Reversible Non-Volatile Electronic Switching in a Near Room Temperature van der Waals Ferromagnet

The ability to reversibly toggle between two distinct states in a non-volatile method is important for information storage applications. Such devices have been realized for phase-change materials, which utilizes local heating methods to toggle between a crystalline and an amorphous state with distinct electrical properties. To expand such kind of switching between two topologically distinct phases requires non-volatile switching between two crystalline phases with distinct symmetries. Here we report the observation of reversible and non-volatile switching between two stable and closely-related crystal structures with remarkably distinct electronic structures in the near room temperature van der Waals ferromagnet Fe$_{5-\delta}$GeTe$_2$. From a combination of characterization techniques we show that the switching is enabled by the ordering and disordering of an Fe site vacancy that results in distinct crystalline symmetries of the two phases that can be controlled by a thermal annealing and quenching method. Furthermore, from symmetry analysis as well as first principle calculations, we provide understanding of the key distinction in the observed electronic structures of the two phases: topological nodal lines compatible with the preserved global inversion symmetry in the site-disordered phase, and flat bands resulting from quantum destructive interference on a bipartite crystaline lattice formed by the presence of the site order as well as the lifting of the topological degeneracy due to the broken inversion symmetry in the site-ordered phase. Our work not only reveals a rich variety of quantum phases emergent in the metallic van der Waals ferromagnets due to the presence of site ordering, but also demonstrates the potential of these highly tunable two-dimensional magnets for memory and spintronics applications

Effect of Floor Openings on Evacuation Efficiency in Multipurpose Commercial Buildings: IFC Mall in Yeouido, Seoul, Korea

To achieve evacuation-optimized design at the architectural planning phase, this study analyzed the effect of floor openings in multipurpose commercial buildings on their evacuation efficiency. Herein, the IFC Mall in Yeouido, Seoul, Korea was considered the study site, because all the factors influencing the evacuation efficiency can be controlled owing to the underground location of all floors. Therefore, all evacuees followed the same evacuation direction. Comprehensively, a spatial analysis methodology (Cellular ECEM) was employed to derive the evacuation costs through the sum of visibility cost and distance cost. Subsequently, the evacuation costs were compared in all cases to review the hindrances in evacuation according to the type and area ratio of the planned floor opening, and several causes of evacuation cost deviations were discussed. Overall, increasing the area of the floor opening deteriorates the evacuation efficiency. The evacuation efficiency increased if the area of the floor opening is appropriately separated and a bridge is constructed in the middle to connect a path. Furthermore, following the longer path around the floor opening to use the main vertical means of circulation, owing to the connection between the atrium and floor opening, is more vulnerable toward evacuation efficiency than other floor opening types

Direct Observation of Localized Spin Antiferromagnetic Transition in PdCrO2 by Angle-Resolved Photoemission Spectroscopy

We report the first case of the successful measurements of a localized spin antiferromagnetic transition in delafossite-type PdCrO2 by angle-resolved photoemission spectroscopy (ARPES). This demonstrates how to circumvent the shortcomings of ARPES for investigation of magnetism involved with localized spins in limited size of two-dimensional crystals or multi-layer thin films that neutron scattering can hardly study due to lack of bulk compared to surface. Also, our observations give direct evidence for the spin orderingpattern of Cr31 ions in PdCrO2 suggested by neutron diffraction and quantum oscillation measurements,and provide a strong constraint that has to be satisfied by a microscopic mechanism for the unconventional anomalous Hall effect recently reported in this system. (c)2014, Nature Publishing Group. All rights reserved.118161sciescopu

Impact of preoperative nonselective beta-blocker use on acute kidney injury after living donor liver transplantation: Propensity score analysis

Introduction and Objectives: Acute kidney injury (AKI) is prevalent and has deleterious effects on postoperative outcomes following liver transplantation (LT). The impact of nonselective beta-blockers (NSBBs) in patients with liver cirrhosis remains controversial. This study investigated the association between preoperative NSBB use and AKI after living donor LT (LDLT). Patients and Methods: We evaluated 2,972 adult LDLT recipients between January 2012 and July 2022. The patients were divided into two groups based on the preoperative NSBB use. Propensity score matched (PSM) and inverse probability of treatment weighting (IPTW) analyses were performed to evaluate the association between preoperative NSBB use and postoperative AKI. Multiple logistic regression analyses were also used to identify the risk factors for AKI. Results: The overall incidence of AKI was 1,721 (57.9%) cases. The NSBB group showed a higher incidence of AKI than the non-NSBB group (62.4% vs. 56.7%; P = 0.011). After PSM and IPTW analyses, no significant difference in the incidence of AKI was found between the two groups (Odds ratio, OR 1.13, 95% confidence interval, CI 0.93–1.37, P = 0.230, PSM analysis; OR 1.20, 95% CI 0.99–1.44, P = 0.059, IPTW analysis). In addition, preoperative NSBB use was not associated with AKI after multivariate logistic regression analysis (OR 1.16, 95% CI 0.96–1.40, P = 0.118). Conclusions: Preoperative NSBB use was not associated with AKI after LDLT. Further studies are needed to validate our results