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Masotti A 《Recent patents on nanotechnology》2011,5(3):163-177
In recent years, polymeric scaffolds have been used in several biomedical applications for delivery of drugs or other biologically relevant molecules. Polymeric nanostructures display different (and in some cases more powerful) properties respect to bulk materials. This, lead academic researchers and industry to cooperate in developing pioneering nanostructured materials for industrial and biomedical applications. Moreover, the preparation and use of systems with multiple (multifunctional) properties (i.e., bioconjugation with superparamagnetic, fluorescent or targeting molecules) is positioned to become a viable and innovative tool for application in several clinical fields. Other nanostructured systems like nanocages and degradable nanoparticles, are emerging as potential innovative systems that could be exploited as multifunctional delivery vectors. This brief critical review is aimed at collecting and discussing some recent patents dealing with the preparation and use of multifunctional nanoparticles, nanocages and degradable nanoparticles in biomedicine and non-invasive bioimaging applications. Perspectives for a potential use of these multifunctional nanosystems in pediatries have been also discussed. 相似文献
995.
Daniele Pellegrini Andrea Ghiotti Stefania Bruschi 《International Journal of Material Forming》2011,4(2):155-161
The paper presents the mechanical and microstructural characterization of the magnesium alloy AZ31B through tests conducted at elevated temperature on a dedicated uni-axial tensile set-up. The samples are heated in-situ through induction heating and their actual deformation is recorded in-line through the Aramis? system. Results from the tests in terms of flow stress, plastic properties and anisotropic coefficients are presented and commented. Additionally, the microstructural analysis on deformed samples in terms of grain size and recrystallized fraction is shown, in order to identify the fundamental mechanisms of dynamic recrystallization and grain growth and to correlate them with the testing parameters. The study provides the best combination of process parameters that can assure, at the same time, good formability and sound microstructure in the warm forming temperature range. 相似文献
996.
This article critically reviews methodologies and theoretical orientations of 27 published empirical studies examining the graduate school experiences of students of color using Bronfenbrenner's (1979, 1994) bioecological model. Despite the urgent need for evidence-based approaches to increase the number of scholars of color, the findings in this review indicate an inadequate number of studies explaining how to realize that goal. Furthermore, much of the existing literature examined individual-level characteristics rather than how environmental factors benefit students. Specific recommendations for future ecological research are provided. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
997.
Placing metallic nanoparticles inside cavities, rather than in dimers, greatly improves their plasmonic response. Such particle-in-cavity (PIC) hybrid architectures are shown to produce extremely strong field enhancement at the particle-cavity junctions, arising from the cascaded focusing of large optical cross sections into small gaps. These simply constructed PIC structures produce the strongest field enhancement for coupled nanoparticles, up to 90% stronger than for a dimer. The coupling is found to follow a universal power law with particle-surface separation, both for field enhancements and resonant wavelength shifts. Significantly enhanced Raman signals are experimentally observed for molecules adsorbed in such PIC structures, in quantitive agreement with theoretical calculations. PIC architectures may have important implications in many applications, such as reliable single molecule sensing and light harvesting in plasmonic photovoltaic devices. 相似文献
998.
We report the results of uniaxial compressive tests on a DGEBA epoxy resin at room temperature, well below its glass transition. We first focus on the strength, defined as the stress value corresponding to either a maximum or a flattening of the stress-strain curve, which, for this polymer, may be taken to be coincident with the yield stress, as often assumed for many thermosets. Within the strain rate range (1.E?6 s?1, 2.E?3 s?1) we confirm the linear trend relating the logarithm of the strain rate to the yield stress, as already been observed by other investigators even for the same epoxy resin; instead, at strain rates below \(\dot{\varepsilon} _{0} \approx 1.\mathrm{E}{-}6~\mathrm{s}^{-1}\), we found a negligible rate-dependence, as our data indicate a lowest limit of the yield stress, of about 87 MPa. On the basis of these results, we propose how to extend to the viscoplastic regime of deformation a nonlinear viscoelastic model previously put forward.Secondarily, within the viscoelastic range, at a stress level significantly lower than the yield stress, our measurements show a mild volumetric instability, allowed by the free lateral expansion, not ascribable to any macroscopic structural effect; such a behaviour has never been reported in the literature, to the best of our knowledge. 相似文献
999.
Giuliana Aquilanti Andrea Cognigni M. Anis-ur-Rehman 《Journal of Superconductivity and Novel Magnetism》2011,24(1-2):659-663
Information on local crystal and electronic structure with elemental specificity is of paramount importance to understand many scientific problems. X-ray Absorption Spectroscopy (XAS) is particularly suited for this. Spinel structured ferrites exhibit a range of electrical and magnetic properties that make them particularly appealing for many technological applications such as permanent magnets, microwave absorbers, catalysts, and chemical sensors. Since the peculiar properties of ferrites are strictly related to the distribution of cations between octahedral and tetrahedral sites in the spinel structure, the control of cation distribution provides a means to tailor their properties. An EXAFS study of Co x Zn1?x Fe2O4 nanoparticles is presented here. Using this technique, the information about the site distribution for Fe and Co/Zn is determined. The information obtained on the cation distribution is important to understand the microstructure of spinel ferrites which is useful to study their effects on structural, electrical, and magnetic properties. 相似文献
1000.
Andrea Centrone Erik E. Santiso T. Alan Hatton 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(16):2356-2364
HPLC columns custom‐packed with metal–organic framework (MOF) materials are used for the separation of four small intermediates and byproducts found in the commercial synthesis of an important active pharmaceutical ingredient in methanol. In particular, two closely related amines can be separated in the methanol reaction medium using MOFs, but not with traditional C18 columns using an optimized aqueous mobile phase. Infrared spectroscopy, UV–vis spectroscopy, X‐ray diffraction, and thermogravimetric analysis are used in combination with molecular dynamic simulations to study the separation mechanism for the best‐performing MOF materials. It is found that separation with ZIF‐8 is the result of an interplay between the thermodynamic driving force for solute adsorption within the framework pores and the kinetics of solute diffusion into the material pores, while the separation with Basolite F300 is achieved because of the specific interactions between the solutes and Fe3+ sites. This work, and the exceptional ability to tailor the porous properties of MOF materials, points to prospects for using MOF materials for the continuous separation and synthesis of pharmaceutical compounds. 相似文献