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- Broadhurst, Edward, et al.
(författare)
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The Effect of High Pressure on Polymorphs of a Derivative of Blatter's Radical : Identification of the Structural Signatures of Subtle Phase Transitions
- 2023
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 23:3, s. 1915-1924
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Tidskriftsartikel (refereegranskat)abstract
- The effect of pressure on the alpha and beta polymorphs of a derivative of Blatter's radical, 3-phenyl-1-(pyrid-2-yl)-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl, has been investigated using single-crystal X-ray diffraction to maximum pressures of 5.76 and 7.42 GPa, respectively. The most compressible crystallographic direction in both structures lies parallel to pi-stacking interactions, which semiempirical Pixel calculations indicate are also the strongest interactions present. The mechanism of compression in perpendicular directions is determined by void distributions. Discontinuities in the vibrational frequencies observed in Raman spectra measured between ambient pressure and similar to 5.5 GPa show that both polymorphs undergo phase transitions, the alpha phase at 0.8 GPa and the beta phase at 2.1 GPa. The structural signatures of the transitions, which signal the onset of compression of initially more rigid intermolecular contacts, were identified from the trends in the occupied and unoccupied volumes of the unit cell with pressure and in the case of the beta phase by deviations from an ideal model of compression defined by Birch-Murnaghan equations of state.
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- Ramirez, Kelly S., et al.
(författare)
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Detecting macroecological patterns in bacterial communities across independent studies of global soils
- 2018
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Ingår i: Nature Microbiology. - : NATURE PUBLISHING GROUP. - 2058-5276. ; 3:2, s. 189-196
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of high-throughput DNA sequencing methods provides unprecedented opportunities to further unravel bacterial biodiversity and its worldwide role from human health to ecosystem functioning. However, despite the abundance of sequencing studies, combining data from multiple individual studies to address macroecological questions of bacterial diversity remains methodically challenging and plagued with biases. Here, using a machine-learning approach that accounts for differences among studies and complex interactions among taxa, we merge 30 independent bacterial data sets comprising 1,998 soil samples from 21 countries. Whereas previous meta-analysis efforts have focused on bacterial diversity measures or abundances of major taxa, we show that disparate amplicon sequence data can be combined at the taxonomy-based level to assess bacterial community structure. We find that rarer taxa are more important for structuring soil communities than abundant taxa, and that these rarer taxa are better predictors of community structure than environmental factors, which are often confounded across studies. We conclude that combining data from independent studies can be used to explore bacterial community dynamics, identify potential 'indicator' taxa with an important role in structuring communities, and propose hypotheses on the factors that shape bacterial biogeography that have been overlooked in the past.
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