Anti-interference Performance Research Articles

Application of Improved PSO and BP Hybrid Optimization Algorithm in Electrical Automation Intelligent Control

A fuzzy RBF-PID control strategy based on particle swarm optimization (PSO) algorithm is proposed to solve the problem of large inertia lag in temperature control system of industrial production refuse furnace. In this control system, an improved particle swarm optimization algorithm combined with inertia weight and genetic transformation was used to optimize the initial values of membership functions of fuzzy RBF (radial basis function). Then, BP (error backpropagation) algorithm is used for fine tuning, and fuzzy reasoning and RBF learning ability are combined to adjust the PID control parameters online to achieve the optimal PID control effect. The simulation results show that the algorithm has fast tracking, small overshoot, and is not easily trapped in local minima. At the same time, its robustness and anti-interference performance are better than traditional PID control.

Simultaneous fault-tolerant control and disturbance rejection for impulsive switched systems

This paper considers the simultaneous fault-tolerant control and disturbance rejection of impulsive switched linear systems. First, estimates of faults and disturbances in the system can be obtained by designing observers. Then, through the obtained estimation, the controller with anti-interference performance and fault tolerance performance is designed. Under the arbitrary switching rules and the minimum dwell time switching rules, the stability of the system is guaranteed. Finally, the effectiveness of the method is verified by numerical simulation and example simulation.

N-doped porous carbon modified by polyacrylic acid for efficient removal of disinfection products in environmental waters under extensive conditions

In this work, a novel porous carbon nanocomposite was successfully prepared by creatively using polyacrylic acid to modify N-doped porous carbon, which was used to adsorb and remove new cyclic chlorine disinfection by-products in various water environments. The high-temperature calcination process at 1000 °C created a hierarchical pore structure that contained both micropores and mesopores. This structure significantly increased the mass transfer efficiency of the target on the adsorbent. The incorporation of N atoms enhanced NC's binding affinity and furnished target adsorption sites. The dispersion of N-doped porous carbon was significantly improved after polyacrylic acid modification. Moreover, the surface charge of NC-1000 was also altered, facilitating easier electrostatic interaction with DBPs. Subsequently, faster adsorption kinetics was obtained within 2 min, and the removal efficiency of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) were promoted to 94.10 % and 98.71 %, respectively. Characterization and data analysis revealed that the primary adsorption mechanism was chemical (electrostatic interaction, hydrophobic interaction, π-π interaction, and hydrogen bond). Surprisingly, factors such as ionic strength, natural organic matter and pH had minimal impact on the adsorption process, indicating that NC-1000@PAA had excellent anti-interference performance. Despite undergoing four adsorption–desorption cycles, NC-1000@PAA upheld a steady composition along with a remarkable adsorption capability. Furthermore, NC-1000@PAA had negligible cytotoxicity, which was assessed by cell experiments. The application of NC-1000@PAA was attested in various environmental waters. The proposed method provided a new strategy to pollutant removal by NC-1000@PAA under extensive conditions, which had wide perspective and practicability on the purification treatment of environmental water.

Time Delay Study of Ultrasonic Gas Flowmeters Based on VMD-Hilbert Spectrum and Cross-Correlation.

The accuracy of ultrasonic flowmeter time delay measurement is directly affected by the processing method of the ultrasonic echo signal. This paper proposes a method for estimating the time delay of the ultrasonic gas flowmeter based on the Variational Mode Decomposition (VMD)-Hilbert Spectrum and Cross-Correlation (CC). The method improves the accuracy of the ultrasonic gas flowmeter by enhancing the quality of the echo signal. To denoise forward and reverse ultrasonic echo signals collected at various wind speeds, a Butterworth filter is initially used. The ultrasonic echo signals are then analyzed by Empirical Mode De-composition (EMD) and VMD analysis to obtain the Intrinsic Mode Function (IMF) containing distinct center frequencies, respectively. The Hilbert spectrum time-frequency diagram is used to evaluate the results of the VMD and EMD decompositions. It is found that the IMF decomposed by VMD has a better filtering performance and better anti-interference performance. Therefore, the IMF with a better effect is selected for signal reconstruction. The ultrasonic time delay is then calculated using the Cross-Correlation algorithm. The self-developed ultrasonic gas flowmeter was tested on the experimental platform of the gas flow standard devices using this signal processing method. The results show a maximum indication error of 0.84% within the flow range of 60-606 m3/h, with a repeatability of no more than 0.29%. These results meet the 1-level accuracy requirements as outlined in the national ultrasonic flowmeters calibration regulation JJG1030-2007.

GAA/(Au–Au/IrO2)@Cu(PABA) reactor with cascade catalytic activity for α-glucosidase inhibitor screening

BackgroundIn vitro screening strategies based on the inhibition of α-glucosidase (GAA) activity have been widely used for the discovery of potential antidiabetic drugs, but they still face some challenges, such as poor enzyme stability, non-reusability and narrow range of applicability. To overcome these limitations, an in vitro screening method based on GAA@GOx@Cu-MOF reactor was developed in our previous study. However, the method was still not satisfactory enough in terms of construction cost, pH stability, organic solvent resistance and reusability. Thence, there is still a great need for the development of in vitro screening methods with lower cost and wider applicability. ResultsA colorimetric sensing strategy based on GAA/(Au–Au/IrO2)@Cu(PABA) cascade catalytic reactor, which constructed through simultaneous encapsulating Au–Au/IrO2 nanozyme with glucose oxidase-mimicking and peroxidase-mimicking activities and GAA in Cu(PABA) carrier with peroxidase-mimicking activity, was innovatively developed for in vitro screening of GAA inhibitors in this work. It was found that the reactor not only exhibited excellent thermal stability, pH stability, organic solvent resistance, room temperature storage stability, and reusability, but also possessed cascade catalytic performance, with approximately 12.36-fold increased catalytic activity compared to the free system (GAA + Au–Au/IrO2). Moreover, the in vitro GAA inhibitors screening method based on this reactor demonstrated considerable anti-interference performance and detection sensitivity, with a detection limit of 4.79 nM for acarbose. Meanwhile, the method owned good reliability and accuracy, and has been successfully applied to the in vitro screening of oleanolic acid derivatives as potential GAA inhibitors. SignificanceThis method not only more effectively solved the shortcomings of poor stability, narrow scope of application, and non-reusability of natural enzymes in the classical method compared with our previous work, but also broaden the application scope of Au–Au/IrO2 nanozyme with glucose oxidase and peroxidase mimicking activities, and Cu(PABA) carrier with peroxidase mimicking activity, which was expected to be a new generation candidate method for GAA inhibitor screening.

Self-powered biosensing platform for Highly sensitive detection of soluble CD44 protein

In this study, a self-powered biosensor based on an enzymatic biofuel cell was proposed for the first time for the ultrasensitive detection of soluble CD44 protein. The as-prepared biosensor was composed of the co-exist aptamer and glucose oxidase bioanode and bilirubin oxidase modified biocathode. Initially, the electron transfer from bioanode to biocathode was hindered due to the presence of the aptamer with high insulation, generating a low open-circuit voltage (EOCV). Once the target CD44 protein was present, it was recognized and captured by the aptamer at the bioanode, thus the interaction between the target CD44 protein and the immobilized aptamer caused the structural change at the surface of the electrode, which facilitated the transfer of electrons. The EOCV showed a good linear relationship with the logarithm of the CD44 protein concentrations in the range of 0.5–1000 ng mL−1 and the detection limit was 0.052 ng mL−1 (S/N = 3). The sensing platform showed excellent anti-interference performance and outstanding stability that maintained over 97% of original EOCV after 15 days. In addition, the relative standard deviation (1.40–1.96%) and recovery (100.23–101.31%) obtained from detecting CD44 protein in real-life blood samples without special pre-treatment indicated that the constructed biosensor had great potential for early cancer diagnosis.

Highly effective activation of peroxymonosulfate via oxygen-coordinated single-atom iron for water decontamination

The traditional peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been significantly limited by the high inputs of oxidants. Herein, an oxygen-coordinated Fe-based single-atom catalyst (Fe-N2O1/OCN) was developed as an efficient pathway to activate peroxymonosulfate (PMS). This catalyst allows for a sharp decrease in PMS dosage while avoiding the release of additional sulfate ions into the treated water. The PAPO generates bisphenol-A (BPA) radicals and SO4•− species adsorbed onto Fe-N2O1/OCN, triggering a chain reaction for BPA degradation through BPA-initiated PAPO. The excellent performance of this system is attributed to the oxygen-coordinated iron center, which weakens the coordination of PMS on Fe-N2O1 and prevents its pre-activation. Furthermore, this PMS activation pathway demonstrates high anti-interference performance and can be continuously conducted in complex water matrices for 20 days, providing a promising alternative to traditional PMS-AOPs.

Multilayer Ti3C2-CNTs-Au Loaded with Cyclodextrin-MOF for Enhanced Selective Detection of Rutin.

In this work, multi-layer Ti3C2 - carbon nanotubes - gold nanoparticles (Ti3C2-CNTs-Au) and cyclodextrin metal-organic framework - carbon nanotubes (CD-MOF-CNTs) have been prepared by in situ growth method and used to construct the ultra-sensitive rutin electrochemical sensor for the first time. Among them, the large number of metal active sites of Ti3C2, the high electron transfer efficiency of CNTS, and the good catalytic properties of AuNPs significantly enhance the electrochemical properties of the composite carbon nanomaterials. Interestingly, CD-MOF has a unique host-guest recognition and a large number of cavities, molecular gaps, and surface reactive groups, which gives the composite outstanding accumulation properties and selectivity for rutin. Under the optimized conditions, the constructed novel sensor has satisfactory detection performance for rutin in the range of 2 × 10-9 to 8 × 10-7M with a limit of detection of 6.5 × 10-10M. In addition, the sensor exhibits amazing anti-interference performance against rutin in some flavonoid compounds and can be used to test natural plant samples (buckwheat, Cymbopogon distans, and flos sophorae immaturus). This work has promising applications in the field of environmental and food analysis, and exploring new directions for the application of Mxene-based composites.

Controllable Pyridine N-Oxidation-Nucleophilic Dechlorination Process for Enhanced Dechlorination of Chloropyridines: The Cooperation of HCO4- and HO2.

Dechlorination of chloropyridines can eliminate their detrimental environmental effects. However, traditional dechlorination technology cannot efficiently break the C-Cl bond of chloropyridines, which is restricted by the uncontrollable nonselective species. Hence, we propose the carbonate species-activated hydrogen peroxide (carbonate species/H2O2) process wherein the selective oxidant (peroxymonocarbonate ion, HCO4-) and selective reductant (hydroperoxide anion, HO2-) controllably coexist by manipulation of reaction pH. Taking 2-chloropyridine (Cl-Py) as an example, HCO4- first induces Cl-Py into pyridine N-oxidation intermediates, which then suffer from the nucleophilic dechlorination by HO2-. The obtained dechlorination efficiencies in the carbonate species/H2O2 process (32.5-84.5%) based on the cooperation of HCO4- and HO2- are significantly higher than those in the HO2--mediated sodium hydroxide/hydrogen peroxide process (0-43.8%). Theoretical calculations confirm that pyridine N-oxidation of Cl-Py can effectively lower the energy barrier of the dechlorination process. Moreover, the carbonate species/H2O2 process exhibits superior anti-interference performance and low electric energy consumption. Furthermore, Cl-Py is completely detoxified via the carbonate species/H2O2 process. More importantly, the carbonate species/H2O2 process is applicable for efficient dehalogenation of halogenated pyridines and pyrazines. This work offers a simple and useful strategy to enhance the dehalogenation efficiency of halogenated organics and sheds new insights into the application of the carbonate species/H2O2 process in practical environmental remediation.

Ultrasensitive Eu-Based MOF Luminescence Sensor for Clenbuterol Visible Recognition.

Clenbuterol (CLB) as an illegal feed additive may cause a great security risk to food safety. However, convenient and efficient detection means for CLB in practical application remain a formidable challenge. Herein, a stable Eu-based organic framework {[H2N(CH3)2]2[Eu2(ttca)2]·H2O}n (compound 1) (H4ttca = [1,1':2',1″-terphenyl]-4,4',4″,5'-tetracarboxylic acid) has been harvested, exhibiting excellent chemical stability and thermal stability. Luminescence investigation reveals that compound 1 can sensitively and selectively detect CLB without being affected by different components from simulated serum and urine (limit detection: 22.7 nM). Furthermore, sensor 1 can also be applicable to CLB recognition in real swine feeds, presenting excellent anti-interference performance. The good cyclicity of compound 1 endows CLB determination with many advantages: low cost, high stability, and simplicity. Importantly, in view of the indication of the luminescence color (red to blue), test membranes were fabricated and employed for convenient and fast CLB detection, providing a valuable scheme for the visual monitoring of CLB in meat products. This work enriches rare earth metal compounds and luminescence sensor portfolios and breaks the concentration record (nM) for detecting CLB compared with reported complex materials, providing an effective monitoring platform for CLB visually.

Analysis on Anti-Interference Performance of Sensor in Explosive Electromagnetic Environment

Analysis on Anti-Interference Performance of Sensor in Explosive Electromagnetic Environment

Highly Emissive and Robust Cd-Based MOF with an Unprecedented Topology for Tetracycline Sensing.

Herein, an unprecedented cadmium-based metal-organic framework (JNU-106) fabricated by utilizing pyrazole-functionalized tetraphenylethylene ligands (Py-TPE) and rod-shaped secondary building units is reported, possessing a new (3,3,3,6,6,8)-connected topological network. Thanks to the ingeniously designed intramolecular charge transfer behavior, which originates from the congruent coplanarity between Py and TPE, JNU-106 exhibits intense green luminescence with a quantum yield increased by 1.5 times. The phenomenon of remarkable fluorescence quenching of JNU-106 reveals that it possesses extremely high anti-interference performance, superior sensitivity, and dedicated selectivity toward tetracycline antibiotics (TCAs) in aqueous solutions, which are comparable to those of the state-of-the-art porous sensing compounds. Taking the theoretical calculations and experimental results into account, the luminescence quenching is mainly attributed to the internal filtration effect and the static quenching effect. Considering the portable and rapid performance of JNU-106-based testing strips for sensing TCAs, the fabricated JNU-106 provides an alternative for ecological monitoring and environmental governance.

Iron containing sludge-derived carbon towards efficient peroxymonosulfate activation: Active site synergy, performance and alternation mechanism

Converting industrial sludge into catalytic materials for water purification is a promising approach to simultaneously realize effective disposal of sludge and resource of water. However, manipulating the high efficiency remains a huge challenge due to the difficulty in the active sites control of the sludge. Herein, we proposed a constitutive modulation strategy by the combination of hydrothermal and pyrolysis (HTP) for the fabrication of defects-assistant Fe containing sludge-derived carbon catalysts on upgrading performance in peroxymonosulfate (PMS) activation for pollutant degradation. Adjustable defects on dyeing sludge-derived carbon catalysts (DSCC) were achieved by introducing oxygen or nitrogen functional precursors (hydroquinone or p-phenylenediamine) during hydrothermal processes and by further pyrolysis, where O was detrimental while N was beneficial to defect generation. Compared to the DSCC with less defects (DHSC-O), the defect-rich sample (DHSC-2N) exhibited superior catalytic performance of PMS activation for bisphenol A (BPA) elimination (k = 0.45 min−1, 2.52 times of DHSC-O), as well as 81.4% total organic carbon (TOC) removal. Meanwhile, the degradation capacity was verified in wide pH range (2.1–8.1) and various aqueous matrices, reflecting the excellent adaptability and anti-interference performance. Furthermore, the continuous-flow experiments on industrial wastewater showed synchronous BPA and chemical oxygen demand (COD) removal, implying great potential for practical application. Solid electron paramagnetic resonance (EPR) and 57Fe Mösssbauer spectra analysis indicated that the defects acted as secondary active sites for Fe sites, which were beneficial to accelerating the electron transfer process. The only Fe active sites preferred the radical pathway. The controllable reaction tendency provides possibilities for the on-demand design of sludge-based catalysts to meet the requirements of practical wastewater treatment under Fenton-like reaction.

O-Semiquinone Radical and o-Benzoquinone Selectively Degrade Aniline Contaminants in the Periodate-Mediated Advanced Oxidation Process.

Advanced oxidation processes (AOPs) often employ strong oxidizing inorganic radicals (e.g., hydroxyl and sulfate radicals) to oxidize contaminants in water treatment. However, the water matrix could scavenge the strong oxidizing radicals, significantly deteriorating the treatment efficiency. Here, we report a periodate/catechol process in which reactive quinone species (RQS) including the o-semiquinone radical (o-SQ•-) and o-benzoquinone (o-Q) were dominant to effectively degrade anilines within 60 s. The second-order reaction rate constants of o-SQ•- and o-Q with aniline were determined to be 1.0 × 108 and 4.0 × 103 M-1 s-1, respectively, at pH 7.0, which accounted for 21% and 79% of the degradation of aniline with a periodate-to-catechol molar ratio of 1:1. The major byproducts were generated via addition or polymerization. The RQS-based process exhibited excellent anti-interference performance in the degradation of aniline-containing contaminants in real water samples in the presence of diverse inorganic ions and organics. Subsequently, we extended the RQS-based process by employing tea extract and dissolved organic matter as catechol replacements as well as metal ions [e.g., Fe(III) or Cu(II)] as periodate replacements, which also exhibited good performance in aniline degradation. This study provides a novel strategy to develop RQS-based AOPs for the highly selective degradation of aniline-containing emerging contaminants.

Understanding the Distance Effect of the Single-Atom Active Sites in Fenton-Like Reactions for Efficient Water Remediation.

Emerging single-atom catalysts (SACs) are promising in water remediation through Fenton-like reactions. Despite the notable enhancement of catalytic activity through increasing the density of single-atom active sites, the performance improvement is not solely attributed to the increase in the number of active sites. The variation of catalytic behaviors stemming from the increased atomic density is particularly elusive and deserves an in-depth study. Herein, single-atom Fe catalysts (FeSA-CN) with different distances (dsite) between the adjacent single-atom Fe sites are constructed by controlling Fe loading. With the decrease in dsite value, remarkably enhanced catalytic activity of FeSA-CN is realized via the electron transfer regime with peroxymonosulfate (PMS) activation. The decrease in dsite value promotes electronic communication and further alters the electronic structure in favor of PMS activation. Moreover, the two adjacent single-atom Fe sites collectively adsorb PMS and achieve single-site desorption of the PMS decomposition products, maintaining continuous PMS activation and contaminant removal. Moreover, the FeSA-CN/PMS system exhibits excellent anti-interference performance for various aquatic systems and good durability in continuous-flow experiments, indicating its great potential for water treatment applications. This study provides an in-depth understanding of the distance effect of single-atom active sites on water remediation by designing densely populated SACs.

Optical fiber gas sensor with multi-parameter sensing and environmental anti-interference performance

Formic acid finds widespread applications in numerous fields, including the petrochemicals production, rubber industry, and leather tanning process, in which the operational environments are complex and diverse. The corresponding industrial systems are often intricate and highly integrated. Indeed, formic acid gas is insidious and poses a hazard to both operating personnel and industrial equipment. The existing detection technologies for formic acid gas suffer from inherent technical limitations, making it challenging to effectively shield against industrial interference in complex environments while accurately conveying information. Furthermore, the simultaneous transmission of essential environmental data alongside formic acid gas concentration remains a formidable challenge, which is crucial for facilitating the integration and simplification of industrial system. In response to the aforementioned challenges, this research firstly employs an optical fiber structure (SNS: single mode fiber-no-core fiber-single mode fiber) with natural resistance to electromagnetic interference as the substrate. Subsequently, considering the characteristics of spectral variations and the response mechanism of formic acid gas, and addressing the issue of humidity interference of the current-stage sensors based on sensitive material, the chitosan and chitosan@PDMS are chosen as sensitive membranes. Finally, a correction formula was introduced to address the temperature and humidity coupling issue of the sensor, resulting in the successful development of two formic acid gas sensors. The chitosan-based sensor has a detection sensitivity of up to 7.7 pm/ppm, whose dual parameter detection performance for temperature and formic acid gas has been experimentally demonstrated. It can also correct the humidity-induced detection error in real-time by the correction formula. The chitosan@PDMS-based sensor was fabricated by plating a hydrophobic and breathable PDMS membrane on the surface of the chitosan-based sensor. In addition to maintaining the performance compared to the original sensor (response and recovery time was increased), the latter sensor can effectively resist the humidity interference from the environment. Furthermore, the new capability has been complemented for the simultaneous detection of temperature and humidity. That is, it realizes the dual parametric detection for formic acid gas and humidity, meanwhile providing the compensation ability for temperature change. The proposed sensors have the outstanding sensitivity, selectivity, immunity, and safety. This research not only effectively resolves the interference problem in formic acid gas detection, but also provides a new idea for equipment simplification and information integration in complex industrial systems.

Enhanced degradation of Rhodamine B through activating peroxydisulfate by humic acid-Fe incorporated biochar: Kinetics and mechanism studies

Sulfate radical advanced technologies (SR-AOPs) has been increasingly applied for chemical oxidation of toxic wastewater treatment, while the sluggish kinetics of Fe(III)/Fe(II) cycling remains a serious problem in its application. In this study, a novel co-catalyst of humic acid-Fe incorporated biochar (HA-Fe@BC) was successfully synthesized that can greatly accelerate the Fe(II) regeneration. More than 95 % organic pollutants could be degraded in HA-Fe@BC/peroxydisulfate (PDS) system, especially for the model pollutant Rhodamine B (an almost 8.0-fold kinetic increase). More excitingly, the superior catalytic activity of HA-Fe@BC for PDS activation may be attributed to the ample surface C-OH and C=O groups, accelerated electron transfer and formed surface HA-Fe@BC-PDS* complex with efficient oxidation activity. Radical capture, quenching experiments and electrochemical analysis confirmed that the HA-Fe@BC/PDS was caused by radicals (SO4•-+ O2•-+•OH = 68.13 %) and non-radical (surface-mediated electron transfer and 1O2 = 26.33 %) pathways. Besides, it also exhibited anti-interference performance against anions and organic matter (eg. Cl-, Br-, NO3–, and PO43-). Furthermore, the degradation pathways were proposed by LC-MS assisted with density functional theory (DFT) calculations, and the mechanism was proposed comprehensively. This work demonstrates the PDS activation by HA-Fe@BC through free radical and non-free radical pathways, which provides insight into application of biochar-based materials for wastewater treatment.

A new stereo matching algorithm based on improved four-moded census transform and adaptive cross pyramid model

<p>Stereo matching is still very challenging in terms of depth discontinuity, occlusions, weak texture regions, and noise resistance. To address the problems of poor noise immunity of local stereo matching and low matching accuracy in weak texture regions, a stereo matching algorithm (iFCTACP) based on improved four-moded census transform (iFCT) and a novel adaptive cross pyramid (ACP) structure were proposed. The algorithm combines the improved four-moded census transform matching cost with traditional measurement methods, which allows better anti-interference performance. The cost aggregation is performed on the adaptive cross pyramid structure, a unique structure that improves the traditional single mode of the cross. This structure not only enables regions with similar color and depth to be connected but also achieves cost smoothing across regions, significantly reducing the possibility of mismatch due to inadequate corresponding matching information and providing stronger robustness to weak texture regions. Experimental results show that the iFCTACP algorithm can effectively suppress noise interference, especially in illumination and exposure. Furthermore, it can markedly improve the error matching rate in weak texture regions with better generalization. Compared with some typical algorithms, the iFCTACP algorithm exhibits better performance whose average mismatching rate is only 3.33$ \% $.</p>

A lipase-conjugated carbon nanotube fiber-optic SPR sensor for sensitive and specific detection of tributyrin.

As a low-density lipoprotein, tributyrin plays an essential role in food safety and human health. In this study, a novel lipase-conjugated carbon nanotube (CNT) surface plasmon resonance (SPR) fiber-optic sensor is used to specifically detect tributyrin for the first time. In this work, CNTs can be used as an amplifying material to significantly increase the sensitivity of SPR sensors due to their high refractive index and large surface area. CNTs can also be used as an enzyme carrier to provide abundant carboxyl groups for the specific binding of lipases. Covering the surface of the sensor with CNTs can not only enhance the performance of the sensor, but also provide sufficient detection sites for subsequent biomass detection, reduce the functionalization steps, and simplify the sensor preparation process. The experimental results demonstrate that the refractive index sensitivity of the traditional multimode fiber (MMF)-single mode fiber (SMF)-MMF transmissive optical fiber sensor is 1705 nm RIU-1. After covering the sensor with CNTs, the sensitivity is 2077 nm RIU-1, and the sensitivity has been improved very well. In addition, there are abundant functional groups on CNTs, which can provide abundant binding sites. Conjugating lipase on carbon nanotubes helps to achieve linear detection in the range of 0.5 mM to 4 mM tributyrin, with a sensitivity of 4.45 nm mM-1 and a detection limit of 0.34 mM, which is below the 2.26 mM detection standard and meets food safety monitoring requirements. Compared with other sensors, the optical fiber biosensor proposed in this study expands the concentration detection range of tributyrin. Furthermore, the sensor also has good stability, anti-interference performance and specificity. Therefore, the sensor proposed in this paper has good application prospects in the fields of food safety and biomedicine.

A phenothiazine-based ratiometric fluorescence probe for the detection of hydroxylamine in real water and living cells.

In this study, a phenothiazine-based ratiometric fluorescent probe PCHO was developed for highly sensitive and specific detection of hydroxylamine (HA). In the presence of HA, the aldehyde group on the PCHO molecule underwent a specific nucleophilic addition with HA to form an oxime group, accompanied by significant changes in fluorescence from green to blue. This detection mechanism was well supported by 1H NMR titration, HRMS and DFT calculations. The probe PCHO exhibited high sensitivity for HA detection (LOD was 0.19 μM) with a rapid response time (1 min), high selectivity and strong anti-interference performance. Surprisingly, the probe PCHO could selectively distinguish HA from its similar competing agents such as hydrazine and amines. Moreover, paper strips loaded with PCHO were prepared and combined with a smartphone to achieve point-of-care and visual detection of HA. The probe PCHO was further applied for the detection of HA in real water samples, achieving a recovery rate of 98.90% to 104.86% and an RSD of 0.86% to 2.44%, confirming the accuracy and reliability of the method. Additionally, the probe PCHO was used for imaging analysis of HA in living cells, providing a powerful visualization tool for exploring the physiological functions of HA in vivo.