Journal of Applied Spectroscopy最新文献

A stability-indicating greener UV spectrophotometric method was developed and is here reported to quantify felodipine (FDP) in pharmaceutical and spiked human urine samples, with degradation studies and IR spectral analysis of degradation products. The approach involved the preparation of calibration curves using varying concentrations of FDP in 1:1.5 acetic acid (HOAc) and measuring absorbance at 365 nm. Relative standard deviation (RSD) values for the synthetic mixture were less than 5%, and the recovery rate of FDP ranged from 95.65 to 103.1%. The FDP showed considerable degradation under basic conditions, as indicated by a shift in the λ_max, a decrease in recovery at the analytical wavelength, and changes observed in the IR spectrum. The method's robustness and ruggedness were confirmed through variations in experimental conditions and reproducibility tests, with RSD values between 3 and 5%. In the analysis of spiked human urine samples, the method demonstrated high recovery rates of FDP, ranging from 95.50 to 102.30%, with RSD values below 5%, confirming its applicability to analyse physiological samples. The me thod showed excellent linearity over 2.5–100 μg/mL FDP, low limits of detection (0.86 μg/mL), and quantification (2.62 μg/mL), with the regression coefficient (r) of 0.9983, making it suitable for routine analysis of FDP in pharmaceutical formulations and clinical samples. This method provides a reliable approach to quantify FDP, with a proven stability-indicating capability, and applies to both pharmaceutical and physiological contexts. The developed method is environmentally friendly, utilizing less toxic reagents like HOAc, minimizing waste and requiring no sophisticated equipment, making it a sustainable option for routine analysis.

As soil is an important natural resource on the earth's surface, the composition and characterization of soil have a significant impact on agricultural production, the ecological environment, and human health. Traditional soil identification methods need to deal with a large number of samples and complex chemical analysis, which requires a lot of time and effort. In this paper, a method combining laser-induced breakdown spectroscopy (LIBS) and adaptive particle swarm optimization radial basis neural network (APSO–RBF) is proposed to classify and identify soil standard samples from different geographical regions. By selecting the appropriate principal component of LIBS spectral data as input, the computational complexity can be reduced, the redundancy of the original spectral data can be reduced, and the samples can be classified quickly and accurately. For the soil from 10 different regions, the first 6 principal components with the highest contribution rate in principal component analysis were used as the input of APSO–RBF classification model, and the classification accuracy of the test set could reach 98.81%. In comparison with the back propagation (BP) algorithm, back propagation based on adaptive particle swarm optimization (APSO–RBF) algorithm and radial basis function neural network (RBF) algorithm, the powerful classification performance of the model is verified. The results show that LIBS technology greatly improved the accuracy of soil identification in different regions with the help of APSO–RBF model.

Recent innovations in antimicrobial coatings for surgical tools and implants utilize engineered multi-cation oxides combined with nanofibers, nanotubes, and nanosheets, which generate reactive oxygen species to effectively reduce infection risk. This research provides an in-depth examination of lattice dynamics through Raman spectroscopy and ten Raman bands observed from the study indicate the vibrational modes of the orthorhombic structure of V_2–xSb_2xO_5–δ (Sb–V–O, 0.05 ≤ x ≤ 0.08) compounds with the polycrystalline nature of the powder ceramics. The study also assesses the antibacterial properties of Sb–V–O compounds against both human pathogenic gram-positive and gram-negative bacteria. Additionally, the antifungal effectiveness of these compounds is tested against Penicillium spp. and Aspergillus niger. Streptomycin and metronidazole are utilized as positive controls, while dimethyl sulfoxide is used as a negative control. The results highlight the diverse characteristics of the compounds, illustrating their broad-spectrum antimicrobial capabilities and their potential applications in various biomedical and industrial fields.

Nanocrystalline CdWO₄ particles were synthesized via a co-precipitation method using diethylene glycol (DEG) as a capping agent, followed by a hydrothermal technique. Synthesized samples were characterized via X-ray diff raction (XRD), scanning electron microscopy (SEM), dynamic light scattering, Fourier transform infrared spectroscopy, Raman spectroscopy, and UV-visible absorption and photoluminescence analysis. XRD analysis confi rmed the formation of a monoclinic structure in CdWO₄. Uniform homogeneous NanoRect long rod-like morphologies with lengths of <20 to 300 nm were observed via SEM. Hydrodynamic size distribution of the synthesized particles increased with increasing DEG concentration from 20 to 1500 nm. Raman analysis confi rmed the monoclinic structure of the prepared CdWO₄. The width of the strong vibration mode at 897 cm^–1 decreases as the annealing temperature increases, indicating that the crystallite size increases as the crystal evolves with temperature. The band gap of CdWO₄ was found to vary between 2.47 and 4.06 eV from the UV-Vis absorption measurements. Bandgap increases with increasing lattice strain, which is refl ected by the calculated XRD results. UV-visible measurements reveal that the bandgap of CdWO₄ increases with strain in the sample. A broad intense emission peak was observed at 482 nm when the samples were excited at 298 nm.

Predicting the oil content of reinjection water is a crucial challenge in the advancement of digital oilfield technologies. To effectively address this challenge, this study investigates rapid and accurate prediction methods for oil content in reinjection water. A total of 146 samples of reinjection water were collected from a sewage treatment station in the Daqing oilfield. Using UV-visible transmission spectra ranging from 190 to 900 nm, three residual neural networks (ResNet) models with different network structures and several layers were constructed for predicting oil content. Comparative analysis was performed using the joint interval partial least squares method (siPLS). Results showed that the mean absolute errors of the three ResNet models were 1.23, 0.76, and 0.29 mg/L, respectively, all demonstrating lower values than those obtained with the siPLS model, notably, increasing the number of layers in the ResNet model enhanced detection accuracy. Consequently, the ResNet model proves to be suitable for predicting oily sewage content within the 20.0 mg/L range as mandated by industry specifications.

Composites derived from phenolic and urethane polymers were studied using spectral and thermographic methods. Boric acid was used as a modifier. Quantum chemical calculations of fragments simulating the structure of these composites were carried out using the density functional theory method. It has been suggested that the greater heat resistance and reduced flammability of the modified polymer foams result from a chemical reaction of the polymer matrix with the modifier. In this case, the formation of a supramolecular structure of the urethane polymer is attributed to binding through the boroxide group, while the formation of boroxine fragments is characteristic of the phenolic polymer.

The spectra and structure of the near-surface plasma formation and the plume luminosity were experimentally studied with dual-pulse laser action at wavelengths of 1064 and 532 nm on a zirconium target in air as functions of the time interval between laser pulses and their sequence. The dependences of laser plasma temperature on the parameters of the paired laser pulses were established at power densities of q₁₀₆₄ ≈ 3.1∙10⁹ W/cm² and q₅₃₂ ≈ 2.7∙10⁹ W/cm² at laser radiation wavelengths of 1064 and 532 nm, respectively. It was shown that the optimal conditions for excitation of erosion plasma were provided by the action of laser radiation pre-pulses with wavelength of 532 nm and a time interval between laser pulses of 4–5 μs, which was important for increasing the efficiency of laser emission spectral analysis and laser-plasma processing of materials.

The drying conditions (in vacuum or in the air) of nanoparticles consisting of Yb:Yb₂O₃ + 5 mole% ZrO₂ obtained by sedimentation in ethanol have been found to affect the optical quality of the resultant ceramic samples. The studies were carried out using absorption spectroscopy in both the 200–1100 nm and near-infrared regions as well as Raman scattering. Regardless of the drying process for these nanopowders, carbonate species as well as fragments of ethanol and water are formed in the resultant ceramics, leading to complex crystalline defects containing divalent ytterbium ions. These defects lead to a loss of transparency of the ceramics and photoluminescence of trivalent ytterbium excited by laser radiation with wavelength 785 nm. The most significant negative effect of these defects was observed in the ceramics made of nanopowders dried in vacuum.

A comparative analysis of existing endoscopic means of Raman spectroscopy is presented. Their capabilities and characteristic limitations are described. A diagram of a promising endoscopic Raman spectrometer based on an acousto-optical deflector and a composite fiber bundle is proposed.

Changes of the thickness and optical constants of boron oxide films deposited on substrates of sapphire glass, sitall, and polycrystalline massive aluminum were studied directly during heating in air in the temperature range 24–700oC using single-wave and spectral ellipsometry methods. The high hygroscopicity of these films was demonstrated and decreased after their preliminary annealing. It was shown that the film thickness continuously decreased in the studied temperature range due to dehydration processes in the temperature range up to 300°C. The decrease in the film thickness at higher temperatures was explained by slow evaporation of boric acid formed in the film. It was shown that the deposition of a boron oxide film on the aluminum surface did not affect its oxidation rate.