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Volumn 1-2, Issue , 2003, Pages 369-390

Pyrolysis of Active and Passive Filler-loaded Preceramic Polymers

Author keywords

[No Author keywords available]

Indexed keywords

CERAMIC MATERIALS; CERAMIC PRODUCTS; FILLED POLYMERS; HYBRID MATERIALS; MACHINERY; MANUFACTURE; POLYMERS; PYROLYSIS;

EID: 7544236145     PISSN: None     EISSN: None     Source Type: Book    
DOI: 10.1016/B978-012654640-8/50008-0     Document Type: Chapter
Times cited : (10)

References (65)
  • 1
    • 0020806841 scopus 로고
    • Siloxanes, silanes, and silazanes in the preparation of ceramics and glasses
    • Wills R.R., Markle R.A., Mukherjee S.P. Siloxanes, silanes, and silazanes in the preparation of ceramics and glasses. Bull. Am. Ceram. Soc. 1983, 62:904.
    • (1983) Bull. Am. Ceram. Soc. , vol.62 , pp. 904
    • Wills, R.R.1    Markle, R.A.2    Mukherjee, S.P.3
  • 3
    • 0024926972 scopus 로고
    • Metallorganic compounds as preceramic materials I. Non-oxide ceramics. Part II. Oxide ceramics
    • Pouskouleli G. Metallorganic compounds as preceramic materials I. Non-oxide ceramics. Part II. Oxide ceramics. Ceram. Int. 1989, 15:213.
    • (1989) Ceram. Int. , vol.15 , pp. 213
    • Pouskouleli, G.1
  • 4
    • 0024921422 scopus 로고
    • Metallorganic compounds as preceramic materials I. Non-oxide ceramics. Part II. Oxide ceramics
    • Pouskouleli G. Metallorganic compounds as preceramic materials I. Non-oxide ceramics. Part II. Oxide ceramics. Ceram. Int. 1989, 15:255.
    • (1989) Ceram. Int. , vol.15 , pp. 255
    • Pouskouleli, G.1
  • 5
    • 0342680538 scopus 로고
    • Derivatization to preformed polymers to produce ceramic precursors
    • Maya L. Derivatization to preformed polymers to produce ceramic precursors. J. Am. Ceram. Soc. 1990, 73:2714.
    • (1990) J. Am. Ceram. Soc. , vol.73 , pp. 2714
    • Maya, L.1
  • 7
    • 0029376096 scopus 로고
    • Precursor-derived covalent ceramics
    • Bill J., Aldinger F. Precursor-derived covalent ceramics. Adv. Mater. 1995, 7:775.
    • (1995) Adv. Mater. , vol.7 , pp. 775
    • Bill, J.1    Aldinger, F.2
  • 8
    • 0034678892 scopus 로고    scopus 로고
    • Ceramics and nanostructures from molecular precursors
    • Corriu R.J. Ceramics and nanostructures from molecular precursors. Angew. Chem. Ind. Ed. 2000, 39:1376.
    • (2000) Angew. Chem. Ind. Ed. , vol.39 , pp. 1376
    • Corriu, R.J.1
  • 9
    • 0025479420 scopus 로고
    • Structural evolutions from polycarbosilane to SiC ceramics
    • Soraru G.D., Babonneau F., Mackenzie J.D. Structural evolutions from polycarbosilane to SiC ceramics. J. Mater. Sci. 1990, 25:3866.
    • (1990) J. Mater. Sci. , vol.25 , pp. 3866
    • Soraru, G.D.1    Babonneau, F.2    Mackenzie, J.D.3
  • 10
    • 0001219355 scopus 로고    scopus 로고
    • Thermal behavior of (organosilicon) polymer derived ceramics. V: Main facts and trends
    • Monthioux M., Delverdier O. Thermal behavior of (organosilicon) polymer derived ceramics. V: Main facts and trends. J. Eur. Ceram. Soc. 1996, 16:721.
    • (1996) J. Eur. Ceram. Soc. , vol.16 , pp. 721
    • Monthioux, M.1    Delverdier, O.2
  • 12
    • 0039084022 scopus 로고
    • A novel processing route for alumina/SiC-Nanocomposites by Si-polymer pyrolysis
    • Gruppo Editiorale Faenca Editirice, Faneza/I, A. Bellosi (Ed.)
    • Su B., Sternitzke M. A novel processing route for alumina/SiC-Nanocomposites by Si-polymer pyrolysis. Fourth Euro Ceramics 1995, Vol. 4:109. Gruppo Editiorale Faenca Editirice, Faneza/I. A. Bellosi (Ed.).
    • (1995) Fourth Euro Ceramics , vol.4 , pp. 109
    • Su, B.1    Sternitzke, M.2
  • 13
    • 0038542378 scopus 로고
    • Silicon carbide preceramic polymers as binders for ceramic powders
    • Kluwer, Dordrecht, J.F. Harrod, R.M. Laine (Eds.)
    • Atwell W.H., Burns G.T., Zank G.A. Silicon carbide preceramic polymers as binders for ceramic powders. Inorganic and Organometallic Oligomers and Polymers 1991, 147. Kluwer, Dordrecht. J.F. Harrod, R.M. Laine (Eds.).
    • (1991) Inorganic and Organometallic Oligomers and Polymers , pp. 147
    • Atwell, W.H.1    Burns, G.T.2    Zank, G.A.3
  • 14
    • 0002795929 scopus 로고
    • Application of preceramic polymers in powder metallurgy: their use as low-loss binders and for the in situ formation of dispersed ceramic phases in the metal matrix
    • Seyferth S., Czubarow P. Application of preceramic polymers in powder metallurgy: their use as low-loss binders and for the in situ formation of dispersed ceramic phases in the metal matrix. Chem. Mater. 1994, 6:10.
    • (1994) Chem. Mater. , vol.6 , pp. 10
    • Seyferth, S.1    Czubarow, P.2
  • 15
    • 0020805838 scopus 로고
    • Preparation and properties of monolithic and composite ceramics produced by polymer pyrolysis
    • Walker B.E., Rice R.W., Becher P.F., Bender B.A., Coblenz W.S. Preparation and properties of monolithic and composite ceramics produced by polymer pyrolysis. Bull. Am. Ceram. Soc. 1983, 62:916.
    • (1983) Bull. Am. Ceram. Soc. , vol.62 , pp. 916
    • Walker, B.E.1    Rice, R.W.2    Becher, P.F.3    Bender, B.A.4    Coblenz, W.S.5
  • 16
    • 0026822033 scopus 로고
    • Synthesis of dense silicon-based ceramics at low temperatures
    • Riedel R., Passing G., Schönfelder H., Brook R.J. Synthesis of dense silicon-based ceramics at low temperatures. Nature 1992, 355:355.
    • (1992) Nature , vol.355 , pp. 355
    • Riedel, R.1    Passing, G.2    Schönfelder, H.3    Brook, R.J.4
  • 17
    • 0029222490 scopus 로고
    • Polymer-derived Si-based bulk ceramics. Part I: Preparation processing and properties
    • Riedel R., Seher M., Mayer J., Szabo D.V. Polymer-derived Si-based bulk ceramics. Part I: Preparation processing and properties. J. Eur. Ceram. Soc. 1995, 15:703.
    • (1995) J. Eur. Ceram. Soc. , vol.15 , pp. 703
    • Riedel, R.1    Seher, M.2    Mayer, J.3    Szabo, D.V.4
  • 18
    • 0030109855 scopus 로고    scopus 로고
    • Production of compact polysilazane-derived Si/C/N-ceramics by plastic forming
    • Seitz J., Bill J. Production of compact polysilazane-derived Si/C/N-ceramics by plastic forming. J. Mater. Sci. Lett. 1996, 15:391.
    • (1996) J. Mater. Sci. Lett. , vol.15 , pp. 391
    • Seitz, J.1    Bill, J.2
  • 19
    • 84985113629 scopus 로고
    • Inorganic fibers-a literature review
    • Cooke T.F. Inorganic fibers-a literature review. J. Am. Ceram. Soc. 1991, 74:2959.
    • (1991) J. Am. Ceram. Soc. , vol.74 , pp. 2959
    • Cooke, T.F.1
  • 20
    • 0001352699 scopus 로고
    • Polymer-derived ceramic fibers
    • Lipowitz J. Polymer-derived ceramic fibers. Bull. Am. Ceram. Soc. 1991, 70:1888.
    • (1991) Bull. Am. Ceram. Soc. , vol.70 , pp. 1888
    • Lipowitz, J.1
  • 21
    • 0031237946 scopus 로고    scopus 로고
    • Synthesis of silicon carbide thin films with polycarbosilane (PCS)
    • Colombo P., Paulson T.E., Pantano C.G. Synthesis of silicon carbide thin films with polycarbosilane (PCS). J. Am. Ceram. Soc. 1997, 80:2333.
    • (1997) J. Am. Ceram. Soc. , vol.80 , pp. 2333
    • Colombo, P.1    Paulson, T.E.2    Pantano, C.G.3
  • 22
    • 0032630890 scopus 로고    scopus 로고
    • Silicon oxycarbide ceramic foams from a preceramic polymer
    • Colombo P., Modesti M. Silicon oxycarbide ceramic foams from a preceramic polymer. J. Am. Ceram. Soc. 1999, 82:573.
    • (1999) J. Am. Ceram. Soc. , vol.82 , pp. 573
    • Colombo, P.1    Modesti, M.2
  • 23
    • 0025489534 scopus 로고
    • Structural ceramics derived from a preceramic polymer
    • Semen J., Loop J.G. Structural ceramics derived from a preceramic polymer. Ceram. Eng. Sci. Proc. 1990, 11:1387.
    • (1990) Ceram. Eng. Sci. Proc. , vol.11 , pp. 1387
    • Semen, J.1    Loop, J.G.2
  • 25
    • 0009820989 scopus 로고
    • Preparation of carbon fiber reinforced composite by impregnation with perhydropolysilazane followed by pressureless firing
    • Sato K., Suzuki T., Funayama O., Isoda T., Itoh T. Preparation of carbon fiber reinforced composite by impregnation with perhydropolysilazane followed by pressureless firing. Ceram. Eng. Sci. Proc. 1992, 13:614.
    • (1992) Ceram. Eng. Sci. Proc. , vol.13 , pp. 614
    • Sato, K.1    Suzuki, T.2    Funayama, O.3    Isoda, T.4    Itoh, T.5
  • 28
  • 29
    • 0027206692 scopus 로고
    • 4C and stochiometric SiC from mixtures of a vinylic polysilane and metal powders
    • 4C and stochiometric SiC from mixtures of a vinylic polysilane and metal powders. Mater. Res. Soc. Symp. Proc. 1993, 286:437.
    • (1993) Mater. Res. Soc. Symp. Proc. , vol.286 , pp. 437
    • Jiang, Z.1    Rhine, W.E.2
  • 31
    • 0029293070 scopus 로고
    • Active-filler-controlled pyrolysis of preceramic polymers
    • Greil P. Active-filler-controlled pyrolysis of preceramic polymers. J. Am. Ceram. Soc. 1995, 78:835.
    • (1995) J. Am. Ceram. Soc. , vol.78 , pp. 835
    • Greil, P.1
  • 32
    • 0029341152 scopus 로고
    • Pyrolysis of titanium-metal-filled poly(siloxane) preceramic polymers: effect of atmosphere on pyrolysis product chemistry
    • Yu S.H., Riman R.E., Danforth S.C., Leung R.Y. Pyrolysis of titanium-metal-filled poly(siloxane) preceramic polymers: effect of atmosphere on pyrolysis product chemistry. J. Am. Ceram. Soc. 1995, 78:1818.
    • (1995) J. Am. Ceram. Soc. , vol.78 , pp. 1818
    • Yu, S.H.1    Riman, R.E.2    Danforth, S.C.3    Leung, R.Y.4
  • 33
    • 0029673724 scopus 로고    scopus 로고
    • Injection moulding of polysiloxane/filler mixtures for oxycarbide ceramic composites
    • Walter S., Suttor D., Erny T., Hahn B., Greil P. Injection moulding of polysiloxane/filler mixtures for oxycarbide ceramic composites. J. Eur. Ceram. Soc. 1996, 16:387.
    • (1996) J. Eur. Ceram. Soc. , vol.16 , pp. 387
    • Walter, S.1    Suttor, D.2    Erny, T.3    Hahn, B.4    Greil, P.5
  • 34
    • 0029373463 scopus 로고    scopus 로고
    • Ceramic materices and monoliths synthesized from a combination of reactive polymers, fillers and atmospheres
    • Lighfoot A., Haggerty J.S., Rhine W.E. Ceramic materices and monoliths synthesized from a combination of reactive polymers, fillers and atmospheres. Ceram. Eng. Sci. Proc. 1996, 17:653.
    • (1996) Ceram. Eng. Sci. Proc. , vol.17 , pp. 653
    • Lighfoot, A.1    Haggerty, J.S.2    Rhine, W.E.3
  • 36
    • 0034344340 scopus 로고    scopus 로고
    • Polymer derived engineering ceramics
    • Greil P. Polymer derived engineering ceramics. Adv. Eng. Ceram. 2000, 2:339.
    • (2000) Adv. Eng. Ceram. , vol.2 , pp. 339
    • Greil, P.1
  • 37
    • 11944251509 scopus 로고
    • Ceramics from organometallic polymers
    • Peuckert M., Vaahs T., Brück M. Ceramics from organometallic polymers. Adv. Mater. 1990, 2:398.
    • (1990) Adv. Mater. , vol.2 , pp. 398
    • Peuckert, M.1    Vaahs, T.2    Brück, M.3
  • 39
    • 0000821145 scopus 로고
    • Production mechanism of polytitano carbosilane and its conversion of the polymer into inorganic materials
    • Ishikawa T., Yamamura T., Okamura K. Production mechanism of polytitano carbosilane and its conversion of the polymer into inorganic materials. J. Mater. Sci. 1992, 27:6627.
    • (1992) J. Mater. Sci. , vol.27 , pp. 6627
    • Ishikawa, T.1    Yamamura, T.2    Okamura, K.3
  • 40
    • 0030902170 scopus 로고    scopus 로고
    • Novel High Performance Ceramics-amorphous inorganic networks from molecular precursors
    • Baldus H.P., Jansen K. Novel High Performance Ceramics-amorphous inorganic networks from molecular precursors. Angew. Chem. Int. Ed. 1997, 36:328.
    • (1997) Angew. Chem. Int. Ed. , vol.36 , pp. 328
    • Baldus, H.P.1    Jansen, K.2
  • 41
    • 0001916524 scopus 로고    scopus 로고
    • Molecular precursor routes to inorganic solids
    • Wiley-VCH, New York, L.V. Interrante, M.J. Hamden-Smith (Eds.)
    • Livage J., Sanchez C., Babonneau F. Molecular precursor routes to inorganic solids. Chemistry of Advanced Materials 1998, 48. Wiley-VCH, New York. L.V. Interrante, M.J. Hamden-Smith (Eds.).
    • (1998) Chemistry of Advanced Materials , pp. 48
    • Livage, J.1    Sanchez, C.2    Babonneau, F.3
  • 43
    • 0001622016 scopus 로고
    • Synthesis of advanced ceramics in the system Si-B-N and Si-B-N-C employing novel precursor compounds
    • Baldus H.P., Wagner O., Jansen M. Synthesis of advanced ceramics in the system Si-B-N and Si-B-N-C employing novel precursor compounds. Mater. Res. Soc. Symp. Proc. 1992, 271:821.
    • (1992) Mater. Res. Soc. Symp. Proc. , vol.271 , pp. 821
    • Baldus, H.P.1    Wagner, O.2    Jansen, M.3
  • 44
    • 0034498468 scopus 로고    scopus 로고
    • High-temperature mechanical properties of Si-B-C-N-precursor-derived amorphous ceramics and the applicability of deformation models developed for metallic glasses
    • Christ M., Thurn G., Weinmann M., Bill J., Aldinger F. High-temperature mechanical properties of Si-B-C-N-precursor-derived amorphous ceramics and the applicability of deformation models developed for metallic glasses. J. Am. Ceram. Soc. 2000, 83:3025.
    • (2000) J. Am. Ceram. Soc. , vol.83 , pp. 3025
    • Christ, M.1    Thurn, G.2    Weinmann, M.3    Bill, J.4    Aldinger, F.5
  • 45
    • 0000305701 scopus 로고
    • Silicon oxycarbide glasses. Part I. Preparation and Chemistry; Part II. Structure and properties
    • Renlund G.R., Prochazka S., Doremus R.H. Silicon oxycarbide glasses. Part I. Preparation and Chemistry; Part II. Structure and properties. J. Mater. Res. 1991, 6:2716.
    • (1991) J. Mater. Res. , vol.6 , pp. 2716
    • Renlund, G.R.1    Prochazka, S.2    Doremus, R.H.3
  • 46
    • 0000305701 scopus 로고
    • Silicon oxycarbide glasses. Part I. Preparation and Chemistry; Part II. Structure and properties
    • Renlund G.R., Prochazka S., Doremus R.H. Silicon oxycarbide glasses. Part I. Preparation and Chemistry; Part II. Structure and properties. J. Mater. Res. 1991, 6:2723.
    • (1991) J. Mater. Res. , vol.6 , pp. 2723
    • Renlund, G.R.1    Prochazka, S.2    Doremus, R.H.3
  • 47
    • 0000670187 scopus 로고
    • Modelling of dimensional changes during polymer-ceramic conversion for bulk component fabrication
    • Greil P., Seibold M. Modelling of dimensional changes during polymer-ceramic conversion for bulk component fabrication. J. Mater. Sci. 1992, 27:1053.
    • (1992) J. Mater. Sci. , vol.27 , pp. 1053
    • Greil, P.1    Seibold, M.2
  • 48
    • 0001361287 scopus 로고    scopus 로고
    • Near net shape manufacturing of polymer derived ceramics
    • Greil P. Near net shape manufacturing of polymer derived ceramics. J. Eur. Ceram. Soc. 1998, 18:1905.
    • (1998) J. Eur. Ceram. Soc. , vol.18 , pp. 1905
    • Greil, P.1
  • 49
    • 34548168627 scopus 로고    scopus 로고
    • Pyrolysis of polycarbosilane/nano-cobalt particles
    • Wang J., Song Y., Feng C. Pyrolysis of polycarbosilane/nano-cobalt particles. Ailiao Kexue Yu Gongcheng 1998, 16:69.
    • (1998) Ailiao Kexue Yu Gongcheng , vol.16 , pp. 69
    • Wang, J.1    Song, Y.2    Feng, C.3
  • 50
    • 0039540115 scopus 로고
    • Aluminium powder-preceramic polymer mixtures for the preparation of ceramic composites
    • Gruppo Editiorale Faenza Editirice, Faneza/I, A. Bellosi (Ed.)
    • Colombo P., Abdirashid M.O., Maddalena A., Marchetti A. Aluminium powder-preceramic polymer mixtures for the preparation of ceramic composites. Fourth Euro Ceramics 1995, Vol. 4:117. Gruppo Editiorale Faenza Editirice, Faneza/I. A. Bellosi (Ed.).
    • (1995) Fourth Euro Ceramics , vol.4 , pp. 117
    • Colombo, P.1    Abdirashid, M.O.2    Maddalena, A.3    Marchetti, A.4
  • 51
    • 0027224627 scopus 로고
    • Microstructure development of oxycarbide composites during active-filler-controlled polymer pyrolysis
    • Erny T., Seibold M., Jarchow O., Greil P. Microstructure development of oxycarbide composites during active-filler-controlled polymer pyrolysis. J. Am. Ceram. Soc. 1993, 76:207.
    • (1993) J. Am. Ceram. Soc. , vol.76 , pp. 207
    • Erny, T.1    Seibold, M.2    Jarchow, O.3    Greil, P.4
  • 52
    • 0027224512 scopus 로고
    • Thermodynamics and microstructural development of ceramic composite formation by active-filler-controlled pyrolysis (AFCOP)
    • Seibold M., Greil P. Thermodynamics and microstructural development of ceramic composite formation by active-filler-controlled pyrolysis (AFCOP). J. Eur. Ceram. Soc. 1993, 11:105.
    • (1993) J. Eur. Ceram. Soc. , vol.11 , pp. 105
    • Seibold, M.1    Greil, P.2
  • 53
    • 0031189206 scopus 로고    scopus 로고
    • Fiber-reinforced ceramic-matrix composites with a polysiloxane/boron-derived matrix
    • Suttor D., Erny T., Greil P., Goedecke H., Haug T. Fiber-reinforced ceramic-matrix composites with a polysiloxane/boron-derived matrix. J. Am. Ceram. Soc. 1997, 80:1831.
    • (1997) J. Am. Ceram. Soc. , vol.80 , pp. 1831
    • Suttor, D.1    Erny, T.2    Greil, P.3    Goedecke, H.4    Haug, T.5
  • 54
    • 84977694484 scopus 로고
    • Proposed fracture theory of a dispersion strengthened glass matrix
    • Hasselman D.P.H., Fulrath R.M. Proposed fracture theory of a dispersion strengthened glass matrix. J. Am. Ceram. Soc. 1966, 49:68.
    • (1966) J. Am. Ceram. Soc. , vol.49 , pp. 68
    • Hasselman, D.P.H.1    Fulrath, R.M.2
  • 55
    • 0013130290 scopus 로고    scopus 로고
    • Microstructure and mechanical properties of polymer derived oxycarbide ceramics
    • (in German), University of Erlangen-Nuernberg, Germany
    • Walter S. Microstructure and mechanical properties of polymer derived oxycarbide ceramics. PhD thesis 1999, (in German), University of Erlangen-Nuernberg, Germany.
    • (1999) PhD thesis
    • Walter, S.1
  • 56
    • 84943392770 scopus 로고
    • Silicon-oxycarbide glasses
    • Rensselaer Polytechnic Institute, NY
    • Renlund G.M. Silicon-oxycarbide glasses. PhD thesis 1989, Rensselaer Polytechnic Institute, NY.
    • (1989) PhD thesis
    • Renlund, G.M.1
  • 57
    • 0034325480 scopus 로고    scopus 로고
    • Electrical conductivity measurements as a Microprobe for structure transitions in polysiloxane derived Si-O-C ceramics
    • Cordelair J., Greil P. Electrical conductivity measurements as a Microprobe for structure transitions in polysiloxane derived Si-O-C ceramics. J. Eur. Ceram. Soc. 2000, 20:1947.
    • (2000) J. Eur. Ceram. Soc. , vol.20 , pp. 1947
    • Cordelair, J.1    Greil, P.2
  • 59
    • 0027147275 scopus 로고
    • Models proposed to explain the electrical conductivity of mixtures made of conductive and insulating materials
    • Lux F. Models proposed to explain the electrical conductivity of mixtures made of conductive and insulating materials. J. Mater. Sci. 1993, 28:285.
    • (1993) J. Mater. Sci. , vol.28 , pp. 285
    • Lux, F.1
  • 60
    • 84943387760 scopus 로고
    • Electrical conductivity of composites: a percolation approach
    • 1992
    • De Bondt A., Froyen L., Deruyettere A. Electrical conductivity of composites: a percolation approach. J. Mater. Sci. 1983, 27. 1992.
    • (1983) J. Mater. Sci. , vol.27
    • De Bondt, A.1    Froyen, L.2    Deruyettere, A.3
  • 62
    • 0013125698 scopus 로고    scopus 로고
    • Electrical properties of polymer filler-derived ceramics
    • (in German), University of Erlangen-Nuernberg, Germany
    • Cordelair J. Electrical properties of polymer filler-derived ceramics. PhD thesis 1999, (in German), University of Erlangen-Nuernberg, Germany.
    • (1999) PhD thesis
    • Cordelair, J.1
  • 63
    • 85032536562 scopus 로고    scopus 로고
    • Oxidation protection systems for porous ceramics
    • (in German), University of Erlangen-Nuernberg, Germany
    • Mueller C. Oxidation protection systems for porous ceramics. PhD thesis 1998, (in German), University of Erlangen-Nuernberg, Germany.
    • (1998) PhD thesis
    • Mueller, C.1
  • 64
    • 84985164592 scopus 로고
    • Interpenetrating phase composites
    • Clarke D.R. Interpenetrating phase composites. J. Am. Ceram. Soc. 1992, 75:739.
    • (1992) J. Am. Ceram. Soc. , vol.75 , pp. 739
    • Clarke, D.R.1
  • 65
    • 0029360210 scopus 로고
    • Silicon carbide from laser pyrolysis of polycarbosilane
    • Jacubenas K., Marcus H.L. Silicon carbide from laser pyrolysis of polycarbosilane. J. Am. Ceram. Soc. 1995, 78:2263.
    • (1995) J. Am. Ceram. Soc. , vol.78 , pp. 2263
    • Jacubenas, K.1    Marcus, H.L.2


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