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Growth Approach (growth + approach)
Selected AbstractsFormation of Gold and Silver Nanoparticle Arrays and Thin Shells on Mesostructured Silica Nanofibers,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2007S. Zhang Abstract Mesostructured silica nanofibers synthesized in high yields with cetyltrimethylammonium bromide as the structure-directing agent in HBr solutions are used as templates for the assembly of Au and Ag nanoparticles and the formation of thin Au shells along the fiber axis. Presynthesized spherical Au and Ag nanoparticles are adsorbed in varying amounts onto the silica nanofibers through bifunctional linking molecules. Nonspherical Au nanoparticles with sharp tips are synthesized on the nanofibers through a seed-mediated growth approach. The number density of nonspherical Au nanoparticles is controlled by varying the amount of seeded nanofibers relative to the amount of supplied Au precursor. This seed-mediated growth is further used to form continuous Au shells around the silica nanofibers. Both the Au- and Ag-nanoparticle/silica-nanofiber hybrid nanostructures and silica/Au core/shell fibers exhibit extinction spectra that are distinct from the spectra of Au and Ag nanoparticles in solution, indicating the presence of new surface plasmon resonance modes in the silica/Au core/shell fibers and surface plasmon coupling between closely spaced metal nanoparticles assembled on silica nanofibers. Spherical Au- and Ag-nanoparticle/silica-nanofiber hybrid nanostructures are further used as substrates for surface-enhanced Raman spectroscopy, and the enhancement factors of the Raman signals obtained on the Ag-nanoparticle/silica-nanofiber hybrid nanostructures are 2,×,105 for 4-mercaptobenzoic acid and 4-mercaptophenol and 7,×,107 for rhodamine,B isothiocyanate. These hybrid nanostructures are therefore potentially useful for ultrasensitive chemical and biological sensing by using molecular vibrational signatures. [source] Synthesis of dendritic macromolecules through divergent iterative thio-bromo "Click" chemistry and SET-LRPJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2009Brad M. Rosen Abstract The development of a novel nucleophilic thio-bromo "Click" reaction, specifically base-mediated thioetherification of thioglycerol with ,-bromoesters was reported in an earlier article. The combination of this thio-bromo click reaction with subsequent acylation with 2-bromopropionyl bromide provides an iterative two-step divergent growth approach to the synthesis of a new class of poly(thioglycerol-2- propionate) (PTP) dendrimers. In this article, the addition of a third step, the single-electron transfer living radical polymerization (SET-LRP) of methyl acrylate (MA), was shown to provides access to a three-step "branch" and "grow" divergent approach to dendritic macromolecules wherein poly(methyl acrylate) (PMA) connects the branching subunits. This facile methodology can provide a diversity of dendritic macromolecular topologies and will ultimately provide the means to the development of self-organizable dendritic macromolecules. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3940,3948, 2009 [source] Is R&D investment in lagging areas of Europe worthwhile?PAPERS IN REGIONAL SCIENCE, Issue 3 2001Theory, empirical evidence R&D, technology; spillovers; economic growth; regions; Western Europe Abstract. Is R&D investment in lagging areas worthwhile? There is no simple answer, nor is there universal theoretical agreement on the question. The Schumpeterian strand of the endogenous growth approach highlights the advantages of spatially concentrating the research and development (R&D) effort in a few areas, in order to maximise external economies and technological spillovers. Innovation is then expected to spill over from these technologically advanced areas into neighbouring regions. The neoclassical view, in contrast, considers that decreasing returns render investment in core areas increasingly less efficient, and makes investment in peripheries more effective. The regional policy view holds that public investment in R&D in lagging regions triggers economic convergence, because it limits congestion in the centre, helps to keep talent, and generates spin-offs in lagging areas. This article surveys these strands and highlights the advantages and disadvantages of investing in R&D in lagging regions. I then turn to the evolution of R&D investment across regions in Western Europe. [source] Status versus growth: The distributional effects of school accountability policiesJOURNAL OF POLICY ANALYSIS AND MANAGEMENT, Issue 3 2010Helen F. Ladd Although the federal No Child Left Behind program judges the effectiveness of schools based on their students' achievement status, many policy analysts argue that schools should be measured, instead, by their students' achievement growth. Using a 10-year student-level panel data set from North Carolina, we examine how school-specific pressure associated with status and growth approaches to school accountability affect student achievement at different points in the prior-year achievement distribution. Achievement gains for students below the proficiency cut point emerge in schools failing either type of accountability standard, with the effects clearer for math than for reading. In contrast to prior research highlighting the possibility of educational triage, we find little or no evidence that failing schools in North Carolina ignore the students far below proficiency under either approach. Importantly, we find that the status, but not the growth, approach reduces the reading achievement of higher performing students. Our analysis suggests that the distributional effects of accountability pressure depend not only on the type of pressure for which schools are held accountable (status or growth), but also the tested subject. © 2010 by the Association for Public Policy Analysis and Management. [source] Poetic Experience: Found or Made?ENGLISH IN EDUCATION, Issue 3 2002Andrew Stables Abstract This article considers the arguments for seeing work rather than response as key to poetic experience, and therefore to the development of such experience in the classroom. This is worth exploring not only in terms of the 1iterature/literacy curriculum, but with respect to the curriculum as a whole, since poetry is often invoked as an important, and under exploited, resource for the development of both cross-curricular learning and responsible and sustainable citizenship. However, there is a danger of the poetic being reduced in such arguments to a vague and philosophically suspect notion of self-expression grounded in ,response'. This can be exacerbated by the adherence to the notion of a pre-existing Romantic Ego that often characterises ,personal growth' approaches to Englis/language teaching. [source] | ||||||||||