Luminescence最新文献

This research focuses on the preparation and comprehensive characterization of Li₂Sr.₂Al₂PO₄F₉ phosphors doped with Dy³⁺ ions. The material was synthesized via combustion method utilizing urea as a fuel source. Structural and luminescence properties are investigated through X-ray diffraction and photoluminescence (PL) techniques. The PL excitation spectrum of Li₂Sr.₂Al₂PO₄F₉:Dy³⁺ revealed multiple excitation bands between 300 and 400 nm, attributed to 4f electronic transitions of Dy³⁺ ions. Upon excitation at 348 nm, the PL emission spectrum exhibited characteristic emissions at 478 nm (blue), corresponding to ⁴F₉/₂ → ⁶H₁₅/₂ transition, and at 571 nm (yellow), associated with the ⁴F₉/₂ → ⁶H₁₃/₂ transition of Dy³⁺.

Using several spectroscopic methods, such as fluorescence spectroscopy, Fourier transform infrared (FTIR), UV–visible spectroscopy, thermodynamic investigations, and molecular modeling (MD), is a recent trend in investigating the binding interactions between pharmaceuticals and proteins. The current research examines how nicorandil (NCL) interacts with bovine serum albumin (BSA), a major blood plasma carrier protein, under simulated physiological circumstances (pH 7.4). Fluorescence data and ultraviolet spectra proved that the intrinsic fluorescence of BSA was diminished by NCL through an integration of dynamic and static quenching mechanisms. Studies indicated that NCL binds weakly to BSA with a single binding site (6.35 × 10² M⁻¹ at 298 K), which is consistent with the reported plasma protein binding percentage (approximately 25%). Analysis of the thermodynamic parameters revealed that the NCL-BSA interaction was spontaneous with an enthalpy change (ΔH) of 174.85 kJ mol⁻¹. Hydrophobic forces were the primary binding forces; the entropy change (ΔS) was 639.96 kJ mol⁻¹. Competitive binding experiments proposed that NCL was primarily attached to Site I of BSA's hydrophobic cavity. In addition, synchronous fluorescence spectroscopy, FTIR, and ligand-protein docking studies have deduced the conformational alteration in the BSA secondary structure when it interacts with NCL. Docking results were in accordance with experimental results.

A fast and economical flow injection-fluorometric technique has been employed for the estimation of lurasidone (LUR) in pharmaceutical formulations and biological fluids. LUR natively fluoresces due to the presence of the benzothiazole ring in its chemical composition. The assay relies on detecting the intense native fluorescence of LUR at 398 nm after excitation at 316 nm. Phosphate buffer (pH: 4.5, 10 mM): Acetonitrile (30:70 v/v) was used as the carrier solution, and the flow rate was 0.5 mL min⁻¹. Based on peak area, the calibration graph was linear throughout the range of 30–800 ng mL⁻¹ of LUR with a correlation coefficient (r) of 0.9999. The limit of quantitation was 21.7 ng mL⁻¹, while the limit of detection was 7.16 ng mL⁻¹. The approach was applied to quantify LUR in pharmaceuticals and human plasma. The approach was assessed in accordance with ICH specifications. There were no excipient-related interferences during the application of the analyses.

An ability to effectively detect glyphosate residues in food and the environment on-site remains a challenge. Herein, we developed a ratiometric fluorescent sensing platform based on blue fluorescent carbon dots (B-CDs) and red carbon dots (R-CDs) for rapid, visual, and quantitative detection of glyphosate. Although B-CDs, which were functionalized with abundant amino and hydroxyl groups, caused glyphosate-mediated aggregation-caused quenching (ACQ) via hydrogen bonding effect, R-CDs acted as a stable internal reference. The system could detect glyphosate in one step within 20 s and had a low detection limit of 2.87 μM. During the detection process, the fluorescent color changes from blue to red. On-site detection can be achieved by using the RGB analysis integrated in the smartphone. The sensor had high selectivity to glyphosate, despite the presence of metal ions, biomolecules, and various pesticides. It was successfully applied to detect actual water samples with recovery rates of 81.8%–96.6% (RSD ≤ 11.1%). With its rapid response, smartphone compatibility, and robustness in detecting complex matrices, the proposed sensor has promising potential for the monitoring of glyphosate in agricultural and environmental samples.

This study investigates the thermoluminescence (TL) properties of silver (Ag)-doped magnesium tetraborate (MgB₄O₇, MBO) for radiation dosimetry applications. MBO, known for its tissue-equivalent properties, was synthesized via the solid-state reaction method with Ag doping concentrations of 0.1 wt%, 0.5 wt% and 1.0 wt%. Comprehensive TL experiments were conducted to evaluate key dosimetric properties such as dose response, reusability, fading and heating rate. Additionally, kinetic parameters were derived using the glow curve decomposition (CGCD) and variable heating rate (VHR) methods. The TL glow curves demonstrated that Ag doping significantly enhances the TL signal intensity, particularly at higher doping levels, indicating an impact on trap density and energy release mechanisms. The 1.0 wt% Ag-doped MBO sample exhibited high TL signal intensity and optimal trap stability, making it suitable for applications requiring high sensitivity. Dose–response experiments confirmed the linearity of the TL signal up to high radiation doses (4.6 kGy), while cycling tests validated the material's good reusability and thermal stability. Overall, these findings demonstrate that Ag doping, especially at 1.0 wt%, is an effective approach to enhance the dosimetric performance of MBO, strengthening its potential as a robust candidate for advanced radiation dosimetry systems.

Thin films of DPP were synthesized by thermal deposition technique. The films were treated by exposure to ultraviolet irradiation or thermal annealing. Surface topography of the DPP films was examined by atomic force microscopy technique. DPP films were found to have a very smooth surface after treatment by both ultraviolet irradiation and thermal annealing. The optical absorption analyses were assessed by ultraviolet–visible spectroscopy. The influence of ultraviolet irradiation and thermal annealing on the band gap and Urbach's energy was investigated. The emission characteristics of DPP films were also investigated along with the effects of ultraviolet irradiation and thermal annealing on them. DPP films showed fluorescence emission spectra with emission maxima at around 500 nm. The emission peak was decayed by the effect of ultraviolet irradiation and thermal annealing. The color coordinates of the emission spectra were assessed by a color calculator program, and it revealed that the color coordinates changed as an effect of treatment to the DPP films. The investigated results suggest DPP as a good optoelectronic material that can be applied in sensor applications.

In this work, nanostructured silicon dioxide (SiO₂) thin films were deposited on glass substrates using a DC reactive magnetron sputtering technique. A gaseous mixture of argon and oxygen at different mixing ratios was used to synthesize SiO₂ nanoparticles. Following the extraction of the SiO₂ powder from the glass substrate, we analyzed it to study its structural, morphological, and optical characteristics. X-ray diffraction (XRD) revealed a transition from amorphous to partially crystalline phases as the oxygen ratio increased, indicating enhanced crystallinity under oxygen-rich conditions. Field emission scanning electron microscopy (FE-SEM) showed that particle size decreased with higher oxygen content, suggesting improved oxidation and limited grain growth. Atomic force microscopy (AFM) indicated smoother surfaces at intermediate gas ratios, with the lowest RMS roughness observed at an Ar:O₂ ratio of 70:30. Optical absorbance measurements demonstrated that the film deposited at a 50:50 ratio exhibited the highest absorbance in the visible range (400–600 nm), making it promising for optoelectronic applications. The results confirm that the Ar:O₂ gas ratio plays a critical role in tuning the structural and optical properties of SiO₂ nanostructured thin films.

Tetracycline (TC) and its degradation products, 4-epitetracycline (ETC), anhydrotetracycline (ATC), and 4-epianhydrotetracycline (EATC), are known to contribute to environmental toxicity, yet their molecular interactions with bovine serum albumin (BSA), a model for human serum albumin, remain insufficiently understood. This study explores the binding characteristics of TC and its degradates with BSA using fluorescence spectroscopy and molecular docking. Experimental results revealed fluorescence quenching of BSA upon binding with all four compounds, with ATC and EATC causing the highest quenching. The Stern–Volmer analysis confirmed static quenching and ranked binding affinities as ATC > EATC > ETC ≈ TC, with K_SV values of 9.54 × 10⁵, 6.36 × 10⁵, 1.47 × 10⁵, and 1.79 × 10⁵ M⁻¹, respectively. Spectral shifts indicated conformational changes in BSA upon ligand binding. Docking simulations supported the experimental findings, showing stronger binding of ATC and EATC, attributed to their planar structures, which favor hydrogen bonding and hydrophobic interactions. TC and ETC, due to internal hydrogen bonding and curled conformations, formed weaker interactions. This is the first study to report strong binding of EATC to BSA, highlighting its potential biological relevance and underscoring the need for further in vivo or in vitro validation of its toxicological impact.

Freeform lenses play a critical role in LED packaging due to their beam-shaping capabilities. However, existing packaging designs commonly neglect the Fresnel loss effect at multi-interface boundaries. Addressing this gap, this study establishes a synergistic freeform lens design methodology based on a multi-objective optimization framework, achieving breakthroughs in both high light extraction efficiency and optical quality control. Leveraging the Fresnel equations, a multi-interface energy transmission model is constructed to quantitatively characterize the coupled mechanism of total internal reflection and refraction losses. A triobjective optimization scheme was implemented, targeting flux loss minimization, surface curvature regularization, and illuminance uniformity enhancement. Pareto-optimal solutions were generated via the NSGA-II algorithm, balancing Snell's law compliance, differential geometry constraints, and ray-mapping optimization. Experimental validation demonstrated reduced total flux loss from 8.98 to 4.41 lm, suppressed peak surface curvature from 25.4 to 2.42, and improved illuminance uniformity from 0.84 to 0.91. The proposed methodology provides a systematic approach for designing high-efficiency freeform optics with balanced photometric performance.

The practice of establishing a life prediction model from accelerated life test (ALT) data to assess products' reliability is becoming increasingly popular in industries producing long-life products such as solid-state light-emitting devices (solid-state LEDs). Nevertheless, if ALT fails and results in data missing, retesting will cost a lot of time and affect the production cycle. To address this issue, a life prediction model based on support vector machine (SVM) improved by adaptive genetic algorithm (GA) was proposed in this study. First, adaptive GA-SVM was used for the restoration of failure ALT data, and then the conventional life of the product could be predicted according to the restored data combined with probabilistic statistical methods. Furthermore, in order to verify the prediction performance of the model, the failure ALT of an organic light-emitting diode (OLED) product was taken as an example. The results demonstrate that the data restoration effect of the model is satisfactory, and the relative error between the life predicted according to the restored data and the actual life of the product is merely 2.88%, which proves the effectiveness of the model proposed. Meanwhile, the achievement provides a good remedy for the special situation of failed ALT.