Structure brick-like

Nacreous structure layer a layer consisting of stacked platy aragonite crystals in brick-like layers and an interstitial protein layer. 

Earlier concepts about the fine structure of microfibrils have been reviewed by several authors - " and will be only briefly mentioned here as background for the description of later developments. In 1858, Nageli - - proposed the micellar theory this assumed the presence of separate, brick-like, crystalline micelles within the cellulose fibers (see Fig. 6) to explain the birefringence observed with a polarized... 

Fig, 6.—The Brick-like Structure of Cellulose Fibers, According to the Original Micellar Theory... 

The cell wall of S. cerevisiae, like that of other fungi, is very strong. Despite its great strength, one should remember that the cell wall is a dynamic structure (unlike a brick wall). There are three major components ... 

Like the natural iron oxide pigments, the synthetics are used for colouring concrete, bitumen, asphalt, tiles, bricks, ceramics and glass. They are also used extensively in house and marine paints. Because the shapes of the particles can be accurately controlled and the particle size distribution is narrow, synthetic iron oxides have a greater tinting strength than the natural ones and so, are chosen where paint colour is important, i. e., for top coats. Red iron oxides are used in primers for automobiles and steel structures. 

Packing of the cyclodextrin molecules (a, p, p) within the crystal lattice of inclusion compounds (58,59) occurs in one of two modes, described as cage and channel structures (Fig. 7). In channel-type inclusions, cyclodextrin molecules are stacked on top of one another like coins in a roll producing endless channels in which guest molecules are embedded (Fig. 7a). In crystal structures of the cage type, the cavity of one cyclodextrin molecule is blocked off on both sides by neighboring cyclodextrin molecules packed crosswise in herringbone fashion (Fig. 7b), or in a motif reminiscent of bricks in a wall (Fig. 7c). 

The outermost layer of the skin, the cornified layer or stratum corneum, has been identified as the principal diffusion barrier for substances, including water [2,3]. It is approximately 10 to 20 pm thick when dry but swells to several times this thickness when fully hydrated [17], It contains 10 to 25 layers lying parallel to the skin surface of nonviable cells, the corneocytes, which are surrounded by a cell envelope and imbedded in a lipid matrix. This architecture is often modeled as a wall-like structure, with the corneocytes as protein bricks embedded in a lipid mortar [18]. Similarly to the viable epidermis, desmosomes (corneodesmosomes) contribute to the cell cohesion. 

Group 2 elements typically form ionic carbides of formnla MC2. When BeO is heated with C at 1900-2000 °C, a brick red colored carbide of formula Bo2C results. This ionic compound adopts the antifluorite structure, that is, like the Cap2 structure except that the positions of the cations and Anions are interchanged. It is unusual because it reacts with water, forming methane, and is thus called a methanide (equation 9). 

Figure 9.11 (a) Brick-wall-like structure of [Gd(DMF)2(H20)3Cr(CN)6]-H20. (b) Temperature dependence of xmT for [Gd(DMF)2(H20)3Cr(CN)6]-H20. Inset left, isothermal magnetization at 1.8 K right, real and imaginary AC susceptibilities in zero applied DC field and an AC field of 2 Oe at different frequencies [49]. (Reprinted with permission from H. Kou, etal., Metamagnetism of the first cyano-bridged two-dimensional brick-wall-like 4f-3d array, Chemistry of Materials, 13, 1431-1433, 2001. 2001 American Chemical Society.)... 

Suspensions or dispersions of particles in a liquid medium are ubiquitous. Blood, paint, ink, and cement are examples that hint at the diversity and technological importance of suspensions. Suspensions include drilling muds, foodstuffs, pharmaceuticals, ointments and cremes, and abrasive cleansers and are precursors of many manufactured goods, such as composites and ceramics. Control of the structure and flow properties of such suspensions is often vital to the commercial success of the product or of its manufacture. For example, in consumer products, such as toothpaste, the rheology of the suspension can often determine consumer satisfaction. In ceramic processing, dense suspensions are sometimes molded (Lange 1989) and then dried and sintered or fired into optical components, porcelin insulators, turbine blades, fuel cells, and bricks (Rice 1990 Simon 1993). Crucial to the success of the processing is the ability to transform a liquid, moldable suspension into a solid-like one that retains its shape when removed from the mold. These examples could be multiplied many times over. 

Now, as the weir wall brick grow and expand, the brick can release thermal stress by sliding outward on the Teflon film under them, and slide into the brick slots in the wall, compressing the foam. This curved design provides for both the thrust against the wall from upstream and the expansion of the brick in the weir wall. The designer should bear in mind that like other all-brick structures, this wall will not be liquid-tight and will weep into the downstream side. It will, however, act to trap any suspended material that settles out. 

A technique used for dating ceramics, bricks, sediment layers, burnt flint, lava, and even cave structures like stalactites and stalagmites, based on the fact that some materials, when heated, give off a flash of light. The intensity of the light is used to date the specimen and is proportional to the quantity of radiation to which it has been exposed and the time span since it was heated. The technique is similar to electron spin resonance (ESR). Good for dates between 10,000 and 230,000 years. 

---