Ursolic acid (UA) is a naturally bioactive product that exhibits potential anticancer effects. The relatively safe and effective molecule intrigued us to explore a way to further improve its anti-cancer activity and tumor-targeting specificity. In the present study, a series of structural modifications of UA was achieved, which resulted in significant increase in growth inhibition on various cancer cell lines with minimal effects on normal cells. The leading molecule US597 (UA-4) caused depolarization of mitochondrial membrane potential, cell arrest in G0/G1 phase and apoptosis/necrosis in a dose-dependent manner. Structural docking suggested that the carbon chains of the modified UA derivatives compete strongly with glucose for binding to glucokinase, the key glycolysis enzyme presumably active in cancer cells. The combination of 2-deoxy-D-glucose (2-DG) and UA-4 induced cell cycle arrest in G2/M phase, promoted caspase-dependent cell death, reduced hexokinase activity, aggravated depletion of intracellular ATP, decreased lactate production and synergistically inhibited cancer cell growth in vitro (HepG2) and in vivo (H22). Collectively, our findings suggest that the structural modification enhances efficacy and selectivity of UA, and the combination of UA-4 with 2-DG produces synergistic inhibition on hepatoma cell proliferation by dual targeting of apoptosis and glycolysis.

A wideband fourth-order filtering antenna consists of two substrate integrated waveguide (SIW) dual-mode cavities is presented in this letter. The first SIW cavity creates two resonant nodes and one radiation null (RN) located on the upper stopband. The second SIW cavity integrated with a slot cannot only achieve radiation function but also realize dual-mode resonance, which can produce another lower out-of-band RN. These two RNs can be controlled to improve frequency selectivity and design flexibility. The coupling matrix theory is adopted to guide the design of the filtering antenna, and the generation principle of these two RNs can be explained by cross coupling. Finally, such a filtering antenna operating at the center frequency of 5.4 GHz with a fractional bandwidth of 7.64% and a maximum gain of 5.3 dBi is fabricated and measured.

A novel transparent and broadband diffusion metasurface that is composed of digital coding elements is presented. A coding unit shares a symmetric circular quasi-Minkowski closed-loop shape that is capable of generating 1 bit coding (with two phase states of 0° and 180°) elements by using different geometric scales. To improve the optical transmittance of metasurface, the top layer of the coding elements adopts the metal rings with ultrathin linewidth with the optical transmittance of above 97% theoretically, whereas the bottom layer adopts hexagonal ring mesh metallic film with the optical transmittance of 95.4% and high electromagnetic interference (EMI) shielding effectiveness. Moreover, an optimized random distribution of coding elements is elaborately designed to realize diffusion patterns with numerous uniform grating lobes resulting in significant suppression of the backward peak energy level. Finally, a prototype diffusion metasurface is fabricated and good agreement between the simulated and the measured results is obtained. The results demonstrate a significant polarization-insensitive diffusion property with about 10 dB scattering reduction in a broadband from 10.5 to 19.5 GHz, reaching a fractional bandwidth of 60%, as well as show good scattering reduction properties for oblique incident waves. The proposed optical transparent diffusion metasurface has further advantages of opening up a new route for tailoring the exotic microwave scattering features with simultaneously high transmittance such as window and other transparent applications in visible frequencies and can be extended for imaging and communications.

In this letter, a miniaturized half-mode fan-shaped substrate integrated waveguide (HMFSSIW) resonator is proposed to form different order of filters without increasing the size. The resonator is based on a semicircular substrate integrated waveguide (SIW) cavity with metallized vias distributed along the circumference. A metallized via located on the circle center and a semicircular ring slot etched along the circumference to realize half-mode resonances. By introducing one or two radial slots with different lengths, the four half-mode resonant frequencies can be controlled independently, which enables to form second- or third-order filter with controllable bandwidth and wide stopband. Finally, a second-order Chebyshev filter is well designed and a third-order filter centered at 1 GHz with a fractional bandwidth of 15% and a transmission zero (TZ) on the right side is designed, fabricated, and measured. The measured results show good agreement with the simulated ones.

In this article, the design, principle, and characterization of a 3-D metamaterial absorber (MA) have been presented, which consists of the spatial lossy transmission lines (SLTLs) and the resistively loaded high impedance surface (HIS). The proposed MA possesses a fractional bandwidth of 193% with absorption rate of above 90% in the frequency range from 2 to 110 GHz under TM polarization while maintaining large oblique incident angle stability of over 50 $^{\circ}$ . For demonstration, a prototype is fabricated, whose measurement results are in good agreement with the simulation results. Losses from the periodically patterned SLTLs and resistively loaded HIS are introduced by resistive graphene films using screen-printing technology, resulting in avoiding conventional soldering of numerous lumped resistors. An equivalent circuit model and a surface loss distribution are given to better illustrate the physical mechanism. Our findings establish general and systematic strategies for guiding the design of extremely wideband MA with large incident angle and pave the way for enhancing the microwave performance in applications of electromagnetic compatibility, imaging, radar detection, and stealth.

In this article, we propose a kind of new miniaturized cutoff tunable spoof surface plasmon polaritons (SSPPs) cell and design a bandpass filter (BPF) using high-order mode of this SSPP cell. The proposed new SSPP cell is miniaturized by adding a branch structure at the open end of the stub and bending the waveguide structure at the short end of the stub. For the designed BPF, by opening the rectangular slot in the stub and controlling the length and width of the rectangular slot, the upper cutoff frequency and the lower cutoff frequency can be tunable, respectively. Moreover, loading a capacitor between the stubs can further adjust the upper cutoff frequency of the BPF. Compared with the conventional SSPP unit, the area of the unit is reduced by 36.8%. The total tunable frequency range of the filter designed in this article reaches 1.91 GHz, and the return loss remains below $-$ 10 dB in the passband from 6.03 to 10.03 GHz.