Search Results (183)

Carbon quantum dots (CQDs) have attracted intense research interest due to their unique physicochemical properties and broad application potential. CQDs are a new class of ultrasmall fluorescent carbon nanoparticles (<10 nm) that exhibit bright photoluminescence, broad excitation spectra, high quantum yields (QYs), and excellent photostability. Structurally, they consist of graphitic sp²/sp³-hybridized carbon with amorphous or nanocrystalline cores. Unlike conventional semiconductor quantum dots (SQDs), which often contain toxic group II–VI, III–VI, or IV–VI elements, CQDs offer a safer and more environmentally friendly alternative for biomedical and cosmetic applications. This review summarizes recent advances in green-chemistry approaches for CQD synthesis, including top-down, bottom-up, waste-derived, and surface-functionalization methods. Particular attention is given to natural carbon sources, which provide low-cost, sustainable, and eco-friendly routes for scalable production. The optical, electronic, and toxicological properties of CQDs are discussed to clarify their performance and safety profiles. Special emphasis is placed on their emerging roles in wound healing and cosmetic formulations, which remain underexplored despite their promising potential. To our knowledge, this is the first comprehensive review focusing on the current progress, key challenges, and future perspectives of CQDs in beauty and personal care applications. Full article

Multicomponent mixed lanthanide oxide (MMLO) nanoparticles possess considerable potential as multimodal imaging agents because they integrate diverse excellent optical and magnetic properties within a single nanoparticle. Herein, we present triply and quadruply mixed lanthanide oxide nanoparticles, namely, gadolinium (Gd)/dysprosium (Dy)/europium (Eu) oxide (GDEO), Gd/Dy/terbium (Tb) oxide (GDTO), and Gd/Dy/Eu/Tb oxide (GDETO) nanoparticles. Gd³⁺ can strongly induce positive (T₁) contrast in magnetic resonance imaging (MRI), Dy³⁺ and Tb³⁺ can generate negative (T₂) contrast in MRI, and Eu³⁺ and Tb³⁺ emit visible photons that are applicable to fluorescence imaging (FI). All the nanoparticles were grafted with hydrophilic, biocompatible polyacrylic acid (PAA) to enhance colloidal stability and biocompatibility and further grafted with small amounts of an organic photosensitizer, 2,6-pyridinedicarboxylic acid (PDA), to obtain a high absolute fluorescent quantum yield (QY) with an extended fluorescent lifetime (τ). All PAA-MMLO and PAA/PDA-MMLO nanoparticles exhibited nearly monodispersed particle-size distributions with average particle diameters of ~2 nm and displayed considerably higher longitudinal (r₁) and transverse (r₂) water proton spin relaxivities than commercial molecular MRI contrast agents. The PAA/PDA-GDEO, PAA/PDA-GDTO, and PAA/PDA-GDETO nanoparticles exhibited high absolute QYs of 45, 29, and 61%, respectively, and long τ values of 1–2 ms, making them suitable for time-delayed noise-free fluorescence signal detection. These findings confirm the high potential of PAA-MMLO nanoparticles as T₁ and/or T₂ MRI contrast agents and PAA/PDA-MMLO nanoparticles as both T₁ and/or T₂ MRI and FI agents. Full article

Highly accurate quantitative detection of heavy metals is crucial for preventing environmental pollution and safeguarding public health. To address the demand for sensitive and specific detection of Cu²⁺ ions, we have developed carbon dots using a simple hydrothermal process. The synthesized carbon dots are highly stable in aqueous media, environmentally friendly, and exhibit strong blue photoluminescence at 440 nm when excited at 352 nm, with a quantum yield of 5.73%. Additionally, the size distribution of the carbon dots ranges from 2.0 to 20 nm, and they feature excitation-dependent emission. They retain consistent optical properties across a wide pH range and under high ionic strength. The photoluminescent probes are selectively quenched by Cu²⁺ ions, with no interference observed from other metal cations such as Ag⁺, Ca²⁺, Cr³⁺, Fe²⁺, Fe³⁺, Hg²⁺, K⁺, Mg²⁺, Sn²⁺, Pb²⁺, Sr²⁺, and Zn²⁺. The emission of carbon dots exhibits a strong linear correlation with Cu²⁺ concentration in the range of 0–14 μM via a static quenching mechanism, with a detection limit (LOD) of 4.77 μM in water. The proposed carbon dot sensor is low cost and has been successfully tested for detecting Cu²⁺ ions in general water samples collected from rivers in Taiwan. Full article

Fluorescent carbon dots (CDs) were efficiently synthesized by a one-step microwave-assisted method using diphenylamine as a carbon precursor. The obtained CDs exhibit high stability and strong water solubility. Under UV irradiation, these CDs could emit bright green photoluminescence. These synthesized CDs have an average diameter of 1.8 nm (±0.46) and quantum yield (QY) as high as 44.69% using rhodamine-B as a reference. The CDs’ intensity can be quantitatively quenched by Hg²⁺ and Fe³⁺ ions with high sensitivity and low LOD about 9.58 nM and 22.27 nM, respectively, indicating that the CDs sensors can be potentially applied for Hg²⁺ and Fe³⁺ detection in aqueous solutions. Full article

As a core component of emerging quantum-dot display technology, the stability of quantum-dot materials is crucial to determining the performance of quantum-dot photoluminescent diffuser plates. This study successfully synthesized high-stability thick-shell CdZnSeS/CdZnS/ZnS core–shell structured green-alloy quantum dots suitable for photoluminescent diffuser plates, providing an innovative solution for performance breakthroughs in this field. Through orthogonal experimental design, the synthesis parameters of the CdZnSeS alloy core were precisely optimized to achieve an ideal balance in emission wavelength, full width at half maximum (FWHM), and quantum yield (QY). Furthermore, by systematically adjusting ligands and synthesis parameters, a thick-shell CdZnSeS/CdZnS/ZnS core–shell structure was constructed, significantly improving the stability of the quantum dots. Critically, the replacement of the original oleic-acid ligands with tetradecylphosphonic-acid (TDPA) ligands at high temperature doubled the stability of the quantum-dot diffuser plates. Under extreme accelerated-aging conditions such as intense blue light, high temperature, and high humidity, the T90 lifetime of the diffuser plate exceeded 1000 h, and the xy chromaticity coordinate shift was strictly controlled within 1%, fully meeting the stringent commercial requirements. This achievement not only overcomes the stability bottleneck of quantum dots in the application of photoluminescent diffuser plates but also paves the way for their large-scale commercialization, promising to promote the development of display technology toward higher color gamut and longer lifetimes. Full article

Pigeon paramyxovirus type 1 (PPMV-1) poses a significant threat to pigeon farming in China, and understanding its biological characteristics and pathogenicity is critical for vaccine development and disease control. In this study, we characterized a PPMV-1 QY strain, performed full-length genome sequencing, and constructed a phylogenetic tree based on the F gene. Then, the biological properties and the pathogenicity of the QY strain were assessed and evaluated in vitro and in vivo. The results showed that phylogenetic analysis classified the QY strain within subgenotype VI.2.1.1.2.2, the predominant circulating strain in China. The QY strain exhibited a 50% egg infectious dose (EID₅₀) of 10^−6.8/0.1 mL, mean death time (MDT) in chicken embryos of 68.7 ± 2.1 h, and intracerebral pathogenicity index (ICPI) in one-day-old chicks of 1.12, which indicate it is a moderately virulent strain. Animal experiments showed that the QY strain resulted in a mortality rate of 66.7% in healthy pigeons. Necropsy findings included cerebral congestion and swelling, hemorrhagic glandular stomach papillae, tracheal ring hemorrhages, and duodenal congestion and swelling. Histopathological analysis revealed extensive inflammatory infiltration in the lungs and liver, widespread intestinal erosion, and severe necrosis of splenic red pulp cells. In conclusion, the QY strain belongs to subgenotype VI.2.1.1.2.2 and exhibits moderate virulence, causing high mortality and severe pathological lesions in infected pigeons. These findings provide valuable insights into the pathogenicity of PPMV-1 and the specific mutations in the F protein can serve as potential attenuation targets in vaccine development against the emerging subgenotype VI.2.1.1.2.2. Full article

Sediment buildup in storage tanks over extended operation periods may compromise their efficiency. To prevent pollutant deposition in storage tanks and enhance their hydraulic self-cleaning efficiency, this study addressed the unique structural configuration of lateral flow in storage tanks. Conducting numerical simulations to investigate the hydraulic characteristics within storage tanks, an integrated approach combining physical experiments and response surface methodology (RSM) was employed to optimize flow distribution. Key findings reveal that tangential and normal velocity differences lead to flow distribution nonuniformity, exacerbated by increased inflow Froude number (F_r) and reduced relative weir height (h_i). Based on the flow-splitting mechanism, an optimized “combined raised baffle” was proposed. Through single-factor experiments, Plackett–Burman (PB) screening, and RSM experiments, the optimal combination for maximal flow uniformity was determined as h₁ = 1.27, h₂ = 1.23, and h₃ = 1.24, achieving an 87.18% improvement in Q_y compared to the initial design. After optimization, the incoming flow pattern of the inlet channel of the storage pond was improved, and the difference between tangential and normal flow velocity in the flow field was significantly reduced. This research provides a novel approach and methodological paradigm for optimizing storage tanks and other hydraulic structures, demonstrating significant academic and engineering value. Full article

Ziziphi Spinosae Semen (ZSS) has significant medicinal value, and its growing environment critically influences medicinal component accumulation. We analyzed 10 ZSS samples from six major Chinese production areas, identifying 2994 metabolites while exploring tranquilizing constituents and volatiles. Lipids and amino acids were the primary nutrients, while terpenoids were the most abundant class of secondary metabolites. Volatile profiling revealed characteristic sour-fruity-herbaceous flavors, with GS-QY samples showing the highest volatile content. HB-XT and LN-CY samples accumulated the most sedative compounds (jujubosides A/B, spinosin). These findings demonstrate production regions significantly influence ZSS’s medicinal/aromatic profiles, supporting targeted product development. Full article

Oat is a dual-purpose crop valued for both grain and forage. The stay-green (SG) trait, which delays leaf senescence and prolongs photosynthesis, has been shown to increase yield and quality in several crop species, yet its performance across diverse environments in oats remains underexplored. In this study, multi-location field trials were conducted in Ledu, Huangzhong and Haiyan, Qinghai Province, China, to comprehensively evaluate the performance of stay-green oat lines. The traits evaluated included grain yield components, nutritional quality, and seedling establishment traits. A TOPSIS (technique for order preference by similarity to an ideal solution) model, coefficient of variation (CV) and G × E (genotype × environment) visualization were used to assess adaptability, stability, and genotype × environment interactions. On average, the stay-green lines exhibited an 16.00% increase in plot yield and a 22.93% increase in thousand-grain weight compared to controls. Notable improvements were also observed in the starch (7.58% LN_SG in HZ and HY) and protein (3.58%, QY5_SG all the sites) contents, as well as multiple seedling establishment indices, with the seedling vigor indices increasing by more than 50%. Stability analysis further showed that the stay-green lines were stable in spike length, thousand-grain weight, water-soluble carbohydrates, and seed and seedling vigor. TOPSIS analysis identified ‘LN_SG’ as the top-performing and most adaptable genotype across all environments. Overall, stay-green oat lines demonstrated superior performance in grain yield, nutritional quality, and seedling establishment. These findings highlight their potential for field application and their value as parental materials in oat breeding programs enhancing environmental adaptability and stability. Full article

We report the development of highly luminescent, bovine serum albumin (BSA)-stabilized gold–silver bimetallic nanoclusters (Au-AgNCs@BSA) as a novel platform for high-sensitivity, ratiometric intracellular temperature sensing. Precise and non-invasive temperature sensing at the nanoscale is crucial for applications ranging from intracellular thermogenesis monitoring to localized hyperthermia therapies. Traditional luminescent thermometric platforms often suffer from limitations such as high cytotoxicity and low photostability. Here, we synthesized Au-AgNCs@BSA via a one-pot aqueous reaction, achieving significantly enhanced photoluminescence quantum yields (PL QYs, up to 18%) and superior thermal responsiveness compared to monometallic counterparts. The dual-emissive Au-AgNCs@BSA exhibit a linear ratiometric fluorescence response to temperature fluctuations within the physiological range (20–50 °C), enabling accurate and concentration-independent thermometry in live cells. Time-resolved PL and Arrhenius analyses reveal two distinct emissive states and a high thermal activation energy (E_a = 199 meV), indicating strong temperature dependence. Silver doping increases radiative decay rates while maintaining low non-radiative losses, thus amplifying fluorescence intensity and thermal sensitivity. Owing to their small size, excellent photostability, and low cytotoxicity, these nanoclusters were applied to non-invasive intracellular temperature mapping, presenting a promising luminescent nanothermometer for real-time cellular thermogenesis monitoring and advanced bioimaging applications. Full article

Crop disease identification is a pivotal research area in smart agriculture, forming the foundation for disease mapping and targeted prevention strategies. Among the most prevalent global wheat diseases, powdery mildew—caused by fungal infection—poses a significant threat to crop yield and quality, making early and accurate detection crucial for effective management. In this study, we present QY-SE-MResNet34, a deep learning-based classification model that builds upon ResNet34 to perform multi-class classification of wheat leaf images and assess powdery mildew severity at the single-leaf level. The proposed methodology begins with dataset construction following the GBT 17980.22-2000 national standard for powdery mildew severity grading, resulting in a curated collection of 4248 wheat leaf images at the grain-filling stage across six severity levels. To enhance model performance, we integrated transfer learning with ResNet34, leveraging pretrained weights to improve feature extraction and accelerate convergence. Further refinements included embedding a Squeeze-and-Excitation (SE) block to strengthen feature representation while maintaining computational efficiency. The model architecture was also optimized by modifying the first convolutional layer (conv1)—replacing the original 7 × 7 kernel with a 3 × 3 kernel, adjusting the stride to 1, and setting padding to 1—to better capture fine-grained leaf textures and edge features. Subsequently, the optimal training strategy was determined through hyperparameter tuning experiments, and GrabCut-based background processing along with data augmentation were introduced to enhance model robustness. In addition, interpretability techniques such as channel masking and Grad-CAM were employed to visualize the model’s decision-making process. Experimental validation demonstrated that QY-SE-MResNet34 achieved an 89% classification accuracy, outperforming established models such as ResNet50, VGG16, and MobileNetV2 and surpassing the original ResNet34 by 11%. This study delivers a high-performance solution for single-leaf wheat powdery mildew severity assessment, offering practical value for intelligent disease monitoring and early warning systems in precision agriculture. Full article

Tomato waste (TW) was employed as a sustainable source for the synthesis of fluorescent carbon dots (CDs) via a microwave-assisted hydrothermal carbonization (Mw-HTC) method, aiming at its valorization. Several amines were used as nitrogen additives to enhance the fluorescence quantum yield (QY) of CDs, and a set of reaction conditions, including additive/TW mass ratio (0.04–0.32), dwell time (15–60 min), and temperature (200–230 °C) of the HTC process, were scrutinized. The structural analysis of the tomato waste carbon dots (TWCDs) was undertaken by FTIR and ¹H NMR techniques, revealing their most relevant features. In solid state, transmission electron microscopy (TEM) analysis showed the presence of nearly spherical nanoparticles with an average lateral size of 8.1 nm. Likewise, the topographical assessment by atomic force microscopy (AFM) also indicated particles’ heights between 3 and 10 nm. Their photophysical properties, revealed by UV–Vis, steady-state, and time-resolved fluorescence spectroscopies, are fully discussed. Higher photoluminescent quantum yields (up to 0.08) were attained when the biomass residues were mixed with organic aliphatic amines during the Mw-HTC process. Emission tunability is a characteristic feature of these CDs, which display an intensity average fluorescence lifetime of 8 ns. The new TWCDs demonstrated good antioxidant properties by the ABTS radical cation method (75% inhibition at TWCDs’ concentration of 5 mg/mL), which proved to be related to the dwell time used in the CDs synthesis. Moreover, the synthesized TWCDs suppressed the growth of Escherichia coli and Staphylococcus aureus at concentrations higher than 2000 μg/mL, encouraging future antibacterial applications. Full article

Lead halide perovskites (LHPs) have superior luminescent properties, but their toxicity hinders their commercialization, arousing interests in tin halide perovskites as environmentally friendly substitutes for LHPs. Herein, we synthesized a series of two-dimensional tin halide perovskite ODASnBr_4-xI_x (ODA denotes 1,8-octanediammonium, X = 0, 1, 2, 3, 4) microcrystals via an aqueous-phase method. The differences between ODASnI₄ and ODASnBr₄ in luminescent properties and morphological characteristics were systematically discussed for the first time and attributed to light-driven ligand-to-metal charge transfer. The prepared ODASnBr₄ has a PL peak at 567 nm and a PL QY of 99%, and the white light-emitting diodes fabricated with ODASnBr₄ and commercial blue phosphors realized a luminous efficacy of up to 96.27 lm/W, which demonstrated the remarkable potential of ODASnBr₄ microcrystals for high-efficiency white light-emitting diode applications. Full article

A zinc complex bearing a pyrazolone-based azomethine ligand has been synthesized for blue-emitting organic light-emitting diodes (OLEDs). The azomethine ligand H₂L and the complex [ZnL·H₂O] were characterized by IR, 1H NMR, XRD, and TGA/DSC techniques. According to a single-crystal X-ray diffraction analysis, the complex [ZnL·H₂O] has a molecular structure. Its solid-state PL maxima appear to be at 416 nm and emit moderate blue emission with a quantum yield (QY) of 2%, with a dehydrated form of the complex showing greater efficiency with a QY of 55.5%. ZnL-based electroluminescent devices for OLED applications were fabricated. The devices exhibit blue emission with brightness up to 5300 Cd/A. Full article

A binuclear Au-P complex [Au₂(2-bdppmapy)₂](PF₆)₂ (1) was synthesised by the reaction of 2-bdppmapy (N,N′-bis-(diphenylphosphanylmethyl-2-aminopyridine) with AuCN and [Cu(MeCN)₄]PF₆. The solid phase of 1 emitted bright yellow phosphorescence at λ_max = 580 nm under UV excitation (QY = 4.41%, τ = 1.88 μs), which shifted to green (λ_max = 551 nm, QY = 5.73%) after being pressurised under 5 MPa. This colour change was recoverable upon exposure to CH₂Cl₂ vapor. Similar mechanochromic photoluminescence behaviour was observed after grinding the crystals of 1. A filter paper impregnated with 1 demonstrated recyclable write/erase functionality for encrypted information transfer. Full article