This paper deals with the birefringence and order parameter calculation of liquid crystalline (LC) materials like p-n-decyloxy (10OBA) benzoic acid with the incorporation of ZnO nanoparticles (NPs) in different low wt.
A simple, accurate, and precise spectrophotometric method has been developed for the simultaneous determination of pseudoephedrine (PSE) and loratadine (LOR) in bulk and tablets. The method principally exploits the spectral characteristics of the two compounds to affect mathematical manipulation of Beer’s law. The approach in this method enabled the removal of the spectral interference from LOR at the wavelength for the determination of PSE. It was possible to determine pseudoephedrine in the presence of loratadine using two wavelengths (257 and 280 nm). Two calibration curves were established for the analysis. The first was constructed to quantify LOR in the mixture on the basis of its absorbance at 280 nm. The second calibration curve was developed to determine the concentration ratio (CR) between the components at 257 nm. This curve was obtained by plotting the absorbance ratio (AR) against the concentration ratio, defined as CR = [PSE]/[LOR]. The concentration of PSE was calculated using the equation: [PSE] = CREXP × [LOR]. The developed analytical method was statistically validated in accordance with ICH Q2 guidelines and yielded satisfactory results. The assay results, expressed as a percentage of the labeled claim, were found to be 99.97 ± 0.71
A simple and accurate spectrophotometric method was developed for the simultaneous determination of levodopa (LD), carbidopa (CD), and entacapone (ENT) in pharmaceutical formulations. Because of the extensive overlap among their absorption spectra, three chemometric techniques — Artificial Neural Network (ANN), Fuzzy Inference System (FIS), and Adaptive Neuro-Fuzzy Inference System (ANFIS) — were applied to extract quantitative information and resolve spectral interferences. The ANN model, optimized using the Levenberg–Marquardt (LM) algorithm, demonstrated excellent predictive performance, with a coefficient of determination (R2) of 0.9999 for all analytes. The corresponding mean recoveries were 100.25, 99.42, and 99.65
Enhancing the precision of quantitative analysis in calibration-free laser-induced breakdown spectroscopy (CFLIBS) requires a thorough understanding of self-absorption correction techniques. This work introduces blackbody radiation referenced-particle swarm optimization (BRR-PSO) as a self-absorption correction technique. This method compares the measured spectral intensity to blackbody radiation using Particle Swarm Optimization (PSO) to enable quick self-absorption correction. Corrected spectral intensities are obtained by iteratively refining initial values using the PSO optimization technique. Experiments were conducted on alloy samples to verify the efficacy of this method. The results show that as compared to the traditional CF-LIBS methodology, the CF-LIBS with the BRR-PSO method significantly improves the mean relative error (MRE). The MRE decreased from a range of 27.35–43.75
Aquilaria malaccensis, a highly endangered species valued for its fragrant resin, faces significant threats from over-harvesting. This study presents a conservation-oriented method for producing agarwood metabolites using a standardized in vitro callus proliferation protocol and solvent-based FTIR spectral profiling. FTIR analysis identified functional groups in ethanol, methanol, ethyl acetate, acetone, and petroleum ether extracts from both in vivo plants and in vitro callus. Callus extracts exhibited higher intensity and a greater diversity of sesquiterpenoidrelated functional groups. Ethanolic and methanolic extracts from both sources exhibited strong O–H and N–H stretches (3366 and 3400 cm–1), while callus extracts displayed unique peaks such as C=O (1076 cm–1), C=N (1076 cm–1), and C=C=C (1956 cm–1), indicating oxidized and nitrogenous sesquiterpenoids. Ethyl acetate and petroleum ether extracts demonstrated strong C–H stretching and bending vibrations at 2920, 1460, and 778 cm–1, characteristic of long hydrocarbon chains in resinous compounds. Notably, ethyl acetate extracts from callus also indicated nitrogenous and aromatic sesquiterpenoids. Acetone extracts revealed aromatic and aminerelated peaks at 1509, 1400, and 1056 cm–1. These findings highlight the enhanced biosynthetic potential of callus cultures. This approach reduces reliance on wild populations, preserves the product's biochemical integrity, and offers an eco-friendly alternative for pharmaceutical applications.
Triazoxide as a fungicide was experimentally characterized via the help of the FTIR, 1H/13C NMR chemical shifts and UV-Vis spectroscopies. Theoretical modeling was performed using the DFT/B3LYP/6-311++G(df,pd) computational level. The correlation between experimental and computed spectral data was investigated. The conformational analysis was used to obtain the most stable molecular geometry. Computational studies were performed for the two most stable conformational forms (C1 and C2) of triazoxide. The vibrational frequencies and assignments helped to determine the molecular vibrational motions. The effect of electron delocalization within the π-systems of triazoxide on its molecular structure and some vibrational wavenumbers was uncovered. The computational NMR results were analyzed with the GIAO method. The intra-molecular electronic transitions corresponding to the UV-Vis wavelengths were elucidated with simulations of the HOMO/LUMO electron localizations. The electron densities within the occupied/unoccupied molecular orbitals were investigated with the density of states analysis.
We aimed to develop a stability-indicating method for tenofovir disoproxil using first-order derivative UV spectrophotometry to achieve clearer separation of overlapping spectra and ensure reliable detection of the drug along with its degradation products. λmax was recorded at 231 nm, while the first-order derivative wavelength was selected at 244 nm. The method followed Beer–Lambert's law in the concentration range of 35–60 μg/mL with an R2 = 0.9961, and methanol proved to be the most suitable solvent. The method was validated as per ICH Q2 (R2) guidelines, covering linearity, accuracy, precision, LOD, LOQ, and robustness. The results showed minimal variation, with RSD values below 2
This study systematically investigates the effects of configuration interaction (CI) on the photoionization of the 3s shell in argon atoms using relativistic multiconfiguration Dirac–Fock methods. To quantify both CI effects and electron correlations, four distinct computational models were employed: Model A (single-configuration), Model B (restricted configuration with valence excitations up to the 4p orbital), Model C (extended configuration with core–valence excitations up to the 4p orbital), and Model D (extended configuration with core–valence excitation up to the 4d orbital). The results demonstrate that Models C and D, which incorporate single and double excitations from core–valence electrons into the 4p and 4d orbitals, achieve excellent agreement with the experimental cross-sectional data. Notably, the angular asymmetry-parameter β exhibits pronounced energy-dependent behavior, with significant divergence observed between models employing restricted versus extended CI treatments. A detailed analysis was conducted to explore the variations in bound-state and continuum-state electron orbitals across different models, as well as their influence on the photoionization transition matrix elements. This work underscores the critical importance of accurately modeling core–valence electron correlations for reproducing both absolute cross sections and photoelectron angular distributions, particularly near ionization thresholds and the Cooper minimum. These findings provide valuable insights into the fundamental mechanisms governing photoionization processes and highlight the need for advanced theoretical frameworks to enable precise predictions in atomic collision dynamics.
Based on a comparison of experimental and theoretical IR spectra of six brassinosteroids with different configurations of the (22,23)-diol group and the substituent at C-24, criteria are proposed for rapid discrimination between the (22R,23R)- and (22S,23S)-stereoisomers. These criteria are validated by a combined molecular mechanics and CNDO/2 calculation and are found suitable for express screening of synthesized compounds and checking their stereochemical purity without recourse to time-consuming techniques.
A model for forming a range-energy profile (REP) of the visibility zone for an object stationary relative to the system when the duration of the photodetector strobe pulses (exposure time) is significantly shorter than the duration of laser pulses illuminating the objects was proposed. Analytical expressions were derived linking the characteristic distances (points) of the visibility zone REP with the durations of strobe pulses, the uncontrolled technical delay, and the parameters of the laser pulses for different temporal shapes. Numerical calculations confirmed the validity of the obtained analytical expressions. It was established and experimentally confirmed that the REP, taking into account certain patterns, reproduced (displayed) the temporal shape of the laser pulse following from its beginning to its end when moving from the initial point of the visibility zone to the final point.
Constructing heterojunctions is important for improving the photocatalytic performance of materials. In this study, porous Fe2TiO5 was prepared via a sol-gel method, and CuS was grown in situ on its surface through a hydrothermal process, thereby successfully synthesizing CuS/Fe2TiO5 heterojunction composites. The CuS/Fe2TiO5 composites were characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis), and Brunauer–Emmett–Teller (BET) analysis. The results indicated that CuS is uniformly loaded on the surface of Fe2TiO5, with lattice spacings of 0.3550 and 0.2972 nm corresponding to CuS and Fe2TiO5, respectively, and no impurity phases were observed. Heterojunction construction induced distortion of the TiO6 octahedra at the interface, resulting in the emergence of a new absorption peak in the ultraviolet region. Among the samples, the 20 wt.
The physical characteristics of several series of marble samples taken from different regions of Morocco were experimentally determined. These characteristics include optical, elemental, and crystalline properties. The marbles and stones analyzed exhibited a variety of colors, including gray, white, black, yellow, and brown. For reference purposes, three white marble samples from Carrara, Italy; Drama; and Kozani, Greece were studied under the same conditions. A white marble sample from the 18th-century Moulay Ismail Mausoleum in Meknes was also studied under the same conditions. Using optical absorption spectroscopy, we identified bands attributed to ferrous and ferric ions (Fe2+ and Fe3+), which play a fundamental role in marble coloring. Other bands alongside long wavelengths were identified in accordance with crystalline and elemental studies and attributed to carbonates. Electron paramagnetic resonance (EPR) spectra revealed varying concentrations of Mn2+ ions in all the marbles studied. EPR lines attributed to Fe3+ ions distinguished ions resulting from Ca2+ substitution in the calcite lattice from those in iron oxides, clay minerals, and silicates. These identified ions are considered chromogenic elements responsible for the marbles' coloration.
Feasibility is demonstrated for obtaining a dielectric material derived from oxidized porous silicon and titanium oxide by depositing the latter onto porous silicon using a sol-gel method followed by high-temperature oxidation. The resulting dielectric material has an enhanced refractive index, making it promising for creating low-loss integrated optical channel waveguides in bulk microassemblies of electronic circuits with optical interconnects.
A green, stability-indicating UV-spectrophotometric method was developed and validated for the quantification of vanillic acid (VA) in bulk and niosomal formulations within a Quality by Design (QbD) framework. This method utilizes a phosphate buffer (pH 6.8) as an eco-friendly solvent, in accordance with the principles of green analytical chemistry. Key analytical variables, such as sonication time and scanning interval, were optimized using a Design of Experiments (DoE) approach to enhance precision and robustness. The optimized method exhibited a maximum absorbance at 251 nm with excellent linearity over a concentration range of 2–16 μg/mL (R2 = 0.999). Validation according to the ICH Q2(R1) guidelines demonstrated high accuracy (recoveries between 99.65–101.41
A new UV-visible spectrophotometric method using the first derivative has been established for the selective measurement of tyramine in fermented food samples, successfully minimizing interference from histamine. This method has been validated following ICH Q2(R2) standards, showing excellent linearity between 10 and 18 μg/mL, with a limit of detection (LOD) at 0.401 μg/mL and a limit of quantification (LOQ) of 1.217 μg/mL, confirming its sensitivity and dependability for routine testing. An evaluation of the method's environmental impact using AGREE (0.66), BAGI (62.5), and MoGAPI (74) tools revealed a favorable level of greenness, particularly regarding energy efficiency, minimal sample preparation, and safe preservation, despite certain less eco-friendly elements associated with methanol and trichloroacetic acid due to their harmful nature. In conclusion, this method offers a simple, accurate, and reproducible way to measure tyramine in fermented foods, providing important insights into environmental performance and supporting sustainable practices in food analysis.
Hydrogen sulfide (H2S), a recognized toxic gas, has emerged as a key indicator of food spoilage and a potential threat to water safety. Herein, a new fluorescent probe PHZ was designed and synthesized for sensing H2S. When added to PBS (10 mM, pH 7.40) solution, the probe PHZ exhibited a remarkable "turn-on" emission response at 450 nm producing a significant blue fluorescence. The probe PHZ demonstrated excellent selectivity and anti-interference performance in complex environments. It also exhibited good sensitivity for the detection of H2S; however, detection was limited to 0.23 μM. Moreover, the probe PHZ was successfully used for the detection of H2S in environmental water samples and monitoring food spoilage process. In summary, this study highlights the potential of fluorescent probes like PHZ for evaluating environmental water pollution and food freshness.
This work describes the development of a fluorescence sensor based on citrate-reduced gold nanoparticles (GNPs) conjugated with 5-aminofluorescein (5AF) using EDC/NHS chemistry to create GNP@5AF nanoparticles. These nanoparticles were used to detect tryptamine (TRYP) by measuring changes in fluorescence intensity upon incubation with various TRYP concentrations. The sensor showed efficient fluorescence quenching with good linearity and a detection limit of 4 ng TRYP. The sensor's applicability was tested in biological and food samples. In cheese and banana samples, a linear fluorescence enhancement allowed quantitative determination of TRYP within certain concentration ranges (2–10 ng in cheese and 2–16 ng in banana). However, nonlinear responses in other matrices limited the method's broader application. Interference studies indicated that GNP@5AF had a high selectivity for TRYP compared to other amine-containing molecules. Overall, the GNP@5AF sensor offers a simple and sensitive fluorescence-based method for detecting tryptamine, with potential for food safety monitoring. The study suggests that further optimization with selective ligands could improve sensor performance and analytical robustness.
Zinc oxide nanocrystals were synthesized in aqueous solutions at low temperatures. Their surface was coated with a thin film of the electrically conductive polymer poly(3-hexylthiophene) (P3HT) to form hybrid heterostructures. The synthesized nanostructures and hybrid heterostructures formed on their basis were subjected to heat treatment at various temperatures both in air and in vacuum (10–5 Pa). Changes in the optical properties of nanostructures and hybrid heterostructures after heat treatment were studied. The emission band corresponding to 0–0 transitions dominated the photoluminescence spectra of ZnO/P3HT heterostructures annealed in air. The photoluminescence spectra were dominated by the emission band corresponding to defects in ZnO and the polymer of heterostructures annealed in vacuum. Heat treatment of heterostructures based on ZnO nanocrystals in air and vacuum at 100°C resulted in an optimal state of the interface layer between ZnO and P3HT polymer.
The fluorescence of graphene quantum dots (GQDs) at various pH values, temperatures, and ionic strengths and in the absence and presence of peroxidases was investigated. Myeloperoxidase and the hypochlorous acid produced by it were found to cause GQD degradation in biological systems. The rate of substrate oxidation by horseradish peroxidase and myeloperoxidase was shown to decrease in the presence of GQDs. Fluorescence, biodegradation, and the ability to be functionalized make GQDs promising components for theranostic platforms.
The effect of reactor neutron irradiation on Raman scattering spectra and electron spin resonance (ESR) signals of monocrystalline CVD diamond films is studied. The presence of superparamagnetic clusters of spin radicals (ferrons) — regions of magnetic ordering of uncompensated electron spins (g-factor ≈4.65) in an external magnetic field — is revealed for the first time in neutron-irradiated (fluence 3·1018 cm−2) diamonds. It is established that thermal annealing at 400°C for 1 h drastically reduces the ESR signal intensity of spin-radical associates of radiation defects, while approximately doubles the amplitude of the ESR signal from single paramagnetic centers and narrows its linewidth by a factor of ≈4.6. Raman spectroscopy data indicate partial recovery of the crystal structure of diamond due to the annealing of both single radiation defects and nanoscale amorphized regions (ferrons). The types of defects responsible for the formation of ferrons in diamonds as a result of their irradiation with reactor neutrons are discussed.
