Metal and nano-ceramic nanocomposite coatings were prepared on the gray cast iron surface by the electrodeposition method. The Ni-Co was used as the metal matrix,and nano-Al2O3 was chosen as the second-phase particula...Metal and nano-ceramic nanocomposite coatings were prepared on the gray cast iron surface by the electrodeposition method. The Ni-Co was used as the metal matrix,and nano-Al2O3 was chosen as the second-phase particulates. To avoid poor inter-face bonding and stress distribution,the gradient structure of biology materials was found as the model and therefore the gradient composite coating was prepared. The morphology of the composite coatings was flatter and the microstructure was denser than that of pure Ni-Co coatings. The composite coatings were prepared by different current densities,and the 2-D and 3-D morphologies of the surface coatings were observed. The result indicated that the 2-D structure became rougher and the 3-D surface density of apices became less when the current density was increased. The content of nanoparticulates reached a maximum value at the current density of 40mA·cm^-2,at the same time the properties including microhardness and wear-resistance were analyzed. The microhardness reached a maximum value and the wear volume was also less at the current density of 40mA·cm^-2. The reason was that nano-Al2O3 particles caused dispersive strengthening and grain refining.展开更多
Nanoparticles are increasingly being used to improve the friction and wear performance of polymers. In this study, we investigated the tribological behavior and energy dissipation characteristics of nano-Al_2O_3-reinf...Nanoparticles are increasingly being used to improve the friction and wear performance of polymers. In this study, we investigated the tribological behavior and energy dissipation characteristics of nano-Al_2O_3-reinforced polytetrafluoroethylenepolyphenylene sulfide(PTFE-PPS) composites in a sliding system. The tribological behaviors of the composites were evaluated under different normal loads(100–300 N) at a high linear velocity(2 m/s) using a block-on-ring tester. Addition of the nano-Al_2O_3 filler improved the antiwear performance of the PTFE-PPS composites, and the friction coefficient increased slightly. The lowest wear rate was obtained when the nano-Al_2O_3 content was 3%(volume fraction). Further, the results indicated a linear correlation between wear and the amount of energy dissipated, even though the wear mechanism changed with the nano-Al_2O_3 content, independent of the normal load applied.展开更多
Non-enzymatic biosensors based on mixed transition metal oxides are deemed as the most promising devices due to their high sensitivity,selectivity,wide concentration range,low detection limits,and excellent recyclabil...Non-enzymatic biosensors based on mixed transition metal oxides are deemed as the most promising devices due to their high sensitivity,selectivity,wide concentration range,low detection limits,and excellent recyclability.Spinel NiCo2O4 mixed oxides have drawn considerable attention recently due to their outstanding advantages including large specific surface area,high permeability,short electron,and ion diffusion pathways.Because of the rapid development of non-enzyme biosensors,the current state of methods for synthesis of pure and composite/hybrid NiCo2P4 materials and their subsequent electrochemical biosensing applications are systematically and comprehensively reviewed herein.Comparative analysis reveals better electrochemical sensing of bioanalytes by one-dimensional and two-dimensional NiCo2O4 nano-/microstructures than other morphologies.Better biosensing efficiency of NiCo2O4 as compared to corresponding individual metal oxides,viz.NiO and Co3O4,is attributed to the close intrinsic-state redox couples of Ni3+/Ni2+(0.58 V/0.49 V) and Co3+/Co2+(0.53 V/0.51 V).Biosensing performance of NiCo2O4 is also significantly improved by making the composites of NiCo2O4 with conducting carbonaceous materials like graphene,reduced graphene oxide,carbon nanotubes(single and multi-walled),carbon nanofibers;conducting polymers like polypyrrole(PPy),polyaniline(PANI);metal oxides NiO,Co3O4,SnO2,MnO2;and metals like Au,Pd,etc.Various factors affecting the morphologies and biosensing parameters of the nano-/microstructured NiCo2O4 are also highlighted.Finally,some drawbacks and future perspectives related to this promising field are outlined.展开更多
An efficient and versatile practical protocol for the chemoselective N-tert-butoxycarbonylation of amines using Nano-γ-Fe2O3 and (BOC)2O. Nano-γ-Fe2O3 was applied as an efficient, green, heterogeneous and reusable c...An efficient and versatile practical protocol for the chemoselective N-tert-butoxycarbonylation of amines using Nano-γ-Fe2O3 and (BOC)2O. Nano-γ-Fe2O3 was applied as an efficient, green, heterogeneous and reusable catalyst at ambient temperature;the method is general for the preparation of N-Boc derivatives of aliphatic, heterocyclic, aromatic as well as amino acid derivatives.展开更多
Selective laser sintering （SLS） is a new process to prepare the polystyrene （PS）/Al2O3 nanocomposites. In this paper, with different laser power and other processing parameters unchanged, the morphology, density a...Selective laser sintering （SLS） is a new process to prepare the polystyrene （PS）/Al2O3 nanocomposites. In this paper, with different laser power and other processing parameters unchanged, the morphology, density and mechanical properties of the sintered specimens were investigated. It was found that nano-sized inorganic particles are uniformly located in the PS matrix and the maximum density of the sintered specimens with pure PS powder reaches 1.07 g/cm^3, higher than 1.04 g/cm^3 that of the sintered specimens with mixture powder. Due to strengthening and toughness of the nano-sized Al2O3 inorganic particles, the maximum notched impact strength and tensile strength of the sintered part mixed with nano-sized inorganic particles are improved greatly from 7.5 to 12.1 kJ/m^2 and from 6.5 to 31.2 MPa, respectively, under the same sintering condition.展开更多
Aluminum-matrix boron carbide (B4Cp/Al) is a kind of neutron absorbing material widely used in nuclear spent fuel storage. In order to improve the tensile property of B4Cp/Al composites, a new type of nano-Al2O3 parti...Aluminum-matrix boron carbide (B4Cp/Al) is a kind of neutron absorbing material widely used in nuclear spent fuel storage. In order to improve the tensile property of B4Cp/Al composites, a new type of nano-Al2O3 particle (Al2O3np) reinforced B4Cp/Al + Al2O3np composites were prepared by powder metallurgy method. The Monte Carlo particle transport program (MCNP) was used to determine the influence of Al2O3np on the thermal neutron absorptivity of composites. The universal material testing machine and scanning electron microscope (SEM) were used to study the mechanical properties, microstructure and fracture morphology of B4Cp/Al composites. The results indicated that the neutron absorption properties of B4Cp/Al composites were not affected by the addition of nano-Al2O3 particles in the range of 1 wt%-15 wt%. The addition of Al2O3np can obviously reduce the grain size of B4Cp/Al matrix metals thus improve the tensile strength of the composites. The addition threshold of Al2O3np is about 2.5 wt%. Both B4Cp and Al2O3np change the fracture characteristics of the composites from toughness to brittleness, and the latter is more important.展开更多
SiO2-Al2O3/EP-PU nanocomposites, which contained polyurethane(PU) flexible chain, were prepared via epoxy resin, PU and modified silica and alumina particles. Silica and alumina particles were modified by coupling age...SiO2-Al2O3/EP-PU nanocomposites, which contained polyurethane(PU) flexible chain, were prepared via epoxy resin, PU and modified silica and alumina particles. Silica and alumina particles were modified by coupling agents KH-560 and KH550, respectively. EP-PU was used as matrix, PU as toughening agent, Si O2-Al2O3 as filled and MTHPA as curing agent. The mass ratio of PU was 30% in this system. The chemical structure of the products was confirmed by FT-IR measurements, the morphological structure of fracture surface and the surface of the hybrid materials were observed by scanning electron microscope(SEM) and transmission electron microscope(TEM), and shearing strength and breakdown field were measured, respectively. When the mass fraction of inorganic component was 10% and the mass ratio of Si O2 to Al2O3 was 4.5:5.5, shearing strength of Si O2-Al2O3/EP-PU was 28.5 MPa and breakdown field was 15 k V/mm, the data could meet the property requirement of insulating material.展开更多
CO methanation over the 20% nickel catalyst prepared by impregnation-precipitation method on different supports of commercial γ-Al2O3, TiO2, SiO2 and nano-γ-Al2O3* was investigated. The nano-γ-Al2O3* support was pu...CO methanation over the 20% nickel catalyst prepared by impregnation-precipitation method on different supports of commercial γ-Al2O3, TiO2, SiO2 and nano-γ-Al2O3* was investigated. The nano-γ-Al2O3* support was pulverized using a ball milling method. Catalyst characterization was done using the methods of BET, XRD, SEM, ICP-OES methods. Carbon monoxide methanation process was carried out at the temperature of 350°C in pressure of 3 bar of H2:CO syngas with the molar ratio of 3:1 and with the GHSV of 3000 h-1 in a fixed bed reactor. The initial temperature of methane formation increased according to the order of Ni/γ-Al2O3* 2 γ-TiO2 γ-Al2O3. The Ni/γ-Al2O3*, which was prepared on the surface of nano milled γ-Al2O3 support, produced methane from the lowest temperature of 178°C to 350°C in CO methanation. The Ni/γ-Al2O3* catalyst gave the highest amount of methane (0.1224 mmol/g-cat) for 1 h methanation among other catalysts. XRD and SEM analysis proved that NiO particles in the Ni/γ-Al2O3* were finely distributed, and their sizes were smaller compared to those in the traditional one. The pulverization of γ-Al2O3 improved the dispersion of catalytic active nickel species inside porosity of the support leading to the improvement of its catalytic performance for CO methanation.展开更多
Based on the two-step nucleation mechanism, a multi-step thermodynamic model for alumina inclusion for- mation during aluminum deoxidation process was proposed in Fe-O-Al melt. Thermodynamic properties of metastable i...Based on the two-step nucleation mechanism, a multi-step thermodynamic model for alumina inclusion for- mation during aluminum deoxidation process was proposed in Fe-O-Al melt. Thermodynamic properties of metastable intermediates including （Al2O3）n clusters for prenucleation and α-Al2O3 nanoparticle for growth process were calculated using density functional theory. Furthermore, Gibbs free energy change of forming the intermediate by reaction between the dissolved aluminum （Al） and oxygen （O） in the melt was calculated. The results indicated that the thermodynamics of （Al2O3）n at steelmaking temperature are dependent on their structures, while that of α-Al2O3 nanoparticle are dependent on their size. The nuclei of α-Al2O3 which was originated from （Al2O3）n aggregated under a high supersaturation ratio of Al and O（Rs） in the melt. There existing excess oxygen because of the low Rs, but the secondary inclusions will be formed during the cooling process due to the excess oxygen. The nuclei lager than 20 nm can grow up spontaneously and instantaneously into primary inclusions because of thermodynamic drive. It is difficult to control the size of α-Al2O3 to be less than 20 nm, in the aluminum deoxidation process of the current conditions of steelmaking.展开更多
A two-dimensional LC(2D-LC)method was coupled to an ion mobility-high-resolution mass spectrometer(IM-MS),which enables the separation of complex samples in four dimensions[2D-LC,ion mobility(IM)and mass spectrometry(...A two-dimensional LC(2D-LC)method was coupled to an ion mobility-high-resolution mass spectrometer(IM-MS),which enables the separation of complex samples in four dimensions[2D-LC,ion mobility(IM)and mass spectrometry(MS)].This approach works as a continuous multiheart-cutting LC-system,using a long modulation time of four minutes,in comparison to comprehensive two-dimensional liquid chromatography,which allows the complete transfer of most of the first dimension peaks to the second dimension column without fractionation.Hence,each compound delivers only one peak in the second dimension,which simplifies the data handling even when ion mobility as a third and mass spectrometry as a fourth dimension are introduced.The analysis of different complex samples,such as a plant extract from Hediotys diffusa and Scutellaria barbata,a waste water inflow,and a biocoal sample,was shown.The results of the four-dimensional separation method demonstrate that with the same column combination and the same solvents and gradients,that means without method optimization,totally different samples can be separated with outstanding separation power.Each sample was spiked with cyclophosphamide and ifosfamide and the ion suppression was determined by comparison of the peak area in the complex samples and in pure water after analysis of these samples with a 1D-LC and a 2D-LC approach.It is shown that the 2D-LC method allows an external calibration for the spiked compounds in the plant and waste water sample because of the higher separation power in comparison with 1D-LC.展开更多
In this work,a novel kind of particulate capillary precolumns with double-end polymer monolithic frits has been developed.Firstly,the polymer monolithic frit at one end was prepared via photo-initiated polymerization ...In this work,a novel kind of particulate capillary precolumns with double-end polymer monolithic frits has been developed.Firstly,the polymer monolithic frit at one end was prepared via photo-initiated polymerization of a mixture of lauryl methacrylate and ethyleneglycol dimethacrylate with 1-propanol and 1,4-butanediol as porogens and 2,2-dimethoxy-2-phenylacetophenone as a photo-initiator in UV transparent coating capillary（100 μm i.d.）.Subsequently,C18 particles（5 μm,100 A） were packed into the capillary,and sealed with the polymer monolithic frit at another end.To prevent the reaction of monomers and C18 particles,the packed C18 particles were masked during UV exposure.The loading capacity of such a precolumn was determined to be about 9 μg by frontal analysis with a synthetic peptide APGDR1 YVHPF as a model sample.Furthermore,two parallel precolumns were incorporated into a two-dimensional nano-liquid chromatography（2D nano-LC） system with dual capillary trap columns for peptide trapping and concentration.Compared to 2D nano-LC system with a single trap column,such two dimensional separations could be operated simultaneously to improve the analysis throughput.All these results demonstrated that such capillary precolumns with double frits would be promising for high-throughput proteome analysis.展开更多
基金the National Natural Science Foundation of China (No50635030)the National Basic Research of China (No2007CB616913)the Program for New Century Excellent Talents in University (2005)
文摘Metal and nano-ceramic nanocomposite coatings were prepared on the gray cast iron surface by the electrodeposition method. The Ni-Co was used as the metal matrix,and nano-Al2O3 was chosen as the second-phase particulates. To avoid poor inter-face bonding and stress distribution,the gradient structure of biology materials was found as the model and therefore the gradient composite coating was prepared. The morphology of the composite coatings was flatter and the microstructure was denser than that of pure Ni-Co coatings. The composite coatings were prepared by different current densities,and the 2-D and 3-D morphologies of the surface coatings were observed. The result indicated that the 2-D structure became rougher and the 3-D surface density of apices became less when the current density was increased. The content of nanoparticulates reached a maximum value at the current density of 40mA·cm^-2,at the same time the properties including microhardness and wear-resistance were analyzed. The microhardness reached a maximum value and the wear volume was also less at the current density of 40mA·cm^-2. The reason was that nano-Al2O3 particles caused dispersive strengthening and grain refining.
基金Project(51165022)supported by the National Natural Science Foundation of ChinaProject(20122117)supported by the Lanzhou Science and Technology Bureau Foundation,ChinaProject(1310RJZA036)supported by the Natural Science Foundation of Gansu Province,China
文摘Nanoparticles are increasingly being used to improve the friction and wear performance of polymers. In this study, we investigated the tribological behavior and energy dissipation characteristics of nano-Al_2O_3-reinforced polytetrafluoroethylenepolyphenylene sulfide(PTFE-PPS) composites in a sliding system. The tribological behaviors of the composites were evaluated under different normal loads(100–300 N) at a high linear velocity(2 m/s) using a block-on-ring tester. Addition of the nano-Al_2O_3 filler improved the antiwear performance of the PTFE-PPS composites, and the friction coefficient increased slightly. The lowest wear rate was obtained when the nano-Al_2O_3 content was 3%(volume fraction). Further, the results indicated a linear correlation between wear and the amount of energy dissipated, even though the wear mechanism changed with the nano-Al_2O_3 content, independent of the normal load applied.
文摘Non-enzymatic biosensors based on mixed transition metal oxides are deemed as the most promising devices due to their high sensitivity,selectivity,wide concentration range,low detection limits,and excellent recyclability.Spinel NiCo2O4 mixed oxides have drawn considerable attention recently due to their outstanding advantages including large specific surface area,high permeability,short electron,and ion diffusion pathways.Because of the rapid development of non-enzyme biosensors,the current state of methods for synthesis of pure and composite/hybrid NiCo2P4 materials and their subsequent electrochemical biosensing applications are systematically and comprehensively reviewed herein.Comparative analysis reveals better electrochemical sensing of bioanalytes by one-dimensional and two-dimensional NiCo2O4 nano-/microstructures than other morphologies.Better biosensing efficiency of NiCo2O4 as compared to corresponding individual metal oxides,viz.NiO and Co3O4,is attributed to the close intrinsic-state redox couples of Ni3+/Ni2+(0.58 V/0.49 V) and Co3+/Co2+(0.53 V/0.51 V).Biosensing performance of NiCo2O4 is also significantly improved by making the composites of NiCo2O4 with conducting carbonaceous materials like graphene,reduced graphene oxide,carbon nanotubes(single and multi-walled),carbon nanofibers;conducting polymers like polypyrrole(PPy),polyaniline(PANI);metal oxides NiO,Co3O4,SnO2,MnO2;and metals like Au,Pd,etc.Various factors affecting the morphologies and biosensing parameters of the nano-/microstructured NiCo2O4 are also highlighted.Finally,some drawbacks and future perspectives related to this promising field are outlined.
文摘An efficient and versatile practical protocol for the chemoselective N-tert-butoxycarbonylation of amines using Nano-γ-Fe2O3 and (BOC)2O. Nano-γ-Fe2O3 was applied as an efficient, green, heterogeneous and reusable catalyst at ambient temperature;the method is general for the preparation of N-Boc derivatives of aliphatic, heterocyclic, aromatic as well as amino acid derivatives.
文摘Selective laser sintering （SLS） is a new process to prepare the polystyrene （PS）/Al2O3 nanocomposites. In this paper, with different laser power and other processing parameters unchanged, the morphology, density and mechanical properties of the sintered specimens were investigated. It was found that nano-sized inorganic particles are uniformly located in the PS matrix and the maximum density of the sintered specimens with pure PS powder reaches 1.07 g/cm^3, higher than 1.04 g/cm^3 that of the sintered specimens with mixture powder. Due to strengthening and toughness of the nano-sized Al2O3 inorganic particles, the maximum notched impact strength and tensile strength of the sintered part mixed with nano-sized inorganic particles are improved greatly from 7.5 to 12.1 kJ/m^2 and from 6.5 to 31.2 MPa, respectively, under the same sintering condition.
基金Funded by Natural National Science Foundation of China(NSFC)(No.11305149)National High-Tech R&D Program(863 Program)(No.2013AA030704)。
文摘Aluminum-matrix boron carbide (B4Cp/Al) is a kind of neutron absorbing material widely used in nuclear spent fuel storage. In order to improve the tensile property of B4Cp/Al composites, a new type of nano-Al2O3 particle (Al2O3np) reinforced B4Cp/Al + Al2O3np composites were prepared by powder metallurgy method. The Monte Carlo particle transport program (MCNP) was used to determine the influence of Al2O3np on the thermal neutron absorptivity of composites. The universal material testing machine and scanning electron microscope (SEM) were used to study the mechanical properties, microstructure and fracture morphology of B4Cp/Al composites. The results indicated that the neutron absorption properties of B4Cp/Al composites were not affected by the addition of nano-Al2O3 particles in the range of 1 wt%-15 wt%. The addition of Al2O3np can obviously reduce the grain size of B4Cp/Al matrix metals thus improve the tensile strength of the composites. The addition threshold of Al2O3np is about 2.5 wt%. Both B4Cp and Al2O3np change the fracture characteristics of the composites from toughness to brittleness, and the latter is more important.
基金Project(2012RFJGG006)supported by the Harbin Science and Technology Innovation Foundation,China
文摘SiO2-Al2O3/EP-PU nanocomposites, which contained polyurethane(PU) flexible chain, were prepared via epoxy resin, PU and modified silica and alumina particles. Silica and alumina particles were modified by coupling agents KH-560 and KH550, respectively. EP-PU was used as matrix, PU as toughening agent, Si O2-Al2O3 as filled and MTHPA as curing agent. The mass ratio of PU was 30% in this system. The chemical structure of the products was confirmed by FT-IR measurements, the morphological structure of fracture surface and the surface of the hybrid materials were observed by scanning electron microscope(SEM) and transmission electron microscope(TEM), and shearing strength and breakdown field were measured, respectively. When the mass fraction of inorganic component was 10% and the mass ratio of Si O2 to Al2O3 was 4.5:5.5, shearing strength of Si O2-Al2O3/EP-PU was 28.5 MPa and breakdown field was 15 k V/mm, the data could meet the property requirement of insulating material.
文摘CO methanation over the 20% nickel catalyst prepared by impregnation-precipitation method on different supports of commercial γ-Al2O3, TiO2, SiO2 and nano-γ-Al2O3* was investigated. The nano-γ-Al2O3* support was pulverized using a ball milling method. Catalyst characterization was done using the methods of BET, XRD, SEM, ICP-OES methods. Carbon monoxide methanation process was carried out at the temperature of 350°C in pressure of 3 bar of H2:CO syngas with the molar ratio of 3:1 and with the GHSV of 3000 h-1 in a fixed bed reactor. The initial temperature of methane formation increased according to the order of Ni/γ-Al2O3* 2 γ-TiO2 γ-Al2O3. The Ni/γ-Al2O3*, which was prepared on the surface of nano milled γ-Al2O3 support, produced methane from the lowest temperature of 178°C to 350°C in CO methanation. The Ni/γ-Al2O3* catalyst gave the highest amount of methane (0.1224 mmol/g-cat) for 1 h methanation among other catalysts. XRD and SEM analysis proved that NiO particles in the Ni/γ-Al2O3* were finely distributed, and their sizes were smaller compared to those in the traditional one. The pulverization of γ-Al2O3 improved the dispersion of catalytic active nickel species inside porosity of the support leading to the improvement of its catalytic performance for CO methanation.
基金financially supported by the National Natural Science Foundation of China (No. 51004054)Foundation from the Liaoning Province Education Department (No. L2013127)
文摘Based on the two-step nucleation mechanism, a multi-step thermodynamic model for alumina inclusion for- mation during aluminum deoxidation process was proposed in Fe-O-Al melt. Thermodynamic properties of metastable intermediates including （Al2O3）n clusters for prenucleation and α-Al2O3 nanoparticle for growth process were calculated using density functional theory. Furthermore, Gibbs free energy change of forming the intermediate by reaction between the dissolved aluminum （Al） and oxygen （O） in the melt was calculated. The results indicated that the thermodynamics of （Al2O3）n at steelmaking temperature are dependent on their structures, while that of α-Al2O3 nanoparticle are dependent on their size. The nuclei of α-Al2O3 which was originated from （Al2O3）n aggregated under a high supersaturation ratio of Al and O（Rs） in the melt. There existing excess oxygen because of the low Rs, but the secondary inclusions will be formed during the cooling process due to the excess oxygen. The nuclei lager than 20 nm can grow up spontaneously and instantaneously into primary inclusions because of thermodynamic drive. It is difficult to control the size of α-Al2O3 to be less than 20 nm, in the aluminum deoxidation process of the current conditions of steelmaking.
文摘A two-dimensional LC(2D-LC)method was coupled to an ion mobility-high-resolution mass spectrometer(IM-MS),which enables the separation of complex samples in four dimensions[2D-LC,ion mobility(IM)and mass spectrometry(MS)].This approach works as a continuous multiheart-cutting LC-system,using a long modulation time of four minutes,in comparison to comprehensive two-dimensional liquid chromatography,which allows the complete transfer of most of the first dimension peaks to the second dimension column without fractionation.Hence,each compound delivers only one peak in the second dimension,which simplifies the data handling even when ion mobility as a third and mass spectrometry as a fourth dimension are introduced.The analysis of different complex samples,such as a plant extract from Hediotys diffusa and Scutellaria barbata,a waste water inflow,and a biocoal sample,was shown.The results of the four-dimensional separation method demonstrate that with the same column combination and the same solvents and gradients,that means without method optimization,totally different samples can be separated with outstanding separation power.Each sample was spiked with cyclophosphamide and ifosfamide and the ion suppression was determined by comparison of the peak area in the complex samples and in pure water after analysis of these samples with a 1D-LC and a 2D-LC approach.It is shown that the 2D-LC method allows an external calibration for the spiked compounds in the plant and waste water sample because of the higher separation power in comparison with 1D-LC.
基金the financial support from National Basic Research Program of China(No.2012CB910604)National Natural Science Foundation of China(No.20935004)+1 种基金the Creative Research Group Project by NSFC(No.21321064)National High Technology Research and Development Program of China (No.2012AA020202)
文摘In this work,a novel kind of particulate capillary precolumns with double-end polymer monolithic frits has been developed.Firstly,the polymer monolithic frit at one end was prepared via photo-initiated polymerization of a mixture of lauryl methacrylate and ethyleneglycol dimethacrylate with 1-propanol and 1,4-butanediol as porogens and 2,2-dimethoxy-2-phenylacetophenone as a photo-initiator in UV transparent coating capillary（100 μm i.d.）.Subsequently,C18 particles（5 μm,100 A） were packed into the capillary,and sealed with the polymer monolithic frit at another end.To prevent the reaction of monomers and C18 particles,the packed C18 particles were masked during UV exposure.The loading capacity of such a precolumn was determined to be about 9 μg by frontal analysis with a synthetic peptide APGDR1 YVHPF as a model sample.Furthermore,two parallel precolumns were incorporated into a two-dimensional nano-liquid chromatography（2D nano-LC） system with dual capillary trap columns for peptide trapping and concentration.Compared to 2D nano-LC system with a single trap column,such two dimensional separations could be operated simultaneously to improve the analysis throughput.All these results demonstrated that such capillary precolumns with double frits would be promising for high-throughput proteome analysis.
