The Long‐Term Stability of KO2 in K‐O2 Batteries

The rechargeable K‐O₂ battery is recognized as a promising energy storage solution owing to its large energy density, low overpotential, and high coulombic efficiency based on the single‐electron redox chemistry of potassium superoxide. However, the reactivity and long‐term stability of potassium superoxide remains ambiguous in K‐O₂ batteries. Parasitic reactions are explored and the use of ion chromatography to quantify trace amounts of side products is demonstrated. Both quantitative titrations and differential electrochemical mass spectrometry confirm the highly reversible single‐electron transfer process, with 98 % capacity attributed to the formation and decomposition of KO₂. In contrast to the Na‐O₂ counterparts, remarkable shelf‐life is demonstrated for K‐O₂ batteries owing to the thermodynamic and kinetic stability of KO₂, which prevents the spontaneous disproportionation to peroxide. This work sheds light on the reversible electrochemical process of K⁺+e^?+O₂?KO₂.     

Some applications of modern polarography in metallurgical analysis

Summary A brief review is set out on the application of modern polarographic techniques, as square-wave, pulse and differential cathode-ray polarography in the field of metallurgical and trace analysis. Some experimental details are given to achieve the increased precision of 0.1% of differential cathode-ray polarography. For a number of alloys the analytical data obtained by modern polarographic techniques are compared with those of other analytical methods, e.g. volumetric and gravimetric analysis, electrolysis, X-ray fluorescence.

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Zusammenfassung Es wird ein Überblick über Anwendung moderner polarographischer Verfahren wie Square-Wave-, Pulse- und Differentialkathodenstrahlpolarographie in der Legierungs- und Spurenanalyse gegeben. Einzelheiten über die bei der Anwendung der Kathodenstrahlpolarographie erzielbare Genauigkeit von 0,1% werden mitgeteilt. Für eine Reihe von Metallegierungen werden die polarographischen Analysenergebnisse mit den nach anderen Methoden (Volumetrie, Gravimetrie, Elektrolyse, Röntgenfluorescenz) erhaltenen Werten verglichen.

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Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday.     

A study of η-allyl(η-cyclopentadienyl)- dicarbonylmanganese salts

New substituted η³-allyl(η⁵-cyclopentadienyl)dicarbonylmanganese cations have been prepared as their tetrafluoroborates. They readily add a wide range of nucleophiles yielding η²-alkene(η⁵-cyclopentadienyl)dicarbonylmanganese complexes. Of the latter, in general only those involving terminal alkenes are sufficiently stable to permit ready isolation; otherwise metal-free alkenes are obtained. Regioselectivity in these additions depends on the nucleophile.     

A robust interface enabled by electrospun membrane with optimal resistance in lithium metal batteries

A uniform diffusion layer is essential for non-dendritic deposition of lithium in high-density lithium batteries.However,natural pristine solid electrolyte interface(SEI)is always porous and inhomogeneous because of repeated breakdown and repair cycles,whereas ideal materials with excellent mechanical property for artificial SEIs remain a challenge.Herein,a robust and stable interface is achieved by spinning soft polymer associated with few MoO₃ into fibers,and thus mechanical property of fibers other than materials determines mechanical performance of the interface which can be optimized by adjusting parameters.Furthermore,lithium deposited underneath the layer is enabled by constructing an optimal resistance to make the membrane serve as an artificial SEI rather than lithium host.As a result,dendritefree lithium was observed underneath the membrane,and stable interface for long-term cycling was also indicated by EIS measurements.The lithium iron phosphate(LiFePO₄)full-cell with coated electrode demonstrated an initial capacity of 155.2 m Ah g^-1,and 80%of its original capacity was retained after 500 cycles at 2.0℃ without any additive in carbonate-based electrolyte.     

Spectral Asymptotics for Higher-Order Ordinary Differential Equations

This paper gives one-term componentwise asymptotics for theM and spectral matrices of a self-adjoint realisation of aneven-order ordinary differential expression. The underlyinginterval is assumed to have at least one regular endpoint, andthe boundary conditions are supposed to be separated. Furthermore,the weight function and the reciprocal of the highest-ordercoefficient are supposed to be of regular variation at the regularendpoint, in the sense of Bingham, Goldie and Teugels. 1991Mathematics Subject Classification: 34B24, 34E05.     

TRPM5-expressing microvillous cells in the main olfactory epithelium

Background  

The main olfactory epithelium (MOE) in the nasal cavity detects a variety of air borne molecules that provide information regarding the presence of food, predators and other relevant social and environmental factors. Within the epithelium are ciliated sensory neurons, supporting cells, basal cells and microvillous cells, each of which is distinct in morphology and function. Arguably, the least understood, are the microvillous cells, a population of cells that are small in number and whose function is not known. We previously found that in a mouse strain in which the TRPM5 promoter drives expression of the green fluorescent protein (GFP), a population of ciliated olfactory sensory neurons (OSNs), as well as a population of cells displaying microvilli-like structures is labeled. Here we examined the morphology and immunocytochemical properties of these microvillous-like cells using immunocytochemical methods.     

Molecular complexes of sulfur dioxide with organic carbonates

Spectroscopic studies made on the bisphenol A polycarbonate–sulfur dioxide system showed evidence of interaction between polymer and penetrant. Equilibrium studies made on solutions of sulfur dioxide and organic carbonates chosen as monomer analogs showed that complexes of the donor–acceptor type were formed, and that at temperatures of 15°C and less the stoichiometry of these was greater than 1:1. The procedures described are compared with those used in other donor–acceptor studies, and the results observed from the equilibrium studies are interpreted by using data reported for other sulfur dioxide–donor systems.     

Femtosecond vibrational dynamics of self-trapping in a quasi-one-dimensional system

We have directly time resolved the lattice motions associated with the formation of the self-trapped exciton in the quasi-one-dimensional system [Pt(en)(2)] [Pt(en)2Br2];(PF6)(4) ( en = ethylene-diamine, C2H8N2), using femtosecond impulsive excitation techniques. A strongly damped, low-frequency wave packet modulation at approximately 110 cm(-1) accompanies the formation of the self-trapped exciton on a approximately 200 fs time scale following excitation of the intervalence charge-transfer transition. Coherent oscillations at the ground state vibrational frequency and its harmonics are also detected.     

Development and applications of a preparative scale sample controlled thermogravimetric system

Journal of Thermal Analysis and Calorimetry -