Search Results (3,510)

Electrochemical CO₂ reduction reaction (CO₂RR) is a key technology for achieving carbon neutrality and efficient utilization of renewable energy, capable of converting CO₂ into high-value-added carbon-based fuels and chemicals. Copper (Cu)-based catalysts have attracted significant attention due to their unique performance in generating multi-carbon (C₂₊) products such as ethylene and ethanol; however, there are still many controversies regarding their complex reaction mechanisms, active sites, and the dynamic evolution of intermediates. In situ Raman spectroscopy, with its high surface sensitivity, applicability in aqueous environments, and precise detection of molecular vibration modes, has become a powerful tool for studying the structural evolution of Cu catalysts and key reaction intermediates during CO₂RR. This article reviews the principles of electrochemical in situ Raman spectroscopy and its latest developments in the study of CO₂RR on Cu-based catalysts, focusing on its applications in monitoring the dynamic structural changes of the catalyst surface (such as Cu⁺, Cu⁰, and Cu²⁺ oxide species) and identifying key reaction intermediates (such as *CO, *OCCO(*O=C-C=O), *COOH, etc.). Numerous studies have shown that Cu-based oxide precursors undergo rapid reduction and surface reconstruction under CO₂RR conditions, resulting in metallic Cu nanoclusters with unique crystal facets and particle size distributions. These oxide-derived active sites are considered crucial for achieving high selectivity toward C₂₊ products. Time-resolved Raman spectroscopy and surface-enhanced Raman scattering (SERS) techniques have further revealed the dynamic characteristics of local pH changes at the electrode/electrolyte interface and the adsorption behavior of intermediates, providing molecular-level insights into the mechanisms of selectivity control in CO₂RR. However, technical challenges such as weak signal intensity, laser-induced damage, and background fluorescence interference, and opportunities such as coupling high-precision confocal Raman technology with in situ X-ray absorption spectroscopy or synchrotron radiation Fourier transform infrared spectroscopy in researching the mechanisms of CO₂RR are also put forward. Full article

The search for bioactive compounds against chronic diseases such as cancer and diabetes
includes curcuminoids as promising scaffolds. Here, we report the synthesis of a family
of curcuminoid analogue compounds with an extended unsaturated central chain, as follows:
difluoroboron complex 1, the enolised curcuminoid 2, and its homoleptic copper
complex 3, in moderate to good yields (68–90%). Additionally, their β-cyclodextrin (BCD)
association complexes, 4 and 5, were prepared through a mechanochemical method and
characterised by spectroscopic techniques. Complete ¹H and ¹³C NMR assignments and
NOESY correlations revealed unique solvent effects on the conformational disposition of
compound 2, while the copper complex 3 displayed the highest extinction coefficient (1.20
× 10⁵ M⁻¹·cm⁻¹). Furthermore, the authentication of the polymorph of 1 and the new crystal
structures of 2 and 3, determined by single-crystal X-ray analysis, were highlighted. Although
the copper complex 3 initially exhibited the lowest a-glucosidase inhibitory activity
(IC₅₀ > 100 μM), it showed a significant increase (IC₅₀ = 36.27 μM) upon association with
BCD, reaching values comparable to the free ligand (IC₅₀ = 45.63 μM). Compounds 1–5
were non-toxic to healthy cells (COS-7), but compound 5 stands out as a promising candidate
against this metabolic condition. Full article

Biodegradable polymers offer a promising solution to the growing issue of global microplastic pollution. To effectively replace conventional plastics, it is essential to develop strategies for tuning the properties of biodegradable polymers without relying on additives. Biaxial stretching promotes anisotropic crystallization in polymer domains, thereby altering the mechanical performance of polymer blends. In this study, we employed a design of experiment (DoE) approach to investigate the effects of biaxial stretching at three drawing temperatures (T_ds) and draw ratios (λs) on a biodegradable blend of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT), aiming to optimize both the strength and ductility. The DoE analysis revealed that the composition, the λ, the interaction between the λ and composition, and the interaction between the T_d and composition significantly affect the elongation at break (ε_Break). For the stress at break (σ_Break), the most influential factors were the interaction between the λ and PLA concentration; a three-way interaction among the λ, PLA, and T_d; the T_d; the λ; and finally the PLA concentration alone. The optimal ε_Break and σ_Break were achieved at a λ = 5 × 5 and T_d = 110 °C, with a composition of 10% PLA and 90% PBAT. The stretched samples exhibited higher crystallinity compared to the pressed samples across all compositions. This work demonstrates that in addition to the composition, the processing parameters, such as the λ and T_d, critically influence the mechanical properties, enabling performance enhancements without the need for compatibilizers or toxic additives. Full article

The combined effects of accelerated carbonation and lime sludge incorporation on the mechanical and durability performance of fiber-cement composites were assessed in this study. Lime sludge was used to replace 0%, 10%, and 20% of the cement in the composites, which were then autoclave-cured and carbonated more quickly for two or eight hours. With LS20-C8 (20% lime sludge, 8 h carbonation) achieving the highest carbonation efficiency (74.0%), X-ray diffraction (XRD) verified the gradual conversion of portlandite into well-crystallized calcium carbonate (CaCO₃). In terms of mechanical performance, LS20-C8 outperformed the control by increasing toughness by 16.7%, flexural strength by 14.2%, compressive strength by 14.6%, and compressive modulus by 20.3%. The properties of LS20-C8 were better preserved after aging under wetting-drying cycles, as evidenced by lower losses of toughness (10.0%) and compressive strength (10.1%) compared to the control (14.6% and 18.3%, respectively). The mechanical improvements were explained by optical microscopy, which showed decreased porosity and an enhanced fiber–matrix interface. Overall, the findings show that adding lime sludge to accelerated carbonation improves durability, toughness, strength, and stiffness while decreasing porosity. This method helps to value industrial byproducts and is a sustainable and efficient way to create long-lasting fiber-cement composites. Full article

This study investigates the structural and magnetic properties of ultra-high coercivity (Fe₈₀B₁₄Nb₆)_0.88Dy_0.12 alloys, doped with 0.5–5 at.% of selected metallic additions: magnetic (Ni, Co) and non-magnetic (Pt, Cu) elements. Material characterization involved both structural and magnetic measurements. Alloys containing dopant concentrations up to 2 at.% exhibited similar phase compositions, with the Dy₂Fe₁₄B compound being dominant. Magnetic hysteresis loops revealed a superposition of two components: magnetically soft and hard phases. A significant change in magnetic properties was observed within the 0.5 to 1 at.% dopant concentration range. Notably, the addition of 0.5 at.% Ni increased the apparent anisotropy field from 5.2 T to 7.5 T. Furthermore, 0.5 at.% Pt led to an increase in the coercive field from 4.6 T to 5.5 T. These additions influenced crystallization, resulting in the formation of a more regular microstructure without submicrometric dendrite branches, when compared to the base alloy. Full article

A systematic investigation was conducted into the effects of varying Al₂O₃ and SrO contents on the structure, sintering kinetics, crystallization patterns, and properties of the SrO-BaO-ZnO-MgO (RO)-B₂O₃-Al₂O₃-SiO₂ (RBAS) system. This glass-ceramic demonstrates effective applicability for low-temperature co-firing of alumina ceramics. Increasing Al₂O₃ content densified the glass network and reduced crystallinity, thereby promoting sintering densification. It led to improved acid resistance and a lower coefficient of thermal expansion (CTE). The composition with 17.50 mol% Al₂O₃ sintered at 800 °C exhibited optimal properties: a well-matched CTE of 7.45 × 10⁻⁶ K⁻¹, a high flexural strength of 130.58 MPa, and excellent chemical stability. Furthermore, it demonstrated excellent compatibility when co-sintered with an Al₂O₃ substrate. Full article

Calcium carbonate (CaCO₃) is a dominant component of sedimentary rocks and biogenic structures, and is one of the most frequently studied inorganic compounds. It also plays a key role in preparing modern engineered materials. CaCO₃ has three well-known polymorphs, calcite, aragonite, and vaterite, and four solvatomorphs with diverse crystallographic arrangements, hydration states, reactivity, and stability. Its solvatomorphs include the variable water-containing amorphous calcium carbonate (ACC—CaCO₃·xH₂O) and the crystalline monohydrocalcite (MHC—CaCO₃·H₂O), calcium carbonate hexahydrate (ikaite—CaCO₃·6H₂O), and the recently reported hemihydrate (CCHH—CaCO₃·0.5H₂O). Here, we review the preparation, crystal structure, and properties of these solvatomorphs and discuss their mutual transformations. Full article

An increase in the production of cationic dyes is expected over the next decade, which will have an impact on health and the environment. This work reports an adsorbent hydrogel composed of poly(acrylic acid) [poly(AA)] and Fe₃O₄ particles, prepared by radical polymerization and in situ co-precipitation of Fe³⁺ and Fe²⁺. This Fe₃O₄/poly(AA) composite hydrogel was used to evaluate its potential for removing the cationic dyes methylene blue (MB) and crystal violet (CV) from aqueous solutions. Instrumental characterization of the hydrogel was performed by FTIR, XRD, TGA, VSM, and physicochemical analysis (swelling and response to changes in pH). The results show that the incorporation of Fe₃O₄ particles improves the adsorption capacity of MB and CV dyes to a maximum adsorption of 571 and 321 mg/g, respectively, under the best conditions (pH 6.8, dose 1 g/L, time 24 h). The adsorption data best fit the pseudo-first order (PFO) kinetic model and the Freundlich isothermal model, indicating mass transfer via internal and/or external diffusion and active sites with different adsorption potentials. Moreover, the thermodynamic analysis confirmed that the adsorption process was spontaneous and exothermic, with physisorption as the dominant mechanism. In addition, the Fe₃O₄/poly(AA) hydrogel is capable of removing 95% of the dyes after ten consecutive adsorption–desorption cycles, demonstrating the potential of hydrogels loaded with Fe₃O₄ particles for the treatment of wastewater contaminated with dyes. Full article

This study provides an in-depth analysis of the learning dynamics of multichannel optical neurons based on spatial solitons generated in lithium niobate crystals. Single-node and multi-node configurations with different topological complexities (3 × 3, 4 × 4, and 5 × 5) were compared, assessing how the number of channels, geometry, and optical parameters affect the speed and efficiency of learning. The simulations indicate that single-node neurons achieve the desired imbalance more rapidly and with lower energy expenditure, whereas multi-node structures require higher intensities and longer timescales, yet yield a greater variety of responses, more accurately reproducing the functional diversity of biological neural tissues. The results highlight how the plasticity of these devices can be entirely modulated through optical parameters, paving the way for fully optical photonic neuromorphic networks in which memory and computation are co-localized, with potential applications in on-chip learning, adaptive routing, and distributed decision-making. Full article

A series of cobalt(II) dicyanamide (dca⁻) coordination polymers with substituted pyrazines (pyz) and pyrimidines (pym) as auxiliary ligands have been synthesized and structurally characterized to investigate the influence of the type and substitution pattern of the auxiliary ligand on the dimensionality and topology of the resulting frameworks. As a result of our studies, 13 novel heteroleptic cobalt(II) dicyanamide coordination polymers were obtained, and their crystal structures were determined by single-crystal X-ray diffraction. Eight of the investigated compounds exhibit a single-chain structure composed of [Co(L_pyz/_pym)₂]²⁺ units bridged via double μ_1,5–dca ligands. In two complexes, neutral triple-chain topologies were observed, in which double μ_1,5– and single μ_1,3,5–dca bridges connect two crystallographically independent cobalt(II) ions, both being six-coordinate in tetragonally elongated octahedral environments. Two- and three-dimensional architectures were confirmed only in the case of Co(II) compounds with 2,6–Me₂pyz and 4-NH₂-pym co-ligand, respectively The cobalt(II) complexes described herein have also been compared with dicyanamide-based cobalt(II) systems incorporating pyrazine- and pyrimidine-like ligands. These structural relationships are of high significance for the rational design and synthesis of heteroleptic cobalt(II) dicyanamide systems. Full article

Nanocrystalline CoWO₄ sampled were synthesized using a simple mechanochemical approach and a solid-state reaction, respectively. The formation of nanocrystalline CoWO₄ was characterized by X-ray diffraction (XRD) and infrared spectroscopy (IR). The optical properties of the obtained samples were explored by diffuse reflectance UV–visible (DRS) and photoluminescence (PL) techniques. A milling speed of 850 rpm led to the direct synthesis of monoclinic CoWO₄ with a short reaction time (1 h). The complete reaction did not occur in the solid-state synthesis. The obtained samples had monoclinic crystal systems with different lattice parameters. The average crystallite sizes of CoWO₄ were in the range of 20 to 180 nm. The TEM investigation showed that the morphology of the CoWO₄ particles differed depending on the preparation conditions. The values of the determined optical bandgap of CoWO₄ were the range of 1.89 to 2.18 eV, according to diffusion reflectance spectroscopy in the ultraviolet-to-visible range. Broader blue–green emission spectra with peaks at 430 nm were observed for samples prepared via both routes. The CIE color coordinates of the CoWO₄ samples lay in the blue and purple regions. The quantum yields of the CoWO₄ samples synthesized after 1 h and 5 h milling times at 850 rom were 0.34 and 0.67%, respectively. This study proposes an affordable mechanochemical approach for blue–green phosphors that could possibly be used in various light-emitting diodes (LEDs). Full article

Four 8-acyl-1-pyrrolidinylnaphalenes are prepared where the acyl group is pivaloyl (6), benzoyl (7), benzyloxycarbonyl (8), and ethyloxycarbonyl (9). Crystal structures for 6–8 show that both the carbonyl and pyrrolidinyl groups are nearly perpendicular to the naphthalene ring. Esters 8 and 9 fluoresce more strongly than ketones 6 and 7. All show some solvatofluoro-chromic emission from a charge-transfer excited state. Calculations suggest that both the acyl and amino groups twist back toward planarity with the naphthalene in the relaxed first singlet excited state. With 8 and 9, co-planarity is within 20°, while with 6 and 7, the carbonyl approaches no closer than 30°. With 6 and 7, the charge-transfer emission is replaced with a shorter wavelength band with more polar solvents. Despite the twisted geometries and steric interference toward planarization, these systems do not show emission from a twisted intramolecular charge-transfer (TICT) state. Full article

Biocatalytic nanomembranes have emerged as promising platforms for micropollutant remediation, yet their practical application is hindered by limitations in removal efficiency and operational stability. This study presents an innovative approach for fabricating highly stable and efficient biocatalytic nanomembranes through the co-immobilization of horseradish peroxidase (HRP) and glucose oxidase (GOx) within a covalent organic framework (COF) nanocrystal. Capitalizing on the dynamic covalent chemistry of COFs during their self-healing and self-crystallization processes, we achieved simultaneous enzyme immobilization and framework formation. This unique confinement strategy preserved enzymatic activity while significantly enhancing stability. HRP/GOx@COF biocatalytic membrane was prepared through the loading of immobilized enzymes (HRP/GOx@COF) onto a macroporous polymeric substrate membrane pre-coated with a polydopamine (PDA) adhesive layer. At HRP and GOx dosages of 4 mg and 4.5 mg, respectively, and a glucose concentration of 5 mM, the removal rate of bisphenol A (BPA) reached 99% through the combined functions of catalysis, adsorption, and rejection. The BPA removal rate of the biocatalytic membrane remained high under both acidic and alkaline conditions. Additionally, the removal rate of dyes with different properties exceeded 88%. The removal efficiencies of doxycycline hydrochloride, 2,4-dichlorophenol, and 8-hydroxyquinoline surpassed 95%. In this study, the enzyme was confined in the ordered and stable COF, which endowed the biocatalytic membrane with good stability and reusability over multiple batch cycles. Full article

Bicalutamide (BCL), a clinically important non-steroidal antiandrogen, exhibits pronounced conformational polymorphism and complex solid-state behaviour that critically influence its physicochemical and biopharmaceutical properties. This review comprehensively integrates current computational and experimental findings on the structural features, polymorphic forms, and intermolecular stabilisation mechanisms of BCL. Key factors, including torsional flexibility, hydrogen-bond networks, π–π stacking, and fluorine–fluorine contacts, are examined with respect to polymorph stability, solubility, and dissolution kinetics. The review also synthesises recent advances in solid-state optimisation strategies—including co-crystals, solvates, amorphous forms, and solid dispersions—and explores the emerging role of supercritical fluid (SCF) technologies in particle engineering and dissolution enhancement. This work offers a framework for designing next-generation BCL solid forms with enhanced bioavailability and stability by connecting molecular insights with formulation approaches. Full article