Search Results (539)

Carbon dots have emerged as promising nanocarriers for drug delivery due to their unique physicochemical properties and biocompatibilities. Here, the potential of leaf-derived carbon dots (named as SBL_CD), derived from Seabuckthorn (Hippophae rhamnoides L.), was illustrated as a novel nano-formulation for bioactive compound delivery. Seabuckthorn leaves, rich in flavonoids, are the waste product during the production of Seabuckthorn fruits. The wasted leaves were utilized to synthesize carbon dots via a hydrothermal method. The resulting SBL_CD, characterized by TEM, FT-IR and Raman spectroscopy, exhibited a diameter of ~5 nm in both amorphous and quasi-crystalline forms. Applications of SBL_CD in cultures demonstrated robust properties of anti-inflammation and inducing neuronal cell differentiation. Furthermore, SBL_CD was able to encapsulate luteolin, a bioactive flavonoid. The enhanced delivery efficiency translated to superior biological activity, with SBL_CD-luteolin requiring only 1.50 μg/mL in achieving the EC₅₀ efficacy, as compared to 6.82 μg/mL for free luteolin in pNF200-Luc expression assays. This approach not only valorizes Seabuckthorn leaf by-products but also potentially improves the efficacy of encapsulated flavonoids. The development of SBL_CD as a multifunctional platform for flavonoid delivery represents a promising strategy in enhancing the efficacy of neuroactive compounds, combining anti-inflammatory effects (>70% cytokine suppression) with enhanced cellular uptake (4.5-fold increase). Full article

This study investigated the hierarchical structuring of *BEA zeolite using 0.2 M sodium hydroxide followed by 0.5 M hydrochloric acid (T-NaOH-HCl). Tungsten trioxide (WO₃) was then impregnated at different loadings (5, 10, 15, and 20 wt.%) onto the hierarchized materials (BEA-T). The modified zeolites were subsequently used as catalysts for the dehydration of ethanol (230 and 250 °C) and 1-propanol (230 °C). The hierarchization treatment increased the Si/Al ratio (from 13 to 39), decreased relative crystallinity by 15%, and reduced the average crystal-domain size (from 18 to 10 nm). After the NaOH–HCl treatment (BEA-T), the mesopore area increased by 7%, the mesopore volume by 19%, and the total pore volume by 12%. Conversely, the BET specific surface area and micropore volume decreased, indicating effective hierarchization of the *BEA zeolite. XRD, FT-IR and Raman confirmed the presence of monoclinic WO₃ on the BEA-T surface. MAS NMR analyses of ²⁷Al and ²⁹Si indicated that the T-NaOH-HCl treatment slightly increased the population of tetrahedral Al environments. The high conversion and selectivity from the dehydration of ethanol and 1-propanol can be attributed to a moderate reduction in the acidity of *BEA zeolite and tunned mesoporosity. Based on TON, catalysts with 10% and 20% WO₃ stood out in dehydration tests. Full article

Understanding the molecular mechanisms of protein–nanoparticle interactions is crucial for enabling the development of new applications in biomedicine and nanotechnology. Ubiquitin, an important and structurally small functional protein, plays a central role in numerous cellular processes. Therefore, in the current study, we focused on the few-layer graphene (FLG)–Ubiquitin complexes formed by exfoliating FLG structures using only water. Optical spectroscopic techniques (Raman, FT-IR, UV-Vis and circular dichroism) were employed to investigate these complexes on the molecular level. Overall, both CD and FT-IR data reveal that the formation of the FLG–Ubiquitin complexes occurred without inducing disordered structures in the protein. Based on the existence of a blue shift (hypsochromic shift) in the UV-Vis data, the presence of a single tyrosine and two phenylalanine residues in ubiquitin enables the detection of FLG-induced micro-environmental changes, particularly influencing the protein’s β-sheet and α-helix structures. The CD spectral results and CDPro quantitative estimations are in line with ATR FT-IR results, confirming the absence of disordered structure formation while altering the protein’s chirality. UV-Vis and CD spectroscopy results revealed concentration-dependent trends consistent with FLG–protein interactions that preserve the overall protein structure. This study has potential applications in both academic research and practical usage, particularly in biomedicine and nanotechnology specifically for FLG. Full article

Contemporary science is seeking simple and scalable methods of producing stable colloidal solutions of carbon nanomaterials that have favorable optical properties. Pyrolytic carbon (PyC), a by-product of methane pyrolysis, is a promising sustainable material. This study developed a method of obtaining stable PyC colloids using ultrasonic homogenization and investigated the effects of solvent polarity on dispersion, stability, and photoluminescence. Mechanically fragmented PyC was ultrasonically treated in ethanol, acetonitrile, and cyclohexane. Characterization using dynamic light scattering, UV-Vis spectroscopy, photoluminescence, Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and electron microscopy revealed that solvent polarity significantly influenced fragmentation and colloid stability. Polar solvents, especially ethanol, promoted better dispersion of aggregates, whereas nonpolar cyclohexane produced smaller, yet unstable aggregates. Raman and FT-IR analyses confirmed graphitic domains and oxygen-containing surface groups, which are critical to colloidal stability. UV-Vis spectra displayed solvent-dependent shifts in absorption edges, while photoluminescence spectra showed blue emission centered at ~490 nm, which is linked to surface states. Electron microscopy verified the presence of spherical nanoparticles with a diameter of ~20 nm and high carbon purity after sedimentation. These results demonstrate that ultrasonic treatment combined with solvent selection provides a straightforward route to photoluminescent PyC colloids with potential applications in sensors, bioimaging, and optoelectronics. Full article

Modification of zeolitic structures through the incorporation of transition metal oxides has proven to be a promising approach for heterogeneous catalysis. In the present study, *BEA zeolite was modified using the incipient wetness impregnation method with varying amounts (10, 20, and 40 wt.%) of iron(III) oxide to investigate its structural and physicochemical properties. Characterization techniques such as XRD, UV–Vis DRS, FT–IR, Raman spectroscopy, SEM/EDS, TEM/EDS, and SAED, as well as textural and thermal analyses, were employed to assess the main changes. Different iron species were detected, including isolated iron(III) and well-dispersed Fe₂O₃ nanoparticles coating the zeolite surface. Under the synthesis conditions, increased Fe₂O₃ loading promoted hematite nanocrystal growth and the formation of the α-Fe₂O₃ phase, as demonstrated by XRD, Raman, and SAED analyses. Key observations included the preservation of the zeolite framework, high relative crystallinity (ranging from 70% to 85%), and a band gap of approximately 2.0 eV. Furthermore, a general increase in mesoporosity and external surface area was observed, along with a reduction in the number of acidic sites. This decrease may be attributed to restricted accessibility of the probe molecule (pyridine) to Brønsted sites due to micropore blockage in *BEA. These results demonstrate that the adopted synthesis method effectively produced α-Fe₂O₃/BEA catalysts, with no other crystalline phases of iron(III) oxide detected. Full article

The crystal structures and vibrational spectra of 5-chloro-7-azaindole (5Cl7AI), 4,5-dichloro-7-azaindole (4,5Cl7AI), and 5-hydroxy-7-azaindole (5OH7AI) were investigated to elucidate how ring substituents modulate intermolecular hydrogen bonding and molecular packing in the solid state. Density functional theory (DFT) calculations were employed to support the interpretation of the spectroscopic data, while Hirshfeld surface analysis provided additional insight into intermolecular contacts. Single-crystal X-ray diffraction revealed that the halogenated derivatives form nearly linear N–H···N hydrogen-bonded dimers or layered arrangements, whereas 5OH7AI adopts a three-dimensional network stabilized by N–H···O and O–H···N interactions. FT-IR and FT-Raman spectra showed that variations in hydrogen-bond topology strongly affect the N–H and O–H stretching regions: the halogenated derivatives exhibit broad, red-shifted bands (3300–2500 cm⁻¹) characteristic of N–H···N hydrogen bonds, while 5OH7AI displays smaller red shifts of the N–H stretching bands accompanied by some additional features from O–H stretching vibrations. DFT calculations at the B3LYP-D3 and ωB97X-D levels reproduced the experimental geometries and vibrational spectra very well, providing detailed insight into the relationship between hydrogen-bond linearity, network dimensionality, and vibrational behavior. Full article

Hybrid buckypapers (BPs) composed of graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) hold great potential for applications in flexible electronics, electromagnetic shielding, and energy storage. In this study, hybrid BPs were fabricated and characterized to evaluate their structural, thermal, and electrical properties. Hybrid BPs with varying GNP/CNT mass ratios (0/100, 25/75, 50/50, 75/25, 85/15, 90/10, and 95/5 wt%) were prepared via vacuum-assisted filtration of well-dispersed aqueous suspensions stabilized by surfactants. The resulting hybrid GNP/CNT BPs were dried and subjected to post-treatment processes to enhance structural integrity and electrical performance. Characterization techniques included scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectroscopy, thermogravimetric analysis (TGA), nitrogen adsorption/desorption isotherms, and impedance spectroscopy (IS). The hybrid GNP/CNT BPs exhibited electrical conductivities comparable to conventional CNT-based BPs. At GNP concentrations of 25 to 50 wt%, electrical conductivity values approached those of CNT-based BPs, while at GNP concentrations between 75 and 90 wt%, a slight increase in conductivity was observed (171%). These results highlight a synergistic effect at lower CNT concentrations, where the combination of CNTs and GNPs enhances conductivity. The findings suggest that optimal conductivity is achieved through a balanced incorporation of both materials, offering promising prospects for advanced BP applications. Full article

Seafood-derived carbonate waste, primarily calcium carbonate (CaCO₃), has attracted growing interest for sustainable reuse, yet the unique potential of aged biogenic sources remains underexplored. Blue crab (Callinectes sapidus) shells are particularly distinctive: they consist of Mg-calcite with an intrinsic 3D-porous structure and naturally embedded astaxanthin, a potent antioxidant not found in other calcite- or aragonite-based residues. While organic degradation over time is often assumed to compromise functionality, this study demonstrates that five-years-aged crustacean shell waste retains both its crystallinity and bioactive carotenoids after calibrated ball milling. Across four powder batches produced under distinct milling conditions by varying frequencies and durations, dynamic light scattering confirmed only subtle particle size variation, while Raman spectroscopy, XRD, FT-IR, and SEM-EDX confirmed structural and chemical integrity and highlighted the subtle amorphization induced by slightly different milling parameters, which, in turn, driven to slightly different conversion efficiency into phosphate mineral. Strikingly, all powders underwent rapid transformation into dicalcium phosphate dihydrate (brushite) enriched with carotenoids upon reaction with phosphoric acid. This work reveals, for the first time, that years-aged biogenic Mg-calcite waste not only preserves its naturally embedded carotenoids but also offers a direct route to functional phosphate composites, establishing its untapped value in environmental and biomedical applications. Full article

Graphite anodes are widely used as consumable electrodes in the high-temperature electrolytic production of rare earth metals within fluoride molten salts. However, their rapid and complex corrosion presents significant economic and operational challenges, including high consumption costs, process instability, greenhouse gas emissions, and product contamination. While the corrosion morphology of specific graphite types has been studied, a systematic investigation linking the intrinsic properties of diverse graphite materials to their microstructural and chemical evolution during corrosion is lacking. This study elucidates the corrosion mechanisms of three distinct graphite anodes—fine-grained, isostatically pressed graphite anodes (#1), medium-coarse-grained, extruded graphite anodes (#2), and recycled, extruded graphite anodes (#3) in industrial PrNdF₃–LiF molten salt electrolytes at 1050 °C. Through a multifaceted analytical approach encompassing SEM, EDS, XRD, Raman, and FT-IR, we investigated the macro- and microscale corrosion behaviors across multiple scales. The results revealed markedly different degradation patterns: the #1 anode exhibited intergranular corrosion with granular exfoliation; the #2 anode developed a protective but cracked resolidified salt layer; and the #3 anode suffered the most severe uniform and pitting corrosion. Postcorrosion analysis confirmed surface enrichment with fluorine, praseodymium, and neodymium, the formation of PrF₃ and NdF₃ phases, and substantial degradation of the graphitic structure. Raman spectroscopy specifically revealed a reduction in the crystallite size, introduction of in-plane point defects, and disruption of the interlayer stacking order. On the base of infrared spectroscopy analysis, all key characteristic absorption peaks of the graphite anodes undergo consistent attenuation after corrosion. This work provides critical insights for the informed selection and optimization of graphite anodes to increase the efficiency and sustainability of rare earth electrolysis. Full article

N^G, N^G-dimethylarginine (ADMA) is an endogenous compound that acts as a competitive inhibitor of nitric oxide synthase (NOS), thereby reducing nitric oxide (NO) production and contributing to endothelial dysfunction. This dysfunction plays a pivotal role in the development of various pathological conditions, including cardiovascular disease, chronic renal failure, and diabetes. The diminished bioavailability of NO is a critical factor in the progression of these disorders, and alterations in ADMA levels have emerged as significant predictors of cardiovascular events and mortality. In this study, we investigated the molecular characteristics of ADMA using a combined approach of Raman and Fourier Transform Infrared (FT-IR) spectroscopy, complemented by computational simulations with the GaussView 5.0.8 and Gaussian 09 software suite. Experimental Raman and FT-IR spectra were acquired and compared with simulated spectra generated through Density Functional Theory (DFT) calculations. This comparative analysis enabled precise vibrational band assignments and the identification of key molecular vibrational modes, providing valuable insights into ADMA’s structural and vibrational properties. These findings establish a comprehensive spectroscopic reference for ADMA, supporting its potential application as a biomarker in clinical diagnostics. Full article

The organic/inorganic hybrid compound bis(2-amino-6-bromopyridinium) tetrachloridocuprate(II) (HABPy)₂[CuCl₄] was synthesized in crystalline form in a 77% yield from aqueous HCl solutions containing Cu(OAc)₂ and 2-amino-6-bromopyridine (ABPy). Single-crystal X-ray diffraction analysis revealed that the compound crystallizes in the monoclinic, centrosymmetric space group C2/c. The Cu atom shows a distorted tetrahedral coordination geometry with a τ₄ value of 0.69 (τ₄ = 1 for a perfect tetrahedron). The structure consists of organic (HABPy)⁺ cation layers at z = 0 and z = ½, alternating with inorganic [CuCl₄]²⁻ dianion layers at z = ¼ and z = ¾. These layers, parallel to the (001) plane, are interconnected by a plethora of supramolecular forces such as N–H···Cl hydrogen bonds, forming a three-dimensional network. Powder X-ray diffraction confirmed the purity of the synthesized bulk material. Fourier-transform infrared (FT-IR) spectroscopy and Raman spectroscopy support the protonation of the pyridine N atom. Hirshfeld surface analysis allowed us to further study the supramolecular forces in the crystal structure. The material shows purely paramagnetic behavior according to S = ½ with an effective magnetic moment µ_eff of 1.85 µB and a g factor of 2.14, in keeping with magnetically isolated [CuCl₄]²⁻ dianions. UV-vis diffuse reflectance spectroscopy of the orange-red material showed a tiny band at 314 nm and an intense band peaking at 622 nm. The optical gap was found to be 2.25 eV. The photoluminescence spectrum shows a partially structured band with maxima at 416 and 436 nm when irradiating at 370 nm, the wavelength of the maximum band found in the excitation spectrum. Full article

Textile production contributes significantly to water pollution, making dye removal crucial for protecting water resources from toxic textile waste. The use of nano-adsorbents for water purification has emerged as a promising approach to removing pollutants from wastewater. Nickel Ferrite (NiFe₂O₄), Iron Oxide (Fe₂O₃), and Nickel Oxide (NiO) nanoparticles (NPs) were prepared via an auto-combustion sol–gel technique using chitosan as a capping and stabilizing agent. The prepared nanomaterials were characterized using various techniques such as XRD, UV-Vis DRS, FT-IR, Raman, EDX, SEM, and TEM to confirm their structure, particle size, morphology, functional groups on the surface, and optical properties. Subsequently, the adsorption of the methylene blue (MB) dye using the prepared nanomaterials was studied. NiFe₂O₄ NPs exhibited the best adsorption behavior compared to the mono-metal oxides. Moreover, all prepared nanomaterials were compatible with the pseudo-second-order model. Further investigations were conducted for NiFe₂O₄ NPs, showing that both the Freundlich and Langmuir isotherm models can explain the adsorption of the MB dye on the surface of NiFe₂O₄ NPs. Factors affecting MB dye adsorption were discussed, such as adsorbent dose, concentration of the MB dye, contact time, pH, and temperature. NiFe₂O₄ NPs exhibited a maximum removal efficiency of the MB dye, reaching 96.8% at pH 8. Different water sources were used to evaluate the ability of NiFe₂O₄ NPs to purify a wide range of water types. Full article

Sodalite is a common feldspathoid in alkaline systems, with some varieties exhibiting notable fluorescence due to impurity activators. This study reports the first documented occurrence and characterization of fluorescent sodalite from the classic Ditrău Alkaline Massif, Romania, where its optical properties were previously undescribed. Sodalite-bearing syenite samples from different perimeters of the massif were investigated using macroscopic UV fluorescence, petrographic microscopy, and vibrational spectroscopy (Raman and FT-IR). The sodalite occurs as a late-stage, interstitial and poikilitic mineral, often associated with alteration to cancrinite. Under long-wave UV (365 nm) light, it exhibits spatially variable fluorescence, from absent in parts of the western Prişca perimeter to strong, uniform orange in the eastern Aurora perimeter. Raman and FT-IR spectroscopy confirmed the mineral’s identity and revealed subtle spectral variations, particularly the presence of a minor cancrinite component in some analyses. The vibrant orange fluorescence is consistent with activation by disulfide radical anion ($S_2^{·-}$) activators, formed in the sulfur- and chlorine-rich late-stage fluids characteristic of the massif’s evolution. The geographic variation in fluorescence intensity serves as a potential indicator of the geochemical heterogeneity of these fluids across the massif, linking the strongest fluorescence to the most evolved portions of the igneous complex. This finding opens a new avenue for using fluorescence as a tool for petrogenetic investigation in this classic locality. Full article

Isosymmetric phase transitions (IPTs) represent a rare class of solid-state transformations in which substantial structural reorganization occurs without a change in crystallographic symmetry. These phenomena, though subtle, can have a profound impact on the physical and functional properties of materials, offering novel opportunities for property tuning without chemical modification. This review provides a comprehensive overview of the experimental and computational methods used to detect and characterize IPTs, including single-crystal and powder X-ray diffraction, Raman and FT-IR spectroscopy, differential scanning calorimetry, and advanced simulation techniques such as density functional theory, molecular dynamics, and crystal structure prediction. Special emphasis is placed on correlating local structural rearrangements—such as hydrogen-bond reconfiguration, polyhedral tilting, and molecular fragment reorientation—with macroscopic thermodynamic signatures. A broad selection of examples from the literature is discussed, covering molecular crystals, coordination compounds, organic functional materials, simple salts, and inorganic oxides, with detailed tables summarizing pressure- and temperature-induced IPTs. The review also analyses the primary factors that trigger IPTs, particularly temperature and pressure, and examines their role in governing structural stability and transformation pathways. By combining structural, spectroscopic, and thermodynamic perspectives, this work aims to consolidate the understanding of IPT mechanisms and to highlight their significance for the design of responsive crystalline materials. Full article

The origin of glass formation has been one of the greatest mysteries of science. The first clues emerged in Ge_xSe_1-x glasses, where the bond-stretching and bond angle-bending constraints are countable, and it was found that the most favorable compositions for glass formation involved matching constraints with the degrees of freedom. Modulated-Differential Scanning Calorimetric (MDSC) studies on Ge_xSe_1-x chalcogenide glasses revealed two elastic phase transitions—a stiffness transition at x = 0.20 and a stress transition at x = 0.26—leading to the observation of three topological phases: a flexible phase at x < 0.20, an intermediate phase in the 0.20 < x < 0.26 range, and a stressed–rigid phase for compositions x > 0.26. The three topological phases (TPs) have now been generically observed in more than two dozen chalcogenides and modified oxide glasses. In proteins, the transition from the unfolded (flexible) to the folded (isostatically rigid intermediate) phase represents the stiffness transition. Self-organization causes proteins to display a dynamic reversibility of the folding process. The evolutions of protein dynamics may also exhibit stiffness phase transitions similar to those seen in glasses. Full article