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Emanuela Fabiola Craparo Girolamo Teresi Maria Chiara Ognibene Maria Pia Casaletto Maria Luisa Bondì Gennara Cavallaro 《Journal of nanoparticle research》2010,12(7):2629-2644
In this article, the synthesis of two amphiphilic polyaspartamide copolymers, useful to obtain polymeric nanoparticles without
using surfactants or stabilizing agents, is described. These copolymers were obtained starting from α,β-poly-(N-2-hydroxyethyl)-dl-aspartamide (PHEA) by following a novel synthetic strategy. In particular, PHEA and its pegylated derivative (PHEA-PEG2000) were functionalized with poly(lactic acid) (PLA) through 1,1′-carbonyldiimidazole (CDI) activation to obtain PHEA–PLA and
PHEA-PEG2000–PLA graft copolymers, respectively. These copolymers were properly purified and characterized by 1H-NMR, FT-IR, and Size Exclusion Chromatography (SEC) analyses, which confirmed that derivatization reactions occurred. Nanoparticles
were obtained from PHEA–PLA and PHEA-PEG2000–PLA graft copolymers by using the high pressure homogenization-solvent evaporation method, avoiding the use of surfactants
or stabilizing agents. Polymeric nanoparticles were characterized by dimensional analysis, before and after freeze-drying
process, and Scanning Electron Microscopy (SEM). Zeta potential measurements and X-ray Photoelectron Spectroscopy (XPS) analysis
demonstrated the presence of PEG and/or PHEA onto the PHEA-PEG2000–PLA and PHEA–PLA nanoparticle surface, respectively. 相似文献
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Nanostructured perovskite-type Sr1−aCeaFeO3−x, (0?a<0.15) powders have been prepared by citrate-nitrate smoldering auto-combustion. Their phase structure and stability, surface and morphological properties, reduction behavior and interaction with oxygen have been investigated by X-ray Powder Diffraction combined with Rietveld Analysis, 57Fe Mössbauer and X-ray Photoelectron Spectroscopies, N2-adsorption method, Temperature Programmed Reduction and Oxidation experiments. Our results reveal that citrate-nitrate auto-combustion method is effective in obtaining single phase Sr1−aCeaFeO3−x. The Sr1−aCeaFeO3−x structure is cubic only for a?0.06, while for a<0.06 remains tetragonal. Moreover, for a?0.06 after semi-reductive treatment under inert gas, an expanded cubic phase is obtained instead of the brownmillerite-type structure, which is known to have ordered vacancies. Stabilization of octahedral Fe3+ by cerium doping appears to be the main factor in determining the structural properties of Sr1−aCeaFeO3−x. The highest oxygen consumption for Ce-doped SrFeO3 occurs for a=0.06. Preliminary impedance measurements show that Sr0.94Ce0.06FeO3−x has the lowest area-specific resistance. 相似文献
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M. Brai M. P. Casaletto G. Gennaro M. Marrale T. Schillaci L. Tranchina 《Applied Physics A: Materials Science & Processing》2010,100(3):945-951
In the present work results on the degradation phenomena of stone materials in the Ancient Theatre of Taormina, one of the
most important Greek–Roman monuments of Sicily, are reported. Artificial stone materials in different conservation conditions
were investigated. Samples of salt efflorescences from brick walls and degraded setting mortars were taken from the open gallery
in “summa cavea”. The chemical, physical and structural characterization was performed by means of X-Ray Photoelectron Spectroscopy (XPS),
X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF), both in situ and ex situ. 相似文献
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Conservative methods for the Toda lattice equations 总被引:1,自引:0,他引:1
We are concerned with the numerical integration of the Todalattice equations by using different conservative methods. Numericalexperiments suggest that the global error for isospectral schemesdecreases exponentially with time but it is almost constantfor either symplectic or more general integrators. We providea theoretical explanation for these experimental findings. 相似文献
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