Monodisperse manganese oxide flowerlike nanostructures have been prepared facilely at low temperature and ambient atmosphere. The effect of the reaction time on the microstructure and morphology is observed systemically by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Meanwhile, the possible formation mechanism of the flowerlike nanostructures has been proposed and discussed. It is also found that the reaction temperature has great influences on the morphology of these unique nanostructures. The results of nitrogen adsorption-desorption experiments and electrochemical measurements show that the product obtained at 40 °C for 8 h has large specific surface area, uniform pore size distribution, and excellent capacitance performance, which make it a potential supercapacitor electrode material.

The modulation of metal-insulator transition (MIT) temperature and phase stability of thermochromic materials based on all the transition metal doped VO 2 were systematically studied using density functional theory (DFT) calculations. The free energies, formation enthalpies, and Fermi energies of transition metal doped VO 2 were evaluated from DFT calculations; the cell volumes and bulk moduli were obtained by fitting the free energies to the Birch-Murnaghan equation of states; and the decomposition enthalpies and entropies of the transition metal doped VO 2 were calculated using both experimental data and DFT calculations. Based on these results, the MIT temperature was associated with lattice distortion of VO 2 (M 1 ) upon doping, the expansion of cell volume and the decrease in bangle were associated with the decrease in MIT temperature, and the shrinkage of cell volume and the increase in b-angle were associated with the increase in MIT temperature. And it was also concluded that VO 2 (M 1 ) doped with high valence cations is more stable than those doped with low valence cations.These conclusions are consistent with experimental facts that W-, Mo-, and Re-are the most studied and the most effective dopants for the reduction of MIT temperature, and La-, Hg-, and Ag-doped VO 2 undergoes phase separation. In addition, DFT calculations without spin-polarization were also carried out, and the influence of spin-polarization was evaluated. Finally, scandium was proposed as a potential dopant for VO 2 in view of balanced comprehensive performance.

Hierarchical cantaloupe-like and hollow microspherical AlOOH superstructures were successfully synthesized on a large scale via a one-step hydrothermal route. The as-obtained superstructures were characterized by several techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen adsorption/ desorption measurement. The as-obtained superstructures, consisting of closely packed nanorods in an ordered fashion, have an average horizontal axis of ca. 2.5 µm and a longitudinal axis of ca. 1.5 µm. The as-obtained cantaloupe-like AlOOH superstructures have Brunauer-Emmett-Teller (BET) surface area of about 55.5 m 2 /g. The possible formation mechanism of the cantaloupe-like AlOOH superstructures is proposed and discussed.

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Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/eng/view/object/?id=e39a317b-2207-400d-8a85-80f321547316 http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/voir/objet/?id=e39a317b-2207-400d-8a85-80f321547316 Standards and Technology, Gaithersburg, Maryland 20899 ReceiVed: June 9, 2004; In Final Form: September 8, 2004 Spontaneously formed unilamellar vesicles (ULV) composed of short-and long-chain phospholipids, dihexanoyl phosphorylcholine (DHPC) and dimyristoyl phosphorylcholine (DMPC), respectively, were doped with a negatively charged lipid, dimyristoyl phosphorylglycerol (DMPG), and studied with small-angle neutron scattering (SANS) and dynamic light scattering (DLS). Upon dilution, the spontaneous formation of vesicles was found to take place from bilayered micelles, or so-called "bicelles". SANS and DLS data show that ULV with narrow size distributions are highly stable at low lipid (C lp < 0.50 wt %) and NaCl salt (C s ) concentrations. ULV size was found to be independent of both C lp and C s when they were below 0.33 and 0.5 wt %, respectively. Surface charge and salinity were found to be important factors in preparing ULV of a certain size. This observation is not in complete agreement with previous experimental results and cannot be completely explained with current theoretical predictions based on equilibrium calculations for catanionic surfactant mixtures. ULV size is found to be invariant over a wide range of temperatures, both below and above the phase-transition temperature, T M , of DMPC, and was stable for periods of weeks and months, even after sonication.