review emphasizes the advancements of visible-light-mediated reactions utilizing the broad potential of organic peroxides for constructing various chemical bonds. Full article

The ability of the atmosphere to convert primary pollutants into secondary pollutants through atmospheric oxidants is referred to as the atmospheric oxidizing capacity (AOC). This study systematically reviews the generation mechanisms, influencing factors, and quantitative characterization methods of major oxidants, along with advances in chemical mechanisms and modeling. We provide a comparative analysis of AOCs across diverse environments, including urban, suburban, and rural regions, highlighting the distinct impacts of anthropogenic and biogenic emissions on oxidation regimes. Despite advancements in chemical transport models and machine learning, limitations such as sparse observations, imperfect parameterizations, and unresolved chemical mechanisms lead to significant underestimations of the AOC. Future research must prioritize multi-scale observational networks and the elucidation of key chemical processes to refine model accuracy and improve the effectiveness of pollution control strategies. Full article

Polyester/cotton blended fabrics—valued for comfort and durability—face significant fire hazards due to a synergistic “scaffold effect” during combustion. Conventional treatments with high temperature or some acidic phosphorus flame retardants during preparation often compromise the mechanical strength. Inspired by mussel adhesion chemistry, a mechanically enhanced polyester/cotton fabric was developed by using a novel bio-inspired phosphorus/nitrogen (P/N) synergistic coating. A uniform polydopamine-polyethylenimine (PDA-PEI) layer is rapidly deposited via co-deposition, suppressing dopamine self-polymerization. Subsequent covalent bonding with 2,2-dimethyl-1,3-propanediyl bis (phosphoryl chloride) (DPPC) establishes a robust P/N network. The fabricated PDA-PEI/DPPC coating reduces peak heat release rate (pHRR) and total heat release (THR) by 57.7% and 32.6%, respectively, in cone calorimetry, achieving self-extinguishment and a high limiting oxygen index (LOI) of 24.6%. Remarkably, the coating simultaneously increases the weft-direction breaking strength by 55% and elongation at break by 27.2%; these changes overcome the typical mechanical degradation associated with acidic phosphorus flame retardants. A comprehensive analysis reveals a synergistic mechanism: phosphoric acids catalyze cellulose dehydration and char layer formation in the condensed phase (90% stable C–C bonds), while radical scavengers (PO·, HPO·, and PDA) and non-flammable gases suppressed gas-phase combustion. This work presents a facile and effective strategy for fabricating high-performance and mechanically robust flame retardant polyester/cotton textiles, demonstrating the significant potential for improving fire safety in practical applications. Full article

Selective functionalisation of inert C(sp³)–H bonds in alkanes and cycloalkanes remains one of the main challenges in the field of environmentally sustainable chemistry. This review provides a critical assessment of current catalytic strategies, in particular addressing the persistent problem of overoxidation and low selectivity. Going beyond traditional compartmentalised summaries, this work identifies a significant trend towards the integration of non-traditional activation methods, including ultrasonic cavitation, photocatalysis, and nanosecond pulse discharges, in both homogeneous and heterogeneous systems. Key contributions include a comparative analysis of radical control strategies, in particular highlighting how intermediate hydroperoxides can be used to shift reaction pathways towards selectivity of over 97% for alcohols and ketones. In addition, we discuss the emerging role of carbon nanomaterials (e.g., fullerenes and brominated nanotubes) as active electron-rich carriers and catalysts that lower the energy barriers for C–H activation under mild, ‘green’ conditions. The review concludes that the future of scalable hydrocarbon oxidation lies in ‘hybrid’ approaches such as stabilising active metal centres in protective matrices (zeolites, polymers) while using physical stimuli (ultrasound) to overcome diffusion limitations. This unique perspective highlights the transition from purely chemical catalyst design to integrated process intensification, offering a roadmap for energy-efficient and environmentally friendly industrial technologies. Full article

Oxidative stress seems to be part of many deranged processes in the organism, affecting multiple degenerative conditions at a cellular and tissue level. Coumarins and flavonoids comprise two main categories of naturally derived compounds with multiple effects and applications. Our aim in this paper is the design of compounds with increased antioxidant activity with the conjugation of two moieties with highly antioxidant potency in the frame of one molecule. A series of novel derivatives, comprising fusion of 7-hydroxycoumarin (Umbelliferone) and Quercetin (flavonol) have been synthesized using classical organic chemistry methods. Additionally, one novel flavone derivative was prepared for comparison. The novel compounds were tested for their radical, reactive oxygen and nitrogen species (ROS and RNS) scavenging, their reductive activity, and their labile metal chelating potency, as well as with in silico tools. All of them were more active, in most cases, than reference molecules Trolox and vitamin C. The most active compound 2 reached IC₅₀ of 4.03 and 43.75 μM for ABTS and DPPH, respectively (up to three times lower than that of Trolox). Compound 1 was of equal to vitamin C activity in H₂O₂ scavenging, whilst compound 3 was up to 6.4 times more active than Trolox in NO scavenging. Since our designed compounds seem to exhibit high antioxidant potential, scavenging reactive nitrogen and oxygen species, which are accumulated and promote the progression of inflammatory conditions, and have reductive and metal chelating abilities, they can be considered as potential candidates for protection in cases of oxidative stress derived toxicity. Full article

Plant polyphenols, particularly flavonoids, are prominent bioactives in preventive/complementary therapeutic strategies. This article analyzes how some polyphenols can mitigate oxidative stress and inflammation. These processes are involved in cardiovascular disease, cancer, neurodegeneration, and metabolic disorders. Polyphenols are explored through the integration of direct antioxidant chemistry (radical scavenging via hydrogen atom transfer/single-electron transfer/metal chelation), redox signaling (Keap1–Nrf2/ARE and inflammatory pathways), endogenous antioxidant enzyme systems, and mitochondrial quality control. Unlike previous descriptive reviews, a novel aspect of this manuscript is its evidence-based synthesis, fully supported by structured summary tables that explicitly detail limitations, contradictions, and context dependencies in in vitro, in vivo, and human studies, and identify clinically interpretable endpoints for their application. We describe relevant flavonoids and dietary sources, along with functional outcomes in cardiometabolic–cognitive/neuroprotective–immunometabolic contexts. We integrate representative clinical interventions and nutraceutical applications, highlighting where reported benefits are supported and where the evidence is preliminary. Bioavailability, microbiota-driven biotransformation, and dose realism are considered the primary determinants of in vivo relevance, rather than secondary or descriptive considerations. Future research should prioritize standardized exposure and metabolite profile, dose-appropriate interventions, harmonized clinical endpoints, and stratification strategies that account for microbiome-driven interindividual variability to improve reproducibility and inform nutraceutical and therapeutic use. Full article

The synthesis of monocyclic and bicyclic compounds plays a fundamental role in organic chemistry, and the need for novel synthetic methodologies is still under investigation. In particular, α,β-unsaturated (bis)enones have emerged as valuable precursors for the formation of cyclic (both mono and bicyclic) structures through single-electron transfer (SET) processes. Single-electron transfer (SET) is a redox process where one electron moves from a donor species to an acceptor, generating radical ions or neutral radicals that drive unique reaction pathways. Thanks to the advent of radical chemistry, it was possible to discover an entirely new reactivity of α,β-unsaturated (bis)enones, which, after a SET event, undergo the formation of cyclic molecules, both in intra and inter-molecular reactions, under several possible pathways, including formal [2+2] cycloaddition reaction (22CA) and 5-exo-trig cyclization, for ring closure. Today, the generation of radical species can be broadly classified into three main approaches: photochemical and photocatalytic, metal-driven and electrochemical processes. In this review, we summarize the progress achieved to date in the synthesis of cyclic molecules from α,β-unsaturated (bis)enones via single-electron transfer events under these three main classes of processes. Whenever possible, the reaction pathway and fate of the radical species generated through SET is discussed. Full article

The anti-Markovnikov addition of thiyl radicals, generated via one-electron oxidation of thiols, to C=C double bonds is a useful method for synthesizing unsymmetrical sulfides and has been widely applied in the preparation of pharmaceuticals and functional materials. However, conventional radical thiol–ene reactions require metal-based photoinitiators or organic photosensitizers, raising concerns about product isolation and environmental impact. Herein, we demonstrate an initiator-free thiol–ene coupling via electrochemical oxidation of thiols. Using a microfluidic electrochemical reactor, the electrochemically generated thiyl radicals undergo rapid and selective addition to alkenes, affording thioethers in reasonable yields. Substrate scope studies involving 13 alkenes and 13 thiols indicate that thiol acidity (pK_a), alkene electronic properties, and steric effects play key roles in determining reaction efficiency. Although further optimization is required to improve yields and broaden substrate scope, this electrochemical approach highlights the potential of thiol–ene coupling as a sustainable tool in green synthetic chemistry. Full article