RESUMO
The correlation properties of a random system of densely packed disks, obeying a power-law size distribution, are analyzed in reciprocal space in the thermodynamic limit. This limit assumes that the total number of disks increases infinitely, while the mean density of the disk centers and the range of the size distribution are kept constant. We investigate the structure factor dependence on momentum transfer across various number of disks and extrapolate these findings to the thermodynamic limit. The fractal power-law decay of the structure factor is recovered in reciprocal space within the fractal range, which corresponds to the range of the size distribution in real space. The fractal exponent coincides with the exponent of the power-law size distribution as was shown previously by the authors of the work of Cherny et al. [J. Chem. Phys. 158(4), 044114 (2023)]. The dependence of the structure factor on density is examined. As is found, the power-law exponent remains unchanged but the fractal range shrinks when the packing fraction decreases. Additionally, the finite-size effects are studied at extremely low momenta of the order of the inverse system size. We show that the structure factor is parabolic in this region and calculate the prefactor analytically. The obtained results reveal fractal-like properties of the packing and can be used to analyze small-angle scattering from such systems.
RESUMO
Creation of artificial forest plantations on a global scale is one of the ways to mitigate the negative effects of climate change on ecosystems, at the same time providing soil protection from erosion, regulation of the hydrological regime and carbon sequestration in soils of different natural and climatic zones. However, the change of the dominant plant community cause significant ecosystem changes, reflecting at the structure and functioning of the soil microbial complex as well. The shifts in prokaryotic community of the meadow soil resulting from the conversion of the native meadow (further grassland) phytocenosis to the artificial forest plantations was investigated with the use of NGS sequencing technology and metabarcoding approach-amplicon sequencing of V4 region of 16 S rRNA (performed on Illumina Miseq platform). The identified shifts in taxonomic structure and diversity may be the result of changes in the physic-chemical conditions of soils and, on the other hand, may serve as indicators of such changes. Cultivation of larch led to an increase in the diversity of the prokaryotic community and its stratification by depth. The acidifying effect of larch manifested itself in an increase in the proportion and diversity of acidobacteria, in the abundance of oligotrophic microorganisms of phyla Chloroflexi, Firmicutes, and a simultaneous comparative decrease in the bacteria of Verrucomicrobia phylum, alphaproteobacteria of or. Rhizobiales and Burkholderiales. The absence of clearly expressed dominants in the prokaryotic community, as well as a significant increase in alpha-diversity indices, compared with the control plot of native mountain-meadow soil under grassland vegetation, suggests a transitional nature of the soil ecosystem of artificial forest plantations.
