Elastic modulus of single cellulose microfibrils from tunicate measured by atomic force microscopy.

The elastic modulus of single microfibrils from tunicate ( Halocynthia papillosa ) cellulose was measured by atomic force microscopy (AFM). Microfibrils with cross-sectional dimensions 8 x 20 nm and several micrometers in length were obtained by oxidation of cellulose with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) as a catalyst and subsequent mechanical disintegration in water and by sulfuric acid hydrolysis. The nanocellulosic materials were deposited on a specially designed silicon wafer with grooves 227 nm in width, and a three-point bending test was applied to determine the elastic modulus using an AFM cantilever.

[Study on preparation of berberine microemulsion and its absorption in intestine].

Objective: To prepare berberine microemulsion, and to investigate its properities and the absorption character in rat intestine in situ.

Method: The optimum formulation of the blank microemulsion selected by pseudo tertiary phase diagrams and the berberine microemulsion was prepared based on the blank microemulsion. The viscosity, conductance, refraction rate and particle size of berberine microemulsion were surveyed.

Polymorphic packing and dynamics of biodegradable poly(3-hydroxypropionate).

The packing and dynamics of the beta-, gamma-, and delta-forms of poly(3-hydroxypropionate) (P3HP), which represents the basic skeleton of bacterial poly(3-hydroxyalkanoate)s, were investigated by the variable-temperature FTIR and (13)C solid-state NMR measurements (SNMR). Under cooling, most of IR bands in the 1500-750 cm(-1) region were noted to be distinctively blueshifted and enhanced, which should reflect the increased intermolecular interaction and depend on the chain packing of each crystal form. Furthermore, the temperature-dependent splitting of vibration were found to occur at the CH2 bending and rocking for the gamma-form, and at the CH2 bending and C-O-C stretching for the delta-form, while be absent for the beta-form.