Enhancement and Optimization of Underwater Images and Videos Mapping.

Underwater images tend to suffer from critical quality degradation, such as poor visibility, contrast reduction, and color deviation by virtue of the light absorption and scattering in water media. It is a challenging problem for these images to enhance visibility, improve contrast, and eliminate color cast. This paper proposes an effective and high-speed enhancement and restoration method based on the dark channel prior (DCP) for underwater images and video. Firstly, an improved background light (BL) estimation method is proposed to estimate BL accurately. Secondly, the R channel's transmission map (TM) based on the DCP is estimated sketchily, and a TM optimizer integrating the scene depth map and the adaptive saturation map (ASM) is designed to refine the afore-mentioned coarse TM. Later, the TMs of G-B channels are computed by their ratio to the attenuation coefficient of the red channel. Finally, an improved color correction algorithm is adopted to improve visibility and brightness. Several typical image-quality assessment indexes are employed to testify that the proposed method can restore underwater low-quality images more effectively than other advanced methods. An underwater video real-time measurement is also conducted on the flipper-propelled underwater vehicle-manipulator system to verify the effectiveness of the proposed method in the real scene.

MiR-7 Regulates Pathogen-Induced Immune Response via PAK1 in the Sea Cucumber Apostichopus japonicus.

MicroRNA-7 (miR-7) is a highly conserved short non-coding RNA involved in various bioprocesses via the regulation of multiple target genes. To enrich our knowledge of the functions of miR-7 in innate immune regulation in echinoderms, we first investigated the targeting relationship between miR-7 and PAK1 in the sea cucumber Apostichopus japonicus and then explored the functions of miR-7, the PAK1 gene, and the miR-7/PAK1 axis in the pathogen-induced immune response of A. japonicus. Our results showed that miR-7 can bind to the 3'UTR of PAK1 and negatively regulate the expression of PAK1 in A. japonicus. Overexpression and inhibition of miR-7 and inhibition of the expression of PAK1 can alter phagocytosis, cellular agglutination, and lysozyme contents in A. japonicus. Both miR-7 and the PAK1 gene are involved in immune defense against Vibrio splendidus infection; the miR-7/AjPAK1 axis showed immune regulatory function at 48 to 72 h post-infection (hpi) after V. splendidus infection in A. japonicus. In summary, the results of this study established that miR-7 regulates the pathogen-induced immune response by targeting PAK1 in A. japonicus.

Isolation and characterization of four pathogenic strains of Vibrio spp. from farmed sea urchins, Strongylocentrotus intermedius, in China.

The sea urchin Strongylocentrotus intermedius, famous for its gonadal quality, is one of the most important farmed species in the sea area of northern China. Since 2020, outbreaks of black peristomial membrane disease (commonly called black mouth disease) have frequently occurred in spring and winter in cultured S. intermedius. In this study, we isolated the predominant bacteria from different tissues of diseased sea urchins from a North China farm in the spring of 2021. Four pathogenic strains (named SIBMPM01, SIBMPM02, SIBMPM03 and SIBMCF01) were obtained and characterized by Gram staining, morphological observation, artificial infection tests, and metabolic characteristics. Our results showed that: 1) all obtained strains belonged to the genus Vibrio and had morphological differences. Phylogenetic analysis indicated that the four obtained strains might be novel Vibrio species. 2) Laboratory-based artificial infection tests showed that sea urchins infected with either SIBMPM01, SIBMPM02, SIBMPM03 or SIBMCF01 exhibited pathological symptoms of a black peristomial membrane in a dosage-dependent and temperature-dependent manner. The virulence of SIBMCF01 was greater than those of the others. 3) Metabolic characterization data showed that SIBMPM01, SIBMPM02, SIBMPM03 and SIBMCF01 shared similar metabolic characteristics. 4) Antimicrobial susceptibility tests demonstrated that the four obtained strains were all sensitive to ampicillin, doxycycline, norfloxacin, ofloxacin, furazolidone and chloramphenicol. SIBMPM01 was specifically sensitive to neomycin, and SIBMCF01 was specifically sensitive to carboxybenzyl penicillin.

ZIF-67 Derived Co2VO4 Hollow Nanocubes for High Performance Asymmetric Supercapacitors.

In this work, a new type of Co2VO4 hollow nanocube (CoVO-HNC) was synthesized through an ion exchange process using ZIF-67 nanocubes as a template. The hollow nanocubic structure of the CoVO-HNC provides an abundance of redox sites and shortens the ion/electron diffusion path. As the electrode material of supercapacitors, the specific capacitance of CoVO-HNC is 427.64 F g-1 at 1.0 A g-1. Furthermore, an asymmetric supercapacitor (ASC) was assembled using CoVO-HNC and activated carbon (AC) as electrodes. The ASC device attains an energy density of 25.28 Wh kg-1 at a high-power density of 801.24 W kg-1, with 78% capacitance retention after 10,000 cycles at 10 A g-1.