MnO2 nanostructures with sea urchin shapes have been prepared by an sodium dodecyl sulfate (SDS)-assisted hydrothermal treatment method. The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). XRD patterns indicated that the sea urchin shaped MnO2 nanostructures were tetragonal phase. Furthermore, SEM and TEM revealed that MnO2 nanostructures with sea urchin shapes consisted of MnO2 nanorods 150−200 nm wide and several micrometers long. A growth mechanism of MnO2 nanostructures with sea urchin shapes was suggested and explained in detail.

Densities and viscosities of aqueous solutions of R-amino acids (glycine, DL-alanine, DL-R-amino-n-butyric acid, DL-R-valine, and DL-R-leucine) + sodium caprylate have been measured as a function of the concentrations of amino acid and sodium caprylate at 298.15 K. These data have been used to calculate apparent molar volumes and viscosity B coefficients of the amino acids. The standard partial molar volume V°2 ,φ and standard volumes of transfer ∆ t V°have been determined for the amino acids. It has been shown that values of V°2 ,φ and the B coefficient vary linearly with the increasing number of carbon atoms in the alkyl chain of the amino acids, and they were split into contributions from the zwitterionic end group (NH 3 + , COO -) and CH 2 groups of the amino acids. From the volumetric data, it is suggested that the amino acids are solubilized in the palisade layer of sodium caprylate micelles. The viscosity properties have been interpreted in light of the solute-solvent interactions in aqueous media.