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Self-template construction of honeycomb-like mesoporous YPO4:Ln3+ (Ln?=?Eu, Tb) phosphors with tuneable luminescent properties
摘要： Rare earth (RE)-based phosphors with mesoporous structure that can improve the absorption and utilization of light have attracted much attention recently. Herein, we develop a novel and facile self-template strategy to synthesize honeycomb-like mesoporous YPO4:Ln3+ (Ln = Eu, Tb) phosphors using Y4O(OH)9NO3: Ln3+ as the precursor through a simple H3PO4 etching process. The maximum specific surface area of the mesoporous YPO4:Ln3+ phosphors can reach 406 m2 g?1. The influence of mesoporous structure, crystallinity, and the concentration of rare earth ions on the photoluminescence performance of mesoporous YPO4:Ln3+ phosphors was investigated. The results of fluorescence measurements indicate the mesoporous YPO4:Ln3+ phosphors exhibit better photoluminescence performance after calcination at 900 °C due to the large surface area and high crystallinity. The optimum doped concentrations of Eu3+ and Tb3+ ions are 0.12 and 0.08, respectively, and the concentration quenching occurs among nearest-neighbor ions. This work provide a new sight on preparation of phosphors for white light-emitting diodes lamps.
关键词： Mesostructure,Ultrahigh specific surface area,Temperature dependent luminescence,Self-template strategy
更新于2025-11-14 17:15:25
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Dual-Signal Amplification Strategy for miRNA Sensing with High Sensitivity and Selectivity by Use of Single Au Nanowire Electrodes
摘要： MicroRNAs (miRNAs) have been applied as biomarkers and better detection of their expression profiles plays important roles in early diagnosis of cancers. In this work, a simple dual-signal amplification strategy has been used to construct a novel nanosensor on single Au nanowire electrodes (SAuNWEs) for miRNA-16 detection based on the “signal-on” and “signal-off” features during hybridization/de-hybridization process. The ferrocene-labeled aptamer capture probe (Fc-CP-16) is designed to hybridize with thiolated methylene blue-labeled DNA probe (MB-CP) on SAuNWE to form duplex DNA, and the addition of miRNA-16 can lead to the dissociation of duplex structure due to the highly matched sequences between miRNA-16 and Fc-CP-16. The remaining MB-CP can thus tend to recover its hairpin structure at the presence of Mg2+ through the hybridization of its complementary sequences. During this hybridization/de-hybridization process, the changes of Fc and MB oxidation peaks can be recorded, and there has a linear relationship between the sum of dual-signal changes (ΔI = ΔIMB + |ΔIFc|) and the logarithm of miRNA-16 concentrations, which can be used to detect miRNA-16. Including miRNA extraction, the dual-signal amplification strategy for miRNA sensing assay was carried out about 2 hours for the detection in real samples. This novel nanosensor has small dimension, good selectivity, rapid response and regeneration ability, which can satisfy the need for early cancer marker detection in cells/organelles.
关键词： nanosensors,single Au nanowire electrodes,dual-Signal Amplification Strategy,micro RNA
更新于2025-11-14 17:03:37
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A variable importance criterion for variable selection in near-infrared spectral analysis
摘要： Variable selection is a universal problem in building multivariate calibration models, such as quantitative structure-activity relationship (QSAR) and quantitative relationships between quantity or property and spectral data. Significant improvement in the prediction ability of the models can be achieved by reducing the bias induced by the uninformative variables. A new criterion, named as C, is proposed in this study to evaluate the importance of the variables in a model. The value of C is defined as the average contribution of a variable to the model, which is calculated by the statistics of the models built with different combinations of the variables. In the calculation, a large number of partial least squares (PLS) models are built using a subset of variables selected by randomly re-sampling. Then, a vector of the prediction errors, in terms of root mean squared error of cross validation (RMSECV), and a matrix composed of 1 and 0 indicating the selected and unselected variables can be obtained. If multiple linear regression (MLR) is employed to model the relationship between the RMSECVs and the matrix, the coefficients of the MLR model can be used as a criterion to evaluate the contribution of a variable to the RMSECV. To enhance the efficiency of the method, a multi-step shrinkage strategy was used. Comparison with Monte Carlo-uninformative variables elimination (MC-UVE), randomization test (RT) and competitive adaptive reweighted sampling (CARS) was conducted using three NIR benchmark datasets. The results show that the proposed criterion is effective for selecting the informative variables from the spectra to improve the prediction ability of models.
关键词： multivariate calibration,multi-step strategy,variable selection,near-infrared spectroscopy
更新于2025-09-23 15:23:52
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A new solar hybrid clean fuel-fired distributed energy system with solar thermochemical conversion
摘要： This paper proposes a new solar hybrid clean fuel-fired distributed energy system to increase the system thermodynamic efficiency and save fossil fuel, in which solar energy is upgraded into high-level chemical energy of syngas (H2 and CO) by integrating the solar-driven methanol decomposition based thermochemical conversion. Solar energy, in the form of chemical energy of the generated syngas, is steadily stored and utilized to drive the distributed energy system to generate power, heat and cooling. The double-axis tracking parabolic trough solar collector is deployed to the proposed system to reduce the cosine loss of solar energy. The incorporation of the solar thermochemistry and double-axis solar concentrator technologies leads to a significant improvement in the solar energy utilization efficiency and the off-design performances under varying solar irradiations. With the integration of solar energy utilization and tri-generation, the proposed system achieves a high net solar-to-electric efficiency, 24.66%, and results in high primary energy ratio, 83.86%, exergy efficiency, 38.81%, and carbon emission saving rate, 51.43%. The proposed system is deployed to an office building to study the operation strategies and annual thermo-economy performances, and competitive off-design performances and economy performances are achieved. The research findings open up a new avenue towards the efficient utilization modes of clean fuel and solar energy.
关键词： Distributed energy system,Solar fuel,Solar thermochemistry,Methanol decomposition,Tracking strategy
更新于2025-09-23 15:23:52
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A turn-on fluorescent probe for vitamin C based on the use of a silicon/CoOOH nanoparticle system
摘要： The authors describe a fluorometric method for the turn-on determination of vitamin C (ascorbic acid). The blue fluorescence of silicon nanoparticles (SiNPs; with excitation/emission maxima at 350/450 nm) is found to be quenched by CoOOH nanoparticles (NPs). In the presence of vitamin C, the CoOOH NPs are decomposed by a redox reaction between the diol group of vitamin C and CoOOH NPs. As a result, fluorescence recovers. On the basis of this finding, a fluorometric method was designed for the turn-on detection of vitamin C. Under optimal conditions, the method has a low detection limit (0.47 μM) and a linear response in the 0.5 μM to 20 μM a concentration range. It was successfully applied to the determination of vitamin C in spiked red grape and orange juice, and in vitamin C tablets.
关键词： Fluorescence Bturn-on^ strategy,Cobalt oxyhydroxide nanoparticles,Fluorometry,Stern-Volmer plot,Surface energy transfer,Redox reaction,Inner filter effect,Quenching,Silicon nanoparticles
更新于2025-09-23 15:23:52
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Building a Fluorescent Aptasensor Based on Exonuclease-Assisted Target Recycling Strategy for One-Step Detection of T-2 Toxin
摘要： In this work, a rapid and accurate assay was successfully developed for T-2 toxin detection based on exonuclease-catalyzed target recycling strategy. Upconversion nanoparticles (UCNPs) were conjugated with T-2 aptamer and used as signal probes, while magnetic nanoparticles (MNPs) were conjugated with the complementary DNA of T-2 aptamer (cDNA) and used as capture probes. The results reveled that good linear correlation (R2 = 0.9988) was achieved for T-2 toxin detection over the concentration range of 0.1–100 ng/mL with a detection limit as low as 0.035 ng/mL (S/N = 3). In addition, the reliability of the proposed method was also applied to the determination of T-2 toxin contents in real food samples and the average recoveries ranged from 95.97 to 104.00%. The sensing platform developed in our study demonstrated great potential for simple and sensitive detection of T-2 toxin contents in food samples.
关键词： T-2 toxin,Food safety,Fluorescence,Aptasensor,Target recycling strategy
更新于2025-09-23 15:23:52
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Visible-light-initiated one-pot clean synthesis of nitrone from nitrobenzene and benzyl alcohol over CdS photocatalyst
摘要： The controlled visible-light mediated conversion of nitroaromatics to versatile nitrogen-containing intermediates is of great significance but still remains a challenge. Herein, we report for the first time a facile visible-light-initiated one-pot strategy for clean and efficient synthesis of nitrone from nitrobenzene and benzyl alcohol. It integrates the controlled photocatalytic reduction of nitrobenzene to phenylhydroxylamine by photogenerated electrons with the selective photocatalytic oxidation of benzyl alcohol to benzaldehyde by photoinduced holes over a low-cost CdS photocatalyst with a suitable reduction capability, followed by spontaneous condensation of the as-formed hydroxylamine and aldehyde at ambient pressure and room temperature. Furthermore, by modulating cocatalyst and illumination time, for the conversion of the same reactants, the other two useful nitrogen-containing compounds, imine and secondary amine, were also successfully synthesized. The reaction mechanisms for flexible synthesis of the three target products are proposed.
关键词： One-pot strategy,Clean synthesis,Photocatalysis,Nitrobenzene and benzyl alcohol,Nitrone,Imine and secondary amine
更新于2025-09-23 15:23:52
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Photocatalytic overall water splitting on isolated semiconductor photocatalyst sites in an ordered mesoporous silica matrix: A multiscale strategy
摘要： Photocatalytic overall water splitting (OWS) in a stoichiometric ratio has attracted increasing attention for the realization of a sustainable, environmentally friendly future. However, this reaction exhibits sluggish kinetics due to efficiency limitations of the involved steps, including photon absorption, electron transfer, and the reactions that occur at triple-phase boundary regions. Herein, we report a general multiscale strategy to address this challenge by designing a model composite catalyst with a high loading density of isolated Bi0.5Y0.5VO4 nanocrystals, as building blocks, dispersed in a hexagonally ordered mesoporous silica matrix. In contrast to the well-recognized heterojunction formed between different semiconductors, we show that confined growth favours the formation of isolated quaternary solid-solution photocatalysts (Bi0.5Y0.5VO4), which can further interface with the insulating silica to overcome temperature limitations and exhibit enhanced photon absorption and electrochemical and mass transfer properties due to the transparent periodic porous structure of silica and the as-formed small nanocrystals with high crystallinity and a passivated surface. When the semiconductor photocatalyst is incorporated with the inert silica insulator, this nanoarchitecture does not inhibit the OWS activity but actually delivers a 10-fold higher OWS activity than bulk Bi0.5Y0.5VO4 prepared by the conventional solid-state method.
关键词： Multiscale strategy,Photocatalysis,Isolated solid-solution nanocrystal,Overall water splitting,Mesoporous composite
更新于2025-09-23 15:23:52
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Cooperative Operation of R-SFCL and Online Current Limitation Strategy of GCPVS under Asymmetrical Faults
摘要： Grid-connected photovoltaic (GCPVS) should remain grid-connected and inject specified reactive current in accordance with fault-ride-through (FRT) requirements. To minimize voltage ripples on the DC link voltage and restrict the maximum phase currents, a modified online current limitation strategy (OCLS) is presented in this paper. Transient performance of GCPVS is enhanced as resistive-type superconducting fault current limiter (R-SFCL) is applied under severe asymmetrical faults. By introducing proper resistance selection process, the cooperative operation of OCLS and SFCL is proved to be effective.
关键词： reactive power control,transient performance,superconducting fault current limiters (FCL),online current limitation strategy (OCLS),photovoltaic systems,Fault ride-through (FRT) capability,symmetrical and asymmetrical faults
更新于2025-09-23 15:22:29
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Detection of Multiclass Objects in Optical Remote Sensing Images
摘要： Object detection in complex optical remote sensing images is a challenging problem due to the wide variety of scales, densities, and shapes of object instances on the earth surface. In this letter, we focus on the wide-scale variation problem of multiclass object detection and propose an effective object detection framework in remote sensing images based on YOLOv2. To make the model adaptable to multiscale object detection, we design a network that concatenates feature maps from layers of different depths and adopt a feature introducing strategy based on oriented response dilated convolution. Through this strategy, the performance for small-scale object detection is improved without losing the performance for large-scale object detection. Compared to YOLOv2, the performance of the proposed framework tested in the DOTA (a large-scale data set for object detection in aerial images) data set improves by 4.4% mean average precision without adding extra parameters. The proposed framework achieves real-time detection for 1024 ×1024 image using Titan Xp GPU acceleration.
关键词： Feature introducing strategy,optical remote sensing image,object detection,oriented response (OR) dilated convolution
更新于2025-09-23 15:22:29