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Facile Synthesis of Luffa Sponge Activated Carbon Fiber Based Carbon Quantum Dots with Green Fluorescence and Their Application in Cr(VI) Determination
摘要： Carbon quantum dots (CQDs) were prepared by a chemical oxidation method using lu?a sponge based activated carbon ?ber as the raw material. The obtained CQDs were well characterized. The ?uorescence quenching e?ect of Cr(VI) ion on CQDs was investigated. The results show that the addition of Cr(VI) changes the intensity of the ultraviolet characteristic absorption peak of CQDs, and causes static quenching of the ?uorescence of CQDs. With the increase in the Cr(VI) concentration, the ?uorescence of CQDs was gradually extinguished linearly.
关键词： Activated carbon ?ber,Lu?a sponge,Cr(VI) determination,Fluorescence quenching,Carbon quantum dots
更新于2025-11-21 11:01:37
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Photoluminescence enhancement <i>via</i> microwave irradiation of carbon quantum dots derived from solvothermal synthesis of <scp>l</scp> -arginine
摘要： Photoluminescence enhancement of carbon quantum dots was achieved via solvothermal synthesis followed by microwave irradiation. Nitrogen and phosphorous doped carbon quantum dots were prepared by solvothermal heating of L-arginine with phosphoric acid for 12 hours followed by microwave irradiation for 3 minutes. The photoluminescence enhancement was nearly two fold after microwave irradiation. The morphology, structure, and surface properties were the same for the solvothermal (CQDs-S) as well as after microwave (CQDs-M) irradiation. Thus, the enhancement is attributed to the decrease of surface defects within CQDs, which led to a decrease in the non-radiative transitions. The CQDs were quenched selectively by Fe3+ ions. The quenching led to the fabrication of the fluorescence probe for ferric ion determination. The CQDs-M had a low detection limit of 4.0 nM, while CQDs-S had a limit of 50 nM. This study gives a tool for enhancing photoluminescence quantum yields, which is highly desired for biosensing and bioimaging applications.
关键词： Photoluminescence enhancement,Fluorescence probe,Solvothermal synthesis,Ferric ion determination,Microwave irradiation,Carbon quantum dots
更新于2025-11-19 16:56:42
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Structure-based design and application of an engineered glutathione transferase for the development of an optical biosensor for pesticides determination
摘要： In the present work, a structure-based design approach was used for the generation of a novel variant of synthetic glutathione transferase (PvGmGSTU) with higher sensitivity towards pesticides. Molecular modelling studies revealed Phe117 as a key residue that contributes to the formation of the hydrophobic binding site (H-site) and modulates the affinity of the enzyme towards xenobiotic compounds. Site-saturation mutagenesis of position Phe117 created a library of PvGmGSTU variants with altered kinetic and binding properties. Screening of the library against twenty-five different pesticides, showed that the mutant enzyme Phe117Ile displays 3-fold higher catalytic efficiency and exhibits increased affinity towards α-endosulfan, compared to the wild-type enzyme. Based on these catalytic features the mutant enzyme Phe117Ile was explored for the development of an optical biosensor for α-endosulfan. The enzyme was entrapped in alkosixylane sol-gel system in the presence of two pH indicators (bromocresol purple and phenol red). The sensing signal was based on the inhibition of the sol-gel entrapped GST, with subsequent decrease of released [H+] by the catalytic reaction, measured by sol–gel entrapped indicators. The assay response at 562 nm was linear in the range pH = 4–7. Linear calibration curves were obtained for α-endosulfan in the range of 0–30 μM. The reproducibility of the assay response, expressed by relative standard deviation, was in the order of 4.1% (N = 28). The method was successfully applied to the determination of α-endosulfan in real water samples without sample preparation steps.
关键词： Glutathione transferase,Biosensor,α-Endosulfan,Pesticides determination,Protein engineering
更新于2025-09-23 15:23:52
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Simultaneous determination of trace amounts of copper and cobalt in high concentration zinc solution using UV–vis spectrometry and Adaboost
摘要： Simultaneous determination of trace ions in zinc metallurgical solution provides effective process information for optimal control in zinc hydrometallurgy. In this paper, Ultraviolet and Visible (UV–vis) spectrometry with the analytical system based on nitroso R salt is applied to simultaneously determine the trace concentrations of copper and cobalt in high and varying concentration zinc sulfate solution. Firstly, fractional differentiation is applied to reduce the overlap between ions and covering of zinc on trace ions. Then, a multi-indexes fusion wavelength selection is utilized to find the optimal combination of variables for the partial least squares model. Next, to reduce the interference caused by competitive reaction and matrix effect of zinc ions, Adaboost creates a group of weak models to analyze trace ion concentration from multiple perspectives. Finally, Adaboost trains the sample weights and model weights of weak models and integrates those weak models into a strong model to predict the trace ion concentration comprehensively. A spectrum dataset containing 72 samples of zinc, copper and cobalt ions mixture solution is prepared for the proposed method. Results show that the proposed method can simultaneously determine the trace concentrations of copper and cobalt in high and varying concentration zinc sulfate solution accurately.
关键词： Adaboost,UV–vis,Simultaneous determination,Trace ion,High concentration zinc solution
更新于2025-09-23 15:23:52
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[IEEE 2018 Conference on Electrotechnology: Processes, Models, Control and Computer Science (EPMCCS) - Kielce, Poland (2018.11.12-2018.11.14)] 2018 Conference on Electrotechnology: Processes, Models, Control and Computer Science (EPMCCS) - Investigation and Determination of Efficiency of the Waste Heat Recovery System Using Peltier Modules
摘要： High efficiency technology of waste heat energy utilization would change the face of the energy market. Due to the fact that the energy system and transport are based on fossil fuels, there is a huge potential for its efficient use. Despite the fact that the technology of Peltier semiconductor modules has been known for many years, there are no solutions that might be commonly disseminated. There is also a deficit of available sources that in a transparent, coherent and synthetic way could provide guidelines for the constructors of such devices, and show how much energy they can generate and what efficiency they have. Moreover, the Peltier modules available on the market are burdened with many stereotypes. When trying to use this technology, it should be remembered that in addition to the Peltier phenomenon, the module's operation is based on four other physical phenomena: two of them have a negative impact and they determine the practically obtained parameters of the Peltier module. These are: Joule effect and heat conduction phenomenon. The other two phenomena: Seebeck and Thomson ones, play slightly smaller roles. The aim of the authors was to investigate the self-made model of a thermoelectric generator TEG, constructed using Peltier modules. The paper presents the results of measurements and the method of determining the electrical efficiency of this model. Additionally, a temperature range was determined at that such recovery has a measurable utilitarian aspect and economic sense. The limitations of semiconductor technology of Peltier cells have been given, and design guidelines at construction process of such systems to optimize their efficiency are presented.
关键词： Seebeck effect,thermoelectric generator TEG,determination of efficiency,Peltier module
更新于2025-09-23 15:23:52
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Low-rank Bayesian tensor factorization for hyperspectral image denoising
摘要： In this paper, we present a low-rank Bayesian tensor factorization approach for hyperspectral image (HSI) denoising problem, where zero-mean white and homogeneous Gaussian additive noise is removed from a given HSI. The approach is based on two intrinsic properties underlying a HSI, i.e., the global correlation along spectrum (GCS) and nonlocal self-similarity across space (NSS). We first adaptively construct the patch-based tensor representation for the HSI to extract the NSS knowledge while preserving the property of GCS. Then, we employ the low rank property in this representation to design a hierarchical probabilistic model based on Bayesian tensor factorization to capture the inherent spatial-spectral correlation of HSI, which can be effectively solved under the variational Bayesian framework. Furthermore, through incorporating these two procedures in an iterative manner, we build an effective HSI denoising model to recover HSI from its corruption. This leads to a state-of-the-art denoising performance, consistently surpassing recently published leading HSI denoising methods in terms of both comprehensive quantitative assessments and subjective visual quality.
关键词： Hyperspectral image denoising,Global correlation along spectrum,Full Bayesian CP factorization,Nonlocal self-similarity,Variational Bayesian inference,Tensor rank auto determination
更新于2025-09-23 15:23:52
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Characteristics of Orbit Determination with Short-Arc Observation by an Optical Tracking Network, OWL-Net
摘要： An optical tracking network, the Optical Wide-field patroL Network (OWL-Net), has been developed to maintain the orbital ephemeris of 11 domestic low Earth orbit satellites. The schedule overlapped events were occurred in the scheduling of the OWL-Net with reduction of the optical observation chances. A short-arc observation strategy for the OWL-Net was tested to reduce schedule overlapped events with the optical observation simulation and the orbit determination. In the full-scale optical observation simulation from January 2014 to December 2016, the most frequent overlapped events were occurred 127, 132, and 116 times in the 4th, 34th, and 18th weeks of 2014, 2015, and 2016, respectively. The average number of overlapped event for three years was over 10% for the whole observation chances of five stations. Consequently, the short-arc observation strategy reduced the schedule overlapped events for every observation target of the OWL-Net. In case of the 5 s and 10 s cases, the most schedule overlapped events were removed. The test results of the orbit determination results show that the most maximum orbit prediction errors after seven days are maintained at <10 km in the in-track direction for the short-arc observation simulations. The results demonstrate that the short-arc optical observation strategy is more optimal to maintaining the accuracy of orbital ephemeris with more observation chances.
关键词： short-arc observation,optical tracking network,OWL-Net,orbit determination,LEO satellites
更新于2025-09-23 15:23:52
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A Method for Determining the Length of FBG Sensors Accurately
摘要： In this study we propose a method for estimating the length of single mode fibre Bragg grating type sensors with high accuracy. Our method is based on calculating the maximum oscillation frequency of the side-lobes of the FBG reflection spectrum. We show that this frequency is independent of the stress field to which the sensor is subjected, and is dependent on the length of the sensor. This method can be used to characterise the gauge length of already installed FBG sensors so that they can provide useful data for engineering models of structural integrity. All the analyses are based on the approximated transfer matrix model, which is a newly developed numerical method for analysis of the FBG reflection spectrum under various stress fields.
关键词： Fiber Bragg grating,structural integrity,reflection spectrum,FBG,length determination
更新于2025-09-23 15:22:29
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[IEEE 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace) - Rome, Italy (2018.6.20-2018.6.22)] 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace) - Characterization and Testing of a High-Resolution Time-of-Flight Camera for Autonomous Navigation
摘要： This paper presents the results of research activities carried out to characterize and test the operation of a latest generation commercial, high-resolution Time-of-Flight (TOF) camera. The aim is to preliminary evaluate the achievable performance as well as potential limitations related to the use of this instrument for autonomous navigation purposes. Two fields of investigation have been identified: autonomous navigation of Unmanned Aerial Vehicles flying in GPS-denied environments; autonomous relative navigation between non-cooperative space objects. With reference to these applications, first, a metrological characterization has been operated within a laboratory setup. Second, experimental tests have been carried out by processing point clouds acquired by the TOF sensor with state-of-the-art algorithms (for depth-based odometry and non-cooperative pose determination, respectively).
关键词： depth-based odometry,non-cooperative pose determination,TOF camera,autonomous navigation,metrological characterization
更新于2025-09-23 15:22:29
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VALIDATED SPECTROPHOTOMETRIC METHOD FOR THE ESTIMATION OF VINCRISTINE AND VINBLASTINE
摘要： Objective: A simple, sensitive, precise, reproducible and validated UV spectrophotometric methods have been developed for the determination of vincristine (VCR) and vinblastine (VLB) in the pure and dosage forms. Methods: The method was founded on the simple solubility of VCR and VLB in purified water, and their characteristic maximum absorption λ (max) at 295 nm and λ (max) at 268 nm for VCR and VLB respectively in the UV regions. The nature of obedience, to the Bouguer-Lambert-Beer’s law by the VCR and VLB in the range of concentration 5-50 μg/ml was employed to this method. Results: Accuracy and reproducibility of the proposed method were statistically validated by recovery studies. The accuracy of the method for the VCR and VLB was ~ 100.4 % and ~ 100.32 % respectively with good reproducibility. The analytical curves were linear over a wide concentration range (5-50 μg/ml), with a correlation coefficient (r)-0.9998, and 0.9999 for VCR and VLB in that order. The method was showed sufficient precision, with a relative standard deviation (RSD) less than 1%. Conclusion: The method was validated in accordance with Russian general pharmacopoeia article (RGPA) 42-0113-09 and ICH guidelines. Validated method can easily apply for fast, precise and reliable rapid assessment of drug forms and pure substances in the laboratory.
关键词： Vincristine,Quantity determination,Analytical curve,Vinblastine,UV-visible spectrometry
更新于2025-09-23 15:22:29