BackgroundSince the analysis of a large number of metagenomic sequences costs heavy computing resources and takes long time, we examined a selected small part of metagenomic sequences as “sample”s of the entire full sequences, both for a mock community and for 10 different existing metagenomics case studies. A mock community with 10 bacterial strains was prepared, and their mixed genome were sequenced by Hiseq. The hits of BLAST search for reference genome of each strain were counted. Each of 176 different small parts selected from these sequences were also searched by BLAST and their hits were also counted, in order to compare them to the original search results from the full sequences. We also prepared small parts of sequences which were selected from 10 publicly downloadable research data of MG-RAST service, and analyzed these samples with MG-RAST.ResultsBoth the BLAST search tests of the mock community and the results from the publicly downloadable researches of MG-RAST show that sampling an extremely small part from sequence data is useful to estimate brief taxonomic information of the original metagenomic sequences. For 9 cases out of 10, the most annotated classes from the MG-RAST analyses of the selected partial sample sequences are the same as the ones from the originals.ConclusionsWhen a researcher wants to estimate brief information of a metagenome’s taxonomic distribution with less computing resources and within shorter time, the researcher can analyze a selected small part of metagenomic sequences. With this approach, we can also build a strategy to monitor metagenome samples of wider geographic area, more frequently.Electronic supplementary materialThe online version of this article (10.1186/s12859-018-2431-8) contains supplementary material, which is available to authorized users.

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An annular linear induction electromagnetic pump (ALIP) with a flow rate of 2265 L/min and a developed pressure of 4 bar was designed and fabricated to test the performance of the components of a sodium-cooled fast reactor (SFR) in a sodium thermal hydraulic experimental loop. The design characteristic of the ALIP was calculated using the electrical equivalent circuit method typically used for analyzing linear induction machines. Preliminary tests, such as verification of the moving function using an annular Al pipe, were carried out. The linearity between the input voltage, current, and magnetic flux density was verified. The developed force demonstrated an increase proportional to the square of the input current, whereas the velocity was linearly proportional to the input current. The main design variables of the pump were calculated theoretically for the SFR thermal hydraulic experimental loop. The pump was optimized for the design variables including input frequency, and the characteristics of the optimized pump were compared with those of the pump at the commercially used frequency of 60 Hz.

Summary The report describes the development of an innovative magnetohydrodynamic (MHD) space‐integrated coolant system design concept for the small modular lead fast reactor called the ubiquitous, rugged, accident‐forgiving, nonproliferating, and ultralasting sustainer reactor. The coolant system efficiency was analyzed based on space‐integrated geometric and electromagnetic variables related to the circulation of lead‐bismuth eutectic (LBE) liquid metal coolant in a reactor with a thermal output of 100 MWt and using the MHD principle. The objective of the system is to optimize the circulation of the noncontacting liquid metal coolant without any internal structure, such as an impellor or sealing part, to transport the LBE with high electrical conductivity in the reactor. The concept was first applied to the pool‐type integral leading facility for lead‐alloy cooled advanced small modular reactor, which serves as a scaled‐down experimental facility for the ubiquitous, rugged, accident‐forgiving, nonproliferating, and ultralasting sustainer reactor, for characteristic analysis of the coolant system subject to the requirements of a developed pressure of 8456 Pa and a mass flow rate of 21.37 kg/second. The MHD core blanket, which was attached to the upper part of the pool‐type integral leading facility for lead‐alloy cooled advanced small modular reactor and wrapped it cylindrically from the outside to form an annular passage, was designed for the forced circulation of liquid LBE taking into account its internal space and the high operating temperature of 440°C. Design variable analysis provided the optimized geometric and electromagnetic parameters of the MHD driving system based on the electromagnetic characteristics in the coolant passage of the reactor. This forced cooling system concept based on MHD propulsion is structurally simple and will enable significant space reduction and increased power for small modular lead fast reactors. It was also determined that safe long‐term reactor operation could be ensured without requiring particular maintenance because the operation does not involve fluid contact.

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