A conformal circularly polarized (CP) H-plane horn antenna with broadband and low-profile characteristics is proposed in this communication, which is integrated with quasi-Yagi and wrapped around a ...hollow cylinder. The H-plane horn based on bent corrugated substrate integrated waveguide (BCSIW) technology and the quasi-Yagi with fan-shaped driving elements provide the vertical and horizontal linear-polarized waves, respectively, which generates CP radiation combined with the suitable phase delay provided by the transition section. The proposed antenna is wrapped around a hollow metallic cylinder with a radius of 100 mm and a height of 90 mm. The measured voltage standing wave ratio (VSWR) of the fabricated antenna is less than 2.0 in the frequency range over 9.4 GHz (81%), while the axial ratio (AR) is below 3 dB from 9.4 to 21.7 GHz (78%). The antenna also exhibits a stable radiation pattern with a peak gain of 12.1 dBi and a cross-polarization below −17 dB over the whole frequency range. It is observed that the measured results agree well with simulated ones.
Two types of WR-3 band quasi-elliptical waveguide bandpass filters (BPFs) using higher order mode resonators are presented based on physical cross coupling and modal bypass coupling, respectively. ...Under the situation of physical folded structure, a TE102-mode in an oversized waveguide resonator is utilized to reverse the magnetic field direction of main path to implement a negative cross coupling (Filter-I). Limited to the structure of Filter-I itself, the simulated 3 dB fractional bandwidth (FBW) of 8.5% is slightly narrower than desired 10% FBW. For the other case, two TE101/TE201 overmode resonant cavities with suitable input and output coupling locations are employed to generate two transmission zeros in the vicinity of the passband through modal bypass couplings (Filter-II). The benefit from the realization of the wideband source and load couplings in the fringe first and fourth oversized cavities is that the FBW of 10% is achieved in the Filter-II. The two BPFs fabricated by computer numerical control milling technology exhibit an insertion loss (IL) of about 0.7 dB and a 3 dB FBW of 8.77% centered at 257.7 GHz (Filter-I), IL of around 0.5 dB, and FBW of 9.83% with center frequency of 256.3 GHz (Filter-II), which are all in good agreement with the simulations. The performance of the two BPFs based on one or two oversized waveguide resonators is highlighted comparing with the reported similar terahertz waveguide filters.
A 220-GHz low-loss and wideband waveguide bandpass filter with fourth-order quasi-elliptic response is presented and analyzed in this letter. An electric cross-coupling realized by easily ...manufactured capacitive iris is introduced in the classical folded quadruplet topology. The prototype fabricated by conventional computer numerical control (CNC)-metal-milling technology exhibits meaningful results of an insertion loss of around 0.6 dB and a 3-dB fractional bandwidth of 9.8% centered at 214.3 GHz, which are in excellent agreement with the simulated ones. The effects of tolerance and surface roughness on the filter performance are discussed in detail. All the results indicate that the present CNC process can meet the accuracy and roughness requirement of such waveguide filter in WR-4 band.
A novel <inline-formula> <tex-math notation="LaTeX">H </tex-math></inline-formula>-plane waveguide in-phase power divider (also known as combiner) with high isolation working across full WR-3 band ...(220-330 GHz) is realized in this paper. This distinctive architecture is designed based on the sum-difference principle of Magic-T, whose <inline-formula> <tex-math notation="LaTeX">E </tex-math></inline-formula>-plane branch (difference port) is matched with an <inline-formula> <tex-math notation="LaTeX">E </tex-math></inline-formula>-plane T-junction. Both effects of processing and assembling uncertainties on this power divider/combiner performance are discussed in detail to display error sensitivity. The physical prototype is split into three blocks and processed by the state-of-the-art computer numerical control (CNC) milling technology. The absorbing materials are housed in the loaded T-junction arms to terminate return wave as well. Compared with the most reported terahertz waveguide power couplers, the meaningful measured results of this advanced in-phase power divider are delivered. The input and output matching as well as high isolation have been obtained over full WR-3 band, when an 11 dB reference level is considered. A total insertion loss of about 1.2 dB is achieved including three straight waveguides having a total length of 30 mm, which is also in good agreement with simulations. This module, which is fully compatible with the standard CNC-milling technique, can be directly integrated to terahertz detection systems.
The manipulation of light in an integrated circuit is crucial for the development of high-speed electro-optic devices. Recently, molybdenum disulfide (MoS2) monolayers generated broad interest for ...the optoelectronics because of their huge exciton binding energy, tunable optical emission, direct electronic band-gap structure, etc. Miniaturization and multifunctionality of electro-optic devices further require the manipulation of light–matter interaction at the single-nanoparticle level. The strong exciton–plasmon interaction that is generated between the MoS2 monolayers and metallic nanostructures may be a possible solution for compact electro-optic devices at the nanoscale. Here, we demonstrate a nanoplasmonic modulator in the visible spectral region by combining the MoS2 monolayers with a single Au nanodisk. The narrow MoS2 excitons coupled with broad Au plasmons result in a deep Fano resonance, which can be switched on and off by applying different gate voltages on the MoS2 monolayers. A reversible display device that is based on this single-nanoparticle modulator is demonstrated with a heptamer pattern that is actively controlled by the external gates. Our work provides a potential application for electro-optic modulation on the nanoscale and promotes the development of gate-tunable nanoplasmonic devices in the future.
A functional cancer theranostic nanoplatform is developed, specifically tailored toward the optoacoustic modality by combining gold nanorods with DNA nanostructures (D–AuNR). DNA origami is used as ...an efficient delivery vehicle owing to its prominent tumor‐targeting property. The D–AuNR hybrids display an enhanced tumor diagnostic sensitivity by improved optoacoustic imaging and excellent photothermal therapeutic properties in vivo.
The exploration of biocompatible materials with circularly polarized luminescence (CPL) activity is becoming an attractive topic due to the great potential application in biosensing and bioimaging. ...Here, we describe a strategy to fabricate new CPL-active biomaterials using achiral carbazole-based biscyanine fluorophores coassembled with chiral deoxyribonucleic acid (DNA) molecules. This cyanine molecule has been shown to behave as a DNA detecting probe, featuring strong fluorescent emission induced by restriction of intramolecular rotation (RIR). When the achiral cyanine molecules are bound to the minor groove of DNA via electrostatic attraction in aqueous solution, the chirality of the DNA molecules can be transferred to the confined RIR cyanine dyes, triggering a remarkable circularly polarized luminescent emission. The chirality of the CPL signal can be regulated by the structures of the DNA templates. Stimuli-responsive CPL activates were observed from DNA–cyanine complexes. We further verified this strategy on different DNA-based nanomaterials, including DNA origami nanostructure. Our design presents a new avenue to fabricate compatible CPL materials.
An anaerobic, spore-forming, ethanol-hydrogen-coproducing bacterium, designated LX-BT, was isolated from an anaerobic sludge treating herbicide wastewater. Cells of strain LX-BT were non-motile rods ...(0.3-0.5×3.0-18.0 µm). Spores were terminal with a bulged sporangium. Growth occurred at 20-50 °C (optimum 37-45 °C), pH 5.0-8.0 (optimum pH 6.0-7.7) and 0-2.5% (w/v) NaCl. The strain could grow fermentatively on glucose, maltose, arabinose, fructose, xylose, ribose, galactose, mannose, raffinose, sucrose, pectin, starch, glycerol, fumarate, tryptone and yeast extract. The major end-products of glucose fermentation were acetate, ethanol and hydrogen. Yeast extract was not required but stimulated growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, anthraquinone-2,6-disulfonate, fumarate and Fe (III) nitrilotriacetate were not used as terminal electron acceptors. The G+C content of the genomic DNA was 56.1 mol%. The major cellular fatty acids were anteiso-C15:0, iso-C14:0 and C16:0. The most abundant polar lipids of strain LX-BT were diphosphatidylglycerol and phosphatidylglycerol. 16S rRNA gene sequence analysis revealed that it belongs to an as-yet-unidentified taxon at the order- or class-level (OPB54) within the phylum Firmicutes, showing 86.5% sequence similarity to previously described species of the Desulfotomaculum cluster. The name Hydrogenispora ethanolica gen. nov., sp. nov. is proposed to accommodate strain LX-BT (=DSM 25471T=JCM 18117T=CGMCC 1.5175T) as the type strain.
On-chip filters play an invaluable role in most detectors and instruments, blocking unwanted, harmonic, or mirrored signals. In this article, two coplanar waveguide bandpass filters working at 350 ...GHz are designed based on quarter-wavelength stepped impedance resonators, which can be easily integrated in on-chip systems. A second-order filter with a classical Chebyshev response and a fourth-order filter with quasi-elliptical characteristic is developed together to define the roll-off performance. Both filters are patterned based on superconducting niobium film by the optical lithography and lift-off process, which could reduce the significant metallic loss in high terahertz band. All the chips integrated with transitions are evaluated through a quasi-optical system, which is built based on the sensitive superconductor-insulator-superconductor tunnel junction detector at cryogenic temperature. The calibrated transmission responses, which are matched with simulations, have indicated that such superconducting coplanar waveguide filters can be enabled in future terahertz astronomical spectrometer.
•Appropriate model of temperature dependent relaxation time and carrier mobility for BiCuSeO were derived.•Acoustic phonon scattering is in dominant and the constant relaxation time approximation is ...reasonable in lightly doped case.•Ionized impurity scattering was added in the model in the heavily doped BiCuSeO system.
To obtain thermoelectric properties of materials, a constant relaxation time approximation is generally employed. By employing deformation potential theory, a derivation of relaxation time and carrier mobility of BiCuSeO system is proposed combining with density functional theory calculation. And the inter-valley scattering, acoustic phonon scattering and ionized impurity scattering were considered in the model. The calculated values of relaxation time and carrier mobility in BiCuSeO are in good agreement with the results of experiment. The results suggest that acoustic phonon scattering is in dominant and the constant relaxation time approximation is reasonable in lightly doped sample, and the ionized impurity scattering play a significant role in heavily doped system.
PDF
