Three-Leaf Dart-Shaped Single-Crystal BN Formation Promoted by Surface Oxygen

Two-dimensional hexagonal boron nitride (h-BN) single crystals with various shapes have been synthesized by chemical vapor deposition over the past several years. Here we report the formation of three-leaf dart (3LD)-shaped single crystals of h-BN on Cu foil by atmospheric-pressure chemical vapor deposition. The leaves of the 3LD-shaped h-BN are as long as 18 {\mu}m and their edges are smooth armchair on one side and stepped armchair on the other. Careful analysis revealed that surface oxygen plays an important role in the formation of the 3LD shape. Oxygen suppressed h-BN nucleation by passivating Cu surface active sites and lowered the edge attachment energy, which caused the growth kinetics to change to a diffusion-controlled mode.Comment: 7 pages,6 figure

Treating the Expansive Soil Subgrade on the Goaf of Middle-Shallow Layer by Dynamic Compaction With Geogrid Reinforcement

Middle-shallow layer goaf left after the excavation of small coal mines in expansive soil areas always brings much trouble to expressway construction, the section of K21 +400~K22 +550 of Nanning outer ring expressway under construction faces such a situation. Based on the grasp of geological condition of the goaf, related national technical specifications and existing technical research about treatment, the dynamic compaction with geogird reinforcement method is applied to settle the roadbed with a good result showed in the field testing. This paper introduces the geological condition and stability evaluation of the goaf, and emphatically presents the technical note, construction procedure, quality inspection of the dynamic compaction with geogird reinforcement and the filling method of the upper expansive soil subgrade, which can offer a reference for the similar treatment projects in other expansive soil areas

Estimating the central charge from the R\'enyi entanglement entropy

We calculate the von Neumann and R\'enyi bipartite entanglement entropy of the $O(2)$ model with a chemical potential on a 1+1 dimensional Euclidean lattice with open and periodic boundary conditions. We show that the Calabrese-Cardy conformal field theory predictions for the leading logarithmic scaling with the spatial size of these entropies are consistent with a central charge $c=1$. This scaling survives the time continuum limit and truncations of the microscopic degrees of freedom, modifications which allow us to connect the Lagrangian formulation to quantum Hamiltonians. At half-filling, the forms of the subleading corrections imposed by conformal field theory allow the determination of the central charge with an accuracy better than two percent for moderately sized lattices. We briefly discuss the possibility of estimating the central charge using quantum simulators.Comment: 10 pages, 8 figures, 3 table