Abalone shell

Fig. 13.19. Abalone shell (a) AFM (b) UFM (c) W-UFM (d) AFM (e) HFM amplitude (f) HFM phase. All images 2(tm x 2//m the second row is of a different area. The ultrasonic frequency was 9.5 MHz the difference frequency for HFM was 2.7 kHz. In the HFM phase image the full greyscale corresponds to a phase delay of 10 ns. The arrows in the HFM images indicate features attributed to bifurcation of layers (sample courtesy of Mehmet Sarikaya).

Fig. 2. Nacre of red abalone shell Halitotis refescens), imaged here by transmission electron microscopy (left), has a bricks-and-mortar structure. The bricks are CaCOs (aragonite) platelets, and the mortar is a composite of macromolecules, including structural proteins and polysaccharides, that form a thin film around the platelets. The three-dimensional structure is depicted on the right [23]...

This chapter identifies the limitations the various official parties to a cleanup action have. It is not intended as an indictment of incompetence but rather as a reminder of the strengths and weaknesses of the players. Of course, this book is designed to teach, refresh, remind, or supplement the knowledge gaps of each of the major players in addition to serving as a crash course for those who do not know a 105 shell from an abalone shell. 

FIGURE 35.12 (a) Schematic of the abalone shell, (b) Abalone slabs. 

Figure 35.12a Redrawn after Lin, A. and Meyers, M. A. (2005) Growth and structure in abalone shell, Mater. Sci. Eng. A 390 27.

Calcium and oxygen are major players in other external materials encountered in nature beyond shells and bones. Abalone shells, deer antlers, lobster shells, sponge skeletons, bird-of-paradise stems, porcupine quills, toucan beaks, and feathers are all listed in a single review on biomimetic materials, and all are linked with calcium, oxygen, and/or oxidized crosslinks. This is what calcium and oxygen made possible right before the Cambrian explosion. 

The many forms of calcium carbonate described clockwise from top). An abalone shell is composed of thin overlapping layers of calcium carbonate, interspersed with a protein (a class of macromolecules described in Chapter 22). Limestone is a mixture of calcium carbonate and other compounds found in sedimentary rocks. Aragonite is one of the crystalline solid forms of calcium carbonate, characterized by the arrangement of carbonate ions in two planes that point in opposite directions. Blackboard chalk is often incorrectly believed to be made from the mineral chalk, which is a form of calcium carbonate, but, in fact, it is made from calcium sulfate. Iceland spar is the clear form of the mineral calcite, which is calcium carbonate arranged in a different crystal structure from that of aragonite. 

Industrial Products. The commercial value of fish is not limited to its use as food. Various industrial products contain fish parts or fish by-products. For example, manufacturers make shoes from the skins of sharks. Abalone shells are made into buttons. Other manufacturers use by-products to make glue. A kind of gelatin called isinglass is made from the air bladders of certain fish. Menhaden, sardines, herrings, and sharks produce valuable oils. These oils are used in making paints and varnishes, in tanning leather, and in the manufacture of linoleum and synthetic materials. 

Figure 14.6. A polished abalone (paua) shell from New Zealand (left) and a crystal of the mineral calcite (right). Both materials are constmcted from calcium carbonate, but in the abalone shell, the material takes the form of many layers, each a few hundred nanometers thick. These otherwise clear layers diffract light to impart the vivid colors seen in the shell.

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