Search Results (906)

Background: Graphene oxide (GO) is widely explored as a functional additive in polymer composites; however, its simple physical dispersion in dental resins often leads to poor interfacial stability and limited long-term performance. Covalent functionalization may overcome these limitations by enabling chemical integration into the polymer matrix. This study presents the synthesis and FT-IR/Raman characterization of GRAPHYMERE^®, a novel graphene oxide-based monomer obtained through exfoliation, amine functionalization with 1,6-hexanediamine, and transamidation with methyl methacrylate. Methods: A novel GO-based monomer, GRAPHYMERE^®, was synthesized through a three-step process involving GO exfoliation, amine functionalization with 1,6-hexanediamine, and transamidation with methyl methacrylate to introduce polymerizable acrylic groups. The resulting product was characterized using FT-IR and Raman spectroscopy. Results: Spectroscopic analyses confirmed the presence of aliphatic chains and amine functionalities on the GO surface. Although some expected signals were overlapped, the data suggest successful surface modification and partial insertion of methacrylamide groups. The process is straightforward, uses low-toxicity reagents, and avoids complex reaction steps. Conclusions: GRAPHYMERE^® represents a chemically modified GO monomer potentially suitable for copolymerization within dental resin matrices. While its structural features support compatibility with radical polymerization systems, further studies are required to assess its mechanical performance and functional properties in dental resin applications. Full article

Tomatoes are among the most widely consumed and economically significant fruits in the world. However, the extensive use of pesticides in their cultivation has led to the contamination of the peels, posing potential health risks to consumers. As one of the top global producers, consumers, and exporters of tomatoes, Mexico requires rapid, non-destructive, and real-time methods for pesticide monitoring. In this study, a detailed characterization of six pesticides using Raman and Fourier Transform Infrared (FT-IR) spectroscopies was carried out to identify their characteristic vibrational modes. The pesticides examined included different chemical classes commonly used in tomato cultivation: organophosphorus (dichlorvos and methamidophos), pyrethroids (lambda-cyhalothrin and cypermethrin), and carbamates (methomyl and benomyl). Tomato peel samples were examined both before and after pesticide application. Prior to treatment, the peel exhibited a well-organized polygonal structure and showed the presence of carotenoid compounds. After pesticide application, no visible structural damage was observed; however, distinct vibrational bands enabled the detection of each pesticide. Organophosphorus pesticides could be identified through vibrational bands associated with P-O and C-S bonds. Pyrethroid detection was facilitated by benzene ring breathing modes and C=C stretching vibrations, while carbamates were identified through C-N stretching contributions. Phytotoxicity testing in the presence of pesticides indicates no significant damage during the germination of tomatoes. Full article

After reviewing the state of the art of the fluorination of inorganic solid electrolytes, an application of gas/solid fluorination is given and how it can be processed. Garnet-type oxide has been chosen. These oxides with an ideal structure of chemical formula A₃B₂(XO₄)₃ are mainly known for their magnetic and dielectric properties. Certain garnets may have a high enough Li⁺ ionic conductivity to be used as solid electrolyte of lithium ion battery. The surface of LLZO may be changed in contact with the moisture and CO₂ present in the atmosphere that results in a change of the conductivity at the interface of the solid. LiOH and/or lithium carbonate are formed at the surface of the garnet particles. In order to allow for handling and storage under normal conditions of this solid electrolyte, surface fluorination was performed using elemental fluorine. When controlled using mild conditions (temperature lower or equal to 200 °C, either in static or dynamic mode), the addition of fluorine atoms to LLZO with Li_6,4Al_0,2La₃Zr₂O₁₂ composition is limited to the surface, forming a covering layer of lithium fluoride LiF. The effect of the fluorination was evidenced by IR, Raman, and NMR spectroscopies. If present in the pristine LLZO powder, then the carbonate groups disappear. More interestingly, contrary to the pristine LLZO, the contents of these groups are drastically reduced even after storage in air up to 45 days when the powder is covered with the LiF layer. Surface fluorination could be applied to other solid electrolytes that are air sensitive. Full article

This study explores the feasibility of utilizing granite sawing sludge (FC) as a precursor to produce alkali-activated materials (AAMs). To enhance the reactivity of the system, metakaolin (MK) was added and binary mixtures were synthetized. A multidisciplinary approach, including mineralogical, chemical and mechanical analysis, was employed to assess the suitability of these precursors to produce AAMs. X-Ray diffraction (XRD) and Fourier-Transform Infrared spectroscopy (FT-IR) confirmed the occurred activation reaction with the consequent increase in the amorphous content. Raman spectroscopy was used to further explore the mineralogical composition of the consolidated specimens, helping in the detection of salts, whose formation is ascribed to secondary carbonatation processes. Morphological analysis (SEM-EDS) displayed relatively uniform microstructures for all specimens. Compressive strength tests revealed that MK rich samples achieved best values compared to FC rich formulations, which exhibited reduced strength resistance. This study highlights, for the first time, the benefits of incorporating Cuasso al Monte granite sawing sludges into alkali-activated binders. Results suggested that the incorporation of FC is recommended for both environmental and economic advantages. Full article

This paper presents the synthesis of La₂Ti₂O₇ nanoparticles by the sol–gel method starting from lanthanum nitrate and titanium alkoxide (noted as LTA). Subsequently, the lanthanum titanium oxide nanoparticles are modified with noble metals (platinum) using the chemical impregnation method, followed by a reduction process with NaBH₄. The comparative analysis of the structure and surface characteristics of the nanopowders subjected to thermal treatment at 900 °C is conducted using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet-visible (UV–Vis) spectroscopy, as well as specific surface area and porosity measurements. The photocatalytic activity is evaluated in the oxidative photodegradation of ethanol (CH₃CH₂OH) under simulated solar irradiation. The modified sample shows higher specific surfaces areas and improved photocatalytic properties, proving the better conversion of CH₃CH₂OH than the pure sample. The highest conversion of ethanol (29.75%) is obtained in the case of LTA-Pt after 3 h of simulated solar light irradiation. Full article

This research focused on studying the issue of coating ammonium nitrate (AN) with nitrocellulose (NC) and its microcrystalline form (MNC), using two esterification methods: traditional (HNO₃/H₂SO₄) and in situ synthesis (KNO₃/H₂SO₄). This study employed Raman and IR spectroscopy, SEM, as well as thermokinetic and mechanical analyses. The results showed that the addition of NC-KNO₃ significantly increased the pseudo-energy of activation (E_A ≈ 268 kJ/mol for pure NC), improving thermal stability. MNC modifications, however, yielded inconclusive results. Despite the confirmed presence of NC on the AN surface (Raman band at 1128 cm⁻¹), SEM analysis did not show formation of a core–shell structure—a reversed-layer formation was observed, where AN deposited onto NC instead of the expected coating. The addition of diesel oil reduced the sensitivity of the mixtures (e.g., ANNC-D showed 35 J for impact and 288 N for friction) due to improved homogeneity. The esterification method affected the mechanical properties of the material: NC synthesised from HNO₃ was less sensitive than that obtained from KNO₃. This paper highlights the key role of nitrocellulose in modifying the properties of energetic materials, but further research is needed to control the coating process and optimise the synthesis conditions. Full article

LiTaO₃ crystals doped with Cr³⁺ and Nd³⁺ ions are promising for developing active nonlinear laser media. In this work, the defect structure of LiTaO₃ crystals, including those doped with Cr³⁺ and Nd³⁺, is examined. X-ray patterns of all six investigated LiTaO₃:Cr:Nd crystals are identical and correspond to a highly perfect structure. Using optical microscopy, the presence of defects of various shapes, microinhomogeneities, and lacunae was revealed. The optical absorption and Raman scattering spectra of a series of nonlinear, optical, double-doped LiTaO₃:Cr³⁺:Nd³⁺ (0.06 ≤ [Cr³⁺] ≤ 0.2; 0.2 ≤ [Nd³⁺] ≤ 0.45 wt%) crystals showed that at concentrations of doping Cr³⁺ ions less than 0.09 wt% and Nd³⁺ ions less than 0.25 wt%, the crystal structure is characterized by a low level of defects, and the optical transmission spectra characterized by narrow lines corresponding to electron transitions in Nd³⁺ ions. In this case, for the radiative transition in the cation sublattice, the existence of three nonequivalent neodymium centers is observed, and for the radiative transition, two nonequivalent centers are observed. IR absorption spectroscopy in the OH⁻-stretching vibration range revealed two main spectral regions: 3463–3465 cm⁻¹, associated with stoichiometry changes, and 3486–3490 cm⁻¹, linked to complex defects such as (V^-_Li)-OH and (Ta⁴⁺_Li)-OH. A distinct low-intensity line at ~3504 cm⁻¹ was observed only in doped crystals, attributed to (Nd²⁺_Li)-OH defects that significantly distort the oxygen-octahedral clusters due to the larger ionic radius of Nd³⁺ compared to Ta⁵⁺. In contrast, Cr-related defects cause only minor distortions. The Klauer method indicated that the highest concentration of OH⁻-groups occurs in the LiTaO₃:Cr³⁺ (0.09 wt%):Nd³⁺ (0.25 wt%) crystal, where multiple complex defects are present. Full article

To address the challenge of ultra-deep desulfurization in fuels, a series of heteropolyacid-based poly(ionic liquid) catalysts (C4-PIL@PW, C8-PIL@PW, and C16-PIL@PW) were synthesized via radical polymerization and anion exchange methods. The prepared catalysts were characterized via FT-IR, XRD pattern, and Raman spectroscopy. Optimal reaction parameters (e.g., temperature, catalyst dosage, and O/S molar ratio) were systematically investigated, as well as the catalytic mechanism. The typical sample C8-PIL@PW exhibited exceptional oxidative desulfurization (ODS) performance, achieving a sulfur removal of 99.2% for dibenzothiophene (DBT) without any organic solvent as extractant. Remarkably, the sulfur removal could still retain 89% after recycling five times without regeneration. This study provides a sustainable and high-efficiency catalyst for ODS, offering insights into fuel purification strategies. Full article

The incorporation of commercial graphene oxide (GO) into composites offers significant improvements in mechanical, thermal, and electrical properties, making it a promising material for industrial applications. This study presents a comprehensive characterization analysis of five commercial GOs, using advanced techniques to evaluate their structural, chemical, and especially their behavior when submitted to thermal treatment. The aim is to enable the use of GO in industrial processes of particular technological importance, where its thermal stability/integrity is required, such as in polymer composites, electronic and energy storage devices, among others. Raman spectroscopy and attenuated total reflectance–Fourier-transform infrared (ATR-FTIR) spectroscopy are employed to examine the structural defects and functional groups of GOs, while X-ray diffraction (XRD) provides insight into the crystallinity and interlayer spacing. Thermogravimetric analysis (TGA) assesses the thermal stability, and X-ray photoelectron spectroscopy (XPS) offers detailed information on the surface chemistry and relevant elemental composition of GOs. Additionally, the temperature-dependent behavior of GOs is explored through temperature-dependent XRD and IR measurements to investigate the thermal expansion and functional group stability. The study highlights the critical role of oxygen-containing groups—such as epoxides, hydroxyls, and carboxyls—while variations in the type and concentration of these functional groups across commercial GOs could influence the compatibility and performance of nanocomposites. This research attempts to fill to some extent the gap in understanding how the unique properties of different commercial GOs can be strategically applied to meet specific industrial performance requirements, such as barrier properties, transport efficiency, or mechanical strength, among others. Full article

This study focused on composites of magnetite magnetic nanoparticles (MNP) and poly(lactic acid) (PLA) prepared via sonochemical synthesis. The evaluation of MNP loadings (2, 5, 10, 15, and 20 wt.%) provided insights into the structural and reactivity properties of the materials. Methods used included XRD, FT-IR and Raman spectroscopy, SEM and TEM microscopy, textural and thermal analysis (TG and DTA), and magnetic property measurements. The agreement between theoretical and experimental MNP loadings was good. XRD patterns showed predominantly MNP and semicrystalline phases, with a minor maghemite phase detected by FT-Raman and magnetic measurements. FT-IR analysis revealed interactions between MNP and PLA, confirmed by thermal analysis showing higher transition temperatures for the composites (145 °C) compared to pure PLA (139 °C). FT-Raman spectra also indicated that PLA helps prevent iron oxide oxidation, enhancing nanoparticle stability. SEM and TEM micrographs showed well-dispersed, spherical nanoparticles with minimal agglomeration, dependent on MNP loading. The nanocomposites exhibited low N₂ adsorption, resulting in low surface area (~2.1 m²/g) and porosity (~0.03 cm³/g). Magnetic analysis indicated that in the 2MNP/PLA sample, MNP were in a superparamagnetic-like regime at 300 K, suggesting good dispersion of 2 wt.% MNP in the PLA matrix. Full article

This study investigated the chemical, thermal, and mechanical properties of segmented polyurethanes (SPUs) synthesized using less common biodegradable polyester polyols, specifically poly(adipate) (PAD) and poly(sebacate) (PSC), to evaluate their potential as nerve guidance conduits (NGCs) in peripheral nerve regeneration. The synthesis of novel 4,4′ methylene-bis-cyclohexyl diisocyanate (HMDI) SPUs was conducted in a two-step process: prepolymer formation and chain extension with 1,4-butanediol (BO) or 1,4-butanediamine (BA). SPUs were synthesized with two molar ratios—polyol:HMDI:BA/BO at 1:2:1 and 1:3:2 for the PAD:HMDI:BA system—to optimize mechanical properties. 1HRMN analysis verified the expected chemical structure of SPUs, whereas Raman and IR spectroscopy confirmed successful polyurethane synthesis. X-ray diffractograms showed that PAD-based SPUs (SPUPAD) were amorphous while PSC-based SPUs (SPUPSC) exhibited semi-crystalline behavior. SPUPAD showed only one degradation stage by TGA, while DSC showed one thermal event. In contrast, SPUPSC exhibited two degradation stages and three thermal events that confirmed phase separation. The longitudinal tensile properties of an NGC fabricated from SPUA-PAD-2 (PAD:HMDI:BA (1:3:2)) after 30 days of immersion in water (25 °C) showed a lower modulus (4.46 ± 0.5 MPa) than native intact nerves (15.87 ± 2.21 MPa) but a similar modulus to extracted nerves (8.19 ± 7.27 MPa). This system exhibited a longitudinal tensile force of 11.1 ± 1.6 N, which is lower than that of peripheral nerves (19.85 ± 7.21 N) but higher than that of commercial collagen-based nerve guide conduits (6.89 ± 2.6 N). The observed properties suggest that PUA-PAD-2 has potential as a biomaterial for nerve regeneration applications. Full article

Aerogels have gained much interest in the last decades due to their specific properties, such as high porosity, high surface area, and low density, which have caused them to be used in multiple and varied fields. As the applicability of aerogels is tightly correlated to their morpho-structural features, special consideration must be allocated to the fabrication method. An emerging technique for producing nanostructured materials with tailored morphology and dimensions is represented by continuous-flow microfluidics. In this context, this work explores the synergic combination of aerogel-based materials with microfluidic synthesis platforms to generate advanced nanocomposite adsorbents for water decontamination. Specifically, this study presents the novel synthesis of a magnetic silica-based aerogel using a custom-designed 3D microfluidic platform, offering enhanced control over nanoparticle incorporation and gelation compared to conventional sol–gel techniques. The resulting gel was further dried via supercritical CO₂ extraction to preserve its unique nanostructure. The multi-faceted physicochemical investigations (XRD, DLS, FT-IR, RAMAN, SEM, and TEM) confirmed the material’s uniform morphology, high porosity, and surface functionalization. The HR-MS FT-ICR analysis has also demonstrated the advanced material’s adsorption capacity for various pesticides, suggesting its adequacy for further environmental applications. An exceptional 93.7% extraction efficiency was registered for triazophos, underscoring the potential of microfluidic synthesis approaches in engineering advanced, eco-friendly adsorbent materials for water decontamination of relevant organic pollutants. Full article

Using optical spectroscopy methods including absorption in the UV-VIS, FTIR, Raman, and fluorescence, the spectra of 25 different Baltic amber samples were measured, and the ability of each method to distinguish between thermally modified and naturally aged material was analyzed. The natural ambers studied are characterized by a wide range of spectral properties: the position of the transmission edge in the UV-VIS spectra, the absorbance ratios of the C-H and C=O groups in the IR spectra, a difference of approximately 20% in the fluorescence intensity level, and differences in the band ratios in the C=C and C-H bonds in the Raman spectrum. Spectral studies were carried out on samples of natural and thermally modified amber at temperatures of 100, 150, and 200 °C for 2–8 h. Drastic changes occur at temperatures above 150 °C: the color changes to dark brown, the UV-VIS transmission edge shifts, the absorbance of the C=O group increases, the absorbance intensity of the C=C bond decreases, and fluorescence disappears. In some special cases, fluorescence methods allow for the unambiguous distinction of amber from different geographical regions (e.g., Baltic and Dominican). Spectroscopic methods can distinguish natural amber from thermally modified amber only for large changes in the spectrum at temperatures of 150–200; for smaller changes, the differences between individual samples of natural amber may be greater than in the case of thermal modification. Full article

The clinical utility of sulfonamide antibiotics is increasingly challenged by antimicrobial resistance and pharmacokinetic limitations. In this study, we synthesized five graphene oxide–sulfonamide nanoconjugates (GO–S1 to GO–S5) via covalent functionalization, comprehensively characterized them by IR, Raman, SEM, EDS, etc., and evaluated their antimicrobial, antibiofilm, cytotoxic, apoptotic, hemolytic and gene expression-modulating effects. While the free sulfonamides (S1–S5) exhibited superior antimicrobial activity in planktonic cultures (MICs as low as 19 μg/mL), their GO-functionalized counterparts demonstrated enhanced antibiofilm efficacy, particularly against Pseudomonas aeruginosa (MBIC: 78–312 μg/mL). Cytotoxicity studies using CellTiter assays and Incucyte live-cell imaging revealed low toxicity for all compounds below 250 μg/mL. Morphological and gene expression analyses indicated mild pro-apoptotic effects, predominantly via caspase-9 and caspase-7 activation, with minimal caspase-3 involvement. Hemolysis assays confirmed the improved blood compatibility of GO–Sx conjugates compared to GO alone. Furthermore, qRT-PCR analysis showed that GO–Sx modulated the expression of key xenobiotic metabolism genes (CYPs and NATs), highlighting potential pharmacokinetic implications. Among all tested formulations, GOS3, GOS4 and GOS5 emerged as the most promising candidates, balancing low cytotoxicity, high hemocompatibility and strong antibiofilm activity. These findings support the use of graphene oxide nanocarriers to enhance the therapeutic potential of sulfonamides, particularly in the context of biofilm-associated infections. Full article

Previously, we reported that microplastic volatile organic compounds are present within the Chrysaora chesapeakei of Chesapeake Bay, MD. In this study, we report the presence of contaminants of emerging concern (CECs) on the hydrophobic surface of microplastic (MP) particles extracted from the C. chesapeakei, detected by Raman spectroscopy and identified by Wiley’s KnowItAll Software with IR & Raman Spectral Libraries. C. chesapeakei encounters various microplastics and emerging contaminants as it floats through the depths of the Patuxent River water column. This study identifies subsuming CECs found directly on microplastics from within C. chesapeakei in the wild using Raman spectroscopy. Among the extracted microplastics, some of the emerging contaminants found on the different microplastics were pesticides, pharmaceuticals, minerals, food derivatives, wastewater treatment chemicals, hormones, and recreational drugs. Our results represent the first of such findings in C. chesapeakei, obtained directly from the field, and indicate C. chesapeakei’s relationship with microplastics, with this species serving as a vector of emerging contaminants through the marine food web. This paper further illustrates a relationship between different types of plastics that attract dissimilar types of emerging pollutants in the same surrounding environmental conditions, underscoring the urgent need for further research to fully understand and mitigate the risks that MPs coexist with contaminants. Full article