Search Results (26,146)

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

Phosphogypsum (PG) produced by different wet-process phosphoric acid routes exhibits distinct mineralogical characteristics and metal ion release behaviors, which may influence its environmental risk and resource utilization potential. In this study, PG generated from the hemihydrate–dihydrate (HH-DH) and dihydrate (DH) processes was systematically investigated to elucidate the occurrence states, distribution characteristics, and leaching behavior of metal ions. Particle size distribution analysis, water-leaching experiments, Advanced Mineral Identification and Characterization System (AMICS), and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) were employed to characterize the particle size distribution, mineral composition, elemental distribution, and mineral liberation behavior before and after leaching. The results showed that gypsum was the dominant mineral phase, while quartz and phosphorus-containing gypsum (PCG) were the major impurity minerals. K and Na mainly occurred in soluble mineral phases and exhibited high leaching rates, whereas Al, Fe, and Mg were primarily associated with relatively stable insoluble minerals and showed limited leaching behavior. After water leaching, the particle size distribution shifted toward finer particles, accompanied by decreases in gypsum content and mineral liberation degree, especially in HH-DH phosphogypsum. Significant differences in mineral association, metal occurrence states, and ion release behavior were observed between HH-DH and DH phosphogypsum. These findings provide a mineralogical basis for impurity removal, water washing pretreatment, environmental risk control, and the resource utilization of phosphogypsum. Full article

By precisely controlling the growth temperature and coverage, we successfully synthesized a highly ordered zero-dimensional (0D) Sb₁₈ nanocluster and a one-dimensional (1D) Janus Sb nanochain on the Ag₂Sb/Ag(111) surface. Using scanning tunneling microscopy (STM) in combination with density functional theory (DFT) calculations, we characterized their atomic structures and found that the alloy substrate plays a significant role in stabilizing these configurations. Our findings not only demonstrate the feasibility of controllably synthesizing low-dimensional Sb nanostructures on metallic substrates but also provide valuable insights into their growth mechanism. Full article

Psychoactive nitrogen-containing compounds represent a structurally diverse group of natural and synthetic molecules whose interactions with metal ions influence their physicochemical properties, biological activity, and analytical behavior. Although numerous studies have reported the synthesis of metal complexes, solution interactions, and metal-assisted analytical methods, the available knowledge remains scattered across compound classes and has not been comprehensively evaluated. This review summarizes advances in the coordination chemistry of psychoactive nitrogen-containing compounds from ScienceDirect, Google Scholar, and the Cambridge Structural Database (CSD), emphasizing donor atoms, coordination modes, structural diversity, crystallographic characterization, spectroscopic and computational investigations, and the biological properties of the resulting metal complexes. The current literature demonstrates that metal complexation can alter molecular geometry, electronic structure, redox behavior, biomolecular recognition, and pharmacological activity, while also offering opportunities to develop compounds with enhanced antimicrobial, anticancer, antioxidant, and DNA-binding properties. By integrating coordination behavior, structural, and biological aspects within a single framework, this review highlights the central role of metal interactions in psychoactive compounds and identifies emerging opportunities to develop advanced analytical methodologies and functional metal-based systems. Full article

Water retention on the lunar surface is governed by water–mineral interactions, yet the atomic-scale transition from isolated adsorption to high-coverage water accumulation remains insufficiently understood. We perform spin-polarized first-principles calculations to investigate single- and multi-water adsorption on representative surfaces of four major lunar regolith minerals: CaAl₂Si₂O₈, MgFeSi₂O₆, FeTiO₃, and Mg₃FeSi₂O₈. Single-water adsorption reveals that H₂O preferentially anchors at exposed metal sites via O-M coordination, with Ti and Fe sites exhibiting stronger initial binding than Mg, Ca, or Al sites. The Hard–Soft Acid–Base (HSAB) principle provides a qualitative framework for this low-coverage site preference based on Lewis acidity. Specifically, the accessible d-orbitals and localized states of Ti/Fe centers introduce substantial covalent orbital coupling and interfacial polarization, which effectively reinforce the binding with the hard O-donor of water. However, as water coverage increases, the stabilization mechanism undergoes a fundamental transition. At low coverage, adsorption is localized and site-specific, governed by cation acidity. At high coverage, the formation of laterally connected hydrogen-bonded networks becomes the dominant stabilizing factor, and the overall adsorption behavior is increasingly dictated by surface topology and geometric compatibility for hydrogen-bond connectivity rather than by isolated cation acidity. This coverage-dependent evolution from electronic-driven anchoring to topology-driven network formation establishes a dual-stage cooperative mechanism for water accumulation on lunar mineral surfaces. Our findings suggest that models for volatile retention on airless bodies must account for both the electronic activity of surface cations and the structural topology of mineral surfaces. Full article

Surfactants are widely used to promote hydrate formation and improve flow assurance, yet their effects on hydrate surface morphology at the microscale remain poorly understood. Here, in situ Atomic Force Microscopy (AFM) was employed to quantitatively characterize the surface microstructure of tetrahydrofuran (THF) hydrate formed in the presence of five distinct surfactants, with particular emphasis on grain area, protrusion distribution, grain-boundary geometry, and surface roughness. Results show that pure THF hydrate exhibits a relatively smooth and regular grain morphology, with narrow and shallow grain boundaries and only limited protrusions. Surfactant addition induces pronounced surface reconstruction, yet the morphological evolution pathways differed markedly among systems. Surfactants I and II were associated with grain refinement, reducing the average grain area to 71.4 and 89.9 μm², respectively, while protrusions were concentrated mainly near grain boundaries and grain-boundary grooves became deeper, corresponding to a grain-boundary-dominated roughening mode. In contrast, surfactants III–V were associated with grain coarsening, increasing the average grain area to 121.1, 128.2, and 156.0 μm², respectively, together with more pronounced intragranular protrusions and widened grain boundaries, corresponding to an intragranular-dominated roughening mode. All surfactants increase surface roughness of THF hydrate to different extents. These findings reveal that surfactants regulate hydrate surface architecture through site-selective adsorption, offering a mechanistic framework for the molecular design of surfactant additives in hydrate-based applications. Full article

CO₂ hydrogenation to methanol is a key route for carbon recycling within the carbon capture, utilization, and storage (CCUS) framework. Cu-based catalysts are widely employed because of their low cost and high methanol selectivity, yet monometallic Cu suffers from sintering, limited CO₂ activation, and competing reverse water-gas shift (RWGS) reactions. This review systematically summarizes recent advances in Cu-based bimetallic catalysts, categorized as Cu-p-block, Cu-noble metal, Cu-transition metal, and Cu-rare-earth metal systems. Throughout this review, the term “bimetallic catalysts” broadly refers to Cu-based systems containing a second metallic element, which may be present as a metallic alloy, an intermetallic compound, an atomically dispersed promoter species, or an oxide promoter or support component that forms Cu-M or Cu-MO_x interfacial structures. Experimental findings and density functional theory calculations are integrated to clarify how second metals regulate electronic structures, interfacial sites, oxygen vacancies, and hydrogen activation, thereby governing the competition between the formate pathway and RWGS. The dynamic evolution of active sites and the concentration-dependent role of reaction-generated water are also discussed. Finally, current challenges in machine learning-assisted catalyst development are assessed, and future directions involving operando characterization, hydrophobic interface engineering, reactor-level water management, and interpretable data-driven catalyst design are proposed to guide catalyst optimization and practical implementation. Full article

The rapid development of quantum technology and single-photon LiDAR places ever-increasing demands on detection systems in terms of bandwidth suppression, wavelength stability, and transmission accuracy. Conventional narrowband filters, however, are falling short in sub-nanometer bandwidth control and high-temperature stability, thereby failing to support high-precision measurements. Consequently, ultra-narrowband optical filters have emerged as a key approach to overcoming these performance bottlenecks. This paper focuses on the core technologies involved in the development of such filters. In the design phase, multiparameter optimization based on a Fabry–Perot (F-P) etalon translates application requirements into fabrication parameters. For substrate fabrication, a sequential process of computer numerical control (CNC) milling, lapping, chemical–mechanical polishing (CMP), and ion-beam polishing, followed by atomic layer deposition (ALD) step formation and ion-beam evaporation coating, is employed to achieve a nanometer-level surface figure and roughness. Temperature control is achieved via a dual-tank hybrid circulation system, maintaining stability within ±0.1 °C. Test results show that the fabricated filter exhibits a full width at a half maximum (FWHM) of 30–60 pm, a free spectral range (FSR) of 260 ± 5 pm, a temperature stability of ≤3 pm/°C, and a peak transmittance of ≥80%. These results preliminarily confirm the device’s excellent overall performance. Full article

This work addresses the post-combustion CO₂ capture demand, employing a single-atom solvent as the absorbent to conduct systematic research on process modeling, energy consumption analysis, and multi-objective optimization. The energy consumption of the single-atom solvent-enhanced CO₂ capture process was reduced to 2.864 GJ/t, representing a 26.9% reduction compared with that of the conventional solution. The effects of solvent flow rate, gas flow rate, rich solvent temperature, reflux ratio, and extraction ratio on the energy consumption, annual total utility consumption, CO₂ equivalent emissions, and total annual cost were systematically investigated. The results indicate that rich solvent temperature and reflux ratio are the most sensitive parameters affecting system energy consumption variations; increasing solvent flow rate linearly elevates the reboiler duty, whereas gas flow rate variations exert negligible influence on system performance. The energy consumption was further reduced to 1.84 GJ/t CO₂ after process parameter optimization. A multi-objective optimization approach coupling the NSGA-II with Aspen Plus process simulation was developed for economic–energy–environmental optimization. Annual total utility consumption was reduced by 12.75%, CO₂ equivalent emissions per unit of product were reduced by 47.87%, and total annual cost was reduced by 13.09% after optimization. The optimal operating conditions under multi-objective optimization were determined simultaneously. This study provides an optimization strategy for the industrial application of CO₂ capture technology. Full article

During the service life of karst tunnels, groundwater containing Ca²⁺ and CO₃²⁻ can migrate along the shotcrete–surrounding rock interface and induce calcite deposition, thereby changing the interfacial material composition and load transfer path. To clarify the effect of this process on interfacial bonding performance, this study used molecular dynamics simulations to construct CSH–SiO₂, SiO₂–calcite, CSH–calcite, and CSH–calcite–SiO₂ interface models. The interfacial density distribution, radial distribution function, number of hydrogen bonds, interaction energy, and normal tensile failure behavior were analyzed. The results show that all four models reached stable energy plateaus after relaxation, and clear atomic density overlap and short-range RDF peaks appeared in the interfacial regions. These descriptors indicate short-range contact and possible Ca–O electrostatic attraction, hydroxyl-related hydrogen bonding, and carbonate-associated interactions between calcite and both SiO₂ and CSH surfaces. Approximately 80 hydrogen bonds were formed at the SiO₂–calcite interface, approximately 32 at the CSH–calcite interface, and approximately 59 in total for the two hydrogen bond subtypes at the SiO₂–CSH interface, indicating that the hydroxyl state of different substrate surfaces controls the interfacial hydrogen bond network. Interaction energy analysis shows that the single CSH–calcite interface has the strongest interaction (−51,753.6 kcal/mol), approximately 1.90 times that of the SiO₂–CSH interface and 16.43 times that of the SiO₂–calcite interface. However, in the three-layer composite model, the interaction energy on the CSH–calcite side is only approximately 28.0% of that on the SiO₂–calcite side, suggesting that a continuous calcite interlayer introduces asymmetric interfacial constraints. Tensile simulations further show that the SiO₂–calcite model has the highest peak stress (approximately 3.23 GPa) and exhibits brittle failure, whereas failure in CSH-containing systems is more likely to transfer into the CSH layer or weakly connected regions. These results indicate that calcite deposition does not simply strengthen or weaken the interface. Instead, within the two idealized endpoint configurations tested here, its effect depends on deposition continuity, the surface chemistry of the two substrates, and the weak links within the serial interface. This study provides a nanoscale theoretical basis for evaluating relative trends in the long-term service performance of shotcrete–surrounding rock interfaces, and for guiding future multiscale validations of drainage and waterproofing measures in karst tunnels. Full article

Structural defects provide an effective means of tailoring the electronic and optical properties of two-dimensional transition-metal dichalcogenides. In this work, the structural, electronic, and polarization-resolved optical properties of pristine WS₂ and WSe₂ monolayers and their stoichiometric trefoil-like rotational reconstructions were investigated using density functional theory. The reconstruction was generated through a local 60° bond rotation without removing or adding atoms and therefore differs fundamentally from the experimentally observed chalcogen-deficient T₁(3DV) defect. Electronic-structure calculations were performed using the PBE-GGA + U and SOGGA approaches, with noncollinear spin–orbit coupling included in the latter, while the optical response was evaluated within the independent-particle Kubo-Greenwood formalism. Structural relaxation revealed two distinct regimes. In WS₂, the reconstruction produced a largely compensated redistribution of W–S bond lengths, with the mean distance remaining nearly unchanged, whereas WSe₂ exhibited a net expansion of the W–Se coordination network and substantially stronger out-of-plane buckling. The reconstruction introduced additional W 5d–chalcogen p states near the band edges and markedly reduced the electronic band gaps. For WS₂, the gap decreased from 1.87 to 1.55 eV within DFT + U and from 1.96 to 1.46 eV within SOGGA. A substantially stronger response was obtained for WSe₂, for which the corresponding gaps decreased from 1.533 to 0.751 eV and from 1.657 to 0.645 eV. The reconstructed monolayers exhibited pronounced optical anisotropy, red-shifted absorption edges, spectral broadening, and additional low-energy in-plane optical transitions. These effects were particularly strong in WSe₂, where the calculated optical response extended into the near-infrared region. The results demonstrate that the electronic and optical response to a stoichiometric trefoil-like reconstruction is strongly chalcogen-dependent and is governed by the interplay among local geometrical distortion, W 5d–chalcogen p hybridization, and spin–orbit coupling. Full article

Jadeite and omphacite, both pyroxene-group minerals, are the two most dominant component minerals in fei cui (a rock-origin gemstone that may be dominated by jadeite, omphacite, kosmochlor, or their intermediate compositions), and classifying jadeitic vs. omphacitic domains is key to identification, grading, and evaluation. However, determining their proportion quantitatively often needs destructive analyses, which is not suitable for high-value fei cui samples. In this study, 29 fei cui samples were selected to obtain electron probe micro-analysis (EPMA) data and infrared reflectance spectra. We found that six characteristic peaks and the intensity ratio (I_B/I_C) near 1085–1066 cm⁻¹ and 963–946 cm⁻¹ showed strong linear correlations with the Na/(Na+Ca) atomic ratio in the jadeite–omphacite series of the studied fei cui, upon which an infrared spectroscopy semi-quantitative screening method was then developed. In this method, the I_B/I_C ratio from infrared spectra was derived to provisionally estimate the Na/(Na+Ca) atomic ratio according to statistical models; for jadeite (Na/(Na+Ca) atomic ratio > 0.8), its I_B/I_C ratio > 1.68, whereas for omphacite (Na/(Na+Ca) atomic ratio ≤ 0.8), its I_B/I_C ratio ≤ 1.68. This finding has implications for provisionally discriminating jadeitic from omphacitic domains non-destructively. Furthermore, by FTIR mapping using micro-FTIR, heatmaps based on the calculated I_B/I_C ratio at each scanned spot allow observation of the spatial distribution of jadeite-dominant and omphacite-dominant domains classified as jadeitic or omphacitic according to the Na/(Na+Ca) ratio, providing a semi-quantitative estimate of their mapped areal proportion on the polished surface. The method and its application were reinforced by micro-XRF mapping; Na and Ca elemental heatmaps show the same distribution in the same region, and would satisfy the increasing demand in fei cui testing. Full article

Carbon-based materials are widely employed in electrocatalytic energy conversion and storage technologies owing to their high electrical conductivity, chemical stability, tunable structure, and low cost. However, the limited intrinsic activity and surface inertness of pristine carbon materials often necessitate surface modification to generate catalytically active sites and improve interactions with reactants and electrolytes. Among the available approaches, plasma functionalization has emerged as a versatile, rapid, solvent-free, and potentially resource-efficient technique that enables systematic tuning of surface chemistry while often limiting modification primarily to the near-surface region. This review discusses the fundamentals of plasma-assisted surface modification of carbon materials, including plasma generation, reactive species, plasma–surface interaction mechanisms, and the influence of key processing parameters such as gas composition, power, pressure, and treatment time. Particular attention is devoted to plasma-induced heteroatom doping, defect engineering, surface functionalization, and the dynamic structural evolution of carbon frameworks during treatment. The impact of these modifications on the physicochemical properties and electrocatalytic performance of carbon materials is critically examined with respect to representative reactions, including the oxygen reduction, oxygen evolution, and hydrogen evolution reactions. The advantages, limitations, and scalability of plasma technologies are also discussed, along with current challenges in process control and reproducibility. Finally, future opportunities involving operando diagnostics, single-atom catalysts, advanced porous carbon architectures, and industrial-scale plasma processing are highlighted. Plasma processing offers a versatile route to carbon surface and catalyst-interface engineering, although standardized reporting and quantitative plasma–structure–performance relationships are still required for rational process design and scale-up. Full article

Lung cancer ranks first among all malignancies in both incidence and mortality worldwide, and precise target volume delineation is the key to ensuring the efficacy and safety of radiotherapy. Conventional CT imaging has significant limitations in distinguishing tumors from surrounding normal tissues, particularly in the presence of atelectasis or inflammation, which compromises the accuracy of target delineation. As an advanced imaging technology, spectral CT can provide multi-dimensional information, including material composition analysis, monoenergetic images, and effective atomic number mapping, offering groundbreaking potential to enhance the precision of lung cancer target volume delineation. This article provides a comprehensive overview of the fundamental principles of spectral CT, explores its specific application value in lung cancer target volume delineation, analyzes the current challenges, and provides an outlook on future development trends, aiming to serve as a comprehensive reference for clinical practice and scientific research. Full article

MicroRNAs (miRNAs) represent highly promising biomarkers for non-invasive clinical diagnostics. To overcome the limitations of conventional methods, Field-Effect Transistor biosensors (bioFETs) emerge as compelling alternatives by providing label-free and real-time readouts. However, bioFETs employing canonical DNA/RNA probes face fundamental limitations due to the Debye screening effect. Peptide Nucleic Acid (PNA), a synthetic nucleic acid analog featuring an uncharged peptide-like backbone, offers an effective solution. PNA’s electroneutrality allows for efficient hybridization at a low ionic strength, thereby mitigating Debye screening constraints. PNA also offers additional key advantages, including high specificity and enzymatic resistance. This work examines recent advancements in PNA–bioFETs, highlighting their potential for the development of robust platforms for clinical miRNA evaluation. Surface Plasmon Resonance (SPR) and Atomic Force Spectroscopy (AFS) are valuable tools to preliminarily characterize probe–target interactions. Key approaches, focused on implementing alternative PNA probe designs and optimizing Self-Assembled Monolayer (SAM) organization, are outlined. By presenting a cross-study comparison that correlates each strategy with the analytical outcomes of a custom-designed bioFET platform targeting miRNA 155, complemented by an overview of PNA–bioFETs across other miRNAs, we illustrate how the synergy between PNA and bioFET can approach reliable miRNA detection, paving the way for the development of Point-of-Care (POC) devices. Full article