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To obtain higher power in ${W}$ -band traveling-wave tubes (TWTs), a modified folded waveguide (FWG) with non-concentric bends is introduced and demonstrated, which has higher coupling impedance compared with the normal FWG structure and is utilized to eliminate the band-edge instability of TWT. Phase velocity tapering (PVT) is also used to improve the interaction efficiency between the beam and the circuit. Furthermore, a higher beam current is used and the corresponding magnetic focusing system is designed to confine the beam. A prototype tube was then fabricated and tested at a beam current of 220 mA and beam voltage of 21.9 kV. The testing data show that this ${W}$ -band TWT is capable of delivering an output power of over 450 W with a 4.5-GHz bandwidth at a duty cycle of 10%, with a maximum power of 647 W and electronic efficiency of 13.4%. That is the highest output power and electronic efficiency test results of ${W}$ -band TWTs reported so far.

Using a new kind of folded waveguide (FWG) with modified circular bends and two-stage depressed collector, we have designed a $W$ -band-pulsed traveling wave tube (TWT) operating at substantially lowered-voltage with high power and efficiency. A prototype tube has been tested at voltage of 15.66 kV and 30% duty cycle, showing output power over 180 W and gain over 36 dB in 91–97-GHz frequency range. The electronic and overall efficiency are above 7.8% and 29%, respectively, within the bandwidth of 6 GHz. The packaged TWT has outer dimensions of $270\times 49\times46$ mm3 and weighs less than 1.5 kg.

In this article, a $3\pi $ band-edge dual frequency oscillator using a novel half-period staggered folded waveguide (FWG) is proposed. Simulation results from CST Particle Studio show that the half-period staggered FWG could form a stopband at $3\pi $ phase shift with a high coupling impedance, enabling the device operating at two frequencies. A prototype oscillator was then designed and fabricated. The experimental results showed that it was capable of operating at both 89.2 and 94.5 GHz with the maximum output power 148 and 65W, respectively. The testing results are also compared with the simulation.

Pancreatic cancer will be the second leading cause of cancer-related mortality worldwide due to its high rate of metastasis. Cathepsins (CATs) are effectors of invasive growth in various cancers. Currently, targeting CATs represents an attractive strategy for the treatment of highly metastatic cancers with high CATs activity, such as pancreatic cancer. To develop a stronger antimetastatic agent, ASPER-29, a novel inhibitor of CATs designed by using the asperphenamate derivative BBP as a lead compound, was synthesized, and its therapeutic potential in pancreatic cancer metastasis was investigated in this study. Molecular docking and enzyme inhibition assays proved that ASPER-29 can inhibit the activity of CAT-L and CAT-S by binding with these enzymes in classical action modes. Furthermore, ASPER-29 significantly inhibited the activity of CAT-L and CAT-S but had no effect on their expression in PANC-1 and BxPC-3 cells. The in vitro antimetastatic activities of ASPER-29 were examined by wound healing and Transwell chamber assays. We found that ASPER-29 inhibited the migration and invasion of PANC-1 and BxPC-3 cells in a concentration-dependent manner. Moreover, the in vivo antimetastatic effects of ASPER-29 were confirmed in a mouse xenotransplantation model. HE staining and immunohistochemistry assays of Ki67 and CEACAM6 proved that ASPER-29 treatment significantly blocked the metastasis of pancreatic cancer cells to lung and liver tissues. Additionally, the activity of both CAT-L and CAT-S was markedly inhibited in the lung and liver tissues of ASPER-29-administered mice compared with the mice in the model group, suggesting that the metastasis-blocking effect of ASPER-29 should be mediated via inhibition of the activity of CAT-L and CAT-S in pancreatic cancer cells. Together, our results demonstrated that ASPER-29, as a novel inhibitor of CAT-L and CAT-S, possessed the evident ability to block the metastasis of pancreatic cancer cells.

The W-band pulsed traveling-wave tubes (TWTs) are known to play a crucial role in the high-resolution radars due to their wide bandwidth and high output power. This paper presents some experimental results of an ultrawide bandwidth W-band pulsed TWT with folded-waveguide circuits fabricated by ultraviolet lithography, electroplating, and molding. A prototype tube has been tested, showing a gain of over 30 dB from 94 to 110 GHz and saturated output power of over 100 W from 94 to 101.8 GHz, with an electronic efficiency of 2.86%-4.08%. Limited by the drive power, the prototype's unsaturation output power is over 60 W from 101.8 to 110 GHz.

A compact folded waveguide traveling-wave tube (TWT) with PPM system operating at 220 GHz with 10 W of output power and 10 GHz bandwidth is being developed. This paper reports the test results of the latest prototype.

A folded waveguide traveling-wave tube (TWT) with PPM system operating at 220 GHz with 10 W of output power and 10 GHz bandwidth is being developed. This paper reports the status of fabrication and test.