Modification by chemical means

Nano tubes, in particular SWNTs, are typically held together as bundles, resulting in poor NT dispersion in polymer matrices. Since, due to the relatively smooth graphene Hke surface of NTs, there is a lack of interfacial bonding between polymer matrix and carbon nanotubes, surface modification by chemical means of NTs has been envisaged as a very important factor to overcome this problem and to fadhtate NTs processing and applications [30]. 

The elimination or inactivation of enzymes used to treat proteins is a critical problem once the desired modification in functionality is achieved. In many instances, product inhibition or self destruction does not occur as noted above for fish protein concentrate. As stated by Puski (20), if heat inactivation is used, the proteins may be denatureT"and revert to insoluble forms. Washing out the enzyme at its isoelectric point would also remove a portion of the protein which is solubilized by the enzyme. Inactivation of enzymes by chemical means may also cause significant changes in the protein. Thus, while desired functional modifications of food ingredients may be obtained through enzyme treatment, the problem of latent enzyme activity in food formulations must be addressed. 

As the native cyclodextrins (CDs) exhibit some limitations in application, they need to be modified to improve the properties. All the modification methods could be divided into two kinds, chemical modification and enzymatic modification. Based on the stable cyclic structure, CDs could be modified via etherification, esterification, oxidation and crosslinking reactions. The chemical modification has a special purpose of introducing novel functional group. CDs modified by chemical means were named as cyclodextrin chemical derivatives (CCDs). 

The total synthesis of natural products and their structural variants by chemical means may indirectly expand our understanding of structure-activity relationships of the parent molecule. For example, the biological activity and therapeutic profile of many antibiotics of natural origin have been improved by chemical modification from a knowledge of their modes of action, inactivation by endogenous enzymes and other molecular events. 

The final section contains six chapters emphasizing the use of proteinaceous materials as leather, wool, polypeptides, and collagen. The chemical modification of leather through the use of radiation, and poly(gamma-methyl-L-glutamate) membranes is described as is the modification of collagen, wool, and leather by chemical means. 

The feed preparation stage e.g. by mineral extraction and evaporation, chemical reaction etc. can give rise to both dissolved and suspended solid impurities, either of which may affect the crystallization step. Removal of suspended solids, e.g. by filtration, is usually the easier process. Dissolved impurities can have by far the more pronounced effect, however, and may have to be removed e.g. by chemical means or by adsorption. Such impurities may, of course, actually be beneficial to the process by inducing nucleation, habit modification etc. 

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