Lewis Carroll's ciphers: The literary connections

Charles L. Dodgson, who lectured on mathematics at Christ Church in Oxford University, constructed ciphers that were state of the art in his time. In poems and letters he demonstrated a great talent for creating acrostics and anagrams. In this paper I describe the ciphers closely and argue that their creation was intertwined with his word game inventions.     

Stability of [Ru(II)(tpy)(bpy)(OH(2))](2+)-modified graphite electrodes during indirect electrolyses

The stability of a graphite felt electrode modified by covalent attachment of [Ru(II)(tpy)(bpy)(OH(2))](2+) is investigated during the indirect electrolyses of alcohols in a flow cell. The continuous increase of the local potential of the electrode during the electrolyses attests to its degradation. Cyclic voltammetry analyses of the modified electrode after electrolyses show a total decrease of 80-90% of the wave corresponding to the Ru(III/II) couple. The concentration of remaining alcohol measured at the outlet of the cell is almost constant during all the electrolyses but increase when the potential exceeds 0.95 V(SCE). At low potentials, the electrode can be regenerated by reaction with Ru(II)Cl(2)(DMSO)(tpy) and then CF(3)SO(3)H, followed by hydrolysis, showing that the bipyridine ligand remains covalently attached to the electrode. At high potentials, the graphite is oxidized and the catalyst is partly lost in the reaction medium. XPS analyses of Ru core levels reveal that the ruthenium disappeared after electrolysis, showing that the degradation of the modified electrode is due to the demetalation of the oxidized complex.     

Multiple scattering in a trabecular bone: influence of the marrow viscosity on the effective properties

The Foldy and the Waterman and Truell approximations are used to determine the effective properties of the coherent wave that emerges after multiple scattering of a plane longitudinal fast wave by the largest pores in a trabecular bone. The unit scattering cell considered is either a single pore or two close cylindrical pores (cluster), at a fixed overall bone porosity. In the cluster case, the effective attenuation is about twice that obtained with one single pore per scatterer. It is shown that taking into account the marrow viscosity leads only to minor differences on the effective dispersion and attenuation.     

Etude structurale de la forme ordonnée de LiAl5O8

A single crystal of ordered LiAl₅O₈ has been prepared by image furnace melting and its structure has been determined; 400 X-ray reflections were collected on an automatic counter diffractometer (MoKα radiation). The structure is of the spinel type. The space group is P4₃32 (or P4₁32); the lattice parameter is a = 7.908(2), Å, Z = 4. The value of R is 0.022. The distribution of cations shows the absence of Li⁺ ions in tetrahedral cation sites and 1–3 imperfect ordering of Li⁺ and Al₃₊ in octahedral cation sites of spinel.     

SYNTHESE DE SELS DE VINYLPHOSPHONIUMS β-SUBSTITUES ET DE SELS D'ALKYLPHOSPHONIUMS β-DISUBSTITUES

Abstract

Vinylene-1,2 bisphosphoniums salts react, in the presence of a base, with compounds ZH having a mobile hydrogen, to give a way of synthesis of β-substituted vinylphosphoniums salts 2 or β-disubstituted alkylphosphoniums salts 3. We have studied the limits of these synthesis depending on the experimental conditions and the nature of compounds ZH (alcohols, phenols, thiols, phosphines, amines).

Les sels de vinylène-1,2 bisphosphoniums réagissent, en présence d'une base, avec les composés à hydrogène mobile ZH pour fournir ainsi une méthode d'obtention de sels de vinylphosphoniums β-substitués 2 ou de sels d'alkylphosphoniums β-disubstitués 3. Nous avons étudié les limites de ces synthèses en faisant varier les conditions opératoires et la nature des composés ZH (alcools, phénols, thiols, phosphines, amines).