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Underwater source localization by deep neural networks (DNNs) is challenging since training these DNNs generally requires a large amount of experimental data and is computationally expensive. In this paper, label distribution-guided transfer learning (LD-TL) for underwater source localization is proposed, where a one-dimensional convolutional neural network (1D-CNN) is pre-trained with the simulation data generated by an underwater acoustic propagation model and then fine-tuned with a very limited amount of experimental data. In particular, the experimental data for fine-tuning the pre-trained 1D-CNN are labeled with label distribution vectors instead of one-hot encoded vectors. Experimental results show that the performance of underwater source localization with a very limited amount of experimental data is significantly improved by the proposed LD-TL.

Cross-ice acoustic information transmission is an effective means of communication in polar sea areas covered by ice. However, the channel is extremely complicated because of the combined influence of water, ice, and air. Based on the normal-mode theory, this paper establishes a cascade acoustic channel (CAC) model for the transmission of under-water acoustic waves across ice layer. The model cancalculate the displacement response of the ice layer's upper surface by separating the upward waves from normal modes in the water and multiplying it by at ransmission coefficient matrix. The relationship between the displacement response of the upper surface of ice layer and the acoustic frequency is calculated by the finite-element method, and the calculation result was consistent with that of the CAC model. To verify the applicability of the model, a cross-ice acoustic communication experiment was conducted in Songhua River in January 2019. Experimental results show the energy of the acoustic signals received by geo-phones is closely related to sound frequency and cross-ice acoustic communication is feasible. The result of present research is important for understanding cross-ice acoustic channel characteristics and developing future cross-ice acoustic communication in polar sea areas.

One-dimensional (1D) hierarchical WO3/BiOI p–n (WB) heterojunctions with different mass percentages of WO3 were fabricated through a precipitation process. Various analytical techniques were employed to characterize the resulting WB composites, and their photocatalytic properties were measured by the degradation of rhodamine B (RhB) and methylene blue (MB) under irradiation of visible light. The WB heterojunctions showed largely enhanced photocatalytic performance as compared to the pure photocatalysts. Notably, the degradation rate constant of RhB by WB-10 was 3.3 and 33.6 times higher than those of pure BiOI and WO3, respectively. The enhanced activity could be attributed to the hierarchical p–n heterostructures, which can supply more reaction sites and effectively promote the separation of photogenerated charge carriers, as confirmed by PL and photocurrent. Trapping experiments implied that holes (h+) and superoxide anion radicals (˙O2−) were the dominant active species for organic pollutants decomposition on the WB composites. This work may benefit the construction of hierarchical heterostructures with high photocatalytic efficiency.

The seismic method on ice provides rich information and a feasible technical way for acoustic study in ice-covered water. This paper presents a method to determine the modes in ice–water bi-layer waveguides. We achieve the purpose by deducing the scaled boundary formulation for solid and fluid layers then coupling them with the coupling matrix. The wave numbers and mode shapes are compared with the results of the finite element method. It shows that the configuration for ice–water bi-layer waveguide is of high precision. In underwater acoustic applications, the depth of water is comparatively large relative to ice thickness, which addresses the additional difficulty of accuracy in high frequency. The study on convergence is carried out, and approximate formulas are addressed based on the calculated results, giving a quick insight into piratical application.

Ho3+/Ce3+ co-doped K2YbF5 microcrystals were synthesized by solvent-thermal method. Under excitation of 980 nm laser diode, effectively visible and 2 μm-infrared luminescence of Ho3+ ion were obtained in the microcrystals. By changing Ce3+-ion doping concentration, the luminescence properties of visible and 2 μm emission were effectively regulated. At low Ce3+-ion doping level, the red and green upconversion emission obviously increases and decreases respectively with the increase of Ce3+-ion amount in the samples, meanwhile the intensity of 2 μm fluorescence changes very little. At high Ce3+-ion doping level, the intensities of the red and green emission both decrease with the increase of Ce3+-ion concentration, while the 2 μm emission intensity increases obviously. In the sample doped with 16% Ce3+ ion, the intensity of 2 μm emission is about 4.5 times that of the sample without Ce3+ ion, and the corresponding quantum efficiency is about 78.3%. The result is attributed to the influence of the different cross relaxation between Ho3+ and Ce3+ ion in luminescence process at low and high Ce3+-ion doping concentration. The corresponding luminescence mechanism and energy transfer process were discussed in detail.

The Ni-doped Y-type hexaferrites Ba0.5Sr1.5Zn2−xNixFe12O22 have been prepared using the solid-state technique. The X-ray diffraction patterns indicate that the lattice constant is increased as the Ni content raises, which can be ascribed to the different ionic radius of Zn2+ and Ni2+. All samples are polycrystalline with clear grain interface by means of scanning electron microscopy. The grain size is found to increase with an increase of Ni concentration. The magnetic properties of all samples show different Ni-substitution dependence and strongly depend on Ni content. The results indicate that the value of saturation magnetization increases to a maximum of 41.5 emu/g at x = 0.8, and then decreases with increasing Ni content. For low-doped Ni-substitution (x ≤ 0.8) specimens, the magnetic transition temperature associated with a screw to ferrimagnetic state increases, suggesting that magnetically induced ferroelectric polarization will be observed at high temperature even room temperature. Especially for x = 1.2 specimen, the stabilization of the ferroelectricity phase at a low magnetic field is expected in terms of the disappearance of phase boundary from the screw to intermediate-I. At the same time, the ferroelectric polarization can be maintained in a wide range of magnetic fields for Ni-doped samples. These results confirm that Ba0.5Sr1.5-based Y-type hexaferrite with different Ni-doped content have a great application prospect in magnetoelectric devices at high temperature and under low magnetic fields.

In this study, a series of BiOI/KTaO3 p–n heterojunctions were prepared via a facile in situ chemical bath strategy. The photocatalytic properties of the catalysts was tested by the degradation of Rhodamine B (RhB) and phenol under visible light irradiation. The BiOI/KTaO3 composites exhibited improved photocatalytic efficiency compared to the individual catalysts. In particular, 54 wt% BiOI/KTaO3 displayed the highest photocatalytic activity since it degraded 98.6% RhB within 30 minutes, while only 68.1% RhB was degraded over pure BiOI under identical conditions. In addition, the reaction kinetic constant of RhB degradation over 54 wt% BiOI/KTaO3 was approximately 2.56 and 115-fold larger than those of pure BiOI and KTaO3, respectively. The results of PL, photocurrent and EIS indicated that the improved photocatalytic efficiency could root in the p–n junction formed between BiOI and KTaO3, which was conducive to the separation and migration of photo-generated carriers. Furthermore, a free-radical capture experiment illustrated that h+ and ˙O2− were the key factors in the photodegradation of RhB.

Diabetes mellitus is the syndrome associated with metabolism having complicated pathogenesis and its morbidity rate is rapidly increasing every year. The present study investigated the preventive effect of salicin ether against type-2 diabetes and explored the underlying mechanism. Salicin ether reduced PPARγ-LBD level and transcriptional property of RXRα-PPARγ in 293T cells. The rosiglitazone significantly (p0.01) increased grease droplet accumulation in adipocytes in comparison to control adipocytes. Increased grease droplet accumulation by rosiglitazone in adipocytes was reversed on treatment with salicin ether in dose-dependent manner. Salicin ether treatment of the adipocytes effectively suppressed rosiglitazone induced expression of FAS, C/EBPα, aP2, and HMG-CoA genes. Treatment of the adipocytes with salicin ether led to a prominent decrease in rosiglitazone mediated increase in aP2, CHIP, and C/EBPα protein expression. The inhibitory effect of rosiglitazone on expression of p-Akt/t-Akt, PPARa, p-FoxO1/t-FoxO1, and p-AMPK/t-AMPK was significantly (p0.01) alleviated in the adipocytes by salicin ether. In summary, the present study demonstrated that salicin ether suppressed PPARγ activity and adipocyte differentiation. Moreover, the activation of FoxO1/Akt/AMPK was up-regulated and FAS/EBPα/aP2/HMG-CoA level inhibited by salicin ether in the adipocytes. Thus, salicin ether may be studied further for possible role in the treatment of diabetes.

In the context of building a low-carbon integrated energy city, the energy data of electricity, water, heat, gas and other in city belong to different public utility management departments, and there are information barriers and data privacy protection issues between different energy systems. Under the premise of ensuring data security, aiming at the problem of training algorithm models for different energy data, the energy edge collaboration architecture based on homomorphic encrypted federated learning is proposed firstly, and then the urban comprehensive energy federated learning model is established to realize the local training model and transmit the updated model parameters to the server. Finally, the prediction of multivariate short-term loads by federated learning framework training and centralized training neural network models is verified by comparative experiments, and the results prove the feasibility and superiority of urban integrated energy edge collaboration and privacy protection based on federated learning framework in the field of urban integrated energy.

In recent years, moving target detection methods based on low-rank and sparse matrix decomposition have been developed, and they have achieved good results. However, there is not enough interpretation to support the assumption that there is a high correlation among the reverberations after each transmitting pulse. In order to explain the correlation of reverberations, a new reverberation model is proposed from the perspective of scattering cells in this paper. The scattering cells are the subarea divided from the detection area. The energy fluctuation of a scattering cell with time and the influence of the neighboring cells are considered. Key parameters of the model were analyzed by numerical analysis, and the applicability of the model was verified by experimental analysis. The results showed that the model can be used for several simulations to evaluate the performance of moving target detection methods.

Cadmium sulfide (CdS), as a promising semiconductor photocatalyst, has been widely investigated in the hydrogen (H2) evaluation field from splitting water, in order to settle environmental problems and energy shortages. But serious photocorrosion and low visible light absorption limited its H2 production performance. In our work, we first synthesized inorganic-organic CdS-diethylenetriamine (CdS-DETA) nanosheets via microwave hydrothermal method. The small organic amine molecules will link normal CdS nanoparticles together to form nanosheets with large surface area, which can reduce overpotential of H2 evolution reaction and promoted the separation of photo-induced carriers. Then, the nickel sulfide (NiS) was deposited on the surface of CdS-DETA by a fast and simple photochemical method, demonstrating that the H2 production performance was further improved. Specifically, the best H2 production rate of NiS/CdS-DETA composite is up to 230.6 μmol·h−1 under visible light, which is 8.42 and 1.72 times as high as that of pure CdS nanoparticles and CdS-DETA hybrid, and even stronger than that of Pt/CdS-DETA (173.8 μmol·h−1). Moreover, the photocatalytic H2 evolution rate is still stable after 16 h of cycle testing. Besides, the photocatalytic mechanism using NiS as a cocatalyst has also been proposed, where NiS can effectively accelerate the separation of photoinduced holes and electrons for CdS-DETA. This work embodied a feasible method to design photocatalysts to convert sun light into clean H2 energy more efficiently and stably.

Inorganic-organic hybrid materials, a class of probable candidates for combining two counterparts into one structure could be beneficial for improving or combing the excellent electronic, magnetic, rigidity and thermal stability, and optical feathers of inorganic frameworks with diverse structure, processability, flexibility and good geometric controllability of organic molecules. Anchoring inorganic-organic hybrid materials with cocatalysts is a usually used strategy for enhancing their catalytic performance. However, noble metal cocatalysts always limit their practical application. Herein, we report that noble metal free cocatalyst of Ni2P decorated CdS-diethylenetriamine (CdS-DETA) can effectively overcome this limitation to achieve highly photocatalytic hydrogen production. The rapid microwave solvothermal synthesis of CdS-DETA (MCdS-DETA) process shortens reaction time, saves energy and lead to achieve highly photocatalytic activity due to its low crystallinity. When Ni2P decorated MCdS-DETA, The 0.4%Ni2P/MCdS-DETA exhibited the highest photocatalytic hydrogen evolution activity (6836 μmmol h−1 g−1), which is 4.14 times, 2.06 times and 1.34 times higher than traditional solvothermal CdS-DETA(TCdS-DETA), MCdS-DETA and Pt cocatalysted MCdS-DETA, respectively. The method reported here can be extended to other inorganic-organic hybrid materials, and develops new strategies for exploring inorganic-organic hybrid-based photocatalysts.

In this work, novel WO3(H2O)0.333/BiOI heterostructure photocatalyst was synthesized via in-situ solvothermal method. The crystal structure, morphology and optical property of as-prepared samples were investigated by X-ray diffraction (XRD), field emission electron microscope (FESEM), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) measurements. WO3(H2O)0.333/BiOI heterojunction showed excellent photocatalytic performance under visible light. The constant kapp of WO3(H2O)0.333/BiOI is 0.08599 min−1, which is 3.33 and 51.49 times greater than that of BiOI and WO3(H2O)0.333, respectively. Moreover, WO3(H2O)0.333/BiOI heterostructure also presented high photostability. Finally, the direct Z-scheme photocatalytic mechanism of WO3(H2O)0.333/BiOI was proposed.

Semiconductor heterojunction represents a family of promising photocatalysts for visible-light photocatalysis. In this work, a novel ternary g-C3N4/ZnS/SnS2 heterostructure has been designed and synthesized by a facile one-step hydrothermal method. The obtained ternary g-C3N4/ZnS/SnS2 heterostructures exhibited high photocatalytic activity in photodegradation of organic pollutants and photocurrent response irradiated by 410 nm LED light. The results demonstrated that the formation of the heterostructures can much improve the excellent photocatalytic activity if the lattice and energy level matching among the three semiconductors be satisfied, which causes efficient separation of photoinduced carriers, resulting in the high photodegradation of methylene blue (MB). As a result, the highest apparent rate constant Kapp of g-C3N4/ZnS/SnS2 hybrid is 0.148 min−1, which is 8.74, 3.22 and 37.01 times as high as that of pristine g-C3N4, SnS2 and ZnS, respectively.

Focusing on the potential value of narrow directivity of parametric sonar in underwater acoustic communication, a broadband recursive filtering modulation method is proposed in this paper to generate parametric array excitation signal. The idea is to design the transient waveform by reversing the relationship between the envelope of original wave and difference frequency wave with the recursive filter. The method could process broadband and unknown arbitrary waveform signal (such as voice, image and video signal) in real time to get almost undistorted packets with low computation complexity. The feasibility and efficiency of the proposed method are verified by pool and trial experiments. The single carrier underwater acoustic communication system based on parametric array is applied to test the method in a distributed network. Performance of the system is improved effectively since the approximately distortion-free and narrow directivity compared with the conventional broadcast underwater acoustic communication system in Dalian sea trial.

Nowadays, the increasing CO2 emissions have attracted widespread attentions and it is necessary to reduce CO2 emissions to solve the global warming problem. So photocatalytic reduction of CO2 into chemical fuels is a promising strategy. Here, a Z-scheme porous g-C3N4/Sn2S3-diethylenetriamine (Pg-C3N4/Sn2S3-DETA) composite without an electron intermediary is designed. Photocatalytic performance of the as-fabricated samples is investigated on the basis of photocatalytic CO2 reduction (PCR) to form CH4 and CH3OH. We find that the Z-scheme heterostructure photocatalysts show a higher PCR performance than Pg-C3N4 and Sn2S3-DETA. An optimized Pg-C3N4/Sn2S3-DETA heterostructure sample displays high CH4 production rate of 4.84 μmol h−1 g−1 and CH3OH-production rate of 1.35 μmol h−1 g−1 with 5% Pg-C3N4 content. The superior PCR performance could be ascribed to the special structure of a direct Z-scheme Pg-C3N4/Sn2S3-DETA photocatalyst, which is beneficial to efficient separation of electron-hole pairs. Density functional theory (DFT) calculation further confirms the presence of direct Z-scheme mechanism. This Z-scheme heterostructure photocatalyst with superior performance may inaugurate the perspective on a new promising hierarchy of materials on CO2 photoreduction.

Recently, cadmium selenide (CdSe) has been deeply studied because of its excellent photocatalytic hydrogen (H2) production performance. However, pure CdSe has poor stability and severe photocorrosion, which seriously affect its application prospect. In this work, we successfully deposit Bi2MoO6 on an inorganic-organic CdSe-diethylenetriamine (DETA) hybrid to design Bi2MoO6/CdSe-DETA composites by an in situ solvothermal method. The morphology, crystal structure, electrochemical properties, H2 evolution performance and the photostability of Bi2MoO6/CdSe-DETA composites are explored using various techniques. The results show that the as-prepared Bi2MoO6/CdSe-DETA composites exhibit excellent photocatalytic performance and photostability under visible light irradiation. Among them, the Bi2MoO6/CdSe-DETA hybrid system exhibits excellent photocatalytic H2 production performance (5.92 mmol g-1 h-1), which is approximately 3.6 and 1.8 times higher than that of pure CdSe and CdSe-DETA, respectively. After 4 cycles, the photocatalyst still maintains high H2 production. This study develops a new type of photocatalyst that can respond to visible light. This provides an effective way to solve the energy problem by using solar energy.

One-dimensional (1D) hierarchical WO

The underwater surveillance of harbors is challenging, as the reverberation-limited environment means that intruders with a weak target strength, such as autonomous underwater vehicles and frogmen, may be overlapped or even overwhelmed by reverberations. In recent years, developments in low-rank and sparsity theory have presented an innovative idea for intruder detection. This paper describes a method in which multi-frame data containing echoes of an intruder and reverberations are arranged in a matrix, and then the data matrix is decomposed to achieve detection. Based on this idea, the alternating direction method of multipliers (ADMM) is applied to the problem of intruder detection. The key parameters of ADMM are discussed and recommended values are given. The proposed method is validated and evaluated through a series of experiments.

Mo-ZrO2 alloys were prepared through hydrothermal synthesis and powder metallurgy process. Room temperature microstructures of these alloy plates were observed, while high temperature tensile strength and plasticity of them were tested above 1000 °C using a Gleeble-1500D thermal simulated test machine. Results have shown that ZrO2 particles were fine in the alloy and distributed at grain boundaries and within the grains. The second phase of ZrO2 particles demonstrated a pinning effect to retard recrystallization progress and thus enhance high temperature tensile stress and plasticity of the alloys effectively. Besides, the strengthening effect of the second phase in the alloy could also effectively improve its high temperature tensile stress. Under 1400 °C, maximum tensile stress of Mo-1.5%ZrO2 alloy was 1.5 times that of pure molybdenum, while the alloy plasticity also increased dramatically. The area shrinkage of Mo-1.5% ZrO2 alloy at 1400 °C was 5 times that of pure molybdenum.

The delafossite CuFeO2 anode materials have been successfully synthesized by hydrothermal process with different temperatures. The X-ray diffraction patterns reveal that two structural polytypes of CuFeO2 with 3R-CuFeO2 and 2H-CuFeO2 are obtained. The results of field-emission scanning electronic microscopy confirm that all CuFeO2 crystals display both hexagonal and rhyombohedral morphologies, which are in good agreement with XRD results. It can be clearly observed that particles sizes of CuFeO2 are increased and the size distributions of particles become broader as hydrothermal temperature increasing. Electrochemical results show that the CuFeO2 particles synthesized at 180 °C for 24 h display the best electrochemical performance and superior cycle performance. The CuFeO2 materials obtained at 180 °C for 24 exhibit a high reversible capacity and high-rate capability (a reversible capability of 390, 276, 185, 133, and 85 mA h g− 1 at 0.1, 0.2, 0.5, 1, 2C, respectively) with good cycling performance (approximate 6.8% capacity loss after 500 cycles at 1C with a capacity retention of 124 mA h g− 1). The excellent electrochemical performance can be attributed to the small particle size and narrow size distributions. It is believed that obtained CuFeO2 crystals as anode materials with high reversible capacity, good rate capability and cyclic stability may be potential candidates for applying in lithium-ion batteries.

Cadmium sulfide (CdS), is one of the superior visible-light-driven photocatalysts, and has a prosperous and practical future in hydrogen (H2) production from water splitting for addressing environmental problems, such as environmental contamination and energy shortage. But the inherent serious drawback of photocorrision always limits its photocatalytic performance. Here, we fabricated a layered nanojunction to enhance the H2 generation of the surface-fluorinated TiO2/CdS–diethylenetriamine (F–TiO2/CdS–DETA) system. The loading of F–TiO2 nanosheets (NSs) with exposed {001} facets on inorganic–organic CdS–DETA nanobelts (NBs) greatly improves the interfacial contact. The layered nanojunction structure efficiently inhibits the charge carriers’ recombination and enhances the H2 production stability of CdS. At an optimal ratio of 30%F–TiO2, the F–TiO2/CdS–DETA composite exhibits the highest H2 production rate of 8342.86 μmol h–1 g–1, which is 6.6 times and 1.7 times as high as that of CdS nanoparticles and CdS...

The design and control of effective, sustainable, cheap, and reusable photocatalysts are crucial to the development of solar energy conversion to hydrogen (H2) for solving environmental problems. The cadmium sulfide/diethylenetriamine (CdS/DETA) hybrid in a single crystalline structure was achieved by a solvothermal approach. The organic-inorganic CdS/DETA hybrid shows high performance and satisfactory stability for H2 production under visible-light irradiation. The synergetic chemical coupling effect between CdS and DETA leads to a marked increase in the H2 generation rate and the apparent quantum yield. H2-production rate of CdS/DETA24 under visible light illumination are 31.7% and 8059.5μmolg-1h-1, respectively, which is 3.5 times more than CdS nanorods without DETA. Our findings may give a promising method to improve CdS for efficient electron-hole separation, electron transferring and anticorrosion in photocatalytic process, which reforms the conventional organic-inorganic hybrid system.

Binary transition metal oxides have attracted great attention as high-performance electrode materials for lithium-ion batteries in recent years. Herein, monodisperse NiCo2O4 porous microcubes were prepared for the first time via a simple urea-assisted solvothermal method followed by a thermal decomposition process. The porous microcubes assembled by nanoparticles with a size of ca. 35 nm have an average edge length of 1.5 μm. Nitrogen sorption isotherms show that this structure possesses a high surface area of 26.26 m2 g−1 with an average pore diameter of 22.57 nm. The rich mesopores among NiCo2O4 microcubes not only provide a large electrode/electrolyte reaction interface, but also provide enough void space to accommodate the volume change and prevent electronic disconnection in the electrode material during cycling. Furthermore, primary nanoparticles with a smaller size within microcubes can facilitate rapid Li-ion transport. So, when the as-prepared porous NiCo2O4 microcubes are used as anode materials for Li-ion batteries, they exhibit high-rate capability and outstanding cyclability.

In recent years, machine learning has been prospectively performed in underwater acoustic ranging task. The scale of acoustic observation has a considerable impact in the performance of networks. In this paper, we propose a joint color spectrum and conditional generative adversarial network processing for underwater acoustic source ranging. The joint method maps acoustic observations into color images to extract features. Original images are fed into conditional generative adversarial network and vast images generated from the generator network could be regarded as an expansion of the training set. The feasibility and effectiveness of the joint method are verified through some statistical indexes. In addition, variational auto-encoder and principal component analysis are used to measure the similarity of generated and original data. The method yields a meaningful improvement for underwater acoustic source ranging.

In this paper, novel two dimensional (2D) Bi 2 MoO 6 @Ag 2 MoO 4 core-shell composites have been successfully prepared by two-step hydrothermal and in-situ generating process. The sheet-structured composites can not only shorten the distance between the charge carriers and active sites, but provide more active sites for photocatalytic performance. Coated Ag 2 MoO 4 nanoparticles on the surface of Bi 2 MoO 6 nanosheets at room temperature has been verified to be an effective approach to prepare 2D core-shell composites, which benefits the formation of large-area heterojunction and boosts the separation of charge carriers. Bi 2 MoO 6 @Ag 2 MoO 4 composites show excellent visible light photocatalytic performance and high stability. The apparent pseudo-first-order rate constant k app for Bi 2 MoO 6 @Ag 2 MoO 4 2:1 is 0.07255 min −1 , which is 7.2 and 10.4 times higher than that of Bi 2 MoO 6 (0.01010 min −1 ) and Ag 2 MoO 4 (0.00698 min −1 ), respectively. Furthermore, by trapping experiment for reactive species, we demonstrate that holes play a vital role in the process of photocatalytic degradation. Eventually, a reasonable photocatalytic mechanism is proposed.

In this paper, novel Z-scheme octahedral Cu 2 O/Ag 3 PO 4 composites are fabricated by a facile chemical method at low temperature. Field emission scanning electron microscope (FESEM), UV–Vis diffuse reflectance spectroscopy (DRS), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) are used to investigate the crystal structure and optical properties of the as-prepared nanocomposites. Photocatalytic activity of catalysts is displayed by methylene blue (MB) removal under visible light irradiation. The results show that photocatalytic performance of Cu 2 O/Ag 3 PO 4 is much higher than that of Cu 2 O and Ag 3 PO 4 , and the kinetic constant k app of MB degradation over Cu 2 O/Ag 3 PO 4 is 0.30447 min −1 , which is 7.0 and 2.1 times as high as those of Cu 2 O and Ag 3 PO 4 , respectively. Finally, the possible separation mechanism of electrons and holes is proposed.

Porous graphitic carbon nitride (Pg-C3N4) nanosheets have been prepared via thermal decomposition, and then novel 2D Pg-C3N4/BiOBr hybrid is designed by a facile hydrothermal process. The as-prepared Pg-C3N4/BiOBr hybrids are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–Vis diffuse reflectance spectroscopy (DRS). The results show that BiOBr tightly composited on the surface of Pg-C3N4. Enhanced electron and hole separation efficiency is confirmed by photoluminescence (PL) spectroscopy measurements and the photoelectrochemical evaluation. The photoactivity performance of Pg-C3N4/BiOBr is tested under visible-light irradiation, the result shows that coupling semiconductor of Pg-C3N4/BiOBr apparently enhances the photocatalytic activity. An optimal Pg-C3N4 content has been determined to be 20 wt%, corresponding to apparent pseudo-first-order rate constant kapp of 0.088 min−1, which is 3.7 times, 4.2 times and 7.3 times as high as that of Pg-C3N4, BiOBr and common g-C3N4, respectively. Furthermore, photocatalytic stability and mechanism of enhanced photocatalytic process are also investigated.

A novel hierarchical Ag2WO4/Ag/Bi2MoO6 ternary visible-light-driven photocatalyst was successfully synthesized by in situ doping Ag2WO4 with Bi2MoO6 nanosheets through a facile hydrothermal and photochemical process. The morphology, structure, optical performance and crystallinity of the products were measured by field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), UV–vis diffuse reflectance spectroscopy (DRS) and X-ray diffraction (XRD). The results showed that Ag2WO4/Ag was uniformly dispersed on the surface of Bi2MoO6 nanosheets. The photocatalytic performance of Ag2WO4/Ag/Bi2MoO6 heterostructures was evaluated by the degradation of methylene blue (MB) under 410 nm LED arrays. The ternary Ag2WO4/Ag/Bi2MoO6 nanocomposite exhibits higher photocatalytic activity than Bi2MoO6 and Ag2WO4. The synergistic effect of Ag2WO4 and Bi2MoO6 could generated more heterojunctions which promoted photoelectrons transfer from Ag2WO4 to Bi2MoO6, leading to the improvement of photocatalytic performance by photoelectrons-holes recombination suppression. At the same time, the surface plasmon resonance of Ag2WO4/Ag/Bi2MoO6 is another crucial reason for the high photocatalytic performance of organic pollutants degradation. And the 20 wt% Ag2WO4-loaded Bi2MoO6 shows the optimal photocatalytic performance in the degradation of MB. In addition, the ternary composites can be easily reclaimed by precipitation and exhibits high stability of photocatalytic degradation after five recycles.

In this paper, novel Z-scheme porous graphitic C3N4 (Pg-C3N4)/Ag3PO4 composite was synthesized by a facile and green method at room temperature. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and UV–vis diffuse reflectance spectroscopy (DRS) were used to characterize the structural, crystal and optical properties of the as-prepared nanocomposites. Photocatalytic activity of catalysts is evaluated by degrading methylene blue (MB) under visible light irradiation. The results showed that photocatalytic activity of Pg-C3N4/Ag3PO4 was much higher than that of Pg-C3N4 and Ag3PO4. The kinetic constant Kapp of MB degradation over Pg-C3N4/Ag3PO4 was 1.45 and 9.6 times as high as that of Ag3PO4 and Pg-C3N4, respectively. Finally, Z-scheme photocatalytic mechanism is proposed.

Three-dimensional (3D) micro/nano hierarchical structure semiconductor catalysts not only inherit the excellent properties of single nanometer-size building blocks resulting from their high specific surface area and high activity but also provide the merits of high dispersion and easy recovery of microstructures. Herein, the interlaced nanoflake-assembled flower-like hierarchical Ag/Cu2O composite microspheres have been prepared via a one-step, environmentally friendly solvothermal method. Such interlaced nanoflake-assembled flower-like hierarchical Ag/Cu2O composite microspheres show an excellent photocatalytic activity, which is 121 times faster than that of the commercial Cu2O powders, and is one of the highest reported to date in the Ag/Cu2O composite materials for the degradation of Methyl Orange (MO) under visible light illumination. Our experimental results for photodegradation of MO also indicate that the existence of Cu in the products does not favor high photocatalytic activity for Ag/Cu2O composites, which may be due to the existence of excess metal in the products which provides the recombination centers for electron–hole pairs. After five consecutive cycles, the photocatalytic activity of the interlaced nanoflake-assembled flower-like hierarchical Ag/Cu2O composite microspheres almost remains unchanged, indicating that they are photostable during the photodegradation of MO. Most importantly, such micrometer-sized overall structures of the interlaced nanoflake-assembled flower-like hierarchical Ag/Cu2O composite microspheres enable them to be recycled and reused easily from solution by natural settlement in a short time. These results suggest that the interlaced nanoflake-assembled flower-like hierarchical Ag/Cu2O composite microspheres had potential applications in visible light photocatalysis for environmental remediation.

In this study, a series of BiOI/KTaO

Reverberation is the unavoidable interference for an active sonar. It makes difficult to detect an underwater target. The theory of low-rank and sparse matrix decomposition provides a new idea for underwater target detection. Inspired by this theory, we propose a method via non-negative matrix factorization (NMF). The method first extracts the low-rank structure and then separates targets from reverberation through iterations. Simulation is performed to verify its feasibility and to evaluate with the ROC curve.

In the present work, a series of Ag2O/KNbO3 composite photocatalysts are prepared for the first time through an in situ growth method. The as-obtained samples are well characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV-vis absorption spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic properties of the samples are assessed by decomposition of rhodamine B (RhB) under visible-light excitation. The results demonstrate Ag2O/KNbO3 illustrated superior photocatalytic activity. The rate constant of RhB degradation over the optimal sample (Ag2O/KNbO3-6:1) exceeded 2.78 and 65 times higher than that of pure Ag2O and KNbO3, respectively. The improved photocatalytic activity could be due to the heterostructure of the catalyst, which enhance the visible light absorption capacity and the separation efficiency of photogenerated carriers. The quenching experiments of varied scavengers illustrated that •O2− and h+ were the primary active species in the decoloration of RhB.

The Co and Ti co-doped SrFe12O19 hexaferrites have been successfully synthesized via the sol–gel method. The X-ray diffraction patterns demonstrate that all doped samples are single-phase hexagonal crystal confirmed by Rietveld refinement. The results of field-emission scanning electronic microscopy reveal that the particle sizes increase obviously with increasing Co–Ti substitution rate. It can be clearly observed that the magnetic properties can be effectively tuned by the partial substitution of Fe with Co and Ti. The magnetization measurement manifests both saturation magnetization and coercivity drop with increasing Co–Ti concentration. Specifically, the coercivity falls substantially from about 1697 to 20 Oe with only a little decrease in the saturation magnetization as x increases from 0.5 to 1.5. The results indicate that low-doped Co–Ti substitution rates (x) make hexaferrites suitable for high density and perpendicular recording technology. It is worthy to note that the Co–Ti substituted samples can gradually turn the magnetocrystalline anisotropy from uniaxial to planar, and the transition point is near x = 1.5, which is beneficial to the formation of a conical magnetic structure to induce electric polarization. It is expected that Co–Ti co-doped hexaferrite Sr(CoTi)1.5Fe9O19 may be potential candidates for application based on the magnetoelectric devices.

To obtain the channel characteristics of acoustic information across ice propagation, a field experimental was conducted involving of cross-ice acoustic (CIA) direct-sequence spread spectrum communication. In the experiment, three single-component geophones installed on the surface of the ice layer were used to measure the vertical component of the particle displacement. For comparison, two hydrophones were used to measure the sound pressure for under-ice acoustic (UIA) communication. The experimental results are used to compare and analyze the characteristics of the two communication methods. This paper uses the normal model theory to calculate the acoustic signal propagation characteristics. The calculation results explain why (i) the acoustic speed of the signal received by the geophone is less than that in the water and (ii) the frequency characteristics of the UIA and CIA communication channels differ. Finally, the communication performance based on differential energy detector is analyzed, and the feasibility of CIA direct-sequence spread spectrum communication is verified.

In this paper, a large scale and facile process was proposed for fabricating uniform and cheap Cu/Ag/Ag 3 PO 4 core–shell coaxial nanowires at room temperature. Cu/Ag/Ag 3 PO 4 ternary nanowire photocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and ultraviolet–visible diffuse reflectance spectra (DRS). Photocatalytic tests displayed that the Cu/Ag/Ag 3 PO 4 heterostructures possessed a higher degradation rate of methylene blue than pure Ag 3 PO 4 and P25 under visible light irradiation. The enhanced photocatalytic performance could be attributed to effective separation of photogenerated carriers driven by photoinduced potential difference generated at the metal-semiconductor heterojunction interface. Repetitive tests showed that the Cu/Ag/Ag 3 PO 4 heterostructures maintained high stability over 5 cycles. This kind of cheap and high-efficient hybrid photocatalysts are expected to show considerable potential applications in pollution controlling.

In this paper, cobalt sulfide (CoS) in-situ hybridized with carbon nanotube (CNT) is achieved through a hydrothermal process with the presence of polyvinylpyrrolidone (PVP). The morphology and structure of CoS/CNT hybrids are investigated by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the product consists of CoS nanoparticles with the diameter of 30–50 nm that well dispersed on the outer surface of CNTs. Furthermore, CoS/CNT hybrid has shown excellent electrochemical capacitance and exhibited favorable electrochemical cycling stability with 93.4% capacitance retention over 1000 cycles. Therefore, the CoS/CNT hybrids can be considered as promising electrode materials for supercapacitor.

It's important to reduce recombination of electrons and holes and enhance charge transfer through fine controlled interfacial structure. In this work, novel graphitic-C3N4 (g-C3N4)/Ag2WO4/Ag ternary photocatalyst has been synthesized by deposition of Ag2WO4 onto g-C3N4 template and followed by sun light reduction of Ag2WO4 into Ag2WO4/Ag. As-prepared g-C3N4/Ag2WO4/Ag presented significantly enhanced photocatalytic performance in degrading methylene blue (MB) under 410 nm LED light irradiation. Metallic Ag0 is used as plasmonic hot spots to generate high energy charge carriers. Optimal g-C3N4 content has been confirmed to be 40 wt%, corresponding to apparent pseudo-first-order rate constant kapp of 0.0298 min−1, which is 3.3 times and 37.3 times more than that of pure g-C3N4 and Ag2WO4, respectively. This novel ternary g-C3N4/Ag2WO4/Ag structure material is an ideal candidate in environmental treatment and purifying applications.