Modeling of structured electrodes in lithium-sulfur batteries

Due to their high theoretical capacity lithium-sulfur batteries (Li/S) are envisioned as next-generation storage technology for electric vehicles [1]. However, several challenges obviate a successful commercialization of the battery. Most of them are related to the high solubility of intermediate polysulfide species and the resulting so-called ‘shuttle effect’. The transport of polysulfides between positive and negative electrode causes a decay of capacity and low coulombic efficiency upon cycling. Experimental studies [2] demonstrate that nano-structuring of carbon/sulphur composite electrodes significantly improves the cyclability of the battery. Micro-porous particles [3], hollow carbon spheres (HCS) or carbon nano tubes (CNTs) are used to encapsulate the sulphur and to prevent transport of polysulfides to the anode. In our contribution we present results of a detailed 1D single particle continuum model describing reaction and transport inside a representative spherical particle [4], [5]. On the surface we assume that only lithium ions are able to enter and leave the particle. This relatively simple model gives some interesting insights on the behavior of the particle during battery operation. Most prominently, we identified an additional overpotential during discharge resulting from the transport of Li ions against a concentration gradient into the particle. In a following step we couple the single particle model to a macroscopic model of a full battery cell. Results of the 1+1D full cell simulations are parameterized and validated based on experimental data [3]. Systematic parameter studies reveal the influence of novel electrode geometries on battery performance and are able to guide future improvements in electrode design

Microstructure of Silica in the Presence of Iron Oxide

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65543/1/j.1151-2916.1960.tb14328.x.pd

Vp/Vs ratio of incoming sediments off Cascadia subduction zone from analysis of controlled-source multicomponent OBS records

Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 125(6), (2020): e2019JB019239, doi:10.1029/2019JB019239.P‐to‐S‐converted waves observed in controlled‐source multicomponent ocean bottom seismometer (OBS) records were used to derive the Vp/Vs structure of Cascadia Basin sediments. We used P‐to‐S waves converted at the basement to derive an empirical function describing the average Vp/Vs of Cascadia sediments as a function of sediment thickness. We derived one‐dimensional interval Vp/Vs functions from semblance velocity analysis of S‐converted intrasediment and basement reflections, which we used to define an empirical Vp/Vs versus burial depth compaction trend. We find that seaward from the Cascadia deformation front, Vp/Vs structure offshore northern Oregon and Washington shows little variability along strike, while the structure of incoming sediments offshore central Oregon is more heterogeneous and includes intermediate‐to‐deep sediment layers of anomalously elevated Vp/Vs. These zones with elevated Vp/Vs are likely due to elevated pore fluid pressures, although layers of high sand content intercalated within a more clayey sedimentary sequence, and/or a higher content of coarser‐grained clay minerals relative to finer‐grained smectite could be contributing factors. We find that the proto‐décollement offshore central Oregon develops within the incoming sediments at a low‐permeability boundary that traps fluids in a stratigraphic level where fluid overpressure exceeds 50% of the differential pressure between the hydrostatic pressure and the lithostatic pressure. Incoming sediments with the highest estimated fluid overpressures occur offshore central Oregon where deformation of the accretionary prism is seaward vergent. Conversely, landward vergence offshore northern Oregon and Washington correlates with more moderate pore pressures and laterally homogeneous Vp/Vs functions of Cascadia Basin sediments.This research was funded by National Science Foundation (NSF) Grant OCE‐1657237 to J. P. C, OCE‐1657839 to A. F. A. and S. H., and OCE‐1657737 to S. M. C. Data used in this study were acquired with funding from NSF Grants OCE‐1029305 and OCE‐1249353. Data used in this research were provided by instruments from the Ocean Bottom Seismic Instrument Center (http://obsic.whoi.edu, formerly OBSIP), which is funded by the NSF. OBSIC/OBSIP data are archived at the IRIS Data Management Center (http://www.iris.edu) under network code X6 (https://doi.org/10.7914/SN/X6_2012). Data processing was conducted with Emerson‐Paradigm Software package Echos licensed to Woods Hole Oceanographic Institution under Paradigm Academic Software Program and MATLAB package SeismicLab of the University of Alberta, Canada (http://seismic-lab.physics.ualberta.ca), under GNU General Public License (MATLAB® is a registered trademark of MathWorks).2020-11-2

Stacked magma lenses beneath mid-ocean ridges: insights from new seismic observations and synthesis with prior geophysical and geologic findings

Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 126(4), (2021): e2020JB021434, https://doi.org/10.1029/2020JB021434.Recent multi-channel seismic studies of fast spreading and hot-spot influenced mid-ocean ridges reveal magma bodies located beneath the mid-crustal Axial Magma Lens (AML), embedded within the underlying crustal mush zone. We here present new seismic images from the Juan de Fuca Ridge that show reflections interpreted to be from vertically stacked magma lenses in a number of locations beneath this intermediate-spreading ridge. The brightest reflections are beneath Northern Symmetric segment, from ∼46°42′-52′N and Split Seamount, where a small magma body at local Moho depths is also detected, inferred to be a source reservoir for the stacked magma lenses in the crust above. The imaged magma bodies are sub-horizontal, extend continuously for along-axis lengths of ∼1–8 km, with the shallowest located at depths of ∼100–1,200 m below the AML, and are similar to sub-AML bodies found at the East Pacific Rise. At both ridges, stacked sill-like lenses are detected beneath only a small fraction of the ridge length examined and are inferred to mark local sites of higher melt flux and active replenishment from depth. The imaged magma lenses are focused in the upper part of the lower crust, which coincides with the most melt rich part of the crystal mush zone detected in other geophysical studies and where sub-vertical fabrics are observed in geologic exposures of oceanic crust. We infer that the multi-level magma accumulations are ephemeral and may result from porous flow and mush compaction, and that they can be tapped and drained during dike intrusion and eruption events.This research was supported by NSF OCE 0002488 and 0648303 (LDEO), 0002551 (WHOI), 1658199 and 1357076 (UTIG). S. M. Carbotte was partially supported by Columbia University and J. P. Canales by the Independent Research & Development Program at WHOI

Editorial: Semantic Algorithms in the Assessment of Attitudes and Personality

Editorial on the Research Topic Semantic Algorithms in the Assessment of Attitudes and Personalit

Appeals to semiotic registers in ethno-metapragmatic accounts of variation

Discussions of folklinguistic accounts of language use are frequently focused on dismissing them because of their limitations. As a result, not a lot is written regarding how such accounts are done and how they ‘work’. This article examines how folklinguistic evaluations are achieved in interaction, particularly through appeals to semiotic registers (Agha 2007). It describes how in explaining their beliefs regarding linguistic variation, speakers frequently produce voicings with varying transparency. These rely on understandings of the social world and bring large collections of linguistic resources into play. They offer rich insights if analytic attention is given to their details because even when evaluating a single variant, whole ways of speaking, and even being, may be utilized. The paper explores in turn how analysis reveals the inseparability of variants, understandings of context and audience, the relationship between linguistic forms and social types, and the performance of social types via the evaluation of semiotic resources. In each section, discussion is grounded in extracts from interviews on Australian English with speakers of this variety of English. Cumulatively they show the primacy of semiotic registers in ethno-metapragmatic accounts.N/

Interferon β-1a in relapsing multiple sclerosis: four-year extension of the European IFNβ-1a Dose-C omparison Study

Background: Multiple sclerosis (MS) is a chronic disease requiring long-term monitoring of treatment. Objective: To assess the four-year clinical efficacy of intramuscular (IM) IFNb-1a in patients with relapsing MS from the European IFNb-1a Dose-C omparison Study. Methods: Patients who completed 36 months of treatment (Part 1) of the European IFNb-1a Dose-C omparison Study were given the option to continue double-blind treatment with IFNb-1a 30 mcg or 60 mcg IM once weekly (Part 2). Analyses of 48-month data were performed on sustained disability progression, relapses, and neutralizing antibody (NA b) formation. Results: O f 608/802 subjects who completed 36 months of treatment, 493 subjects continued treatment and 446 completed 48 months of treatment and follow-up. IFNb-1a 30 mcg and 60 mcg IM once weekly were equally effective for up to 48 months. There were no significant differences between doses over 48 months on any of the clinical endpoints, including rate of disability progression, cumulative percentage of patients who progressed (48 and 43, respectively), and annual relapse rates; relapses tended to decrease over 48 months. The incidence of patients who were positive for NAbs at any time during the study was low in both treatment groups. Conclusion: C ompared with 60-mcg IM IFNb-1a once weekly, a dose of 30 mcg IM IFNb-1a once weekly maintains the same clinical efficacy over four years

Anatomy of an active submarine volcano

Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Geological Society of America for personal use, not for redistribution. The definitive version was published in Geology 42 (2014): 655-658, doi:10.1130/G35629.1.Most of the magma erupted at mid-ocean ridges is stored in a mid-crustal melt lens that lies at the boundary between sheeted dikes and gabbros. Nevertheless, images of the magma pathways linking this melt lens to the overlying eruption site have remained elusive. Here, we have used seismic methods to image the thickest magma reservoir observed beneath any spreading center to date, which is principally attributed to the juxtaposition of the Juan de Fuca Ridge with the Cobb hotspot. Our results reveal a complex melt body beneath the summit caldera, which is ~14 km long, 3 km wide and up to 1 km thick. The estimated volume of the reservoir is 18–30 km3, more than two orders of magnitude greater than the erupted magma volumes of the 1998 and 2011 eruptions. Our images show a network of sub-horizontal to shallow dipping (<30°) features that we interpret as pathways facilitating melt transport from the magma reservoir to the eruption sites.This research was funded through a National Science Foundation grant, OCE- 0002600, and additionally supported through the Cecil H. and Ida M. Green Foundation at the Scripps Institution of Oceanography.2015-06-0