Search Results (138)

Natural V-rich green beryl from the North Muzart River area, Xinjiang, was investigated using microscopy, EDXRF, UV–Vis–NIR, FTIR, and Raman spectroscopy. Ten specimens were examined microscopically; selected detached crystals were analyzed spectroscopically. Thirteen EDXRF analyses on seven detached crystals yielded V₂O₅- and Fe₂O₃-equivalent contents of 0.562–4.616 wt.% and 0.172–0.494 wt.%, respectively; Cr₂O₃ was not detected under the present analytical conditions, and normalized Fe₂O₃–V₂O₅–Cr₂O₃ compositions plot near the V₂O₅ endmember. Broad absorption bands near 429 and 617 nm fall within the spectral range commonly attributed to V³⁺ in beryl. Given the V-dominant EDXRF composition, these bands are interpreted as predominantly V-related; however, the V³⁺ assignment remains indirect because EDXRF does not determine the oxidation state, crystallographic site, or local coordination of V, and a minor contribution from Cr below the EDXRF detection capability cannot be excluded. Weaker responses near 366, 391, and 847 nm may involve Fe-related centers. Raman spectra from two selected green regions are consistent with the beryl host, and FTIR spectra of four selected crystals indicate predominantly type-II channel-water features with weaker type-I contributions. These samples provide a natural comparative system for evaluating V-related absorption in beryl and for comparison with V-doped synthetic beryl. Full article

Nano- and microplastics (NMPs) are now widely detected across agroecosystems and can act as physiological stressors in plants. Exposure occurs through contaminated soil, irrigation water, or airborne deposition, bringing particles into direct contact with roots and above-ground tissues. Reported entry routes include apoplastic transport, cracks formed at lateral root emergence, leaf stomata, and endocytosis once particles have crossed the cell wall. Once internalized, particles may translocate through the xylem and, in some cases, the phloem, accumulating in roots, stems, and leaves depending on particle size, surface charge, and plant structural characteristics. NMPs have been associated with oxidative stress, disrupted photosynthesis, and altered metabolic pathways. Detecting NMPs within heterogeneous, hydrated plant tissues remains challenging, as particles often show low contrast against biological structures and can be mistaken for cellular components. This review examines how microscopy techniques reveal NMPs size, surface attachment, tissue distribution, and cellular-level interactions, while noting that these approaches primarily provide morphological or localization information rather than confirming polymer identity. Complementary spectroscopic and mass-based analytical methods are discussed for their role in chemical confirmation and quantification. This review supports informed selection among imaging, spectroscopic, and quantitative techniques for studying plant–plastic interactions, while highlighting current analytical challenges facing the field. Full article

Whey–quercetin-loaded microspheres were synthesized using the solid/organic phase/water phase (S/O/W) method, whereas nanocapsules were prepared by interfacial polymerization. The resulting systems noted that Q1, Q2, and Q3 were characterized by polarized light microscopy (PLM), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), high-performance liquid chromatography (HPLC), and antioxidant activity assays. Structural and spectroscopic analyses confirmed the successful encapsulation of whey and quercetin within both microsphere and nanocapsule systems. Q2 exhibited the highest encapsulation efficiency (51.79 ± 1.03%) and loading capacity (5.78 ± 0.71%), demonstrating its superior quercetin encapsulation performance. However, measurable antioxidant activity was detected exclusively in the nanocapsule formulations, whereas microspheres showed no detectable activity under the experimental conditions. Although the antioxidant activity of encapsulated quercetin was lower than that of free quercetin, the nanocapsules retained a radical-scavenging capacity, supporting their potential as effective delivery systems. Full article

Background/Objectives: Chronic insomnia commonly induces progressive memory decline, severely compromising human daily life and work capability. At present, there are no safe long-term available agents that can concurrently relieve insomnia symptoms and rescue accompanying memory dysfunction. This study aimed to optimize the preparation of deer brain peptides (DBPP) and zinc-chelated DBPP (Zn-DBPP), and explore their protective effects and molecular mechanism against insomnia-caused memory impairment, hoping to develop novel functional candidates for related neurological disorders. Methods: Single-factor experiments combined with response surface methodology were used to optimize the synthesis process of DBPP and Zn-DBPP. A para-chlorophenylalanine-induced insomnia mouse model was established. The structural characteristics, amino acid composition, and antioxidant activity of the products were verified via multiple spectroscopic and biochemical assays. Pentobarbital sodium sleep test and Morris water maze test assessed behavioral changes. Hippocampal neuronal morphology and BDNF-TrkB pathway expression were detected by histological staining, immunofluorescence and Western blotting. Results: The optimized DBPP achieved a hydrolysis rate of 43.89%, and Zn-DBPP possessed a zinc content of 143.37 mg/g. Successful zinc chelation, rich amino acid components, and strong antioxidant capacity were confirmed in Zn-DBPP. In vivo results showed that Zn-DBPP elevated brain zinc levels, improved learning and memory deficits, and restored hippocampal neuronal damage in insomniac mice. Mechanically, Zn-DBPP alleviated memory impairment by upregulating the BDNF-TrkB signaling pathway. Conclusions: The optimized Zn-DBPP exhibits excellent neuroprotective effects against insomnia-induced memory dysfunction. This work provides a reliable theoretical basis for the application of Zn-DBPP as a promising functional food or drug candidate for intervening in insomnia and cognitive decline. Full article

A simple and cost-effective graphite paste electrode modified with 5-(4-aminophenyl)-4-amino-1,2,4-triazole-3(2H)-thione was developed for the selective voltammetric determination of Cu(II) ions in environmental water samples. The N,S-donor ligand was incorporated into a graphite–polystyrene matrix without the use of nanomaterials, providing a reproducible and straightforward electrode fabrication route. Scanning electron microscopy revealed a rough, porous surface morphology with an enhanced electroactive surface area of 0.065 cm², approximately twice the geometric area. Electrochemical impedance spectroscopy confirmed diffusion-controlled mass transport, while cyclic voltammetry indicated quasi-reversible behaviour of the Cu(II)/Cu(0) redox system with a linear dependence of peak current on the square root of the scan rate. Differential pulse voltammetry under optimised conditions (0.1 mol·L⁻¹ H₂SO₄, pH 1.0–1.2) yielded a linear analytical response over the concentration range of 0.01–0.4 μmol·L⁻¹ (R² = 0.99507), with a limit of detection of 0.02 μmol·L⁻¹ and a limit of quantification of 0.06 μmol·L⁻¹—well below the WHO guideline for copper in drinking water. The sensing mechanism involves selective N,S-bidentate coordination of Cu(II) at the electrode surface, followed by electrochemical reduction, as supported by FT-IR spectroscopic evidence. The sensor demonstrated good selectivity toward Cu(II) in the presence of common interfering metal ions at up to 20-fold excess. The method was successfully validated against ICP-OES (recovery 99.8%, RSD < 0.33%) and confirmed by spike–recovery experiments (99.0–99.5%), confirming its practical applicability for trace-level environmental monitoring. The modified electrode retained approximately 93% of its initial response after 30 consecutive measurements and 91% after 14 days of storage, demonstrating good operational stability. Full article

We studied the Stokes signals generated following the Raman photoexcitation of dissolved oxygen in water. When a water sample is pumped with intense nanosecond radiation, Stokes signals of different origins are generated. These signals form a characteristic nonlinear diffraction pattern, comprising a central spot and concentric rings whose radii depend on the Stokes wavelengths. Although most of the Stokes signals correspond to the stretching vibrations of water molecules, we also observed a small contribution from dissolved oxygen molecules. This contribution can be separated from the others using appropriate spectroscopic filters, then analyzed with a spectrometer. In this study, we report on Stokes components assigned to singlet oxygen excitation detected in the central spot, as well as in the diffraction pattern’s ring structure. The signal detected in the central spot exhibits a single peak, while that from the ring shows a two-peak structure. These two observed peaks are interpreted as Stokes signals corresponding to Raman transitions to the two lowest vibrational sublevels of the singlet-oxygen electronic state. We also report exponential growth in the Stokes signal with the pulse energy, in agreement with the standard stimulated Raman theoretical model. Full article

The pervasive contamination of aquatic environments by microplastic particles necessitates the development of rapid, cost-effective and field-deployable detection methodologies to complement established but laboratory-bound spectroscopic techniques such as Fourier-transform infrared and Raman microscopy. The demand for field-suitable methods with a broad accessibility comes from researchers themselves. In this review we systematically examine recent advances in optical methods for microplastics identification with a particular emphasis on birefringence as a key diagnostic feature of partially crystalline synthetic polymers. In particular, we analyze three complementary technological directions: liquid crystal-based sensors that exploit orientational order disruptions at interfaces for label-free microplastics detection; polarization holographic imaging combined with machine learning for high-throughput particle classification; and on-chip polarization light microscopy enabling compact and portable analyzing systems. Liquid crystal platforms demonstrate exceptional sensitivity to submicron particles and enable real-time visualization of microplastics aggregation at aqueous interfaces, though they currently lack polymer-specific chemical identification. Conversely, smart polarization holography integrated with Stokes polarimetry and deep learning algorithms achieves over 90% accuracy in distinguishing microplastics from natural particles while processing up to 10,000 particles per minute. Emerging on-chip polarized light microscopy offers a pathway toward miniaturized, low-cost devices suitable for field applications. By synthesizing insights from foundational studies, this review identifies convergent interdisciplinary trends—particularly the integration of artificial intelligence with multimodal optical imaging—and outlines persistent challenges including standardization, interference from natural organic matter, and the transition from laboratory prototypes to robust field-deployable instruments. The systematization of birefringence-based approaches aims to guide future research towards integrated monitoring systems capable of addressing water quality concerns. Full article

Hydrogen sulfide (H₂S) is a toxic and biologically relevant gas, necessitating sensitive and interference-resistant detection methods for environmental monitoring. Here, we develop a donor–acceptor molecular platform incorporating a polarized conjugated double bond bridge and demonstrate its application, using YG2 as the representative probe, as a dual-peak ratiometric UV–Vis sensor for H₂S. UV–Vis spectroscopy, supported by ¹H NMR analysis, indicates HS^--induced interaction with the conjugated linkage, leading to disruption of π-conjugation, suppression the intramolecular charge-transfer (ICT) band at 409 nm, and enhancing the locally excited (LE) band at 279 nm. The ratiometric parameter log(Abs₂₇₉/Abs₄₀₉) affords a linear response over the concentration range of 1.0 × 10⁻⁶–1.0 × 10⁻⁴ M with a detection limit of 8.3 × 10⁻⁷ M, providing approximately an order-of-magnitude improvement in analytical sensitivity compared with single-wavelength methods, and the reaction reaches completion within ~10 s. YG2 exhibits excellent selectivity toward H₂S over common anions and enables accurate quantification in real water samples, with recoveries of 95.43–105.86% and relative standard deviations (RSDs) of 0.56–9.58%. These results suggest that YG2 is a rapid, self-calibrating, and spectroscopically interpretable ratiometric probe suitable for reliable H₂S detection in complex aqueous environments. Full article

A TiO₂/hydrazine system was investigated as a proof-of-concept platform for coupling chemical CO₂ capture with light-driven H₂ evolution under UV irradiation. Hydrazine served as the CO₂ capture agent, leading to the formation of carbamate-type intermediates, while TiO₂ acted as the photoresponsive solid. FT-IR, UV-Vis, and mass spectrometry analyses supported carbamate formation after CO₂ uptake and confirmed H₂ generation during irradiation, reaching a maximum of 33.2 μmol under the conditions evaluated. Deuterated experiments showed no detectable HD or D₂, indicating that H₂ evolution predominantly proceeded via hydrazine dehydrogenation rather than direct water splitting. On the basis of the available spectroscopic evidence, a tentative pathway involving carbamate intermediates and nitrogen-containing oxidation products is proposed. However, key control experiments required to confirm a strictly photocatalytic origin of H₂ evolution were not performed in the present exploratory study. Therefore, the observed behavior is more appropriately interpreted as preliminary photoinduced reactivity in a TiO₂/hydrazine/CO₂ system rather than definitive proof of a fully established photocatalytic mechanism. Overall, the results establish a preliminary proof of concept, while the limitations related to control experiments, product identification, quantification, and reproducibility are recognized. Full article

Removing altered varnishes and retouching from oil paintings is a delicate and irreversible procedure in the conservation of cultural heritage. Surfactant-free gelled o/w emulsions containing dibasic esters (DBE) provide a green, safe, and environmentally friendly alternative to traditional solvent methods. The use of Xanthan gum and polyacrylate as thickening agents successfully restricted solvent diffusion, thereby minimizing the risk of interaction with water-sensitive substrates. Spectroscopic and microscopic analyses (FTIR and SEM) were employed to evaluate the cleaning efficacy and to assess the morphological integrity of the paint surface post-treatment, detecting potential inhomogeneities, erosion, or pigment loss. Determination of surface conductivity has allowed us to verify the degree of removal of any residues that could have undesirable long-term effects. Fatty acid leaching was quantified by gas chromatography-mass spectrometry (GC/MS): the use of free DBE resulted in a loss of up to 60% of the lipid component, while for surfactant-free gelled o/w emulsions with DBE, this figure was significantly reduced, with no observable surface damage. The tests were performed at both neutral pH and pH 8.5. The pH change was consistent with expected values: alkaline and ionizing conditions enhanced the emulsifying and removal effect, as well as the interaction with the painting medium. These results suggest that surfactant-free gelled o/w emulsions represent a promising alternative to conventional solvent-based systems, offering effective varnish removal while minimizing risks to both artifacts and restorers. Full article

Nitrates and nitrites are inorganic anions which, beyond specific concentration threshold, are classified as water pollutants. Nitrate compounds are commonly used as fertilizers; however, their high concentration in soil and in wastewater, as well as their reduction to nitrites, pose serious environmental and human health risks. Therefore, detecting these ions in water intended for human consumption, zootechnical use, and agricultural applications is essential. This work presents a proof of concept for a spectroscopic prototype setup enabling simple, direct, and simultaneous detection of nitrates and nitrites in water. The device employs solid-state sensor technology and requires no sample pretreatment or chemicals. Ultimately, this apparatus will allow real-time, in-line process analysis. UV absorption bands centered at approximately 302 nm and 355 nm were selected for detecting nitrates and nitrites, respectively. Because nitrite exhibits a slight absorption at 302 nm as well, a straightforward method for simultaneous nitrate and nitrite detection is proposed. The proposed system incorporates a UV deuterium lamp, a 10 cm path length optical cuvette, and a custom home-built silicon carbide detector. This configuration enables testing various concentrations, achieving detection limits of 2.2 mg/L for nitrates and 0.5 mg/L for nitrites. Potential interferences from substances commonly found in drinking and treated agricultural wastewaters, including sodium bicarbonate, sodium sulfate, ammonium chloride, hydrogen peroxide, and sodium hypochlorite, were also investigated. Finally, a compact on-site and online monitoring future device is illustrated. Full article

Chemical oxygen demand (COD) serves as a critical indicator for assessing the extent of water pollution caused by organic matter. This study proposes an integrated COD detection methodology that combines laser absorption spectroscopy with laser-induced fluorescence spectroscopy, enabling accurate measurement of COD parameters across a wide concentration range. For high-concentration COD, conventional ultraviolet absorption spectrophotometry based on the Lambert–Beer law is employed. However, since laser absorption spectrophotometry exhibits substantial errors in detecting low-concentration COD, laser-induced fluorescence spectroscopy is adopted for the precise quantification of trace-level COD. By integrating these two laser-based approaches, a spectroscopic COD detection system has been developed that simultaneously records absorbance after the laser passes through the sample and quantifies fluorescence intensity perpendicular to the beam with an image sensor, thereby achieving comprehensive COD analysis. Laboratory validation using COD standard solutions demonstrated relative errors below 11% across the concentration range of 2–220 mg/L. Further application to natural water samples confirmed that the integrated laser absorption–fluorescence spectroscopy approach achieves wide-range COD measurement with high sensitivity, a compact configuration, and rapid response, demonstrating strong potential for real-time online water quality monitoring. Full article

Glyphosate (GLY) is a systemic herbicide used in agriculture and has a carcinogenic effect after long-term usage. Herein, a molecularly imprinted electrochemical sensor based on palladium@yttrium oxide@boron nitride nanosheets (Pd/Y₂O₃@BN) nanocomposite was developed for the detection of GLY in drinking water. After the preparation of Pd/Y₂O₃@BN nanocomposite by using sonication and NaBH₄ reduction methods, Pd/Y₂O₃@BN nanocomposite as electrode material was applied on glassy carbon electrode by infrared lamp. Then, a molecularly imprinted glassy carbon electrode based on Pd/Y₂O₃@BN (MIP) was designed with cyclic voltammetry (CV) in presence of pyrrole monomer and GLY molecule. After the spectroscopic and microscopic characterizations, the linearity in the range of 1.0 × 10⁻⁹–1.0 × 10⁻⁸ M with a detection limit (LOD) of 3.3 × 10⁻¹⁰ M was obtained for GLY molecule. After MIP electrode was applied to drinking water samples with high recovery, the selectivity, stability, repeatability, and reproducibility features were studied. These promising results suggested that the as-fabricated MIP electrode presented a novel and highly effective approach for GLY assay. Full article

Spectroscopic technology offers the advantage of rapid online monitoring and has attracted significant attention in molecular detection. However, the complex optical spectroscopic structure results in a relatively complex structure for spectral detection systems, limiting their widespread application. In water spectral detection, in addition to ensuring the stability of the optical system, waterproofing is also crucial. Therefore, developing miniaturized spectral detection modules in water spectral detection can improve system stability and reduce the complexity of developing and maintaining underwater hardware. This work develops a compact multispectral detection system centered on a miniature multispectral sensor. The system, controlled by a microcontroller, detects eight spectral channels within the 400–700 nm range and transmits data via the I²C bus. The sensitivity and stability of the detection are sufficient for water reflectance spectral detection. Based on the reflectance spectrum obtained by the above module, this work develops a regression algorithm to estimate the chlorophyll concentration in water. By comparing with standard chlorophyll concentration detection instruments, the results demonstrate the effectiveness of the proposed system in accurately estimating chlorophyll concentration. 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