Search Results (825)

This study investigated the influence of acrylonitrile-butadiene rubber (NBR) at 5 and 15 phr on the properties of silica-filled styrene-butadiene /polyisoprene (SBR/NR) rubber blends intended for boot tread production. Fourier Transform Infrared Spectroscopy evaluated the performance of the resulting SBR/NR/NBR composites with Attenuated Total Reflectance (FTIR-ATR), which confirmed interactions between the rubber matrix and the silica filler. In addition, changes in thermal and mechanical properties, as well as cross-linking parameters, were systematically examined. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are used to provide a comprehensive understanding of the structural, thermal, and mechanical behavior of silica-reinforced SBR/NR/NBR composites. The rheological characteristics of the tested composites were examined as a function of the mixture ratio. Atomic force microscopy (AFM) revealed variations in the sample’s surface roughness and morphology with varying rubber blend ratios. The findings confirmed that incorporating NBR improves filler dispersion, increases cross-link density, and enhances mechanical properties, including hardness and tensile strength, while also influencing thermal stability and curing behavior. The results suggest the potential of these composites for reliable, efficient sole manufacturing in the footwear industry, where durability, strength, and processability are critical requirements. Full article

Nitrate pollution in groundwater poses severe threats to ecosystems and human health, making the electrochemical nitrate reduction reaction (NO₃RR) a promising remediation technology. Conductive metal–organic frameworks (cMOFs) with π-d conjugation, dispersed active sites, and tunable structures are ideal candidates for electrocatalysis. Herein, we synthesized a series of cMOFs (M₃(HHTP)₂, M = Fe, Zn, Cu, Co, Ni) via conjugated coordination between hexahydroxytriphenylene (HHTP) ligands and metal ions and systematically investigated their NO₃RR performance. Electrochemical tests revealed that Fe₃(HHTP)₂ exhibits superior catalytic performance for nitrate reduction, achieving a high NH₃ selectivity of 99.5% and a yield rate of 676.4 mg·g_cat⁻¹·h⁻¹ at −1.0 V vs. RHE (reversible hydrogen electrode), along with excellent cyclic and structural stability. In situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy identified key intermediates (*NO₂, *NH₂OH) and proposed the reaction pathway: NO₃⁻ → *NO₃ → *NO₂ → *NO → *NOH → *NH₂OH → *NH₂ → *NH₃. DFT calculations revealed that Fe center exhibited a lower energy barrier for NO₃RR compared to other metal ions (Zn, Cu, Co, Ni). This study demonstrates the significant potential of Fe₃(HHTP)₂ for efficient NO₃RR and provides new insights into the structure-function relationship of cMOF-based electrocatalysts. Full article

The increasing use of electronic cigarettes (e-cigarettes) highlights the need for accessible and reliable biomarkers to assess nicotine exposure. Fingernails represent a non-invasive and stable keratin matrix capable of capturing the long-term incorporation of xenobiotics such as cotinine, the primary metabolite of nicotine. This study aimed to optimise cotinine extraction from fingernails using Response Surface Methodology (RSM) with a central composite design prior to quantification by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Three extraction variables were evaluated: NaOH concentration, extraction temperature, and extraction time. Numerical optimisation identified the optimal conditions as 3.74 M NaOH, 50 °C, and 40 min, yielding a predicted recovery of 84.06% with a high desirability value of 0.973. The calibration curve demonstrated excellent linearity (R² = 0.9998), with a limit of detection of 14.5 µg kg⁻¹ and a limit of quantification of 43.8 µg kg⁻¹. The RSM model exhibited strong predictive performance, with an R² of 0.9990, an adjusted R² of 0.9982, and a predicted R² of 0.9958, supported by a non-significant lack of fit and robust residual diagnostics. Application of the optimised protocol to real fingernail samples successfully differentiated e-cigarette smokers from non-smokers based on characteristic cotinine-associated FTIR spectral features and quantitative measurements, demonstrating the practical utility of the proposed method. Overall, this study establishes a rapid, chromatography-free, and cost-effective analytical approach for monitoring long-term nicotine exposure using keratin-based matrices. Full article

The present study provides a comprehensive comparative evaluation of three Greek fig cultivars through integrated instrumental, computational, and chemometric approaches. Fresh fig peel and flesh samples were analyzed to determine total soluble solids, total phenolic and flavonoid content, as well as antioxidant and antiradical activities, complemented by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy for structural profiling. Significant varietal and tissue-dependent differences were observed, with fig peel exhibiting higher levels of phenolic compounds and antioxidant activity compared to flesh. ATR-FTIR spectral patterns revealed the presence of characteristic functional groups associated with carbohydrates, phenolic compounds, carboxylic acids, and volatile compounds, reflecting the influence of variety, pollination requirements, and geographical origin. In parallel, to explore potential neuroprotective relevance, 30 phytochemicals reported in figs were subjected to molecular docking against human β-secretase 1 (hBACE1), a key enzyme in Alzheimer’s disease (AD) pathogenesis. Phenolic acids and flavonoids displayed favorable binding affinities and interaction profiles with the catalytic Asp32–Asp228 dyad and with the flap domain. A machine learning model (XGBoost) trained on known BACE1 inhibitors further classified all examined fig metabolites as active candidates. Collectively, these findings highlight Greek figs as chemically rich fruits with potential biological properties, supporting future targeted studies on their bioactive potential. Full article

Cotton fiber length and maturity, two critical fiber qualities, are commonly determined in the U.S. by Uster high volume instrument (HVI) and advanced fiber information system (AFIS). The main objectives of this investigation were to compare how HVI lengths agree with AFIS lengths and to examine whether the fiber length is linked with fiber maturity between the Universal HVI length calibration cotton standards and diverse upland lint samples. HVI micronaire (MIC) and AFIS fineness showed insignificant differences from HVI length calibration cotton standards to lint samples. Although there were strong and significant correlations between HVI upper-half mean length (UHML) and either AFIS UQL (w) or AFIS L5% (n), the relationship between UHML and L5% (n) was better suited than between UHML and UQL (w) in scrutinizing fiber lengths. Meanwhile, analysis revealed a moderate correlation between AFIS L5% (n) length and AFIS maturity ratio (MR), indicating the possibility of improving AFIS L5% (n) length by regulating fiber MR development. Further, AFIS MR values were positive and moderate correlated with algorithmic M_IR values of attenuated total reflection Fourier transform infrared (ATR FT-IR) spectra. The results suggested the feasibility of the ATR FT-IR method along with M_IR analysis in estimating AFIS MR rapidly away from fiber testing laboratories. Full article

To explore the aging mechanism of (Styrene Butadiene Styrene) and CR (Crumb Rubber) composite-modified asphalt in a multi-source environment, the characteristics of functional group changes in the infrared spectroscopy of SBS and CR modifiers as well as their single and composite modified asphalts under thermal, UV, and coupled aging were tested using Attenuated Total Reflection–Fourier Transform Infrared Spectroscopy (ATR-FTIR) technology. It was found that SBS and CR modifiers exhibited significant yellowing degradation after aging due to high-energy effects, causing abstraction of α-hydrogen from polybutadiene via oxidation, initiating radical chain reactions. The addition of SBS and CR to asphalt significantly increased the absorption peaks of 966 cm⁻¹ polybutadiene and 699 cm⁻¹ polystyrene. However, certain labile bonds in the modified asphalt, such as the C-H bond, C-C bond, and C=C double bond in polycyclic aromatic hydrocarbons, were easily broken to produce reactive free radicals under aging, which reacted chemically with other components to produce new sulfoxide and carbonyl groups. Overall, the aging reaction of the asphalt was a dual sequential oxidation process. Under normal temperature conditions in the early stage, a large number of sulfoxides were oxidized. In the later stage of the reaction, as the concentration and persistence of active free radicals increased, the oxidation reaction of the asphalt benzyl carbon also enhanced significantly, ultimately generating carbonyls. Full article

The structure of self-assembled monolayers (SAMs) greatly influences electrochemical interface behavior. This study systematically examines how positional isomers of aromatic diamines (ADMs) assemble on a glassy carbon (GC) electrode and how such ordering affects the attachment and performance of electrochemically reduced graphene oxide (ERGO). SAMs of ortho-, meta-, and para-phenylenediamine (o-PDA, m-PDA, and p-PDA) were fabricated on GC and characterized using atomic force microscopy (AFM) and Raman spectroscopy. Among them, GC/p-PDA exhibited the most compact and homogeneous interfacial structure. ERGO was subsequently immobilized through the free amine functionalities of the SAM, as confirmed by attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Strong covalent coupling and electrostatic interactions between the positively charged ERGO and terminal amines enabled stable attachment. Under optimized conditions, the modified GC/p-PDA/ERGO electrode demonstrated exceptional electrocatalytic activity toward nitrobenzene (NBz) reduction, achieving a high sensitivity of 1410 μA mM⁻¹ cm⁻² and a low detection limit of 0.040 μM. In addition, this sensor displayed outstanding anti-interference capability, stability, and recovery in a water sample. These results establish GC/p-PDA/ERGO sensor as a robust and efficient electrocatalytically active interface for nitroaromatic pollutants detection and sustainable environmental monitoring. Full article

Early detection of premalignant cervical lesions is essential for improving cervical cancer outcomes; however, current screening methods frequently lack adequate sensitivity and specificity. This research introduces a diagnostic platform that integrates lectin-based biosensors with spectral and multivariate analysis. The biosensors are composed of gold nanoparticles (AuNPs) conjugated with Maackia amurensis (MAA) lectin, which selectively binds to α2,3-linked sialic acid. Validation was performed using cervical cancer cell lines (SiHa, HeLa, C33A), fibroblasts, and cervical scrapes, and specificity was verified by enzymatic removal of sialic acids. Spectral data were obtained using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and analyzed by principal component analysis (PCA). Application of PCA to the 1600–1350 cm⁻¹ spectral region, using 99% confidence ellipses, enabled clear differentiation between samples negative and positive for intraepithelial lesions in a double-blind study of 58 patients. The MAA biosensors exhibited high sensitivity and specificity, comparable to established diagnostic methods. These results indicate that the combination of ATR-FTIR spectroscopy, MAA lectin-based biosensors, and chemometric analysis provides a robust and reliable approach for early detection of premalignant cervical lesions, with considerable potential to enhance patient outcomes. Full article

Salicornia spp. is a halophytic plant with great potential in sustainable agriculture due to its ability to thrive in saline environments where conventional crops cannot grow. This study investigated Salicornia ramosissima J. Woods cultivated under two systems: hydroponics and substrate environments. The plants produced were subsequently preserved for food applications and chemically characterized within biorefinery processes. Analyses were performed using Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR-ATR), Ultraviolet/Visible Spectrophotometry, and Thin-Layer Chromatography (TLC). The hydroponic system proved to be the most promising cultivation method, promoting superior aerial growth ranging from 14% to 50% higher than substrate-grown plants throughout the cultivation period and achieving a higher biomass yield. Regarding pigment preservation, freezing best maintained compound integrity, as observed through TLC analysis, while desiccator and vacuum storage at room temperature were most suitable for hydroponically grown samples. Under vacuum storage, pigments pheophytin A and B and chlorophyll A showed an estimated 33% higher retention compared with desiccator storage. Both cultivation methods demonstrated potential for large-scale applications, highlighting Salicornia ramosissima J. Woods as a valuable crop for saline agriculture and sustainable food production. Full article

Agro-industrial chestnut waste derived from chestnut processing is usually discharged without further use. However, these residues are attractive due to their high-value composition, rich in sugars and lignin. Among these residues, chestnut burrs (CB) represent a promising feedstock for biorefinery applications aimed at maximizing the valorization of their main constituents. In this study, we propose an environmentally friendly approach based on deep eutectic solvents (DES) formed by choline chloride and urea (ChCl/U) (1:2, mol/mol) for the selective deconstruction of lignocellulosic architecture, followed by enzymatic hydrolysis to release second-generation (2G) fermentable sugars. Pretreatments were applied to raw CB, washed CB (W-CB), and the obtained solid fraction after prehydrolysis (PreH). Structural and morphological modifications, as well as crystallinity induced by DES pretreatment, were characterized using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). Remarkable results in terms of effectiveness and environmental friendliness on saccharification yields were achieved for PreH subjected to DES treatment for 8 h, reaching approximately 60% glucan and 74% xylan conversion under the lower enzyme loading (23 FPU/g) and liquid-to-solid ratio (LSR) of 20:1 studied. This performance significantly reduces DES pretreatment time from 16 h to 8 h at mild conditions (100 °C), lowers the LSR for enzymatic hydrolysis from 30:1 to 20:1, and decreases enzyme loading from 63.5 FPU/g to 23 FPU/g, therefore improving process efficiency and sustainability. Full article

The integration of Reverse Osmosis (RO) desalination with Renewable Energy (RE) sources offers a sustainable approach to freshwater production, particularly in remote and off-grid regions. However, the variable and intermittent output of RE power can cause operational instability that affects membrane performance and system reliability. This study experimentally evaluated a flat sheet seawater RO membrane under variable conditions emulating a Photovoltaic (PV)-powered system over three days. Three scenarios were examined: (i) steady full-load operation representing PV with battery storage, (ii) variable operation representing sunny-day PV output, and (iii) highly variable operation representing cloudy-day PV output. A Variable Frequency Drive (VFD) regulated by an Arduino microcontroller adjusted high-pressure pump operation in real time to replicate power fluctuations without energy storage. Each scenario operated for eight hours per day and was tested with and without end-of-day rinsing. Under the highly variable cloudy-day scenario without rinsing, water permeability decreased by 37%, salt rejection decreased by 18%, and membrane resistance increased by 37%, indicating compaction and fouling effects. Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) confirmed structural changes in membranes exposed to fluctuating conditions. These results highlight the need for improved operational strategies to protect membrane longevity in RE-powered desalination systems. Full article

Background/Objectives: Plants inhabiting mediterranean-influenced climatic zones, like Helichrysum stoechas (L.) Moench subsp. stoechas, Lavandula pedunculata (Mill.) Cav., and Thymus mastichina (L.) L. subsp. mastichina, have been scarcely investigated regarding their richness in phenolic compounds, herein explored as sources of skin anti-aging compounds. Methods: In this investigation, Fourier transform infrared spectroscopy (FTIR) in attenuated total reflectance (ATR) mode and high-performance liquid chromatography coupled with diode-array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI/MSⁿ) were employed to chemically characterize the hydroethanolic extracts (HEs), and their cell-free antioxidant potential was screened. Thereafter, non-toxic concentrations of HEs were determined in human skin cells using Alamar blue^® and Sulforhodamine B assays. The cytoprotective and antioxidant effects of HEs were assessed in tert-butyl hydroperoxide-stimulated fibroblasts, their anti-inflammatory potential was studied in lipopolysaccharide-injured macrophages, and enzymatic inhibition assays were performed. Notably, the irritant effects of HEs were tested according to Test Guideline No. 439 of the Organization for Economic Co-operation and Development (OECD). Results: The major compounds identified in the T. mastichina and L. pedunculata HEs were rosmarinic and salvianolic acid derivatives, while H. stoechas HE was mainly composed of caffeoyl and feruloyl derivatives, and O-glycosylated flavonoids. T. mastichina (≤0.4 mg/mL) exhibited significant cytoprotective, anti-inflammatory, and antioxidant effects, as well as remarkable anti-hyaluronidase activity. Conclusions: Shedding light on the quantitative and qualitative chemical picture of these HEs highlighted T. mastichina as a promising candidate to target skin aging effects, which correlates with its phenolic content. Further investigation is warranted regarding its anti-aging pharmacological activity, which could lead to the development of plant-based skin anti-aging products. Full article

Two folding screens by futurist artist Giacomo Balla (1871–1958) in the collection of the Kröller-Müller Museum (the Netherlands) were investigated: Paravento con linea di velocità (1916–1917) and Paravento (1916/1917–1958). The screens are painted on both sides, the first on four canvases, stretched onto two wooden strainers and framed with painted wooden strips, and the second on wooden panels set into four painted stiles. In the past, damages on Paravento con linea di velocità were restored by conservators, while Paravento was probably first reworked by the artist himself and later restored by conservators. Yellowed varnish and discolored retouches on both screens led to a wish for treatment. The aim of this research was to gain insight into the painting techniques, layer buildup, pigments, binders, and varnishes of the two artworks. This information supported the decision making for treatment, and it broadens the knowledge on the materials used by Balla. Up to now, only a few published studies deal with the technical examination of paintings by this artist. Both folding screens were subjected to technical photography (UV, IR photography, and X-ray) and were examined with portable point X-ray fluorescence (pXRF) and Raman spectroscopy. Moreover, samples were taken. Cross-sections were studied with optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), attenuated total reflection Fourier-transform infrared (ATR-FTIR) imaging, and micro-Raman spectroscopy. Loose samples were examined with SEM-EDX, FTIR and micro-Raman spectroscopy, and pyrolysis gas chromatography mass spectrometry (Py-GC/MS). For Paravento con linea di velocità, all pigments and fillers of the painted canvases are compatible with the dating of the screen (1916–1917), but they differ from those on the frame. Here, rutile, in combination with various pigments, among which are blue copper phthalocyanine (PB15) and other synthetic organic pigments, was found. This indicates that the frame has been painted later, likely after the Second World War. The composition of the binders differs as well. Drying oil and pine resin have been used on the canvases, explaining the smooth and glossy appearance and solvent-sensitivity of the paint. On the frame, oil with some alkyd resin was identified. The provenance of the screen before 1972 is not clear, nor when the frame was made and painted and by whom. The results for Paravento indicate that the palettes of the two sides—painted in different styles—are comparable. Mainly inorganic pigments were found, except for the dark red areas, where toluidine red (PR3) is present. pXRF showed high amounts of zinc; cross-sections revealed that zinc white is present in the lower layers. These pigments are compatible with the dating of the screen (1916–1917). In many of the upper paint layers though, except for some green, dark red, and black areas, rutile has been identified. This indicates that these layers were applied later, likely after the Second World War. Since this folding screen was used by the artist and his family until his death in 1958, it seems likely that Balla himself reworked the screen. Full article

Lignin obtained in acidic conditions is a waste product in various technological processes like sulfite pulping, organosolv pulping, or bioethanol production. Knowing the structure of the lignin enables its use in high-value-added applications. In this paper, the lignin structure isolated from Pinus sylvestris L. and Populus deltoides × maximowiczii wood in acidic conditions was investigated. Two methods of lignin isolation (Klason method and a method using a sulfuric and phosphoric acid mixture) were compared. Additionally, lignin acetylation was performed. The lignin samples were analyzed using different instrumental techniques, such as size exclusion chromatography (SEC), attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). Based on the studies carried out, it was found out that the lignin isolated from pine and poplar wood in acidic conditions had a highly condensed structure. This was evidenced by the high-weight average molar mass of lignin (up to 118,700 g/mol) and the precipitates, aggregates, and agglomerates on its surface. Moreover, the characteristic signals of condensed lignin in ATR-FTIR analysis (band with wavenumber of 767 cm⁻¹) and their decrease/disappearance (band that usually occurs with a wavenumber of about 814 cm⁻¹) were observed. Lignin acetylation and analysis in the 0.5% LiCl/DMAc system have proven particularly effective in the case of the condensed poplar lignin. The beneficial effect of lignin acetylation was confirmed by SEM analysis. The high-molecular-weight condensed lignin, despite some of its problematic properties connected mainly with solubility, is a valuable substance that can be used for different applications (carbon fibers or as an additive for thermoplastic blends), which was confirmed by the studies in this paper and the findings of other scientists. Full article

This study presents the synthesis and comprehensive characterization of tin dioxide nanoparticles (SnO₂NPs). SnO₂NPs were obtained using a conventional wet-chemistry route and an environmentally friendly green-chemistry approach employing plant extracts from rooibos leaves (Aspalathus linearis), pomegranate seeds (Punica granatum), and kiwifruit peels (family Actinidiaceae). The thermal stability and decomposition profiles were analyzed by thermogravimetric analysis (TGA), while their structural and physicochemical properties were investigated using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), ultraviolet–visible (UV–Vis) spectroscopy, dynamic light scattering (DLS), Raman spectroscopy, and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy. Transmission electron microscopy (TEM) confirmed the nanoscale morphology and uniformity of the obtained particles. The photocatalytic activity of SnO₂NPs was evaluated via the degradation of methyl orange (MeO) under UV irradiation, revealing that nanoparticles synthesized using rooibos extract exhibited the highest efficiency (68% degradation within 180 min). Furthermore, surface-enhanced Raman scattering (SERS) spectroscopy was employed to study the adsorption behavior of L-phenylalanine (L-Phe) on the SnO₂NP surface. To the best of our knowledge, this is the first report demonstrating the use of pure SnO₂ nanoparticles as SERS substrates for biologically active, low-symmetry molecules. The calculated enhancement factor (EF) reached up to two orders of magnitude (10²), comparable to other transition metal-based nanostructures. These findings highlight the potential of SnO₂NPs as multifunctional materials for biomedical and sensing applications, bridging nanotechnology and regenerative medicine. Full article