Abnormal Behavior Monitoring Method of Larimichthys crocea in Recirculating Aquaculture System Based on Computer Vision.

It is crucial to monitor the status of aquaculture objects in recirculating aquaculture systems (RASs). Due to their high density and a high degree of intensification, aquaculture objects in such systems need to be monitored for a long time period to prevent losses caused by various factors. Object detection algorithms are gradually being used in the aquaculture industry, but it is difficult to achieve good results for scenes with high density and complex environments. This paper proposes a monitoring method for Larimichthys crocea in a RAS, which includes the detection and tracking of abnormal behavior. The improved YOLOX-S is used to detect Larimichthys crocea with abnormal behavior in real time. Aiming to solve the problems of stacking, deformation, occlusion, and too-small objects in a fishpond, the object detection algorithm used is improved by modifying the CSP module, adding coordinate attention, and modifying the part of the structure of the neck. After improvement, the AP50 reaches 98.4% and AP50:95 is also 16.2% higher than the original algorithm. In terms of tracking, due to the similarity in the fish's appearance, Bytetrack is used to track the detected objects, avoiding the ID switching caused by re-identification using appearance features. In the actual RAS environment, both MOTA and IDF1 can reach more than 95% under the premise of fully meeting real-time tracking, and the ID of the tracked Larimichthys crocea with abnormal behavior can be maintained stably. Our work can identify and track the abnormal behavior of fish efficiently, and this will provide data support for subsequent automatic treatment, thus avoiding loss expansion and improving the production efficiency of RASs.

Size effect on nonlinear optical properties and ultrafast dynamics of silver nanoparticles.

Z-scan technology was used to study the nonlinear absorption (NLA) and nonlinear refraction (NLR) of silver nanoparticles (Ag NPs) with various sizes under different laser intensities. The results demonstrate that the NLA and NLR of Ag NPs were size-dependent. Specifically, the 10 nm Ag NPs exhibit saturation absorption (SA) and insignificant NLR. The 20 and 40 nm Ag NPs show the coexistence of SA and reverse saturation absorption (RSA). SA is believed to result from ground-state plasma bleaching, whereas RSA originates from excited state absorption (ESA). The 20 nm and 40 nm Ag NPs shows increasing self-defocusing with the increase of laser intensity. It was observed that the energy relaxation of Ag NPs mainly includes two processes of electron-phonon and phonon-phonon couplings on the order of picoseconds.

Resistive switching memory devices based on electrical conductance tuning in poly(4-vinyl phenol)-oxadiazole composites.

Nonvolatile memory devices, based on electrical conductance tuning in thin films of poly(4-vinyl phenol) (PVP) and 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) composites, are fabricated. The current-voltage characteristics of the fabricated devices show different electrical conductance behaviors, such as the write-once read-many-times (WORM) memory effect, the rewritable flash memory effect and insulator behavior, which depend on the content of PBD in the PVP + PBD composites. The OFF and ON states of the WORM and rewritable flash memory devices are stable under a constant voltage stress or a continuous pulse voltage stress at a read voltage. The memory mechanism is deduced from the modeling of the nature of currents in both states in the devices.

Electrooxidation of formaldehyde based on nickel-palladium modified ordered mesoporous silicon.

Nickel and palladium nanoparticles were finely dispersed on ordered mesoporous silicon microchannels plate (MCP) by electroless plating. The structure and composition of the resulting Ni-Pd/Si MCP were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The electrocatalystic properties of Ni-Pd/Si MCP electrode for formaldehyde oxidation have been investigated by cyclic voltammetry. The results show that Ni-Pd/Si MCP has a higher catalytic activity and better steady-state behavior for formaldehyde oxidation. This may be attributed to the synergistic property of high dispersion of Nickel and Palladium nanoparticles and particular properties of mesoporous Si MCP. The present study shows a promising choice of Ni-Pd nanoparticles supported by mesoporous silicon as effective electrocatalyst for formaldehyde electrooxidation in alkaline medium. The results imply that the Ni-Pd/Si MCP nanocomposite has good potential application in formaldehyde fuel cells and sensors.

Local Privacy Protection for Sensitive Areas in Multiface Images.

The privacy protection for face images aims to prevent attackers from accurately identifying target persons through face recognition. Inspired by goal-driven reasoning (reverse reasoning), this paper designs a goal-driven algorithm of local privacy protection for sensitive areas in multiface images (face areas) under the interactive framework of face recognition algorithm, regional growth, and differential privacy. The designed algorithm, named privacy protection for sensitive areas (PPSA), is realized in the following manner: Firstly, the multitask cascaded convolutional network (MTCNN) was adopted to recognize the region and landmark of each face. If the landmark overlaps a subgraph divided from the original image, the subgraph will be taken as the seed for regional growth in the face area, following the growth criterion of the fusion similarity measurement mechanism (FSMM). Different from single-face privacy protection, multiface privacy protection needs to deal with an unknown number of faces. Thus, the allocation of the privacy budget ε directly affects the operation effect of the PPSA algorithm. In our scheme, the total privacy budget ε is divided into two parts: ε_1 and ε_2. The former is evenly allocated to each seed, according to the estimated number of faces ρ contained in the image, while the latter is allocated to the other areas that may consume the privacy budget through dichotomization. Unlike the Laplacian (LAP) algorithm, the noise error of the PPSA algorithm will not change with the image size, for the privacy protection is limited to the face area. The results show that the PPSA algorithm meets the requirements ε-Differential privacy, and image classification is realized by using different image privacy protection algorithms in different human face databases. The verification results show that the accuracy of the PPSA algorithm is improved by at least 16.1%, the recall rate is improved by at least 2.3%, and F1-score is improved by at least 15.2%.

Visible and Near-Infrared Broadband Absorber Based on Ti3C2Tx MXene-Wu.

A high absorption broadband absorber based on MXene and tungsten nanospheres in visible and near-infrared bands is proposed. The absorber has a maximum absorption of 100% and an average absorption of 95% in the wavelength range of 400-2500 nm. The theoretical mechanism and parameter adjustability of the absorber are analyzed by FDTD solutions. The results show that the structural parameters can effectively adjust the absorption performance. The good absorption performance is due to the action of the local surface plasmon resonance coupling with the gap surface plasmon resonance and Fabry-Perot resonance. The simulation results show that the absorber is insensitive to the polarization and oblique incidence angle of incident light, and that high absorption and broadband can be maintained when the oblique incidence angle is up to 60°.

Synthesis of high-performance conjugated microporous polymer/TiO2 photocatalytic antibacterial nanocomposites.

High-performance conjugated microporous polymer (CMP)/TiO2 photocatalytic antibacterial nanocomposites were successfully synthesized by in situ Sonogashira polymerization. TiO2 was uniformly dispersed onto the surface and within the CMP which show the microporous nature with narrow pore size distribution. The high crystallinity and thermal stability of the CMP/TiO2 nanocomposites are attractive for use as antibacterial materials. The composites we prepared showed excellent photocatalytic antibacterial properties for the inactivation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under visible light irradiation. The photocatalytic antibacterial rates of nanocomposites against E. coli and S. aureus after 120 min of visible light irradiation were 98.14% and 100%, respectively. The superoxide anion (O2-) was confirmed to be an important substance in the antibacterial process above. The cytocompatibility of the antibacterial agents was studied in terms of cytotoxicity against NIH 3T3 fibroblasts. More than 95% of the cells were still alive in the presence of the nanocomposites, both without and with light irradiation, indicating the good cytocompatibility of the nanocomposites. Judging from the excellent photocatalytic antibacterial properties and ultralow toxicity of nanocomposites, these materials can be used in many fields such as medical treatment, transportation and construction.

Synthesis of Cis-Cisoid or Cis-Transoid Poly(Phenyl-Acetylene)s Having One or Two Carbamate Groups as Oxygen Permeation Membrane Materials.

Three new phenylacetylene monomers having one or two carbamate groups were synthesized and polymerized by using (Rh(norbornadiene)Cl)2 as an initiator. The resulting polymers had very high average molecular weights (Mw) of 1.4-4.8 × 106, with different solubility and membrane-forming abilities. The polymer having two carbamate groups and no hydroxy groups in the monomer unit showed the best solubility and membrane-forming ability among the three polymers. In addition, the oxygen permeability coefficient of the membrane was more than 135 times higher than that of a polymer having no carbamate groups and two hydroxy groups in the monomer unit with maintaining similar oxygen permselectivity. A better performance in membrane-forming ability and oxygen permeability may be caused by a more extended and flexible cis-transoid conformation and lower polarity. On the other hand, the other two new polymers having one carbamate group and two hydroxy groups in the monomer unit showed lower performances in membrane-forming abilities and oxygen permeabilities. It may be caused by a very tight cis-cisoid conformation, which was maintained by intramolecular hydrogen bonds.

Electrodeposited Pd/graphene/ZnO/nickel foam electrode for the hydrogen evolution reaction.

Efficient electrocatalysts are crucial to water splitting for renewable energy generation. In this work, electrocatalytic hydrogen evolution from Pd nanoparticle-modified graphene nanosheets loaded on ZnO nanowires on nickel foam was studied in an alkaline electrolyte. The high electron mobility stems from the cylindrical ZnO nanowires and the rough surface on the graphene/ZnO nanowires increases the specific surface area and electrical conductivity. The catalytic activity arising from adsorption and desorption of intermediate hydrogen atoms by Pd nanoparticles improves the hydrogen evolution reaction efficiency. As a hydrogen evolution reaction (HER) catalyst, the Pd/graphene/ZnO/Ni foam (Pd/G/ZnO/NF) nanocomposite exhibits good stability and superior electrocatalytic activity. Linear sweep voltammetry (LSV) revealed an overpotential of -31 mV and Tafel slope of 46.5 mV dec-1 in 1 M KOH. The economical, high-performance, and environmentally friendly materials have excellent prospects in hydrogen storage and hydrogen production.

MnO2/ZnCo2O4 with binder-free arrays on nickel foam loaded with graphene as a high performance electrode for advanced asymmetric supercapacitors.

ZnCo2O4 nanosheets were successfully arrayed on a Ni foam surface with graphene using a hydrothermal method followed by annealing treatment; then MnO2 nanoparticles were electrodeposited on the ZnCo2O4 nanosheets to obtain a synthesized composite binder-free electrode named MnO2/ZnCo2O4/graphene/Ni foam (denoted as MnO2/ZnCo2O4/G/NF). After testing the binder-free composite electrode of MnO2/ZnCo2O4/G/NF via cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy testing, we found that it exhibited ultrahigh electrochemical properties, with a high specific areal capacitance of 3405.21 F g-1 under a current density of 2 A g-1, and wonderful cycling stability, with 91.2% retention after 5000 cycles. Moreover, an asymmetric supercapacitor (ASC) based on MnO2/ZnCo2O4/G/NF//G/NF was successfully designed. When tested, the as-designed ASC can achieve a maximum energy density of 46.85 W h kg-1 at a power density of 166.67 W kg-1. Finally, the ASC we assembled can power a commercial red LED lamp successfully for more than 5 min, which proves its practicability. All these impressive performances indicate that the MnO2/ZnCo2O4/graphene composite material is an outstanding electrode material for electrochemical capacitors.

New Synthetic Methods of Novel Nanoporous Polycondensates and Excellent Oxygen Permselectivity of Their Composite Membranes.

Two kinds of novel nanoporous polycondensates (sc(Rf)) have been synthesized by two new preparation methods consisting of polycondensation and highly selective photocyclicaromataization of 1/3 helical cis-cis polyphenylacetylenes with polymerizable groups. By the original methods, new well-defined sheet polymers having nanopores or nanospaces have been synthesized for the first time. Their composite membranes, containing small amounts (1.0 wt%) of sc(Rf), had ultrahigh oxygen permeability (Po2 > 1000 barrer), and their plots were beyond the Robeson's upper bound line in the graph of oxygen permselectivity (α = Po2/PN2) versus Po2. Both α and Po2 values were enhanced by adding only small amounts (1.0 wt%) of sc(Rf). One of the sc(Rf)s synthesized on the base membrane surface showed the best performance, i.e., Po2 = 5300 barrer and α = 2.5. The membrane surface was effectively covered by sc(Rf), judging from the contact angle values. It is thought that nanopores and nanospaces created in and between sc(Rf) molecules played an important role for the enhancement of both α and Po2/PN2.

Hybrid ZnO-graphene electrode with palladium nanoparticles on Ni foam and application to self-powered nonenzymatic glucose sensing.

A self-powered nonenzymatic glucose sensor electrode boasts the advantages of both a glucose sensor and fuel cell. Herein, an electrode composed of ZnO-graphene hybrid materials on nickel foam (NF) is prepared by electrodeposition of Pd NPs. The electrode is characterized systematically and the dependence of electrocatalytic oxidation of glucose on the concentrations of KOH and glucose, temperature, and potential limit in the anodic direction is investigated. The Pd/NF-ZnO-G electrode shows high catalytic activity, sensitivity, stability, and selectivity in glucose detection, as exemplified by an electrocatalytic glucose oxidation current of 222.2 mA cm-2 under alkaline conditions, high linearity in the glucose concentration range from 5 µM to 6 mM (R 2 = 0.98), and high sensitivity of 129.44 µA mM-1-1 cm-2. The Pd/NF-ZnO-G electrode which exhibits superior electrocatalytic activity under alkaline conditions has large potential in nonenzymatic glucose sensing and direct glucose fuel cells and is suitable for miniaturized self-powered nonenzymatic glucose sensing.

Synthesis of soluble oligsiloxane-end-capped hyperbranched polyazomethine and their application to CO2/N2 separation membranes.

Three soluble hyperbranched polyazomethines containing oligosiloxane end group HBP-PAZ-SiOn were successfully synthesized. HBP-PAZ-SiOns were used as modifiers of ethyl cellulose (EC) and polysulfone (PS) membranes. Blend membranes, HBP-PAZ-SiOn /EC and HBP-PAZ-SiOn /PS were prepared by blending the THF solution of HBP-PAZ-SiOn with ethanol solution of EC and dichloromethane solution of PS, respectively. Surprisingly, the permeabilities for CO2 of the blend membranes were more than 15-16 times higher than those of pure EC and PS membranes without any drop of pemselectivity to N2. This unusual improvement has been achieved by both enhancement of diffusivity for carbon dioxide and nitrogen by the oligosiloxane groups and enhancement of affinity of the amino groups with carbon dioxide at the end groups of HBP-PAZ-SiOn .

Preparation and electrochemistry of Pd-Ni/Si nanowire nanocomposite catalytic anode for direct ethanol fuel cell.

A new silicon-based anode suitable for direct ethanol fuel cells (DEFCs) is described. Pd-Ni nanoparticles are coated on Si nanowires (SiNWs) by electroless co-plating to form the catalytic materials. The electrocatalytic properties of the SiNWs and ethanol oxidation on the Pd-Ni catalyst (Pd-Ni/SiNWs) are investigated electrochemically. The effects of temperature and working potential limit in the anodic direction on ethanol oxidation are studied by cyclic voltammetry. The Pd-Ni/SiNWs electrode exhibits higher electrocatalytic activity and better long-term stability in an alkaline solution. It also yields a larger current density and negative onset potential thus boding well for its application to fuel cells.