Complexation of F⁻ by Li⁺ and Mg²⁺ Ions as Inorganic Anion Acceptors in Lactone-Based Li⁺/F⁻ and Mg²⁺/F⁻ Hybrid Electrolytes for Fluoride Shuttle Batteries

The development of high-quality fluoride-ion transporting electrolytes is a crucial demand for fluoride shuttle batteries (FSBs). However, the uncontrolled chemical and electrochemical activities of fluoride ions narrow the available potential window, hindering the development of high-voltage FSB cells. We present a method for upgrading recently developed lactone-based liquid fluoride electrolytes by complexation of F⁻ with Li⁺ and Mg²⁺ ions. In the resultant Li⁺/F⁻ and Mg²⁺/F⁻ hybrid electrolytes, Li2F+ and MgF+ were the most probable soluble complexes, and the effective fluoride concentrations could reach ∼0.15 M along with excess Li⁺(Mg²⁺) ions. Unique interactions between F⁻ and Li⁺(Mg²⁺) were observed using ¹⁹F nuclear magnetic resonance spectroscopy. Li⁺(Mg²⁺) ions thus served as inorganic anion acceptors with ultimate redox stabilities to expand the negative potential window of the electrolytes to near −3 V vs SHE. The proposed complex formation was also supported by a conductometric titration method. We demonstrated the superior and versatile electrochemical performances of the Li⁺/F⁻ hybrid electrolyte, which enabled reversible charge/discharge reactions of various metal electrodes and composite electrodes in a wide range of redox series. Further, the Li⁺/F⁻ hybrid electrolyte opened valid new reaction paths for aluminum, making it a promising negative electrode in high-voltage FSB cells

Orchestrated ensemble activities constitute a hippocampal memory engram

The brain stores and recalls memories through a set of neurons, termed engram cells. However, it is unclear how these cells are organized to constitute a corresponding memory trace. We established a unique imaging system that combines Ca2+ imaging and engram identification to extract the characteristics of engram activity by visualizing and discriminating between engram and non-engram cells. Here, we show that engram cells detected in the hippocampus display higher repetitive activity than non-engram cells during novel context learning. The total activity pattern of the engram cells during learning is stable across post-learning memory processing. Within a single engram population, we detected several sub-ensembles composed of neurons collectively activated during learning. Some sub-ensembles preferentially reappear during post-learning sleep, and these replayed sub-ensembles are more likely to be reactivated during retrieval. These results indicate that sub-ensembles represent distinct pieces of information, which are then orchestrated to constitute an entire memory

Receptor for Activated Protein Kinase C: Requirement for Efficient MicroRNA Function and Reduced Expression in Hepatocellular Carcinoma

MicroRNAs (miRNAs) are important regulators of gene expression that control physiological and pathological processes. A global reduction in miRNA abundance and function is a general trait of human cancers, playing a causal role in the transformed phenotype. Here, we sought to newly identify genes involved in the regulation of miRNA function by performing a genetic screen using reporter constructs that measure miRNA function and retrovirus-based random gene disruption. Of the six genes identified, RACK1, which encodes “receptor for activated protein kinase C” (RACK1), was confirmed to be necessary for full miRNA function. RACK1 binds to KH-type splicing regulatory protein (KSRP), a member of the Dicer complex, and is required for the recruitment of mature miRNAs to the RNA-induced silencing complex (RISC). In addition, RACK1 expression was frequently found to be reduced in hepatocellular carcinoma. These findings suggest the involvement of RACK1 in miRNA function and indicate that reduced miRNA function, due to decreased expression of RACK1, may have pathologically relevant roles in liver cancers

Collins and Sivers asymmetries in muonproduction of pions and kaons off transversely polarised protons

Measurements of the Collins and Sivers asymmetries for charged pions and charged and neutral kaons produced in semi-inclusive deep-inelastic scattering of high energy muons off transversely polarised protons are presented. The results were obtained using all the available COMPASS proton data, which were taken in the years 2007 and 2010. The Collins asymmetries exhibit in the valence region a non-zero signal for pions and there are hints of non-zero signal also for kaons. The Sivers asymmetries are found to be positive for positive pions and kaons and compatible with zero otherwise. © 2015

Lactone-Based Liquid Electrolytes for Fluoride Shuttle Batteries

Rechargeable secondary batteries operating through fluoride-ion shuttling between the positive and negative electrodes, referred to as fluoride shuttle batteries (FSBs), offer a potentially promising solution to overcoming the energy-density limitations of current lithium-ion battery systems. However, there are many technical issues that need to be resolved to achieve high-quality fluoride-carrying electrolytes and ensure reversible transformations between a metal and its fluoride counterpart at both electrodes. Here, we introduce novel lactone-based liquid electrolytes consisting either of CsF or KF, which are prepared by a solvent substitution method. Although the maximum fluoride-ion concentration achieved by the method is approximately 0.05 M, these systems behave as strong electrolytes where CsF(KF) is almost fully dissociated into Cs⁺(K⁺) and F⁻ ions to give a maximum ionic conductivity of 0.8 mS.cm⁻¹. Hence, the solvent supports electrochemically active fluoride ions that can drive reversible metal/metal-fluoride transformations at room temperature for a wide range of metal electrodes. However, irreversible reductive reactions of the solvent, also promoted by the fluoride ions, limit currently the negative potential window to approximately −1.5 V vs the standard hydrogen electrode

Impact of electron-beam irradiation on the performance of β-Ga2O3 Schottky barrier diodes

Gallium oxide (Ga2O3) is expected to have high radiation tolerance owing to their strong bond strengths and thus promising for the fabrication of robust electronic devices to be deployed in space missions and nuclear power plants. In this work, we investigated the performance of β-Ga2O3 vertical Schottky barrier diodes (SBDs) before and after electron-beam irradiation up to a cumulative fluence of 1×1016 cm-2. Electron-beam irradiation with an energy of 1.5 MeV and a fixed fluence rate of 4.62×1012 cm-2∙s-1 was carried out in air at room temperature with cumulative fluences of 0 (i.e., before irradiation), 1×1014, 5×1015, and 1×1016 cm-2. The specific on-resistances (Ron) and turn-on voltages (Von) were extracted from linear fits to the forward current density–voltage (J–V) characteristics and extrapolation of the linear fits to J=0 A/cm2, respectively. The Ron increased from 4.1 to 7.0 mΩ∙cm2 as the cumulative fluence increased from 0 to 1×1016 cm-2. The Von were estimated to be 1.8, 1.8, 1.7 and 1.7 V for cumulative fluences of 0, 1×1014, 5×1015, and 1×1016 cm-2, respectively. From linear fits to semi-logarithmic J–V plots, the ideality factors (η) for cumulative fluences of 0, 1×1014, 5×1015, and 1×1016 cm-2 were extracted to be 1.11, 1.10, 1.12 and 1.09, respectively. Insignificant changes in both Von and η implied a negligible effect of irradiation on the Pt/Ga2O3 interface. However, the 73% increase in Ron from 4.1 to 7.0 mΩ∙cm2, which was attributable to a comparable reduction in Nd-Na from 2.3×1016 to 1.2×1016 cm-3 as revealed by C–V measurement, suggested the presence of a high density of electron traps in irradiated Ga2O3.The 3rd International Workshop on Gallium Oxide and Related Materials (IWGO-3