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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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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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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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Pressure effect on optical and structural properties of ZnMnO thin films grown by pulsed laser deposition
摘要： Zn0.95Mn0.05O thin films were deposited on Si substrate by pulsed laser ablation technique under different oxygen pressure. The structural and optical properties of the films were analyzed as a function of the oxygen gas pressure. The Mn concentration and the substrate temperature of the thin films were kept constant at 5 wt% and 200°C respectively. X-ray diffraction technique (XRD), atomic force spectroscopy (AFM), raman spectroscopy and UV-Vis were employed to characterize the optical properties and the crystalline structure of the films. The diffraction patterns revealed that the Mn0.05Zn0.95O thin films were polycrystalline with the wurtzite hexagonal structure of ZnO and highly oriented in c-axis direction, without any secondary phases. The average energy band gap of the films was evaluated around 3.23-3.56 eV. Raman spectrum showed E2 (low) mode of ZnO structure shifted to red and increased its FWHM.
关键词： Laser Ablation,X-ray Diffraction,UV-Vis Spectroscopy,Atomic Force Microscopy,Raman Spectroscopy
更新于2025-09-16 10:30:52
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Plasmonic Response of Light-Activated, Nano-Gold Doped Polymers
摘要： Incorporation of metallic nanoparticles (NPs) in polymer matrix has been used to enhance and control dissolution and release of drugs, for targeted drug delivery, as antimicrobial agents, localized heat sources, and for unique optoelectronic applications. Gold NPs in particular exhibit a plasmonic response that has been utilized for photothermal energy conversion. Because plasmonic nanoparticles typically exhibit a plasmon resonance frequency similar to the visible light spectrum, they present as good candidates for direct photothermal conversion with enhanced solar thermal efficiency in these wavelengths. In our work, we have incorporated ~3-nm-diameter colloidal gold (Auc) NPs into electrospun polyethylene glycol (PEG) fibers to utilize the nanoparticle plasmonic response for localized heating and melting of the polymer to release medical treatment. Auc and Auc in PEG (PEG+Auc) both exhibited a minimum reflectivity at 522 nm or approximately green wavelengths of light under ultraviolet-visible (UV-Vis) spectroscopy. PEG+Auc ES fibers revealed a blue shift in minimum reflectivity at 504 nm. UV-Vis spectra were used to calculate the theoretical efficiency enhancement of PEG+Auc versus PEG alone, finding an approximate increase of 10 % under broad spectrum white light interrogation, and ~14 % when illuminated with green light. Auc enhanced polymers were ES directly onto resistance temperature detectors and interrogated with green laser light so that temperature change could be recorded. Results showed a maximum increase of 8.9 °C. To further understand how gold nanomaterials effect the complex optical properties of our materials, spectroscopic ellipsometry was used. Using spectroscopic ellipsometry and modeling with CompleteEASE? software, the complex optical constants of our materials were determined. The complex optical constant n (index of refraction) provided us with optical density properties related to light wavelength divided by velocity, and k (extinction coefficient) was used to show the absorptive properties of the materials.
关键词： spectroscopic ellipsometry,photothermal energy conversion,polyethylene glycol,metallic nanoparticles,plasmonic response,UV-Vis spectroscopy,gold NPs,electrospun fibers
更新于2025-09-16 10:30:52
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Plasmonic Oligomers with Tunable Conductive Nanojunctions
摘要： Engineering plasmonic hot-spots is essential for applications of plasmonic nanoparticles. A particularly appealing route is to weld plasmonic nanoparticles together to form more complex structures sustaining plasmons with symmetries targeted to given applications. However, the control of the welding and subsequent hotspot characteristic is still challenging. Herein, we demonstrate an original method that connects gold particles to their neighbors by another metal of choice. We first assemble gold bipyramids in a tip-to-tip configuration, yielding short chains of variable length and grow metallic junctions in a second step. We follow the chain formation and the deposition of the second metal (i.e. silver or palladium) via UV/Vis spectroscopy and we map the plasmonic properties using electron energy loss spectroscopy. The formation of silver bridges leads to a huge redshift of the longitudinal plasmon modes into the mid-infrared region, while the addition of palladium results in a redshift accompanied by significant plasmon damping.
关键词： UV/Vis spectroscopy,Tunable conductive nanojunctions,Palladium,Plasmonic oligomers,Gold bipyramids,Electron Energy Loss Spectroscopy,Silver bridges
更新于2025-09-12 10:27:22
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A Plasmonic Approach to Study Protein Interaction Kinetics through the Dimerization of Functionalized Ag Nanoparticles
摘要： Understanding the kinetics of protein interactions plays a key role in biology with significant implications for the design of analytical methods for disease monitoring and diagnosis in medical care, research and industrial applications. Herein, we introduce a novel plasmonic approach to study the binding kinetics of protein-ligand interactions following the formation of silver nanoparticles (Ag nps) dimers by UV-Vis spectroscopy that can be used as probes for antigen detection and quantification. to illustrate and test the method, the kinetics of the prototype biotin-streptavidin (Biot-StV) pair interaction was studied. controlled aggregates (dimers) of StV functionalized Ag nps were produced by adding stoichiometric quantities of gliadin-specific biotinylated antibodies (IgG-Biot). The dimerization kinetics was studied in a systematic way as a function of Ag NPs size and at different concentrations of IgG-Biot. The kinetics data have shown to be consistent with a complex reaction mechanism in which only the Ag NPs attached to the IgG-Biot located in a specific STV site are able to form dimers. These results help in elucidating a complex reaction mechanism involved in the dimerization kinetics of functionalized Ag nps, which can serve as probes in surface plasmon resonance-based bioassays for the detection and quantification of different biomarkers or analytes of interest.
关键词： biotin-streptavidin interaction,silver nanoparticles,dimerization,protein interaction kinetics,plasmonic approach,surface plasmon resonance,UV-Vis spectroscopy
更新于2025-09-11 14:15:04
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The Effect of In-Vivo Collagen Cross-Linking Procedure on the Material of Intracorneal Ring Segments
摘要： The material of Intracorneal Rings Segments (ICRS) has seemed to be polymerized after the absorption of Riboflavin and UV illumination in laboratory settings. This study aimed to assess the potential impact of in-vivo corneal crosslinking (CXL) on the chemical composition of ICRS. Within this contex, three ICRS samples (S1, S2 and S3) were extracted from patients' cornea, which formerly had undergone CXL treatment. Alterations on the chemical structure of PMMA rings were studied using Ultraviolet-Visible (UV-Vis) spectroscopy and Fourier Transform-Infrared (FT-IR) spectroscopy. An extracted ICRS from a patient who didn’t underwent CXL treatment, was also used as reference (S0). UV-Vis spectroscopy didn't identify any change in the specimens S1, S2 and S3. Nevertheless, FT-IR spectroscopic analysis showed alterations in the spectra of ICRS material of samples S1, S2 and S3, mainly at the 2800 to 3200 cm-1 spectral region [modification in band intensities of CH2 (2850 cm-1 and 2925 cm-1) and CH3 (2950cm-1)]. In conclusion, our results suggest crosslinking reaction in ICRS material after in-vivo CXL treatment. This should be taken into consideration prior to any CXL treatment of post ICRS implanted cornea.
关键词： FT-IR spectroscopy,Corneal crosslinking,INTACS,UV-Vis spectroscopy,Keratoconus
更新于2025-09-10 09:29:36
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Investigations on synthesis, growth and physicochemical properties of semi-organic nonlinear optical crystal: l-arginine sodium nitrate
摘要： Single crystals of l-arginine sodium nitrate semiorganic nonlinear optical crystal were grown by slow evaporation process at room temperature. The single crystal X-ray diffraction study confirms that the unit cell parameters of the grown l-arginine sodium nitrate crystal. Fourier transform infrared spectrum analysis was used to identify the functional groups of the grown crystal. The thermal stability of the l-arginine sodium nitrate was determined using thermogravimetric analysis and differential thermal analysis. The linear optical property of LARSN crystal has been studied using Ultraviolet–visible spectroscopy studies in the wavelength range 200–800 nm. The relative second harmonic efficiency of the l-arginine sodium nitrate compound is found to be 0.49 times that of Potassium Di-hydrogen phosphate. The mechanical property of the grown crystals was determined by Vicker’s micro hardness test and it proved the hard nature of the grown crystal. Dielectric study reveals that both dielectric constant and dielectric loss decreases with increase in frequency.
关键词： thermal analysis,l-arginine sodium nitrate,slow evaporation process,FTIR,nonlinear optical crystal,microhardness,dielectric properties,X-ray diffraction,SHG efficiency,UV–Vis spectroscopy
更新于2025-09-10 09:29:36
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UV-Vis spectroscopy
摘要： UV-Vis reflectance spectroscopy has been widely used as a non-invasive method for the study of cultural heritage materials for several decades. In particular, FORS, introduced in the 1980s, allows to acquire hundreds of reflectance spectra in situ in a short time, contributing to the identification of artist’s materials. More recently, microspectrofluorimetry has also been proposed as a powerful non-invasive method for the identification of dyes and lake pigments that provides high sensitivity and selectivity. In this chapter, the concepts behind these spectroscopic methodologies will be discussed, as well as the instrumentation and measurement modes used. Case studies related with different cultural heritage materials (paintings and manuscripts, textiles, carpets and tapestries, glass, metals, and minerals), which show the usefulness of UV-Vis reflectance spectroscopy and microspectrofluorimetry applied to the study of artworks, will also be presented.
关键词： glass,reflectance,microspectrofluorimetry,textiles,FORS,carpets and tapestries,paintings and manuscripts,minerals,non-invasive,metals,UV-Vis spectroscopy
更新于2025-09-10 09:29:36