- 标题
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Harnessing the synergy between upconverting nanoparticles and lanthanide complexes in a multi-wavelength responsive hybrid system
摘要： We prepared a hybrid system composed of a continuous film of dinuclear lanthanide complex [Ln2bpm(tfaa)6] (Ln = Tb or Eu) and upconverting nanoparticles (UCNPs) using a straightforward drop-cast methodology. The system displayed visible emission under near-infrared (NIR) excitation, simultaneously stemming from sub-10-nm UCNPs and [Ln2] complexes, the latter species being otherwise directly excitable only using UV-blue radiation. In light of the results of steady-state – including power-dependent – and time-resolved optical measurements, we identified the radiative, primarily ligand-mediated nature of the energy transfer from Tm3+ ions in the UCNPs-to-Ln3+ ions in the complexes. Hyperspectral mapping and electron microscopy observations of the surface of the hybrid system confirmed the continuous and concomitant distribution of UCNPs and lanthanide complexes over the extensive composite films. Key features of the hybrid system are the simultaneous UV-blue and NIR light harvesting capabilities and their ease of preparation. These traits render the presented hybrid system a formidable candidate for the development of photoactivated devices capable to operate under multiple excitation wavelength and to transduce the absorbed light into narrow, well-defined spectral regions.
关键词： hybrid system,complex,energy transfer,lanthanide,films,upconverting nanoparticles,hyperspectral imaging
更新于2025-09-23 15:23:52
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[IEEE 2018 18th International Symposium on Communications and Information Technologies (ISCIT) - Bangkok, Thailand (2018.9.26-2018.9.29)] 2018 18th International Symposium on Communications and Information Technologies (ISCIT) - High-Accuracy Phase-Compensating System Design Using Successively Linearized Constraints
摘要： This paper develops a new iterative algorithm for the design of an all-pass phase-compensating filter (AP-PCF). This design algorithm employs the linear programming method through successively linearizing the nonlinear constraints as linear ones, and the AP-PCF is designed using the minimax criterion. The resulting AP-PCF is useful in the compensation of phase distortions of a variety of nonlinear-phase digital systems including digital communication channels. The basic idea of this design algorithm is to successively convert the nonlinear design constraints into linear ones and thus the design problem becomes a linear optimization problem. Based on such a problem conversion, the obtained linear optimization problem can be easily solved. A computer simulation example is given for showing the accuracy enhancement.
关键词： non-linear phase channel,phase-compensating filter,all-pass digital system,Digital communications
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Cleveland, OH, USA (2018.10.17-2018.10.19)] 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS) - Gaussian Monocycle Pulse Generator with Calibration Circuit for Breast Cancer Detection
摘要： Gaussian Monocycle Pulses (GMP) play a very important role in a radar-based painless breast cancer detection system. In order to guarantee the detection accuracy, it is necessary to stabilize the pulse width and the amplitude under the influence of the manufacturing variation of MOSFETs. Therefore, in this paper, the GMP generator with a calibration circuit is proposed. The calibration circuit for adjusting the delay time of each path is realized by MOS capacitor array. The proposed GMP generator has a center frequency of 5.5 GHz, -3dB bandwidth from 2.8 GHz to 9.1 GHz, and 498.6 μW power consumption.
关键词： Gaussian Monocycle Pulse (GMP),equivalent time sampling,breast cancer detection system,calibration circuit
更新于2025-09-23 15:23:52
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Incoherent Range Walk Compensation for Spaceborne GNSS-R Imaging
摘要： Global navigation satellite system reflectometry (GNSS-R) receivers produce delay-Doppler maps (DDMs) by incoherently integrating coherent integration results. Due to system dynamics, during incoherent integration, the receiver aligns each coherent result by tracking the delay and Doppler of the specular point. This is known to cause a blurring of the spatial footprint of the Woodward ambiguity function (WAF) on the reflecting surface. In this paper, we demonstrate that the blurring of the WAF varies over the glistening zone (GZ), and even if a fixed point on the ground is tracked, blurring still occurs. We derive the expressions for the delay and Doppler change rates over the GZ and then predict the error introduced by range walk for typical GNSS-R scatterometry configurations. We find that ≈6 dB of loss is expected for a point scatterer near the edge of the GZ when a fixed point on the surface is tracked. The incoherent range walk compensation (IRWC) method is then presented for GNSS-R receivers to mitigate this loss. The IRWC method focuses the power in the DDM to the isodelay and iso-Doppler configuration occurring at the midpoint of the integration time. DDMs produced by tracking a fixed point with and without IRWC are simulated, and errors are found to be in agreement with those predicted. Spatial domain GNSS-R products will be improved with IRWC. Target detection will benefit from a larger usable swath, allowing longer tracking and detection times as a result of the increased target to clutter and noise ratio. At the same time, imaging applications will no longer suffer from a spatially variant blurring of the WAF, which limits the resolution of the estimated products. IRWC is shown to mitigate the range migration losses and improve the SNR of an imaging GNSS-R receiver by ≈6 dB near the edge of the GZ.
关键词： integration,global navigation satellite system reflectometry (GNSS-R),reflectometry,imaging,target detection,receiver,incoherent range walk compensation (IRWC),Dynamic corrections
更新于2025-09-23 15:23:52
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The role of incidence angle in the morphology evolution of Ge surfaces irradiated by medium-energy Au ions
摘要： Germanium (Ge) surfaces have been irradiated with 26 keV gold (Au) ions at a constant fluence and at incidence angles varying from 0° to 85°. The evolution of the emerging nanostructures is studied by atomic force microscopy (AFM), scanning electron microscopy, x-ray photoelectron spectroscopy (XPS), and cross-sectional transmission electron microscopy. The obtained results are compared with findings reported in the literature. Periodic rippled patterns with the wave vector parallel to the projection of the ion beam direction onto the Ge surface develop between 30° and 45°. From 75° the morphology changes from parallel-mode ripples to parallel-mode terraces, and by further increasing the incidence angle the terraces coarsen and show a progressive break-up of the front facing the ion beam. No perpendicular-mode ripples or terraces have been observed. The analysis of the AFM height profiles and slope distributions shows in the 45°–85° range an angular dependence of the temporal scale for the onset of nonlinear processes. For incidence angles below 45°, the surface develops a sponge-like structure, which persists at higher incidence angles on the top and partially on the face of the facets facing the ion beam. The XPS and the energy-dispersive x-ray spectroscopy evidence the presence of Au nano-aggregates of different sizes for the different incidence angles. This study points out the peculiar behavior of Ge surfaces irradiated with medium-energy Au ions and warns about the differences to be faced when trying to build a universal framework for the description of semiconductor pattern evolution under ion-beam irradiation.
关键词： ion beam irradiation,gold ions,terraces,germanium,binary system,sponge-like structures,ripples
更新于2025-09-23 15:23:52
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Interaction between in-gap states and carriers at the conductive interface between perovskite oxides
摘要： The 2D electron systems of SrTiO3/NdGaO3 (STO/NGO) and amorphous-LaAlO3/SrTiO3/NdGaO3 (a-LAO/STO/NGO) heterojunctions were explored. An obvious interaction between in-gap states (IGSs) and carriers was found. The IGSs can trap a large number of carriers and enhance carrier scattering. As a result of the high density of IGSs in STO, the conductivity of STO/NGO was severely weakened. However, for a-LAO/STO/NGO heterojunctions, the high carrier density can reduce the effect of IGSs through the electrostatic screening effect. The competition between IGSs and the screening effect of carriers results in an insulator–metal transition and a strange temperature dependence of carrier density. We also explored the interaction between IGSs and carriers theoretically. A mathematical description was proposed and the calculated results showed good agreement with experimental findings.
关键词： in-gap states,perovskite oxides interface,2D electron system,electrostatic screening effect
更新于2025-09-23 15:23:52
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Growth of perovskite nanocrystals in poly-tetra fluoroethylene based microsystem: On-line and off-line measurements
摘要： Cesium lead halide perovskite nanocrystals are photoelectric nanomaterials that have potential applications in a variety of areas due to their excellent photoelectric and tunable photo luminescent properties. In this work, we investigate the synergetic effects of reaction temperature, reaction-capillary length and flow rate on the growth kinetics of perovskite nanocrystals in PTFE-based microsystem and the photoluminescence characteristics of the synthesized nanocrystals both online and offline. The on-line measurement finds that increasing the reaction temperature leads to the increase of the wavelength of the PL emission peak of the nanocrystals synthesized at different reaction temperatures decreases with the increase of the flow rate. The off-line measurement reveals that increasing the flow rate generally leads to the blueshift of the PL emission peaks and the decrease of the average size of the perovskite nanocrystals synthesized at the reaction temperature of 160 oC in the capillary length of 60 cm. Increasing temperature leads to the increase of the emission wavelength of the perovskite nanocrystals from 560 nm to 608 nm. The temperature dependence of the average size of the synthesized nanocrystals with the same synthesis conditions at different temperatures can be described by the Arrhenius relationship with an activation energy of 8.54 kJ/mol. Five different cross-sections of the synthesized perovskite nanocrystals are observed, including rhombus, hexagon, rectangle, square and quadrangle with three of them being observed for the first time.
关键词： microreaction system,morphologies,growth kinetics,reaction parameters,perovskite nanocrystal
更新于2025-09-23 15:23:52
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Superradiance and Collective Gain in the Atom-Assisted Multimode Optomechanical System
摘要： We investigate that the muti-mode optomechanical system coupled with the two-level atoms. If the driving pump field is resonance with the anti-Stokes sideband, the system is at the superradiative state. For the driving filed in the Stokes sideband, the collective gain can be observed. We study a scheme that how the atomic medium affect these superradiance and collective gain. Our results show that the presence of the atom can enhance the superradiant behavior. In the mode splitting regime, the mode splits into thirds with the presence of the atoms with the anti-Stokes sideband. In addition, we also show that the use of atoms in this system could provide us a way to switch the system form superradiative state to collective gain.
关键词： Anti-stoke sideband,Stokes sideband,Atoms,Collective gain,Superradiance,Optomechanical system
更新于2025-09-23 15:23:52
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In-situ synthesis of mullite-SiCw composite ceramics in Li2O-Al2O3-SiO2 ternary system for solar heat transmission pipeline
摘要： Nano-SiC whiskers (nano-SiCw) were in-situ synthesized in Li2O-Al2O3-SiO2 ternary system for preparing highly densified mullite-SiCw composite ceramics used for solar heat transmission pipeline. Mechanisms on the in-situ synthesis of nano-SiCw in the ternary system were investigated and the impact of nano-SiCw on the performances of the composites had been studied. Results showed that the growth processes of nano-SiC whiskers in Li2O-Al2O3-SiO2 ternary system were dominated by liquid-solid (LS) mechanism and the Li2CO3 additive could improve the SiCw yield through increasing the content of liquid phase and lowering the liquid viscosity. Sample BS3 (with 2.22 wt% Li2CO3 additive) sintered at 1440 °C obtained the highest SiC content of 47.9%. Nano-SiC whiskers with a diameter of 20e30 nm were interlocking with rod-like mullite crystals to improve the mechanical properties of the composites, and sample BS1 sintered at 1420 °C showed the highest bending strength of 115.4 MPa. The in-situ synthesized SiCw also shew significant effects on improving the thermophysical properties of the composites and sample BS1 exhibited a 3.6 times higher thermal conductivity than that of blank sample B1 without the introduction of nano-SiCw.
关键词： Li2O-Al2O3-SiO2 ternary system,Thermal conductivity,Mullite-SiCw composite ceramics,Solar heat transmission pipeline,SiC whiskers
更新于2025-09-23 15:23:52
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[IEEE 2018 2nd School on Dynamics of Complex Networks and their Application in Intellectual Robotics (DCNAIR) - Saratov, Russia (2018.10.8-2018.10.10)] 2018 2nd School on Dynamics of Complex Networks and their Application in Intellectual Robotics (DCNAIR) - Autonomous Power Supply System of Magnetron Generators Group
摘要： The issues which emerge at autonomous power supply system development are considered. The objects of power supply are magnetron generators groups as part of technological complex with a distributed supply of microwave energy.
关键词： solar panels,wind generator,power supply system,diesel generator,magnetron
更新于2025-09-23 15:23:52