17O MQMAS NMR was used to characterize the influence of zirconium on the structural organization of soda-lime borosilicate glasses. A new method of quantitative analysis of the 17O MQMAS spectra is presented, by a direct fit of the two-dimensional MQMAS spectrum which provides the resolution of all the structural groups in glasses containing up to five oxides. Additional data were also obtained from the quantitative deconvolution of the 11B MAS NMR spectra, with the help of the direct fit of MQMAS data as well. Excess of non-bridging oxygen is clearly identified in these glasses. Sixfolded zirconium is preferentially compensated rather than the tetrahedral boron and calcium only partially compensate the tetrahedral boron. Alteration gels arising from glass leaching were probed by oxygen-17 supplied by the alteration solution. Most of the zirconium is inserted in the silicate network forming Si–O–Zr bonds with the same configuration in the glass and in the gel. During leaching, calcium clearly remains in the alteration gel, either near non-bridging oxygen or as a zirconium charge compensator. This quantitative approach applied to 17O MQMAS spectra demonstrates its potential for investigating the structure of increasingly complex glass and gel compositions.

The 43Ca MAS NMR spectra obtained for three calcium silicate glasses containing aluminum and/or sodium are analyzed. The 43Ca NMR parameters are shown to be highly sensitive to variations in its chemical environment. The transition from a charge-compensating role of [AlO4]− groups to a network-modifying role near nonbridging oxygen atoms results in an increase of both the isotropic chemical shift and the quadrupolar coupling constant of 43Ca. This effect can be related to the first coordination shell of calcium (through the Ca–O bond distance) which is affected by the chemical environment beyond the first neighbors of calcium.

A multinuclear solid-state NMR investigation of the structure of the amorphous alteration products (so called gels) that form during the aqueous alteration of silicate glasses is reported. The studied glass compositions are of increasing complexity, with addition of aluminum, calcium, and zirconium to a sodium borosilicate glass. Two series of gels were obtained, in acidic and in basic solutions, and were analyzed using 1H, 29Si, and 27Al MAS NMR spectroscopy. Advanced NMR techniques have been employed such as 1H–29Si and 1H–27Al cross-polarization (CP) MAS NMR, 1H double quantum (DQ) MAS NMR and 27Al multiple quantum (MQ) MAS NMR. Under acidic conditions, 29Si CP MAS NMR data show that the repolymerized silicate networks have similar configuration. Zirconium as a second nearest neighbor increases the 29Si isotropic chemical shift. The gel porosity is influenced by the pristine glass composition, modifying the silicon–proton interactions. From 1H DQ and 1H–29Si CP MAS NMR experiments, it was possible to discriminate between silanol groups (isolated or not) and physisorbed molecular water near Si(Q2), Si(Q3), and Si(Q4) sites, as well as to gain insight into the hydrogen-bonding interaction and the mobility of the proton species. These experiments were also carried out on heated samples (180°C) to evidence hydrogen bonds between hydroxyl groups on molecular water. Alteration in basic media resulted in a gel structure that is more dependent on the initial glass composition. 27Al MQMAS NMR data revealed an exchange of charge compensating cations of the [AlO4]− groups during glass alteration. 1H–27Al CP MAS NMR data provide information about the proximities of these two nuclei and two aluminum environments have been distinguished. The availability of these new structural data should provide a better understanding of the impact of glass composition on the gel structure depending on the nature of the alteration solution.

The positions of nu8a and nu*(NH) bands in the spectrum of protonated 2,6-dimethylpyridine vary with the strength of Brønsted acidity: the higher the nu*(NH) wavenumber and the lower the nu8a wavenumber, the stronger the acidity. The results obtained with 2,6-dimethylpyridine adsorption correlate with those obtained by CO adsorption experiments on a series of faujasite zeolites (LiHNaY, KHNaY, HY, HY(SA), HNaX). These relations were extended to gamma-Al2O3 having weak Brønsted acidity, not detected by pyridine and hardly detected by CO. The number (0.1 per nm2) and the strength (corresponding to delta nu (OH) by CO = 155 cm(-1)) of the most acidic OH groups of Al2O3, as well as the position of the corresponding nu (OH) band (<3700 cm(-1)) are deduced from 2,6-dimethylpyridine adsorption experiments.

Les femmes 'ayyar sont des personnages d'exception dans tous les sens du terme : moins nombreuses que leurs homologues masculins, elles sont, pour certaines, remarquables tant par l'ampleur de leur role que par l'excellence dont elles temoignent dans l'exercice de 'ayyâri. Apres un apercu du role narratif des grandes heroines mises en scene par deux celebres recits en prose (Samak-e 'Ayyar, Faramarz b. Xodadad al-Arrajani, ca. VI e /XII e s. ; Abu Moslem Name, Abu Taher Tartusi, V e /XI e -VI e /XII e s.), on observera les rares passages ou celles-ci s'expriment sur leur situation ainsi que la facon dont les hommes les considerent, dans leur camp ou chez l'ennemi. Qu'elles veuillent echapper au mariage ou qu'elles aient epouse des 'ayyar de profession, elles font preuve d'une grande independance, mais mise a part leur activite, elles ne troublent pas l'ordre social. Est-ce un hasard si ces femmes a la forte personnalite, aspirant a un mode de vie peu conformiste, se sont tournees vers le milieu 'ayyar ou elles semblent bien admises ?

The modification of surface properties resulting from H2S adsorption on a fully sodium-exchanged Y zeolite was studied in situ using a combination of infrared and Solid-State NMR spectroscopy. In order to perform in situ measurement in the same conditions with both techniques, a homebuilt device for preparing the NMR samples under vacuum or controlled atmosphere was used. Double-resonance NMR methods were achieved for a complete assignment of the different lines in proton NMR spectra. A small fraction of H2S is shown to adsorb dissociatively on NaY whereas the main part of H2S interacts non-dissociatively, either by coordination with the Na+ cations or by H-bonding.

The modification of acidic properties resulting from H2S adsorption on the NaY zeolite were studied by IR spectroscopy using pyridine and 2,6-dimethylpyridine as probe molecules. A very small fraction of H2S adsorbs dissociatively on NaY whereas the main part of H2S interacts nondissociatively, either by coordination with Na+ cations or by H-bonding. Evacuation at room temperature (RT) eliminates all the molecular H2S species. Both probe molecules detected Brønsted acidity in the presence of H2S but this acidity is almost completely eliminated by pumping at RT. No link between the variation in the number of protonated species and the variation in the intensity of the OH bands appears. On the contrary, there is a relationship between the presence of molecular H2S and the detection of protonated species. These results show that coordination of H2S on cationic sites leads to a modification of the electronic repartition in the hydrogen disulfide molecule, giving rise to the appearance of a positive charge on the hydrogen atom of the molecular H2S, which, thus, presents a proton-donating ability.

Le Ddrdb Name de Tarsusi, recit semi-populaire en prose du 6712 siecle environ, n'est aucunement un roman "de 'ayydrs", c'est-a-dire un roman dans lequel interviennent de facon significative des jeunes gens issus de milieux populaires urbains et developpant, au sein de confraternites, des qualites de conduite relevant du code ethique de javdnmardi. Pour cette definition du 'ayydr "professionnel", dont l'activite consiste a mettre ses capacites specifiques au service d'une cause ou d'une autre, on se refere evidemment au tableau que peut nous offrir un texte comme le Samak-e 'Ayydr, le roman de Faramarz b. Xodadad b. 'Abd Allah al-Kateb al-Arrajani, mis par ecrit au debut du 6/12 siecle environ et qui, en tant que recit a portee didactique, est intentionnellement tres explicite sur ce en quoi consistent 'ayydri et javdnmardi et leur exercice. Cependant, a la lecture du Ddrdb Name, l'attention ne peut manquer d'etre attiree par la frequence d'apparition des termes 'ayydrfl) et javdnmard(i) (adjectifs ou substantifs). Le premier y est utilise quarante et une fois, le second cent soixante deux fois. Le recit peut mentionner des 'ayydrs proprement dits, tels ceux de la ville d'Alep, appeles 'ayydrdn-e sahr, mais ils ne sont pas montres dans l'action quotidienne (I, p. 488). Ailleurs, le terme est plus souvent employe pour qualifier une maniere d'agir que pour designer une personne definie au travers d'un ensemble de competences particulieres, et il ne se rapporte de toute facon pas a des 'ayydrs de profession. Aussi tous ces termes interviennent-ils comme des mots courants dans le recit, utilises de fa?on usuelle, et c'est par le seul contexte — encore que celui-ci soit parfois absent —, que Ton peut se faire une idee de la situation qui a motive leur choix. En confrontant done les termes et leur champ d'emploi a ce qu'on sait du Samak-e 'Ayydr, on va tenter de voir ce qu'il y a de persistant ou de variable, d'un recit a l'autre, en ce qui concerne les situations, et surtout en ce qui concerne les acteurs de ces situations, puisque dans le Ddrdb Name aucun d'eux n'est un veritable 'ayydr.