Density of states of a graphene in the presence of strong point defects

The density of states near zero energy in a graphene due to strong point defects with random positions are computed. Instead of focusing on density of states directly, we analyze eigenfunctions of inverse T-matrix in the unitary limit. Based on numerical simulations, we find that the squared magnitudes of eigenfunctions for the inverse T-matrix show random-walk behavior on defect positions. As a result, squared magnitudes of eigenfunctions have equal {\it a priori} probabilities, which further implies that the density of states is characterized by the well-known Thomas-Porter type distribution. The numerical findings of Thomas-Porter type distribution is further derived in the saddle-point limit of the corresponding replica field theory of inverse T-matrix. Furthermore, the influences of the Thomas-Porter distribution on magnetic and transport properties of a graphene, due to its divergence near zero energy, are also examined.Comment: 6 figure

Isolation of Xylose Fermentation Strains for Ethanol Production and Xylose Fermentation Research

Xylose is abundant in lignocellulosic biomass. The fermentation of xylose is still a key problem in cellulose ethanol fermentation. In this research, the xylose fermentation strains were isolated from the soil sample. Strain N6 was chosen for further xylose fermentation experiments. Comparison of its 16S rDNA gene sequence with available sequences in GenBank showed that it was 100 % identical to that of Bacillus cereus strain SWFU2816 (Accession No. JN935015.1). Strain N6, which ferments xylose and hexose to ethanol, can produce fuel ethanol. The ability of strain N6 to transform xylose was better than its ability to transform glucose. As a result, the optimal condition for xylose fermentation was determined. The optimum fermentation conditions at 150 rpm for 48 h in a shake flask were as follows: pH 7.0, reducing sugar 70 g L–1, inoculation amount 5 %, and temperature 38 °C. The xylose to ethanol yield coefficient could reach a maximum of 0.26 g g–1. At the same time, the influence of the acid hydrolysis by-products on the isolated strain was studied. Compared to the commonly used saccharomycetes, the tolerance of strain N6 on furaldehyde had greatly improved, which could help ethanol fermentation from lignocellulose materials

Numerical analysis and case study on the mitigation of mining damage to the floor of no. 5 coal seam of Taiyuan Group by grouting

Based on the geological condition of panel 22507 of the no. 5 coal seam at Dongjiahe coal mine, numerical analysis of the stability and water permeability of the floor aquiclude before and after grouting was conducted using Rock Failure Process Analysis (F-RFPA2D). The dynamic development, extension, and distribution of the cracks in the aquiclude are discussed. It is shown that grouting can increase the effective thickness of the aquiclude, reduce the floor damage depth, and control the floor water inrush path, thus effectively improving the overall strength and water blocking capability of the aquiclude. These numerical study results were applied to facilitate relevant engineering work at Dongjiahe coal mine. The mitigation measures involved grouting the floor of the no. 5 coal seam, allowing panel 22507 to be mined safely above confined water. This exercise provided invaluable experience in preventing water inrush hazards