The thermodynamic systems consisting of a liquid and a lyophobic porous matrix, that is a porous solid and a non wetting liquid, have the property to accumulate, transform, restore or dissipate energy. 1-3 By submitting these systems to an increasing hydrostatic pressure, the intrusion of the liquid into the pores of the solid is observed when the pressure P becomes equal to the capillary pressure P L 1 which can be expressed by the LaplaceWashburn relation where σ is the surface tension, r the radius of the pores, and θ the contact angle between the liquid and the solid (θ . 90°).During the intrusion of a nonwetting liquid into a porous material, a large interface Ω carrying the surface free energy is created. The development of this surface (∆Ω > 0), leads to an increase in the Gibbs energy (∆G > 0) which may be written as To minimize this energy (∆G < 0), the system spontaneously evolves and decreases its interface (∆Ω < 0) by extrusion of the liquid out of the cavities of the solid. Depending on the external pressure, the molecules of the liquid can penetrate or are expelled from the cavities. 2,4 Therefore, there is a reciprocal transformation of mechanical energy into interfacial energy. When the stress is suppressed, the compressed heterogeneous system spontaneously expands as a result of the extrusion of the liquid and then constitutes a real molecular spring. This property could be used in engineering for devices where short-range molecular forces occur to induce important efforts and large displacements 3-5 such as the spreading of solar panels of satellites.The originality of the present thermodynamic study results in the choice of the constituents of the heterogeneous systems. Water is well suited as the mobile phase; it is a polar liquid, not polluting, easy to obtain as a pure phase, not expensive, and characterized by a high surface tension. The very small water molecules, which are comparable to small spheres of 2.8 Å of diameter, are able to access very small micropores. The choice of water imposes the solid phase to be a hydrophobic porous material. Crystallized microporous solids such as zeolites should be good candidates. These materials show a large variety of structures with variable chemical compositions and are characterized by the presence of micropores with very well defined shape and size. During its intrusion in the zeolitic channels, liquid water disperses as clusters, constituted by few water molecules. Two types of attractive interactions can be involved: (i) the dispersion forces between the water molecules and the pore walls, (ii) the interactions between the water molecules themselves. In the case of these hydrophobic solids, the apparent repulsive interaction between the pore walls and water clusters is probably due to the fact that the latter interaction is stronger than the former.In the present work, the behavior of several "water-zeolite" systems was studied. In particular those including purely siliceous zeolites (zeosils), which present a strong hydrophobic character, for ...

We report a joint experimental and molecular simulation study of water condensation in silicalite-1 zeolite. A sample was synthesized using the fluoride route and was found to contain essentially no defects. A second sample synthesized using the hydroxide route was found to contain a small amount of silanol groups. The thermodynamics of water condensation was studied in these two samples, as well as in a commercial sample, in order to understand the effect of local defects on water adsorption. The molecular simulation study enabled us to qualitatively reproduce the experimentally observed condensation thermodynamics features. A shift and a rounding of the condensation transition was observed with an increasing hydrophilicity of the local defect, but the condensation transition was still observed above the water saturation vapor pressure P0. Both experiments and simulations agree on the fact that a small water uptake can be observed at very low pressure, but that the bulk liquid does not form from the gas phase below P0. The picture that emerges from the observed water condensation mechanism is the existence of a heterogeneous internal surface that is overall hydrophobic, despite the existence of hydrophilic "patches". This heterogeneous surface configuration is thermodynamically stable in a wide range of reduced pressures (from P/P0 = 0.2 to a few thousands), until the condensation transition takes place.

This paper deals with the use of the fluoride route in the synthesis of silica-based zeolites and metallophosphates (mainly gallophosphates) microporous materials, with a special emphasis on the work of the Mulhouse's group during the last recent years. The first part of this account relates to silica-based zeolites and is divided into three sections. The first section is mainly devoted to pure silica and variously substituted MFI-type zeolite (T = Al, Ga, B, Ti....), whereas the second section concerns the synthesis of pure silica or (Si, Al) zeolites with other framework topologies. Among the numerous structure-types so far obtained in fluoride medium, some of them are new and display the small F --containing double four-ring unit (D4R-F). The formation of this type of unit was first observed in the case of the clathrasil octadecasil (AST-structure-type), and is only possible due to the templating and stabilizing effect of the fluoride anion. Besides, the fluoride route leads to pure silica zeolite samples with very few or no connectivity defects. The resulting hydrophobic character allowed us to develop a new application in the field of energetics, where the systems zeolite-water can be used as molecular springs or bumpers. The third section concerns specifically the recently discovered silicogermanate zeolites with new framework topologies. Germanium acts indeed as a real structuredirecting agent, favoring in particular the formation of structures displaying the small D4R or D4R-F unit. The example of IM-10 (IM standing for Institut Français du Pétrole: Mulhouse), with UOZ structure-type, prepared in our laboratory in fluoride medium and from germanium-rich mixtures in the presence of hexamethonium cations, is described. Two other new materials called IM-9 and IM-12, both characterized by the presence of the same D4R-F or D4R unit in their structures, and prepared, respectively, from fluoride-containing or fluoride-free systems in the presence of the (6R,10S)-6,10-dimethyl-5-azoniaspiro [4,5] organic agent, are also presented. The second part concerns the phosphate-based microporous materials prepared in fluoride media and mainly the gallophosphates. As for silica-based zeolites, besides its mineralizing role, Fcan play a templating role, being found inside the small D4R units. Thus many fluorogallophosphates of the Mu-n family, with 0-D, 1-D, 2-D or 3-D frameworks (Mu standing for Mulhouse), showing such a building unit were obtained. Specific experiments are reported about the hydrothermal transformation of the fluorogallophosphate Mu-3 (1-D framework) into the fluorogallophosphate Mu-2 (3-D framework), both containing D4R-F units, and a possible mechanism of reaction is suggested. Several examples are also given where fluorine is part of the framework as terminal groups (Ga-F) or bridging species (Ga-F-Ga). Finally the observed variety

We report a joint experimental and molecular simulation study of water intrusion in silicalite-1 and ferrerite zeolites. The main conclusion of this study is that water condensation takes place through a genuine first-order phase transition, provided that the interconnected pores structure is 3-dimensional. In the extreme confinement situation (ferrierite zeolite), condensation takes place through a continuous transition, which is explained by a shift of both the first-order transition line and the critical point with increasing confinement. The present findings are at odds with the common belief that conventional phase transitions cannot take place in microporous solids such as zeolites. The most important features of the intrusion/extrusion process can be understood in terms of equilibrium thermodynamics considerations. We believe that these findings are very general for hydrophobic solids, i.e. for both nonwetting as well as wetting water-solid interface systems.

Simple but effective: The intrusion/extrusion cycle of a nonwetting fluid in a hydrophobic solid can be described by simple models and simulation methods found useful for studying gas adsorption in nanoporous materials. The water confined to hydrophobic spaces of nanoscopic dimensions in the zeolite silicalite‐1 is shown to be a strongly depleted and highly inhomogeneous fluid (see picture).

Energetic performances of nine channel or cage-type zeosils (AFI, FER, MFI, MEL, TON, MTW, DDR, STT, and CHA-type pure silica zeolites) are obtained using water intrusion−extrusion isotherms. The water intrusion is obtained by applying a high hydraulic pressure corresponding to the intrusion step. When the pressure is released, these nine "zeosil−water" systems behave like a molecular spring, water being spontaneously expelled out of the cavities of the zeosils (extrusion step). The first part of this study details the energetic characteristics of MEL-type zeosil (Silicalite-2), which displays a molecular spring behavior reproducible over several water intrusion−extrusion cycles. However, solid-state NMR spectroscopy revealed the presence of structure defects (>5%), which are responsible for the low value of the stored energy (6.5 J/g of zeosil). In a second part, the energetic properties of the nine channel or cage-type zeosils are compared. For these samples, structural modifications can be observed by solid-state NMR spectroscopy. An overall view of the characteristics derived from the water intrusion− extrusion isotherms of these nine zeosils is discussed. The relation between the structure type, in particular, the porous system (cages or channels) and the intrusion pressure, is studied to better understand the mechanism of water intrusion and to predict the zeolite behavior (intrusion pressure values) for a given structure type. The Laplace−Washburn relationship seems to be not appropriate for microporous materials. A correlation was found between the intrusion pressure and the pore diameter for channel systems and the largest cage size for cage systems.

The autoantigen p43 is a nuclear protein initially identified with autoantibodies from dogs with a lupus-like syndrome. Here we show that p43 is an RNA-binding protein, and identify it as hnRNP G, a previously described component of heterogeneous nuclear ribonucleoprotein complexes. We demonstrate that p43/hnRNP G is glycosylated, and identify the modification as O-linked N-acetylglucosamine. A full-length cDNA clone for hnRNP G has been isolated and sequenced, and the predicted amino acid sequence for hnRNP G shows that it contains one RNP-consensus RNA binding domain (RBD) at the amino terminus and a carboxyl domain rich in serines, arginines and glycines. The RBD of human hnRNP G shows striking similarities with the RBDs of several plant RNA-binding proteins.

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