Using a sample of spiral galaxies selected from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) and Galaxy Zoo 2 (GZ2), we investigate the alignment of spin axes of spiral galaxies with their surrounding large scale structure, which is characterized by the large-scale tidal field reconstructed from the data using galaxy groups above a certain mass threshold. We find that the spin axes only have weak tendency to be aligned with (or perpendicular to) the intermediate (or minor) axis of the local tidal tensor. The signal is the strongest in a cluster environment where all the three eigenvalues of the local tidal tensor are positive. Compared to the alignments between halo spins and local tidal field obtained in N-body simulations, the above observational results are in best agreement with those for the spins of inner regions of halos, suggesting that the disk material traces the angular momentum of dark matter halos in the inner regions.

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Levan is a polymer of fructose synthesized by levansucrase using sucrose as the substrate, which is employed as a viscosifier, stabilizer, emulsifier, and gelling or water-binding agent for diverse industrial applications. To enable a gentle and efficient purification process, we cloned the gene of levansucrase (sacB) from Bacillus amyloliquefaciens BH072 into an inducible vector harboring the signal peptide gene amyQ and then expressed it in Bacillus subtilis 168. The optimal pH values for d-glucose production and levan formation by the recombinant enzyme were 6.0 and 7.0, respectively, whereas the optimum temperatures were 40 and 35 °C, respectively. The K m and V max values for the recombinant levansucrase were calculated to be 0.71 mM sucrose and 0.49 μmol mL–1 min–1. Finally, levan biosynthesized by the recombinant enzyme was detected by thin layer chromatography (TLC) and Fourier transform infrared spectroscopy (FT-IR). TLC chromatograms of reaction products qualitatively indicated the formation of levan that was further assessed by high-performance liquid chromatography analysis. Some important functional groups and chemical bonds of the obtained dried levan powder were determined by FT-IR.

The alignment between satellites and central galaxies has been studied in detail both in observational and theoretical works. The widely accepted fact is that the satellites preferentially reside along the major axis of their central galaxy. However, the origin and large-scale environment dependence of this alignment are still unknown. In an attempt to figure out those, we use data constructed from SDSS DR7 to investigate the large-scale environmental dependence of this alignment with emphasis on examining the alignments' dependence on the colour of the central galaxy. We find a very strong large-scale environmental dependence of the satellite-central alignment in groups with blue centrals. Satellites of blue centrals in knots are preferentially located perpendicular to the major axis of the centrals, and the alignment angle decreases with environment namely when going from knots to voids. The alignment angle strongly depend on the 0.1 (g − r) colour of centrals. We suggest that the satellite-central alignment is the result of a competition between satellite accretion within large scale-structure and galaxy evolution inside host haloes. For groups containing red central galaxies, the satellite-central alignment is mainly determined by the evolution effect, while for blue central dominated groups, the effect of large-scale structure plays a more important role, especially in knots. Our results provide an explanation for how the satellite-central alignment forms within different largescale environments. The perpendicular case in groups and knots with blue centrals may also provide insight into understanding similar polar arrangements such the formation of the Milky Way and Centaurus A's satellite system.

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