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UV-induced macromolecular and optical modifications in gelatin solid films with transition metal chlorides
摘要： Gelatin solid films containing transition metal chlorides (NiCl2·6H2O, CoCl2·6H2O and CrCl3.6H2O) were prepared and UV-irradiated at different exposure times, to study the effect of irradiation on the structural properties at the molecular level, as well as the electronic level, using FT-IR and UV-visible spectroscopies. Results showed that modifications in the molecular and electronic structure due to UV-irradiations were possible even when applying the irradiation treatment to the films in the solid phase. These modifications also differ according to the additive’s type and concentration. The force constant of the CO bond tends to increase, and that for the OH bond tends to decrease, by increasing the irradiation exposure time. The colour difference tends to have higher values for the films with the higher additive concentration and higher exposure times, in the meantime, the brightness tends to increase for Gelatin-NiCl2 and Gelatin-CrCl3 films, and decrease for Gelatin-CoCl2 films. The samples of the Gelatin-NiCl2 group become more yellowish and more greenish by increasing concentrations and exposure times, whereas those of the Gelatin-CoCl2 group tend to become more bluish and more reddish. Moreover, the values of yellowness tend to increase for Gelatin-CoCl2 and Gelatin-NiCl2 films with increasing concentrations and exposure times. Our research concludes that UV-induced modifications in the microstructure and optical properties of the gelatin films are possible in the solid phase due to increasing the crosslinking effects. With the current findings, these films can be used as radiation biosensors.
关键词： UV-vis spectroscopy,Ultraviolet radiation,Transition metals,gelatin,macrostructure,FT-IR
更新于2025-09-19 17:15:36
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Theoretical study of the excited state properties of luminescent phospholes
摘要： TD-DFT calculations with the use of hybrid PBE0 functional and def-TZVP Alrich’s basis set are shown to provide an excellent cost-effective computational approach for the treatment of the excited states of phospholes. The general geometrical changes taking place upon excitation and bearing a common character in the series of considered phospholes have been revealed. It is demonstrated that conjugation of P-heterol with exocyclic aryl fragments makes the main impact on the ground-state (electronic absorption) properties of phospholes. The main structural transformations of the excited states responsible for emission properties are shown to occur mostly inside the P-hetorole ring causing change in bonds ordering upon excitation. The general good agreement between the experiments and the calculations found for the considered systems suggests that the applied theoretical approach can be used as an effective predictive tool for the rational design of luminescent phospholes.
关键词： phospholes,excited states properties,TD-DFT,UV-vis absorption/emission
更新于2025-09-19 17:15:36
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Enhanced UV-Vis-NIR activated photocatalytic activity from Fe <sup>3+</sup> -doped BiOBr:Yb <sup>3+</sup> /Er <sup>3+</sup> upconversion nanoplates: synergistic effect and mechanism insight
摘要： Upconversion (UC) materials are recognized as promising candidates to harvest solar energy for photocatalysis. In this work, a simple strategy for simultaneously enhancing the UC luminescence and photocatalytic efficiency of BiOBr:Yb3+/Er3+ nanoplates through Fe3+ ion doping is reported. Compared to the Fe3+-free sample, the UC emission intensity was significantly enhanced through tailoring of the crystal symmetry by Fe3+ ions. Experiment and DFT calculations reveal that the introduction of Fe3+ ions resulted in the formation of an impurity energy level, extending to the light absorption region. As expected, the Fe3+-doped BiOBr:Yb3+/Er3+ nanoplates exhibit a wide photoresponse from the UV to NIR regions, good stability, and obviously enhanced photocatalytic activities compared with the BiOBr:Yb3+/Er3+ nanoplates in the degradation of RhB. The boosted photocatalytic activity can be attributed to the synergic effect of the efficient utilization of UC luminescence and Fe3+ doping, where Fe3+ doping could improve the light harvesting capacity, enhance the separation efficiency of electron and hole (e?/h+) pairs, and promote the production of highly oxidative species. This work not only provides a promising system for the efficient utilization of solar light, but also offers a feasible guideline for the further design of broad-spectrum active photocatalysts.
关键词： Enhanced UV-Vis-NIR activated photocatalytic activity,mechanism insight,Fe3+-doped BiOBr:Yb3+/Er3+ upconversion nanoplates,synergistic effect
更新于2025-09-19 17:15:36
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uality Evaluation of “Tardivo di Ciaculli” Mandarins in Post-Harvest Processing on an Industrial Scale Using a Portable Vis/NIR Device
摘要： Vis/NIR technology is widely used today to quickly and non-destructively evaluate fruit and vegetable qualities, and many applications have been found since the 1990s. However, no industrial-scale applications can further consolidate the use of non-destructive techniques in post-harvest processing. This study aims to test the possibility of applying vis/NIR technology in a modern citrus-processing plant to assess the damage that the fruits eventually suffer when they are processed on an industrial scale and the evolution of their key quality parameters in a period of 10 days after harvest. The spectral acquisitions were performed using a portable vis/NIR device, which operated in the wavelength range of 600 to 1000 nm. The firmness, pH, and soluble solids content (SSC) were studied for “Tardivo di Ciaculli” mandarin on a total of 1800 fruits. The results show that the vis/NIR device can predict 96% of the total variability of the observed values for fruit firmness; however, the insignificance of the coefficients corresponding to the different sampling points of the processing plant, in the early stages of time, denotes the poor ability of the device to properly detect firmness in the time points closer to the fruit processing. The vis/NIR device explains 93% of the variability of the observed pH and SSC values.
关键词： Mandarin,Processing plant,Post-harvest,Vis/NIR
更新于2025-09-19 17:15:36
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EXPRESS: Use of Visible–Near-Infrared (Vis–NIR) Spectroscopy to Detect Aflatoxin B <sub/>1</sub> on Peanut Kernels
摘要： Current methods for detecting aflatoxin contamination of agricultural and food commodities are generally based on wet chemical analyses, which are time-consuming, destructive to test samples and require skilled personnel to perform, making them impossible for large-scale nondestructive screening and on-site detection. In this study, we utilized visible–near-infrared (Vis–NIR) spectroscopy over the spectral range of 400–2500 nm to detect contamination of commercial, shelled peanut kernels (runner type) with the predominant aflatoxin B1 (AFB1). The artificially contaminated samples were prepared by dropping known amounts of aflatoxin standard dissolved in methanol, onto peanut kernel surface to achieve different contamination levels. The partial least squares discriminant analysis (PLS-DA) models established using the full spectra over different ranges achieved good prediction results. The best overall accuracy of 88.57% and 92.86% were obtained using the full spectra when taking 20 and 100 parts per billion (ppb), respectively, as the classification threshold. The random frog (RF) algorithm was used to find the optimal characteristic wavelengths for identifying the surface AFB1-contamination of peanut kernels. Using the optimal spectral variables determined by the RF algorithm, the simplified RF-PLS-DA classification models were established. The better RF-PLS-DA models attained the overall accuracies of 90.00% and 94.29% with the 20 ppb and 100 ppb thresholds, respectively, which were improved compared to using the full spectral variables. Compared to using the full spectral variables, the employed spectral variables of the simplified RF-PLS-DA models were decreased by at least 94.82%. The present study demonstrated that the Vis–NIR spectroscopic technique combined with appropriate chemometric methods could be useful in identifying AFB1 contamination of peanut kernels.
关键词： Vis–NIR,PLS-DA,peanut kernel,visible–near-infrared spectroscopy,random frog,Aflatoxin,partial least squares discriminant analysis
更新于2025-09-19 17:15:36
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Effect of the degree of inversion on optical properties of spinel ZnFe <sub/>2</sub> O <sub/>4</sub>
摘要： Spinel ferrites (T[M1?xFex]O[MxFe2?x]O4 with 0 ≤ x ≤ 1, where M is a bivalent metal ion and the superscripts denote tetrahedral and octahedral sites) are materials commonly used in electronics due to their outstanding magnetic properties. Thus, the effect of the degree of inversion, x, on these properties is well known. However, its effect on other properties of these materials has rarely been investigated in detail. Since ferrites gained much attention during the last decade as visible light active photocatalysts and photoelectrocatalysts, understanding the effect of the degree of inversion on the optical properties became necessary. Among photocatalytically and photoelectrocatalytically active spinel ferrites, zinc-ferrite (ZnFe2O4, ZFO) is one of the most widely studied materials. In this work, five ZFO samples with degrees of inversion varying from 0.07 to 0.20 were prepared by a solid-state reaction employing different annealing temperatures and subsequent quenching. Raman and UV-Vis-NIR spectra were measured and analyzed together with theoretical results obtained from ab initio calculations. Changes in the UV-Vis-NIR spectra associated with electronic transitions of tetrahedrally and octahedrally coordinated Fe3+ ions are distinguished. However, the optical band gap of the material remains unchanged as the degree of inversion varies. Based on the experimental and theoretical results, a new assignment for the Raman active internal modes and the electronic transitions of ZFO is proposed.
关键词： ab initio calculations,degree of inversion,zinc ferrite,spinel ferrites,optical properties,UV-Vis-NIR spectroscopy,Raman spectroscopy
更新于2025-09-19 17:15:36
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KEV: a free software for calculating the equilibrium composition and determining the equilibrium constants using UV-Vis and potentiometric data
摘要： Present paper reports on an algorithm for calculating the equilibrium composition of several compounds mixture if their total (equilibrium) concentrations and the equilibrium constants of reactions between them are known. The algorithm for determining the unknown equilibrium constants from UV-Vis or potentiometric experimental data using minimizing function (maximal likelihood method) is described. The recommendations on the evaluating of equilibrium constants from experimental results are given. The algorithms described are realized as free-of-charge distributed software/scripts bundle/source code.
关键词： potentiometry,UV-Vis spectroscopy,constant,equilibrium
更新于2025-09-19 17:15:36
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<i>Ab initio</i> quantum-chemical computations of the absorption cross sections of HgX <sub/>2</sub> and HgXY (X, Y = Cl, Br, and I): molecules of interest in the Earth's atmosphere
摘要： The electronic-structure properties of the low-lying electronic states and the absorption cross sections (σ(E)) of mercury halides HgCl2, HgBr2, HgI2, HgBrCl, HgClI, and HgBrI have been determined within the UV-vis spectrum range (170 nm ≤ λphoton ≤ 600 nm) by means of the DKH3-MS-CASPT2/SO-RASSI quantum-chemical methodology (with the ANO-RCC basis set) and a semi-classical computational strategy based on nuclear sampling for simulating the band shapes. Computed band energies show a good agreement with the available experimental data for HgX2 with errors around 0.1–0.2 eV; theoretical and σ(E) are within the same order of magnitude. For the mixed HgXY compounds, the present computed data allow us to interpret previously proposed absorption bands estimated from the spectra of the parent molecules HgX2 and HgY2, measured in methanol solution. The analyses performed on the excited-state electronic structure and its changes around the Franck–Condon region provide a rationale on the singlet–triplet mixing of the absorption bands and the heavy-atom effect of the Hg compounds. Furthermore, the present benchmark of HgX2 and HgXY absorption σ values together with the previous benchmark of the electronic-structure properties of HgBr2 [see S. P. Sitkiewicz, et al., J. Chem. Phys., 2016, 145, 244304] has been helpful to set up a methodological and computational protocol which shall be used for predicting the atmospheric absorption and photolysis properties of several Hg compounds present in the atmospheric cycle of Hg.
关键词： semi-classical approach,quantum-chemical computations,Earth's atmosphere,UV-vis spectrum,spin-orbit coupling,mercury halides,absorption cross sections
更新于2025-09-19 17:15:36
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A study on the fabrication and characterization of dye-sensitized solar cells with Amaranthus red and Lawsonia inermis as sensitizers with maximum absorption of visible light
摘要： Dye-sensitized solar cells (DSSC) were fabricated with dyes extracted from the leaves of Amaranthus red and Lawsonia inermis (Henna). A total of ten dyes were synthesized using solvents like distilled water, acetone and ethanol. UV–Vis spectroscopy was taken for all the dyes prepared. FTIR was taken for the dyes which had maximum absorption in the visible region. FTO substrates coated with nanosized TiO2 sensitized with dyes extracted were the photoanodes. Counter cathode was primed using graphene-coated FTO films. Two solar cells have been made up with the efficient dyes prepared from Amaranthus and Henna. J–V characterization performed for the cells showed that the solar cell fabricated with Amaranthus dye was efficient with the photoconversion efficiency and fill factor of 0.14% and 0.3864, respectively, compared to the cells fabricated using Henna dye whose photoconversion efficiency and fill factor are 0.09% and 0.3851, respectively.
关键词： UV–Vis spectroscopy,Lawsonia inermis,FTIR,Photoconversion efficiency,Dye-sensitized solar cells,Amaranthus red
更新于2025-09-19 17:13:59
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Synthesis and Characterization of Aluminum Nanoparticles Prepared in Vinegar Using a Pulsed Laser Ablation Technique
摘要： The second harmonic wavelength of a neodymium-doped yttrium-aluminum-garnet (Nd-YAG) laser (λ = 532 nm) was used in a pulsed laser ablation technique (PLAL) to synthesize aluminum nanoparticles suspended in white vinegar from an aluminum target. The nanoparticles were characterized by HRTEM and UV-Vis spectrophotometry. They were found to range in size between 2 and 50 nm in diameter, with an average diameter of 12 ± 9 nm. The nanoparticles had a maximum absorption peak at 237 nm and were found to exhibit a core-shell structure with an Al core coated by a thin layer of an amorphous material which could be attributed to amorphous carbon. HRTEM results revealed that the small nanoparticles (<20 nm) had an fcc phase of aluminum crystalline structure, where the larger particles represented alumina (γ-Al2O3) nanoparticles. Such observation suggests that the use of white vinegar as an ablation medium could facilitate the synthesis of aluminum nanoparticles with minimal evidence of the existence of aluminum oxide nanoparticles in the resultant suspension.
关键词： pulsed laser ablation in liquid (PLAL),UV-Vis spectrophotometry,white vinegar,HRTEM,Aluminum nanoparticles
更新于2025-09-19 17:13:59