Synthesis regular array

Mesoporous materials of the M41S family with their regular arrays of uniform pore openings and high surface areas have attracted much attention since their first synthesis in 1992 (61), because their properties were expected to open new applications as catalysts and/or adsorbents. These materials are formed by condensation of an amorphous silicate phase in the presence of surfactant molecules (usually ammonium salts with long alkyl chains). However, the chemistry of the steps of the synthesis process is still not fully clear. Ideas put forward so far include (a) condensation of a silicate phase on the surface of a liquid crystalline phase preformed by the surfactant molecules (62) (b) assembly of layers of silicate species in solution followed by puckering of those layers to form hexagonal channels (63) and (c) formation of randomly disordered rod-like micelles with the silicate species... 

Figure 12 Schematic process flow-chart for the CVD synthesis of regular arrays of oriented nanotubes on a porous silicon through catalyst patterning (a) SEM image of nanotube blocks synthesized on 250 tm by 250 pm catalyst pattern. The nanotubes are 80 pm long and oriented perpendicular to the substrate, (b) SEM image of nanotube towers synthesized on 38 pm by 38 pm catalyst pattern. The nanotubes are 130 pm long, and (c) side view of the nantube towers in (b). (Reprinted with permission from S. Fan, M.G. Chapfrne, N.R. Franklin, T.W. Tombler, A.M. Cassell, and H. Dai, Science, 1999, 283, 512. 1999 AAAS)...

The above results have obvious implications for the biosynthesis of cellulose mlcrofIbrlls. The parallel chain structure of cellulose I rules out any kind of regularly folded chain structure, and reveals the mlcrofibrils to be extended chain polymer single crystals, which leads to optimum tensile properties. Work by Brown and co-workers (22) on the mechanism of biosynthesis points to synthesis of arrays of cellulose chains from banks of enzyme complexes on the cell wall. These complexes produce a bundle of chains with the same sense, which crystallize almost immediately afterwards to form cellulose I mlcroflbrlls there is no opportunity to rearrange to form a more stable anti-parallel cellulose II structure. Electron microscopy by Hleta et al. (23) confirms the parallel sense of cellulose chains within the individual mlcroflbrlls stains reactive at the reducing end of the cellulose molecule stain only one end of the mlcroflbrll. 

Methods for preparation of silica samples exhibiting or not porosity are known since a long time [10]. Before the discovery of mesoporous silica [11] zeohtes were the most important materials with micropores forming a regular array of channels with uniform size [12-14]. Mesoporous materials were mainly represented by amorphous silica [1], pillared clays, sihcates [15,16] and certain forms of alumina. A common characteristic of those materials is the irregular spatial distribution of pores and a wide spectrum of pore sizes [17]. In 1992 Beck et al. announced the synthesis and characterization of new mesoporous silica-based materials [11,18]. These mesoporous molecular sieves received the general... 

Novel design methodologies and synthesis techniques for regular array processor architectures intended for regular, high-throughput data-flow appli-cations. 

Regular array synthesis for image and video applications ... 

REGULAR ARRAY SYNTHESIS FOR IMAGE AND VIDEO APPLICATIONS... 

Figure 1 The proposed regular array synthesis methodology.

It has been demonstrated that the proposed design script for regular array synthesis leads to efficiently designed architectures. The script has been developed in the context of the Cathedral project. The re-indexing and localization tools, developed respectively at IMEC and IRISA, can be used to allow a higher input behavioral description of an application. The transformations provided by these tools can also be useful in other architecture synthesis areas. 

M. van Swaaij, J. Rosseel, F. Catthoor, and H. De Man. Synthesis of ASIC regular arrays for real-time image processing systems. In E. Deprettere et al., editors, Algorithms and Parallel VLSI Architectures, Vol. B, pages 329-342, Elsevier Science, 1991. 

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