Sponge structure

The choice of the inorganic supports was based on their different structural features. The MCM-41 material consists of uniform hexagonal arrays of linear channels that are constructed with a silica matrix like a honeycomb (Fig. 6), whereas HMS (hexagonal molecular silica) has a wormlike or sponge structure (Fig. 7) [94-100],... 

The most general surface within this class is a boundless sponge structure (Fig. 1.11). The mathematics of such random surfaces is at present poorly developed. We confine our treatment to the more tractable cases of periodic surfaces of imboimded genus. 

F 1. Farbenfabriken Bayer AG Anion exchanger with sponge structure. Brit. Pat. 885.719 (1961). 

V. Lehmann and U. Gosele, Porous silicon Quantum sponge structures grown via a self-adjusting etching process, Adv. Mater. 4, 114, 1992. 

The formation of the sponge-structured membranes can be easily rationalized utilizing the description of the precipitation process given above. With finger-structured membranes the formation process is more complex and cannot entirely be described by the thermodynamic and kinetic arguments of phase separation processes. 

The membrane thickness comes to a minimum where permeation has the lowest value. Scanning electron microscope studies on membrane substrate structure revealed that a change from a finely pored sponge structure to a coarsely pored finger structure occurs at the point where the membrane thickness turns to go up with increase in cyclohexanone content as already shown in Figure 6. 

The cells of the structure can be either closed or open. The former type is like a foam, in that the matrix can geometrically be compared with the continuous phase of the foam, which consists of thin lamellae and Plateau borders. Here we have thicker lamellae or walls, and beams (struts, ribs) where two lamellae meet if the cells are filled with gas we can call the system a solid foam. Open cells occur when the lamellae contain holes now we speak of a sponge. Some types of sponge structures merely consist of beams. Most plant tissues (see, e.g., Figure 9.4) consist of closed cells that are mainly filled with an aqueous liquid. 

Figure 1.14 Scanning electron micrograph of membrane cross sections with typical structures (a) symmetric microporous membrane without a "skin" (b) asymmetric membrane with a "finger"-type structure and a dense skin at the surface (c) asymmetric membrane with a "sponge"-type structure, a dense skin, and pore sizes increasing from the surface to the bottom side (d) symmetric membrane with a sponge structure, a dense skin and a uniform pore size distribution in the substructure.

Water-soluble EDC is non-toxic and biocompatible. It is not incorporated directly into the crosslinked sponge structure, but is changed to water-soluble urea derivatives... 

A porous material consists of at least two immiscible phases of which one is usually a continuous sohd material, the matrix, which surrounds the second phase of finely dispersed voids, the pores, containing a liquid, gas, or vacuum. If the void phase is discontinuous and comprises individually separated cavities filled with gas (bubbles), the material represents a foam structure. On the other hand, if both phases form two interpenetrating continua with the matrix as well as the pores being continuous, the material represents a sponge structure or a so-called porous network. Such porous networks with interconnected voids are the focus of this article as they may have funda-... 

These anatase sponge structures combine the convenient handling of larger spheres with a very high sur ce area and narrow pore size distribution and are expected to have potential in solar energy conversion, catalysis and optoelectronic... 

In particular, evaporation of water from the textile layer reduces the temperature and induces the feeling of clamminess. The feeling of wetness is often considered tmpleasant, and therefore efforts are undertaken to minimize the feeling. When touching wetted cotton, sponge-structured, and thin viscose with the hands, no differences in perception of wemess were observed between the materials (Bergmann Tiest et al., 2012a). However, it is not unlikely that the evaluation of wetness in terms of comfort may differ, similar to the above example. 

The membrane tended to have a dense and sponge structure when Ag was added during dope preparation. In addition to higher water flux and higher BSA rejection, the PES/Ag membrane also showed higher antibacteriality than the neat PES membrane. 

All these results should convince us that the monomer plays a crucial role in the phase diagrams of these systems. In fact, this role, more or less ignored by formulators until recently, is two-fold. As a cosurfactant, the monomer increases flexibility of the interfacial film. It can therefore deform more easily to produce a sponge structure. And as an electrolyte, the monomer reduces aqueous solubility of ethoxylated surfactants. It thereby favours their gradual transfer into the organic phase and the formation of a bicontinuous structure. This effect of salt in the formation of bicontinuous microemulsions is well known to the users of such systems. It is significant in this respect that the same systems without monomer or electrolyte (if the monomer is neutral) do not lead to bicontinuous structures. 

Bisi O, Ossicinib S, Pavesi L (2000) Porous silicon a quantum sponge structure for silicon based... 

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