Spinning gland

Nevertheless, silk spinning remains a very complex process. Spiders and silkworms not only have a set of well-developed spinning glands but also have a set of well-defined and controlled chemical boundary conditions. Besides the composition of the spinning dope, the spinning techniques and the combination of chemical parameters (pH and metallic ions) must be considered and optimized. 

The different spinning glands in the spider s abdomen produce different kinds of silks, such as draglines, frame threads, mooring radial threads, spiral threads, sticky material, egg cocoon, swathing bands and attachment discs. 

Apart from the above-mentioned fiber formation techniques, biomaterial fibers may be produced by other techniques. Among these, biospinning plays an important role. Biospinning is defined as the process of direct fiber drawing from the spinning glands of various insects such as silkworms and spiders [37]. Biospun fibers, eg, from Bombyx mori silkworms, have been traditionally used as suture material [38]. 

Figure 10.7. Schematic of two sfik spinning glands that join just before the duct. (Willcox, P.J., et. a., Macromolecules, 29, 5106-5110,1996.)...

The problems of identification are not nearly so acute when dealing with metalloproteins as they have a wide range of g values, and a number of these have been observed in whole tissue. Thus, the low spin ferric form of cytochrome P-450 has been observed in liver and its concentration found to be reduced in Morris hepatomas [82]. Adrenal ferredoxin in adrenal glands [83], sulphite oxidase in liver [84], iron-sulphur proteins in pigeon heart [85], methaemoglobin and erythrocyte catalase in whole blood are further examples in mammals. 

The silkworm spins the whole of its cocoon without a stop and the silk therefore is a continuous thread. One cocoon may contain about three thousand yards of silk and about one thousand cocoons would be required to produce 4 oz of useful thread. The spinning of the cocoon takes 3 to 4 days and when it is complete the worm changes into a pupa which may be either male or female. The cocoons producing males are somewhat smaller and more cylindrical in shape than those from which the females emerge (see Fig. 5.24). Although the two glands join at a common orifice they produce separate filaments known as... 

For a long time, the Hartree-Fock (HF) theory combined with the self-consistent field (SCF) procedure proved arguably to be the most useful method for computational chemists despite its well-known limitations. Within its framework, orbitals can be constmcted to reflect paired or unpaired electrons. If the molecular system has a singlet spin state, then the same orbital spatial function can be used for both the Gland (3-spin electrons in each pair. This assumption is called the restricted Hartree-Fock method (RHF). 

Dynamic NMR studies of the silk fibroin from silkworms have been reviewed. The chain dynamics of B. ntori and S.c. ricini silk fibroins in aqueous solution were studied to determine the relaxation parameters spin-lattice relaxation time, nuclear Overhauser enhancement and line width. - C NMR observations were also made to study the chain dynamics of silk fibroin stored in the silk gland of living silkworms. The chain dynamics of the B. mori and S.c. ricini silk fibroin fiber were studied with "H and C solid-state NMR. The solid-state NMR spectra of S.c. ricini silk fibroins showed a gradual and monotonic slowdown of the overall molecular motions leading to molecular aggregation. The chain dynamics of silk fibroin absorbed solvent were detected by H and C solid-state NMR methods, and also using an NMR imaging method. ESR approaches were applied to the dynamic studies of Tyr side-chain in the silk fibroin. 

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