Search Results (1,562)

Coumarin compounds are of great interest in drug development research. Various substituents on the coumarin core significantly influence its biological activity. Although a number of coumarins with specific biological properties have already been identified, the ongoing challenge lies in the design and synthesis of novel derivatives with high specificity for pharmacological targets. In this work, 6-(4-aminobut-2-ynyloxy)- and 7-(4-aminobut-2-ynyloxy)-substituted coumarin derivatives were designed and synthesized. As a method for the synthesis of 6- or 7-substituted coumarins (yields 26–98%), a copper-catalyzed one-pot three-component reaction (A³ coupling) of 6- or 7-(prop-2-ynyloxy)coumarins with formaldehyde and secondary amines was studied. In vitro biological testing (MTT assay) results showed that the new coumarins exhibit pronounced cytotoxicity against human cervical cancer (C33 A and CaSki) and breast cancer (MCF-7) cell lines, with activity being dependent on the substituent at the nitrogen atom in the side chain. The most active compounds inhibited tumor cell growth, with GI₅₀ values of 4.3–9.4 μM (SI = 9.1–19.8). All new compounds demonstrated low cytotoxicity against the non-malignant epithelial VERO cells (GI50 > 86 μM). To understand the observed SAR trends, molecular modeling of the interaction between the new coumarin derivatives and DNA G-quadruplex binding sites was performed. Full article

Malachite green (MG), a triarylmethane dye extensively used in the textile and aquaculture industries, is a persistent aquatic contaminant with documented carcinogenic, mutagenic, and teratogenic effects even at trace concentrations. In the present work, a natural, low-cost Serpentine clay was surface-modified with copper oxide nanoparticles generated in situ through a green, lemon-extract-mediated reduction of copper nitrate, yielding a novel SER/CuO nanocomposite. The as-prepared adsorbent was characterized by FTIR, XRD, BET, and SEM to confirm the successful anchoring of CuO nanoparticles onto the Serpentine lattice. Batch adsorption experiments demonstrated that the removal of MG was governed by solution pH, adsorbent dose, contact time, and initial dye concentration, with maximum uptake obtained close to neutral pH, consistent with the point of zero charge (pH_pzc = 7.6) of the composite relative to the pKa (6.9) of the dye. Equilibrium data were described comparably well by the Langmuir and Freundlich isotherms at 25 and 55 °C, with a maximum monolayer capacity of 279.06 mg g⁻¹ at 25 °C, while kinetic analysis showed the closest statistical agreement with the Elovich model, pointing to an energetically heterogeneous, chemisorption-assisted process supported by a three-stage intraparticle-diffusion profile. The individual and combined effects of solution pH, adsorbent dose, and contact time on removal efficiency were systematically evaluated using a one-factor-at-a-time approach. Thermodynamic estimation from the two-temperature Langmuir constants indicated a spontaneous and exothermic, and entropy-favored adsorption process. The spent adsorbent was regenerated using dilute hydrochloric acid and retained appreciable efficiency over successive cycles. Comparison to previously reported adsorbents supported the competitiveness of SER/CuO in terms of capacity, cost, and simplicity of preparation, and a techno-economic appraisal supported the feasibility of scale-up. As a waste-valorization step, both the bare SER/CuO adsorbent and its MG-loaded form were evaluated as electrode materials for the urea oxidation reaction: MG loading raised the anodic current density from 143.10 to 176.46 mA cm⁻² at 1.0 M urea, nearly doubled the electrochemically active surface area (7.34 to 14.41 cm²), and lowered the charge-transfer resistance, while sustaining a higher stable current density (111 vs. 81 mA cm⁻²) over 3600 s of continuous operation demonstrating a promising route for coupling water remediation with energy recovery. Full article

To address the challenge of efficient catalytic elimination of carbon monoxide (CO) generated from spontaneous coal combustion in goaf and blasting operations in underground coal mines under low-velocity laminar flow conditions, we propose a perforated spiral-insert catalytic tube. The design inserts a spiral vane with surface micro-holes into a straight tube; the vane surface and internal pore walls are coated with a CuMnOx catalyst. A porous medium equivalent model describes the flow and catalytic reaction characteristics in the perforated region. A three-dimensional Computational Fluid Dynamics (CFD) model coupling flow, mass transfer, and surface catalytic reactions is developed. After grid independence verification, three sets of L9 orthogonal experiments systematically investigate the effects of inlet velocity, helix pitch, vane height, opening ratio, and pore diameter on CO conversion and flow resistance. Range analysis, variance analysis, and the comprehensive performance factor are used for multi-objective optimization. $PEC$ results show that inlet velocity is the primary factor affecting both conversion and comprehensive performance, and its dominance is independent of the number of vanes. At a low velocity of 0.2 m/s, the four-vane configuration achieves a maximum conversion of 51.07%. For a balanced trade-off between conversion and flow resistance, four vanes with a high opening ratio, large pore diameter, and large helix pitch yield the best comprehensive performance. If low resistance is the primary goal, two vanes with a high opening ratio achieve a resistance of only 0.29 Pa and a per-unit-resistance conversion efficiency of 97.72 Pa⁻¹. A further predicted optimal combination is validated by simulation, achieving a conversion of 64.96%, confirming the effectiveness of the parameter optimization. Under low-velocity conditions, the flow resistance of this design is only about 0.3–1.3 Pa, allowing passive operation using the natural negative pressure of the extraction pipeline. The design offers modular replaceability of the catalyst insert and operates without external power input beyond the natural negative pressure of the pipeline under the simulated low-velocity conditions, providing a theoretical basis and parameter optimization method for in situ CO catalytic elimination in coal mines. Full article

Weakly nonlinear free-surface flows past disturbances are traditionally modeled using the forced Korteweg–de Vries (fKdV) equation with a prescribed instantaneous pressure field. However, physical wake responses possess finite relaxation times and advection scales that diagnostic algebraic closures fail to capture. This paper introduces a novel coupled system in which the surface pressure is a dynamical field governed by an advection–reaction–diffusion equation driven by band-limited curvature. Using linear spectral theory and numerical validation, we derive a phase-speed criterion demonstrating that energy transfer is determined by the comparison between the pressure drift speed and the surface phase speed. A sharp stability theorem proves that, to leading order in the coupling strength and for a non-negative even response transfer function whose drift speed exceeds the Froude detuning, the system is spectrally stable if and only if the response is band-limited below a critical wavenumber $k_c$. Furthermore, an exact energy identity establishes that passivity and linear stability are equivalent. Finally, we demonstrate resonance steering: while coupling typically increases the wave resistance for monotone spectra, tuning the response to a spectral zero of a multi-lobe footprint reduces the drag significantly relative to its classical value. This result identifies an explicit performance–strongness trade-off, providing a mathematically strong structure for wave drag minimization through dynamic pressure control. Full article

The development of sustainable and efficient methods for carbon–carbon (C–C) bond formation remains the main objective in modern organic synthesis. In recent years, photocatalysis has developed as a suitable alternative to conventional transition-metal-catalyzed approaches, offering mild reaction conditions, high functional-group tolerance, excellent atom economy, and the ability to utilize visible light as a clean and renewable energy source. Through unique radical-mediated pathways, photocatalytic strategies allow the selective activation of traditionally unreactive substrates, including haloarenes, alkanes, alcohols, carboxylic acids, and amines, thereby providing efficient routes to complex molecular architectures. Beyond organic synthesis, photocatalysis has also demonstrated significant potential in broader areas of applied chemistry. This review summarizes the major advances in photocatalytic C–C bond coupling reported from 2023 to early 2026, with special focus on C(sp³)–C(sp³), C(sp³)–C(sp²), and C(sp²)–C(sp²) bond-forming reactions. Representative catalytic systems, substrate scope, reaction mechanisms, and synthetic applications are critically discussed, including dual photoredox/transition-metal catalysis, metal-free photocatalysis, hydrogen atom transfer (HAT), proton-coupled electron transfer (PCET), radical–radical coupling, decarboxylative and deaminative functionalization, and enantioselective transformations. Finally, current challenges, emerging trends, and future opportunities for developing more sustainable, scalable, and selective photocatalytic C–C bond-forming methodologies are highlighted, providing a comprehensive resource for researchers working in synthetic and medicinal chemistry. Full article

Carbon deoxidation is a clean steelmaking route, but rapid CO generation can increase gas holdup, raise the melt level, and cause splashing. However, a quantitative link between internal deoxidation kinetics and melt-level rise has not yet been established. Hot-state experiments at 1873 K in a 2 kg crucible under argon with 0.20–1.00 wt.% C were coupled with a dual-pathway kinetic model developed by decoupling free-surface mass transfer from internal CO generation through heterogeneous nucleation at active refractory pores and incorporating an effective reaction depth constrained by hydrostatic pressure. The model reproduced measured oxygen evolution and revealed three deoxidation stages. Internal gas generation initially dominated, contributing 96.6% of the overall rate. As carbon–oxygen supersaturation fell below a critical threshold, the nucleation zone receded upward and free-surface mass transfer became dominant. Within the investigated conditions, the internal apparent deoxidation rate constant during the rapid stage showed an empirical linear relationship with the measured maximum melt-level rise. The critical splash-prevention rate was 4.25 min⁻¹ for the crucible and was estimated to be 2.43 min⁻¹ for a selected 85 t ladle by combining this relationship with the average gas holdup relation and ladle geometry. The present results provide a kinetic basis for assessing splash risk during atmospheric carbon deoxidation. Full article

Background/Objectives: AC02 is a novel 39-amino-acid adrenocorticotropic hormone (ACTH) analogue designed for the treatment of infantile spasms. To support its clinical study, in which porcine ACTH_1–39 served as the positive-control drug, reliable methods for the determination of AC02 and porcine ACTH_1–39 in human plasma were required. Reported analytical methods for ACTH analogues are mainly immunoassays, which are easily affected by cross-reaction and the hook effect, necessitating a more selective analytical approach. Methods: Two LC-MS/MS methods were developed for the determination of ACTH analogues AC02 and porcine ACTH_1–39 in human plasma. Human ACTH_1–39 was included as a selectivity marker to confirm that endogenous ACTH does not interfere with the quantification of AC02. Based on the distinct concentration requirements and matrix challenges, two sample-preparation procedures were established: micro-solid-phase extraction coupled with protein precipitation for porcine ACTH_1–39 (LLOQ 0.100 ng/mL), and acid-mediated protein precipitation for AC02 (LLOQ 0.500 ng/mL). The [M+6H]⁶⁺ ions were selected as precursor ions, and the corresponding 5⁺ fragment ions, formed by loss of the C-terminal phenylalanine, were used for MRM detection. Results: Despite a mass difference of only 0.98 Da between AC02 and human ACTH_1–39, which are indistinguishable by mass spectrometry, baseline chromatographic separation was achieved. Both methods were fully validated in accordance with current bioanalytical guidelines. Conclusions: The validated methods were successfully applied to the phase I clinical study of AC02 and porcine ACTH_1–39, enabling reliable quantification of the drug candidate and its active comparator, porcine ACTH_1–39. Full article

Chicken manure represents a major agricultural waste stream with significant environmental risks if left unmanaged, yet its hydrothermally treated hydrochar (HCCM) holds promise as a renewable solid fuel. This study investigates the pyrolysis behavior, kinetics, thermodynamics, and gas evolution mechanism of HCCM using thermogravimetric analysis coupled with FTIR and mass spectrometry (TG-FTIR/TG-MS) at five heating rates (5–25 °C/min). TG-DTG results revealed a characteristic three-stage decomposition, with the main devolatilization occurring between 180 and 400 °C and a stable char residue of 22–27% remaining at 800 °C; DTG peaks shifted to higher temperatures and intensified with increasing heating rate, confirming a kinetically controlled process. Isoconversional analysis using the Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink (STK) methods; R² > 0.98 showed the apparent activation energy rising sharply from ~150 to over 320 kJ/mol with conversion, while consistently positive Gibbs free energy (130–210 kJ/mol) confirmed an endothermic, non-spontaneous reaction pathway. TG-FTIR and TG-MS identified CO₂, H₂O, carbonyl/amide fragments, and light hydrocarbons as dominant volatiles, with delayed H₂ release reflecting secondary aromatization and char condensation. These findings establish a mechanistic framework linking dehydration, decarboxylation, and aromatization reactions, supporting HCCM as a viable feedstock for sustainable energy recovery within a circular waste valorization strategy. Full article

Microwave-driven thermochemical cycles can split water for hydrogen production at temperatures far below those of conventional solar thermochemical routes, yet the responsible physical mechanisms remain unclear and numerical models for the coupled solar-microwave hybrid system are still scarce. Building on previous experimental work, we developed a coupled numerical model that integrates impedance matching, non-thermal enhancement, two-stage Arrhenius kinetics, and energy conservation to systematically investigate the interplay between microwave power, temperature evolution, and reaction progress. The model predictions agree well with experimental data in terms of temperature evolution trends, power threshold ranges, and reaction timescales. The results indicate that, within the present modeling framework, the effective microwave absorption efficiency increases from 1.2% at low temperatures to approximately 14% near 85 °C, with the non-thermal enhancement factor contributing as an empirical parameter. Under pure microwave mode, the required power threshold for reaction initiation is approximately 120 W; the solar-microwave synergistic mode reduces this threshold to about 70 W, a 42% reduction. At an input power of 100 W, the energy conversion efficiency reaches a maximum of 42%. Analysis of the sudden temperature change identifies 85 °C as the critical triggering temperature: below it, the system remains in a low-absorption cold state, while once crossed, a positive feedback mechanism rapidly propels the system into the high-temperature reaction regime. This study provides a numerical modeling framework for describing the coupled solar-microwave thermal behavior of the system and for guiding the optimization of its operational parameters. Since the available measurements cannot independently separate the thermal and non-thermal contributions, the non-thermal enhancement remains an empirically introduced factor rather than an experimentally established physical effect. Full article

To improve the inherently low electronic and ionic conductivity of lithium iron phosphate (LFP) cathode materials, the synergistic modification of Al doping and carbon coating has been proven to be an effective strategy. However, the doping effects of different aluminum (Al) sources have not been systematically compared, and the mechanism of the synergistic effect between the characteristics of the Al source and the synthesis process remains poorly understood. To address this, the present study systematically investigated the effects of three Al sources on the structure and electrochemical performance of LFP/C composites under two sintering processes: static and dynamic. Phase and microstructure characterizations confirmed the successful doping of Al³⁺ and the formation of an effective carbon coating. Electrochemical tests indicated that the choice of Al source and sintering process was strongly coupled: in the dynamic fluidized-bed process, which is highly characterized by efficient mass and heat transfer, Al(OH)₃, due to its lower thermal decomposition temperature and the release of active H₂O, promoted uniform Al³⁺ doping and optimized the quality of the carbon coating, thereby achieving the best overall performance. By contrast, under the sluggish reaction kinetics of static sintering, the chemically stable Al₂O₃ achieved ordered doping through slow solid-state diffusion, demonstrating the best cycling stability. In both processes, the overly stable AlPO₄ failed to release Al³⁺ effectively, resulting in limited performance improvement. This work reveals the key principle that the intrinsic reactivity of the Al source must be matched with the kinetics of the sintering process, deepens mechanistic understanding of the doping modification, and provides clear experimental evidence for the selection of the optimal Al source under different synthesis processes. Full article

Sulforaphane (SFN), an isothiocyanate abundant in cruciferous vegetables, possesses well-documented anticancer, antioxidant, and anti-inflammatory properties, and has attracted interest as a dietary chemopreventive agent. However, sensitive and fully automated methods for its quantification in foods remain limited. In this study, we developed an automated analytical system coupling in-tube solid-phase microextraction (IT-SPME) with high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) to determine SFN in vegetable samples. Vegetable samples were autohydrolyzed in aqueous solution at 37 °C to generate SFN, which was then extracted with methanol by sonication. The extract was concentrated onto a Carboxen 1006 capillary column by IT-SPME, separated within 5 min on an Inertsil C8 column, and detected in positive electrospray ionization mode using multiple reaction monitoring. The detection limit was 5.6 pg/mL, with good linearity (R² = 0.9995) over 0.1–100 ng/mL, intra- and inter-day precisions below 2.9% and 3.9%, respectively, and accuracy of 98–102%. SFN was detected at concentrations of 600 μg/g or higher in broccoli sprouts, florets, and stems, but was found at less than one-tenth of these levels in other vegetables tested. This method provides a simple, sensitive, and solvent-efficient tool for SFN quantification in vegetables, with potential application in food functionality assessment and chemopreventive research. Full article

Dephosphorisation in oxygen steelmaking depends on more than the equilibrium phosphorus partition ratio. It also depends on where gas, slag, metal and injected lime powder coexist while the bath is stirred. We develop a gas–slag–metal–particle reaction model for bottom-blown oxygen–CaO powder injection by coupling Euler–Euler transport of liquid steel, mixed slag, and gas with a discrete phase model (DPM) for CaO particles. The local source terms include oxygen dissolution, FeO/Fe₂O₃ conversion, CO/CO₂ buffering, competitive C/Si/P oxidation, ${\mathrm{P}}_2{\mathrm{O}}_5$ formation, $C_{2}S$–$C_{3}P$ fixation, reaction heat, and phase-wise mass conservation. Bubble swarms, dispersed slag, and emulsified metal–slag contact are represented through mean-field interfacial area densities tied to local phase fractions and mixing. Two simulated composition states have the same initial phosphorus content but different C, Si, and dissolved O levels; they are therefore compared as Case H and Case L rather than as a carbon-only test. Under the selected closures, Case H shows stronger decarburisation and CO-supported plume motion, whereas Case L retains more ${\mathrm{FeO}}_x$ and dissolved oxygen near the slag–metal interface. In both states, calculated P removal is confined mainly to locations where ${\mathrm{FeO}}_x$ supply, CaO availability, $P_2{O}_5$ generation, and $C_{2}S$–$C_{3}P$ fixation overlap. These observations are conditional on the reported parameters, a production mesh accompanied only by a two-grid qualitative sensitivity check, one time step, and the early transient considered here. Quantitative validation, systematic grid/time-step studies, closure-sensitivity tests, and controlled-composition simulations are required before the framework is used for process prediction. Full article

Elemental mercury (Hg⁰) removal in coal combustion flue-gas over commercial V-based SCR catalysts is still limited by insufficient low-temperature activity and the complex interference of gas components. In this work, V₂O₅/TiO₂, V₂O₅⁻MoO₃/TiO₂, and V₂O₅⁻MoS₂/TiO₂ catalysts were comparatively investigated for Hg⁰ removal under simulated coal combustion flue-gas conditions. Among them, V₂O₅⁻MoS₂/TiO₂ exhibited the best performance over the whole temperature window of 200–400 °C, reaching a Hg⁰ removal efficiency of 73.3% at 200 °C, which was markedly higher than those of V₂O₅/TiO₂ and V₂O₅⁻MoO₃/TiO₂. Under multicomponent SCR atmospheres in coal-fired plants, the catalyst also showed the highest Hg⁰ oxidation efficiency of 72.9%, indicating that MoS₂ modification was more effective than oxide promotion in enhancing low-temperature mercury removal. XRD and FT-IR results showed that MoS₂ and vanadia were successfully incorporated onto TiO₂ as dispersed surface phases, while the MoS₂-modified catalyst exhibited a distinct and persistent terminal V=O feature, implying the formation of a coupled Mo-S-V interfacial environment. H₂-TPR and NH₃-TPD demonstrated that MoS₂ modification simultaneously stabilized the redox structure and moderated the surface acidity, suppressing excessively strong NH₃ retention while maintaining a tunable oxidation-active surface. XPS analysis further revealed atmosphere-dependent redistribution of O_α/O_β species, sulfur oxidation to SO₃²⁻/SO₄²⁻ species, and dynamic V⁵⁺/V⁴⁺ interconversion, confirming that MoS₂ acted not only as a sulfur-containing component but also as an interfacial electronic regulator. Post-reaction Hg 4f XPS showed that retained mercury mainly existed as Hg²⁺ species, while Hg-TPD indicated that MoS₂ modification provided a more diverse and thermally stable mercury-binding environment. These results demonstrate that Hg⁰ removal over V₂O₅⁻MoS₂/TiO₂ proceeds through oxidation-retention coupling rather than simple oxidation alone. The enhanced performance originates from the synergistic effects of active oxygen migration, vanadium redox cycling, sulfur-assisted stabilization, and interfacial Mo-S-V electronic coupling. This work provides a promising strategy for designing multifunctional SCR catalysts in coal-fired plants for efficient Hg⁰ control under practical coal combustion flue-gas conditions. Full article

Aiming at the problem that the selectivity of heterogeneous catalysts is difficult to be controlled and the active components are easy to be lost in the acetylene double carbonylation reaction, this paper constructs a highly efficient Pd-based catalyst through the combination of carrier morphology engineering and surface basicity regulation. Using melamine/urea as a precursor, tubular carbon nitride (TCN) was constructed by hydrothermal calcination, and then Pd/TCN-series catalysts were prepared by ultrasonic-assisted impregnation loading 5 wt% Pd and heat treatment in a N₂ atmosphere. At the same time, bulk g-C₃N₄ (BCN) and activated carbon (AC), TiO₂, and ZSM-5 supported systems were used as controls. The characterization results show that compared to BCN, TCN-500 (calcined at 500 °C) has a higher specific surface area (40.19 m²/g vs. 12.47 m²/g) and pore volume (0.1850 cm³/g vs. 0.0792 cm³/g), which provides abundant anchoring sites and efficient mass-transfer channels for Pd nanoparticles. After the introduction of Pd, the total base amount of the catalyst increased significantly from 0.4866 to 1.7172 mmol/g, and the strong Lewis-base center was significantly enhanced. TEM/XRD confirmed that Pd was uniformly dispersed on TCN-500 and mainly exposed the (111) crystal plane. XPS further revealed that there was a stronger electron-coupling effect between Pd and the support. Under the reaction conditions of 70 °C and 5 h, the selectivity of Pd/TCN-500 to dimethyl butenedioate was up to 83.7% (acetylene conversion was 59.6%), which was significantly better than that of the contrast carrier system. The cycle test showed that the selectivity and conversion of the catalyst were reduced to 54.4% and 41.1%, respectively, on the third use. The performance degradation was mainly attributed to the oxidative damage of the TCN nanotube skeleton and the passivation of the surface active defect sites. In this study, the synergistic effect of tubular morphology and surface Lewis basicity effectively stabilized the Pd active center and regulated the product selectivity, which provided a new idea for the development of efficient heterogeneous catalysts for acetylene double carbonylation in non-petroleum routes. Full article

A comprehensive investigation is presented for cyclohexene, C₆H₁₀, via the vacuum ultraviolet (VUV) absorption spectrum in the photon energy range 4.0–10.8 eV (310–115 nm). Quantum chemical calculations (Density Functional Theory (DFT), Time Dependent Density Functional Theory (TD-DFT) and Equation of Motion Coupled-Cluster Single and Doubles (EOM-CCSD)) are combined with experiments in order to provide the most accurate and up-to-date information about the electronic state spectroscopy of cyclohexene. The spectrum reveals several new features not previously reported in the literature, with special attention to the different Rydberg series converging to (11b)⁻¹ $\tilde{X}{}^{2}B$, (10b)⁻¹ $\tilde{A}{}^{2}B$, (12a)⁻¹ $\tilde{B}{}^{2}A$, (11a)⁻¹ $\tilde{C}{}^{2}A$, and (9b)⁻¹ $\tilde{D}{}^{2}B$ ionic electronic states of cyclohexene. We also provide absolute cross-section values from high-resolution VUV photoabsorption measurements, with photolysis lifetimes in the Earth’s atmosphere from 0 to 50 km altitude being obtained, showing that solar photolysis is not an important sink mechanism at altitudes lower than 22 km, relative to ^●OH radical reactions. Full article