TY - JOUR
AB - Electrodepositing insulating lithium peroxide (Li2O2) is the key process during discharge of aprotic Li–O2 batteries and determines rate, capacity, and reversibility. Current understanding states that the partition between surface adsorbed and dissolved lithium superoxide governs whether Li2O2 grows as a conformal surface film or larger particles, leading to low or high capacities, respectively. However, better understanding governing factors for Li2O2 packing density and capacity requires structural sensitive in situ metrologies. Here, we establish in situ small- and wide-angle X-ray scattering (SAXS/WAXS) as a suitable method to record the Li2O2 phase evolution with atomic to submicrometer resolution during cycling a custom-built in situ Li–O2 cell. Combined with sophisticated data analysis, SAXS allows retrieving rich quantitative structural information from complex multiphase systems. Surprisingly, we find that features are absent that would point at a Li2O2 surface film formed via two consecutive electron transfers, even in poorly solvating electrolytes thought to be prototypical for surface growth. All scattering data can be modeled by stacks of thin Li2O2 platelets potentially forming large toroidal particles. Li2O2 solution growth is further justified by rotating ring-disk electrode measurements and electron microscopy. Higher discharge overpotentials lead to smaller Li2O2 particles, but there is no transition to an electronically passivating, conformal Li2O2 coating. Hence, mass transport of reactive species rather than electronic transport through a Li2O2 film limits the discharge capacity. Provided that species mobilities and carbon surface areas are high, this allows for high discharge capacities even in weakly solvating electrolytes. The currently accepted Li–O2 reaction mechanism ought to be reconsidered.
AU - Prehal, Christian
AU - Samojlov, Aleksej
AU - Nachtnebel, Manfred
AU - Lovicar, Ludek
AU - Kriechbaum, Manfred
AU - Amenitsch, Heinz
AU - Freunberger, Stefan Alexander
ID - 9301
IS - 14
JF - Proceedings of the National Academy of Sciences
KW - small-angle X-ray scattering
KW - oxygen reduction
KW - disproportionation
KW - Li-air battery
SN - 0027-8424
TI - In situ small-angle X-ray scattering reveals solution phase discharge of Li–O2 batteries with weakly solvating electrolytes
VL - 118
ER -
TY - JOUR
AB - Endoplasmic reticulum–plasma membrane contact sites (ER–PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis thaliana mutants lacking the ER–PM protein tether synaptotagmin1 (SYT1) exhibit decreased PM integrity under multiple abiotic stresses, such as freezing, high salt, osmotic stress, and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER–PM tether that also functions in maintaining PM integrity. The ER–PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to wild-type while the levels of most glycerolipid species remain unchanged. In addition, the SYT1-green fluorescent protein fusion preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work uncovers a SYT-dependent mechanism of stress adaptation counteracting the detrimental accumulation of diacylglycerol at the PM produced during episodes of abiotic stress.
AU - Ruiz-Lopez, N
AU - Pérez-Sancho, J
AU - Esteban Del Valle, A
AU - Haslam, RP
AU - Vanneste, S
AU - Catalá, R
AU - Perea-Resa, C
AU - Van Damme, D
AU - García-Hernández, S
AU - Albert, A
AU - Vallarino, J
AU - Lin, J
AU - Friml, Jiří
AU - Macho, AP
AU - Salinas, J
AU - Rosado, A
AU - Napier, JA
AU - Amorim-Silva, V
AU - Botella, MA
ID - 9443
JF - Plant Cell
SN - 1040-4651
TI - Synaptotagmins at the endoplasmic reticulum-plasma membrane contact sites maintain diacylglycerol homeostasis during abiotic stress
ER -
TY - JOUR
AB - Lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) based water-in-salt electrolytes (WiSEs) has recently emerged as a new promising class of electrolytes, primarily owing to their wide electrochemical stability windows (~3–4 V), that by far exceed the thermodynamic stability window of water (1.23 V). Upon increasing the salt concentration towards superconcentration the onset of the oxygen evolution reaction (OER) shifts more significantly than the hydrogen evolution reaction (HER) does. The OER shift has been explained by the accumulation of hydrophobic anions blocking water access to the electrode surface, hence by double layer theory. Here we demonstrate that the processes during oxidation are much more complex, involving OER, carbon and salt decomposition by OER intermediates, and salt precipitation upon local oversaturation. The positive shift in the onset potential of oxidation currents was elucidated by combining several advanced analysis techniques: rotating ring-disk electrode voltammetry, online electrochemical mass spectrometry, and X-ray photoelectron spectroscopy, using both dilute and superconcentrated electrolytes. The results demonstrate the importance of reactive OER intermediates and surface films for electrolyte and electrode stability and motivate further studies of the nature of the electrode.
AU - Maffre, Marion
AU - Bouchal, Roza
AU - Freunberger, Stefan Alexander
AU - Lindahl, Niklas
AU - Johansson, Patrik
AU - Favier, Frédéric
AU - Fontaine, Olivier
AU - Bélanger, Daniel
ID - 9447
IS - 5
JF - Journal of The Electrochemical Society
KW - Renewable Energy
KW - Sustainability and the Environment
KW - Electrochemistry
KW - Materials Chemistry
KW - Electronic
KW - Optical and Magnetic Materials
KW - Surfaces
KW - Coatings and Films
KW - Condensed Matter Physics
SN - 0013-4651
TI - Investigation of electrochemical and chemical processes occurring at positive potentials in “Water-in-Salt” electrolytes
VL - 168
ER -
TY - JOUR
AB - Given a locally finite set 𝑋⊆ℝ𝑑 and an integer 𝑘≥0, we consider the function 𝐰𝑘:Del𝑘(𝑋)→ℝ on the dual of the order-k Voronoi tessellation, whose sublevel sets generalize the notion of alpha shapes from order-1 to order-k (Edelsbrunner et al. in IEEE Trans Inf Theory IT-29:551–559, 1983; Krasnoshchekov and Polishchuk in Inf Process Lett 114:76–83, 2014). While this function is not necessarily generalized discrete Morse, in the sense of Forman (Adv Math 134:90–145, 1998) and Freij (Discrete Math 309:3821–3829, 2009), we prove that it satisfies similar properties so that its increments can be meaningfully classified into critical and non-critical steps. This result extends to the case of weighted points and sheds light on k-fold covers with balls in Euclidean space.
AU - Edelsbrunner, Herbert
AU - Nikitenko, Anton
AU - Osang, Georg F
ID - 9465
IS - 1
JF - Journal of Geometry
SN - 00472468
TI - A step in the Delaunay mosaic of order k
VL - 112
ER -
TY - CONF
AB - We firstly introduce the self-assembled growth of highly uniform Ge quantum wires with controllable position, distance and length on patterned Si (001) substrates. We then present the electrically tunable strong spin-orbit coupling, the first Ge hole spin qubit and ultrafast operation of hole spin qubit in the Ge/Si quantum wires.
AU - Gao, Fei
AU - Zhang, Jie Yin
AU - Wang, Jian Huan
AU - Ming, Ming
AU - Wang, Tina
AU - Zhang, Jian Jun
AU - Watzinger, Hannes
AU - Kukucka, Josip
AU - Vukušić, Lada
AU - Katsaros, Georgios
AU - Wang, Ke
AU - Xu, Gang
AU - Li, Hai Ou
AU - Guo, Guo Ping
ID - 9464
SN - 9781728181769
T2 - 2021 5th IEEE Electron Devices Technology and Manufacturing Conference, EDTM 2021
TI - Ge/Si quantum wires for quantum computing
ER -
TY - JOUR
AB - In this paper, we consider reflected three-operator splitting methods for monotone inclusion problems in real Hilbert spaces. To do this, we first obtain weak convergence analysis and nonasymptotic O(1/n) convergence rate of the reflected Krasnosel'skiĭ-Mann iteration for finding a fixed point of nonexpansive mapping in real Hilbert spaces under some seemingly easy to implement conditions on the iterative parameters. We then apply our results to three-operator splitting for the monotone inclusion problem and consequently obtain the corresponding convergence analysis. Furthermore, we derive reflected primal-dual algorithms for highly structured monotone inclusion problems. Some numerical implementations are drawn from splitting methods to support the theoretical analysis.
AU - Iyiola, Olaniyi S.
AU - Enyi, Cyril D.
AU - Shehu, Yekini
ID - 9469
JF - Optimization Methods and Software
SN - 10556788
TI - Reflected three-operator splitting method for monotone inclusion problem
ER -
TY - JOUR
AB - A key step in understanding the genetic basis of different evolutionary outcomes (e.g., adaptation) is to determine the roles played by different mutation types (e.g., SNPs, translocations and inversions). To do this we must simultaneously consider different mutation types in an evolutionary framework. Here, we propose a research framework that directly utilizes the most important characteristics of mutations, their population genetic effects, to determine their relative evolutionary significance in a given scenario. We review known population genetic effects of different mutation types and show how these may be connected to different evolutionary outcomes. We provide examples of how to implement this framework and pinpoint areas where more data, theory and synthesis are needed. Linking experimental and theoretical approaches to examine different mutation types simultaneously is a critical step towards understanding their evolutionary significance.
AU - Berdan, Emma L.
AU - Blanckaert, Alexandre
AU - Slotte, Tanja
AU - Suh, Alexander
AU - Westram, Anja M
AU - Fragata, Inês
ID - 9470
IS - 12
JF - Molecular Ecology
SN - 09621083
TI - Unboxing mutations: Connecting mutation types with evolutionary consequences
VL - 30
ER -
TY - JOUR
AB - Motivated by the successful application of geometry to proving the Harary--Hill conjecture for “pseudolinear” drawings of $K_n$, we introduce “pseudospherical” drawings of graphs. A spherical drawing of a graph $G$ is a drawing in the unit sphere $\mathbb{S}^2$ in which the vertices of $G$ are represented as points---no three on a great circle---and the edges of $G$ are shortest-arcs in $\mathbb{S}^2$ connecting pairs of vertices. Such a drawing has three properties: (1) every edge $e$ is contained in a simple closed curve $\gamma_e$ such that the only vertices in $\gamma_e$ are the ends of $e$; (2) if $e\ne f$, then $\gamma_e\cap\gamma_f$ has precisely two crossings; and (3) if $e\ne f$, then $e$ intersects $\gamma_f$ at most once, in either a crossing or an end of $e$. We use properties (1)--(3) to define a pseudospherical drawing of $G$. Our main result is that for the complete graph, properties (1)--(3) are equivalent to the same three properties but with “precisely two crossings” in (2) replaced by “at most two crossings.” The proof requires a result in the geometric transversal theory of arrangements of pseudocircles. This is proved using the surprising result that the absence of special arcs (coherent spirals) in an arrangement of simple closed curves characterizes the fact that any two curves in the arrangement have at most two crossings. Our studies provide the necessary ideas for exhibiting a drawing of $K_{10}$ that has no extension to an arrangement of pseudocircles and a drawing of $K_9$ that does extend to an arrangement of pseudocircles, but no such extension has all pairs of pseudocircles crossing twice.
AU - Arroyo Guevara, Alan M
AU - Richter, R. Bruce
AU - Sunohara, Matthew
ID - 9468
IS - 2
JF - SIAM Journal on Discrete Mathematics
SN - 08954801
TI - Extending drawings of complete graphs into arrangements of pseudocircles
VL - 35
ER -
TY - JOUR
AB - Brain neurons arise from relatively few progenitors generating an enormous diversity of neuronal types. Nonetheless, a cardinal feature of mammalian brain neurogenesis is thought to be that excitatory and inhibitory neurons derive from separate, spatially segregated progenitors. Whether bi-potential progenitors with an intrinsic capacity to generate both lineages exist and how such a fate decision may be regulated are unknown. Using cerebellar development as a model, we discover that individual progenitors can give rise to both inhibitory and excitatory lineages. Gradations of Notch activity determine the fates of the progenitors and their daughters. Daughters with the highest levels of Notch activity retain the progenitor fate, while intermediate levels of Notch activity generate inhibitory neurons, and daughters with very low levels of Notch signaling adopt the excitatory fate. Therefore, Notch-mediated binary cell fate choice is a mechanism for regulating the ratio of excitatory to inhibitory neurons from common progenitors.
AU - Zhang, Tingting
AU - Liu, Tengyuan
AU - Mora, Natalia
AU - Guegan, Justine
AU - Bertrand, Mathilde
AU - Contreras, Ximena
AU - Hansen, Andi H
AU - Streicher, Carmen
AU - Anderle, Marica
AU - Danda, Natasha
AU - Tiberi, Luca
AU - Hippenmeyer, Simon
AU - Hassan, Bassem A.
ID - 8546
IS - 10
JF - Cell Reports
TI - Generation of excitatory and inhibitory neurons from common progenitors via Notch signaling in the cerebellum
VL - 35
ER -
TY - JOUR
AB - We prove that the energy of any eigenvector of a sum of several independent large Wigner matrices is equally distributed among these matrices with very high precision. This shows a particularly strong microcanonical form of the equipartition principle for quantum systems whose components are modelled by Wigner matrices.
AU - Bao, Zhigang
AU - Erdös, László
AU - Schnelli, Kevin
ID - 9550
JF - Forum of Mathematics, Sigma
TI - Equipartition principle for Wigner matrices
VL - 9
ER -