- 标题
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Enhanced Photoelectrocatalytic H <sub/>2</sub> Evolution over Two-Dimensional MoS <sub/>2</sub> Nanosheets Loaded on Cu-Doped CdS Nanorods
摘要： Transition-metal ion doping and efficient decoration by using a co-catalyst have been proven to effectively inhibit the recombination of photogenerated electron-hole pairs and broaden the visible-light response region. Here, we have constructed MoS2 nanosheets decorated on a copper-doped CdS nanorod composite as a noble-metal-free photoelectrocatalyst. This kind of composite material was constructed through a simple solvothermal method. The morphology, structure, chemical states, photoelectrochemical properties, and other properties were tested by using a diverse range of analytical techniques. Owing to the Cu2 + doping and the excellent electron-capturing ability of MoS2, 5 % MoS2/Cu(cid:0) CdS (with 7 % Cu2 + doping in CdS) exhibits excellent hydrogen evolution reaction with a rate of 10.18 mmol h(cid:0) 1 g(cid:0) 1, which is about 48 times higher than that of pure CdS. A significant increase in the photoelectrochemical performance of the composite catalytic material benefits from the synergistic effect between CdS and MoS2 and fast interfacial charge transfer, owing to the Cu2 + doping. These findings provide a new thought for further research of the ion doping in photoelectrocatalytic field.
关键词： CdS,hydrogen evolution reaction,photoelectrochemical performance,MoS2,Cu2 + doping
更新于2025-09-04 15:30:14
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Polymeric Micelles Encapsulating a Small Molecule SO <sub/>2</sub> Fluorescent Probe Exhibiting Novel Analytical Performance and Enhanced Cellular Imaging Ability
摘要： Because of the limited knowledge on the relationship between molecular structure and analytical performance, developing a small molecule fluorescent probe with desirable response properties is usually a laborious work. On the other hand, the application of small molecule fluorescent probe in biological samples is always limited due to the unwanted interaction between dyes and biomacromolecules. Polymer micelles, thanks to its unique core?shell structure, may have the potential to improve these situations. However, utilization of polymer micelles to improve these situations is rarely explored. Herein, we engineered the first micellar SO2 nanoprobe Nano-Cz by self-assembly of a carbazole-based SO2 small molecule probe and an amphiphilic copolymer (DSPE-mPEG2000). The optical and cell imaging experiments revealed that Nano-Cz can work in 100% aqueous environment and act as an effective mitochondrial-targeting ratio SO2 nanoprobe. Compared with the single small molecule probe, Nano-Cz showed extraordinary large dynamic response range (0?0.7 mM vs 0?50 μM), eliminated signal interference from DNA and superior cellular imaging performance. These results clearly show the ability of polymer micelles in modulating sensors’ analytical performance and reducing the signal interference from the unwanted interaction between small molecule probe and biomacromolecule, indicating that polymer micelles encapsulating single small molecule probe can provide us an alternative strategy to explore sensors with various performance and promote the biological application of fluorescent sensors. In addition, we hope that more and more polymer micelles would be used to construct biosensors in the future.
关键词： sensing performance,biological application,sulfur dioxide,polymer micelles,fluorescent sensor
更新于2025-09-04 15:30:14
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Guiding the Design of Organic Photocatalyst for PET-RAFT Polymerization: Halogenated Xanthene Dyes
摘要： By examining structurally similar halogenated xanthene dyes, this study establishes a guiding principle for resolving structure?property?performance relationships in the photocontrolled PET-RAFT polymerization system (PET-RAFT: photoinduced electron/energy transfer?reversible addition?fragmentation chain transfer). We investigated the effect of the halogen substituents on the photophysical and electrochemical properties of the xanthene dyes acting as photocatalysts and their resultant effect on the performance of PET-RAFT polymerization. Consideration of the structure?property?performance relationships allowed design of a new xanthene photocatalyst, where its photocatalytic activity (oxygen tolerance and polymerization rate) was successfully optimized for PET-RAFT polymerization. We expect that this study will serve as a theoretical framework in broadly guiding the design of high performance photocatalysts for organic photocatalysis.
关键词： PET-RAFT polymerization,structure?property?performance relationships,oxygen tolerance,photocatalysts,halogenated xanthene dyes
更新于2025-09-04 15:30:14
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Generalised polarimetric whitening filter for polarimetric MIMO radar detection
摘要： The polarimetric multiple-input multiple-output (MIMO) radar utilises both the polarisation and spatial diversities, thus the generalised likelihood ratio test (GLRT) of the polarimetric MIMO radar exhibits better detection performance than the GLRT of the MIMO radar when the secondary data set is large enough. However, the secondary data set is often not enough in reality. In this instance, the good detection performance of the GLRT of polarimetric MIMO radar cannot be guaranteed any more. In this study, the authors propose three kinds of generalised polarimetric whitening filters (GPWFs) to improve the detection performance of polarimetric MIMO radar in the limited secondary data environment. They first present the signal models and the test statistics for the three GPWFs. Then they analyse the detection performance of the three GPWFs by simulation, and find the second GPWF performs the best. They further compare the detection performance of the second GPWF with those of the GLRT and non-coherent integration (NCI) detector. Simulation results show that the proposed second GPWF outperforms the GLRT and NCI in the limited secondary data environment.
关键词： polarimetric MIMO radar,limited secondary data environment,detection performance,generalised polarimetric whitening filters
更新于2025-09-04 15:30:14
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Secure Communication in Non-Geostationary Orbit Satellite Systems: A Physical Layer Security Perspective
摘要： Satellite communication systems serve as an indispensable component of wireless heterogeneous networks in 5G era for providing various critical civil and military applications. However, due to the broadcast nature and full accessibility of wireless medium, such systems exist serious security threats. As an effort to address this issue, this paper, for the first time, investigates the secure communication in a non-geostationary orbit (NGSO) satellite system from a physical layer security perspective. Specifically, we focus on the downlink of an NGSO satellite which provides services to a fixed earth station and is wiretapped by a fixed eavesdropper. We first apply three types of orbiting models to characterize the movement state of the satellite. Based on the orbiting models, we then provide theoretical analysis for the secure communication performance of such a system. The expressions of two fundamental performance metrics, secrecy capacity and secrecy outage probability, are derived in closed-form for any system time. Finally, we conduct extensive simulations to validate our theoretical performance analysis and illustrate the security performance in a practical NGSO satellite communication system.
关键词： Non-geostationary orbit satellite system,physical layer security,performance evaluation
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Atlanta, GA, USA (2018.10.31-2018.11.2)] 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Parasitic Capacitors' Impact on Switching Performance in a 10 kV SiC MOSFET Based Converter
摘要： In a converter based on 10 kV SiC MOSFETs, major sources of parasitic capacitance are the anti-parallel junction barrier schottky (JBS) diode, heat sink, and load inductor. A half bridge phase leg test setup is built to investigate these parasitic capacitors’ impact on the switching performance at 6.25 kV. Generally these parasitic capacitors slows down both turn-on and turn-off transient and can cause significant increase in switching energy loss. The impact of the parasitic capacitor in the load inductor is analyzed, which has either very short wire or long wire in series. Switching performance of the phase leg with two different thermal designs are compared to investigate the impact of the parasitic capacitor due to the heat sink. The large parasitic capacitor due to the large drain plate of discrete 10 kV SiC MOSFET for heat dissipation can result in 44.5% increase in switching energy loss at low load current.
关键词： 10 kV SiC MOSFET,parasitic capacitor,switching performance
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Krakow, Poland (2018.10.16-2018.10.18)] 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Performance and power consumption evaluation in smartphone based image processing for medical applications
摘要： More and more image processing applications are intended to run on mobile devices. This trend is visible also in medical industry, which have very strict reliability and safety requirements. Increased power consumption and inefficient image processing can affect both of these factors significantly. More over, it affects the user experience as well. In this paper authors investigates the performance and power consumption of several different numeric algorithms implemented on iPhone device. The comparison is made between CPU and GPU based solutions. Authors evaluated the test scenarios involving common used operations: matrix multiplication, thresholding and Canny’s edge detection. The results showed that GPU based solution can be up to 4 times faster as CPU based one, with similar power footprint in particular cases. All measurements have been gathered without hardware interference nor jailbreaking of the device. Finally authors discuss possible application considerations and scenarios in medical related image processing smartphone apps.
关键词： smart devices,performance evaluation,cybercare,image processing,user experience
更新于2025-09-04 15:30:14
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Novel polyimide nanocomposites enhanced by covalent modified graphene nanosheets based on Friedel–Crafts reaction
摘要： We report a new approach to fabricate novel polyimide (PI) nanocomposites using amine-functionalized graphene nanosheets (AGNS). AGNS was successfully prepared by Friedel–Crafts (F–C) reaction and nitroreduction. The PI nanocomposites with outstanding strength and high tribological performance were obtained though in situ polymerization in the presence of different contents of AGNS. The thermal stability, mechanical performance, and the tribological properties of PI/AGNS nanocomposites were significantly enhanced compared with that of pristine PI and PI/graphene nanosheets (GNS) blends, resulting from the strong covalent bonds between AGNS with PI matrix. Particularly, given that the friction coefficient and wear rate were reduced separately by 20.5% and 90.5% under dry sliding condition, the PI/AGNS nanocomposite with 0.5 wt% AGNS manifested the optative friction performance. The combined exclusive friction resistance and mechanical performance were the paramount factors which illustrate the applications of the resultant PI/AGNS nanocomposites in the wear-resistant field or another high-performance material.
关键词： graphene nanosheets,mechanical properties,polyimide nanocomposites,tribological performance,Friedel–Crafts reaction
更新于2025-09-04 15:30:14