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As an exceptional nonlinear material, graphene offers versatile appealing properties, such as electro-optic tunability and high electromagnetic field confinement in the terahertz regime, spurring advance in ultrashort pulse formation, photodetectors and plasmonic emission. However, limited by atomic thickness, weak light–matter interaction still limits the development of integrated optical devices based on graphene. Here, an exquisitely designed meta-cavities combined with patterned graphene is used to overcome this challenge and promote THz-graphene interaction via terahertz location oscillation. By using an 800 nm pump laser, the local field-induced strong interaction allows sensitive responses to the ultrafast energy transfer from the ultrafast optical pump to graphene electron heat, enabling 46.2% enhancement of terahertz transparency. Such optical modulation of terahertz waves shows ultrafast response in delay less than 10 ps. Moreover, thanks to the nature of graphene, the device shows unique potential for electrically dynamic tuning and further bandwidth broadening.

Chronic obstructive pulmonary disease (COPD) is a highly prevalent chronic respiratory disease characterised by irreversible airways obstruction associated with chronic airways inflammation and remodelling, while the pathogenesis and the mechanistic differences between patients remain to be fully elucidated. We previously reported that alarmin cytokine IL‐33 may contribute to the production of autoantibodies against respiratory epithelial cells. Here we expand the hypothesis that pulmonary autoimmune responses induced by airway microbiota also contribute to the progression of COPD. We focused on Edwardsiella tarda which we detected uniquely in the induced sputum of patients with acute exacerbations of COPD. Pernasal challenge of the airways of WT mice with supernatants of cultured E. tarda induced marked, elevated expression of IL‐33 in the lung tissues. Immunisation of animals with supernatants of cultured E. tarda resulted in significantly elevated airways inflammation, the formation of tertiary lymphatic structures and significantly elevated proportions of T follicular helper T cells in the lung tissue and mediastinal lymph nodes. Interestingly, such challenge also induced production of IgG autoantibodies directed against lung tissue lysate, alveolar epithelial cell proteins and elastin fragment, while putrescine, one of metabolites generated by the bacterium, might play an important role in the autoantibody production. Furthermore, all of these effects were partly but significantly abrogated in mice with deletion of the IL‐33 receptor ST2. Collectively, these data support the hypothesis that COPD is progressed at least partly by airways microbiota such as E. tarda initiating autoimmune attack of the airways epithelium mediated at least partly through the IL‐33‐ST2 axis. [ABSTRACT FROM AUTHOR]

In the digital workflow of complete denture fabrication, one solution for producing computer-aided design and computer-aided manufacturing dentures has been to mill the denture teeth and base separately and then bond them together. The correct bonding of the denture teeth and base is important to reproduce the designed occlusion in the definitive prosthesis. A novel technique is described to assist in the accurate positioning of denture teeth on the denture base by constructing auxiliary positioning slots on the denture base and auxiliary positioning posts on the denture teeth. The technique can assist in accurately assembling CAD-CAM milled complete dentures and may shorten chairside time by reducing clinical occlusal adjustment. [ABSTRACT FROM AUTHOR]

Electrical and trap characteristics of a large-size (2 × 2 mm2) β-Ga2O3 Schottky barrier diode (SBD) from 50 to 350 K have been reported. The ideality factor (n) decreases from 1.34 to nearly unity as temperature rises from 50 to 350 K, demonstrating near-ideal Schottky characteristics. The leakage current at cryogenic temperature (100 K) was significantly suppressed, indicating excellent off-state blocking performance at low temperatures. The weak temperature dependence of the carrier concentration (NS) and Schottky barrier height (ΦB) infers stable electrical characteristics of the β-Ga2O3 SBD. The stressed current density-voltage (J-V) and on-the-fly measurements reveal reliable dynamic performance under harsh low temperature conditions. Via deep-level transient spectroscopy, an electron trap, which is related to the dynamic performance instability and Lorentzian hump in low frequency noise spectra, is revealed for a β-Ga2O3 epilayer. The study reveals enormous potential of the utilization of a large-size β-Ga2O3 SBD for extreme temperature environments. [ABSTRACT FROM AUTHOR]

Terahertz amplitude and phase modulation technologies are crucial for terahertz communication, radar, and imaging. However, most current approaches can only achieve either amplitude or phase modulation. In this paper, we present a low terahertz frequency on-chip multi-functional modulator that consists of a hybrid coupler and reflection meta-structure. High-performance amplitude modulation is achieved by combining series resonant absorption of series coupling branch with resonance enhancement of parallel coupling branch in the reflection meta-structure. Meanwhile, the enhanced resonance provides a larger range of phase shifts, enabling effective amplitude and phase modulation in two different frequency regions. Therefore, we realize an amplitude modulation in the range of 115–135 GHz with a minimum transmission loss of 4 dB and a modulation depth of over 10 dB. At the same time, we achieved a continuous phase shift in the 103–113 GHz region, as well as a 180° two-bit phase shift in the 107–109 GHz range with only 5.7 dB transmission loss. Our simple method for terahertz amplitude and phase multi-functional modulation offers the potential to construe terahertz multifunctional integrated systems. [ABSTRACT FROM AUTHOR]

The structure and dimension of Schottky diode were designed. The loss at high frequency was reduced using a quasi-whisker contacted anode structure by a metal finger akin to an air bridge. The nonlinear model of Schottky anode and three dimensional electromagnetic(EM) model were established respectively according to the measured data and structure of Schottky diode. The diodes were placed in waveguide using balanced circuit design. The EM mode orthogonality ensured very good input and output signal isolation, which simplified the circuit structure and reduced the circuit loss. A 300 GHz doubler was designed and fabricated successfully. The efficiency is higher than 5% at 312～319 GHz with a peak efficiency of 10.1% at 316 GHz. The output power is higher than 4 mW at 307～318 GHz with a peak output power of 8.7 mW at 316 GHz. The diodes are replaced by one with higher doping concentration. The peak efficiency is 13.7% and the peak output power is 11.8 mW which reaches the similar level of reported doublers. The results proved the ability of Schottky diode working at high frequency.

Terahertz (THz) science and technology promise unique applications in high-speed communications, high-accuracy imaging, and so on. To keep up with the demand for THz systems, THz dynamic devices should feature large phase shift modulation and high speed. To date, however, only a few devices can efficiently manipulate the phase of THz waves. In this paper, we demonstrate that efficient phase modulation of THz waves can be addressed by an active and enhanced resonant metamaterial embedded with a nanostructured 2D electron gas (2DEG) layer of a GaN high electron mobility transistor (HEMT). The enhanced resonant metaunit couples the traditional dipolar and inductance-capacitance resonances together to realize a coupling mode with enhanced resonance. Embedded with the nanostructured 2DEG layer of GaN HEMT, the resonance intensity and surface current circuit of the enhanced resonant mode in the metamaterial unit can be dynamically manipulated by the electrical control of the carrier distribution and depletion of the 3 nm 2DEG, leading to a phase shift greater than 150° in simulation. In the dynamic experiments, a 137° phase shift was achieved with an external controlling voltage of only several volts in the THz transmission mode. This work represents the first realization of a phase shift greater than 100° in a dynamic experiment in transmission mode using an active metamaterial structure with only a single layer. In addition, given the high-speed modulation ability of the HEMT, this concept provides a promising approach for the development of a fast and effective phase modulator in THz application systems.