采用高温有机液相法,以醋酸镍为前驱体,用三辛基膦作表面活性剂,用连续注入的方式,在不同的反应阶段加入三辛基膦,制备了Ni_3C@Ni核壳型纳米粒子(NPs)。催化性能研究表明,该核壳结构的活化能ΔE=60 k J/mol,低于单一镍纳米粒子(ΔENi=65...采用高温有机液相法,以醋酸镍为前驱体,用三辛基膦作表面活性剂,用连续注入的方式,在不同的反应阶段加入三辛基膦,制备了Ni_3C@Ni核壳型纳米粒子(NPs)。催化性能研究表明,该核壳结构的活化能ΔE=60 k J/mol,低于单一镍纳米粒子(ΔENi=65 k J/mol)的活化能;磁学性能研究表明,该纳米粒子为铁磁性,在300 K时的矫顽力为65.2 Oe,饱和磁感应强度为0.25 emu/g。退火后的产物为镍/氧化镍的核壳结构。电化学性能研究表明,该核壳结构具有较为稳定的循环可逆性,首次充放电容量较高,可作为新型锂离子电池负极材料。展开更多
Methods for determining nine low molecular weight organic acids in root exudates were developed by using reversed phase high performance liquid chromatography with UV (ultraviolet) detection at 214 nm. The mobile ph...Methods for determining nine low molecular weight organic acids in root exudates were developed by using reversed phase high performance liquid chromatography with UV (ultraviolet) detection at 214 nm. The mobile phase was 18 mmol L -1 kH 2PO 4 adjusted to pH 2.25 with phosphoric acid and the flow rate was 0.3 mL min -1 . The analytical column was a reversed phase silica based C 18 column (Shim pack CLC ODS). The root exudates were collected through submerging the whole root system into aerated deionized water for 2 hours. The filtered exudate solutions were concentrated to dryness by rotary evaporation at 40 °C, dissolved in 10 mL mobile phase. The chromatographic conditions of organic acid determination were analyzed. The results showed that there was a high selectivity and sensitivity in the organic acid determination by reversed phase high performance liquid chromatography. Coefficients of variation for organic acid determination were lower than 10% except lactic acid. The recoveries were consistently between 80.1% to 108.3%. Detection limits were approximately 0.05 to 4.5 mg L -1 for organic acids except succinic acid with the detection limit of 7.0 mg L -1 . Phosphorus deficiency may contribute to the release of organic acids in soybean root exudates especially malic, lactic and citric acids.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
Abstract Asphaltene, from co-processing of coal and petroleum residues is one of the most precious and complex molecular mixtures existing, with tremendous economic relevance. Asphaltene was separated by Soxhlet extra...Abstract Asphaltene, from co-processing of coal and petroleum residues is one of the most precious and complex molecular mixtures existing, with tremendous economic relevance. Asphaltene was separated by Soxhlet extraction with methylbenzene and then divided into three parts by distillation. Gas chromatography （GC） and high-performance liquid chromatography （HPLC） were coupled with quadrupole time-of-flight mass spectrometry （Q-TOF MS） to separate and characterize organic nitrogen species in the distillates of asphaltene at molecular level. Molecular mass of compounds was mainly distributed from 150 to 600 ~t. Number of rings plus double bonds （rdb） and synchronous fluorescence spectra indicated that most of the organonitrogen compounds （NPAC） contained heterocyclic aromatic rings, including pyridines, anilines, quinolins, pyrroles, carbazoles and indoles plus various alkyl groups. Constant-wavelength synchronous fluo- rescence spectrometry （CWSFS） indicated NPAC with 2-3 rings were the main structures of organonitrogen compounds and the corresponding structural information was proposed. Some organic nitrogen isomers were separated and identified by atmospheric pressure chemical ionization （APCI） GC-Q-TOF MS and electrospray ionization （ESI） HPLC-Q-TOF MS. The methodology applied here contained chromatographic injection of the diluted sample using conventional columns sets and Data Analysis 4.2 software. Identifying molecular structures provides a foundation to understand all aspects of coal- derived asphaltene, enabling a first-principles approach to optimize resource utilization.展开更多
Pinellia ternata has a long history of medicinal use in China, Japan, and Korea. Herein, we present a sensitive, selective, and robust HPLC method for the simultaneous determination of 6 organic acids （oxalic acid, m...Pinellia ternata has a long history of medicinal use in China, Japan, and Korea. Herein, we present a sensitive, selective, and robust HPLC method for the simultaneous determination of 6 organic acids （oxalic acid, malic acid, citric acid, formic acid, acetic acid, and succinic acid）, 3 nucleosides （uridine, guanosine hydrate, and adenosine）, and ephedrine in P. ternata. The Rhizoma pinelliae samples were collected from different parts of Southwest China, and the 10 constituents were detected at a wavelength of 210 nm. Chromatographic separation was achieved on a Boston Green ODS reversed-phase column along with a gradient mobile phase of methanol and phosphate buffer （pH 2.3, 10 mmol/L, v/v） at a flow rate of 1.0 mL/min. The range of recovery was between 90.8% and 101.9%, and the calibration curves showed high linearity. The relative standard deviations of the new method were less than 3.0% for intra- and inter-day analyses. All samples were stable for at least 48 h. The abundance of the 10 compounds were dependent on their specific locations. The new HPLC method is a powerful technique for the quality control ofP. Ternata.展开更多
Epitaxial heterostructures based on organicinorganic hybrid perovskites and two-dimensional materials hold great promises in optoelectronics, but they have been prepared only via solid-state methods that restricted th...Epitaxial heterostructures based on organicinorganic hybrid perovskites and two-dimensional materials hold great promises in optoelectronics, but they have been prepared only via solid-state methods that restricted their practical applications. Herein, we report cubic-phased MAPbBr3(MA=CH3NH3+) nanocrystals were epitaxially deposited on trigonal/hexagonal-phased MoS2 nanosheets in solution by facilely tuning the solvation conditions. In spite of the mismatched lattice symmetry between the square MAPbBr3(001) overlayer and the hexagonal MoS2(001) substrate, two different aligning directions with lattice mismatch of as small as 1% were observed based on the domainmatching epitaxy. This was realized most likely due to the flexible nature and absence of surface dangling bonds of MoS2 nanosheets. The formation of the epitaxial interface affords an effective energy transfer from MAPbBr3 to MoS2, and as a result, paper-based photodetectors facilely fabricated from these solution-dispersible heterostructures showed better performance compared to those based on MoS2 or MAPbBr3 alone. In addition to the improved energy transfer and light adsorption, the use of MoS2 nanosheets provided flexible and continuous substrates to connect the otherwise discrete MAPbBr3 nanocrystals and achieved the better film forming ability. Our work suggests that the scalable preparation of heterostructures based on organic-inorganic hybrid perovskites and 2D materials via solution-phase epitaxy may bring about more opportunities for expanding their optoelectronic applications.展开更多
文摘采用高温有机液相法,以醋酸镍为前驱体,用三辛基膦作表面活性剂,用连续注入的方式,在不同的反应阶段加入三辛基膦,制备了Ni_3C@Ni核壳型纳米粒子(NPs)。催化性能研究表明,该核壳结构的活化能ΔE=60 k J/mol,低于单一镍纳米粒子(ΔENi=65 k J/mol)的活化能;磁学性能研究表明,该纳米粒子为铁磁性,在300 K时的矫顽力为65.2 Oe,饱和磁感应强度为0.25 emu/g。退火后的产物为镍/氧化镍的核壳结构。电化学性能研究表明,该核壳结构具有较为稳定的循环可逆性,首次充放电容量较高,可作为新型锂离子电池负极材料。
文摘Methods for determining nine low molecular weight organic acids in root exudates were developed by using reversed phase high performance liquid chromatography with UV (ultraviolet) detection at 214 nm. The mobile phase was 18 mmol L -1 kH 2PO 4 adjusted to pH 2.25 with phosphoric acid and the flow rate was 0.3 mL min -1 . The analytical column was a reversed phase silica based C 18 column (Shim pack CLC ODS). The root exudates were collected through submerging the whole root system into aerated deionized water for 2 hours. The filtered exudate solutions were concentrated to dryness by rotary evaporation at 40 °C, dissolved in 10 mL mobile phase. The chromatographic conditions of organic acid determination were analyzed. The results showed that there was a high selectivity and sensitivity in the organic acid determination by reversed phase high performance liquid chromatography. Coefficients of variation for organic acid determination were lower than 10% except lactic acid. The recoveries were consistently between 80.1% to 108.3%. Detection limits were approximately 0.05 to 4.5 mg L -1 for organic acids except succinic acid with the detection limit of 7.0 mg L -1 . Phosphorus deficiency may contribute to the release of organic acids in soybean root exudates especially malic, lactic and citric acids.
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.
基金Acknowledgements The authors gratefully acknowledge the financial support of this work by the National Natural Science Foundation of China （No. U1510122）. The authors declare that the experiments comply with the current laws of China.
文摘Abstract Asphaltene, from co-processing of coal and petroleum residues is one of the most precious and complex molecular mixtures existing, with tremendous economic relevance. Asphaltene was separated by Soxhlet extraction with methylbenzene and then divided into three parts by distillation. Gas chromatography （GC） and high-performance liquid chromatography （HPLC） were coupled with quadrupole time-of-flight mass spectrometry （Q-TOF MS） to separate and characterize organic nitrogen species in the distillates of asphaltene at molecular level. Molecular mass of compounds was mainly distributed from 150 to 600 ~t. Number of rings plus double bonds （rdb） and synchronous fluorescence spectra indicated that most of the organonitrogen compounds （NPAC） contained heterocyclic aromatic rings, including pyridines, anilines, quinolins, pyrroles, carbazoles and indoles plus various alkyl groups. Constant-wavelength synchronous fluo- rescence spectrometry （CWSFS） indicated NPAC with 2-3 rings were the main structures of organonitrogen compounds and the corresponding structural information was proposed. Some organic nitrogen isomers were separated and identified by atmospheric pressure chemical ionization （APCI） GC-Q-TOF MS and electrospray ionization （ESI） HPLC-Q-TOF MS. The methodology applied here contained chromatographic injection of the diluted sample using conventional columns sets and Data Analysis 4.2 software. Identifying molecular structures provides a foundation to understand all aspects of coal- derived asphaltene, enabling a first-principles approach to optimize resource utilization.
基金National Science & Technology Project of China(Grant No.2011BAI13B03)
文摘Pinellia ternata has a long history of medicinal use in China, Japan, and Korea. Herein, we present a sensitive, selective, and robust HPLC method for the simultaneous determination of 6 organic acids （oxalic acid, malic acid, citric acid, formic acid, acetic acid, and succinic acid）, 3 nucleosides （uridine, guanosine hydrate, and adenosine）, and ephedrine in P. ternata. The Rhizoma pinelliae samples were collected from different parts of Southwest China, and the 10 constituents were detected at a wavelength of 210 nm. Chromatographic separation was achieved on a Boston Green ODS reversed-phase column along with a gradient mobile phase of methanol and phosphate buffer （pH 2.3, 10 mmol/L, v/v） at a flow rate of 1.0 mL/min. The range of recovery was between 90.8% and 101.9%, and the calibration curves showed high linearity. The relative standard deviations of the new method were less than 3.0% for intra- and inter-day analyses. All samples were stable for at least 48 h. The abundance of the 10 compounds were dependent on their specific locations. The new HPLC method is a powerful technique for the quality control ofP. Ternata.
基金supported by the National Natural Science Foundation of China (51322202) the Young 1000 Talents Global Recruitment Program of China+2 种基金the financial support from Macao Science and Technology Development Fund (FDCT-116/2016/A3 and FDCT-091/2017/A2)Research Grant (SRG2016-00087-FST) from the University of Macao, the Natural Science Foundation of China (91733302, 61605073 and 2015CB932200)the Young 1000 Talents Global Recruitment Program of China
文摘Epitaxial heterostructures based on organicinorganic hybrid perovskites and two-dimensional materials hold great promises in optoelectronics, but they have been prepared only via solid-state methods that restricted their practical applications. Herein, we report cubic-phased MAPbBr3(MA=CH3NH3+) nanocrystals were epitaxially deposited on trigonal/hexagonal-phased MoS2 nanosheets in solution by facilely tuning the solvation conditions. In spite of the mismatched lattice symmetry between the square MAPbBr3(001) overlayer and the hexagonal MoS2(001) substrate, two different aligning directions with lattice mismatch of as small as 1% were observed based on the domainmatching epitaxy. This was realized most likely due to the flexible nature and absence of surface dangling bonds of MoS2 nanosheets. The formation of the epitaxial interface affords an effective energy transfer from MAPbBr3 to MoS2, and as a result, paper-based photodetectors facilely fabricated from these solution-dispersible heterostructures showed better performance compared to those based on MoS2 or MAPbBr3 alone. In addition to the improved energy transfer and light adsorption, the use of MoS2 nanosheets provided flexible and continuous substrates to connect the otherwise discrete MAPbBr3 nanocrystals and achieved the better film forming ability. Our work suggests that the scalable preparation of heterostructures based on organic-inorganic hybrid perovskites and 2D materials via solution-phase epitaxy may bring about more opportunities for expanding their optoelectronic applications.
