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The surface and pore structure of cellulose fibers have a significant impact on the properties and performance in applications. Cellulase enzymatic hydrolysis of cellulose fibers can result in changes to the surface and pore structure, thus providing a useful tool for fiber modification. This research characterizes these changes using various test methods such as fiber dimension, water retention value (WRV), hard-to-remove (HR) water content, freezing and nonfreezing bound water content, polymer adsorption, and crystallinity index. For a high-dosage cellulase treatment (600 U/g dry solid), the fiber length was significantly decreased and the fibers were “cut” in the cross direction, not in the axial direction. The swelling capacities as measured by the WRV and HR water content increased for the high-dosage treatment. Three independent measurements (nonfreezing bound water, polymer adsorption, and crystallinity index) are in good agreement with the statement that the amorphous regions of cellulose fibers are a more readily available substrate relative to crystalline regions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3833–3839, 2007

Acid-catalyzed vapor phase esterification with maleic anhydride was used to improve the integrity and thermo-mechanical properties of fiber webs based on poly(vinyl alcohol), PVA. The fibers were produced by electrospinning PVA from aqueous disper- sions containing cellulose nanocrystals (CNCs). The effect of esterification and CNC loading on the structure and solvent resistance of the electrospun fibers was investigated. Chemical characterization of the fibers (FTIR, NMR) indicated the formation of ester bonds between hydroxyl groups belonging to neighboring molecules. Thermomechanical properties after chemical modification were analyzed using thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. An 80% improve- ment in the ultimate strength was achieved for CNC-loaded, crosslinked PVA fiber webs measured at 90% air relative humidity. Besides the ultra-high surface area, the composite PVA fiber webs were water resistant and presented excellent mechanical properties. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40334.

The gross structure of perimycin A was revised: the position of the keto group was changed from C-13 to C-5. The Stereostructure of perimycin A was established based upon NMR studies.

NMR studies of rimocidin, consisting of DQF-COSY, ROESY, HSQC, HMBC and 1D-TOCSY experiments, resulted in the assignment of the absolute configuration of the rimocidin chiral centers as 2S, 3R, 9S, 11R, 13S, 14R, 15S, 17R and 27R. The geometry of tetraene chromophore was found to be all-trans.

The Stereostructure of amphotericin A was established on the basis of NMR studies which contained DQF COSY, ROESY, ID TOCSY, HSQC and HMBC experiments.

and roxaticin3 have been determined by x-ray analysis, because most of the polyene macrolides exhibit poor crystallinity. On the other hand, NMR studies of polyene macro- lides have long been hampered by their low solubility and high tendency for association, for which reason DMSO-d, is the most commonly used solvent. The res- onance line width in DMSO-d, was 7-8 Hz? and this almost prevented coupling constant analysis.