The microbes associated with black corals remain poorly studied. The present study is the first attempt to investigate microbial community structure in the black corals Antipathes ceylonensis and A. dichotoma from the South China Sea by using high-throughput Illumina sequencing. A total of 52 bacterial and 3 archaeal phyla were recovered in this study, suggesting the black corals harboured highly diverse microbial communities. Among the 55 microbial phyla, Proteobacteria, Firmicutes, Bacteroidetes, Chloroflexi, Acidobacteria and Actinobacteria dominated in the two black corals from the South China Sea. Although most of the microbial phyla recovered from the two black corals have been reported in previous studies on coral-associated microbes, eight bacterial phyla including Synergistetes, Thermi, AncK6, GNO2, NKB19, NC10, WWE1 and GAL15, and the archaeal phylum Parvarchaeota are reported for the first time from corals in this study, which expands our knowledge about the diversity of coral-associated microbes. The comparison of microbial communities in the different black coral species indicated that A. ceylonensis harboured few abundant bacterial genera such as Citrobacter and Pseudomonas, whereas a high diversity of rare bacterial genera (<1% abundance), such as Winogradskyella and Rubricoccus, was detected only in A. dichotoma. These results suggested that the microbial community in black corals exhibited species-specific variation.

Since computer controlled optical surfacing (CCOS) processes were proposed in the 1960s, many processes were developed for precision optics successfully. In this present work, a novel approach, the precessions process, is proposed and used for large segments fabrication. The removal function of the bonnet polisher based on velocity and pressure distribution, which are obtained from the geometry of the process tool-motion and Hertzian contact theory respectively, are simulated. A finite element analysis (FEA) model is constructed to optimize process parameters. At last, detailed experimental studies are carried out to verify the optimal parameters.

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To meet the special demands in small-scale discontinuous optical surface fabrication, the integrated magnetorheological jet polishing (IMJP) tool with multiple motion degrees is introduced in this paper. Four jetting models are implemented and investigated by means of the IMJP tool for practical manufacture. To ensure steady jetting in a long distance, ideal distribution characteristics of the magnetic field in the structure is proposed, based on electromagnetic theory. The magnetic field distribution is simulated subsequently using the finite element analysis method, and three key parameters in the IMJP tool structure are optimized through the simulations. The actual magnetic flux density is measured and spot polishing experiments are conducted in different standoff distances, verifying the effectiveness of the optimization. A processing experiment of a millimeter scale structure with milling tool marks located on a surface with nonuniform curvatures was conducted using the IMJP tool. The roughness of the polishing region converged to 4.86 nm Ra from a low initial quality after processing, and the tool marks have been efficiently removed. The experimental results reveal the reliability of the setup design and the remarkable roughness convergence ability of the IMJP tool for small complex structures.