Coding metasurfaces, composed of an array of coding particles with discrete phase responses, are encoded with predesigned coding sequences to manipulate wavefronts of electromagnetic (EM) waves and realize novel functionalities such as anomalous beam deflection, broadband diffusion, and polarization conversion. Such a new concept can be viewed as a bridge linking metamaterial and digital codes, yielding the investigation of metamaterials from a digital perspective and eventually the realization of real-time control of EM waves. Here, we propose and experimentally demonstrate a transmission-type coding metasurface to bend normally incident terahertz beams in anomalous directions and generate nondiffractive Bessel beams in normal and oblique directions. To overcome the larger reflection and strong Fabry−Perot resonance that usually originate from a thick silicon substrate, a free-standing design is presented for the coding particle, which is formed by stacking three metallic layers with four polyimide spacers alternately. Experimental results show that the fabricated sample could bend the normally incident terahertz wave to anomalous refraction angles of 26°and 58°with 58% and 40% efficiencies, respectively. Owing to the excellent mechanical and chemical properties of polyimide, the fabricated sample is extremely flexible and stable, implying promising applications in terahertz imaging and communication.
A method for fast design of broadband terahertz diffusion metasurface is presented. The proposed metasurface is composed by three kinds of simply patterned elements with different resonant properties. To obtain the best broadband performance with the lowest backward reflections, a genetic algorithm is developed to manipulate the resonances for the fast determination of element geometries. An inverse discrete Fourier transform method is used to predict the scattering pattern of the metasurface with high accuracy and low time consumption, significantly enhancing the efficiency of the array-pattern design. The proposed fast design flow will benefit a broad range of terahertz applications, such as biological detection and imaging.
subwavelength scatterers. With this emerging technique, many conventional devices such as beam defl ector, [ 18,21 ] Bessel beam lens, [ 22 ] vortex beam lens, [ 19,23,24 ] background-free circular polarizer, [ 25 ] and focusing lens [ 26 ] have been redesigned as 2D lightweight devices. Therefore, this new concept provides us with another way to design thinner transmitarrays with better performance, especially at THz frequencies, where the miniaturization is very desirable.Based on the generalized Snell's law, an ultrathin transmitarray at THz frequencies is proposed and demonstrated experimentally here. By carefully designing the geometry of unit cell, which is composed of three metallic layers separated by polyimide (PI) spacers, the fi ve basic constitutive elements offer a discretized 2π phase coverage, and can be utilized to manipulate the EM waves. Although there have been some designs previously reported on bending and rotating the THz waves by using single-layer metasurfaces, [27][28][29][30] all measured results for transmissions were severely suffered by strong Fabry-Perot effects, which are caused by the large thickness of substrates (over one free-space wavelength) and the high permitivities. In this work, owning to the fully free-standing design, all measured effi ciencies are obtained from the fabricated sample itself, which do not need to be normalized to the bare substrate, and hence can be directly applied to the current THz systems. Two examples are given to demonstrate the performance of the proposed transmitarrays in bending and focusing the terahertz waves.There are several reports on metasurfaces to bend the light to anomalous directions using single-layered metallic patterns at the optical frequency. [ 27,30,31 ] However, the maximum transmission effi ciency (copolarization) for a single nonmagnetic metasurface has a theoretical limit of 0.5, which was derived in ref. [ 32 ] by applying the reciprocity, symmetry, and passivity conditions to a two-port network. [ 32 ] To overcome the limitation, we proposed a triple-layered metasurface, which could provide a unity transmission and the entire 2π phase coverage simultaneously. Here, an electric-fi elddriven inductor-capacitor (ELC) resonant structure [ 33 ] is adopted to design the basic unit cell of transmitarrays because it can be switched between inductive and capacitive modes in the THz bandwidth of interest. The designed multilayered unit cell is formed by stacking three ELC resonators with two identical metasurfaces at outer layers, as illustrated schematically in Figure 1 a. Each metallic layer is separated by a polyimide spacer with 30 µm thickness. Considering the inevitable scratches, and any unpredictable contact that may damage the outer metallic layers in real applications, the top
Introduction: Systematic documentation of chemotoxicities in outpatient clinics is challenging. Incorporating patient-reported outcome (PRO) measures in clinical workflows can be an efficient strategy to strengthen the assessment of symptomatic treatment toxicities in oncology clinical practice. We compared the adequateness, feasibility, and acceptability of toxicity documentation using systematic, prospective, application of the PRO Common Toxicity Criteria for Adverse Events (PRO-CTCAE) tool. Methods: At a comprehensive cancer center, data abstraction of electronic health record reviews elucidated current methods and degree of chemotoxicity documentation. Web-based 32-item PRO-CTCAE questionnaires, administered in ambulatory clinics of patients receiving chemotherapy, captured chemotoxicities and respective severities. Patient telephone surveys assessed whether healthcare providers had addressed chemotoxicities to the patients' satisfaction. Results: Over a broad demographic of 497 patients receiving chemotherapy, 90% (95% CI 84-96%) with significant chemotoxicities (n = 107) reported that their providers had discussed toxicities with them; of these, 70% received a therapy management change, while among the rest, 17% desired a change in management. Of patients surveyed, 91% (95% CI 82-99%) were satisfied with their current chemotoxicity management. Clinician chart documentation varied greatly; descriptors rather than numerical grading scales were typically used. Although 93% of patients were willing to complete the PRO survey, only 50% thought that it would be acceptable to complete this survey at routine clinic visits. Conclusion: Use of PRO-CTCAE in routine clinical practice promotes systematic evaluation of symptomatic toxicities and improves the clarity, consistency, and efficiency of clinician documentation; however, methods to improve patient willingness to complete this tool routinely are needed.
According to the requirements of the high temperature flameless catalytic combustion burner ignition and intelligent control, the author designed intelligent electronic igniter with microprocessor controlled. Intelligent electronic igniter is controlled by Freescale MC9S08GB60A microcontroller chip and the thermocouple is used as a temperature sensor. It also combined with high-voltage ignition circuit and the solenoid valve control circuit to achieve real-time temperature monitoring of high temperature flameless catalytic burner control ignition, flame cut off valve and other intelligent control.
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