The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Yu Qiao - One of the best experts on this subject based on the ideXlab platform.
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formation of Anhydro Sugars in the primary volatiles and solid residues from cellulose fast pyrolysis in a wire mesh reactor
Energy & Fuels, 2014Co-Authors: Xun Gong, Yu Qiao, Yun Yu, Minghou Xu, Hongwei WuAbstract:The unique design of wire-mesh reactors (WMR) enables the collection of primary volatiles with minimized secondary reactions from fast pyrolysis of solid fuels. This paper reports the formation of Anhydro-Sugars in both primary volatiles and solid residues from the fast pyrolysis of microcrystalline cellulose in a WMR. Under fast pyrolysis, cellulose is rapidly converted into an intermediate phase, and the maximal yield of the water-soluble intermediates achieved in this study is ∼21% on a carbon basis at 450 °C, much higher than those achieved in other pyrolysis reactor systems. The solid residue consists of Sugar and Anhydro-Sugar oligomers with a wide range of degrees of polymerization (DPs). However, only Anhydro-Sugars with DPs up to 3 can be identified in the primary volatiles, and the presence of these Anhydro-Sugars is evident even at 300 °C. Because of high boiling points, cellobiosan and cellotriosan are impossible to be released into the vapor phase via evaporation under the conditions. These h...
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Formation of Anhydro-Sugars in the Primary Volatiles and Solid Residues from Cellulose Fast Pyrolysis in a Wire-Mesh Reactor
Energy & Fuels, 2014Co-Authors: Xun Gong, Xiangpeng Gao, Yu QiaoAbstract:The unique design of wire-mesh reactors (WMR) enables the collection of primary volatiles with minimized secondary reactions from fast pyrolysis of solid fuels. This paper reports the formation of Anhydro-Sugars in both primary volatiles and solid residues from the fast pyrolysis of microcrystalline cellulose in a WMR. Under fast pyrolysis, cellulose is rapidly converted into an intermediate phase, and the maximal yield of the water-soluble intermediates achieved in this study is ~21% on a carbon basis at 450 °C, much higher than those achieved in other pyrolysis reactor systems. The solid residue consists of Sugar and Anhydro-Sugar oligomers with a wide range of degrees of polymerization (DPs). However, only Anhydro-Sugars with DPs up to 3 can be identified in the primary volatiles, and the presence of these Anhydro-Sugars is evident even at 300 °C. Because of high boiling points, cellobiosan and cellotriosan are impossible to be released into the vapor phase via evaporation under the conditions. These high-DP Anhydro-Sugars are also unlikely formed as a result of oligomerization of levoglucosan in the vapour phase because such secondary reactions are minimized in the WMR. Therefore, cellobiosan and cellotriosan are most likelyreleased into the vapor phase as aerosols, driven by the ejection mechanism (i.e., carryover by the intensive release of volatiles). Among the Anhydro-Sugars in the primary volatiles, levoglucosan has yields of 27-44% (on a weight basis) depending upon pyrolysis temperature, while cellobiosan and cellotriosan have yields of 3-9 and 1-2%, respectively. This leads to the highestselectivity of 34-60% (on a weight basis) in the condensed liquid product for levoglucosan. The yields of Anhydro-Sugars initially increase with the pyrolysis temperature and achieve the maximal value between 400 and 450 °C. Further increases in the pyrolysis temperature lead to substantial reductions in the yields of Anhydro-Sugars in the primary volatiles (although the yield ofliquid product remains unchanged), indicating the increased formation of water-insoluble compounds in the primary volatiles at increased temperatures
Kenichi Hatanaka - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Stereoregular Polysaccharide Derivatives Carrying 2,3-Di-O-alkyl Chains
Polymer Journal, 1995Co-Authors: Ken-ichi Kanno, Kazukiyo Kobayashi, Wataru Kinoshita, Kenichi HatanakaAbstract:A new 1,6-Anhydro-Sugar monomer carrying 2,3-di- O -alkyl chains, 1,6-Anhydro-4- O -benzyl-2,3-di- O -dodecyl-β- D -mannopyranose (ABDDM) was synthesized by regioselective protection, and polymerized in cationic conditions, giving stereoregular (1→6)-α- D -mannopyranan derivative. Copolymerization of ABDDM with 1,6-Anhydro-2,3,4-tri- O -benzyl-β- D -glucopyranose (ATBG) was carried out, and monomer reactivity ratios were calculated by the Kelen-Tüdös method, showing r _ABDDM=0.51 and r _ATBG=0.54.
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Effects of Electron-Withdrawing Groups at C-2 Position of 1,6-Anhydro-Sugars on Their Polymerizabilities
Polymer Journal, 1995Co-Authors: Ken-ichi Kanno, Yuichi Kobayashi, Kenichi HatanakaAbstract:1,6-Anhydro-β- D -mannopyranose derivatives having electron-withdrawing groups at C-2, i.e. , 1,6-Anhydro-3,4-di- O -benzyl-2- O -methanesulfonyl-β- D -mannopyranose ( 5 ), 1,6-an-hydro-2- O -benzoyl-3,4-di- O -benzyl-β- D -mannopyranose ( 6 ), and 1,6-Anhydro-3,4-di- O -benzyl-β- D - arabino -hexopyranos-2-ulose ( 7 ) were synthesized, and polymerized under cationic conditions. The polymerization of 5 gave stereoregular polysaccharide with high molecular weight. On the other hand, the polymerization of 6 yielded lower molecular weight polysaccharide, and 7 showed no polymerizability under various conditions. Differences in the reactivity among 1,6-Anhydro Sugar derivatives having various electron-withdrawing groups at C-2 are discussed.
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synthesis of a novel cellulose type hexopyranan 6 deoxy 1 4 α l talopyranan by selective ring opening polymerization of 1 4 Anhydro Sugar derivatives
Macromolecules, 1991Co-Authors: Masumi Ogawa, Kenichi Hatanaka, Toshiyuki UryuAbstract:La polymerisation cationique stereoselective avec ouverture de cycle du 1,4-Anhydro-6-desoxy-2,3-O-isopropylidene talopyranose amorcee par PF 5 ou SbCl 5 donne le 6-desoxy-2,3-O isopropylidene-(1→4)-α-L-talopyranane optiquement actif. Le monomere 2,3-O-cyclohexylidene est polymerise de la meme maniere. La deprotection des 2 polymeres donne le 6-desoxy-(1→4)-α-L-talopyranane qui est le premier hexopyranane de synthese a structure cellulosique obtenu. La polymerisation du monomere 2,3-O-cyclolidene donne un polymere de structure irreguliere
Xun Gong - One of the best experts on this subject based on the ideXlab platform.
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formation of Anhydro Sugars in the primary volatiles and solid residues from cellulose fast pyrolysis in a wire mesh reactor
Energy & Fuels, 2014Co-Authors: Xun Gong, Yu Qiao, Yun Yu, Minghou Xu, Hongwei WuAbstract:The unique design of wire-mesh reactors (WMR) enables the collection of primary volatiles with minimized secondary reactions from fast pyrolysis of solid fuels. This paper reports the formation of Anhydro-Sugars in both primary volatiles and solid residues from the fast pyrolysis of microcrystalline cellulose in a WMR. Under fast pyrolysis, cellulose is rapidly converted into an intermediate phase, and the maximal yield of the water-soluble intermediates achieved in this study is ∼21% on a carbon basis at 450 °C, much higher than those achieved in other pyrolysis reactor systems. The solid residue consists of Sugar and Anhydro-Sugar oligomers with a wide range of degrees of polymerization (DPs). However, only Anhydro-Sugars with DPs up to 3 can be identified in the primary volatiles, and the presence of these Anhydro-Sugars is evident even at 300 °C. Because of high boiling points, cellobiosan and cellotriosan are impossible to be released into the vapor phase via evaporation under the conditions. These h...
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Formation of Anhydro-Sugars in the Primary Volatiles and Solid Residues from Cellulose Fast Pyrolysis in a Wire-Mesh Reactor
Energy & Fuels, 2014Co-Authors: Xun Gong, Xiangpeng Gao, Yu QiaoAbstract:The unique design of wire-mesh reactors (WMR) enables the collection of primary volatiles with minimized secondary reactions from fast pyrolysis of solid fuels. This paper reports the formation of Anhydro-Sugars in both primary volatiles and solid residues from the fast pyrolysis of microcrystalline cellulose in a WMR. Under fast pyrolysis, cellulose is rapidly converted into an intermediate phase, and the maximal yield of the water-soluble intermediates achieved in this study is ~21% on a carbon basis at 450 °C, much higher than those achieved in other pyrolysis reactor systems. The solid residue consists of Sugar and Anhydro-Sugar oligomers with a wide range of degrees of polymerization (DPs). However, only Anhydro-Sugars with DPs up to 3 can be identified in the primary volatiles, and the presence of these Anhydro-Sugars is evident even at 300 °C. Because of high boiling points, cellobiosan and cellotriosan are impossible to be released into the vapor phase via evaporation under the conditions. These high-DP Anhydro-Sugars are also unlikely formed as a result of oligomerization of levoglucosan in the vapour phase because such secondary reactions are minimized in the WMR. Therefore, cellobiosan and cellotriosan are most likelyreleased into the vapor phase as aerosols, driven by the ejection mechanism (i.e., carryover by the intensive release of volatiles). Among the Anhydro-Sugars in the primary volatiles, levoglucosan has yields of 27-44% (on a weight basis) depending upon pyrolysis temperature, while cellobiosan and cellotriosan have yields of 3-9 and 1-2%, respectively. This leads to the highestselectivity of 34-60% (on a weight basis) in the condensed liquid product for levoglucosan. The yields of Anhydro-Sugars initially increase with the pyrolysis temperature and achieve the maximal value between 400 and 450 °C. Further increases in the pyrolysis temperature lead to substantial reductions in the yields of Anhydro-Sugars in the primary volatiles (although the yield ofliquid product remains unchanged), indicating the increased formation of water-insoluble compounds in the primary volatiles at increased temperatures
Arun K. Ghosh - One of the best experts on this subject based on the ideXlab platform.
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2,5-Anhydro Sugar diacid and 2,5-Anhydro Sugar diamine based C 2 symmetric peptidomimetics as potential HIV-1 protease inhibitors.
Tetrahedron letters, 2000Co-Authors: Tushar Kanti Chakraborty, Subhash Ghosh, M. H. V. Ramana Rao, Ajit C. Kunwar, H. Cho, Arun K. GhoshAbstract:Conformationally constrained molecular frameworks of the 2,5-Anhydro Sugar diacid (9) and 2,5-Anhydro Sugar diamines (10, 11) were used to construct architecturally beautiful novel C 2 symmetric peptidomimetics 1-8. Although none of these compounds showed any significant HIV-1 protease inhibitory activity, further refinements in design may lead to protease inhibitors based on these rigid carbohydrate-derived scaffolds.
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2,5-Anhydro Sugar diacid and 2,5-Anhydro Sugar diamine based C2 symmetric peptidomimetics as potential HIV-1 protease inhibitors
Tetrahedron Letters, 2000Co-Authors: Tushar Kanti Chakraborty, Subhash Ghosh, M. H. V. Ramana Rao, Ajit C. Kunwar, H. Cho, Arun K. GhoshAbstract:Abstract Conformationally constrained molecular frameworks of the 2,5-Anhydro Sugar diacid ( 9 ) and 2,5-Anhydro Sugar diamines ( 10 , 11 ) were used to construct architecturally beautiful novel C 2 symmetric peptidomimetics 1 – 8 . Although none of these compounds showed any significant HIV-1 protease inhibitory activity, further refinements in design may lead to protease inhibitors based on these rigid carbohydrate-derived scaffolds.
Tushar Kanti Chakraborty - One of the best experts on this subject based on the ideXlab platform.
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Conformational studies of C2 symmetric peptidomimetics based on2,5-Anhydro Sugar diacid and 2,5-Anhydro Sugar diamine scaffolds
Arkivoc, 2004Co-Authors: Tushar Kanti Chakraborty, Subhash Ghosh, M. H. V. Ramana Rao, Ajit C. KunwarAbstract:Conformational studies of C2 symmetric peptidomimetics with identical peptide strands attached on both sides of 2,5-Anhydro Sugar diacid and 2,5-Anhydro Sugar diamine scaffolds revealed the presence of nine-membered pseudo β-turns in the Sugar diacid based molecules consisting of identical intramolecular hydrogen bonds at the two ends between the AA 2 NH and SugarOH.
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2,5-Anhydro Sugar diacid and 2,5-Anhydro Sugar diamine based C 2 symmetric peptidomimetics as potential HIV-1 protease inhibitors.
Tetrahedron letters, 2000Co-Authors: Tushar Kanti Chakraborty, Subhash Ghosh, M. H. V. Ramana Rao, Ajit C. Kunwar, H. Cho, Arun K. GhoshAbstract:Conformationally constrained molecular frameworks of the 2,5-Anhydro Sugar diacid (9) and 2,5-Anhydro Sugar diamines (10, 11) were used to construct architecturally beautiful novel C 2 symmetric peptidomimetics 1-8. Although none of these compounds showed any significant HIV-1 protease inhibitory activity, further refinements in design may lead to protease inhibitors based on these rigid carbohydrate-derived scaffolds.
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2,5-Anhydro Sugar diacid and 2,5-Anhydro Sugar diamine based C2 symmetric peptidomimetics as potential HIV-1 protease inhibitors
Tetrahedron Letters, 2000Co-Authors: Tushar Kanti Chakraborty, Subhash Ghosh, M. H. V. Ramana Rao, Ajit C. Kunwar, H. Cho, Arun K. GhoshAbstract:Abstract Conformationally constrained molecular frameworks of the 2,5-Anhydro Sugar diacid ( 9 ) and 2,5-Anhydro Sugar diamines ( 10 , 11 ) were used to construct architecturally beautiful novel C 2 symmetric peptidomimetics 1 – 8 . Although none of these compounds showed any significant HIV-1 protease inhibitory activity, further refinements in design may lead to protease inhibitors based on these rigid carbohydrate-derived scaffolds.