- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Photo-Sensitive Pb5S2I6 Crystal Incorporated Polydopamine Biointerface Coated on Nanoporous TiO2 as an Efficient Signal-on Photoelectrochemical Bioassay for Ultrasensitive Detection of Cr(VI) ions
摘要： An ultrasensitive Visible light-triggered photoelectrochemical (PEC) sensor was designed based on ideal photoactive lead sulfoiodide (Pb5S2I6) as low band gap crystal, which hydrothermally synthesized rapidly at low temperature (160°C) in hydrochloride acid media followed by its incorporation into polydopamine as reactive photo-biointerface, through a facile in situ electropolymerization method, coated on nanoporous TiO2 grown by anodization on Ti foil. The structure of as-prepared samples and their photoelectrochemical properties were fully characterized. This unique photo-sensitive Pb5S2I6 catalyst-based PEC bioassay was constructed for the detection of low-abundant Cr(VI) ion in real samples. Applying central composite design, individual and mutual interaction effects were evaluated to obtain optimized solution pH, applied potential and radiant light wavelength as operational factors influencing the PEC efficiency for Cr(VI) detection. At optimal condition, the proposed sensor due to effective suppress in electron–hole recombinations showed a very low detection limit of 3.0 nM, over a broad linear concentration range of 0.01 μM-80 μM in addition to high sensitivity versus 1.9 μA/μM Cr(VI). Proposed PEC sensor displayed high selectivity, reproducibility and stability as well as improved excitation conversion efficiency, which make it highly applicable using solar energy. The potential applicability of the designed sensor was evaluated in water, tomato juice and hair color.
关键词： Photoelectrochemical biosensor,Nanoporous TiO2,Cr(VI) ions,Visible light excitation.,Pb5S2I6 crystal
更新于2025-11-21 11:01:37
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Synthesis, energy transfer and multicolor luminescent property of Eu3+-doped LiCa2Mg2V3O12 phosphors for warm white light-emitting diodes
摘要： In this study, Eu3+-doped LiCa2Mg2V3O12 (LCMVO) phosphors with multicolor luminescent property were prepared by the solid phase reaction. Their structure, morphology and luminescent property were studied systematically by X-ray diffraction, scanning electron microscope and photoluminescence spectra. The LCMVO phosphors showed pure cubic crystal structure with space group (3Ia d ) and irregular spherical morphology. The excitation spectra showed a strong absorption to ultraviolet light. Under the excitation wavelength at 360 nm, they exhibited a cyan emission with a luminescence center at 520 nm. When Eu3+ ions were doped into LCMVO system, the Eu3+ characteristic emissions were also observed and the emission colors were tuned from cyan to orange via adjusting Eu3+ ion concentration. Further, electric dipole-quadrupole interaction and luminescence decay curves were adopted to explain the energy transfer from (VO4)3- to Eu3+. The emission spectra of as-obtained phosphors at different temperature were measured to evaluate their thermal stability. The quantum efficiency values were measured to be 42.5% for LCMVO host and 38.6% for LCMVO: 0.01Eu3+ sample. The final prepared LED lamp showed easeful warm white light with suitable Ra of 89 and CCT of 3847 K, respectively. These results suggest LCMVO phosphors may be applied in near ultraviolet chip-excited white light-emitting diodes.
关键词： energy transfer,multicolor luminescent,self-activated luminescence,excitation and emission spectra,vanadate phosphor,UV-LED
更新于2025-11-20 15:33:11
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Effect of Excitation Wavelength on Optical Performances of Quantum-Dot-Converted Light-Emitting Diode
摘要： Light-emitting diode (LED) combined with quantum dots (QDs) is an important candidate for next-generation high-quality semiconductor devices. However, the effect of the excitation wavelength on their optical performance has not been fully explored. In this study, green and red QDs are applied to LEDs of different excitation wavelengths from 365 to 455 nm. The blue light is recommended for exciting QDs from the perspective of energy utilization. However, QD LEDs excited at 365 nm have unique advantages in eliminating the original peaks from the LED chip. Moreover, the green or red light excited by ultraviolet light has an advantage in colorimetry. Even for the 455 nm LED with the highest QD concentration at 7.0 wt%, the color quality could not compete with the 365 nm LED with the lowest QD concentration at 0.2 wt%. A 117.5% (NTSC1953) color gamut could be obtained by the 365 nm-excited RGB system, which is 32.6% higher than by the 455 nm-excited solution, and this can help expand the color gamut of LED devices. Consequently, this study provides an understanding of the properties of QD-converted LEDs under different wavelength excitations, and offers a general guide to selecting a pumping source for QDs.
关键词： excitation wavelength,colorimetry,quantum dots,light-emitting diode
更新于2025-11-19 16:46:39
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Multifunctional N,S co-doped carbon dots for sensitive probing of temperature, ferric ion, and methotrexate
摘要： In this paper, we have presented a facile method to fabricate nitrogen and sulfur co-doped carbon dots (N,S-CDs) for blood methotrexate (MTX) sensing applications. The N,S-CDs with quantum yield up to 75% were obtained by one-step hydrothermal carbonization, using reduced glutathione and citric acid as the precursors. With this approach, the formation and the surface passivation of N,S-CDs were carried out simultaneously, resulting in intrinsic fluorescence emission. Owing to their pronounced temperature dependence of the fluorescence emission spectra, resultant N,S-CDs can work as versatile nanothermometry devices by taking advantage of the temperature sensitivity of their emission intensity. In addition, the obtained N,S-CDs facilitated high selectivity detection of Fe3+ ions with a detection limit as low as 0.31 μM and a wide linear range from 3.33 to 99.90 μM. More importantly, the added MTX selectively led to the fluorescence quenching of the N,S-CDs. Such fluorescence responses were used for well quantifying MTX in the range of 2.93 to 117.40 μM, and the detection limit was down to 0.95 μM. Due to Binert^ surface, the N,S-CDs well resisted the interferences from various biomolecules and exhibited excellent selectivity. The proposed sensing system was successfully used for the assay of MTX in human plasma. Due to simplicity, sensitivity, selectivity, and low cost, it exhibits great promise as a practical platform for MTX sensing in biological samples.
关键词： Hydrothermal carbonization,Doped carbon dots,Excitation-independent emission,Multifunctional probe,Methotrexate,Surface passivation
更新于2025-11-19 16:46:39
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Graphene oxide/ZnO nanorods/graphene oxide sandwich structure: The origins and mechanisms of photoluminescence
摘要： In this paper, we present the structural and optical properties of Graphene oxide/ZnO nanorods/graphene oxide (GO/ZnO nanorods/GO) nanocomposites prepared via a hydrothermal method on Si (100) substrate. The X-ray diffraction measurements (XRD) confirm that the prepared samples are of hexagonal wurtzite structure with crystallite size around 50-60 nm. It was obvious from scanning electron microscopy (SEM) that by incorporating the ZnO nanorods between the inter-layer of GO confirmed the formation of sandwich-like nanocomposites structure. ZnO nanorods interaction with GO is displayed by the different vibrational frequencies in fourier transform infrared spectroscopy (FTIR). The UV-Vis spectrum reveals the strongest absorption was observed around 370 nm, while calculating optical band gap energy (Eg) of GO/ZnO NRs/GO was found to be 3.15 eV. The photoluminescence (PL) measurements indicates that the ZnO nanorods have a strong visible emission centered at 559 nm attributed to the presence of impurities in the form of oxygen vacancies. After the nanorods were covered with GO layers, the PL intensity of the nanocomposite is quenched and shifted due to charge-transfer process. Consequently, the obtained results may lead to better performance for the optoelectronic applications.
关键词： ZnO nanorods,hydrothermal method,excitation effect,graphene oxide
更新于2025-11-14 15:25:21
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Negative charge enhancement of near-surface nitrogen vacancy centers by multicolor excitation
摘要： Nitrogen vacancy (NV) centers in diamond have been identified over the past few years as promising systems for a variety of applications, ranging from quantum information science to magnetic sensing. This relies on the unique optical and spin properties of the negatively charged NV. Many of these applications require shallow NV centers, i.e., NVs that are close (a few nm) to the diamond surface. In recent years there has been increasing interest in understanding the spin and charge dynamics of NV centers under various illumination conditions, specifically under infrared (IR) excitation, which has been demonstrated to have significant impact on the NV centers’ emission and charge state. Nevertheless, a full understanding of all experimental data is still lacking, with further complications arising from potential differences between the photodynamics of bulk and shallow NVs. Here we suggest a generalized quantitative model for NV center spin- and charge-state dynamics under both green and IR excitation. We experimentally extract the relevant transition rates, providing a comprehensive model which reconciles all existing experimental results in the literature, except for highly nonlinear regimes. Moreover, we identify key differences between the photodynamics of bulk and shallow NVs, and use them to significantly enhance the initialization fidelity of shallow NVs to the useful negatively charged state.
关键词： nitrogen vacancy centers,recombination,shallow NVs,bulk NVs,photodynamics,green excitation,ionization,charge state,IR excitation,diamond
更新于2025-09-23 15:23:52
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Determination of adulterated gasoline using fluorescence emission-excitation matrices and multivariate calibration
摘要： Methanol gasoline, known as a new energy, has a certain degree of damage to automobile. The aim of this work was to identify and quantify the methanol in methanol gasoline using three-dimensional fluorescence spectroscopy technique combined with second order chemometric methods. Parallel factor analysis (PARAFAC) and self-weighted alternating trilinear decomposition (SWATLD) methods were used to analyse artificial samples. However, the obtained results by PARAFAC were not satisfactory. On the other hand, excellent prediction results were obtained when SWATLD model was applied, with recovery rate between 98.7 and 102.8%, and between 97.4 and 101.9% for two and three factor respectively. In order to verify the accuracy of the method, four real samples were predicted using SWATLD model with RMSEP between 0.1 μg/mL and 0.23 μg/mL.
关键词： SWATLD,Methanol gasoline,PARAFAC,Excitation-emission matrix fluorescence
更新于2025-09-23 15:23:52
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A thermo-sensitive fluorescent agent based method for excitation light leakage rejection for fluorescence molecular tomography
摘要： Fluorescence molecular tomography (FMT) is widely used in preclinical oncology research. FMT is the only imaging technique able to provide three-dimensional distribution of fluorescent probes within thick highly scattering media. However, its integration into clinical medicine has been hampered by its low spatial resolution caused by the undetermined and ill-posed nature of its reconstruction algorithm. Another major factor degrading the quality of FMT images is the large backscattered excitation light component leaking through the rejection filters and coinciding with the weak fluorescent signal arising from a low tissue fluorescence concentration. In this paper, we present a new method based on the use of a novel thermo-sensitive fluorescence probe. In fact, the excitation light leakage is accurately estimated from a set of measurements performed at different temperatures and then is corrected for in the tomographic data. The obtained results show a considerable improvement in both spatial resolution and quantitative accuracy of FMT images due to the proper correction of fluorescent signals.
关键词： Excitation Light Leakage,Biomedical Imaging,Fluorescence Molecular Tomography
更新于2025-09-23 15:23:52
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Classification of pre-dyed textile fibers exposed to weathering and photodegradation by non-destructive excitation-emission fluorescence spectroscopy paired with discriminant unfolded-partial least squares
摘要： Undyed textile fabrics such as Acrylic 864, Nylon 361 and Cotton 400 were pre-dyed with Basic Green 4 (BG4), Acid Yellow 17 (AY17) and Direct Blue 1 (DB1) dyes, respectively; and then exposed to two extremely diverse weather conditions in the United States: desert and humid environmental settings in Arizona (AZ) and Florida (FL) respectively, for different time intervals of exposure, which included 0, 3, 6, 9 and 12 months. After every interval of a 3 months period, ten fibers were uniformly sampled from each cloth piece, and fluorescence microscopy was employed to collect two-dimensional excitation and fluorescence spectra (2-D spectra) and three-dimensional (3D) excitation-emission matrices (EEMs). A significant loss of fluorescence intensity was observed upon fiber exposure to outdoor weathering conditions. For a comprehensive statistical data analysis and to be able to discriminate between any two single fibers weathered under different conditions, a multiway calibration algorithm known as discriminant unfolded partial least-squares (DU-PLS) method was applied to the exposed fibers. Results indicate that fluorescence spectroscopy combined with DU-PLS has the ability to appropriately classify and differentiate between any two pairs of dyed cotton or nylon fibers (acrylic in some cases) exposed to dry versus humid weather environments under different time intervals of exposure. These results provide the foundation for future studies towards a non-destructive approach capable to provide information on the weathering history of the fiber.
关键词： Discriminant unfolded partial least squares,Fiber analysis,Photodegradation,Excitation emission matrices,Weathering,Fluorescence spectroscopy
更新于2025-09-23 15:23:52
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Ship detection based on squeeze excitation skip-connection path networks for optical remote sensing images
摘要： Ship detection plays a crucial role in remote sensing image processing, which has drawn great attention in recent years. A novel neural network architecture named squeeze excitation skip-connection path networks (SESPNets) is proposed. A bottom-up path is added to feature pyramid network to improve feature extraction capability, and path-level skip-connection structure is firstly proposed to enhance information flow and reduce parameter redundancy. Also, squeeze excitation module is adopted, which can adaptively recalibrate channel-wise feature responses by adding an extra branch after each shortcut path connection block. The multi-scale fused region of interest (ROI) align is then proposed to obtain more accurate and multi-scale proposals. Finally, soft-non-maximum suppression is utilized to overcome the problem of non-maximum suppression (NMS) in ship detection. As demonstrated in the experiments, it can be seen that the SESPNets model has achieved the state-of-the-art performance, which shows the effectiveness of proposed method.
关键词： Skip-connection path networks,Squeeze excitation,Ship detection,Optical remote sensing images,Deep learning
更新于2025-09-23 15:22:29