Search Results (654)

Zirconia orthodontic brackets exhibit favorable mechanical and esthetic properties; however, their chemically inert surfaces can limit adhesion to resin cements. This study evaluated the effect of multi-gas atmospheric plasma irradiation on the shear bond strength (SBS) of zirconia brackets. Zirconia brackets were treated with nitrogen (N₂), argon (Ar), or air plasma for 3 and 10 s and compared with untreated controls and conventional alumina-sandblasted specimens. Surface wettability was assessed by contact angle measurements, and surface chemical changes were analyzed using Fourier transform infrared (FT-IR) spectroscopy. After 10 s of plasma treatment, the water-contact angle decreased from 64.3° ± 8.4° in the untreated group to 17.9° ± 6.4°, 18.8° ± 2.7°, and 16.8° ± 5.3° with Ar, N₂, and air, respectively. For SBS testing, zirconia brackets were bonded to bovine enamel, stored in distilled water at 37 °C for 24 h, and subsequently tested (n = 12–15 per group). The mean SBS was 20.99 ± 2.87 MPa for the untreated group, 25.50 ± 2.40 MPa for the sandblasted group, and 23.63 ± 3.33, 23.99 ± 3.26, and 23.98 ± 3.58 MPa after 10-s Ar, N₂, and air plasma treatment, respectively. FT-IR revealed no new absorption peaks. Within the limitations of this study, multi-gas atmospheric plasma treatment markedly reduced the apparent water-contact angle measured on flat zirconia specimens, whereas its effect on SBS relative to the untreated group was not statistically significant. Full article

Linear dichroism (LD) optical absorption spectroscopy historically has found substantial yet still limited application in broad areas of science. In particular, full-dipole-tensor reconstruction has been onerous, usually requiring tedious and difficult measurements on single crystals at many orientations using a four-circle goniometer. As a consequence, it is very seldom done. Here, we propose, and test by numerical simulation, a simpler, faster, novel method of determining the full dipole optical absorption tensor of homogeneous planar films in real time as a function of energy (or wavelength), while requiring only minimal additional time and instrumentation. The goal of this paper is to explain the theory and to demonstrate the effectiveness and stability of the procedure using synthetic data sets. Experimental implementation and testing is deferred to future work and publications. The full-tensor spectrum, after construction from the experimental data, allows one to instantly calculate the absorption for any selected polarization direction, even those that are physically inaccessible to experimental measurement. Although our specific application in this paper is X-ray Absorption Fine Structure (XAFS) Spectroscopy, the method should be applicable to UV–Vis, IR, THz, microwave, and other wavelengths. A strength of this measurement modality is that full-tensor data can be acquired using essentially the same sort of scanning geometry that is normally used for XAFS, with only a discrete shift in the spin axis orientation between groups of scans. The additional instrumentation needed to determine the five Fourier components of the signal at each energy is minimal; two angles gives ten parameters, while six are strictly needed. Robust inversion from data to tensor elements is demonstrated, implemented via simple matrix multiplication. Outside of XAFS, FTMAPS is also expected to be applicable to diverse scientific and technological areas such as oriented bio-molecular films, semiconductor and materials physics, and process control of thin-film photovoltaics and semiconductors. Full article

The study of degradation processes is of fundamental and applied interest. To understand the degradation of cellulose nitrate and to develop sensitive diagnostic methods, combined experimental and theoretical investigations are essential. Sensitive, non-destructive, and contactless methods for diagnosing the state of cellulose nitrate include IR absorption and Raman spectroscopy. While significant experimental work exists, the theoretical modeling of degradation processes, including the prediction of potential products, remains underdeveloped. Therefore, in this work, the structures and vibrational properties of molecular clusters representing segments of the cellulose nitrate chain were modeled using density functional theory (DFT). This approach yielded simulated IR and Raman spectra, allowing for the identification of peaks corresponding to the nitrate group. The elimination of this group to form a ketone was shown to alter peak contours across a broad spectral range. The most significant changes in the Raman spectra were observed at 605 and 851 cm⁻¹. Correspondingly, the key changes in the IR absorption spectra occurred at 836, 1034, 1169, 1283, and 1767–1781 cm⁻¹. The frequency trends for these diagnostic peaks across different model structures were analyzed and compared with experimental spectra from the literature. The demonstrated correlation between specific peak-frequency changes and the modeled degradation products constitutes the principal novelty of this work. Full article

The primary objective of this study was to compare the contribution of cellular and cell-free filtrates of Serratia marcescens ATCC 9986 to the synthesis of silver nanoparticles, followed by a determination of the inhibitory activity on growth of S. marcescens and E. coli of the obtained biogenic silver nanoparticles. The synthesized silver nanoparticles exhibited maximum absorption at 257 nm and 262 nm when analyzed by ultraviolet–visible spectroscopy (UV–Vis). Energy-dispersive X-ray spectroscopy (EDX) analysis revealed a peak at 3 keV, corresponding to silver nanocrystals. Characterization by TEM, EDX, and IR spectroscopy demonstrated the presence of organic compounds in the nanoparticles. IR analysis revealed the presence of proteins, carbohydrates, carboxylic acids, and other compounds with saturated and unsaturated C-C bonds in the nanoparticles. Silver nanoparticles synthesized using cell-free and cellular filtrates inhibited growth of antibiotic-resistant bacteria E. coli. Moreover, cell-free filtrate of S. marcescens exerted inhibitory activity against E. coli, but not against its source, S. marcescens bacteria. Full article

Levofloxacin is an antibiotic belonging to the fluoroquinolone family. N-Demethyllevofloxacin, a metabolite and an impurity of levofloxacin, features a secondary amine that is susceptible to N-nitrosation, raising concerns about the formation of a potentially toxic nitrosamine. The corresponding N-nitrosamine was synthesized in two steps and characterized using HRMS, NMR spectroscopy, IR spectroscopy, UV absorption and emission spectroscopies and powder X-ray diffraction. This work provides a reliable reference for the quantitation and control of nitrosamine impurities associated with levofloxacin in chemical and pharmaceutical contexts. Full article

Background/Objectives: Baicalin (BA), a natural flavonoid with anti-inflammatory activity, shows promise for treating acute pharyngitis (AP) but its clinical application is hindered by poor water solubility and low oral bioavailability. Based on the clinically validated traditional Chinese medicine formula Pudilan Oral Liquid, we identified that BA and chlorogenic acid (CGA) can self-assemble into nanocomplexes (BA-CGA@NPs). This study aims to construct such a nanocomplex to enhance BA absorption and anti-AP efficacy with favorable biocompatibility. Methods: BA-CGA@NPs were prepared via supramolecular self-assembly and characterized by dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and molecular dynamics simulation (MDS). In vivo pharmacokinetics evaluated BA absorption. Biocompatibility and therapeutic efficacy were assessed using lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and an AP rat model. Results: BA-CGA@NPs were successfully formed with enhanced biocompatibility. In vitro, they reduced nitric oxide (NO), reactive oxygen species (ROS), tumor necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β) in macrophages. In AP rats, oral BA-CGA@NPs significantly increased systemic BA exposure, ameliorated pharyngeal histopathology, and lowered IL-1β, TNF-α, and interleukin-6 (IL-6) in serum and pharyngeal tissue, outperforming free BA or CGA alone. Mechanistic studies suggested that the anti-inflammatory effect was associated with modulation of the Toll-like receptor 4 (TLR4)/MyD88/Nuclear factor-κB (NF-κB) signaling pathway. Conclusions: Self-assembled BA-CGA@NPs enhance BA absorption and biocompatibility, alleviating AP inflammation through mechanisms associated with modulation of the TLR4/MyD88/NF-κB pathway, offering a promising nano-traditional Chinese medicine strategy for poorly soluble active ingredients. Full article

Cationic lanthanide luminophores remain underexplored compared with their neutral analogues, despite attractive features for solution-processed electroluminescent devices. Here we report the synthesis and characterization of five europium(III) cationic complexes of the type [Eu(L^{N,N})₂(L^{O,O})₂][PF₆], where L^{N,N} = 2,2′-bipyridine, 1,10-phenanthroline, or bathophenanthroline and L^{O,O} = acetylacetonate (acac) or hexafluoroacetylacetonate (hfac). These complexes are obtained in good yield via one-pot reactions from EuCl₃·6H₂O, β-diketonates, and diimine ligands, and are confirmed by FT-IR and RAMAN spectroscopies, elemental analysis, and single-crystal X-ray diffraction to possess well-defined EuO₄N₄ coordination spheres with PF₆ counterions. UV–Vis spectra show intense ligand-centered π–π* bands below ~300 nm and weak visible tails, consistent with efficient antenna sensitization and negligible direct Eu(III) f–f absorption. All complexes exhibit characteristic Eu(III) emission between ~575 and 725 nm, dominated by the ⁵D₀ → ⁷F₂ transition near 610–620 nm for all complexes and ⁵D₀ → ⁷F_3,4 transitions for 4 and 5, with similar line patterns but markedly different intensities. Replacing acac with hfac dramatically enhances performance with the quantum yields increasing from 15–18% to 85–93%, and excited-state lifetimes from 1.01–1.53 ms to 2.50–3.25 ms. These gains are attributed to improved ligand triplet to Eu(III) ⁵D₀ energy matching and reduced multiphonon relaxation, establishing these cationic Eu(III) complexes as promising emitters for solution-processable photonic devices. Full article

To address the key issues of uneven distribution of functional groups, large dispersion of holographic storage performance across different regions, and poor consistency of storage capacity in traditional PQ/PMMA holographic storage photopolymers, this paper introduces a low-viscosity reactive diluent, tripropylene glycol diacrylate (TPGDA), to modify the matrix. Leveraging the viscosity-reducing and double-bond crosslinking properties of TPGDA, the molecular diffusion behavior of the system was regulated. The effects of TPGDA doping ratio, the ratio of photosensitizer PQ to thermal initiator AIBN, and post-curing process on the holographic performance uniformity of the material were systematically investigated. The uniformity was quantitatively evaluated by the variance of diffraction efficiency at different points. Visible light absorption spectra and Fourier-transform infrared (FT-IR) spectroscopy were employed to reveal the modification mechanism from the perspective of functional group distribution. Actual-data read/write tests were conducted using a collinear holographic storage system. The experimental results show that the optimal TPGDA doping concentration is 40 wt%. For the optimized formulation TPGDA:MMA:AIBN:PQ = 8 g:12 g:0.20 g:0.18 g, the modified material achieves an average diffraction efficiency of 76.58%, and the diffraction efficiency variance decreases from 23.49 (pristine matrix) to 1.64, indicating a significant improvement in performance uniformity. Compared with pure PQ/PMMA, the modified material exhibits an approximately 1.95-fold increase in maximum diffraction efficiency, a 2-fold increase in recording rate, and a 1.6–1.75-fold increase in refractive index modulation. FT-IR spectroscopy confirms that TPGDA optimizes the spatial distribution uniformity of C=C and C=O functional groups. In collinear holographic measurements, the bit error rate (BER) variance of the modified sample is reduced by 40% relative to the pristine matrix, achieving homogeneous storage performance across the entire area while maintaining comparable signal-to-noise ratio (SNR) and BER. Additional short-time UV post-curing can further enhance the diffraction efficiency and refractive index modulation, and a thinner substrate can avoid performance fluctuations caused by incomplete thermal curing of thick samples. This study achieves directional optimization of the holographic uniformity of PQ/PMMA through reactive diluent viscosity reduction modification, providing a new strategy for the formulation design and engineering preparation of high-consistency holographic storage photopolymers. Full article

Two tri-carbonyl complexes, [Mn(CO)₃(5cpa)Br] (1) and [Re(CO)₃(5cqn)(OCH₃)] (2), were synthesized, where 5cpa is 5-Cl-2-picolinic acid and 5cqn is 5-Cl-8-Hydroxyquinoline. Their structures were determined using X-ray diffraction techniques. The electronic absorption and IR spectra of the complexes were experimentally measured and theoretically assigned through density functional theory (DFT) calculations. The photo-induced CO release was verified using time-resolved infrared spectroscopy, and the transfer of CO to hemoglobin (Hb) was monitored by UV-vis spectroscopy. The rate of CO release and transfer from Mn complex 1 is significantly faster than that from Re complex 2. Complex 2 exhibits higher cytotoxicity against HeLa cells than complex 1, with IC₅₀ values of 40.1 μM and 10.6 μM for 1 and 2, respectively, which decrease to 16.2 μM and 4.9 μM after photo irradiation. Moreover, 1 exhibited a stronger binding constant (K_b) with human serum albumin (HSA) than 2, with values of 1.6 × 10⁶ and 7.0 × 10⁵ M⁻¹, respectively. The structures of HSA complex adducts revealed that both the resulting [Mn(CO)₃(5cpa)]⁻ and [Re(CO)₃(5cqn)]⁻ group coordinate with the N atom of His146, while four additional dissociated Mn-CO groups were observed to bind to HSA for complex 1. This study provides insights into the stability, possible metabolic pathways, and potential applications of these carbonyl complexes. Full article

Due to water playing a determinative role in the deterioration mechanisms of stone cultural heritage, water-repellent-surface applications have become an important area of research in preservation studies in recent years. In this study, the efficacy of silane-based surface protectants applied to Sille stone, a volcanic rock commonly used in stone cultural heritage buildings in Konya (Türkiye), was evaluated. Firstly, the mineralogical, petrographic, geochemical and physical properties of the rock were determined. Then, the effects of the coating application on the surface were characterized using contact angle measurements, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses. Finally, capillary and Karsten tube water absorption tests confirmed the effectiveness of the silane treatment, with the capillary water absorption coefficient decreasing from 23.30 to 2.24 g/m²s^−0.5 and the Karsten tube water absorption value decreasing from 1.59 to 0.57 g/m²s, demonstrating a substantial improvement in the water-repellent performance of the Sille stone. Full article

Two new nitropyridine amino N-oxide derivatives were synthesized and characterized: 3-N-methylamino-4-nitropyridine N-oxide (NOPCH₃) and [(4-nitropyridine-3-yl)amino]propanoic acid N-oxide (NOPCOOH)1. Their molecular and crystal structures were determined by single-crystal X-ray diffraction, and the intermolecular contact patterns were evaluated using Hirshfeld surface analysis. Vibrational properties were investigated by FT-IR and Raman spectroscopy and interpreted with the support of quantum-chemical calculations (DFT). Electronic absorption was examined by UV–Vis measurements, while photoluminescence spectra and decay profiles were recorded under femtosecond excitation and interpreted conservatively in terms of relaxed excited-state emission. Solid-state ¹³C CP-MAS and ¹H WPMLG NMR spectroscopy provided additional support for the chemical constitution of both derivatives, with ¹H spectra interpreted conservatively because of the limitations inherent to solid-state homonuclear-decoupled measurements. A comparative analysis shows that replacing the methyl substituent (NOPCH₃) with the carboxylic-acid side chain (NOPCOOH) modifies the hydrogen-bonding landscape and the local electronic environment of the NO₂ group, which is reflected in the positions and intensities of selected NO₂-related vibrational bands and in the near-UV electronic transitions. Overall, the combined structural and spectroscopic dataset provides a consistent structure–property picture for both N-oxide derivatives and a basis for further studies of their coordination and photophysical behavior. Full article

The goal of synthesizing more environmentally friendly high-water-absorbing gels (HWAGs) is to reduce the consumption of petroleum resources. We also aimed to make rational use of plant straw. Reed straw (RS) was modified using strong irradiation. Acrylamide (AM) and acrylic acid (AA) were grafted onto the cellulose for graft copolymerization reactions. The cellulose and gels were analyzed using infrared spectroscopy (IR), scanning electron microscopy (SEM), and thermogravimetric (TG) analysis. To reduce the crystallinity of the RS, the optimal irradiation dosage is 96 kGy. Single-factor and orthogonal experiments were conducted to determine the optimal reaction conditions for IRSC-HWAG: the monomer ratio m(AA):m(AM) was 1.5; The material ratio of (m_(AA+Am):m_(IRSC)) was 9:1; The neutralization degree of AA was approximately 90%; The irradiation dose was 5 kGy, with a dose rate of 2.0 kGy/h; the crosslinking agent dosage was 1.2%. The absorption rate of deionized water (Q_d) by the gels was approximately 1160 g/g; the absorption rate of salt water (Q_s) by the gels was approximately 99 g/g. A water-retention experiment demonstrated the IRSC-HWAG’s superior water-retention properties. These properties were compared with those of resins synthesized using pure chemical reagents. This experiment provides valuable reference data for the further development of plant-based water-retention agents. Full article

Heavy and highly viscous oils account for a significant proportion of the world’s hydrocarbon reserves. The development of these reserves in harsh climates is associated with technological risks due to paraffin deposits and equipment corrosion. Ensuring reliable transportation requires operational monitoring of the physical and chemical properties of fluids directly at the wellhead. Traditional laboratory methods such as SARA fractionation and gas chromatography (GC) are time-consuming and can yield to distortions in the sample composition during transportation. Field optical methods, such as an infrared (IR) spectroscopy are complicated by the optical heterogeneity of crude oils due to emulsified water, supramolecular associations of resins, asphaltenes, and paraffins. In this paper, ultrasonic (US) sample preparation for high-viscosity oils is justified as a method for increasing the reliability and information content of field IR spectroscopic analysis by unmasking the diagnostic extrema of absorption bands that are initially distorted by emulsified water, baseline scattering, and radiation scattering from large resin–asphaltene–paraffin aggregates. The technique is based on cavitation-induced destruction of emulsion shells and disaggregation of the structural framework without volume thermal heating. Experimental data obtained from watered high-viscosity oil has shown that 9 min of the US exposure reduces the light scattering index $I_{\mathrm{t}\mathrm{r}\mathrm{s}}$ by 92.83%, bringing the system into a less heterogeneous state. Statistical correlation analysis confirmed that emulsions and aggregates are the main scattering centers, and their destruction correlates directly with the transparency of the medium. Stability of spectral indices $I_{{\mathrm{C}\mathrm{H}}_3/{\mathrm{C}\mathrm{H}}_2}$, $I_{\mathrm{f}\mathrm{o}\mathrm{c}}$ and $I_{\mathrm{C}=\mathrm{O}}$ indicates the absence of chemical degradation or oxidation at the US exposure intensity of 0.12 W/mL, confirming the physical nature of the effect. The proposed method makes it possible to implement automated monitoring of the properties of high-viscosity oil directly at the wellhead, minimizing logistic costs and risks of the sample degradation. The practical significance of the proposed method is to improve the reliability and information content of wellhead monitoring by reducing optical heterogeneity and making diagnostic significant IR absorption extremes more distinguishable for further interpretation. Full article

The objective of this study was to examine the physicochemical properties of maltodextrins derived from starch isolated from red- and purple-fleshed potatoes, in comparison to those obtained from light-fleshed potatoes. The investigation focused on several parameters, including dextrose equivalent (DE), non-carbohydrate components, maltooligosaccharide profile, particle size, surface morphology, water-binding capacity, solubility, rheological properties, structural composition as determined by Fourier transform infrared spectroscopy (FT-IR), and molecular weights. Maltodextrins sourced from the starch of colored potato varieties exhibit superior functional properties, notably nearly 100% solubility and enhanced water absorption capacity. This is attributed to their fine microstructure, which promotes hydration and facilitates the diffusion of water into the interior of the particles, in contrast to maltodextrins derived from the starch of yellow potato varieties. This phenomenon is also influenced by the maltooligosaccharide profile, characterized by a high proportion of low-molecular-weight sugars, lower molecular weights, and polydispersity (Pd), as well as the low SPAN of these maltodextrins. Additionally, maltodextrins derived from the starch of yellow potato varieties (Tajfun and Lord) formed soft gels, whereas those from colored potatoes resulted in hard gels. Full article

Three new heteroleptic copper(I) complexes of the form [Cu(N,N)(XantPhos)]PF₆ were synthesized and characterized, where N,N refers to phenyl-substituted imidazo[4,5-f][1,10]phenanthroline. All complexes were obtained as yellow powders in yields ranging 82–95% and were fully characterized by NMR spectroscopy, FT-IR, and mass spectrometry. The complexes were also redox-optically characterized. Their absorption profiles display a lower-energy metal-to-ligand charge-transfer (MLCT) band at approximately 412 nm. In solution, weak dual emission is observed, combining ligand-centered and MLCT contributions, with oxygen-dependent quenching supporting the presence of triplet character in the latter. Temperature- and solvent-dependent studies reveal thermally coupled emissive states, in which a relaxed ³MLCT state dominates at low temperatures. In the solid state, intense orange-to-red emission arises from restricted molecular motion and stabilized ³MLCT states, with C3 showing the highest efficiency. Additionally, aggregation-induced emission (AIE) is observed in solvent mixtures. These results suggest that remote substitution can influence the excited-state dynamics and aggregation-driven emission in Cu(I) complexes. Full article