Terahertz switch is one of the key components of future communication, radar, and imaging systems. Limited by the strong electromagnetic coupling in subwavelength scale, the traditional terahertz ...switch is difficult to meet the increasing application requirements. In this paper, a parallel topology terahertz meta-chip switch based on the combination of equivalent circuit theory and electromagnetic coupling is proposed. The meta-chip is realized by adjusting the density of two-dimensional electron gas of InP-HEMT, which converts the electromagnetic coupling between the microstructure and microstrips. By using the 90 nm gate length InP-HEMT process, a C-ring loaded meta-chip is fabricated and tested in this paper. The results show an insertion loss lower than 1 dB with a 10 dB switching ratio, which is 20% higher than that without C-ring while ensuring the rather low insertion loss. It shows that the presented mechanism has positive significance for the design of terahertz band functional devices.
We herein report a method that enables the generation of glycosyl radicals under highly acidic conditions. Key to the success is the design and use of glycosyl sulfinates as radical precursors, which ...are bench‐stable solids and can be readily prepared from commercial starting materials. This development allows the installation of glycosyl units onto pyridine rings directly by the Minisci reaction. We further demonstrate the utility of this method in the late‐stage modification of complex drug molecules, including the anticancer agent camptothecin. Experimental studies provide insight into the reaction mechanism.
Glycosyl radicals were generated under acidic conditions for the first time by the use of glycosyl sulfinates as precursors. This development enables the installation of glycosyl units directly onto pharmaceutically relevant pyridine cores by the Minisci reaction.
Herein, we report a method that enables the synthesis of carbohydrate–DNA conjugates by radical addition. Key to the success is the use of readily available, bench-stable, and unprotected glycosyl ...sulfinates as precursors to glycosyl radicals. The redox neutral reaction proceeds under mild and simple conditions and tolerates a broad substrate scope. A small library of carbohydrate–DNA conjugates was prepared.
As a novel UDP-based transport protocol which supports stream multiplexing, QUIC is faster, more lightweight and flexible than TCP. With the prevalence of multi-homed devices such as smartphones with ...both WiFi and 4G/5G cellular connectivity, Multipath QUIC (MPQUIC) can effectively utilize multiple network interfaces (i.e., multiple paths) to improve transmission efficiency. Current MPQUIC implementation adopts the Lowest-RTT-First (LRF) scheduler which always selects the path with the lowest smoothed RTT among all available paths. However, we show that in networks with heterogeneous paths where network characteristics (e.g., RTT, loss rate) differ considerably, such scheduling scheme leads to unnecessary waiting on fast paths and bufferbloat, degrading overall transmission performance significantly. To use heterogeneous paths efficiently (i.e., to reduce the overall file transfer completion time), this paper proposes a novel scheduling mechanism that assigns data to paths with transfer simulation without causing much additional overhead. Extensive experiment results in Mininet demonstrate that the proposed scheduling mechanism can reduce the transfer completion time by up to 29.6% as compared to existing MPQUIC implementation.
•The wearable strain sensor based on rGO/CNTs hybrids e-textiles with microscopic 3D network-structure are prepared via a novel and facile ultrasonic nano-soldering process.•The wearable rGO/CNTs ...e-textiles sensors present high sensitivity, good repeatability, and durability at detecting stretching and compressing deformation, and healthcare monitoring.•The rGO/CNTs e-textiles show gas permeability, super-hydrophobic performance, and washability.
Electronic textile (e-textile) has emerged as a new generation of wearable electronics with these promising applications in healthcare and human movement detection. Herein, we report the gas-permeable and wearable e-textile strain sensors based on reduced graphene oxide/carbon nanotubes (rGO/CNTs) hybrids with unique structures grown on the low cost and eco-friendly non-woven fabric (NWF) by using a novel and facile nano-soldering method via ultrasonication. The gas-permeable rGO/CNTs e-textile strain sensors are highly sensitive and wearable, and the gauge factors of the rGO/CNTs hybrids sensors are 34.69 and 1.21 kPa−1 at 1 % tensile strain and 8.85 kPa pressure, respectively. Moreover, the gas-permeable and wearable rGO/CNTs e-textiles sensors also present good repeatability, super-hydrophobic performance, washability and durability at detecting stretching and compressing deformation, and it can be used for healthcare by monitoring the motions and blood pulse of human body.
In this paper, we propose a dynamic transmission structure based on the coupling reconfiguration of spoof surface plasmon polaritons (SSPPs) in a 2D coplanar grating. By embedding a VO
2
film into ...the signal line, the dynamic transmission is realized by reconfiguring the coupling of terahertz waves from quasi-TEM waves to SSPPs. The analysis shows that the transmission can be modulated in almost the entire band of the SSPPs, which further benefits a promising group delay due to the weak dispersion characteristic in the frequency region much lower than the cut-off frequency of SSPPs. In addition, for the dynamic modulation caused by the coupling reconfiguration, only rather a small area of VO
2
film is needed to break the robustness of the 2D coplanar grating. Therefore, the coupling reconfiguration mechanism proposed in this paper facilitates the realization of an easily on-chip integrated dynamic SSPPs transmission structure with ultra-large bandwidth, and low group delay time difference. Accordingly, the presented mechanism will play a positive role in promoting the development of terahertz dynamic devices.
Compared to GaAs Schottky barrier diode (SBD), GaN SBD exhibits higher power handling capabilities and superior heat dissipation properties when used on high thermal conductivity SiC substrates. ...However, high-power continuous wave (CW) input causes a temperature rise and reduces performance in GaN-based frequency doublers. This article proposes a solution considering the thermal resistance of the SBD and using AlN as the dielectric substrate under high-power input. Furthermore, extending the metal to the ground minimizes assembly errors and guarantees consistency between simulation and experiment. The experimental results reveal the significant potential of GaN materials. With an input power of 646 mW in CW mode, a remarkable output power of 101.1 mW was achieved with only four anodes. Furthermore, at an input power of 440 mW, the frequency conversion efficiency peaked at 19% at 141 GHz. This notable achievement surpasses the performance of the existing GaN-based doublers and expands the operational capabilities to CW operation.
A nickel(II)-catalyzed asymmetric direct vinylogous Michael addition of γ-alkyl monosubstituted α,β-unsaturated butyrolactams to α,β-unsaturated carbonyl compounds has been disclosed, affording ...γ,γ-dialkyl substituted butyrolactams in good yields and satisfactory enantioselectivities. A tandem catalytic asymmetric vinylogous Michael addition/intramolecular Michael addition has also been developed based on this reaction, which enabled the construction of enantioenriched octahydroindoles with three consecutive stereogenic carbon centers.
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