scholarly journals Beta-PdBi2 Monolayer: Two-Dimensional Topological Metal with Superior Catalytic Activity for Carbon Dioxide Electroreduction to Formic Acid

2020 ◽  
Author(s):  
Xiaorong Zhu ◽  
Yu Wang ◽  
Yu Jing ◽  
Thomas Heine ◽  
Yafei Li
Keyword(s):  
Catalytic Activity ◽  
Large Scale ◽  
Three Dimensional ◽  
Layered Materials ◽  
Spin Orbit Coupling ◽  
Two Dimensional ◽  
Promising Candidate ◽  
Onset Potential ◽  
Promising Solution ◽  
2D Crystals

The lack of efficient electrocatalysts has been a main obstacle for the large-scale commercialization of CO<sub>2</sub> electroreduction. In this work, we demonstrate that two-dimensional (2D) beta-PdBi<sub>2</sub> mono-layer is a promising solution for this issue. beta-PdBi<sub>2</sub> monolayer is a stable 2D crystal and the three-dimensional (3D) bulk interlayer energy is similar as for other layered materials that can be exfoliated into 2D crystals. Interestingly, beta-PdBi<sub>2</sub> monolayer has rather intri-guing electronic properties: while being metallic, it also has a non-trivial topological point. Remarkably, the extra electronic states at the Fermi level induced by the intrinsic spinorbit coupling (SOC) effect significantly enhance the adsorption of OCHO* intermediate on beta-PdBi<sub>2</sub> monolayer, resulting in a rather small onset potential of -0.26 V vs. RHE for CO<sub>2</sub> electroreduction to HCOOH. These results not only suggest a promising candidate for CO<sub>2</sub> electrolysis but also deepen our understanding of the factors dominating the catalytic activity of 2D materials. <br>

scholarly journals Beta-PdBi2 Monolayer: Two-Dimensional Topological Metal with Superior Catalytic Activity for Carbon Dioxide Electroreduction to Formic Acid

2020 ◽  
Author(s):  
Xiaorong Zhu ◽  
Yu Wang ◽  
Yu Jing ◽  
Thomas Heine ◽  
Yafei Li
Keyword(s):  
Catalytic Activity ◽  
Large Scale ◽  
Three Dimensional ◽  
Layered Materials ◽  
Spin Orbit Coupling ◽  
Two Dimensional ◽  
Promising Candidate ◽  
Onset Potential ◽  
Promising Solution ◽  
2D Crystals

The lack of efficient electrocatalysts has been a main obstacle for the large-scale commercialization of CO<sub>2</sub> electroreduction. In this work, we demonstrate that two-dimensional (2D) beta-PdBi<sub>2</sub> mono-layer is a promising solution for this issue. beta-PdBi<sub>2</sub> monolayer is a stable 2D crystal and the three-dimensional (3D) bulk interlayer energy is similar as for other layered materials that can be exfoliated into 2D crystals. Interestingly, beta-PdBi<sub>2</sub> monolayer has rather intri-guing electronic properties: while being metallic, it also has a non-trivial topological point. Remarkably, the extra electronic states at the Fermi level induced by the intrinsic spinorbit coupling (SOC) effect significantly enhance the adsorption of OCHO* intermediate on beta-PdBi<sub>2</sub> monolayer, resulting in a rather small onset potential of -0.26 V vs. RHE for CO<sub>2</sub> electroreduction to HCOOH. These results not only suggest a promising candidate for CO<sub>2</sub> electrolysis but also deepen our understanding of the factors dominating the catalytic activity of 2D materials. <br>

Two-Dimensional Crystallization of Tetanus Toxin

1985 ◽  
Vol 43 ◽  
pp. 528-529
Author(s):  
Jeffry A. Reidler ◽  
John P. Robinson
Keyword(s):  
Electron Microscopy ◽  
Tetanus Toxin ◽  
Structural Information ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Membrane Interface ◽  
3D Reconstructions ◽  
Cellular Receptors ◽  
Computer Reconstruction ◽  
2D Crystals

We have prepared two-dimensional (2D) crystals of tetanus toxin using procedures developed by Uzgiris and Kornberg for the directed production of 2D crystals of monoclonal antibodies at an antigen-phospholipid monolayer interface. The tetanus toxin crystals were formed using a small mole fraction of the natural receptor, GT1, incorporated into phosphatidyl choline monolayers. The crystals formed at low concentration overnight. Two dimensional crystals of this type are particularly useful for structure determination using electron microscopy and computer image refinement. Three dimensional (3D) structural information can be derived from these crystals by computer reconstruction of photographs of toxin crystals taken at different tilt angles. Such 3D reconstructions may help elucidate the mechanism of entry of the enzymatic subunit of toxins into cells, particularly since these crystals form directly on a membrane interface at similar concentrations of ganglioside GT1 to the natural cellular receptors.

Bereziskii-Kosterlitz-Thouless transition in the Weyl system PtBi2

2021 ◽  
Author(s):  
Arthur Veyrat ◽  
Valentin Labracherie ◽  
Rohith Acharya ◽  
Dima Bashlakov ◽  
Federico Caglieris ◽  
...  
Keyword(s):  
Condensed Matter ◽  
Three Dimensional ◽  
Spin Orbit Coupling ◽  
Two Dimensional ◽  
Pairing Mechanism ◽  
Critical Fields ◽  
Weyl Semimetal ◽  
Superconducting Coherence Length ◽  
Low Dimensional ◽  
Strong Spin

Abstract Symmetry breaking in topological matter became, in the last decade, a key concept in condensed matter physics to unveil novel electronic states. In this work, we reveal that broken inversion symmetry and strong spin-orbit coupling in trigonal PtBi2 lead to a Weyl semimetal band structure, with unusually robust two-dimensional superconductivity in thin fims. Transport measurements show that high-quality PtBi2 crystals are three-dimensional superconductors (Tc≈600 mK) with an isotropic critical field (Bc≈50 mT). Remarkably, we evidence in a rather thick flake (60 nm), exfoliated from a macroscopic crystal, the two-dimensional nature of the superconducting state, with a critical temperature Tc≈370 mK and highly-anisotropic critical fields. Our results reveal a Berezinskii-Kosterlitz-Thouless transition with TBKT≈310 mK and with a broadening of Tc due to inhomogenities in the sample. Due to the very long superconducting coherence length ξ in PtBi2, the vortex-antivortex pairing mechanism can be studied in unusually-thick samples (at least five times thicker than for any other two-dimensional superconductor), making PtBi2 an ideal platform to study low dimensional superconductivity in a topological semimetal.

scholarly journals Three-Dimensional Response of the Supported-Deep Excavation System: Case Study of a Large Scale Underground Metro Station

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 76
Author(s):  
Ashraf Hefny ◽  
Mohamed Ezzat Al-Atroush ◽  
Mai Abualkhair ◽  
Mariam Juma Alnuaimi
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Two Dimensional ◽  
Deep Excavation ◽  
Metro Station ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The complexities and the economic computational infeasibility associated in some cases, with three-dimensional finite element models, has imposed a motive for many investigators to accept numerical modeling simplification solutions such as assuming two-dimensional (2D) plane strain conditions in simulation of several supported-deep excavation problems, especially for cases with a relatively high aspect ratio in plan dimensions. In this research, a two-dimensional finite element model was established to simulate the behavior of the supporting system of a large-scale deep excavation utilized in the construction of an underground metro station Rod El Farrag project (Egypt). The essential geotechnical engineering properties of soil layers were calculated using results of in-situ and laboratory tests and empirical correlations with SPT-N values. On the other hand, a three-dimensional finite element model was established with the same parameters adopted in the two-dimensional model. Sufficient sensitivity numerical analyses were performed to make the three-dimensional finite element model economically feasible. Results of the two-dimensional model were compared with those obtained from the field measurements and the three-dimensional numerical model. The comparison results showed that 3D high stiffening at the primary walls’ corners and also at the locations of cross walls has a significant effect on both the lateral wall deformations and the neighboring soil vertical settlement.

First-Principles Study on the Electronic Structure of Bulk and Single-Layer Boehmite

NANO ◽  
2018 ◽  
Vol 13 (12) ◽  
pp. 1850138
Author(s):  
Seungwook Son ◽  
Dongwook Kim ◽  
Sutassana Na-Phattalung ◽  
Jisoon Ihm
Keyword(s):  
Hydrogen Bonding ◽  
First Principles ◽  
Single Layer ◽  
Layered Materials ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Promising Candidate ◽  
Electronic Band ◽  
2D Layered Materials ◽  
Electronic Band Structures

Two-dimensional (2D) or layered materials have a great potential for applications in energy storage, catalysis, optoelectronics and gas separation. Fabricating novel 2D or quasi-2D layered materials composed of relatively abundant and inexpensive atomic species is an important issue for practical usage in industry. Here, we suggest the layer-structured AlOOH (Boehmite) as a promising candidate for such applications. Boehmite is a well-known layer-structured material and a single-layer can be exfoliated from the bulk boehmite by breaking the interlayer hydrogen bonding. We study atomic and electronic band structures of both bulk and single-layer boehmite, and also obtain the single-layer exfoliation energy using first-principles calculations.

Novel Simplification Approach for Large-Scale Structural Models of Coal: Three-Dimensional Molecules to Two-Dimensional Lattices. Part 3: Reactive Lattice Simulations

2013 ◽  
Vol 27 (6) ◽  
pp. 2915-2922 ◽  
Author(s):  
Yesica E. Alvarez ◽  
Brian M. Moreno ◽  
Michael T. Klein ◽  
Justin K. Watson ◽  
Fidel Castro-Marcano ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Structural Models ◽  
Two Dimensional

Numerical Simulations of an Unsteady Confined Natural Convection Flow

2009 ◽  
Author(s):  
Gillian Leplat ◽  
Emmanuel Laroche ◽  
Philippe Reulet ◽  
Pierre Millan
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Large Scale ◽  
Critical Rayleigh Number ◽  
Three Dimensional ◽  
High Amplitude ◽  
Joint Fluid ◽  
Convection Flow ◽  
Two Dimensional ◽  
Natural Convection Flow

A two-dimensional numerical analysis of a laminar natural convection flow within an air-filled enclosure is proposed in this paper from an unstable configuration previously studied experimentally. The flow is driven by a heated square-section cylinder located at the center of a square-section enclosure. Instabilities are observed for an aspect ratio (height of the cylinder over the height of the cavity) of 0.4 and cause the flow to turn into a three-dimensional and unsteady regime characterized by a symmetry breaking and large scale high amplitude flappings around the cylinder. The multi-physic computational software CEDRE, developed at the ONERA, is used to study this unstable behavior and a time-dependent compressible flow solver is used to perform the two-dimensional simulations under the low Mach number approximation, corresponding to the mid-depth cross-section of the enclosure from the experimental configuration. The first results on the investigation of the first unstable modes confirm the onset of the instabilities at the Rayleigh number of the experiment with asymmetrical motions of the fluid around the cylinder. Further analyses highlight the critical Rayleigh number that defines the instability threshold of the first bifurcation which origin and nature could have been identified. Finally, joint fluid-solid simulations are performed to determine more precisely the role of boundary conditions in the onset of instabilities.

scholarly journals Development of three-dimensional wetting and drying algorithm for the Geophysical Scale Transport Multi-Block Hydrodynamic Sediment and Water Quality Transport Modeling System (GSMB)

2021 ◽  
Author(s):  
Ray Chapman ◽  
Phu Luong ◽  
Sung-Chan Kim ◽  
Earl Hayter
Keyword(s):  
Water Quality ◽  
Water Wave ◽  
Large Scale ◽  
Three Dimensional ◽  
The United States ◽  
Technical Note ◽  
Three Dimensions ◽  
Transport Modeling ◽  
Two Dimensional ◽  
Wetting And Drying

The Environmental Laboratory (EL) and the Coastal and Hydraulics Laboratory (CHL) have jointly completed a number of large-scale hydrodynamic, sediment and water quality transport studies. EL and CHL have successfully executed these studies utilizing the Geophysical Scale Transport Modeling System (GSMB). The model framework of GSMB is composed of multiple process models as shown in Figure 1. Figure 1 shows that the United States Army Corps of Engineers (USACE) accepted wave, hydrodynamic, sediment and water quality transport models are directly and indirectly linked within the GSMB framework. The components of GSMB are the two-dimensional (2D) deep-water wave action model (WAM) (Komen et al. 1994, Jensen et al. 2012), data from meteorological model (MET) (e.g., Saha et al. 2010 - http://journals.ametsoc.org/doi/pdf/10.1175/2010BAMS3001.1), shallow water wave models (STWAVE) (Smith et al. 1999), Coastal Modeling System wave (CMS-WAVE) (Lin et al. 2008), the large-scale, unstructured two-dimensional Advanced Circulation (2D ADCIRC) hydrodynamic model (http://www.adcirc.org), and the regional scale models, Curvilinear Hydrodynamics in three dimensions-Multi-Block (CH3D-MB) (Luong and Chapman 2009), which is the multi-block (MB) version of Curvilinear Hydrodynamics in three-dimensions-Waterways Experiments Station (CH3D-WES) (Chapman et al. 1996, Chapman et al. 2009), MB CH3D-SEDZLJ sediment transport model (Hayter et al. 2012), and CE-QUAL Management - ICM water quality model (Bunch et al. 2003, Cerco and Cole 1994). Task 1 of the DOER project, “Modeling Transport in Wetting/Drying and Vegetated Regions,” is to implement and test three-dimensional (3D) wetting and drying (W/D) within GSMB. This technical note describes the methods and results of Task 1. The original W/D routines were restricted to a single vertical layer or depth-averaged simulations. In order to retain the required 3D or multi-layer capability of MB-CH3D, a multi-block version with variable block layers was developed (Chapman and Luong 2009). This approach requires a combination of grid decomposition, MB, and Message Passing Interface (MPI) communication (Snir et al. 1998). The MB single layer W/D has demonstrated itself as an effective tool in hyper-tide environments, such as Cook Inlet, Alaska (Hayter et al. 2012). The code modifications, implementation, and testing of a fully 3D W/D are described in the following sections of this technical note.

scholarly journals Smooth Nonlinear Fitting Scheme for Analog Multiplierless Implementation of Hindmarsh-Rose Neuron Model

2021 ◽  
Author(s):  
Jianming Cai ◽  
Han Bao ◽  
Quan Xu ◽  
Zhongyun Hua ◽  
Bocheng Bao
Keyword(s):  
Large Scale ◽  
Neuron Model ◽  
Hardware Implementation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Implementation Cost ◽  
Hyperbolic Tangent ◽  
Nonlinear Fitting ◽  
Chaotic Bursting ◽  
Electrical Activities

Abstract The Hindmarsh-Rose (HR) neuron model is built to describe the neuron electrical activities. Due to the polynomial nonlinearities, multipliers are required to implement the HR neuron model in analog. In order to avoid the multipliers, this brief presents a novel smooth nonlinear fitting scheme. We first construct two nonlinear fitting functions using the composite hyperbolic tangent functions and then implement an analog multiplierless circuit for the two-dimensional (2D) or three- dimensional (3D) HR neuron model. To exhibit the nonlinear fitting effects, numerical simulations and hardware experiments for the fitted HR neuron model are provided successively. The results show that the fitted HR neuron model with analog multiplierless circuit can display different operation patterns of resting, periodic spiking, and periodic/chaotic bursting, entirely behaving like the original HR neuron model. The analog multiplierless circuit has the advantage of low implementation cost and thereby it might be suitable for the hardware implementation of large-scale neural networks.

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