414 results match your criteria pushing mechanism

Theoretical Insights into Excited-State Intermolecular Proton Transfers of 2,7-Diazaindole in Water Using a Microsolvation Approach.

J Phys Chem A 2021 Jun 14;125(24):5314-5325. Epub 2021 Jun 14.

Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.

The detailed excited-state intermolecular proton transfer (ESInterPT) mechanism of 2,7-diazaindole with water wires consisting of either one or two shells [2,7-DAI(HO); = 1-5] has been theoretically explored by time-dependent density functional theory using microsolvation with an implicit solvent model. On the basis of the excited-state potential energy surfaces along the proton transfer (PT) coordinates, among all 2,7-DAI(HO), the multiple ESInterPT of 2,7-DAI(HO) through the first hydration shell (inner circuit) is the most easy process to occur with the lowest PT barrier and a highly exothermic reaction. The lowest PT barrier resulted from the outer three waters pushing the inner circuit waters to be much closer to 2,7-DAI, leading to the enhanced intermolecular hydrogen-bonding strength of the inner two waters. Read More

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Broadening the Scope of the Zwitterionic 1,3-Diaza-Claisen Rearrangement through a Tethering Strategy.

J Org Chem 2021 Jun 9;86(12):8197-8215. Epub 2021 Jun 9.

Department of Chemistry, University of Vermont, Burlington, Vermont 05405, United States.

Expansion of the scope of the 1,3-diaza-Claisen rearrangement beyond bridged-bicyclic tertiary allylic amines has been investigated through a tethering strategy. Isothioureas tethered to tertiary allylic amines are converted to carbodiimides through a reaction with AgOTf/EtN. Intramolecular cyclization of the tertiary allylic amine to the carbodiimide equilibrates with a zwitterionic intermediate. Read More

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The push-to-open mechanism of the tethered mechanosensitive ion channel NompC.

Elife 2021 Jun 8;10. Epub 2021 Jun 8.

Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.

NompC is a mechanosensitive ion channel responsible for the sensation of touch and balance in . Based on a resolved cryo-EM structure, we performed all-atom molecular dynamics simulations and electrophysiological experiments to study the atomistic details of NompC gating. Our results showed that NompC could be opened by compression of the intracellular ankyrin repeat domain but not by a stretch, and a number of hydrogen bonds along the force convey pathway are important for the mechanosensitivity. Read More

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Monocytic MDSC mobilization promotes tumor recurrence after liver transplantation via CXCL10/TLR4/MMP14 signaling.

Cell Death Dis 2021 May 14;12(5):489. Epub 2021 May 14.

Department of Surgery, HKU-SZH & Faculty of Medicine, The University of Hong Kong, Hong Kong, China.

Tumor recurrence is the major obstacle for pushing the envelope of liver transplantation for hepatocellular carcinoma (HCC) patients. The inflammatory cascades activated by acute liver graft injury promote tumor recurrence. We aimed to explore the role and mechanism of myeloid-derived suppressor cell (MDSC) mobilization induced by liver graft injury on tumor recurrence. Read More

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The structural features of an ancient ribonuclease from Salmo salar reveal an intriguing case of auto-inhibition.

Int J Biol Macromol 2021 Apr 15;182:659-668. Epub 2021 Apr 15.

Department of Biology, University of Naples Federico II, Complesso Universitario di Monte Sant'Angelo, Via Cintia, I-80126 Naples, Italy.

The superfamily of vertebrate ribonucleases, a large group of evolutionarily related proteins, continues to provide interesting structural and functional information. In particular, the crystal structure of SS-RNase-2 from Salmo salar (SS2), here presented, has revealed a novel auto-inhibition mechanism that enriches the number of inhibition strategies observed in some members of the family. Within an essentially unmodified RNase folding, the SS2 active site cleft is in part obstructed by the collapse of an extra pentapeptide inserted in the C-terminal region. Read More

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Hepatic Arterial Buffer Response in Liver Radioembolization and Potential Use for Improved Cancer Therapy.

Cancers (Basel) 2021 Mar 26;13(7). Epub 2021 Mar 26.

Nuclear Medicine Department, Cliniques Universitaires Saint-Luc, 1200 Brussels, Belgium.

Liver radioembolization is a treatment option for unresectable liver cancers, performed by infusion of Y or Ho loaded spheres in the hepatic artery. As tumoral cells are mainly perfused via the liver artery unlike hepatic lobules, a twofold tumor to normal liver dose ratio is commonly obtained. To improve tumoral cell killing while preserving lobules, co-infusion of arterial vasoconstrictor has been proposed but with limited success: the hepatic arterial buffer response (HABR) and hepatic vascular escape mechanism hamper the arterioles vasoconstriction. Read More

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Self-organized patterning of cell morphology via mechanosensitive feedback.

Elife 2021 Mar 26;10. Epub 2021 Mar 26.

Cluster of Excellence Physics of Life, Technische Universität Dresden, Dresden, Germany.

Tissue organization is often characterized by specific patterns of cell morphology. How such patterns emerge in developing tissues is a fundamental open question. Here, we investigate the emergence of tissue-scale patterns of cell shape and mechanical tissue stress in the wing imaginal disc during larval development. Read More

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Integrative Insights into the Myoelastic-Aerodynamic Theory and Acoustics of Phonation. Scientific Tribute to Donald G. Miller.

J Voice 2021 Mar 17. Epub 2021 Mar 17.

National Center for Voice and Speech, University of Utah, Salt Lake City, Utah.

In this tribute article to D.G. Miller, we review some historical and recent contributions to understanding the myoelastic-aerodynamic (MEAD) theory of phonation and the related acoustic phenomena in subglottal and vocal tract. Read More

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Sensor-Less and Control-Less Underactuated Grippers With Pull-In Mechanisms for Grasping Various Objects.

Front Robot AI 2021 22;8:631242. Epub 2021 Feb 22.

Department of Robotics, Ritsumeikan University, Shiga, Japan.

This paper proposes an underactuated grippers mechanism that grasps and pulls in different types of objects. These two movements are generated by only a single actuator while two independent actuators are used in conventional grippers. To demonstrate this principle, we have developed two kinds of gripper by different driving systems: one is driven by a DC motor with planetary gear reducers and another is driven by pneumatic actuators with branch tubes as a differential. Read More

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February 2021

[Metabonomics study of Shouhui Tongbian Capsules in slow transit constipation based on UPLC-ESI-QE-Orbitrap-MS].

Zhongguo Zhong Yao Za Zhi 2021 Feb;46(3):532-538

Center for New Drug Pharmacology, Lunan Pharmaceutical Group Co., Ltd. Linyi 276006, China State Key Laboratory of Generic Manufacture Technology of Chinese Traditional Medicine Linyi 276006 China Linyi Key Laboratory for Immunopharmacology and Immunotoxicology of Natural Medicine Linyi 276006, China.

The effect of Shouhui Tongbian Capsules(SHTB) on the endogenous metabolites of colon tissue in mice with slow transit constipation was analyzed by metabolomics methods to explore its mechanism in the treatment of constipation. ICR mice were randomly divided into normal group, model group and SHTB group according to the body weight. The mice were given diphenoxylate to establish the slow transit constipation model. Read More

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February 2021

Cellular Pushing Forces during Mitosis Drive Mitotic Elongation in Collagen Gels.

Adv Sci (Weinh) 2021 Feb 4;8(4):2000403. Epub 2021 Jan 4.

Department of Mechanical Engineering Stanford University 418 Panama Mall Stanford CA 94305 USA.

Cell elongation along the division axis, or mitotic elongation, mediates proper segregation of chromosomes and other intracellular materials, and is required for completion of cell division. In three-dimensionally confining extracellular matrices, such as dense collagen gels, dividing cells must generate space to allow mitotic elongation to occur. In principle, cells can generate space for mitotic elongation during cell spreading, prior to mitosis, or via extracellular force generation or matrix degradation during mitosis. Read More

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February 2021

Investigating the nature of active forces in tissues reveals how contractile cells can form extensile monolayers.

Nat Mater 2021 Feb 18. Epub 2021 Feb 18.

Université de Paris, CNRS, Institut Jacques Monod (IJM), Paris, France.

Actomyosin machinery endows cells with contractility at a single-cell level. However, within a monolayer, cells can be contractile or extensile based on the direction of pushing or pulling forces exerted by their neighbours or on the substrate. It has been shown that a monolayer of fibroblasts behaves as a contractile system while epithelial or neural progentior monolayers behave as an extensile system. Read More

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February 2021

Diversified Talent Cultivation Mechanism of Early Childhood Physical Education Under the Full-Practice Concept - Oriented by Preschooler Mental Health and Intelligent Teaching.

Front Psychol 2020 15;11:593063. Epub 2021 Jan 15.

Department of Educational Management, Planning and Policy, Faculty of Education, University of Malaya, Kuala Lumpur, Malaysia.

In order to improve early childhood physical education, in this study, the talent cultivation mechanism for undergraduates was explored under the "full-practice" concept, oriented by preschooler mental health. First, from the perspective of preschooler psychology, the mechanisms of ability training and talent cultivation for undergraduates majoring in early childhood education were explored under the "full-practice" concept. Considering that the physical, psychological, and intellectual development of preschoolers shall follow the rules of physical education, and current early childhood education mainly focuses on intelligence education in China, early childhood physical education was analyzed further in this study. Read More

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January 2021

Cooperative epithelial phagocytosis enables error correction in the early embryo.

Nature 2021 02 10;590(7847):618-623. Epub 2021 Feb 10.

Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.

Errors in early embryogenesis are a cause of sporadic cell death and developmental failure. Phagocytic activity has a central role in scavenging apoptotic cells in differentiated tissues. However, how apoptotic cells are cleared in the blastula embryo in the absence of specialized immune cells remains unknown. Read More

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February 2021

The nuclear piston activates mechanosensitive ion channels to generate cell migration paths in confining microenvironments.

Sci Adv 2021 Jan 8;7(2). Epub 2021 Jan 8.

Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.

Cell migration in confining microenvironments is limited by the ability of the stiff nucleus to deform through pores when migration paths are preexisting and elastic, but how cells generate these paths remains unclear. Here, we reveal a mechanism by which the nucleus mechanically generates migration paths for mesenchymal stem cells (MSCs) in confining microenvironments. MSCs migrate robustly in nanoporous, confining hydrogels that are viscoelastic and plastic but not in hydrogels that are more elastic. Read More

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January 2021

Mechanisms of gradual pressure drop in angiographically normal left anterior descending and right coronary artery: Insights from wave intensity analysis.

J Cardiol 2021 Jul 26;78(1):72-78. Epub 2021 Jan 26.

Division of Cardiovascular Medicine and Coronary Heart Disease, Hyogo College of Medicine, Nishinomiya, Japan.

Background: This study evaluated the mechanism of decline in coronary pressure from the proximal to the distal part of the coronary arteries in the left anterior descending (LAD) versus the right coronary artery (RCA) from the insight of coronary hemodynamics using wave intensity analysis (WIA).

Methods: Twelve patients with angiographically normal LAD and RCA were prospectively enrolled. Distal coronary pressure, mean aortic pressure, and average peak velocity were measured at 4 different positions: 9, 6, 3, and 0 cm distal from each coronary ostium. Read More

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Characterization of a 3-hydroxyanthranilic acid 6-hydroxylase involved in paulomycin biosynthesis.

Biochem Biophys Res Commun 2021 Mar 23;543:8-14. Epub 2021 Jan 23.

State Key Laboratory of Microbial Resources & CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address:

Paulomycins (PAUs) refer to a group of glycosylated antibiotics with attractive antibacterial activities against Gram-positive bacteria. They contain a special ring A moiety that is prone to dehydrate between C-4 and C-5 to a quinone-type form at acidic condition, which will reduce the antibacterial activities of PAUs significantly. Elucidation of the biosynthetic mechanism of the ring A moiety may facilitate its structure modifications by combinatorial biosynthesis to generate PAU analogues with enhanced bioactivity or stability. Read More

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Directional mast cell degranulation of tumor necrosis factor into blood vessels primes neutrophil extravasation.

Immunity 2021 Mar 22;54(3):468-483.e5. Epub 2021 Jan 22.

Institute for Molecular and Clinical Immunology, Medical Faculty, Otto-von-Guericke University Magdeburg, Germany; Health Campus Immunology, Infectiology and Inflammation, Otto-von-Guericke-University, Magdeburg, Germany. Electronic address:

Tissue resident mast cells (MCs) rapidly initiate neutrophil infiltration upon inflammatory insult, yet the molecular mechanism is still unknown. Here, we demonstrated that MC-derived tumor necrosis factor (TNF) was crucial for neutrophil extravasation to sites of contact hypersensitivity-induced skin inflammation by promoting intraluminal crawling. MC-derived TNF directly primed circulating neutrophils via TNF receptor-1 (TNFR1) while being dispensable for endothelial cell activation. Read More

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Butterflies fly using efficient propulsive clap mechanism owing to flexible wings.

J R Soc Interface 2021 01 20;18(174):20200854. Epub 2021 Jan 20.

Department of Biology, Lund University, Ecology Building, Sölvegatan 35, 223 62 Lund, Sweden.

Butterflies look like no other flying animal, with unusually short, broad and large wings relative to their body size. Previous studies have suggested butterflies use several unsteady aerodynamic mechanisms to boost force production with upstroke wing clap being a prominent feature. When the wings clap together at the end of upstroke the air between the wings is pressed out, creating a jet, pushing the animal in the opposite direction. Read More

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January 2021

Comparison of the chemical constituents of raw Fructus Aurantii and Fructus Aurantii stir-baked with bran, and the biological effects of auraptene.

J Ethnopharmacol 2021 Apr 24;269:113721. Epub 2020 Dec 24.

Key Laboratory of Modern Preparation of TCM, Ministry of Education, Jiangxi University of Traditional Chinese Medicine, Nanchang, China. Electronic address:

Ethnopharmacological Relevance: Fructus Aurantii (FA) is a Chinese herbal medicine commonly used in clinical practice to improve gastrointestinal motility, treat dyspepsia, and relieve constipation. More than 20 processing methods of FA have been recorded, among which FA stir-baked with bran is the earliest, most time consuming, and the most popular one. Raw FA has a strong ability to promote qi-moving and has middle-energizer-soothing effects; therefore, it is often used to relieve hypochondrium distension and pain, and to relax the stagnation of the liver Qi. Read More

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Anchoring Carbon Nanodots onto Nanosilica for Phosphorescence Enhancement and Delayed Fluorescence Nascence in Solid and Liquid States.

Small 2020 12 13;16(49):e2005228. Epub 2020 Nov 13.

Key Laboratory for Biobased Materials and Energy of Ministry of Education, Guangdong Provincial Engineering Technology Research Center for Optical Agriculture, College of Materials and Energy, South China Agricultural University, Guangzhou, 510642, P. R. China.

Carbon nanodots (CDs) anchored onto inorganic supporter (amorphous nanosilica, SiO ) like a core-satellite structure have enhanced the room-temperature phosphorescence (RTP) intensity along with ultralong lifetime of 1.76 s. Special and quite stable structure should account for these superiorities, including hydrogen network, covalent bond, and trap-stabilized triplet-state excitons that are responsible for the generation of phosphorescence. Read More

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December 2020

The Transition Metal Catalyzed [π2s + π2s + σ2s + σ2s] Pericyclic Reaction: Woodward-Hoffmann Rules, Aromaticity, and Electron Flow.

J Am Chem Soc 2020 11 27;142(45):19033-19039. Epub 2020 Oct 27.

The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.

We have shown that the fundamental step responsible for enantioinduction in the inner-sphere asymmetric Tsuji allylic alkylation is C-C bond formation through a seven-membered pericyclic transition state. We employ an extensive series of quantum mechanics (QM) calculations to delineate how the electronic structure of the Pd-catalyzed C-C bond forming process controls the reaction. Phase inversion introduced by d orbitals renders the Pd-catalyzed [π2s + π2s + σ2s + σ2s] reaction symmetry-allowed in the ground state, proceeding through a transition state with Craig-Möbius-like σ-aromaticity. Read More

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November 2020

Evidence for anaphase pulling forces during C. elegans meiosis.

J Cell Biol 2020 12;219(12)

Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA.

Anaphase chromosome movement is thought to be mediated by pulling forces generated by end-on attachment of microtubules to the outer face of kinetochores. However, it has been suggested that during C. elegans female meiosis, anaphase is mediated by a kinetochore-independent pushing mechanism with microtubules only attached to the inner face of segregating chromosomes. Read More

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December 2020

A Pushing Mechanism for Microtubule Aster Positioning in a Large Cell Type.

Cell Rep 2020 10;33(1):108213

Department of Biology, Boston College, Chestnut Hill, MA 02467, USA; Marine Biological Laboratory, Woods Hole, MA 02543, USA. Electronic address:

After fertilization, microtubule (MT) sperm asters undergo long-range migration to accurately position pronuclei. Due to the large sizes of zygotes, the forces driving aster migration are considered to be from pulling on the astral MTs by dynein, with no significant contribution from pushing forces. Here, we re-investigate the forces responsible for sperm aster centration in sea urchin zygotes. Read More

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October 2020

Microtubule-dependent pushing forces contribute to long-distance aster movement and centration in egg extracts.

Mol Biol Cell 2020 12 7;31(25):2791-2802. Epub 2020 Oct 7.

Department of Molecular Biology, University of Wyoming, Laramie, WY 82071.

During interphase of the eukaryotic cell cycle, the microtubule (MT) cytoskeleton serves as both a supportive scaffold for organelles and an arborized system of tracks for intracellular transport. At the onset of mitosis, the position of the astral MT network, specifically its center, determines the eventual location of the spindle apparatus and ultimately the cytokinetic furrow. Positioning of the MT aster often results in its movement to the center of a cell, even in large blastomeres hundreds of microns in diameter. Read More

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December 2020

How climate change skeptics (try to) spread their ideas: Using computational methods to assess the resonance among skeptics' and legacy media.

PLoS One 2020 5;15(10):e0240089. Epub 2020 Oct 5.

Centre for Media and Communication, University of Passau, Passau, Germany.

We study the discursive resonance of online climate skepticism in traditional media in Germany, a country where climate skeptics lack public prestige and thus form a political counter-movement. We thereby differentiate two temporal dynamics: resonance can be continuous or selective, based on the exploitation of specific events. Beyond, we test whether such resonance is higher within the conservative media. Read More

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November 2020

Discovery of novel liver X receptor inverse agonists as lipogenesis inhibitors.

Eur J Med Chem 2020 Nov 6;206:112793. Epub 2020 Sep 6.

Research Center for Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, 510006, China; School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, 529020, China. Electronic address:

Based on the co-crystal structures of LXRβ and its agonists (spiro [pyrrolidine-3,3'-oxindole] derivatives) discovered by us previously, we designed and synthesized a compound library to explore the agonistic activities. The library was screened with luciferase reporter assays, interestingly, it resulted in the discovery of 10 LXR inverse agonists besides 5 LXR agonists. To clarify the mechanism of the actions, we conducted molecular dynamics (MD) simulations on the LXR and inverse agonists complexes, and revealed that H3, H11 and H12 configurations are the key to turn on agonism or inverse agonism status for LXR. Read More

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November 2020

Coupling without Coupling Reactions: En Route to Developing Phenols as Sustainable Coupling Partners via Dearomatization-Rearomatization Processes.

Acc Chem Res 2020 10 17;53(10):2395-2413. Epub 2020 Sep 17.

Department of Chemistry and FQRNT Centre for Green Chemistry and Catalysis, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada.

Transition-metal-catalyzed cross-coupling reactions represent one of the most straightforward and efficient protocols to assemble two different molecular motifs for the construction of carbon-carbon or carbon-heteroatom bonds. Because of their importance and wide applications in pharmaceuticals, agrochemicals, materials, etc., cross-coupling reactions have been well recognized in the 2010 Nobel Prize in chemistry. Read More

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October 2020

Role of the GH-IGF1 system in progression of cancer.

Mol Cell Endocrinol 2020 12 10;518:111003. Epub 2020 Sep 10.

Endocrinology and Diabetes Research Unit, Schneider Children's Medical Center, Petah Tikva, Israel.

Emerging evidence links the growth hormone (GH)-insulin-like growth factor-1 (IGF1) endocrine axis to cancer development. While this putative correlation is of major translational relevance, most clinical and epidemiological reports to date found no causal linkage between GH therapy and enhanced cancer risk. Thus, it is generally agreed that GH therapy constitutes a safe pharmacological intervention. Read More

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December 2020

Cation-Disorder-Assisted Reversible Topotactic Phase Transition between Antifluorite and Rocksalt Toward High-Capacity Lithium-Ion Batteries.

ACS Appl Mater Interfaces 2020 Sep 21;12(39):43605-43613. Epub 2020 Sep 21.

Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.

Multielectron reaction electrode materials using partial oxygen redox can be potentially used as cathodes in lithium-ion batteries, as they offer numerous advantages, including high reversible capacity and energy density and low cost. Here, a reversible three-electron reaction is demonstrated utilizing topotactic phase transition between antifluorite and rocksalt in a cation-disordered antifluorite-type cubic LiCoO cathode. This cubic phase is synthesized by a simple mechanochemical treatment of conventionally prepared tetragonal LiCoO. Read More

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September 2020