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The triboelectric effect occurs when two dissimilar materials are in physical contact, attributed to the combination of contact electrification (CE) and electrostatic induction. It has been extensively explored for the development of high-performance triboelectric nanogenerators (TENGs). In this paper, we report on, besides the CE-related charge generation, an additional charge generation phenomenon associated with the modulation of the p-n junction when two semiconductor materials [methylammonium lead iodide (MAPI) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)] are put in contact and separated dynamically. The electrical outputs generated by the CE effect are determined by the surface potential difference between the two friction materials, while the ones induced by the p-n junction modulation are determined by the dynamic variations in the depletion widths of the two semiconductor friction materials. The outputs generated by the CE effect and the p-n junction effect are well separated in time scale; the p-n junction modulation contributes ∼20% of the total charge generated and could be varied by changing the chemical composition of the semiconductors. The results may provide an alternative method for the development of high-performance TENGs by utilizing this additional p-n junction modulation effect.

Chemodynamic therapy (CDT), as a powerful tumor therapeutic approach with low side effects and selective therapeutic efficiency, has gained much attention. However, the low intracellular content of H

Energy harvesting and energy transmission are the key technologies for self-powered systems; thus, the combination of these two is urgently needed. An innovative electric field resonance (EFR)-based wireless triboelectric nanogenerator (TENG) is proposed herein. By integrating the TENG with a capacitive coupler, the output of the TENG can be transmitted wirelessly from the transmitter to the receiver in the form of an oscillating signal with an energy-transfer efficiency of 67.8% for a 5 cm distance. Theoretical models of the EFR-TENG system are established, showing excellent agreement with the experimental results. It is demonstrated that the flexible EFR-TENG worn on the wrist can drive a digital watch wirelessly or light up at least 40 light-emitting diodes in series. The EFR-TENG is further utilized for spontaneous wireless sensing with a transmission distance up to 2.3 m with high system tolerance, showing the great potential of this novel strategy for energy harvesting and real-time wireless sensing applications.

Generation of electricity from flowing salt water is extremely attractive as the resources are abundant and green. We propose a generator to harvest DC electricity from flowing ionic solution. The device consists of a substrate with fixed surface charges, a top electrode and a bottom electrode separated with a distance. The electrostatic field originated from the surface charges separates charges of opposite polarities in the solution, while the flow directs the charges to different electrodes in a closed circuit. By utilizing ultrahigh charge density of ferroelectric substrate and ionic solution, the device produces pulsed DC output for droplets and constant current for continuous flow. The output could be greatly enhanced by using substrates with high surface charge densities and high ion concentration solutions. It could also be scaled up by connecting the devices in series or parallel. This work provides a new strategy to harvest low hydrodynamic energy from sea.

This paper presents a novel flexible capacitive 3D tactile sensor using cross-bar polydimethylsiloxane (PDMS) walls and micropillar arrays as the composite structure dielectric layer. The tactile sensor unit consists of a $2\times 2$ capacitor array where electrode pairs are arranged in a cross-bar pattern to ensure a fixed overlap area for these capacitors. A top bump is introduced for the sensor to ensure the force is applied uniformly on the sensor. When a force is applied on the sensor, it changes the capacitances of the four capacitors, distinguishing the forces from different directions. The sensitivities of the sensor in the x-, y- and z- directions are 95.08%/N, 98.30%/N and 237.48%/N, in the ranges of 0-0.15 N, 0-0.15 N and 0-0.1 N respectively, much better than most of reported ones. The high sensitivities of the proposed sensor unit are attributed to the composite structure dielectric layer and the optimized Young’s modulus of PDMS. The flexible capacitive tactile sensor shows great potential for applications in robot technology.

The lengths of input vectors corresponding to different circuits are often quite different, which makes it difficult to standardize them. This paper proposes a characteristic standardization method for circuit input vectors based on hash algorithm. First, the collision rates of different hash algorithms are analyzed, and four representative hash algorithms are selected to process the input vectors. Then, based on the given dataset, their performance is analyzed from collision rate, stability and distribution characteristics, and the best performing RSHash algorithm is selected for further research. Next, we deal with the input vectors using RSHash mapping and partitioning strategy, respectively, and then apply processed input vectors to the deep autoencoder network to perform experiments. The experimental results show that the characteristic standardization method for circuit input vectors based on RSHash algorithm has better performance.

Zinc-ion batteries (ZIBs) have attracted significant attention owing to their high safety, high energy density, and low cost. ZIBs have been studied as a potential energy device for portable and flexible electronics. Here, a highly flexible free-standing Zn anode is fabricated using a simple spin-coating technique, and its application in ZIBs is demonstrated. The free-standing Zn anode precursor is formed by mixing Zn particles with carbon nanotubes and poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP). The hexafluoropropylene group in PVDF-HFP improves the mechanical properties of the free-standing Zn anode, whereas the carbon nanotubes created percolation conduction in the composite electrode, leading to an increased electrical conductivity of the anode. Owing to the excellent electrical conductivity and high specific surface area of the free-standing Zn anode, ZIBs with high capacity, rate performance, and mechanical flexibility are achieved. The volumetric energy density of the ZIBs reaches 8.22 mW h cm-3 with a battery thickness of 0.4 mm. This work demonstrates that free-standing Zn anodes are promising anodes for flexible ZIBs.

Formaldehyde (FA) is a commercially important chemical applied in industry and scientific research. However, FA has a distinct impact on learning and memory. Although the mechanisms of FA toxicity have been well studied, additional research is required to establish the mechanisms of neuroprotection in cases of FA exposure. Docosahexaenoic acid (DHA) is a polyunsaturated fatty acid with a variety of health benefits, including the enhancement of learning and memory. In this study, we investigated the neuroprotective effects of DHA in Drosophila melanogaster that had ingested FA. Our data suggested that DHA enhanced reproductive processes, leading to an increase in the number of eggs, larvae, and adults. Surprisingly, we found that DHA had a mild protective effect against FA-induced impairments in learning and memory.

Electrical impedance matching network (EIMN) is important for the piezoelectric transducer to transmit high-power acoustic signal over a wide bandwidth. Different from the impedance matching between transducers and interface devices with a fixed impedance of $50\Omega $ , this paper presents a novel method of designing an EIMN between transducer and power amplifier (PA) based on matching transformer. First, the equivalent model of the transducer is identified through nonlinear regression process. Then, the matching transformer is designed to meet the specifications of impedance matching and high power operation. To ensure the maximum output power of the PA, a matching transformer is designed to match the impedance of the transducer to a specific resistance which is equal to the ratio of the maximum voltage to the maximum current of the PA. The proposed approach contributes to determining the optimal turns ratio of the matching transformer based on the calculation of the optimal output impedance of the PA. Simulation results demonstrate that the transformer-based EIMN, whose design process is simpler, performs as well as LC-based EIMNs. Experiment based on a B class PA proves the effectiveness and desired performance of the transformer-based EIMN.

The magneto-transport properties of two-dimensional (2D) Fe

Nanomaterials used as novel antimicrobial agents are developed to combat wide-spectrum bacteria as well as alleviate the problem of bacterial resistance to traditional antibiotics. Two-dimensional (2D) nanomaterials are regarded as promising and widely applicable wide-spectrum antibacterial nanoagents due to their outstanding characteristics, including large surface area, stable structure, good biocompatibility, and cheap raw materials, especially excellent photocatalytic or photothermal properties. The advantages of less resistance, rapid sterilization, local action mode, and non-invasive make 2D nanomaterials with photoinduced property stand out in novel sterilization agents. Here, we systematically summarize various kinds of 2D nanomaterials that were used in photoinduced antibacterial field and introduce the synthesis methods and physicochemical properties related to antibacterial capability. Besides, the sterilization mechanisms of different 2D nanomaterials are also introduced in detail including a direct temperature generation, ROS production or ROS-independent oxidative stress, or various synergistic antibacterial modes. Lastly, we have also discussed the current problems of 2D nanomaterials as light-inducing antibacterial agents and their future application prospects in the fields of biomedicine, sewage treatment, food, and other application scenarios. We envision that this review will assist investigators with quick and in-depth understanding of the latest progress in 2D nanomaterials for photoinduced sterilization, inspiring the development of multiply strategies to design and synthesize novel 2D materials with strong bactericidal capability and high biological safety, and expand 2D materials with photoinduced sterilization to more application scenarios.

Here we demonstrate a magnetic resonance coupling based wireless triboelectric nanogenerator (TENG) and fully self-powered wireless sensors. By integrating a microswitch and an inductor with the TENG, the pulsed voltage output is converted into a sinusoidal voltage signal with a fixed frequency. This can be transmitted wirelessly from the transmit coil to the resonant-coupled receiver coil with an efficiency of 73% for a 5 cm distance between the two coils (10 cm diameter). Analytic models of the oscillating and coupled voltage signals for the wireless energy transfer are developed, showing excellent agreement with the experimental results. A TENG of 40 × 50 mm2 can wirelessly light up 70 LEDs or charge up a 15 μF capacitor to 12.5 V in ~90 s. The system is further utilized for two types of fully self-powered wireless chipless sensors with no microelectronic components. The technologies demonstrate an innovative strategy for a wireless ‘green’ power source and sensing., Renewable energy based wireless power transfer is challenging. Here the authors show a resonant-coupled triboelectric nanogenerator as a wireless power source and have further utilized this system to explore two fully self-powered wireless chipless sensors.

Bioelectricity performs vital functions in the human body. When skin is damaged, the endogenous electric field will orient toward the center of wounds, guiding the migration of relevant cells and stimulating the secretion of growth factors. A large number of experiments have indicated that external electric stimuli have significant positive influences on wound healing. However, the mechanism of this therapy remains unclear, and the current selection of parameters for electric stimuli tends to be arbitrary or empirical, making it inefficient and ineffective. From the perspective of bioelectricity and electrochemistry, the mechanism of electric stimuli is investigated in detail based on a sectioned multilayer model in this work, and an electric stimuli window is obtained in terms of frequency, duty cycle, voltage, and electric charge and verified experimentally. This model provides general guidance for the optimization of electrical stimuli therapy for wound healing.

Dengue fever is caused by mosquito-transmitted dengue virus infection and continues to increase worldwide, threatening public health in tropical and subtropical regions. The primary difficulties in preventing a reduction of the medical burden of dengue fever lies in the lack of effective mosquito control, preventive dengue vaccines, and clinically effective antiviral drugs to treat dengue infections. Rapid and accurate diagnosis is crucial for proper patient care and effective control of epidemics. The present work proposes an alternative strategy for detecting the dengue virus nonstructural protein 1 (NS1) antigen in clinical serum samples by using ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) in combination with the molecularly imprinted polymers. Rather than the whole protein, the NS1 signature peptide is selected as a template for molecular imprinting and quantified as a stoichiometric readout of NS1. Three functional monomers with hydrophobic, positively charged, and negatively charged groups were synthesized by click reactions in terms of the signature peptide. These three functional monomers provide abundant recognition sites for the peptide, allowing the peptide template to be effectively imprinted during polymerization. The imprinting conditions were optimized, and the molecularly imprinted polymers were characterized and used for enriching the signature peptide from digested serum samples by solid-phase extraction and then detected by UHPLC-MS/MS. The proposed method is used to detect the dengue virus NS1 in clinical samples and holds significant promise for early confirmation of dengue virus infection.

Magnetic nanomaterials are promising adsorbents for their superior performance in the elimination of radioactive ions from aqueous solution. In this study, a new kind of fluorescent carbon dots were successfully introduced into MnFe2O4 to fabricate magnetic polyethyleneimine-functionalized carbon quantum dots/MnFe2O4 (PECQDs/MnFe2O4) nanocomposites by a simple hydrothermal method, which combined the fluorescent characteristic of CQDs, adsorption capacity of polyethyleneimine and magnetic separation property of MnFe2O4. Detailed characterization certified the formation of nanohybrid composites and its integrating advantages of fluorescence property and magnetism separation, which demonstrated its potential in immobilizing U(VI) and monitoring the adsorption process simultaneously in wastewater. The obtained PECQDs/MnFe2O4 was applied to remove U(VI) from aqueous solution and showed superior construction stability and adsorption capacity of 194 mg/g. Moreover, the kinetic and thermodynamic results suggested that the immobilization of U(VI) was an endothermic and spontaneous multilayer adsorption dominated process. In the end, the cation exchange and interaction between uranyl ions and abundant functional groups (i.e., NH2, OH and COOH) on PECQDs/MnFe2O4 were revealed to be responsible for the enhanced adsorption of U(VI), which was realized by forming outer-sphere surface complexes in the removal process. This study proposed an ultrafast-kinetics and high-efficiency adsorbent for U(VI) sequestration, which has a great application potential due to its outstanding recycling performance.

Liquid metal (LM) has been used as flexible electrodes for high performance triboelectric nanogenerators (TENGs), however it is unclear how the LM in tribo-layers would affect the performance of TENGs. Here, we report the investigation on the effects of LM particles incorporated into a tribo-layer on the performance of TENGs. The TENGs consist of a polyacrylonitrile (PAN) electrospinning nanofiber membrane, and a polytetrafluoroethylene (PTFE) thin film. LM particles with different concentrations are incorporated into PAN polymer matrix, and used to make the PAN nanofibers membranes by electrospinning. Result shows that the outputs of TENGs become much larger with the increase in LM content. Specifically, the current density increases by about 40%, and both the charge density and output voltage increase by nearly 70%. The overall output power is approximately 2 times higher for the TENG with 1.5 wt% LM concentration, as compared to those of TENGs with pure PAN tribo-layer. However, the output of PAN/LM-PTFE TENGs deteriorates drastically when the LM mass content is increased to 2.5 wt%, at which the composite contains a high density of LM spheroid and spindle particles, deteriorating the generation of triboelectric charge.

Zika virus is a small enveloped positive-strand RNA virus, which belongs to the Flaviviridae family. The RNA genome of all flaviviruses encodes three structural and seven nonstructural genes, together with 5′- and 3′-untranslated region genes flanking. Accompanying the explosive nature of the Zika outbreak in 2014, there was a devastating congenital neurodevelopmental disease in fetuses. Apart from viral RNA replication, polyprotein cleavage, Zika virus nonstructural proteins also play vital roles in the host's innate immune evasion. In this brief report, we summarize the evasion mechanisms of the viral nonstructural proteins antagonizing host antiviral innate immunity.

In spite of the high-brightness of perovskite quantum dots (QDs), their instability and sensitive to oxygen and moisture are still major challenges that obstruct their analytical applications. This work demonstrates the fabrication and application of perovskite CsPbBr3 QDs embedded in a molecularly imprinted polymer (MIP) for specific and sensitive detection of phoxim in real samples. CsPbBr3 QDs were obtained via a simple and convenient hot injection method. Based on the chemical structure of phoxim, we designed and synthesized a siloxane functional monomer with multiple functional groups to allow various types of interactions with phoxim. Next, the MIP/QDs composites were synthesized by slowly hydrolyzing the organosilicon monomers in situ. The obtained MIP/QDs composites possessed excellent selectivity for phoxim, and the imprinting factor of the optimized MIP/QDs was 3.27. Compared with previous studies regarding the detection of organophosphorus pesticides, the MIP/QDs fluorescence sensor exhibited high sensitivity and specificity. Under optimal conditions, the fluorescence quenching of the MIP/QDs had a good linear correlation for phoxim in the concentration range of 5–100 ng/mL, and with a limit of detection of 1.45 ng/mL. Finally, the method was used for the detection of phoxim in potato and soil samples, achieving recoveries of 86.8–98.2%.

This paper describes an alternative strategy for the preparation of highly ordered molecularly imprinted mesoporous silica microspheres (MIMSM) for the selective fluorescence sensing of sparfloxacin in biological samples. We designed and synthesized a new functional monomer through the thiol-ene click chemistry reaction of 3-(methacryloyloxy) propyltrimethoxysilane and 3-mercaptopropionic acid. Sparfloxacin was selected as a template, and Mn-doped ZnS quantum dots served as the signal transducing element. This one-pot strategy was used to fabricate the MIMSM. Fourier transform infrared spectroscopy demonstrated successful embedding of a functional monomer in the mesoporous silica microspheres, and the highly ordered, periodic hexagonal mesoporous structure of MIMSM was confirmed with small angle X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption measurements. The fluorescence intensity of the MIMSM had linear correlation with 0.05–2.0 μg/mL sparfloxacin. There was a rapid response time and excellent selectivity for structural analogues. Under optimal conditions, the limit of detection was 0.012 μg/mL for sparfloxacin. This method was then used with serum samples to achieve recoveries of 88.8–102%.

The leakage of radionuclides poses a great threat to the global ecosystem, which has aroused world-wide continuous attention. Since sorption plays the most important role in their environmental fate and humic acid (HA) is a key factor to their migration behavior, it is necessary to develop highly-efficient adsorbents that can remove radionuclides from the contaminated water in the presence of HA. Herein, we reported a novel multi-shelled Fe3O4@MnOx, which showed considerable sorption capacities towards uranium (U(VI)) and europium (Eu(III)). From the systemic batch experiments, the sorption kinetics follows the pseudo-second-order model, and sorption thermodynamics are endothermic processes. The sorption edges are pH-dependent but independent of ionic strength. Furthermore, the sorption isotherms are well described by the Langmuir model, giving maximum sorption capacities of 106.72 mg·g−1 for U(VI) and 138.13 mg·g−1 for Eu(III) at 298 K. Based on the spectroscopic studies, U(VI) is mainly adsorbed on the MnIII-O-H site while Eu(III) shows higher affinity to the MnIV-O-H site. In the presence of humic acid (HA), the HAUO2+ and (HA)2Eu+ species can accelerate the sorption kinetics and enhance the sorption capacities. This work can not only boost the exploration of adsorbent systems in the field of materials, but also promote the investigations of the interface reaction mechanism in the field of radiochemistry.

Stable and reliable electrical properties of interconnects and interfaces between flexible/stretchable and rigid materials/components are essential for the practical applications of flexible electronic devices and systems; traditional metal thin films and hard solder interconnects and interfaces can no longer meet these requirements. As an emerging soft conductive material, liquid metal has the advantages of high stretchability, flexibility, etc. over other soldering materials, and it has been used in interconnects and interfaces for some flexible electronics. In this study, we report a detailed investigation on the reliability and stability of liquid metal-based interconnects/interfaces under various mechanical deformations, including extension, bending, torsion, high frequency vibration and high temperature operation; we also compared the results with those of interconnects and interfaces using silver paste, the most commonly used solder for flexible electronics. The results show that liquid metal interconnects and interfaces maintain high conductivity under severe elongation up to 95% and 130%, upon bending with a curvature radius as low as ∼1.5 mm, and upon twisting up to 360°; meanwhile, interconnects and interfaces with silver paste filler lose electrical conductivity at elongations of 0.6% and 60%, respectively. Liquid metal interconnects and interfaces show superior performance to silver paste interconnects and interfaces because liquid metal can be re-shaped to make good contact with objects, while the silver paste becomes solid and rigid once dried and thus loses contact with other objects under deformation.

Perovskite-based photodetectors have great potential in light-signal conversion; the suppression of the dark current is regarded as one of the main concerns within the academic research communities to achieve a high-performance photodetector. Interfacial engineering in the transport layer is considered as one of the most essential methods for enhancement of perovskite photodetectors. Here, a nanocomposite thin film of tetra-sulfonated copper phthalocyanines and reduced graphene oxide (TS-CuPc/rGO) was investigated as the interfacial layer in perovskite-based photodetectors. Photodetectors with the TS-CuPc/rGO thin film as the interfacial layer exhibited a low dark current density of 2.2 × 10−8 A cm−2 at bias of −0.1 V as well as high responsivity and detectivity of ∼357 mA W−1 and ∼4.2 × 1012 jones, respectively; moreover, we observed an ON/OFF ratio of 7.33 × 103 to 520 nm light with an intensity of ∼0.077 mW cm−2. Our study revealed that with rGO additives, TS-CuPc molecules were favorable for the formation of an edge-on stacking film with high crystallinity. The rGO-induced crystalline TS-CuPc thin film with lower crystallographic defects effectively reduced the carrier recombination rate at the interfaces, leading to a suppressed dark current and enhanced photocurrent in the photodetector device, when compared to the less crystalline TS-CuPc layer.

Uranium, a kind of strategic resource for nuclear energy, is inevitably released into environment because of nuclear fuel fabrication and ore mining. Although numerous traditional materials have been applied for the removal of radionuclides, the integrating advantages of ultrafast adsorption kinetics and high adsorption capacity are still an extreme challenge. Herein we reported a facile strategy for fabricating a novel porous Al2O3 microsphere (P-Al2O3 MSs) by the calcination of metal–organic frameworks (MIL-53(Al)) and applied it to immobilize radionuclides from wastewater. The resulting P-Al2O3 MSs inherited the morphology of MIL-53(Al) and manifested a mesoporous structure with high specific area (∼248.57 m2·g−1). Kinetic analyses denoted that U(VI)/Eu(III) adsorption onto P-Al2O3 MSs achieved equilibrium within 25 min, much shorter than the commercial γ-Al2O3 nanomaterials. The calculated maximum adsorption amounts of P-Al2O3 MSs at 298 K reached 316.87 mg·g−1 for U(VI) (pH = 5.0) and achieved 223.37 mg·g−1 for Eu(III) (pH = 6.0), much higher than γ-Al2O3 and most of other functionalized metal oxides. XPS analysis indicated that the hydroxy groups played a necessary part role for the binding of U(VI) and Eu(III) to P-Al2O3 MSs. Moreover, the excellent adsorption capabilities for U(VI) and Eu(III) in natural or synthetic waters further confirmed the practical application of P-Al2O3 MSs in real wastewater treatment.

Memristors are an important component of the next-generation artificial neural network, high computing systems, etc. In the past, two-dimensional materials based memristors have achieved a high performance and low power consumption, though one at the cost of the other. Furthermore, their performance can not be modulated frequently once their structures are fixed, which remains the bottleneck in the development. Herein, a series of forming free memristors are fabricated with the same Cu/Fe

Functional microcapsule refers to a small container in which solid, liquid or gas are wrapped by natural or synthetic polymer materials to form a core-shell structure. Meanwhile, the corresponding functional ink can be obtained by combining functional microcapsule with ink. In this study, thermal expansion and aromatic slow-release functional microcapsules were formulated at a certain ratio with colorants and binders to obtain a composite microsphere ink with aromatic expansion effects. Based on this, the functional microcapsule ink is transferred to five kinds of different flexible printing substrates such as cotton, non-woven fabric, kraft paper, offset paper and coated paper by screen printing, and the impact of binder on ink printability is mainly investigated. Moreover, the surface morphology, foaming height, adhesion of printed products and thermal stability of printing ink were characterized by laser confocal microscope, thickness gauge and thermogravimetric analyzer. At the same time, the printing effects of functional microcapsule ink on different substrates were evaluated and the ink formula was adjusted. Finally, a functional printed product with long-lasting fragrance and three-dimensional effect is obtained.

Platinum (Pt) gratings on langasite (LGS) substrates are a widely used structures in high temperature surface acoustic wave (SAW) devices. Multiple modes can be excited in Pt/LGS SAW devices owing to the heavy weight of the Pt electrode and leaky waves in the LGS substrate. In this work, we report on a detailed mode analysis of Pt/LGS SAW devices, where three commonly used LGS cuts are considered. A three-dimensional (3D) finite element method (FEM) numerical model was developed, and the simulation and experiment results were compared. The experiment and simulation results showed that there are two modes excited in the Pt/LGS SAW devices with Euler angle (0&deg, 138.5&deg, 27&deg, ) and (0&deg, 117&deg, ), which are Rayleigh-type SAW and SH-type leaky wave, respectively. Only the Rayleigh-type mode was observed in the Pt/LGS SAW devices with Euler angle (0&deg, 72&deg, ). It was found that the acoustic velocities are dependent on the wavelength, which is attributed to the change of wave penetration depth in interdigital transducers (IDTs) and the velocity dispersion can be modulated by the thickness of the Pt electrode. We also demonstrated that addition of an Al2O3 passivation layer has no effect on the wave modes, but can increase the resonant frequencies. This paper provides a better understanding of the acoustic modes of Pt/LGS SAW devices, as well as useful guidance for device design. It is believed that the Rayleigh-type SAW and SH-type leaky waves are potentially useful for dual-mode sensing applications in harsh environments, to achieve multi-parameter monitoring or temperature-compensation on a single chip.

In order to achieve on-site fluorescent detection of antibiotic doxycycline (DOC) residue, a new kind of fluorescent organosilicon nanodots (OSiNDs) was successfully constructed by a one-pot strategy and used as a novel ratiometric fluorescent probe. This method could enhance the fluorescence of DOC by conformational fixation on the surface of OSiNDs, and subsequently induced fluorescence resonance energy transfer (FRET). Control experimental results showed that phenylamine functional groups on the as-prepared OSiNDs possessed favorable interactions with DOC by hydrogen bond/π-π stacking, leading to both conformational change of DOC molecules and fluorescence resonance energy transfer process from OSiNDs to DOC. This method was then adapted and optimized for visual sensitive and selective detection of DOC based on ratiometric fluorescence signal, displaying a good linear range for DOC in the range of 1-35 μM with an excellent limit detection of ∼80 nM. Other tetracycline derivatives (TCs) and possible interferences have little influence on the determination of DOC using the method. The spike and recovery test of DOC in real water samples demonstrated the feasibility of the OSiNDs for DOC assay in practical samples and a test paper was fabricated with OSiNDs loading, achieving easy and visual detection of DOC by naked eyes.

By modulating a linear frequency modulated (LFM) signal onto a high-frequency carrier and transmitting it through the parametric acoustic array (PAA), the self-demodulation low-frequency signal (SD-LFM) can be generated in the far field, which settles the problem of detection range and high range resolution preferably in application. Compared with traditional signal processing method such as pulse compression, fractional Fourier transform (FrFT) is more suitable for time-frequency analysis of LFM and SD-LFM signals. A FrFT approach for parametric array sub-bottom profiler signal processing is proposed in this paper. First, SD- LFM signal generated by PAA is studied, then optimal fractional Fourier transform is performed to obtain the energy centralized signal in fractional Fourier domain (u domain). After that, u domain windowed filtering is done to filter out the in-band noise and enhance the signal. Finally, time dimensional transformation is used to get the high-quality sub-bottom profile in time domain. The performance of the proposed method is verified by simulations, which indicate the effectiveness of the algorithm.