Fraying by Sika Deer (Cervus nippon) in an Evergreen Broadleaf Forest in Miyajima Island, Hiroshima, Japan

The fraying by sika deer (Cervus nippon) in an evergreen broadleaf forest in Miyajima Island, Hiroshima, Japan, was studied. The proportion of trees frayed by deer to the total trees sampled (N = 1209) was 8.1%. Our data suggest that sika deer performed fraying on trees irrespective of diameter at breast height. We found that of the 29 tree species examined, 16 were frayed. Cleyera japonica had a significantly higher proportion of trees frayed by sika deer than the average overall proportion, suggesting that the species attracts sika deer for fraying. By contrast, sika deer significantly avoided Pinus densiflora, Lyonia ovalifolia var. elliptica, and Eurya japonica for fraying. Trees frayed were significantly spatially distributed aggregately. The fraying by deer occurred randomly, regardless of slope angles; sika deer can perform fraying even on very steep slopes. Trees on ridges avoided being frayed by deer, however. This may be explained by the presence of the trees that were less favored for sika-fraying performance (Pinus densiflora, Lyonia ovalifolia var. elliptica, and Eurya japonica), which were mainly distributed on ridge sites

Evaluation of Tensile Performance of Steel Members by Analysis of Corroded Steel Surface Using Deep Learning

To conduct safety checks of corroded steel structures and formulate appropriate maintenance strategies, the residual strength of steel structural members must be assessed with high accuracy. Finite element method (FEM) analyses that precisely recreate the morphology of corroded surfaces using solid elements are expected to accurately assess the strength; however, the cost of conducting these calculations is extremely high. Therefore, a model that uses mean thickness as the thickness of the shell element is widely used but this method has precision issues, particularly regarding overestimation of risk. Thus, this study proposes a method of structural analysis in which the effective thickness of a shell element is assessed using the convolutional neural network (CNN), a type of deep learning performed on tensile structural members. An FEM model is then built based on the shell element that uses this effective thickness. We cross-validated this method by adding a feature extraction layer that reflects the domain knowledge, together with convolutional and pooling layers that are commonly used for CNN and found that a high level of accuracy could be achieved. Furthermore, regarding corroded steel plates and H-section steel, our method demonstrated results that were extremely close to those of models that used solid elements

Interaction between alkali metals and diamond: Etching and charge states of NV centers

Single crystal diamond particles were heated with liquid phase alkali metals (Li, Na, K) in an argon atmosphere. It was found that Li reacts with the diamond above 600 degrees C, Na makes the surface rougher on a nm scale at 800 degrees C, and K did not change the surface morphology. The etching speed by the reaction with Li is the fastest on the (001) surface. Photoluminescence of the NV- (negatively charged nitrogen vacancy) center decreased only after the annealing with K. DFT calculations explained the strong chemical interaction between Li and the diamond (001) surfaces, and upward band bending at the interfaces with Na and K. The behavior of the NV-center photoluminescence is consistent with the extent of band bending. (C) 2021 Elsevier Ltd. All rights reserved

Band Structure Evolution during Reversible Interconversion between Dirac and Standard Fermions in Organic Charge-Transfer Salts

Materials containing Dirac fermions (DFs) have been actively researched because they often alter electrical and magnetic properties in an unprecedented manner. Although many studies have suggested the transformation between standard fermions (SFs) and DFs, the non-availability of appropriate samples has prevented the observation of the transformation process. We observed the interconversion process of DFs and SFs using organic charge-transfer (CT) salts. The samples are unique in that the constituents (the donor D and acceptor A species) are particularly close to each other in energy, leading to the temperature- and D-A-combination-sensitive CT interactions in the solid states. The three-dimensional weak D–A CT interactions in low-symmetry crystals induced the continuous reshaping of flat-bottomed bands into Dirac cones with decreasing temperature; this is a characteristic shape of bands that converts the behavior of SFs into that of DFs. Based on the first-principles band structures supported by the observed electronic properties, round-apex-Dirac-cone-like features appear and disappear with temperature variation. These band-structure snapshots are expected to add further detailed understanding to the related research fields