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Glassy carbon electrodes are modified with a thin film of a cellulose-chitosan nanocomposite. Cellulose nanofibrils (of ca. 4 nm diameter and 250 nm length) are employed as an inert backbone and chitosan (poly-d-glucosamine, low molecular weight, 75 -85% deacetylated) is introduced as a structural binder and "receptor" or molecular binding site. The composite films are formed in a solvent evaporation method and prepared in approximately 0.8 mm thickness. The adsorption of three molecular systems into the cellulose-chitosan films is investigated and approximate Langmuirian binding constants are evaluated: i) Fe(CN) 6 4À (K Ferrocyanide ¼ 2.2 Â 10 3 mol À1 dm 3 in 0.1 M phosphate buffer at pH 6) is observed to bind to ammonium chitosan functionalities (present at pH < 7), ii) triclosan (K Triclosan ¼ 2.6 Â 10 3 mol À1 dm 3 in 0.1 M phosphate buffer pH 9.5) is shown to bind only weakly and under alkaline conditions, and iii) the anionic surfactant dodecylsulfate (K SDS ¼ 3.3 Â 10 4 mol À1 dm 3 in 0.1 M phosphate buffer pH 6) is shown to bind relatively more strongly in acidic media. The competitive binding of Fe(CN) 6 4À and dodecylsulfate anions is proposed as a way to accumulate and indirectly determine the anionic surfactant.

This paper describes a manipulative stage which can be used to vary the strain applied to fibers, yarns, fabrics, or films within the evacuated specimen chamber of a Cambridge Stereoscan SEM. In another similar stage, an object can be twisted or rotated about its axis so that its complete periphery may be examined.Some of the problems encountered, such as the difficulty in maintaining a conductive surface, are considered. Qualitative observations of the fracture characteristics of some types of natural and commercial man-made fibers strained in tensile, loop tensile, and knot tensile tests are presented, as well as some observations on fibers subjected to twisting forces. Finally, observations on the tearing,of a photographic film are recorded.