Low-RCS low-profile MIMO antenna and array antenna using a polarization conversion metasurface.

A specially designed dumbbell type polarization conversion metasurface (PCM) is proposed. The designed PCM achieves line-to-line polarization conversion in ultra-wideband (UWB) from 7.63 GHz to 18.80 GHz. A low-profile metasurface antenna composed of PCM and slot feed is proposed based on characteristic mode analysis (CMA), which realizes the integrated design of radiation and scattering. Because of the checkerboard scattering properties, low-radar cross section (RCS) low-profile multiple-input-multiple-output (MIMO) antenna and array antenna are designed with PCM. The low-RCS high-isolation low-profile MIMO antenna with size of 1.27×1.27×0.07λ 0 3 (λ0: the free-space wavelength corresponding to the center frequency point) operating at 5.8 GHz consists of four orthogonal arranged metasurface antennas. The isolation is greater than 26 dB with impedance bandwidth from 5.51 GHz to 6.06 GHz. In addition, the low-RCS high-gain low-profile array antenna with size of 2.55×2.55×0.07λ 0 3 is also designed. The operating band covers from 5.63 GHz to 6.12 GHz with the gain of 12-15.6 dBi. The RCS reduction of the two antennas for normal incidence is between 6 dB and 23 dB in both X- and Ku-bands. The measured results of the antennas agree with the simulated results, which shows that they have potential application value in 5.8 GHz WLAN wireless communication.

Three-fold information encryption based on polarization- and wavelength-multiplexed metasurfaces.

Metasurface has garnered significant attention in the field of optical encryption as it allows the integration and occultation of multiple grayscale nanoprinting images on a single platform. However, in most cases, polarization serves as the only key for encryption/decryption, and the risk of being cracked is relatively high. In this study, we propose a three-fold information encryption strategy based on a dielectric metasurface, in which a colorful nanoprinting image and two grayscale images are integrated on such a single platform. Unlike previous works based on the orientation-angle degenerated light intensity, the proposed image encryptions are realized by customizing nanobricks with polarization-mediated similar/different transmission characteristics in either broadband or at discrete wavelengths. Different combinations of polarization and monochromatic wavelengths can form three keys with different levels of decryption complexity as compared to the previous counterpart based merely on polarization. Once illuminated by non-designed wavelengths or polarized light, messy images with false information will be witnessed. Most importantly, all images are safely secured by the designated incidence polarization and cannot be decrypted via an additional analyzer as commonly happens in conventional metasurface-based nanoprinting. The proposed metasurface provides an easy-to-design and easy-to-disguise scheme for multi-channel display and optical information encryption.

Dissecting Plant Gene Functions Using CRISPR Toolsets for Crop Improvement.

The CRISPR-based gene editing technology has become more and more powerful in genome manipulation for agricultural breeding, with numerous improved toolsets springing up. In recent years, many CRISPR toolsets for gene editing, such as base editors (BEs), CRISPR interference (CRISPRi), CRISPR activation (CRISPRa), and plant epigenetic editors (PEEs), have been developed to clarify gene function and full-level gene regulation. Here, we comprehensively summarize the application and capacity of the different CRISPR toolsets in the study of plant gene expression regulation, highlighting their potential application in gene regulatory networks' analysis. The general problems in CRISPR application and the optimal solutions in the existing schemes for high-throughput gene function analysis are also discussed. The CRISPR toolsets targeting gene manipulation discussed here provide new solutions for further genetic improvement and molecular breeding of crops.

Enhancing Hydrodeoxygenation of Bio-oil via Bimetallic Ni-V Catalysts Modified by Cross-Surface Migrated-Carbon from Biochar.

Aromatics from selective hydrodeoxygenation (HDO) of biomass-derived bio-oil are an ideal feedstock for replacing industrial fossil products. In this study, biochar-modified Hß/Ni-V catalysts were prepared and tested in the atmospheric HDO of guaiacol and bio-oil to produce aromatics. Compared with unmodified Hß/Ni-V, higher HDO activity was achieved in catalysts with all kinds of biochar modifications. Especially, the pine nut shell biochar (PB)-modified PB-Hß-8/Ni-V showed the highest selectivity to aromatics (69.17%), mainly including benzene and toluene. Besides, under the conditions of 380 °C and weight hourly space velocity (WHSV) of 0.5 h-1, the cleavage of CAr-OH (CAr means the carbon in the benzene ring) was promoted to form more aromatics. Moreover, great recyclability (58.77% aromatics for the reactivated run-3 test) and efficient HDO of bio-oil (44.9% aromatic yield) were also achieved. Based on the characterization results, the enhanced aromatic selectivity of PB-Hß-8/Ni-V was attributed to the synergetic effect between PB and Hß/Ni-V. In detail, a stable surface migrated-carbon layer was formed on Hß/Ni-V via the metal catalytic chemical vapor deposition (CVD) process of the pyrolysis PB volatiles. Simultaneously, a carbothermal reduction driven by the migrated-carbon took place to decorate the surface metals, obtaining more Ni0 and V3+ active sites. With this synergism, increased Ni0 sites promoted H2 adsorption and dissociation, which improved the hydrogenation activity. Furthermore, the higher affinity of the reactant and increased oxygen vacancies both contributed to enhancing the selective surface adsorption of oxygenous groups and the cleavage of the CAr-OH bond, thus improving the deoxygenation activity. Therefore, the HDO activity was improved to form more target aromatics over biochar-modified catalysts. This work highlighted a potential avenue to develop economic and environmental catalysts for the upgrading of bio-oil.

Effect of Pectin on the Expression of Proteins Associated with Mitochondrial Biogenesis and Cell Senescence in HT29-Human Colorectal Adenocarcinoma Cells.

Mitochondria dynamic is regulated by different proteins, maintaining a balance between fission and fusion. An imbalance towards mitochondrial fission has been associated with tumor cell proliferation. The aim of this study was to analyze whether pectin modifies the viability of human colon cancer cells and the expression of proteins involved in mitochondrial fusion and fission. The human colon carcinoma cell line HT29 cells was growth in 10% fetal bovine serum in the absence and presence of pectin. Pectin reduced HT29 cell viability in a concentration-dependent manner, reaching a plateau at 150~300 µmol/L pectin. The presence of 200 µmol/L pectin reduced the expression of dynamin-related protein-1 and increased expression of the mitochondrial fusion-associated proteins mitofusin-1 and 2. Expression of cyclin B1, a protein involved in G2/M transition, was found decreased in pectin-incubated HT29 cells. Moreover, expression of p53 protein, the amount of p53 in the nucleous and ß-galactosidase activity, which are all biomarkers for cellular senescence, were significantly higher in pectin-incubated HT29 cells than in HT29 cells incubated without pectin. Expression of the protein B-cell lymphoma 2 (Bcl-2) homologous antagonist/killer was increased in response to incubation with pectin. However, incubation with pectin did not affect expression of Bcl-2-associated X protein or Bcl-2, or the caspase-3 activity. Overall, we concluded that pectin reduces the viability of human HT29 colon cancer cells, which is accompanied with a shift in the expression of proteins associated with mitochondrial dynamics towards mitochondrial fusion. Moreover, incubation with pectin favors cellular senescence over apoptosis in HT29 cells.