We propose a wideband linear polarization converter in transmission mode by bilayer metamaterial. The polarization converter operates from 0.55 to 1.37 THz with polarization conversion ratio maintaining nearly 100%. The distribution of surface current and electrical field was numerically simulated to clarify physical mechanism of polarization conversion. Importantly, we introduced the Stokes method to assess the polarization state of transmitted converter. The Fabry-Pérot-like cavity model was established to reveal the enhancement of polarization conversion ratio. The clear expressions including ideal and approximate model were deduced to provide an excellent explanation of Fabry-Pérot cavity in subwavelength bilayer metamaterials structure.
Abstract We propose a multiband metamaterial absorber consisting of silicon brick array on metal substrate in infrared range. Using the regular hexagon array of silicon bricks, the absorption rate can reach to 90% over the bandwidth of 100 nm, and four absorption peaks with the absorption rate of more than 98% can be obtained. The absorber is independent on polarization angle. The multiband absorption performance can be attributed to primary cavity mode and Mie resonance in silicon bricks. Importantly, when the all‐dielectric silicon bricks are replaced by metal‐dielectric‐metal sandwich structure, the absorption rate above 75% with the bandwidth of more than 200 nm in the absorber can be realized, and it is polarization‐insensitive. The absorption peaks are increased to obtain broadband absorption. Our designed sandwich microstructure can generate the resonance effect of magnetic dipole among coupled layers, leading to the characteristics of broadband absorption.
We propose and experimentally demonstrate a high quality (Q)-factor all-silicon bound state in the continuum (BIC) metasurface with an imperforated air-hole array.The metasurface supports two polarization-insensitive BICs originated from guided mode resonances (GMRs) in the frequency range of 0.4 to 0.6 THz, and the measured Q-factors of the two GMRs are as high as 334 and 152, respectively.In addition, the influence of the thickness of the silicon substrate on the two resonances is analyzed in detail.The proposed all-silicon THz metasurface has great potential in the design and application of high-Q metasurfaces.
We have studied the absorption spectral of L-and DL-fudosteine using terahertz time-domain spectroscopy (THz-TDS) at room temperature. The results show that both of them have unique absorption fingerprint peaks in terahertz range and can be identified by these peaks. The absorption spectrum of the fudosteine capsule has also been studied. Its absorption spectrum is similar to that of L-fudosteine. Thus, it proves that the main component of fudosteine capsule is L-fudosteine. The study indicates that THz-TDS technology is a new method to identify and analyze main components of material.
In the title compound, C(12)H(10)N(2)O, the dihedral angle between the pyridine ring system and the phenyl ring is 1.8 (1)°. There is an intra-molecular N-H⋯N hydrogen bond between the pyridine N atom and the amide NH function.
The role of exhaled breath condensate (EBC) metabolites in the effect of PM on schoolchildren's pulmonary function has received little attention. We were interested in the potential effects of PM (PM 10 , PM 2.5 , and PM 1 ) on metabolites related to inflammation, oxidative stress, and immune response in schoolchildren's EBC. Air cleaners equipped with and without high-efficiency filter gauzes were tested on sixty schoolchildren residing in a boarding primary school. To evaluate lung ventilation function, pulmonary function testing was performed. To detect the metabolites in EBC, untargeted metabolomics methods were used. To assess the relationship between exposure and effects, including pulmonary function and metabolites, the linear mixed-effect model was used. We then investigated the role of these metabolites in mediating the effect of PM on pulmonary function. Following the metabolomics and correlation analysis processes, 51 metabolites were screened out. Among them, 47 metabolites were linked to PM 1 , 49 to PM 2.5 , and 35 to PM 10 . The magnitude of metabolite changes in boys was more significant than in girls. The study discovered that seven inflammatory, oxidative stress, and energy metabolism-related metabolites played a role in mediating the effect of PM on pulmonary function in boys, these metabolites were 4-hydroxynonenal, myristic acid, heptadecanoic acid, palmitic acid, naphthalene, linoleic acid, and 2-furoic acid, while in girls there are three mediate metabolites, 5-deoxy-D-glucose, 4-hydroxynonenal, and phthalic acid, respectively. The results showed that using air cleaners could reduce indoor PM concentrations and also normalizing pulmonary function by lowering inflammation, oxidative stress, and immune levels while increasing glutathione antioxidant levels. There are gender differences in response to PM exposure, with boys responding more strongly than girls.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Beijing-1satellite(DMC+4 microsatellite) was launched on October 27th 2005,which covers a large area and has outstanding ability of continual observation.The vegetation fractional coverage is an important parameter for describing vegetation quality and indicating ecosystem change.In this study,Beijing-1,SPOT5 and QuickBird images were integrated to detect and analyze the vegetation fractional coverage in riparian buffer zones of Guanting Reservoir.On the basis of integrated detection,scale transforming method was used between three images to improve the precision of vegetation fractional coverage measured by Beijing-1 image.The concrete methods are pixel decomposability method and statistic model establishment,that is,SPOT5 and QuickBird pixels were used to decompose Beijing-1 image pixel,and then established the statistic models between decomposability results and vegetation fractional coverage measured byBeijing-1 image.The results show that:(1) The correlation coefficients of vegetation fractional coverage between Beijing-1,SPOT5 and QuickBird images are high,which suggests that using Beijing-1 image to detect vegetation fractional coverage of riparian buffer zones of Guanting reservoir is feasible.(2) Using these statistic models can effectively improve the precision of vegetation fractional coverage measuring from Beijing-1 image.For reed marshes,compared with the result of using vegetation fractional coverage calculation equation,the mean absolute error of vegetation fractional coverage measured by Beijing-1 image was reduced by 22.7% after applying statistic models.This is a practice on scale transformation of remotely sensed data.(3) Expanding the application extent,pixel decomposability method and statistic model establishment are feasible in enhancing the application precision of lower spatial resolution remotely sensed data by using high spatial resolution remotely sensed data.The integrated application of multi-scale remotely sensed data is a significant approach to promote the precision of acquiring earth surface parameters on large scale.This has become a development trend of remote sensing technology.
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