We report the optical design of a solid immersion mirror (SIM) incorporated with a flying slider -called a SIM slider -for a near-field recording (NFR) system, its fabrication process, and optical evaluation. To achieve diffraction-limited performance $=14 (rms), a two-step glass-molding process was employed to fabricate the SIM. The numerical aperture of the SIM slider was 1.29. The rms value of the total wavefront aberration was 0:0679. The fabricated SIM slider achieves the optical performance estimated by calculation with the fabrication errors considered, and even diffraction-limited performance. However, an rms value of 0:035-0:04 for the total wavefront aberration is generally assigned for condensing optics for practical use because not only condensing optics but also other optical elements are involved in a practical optical disc system. Therefore, the aberration caused by the fabrication errors in the molding process should be reduced to at least 59% of the present level, if the SIM is to be applied to a practical NFR system.
The microbial community of the human gut has a crucial role in sustaining host homeostasis. High-throughput DNA sequencing has delineated the structural and functional configurations of gut metagenomes in world populations. The microbiota of the Russian population is of particular interest to researchers, because Russia encompasses a uniquely wide range of environmental conditions and ethnogeographical cohorts. Here we conduct a shotgun metagenomic analysis of gut microbiota samples from 96 healthy Russian adult subjects, which reveals novel microbial community structures. The communities from several rural regions display similarities within each region and are dominated by the bacterial taxa associated with the healthy gut. Functional analysis shows that the metabolic pathways exhibiting differential abundance in the novel types are primarily associated with the trade-off between the Bacteroidetes and Firmicutes phyla. The specific signatures of the Russian gut microbiota are likely linked to the host diet, cultural habits and socioeconomic status.
We demonstrate the creation and observation of para-hydrogen-induced polarization in heterogeneous hydrogenation reactions. Wilkinson's catalyst, RhCl(PPh3)3, supported on either modified silica gel or a polymer, is shown to hydrogenate styrene into ethylbenzene and to produce enhanced spin polarizations, observed through NMR, when the reaction was performed with H2 gas enriched in the para spin isomer. Furthermore, gaseous phase para-hydrogenation of propylene to propane with two catalysts, the Wilkinson's catalyst supported on modified silica gel and Rh(cod)(sulfos) (cod = cycloocta-1,5-diene; sulfos = -O3S(C6H4)CH2C(CH2PPh2)3) supported on silica gel, demonstrates heterogeneous catalytic conversion resulting in large spin polarizations. These experiments serve as a direct verification of the mechanism of heterogeneous hydrogenation reactions involving immobilized metal complexes and can be potentially developed into a practical tool for producing catalyst-free fluids with highly polarized nuclear spins for a broad range of hyperpolarized NMR and MRI applications.
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