scholarly journals Pulse Discharging of Sodium-Oxygen Batteries to Enhance Cathode Utilization

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5650
Author(s):  
Daniel Langsdorf ◽  
Timo Dahms ◽  
Valerie Mohni ◽  
Julian Jakob Alexander Kreissl ◽  
Daniel Schröder
Keyword(s):  
Energy Density ◽  
Dissolved Oxygen ◽  
Three Dimensional ◽  
Full Potential ◽  
Void Space ◽  
Aprotic Electrolyte ◽  
Discharge Product ◽  
Battery Discharge ◽  
First Time ◽  
Discharge Capacities

Using sodium metal in sodium-oxygen batteries with aprotic electrolyte enables achieving a very high theoretical energy density. However, the promised values for energy density and capacity are not met in practical studies yet due to poor utilization of the void space in the cathode during battery discharge. In this work, we achieve better cathode utilization and higher discharge capacities by using pulse discharging. We optimize the chosen resting-to-pulse times, the applied current density, and elucidate that three-dimensional cathode materials yield higher capacities compared to two-dimensional ones. By implication, the pulse discharging mode ensures better supply with dissolved oxygen within the cathode. The higher amount of dissolved oxygen accumulated during the resting period after a current pulse is essential to form more of the discharge product, i.e., the metal oxide sodium superoxide. Interestingly, we show for the first time that the superoxide is deposited in a very unusual form of stacked and highly oriented crystal layers. Our findings on the pulse discharging can be transferred to other metal-oxygen battery systems and might assist in achieving their full potential regarding practical energy density.

scholarly journals Cobalt-based magnetic Weyl semimetals with high-thermodynamic stabilities

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wei Luo ◽  
Yuma Nakamura ◽  
Jinseon Park ◽  
Mina Yoon
Keyword(s):  
Tight Binding ◽  
Three Dimensional ◽  
Interlayer Coupling ◽  
First Principles Calculation ◽  
Optimization Approach ◽  
Binding Model ◽  
Nodal Lines ◽  
Weyl Semimetal ◽  
Topological Quantum ◽  
First Time

AbstractRecent experiments identified Co3Sn2S2 as the first magnetic Weyl semimetal (MWSM). Using first-principles calculation with a global optimization approach, we explore the structural stabilities and topological electronic properties of cobalt (Co)-based shandite and alloys, Co3MM’X2 (M/M’ = Ge, Sn, Pb, X = S, Se, Te), and identify stable structures with different Weyl phases. Using a tight-binding model, for the first time, we reveal that the physical origin of the nodal lines of a Co-based shandite structure is the interlayer coupling between Co atoms in different Kagome layers, while the number of Weyl points and their types are mainly governed by the interaction between Co and the metal atoms, Sn, Ge, and Pb. The Co3SnPbS2 alloy exhibits two distinguished topological phases, depending on the relative positions of the Sn and Pb atoms: a three-dimensional quantum anomalous Hall metal, and a MWSM phase with anomalous Hall conductivity (~1290 Ω−1 cm−1) that is larger than that of Co2Sn2S2. Our work reveals the physical mechanism of the origination of Weyl fermions in Co-based shandite structures and proposes topological quantum states with high thermal stability.

scholarly journals Shell-crossing in a ΛCDM Universe

2020 ◽  
Vol 501 (1) ◽  
pp. L71-L75
Author(s):  
Cornelius Rampf ◽  
Oliver Hahn
Keyword(s):  
Dark Matter ◽  
Perturbation Theory ◽  
Large Scale ◽  
Cold Dark Matter ◽  
Three Dimensional ◽  
Random Initial Data ◽  
Recursion Relations ◽  
Indispensable Tool ◽  
First Time ◽  
Very High

ABSTRACT Perturbation theory is an indispensable tool for studying the cosmic large-scale structure, and establishing its limits is therefore of utmost importance. One crucial limitation of perturbation theory is shell-crossing, which is the instance when cold-dark-matter trajectories intersect for the first time. We investigate Lagrangian perturbation theory (LPT) at very high orders in the vicinity of the first shell-crossing for random initial data in a realistic three-dimensional Universe. For this, we have numerically implemented the all-order recursion relations for the matter trajectories, from which the convergence of the LPT series at shell-crossing is established. Convergence studies performed at large orders reveal the nature of the convergence-limiting singularities. These singularities are not the well-known density singularities at shell-crossing but occur at later times when LPT already ceased to provide physically meaningful results.

scholarly journals Alternative derivation of the higher-order constitutive model for six-parameter elastic shells

2021 ◽  
Vol 72 (2) ◽  
Author(s):  
Mircea Bîrsan
Keyword(s):  
Energy Density ◽  
Constitutive Model ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Shell Theory ◽  
Constitutive Relations ◽  
Three Dimensional ◽  
Classical Shell Theory ◽  
Three Dimensional Elasticity ◽  
General Method

AbstractIn this paper, we present a general method to derive the explicit constitutive relations for isotropic elastic 6-parameter shells made from a Cosserat material. The dimensional reduction procedure extends the methods of the classical shell theory to the case of Cosserat shells. Starting from the three-dimensional Cosserat parent model, we perform the integration over the thickness and obtain a consistent shell model of order $$ O(h^5) $$ O ( h 5 ) with respect to the shell thickness h. We derive the explicit form of the strain energy density for 6-parameter (Cosserat) shells, in which the constitutive coefficients are expressed in terms of the three-dimensional elasticity constants and depend on the initial curvature of the shell. The obtained form of the shell strain energy density is compared with other previous variants from the literature, and the advantages of our constitutive model are discussed.

scholarly journals Imaging the Human Thyroid Using Three-Dimensional Diffuse Optical Tomography: A Preliminary Study

2021 ◽  
Vol 11 (4) ◽  
pp. 1670
Author(s):  
Tetsuya Mimura ◽  
Shinpei Okawa ◽  
Hiroshi Kawaguchi ◽  
Yukari Tanikawa ◽  
Yoko Hoshi
Keyword(s):  
Optical Tomography ◽  
Tumor Hypoxia ◽  
Three Dimensional ◽  
Diffuse Optical Tomography ◽  
Element Model ◽  
Needle Aspiration ◽  
Human Thyroid ◽  
Tissue Oxygen Saturation ◽  
Preliminary Study ◽  
First Time

Thyroid cancer is usually diagnosed by ultrasound imaging and fine-needle aspiration biopsy. However, diagnosis of follicular thyroid carcinomas (FTC) is difficult because FTC lacks nuclear atypia and a consensus on histological interpretation. Diffuse optical tomography (DOT) offers the potential to diagnose FTC because it can measure tumor hypoxia, while image reconstruction of the thyroid is still challenging mainly due to the complex anatomical features of the neck. In this study, we attempted to solve this issue by creating a finite element model of the human neck excluding the trachea (a void region). By reconstruction of the absorption coefficients at three wavelengths, 3D tissue oxygen saturation maps of the human thyroid are obtained for the first time by DOT.

scholarly journals The on-axis magnetic well and Mercier's criterion for arbitrary stellarator geometries

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
P. Kim ◽  
R. Jorge ◽  
W. Dorland
Keyword(s):  
Magnetic Field ◽  
Original Work ◽  
Three Dimensional ◽  
Radial Distance ◽  
Analytical Form ◽  
One Dimensional ◽  
Modern Notation ◽  
Magnetic Well ◽  
First Time ◽  
Dimensional Integral

A simplified analytical form of the on-axis magnetic well and Mercier's criterion for interchange instabilities for arbitrary three-dimensional magnetic field geometries is derived. For this purpose, a near-axis expansion based on a direct coordinate approach is used by expressing the toroidal magnetic flux in terms of powers of the radial distance to the magnetic axis. For the first time, the magnetic well and Mercier's criterion are then written as a one-dimensional integral with respect to the axis arclength. When compared with the original work of Mercier, the derivation here is presented using modern notation and in a more streamlined manner that highlights essential steps. Finally, these expressions are verified numerically using several quasisymmetric and non-quasisymmetric stellarator configurations including Wendelstein 7-X.

scholarly journals Towards an Improved Model of the Galaxy

1998 ◽  
Vol 11 (1) ◽  
pp. 570-570
Author(s):  
Johan Holmberg ◽  
Lennart Lindegren ◽  
Chris Flynn
Keyword(s):  
Three Dimensional ◽  
Direct Determination ◽  
Galactic Structure ◽  
Open Clusters ◽  
Selection Effects ◽  
Observational Errors ◽  
Red Giant ◽  
Improved Model ◽  
First Time ◽  
Hr Diagram

We use the Hipparcos survey to derive an improved model of the local galactic structure. The availability of parallaxes for all the stars permits direct determination of stellar distributions, eliminating the basic indeterminacy of classical methods based on star counts. Hipparcos gives for the first time a truly three-dimensional view of the solar vicinity, and a complete, homogeneous and highly accurate set of magnitudes and colours. This means that new techniques can be applied in the treatment of the data which place strong constraints on a model that tries to describe the local Galactic structure. Here we investigate how well a static model of low complexitycan describe the Hipparcos observations. The interpretation of the Hipparcos data is complicated by various observational errors and selection effects that are hard to treat correctly. We do not try to correct the data, but instead use a model and subject this model to the same observational errors and selection effects. A model catalogue is created that can be compared with the observed catalogue directly in the observational domain, thereby eliminating the effects from various biases. Many features in the HR diagram are for the first time seen in field stars thanks to Hipparcos, such as the slanted red giant clump, previously seen in rich old open clusters such as Berkeley 18. This and other features ofthe observed HR diagram are well reproduced by the model thanks to the rather detailed modelling of the joint Mv/B — V distribution. Actually, separate distributions were derived for the three different components, disk, thick disk and halo, using the kinematic characteristics of the components to discriminate between them.

A New Category of Three-Dimensional Chaotic Flows with Identical Eigenvalues

2020 ◽  
Vol 30 (02) ◽  
pp. 2050026 ◽  
Author(s):  
Zahra Faghani ◽  
Fahimeh Nazarimehr ◽  
Sajad Jafari ◽  
Julien C. Sprott
Keyword(s):  
Chaotic Systems ◽  
Autonomous Systems ◽  
Three Dimensional ◽  
Special Property ◽  
Computer Search ◽  
Chaotic Flows ◽  
Stable Equilibria ◽  
Dynamical Properties ◽  
Simple Systems ◽  
First Time

In this paper, some new three-dimensional chaotic systems are proposed. The special property of these autonomous systems is their identical eigenvalues. The systems are designed based on the general form of quadratic jerk systems with 10 terms, and some systems with stable equilibria. Using a systematic computer search, 12 simple chaotic systems with identical eigenvalues were found. We believe that systems with identical eigenvalues are described here for the first time. These simple systems are listed in this paper, and their dynamical properties are investigated.

scholarly journals Structure of the Lectin Mannose 6-Phosphate Receptor Homology (MRH) Domain of Glucosidase II, an Enzyme That Regulates Glycoprotein Folding Quality Control in the Endoplasmic Reticulum

2013 ◽  
Vol 288 (23) ◽  
pp. 16460-16475 ◽  
Author(s):  
Linda J. Olson ◽  
Ramiro Orsi ◽  
Solana G. Alculumbre ◽  
Francis C. Peterson ◽  
Ivan D. Stigliano ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Three Dimensional ◽  
Binding Pocket ◽  
Dimensional Structure ◽  
Mannose Residue ◽  
Glucosidase Ii ◽  
Mannose 6 Phosphate ◽  
First Time ◽  
Conserved Residue

Here we report for the first time the three-dimensional structure of a mannose 6-phosphate receptor homology (MRH) domain present in a protein with enzymatic activity, glucosidase II (GII). GII is involved in glycoprotein folding in the endoplasmic reticulum. GII removes the two innermost glucose residues from the Glc3Man9GlcNAc2 transferred to nascent proteins and the glucose added by UDP-Glc:glycoprotein glucosyltransferase. GII is composed of a catalytic GIIα subunit and a regulatory GIIβ subunit. GIIβ participates in the endoplasmic reticulum localization of GIIα and mediates in vivo enhancement of N-glycan trimming by GII through its C-terminal MRH domain. We determined the structure of a functional GIIβ MRH domain by NMR spectroscopy. It adopts a β-barrel fold similar to that of other MRH domains, but its binding pocket is the most shallow known to date as it accommodates a single mannose residue. In addition, we identified a conserved residue outside the binding pocket (Trp-409) present in GIIβ but not in other MRHs that influences GII glucose trimming activity.

scholarly journals Thermalization of synchrotron radiation from field-aligned currents

1988 ◽  
Vol 6 (3) ◽  
pp. 493-501 ◽  
Author(s):  
William Peter ◽  
Anthony L. Peratt
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Energy Density ◽  
Radiation Spectrum ◽  
Axial Magnetic Field ◽  
Three Dimensional ◽  
Synchrotron Emission ◽  
Microwave Background ◽  
Strong Function ◽  
Current Filaments

Three-dimensional plasma simulations of interacting galactic-dimensioned current filaments show bursts of synchroton radiation of energy density 1·2 ×10−13 erg/cm3 which can be compared with the measured cosmic microwave background energy density of 1·5 × 10−13 erg/cm3. However, the synchrotron emission observed in the simulations is not blackbody. In this paper, we analyze the absorption of the synchrotron emission by the current filaments themselves (i.e., self-absorption) in order to investigate the thermalization of the emitted radiation. It is found that a large number of current filaments (>1031) are needed to make the radiation spectrum blackbody up to the observed measured frequency of 100 GHz. The radiation spectrum and the required number of current filaments is a strong function of the axial magnetic field in the filaments.

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