95 research outputs found

    Variation in structure and properties of poly(glycerol adipate) via control of chain branching during enzymatic synthesis

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    Poly (glycerol adipate) (PGA) can be produced from divinyl adipate and unprotected glycerol by an enzymatic route to generate a polymer with relatively low molar mass (12 kDa). PGA bears a pendant hydroxyl group which imparts a hydrophilic character to this water insoluble polymer. We have examined the effect of synthesis temperature on polymer characteristics through various techniques including FT-IR, 1H and 13C NMR, surface and thermal analysis, both to expand the data already present in the literature about this material and to understand better its properties for potential pharmaceutical applications. The use of a lipase (Novozym 435) as a catalyst suppresses cross-linking at the pendant glyceryl hydroxyl through steric hindrance at the active site, thus producing polymers with low degrees of branching (5–30%), and removes the need for any pre- or post-polymerization protection/deprotection reactions. Careful temperature control during synthesis can give polymers with reproducible molecular weights and reduced amounts of polymer branching compared to synthesis at higher temperatures. Due to the ability of the synthetic route to produce a range of structures, PGA generated by enzymatic routes may emerge as a useful biodegradable polymer platform to engineer solid dispersions or nanoparticles for healthcare applications

    Just a guy in pajamas? Framing the blogs in mainstream US newspaper coverage (1999—2005)

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    When new technologies are introduced to the public, their widespread adoption is dependent, in part, on news coverage (Rogers, 1995).Yet, as weblogs began to play major role in the public spheres of politics and journalism, journalists faced a paradox: how to cover a social phenomenon that was too large to ignore and posed a significant threat to their profession. This article examines how blogs were framed by US newspapers as the public became more aware of the blogging world. A content analysis of blog-related stories in major US newspapers from 1999 to 2005 was conducted. Findings suggest that newspaper coverage framed blogs as more beneficial to individuals and small cohorts than to larger social entities such as politics, business and journalism. Moreover, only in the realm of journalism were blogs framed as more of a threat than a benefit, and rarely were blogs considered an actual form of journalism.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    local buzz, global pipelines and the process of knowledge creation

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    The version of record [Bathelt, H., Malmberg, A., & Maskell, P. (2004). Clusters and knowledge: Local buzz, global pipelines and the process of knowledge creation. Progress in Human Geography, 28(1), 31-56.] is available online at: http://phg.sagepub.com/content/28/1/31 [doi: 10.1191/0309132504ph469oa]The paper is concerned with spatial clustering of economic activity and its relation to the spatiality of knowledge creation in interactive learning processes. It questions the view that tacit knowledge transfer is confined to local milieus whereas codified knowledge may roam the globe almost frictionlessly. The paper highlights the conditions under which both tacit and codified knowledge can be exchanged locally and globally. A distinction is made between, on the one hand, the learning processes taking place among actors embedded in a community by just being there dubbed buzz and, on the other, the knowledge attained by investing in building channels of communication called pipelines to selected providers located outside the local milieu. It is argued that the co-existence of high levels of buzz and many pipelines may provide firms located in outward-looking and lively clusters with a string of particular advantages not available to outsiders. Finally, some policy implications, stemming from this argument, are identified

    ADJUSTMENTS IN A FARM BUSINESS IN RESPONSE TO AN ENERGY CRISIS

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    Effects of the 1973 price increases by the Organization of Petroleum Exporting Countries (OPEC) and the boycott placed on the United States by the OPEC's Arab members awakened Americans to the reality that the U.S. depends on imported petroleum to maintain the present level of energy consumption. Awareness of this domestic energy gap has raised serious questions about the possible impacts of energy crisis conditions on U.S. agricultural production. Agricultural production in the U.S. depends on petroleum products not only for the liquid fuels used by farm machinery, but also for the manufacture of pesticides and nitrogen fertilizer

    Extraperitoneal Video-Assisted Approach to the Abdominal Aorta

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    Estimated Values of Carbon Sequestration Resulting from Forest Management Scenarios

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    Chapter 3 of "The Valuation of Ecosystem Services from Farms and Forests: Informing a systematic approach to quantifying benefits of conservation programs.
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