In an active magnetic bearing （AMB） system, the catcher bearings （CBs） are indispensable to protect the rotor and stator in case the magnetic bearings fail. Most of the former researches associated with CBs are ma...In an active magnetic bearing （AMB） system, the catcher bearings （CBs） are indispensable to protect the rotor and stator in case the magnetic bearings fail. Most of the former researches associated with CBs are mainly focused on the dynamic responses of the rotor drops onto traditional single-decker catcher bearings （SDCBs）. But because of the lower limited speed of SDCB, it cannot withstand the ultra high speed rotation after rotor drop. In this paper, based on the analysis of the disadvantages of SDCBs, a new type of double-decker catcher bearings （DDCBs） is proposed to enhance the CB work performance in AMB system. In order to obtain thc accurate rotor movements before AMB failure, the dynamic characteristics of AMB are theoretically derived. Detailed simulation models containing rigid rotor model, contact model between rotor and inner race, DDCB force model as well as heating model after rotor drop are established. Then, using those established models the dynamic responses of rotor drops onto DDCBs and SDCBs are respectively simulated. The rotor orbits, contact forces, spin speeds of various parts and heat energies after AMB failure are mainly analyzed. The simulation results show that DDCBs can effectively improve the CBs limit rotational speed and reduce the following vibrations, impacts and heating. Finally, rotor drop experiments choosing different types of CBs are carried out on the established AMB test bench. Rotor orbits, inner race temperatures as well as the rotating speeds of both inner race and intermediate races after rotor drop are synchronously measured. The experiment results verify the advantages of DDCB and the correctness of theoretical analysis. The studies provide certain theoretical and experimental references for the application of DDCBs in AMB system.展开更多
Poly （4- methylphenoxyphosphnzene ） -graft-poly （ ethylene oxide ） （ PPZ-g- PEO ）, a novel amphiphilie grafting polymer was prepared via the Decker-Forster reaction. It is found that the graft efficiency increas...Poly （4- methylphenoxyphosphnzene ） -graft-poly （ ethylene oxide ） （ PPZ-g- PEO ）, a novel amphiphilie grafting polymer was prepared via the Decker-Forster reaction. It is found that the graft efficiency increased with extension of reaction time. Low molecular weight of poly （ ethylene oxide ） favored the grafting reaction. The grafted polymer has two different glass transition temperatures（ Tg） with those of pure poly（ 4-methyl- phenoxy-phopsphazene ） and PEO. The emulsifying ability of grafted polymer was studied with benzene-water mixtare. The emulsifying volumes increased with the decreasing of PEO＇ s molecular weight. The contact angle of film forming from grafted polymer decreased after introduction of PEO grafting chain.展开更多
Two new chiral mixed(phthalocyaninato)(porphyrinato)rare earth triple-decker complexes with both(R)-and(S)-enantiomers were synthesized and structurally characterized.The significant magneto-chiral cross effect reveal...Two new chiral mixed(phthalocyaninato)(porphyrinato)rare earth triple-decker complexes with both(R)-and(S)-enantiomers were synthesized and structurally characterized.The significant magneto-chiral cross effect revealed for the dysprosium compound suggests the great potential of sandwich-type tetrapyrrole rare earth systems in the research field of magneto-chiral dichroism.展开更多
For the purpose of engineering magnetic anisotropy,chiral binaphthyl substituents with slight electron-withdrawing ability and dibutylamino substituents with intense electron-donating nature are incoporated onto the p...For the purpose of engineering magnetic anisotropy,chiral binaphthyl substituents with slight electron-withdrawing ability and dibutylamino substituents with intense electron-donating nature are incoporated onto the periphery of each phthalocyanine ligand in the bis(phthalocyaninato)terbium double-decker compound,resulting in the chiral heteroleptic bis(phthalocyaninato)terbium complex(R)/(S)-[Pc(OBNP)_(4)]Tb{Pc[N(C_(4)H_(9))_(2)]_(8)}(R/S-1){Pc(OBNP)_(4)={tetrakis(dinaphtho[1,2-e:1′,2′-g]-1,4-dioxocine)[2,3-b;2′,3′-k;2″,3″-t;2″′,3″′-c′]phthalocyanine};Pc[N(C_(4)H_(9))_(2)]_(8)=[2,3,9,10,16,17,23,24-octakis(dibutylamino)phthalocyanine]}.Magnetic studies reveal the typical single-ion magnet(SIM)nature of this chiral bis(phthalocyaninato)terbium double-decker with spin reversal energy barrier of 638 K.A butterfly-shaped magnetic hysteresis loop was observed at even 25 K for R-1 under the sweep rate of 500 Oe s^(-1).The performance of this SIM is well rationalized on the basis of theoretical analysis of the electrostatic potential according to calculations using the density functional theory method.展开更多
Despite the rapid progress in the research on the synthesis of linear macromolecular systems with double-decker SQs included in the co-polymer chain,based on diverse catalytic processes,it still has limitations becaus...Despite the rapid progress in the research on the synthesis of linear macromolecular systems with double-decker SQs included in the co-polymer chain,based on diverse catalytic processes,it still has limitations because of the formation of co-oligomers up to 20 units in a chain.Herein,we present a distinct look at known hydrosilylation reactions for forming hybrid copolymers.展开更多
Mixed(phthalocyaninato)(porphyrinato)rare earth double-decker complexes M^(III)(Pc)(TNP)(M=Tb(1),Dy(2),and Y(3);Pc=phthalocyaninate;TNP=tetranaphthylporphyrinate)were synthesized and characterized by elemental analysi...Mixed(phthalocyaninato)(porphyrinato)rare earth double-decker complexes M^(III)(Pc)(TNP)(M=Tb(1),Dy(2),and Y(3);Pc=phthalocyaninate;TNP=tetranaphthylporphyrinate)were synthesized and characterized by elemental analysis and a range of spectroscopic methods.They represent the first examples of double-decker rare earth complexes containing a tetranaphthylporphyrin ligand.展开更多
In this work,we report the preparation,isolation,and characterization of a family of double-decker silses-quioxane architectures starting from the previously reported DDSQ-Me_(2)H_(2)precursor,a mixture of cis and tra...In this work,we report the preparation,isolation,and characterization of a family of double-decker silses-quioxane architectures starting from the previously reported DDSQ-Me_(2)H_(2)precursor,a mixture of cis and trans isomers.Using such a starting material results in a subsequent mixture of isomers when hydrosilyl-ation reactions using DDSQ-Me_(2)H_(2)and hydroxyalkyl-substituted alkenes catalyzed by Karstedt catalyst are performed.We describe a procedure to sequentially crystallize the two isomers from one another,affording a protocol potentially applicable to other closely related derivatives.The ability to access pure cis and trans isomers of double-decker silsesquioxanes may result in the preparation of new materials and polymers with well-defined properties.All resulting silsesquioxanes were characterized by multinuclear(^(1)H,^(13)C,and^(29)Si)NMR spectroscopy,FT-IR,and HR-MS.Additionally,we report five crystal structures of geometrical isomers,including two cis forms described in the literature for the first time.This is a break-through in itself and sets a new strategy for obtaining such exiting organosilicon-based systems.展开更多
Herein,we disclose an unexpected Si–O–Si cage reorganization that was observed during the standard hydrolytic condensation procedure of tetrasilanol double-decker silsesquioxane(DDSQ)with respective mono-and di-chlo...Herein,we disclose an unexpected Si–O–Si cage reorganization that was observed during the standard hydrolytic condensation procedure of tetrasilanol double-decker silsesquioxane(DDSQ)with respective mono-and di-chlorosilanes.The investigation of this process allowed us to propose the possible mechanism of this transformation.The formation of all structures was confirmed by NMR,FT-IR,and X-ray(for eleven examples)techniques and their thermal stability was verified(TGA).Additionally,we revealed unusual intramolecular homocoupling product formation during the silylative coupling reaction of vinyl-DDSQ derivatives.It deserves to be emphasized that these findings are the first example of a thorough investigation of hydrolytic condensation and the silylative coupling procedures in the chemistry of DDSQs.展开更多
Designed and built by eight Dutch engineers,the worlds longest bicycle is 55.16 meters,roughly the same length as four double-decker buses.39-year-old Ivan Schalk had been thinking about building the world's longe...Designed and built by eight Dutch engineers,the worlds longest bicycle is 55.16 meters,roughly the same length as four double-decker buses.39-year-old Ivan Schalk had been thinking about building the world's longest bicycle since reading about it in The Guinness Book of Records when he was a child,but he only started this project in 2018,as a way to fill up his free time.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50975134)
文摘In an active magnetic bearing （AMB） system, the catcher bearings （CBs） are indispensable to protect the rotor and stator in case the magnetic bearings fail. Most of the former researches associated with CBs are mainly focused on the dynamic responses of the rotor drops onto traditional single-decker catcher bearings （SDCBs）. But because of the lower limited speed of SDCB, it cannot withstand the ultra high speed rotation after rotor drop. In this paper, based on the analysis of the disadvantages of SDCBs, a new type of double-decker catcher bearings （DDCBs） is proposed to enhance the CB work performance in AMB system. In order to obtain thc accurate rotor movements before AMB failure, the dynamic characteristics of AMB are theoretically derived. Detailed simulation models containing rigid rotor model, contact model between rotor and inner race, DDCB force model as well as heating model after rotor drop are established. Then, using those established models the dynamic responses of rotor drops onto DDCBs and SDCBs are respectively simulated. The rotor orbits, contact forces, spin speeds of various parts and heat energies after AMB failure are mainly analyzed. The simulation results show that DDCBs can effectively improve the CBs limit rotational speed and reduce the following vibrations, impacts and heating. Finally, rotor drop experiments choosing different types of CBs are carried out on the established AMB test bench. Rotor orbits, inner race temperatures as well as the rotating speeds of both inner race and intermediate races after rotor drop are synchronously measured. The experiment results verify the advantages of DDCB and the correctness of theoretical analysis. The studies provide certain theoretical and experimental references for the application of DDCBs in AMB system.
文摘Poly （4- methylphenoxyphosphnzene ） -graft-poly （ ethylene oxide ） （ PPZ-g- PEO ）, a novel amphiphilie grafting polymer was prepared via the Decker-Forster reaction. It is found that the graft efficiency increased with extension of reaction time. Low molecular weight of poly （ ethylene oxide ） favored the grafting reaction. The grafted polymer has two different glass transition temperatures（ Tg） with those of pure poly（ 4-methyl- phenoxy-phopsphazene ） and PEO. The emulsifying ability of grafted polymer was studied with benzene-water mixtare. The emulsifying volumes increased with the decreasing of PEO＇ s molecular weight. The contact angle of film forming from grafted polymer decreased after introduction of PEO grafting chain.
基金Financial support from the Natural Science Foundation of China,National Key Basic Research Program of China(grant no.2013CB933402 and 2012CB224801)National Ministry of Education of China,and Beijing Municipal Commission of Education is gratefully acknowledged.
文摘Two new chiral mixed(phthalocyaninato)(porphyrinato)rare earth triple-decker complexes with both(R)-and(S)-enantiomers were synthesized and structurally characterized.The significant magneto-chiral cross effect revealed for the dysprosium compound suggests the great potential of sandwich-type tetrapyrrole rare earth systems in the research field of magneto-chiral dichroism.
基金Financial support from National Natural Science Foundation of China(No.21401009,21631003,21671017,and 21671024)Fundamental Research Funds for the Central Universities(No.FRF-BD-17-016A)Beijing Municipal Commission of Education,and University of Science and Technology Beijing is gratefully acknowledged.
文摘For the purpose of engineering magnetic anisotropy,chiral binaphthyl substituents with slight electron-withdrawing ability and dibutylamino substituents with intense electron-donating nature are incoporated onto the periphery of each phthalocyanine ligand in the bis(phthalocyaninato)terbium double-decker compound,resulting in the chiral heteroleptic bis(phthalocyaninato)terbium complex(R)/(S)-[Pc(OBNP)_(4)]Tb{Pc[N(C_(4)H_(9))_(2)]_(8)}(R/S-1){Pc(OBNP)_(4)={tetrakis(dinaphtho[1,2-e:1′,2′-g]-1,4-dioxocine)[2,3-b;2′,3′-k;2″,3″-t;2″′,3″′-c′]phthalocyanine};Pc[N(C_(4)H_(9))_(2)]_(8)=[2,3,9,10,16,17,23,24-octakis(dibutylamino)phthalocyanine]}.Magnetic studies reveal the typical single-ion magnet(SIM)nature of this chiral bis(phthalocyaninato)terbium double-decker with spin reversal energy barrier of 638 K.A butterfly-shaped magnetic hysteresis loop was observed at even 25 K for R-1 under the sweep rate of 500 Oe s^(-1).The performance of this SIM is well rationalized on the basis of theoretical analysis of the electrostatic potential according to calculations using the density functional theory method.
基金supported by the National Science Centre(Poland)Project OPUS UMO 2016/23/B/ST5/00201 and grant no.POWR.03.02.00-00-I026/16 co-financed by the European Union through the European Social Fund under the Operational Program Knowledge Education Development.
文摘Despite the rapid progress in the research on the synthesis of linear macromolecular systems with double-decker SQs included in the co-polymer chain,based on diverse catalytic processes,it still has limitations because of the formation of co-oligomers up to 20 units in a chain.Herein,we present a distinct look at known hydrosilylation reactions for forming hybrid copolymers.
基金the Anyang Key Laboratory for Chemical Biosensing(21302003)the Natural Science Foundation of China(21471015,21631003,and 21701046)the Fundamental Research Funds for the Central Universities(FRF-BD-17-016A)is gratefully acknowledged.
文摘Mixed(phthalocyaninato)(porphyrinato)rare earth double-decker complexes M^(III)(Pc)(TNP)(M=Tb(1),Dy(2),and Y(3);Pc=phthalocyaninate;TNP=tetranaphthylporphyrinate)were synthesized and characterized by elemental analysis and a range of spectroscopic methods.They represent the first examples of double-decker rare earth complexes containing a tetranaphthylporphyrin ligand.
基金supported by the National Science Centre,Poland(Grant No.2020/39/B/ST4/00910).
文摘In this work,we report the preparation,isolation,and characterization of a family of double-decker silses-quioxane architectures starting from the previously reported DDSQ-Me_(2)H_(2)precursor,a mixture of cis and trans isomers.Using such a starting material results in a subsequent mixture of isomers when hydrosilyl-ation reactions using DDSQ-Me_(2)H_(2)and hydroxyalkyl-substituted alkenes catalyzed by Karstedt catalyst are performed.We describe a procedure to sequentially crystallize the two isomers from one another,affording a protocol potentially applicable to other closely related derivatives.The ability to access pure cis and trans isomers of double-decker silsesquioxanes may result in the preparation of new materials and polymers with well-defined properties.All resulting silsesquioxanes were characterized by multinuclear(^(1)H,^(13)C,and^(29)Si)NMR spectroscopy,FT-IR,and HR-MS.Additionally,we report five crystal structures of geometrical isomers,including two cis forms described in the literature for the first time.This is a break-through in itself and sets a new strategy for obtaining such exiting organosilicon-based systems.
基金funded by the National Science Centre(NCN)grant no UMO-2016/23/B/ST5/00201,UMO-2017/27/N/ST5/00175,and UMO-2020/36/T/ST5/00072 and grants no.POWR.03.02.00-00-I023/17 and POWR.03.02.00-00-I026/16 cofinanced by the European Union through the European Social Fund under the Operational Program Knowledge Education Development.
文摘Herein,we disclose an unexpected Si–O–Si cage reorganization that was observed during the standard hydrolytic condensation procedure of tetrasilanol double-decker silsesquioxane(DDSQ)with respective mono-and di-chlorosilanes.The investigation of this process allowed us to propose the possible mechanism of this transformation.The formation of all structures was confirmed by NMR,FT-IR,and X-ray(for eleven examples)techniques and their thermal stability was verified(TGA).Additionally,we revealed unusual intramolecular homocoupling product formation during the silylative coupling reaction of vinyl-DDSQ derivatives.It deserves to be emphasized that these findings are the first example of a thorough investigation of hydrolytic condensation and the silylative coupling procedures in the chemistry of DDSQs.
文摘Designed and built by eight Dutch engineers,the worlds longest bicycle is 55.16 meters,roughly the same length as four double-decker buses.39-year-old Ivan Schalk had been thinking about building the world's longest bicycle since reading about it in The Guinness Book of Records when he was a child,but he only started this project in 2018,as a way to fill up his free time.
