An inevitable consequence of the development of the offshore petroleum industry is the eventual obsolescence of large offshore structures. Proper methods for removal of decommissioned offshore platforms are becoming a...An inevitable consequence of the development of the offshore petroleum industry is the eventual obsolescence of large offshore structures. Proper methods for removal of decommissioned offshore platforms are becoming an important topic that the oil and gas industry must pay increasing attention to. While removing sections from a decommissioned jacket platform, the stability of the remaining parts is critical The jacket danger indices D ~ and Ds defined in this paper are very useful for analyzing the safety of any procedure planned for disassembling a jacket platform. The safest piles cutting sequence can be determined easily by comparing every column of Do and Ds or simply analyzing the figures of every row ofD o and D,.展开更多
The synthesis of chiral polyaniline （PANI） induced by modified hemoglobin （Hb） was pro- foundly explored for the first time. Results revealed that after being separated, inactivated or immobilized, Hb can still in...The synthesis of chiral polyaniline （PANI） induced by modified hemoglobin （Hb） was pro- foundly explored for the first time. Results revealed that after being separated, inactivated or immobilized, Hb can still induce the formation of chiral PANI successfully, suggesting that Hb can be used as the chiral inducers regardless of harsh reaction conditions. By examining the properties of PANI induced by modified Hb, it was found that Hb（inactivated）-PANI possessed excellent chirality, stability, and crystalline structure. The globin separated from Hb was demonstrated to have the ability of inducing the production of chiral PANI whereas the hematin from Hb had no capacity to direct enantio specificity for the PANI chains. Results indicated that Hb（immobilized）-PANI exhibited poor yield, doping state, and crys- talline structure, indicating that the immobilization of Hb by entrapment was not beneficial to the polymerization reaction. Results also showed that the structure of Hb may have significant effects on the morphologies of chiral PANI.展开更多
The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concent...The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.展开更多
The process of resolution of racemic ketoprofen using n-octyl-d-glucamine as an optical resolution agent was investigated. The process consists of preparation of the diastereomer salt of ketoprofen with n-octyl-d-gluc...The process of resolution of racemic ketoprofen using n-octyl-d-glucamine as an optical resolution agent was investigated. The process consists of preparation of the diastereomer salt of ketoprofen with n-octyl-d-glucamine, liberation of S-(+)-ketoprofen from its diastereomer salt and recovery of the remaining ketoprofen and n-octyl-d- glucamine. The suitable conditions for preparation of the diastereomer salt were methanol and ethyl acetate (1.1 by volume) as the solvent, the ratio of solvent volume to ketoprofen mass at 8ml:1g, and the molar ratio of ketoprofen to n-octyl-d-glucamine at 1:1. The preferred approach to liberate S-(+)-ketoprofen from its diastereomer salt was alkali dissolution, acid adjustment and ethyl acetate extraction. Racemization of the recovered ketoprofen could be achieved by reacting the recovered ketoprofen with 10% NaOH at 507 kPa for 6h. The recovered n-octyl-d- glucamine could be refined by acid dissolution and alkali adjustment. S-(+)-ketoprofen can be obtained with high optical purity and yield, showing that the present process is a practical and efficient one which can be used in industrial scale for preparation of S-(+)-ketoprofen.展开更多
The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and f...The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and fully characterized by nuclear magnetic resonance,mass spectrometry,Fourier transform infrared spectroscopy,ultraviolet-visible spectroscopy,and specific rotation.The proposed metalloporphyrin catalysts were synthesized with either 1,1'-bi-2-naphthol or L-phenylalanine,which have different chirality,and then applied to the coupling of propylene oxide and CO2 for generating chiral cyclic carbonates with good enantioselectivity under extremely mild conditions in the presence of tetrabutyl ammonium chloride as a co-catalyst.The good enantioselectivity in the cycloaddition reaction is attributed to a synergistic interplay between the chiral porphyrin catalysts and the substrate.The mechanism and enantioselectivity of the asymmetric cycloaddition reaction is discussed.展开更多
In the paper,we propose a framework to investigate how to effectively perform traffic flow splitting in heterogeneous wireless networks from a queue point.The average packet delay in heterogeneous wireless networks is...In the paper,we propose a framework to investigate how to effectively perform traffic flow splitting in heterogeneous wireless networks from a queue point.The average packet delay in heterogeneous wireless networks is derived in a probabilistic manner.The basic idea can be understood via treating the integrated heterogeneous wireless networks as different coupled and parallel queuing systems.The integrated network performance can approach that of one queue with maximal the multiplexing gain.For the purpose of illustrating the effectively of our proposed model,the Cellular/WLAN interworking is exploited.To minimize the average delay,a heuristic search algorithm is used to get the optimal probability of splitting traffic flow.Further,a Markov process is applied to evaluate the performance of the proposed scheme and compare with that of selecting the best network to access in terms of packet mean delay and blocking probability.Numerical results illustrate our proposed framework is effective and the flow splitting transmission can obtain more performance gain in heterogeneous wireless networks.展开更多
Biomacromolecules including protein and nucleic acids are considered as promising chiral selectors in the fields of enantioselective separation, owing to their inherent chirality, polymorphous structures, stable physi...Biomacromolecules including protein and nucleic acids are considered as promising chiral selectors in the fields of enantioselective separation, owing to their inherent chirality, polymorphous structures, stable physicochemical properties, good biocompatibility as well as susceptible modification and regulation. In this review, firstly,enantioselective recognition mechanism of proteins and nucleic acids toward different enantiomers is discussed,as well as their potential applications on the chiral separation of racemic compounds. Secondly, preparative enantioseparation adopting biomolecule-modified hybrid materials including porous microspheres, magnetic nanoparticles and affinity membranes, are introduced respectively. Finally, novel chiroptical materials constructed on the basis of chiral induction, transfer, amplification and transcription, are recognized as promising candidates in future applications.展开更多
Direct chiral separation of azelnidipine enantiomers with Pirkle-type Sumichiral OA-2500 column was studied by normal phase and reserve phase conditions. By normal phase, azelnidipine enantiomers were well separated w...Direct chiral separation of azelnidipine enantiomers with Pirkle-type Sumichiral OA-2500 column was studied by normal phase and reserve phase conditions. By normal phase, azelnidipine enantiomers were well separated with Rs as 4.0 using hexane–ethanol （90：10, v/v） as mobile phase, and Rs as 2.7 in shorter time （no more than 13 min） using hexane–ethanol （60：40, v/v） as the recommended mobile phase. They were only partially separated by reverse phase using methanol or methanol containing 0.05 mol/L ammonium acetate. Using same chiral column, the chiral separation of other dihydropyridine calcium antagonist analogues almodipine and nimodipine were also studied and showed partial chiral separation in normal phase.展开更多
Effective enantioseparation of Naftopidil and its derivatives by HPLC was accomplished using several different polysaccharide-based chiral stationary phases（CSPs）.In normal-phase mode,the compounds were eluted on fo...Effective enantioseparation of Naftopidil and its derivatives by HPLC was accomplished using several different polysaccharide-based chiral stationary phases（CSPs）.In normal-phase mode,the compounds were eluted on four coated-and two immobilized-columns with the mixture of n-hexane,isopropanol and diethylamine（DEA）.Polysaccharide tris（3,5- dimethylphenyl carbamate） was shown to be the best enantiomer selector.In addition,the immobilized column packed with Chiralpak IA or IB was applied under polar-organic and reversed-phase conditions,both of which exhibited excellent enantioselectivity for Naftopidil and its derivatives.Furthermore,the underlying possible chiral recognition mechanisms were discussed.展开更多
基金Supported by the Open Foundation of the State Key Lab for Ocean Engineering of Shanghai Jiao Tong University under Grant No.0602
文摘An inevitable consequence of the development of the offshore petroleum industry is the eventual obsolescence of large offshore structures. Proper methods for removal of decommissioned offshore platforms are becoming an important topic that the oil and gas industry must pay increasing attention to. While removing sections from a decommissioned jacket platform, the stability of the remaining parts is critical The jacket danger indices D ~ and Ds defined in this paper are very useful for analyzing the safety of any procedure planned for disassembling a jacket platform. The safest piles cutting sequence can be determined easily by comparing every column of Do and Ds or simply analyzing the figures of every row ofD o and D,.
基金supported by the National Natural Science Foundation of China(No.21303105)the Scientific Research Foundation for the Returned Overseas Chinese Scholars and State Education Ministry(No.ZX2012-05)
文摘The synthesis of chiral polyaniline （PANI） induced by modified hemoglobin （Hb） was pro- foundly explored for the first time. Results revealed that after being separated, inactivated or immobilized, Hb can still induce the formation of chiral PANI successfully, suggesting that Hb can be used as the chiral inducers regardless of harsh reaction conditions. By examining the properties of PANI induced by modified Hb, it was found that Hb（inactivated）-PANI possessed excellent chirality, stability, and crystalline structure. The globin separated from Hb was demonstrated to have the ability of inducing the production of chiral PANI whereas the hematin from Hb had no capacity to direct enantio specificity for the PANI chains. Results indicated that Hb（immobilized）-PANI exhibited poor yield, doping state, and crys- talline structure, indicating that the immobilization of Hb by entrapment was not beneficial to the polymerization reaction. Results also showed that the structure of Hb may have significant effects on the morphologies of chiral PANI.
基金Project(20776038)supported by the National Natural Science Foundation of China
文摘The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.
文摘The process of resolution of racemic ketoprofen using n-octyl-d-glucamine as an optical resolution agent was investigated. The process consists of preparation of the diastereomer salt of ketoprofen with n-octyl-d-glucamine, liberation of S-(+)-ketoprofen from its diastereomer salt and recovery of the remaining ketoprofen and n-octyl-d- glucamine. The suitable conditions for preparation of the diastereomer salt were methanol and ethyl acetate (1.1 by volume) as the solvent, the ratio of solvent volume to ketoprofen mass at 8ml:1g, and the molar ratio of ketoprofen to n-octyl-d-glucamine at 1:1. The preferred approach to liberate S-(+)-ketoprofen from its diastereomer salt was alkali dissolution, acid adjustment and ethyl acetate extraction. Racemization of the recovered ketoprofen could be achieved by reacting the recovered ketoprofen with 10% NaOH at 507 kPa for 6h. The recovered n-octyl-d- glucamine could be refined by acid dissolution and alkali adjustment. S-(+)-ketoprofen can be obtained with high optical purity and yield, showing that the present process is a practical and efficient one which can be used in industrial scale for preparation of S-(+)-ketoprofen.
文摘The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and fully characterized by nuclear magnetic resonance,mass spectrometry,Fourier transform infrared spectroscopy,ultraviolet-visible spectroscopy,and specific rotation.The proposed metalloporphyrin catalysts were synthesized with either 1,1'-bi-2-naphthol or L-phenylalanine,which have different chirality,and then applied to the coupling of propylene oxide and CO2 for generating chiral cyclic carbonates with good enantioselectivity under extremely mild conditions in the presence of tetrabutyl ammonium chloride as a co-catalyst.The good enantioselectivity in the cycloaddition reaction is attributed to a synergistic interplay between the chiral porphyrin catalysts and the substrate.The mechanism and enantioselectivity of the asymmetric cycloaddition reaction is discussed.
基金ACKNOWLEDGEMENT This work was supported by National Natural Science Foundation of China （Grant No. 61231008）, National Basic Research Program of China （973 Program） （Grant No. 2009CB320404）, Program for Changjiang Scholars and Innovative Research Team in University （Grant No. IRT0852）, and the 111 Project （Grant No. B08038）.
文摘In the paper,we propose a framework to investigate how to effectively perform traffic flow splitting in heterogeneous wireless networks from a queue point.The average packet delay in heterogeneous wireless networks is derived in a probabilistic manner.The basic idea can be understood via treating the integrated heterogeneous wireless networks as different coupled and parallel queuing systems.The integrated network performance can approach that of one queue with maximal the multiplexing gain.For the purpose of illustrating the effectively of our proposed model,the Cellular/WLAN interworking is exploited.To minimize the average delay,a heuristic search algorithm is used to get the optimal probability of splitting traffic flow.Further,a Markov process is applied to evaluate the performance of the proposed scheme and compare with that of selecting the best network to access in terms of packet mean delay and blocking probability.Numerical results illustrate our proposed framework is effective and the flow splitting transmission can obtain more performance gain in heterogeneous wireless networks.
基金Supported by the National Natural Science Foundation of China(21206107)the National High-tech R&D Program of China(2012AA03A609)Program for Changjiang Scholars and Innovative Research Team in University(IRT1161)
文摘Biomacromolecules including protein and nucleic acids are considered as promising chiral selectors in the fields of enantioselective separation, owing to their inherent chirality, polymorphous structures, stable physicochemical properties, good biocompatibility as well as susceptible modification and regulation. In this review, firstly,enantioselective recognition mechanism of proteins and nucleic acids toward different enantiomers is discussed,as well as their potential applications on the chiral separation of racemic compounds. Secondly, preparative enantioseparation adopting biomolecule-modified hybrid materials including porous microspheres, magnetic nanoparticles and affinity membranes, are introduced respectively. Finally, novel chiroptical materials constructed on the basis of chiral induction, transfer, amplification and transcription, are recognized as promising candidates in future applications.
文摘Direct chiral separation of azelnidipine enantiomers with Pirkle-type Sumichiral OA-2500 column was studied by normal phase and reserve phase conditions. By normal phase, azelnidipine enantiomers were well separated with Rs as 4.0 using hexane–ethanol （90：10, v/v） as mobile phase, and Rs as 2.7 in shorter time （no more than 13 min） using hexane–ethanol （60：40, v/v） as the recommended mobile phase. They were only partially separated by reverse phase using methanol or methanol containing 0.05 mol/L ammonium acetate. Using same chiral column, the chiral separation of other dihydropyridine calcium antagonist analogues almodipine and nimodipine were also studied and showed partial chiral separation in normal phase.
基金Guangzhou mega Projects of Science Research in 2009(Grant No.2009A1-E011-7)
文摘Effective enantioseparation of Naftopidil and its derivatives by HPLC was accomplished using several different polysaccharide-based chiral stationary phases（CSPs）.In normal-phase mode,the compounds were eluted on four coated-and two immobilized-columns with the mixture of n-hexane,isopropanol and diethylamine（DEA）.Polysaccharide tris（3,5- dimethylphenyl carbamate） was shown to be the best enantiomer selector.In addition,the immobilized column packed with Chiralpak IA or IB was applied under polar-organic and reversed-phase conditions,both of which exhibited excellent enantioselectivity for Naftopidil and its derivatives.Furthermore,the underlying possible chiral recognition mechanisms were discussed.
