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Size and shape of sodium deoxycholate micellar aggregates
No full textFrom SAXS and ESR measurements carried out on sodium deoxycholate (NaDC) aqueous solutions as a function of NaDC
and NaCl concentrations and temperature we have deduced the mean hydrodynamic radius, shape, and aggregation number
of the micellar aggregates. The validity of a helical model previously proposed for NaDC micellar aggregates was satisfactorily
checked. Some limits of the experimental techniques are discussed. A qualitative agreement between the data obtained
from SAXS and ESR measurements was observed. The extent of micellar growth increases with the concentration of added
NaCl and as the temperature is lowered. Much smaller changes than for the ionic strength were detected by increasing
the NaDC concentration within the range 0.05-0.15 M
Verifica delle condizioni di stress idrico in specie arboree ed arbustive del Gran Sasso: studi preliminari
No full text
EXAFS - A NEW APPROACH TO THE STRUCTURE OF MICELLAR AGGREGATES
No full textA helical model was previously proposed for sodium (NaDC) and rubidium (RbDC) deoxycholate micellar aggregates in
aqueous solutions. SAXS, NMR, ESR, and CD meehurements verified the helical model. Here we report an EXAFS study
by the spherical wave formalism on the coordination of the Rb' ions in the crystal, macromolecular fiber, and micellar aqueous
solution of RbDC together with measurements carried out on rubidium oxalate (crystal and aqueous solution). The results
show that the Rb" ions of the micellar aggregates have the same (or very similar) peculiar coordination as that inside the
helices of the crystal and macromolecular fiber. Moreover, their coordination remarkably differs from that observed in the
aqueous solutions of rubidium oxalate, where the situation would be similar to that of a classical micelle. Thus, the helical
model is unquestionably confirmed
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