Search Results (900)

Raw Chinese lacquer, tapped from the sap of Toxicodendron vernicifluum, is a natural water-in-oil microemulsion containing urushiol, polysaccharides, proteins, and laccase. Because this reactive system continues to oxidize and polymerize after harvesting, handling conditions directly determine water content, viscosity, and later film-forming performance. This review analyzes potential in situ stabilization routes that couple purification, low-temperature vacuum dehydration, and quality conditioning at, or near, the collection site. Emphasis is placed on how laccase retention, oxygen exposure, and urushiol polymerization are controlled together to limit transport losses and premature crusting. Portable filtration devices, reported centrifugal filtration systems, and proposed vacuum dehydration strategies are compared in terms of throughput, field compatibility, and process control. Physical and bio-based conditioning strategies, including shear adjustment, oxygen management, and natural film-forming aids, are further considered for on-site regulation. Surface-enhanced Raman spectroscopy (SERS) and portable spectroscopic devices are examined as feedback tools for parameter adjustment under field temperatures, humidity, and storage variation; however, these signals are treated as decision-support indicators that still require lacquer-specific calibration after tapping. The central task is to define a field-compatible process window for water removal, laccase retention, viscosity control, drying behavior, and storage stability before downstream coating preparation. The remaining challenges involve miniaturized equipment, standardized evaluation, evidence-level classification, and dynamic control of coupled variables. Full article

Microplastics are a pervasive contaminant of aquatic, terrestrial, and atmospheric systems, with accumulating evidence of ecological harm and human exposure. Conventional workflows, manual microscopy, FTIR, and Raman spectroscopy, are labor-intensive and operator-dependent, motivating artificial intelligence (AI) and machine learning (ML) as scalable alternatives. Following PRISMA guidelines, five databases were searched; 936 records were screened and 113 primary studies met the eligibility criteria, analyzed through dual-reviewer extraction across seven dimensions. Contrary to the assumption that deep learning dominates, classical and chemometric estimators (46.0% of studies) were at least as prevalent as deep learning (36.3%), with support-vector machines the single most used family (35.4%). Method choice tracked input modality rather than recency: chemometric classifiers such as SVM and PLS dominate spectroscopic data (FTIR, Raman; 53.1% of studies), whereas deep learning concentrates in the image-based minority, where representation learning outperforms manual feature engineering. Detection/identification remained the principal task (65.5%), although 19.5% addressed predictive modeling of sorption, toxicity, distribution, and remediation. Characterization coverage was uneven: origin and polymer type were reported in 88.5% and 72.6% of studies, but size and shape in only 50.4% and 28.3%. Reported accuracies, often exceeding 90%, derive from heterogeneous, non-comparable datasets. Future progress depends on open benchmarks, standardized reporting, and explainable methods. Full article

The conformational composition and ultraviolet photochemistry of neutral valine isolated in solid parahydrogen were investigated using high-resolution infrared spectroscopy, ultraviolet photolysis, and density functional theory calculations. The observed infrared spectrum was analyzed by combining calculated vibrational frequencies, relative infrared intensities, and conformer-specific photolysis kinetics. Four distinct photolysis-rate categories were identified experimentally, providing direct evidence for the presence of at least four valine conformers in the parahydrogen matrix. The combined spectroscopic and kinetic analysis enabled assignment of the major absorption bands to the six lowest-energy conformers and revealed pronounced conformer-dependent photostability of valine. Upon irradiation at 213 nm, valine undergoes predominantly $\alpha$-carbonyl C–C bond cleavage, producing the hydrocarboxyl (HOCO) radical and 2-methylpropan-1-imine as the major photoproducts. The formation of HOCO is consistent with previous studies of amino acids isolated in solid parahydrogen and supports a common photodissociation pathway among aliphatic amino acids. The hydrogen-bonded Type II conformer exhibits significantly slower photodepletion than the Type I conformers, indicating that intramolecular hydrogen bonding enhances ultraviolet photostability of valine. These results establish a direct relationship between molecular conformation and photochemical stability in isolated amino acids while further demonstrating the unique capability of solid parahydrogen matrix isolation for conformer-specific photochemical investigations. Full article

Background/Objectives: Sphagneticola trilobata is a phytochemically rich medicinal plant, yet its antioxidant-active fractions and redox-related mechanisms remain incompletely characterized. This study combined metabolite profiling, antioxidant screening, network pharmacology, pharmacokineticprediction, and molecular docking to characterize active flower and leaf fractions and prioritize antioxidant-related targets. Methods: Petroleum ether, methylene chloride, and ethyl acetate fractions of S. trilobata flowers and leaves were analyzed by ultra-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC–ESI–MS/MS). The predominant metabolite was isolated and spectroscopically characterized. Antioxidant activity was assessed using 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and ferric reducing antioxidant power (FRAP). Metabolites from the most active fractions were investigated by target prediction, protein–protein interaction (PPI) analysis, enrichment analysis, SwissADME, and docking. Results: UPLC–ESI–MS/MS tentatively identified 59, 18, and 16 metabolites in the petroleum ether, methylene chloride, and ethyl acetate fractions, respectively, including diterpenes, phenolic acids, flavonoids, fatty acids, triterpenes, and coumarin-related metabolites. Butein was isolated as the predominant metabolite from the ethyl acetate flower fraction, which showed the strongest antioxidant activity, with IC₅₀ values of 5.85 ± 0.14 µg/mL in ABTS and 9.11 ± 0.75 µg/mL in FRAP, followed by the ethyl acetate leaf fraction. Network analysis identified 61 and 82 antioxidant-relevant targets for the flower and leaf ethyl acetate fractions, respectively, with enrichment in inflammation-, apoptosis-, transcription-, hypoxia-, lipid stress-, and kinase-related pathways. Docking suggested fraction-specific compatibility with EGFR/PTGS2/STAT3 for flower metabolites and AKT1/PTGS2 for leaf metabolites. Conclusions: S. trilobata ethyl acetate fractions, particularly the flower fraction, represent promising antioxidant sources with experimentally supported activity and computationally prioritized redox-related hypotheses requiring further validation. Full article

Rutile is an oxide mineral widely distributed in igneous, metamorphic, and sedimentary rocks; it crystallizes in the tetragonal system. Trace-element abundances in rutile are influenced by the host-rock composition, redox conditions and crystallization history. Rutile exhibits high refractive index, strong dispersion, and adamantine luster. Its enrichment in high field strength elements (HFSEs) can be used to trace its formation environment. Owing to its inclusion-poor, compositionally uniform characteristics, rutile is particularly well-suited to in situ U-Pb geochronology. By integrating spectroscopic analysis, trace-element geochemistry, and U-Pb geochronology, this study systematically characterizes nine rutile samples from Madagascar, Pakistan, and Brazil, establishing a multi-dimensional scheme for origin discrimination. Spectroscopic analyses reveal that the infrared reflection band near 670 cm⁻¹ varies systematically with provenance. It appears as a broad, strong band in Madagascar samples, becomes weaker and narrower in Brazilian samples, and is partially absent in Pakistani samples. The Eg Raman mode of Brazilian rutile is slightly left-shifted and exhibits lower intensity, indicating a distinct lattice strain state. Analyzed samples occupy well-separated compositional fields on Nb–V, V–Ta, Zr–Hf and Nb–Ta binary variation plots. Specifically, Pakistani samples are characterized by high Nb and Ta contents and relatively lower V contents than the Brazilian and Madagascar samples. Madagascar samples show pronounced W enrichment and very low Cr. Brazilian samples display elevated Cr, V, higher U contents and more radiogenic Pb isotope compositions. Zr–W systematics and Cr–Nb bivariate discrimination allow inference of geological genesis. The Madagascar rutile is of hydrothermal origin, whereas the Pakistani and Brazilian rutile are metamorphic, derived from felsic/pelitic and mafic protoliths, respectively. LA-ICP-MS U-Pb geochronology yields a lower-intercept age of 504 ± 13 Ma (MSWD = 1.1) for the Madagascar sample (MD-1). This concordant, low-common-Pb age corresponds to the Pan-African orogeny and suggests strong potential as an in-situ U-Pb dating reference material. The Brazilian and Pakistani samples yield lower-intercept ages of 486 ± 53 Ma and 36.8 ± 2.9 Ma, respectively. However, the larger data scatter precludes their use as reference materials. Full article

The development of more accessible perfumes (non-counterfeit replicas) that offer a similar scent to luxury perfume brands is an emerging trend in the perfume market. In this context, it is important to develop simple, rapid, cost-effective, and environmentally friendly alternative analytical tools capable of differentiating original perfumes from their non-counterfeit replicas. In this work, three vibrational spectroscopic techniques, namely near-infrared (NIR), mid-infrared (MIR), and Raman spectroscopy, were evaluated for the discrimination between original perfume samples and their non-counterfeit replicas. Several original perfume samples and their non-counterfeit replicas were scanned through these vibrational spectroscopic techniques and analyzed with two chemometric tools: principal component analysis (PCA) and hierarchical cluster analysis (HCA). Different pre-processing techniques were also tested in PCA and HCA to attest to the robustness of the findings. The results revealed that all vibrational spectroscopic techniques tested demonstrated high efficiency in differentiating original perfumes from their non-counterfeit replicas. NIR spectroscopy revealed the least similarity among the samples across all pre-processing techniques. In this context, these vibrational spectroscopic techniques are a rapid, cost-effective, non-destructive, and interesting alternative for discriminating between original perfume samples and non-counterfeit replicas. Although further studies, including the application of supervised classification methods to a larger sample set, are needed to attest to the robustness of these results, these preliminary results are very interesting and promising. To the best of our knowledge, this was the first time that vibrational spectroscopic techniques were applied and compared in the analysis of perfume and non-counterfeit replicas. Full article

The present study investigates the physicochemical degradation and wear metal evolution of low-viscosity SAE 0W-20 engine oil during the first service interval of a modern gasoline internal combustion engine. Two oil samples were analyzed: fresh lubricant and used oil collected after approximately 13,000 km of vehicle operation. The analysis included determination of kinematic viscosity at 100 °C (ASTM D445), total base number (ASTM D2896), FT-IR spectroscopic indicators of chemical degradation (ASTM E2412), and elemental analysis of wear and additive metals using ICP-OES (ASTM D5185). The results show a viscosity reduction from 8.5 to 7.01 mm²/s and a decrease in the alkalinity reserve to 3.7 mgKOH/g, indicating progressive lubricant aging. FT-IR analysis revealed moderate oxidation, nitration, and sulfation processes, while elemental analysis identified Cu, Fe, and Al as the dominant wear metals. The observed changes correspond primarily to normal oil aging and engine running-in processes. The results demonstrate the effectiveness of combined oil analysis techniques for monitoring lubricant degradation and early engine wear. 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

Non-covalent forces are the primary drivers of biomolecular interactions. They also represent a key factor in the unexpected tendency for proteins, peptides, and even individual amino acids to self-assemble into precise supramolecular assemblies, often characterized by a β-rich, amyloid-like structure. Studies carried out in the last few decades have shown that peptides/proteins self-assembly not only has structural consequences but also generates spectroscopic properties whose origin remains debated. Here, we investigated the spectroscopic properties of four peptides, GAIIGL, NNQQ, SSTSAA, and GNNQQNG (a derivative of the frequently studied GNNQQNY peptide), devoid of aromatic residues, whose crystallographic characterization has been seminal in elucidating the basis of the aggregation process. The spectroscopic behavior of these peptides was analyzed in two different media and in the solid state, highlighting the conditions that favor UV–visible fluorescence emission. These investigations have also prompted the use of this fluorescence as a potential diagnostic tool in nanomedicine. Importantly, the identification of intrinsic fluorescence signatures in these amyloid-like assemblies may support the development of label-free optical approaches for the early detection and monitoring of aggregation-related pathological processes. For all peptides, the emitted fluorescence spans a rather wide range of wavelengths. Although centered in the blue region, a significant signal is also observed in the green region, independent of their physical state. The structural analysis of the solid used to collect the spectroscopic data reveals features related to the packings in the crystal state. This observation suggests that their three-dimensional crystal structures may serve as reliable models for studies aimed at correlating structural and spectroscopic features. Full article

Objectives: Thiocarbohydrazones represent an important class of Schiff base derivatives with versatile chemical and biological properties. Methods: Herein, we present a combined in silico spectroscopic and molecular docking investigation of N′-benzylidenehydrazinecarbothiohydrazide (1). Results: Conformational docking studies were conducted against cathepsin B, acetylcholinesterase, HER2, protein kinase C, and protein kinase A. The compound displayed favorable binding affinities and key interactions within the catalytic sites of all targets, with the strongest predicted binding observed for acetylcholinesterase. Notably, all conformers exhibited higher affinity for protein kinase C than the reference inhibitor balanol, and hydroxylation led to an approximately 10% enhancement in docking performance. Density functional theory (DFT) calculations were employed to analyze vibrational properties, and IR and Raman spectra were computed to elucidate structural features and conformational behavior. Conclusions: The integrated spectroscopic and docking analyses provide mechanistic insights into ligand–target interactions and support rational drug design. These findings identify thiocarbohydrazone derivatives as promising multi-target candidates for the development of enzyme inhibitors relevant to neurodegenerative, oncological, and inflammatory diseases. Full article

Serum albumin binding plays a critical role in determining the pharmacokinetic and pharmacodynamic behavior of many drugs. Despite extensive studies on human and bovine serum albumin, quantitative binding data for rabbit serum albumin remain limited for several therapeutically important compounds. In this study, the binding interactions of three oxicam-class non-steroidal anti-inflammatory drugs (meloxicam, tenoxicam, and piroxicam) with rabbit serum albumin were investigated using circular dichroism spectroscopy and fluorescence quenching measurements. Binding parameters were estimated using nonlinear mixed-effects models that simultaneously incorporated data from multiple spectral channels and experimental replicates while accounting for residual correlation and heteroscedastic variance. Fluorescence-based analyses produced estimates consistent with the combined models and showed substantially lower uncertainty compared with CD-only analyses. These findings demonstrate that fluorescence quenching provides more reliable quantitative estimates of albumin binding affinity, whereas CD measurements exhibit higher variability in this context. The results represent the first systematic report of oxicams binding to rabbit serum albumin, with stability constants of meloxicam (logK = 4.840 ± 0.009), piroxicam (logK = 5.068 ± 0.007 and tenoxicam (logK = 4.668 ± 0.004) and highlight the importance of experimental determination of binding parameters even within closely related drug classes. The modeling framework employed here provides a robust statistical approach for analyzing spectroscopic titration data and may be broadly applicable to studies of drug–protein interactions. Full article

Globally, large quantities of discarded shells, including scallops and surf clams, are often accumulated at disposal sites, causing environmental degradation. Calcium carbonate (CaCO₃) in seashells predominantly exists in polymorphic forms, such as aragonite and calcite, and undergoes phase transformation upon thermal treatment. This study investigates the thermal evolution of scallops and surf clam shells at various calcination temperatures to characterize changes in crystalline structure, pore morphology, and to review their potential as partial cement replacement materials. The seashells were mechanically ground into fine powder and subsequently calcined at 650 °C, 750 °C, and 850 °C for 7 h. The CaCO₃ transformation was comprehensively characterized using solid-state ¹³C NMR, XRD, TG-DTA, and SEM to resolve carbonate speciation, phase transitions, decomposition thermodynamics, and microstructural evolution. The solid-state ¹³C NMR was employed to analyze the local chemical environments of carbonate species and to provide additional spectroscopic evidence supporting the phase identification obtained from XRD and TG-DTA. Furthermore, XRD, TG-DTA, and SEM analyses consistently confirmed the phase transformations and associated changes in pore structure and crystallinity induced by calcination. These findings suggest that solid-state ¹³C NMR can be a useful technique for tracking CaCO₃ decomposition, while calcination may enhance the potential of seashell biowaste as a sustainable cementitious material. Full article

Trace water is one of the most critical matrix contaminants in ultra-high-purity (UHP) process gases, like argon (Ar), nitrogen (N₂), and many others. Even trace amounts can severely degrade the quality of many products that are reliant on these gases. Despite its importance to advanced technology sectors, notably semiconductor manufacturing, it has proven quite difficult to realize preparative or analytical trace water metrology over the full amount fraction range needed or in the broad spectrum of industrially relevant matrix gases. Within the EU-funded PROMETH2O project consortium, this challenge has been addressed through the development or significant improvement of traceable measurement methods and standards spanning 5 nmol⋅mol⁻¹ to 5 µmol⋅mol⁻¹, tailored for use in UHP process gas production, such as Ar, N₂ and clean dry air (CDA). The measurement ranges were extended and the uncertainties were improved while being consistent with the current best practice at primary humidity standard laboratories. The developed standards provide combined standard uncertainties ranging from approximately 0.4 % to 1.5 % in water vapor amount fraction and from 0.03 °C to 0.07 °C in frost-point temperature, while the comb-assisted CRDS system achieves detection limits in the sub-ppb to ppt range. These capabilities were validated in applications that are relevant to process instrumentation and the gas industry. A distributed metrological infrastructure at various European national metrology institutes and partner sites now provides SI-traceable trace water measurements in UHP gases, strongly supporting and extending the calibration capabilities for the gas and semiconductor industries and the associated stakeholders. Full article

Andean crops can be efficiently incorporated into food industrialization after the characterization of their components. This study evaluated tarwi (Lupinus mutabilis Sweet) flours from three ecotypes: PNTF (punto negro), WTF (white), and MTF (moro), with a particle size of 125 µm, analyzing their color, proximate composition, amino acid profile, bioactive compounds, and spectroscopic, thermal, and microstructural properties. Significant differences among ecotypes were determined at p < 0.05. The white ecotype showed greater accumulation in Dx (50), while black point exhibited the highest Dx (90), indicating a higher proportion of large particles. Regarding color, WTF presented the highest lightness and whiteness index, PNTF intermediate values, and MTF the darkest coloration, with greenish tones in black point and reddish tones in moro. The MTF ecotype showed the highest protein content (56.28%) and higher levels of essential amino acids, with methionine being the limiting amino acid. It also contained phenolic compounds ranging from 29.97 to 35.49 mg GAE/100 g, flavonoids from 9.36 to 10.8 mg quercetin/100 g, and antioxidant capacity measured by DPPH ranging from 25.79 to 55.30 mg TE/100 g, particularly notable in MTF. PNTF stood out for its dietary fiber (5.93%) and carbohydrate (17.22%) content. Infrared spectroscopy analysis revealed a similar macromolecular fingerprint among the samples. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) indicated greater thermal stability in MTF. Scanning Electron Microscopy (SEM) revealed greater compaction of irregular particles in MTF and greater dispersion in PNTF. These results support the differentiated valorization of tarwi ecotypes as complementary raw materials for the development of high-value-added foods in the current food industry. Full article

Puerariae Lobatae Radix (PLR) is a commonly used herbal medicine in traditional Chinese medicine, whereas Puerariae Lobatae Caulis (PLC), its aerial part, is frequently utilized as an adulterant due to similar morphological features. Conventional identification methods and pharmacopoeial criteria fail to effectively distinguish these two homologous herbs, creating a demand for a precise identification method. Therefore, a Digital ID method was established for their identification. UPLC-QE-Orbitrap-MS coupled with Progenesis QI software was applied to analyze multi-batch samples of PLR and PLC. Common ion information was extracted, and a differential ion matrix was constructed after eliminating blank ions and cross-shared components. High-intensity characteristic ions were defined as exclusive Digital ID for authenticity identification. The Matching Confidence (MC) values of both herbs matching their own Digital IDs were >85%, while cross-matching MC values were <4%. Unlike subjective macroscopic authentication, compendial TLC and single-marker quantification that fail to discriminate the two materials, and spectroscopic methods incompatible with powdered samples, this digital ID framework enables automated objective authentication via quantitative Matching Confidence without manual spectral comparison. This technique achieves accurate and efficient digital identification of the two herbs, facilitating the quality control of PLR and offering a new strategy for the quality assessment of traditional Chinese medicine (TCM). Full article