Search Results (234)

Interest in gold nanoclusters (AuNCs) has grown significantly in recent decades. AuNCs, with a core size smaller than 2 nm, represent a unique class of functional nanomaterials. Their distinctive properties enable innovative applications across various interdisciplinary fields. Here, we introduce BioGoldNCDB, a freely available, fully annotated, and manually curated database of mainly about AuNCs and related AuNPs. Despite the rapid growth in biomedical applications of gold nanoclusters (AuNCs), the lack of a centralized and structured data resource hinders comparative analysis and rational design. Researchers face challenges in accessing standardized information on AuNCs’ structures, properties, and biological activities, which limits data-driven development in this emerging field. The database provides essential information, including CAS numbers and PubMed IDs, as well as specific details such as biomedical applications, cell lines used in research, particle size, and excitation/emission wavelengths. It currently covers 247 articles from 104 journals. Designed with a user-friendly and intuitive web interface, BioGoldNCDB is accessible on multiple devices, including phones, tablets, and PCs. Users can refine searches with multiple filters, and a help page is available for guidance. While offering quick insights for newcomers, BioGoldNCDB also serves as a valuable resource for researchers across various fields. Full article

In this study, the process of electrolytic–plasma nitrocarburizing (EPNC) of 20-grade steel was investigated using various electrolytes and temperature regimes. At the first stage, optical spectral analysis of plasma emission during EPNC was carried out with spectral registration in the range of 275–850 nm, which allowed the identification of active components (Hα, CN, Fe I, O I lines, etc.) and the calculation of electron density. Additionally, the EPNC process was recorded using a high-speed camera (1500 frames per second), which made it possible to visually evaluate the dynamics of arc and glow discharges under varying electrolyte compositions. At the next stage, the influence of temperature regimes (650 °C, 750 °C, and 850 °C) on the formation of the hardened layer was studied. Using SEM and EDS methods, the morphology, phase zones, and the distribution of chemical elements were determined. Microhardness measurements along the depth and friction tests were carried out. It was found that a temperature of 750 °C provides the best balance between the uniformity of chemical composition, high microhardness (~800 HV), and a minimal coefficient of friction (~0.48). The obtained results confirm the potential of the selected EPNC regime for improving the performance characteristics of 20-grade steel. Full article

A key discovery of this study is the strong correlation (r = 0.96) between excitation and emission maxima across chemically distinct clusteroluminogens. All 157 evaluated peaks fall along a single regression line (Ex = 0.844 Em − 12 nm), a pattern that was not valid for conventional fluorophores. This suggests a general principle of clusteroluminescence. We show that in lignocellulosic materials, peak positions reflect chemical interactions: isolated lignin and cellulose showed short excitation and emission wavelengths, while native wood exhibited longer wavelengths. Fungal or photoinduced degradation led to a further red-shift. These effects are attributed to increased molecular heterogeneity, reducing the effective energy gap within the lignocellulosic complex. We conclude that the spectral position reflects the degree of molecular interaction rather than the chemical structure of individual molecules. It may serve as a novel analytical parameter for assessing purity and degradation in a wide range of polymers. Full article

This study investigates near-infrared (NIR)-induced, Phyto-enhanced, second harmonic generation-mediated photodynamic therapy (Phyto-SHG-PDT) using barium titanate (BT)/rhein/polyethylene glycol 100 (PEG100) and BT/Yemenite “Etrog” leaf extract/PEG100 nanoconjugates. We compare continuous-wave (CW), multi-line Argon-ion laser illumination in the NIR range with high-peak-power femtosecond (fs) 800 nm pulses. Under CW NIR light, BT/rhein nanoconjugates reduced PC3 prostate cancer cell viability by 18% versus non-irradiated controls (p < 0.05), while BT/extract nanoconjugates exhibited 15% dark toxicity. The observed SHG signal matched theoretical predictions and previous CW laser studies. Reactive Oxygen Species (ROS) scavenger 1,3-diphenyl-isobenzofuran (DPBF) showed reduced absorbance at 410 nm upon NIR illumination, indirectly supporting SHG emission at 400 nm from nanoconjugates. Under fs-pulsed laser exposure, pronounced two-photon absorption (TPA) and SHG effects were observed in both nanoconjugate types. Our results demonstrate the effectiveness of BT/rhein nanoconjugates under both laser conditions, while the BT/extract nanoconjugates benefited from high-power pulsed excitation. These results highlight the potential of BT-based Phyto-SHG-PDT nanoconjugates for NIR and blue light applications, leveraging nonlinear optical effects for advanced photochemical cancer therapies. Full article

Lithium (Li)-rich continental brines found in the Lithium Triangle region in South America are a natural resource of paramount importance. In the present research, the analytical performance of laser-induced breakdown spectroscopy (LIBS) technology was assessed for the quantitative analysis of Li in natural brines aimed at enhancing the efficient exploration of salt flats (called salars). Brine samples were collected from different salars located in the Puna plateau (Northwest Argentina) and analyzed by LIBS in the form of solid pressed pellets. Broadband emission spectra (180–900 nm) were recorded and spectrally analyzed by specially designed computational algorithms. The laser-induced plasmas were characterized by calculating the electron density and the temperature. The Li elemental concentrations in the brines were determined through univariate calibration with the Li I emission line at 670.77 nm by using a suitable set of standards with Li concentrations up to 1300 $\mathsf{\mu }$g/g. The calculated limit of detection was LoD = 0.2 ± 0.1 $\mathsf{\mu }$g/g. The Li content in the brines determined with LIBS showed a good agreement (normalized standard deviation: σ_N = 25%) with the concentrations measured with atomic absorption spectroscopy. The results demonstrated the feasibility of the LIBS technique for the quantitative analysis of Li in natural brines, thus contributing to advancing the exploration of Li-rich resources. Full article

A flash smelting furnace operation is based on the exothermic reduction of copper concentrates in the combustion shaft, and these reactions occur at high temperatures (1250–1350 °C), where flame control is fundamental to optimizing copper reduction. Furthermore, inherent physicochemical reactions of the reduction process have been shown to emit spectral lines in the visible-near infrared spectrum (250–900 nm). Thus, an optoelectronic sensor prototype is proposed and developed for flame measurements of an industrial copper concentrate flash smelting furnace. The sensor system is composed of a high-temperature optical fiber probe, which functions as a waveguide to capture the emitted flame radiation and a visible-near infrared spectrometer. From the measured radiation, flame temperature and flame dynamics are analyzed. Flame temperature is estimated using the two-wavelength temperature estimation method, and flame dynamics are defined as variations in the total emissive power, which are studied in the time and frequency domain via the Fourier Transform method. These combustion dynamics are then used to create a flame instability index, which is used to characterize the flame combustion quality. The combination of this index and sensor platform provides a powerful tool to aid in proper flame control. Full article

In this paper, we present the analysis of functional alloy samples containing metals aluminum (Al), copper (Cu), lead (Pb), silicon (Si), tin (Sn), and zinc (Zn) using a Q-switched Nd laser operating at a wavelength of 532 nm with a pulse duration of 5 ns. Nine pelletized alloy samples were prepared, each containing varying chemical concentrations (wt.%) of Al, Cu, Pb, Si, Sn, and Zn—elements commonly used in electrotechnical and thermal functional materials. The laser beam is focused on the target surface, and the resulting emission spectrum is captured within the temperature interval of $9.0\times {10}^3$ to $1.1\times {10}^4$ K using a set of compact Avantes spectrometers. Each spectrometer is equipped with a linear charged-coupled device (CCD) array set at a 2 μs gate delay for spectrum recording. The quantitative analysis was performed using calibration-free laser-induced breakdown spectroscopy (CF-LIBS) under the assumptions of optically thin plasma and self-absorption-free conditions, as well as local thermodynamic equilibrium (LTE). The net normalized integrated intensities of the selected emission lines were utilized for the analysis. The intensities were normalized by dividing the net integrated intensity of each line by that of the aluminum emission line (Al II) at 281.62 nm. The results obtained using CF-LIBS were compared with those from the laser ablation time-of-flight mass spectrometer (LA-TOF-MS), showing good agreement between the two techniques. Furthermore, a random forest technique (RFT) was employed using LIBS spectral data for sample classification. The RFT technique achieves the highest accuracy of ~98.89% using out-of-bag (OOB) estimation for grouping, while a 10-fold cross-validation technique, implemented for comparison, yields a mean accuracy of ~99.12%. The integrated use of LIBS, LA-TOF-MS, and machine learning (e.g., RFT) enables fast, preparation-free analysis and classification of functional metallic materials, highlighting the synergy between quantitative techniques and data-driven methods. Full article

We present a low-cost prototype of a visible and near-infrared (VIS-NIR) remote sensing platform, optimized to detect and characterize natural flaming fire fronts from airborne nighttime light (NTL) observations, and its radiometric calibration. It uses commercially available CMOS sensor cameras and filters with roughly 100 nm bandwidths to effectively discriminate burning biomass from other sources of NTL, a critical ability for wildfire monitoring near populated areas. Our filter choice takes advantage of the strong potassium line emission near 770 nm present in natural flaming. The calibrated cameras operate at 20 ms of exposure time and boast radiance measurements with a sensitivity floor, depending on the filter, in the range 3–5 $\times {10}^{-6}$ W m⁻² sr⁻¹ nm⁻¹ with uncertainties lower than 5% and dynamic ranges near 3000–4000. An additional exposure time with a tenth of the duration is calibrated and extends the dynamic range by a factor of 10. We show images of a spatially resolved fire front from an airborne observation of flaming biomass within this radiance range. Full article

Laser-induced breakdown spectroscopy (LIBS), a rapid and versatile analytical technique, is becoming increasingly widespread within the geoscience community. Suitable for fieldwork analyses using handheld analyzers, the elemental composition of a sample is revealed by generating plasma using a high-energy laser, providing a practical solution to numerous geological challenges, including identifying and discriminating between different mineral phases. This data paper presents over 12,000 reference mineral spectra acquired using a handheld LIBS analyzer (© SciAps), including those of silicates (e.g., beryl, quartz, micas, spodumene, vesuvianite, etc.), carbonates (e.g., dolomite, magnesite, aragonite), phosphates (e.g., amblygonite, apatite, topaz), oxides (e.g., hematite, magnetite, rutile, chromite, wolframite), sulfates (e.g., baryte, gypsum), sulfides (e.g., chalcopyrite, pyrite, pyrrhotite), halides (e.g., fluorite), and native elements (e.g., sulfur and copper). The datasets were collected from 170 pure mineral samples in the form of crystals, powders, and rock specimens, during three research projects: NEXT, Labex Ressources 21, and ARTeMIS. The extensive spectral range covered by the analyzer spectrometers (190–950 nm) allowed for the detection of both major (>1 wt.%) and trace (<1 wt.%) elements, recording a unique spectral signature for each mineral. Mineral spectra can serve as reference data to (i) identify relevant emission lines and spectral ranges for specific minerals, (ii) be compared to unknown LIBS spectra for mineral identification, or (iii) constitute input data for machine learning algorithms. Full article

The present cancer diagnostic techniques and contrast agents suffer drawbacks, adverse effects, and poor compatibility with patients due to health variations. To improve the detection of breast cancer, this work examined and contrasted the prospective applications of pomegranates, chitosan nanoparticles (Cs NPs), and pomegranate-loaded chitosan nanoparticles (PCs NPs) as contrast agents for breast cancer, based on the diffuse reflectance properties at the following laser frequencies: red (670 nm) and near-infrared (700 and 808 nm) spectrum. Herein, a platform for the detection of breast cancer is proposed, offering a promising pathway for cancer detection. PCs NPs with two different pomegranate contents (2 and 5 g/L) were synthesized using the sol–gel method. The cytotoxicity of the developed nanomaterials on human normal (Vero) and breast cancer (MCF7) cell lines were evaluated in the presence of laser irradiation at 670 nm, and the fluorescent effect of the nanoparticles was observed. The chemical structures of the nanomaterials and pomegranate extract were analyzed using FTIR, and they were then further analytically characterized using dynamic light scattering, zeta potential, and field-emission scanning electron microscopy. Results confirmed the structural stability of the nanomaterials. Cytotoxicity measurements revealed that the nanomaterials achieved a selective cytotoxic effect toward tumor cells. Results also showed significant wavelength-dependent changes in diffuse reflectance characteristics between malignant and normal cells. PCs NPs, at a content of 5 g/L, enhanced the reflectance in malignant cells compared to normal cells of more than three folds. These findings indicate the potential of PCs NPs to distinguish between healthy and malignant cells based on the reflection measurements. Full article

This paper presents a space-based limb-imaging spectrometer (LIS) for detecting atmospheric O₂ airglow; it scans the atmosphere with a vertical range of 10–100 km and has a vertical resolution of 2 km. The LIS’s detection performance needs to be examined before launch. A forward radiative transfer model (RTM) of airglow is studied to determine the airglow emission intensity. Spectral and radiation calibration is conducted to obtain the response parameters. Based on the airglow emission intensity, calibration results, and airglow spectral lines, the LIS’s simulated spectra are obtained, and then an optimal estimation inversion method for the LIS is studied. The results show that the LIS’s spectral range is 498.1 nm–802.3 nm, with a spectral resolution of 1.38 nm. Simulation results show that the LIS can detect airglow emission spectral lines, which characterize their dependence on temperature. The digital number response value is 20% to 50% of the saturation value. An inversion error analysis shows that, when the signal-to-noise ratio (SNR) of the LIS is 1000 and the prior temperature error is 10%, the inversion errors are 6.2 and 3 K at 63 and 77 km, respectively. This study shows that the LIS can achieve good SNR detection for airglow. Full article

Background: Polymer-coated mesoporous silica nanoparticles have attracted immense research interest in stimuli-responsive drug delivery systems due to their drug-releasing ability on demand at specific sites in response to external or internal signals. However, the relationships between the coated-copolymer encapsulation and drug delivery performance in the hybrid nanocomposites was rarely reported. Therefore, the main objectives of the present work are to explore the cell uptake, cellular internalization, cytotoxicity, and hemolysis performance of the fluorescent hybrid materials with different polymer-encapsulated amounts. Methods: Using (2-(2-aminoethyl)-6-(dimethylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione)-doped poly[(N-isopropylacrylamide)-co-(acrylic acid)] (PAN) as a shell and bimodal mesoporous silicas (BMMs) as a core, the dual pH- and temperature-responsive mesoporous PAN@M-BMMs with the fluorescent performances were synthesized via a radical polymerization approach. The effects of the PAN-coated thicknesses on their physicochemical properties and structural features were demonstrated via XRD and SAXS patterns, SEM and TEM images, FT-IR spectra, and TG analysis. Their mass fractal (D_m) evolutions were elucidated on the basis of the SAXS patterns and fluorescence spectra. Results: The D_m values increased from 2.74 to 2.87 with an increase of the PAN-coated amount from 17 to 26.5% along with the particle size from 76.1 to 85.6 nm and blue-shifting of their fluorescent emission wavelength from 470 to 444 nm. Meanwhile, the PAN@M-BMMs exhibited a high ibuprofen (IBU) loading capacity (13.8%) and strong dual pH-/temperature-responsive drug-releasing performances (83.1%) at pH 7.4 and 25 °C, as comparison with that (17.9%) at pH 2.0 and 37 °C. The simulated results confirmed that the adsorption energy decreased from −67.18 kJ/mol for pure BMMs to −116.76 kJ/mol for PAN@M-BMMs, indicating the PAN-grafting on the surfaces of the BMMs core was beneficial to improve its IBU-adsorption capacity. Its uptake in the HeLa cell line was performed via microplate readers, confocal microscopy, flow cytometry, and ICP measurement, showing a low cytotoxicity at a concentration up to 100 µg/mL. Specially, P_0.2AN@M-BMMs had a superior cellular uptake and fluorescence properties via the time-dependent uptake experiments, and exhibited the highest silicon content via the cellular internalization analysis, as compared to other carriers. Hemolysis tests confirmed the hemolysis rates below 5%. Conclusions: These demonstrations verified that PAN@M-BMMs should be a promising biomedical application prospect. Full article

Rare-earth doped transparent glass-ceramic waveguides are playing a very crucial role in integrated optics. We fabricated ZnO-HfO₂ hybrid nanocrystals embedded with 70 SiO₂–(30-x) HfO₂–x ZnO (x = 0, 2, 5 and 7 mol %) ternary transparent glass-ceramic waveguides doped with 1 mol % Eu-ions. The formation and size of the nanocrystals evolved with an increase in ZnO concentration in the glass-ceramic waveguides. In this context, key factors of such nanocrystals embedded active glass-ceramic waveguides were optical losses and transparency. A lab-built m-line experimental set-up was used for the characterization of the waveguides. On the other hand, optical gain measurements of the Eu-doped hybrid nanocrystals embedded glass-ceramic waveguides were performed using the variable stripe length method. The optical amplification of the waveguides was investigated on the red emission line (⁵D₀ → ⁷F₂) of Eu-ions pumped by a 532 nm laser in a stripe-like geometry generated by a cylindrical lens. Here, we report, the optical gain in rare-earth activated glass-ceramic waveguides with nanocrystals of varying sizes formed in the waveguides with increasing ZnO concentration. Full article

Azulene-1,3-bis(semicarbazone), 1, and azulene-1,3-bis(thiosemicarbazone), 2, were synthesized by the acid-catalyzed condensation reactions of semicarbazide and thiosemicarbazide, respectively, with azulene-1,3-dicarboxaldehyde in stoichiometric amounts. Compounds 1 and 2 were identified by high-resolution mass spectrometry and characterized by IR, ¹H-NMR, ¹³C-NMR, and UV-vis spectroscopic techniques. Crystal structure determination of azulene-1,3-bis(thiosemicarbazone) shows that the thiosemicarbazone units exhibit a syn-closed conformation, with both arms oriented in the same direction and adopting an E configuration with respect to the imine linkages. Both hydrazones are redox active and showed fluorescence emission at 450 nm upon excitation at 350 nm. The bis-semicarbazone showed no affinity for anions nor for mercury(II) metal cation. Instead, the bis-thiosemicarbazone showed a lower affinity for chloride anions, but enhanced affinity for binding/poisoning Hg²⁺ ions. Both compounds were tested against osteosarcoma MG63 cell lines, exhibiting low antiproliferative activity with comparable IC₅₀ values of 473.08 μM and 472.40 μM for compounds 1 and 2, respectively. Despite this limited antiproliferative effect, further analysis using propidium iodide staining revealed a concentration-dependent decrease in cell viability, with high concentrations inducing a marked reduction in cell number, accompanied by morphological changes characteristic of apoptosis and necrosis. Full article

This study explored a novel method using fructose-derived carbon dots (FCDs) for antitumor therapy in breast cancer (BC), marking a pioneering use of fructose as a carbon source for nanoparticle synthesis. BC, known for its complexity and heterogeneity, was chosen as a model due to its increasing mortality and incidence rates. The FCD synthesis involved the decomposition of fructose through microwave irradiation, followed by purification and characterization using techniques such as transmission electron microscopy, dynamic light scattering, fluorescence spectrophotometry, and Fourier-transform infrared spectroscopy. The FCDs, ranging in size from 2 to 6 nm, presented a hydrodynamic diameter below 2 nm, a spherical morphology, and a crystalline structure. As expected, FCDs were composed by carbon, oxygen, and hydrogen, and exhibited fluorescence with absorption and emission spectra at 405 nm and around 520 nm, respectively. Cell-based assays on breast epithelial and tumor cell lines demonstrated a dose-dependent response, with a decreased viability rate more pronounced in breast tumor cells. In conclusion, FCDs showed significant potential as selective antitumor agents for breast cancer therapy. The comprehensive characterization and cell-based assay evaluations provided valuable insights into the applications of these nanoparticles in breast cancer treatment, highlighting their selective toxicity and impact on tumor cells. Full article