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In this letter, a compact broadband RF rectifier is proposed and tested for ambient RF energy harvesting (EH). An uncomplicated impedance matching network with multistage transmission lines (quasi T-shaped) is presented. Quasi T-shaped network performs three different functions to complete the broadband matching process. The novel matching network widens working bandwidth using fewer transmission lines without via hole so that it has low loss and high conversion efficiency. After theoretical analysis and simulation, the rectifier is manufactured, and the measured results are consistent with the simulation results. The rectifier shows good broadband performance. The frequency range of rectifier efficiency over 50% is from 0.85 to 2.05 GHz (a bandwidth of 82.7%) at 5 dBm. The rectifier shows a bandwidth of 101.5% (0.8-2.45 GHz) with a power conversion efficiency (PEC) greater than 50% for an 8 dBm input power. In addition, the maximum conversion efficiency of the circuit is as high as 73.1% at the input power of 8 dBm.

This letter presents a broadband rectifier that can be applied to harvest ambient radio frequency (RF) energy. The matching network consists of three-stage transmission lines. A cross-shaped match stub of two one-eighth-wavelength transmission lines is proposed to realize efficient and broadband impedance compression. The proposed circuit has been optimized and manufactured, and the measured results show that the rectifier can achieve high RF-to-dc conversion efficiency and broadband characteristics. The simulation and measured results were basically consistent. When the input power is 8 dBm and the terminal load is 1.6 $\text{k}\Omega $ , a bandwidth of 81% (1–2.35 GHz) with an efficiency above 50% and a bandwidth 69% (1–2.05 GHz) with an efficiency above 60% are achieved. The highest conversion efficiency of the test circuit is up to 73.2% at an input power of 8 dBm. Moreover, when the input power changes from 1 to 11 dBm, the efficiency of the rectifier circuit is always above 50%.

In this letter, a compact broadband high-efficiency RF rectifier is presented for ambient RF energy harvesting (EH). A novel impedance matching network with an additional quarter-wavelength short-circuited stub was designed to achieve broadband impedance matching. After the branch was added, the parallel resonance point on track $S_{11}$ did not move, and the remaining points were compressed. The measurement results show that the proposed topology could realize a broadband high-efficiency rectifier for ambient RF EH, and the measured results were basically consistent with the simulation results. The measured efficiency is as high as 71.5% for an input power level of 8 dBm. A 1–2.4 GHz wide frequency band with an efficiency above 50% is achieved for an input power level of 5 dBm with a terminal load of 1.6 $\text{k}\Omega $ . Moreover, the circuit had wide dynamic input power characteristics, whose measured values remained above 50% with an input power of 3–14 dBm.

Despite the widespread occurrence of phenols in anthropogenic and natural compounds, their fate in reactions with hypochlorous acid (HOCl), one of the most common water treatment disinfectants, remains incompletely understood. To close this knowledge gap, this study investigated the formation of disinfection by-products (DBPs) in the reaction of free chlorine with seven para-substituted phenols. Based on the chemical structures of the DBPs and the reaction mechanisms leading to their formation, the DBPs were categorized into four groups: chlorophenols, coupling products, substituent reaction products, and ring cleavage products. In contrast to previous studies that investigated the formation of early-stage chlorophenols, the primary focus of this study was on the elucidation of novel ring cleavage products, in particular α, β-unsaturated C

It is difficult to measure the dimensions of the anterior cruciate ligament (ACL) in vivo, which makes choosing an individualized graft size for ACL reconstruction particularly troublesome. The morphology and function of porcine ACL have been reported to be similar to the native human ACL. This study aimed to identify bony morphological parameters on X-ray images that were significantly correlated with features of the native ACL. Anteroposterior X-ray images of 19 porcine knees were obtained. The width, height and area of the femoral notch, the widths of the femoral and tibial condyles and the width and area of the interspinal fossa of the tibia were measured. ACL length was measured using a caliper. The ACL was then resected and the outline of the bone insertion sites were marked and photographed for measuring the areas of the insertion sites. The excised ACL substance was scanned using X-ray microscopy and reconstructed to measure the medial-lateral (ML) and anterior-posterior (AP) widths, the long and short axes and cross-sectional area of the ACL isthmus. Linear regression analyses showed that the area of the interspinal fossa of the tibia was significantly correlated with the long axis and ML width of the ACL, and with the AP / ML width (p value = 0.038, 0.032 and 0.016 respectively). The width of the femoral condyle was significantly correlated with the area of the tibial insertion and the length and ML width of the ACL (p value = 0.013, 0.000 and 0.038 respectively). The area of the interspinal fossa of the tibia / notch width index (NWI) was significantly correlated with the long axis / short axis of the ACL (p value = 0.016). The width of the interspinal fossa of tibia / NWI was significantly correlated with the short axis of the ACL isthmus (p value = 0.009). However, the dimensions of the femoral intercondylar notch and the width of the interspinal fossa of the tibia were not significantly correlated with any of the ACL parameters. In conclusion, the dimension of the interspinal fossa of the tibia and the width of the femoral condyle measured from X-ray images might be used to estimate the shape and size of the ACL, which might be helpful for choosing a suitable graft size for ACL reconstruction. DATA STATEMENT: All data relevant to the study are included in the article.

A 2450-MHz microwave-induced lamp based on an open-ended dielectric waveguide which directly transfer high-frequency power to the neon plasma without the needs of electrodes and wires is proposed. This device is a simple structure with low-power requirement and high controllability. It can excite a neon bulb at room temperature with 3 Watts microwave power. The minimum sustaining power for plasma is as low as 0.3 Watts. Two Dumet wires are inserted into the plasma and are connected to a resistor. It demonstrates that the microwave induced plasma can rectify microwaves into dc. The rectification efficiency reaches a maximum of 0.05% with the 1000 Ohm resistor and 1.88 W input power. Although the rectification efficiency is relatively low. However, it is a novel method for microwave rectification and possess a great potential in microwave power transfer applications.

Visual inspection is expected as an ideal technique, which can directly and conveniently detect heavy metal ions by observing the color change. Insensitivity of detecting weakly colored heavy transition metal ions and low adsorptivity of metal ions on nanoparticle surface are two main factors hindering the application of visual detection in heavy metal ions detection. Herein, we demonstrated an operational colorimetric sensor based on the color dependence of nanoparticles aggregation to selective and facile detect weakly colored transition heavy metal Cd2+ ions that have been considered as the origin of the "Itai-itai" disease. Uniform colloidal 15nm graphite-like nitride doped carbon quantum dots-capped gold nanoparticle (Au@g-CNQDs) was successfully prepared, wherein the existence of numerous heptazine, carboxyl and hydroxyl groups on the nanoparticle's surface strengthened adsorption of the Cd2+ ions on the surface of Au@g-CNQDs through the "cooperative effect". As a consequence, without expensive and intricate exogenous indicators or other special additives, the Cd2+ ions could sensitively and quickly captured to detect at ultra-low concentration within 30s by the naked-eye. Under the optimal conditions, the Cd2+ ions sensor possesses good analytical performances with a wide linear range of 0.01-3.0μM and a detection limit of 10nM (S/N = 3). Moreover, the biodistribution and aggregation of Cd2+ ions were detected effectively in mice organ tissues suggesting its great potential use for real-word applications.

Microwave power harvesting is one of the promising ways to solve energy problems in the future. Improving the power harvesting ability is the central work in this area. The inverse spin Hall effect (ISHE) in ferromagnetic (FM) and nonmagnetic (NM) metallic bilayers can be utilized to convert microwave power to direct current, which may be one of the candidates of microwave power harvesting. In this work, a FM/NM microstrip array is proposed to enhance the ISHE signal, while the spin rectification effect signal in the FM layer is suppressed. This enhancement is equivalent to connecting the power sources in series, namely, the ISHE voltage is proportional to the number of the FM/NM microstrips. Our work fertilizes the spintronics and shows the possibility to use ISHE in microwave power transfer and harvesting.

Despite the widespread occurrence of furan moieties in synthetic and natural compounds, their fate in aqueous ozonation has not been investigated in detail. Reaction rate constants of seven commonly used furans with ozone were measured and ranged from kO3 = 8.5 × 104 to 3.2 × 106 M−1 s−1, depending on the type and position of furan ring substituents. Transformation product analysis of the reaction of furans with ozone focusing on the formation of toxic organic electrophiles using a novel amino acid reactivity assay revealed the formation of α,β-unsaturated dicarbonyl compounds, 2-butene-1,4-dial (BDA) and its substituted analogues (BDA-Rs). Their formation can be attributed to ozone attack at the reactive α-C position leading to furan ring opening. The molar yields of α,β-unsaturated dicarbonyl compounds varied with the applied ozone concentration reaching maximum values of 7% for 2-furoic acid. The identified α,β-unsaturated dicarbonyls are well-known toxicophores that are also formed by enzymatic oxidation of furans in the human body. In addition to providing data on kinetics, transformation product analysis and proposed reaction mechanisms for the ozonation of furans, this study raises concern about the presence of α,β-unsaturated dicarbonyl compounds in water treatment and the resulting effects on human and environmental health.

The removal of Orange II by activation of persulfate (S2O8(2-), PS) using synthesized Fe/SBA-15 in the electrochemical (EC) enhanced process was reported in this study. The reaction rate constants, degradation mechanism, catalyst stability, and evolution of mineralization and toxicity were detailed investigated. On the basis of radical scavenger results, both the sulfate radicals (SO4(-)) and hydroxyl radicals (OH) were responsible for the degradation of Orange II. A possible pathway is suggested to describe the degradation of Orange II according to the degradation intermediates identified. The results showed that the Fe/SBA-15 catalyst maintained strong reusability and stability with a low level of iron leaching. In addition, favorable mineralization efficiency in terms of COD removal efficiency (75.4%) and TOC removal efficiency (46.3%) was obtained when the reaction time was prolonged to 24h. The toxicity experiments implied that the toxicity of the treated solution ascended at the first 30min but then dropped to almost zero eventually. This study provides a proof-of-concept that can be applied widely for the PS remediation of contaminated water.

Visible (Vis) light (⩾420 nm) response ZnFe 2 O 4 photocatalyst was successfully fabricated via a facile reduction-oxidation method and its catalytic activity was demonstrated by the pronounced Orange II decolorization under Vis/ZnFe 2 O 4 /PS (persulfate, S 2 O 8 2− ) process. The reaction kinetics, degradation mechanism, catalyst stability, and mineralization as well as the toxicity, were detailed investigated. On the basis of the effects of radical scavengers, the sulfate radical (SO 4 − ) is regarded as the predominant reactive oxidants for the Orange II decolorization, while the hydroxyl radical ( OH) is also involved. A possible pathway is proposed according to the intermediates determined by GC-MS. The ZnFe 2 O 4 catalyst maintained high activity and stability with very low iron and zinc leaching during the repeated experiments. At initial pH 6.0, the total organic carbon (TOC) and chemical oxygen demand (COD) removal efficiencies at 300 min were 50.5% and 78.6%, respectively, using 0.5 g/L ZnFe 2 O 4 dosage, 1.0 g/L persulfate, and a 150 W visible light lamp. Toxicity experiments with activated sludge implied that the toxicity of the treated solution increased at the first stage but then declined as the reaction proceeded.

Activation of persulfate (PS) by ultraviolet (UV) light or metal catalysts has been extensively studied, however, little is known about the activation of persulfate by clay-based catalysts in the presence of visible light-emitting diode (LED) irradiation. Herein, a novel kaolinite-supported iron oxide (K-Fe)/PS/Vis process for the degradation of Rhodamine B (RhB) from aqueous solution is reported. It was found that although persulfate can degrade RhB via a non-radical reaction, the excited RhB molecule (RhB*) and the Fe(II) species formed on the catalyst surface can effectively activate persulfate to generate radicals which degrade RhB under visible light irradiation. On the basis of quenching experiments and electron paramagnetic resonance (EPR) studies, it is suggested that the free radicals produced from persulfate coupled with the surface-adsorbed radicals formed on the catalyst were responsible for the degradation of the dye via RhB*. Moreover, the K-Fe catalyst showed excellent reusability and stability with a low level of iron leaching. The findings of this work demonstrate a new pathway for activation of persulfate, which could effectively degrade organic pollutants and also provide some new insights into persulfate remediation of contaminated water.

In this study, a visible (Vis) light response photocatalyst was synthesized via a simple reduction–oxidation method. The structure, morphology and optical properties of the catalyst were well characterized. The absorption capability of ZnFe 2 O 4 in visible-light region was demonstrated by the high rate of Orange II decolorization under Vis/ZnFe 2 O 4 /H 2 O 2 process. Guided by studies to explore the effects of radical scavengers and to quantify the yield of hydroxyl radical ( OH) production, OH on the surface of the catalyst was found to be the dominating reactive species for the Orange II removal. Moreover, ZnFe 2 O 4 maintained high activity, crystallinity and extremely low iron and zinc leaching during repeated experiments. The intermediate products were identified by GC–MS and a possible pathway is accordingly proposed to elucidate the mechanism of Orange II degradation by OH. In addition, high extent of mineralization was obtained as the chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies were 86.6% and 60.4%, respectively, within 60 min reaction. The toxicity tests with activated sludge indicated that the toxicity of the solution increased during the first 30 min but then decreased significantly as the oxidation proceeded.

Herein, we present a catalysis-based, label-free, and efficient strategy for a rapid, high-throughput, highly selective and ultrasensitive naked-eye colorimetric assay of Au3+ in aqueous solutions, based on the gold amalgam-stimulated peroxidase mimetic activity.

A 5.8 GHz Fabry-Perot resonator antenna is proposed to improve the performance of the spin rectification effect and inverse spin Hall effect in the far field region. A planar inverse F-shaped antenna and a metamaterial superstrate are used to increase the magnitude of the electromagnetic field. The microwave electric field is enhanced by ~10-fold, while the magnetic field is enhanced by ~80-fold. Experimental results prove that the dc signal from the spin rectification effect and inverse spin Hall effect is significantly improved. This letter paves the way for the use of spintronic devices in wireless excitation applications.

With the rapid development of various types of unmanned aerial vehicles, anti-UAVs surveillance is very urgent. This paper mainly focuses on monitoring various UAVs in unknown and GPS-denied wide areas. We innovatively construct a novel anti-UAVs surveillance system based on ground random fisheye camera array. The paper mainly includes three novel parts: (1) Construct a ground random fisheye camera array anti-UAVs surveillance platform; (2) Propose a fast self-calibration method for arbitrary layout of camera array; and (3) Design a set of multi-target detection, tracking and 3D localization algorithm based on fisheye camera array. Field experiments have been carried out using four UAVs with significant appearance difference, which performs robust in various complex scenes. The experimental results demonstrate that our system can track UAVs without artificial markers, which is sufficient to complement anti-UAVs surveillance task in unknown and GPS-denied wide areas.

Visual inspection is expected as an ideal technique, which can directly and conveniently detect heavy metal ions by observing the color change. Insensitivity of detecting weakly colored heavy transition metal ions and low adsorptivity of metal ions on nanoparticle surface are two main factors hindering the application of visual detection in heavy metal ions detection. Herein, we demonstrated an operational colorimetric sensor based on the color dependence of nanoparticles aggregation to selective and facile detect weakly colored transition heavy metal Cd

Herein, we present a catalysis-based, label-free, and efficient strategy for a rapid, high-throughput, highly selective and ultrasensitive naked-eye colorimetric assay of Au

In recent years, UAV technology has developed rapidly. Due to the mobility, low cost, and variable monitoring altitude of UAVs, multiple-object detection and tracking in aerial videos has become a research hotspot in the field of computer vision. However, due to camera motion, small target size, target adhesion, and unpredictable target motion, it is still difficult to detect and track targets of interest in aerial videos, especially in the case of a low frame rate where the target position changes too much. In this paper, we propose a multiple-object-tracking algorithm based on dense-trajectory voting in aerial videos. The method models the multiple-target-tracking problem as a voting problem of the dense-optical-flow trajectory to the target ID, which can be applied to aerial-surveillance scenes and is robust to low-frame-rate videos. More specifically, we first built an aerial video dataset for vehicle targets, including a training dataset and a diverse test dataset. Based on this, we trained the neural network model by using a deep-learning method to detect vehicles in aerial videos. Thereafter, we calculated the dense optical flow in adjacent frames, and generated effective dense-optical-flow trajectories in each detection bounding box at the current time. When target IDs of optical-flow trajectories are known, the voting results of the optical-flow trajectories in each detection bounding box are counted. Finally, similarity between detection objects in adjacent frames was measured based on the voting results, and tracking results were obtained by data association. In order to evaluate the performance of this algorithm, we conducted experiments on self-built test datasets. A large number of experimental results showed that the proposed algorithm could obtain good target-tracking results in various complex scenarios, and performance was still robust at a low frame rate by changing the video frame rate. In addition, we carried out qualitative and quantitative comparison experiments between the algorithm and three state-of-the-art tracking algorithms, which further proved that this algorithm could not only obtain good tracking results in aerial videos with a normal frame rate, but also had excellent performance under low-frame-rate conditions.

This paper proposes a novel infrared camera array guidance system with capability to track and provide real time position and speed of an air robot during a landing process. The system mainly include three novel parts: (1) Infrared camera array and infrared laser lamp based cooperative long range optical imaging module; (2) Large scale outdoor camera array calibration module; and (3) Laser marker segmentation and 3D tracking module. Extensive automatic landing experiments with fixed-wing flight demonstrate that our infrared camera array system has the unique ability to guide the air robot landing safely and accurately in real time, and the landing point error is less than 0.2 meters. Moreover, the measurement and control distance of our system is over 1000 meters, far beyond many state-of-the-art optical guidance systems. The experimental results also demonstrate that our system can be used for air robot automatic accuracy landing in GPS-denied environments.

This paper proposes a novel infrared camera array guidance system with capability to track and provide real time position and speed of a fixed-wing Unmanned air vehicle (UAV) during a landing process. The system mainly include three novel parts: (1) Infrared camera array and near infrared laser lamp based cooperative long range optical imaging module; (2) Large scale outdoor camera array calibration module; and (3) Laser marker detection and 3D tracking module. Extensive automatic landing experiments with fixed-wing flight demonstrate that our infrared camera array system has the unique ability to guide the UAV landing safely and accurately in real time. Moreover, the measurement and control distance of our system is more than 1000 m. The experimental results also demonstrate that our system can be used for UAV automatic accurate landing in Global Position System (GPS)-denied environments.

Porphyrin is one of the most attractive molecules for its well known functions in biological and biomimetic systems because of their excellent stability, unique optical and electronic properties.Their electrochemical and photophysical properties make porphyrin derivatives combine with a complementary electron-accepting species to mimic the electron transport of biological process based on the formation of electron donor/acceptor(D/A) system.So Porphyrin compounds are widely employed as platform to recognize various species. Photoinduced charge transfer (PCT) plays a central role in biologically significant systems and in applications that harvest solar energy. The electron-rich macrocyclic compounds such as porphyrins have been widely used as biomimetic photosensitizing electron donor in these studies, since they absorb lights over wide wavelengths in the visible region and exhibit favorable redox potentials. Our group mainly focus on the PCT kinetics, electron transfer mechanisms of porphyrin and its derivarives. Scanning electrochemical microscopy (SECM), Electrochemical Impedance spectroscopy are the techniques that have been used extensively in our investigatios. Self-assembled monolayers (SAMs) of thiol-porphyrins with different alkyl chain length (H2TPPO(CH2)nSH, n=3, 6, 9 and 12)，thiol-derivatized tetraphenylporphyrin (SH-TPP) and cobalt tetraphenylporphyrin (SH-CoTPP) on gold electrode have been prepared and their structure, direct electron transfer (ET) process， electrochemical behaviors of a series of SH-Terminated-Functionalized Porphyrinswas studied by electrochemical impedance spectroscopy and SECM. SAMs of thiol-derivatized tetraphenylporphyrin on Gold electrodes was designed to detect H2PO4 -even in the presence of a 10-fold excess of other anions. Substituent effects of iron porphyrin complexes on the structures and kinetic processes have been studied. We developed a novel SECM model which provide a two-dimensional quantitative analysis on a heterogeneous electron transport (ET) process of a functionalized porpyrin by photoinduced ET at the ITO/liquid interface. Our liquid-liquid interface works include but not restricted to the following examples. Investigation of Ion Transport Traversing the “Ion Channels”, Consecutive electron transfer of metalloporphyrin species containing different substituents at the Liquid/Liquid Interface by thin-layer cyclic voltammetry, electrochemical properties of metalloporphyrin species at the Liquid/Liquid interface by switching substitutes on the porphyrin ring, current oscillatory phenomena based on Fe3+/Fe2+at the liquid/liquid interface. Potential electrochemical sensors have been developed for the anaytes which are of environmenal and biological significance. Few examples are, an electrochemical method for the detection of DNA damage by combining the layer-by-layer assembly film with adriamycin (ADM) as an electrochemical probe, recognition of -1,3-glucanase gene (Glu) specific sequence based on probe extension, electrochemical behavior of hydroquinone (HQ) was studied by cyclic voltammetry at a glassy carbon electrode (GCE) modified by a gel containing multi-walled carbon nanotubes (MWNTs) and room temperature ionic liquid (RTIL) of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), investigation of the mechanism of the N-H migration in asymmetrical metal-free porphyrins, four porphyrins of electron-withdrawing or electron-donating substituent at the -position were studied theoretically visual colorimetric and electrochemical biosensor for porphyrin, Ag nanoparticles on functionalized graphene for an excellent electrochemical sensor of nitroaromatic compounds methyl-parathion pesticide, based on the advantages of porphyrin and porphyrin derivatives, we envisioned the introduction of the hydroxyphenyl-porphyrin into CNTs could enhance the sensitivity of the detection of explosives basedon the synergetic effects of porphyrin and CNTs.

In this paper, a miniaturized omni-directional antenna based on Composite Right and Left Handed (CRLH) structure is proposed. The resonance frequency, the total gain are observed at 5 GHz, 1.15 dB respectively. This design exhibits a bandwidth of 400MHz and has a simple mushroom structure with a small size of 5mm * 5mm * 6.7mm ( λ 0 /12* λ 0 /12* λ 0 / 9). The proposed antenna can be used to the IEEE 802.11a standard for WLAN and WiFi.

This paper demonstrates an effective designing method of the waveguide directional coupler. The coupler designed using this method has wide band, high directivity, flat coupling, low voltage standing ratio and manufacturing accuracy. A Ku band high power waveguide directional coupler has been designed, the directivity is more than 28 dB and the coupling coefficient is 30dB with the deviation of 0.8 dB.

In this paper, a novel microstrip patch antenna is proposed which has Zeroth Order Resonance (ZOR) mode and is based on the Composite Right and Left Handed (CRLH) structure. The metallic patch is suggested to be coupled with four surrounding unit cells. It is different from the previous 1D ZOR antennas commonly having several metal cells in line or the conventional ZOR antennas of periodic mushrooms. The ZOR frequency, the gain and the antenna efficiency are observed 6.5 GHz, 2.12 dB and 90.3%, respectively. Besides, this proposed antenna has the omni-directional field pattern and achieves miniaturization.