In this work, a broadband absorber is designed for application in the terahertz region using graphene antidots array. The proposed absorber consists of an Au substrate, a polyethylene dielectric layer and a graphene s...
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In this work, a broadband absorber is designed for application in the terahertz region using graphene antidots array. The proposed absorber consists of an Au substrate, a polyethylene dielectric layer and a graphene sheet with antidot resonators. The geometrical dimensions of the antidot resonator and its array period, the graphene conductivity parameters and the dielectric layer height and refractive index are the parameters that determine the characteristics of the absorber such as bandwidth, centre frequency, the amount of the absorption and sensitivity to the incident wave incident angle and polarisation. The circuit theory and a broadband matching technique of the transmission lines are utilised in some steps of the design approach. Moreover, some rules of thumb are extracted for the absorber design in different frequencies. The designed absorber has a normalised bandwidth of 80% in the terahertz region, low sensitivity to incident angle and an absorption peak of 100%.
carbon (c), nitrogen (N), and phosphorus (P) are the basic nutrient elements required for plant growth and function. Ecological stoichiometry provides an important method for the determination of plant nutrient utiliz...
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carbon (c), nitrogen (N), and phosphorus (P) are the basic nutrient elements required for plant growth and function. Ecological stoichiometry provides an important method for the determination of plant nutrient utilization and the environmental adaptation strategies of plants. Studying the stoichiometry of c, N and P is crucial to the understanding of nutrient cycling and ecosystem stabilization mechanisms. Most studies so far have focused only on N and P stoichiometry for plant leaves and ignored the stoichiometry characteristics among c, N, and P. As a major element of plant dry matter, c, along with critical nutrient elements (N and P) could regulate and influence the consumption and fixation of organic matter in ecosystems. Therefore, it is necessary to study the ecological stoichiometry of c, N, and P in plants. Here, c, N and P concentrations and their ratios were measured for 329 foliar samples collected at 132 sites along the 4500 km-long chinese Grassland Transect (cGT) that traverses the Inner Mongolian and Qinghai-Tibet Plateaus. The content of c, N, and P of plant leaves in grassland ranged from 257.40 to 590.77 mg/g, 4.49 to 45.85 mg/g, and 0.20 to 3.40 mg/g, with an average of 463.76 mg/g, 19.94 mg/g, 1.31 mg/g, respectively. The coefficient of variation (cV) of P was highest (0.47) while the cV values of c and N were 0.09 and 0.34, respectively. N and P were positively correlated (R2 = 0.491, P b 0.0001), in agreement with previous studies, while no significant correlation was found between c and P or between c and N. The ranges for c/N, N/P, and c/P were 10.93-93.67 (with an average of 26.86 and a cV value of 0.46) for c/N, 1.68-53.00 (with an average of 16.59 and a cV value of 0.39) for N/P, and 61.49-1995.24 (with an average of 436.77 and a cV value of 0.59) for c/P, respectively. The mass ratio of c:N:P in grassland plant was 440:17:1, and the atom ratio was 1136:43:1. c/N and c/P, c/N and N/P were positively correlated (R2 =
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