ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and ultrastructural studies of styrene-divinylbenzene Polyhipe polymersP. Hainey, I. M. Huxham, B. Rowatt, D. C. Sherrington, and L. TetleyCite this: Macromolecules 1991, 24, 1, 117–121Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/ma00001a019https://doi.org/10.1021/ma00001a019research-articleACS PublicationsRequest reuse permissionsArticle Views1776Altmetric-Citations176LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Kraton D1101 and D1102, poly(styrene)–poly(butadiene)–poly(styrene)(PS–PBD–PS), and Kraton G1651, poly(styrene)–poly(hydrogenated butadiene)–poly(styrene)(PS-HPBD-PS) block copolymers have been chemically modified in high conversion to yield novel linear soluble block-copolymer materials. Specifically the PS block in G1651 has been nitrated, and the PBD block in D1101 has been brominated and chlorosulfenylated. The species from the latter modification have also been oxidised quantitatively to yield block copolymers with pendant aromatic sulfone substituents. Transmission electron microscopy has shown that in the solid state the new materials retain the microphase-separated structure of the parent block copolymers, although the precise morphology changes. The latter is discussed in the light of current thinking in the literature. Glass-transition and thermal-decomposition data have also been obtained for the new materials.
Abstract The genes encoding murine macrophage migration inhibitory factor (MIF), IL-2, IFN-γ or TNF-α were cloned individually into an expression plasmid under the control of the inducible promoter nirB and transfected into the aroA−aroD− deletion mutant strain of Salmonella typhimurium (BRD509). These S. typhimurium derivatives (henceforward called constructs and termed GIDMIF, GIDIL2, GIDIFN and GIDTNF) expressed their respective cytokines in vitro under anaerobic conditions and stably colonized BALB/c mice up to 14 days after oral administration. The highly susceptible BALB/c mice that had received the constructs orally and that had been subsequently infected via the footpad with Leishmania major, developed significantly reduced disease compared with control mice administered the untransfected Salmonella strain (BRD509). Importantly, a combination of GIDMIF, GIDIFN, and GIDTNF administered orally after L. major infection was able to significantly limit lesion development and reduced parasite loads by up to three orders of magnitude. Spleen and lymph node cells of mice administered this combination expressed markedly higher levels of inducible nitric oxide synthase (iNOS) compared with those from mice receiving an equivalent dose of the control strain of Salmonella (BRD509). These data therefore demonstrate the feasibility of therapeutic treatment in an infectious disease model using cytokines delivered by attenuated Salmonella. The protective effect observed correlates with the induction of inducible nitric oxide synthase in vivo.
SUMMARY We describe the microscopical analysis of two polystyrene divinylbenzene copolymers (PS‐DVB) made using 20 and 55% (v/v) DVB cross‐linker respectively, in which the hydrated structure of each polymeric material solvated in water is preserved by employing very rapid freezing and low‐temperature freeze‐drying techniques. Using the zero‐loss mode of electron spectroscopic imaging to enhance the contrast of unstained polymer sections, we introduce some novel methods for the application of computer‐assisted image analysis for routine examination of polymer pore structure. We also relate these parameters to the ability of the two polymers to absorb nanometre‐sized particles—neutral colloidal gold particles and cationized ferritin. Both methods will be invaluable in the structural analysis of porous polymers, but particularly for comparative analyses of macroporous sorbents.
The porosity characteristics of a series of 12 macroporous poly(styrene–divinylbenzene) resins have been quantified by the mercury intrusion method and by image analysis of transmission electron micrographs (TEM) of resin particle cross-sections. The results from both methods correlate extremely well. Bearing in mind that the TEM procedure does 'observe' pores more directly than the Hg intrusion method, the present study tends to validate the intrusion procedure and calculations.
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