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Obtaining a continuous relationship between input and output is essential during sensor characteristic determination. However, it is a little challenging for complicated input data, for example, image data. In this article, a sensor characteristic determining method using deep learning Compact yet Efficient Cascade Context-based Estimation (C3E) network, which can establish the continuous relationship between the input and the output, was proposed. A UV sensing system based on this C3E method was presented. The sensor after algorithm optimization has a sensitivity of $1~\mu \text{W}$ /cm2. The limit of detection is $9~\mu \text{W}$ /cm2. The network test time is close to 3 s, and the error rate is 5%, which is very suitable to transplant to the embedded platform and provides solutions for compact instruments.

Industrial wastes, such as steel slag and desulfurized gypsum, are piled up in large quantities and only a very small portion is recycled, adversely impacting natural ecosystems. Meanwhile, environmental problems caused by CO2 have increasingly received attention. Hence, this study introduces a novel environmentally friendly composite, formed by sodium hydroxide (used as an activator), desulfurized gypsum and steel slag (S-GS). The main objective of this study is to evaluate the potential use of S-GS for solidifying clay under the condition of carbonation curing. Besides, the samples’ characteristics are investigated according to the tests of unconfined compressive strength (UCS), pH, carbonation depth, quality loss and scanning electron microscope (SEM). It is found that the UCS of solidified clay decreases with the increasing water content while it increases first and then decreases with the increasing desulfurized gypsum content, reaching the maximum when the water content is 0.5 times the liquid limit and the content of desulfurized gypsum is 8%. Moreover, compared with the standard curing, carbonation curing can stimulate the activity of S-GS to improve the UCS of samples more effectively. With the increasing carbonation curing time, the mass loss rate and carbonation depth of samples increase while the pH value decreases. Additionally, based on the normalized analysis, the carbonation time has the most significant effect on the UCS. Furthermore, the SEM results indicate that formation of Calcium carbonate and Magnesium carbonate are primary reasons for improving the UCS of the stabilised clay during carbonization. This research promotes steel slag and desulfurized gypsum as green stabilisers for soil stabilization, and the method of carbonation curing contributes to the higher UCS, which also greatly shortens the curing time.

UV absorption coating is an important function material, which can protect the substrates from photoaging. In this work, a class of sustainable UV-absorbent copolymers derived from ethyl cellulose (EC), fatty acid and rosin were prepared by a combination of atom transfer radical polymerization (ATRP) and click chemistry. To fulfill this strategy, the pendant azides were first attached onto the backbone of EC. Then, ATRP was applied to fabricate well-defined poly(lauryl methacrylate) (PLMA) bearing terminal alkynes. Finally, click chemistry between the pendant azides in EC and the alkynes in PLMA as well as in rosin esters (DAPE), was performed to achieve the cellulose-rosin graft copolymers (EC-(g-DAPE)-g-PLMA) with UV absorption property. The chemical structure of cellulose-rosin graft copolymers was confirmed by FTIR, 1H NMR and GPC. Thermodynamic performance analysis indicated that these EC-rosin graft copolymers showed better thermal stability than EC. Due to the synergistic hydrophobic interaction of rosin and the hydrophobic lauryl groups in PLMA, these graft copolymers showed excellent hydrophobic property, and the static contact angles were all above 90°. In addition, all the EC-rosin graft copolymers showed outstanding and stable UV absorption capability, and maintained excellent UV absorption capability after continuous UV-irradiation for 1 h or being heated to 100 °C for 0.5 h, which had potential application in UV absorption materials.

Global navigation satellite system (GNSS) spoofing poses a significant threat to maritime logistics. Many maritime electronic devices rely on GNSS time, positioning, and speed for safe vessel operation. In this study, inertial measurement unit (IMU) and Doppler velocity log (DVL) devices, which are important in the event of GNSS spoofing or outage, are considered in conventional navigation. A velocity integration method using IMU and DVL in terms of dead-reckoning is investigated in this study. GNSS has been widely used for ship navigation, but IMU, DVL, or combined IMU and DVL navigation have received little attention. Military-grade sensors are very expensive and generally cannot be utilized in smaller vessels. Therefore, this study focuses on the use of consumer-grade sensors. First, the performance of a micro electromechanical system (MEMS)-based yaw rate angle with DVL was evaluated using 60 min of raw data for a 50 m-long ship located in Tokyo Bay. Second, the performance of an IMU-MEMS using three gyroscopes and three accelerometers with DVL was evaluated using the same dataset. A gyrocompass, which is equipped on the ship, is used as a heading reference. The results proved that both methods could achieve less than 1 km horizontal error in 60 min.

The permeability of soil is a fundamental parameter in hydrological and geotechnical studies, nevertheless, the investigations on the silt especially the heavy mental contaminated silt have rarely been reported. The research introduces the effect of the different factors, including the osmotic pressure, curing time, the content of binders and the concentration of lead, on the permeability and microscopic properties of lead-contaminated silt, which is solidified by a novel curing agent, formed by mixing cement, fly ash and desulphurization gypsum (CFG). According to the tests of the permeability and scanning electron microscope (SEM), the permeability of samples is investigated under different influencing factors. The results demonstrate that the permeability coefficient of the contaminated silt increases with the increasing osmotic pressure and lead ion concentration, while decreases with the increasing CFG content and the curing time, additonally, there are interactions among various factors, which jointly affect the permeability of samples. Moreover, the statistical analysis shows that osmotic pressure has the most significant effect on permeability among various factors. Besides, the influence of lead ion concentration, osmotic pressure and CFG content on the permeability coefficient at the curing time of 14d is more significant than that of 28d, and the influence order of factors was slightly different at different curing time. Furthermore, the SEM test proves the conclusion of the statistical analysis, which also explains the common reasons for the enhancement of the impermeability and unconfined compressive strength (UCS) of the lead-contaminated silt with the increasing curing time.

Well-defined sustainable and recyclable thermoset elastomers derived from cellulose, fatty acid and furfural were successfully prepared via photoinduced metal-free ATRP and Diels-Alder (DA) reaction. Firstly, metal free ATRP was applied to prepare a range of thermoplastic cellulose graft copolymers with furfural groups. Then, a modified epoxidized soybean oil bearing 6-maleimidohexanoic group (ESOM) as a crosslinker was employed to perform DA reaction with furfural groups in these cellulose graft copolymers, by which the copolymer formed the dynamic crosslinked network and achieved the thermoset elastomers. The dynamic crosslinked network formed by DA reaction not only could increase the chain entanglement that was associated with the improved flexibility and could contribute to enhancing the mechanical strength up to 166 %, but also endowed these thermoset elastomers with recyclability, excellent shape memory and self-healing property. These thermoset elastomers can be used as self-healing strain sensor and wearable sensing devices after compounding them with carbon nanotubes.

To overcome the drawback of UV light response in La2Ti2O7 nanosheets, novel up-conversion carbon quantum dots (CQDs) with visible light response have been introduced on the surface of La2Ti2O7 for efficient enhancement of photocatalytic performance. The resulted CQDs/La2Ti2O7 samples were characterized by XRD, TEM, FT-IR, XPS and UV–vis, respectively. Rhodamine B (RhB) solution was chosen as the target organic pollutant to evaluate the photocatalytic activity under visible light irradiation. The results indicated that 5 wt% loading of CQDs composite exhibited the best performance. Both the up-converted photoluminescence behavior and their electron capturing ability of CQDs are considered as the main reasons for the enhanced photocatalytic abilities.

Developing low-cost, high performance, stable non-noble bifunctional electrocatalysts for overall water splitting is of great importance for future energy supplement. Despite recent advances in the synthesis of transition metal selenide nanostructures, the fabrication of porous nanosheet based binder-free electrode with more active sites remains a major challenge. Herein, the self-templating construction of a porous CoSe2 nanosheet array on carbon cloth (p-CoSe2/CC) has been reported by vapor selenizing the preprepared α-Co(OH)2 nanosheet array precursor. Arising from large active surface area, fast diffusion of generated gas and strong structural stability, the as-obtained p-CoSe2/CC can serve as an efficient bifunctional electrocatalyst for both OER and HER in alkaline electrolyte, with a current density of 10 mA cm–2 at overpotential of 243 mV for OER and 138 mV for HER, respectively. Moreover, when p-CoSe2/CC is assembled as an alkaline electrolyzor, it only needs a cell voltage of 1.62 V at 10 mA cm–...

In this paper, we took the initiative to investigate the synthesis and photocatalytic properties of new solar-light active Ag3PO4/La2Ti2O7 0D/2D heterojunction photocatalysts with 10 wt% ∼70 wt% Ag3PO4 loading. 2D La2Ti2O7 nanosheets modified by uniformly dispersed super-small Ag3PO4 nanoparticles with average particle size as small as 4.9 nm were prepared by an in-situ chemical deposition method, and probed by electron microscopy, X-ray diffraction and UV–vis diffuse reflection spectroscopy. The photocatalytic activities were evaluated using Rhodamine B (RhB) as a target organic pollutant under simulated solar light irradiation. The results show that La2Ti2O7 nanosheets modified with proper amount of Ag3PO4 nanoparticles exhibited much higher photocatalytic activity. The optimal loading amount of Ag3PO4 was observed to be 50 wt% with the best photocatalytic performance, which could degrade almost all RhB dyes within 8 min under sunlight irradiation with the highest rate constant value of 0.5632 min−1. The mechanism accounting for the photocatalytic results were also proposed by PL, transient photocurrent response, radical trapping experiments and electron paramagnetic resonance spectra. Moreover, the photocorrosion of Ag3PO4/La2Ti2O7 photocatalysts is efficiently suppressed after depositing thin layers of AgI on Ag3PO4 nanoparticles.

Microfluidic chips integrated with negative dielectrophoresis (nDEP) and electrochemical impedance spectroscopy have wide applications in cell sensing. Accurate analysis of the kinematics and dynamics of cells in the nDEP process is crucial to improve the positioning accuracy and electric cell-substrate impedance sensing (ECIS) performance. This paper reports employing the three-dimensional (3D) finite element model to analyze the coupling effects of electrokinetic flows (EF) such as alternating current electroosmosis (ACEO) and the electrothermal flow (ETF) on the nDEP positionings. On the quadrupole ECIS microfluid chip, three typical nDEP results are observed in the frequency range of 100 Hz-25 MHz and the amplitude range of 1-20 Vp-p. Simulations Based on the 3D hybrid model provide abundant kinematic information and show clear dynamic processes. Based on the discussion, the mechanisms of nDEP localizations and phase-tuning manipulations are proposed. It is found that the drag force could affect the particle's movement through the vortex of the flow field induced by ACEO and ETF, while the nDEP forces dominate the particles' locations on the substrate. Thus, the 3D dynamic-coupling analyses could help design the quadrupole-electrode microfluid chip and optimize the manipulation parameters in the experiment.

Recently, the development of electronic skin and smart wearable sensor have put forward high requirements for flexible sensor with excellent performance. As for a flexible sensor, precision and stability are also significant parameters besides the sensitivity and measuring range. Flexible piezoresistive sensors based on nanomaterial/nanostructure have been reported to possess the high sensitivity. Precision and stability are also important for a sensor, hence we focused on promoting them in this paper. Furthermore, a mechanism for random error generated by a nano-based piezoresistive sensor was proposed. Based on the mechanism, a certain high frequency testing signal was used instead of the direct current signal to promote the precision of the sensor. The relative random error of the sensor decrease greatly above 800 kHz (by three order at low pressure range), which increase the precision greatly. Long-term stability was tested using a total of 12 000 consecutive compression tests. After a 250 s aging process, the sensor remained incredibly stable and only 0.08% change occurred which is much better than those of reported sensors. The sensor also possessed a sensitivity of 0.24 kPa−1 and a linear measuring range of 0–4 kPa. Some applications, including respiratory/arterial pulse measurement and gait recognition, were demonstrated finally.

Formaldehyde is one of the most dangerous air pollutants, which can cause sick building syndrome. Thus, it is very crucial to precisely determine formaldehyde with a low cost and simple operation. In this paper, a smartphone-based microfluidic colorimetric sensor is devised for gaseous formaldehyde determination with high sensitivity and selectivity. Specifically, a novel microfluidic chip is proposed based on the 4-aminohydrazine-5-mercapto-1,2,4-triazole (AHMT) method to determine formaldehyde, the chip consists of two reagent reservoirs, one reaction reservoir and a mixing column. In this design to prevent the fluid from flowing out while letting the gas molecule in, a hydrophobic porous poly tetra fluoroethylene (PTFE) membrane is put on the top of the reaction reservoir. Using the microfluidic chip sensor, a smartphone-based formaldehyde determination system is developed, which makes the measuring process automated and simple. As per the experiment results, the limit-of-detection (LOD) of the system is as low as 0.01 ppm, which is much lower than the maximum exposure concentration (0.08 ppm) recommended by the World Health Organization (WHO). Moreover, the sensor is hardly affected by acetaldehyde, volatile organic compounds (VOCs) or acidic-alkaline, which shows great selectivity. Finally, the performance of the proposed sensor is verified by using it for the determination of formaldehyde in a newly decorated house.

In recent years, the development of electronic skin and smart wearable body sensors has put forward high requirements for flexible pressure sensors with high sensitivity and large linear measuring range. However, it turns out to be difficult to increase both of them simultaneously. In this paper, a flexible capacitive pressure sensor based on a porous carbon conductive paste-polydimethylsiloxane composite is reported, the sensitivity and the linear measuring range of which were developed using multiple methods including adjusting the stiffness of the dielectric layer material, fabricating a microstructure and increasing the dielectric permittivity of the dielectric layer. The capacitive pressure sensor reported here has a relatively high sensitivity of 1.1 kPa-1 and a large linear measuring range of 10 kPa, making the product of the sensitivity and linear measuring range 11, which is higher than that of the most reported capacitive pressure sensors to our best knowledge. The sensor has a detection of limit of 4 Pa, response time of 60 ms and great stability. Some potential applications of the sensor were demonstrated, such as arterial pulse wave measuring and breath measuring, which shows it as a promising candidate for wearable biomedical devices. In addition, a pressure sensor array based on the material was also fabricated and it could identify objects in the shape of different letters clearly, which shows promising application in future electronic skins.

This paper reports a novel microarray chip for in-situ, real-time and selective electroporation on individual cells integrated with cell positioning and impedance monitoring. An array of quadrupole-electrode units (termed positioning electrodes) and pairs of planar center electrodes located at the centers of each quadrupole-electrode unit were fabricated on the chip. The positioning electrodes are used to trap and position living cells onto the center electrodes based on negative dielectrophoresis (nDEP). The center electrodes are used for in-situ cell electroporation and also used to measure cell impedance for monitoring cellular dynamics in real time. Controllably selective electroporation and electrical measurement on the cells in array are realized. We present an evidence of selective electroporation through use of fluorescent dyes. Subsequently we use in-situ and real-time impedance measurement to monitor the process, which demonstrates the dynamic behavior of the cell electroporation. Finally, we show the use of this device to perform successful transfection onto individual HeLa cells with vector DNA encoding a green fluorescent.

In this letter, a novel low profile tri-band frequency selective surface (FSS) with miniaturized periodic element based on complementary structure is presented. The proposed FSS element consists of two split square loops connected with a convoluted cross dipoles in the center, and its complementary pattern etched at the bottom of the substrate. The proposed FSS provides tri-band performance. In this FSS, each element has a dimension of 0.034λ × 0.034λ, where λ represents the free-space wavelength corresponding to the resonant frequency. The frequency response of the structure is shown to have a relatively low sensitivity to the angles and polarizations of striking plane electromagnetic wave, which achieves smaller size in comparison with the previously proposed structures.

In this article, a novel frequency selective surface with multiple transmission zeros is proposed which works with one pass-band from 9. 7GHz to 12.2GHz(X-band) and two stop-bands from C-band to Ku-band. There are two zeros in each band so that the width and the rectangle coefficient of each band can be large enough. The FSS is achieved by two-layer periodic arrays of unit cells based on loop structure and Jerusalem cross. It works stable in different incident angles and polarizations and the insertion loss is less than 0.4dB.