Currently, there is scant information about the biodiversity and functional diversity of microbes in the eastern Indian Ocean (EIO). Here, we used a combination of high-throughput sequencing of 16S rRNA genes and a metagenomic approach to investigate the microbial population structure and its metabolic function in the equatorial EIO. Our results show that Cyanobacterial Prochlorococcus made up the majority of the population. Interestingly, there were fewer contributions from clades SAR11 (Alphaproteobacteria) and SAR86 (Gammaproteobacteria) to microbial communities than contributions from Prochlorococcus. Based on functional gene analysis, functional genes rbcL, narB, and nasA were relatively abundant among the relevant genes. The abundance of Prochlorococcus implies its typically ecological adaptation in the local ecosystem. The microbial metabolic potential shows that in addition to the main carbon fixation pathway Calvin cycle, the rTCA cycle and the 3-HP/4-HB cycle have potential alternative carbon fixation contributions to local ecosystems. For the nitrogen cycle, the assimilatory nitrate and nitrite reduction pathway is potentially the crucial form of nitrogen utilization; unexpectedly, nitrogen fixation activity was relatively weak. This study extends our knowledge of the roles of microbes in energy and resource cycling in the EIO and provides a foundation for revealing profound biogeochemical processes driven by the microbial community in the ocean.
Nano-cemented carbide is a novel material, which is superior to common cemented
carbide on physical and mechanical properties, such as high hardness, toughness, flexural strength
and higher wear resisting property. It is proposed to have wide application prospect to tools and
mould manufacturing.
In this paper, ELID grinding technique is applied to grind nano-cemented carbide tools. And the
ground surface quality, cutting edge radius, and machinability of nano-cemented carbide tools are
studied, compared with common cemented carbide. It is demonstrated by experimental results that
nano-cemented carbide has higher grinding surface quality with less surface flaw than that of
common cemented carbide. The cutting edge radius of nano-cemented carbide tool is less than that
of common cemented carbide tool. Under the same conditions, the tool life of nano-cemented
carbide is 1~2 times longer than that of common cemented carbide. The research results indicate
that ELID grinding technique is suitable for grinding cemented carbide tools. Nano-cemented
carbide tools have better machinability than common cemented carbide tools.
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