This article presents a class of simultaneous transmitting and reflecting pattern manipulation structures (STAR PMS) using 3-D transmission-line-based elements. First of all, the 3-D element is ...realized by compositing slotlines and microstrip lines together, which obtains a transmitting channel and a reflecting channel. To analyze the operating principle of the proposed element, an equivalent transmission line (TL) model is established, corresponding to the receiving structure and transmitting (or reflecting) structure in each channel. In this way, the transmission and reflection characteristics of our element can be designed with good independence, accuracy, and flexibility through the use of the synthesis method. Then, such elements are quasi-periodically arranged in a transverse plane, where the transmission and reflection phases of each element are adjusted according to the desired performance by virtue of the true-time-delay line. As such, the pattern of transmitted and reflected waves can be simultaneously manipulated. To verify our proposed design concept, a prototype is finally implemented from element synthetic design and simulation to array fabrication and testing. Measured results show a transmitting angle of (<inline-formula> <tex-math notation="LaTeX">\theta _{t} </tex-math></inline-formula> = 150° and <inline-formula> <tex-math notation="LaTeX">\phi _{t} </tex-math></inline-formula> = 90°) and a reflecting angle of (<inline-formula> <tex-math notation="LaTeX">\theta _{r} </tex-math></inline-formula> = 30° and <inline-formula> <tex-math notation="LaTeX">\phi _{r} </tex-math></inline-formula> = 90°) within the operating bandwidth of 74.3% (from 5.5 to 12 GHz), where the highest efficiencies for transmitting and reflecting manipulation are 32.2% and 36.7%, respectively. Therefore, the proposed STAR PMS can be viewed as one of the potential candidates for achieving full space electromagnetic (EM) environment reshaping in future wireless networks.
This article presents a method to design and implement pattern manipulation surfaces (PMSs) with polarization rotation by employing a patch-microstrip line-patch (PMP) structure. The ...polarization-rotation PMSs (PRPMSs) receive plane waves from different angles and reradiate polarization-rotated plane waves to a wanted direction. The impedance transforming characteristic of the patch under different incident angles between spatial wave to guided wave is studied with an equivalent circuit model (ECM). All the parameters in the ECM are obtained through one full-wave simulation with periodic boundary conditions (PBCs) under normal incidence in CST. The polarization rotation ability is realized by converting TM10 mode to TM01 mode on the patch through a microstrip line. The polarization conversion ratio (PCR) of the PMS with different incidences, scan angles, and polarizations is modeled by the ECM. Then, PRPMS elements with different microstrip line lengths are studied for phase tuning. The relationship between the microstrip line length and the phase shift is calculated via ECM and verified via full-wave simulation, both of which show that a continuous phase shifting range of 360° can be easily provided. In this way, the scattered waves can be steered in an arbitrarily prescribed direction. To validate the design concept under different incident angles, three PRPMS prototypes with the main beam steered to 0°, 30°, and 50° are fabricated and tested. Measured normalized RCS results agree well with the calculated and simulated ones, which verifies the validity of the proposed ECM and the PRPMS. Therefore, the proposed PRPMS is a promising method for future smart radio environments (SREs).
This article presents the proposal, design, and implementation of 3-D pattern modulation surfaces (PMSs) using short-circuited slotline structure. First, the reflection coefficient of short-circuited ...slotline with a certain length is studied using the equivalent transmission line model. Since the magnitude of its reflection coefficient nearly equals 1, the TE-polarized incident plane wave can be almost fully reflected at the input terminal of each short-circuited slotline. Most importantly, the phase of its reflection coefficient can be freely changed and adjusted by only varying the length of short-circuited slotline. Then, the short-circuited slotline structure is used as the key element of the proposed PMS. In this way, the functionality of pattern modulation is obtained by unequally selecting the lengths of a row of short-circuited slotlines. Finally, three prototypes with modulated angles of 15°, 30°, and 45° are fabricated and tested to validate our design concept. The measured results agree well with the calculations, showing that the predicted reflection angles are realized using short-circuited slotlines. Therefore, the proposed 3-D PMS is evidently verified to be a promising candidate for future wireless networks to achieve pattern modulation in a smart radio environment.
This article proposes a novel design concept of 3-D transmitting pattern manipulation structures (PMSs) using slotline bandpass filter (BPF) elements. First, the parallel-coupled slotline is utilized ...to synthetically design a slotline element by employing the equivalent transmission line model. Then, two types of elements are designed to implement the proposed PMS. The element-I with a variable transmission phase is realized by adjusting the resonant frequency of slotline structure, while keeping the transmission magnitude almost equal to 0 dB within an operating bandwidth of 13.2%. The element-II is obtained by connecting two element-Is in series for a larger range of transmission phase with an operating bandwidth of 10.3%. After that, two 3-D transmitting PMSs (PMS-I with <inline-formula> <tex-math notation="LaTeX">8\times20 </tex-math></inline-formula> elements and PMS-II with <inline-formula> <tex-math notation="LaTeX">10\times30 </tex-math></inline-formula> elements) are obtained by quasi-periodically arranging element-I and element-II, respectively. Finally, two prototypes of PMS-I and PMS-II are fabricated and tested to validate our design concept. Measurements and simulations agree well with each other, showing the desired transmission angles of (<inline-formula> <tex-math notation="LaTeX">\theta _{I}=10^{\circ } </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\phi _{I} </tex-math></inline-formula> = 90°) for PMS-I and (<inline-formula> <tex-math notation="LaTeX">\theta _{II}=20^{\circ } </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\phi _{II} </tex-math></inline-formula> = 90°) for PMS-II with the highest efficiencies of 92.8% and 88.9%. Therefore, the proposed 3-D transmitting PMS can be evidently used as a promising candidate to form the transmission waves for the future smart radio environment.
Lithium–sulfur (Li–S) batteries with a high theoretical energy density based on multi-electron redox reactions were strongly considered. The lithium disulfide/sulfide (Li2S2/Li2S, denoted as Li2S1/2) ...precipitation is critical to achieve high sulfur utilization. However, the kinetic effect on Li2S1/2 precipitation in a working battery has been rarely investigated. Herein, the current-density-dependent Li2S1/2 nucleation/growth was explored and such a dependence served as the guiding principle for the construction of high-sulfur-loading/content Li–S batteries. Generally, the Li2S1/2 nucleation density is proportional to two-third the power of the current density and the shift from a high to low current density alters the Li2S1/2 precipitation pathway from surface deposition to solution-mediated growth. The in-solution growth rate was found to be restricted by the mobilities of polysulfide intermediates and Li2S1/2 in conventional ether electrolytes. The rationalized guideline directed the design of a lightweight, high-surface-area, and open-pore conductive framework for sulfur cathodes, which enabled an extremely high sulfur content of 93.4 wt% in the whole electrode and a high capacity (1269 mA h g−1). The present work affords a kinetic understanding of the liquid–solid conversion in working Li–S batteries and optimization schemes for practical operation parameters.
This article proposes a novel design concept to realize planar pattern manipulation surfaces (PPMSs) using dual-polarized pin-loaded patch resonating elements. First, the resonant frequency and ...reflection coefficient of the pin-loaded patch element are investigated through its equivalent circuit model. By changing the positions of shorting pins, the reflection phase of such a patch element can be appropriately adjusted while maintaining the reflection magnitude unchanged. Additionally, varying the positions of shorting pins possesses a significant property of polarization independence. Then, the dual-polarized pin-loaded patch element is employed to design the proposed PPMS. In this way, the incident wave is manipulated for different reflection angles with the dual-polarization response by adjusting the position distributions of shorting pins in two orthogonal polarization directions. To prove our presented design concept, two prototypes with reflection angles of (<inline-formula> <tex-math notation="LaTeX">\theta ^{r} = 45^{\circ } </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">\phi ^{r} = 0^{\circ } </tex-math></inline-formula>) and (<inline-formula> <tex-math notation="LaTeX">\theta ^{r} = 45^{\circ } </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">\phi ^{r} = 45^{\circ } </tex-math></inline-formula>) are finally implemented, fabricated, and measured. Measurements and calculations agree well with each other, which indicates that the reflection angle is experimentally obtained as predicted in theory. Thus, the proposed PPMS can be apparently viewed as a promising candidate to efficiently customize the radio environment in future wireless networks.
This article presents designs of 3-D microwave absorbers with synthesizable absorptive performance. The synthetic procedure is investigated based on the unified equivalent transmission line (TL) ...model, which theoretically supports different performances. According to the desired absorptive performance, including the normalized absorptive resistance (NAR) and fractional bandwidth (FBW), the impedance parameters in the equivalent model can be easily obtained from the closed-form calculation. For demonstration, two prototypes are structurally developed and their different absorptive performances are measured. Each prototype element is designed with a single-layered 3-D structure consisting of composite TLs and only one loaded resistor. The measurements are in close agreement with the synthesized and simulated results, demonstrating an FBW of 99.0% (from 4.95 to 14.66 GHz) for absorber-A with a smaller NAR of 0.53. Absorber-B with a larger NAR of 1.25 obtains a measured FBW of 84.3% (from 5.76 to 14.16 GHz). These two absorbers realize in-band absorption ratios of 92.4% and 93.0% on average. In addition, efficient absorption can be obtained within 45° oblique incidence. Therefore, such a type of the proposed 3-D microwave absorber with synthesizable absorptive performance is indeed a promising candidate to customize electromagnetic wave absorption.
In vivo wireless photonic photodynamic therapy Bansal, Akshaya; Yang, Fengyuan; Xi, Tian ...
Proceedings of the National Academy of Sciences - PNAS,
02/2018, Letnik:
115, Številka:
7
Journal Article
Recenzirano
Odprti dostop
An emerging class of targeted therapy relies on light as a spatially and temporally precise stimulus. Photodynamic therapy (PDT) is a clinical example in which optical illumination selectively ...activates light-sensitive drugs, termed photosensitizers, destroying malignant cells without the side effects associated with systemic treatments such as chemotherapy. Effective clinical application of PDT and other light-based therapies, however, is hindered by challenges in light delivery across biological tissue, which is optically opaque. To target deep regions, current clinical PDT uses optical fibers, but their incompatibility with chronic implantation allows only a single dose of light to be delivered per surgery. Here we report a wireless photonic approach to PDT using a miniaturized (30 mg, 15 mm³) implantable device and wireless powering system for light delivery. We demonstrate the therapeutic efficacy of this approach by activating photosensitizers (chlorin e6) through thick (> 3 cm) tissues inaccessible by direct illumination, and by delivering multiple controlled doses of light to suppress tumor growth in vivo in animal cancer models. This versatility in light delivery overcomes key clinical limitations in PDT, and may afford further opportunities for light-based therapies.
The formaldehyde sensor with excellent performance has a wide range of applications in industrial production and the monitoring of many household products. Eu-doped 3D porous SnO 2 with a pore size ...of 120 nm were synthesized as a base material for high-performance formaldehyde sensors. The gas sensitivity test results show that the sensitivity of 3.6% Eu-doped 3D porous SnO 2 with a pore size of 120 nm to 20 ppm formaldehyde is 24 at an operating temperature of 230 °C, which is 1.8 times that of pure 3D porous SnO 2 with the same aperture. Moreover, the formaldehyde sensor made of 3.6% Eu-doped 3D porous SnO 2 with a pore size of 120 nm has good selectivity, with a selectivity coefficient of 5.5 for formaldehyde, good repeatability, and low detection limit (0.5 ppm/1.7). These excellent gas sensitivity characteristics are mainly attributed to the 3D porous SnO 2 with a loose and nano-scale porous morphology, more oxygen vacancies and Eu doping. Therefore, the gas-sensing of the metal oxide semiconductor material can be further improved by doping.
Mercury ions sensing is an important issue for human health and environmental safety. A novel fluorescence nanosensor was designed for rapid visual detection of ultratrace mercury ions (Hg2+) by ...using CH3NH3PbBr3 perovskite quantum dots (QDs) based on the surface ion-exchange mechanism. The synthesized CH3NH3PbBr3 QDs can emitt intense green fluorescence with high quantum yield of 50.28%, and can be applied for Hg2+ sensing with the detection limit of 0.124 nM (24.87 ppt) in the range of 0 nM–100 nM. Furthermore, the interfering metal ions have no any influence on the fluorescence intensity of QDs, showing the perovskite QDs possess the high selectivity and sensitivity for Hg2+ detection. The sensing mechanism of perovskite QDs for Hg2+ is has also been investigated by XPS, EDX studies, showing Pb2+ on the surface of perovskite QDs has been partially replaced by Hg2+. Spot plate test shows that the perovskite QDs can also be used for visual detection of Hg2+. Our research indicated the perovskite QDs are promising candidates for the visual fluorescence detection of environmental micropollutants.
Perovskite quantum dots were applied for ultratrace Hg2+ detection based on surface ions exchange mechanism. Display omitted
•The CH3NH3PbBr3 perovskite quantum dots (QDs) emitted intense green fluorescence with high quantum yield of 50.28%.•The perovskite QDs were applied for ultratrace mercury ions (Hg2+) detection with detection limit of 0.124 nM (24.87 ppt).•The fluorescence of perovskite QDs can only be quenched by Hg2+ which exhibits high selectivity.•A spot plate test for visual detection of Hg2+ in solution has been explored.
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