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941.
Christian Heller Martin Schwentenwein Günter Russmüller Thomas Koch Doris Moser Christian Schopper Franz Varga Jürgen Stampfl Robert Liska 《Journal of polymer science. Part A, Polymer chemistry》2011,49(3):650-661
The last decade has seen a remarkable interest in the use of biocompatible and biodegradable polymers as scaffolds for tissue engineering. The fabrication of 3D scaffolds by lithography‐based additive manufacturing technology (AMT) represents an appealing approach. As poly(lactic acid), the state of the art biocompatible and biodegradable material, cannot be processed by these photopolymerization‐based techniques, it has so far been necessary to use selected (meth)acrylates. By developing new photopolymers based on vinyl carbonates and vinyl carbamates as a reactive group we have been able to avoid most of the disadvantages of classical (meth)acrylate‐based photopolymers. The new generation of biocompatible monomers show low cytotoxicity, have good storage stability, and are sufficiently photoreactive to be structured by lithography based AMT. The mechanical properties and rates of degradation of the polymers can be easily tuned over a broad range. Degradation results in the formation of nonacidic and nontoxic degradation products of low molecular weight that can be easily transported within the human body. Initial in vivo tests showed significant osseointegration of the 3D cellular scaffolds and no signs of implant rejection. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
942.
Béatrice Roy Isabelle LefebvreJean-Yves Puy Christian Périgaud 《Tetrahedron letters》2011,52(12):1250-1252
We report on the first solution synthesis of lamivudine 5′-diphosphate in both high yield and purity. Efficient synthesis of lamivudine 5′-monophosphate was obtained through lamivudine H-phosphonate oxidation by (−)-(8,8-dichlorocamphorylsulfonyl)oxaziridine.Diphosphorylation was performed by nucleophilic substitution of the phosphorimidazolate derivative of lamivudine. HPLC coupled with UV or MS detection was found to be an invaluable tool for the follow-up of phosphorylation reactions. 相似文献
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947.
Recently a curvature theory for polyhedral surfaces has been established, which associates with each face a mean curvature
value computed from areas and mixed areas of that face and its corresponding Gauss image face. Therefore a study of minimal
surfaces requires studying pairs of polygons with vanishing mixed area. We show that the mixed area of two edgewise parallel
polygons equals the mixed area of a derived polygon pair which has only the half number of vertices. Thus we are able to recursively
characterize vanishing mixed area for hexagons and other n-gons in an incidence-geometric way. We use these geometric results for the construction of discrete minimal surfaces and
a study of equilibrium forces in their edges, especially those with the combinatorics of a hexagonal mesh. 相似文献
948.
Y. Hu M. Nareen A. Humphries P. Christian 《Journal of Sol-Gel Science and Technology》2010,53(2):300-306
We report a new method for preparing porous silica beads using a high internal phase emulsion (HIPE) sol–gel templating method.
The method uses a silica sol based HIPE and does not rely on a polymeric support to produce the final structure. As a result
beads may be formed readily in large numbers. The beads have an open porous structure commensurate with the formation of a
HIPE precursor phase. We also describe how the rheology of the HIPE reflects the formation of an open porous structure and
how the viscosity of the HIPE can affect the shape of the beads and how HIPE destabilization may be used to vary the pore
size. 相似文献
949.
Uwe Klingebiel Stefan Schmatz Eike Gellermann Christian Drost Mathias Noltemeyer 《Monatshefte für Chemie / Chemical Monthly》2001,40(5):1105-1124
This review describes the synthesis and isomerization reactions of cyclic silylhydrazines. Topics of discussion are the ring
expansion of the three-membered Si(SiN2) to the four-membered (SiN)2 ring by lithiation of the (SiN2) ring and by thermal silyl group insertion into the N*N bond, the ring expansion of a three-membered (SiN2) to a five-membered (CSi2N2) ring by SiCH2 insertion into the Si*N bond, the formation of isomeric four- and six-membered (SiN2)2 rings, the synthesis of five- and six-membered silylhydrazine rings, and the expansion of a five-membered (N2Si2N)N ring to the isomeric six-membered (SiNN)2 ring. The mechanisms of the isomerizations are explained by quantum chemical calculations, and the results are verified by
crystal structure determinations. 相似文献