Structural and Electrochemical Properties of Li2O-V2O5-B2O3-Bi2O3 Glass and Glass-Ceramic Cathodes for Lithium-Ion Batteries

In this study, 20Li₂O-60V₂O₅-(20 − x)B₂O₃-xBi₂O₃ (x = 5, 7.5, 10 mol%) glass materials have been prepared by the melt-quenching method, and the structure and morphology of the glass materials have been characterized by XRD, FTIR, Raman, and FE-SEM. The results show that the disordered network of the glass is mainly composed of structural motifs, such as VO₄, BO₃, BiO_3, and BiO₆. The electrochemical properties of the glass cathode material have been investigated by the galvanostatic charge-discharge method and cyclic voltammetry, and the results show that with the increases of Bi₂O₃ molar content, the amount of the VO₄ group increases, and the network structure of the glass becomes more stable. To further enhance the electrochemical properties, glass-ceramic materials have been obtained by heat treatment, and the effect of the heat treatment temperature on the structure and electrochemical properties of the glass has been studied. The results show that the initial discharge capacity of the glass-ceramic cathode obtained by heat treatment at 280 °C at a current density of 50 mA·g⁻¹ is 333.4 mAh·g⁻¹. In addition, after several cycles of charging and discharging at a high current density of 1000 mA·g⁻¹ and then 10 cycles at 50 mA·g⁻¹, its discharge capacity remains at approximately 300 mAh·g⁻¹ with a capacity retention rate of approximately 90.0%. The results indicate that a proper heat treatment temperature is crucial to improving the electrochemical properties of glass materials. This study provides an approach for the development of new glass cathode materials for lithium-ion batteries.     

Non-adiabatic interactions in charge transfer collisions

An analysis of the charge transfer mechanism in the collision of multiply charged ions with molecular and biomolecular targets is performed, considering the non-adiabatic interactions between the molecular states involved. Collisions of doubly charged C ²⁺ ions on small molecular targets, CO and OH, have been investigated, together with the analysis of charge transfer between C ⁴⁺ ions on uracil and halouracil biomolecular targets. The process is studied theoretically by means of ab-initio molecular calculations followed by a semi-classical treatment of the collision dynamics. The influence of rotational couplings is discussed with regard to the collision energy. Strong anisotropic and vibration effects are pointed out.     

Extended Fermi coordinates

We extend the notion of Fermi coordinates to a generalized definition in which the highest orders are described by arbitrary functions. From this definition rises a formalism that naturally gives coordinate transformation formulae. Some examples are developed in order to discuss the physical meaning of Fermi coordinates.     

On the use of graphs in discrete tomography

In this tutorial paper, we consider the basic image reconstruction problem which stems from discrete tomography. We derive a graph theoretical model and we explore some variations and extensions of this model. This allows us to establish connections with scheduling and timetabling applications. The complexity status of these problems is studied and we exhibit some polynomially solvable cases. We show how various classical techniques of operations research like matching, 2-SAT, network flows are applied to derive some of these results.     

Quantitative determination of hexavalent chromium in aqueous solutions by UV-Vis spectrophotometer

In the last decade, different methods have been developed for the determination of chromium(VI) concentration in water. These methods use high cost equipment or they require a long preparation time. Because of their drawbacks, this paper describes an on-line, rapid and sensitive procedure for the determination of Cr(VI) concentrations in aqueous solutions via pH and absorption measurements. Only four Cr(VI) species are considered. The effects of pH and of total amount of chromium on the Cr(VI) speciation are investigated. The molar absorptivities of four chromium species at 371 nm are determined by minimising an objective function. The knowledge of these molar absorptivities and the measurements of pH and absorption at 371 nm lead to a rapid determination of total Cr(VI) concentration. The reliability and applicability of the method were confirmed using synthetic water samples.      

Multivalent RGD synthetic peptides as potent alphaVbeta3 integrin ligands

We study herein the multivalency effect of a cluster of alphaVbeta3-ligands held on a cyclodecapeptide template. An array of RAFT(c[-RGDfK-])n derivatives containing from one to sixteen clustered RGD motifs were synthesized and comparatively assayed in vitro on alphaVbeta3-expressing cells. Efficient inhibition of the alphaVbeta3-specific 23C6 monoclonal antibody fixation was observed with ligands displaying three and four copies of the cyclo[-RGDfK-] peptide.     

Some chemical transformations of carbohydrates in aqueous medium

The interest of combining the use of carbohydrates as synthons and the use of water as the reaction medium is emphasized by briefly reviewing some examples of contributions in this field achieved in our Lyon and Orsay laboratories.     

Influence of the modified Becke-Johnson exchange potential on thermoelectric properties: application to Mg2Si

The electronic and transport properties of Mg(2)Si are calculated using the density-functional and semi-classical Boltzmann transport theories. A detailed comparison of the efficiency of the Perdew, Burke, and Ernzerhof (PBE) and the modified Becke-Johnson (m-BJ) exchange potentials on the prediction of these properties is presented. We show that the m-BJ potential is able to predict the Mg(2)Si thermoelectric properties with better agreement with the experimental data than the PBE potential. These findings are correlated with a small modification of the valence orbitals of the materials and the opening of the gap.