A model potential in two forms (harmonic and anharmonic) is proposed to be used in molecular dynamics simulations of silicate frameworks. This model is applied to the calculation of structural and vibrational properties of the anhydrous phase of Linde 2Mite 4 A. Our system is formed by a cubic box corresponding to one crystallographic cell containing 662 atoms without constraints. The results are compared with experimental data. The proposed models satisfactorily reproduce the main features of the aluminosilicate framework structure and dynamics.

This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association, Commission on New Minerals and Mineral Names. In a working definition of a zeolite mineral used for this review, structures containing an interrupted framework of tetrahedra are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is allowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundant in atomic proportions. To name these, the appropriate chemical symbol is attached by a hyphen to the series name as a suffix, except for the names harmotome, pollucite and wairakite in the phillipsite and analcime series. Differences in space-group symmetry and in order-disorder relationships in zeolites having the same topologically distinctive framework do not in general provide adequate grounds for recognition of separate species. Zeolite species are not to be distinguished solely on the ratio Si : Al except for heulandite (Si : Al < 4.0) and clinoptilolite (Si : Al ≥ 4.0). Dehydration, partial hydration, and overhydration are not sufficient grounds for the recognition of separate species of zeolites. Use of the term "ideal formula" should be avoided in referring to a simplified or averaged formula of a zeolite. Newly recognized species in compositional series are as follows: brewsterite-Sr, -Ba, chabazite-Ca, -Na, -K, clinoptilolite-K, -Na, -Ca, dachiardite-Ca, -Na, erionite-Na, -K, -Ca, faujasite-Na, -Ca, -Mg, ferrierite-Mg, -K, -Na, gmelinite-Na, -Ca, -K, heulandite-Ca, -Na, -K, -Sr, levyne-Ca, -Na, paulingite-K, -Ca, phillipsite-Na, -Ca, -K, and stilbite-Ca, -Na. Key references, type locality, origin of name, chemical data, IZA structure-type symbols, space-group symmetry, unit-cell dimensions, and comments on structure are listed for 13 compositional series, 82 accepted zeolite mineral species, and three of doubtful status. Herschelite, leonhardite, svetlozarite, and wellsite are discredited as mineral species names. Obsolete and discredited names are listed.Keywords: zeolite nomenclature, herschelite, leonhardite, svetlozarite, wellsite, brewsterite, chabazite, clinoptilolite, dachiardite, erionite, faujasite, ferrierite, gmelinite, heulandite, levyne, paulingite, phillipsite, stilbite. SOMMAIRECe rapport contient les recommandations à propos de la nomenclature des zéolites, telles qu'approuvées par l'Association minéralogique internationale, commission des nouveaux minéraux et des noms de minéraux. Dans la définition d'une zéolite retenue ici, les structures contenant une trame interrompue de tétraèdres sont acceptées dans les cas où les autres propriétés satisfont les critères de cette famille de minéraux. De plus, il peut y avoir remplacement complet de Si et Al par d'autres éléments. Des espèces distinctes font partie de séries de compositions dont l'agencement topologique est le même, le cation dominant ne faisant pas partie de la trame ...

30)K = exp Accepting that yc = ya i.e., Ay = 0 and n, = ns, we deduce that or Mazer et report an aggregation number of 10 for the formation of a primary micelle, Le., n, = 10. Accepting our Awo values and AGO = -RT In K, it is deduced that AGO varies in the range -1.3 to -6.7 kcal/mol. Although several simplifications are involved, such values are very close to those obtained by Mazer et al. (from -3.8 to -6.7 depending on experimental conditions) for the above-mentioned bile salts. Giglio et al." have demonstrated the advantages of the helical model compared with the Small model for deoxycholate derivatives. The previous aggreement could mean that such a model is also valid for other bile salts.The effect of the electrolyte anion on the value of Ay found in this paper has not been considered in KS model and further developments are required.Acknowledgment. We thank the Xunta de Galicia for financial support (project XUGA29906A90). cmc critical micelle concentration QLS quasi-elastic light scattering NaDC sodium deoxycholate NaC sodium cholate NaDHC sodium dehydrocholate NaTDC sodium taurodeoxycholate TC taurocholic acid TDC taurodeoxycholic acid TCDC taurochenodeoxycholic acid TUDC tauroursodeoxycholic acid Salsalicylate anion M mol d n i 3 mM mol m-' Nasal, 54-21-7.The effect of the temperature on the diffusion of methane in silicalite was studied by molecular dynamics both using a model where the vibrations of the zeolite framework are taken into account and keeping the framework Fled. Methane molecules were represented by Lennard-Jones particles. The diffusion coefficients were evaluated at four different temperatures in the range 150450 K and resulted in good agreement with experiment. The effect of the vibrating framework on the diffusive process is discussed and a detailed analysis of the behavior of methane molecules in silicalite is reported. IntroductionThe elucidation of the behavior of fluids within narrow pores

This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association Commission on New Minerals and Mineral Names. In a working definition of a zeolite mineral used for this review, interrupted tetrahedral framework structures are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is allowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundant in atomic proportions. To name these, the appropriate chemical symbol is attached by a hyphen to the series name as a suffix except for the names harmotome, pollucite and wairakite in the phillipsite and analcime series. Differences in space-group symmetry and in order-disorder relationships in zeolites having the same topologically distinctive framework do not in general provide adequate grounds for recognition of separate species. Zeolite species are not to be distinguished solely on Si : Al ratio except for the heulandite (Si : Al < 4.0) and clinoptilolite (Si : Al ≥ 4.0) series. Dehydration, partial hydration, and over-hydration are not sufficient grounds for the recognition of separate species of zeolites. Use of the term "ideal formula" should be avoided in referring to a simplified or averaged formula of a zeolite. Newly recognized species in compositional series are as follows:

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A tough challenge in nanomaterials chemistry is the determination of the structure of multicomponent nanosystems. Dye-zeolite L composites are building blocks of hierarchically organized multifunctional materials for technological applications. Supramolecular organization inside zeolite L nanochannels, which governs electronic properties, is barely understood. This is especially true for confined close-packed dye molecules, a regime not investigated in applications yet and that might have great potential for future development in this field. Here we realize for the first time composites of zeolite L with maximally-packed fluorenone molecules and elucidate their structure by integrated multi-technique analyses. By IR, thermogravimetric and X-ray diffraction we establish the maximum degree of dye loading obtained (1.5 molecules per unit cell) and by modeling we reveal that at these conditions fluorenone molecules form quasi 1-D supramolecular nanoladders running along the zeolite channels. Spatial and morphological control provided by the nanoporous matrix combined with a complex blend of strong dye-zeolite and weaker dye-dye van der Walls interactions lie at the origin of this unique architecture, which is also stabilized by the hydrogen bond network of co-adsorbed water molecules surrounding the dye nanoladder and penetrating between its rungs.

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Structural investigation of the high pressure intrusion/extrusion of different electrolyte aqueous solutions (NaCl, NaBr and CaCl2) with different concentrations (2M and 3M) in a pure-silica chabazite was carried out. In situ synchrotron X-ray powder diffraction experiments were performed in the pressure range of 0.12 -2.6 GPa and upon pressure release, in order to unravel the interactions among intruded species and host material. The energetic performance of the systems were determined by porosimetric studies. Results show that cation in the salt seems to influence the intrusion-extrusion pressures, whereas the structural evolutions, undergone by the systems upon pressure-induced intrusion, are essentially independent on the nature of the penetrating media.Moreover, the initial electrolyte concentration seems to influence only the value of the intrusion pressure, but neither the amount nor the interaction mode of the intruded species. Both water and salt molecules enter the pores and the penetration of comparable extra-framework volumes occurs at similar pressure values. However, the composition of intruded species is different from that of initial solution and depends on applied pressure that reinforces the hypothesis on ion desolvation under penetration into the pores. After pressure release, pure-silica chabazite intruded by NaCl and NaBr aqueous solutions does not recover the initial cell volume and partially retains the intruded extra-framework species. On the contrary, the zeosil intruded by CaCl2 recovers the original cell parameters. These differences have been structurally interpreted on the basis of the electrolyte/zeolite interactions. Interestingly, the extrusion behavior results to be mainly determined by the interactions of the anion with silanol defects of chabazite framework, rather than by the coordination bonds of the cation with the framework oxygen atoms.