Journal of Applied Spectroscopy最新文献

Transmittance and reflectance spectra of a commercial 200-μm-thick polyimide film were recorded in the wavelength range λ = 240–2500 nm. The spectral dependences of the real (n) and imaginary (k) parts of the refractive index of the film were calculated from these spectra using the known exact analytical relations. Absorption spectra and the real and imaginary parts of the dielectric permittivity were also calculated in the indicated wavelength range.

This study focuses on the synthesis of a biocompatible magnetic nanosorbent, modified with β-cyclodextrin (β-CD), using wheat bran (WB) for the adsorption of the drug S-citalopram (S-CIT). Various characterization techniques, including FTIR, SEM, XRD, and VSM, confirmed the successful creation of the wheat bran/Fe₃O₄/β-cyclodextrin (WB/Fe₃O₄/β-CD) nanoadsorbent and its effective interaction with S-CIT. Optimization of parameters such as pH and temperature led to an impressive adsorption efficiency of up to 94%, with a maximum adsorption capacity of 91.74 mg/g under optimal conditions. A calibration curve was established for S-CIT concentrations ranging from 0.2 to 50 μM, yielding a detection limit of 0.050 μM. Thermodynamic and kinetic studies indicated that the adsorption process is exothermic and follows the characteristics of chemisorption. Additionally, it adhered to the Langmuir isotherm model and the pseudo-second-order kinetic model.

This study probes into the structural, thermal, and optical transformations induced in liquid crystalline p-(n-heptyloxy) benzoic acid (7-OBA) by dispersion of dysprosium-doped lithium zinc phosphate nanoparticles [Li₄Zn(PO₄)₂:Dy³⁺] (DLZP-NPs) via the thermal combustion method. X-ray diffraction confirmed the successful incorporation of DLZP-NPs, maintaining the inherent liquid crystalline structure of 7-OBA. Detailed morphological studies using scanning electron microscopy revealed a uniform dispersion of nanoparticles, while energy-dispersive X-ray spectroscopy verified the consistent presence of Dy³⁺ ions throughout the matrix. Fourier-transform infrared spectroscopy identified functional groups within the nanocomposites, with distinct shifts in the stretching regions of C=O, C=C, and C–H bonds, indicative of molecular interactions between the 7-OBA matrix and the nanoparticles. These shifts suggest a reorganization of the molecular environment, facilitated by the synergistic effects of DLZP-NPs. Thermal and phase transition behaviors of the nanocomposites were examined using differential scanning calorimetry and polarized optical microscopy, which highlighted subtle yet significant alterations in phase transition temperatures and liquid crystalline textures. Optical absorption studies revealed a reduction in the energy bandgap of 7-OBA from 3.97 to 3.64 eV with increasing nanoparticle concentrations, emphasizing the potential for bandgap tuning. Spectroscopic ellipsometry further demonstrated a decrease in optical permittivity with increased nanoparticle dispersion, reflecting modifications in electronic polarizability.

Trace impurity elements such as sulfur and phosphorus, along with impurity ions like sulfate and phosphate, have a significant impact on the performance of electrode materials. However, the presence of major elements, including nickel, cobalt, and manganese in ternary materials complicates the determination of these trace components. This study establishes an inductively coupled plasma–optical emission spectrometry (ICP–OES) analytical method for detecting sulfur and phosphorus in ternary materials, as well as indirectly determining the content of sulfate and phosphate through formula conversion. The research investigates the optimization of the microwave digestion acid system and evaluates the interference caused by high concentrations of coexisting elements, such as nickel, cobalt, and manganese, on the determination of phosphorus and sulfur spectral lines. A t-test comparison with ion chromatography revealed no statistically significant difference between the two analytical methods. The results demonstrate that the ICP–OES method provides high precision and accuracy, effectively addressing the challenge of determining sulfur, phosphorus, or sulfate, and phosphate content in ternary materials.

Novel Li₄Zn(PO₄)₂:Tb³⁺ green-light-emitting phosphors were synthesized using the combustion process. A thorough investigation was done on the crystal phase, shape, morphology, and luminescence properties, including decay curves. With the P21(4) space group, the Li₄Zn(PO₄)₂:Tb³⁺ phosphors showed a monoclinic structure. It was calculated that the average crystal size was about 80 nm. Under excitation at 250 nm, a strong green emission peak at 545 nm attributed to ⁵D₄ → ⁷F₅ transition was observed in the present host. It was found that the emission intensity depended on the dopant concentration.

To tackle spectral distortion and spatial detail loss in remote sensing image fusion, this paper proposes a fusion method for panchromatic and multispectral images based on IHS transform and NSST decomposition. However, when the grayscale distribution of the panchromatic image is highly concentrated and has low contrast, the fusion quality declines. To overcome this limitation, an image enhancement technique combining the guided filter (GF) and sigmoid function is introduced in the preprocessing stage of multispectral images. The guided filter effectively preserves edge details, while the sigmoid function enhances contrast by adjusting grayscale values near the center of the distribution. For low-frequency components, a fusion strategy integrating regional energy, regional gradient, and guided filtering (RE–RG–GF) is proposed, ensuring that both local energy and gradient information are retained while maintaining edge details. For high-frequency components, an adaptive pulse-coupled neural network (PA-PCNN) fusion method is applied. Experimental results on two public datasets validate the effectiveness of the proposed approach, showing an increase in standard deviation by 83.49 and 52.69% over the suboptimal results, along with an average gradient increasing by 78.49 and 60.64%, respectively, across seven evaluation metrics.

Topiroxostat (TPX) is a xanthine oxidoreductase inhibitor used in the treatment of gout. For the determination of TPX in bulk and tablets, four simple, specific, precise, sensitive, rapid, and eco-friendly, parallel UV-Visible spectrophotometry methods were developed. Although UV-Visible spectrophotometry estimation work is based on zero-order and first-order derivative spectral transformation, these methods also relied on absorbance, amplitude, and area under the curve of the UV-spectrum. TPX exhibited linearity in the concentration range of 2–12 μg/mL in all four methods, with a correlation coefficient of r² > 0.99. The estimated percentage of drug in the developed methods was found to be in good agreement with what the label claim for the Topimac® tablet formulation. Each method was validated in accordance with the International Council for Harmonisation (ICH) Q2(R2) guidelines. All of these developed methods were linear, accurate, precise, and adequately sensitive, and they were evaluated using one-way ANOVA to assess the statistical comparison of the results. The analyses indicated that the F-value was found to be less than the critical P-value, and there was no identifiable variability in the outcomes. This implied that, for all four methods, there were no significant statistical differences between the results, indicating that they are the best parallel and multimode approaches for the estimation of TPX.

Undoped and a series of Pb²⁺ ion-doped UV-emitting Ca_2-xPb_xB₂O₅ (0.0025 ≤ x ≤ 0.03) phosphors were prepared via the solution combustion method, and their prospective luminescence properties were investigated. The formation of the monoclinic phase of Ca₂B₂O₅ was confirmed by the powder X-ray diffraction result. The Ca_2-xPb_xB₂O₅ (0.0025 ≤ x ≤ 0.03) phosphors’ photoluminescence properties were examined using a spectrofluorometer at room temperature. The broadband peaking at 331 nm is the emission peak of Ca₂B₂O₅:Pb²⁺ (0.01 mol), which is ascribed to the ³P₁→¹S₀ transition. For Ca₂B₂O₅, the relationship between the emission intensity and the Pb²⁺ content was thoroughly examined. Finally, utilizing the excitation band at 273 nm and the emission band at 331 nm, the Stokes shift of the prepared material, Ca₂B₂O₅:Pb²⁺, was determined to be 6418 cm^-1.

The photosynthesis and transpiration rates in 4-, 7-, and 11-day-old Hordeum vulgare L. seedlings exposed to high temperature were studied using IR spectroscopy. The state of the stomata and the real temperature of the primary leaf of these seedlings were assessed to analyze the mechanisms underlying their regulation. It was found that heat treatment (40°C, 3 h, illumination 120 μmol quanta·m^–2·s^–1) did not affect net photosynthesis and stomatal conductivity in rapidly growing 4-day-old H. vulgare seedlings with effective cooling of the leaf due to activation of transpiration. Heat treatment did not change the stomatal conductivity or the transpiration rate in the primary leaf fully formed by the age of 7 days. As a result, the leaf cooled less than in 4-day-old seedlings and net photosynthesis was suppressed. The stomatal conductivity for both water vapor and CO₂ decreased in the aging 11-day-old leaf under heat stress, which caused the suppression of transpiration and photosynthetic activity and significant heating of the leaf. We concluded that the different responses of the stomata and transpiration to heat in H. vulgare seedlings of different ages were aimed at maintaining the most effective balance between cooling the leaf and maintaining the water potential of the plants.

New thermosensitive luminescent materials based on Ba₃La₂(Ge₃O₉)₂ doped with Tb³⁺ or Tb³⁺/Eu³⁺ have been studied. Ba₃La_2–xTb_x(Ge₃O₉)₂ and Ba₃La_1.3Tb_0.7–xEu_x(Ge₃O9)₂ solid solutions were synthesized by the solid-phase method. All samples crystallized in the monoclinic system (space group C2/c, Z = 4) according to the results of x-ray diffraction analysis. The luminescent properties of Ba₃La_2−xTb_x(Ge₃O₉)₂ germanates were studied with excitation by radiation with λ_ex = 377 nm. The spectra consisted of several bands in the range 470–640 nm due to transitions from excited ⁵D₄ to ⁷F_J (J = 3, 4, 5, 6) levels in Tb³⁺ ions. The maximum luminescence intensity was observed for the sample with x = 0.7. Co-doping of phases with Eu³⁺ ions led to the appearance of additional lines in the luminescence spectra in the orange-red region that were associated with the transitions ⁵D₀ → ⁷F_J (J = 0, 1, 2, 3, 4) in europium ions. The color characteristics of a Ba₃La_1.3Tb_0.1Eu_0.6(Ge₃O₉)₂ sample were studied. The temperature dependences of the intensity ratio of the luminescent bands were investigated upon heating from 298 to 473 K. It was shown that heating the phosphor led to an uneven decrease in the intensity of the main emission lines. The maximum values of sensitivities of S_a (1.05%/K) and S_r (1.00%/K) were achieved at T = 298 K.