A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ~ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiato...A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ~ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL pre-polymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide(A) to PCL pre-polymer(BB). The block copolymers were characterized by ~ 1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.展开更多
The relation between technology parameters and performance index of the wheat three-stage concurrent-flow drying technology is studied by use of quadratic orthogonial rotate combinative experiment design method.The op...The relation between technology parameters and performance index of the wheat three-stage concurrent-flow drying technology is studied by use of quadratic orthogonial rotate combinative experiment design method.The optimum parameters of drying technology are obtained by nonlinear optimize corresponding regression model and test.All experiment was finished in concurrent-flow grain drying experiment table.The results of this study will be significant for designing energy-saving grain drying machine.展开更多
The L - proline - functionalized polystyrene with 1- methyldecylene spacerwas synthesized from 2 % divinylbenzene -crosslinked Polystyrene gel via 10 -bro-mo - 1 - methyldecyl polystyrene intermediate. After complexed...The L - proline - functionalized polystyrene with 1- methyldecylene spacerwas synthesized from 2 % divinylbenzene -crosslinked Polystyrene gel via 10 -bro-mo - 1 - methyldecyl polystyrene intermediate. After complexed with copper(Ⅱ )ion, the polymer with L - proline ligand was used as the chiral statiboary phase(CSP) for ligand exchange chromatography of amino acid racemates. The resultsshowed that the CSP possessed powerful enantioselectivity and all racenzates of thefifteen tried amino acids were completely separated.展开更多
Two different illites in samples from S0 to L10 loess-paleosol sequence at Heimugou section in Luochuan are identified by decomposition of X-ray diffraction (XRD) curve, transmission electronic microscopy (TEM) and en...Two different illites in samples from S0 to L10 loess-paleosol sequence at Heimugou section in Luochuan are identified by decomposition of X-ray diffraction (XRD) curve, transmission electronic microscopy (TEM) and energy dis- persive X-ray detector (EDX) analyses. Type I illite displays relatively poor crystallinity, wide and blunt XRD peaks, the highest content of which in <2 μm clay minerals is up to 55%. Type II illite shows good crystallinity, narrow and sharp XRD peaks. The contents of these two types of illites show mutually exclusive relationship in the studied section. The EDX analyses indicate that in contrast to the illite with good crystallinity, the illite with poor crystallinity is enriched in K+, Si4+ and depleted inAl3+.展开更多
Dysembryoplastic neuroepithelial tumors ( DNTs ), which were first describedby Daumas-Duport in 1988, are one of rare benign tumors usually associated with medicallyintractable seizures which date from childhood. The ...Dysembryoplastic neuroepithelial tumors ( DNTs ), which were first describedby Daumas-Duport in 1988, are one of rare benign tumors usually associated with medicallyintractable seizures which date from childhood. The clinical, pathologic and neuroradiologicfindings of DNT have been described. Recent advances in magnetic resonance imaging ( MRI) technologyallow the acquisition of cerebral microcirculation parameters by perfusion weighted imaging ( PWI)and brain metabolic indices by MR spectroscopy (MRS) . Several studies have shown the utility of PWIand MRS can improve the diagnostic accuracy of brain tumor, we combine the two techniques toevaluate a case with DNT and suggest that wider application of these techniques is warranted.展开更多
The study on database technologies, or more generally, the technologies ofdata and information management, is an important and active research field. Recently, many excitingresults have been reported. In this fast gro...The study on database technologies, or more generally, the technologies ofdata and information management, is an important and active research field. Recently, many excitingresults have been reported. In this fast growing field, Chinese researchers play more and moreactive roles. Research papers from Chinese scholars, both in China and abroad, appear in prestigiousacademic forums. In this paper, we, nine young Chinese researchers working in the United States,present concise surveys and report our recent progress on the selected fields that we are workingon. Although the paper covers only a small number of topics and the selection of the topics is farfrom balanced, we hope that such an effort would attract more and more researchers, especially thosein China, to enter the frontiers of database research and promote collaborations. For the obviousreason, the authors are listed alphabetically, while the sections are arranged in the order of theauthor list.展开更多
The recombinant adeno-associated viral vector with human coagulation Factor Ⅸ minigene which wasregulated by CMV promoter was constructed. Largequantity of recombinant adeno-associated viral particles (rAAV/ hFⅨ) wa...The recombinant adeno-associated viral vector with human coagulation Factor Ⅸ minigene which wasregulated by CMV promoter was constructed. Largequantity of recombinant adeno-associated viral particles (rAAV/ hFⅨ) was prepared by the HSV/AAV hybrid helper virus method. Southern dot blot assay and QC-PCR indicated that the titer of the virus was 3.6×1012 v.g./mL. It demonstrated that this method can effectively overcome the hurdles of mass production of AAV vector. Followed by anintramuscular injection of viral vectors (7.5×1011 v.g./mouse) in the quadriceps femoris, an elevation of human Factor Ⅸexpression in the plasma of hemophilia B mice was detected (387 ng/mL) and persisted more than 12 weeks. The level of anti-virus antibody in plasma aligned with the Factor Ⅸexpression curve. The QC-PCR method is easier and moreaccurate than traditional dot hybridization fordetermination of the titer of recombinant adeno-associated virus. Moreover, there are no HSV particles existing inproduced AAV assayed by RT-PCR. AAV is the only virus that has been amplified from AAV-injected muscle by PCR.展开更多
文摘A biodegradable ABBA block copolymer was synthesized via the ring-opening co-polymerization of ~ε-caprolactone(CL, B) and glycolide(A) by means of step polymerization in the presence of ethylene glycol as an initiator and stannous octanoate as a catalyst at 110 ℃ for 48 h. The molecular length of the PCL pre-polymer(BB) could be adjusted by controlling the molar ratio of the ethylene glycol initiator to ε-caprolactone monomer. The structure and the composition of the block copolymer were determined by the weight ratio of the monomer glycolide(A) to PCL pre-polymer(BB). The block copolymers were characterized by ~ 1H NMR, GPC, DSC and X-ray. The results confirm the successful synthesis of an ABBA block copolymer.
文摘The relation between technology parameters and performance index of the wheat three-stage concurrent-flow drying technology is studied by use of quadratic orthogonial rotate combinative experiment design method.The optimum parameters of drying technology are obtained by nonlinear optimize corresponding regression model and test.All experiment was finished in concurrent-flow grain drying experiment table.The results of this study will be significant for designing energy-saving grain drying machine.
文摘The L - proline - functionalized polystyrene with 1- methyldecylene spacerwas synthesized from 2 % divinylbenzene -crosslinked Polystyrene gel via 10 -bro-mo - 1 - methyldecyl polystyrene intermediate. After complexed with copper(Ⅱ )ion, the polymer with L - proline ligand was used as the chiral statiboary phase(CSP) for ligand exchange chromatography of amino acid racemates. The resultsshowed that the CSP possessed powerful enantioselectivity and all racenzates of thefifteen tried amino acids were completely separated.
基金the Youth Fund of Peking Universitythe Teaching and Research Award Program for Outstanding Young Teachers in the Higher Education Institutions of the Ministry of Education,China+1 种基金the National Natural Science Foundation of China(Grant No.49925307) TEM Analysis Fund of Peking University.
文摘Two different illites in samples from S0 to L10 loess-paleosol sequence at Heimugou section in Luochuan are identified by decomposition of X-ray diffraction (XRD) curve, transmission electronic microscopy (TEM) and energy dis- persive X-ray detector (EDX) analyses. Type I illite displays relatively poor crystallinity, wide and blunt XRD peaks, the highest content of which in <2 μm clay minerals is up to 55%. Type II illite shows good crystallinity, narrow and sharp XRD peaks. The contents of these two types of illites show mutually exclusive relationship in the studied section. The EDX analyses indicate that in contrast to the illite with good crystallinity, the illite with poor crystallinity is enriched in K+, Si4+ and depleted inAl3+.
文摘Dysembryoplastic neuroepithelial tumors ( DNTs ), which were first describedby Daumas-Duport in 1988, are one of rare benign tumors usually associated with medicallyintractable seizures which date from childhood. The clinical, pathologic and neuroradiologicfindings of DNT have been described. Recent advances in magnetic resonance imaging ( MRI) technologyallow the acquisition of cerebral microcirculation parameters by perfusion weighted imaging ( PWI)and brain metabolic indices by MR spectroscopy (MRS) . Several studies have shown the utility of PWIand MRS can improve the diagnostic accuracy of brain tumor, we combine the two techniques toevaluate a case with DNT and suggest that wider application of these techniques is warranted.
文摘The study on database technologies, or more generally, the technologies ofdata and information management, is an important and active research field. Recently, many excitingresults have been reported. In this fast growing field, Chinese researchers play more and moreactive roles. Research papers from Chinese scholars, both in China and abroad, appear in prestigiousacademic forums. In this paper, we, nine young Chinese researchers working in the United States,present concise surveys and report our recent progress on the selected fields that we are workingon. Although the paper covers only a small number of topics and the selection of the topics is farfrom balanced, we hope that such an effort would attract more and more researchers, especially thosein China, to enter the frontiers of database research and promote collaborations. For the obviousreason, the authors are listed alphabetically, while the sections are arranged in the order of theauthor list.
基金supported by the National Natural Science Foundation of China(Grant No.30100102).
文摘The recombinant adeno-associated viral vector with human coagulation Factor Ⅸ minigene which wasregulated by CMV promoter was constructed. Largequantity of recombinant adeno-associated viral particles (rAAV/ hFⅨ) was prepared by the HSV/AAV hybrid helper virus method. Southern dot blot assay and QC-PCR indicated that the titer of the virus was 3.6×1012 v.g./mL. It demonstrated that this method can effectively overcome the hurdles of mass production of AAV vector. Followed by anintramuscular injection of viral vectors (7.5×1011 v.g./mouse) in the quadriceps femoris, an elevation of human Factor Ⅸexpression in the plasma of hemophilia B mice was detected (387 ng/mL) and persisted more than 12 weeks. The level of anti-virus antibody in plasma aligned with the Factor Ⅸexpression curve. The QC-PCR method is easier and moreaccurate than traditional dot hybridization fordetermination of the titer of recombinant adeno-associated virus. Moreover, there are no HSV particles existing inproduced AAV assayed by RT-PCR. AAV is the only virus that has been amplified from AAV-injected muscle by PCR.
