- 标题
- 摘要
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- 实验方案
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Wavelength selection of the multispectral lidar system for estimating leaf chlorophyll and water contents through the PROSPECT model
摘要： The estimation of leaf biochemical constituents is of high interest for the physiological and ecological applications of remote sensing. The multispectral lidar (MSL) system emerges as a promising active remote sensing technology with the ability to acquire both three-dimensional and spectral characteristics of targets. The detection wavelengths of the MSL system can be geared toward the specific application purposes. Therefore, it’s important to conduct the wavelength selection work to maximize the potential of the MSL system in vegetation monitoring. Traditional strategies of wavelength selection attempt to establish an empirical relationship between large quantities of observed reflectance and foliar biochemical constituents. By contrast, this study proposed to select wavelengths through the radiative transfer model PROSPECT. A five-wavelength combination was established to estimate leaf chlorophyll and water contents: 680, 716, 1104, 1882 and 1920 nm. The consistency of the wavelengths selected were tested by running different versions of PROSPECT model. Model inversion using simulated and experimental datasets showed that the selected wavelengths have the ability to retrieve leaf chlorophyll and water contents accurately. Overall, this study demonstrated the potential of the MSL system in vegetation monitoring and can serve as a guide in the design of new MSL systems for the application community.
关键词： Multispectral lidar,Wavelength selection,Leaf water content,Leaf chlorophyll content,PROSPECT model
更新于2025-09-04 15:30:14
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Carbon Nitride Dots: A Selective Bioimaging Nanomaterial
摘要： In contrast to the recent immense attention in carbon nitride quantum dots (CNQDs) as a heteroatom-doped carbon quantum dot (CQD), their biomedical applications have not thoroughly investigated. The targeted cancer therapy is a prominently researched area in biomedical field. Here, the ability of CNQDs as a selective bioimaging nanomaterial was investigated to assist the targeted cancer therapy. CNQDs were first synthesized using four different precursor sets, involving urea derivatives and the characteristics were compared to select the best candid material for bioapplications. Characterization techniques such as UV-vis, luminescence X-ray photoelectron spectroscopy, nuclear magnetic resonance spectroscopy and transmission electron microscopy were used. These CNQDs were analyzed in in vitro studies of bioimaging and labeling using pediatric glioma cells (SJGBM2) for possible selective biolabeling and nano-distribution inside the cell membrane. The in vitro cellular studies were conducted under long-wavelength emission without the interference of blue autofluorescence. Thus, excitation-dependent emission of CNQDs was proved to be advantageous. Importantly, CNQDs selectively entered SJGBM2 tumor cells while it did not disperse in to normal human embryonic kidney cells (HEK293). The distribution studies in the cell cytoplasm indicated that CNQDs disperse into lysosomes within approximately 6 h after the incubation. The CNQDs exhibited great potential as a possible nanomaterial in selective bioimaging and drug-delivery for targeted cancer therapy.
关键词： Pediatric glioma cells,Long-wavelength emission,Urea derivatives,Carbon nitride Quantum dots,Fluorescence,Selective bioimaging
更新于2025-09-04 15:30:14
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Enhanced absorption of graphene with variable bandwidth in quarter-wavelength cavities
摘要： Quarter-wavelength cavity, as a classical structure for preventing wave re?ection, presents an effective way to enhance the interaction between light and material of ultrathin thickness. In this paper, we propose a method to control the bandwidth of graphene’s enhanced absorption in quarter-wavelength cavity. By varying the spacing distance between graphene and a metallic re?ecting plane, which equals to an odd number of quarter-wavelengths, fundamental and higher order cavity modes are excited, whose ?elds couple to graphene with different spectral bandwidths, leading to bandwidth-controllable absorption in graphene. Absorption ef?ciencies of 9% and 40% are measured for graphene monolayer at 15? and 85? incident angles, respectively. Its absorption bandwidth varies between 52% and 10% of the central wavelength when the spacing distance between graphene and metallic re?ecting plane increases from a quarter wavelength to seven quarter wavelengths. Our ?ndings pave a way in engineering graphene for strong absorption with a controllable bandwidth, which has potential applications in tailoring spectral response of graphene-based optoelectronic devices.
关键词： quarter-wavelength cavity,bandwidth control,enhanced absorption,graphene
更新于2025-09-04 15:30:14
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DESIGN OF NOVEL COMPACT TRI-BAND BANDPASS FILTER WITH CONTROLLABLE FREQUENCIES AND HIGH SELECTIVITY
摘要： This paper presents a compact tri-band bandpass ?lter (BPF) with high selectivity. The proposed ?lter utilizes novel stub-loaded quarter-wavelength resonators and conventional uniform quarter-wavelength resonators. The latter is embedded in the former, and they are separated by a feed line. Due to these quarter-wavelength resonators, the total size is greatly reduced. Moreover, the passband frequencies can be controlled individually. To enhance its selectivity, source-load coupling is employed. For demonstration, an experimental ?lter is implemented. High skirt selectivity and suppression levels are observed in the measured results. The circuit area of the ?lter is 0.17λg × 0.19λg, featuring compact size.
关键词： high selectivity,compact size,stub-loaded quarter-wavelength resonators,tri-band bandpass filter,source-load coupling
更新于2025-09-04 15:30:14