Arthropod shells

Chitin (poly(N-acetyl-D-glucosatnine)) represents the second most abundant polysaccharide after cellulose. It is found in the exoskeleton of crustaceans and insects and in the cell wall of fungi and microorganisms [23], Arthropod shells (exoskeletons), the most easily accessible sources of chitin, contain 20-50% of chitin on a dry basis. Wastes of seafood processing industries ate used for the commercial production of chitin. 

When the animal is alive, the shell may be covered with a layer of fibrous tissue known as the periostracum. This layer may be very thin and translucent, or thick and dark. It is composed of chitin, a polysaccharide that also makes up the exoskeletons of insects and other arthropods. 

We used the crosslinked chitosan fiber (hereafter called ChF) in this experimental study. ChF was fabricated by Fuji Spinning Co., Japan. Fig.l shows the unit molecular structure of chitosan which was transformed from chitin by deacetylation. Chitin is a natural biopolymer which is contained in the shell of arthropods. Chitosan was crosslinked to make an adsorbent with acid, alkaline, and chemical proofs. The fabrication method of ChF was presented elsewhere.[S,6]. 

Lowenstam and Weiner (1989, pp. 8-11, table 2.1) clearly show that carbonates dominate in biomineralization. They even occur in plants and fungi. The volume percent of limestone and marbles is well documented from the Precambrian to the present. Whether these rocks are inorganic precipitates or festooned with fossils, many of the living creatures had biomineralized with calcium carbonate, is usually clear. Indeed, some strata are composed entirely of calcium carbonate shells. We present examples of carbonate mineral deposition in cyanobacteria, corals, coccoliths, foraminifera, mollusks, echinoids, and the arthropods. 

The body of an arthropod is covered with a hard shell called the exoskeleton, which provides structural support and protection from predators. The skeletons of arthropods are primarily composed of chitin, an extremely tough but highly flexible material made of long chains of molecules that are similar in structure to cellulose. 

Chitin is another highly available polysaccharide biopolymer it is derived from the exoskeleton of arthropods (specifically crab and shrimp shells) and formed from repeats of (l,4)-linked V-acetyl-p-D-glucosamine. In its natural form, the chains of... 

Chitin is a homopolymer of AT-acetyl-D-glucosamine residues and is a major structural component in the exoskeletons of crustaceans, mollusks, arthropods, and the cell walls of numerous fungi and algae. Owing to its widespread presence in both terrestrial and aquatic organisms, chitin is second only to cellulose as the most abundant biopolymer on the Earth (Shahidi and Abuzaytoun, 2005). On a dry weight basis, shrimp, crab, lobster, prawn, and crayfish have been reported to contain between 14% and 35% chitin, while deproteinized dry shell waste of Antarctic krill contains approximately 40% crude chitin (Haard et al, 1994). Crustaceans are the primary sources of chitin used in industry. Chitin can be extracted from shellfish and crustacean waste by mixing with a dilute add to induce demineralization, followed by a deproteini-zation step in a hot alkaline solution (Synowiecki and Al-Khateeb, 2003). 

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