An electrochemical sensor based on self-made nano-porous pseudo carbon paste electrode(nano-PPCPE)has been successfully developed,and used to detect Cd^2+ and Pb^2+.The experimental results showed that the electrochem...An electrochemical sensor based on self-made nano-porous pseudo carbon paste electrode(nano-PPCPE)has been successfully developed,and used to detect Cd^2+ and Pb^2+.The experimental results showed that the electrochemical performance of nanoPPCPE is evidently better than both glassy carbon electrode(GCE)and pure carbon paste electrode(CPE).Then the prepared nano-PPCPE was applied to detect Cd^2+ and Pb^2+in standard solution,the results showed that the electrodes can quantitatively detect trace Cd^2+ and Pb^2+,which has great significance in electrochemical analysis and detection.The linear ranges between the target ions concentration and the D PASV current were from 0.1-3.0 μmol/L,0.05-4.0 μmol/L for Cd^2+ and Pb^2+,respectively.And the detection limits were 0.0780 μmol/L and 0.0292 μmol/L,respectively.Moreover,the preparation of the nano-PPCPE is cheap,simple and has important practical value.展开更多
Clustering of Ti on carbon nanostructures has proved to be an obstacle in their use as hydrogen storage materials. Using density functional theory we show that Ti atoms will not cluster at moderate concentrations when...Clustering of Ti on carbon nanostructures has proved to be an obstacle in their use as hydrogen storage materials. Using density functional theory we show that Ti atoms will not cluster at moderate concentrations when doped into nanoporous graphene. Since each Ti atom can bind up to three hydrogen molecules with an average binding energy of 0.54 eV/H2, this material can be ideal for storing hydrogen under ambient thermodynamic conditions. In addition, nanoporous graphene is magnetic with or without Ti doping, but when it is fully saturated with hydrogen, the magnetism disappears. This novel feature suggests that nanoporous graphene cannot only be used for storing hydrogen, but also as a hydrogen sensor.展开更多
Background Drug-eluting stents represent a major advance in interventional cardiology. However, the current drug- eluting stents have significant limitations. One of the major problems is very late stent thrombosis, w...Background Drug-eluting stents represent a major advance in interventional cardiology. However, the current drug- eluting stents have significant limitations. One of the major problems is very late stent thrombosis, which is likely caused by inflammation and a hypersensitivity reaction related to a polymer on the stent. A polymer-free sirolimus-eluting stent with a unique nano-porous surface has been developed. This study aimed to evaluate this novel polymer-free sirolimus- eluting stent for its efficacy and safety in a pig model. Methods Stents were directly coated with sirolimus (a drug concentration of 2.2 μg/mm2 on the stent surface). The polymer-free sirolimus-eluting stents (PFSES) were compared to standard polymer-coated sirolimus-eluting stents (PCSES) and bare-metal stents (BMS) in 18 pigs. Results At one month the degree of neointimal hyperplasia was similar between the two sirolimus-eluting stent groups and was significantly less compared to BMS ((1.93±0.51) mm2, (1.57±0.69) mm2 vs. (4.45±1.05) mm2, P 〈0.05)At three months, PFSES maintained the low level of neointima ((2.41±0.99) mm2 vs. (4.32±1.16) mm2, P 〈0.05), whereas PCSES had developed significant neointimal proliferation similar to BMS. The inflammation level was significantly higher in PCSES when compared with BMS three months post-implantation (2.50±0.55 vs. 0.83±0.75, P 〈0.05) whereas PFSES showed a low level of inflammation comparable to PCSES (1.33±0.52 vs. 2.50±0.55, P 〈0.05). Conclusion The PFSES is effective and safe. and appears to be suoerior to standard PCSEs.展开更多
Designing efficient and stable non-precious metal HER(hydrogen evolution reaction)electrocatalysts with high large current density adaptability is significant for industrial application of hydrogen production by water...Designing efficient and stable non-precious metal HER(hydrogen evolution reaction)electrocatalysts with high large current density adaptability is significant for industrial application of hydrogen production by water electrolysis.Herein,a facile strategy was developed to construct a multi-phase Ni3 P-Co_(2)P-(Ni-Co)film with self-supporting hierarchically micro/nano-porous structure by using bubble template method electrodeposition of self-supporting micro-porous Ni Co P film,oxygen-free annealing for phase separation producing Ni_(3)P-Ni-Co_(2)P-Co structure,and acid etching for constructing surface nano-porous structure.The effective active sites for HER was significantly increased due to the hierarchically micro/nano-porous structure,which not only enlarged the surface roughness,but enhanced the bubble detachment by improving the hydrophilicity.Meanwhile,the HER electrolysis durability was improved benefiting from the Ni_(3)P-Co_(2)P phases with high corrosion resistance(especially in acid solution)and the self-supporting film structure without binder.Consequently,the Ni Co P-OA-AE film exhibited high HER catalytic performance,which delivered a current density of 10 m A cm^(-2)at a low overpotential of 42.9 and 39.7 m V in 1 M KOH and 0.5 M H_(2)SO_(4),respectively.It also possessed high long-term electrolysis durability,and the cell voltage of water electrolysis using self-supporting porous Ni Co P-OA-AE||Ir O_(2)-Ta_(2)O_(5) electrolyzer at 500 m A cm^(-2)for 250 h in 0.5 M H_(2)SO_(4 )is only 2.9 V.展开更多
High elastic energy density and high-efficiency ionic electromechanical actuators were prepared from aligned activated microwave exfoliated graphite oxide(A-aMEGO)/polymer nano-composites,and the electromechanical per...High elastic energy density and high-efficiency ionic electromechanical actuators were prepared from aligned activated microwave exfoliated graphite oxide(A-aMEGO)/polymer nano-composites,and the electromechanical performance was characterized.The elastic modulus and elastic energy density of the ionic actuators can be tuned over a wide range by varying the polymer(poly(vinylidene fluoride/chlorotrifluoroethylene)[P(VDF-CTFE)])concentration in the nano-composite actuators.The A-aMEGO/P(VDF-CTFE)nano-composite actuators with 35 wt.%of polymer content exhibit an elastic energy density higher than 5 J/cm^(3) and an electromechanical conversion efficiency higher than 3.5%,induced under 4 V.The results show the promise of high-density highly aligned graphene electrodes for high-performance ionic electromechanical transduction devices.展开更多
Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT...Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.展开更多
A novel soft polymer template containing a double-layer structure,which includes a thin layer of polymethylmethacrylate(PMMA)used as a pattern layer and a thicker layer of polydimethylsiloxane(PDMS)used as a back laye...A novel soft polymer template containing a double-layer structure,which includes a thin layer of polymethylmethacrylate(PMMA)used as a pattern layer and a thicker layer of polydimethylsiloxane(PDMS)used as a back layer,was fabricated from a replica molding process.Anodic aluminum oxide(AAO)template was used as the replica mold to be replicated to the polymethylmethacrylate layer by a thermal infiltration process under a vacuum condition.Results indicate that PMMA/PDMS soft templates with different sizes could be easily fabricated from the as-prepared AAO replica mold.The PMMA/PDMS soft templates were then employed to imprint a TiO_2 gel for achieving TiO_2 nano-pore arrays.After the imprinting process,the PDMS layer was firstly peeled off and the PMMA layer was then removed into acetonitrile,which can avoid any demolding problems like damages or distortions.The TiO_2 nano-pore arrays with the crystalline of anatase could be obtained at a heat treatment temperature of 450°C.展开更多
Thermodynamic stability, microvoid distribution and phases transformation of natural pozzolana opal shale(POS) were studied systematically in this work. XRD analysis showed that opal-CT, including microcrystal crist...Thermodynamic stability, microvoid distribution and phases transformation of natural pozzolana opal shale(POS) were studied systematically in this work. XRD analysis showed that opal-CT, including microcrystal cristobalite and tridymite, is a major component of POS. DTA and FT-IR indicated that there were many hydroxyl groups and acid sites on the surface of amorphous SiO2 materials. FE-SEM analysis exhibited amorphous SiO2 particles(opal-A) covering over stacking sequences microcrystal cristobalite and tridymite. Meanwhile, MIP analysis demonstrated that porosity and pore size distribution of POS remained uniform below 600 ℃. Because stable porous microstructure is a key factor in improving photocatalyst activity, POS is suited to preparing highly active supported.展开更多
Yttria-stabilized zirconia and-alumina films were prepared by laser chemical vapor deposition at deposition rates of several hundred micrometers per hour.Moreover,the structural oxide coatings by laser chemical vapor ...Yttria-stabilized zirconia and-alumina films were prepared by laser chemical vapor deposition at deposition rates of several hundred micrometers per hour.Moreover,the structural oxide coatings by laser chemical vapor deposition are reviewed.The laser can significantly accelerate the chemical reaction and grain growth in CVD,yielding high deposition rates.The films contain large amounts of nanopores that act as thermal insulation and are thus promising as coating materials for gas turbine blades of Ni-based superalloys and WC-Co cutting tools.展开更多
The specimens were prepared with high alumina fiber accounting for 0. 5% , 10% or 15% by mass of the total amount of amorphous silica and high alumina fiber, using phenolic resin as binder, and extra-adding 0 or 0. 5%...The specimens were prepared with high alumina fiber accounting for 0. 5% , 10% or 15% by mass of the total amount of amorphous silica and high alumina fiber, using phenolic resin as binder, and extra-adding 0 or 0. 5% ZnO as sunscreen to cut the cost of SiO2 nanoporous insulation board. The hot volume stability and thermal conductivity (flat plate method ) of the specimens were tested and multi-Jimetion simulation equipment was used to study the thermal insulation performante. The results show that: (1) with high alumina fiber addition increasing, the linear shrinkage rate decreases, but thermal eonductivity changes a little; (2) adding ZnO can decrease thermal conductivity obviously; (3)for the specimen with ZnO and 15% of high alumina fiber, its cold face temperature hardly rises during the simulation experiment at 1 000 ℃ for 2 h, and the cold face temperature of the specimen with the smallest thickness of 2 cm doesn't exceed 180 ℃.展开更多
TraPPE force field combined with grand-canonical transition-matrix Monte Carlo simulation were used to investigate the vapor-liquid coexistence curve and critical properties of methane,ethane,propane,and n-butane in s...TraPPE force field combined with grand-canonical transition-matrix Monte Carlo simulation were used to investigate the vapor-liquid coexistence curve and critical properties of methane,ethane,propane,and n-butane in slit pores ranging from 6?to 40?.Long range correction for intermolecular potential in slit pore model was developed,and the fact indicating that its influence on various thermodynamic properties is not negligible was found.The simulation results show that the thermodynamic properties of nano-confined alkanes shift tremendously from the bulk state.The critical temperature under confinement experiences a roughly linear decrease with an inverse in the slit width,while the critical pressure and the critical density have a relative increment related with carbon number on both the large slit width region and the small slit width region.Further analysis on z-density profiles of alkanes revealed that the complex behaviors of shift in critical parameters are the results of interplay between fluid-fluid and fluid-wall interaction.展开更多
For shale of Lower Silurian Longmaxi Formation in Chongqing,southeast Sichuan Basin,characteristics of micro-nano pores in marine shale reservoirs were well studies by means of Field-Emission Scanning Electron Microsc...For shale of Lower Silurian Longmaxi Formation in Chongqing,southeast Sichuan Basin,characteristics of micro-nano pores in marine shale reservoirs were well studies by means of Field-Emission Scanning Electron Microscope and Low-temperature Low-pressure Adsorption Experiment of CO_(2)and N_(2).Results showed that six types of pore were developed in the shale of Longmaxi Formation,i.e.,organic pores,intergranular pores,intragranular pores,intercrystalline pores,dissolution pores and microfractures,among which the organic pores and intragranular pores in interlayers of clay minerals were most developed,and a plenty of dissolution pores were also well developed because of high thermal evolution degree.BET specific surface area of the shale in Longmaxi Formation ranged from 3.5 to 18.1 m^(2)/g,BJH total pore volume was from 0.00234 to 0.01338 cm^(3)/g,DA specific surface area of micropores vaired from 1.3 to 7.3 m^(2)/g,and DA pore volume ranged from 0.00052 to 0.00273 cm^(3)/g.The specific surface area of micropores in the shale accounted for 23.1%-80.2%of total specific surface area with an average of 50.3%,and the pore volume of micropores accounted for 12.1%-48.5%of total pore volume with an average of 32.3%.Micropore was the main storage space in shale reservoir for methane adsorption,that because capacities of specific surface area provided by micropores were considerably greater than those provided by mesopores and macropores.Pore size distribution of the shale was complex,and multiple different peaks occurred in the pore size curves,showing two or three peaks in the range from 0 to 100 nm and four peaks occasionally.TOC had a good linear relationship with pore structure parameters of micropores,mesopores t macropores and total pores in the shale,indicating that TOC was the most important control factor for micron-to nano-pore structure in the shale.After normalization of pore structure parameters to TOC,the pore structure parameters of total pores and mesopores t macropores,had positive linear relationships with content of clay minerals but negative linear relationships with content of brittle minerals,indicating that clay minerals and brittle minerals mainly controlled development of mesopores and macropores in the shale.展开更多
Low-k interconnection is one of the key concepts in the development of high-speed ultra-large-scale integrated(ULSI) circuits.To determine the Young's modulus of ultra thin,low hardness and fragile low-k porous fil...Low-k interconnection is one of the key concepts in the development of high-speed ultra-large-scale integrated(ULSI) circuits.To determine the Young's modulus of ultra thin,low hardness and fragile low-k porous films more accurately,a wideband differential confocal configured laser detected and laser-generated surface acoustic wave(DCC/LD LSAW) detection system is developed.Based on the light deflection sensitivity detection principle, with a novel differential confocal configuration,this DCC/LD LSAW system extends the traditional laser generated surface acoustic wave(LSAW) detection system's working frequency band,making the detected SAW signals less affected by the hard substrate and providing more information about the thin porous low-k film under test.Thus it has the ability to obtain more accurate measurement results.Its detecting principle is explained and a sample of porous silica film on Si(100) is tested.A procedure of fitting an experimental SAW dispersion curve with theoretical dispersion curves was carried out in the high frequency band newly achieved by the DCC/LD LSAW system.A comparison of the measurement results of the DCC/LD LSAW with those from the traditional LSAW shows that this newly developed DCC/LD LSAW can dramatically improve the Young's modulus measuring accuracy of such porous low-k films.展开更多
Agglomerated Pd catalysts with the nano-porous structure were simply prepared by one-step reduction reaction without using any stabilizer. The Pd catalysts show a high catalytic activity for the decomposition of formi...Agglomerated Pd catalysts with the nano-porous structure were simply prepared by one-step reduction reaction without using any stabilizer. The Pd catalysts show a high catalytic activity for the decomposition of formic acid at room temperature. Among all the Pd catalysts tested, the Pdug catalyst exhibits the highest catalytic activity. Moreover, the breakthrough of the advanced catalysts is that the above agglomerated Pd catalysts can be easily separated from the liquid system to control the catalytic reaction at any time, which may further promote the practical application of formic acid as a H2 storage material.展开更多
Fluid mobility has been important topic for unconventional reservoir evaluation.The tight sandstones in Chang 7 Member of the Ordos Basin has been selected to investigate the fluid mobility based on the application of...Fluid mobility has been important topic for unconventional reservoir evaluation.The tight sandstones in Chang 7 Member of the Ordos Basin has been selected to investigate the fluid mobility based on the application of core flooding-NMR combined method and core centrifugation-NMR combined method,and the porous structure is studied using optical microscope,field emission scanning electron microscope(FE-SEM),CT and mercury injection.Our results include:(i)Feldsparrock fragments dissolution pores,calcite dissolution pores,clay mineral dissolution pores,intergranular dissolution expansion pores,inter-granular pores,intra-kaolinite pores,and intra-illite/smectite mixed layer pores are developed in Chang 7 tight sandstones;3D CT pore structure shows that the pore connectivity is positively related to physical properties,and the overall storage space is connected by the throat with diameter between 0.2 and 0.3μm.The percentage of storage space connected by throats with diameter less than 100 nm can reach more than 35%.(ii)Movable fluid saturation of Chang 7 tight sandstones is between 10%and 70%,and movable oil saturation is between 10%and 50%.Movable fluid saturation may cause misunderstanding when used to evaluate fluid mobility,so it is recommended to use movable fluid porosity in the evaluation of fluid mobility.The porosity ranging from 5%to 8%is the inflection point of the fluidity and pore structure.For samples with porosity less than 8%,the movable fluid porosity is generally less than 5%.Moreover,the movable fluid is mainly concentrated in the storage space with a throat diameter of 0.1 to 1μm.For samples with porosity greater than 8%,the porosity of the movable fluid is more than 5%,and the movable fluid is mainly concentrated in the storage space with a throat diameter of 0.2 to 2μm.(iii)The movable fluid saturation measured by core flooding-NMR combined method is generally higher than that measured by core centrifugation-NMR combined method.The former can evaluate the mobility of the oil-water two-phase fluid in samples,while the latter can better reflect the pore structure and directly evaluate the movable fluid in the pore system controlled by different throat diameters.All these results will provide valuable reference for fluid mobility evaluation in tight reservoirs.展开更多
1 Results The catalysts which can efficiently hydro-reform higher n-paraffin to lower isoparaffins for environmentally-friendly gasoline were studied. The catalysts were examined by the conversion of n-hexadecane, n-C...1 Results The catalysts which can efficiently hydro-reform higher n-paraffin to lower isoparaffins for environmentally-friendly gasoline were studied. The catalysts were examined by the conversion of n-hexadecane, n-C16H34 to i-C6H14—i-C10H22.The tri-modally nano-porous catalysts composed of (Ni-Mo)/[γ-Al2O3], nano-oxide, and nano-crystalline zeolite had some active and selective performance because of the interface between nano-oxide and nano-zeolite. The catalyst composed of nano-crystalline MFI or BE...展开更多
基金the National Key Research and Development Program of China (No.2018YFC1602905)the National Natural Science Foundation of China (Nos.61871180 and 61527806)+1 种基金the Natural Science Foundation of Hunan Province (No.2017JJ2069)Hunan Key Research Project (No.2017SK2174) for the financial supports
文摘An electrochemical sensor based on self-made nano-porous pseudo carbon paste electrode(nano-PPCPE)has been successfully developed,and used to detect Cd^2+ and Pb^2+.The experimental results showed that the electrochemical performance of nanoPPCPE is evidently better than both glassy carbon electrode(GCE)and pure carbon paste electrode(CPE).Then the prepared nano-PPCPE was applied to detect Cd^2+ and Pb^2+in standard solution,the results showed that the electrodes can quantitatively detect trace Cd^2+ and Pb^2+,which has great significance in electrochemical analysis and detection.The linear ranges between the target ions concentration and the D PASV current were from 0.1-3.0 μmol/L,0.05-4.0 μmol/L for Cd^2+ and Pb^2+,respectively.And the detection limits were 0.0780 μmol/L and 0.0292 μmol/L,respectively.Moreover,the preparation of the nano-PPCPE is cheap,simple and has important practical value.
文摘Clustering of Ti on carbon nanostructures has proved to be an obstacle in their use as hydrogen storage materials. Using density functional theory we show that Ti atoms will not cluster at moderate concentrations when doped into nanoporous graphene. Since each Ti atom can bind up to three hydrogen molecules with an average binding energy of 0.54 eV/H2, this material can be ideal for storing hydrogen under ambient thermodynamic conditions. In addition, nanoporous graphene is magnetic with or without Ti doping, but when it is fully saturated with hydrogen, the magnetism disappears. This novel feature suggests that nanoporous graphene cannot only be used for storing hydrogen, but also as a hydrogen sensor.
文摘Background Drug-eluting stents represent a major advance in interventional cardiology. However, the current drug- eluting stents have significant limitations. One of the major problems is very late stent thrombosis, which is likely caused by inflammation and a hypersensitivity reaction related to a polymer on the stent. A polymer-free sirolimus-eluting stent with a unique nano-porous surface has been developed. This study aimed to evaluate this novel polymer-free sirolimus- eluting stent for its efficacy and safety in a pig model. Methods Stents were directly coated with sirolimus (a drug concentration of 2.2 μg/mm2 on the stent surface). The polymer-free sirolimus-eluting stents (PFSES) were compared to standard polymer-coated sirolimus-eluting stents (PCSES) and bare-metal stents (BMS) in 18 pigs. Results At one month the degree of neointimal hyperplasia was similar between the two sirolimus-eluting stent groups and was significantly less compared to BMS ((1.93±0.51) mm2, (1.57±0.69) mm2 vs. (4.45±1.05) mm2, P 〈0.05)At three months, PFSES maintained the low level of neointima ((2.41±0.99) mm2 vs. (4.32±1.16) mm2, P 〈0.05), whereas PCSES had developed significant neointimal proliferation similar to BMS. The inflammation level was significantly higher in PCSES when compared with BMS three months post-implantation (2.50±0.55 vs. 0.83±0.75, P 〈0.05) whereas PFSES showed a low level of inflammation comparable to PCSES (1.33±0.52 vs. 2.50±0.55, P 〈0.05). Conclusion The PFSES is effective and safe. and appears to be suoerior to standard PCSEs.
基金supported by the National Natural Science Foundation of China(Nos.51804023 and 51874020)the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-18-007A1)+1 种基金the China Postdoctoral Science Foundation(Nos.2019M650489 and 2019T120046)Taishan Scholars Program(No.tsqn201909087)。
文摘Designing efficient and stable non-precious metal HER(hydrogen evolution reaction)electrocatalysts with high large current density adaptability is significant for industrial application of hydrogen production by water electrolysis.Herein,a facile strategy was developed to construct a multi-phase Ni3 P-Co_(2)P-(Ni-Co)film with self-supporting hierarchically micro/nano-porous structure by using bubble template method electrodeposition of self-supporting micro-porous Ni Co P film,oxygen-free annealing for phase separation producing Ni_(3)P-Ni-Co_(2)P-Co structure,and acid etching for constructing surface nano-porous structure.The effective active sites for HER was significantly increased due to the hierarchically micro/nano-porous structure,which not only enlarged the surface roughness,but enhanced the bubble detachment by improving the hydrophilicity.Meanwhile,the HER electrolysis durability was improved benefiting from the Ni_(3)P-Co_(2)P phases with high corrosion resistance(especially in acid solution)and the self-supporting film structure without binder.Consequently,the Ni Co P-OA-AE film exhibited high HER catalytic performance,which delivered a current density of 10 m A cm^(-2)at a low overpotential of 42.9 and 39.7 m V in 1 M KOH and 0.5 M H_(2)SO_(4),respectively.It also possessed high long-term electrolysis durability,and the cell voltage of water electrolysis using self-supporting porous Ni Co P-OA-AE||Ir O_(2)-Ta_(2)O_(5) electrolyzer at 500 m A cm^(-2)for 250 h in 0.5 M H_(2)SO_(4 )is only 2.9 V.
基金supported by NSF under grant number CMMI-1130437 and by a grant from Korean Institute of Science and Technology。
文摘High elastic energy density and high-efficiency ionic electromechanical actuators were prepared from aligned activated microwave exfoliated graphite oxide(A-aMEGO)/polymer nano-composites,and the electromechanical performance was characterized.The elastic modulus and elastic energy density of the ionic actuators can be tuned over a wide range by varying the polymer(poly(vinylidene fluoride/chlorotrifluoroethylene)[P(VDF-CTFE)])concentration in the nano-composite actuators.The A-aMEGO/P(VDF-CTFE)nano-composite actuators with 35 wt.%of polymer content exhibit an elastic energy density higher than 5 J/cm^(3) and an electromechanical conversion efficiency higher than 3.5%,induced under 4 V.The results show the promise of high-density highly aligned graphene electrodes for high-performance ionic electromechanical transduction devices.
基金the National Natural Science Foundation(No.52073187)NSAF Foundation(No.U2230202)for their financial support of this project+3 种基金National Natural Science Foundation(No.51721091)Programme of Introducing Talents of Discipline to Universities(No.B13040)State Key Laboratory of Polymer Materials Engineering(No.sklpme2022-2-03)support of China Scholarship Council
文摘Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.
基金supported by the Ministry of Science and Technology of China through 863-project under grant 2009AA03Z218the Major Program of the National Natural Science Foundation of China under Grant No.90923012the Research Fund for the Doctoral Program of Higher Education of China under grant 200806980023
文摘A novel soft polymer template containing a double-layer structure,which includes a thin layer of polymethylmethacrylate(PMMA)used as a pattern layer and a thicker layer of polydimethylsiloxane(PDMS)used as a back layer,was fabricated from a replica molding process.Anodic aluminum oxide(AAO)template was used as the replica mold to be replicated to the polymethylmethacrylate layer by a thermal infiltration process under a vacuum condition.Results indicate that PMMA/PDMS soft templates with different sizes could be easily fabricated from the as-prepared AAO replica mold.The PMMA/PDMS soft templates were then employed to imprint a TiO_2 gel for achieving TiO_2 nano-pore arrays.After the imprinting process,the PDMS layer was firstly peeled off and the PMMA layer was then removed into acetonitrile,which can avoid any demolding problems like damages or distortions.The TiO_2 nano-pore arrays with the crystalline of anatase could be obtained at a heat treatment temperature of 450°C.
基金Funded by the National Natural Science Foundation of China(Nos.51278086,51578108)Special Fund for Scientific Research in the Public Interest by Ministry of Water Resource of the People’s Republic of China(No.201501003)
文摘Thermodynamic stability, microvoid distribution and phases transformation of natural pozzolana opal shale(POS) were studied systematically in this work. XRD analysis showed that opal-CT, including microcrystal cristobalite and tridymite, is a major component of POS. DTA and FT-IR indicated that there were many hydroxyl groups and acid sites on the surface of amorphous SiO2 materials. FE-SEM analysis exhibited amorphous SiO2 particles(opal-A) covering over stacking sequences microcrystal cristobalite and tridymite. Meanwhile, MIP analysis demonstrated that porosity and pore size distribution of POS remained uniform below 600 ℃. Because stable porous microstructure is a key factor in improving photocatalyst activity, POS is suited to preparing highly active supported.
文摘Yttria-stabilized zirconia and-alumina films were prepared by laser chemical vapor deposition at deposition rates of several hundred micrometers per hour.Moreover,the structural oxide coatings by laser chemical vapor deposition are reviewed.The laser can significantly accelerate the chemical reaction and grain growth in CVD,yielding high deposition rates.The films contain large amounts of nanopores that act as thermal insulation and are thus promising as coating materials for gas turbine blades of Ni-based superalloys and WC-Co cutting tools.
基金support of the National Natural Science Foundation of China(No.51402265,51202225,and 51272240)
文摘The specimens were prepared with high alumina fiber accounting for 0. 5% , 10% or 15% by mass of the total amount of amorphous silica and high alumina fiber, using phenolic resin as binder, and extra-adding 0 or 0. 5% ZnO as sunscreen to cut the cost of SiO2 nanoporous insulation board. The hot volume stability and thermal conductivity (flat plate method ) of the specimens were tested and multi-Jimetion simulation equipment was used to study the thermal insulation performante. The results show that: (1) with high alumina fiber addition increasing, the linear shrinkage rate decreases, but thermal eonductivity changes a little; (2) adding ZnO can decrease thermal conductivity obviously; (3)for the specimen with ZnO and 15% of high alumina fiber, its cold face temperature hardly rises during the simulation experiment at 1 000 ℃ for 2 h, and the cold face temperature of the specimen with the smallest thickness of 2 cm doesn't exceed 180 ℃.
基金This research was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB10020203)the National Natural Science Foundation of China(U1562215).
文摘TraPPE force field combined with grand-canonical transition-matrix Monte Carlo simulation were used to investigate the vapor-liquid coexistence curve and critical properties of methane,ethane,propane,and n-butane in slit pores ranging from 6?to 40?.Long range correction for intermolecular potential in slit pore model was developed,and the fact indicating that its influence on various thermodynamic properties is not negligible was found.The simulation results show that the thermodynamic properties of nano-confined alkanes shift tremendously from the bulk state.The critical temperature under confinement experiences a roughly linear decrease with an inverse in the slit width,while the critical pressure and the critical density have a relative increment related with carbon number on both the large slit width region and the small slit width region.Further analysis on z-density profiles of alkanes revealed that the complex behaviors of shift in critical parameters are the results of interplay between fluid-fluid and fluid-wall interaction.
基金This work was supported by National Natural Science Foundation of China(No.41690134)National Science and Technology Major Project of China(No.2017ZX05035002-006).
文摘For shale of Lower Silurian Longmaxi Formation in Chongqing,southeast Sichuan Basin,characteristics of micro-nano pores in marine shale reservoirs were well studies by means of Field-Emission Scanning Electron Microscope and Low-temperature Low-pressure Adsorption Experiment of CO_(2)and N_(2).Results showed that six types of pore were developed in the shale of Longmaxi Formation,i.e.,organic pores,intergranular pores,intragranular pores,intercrystalline pores,dissolution pores and microfractures,among which the organic pores and intragranular pores in interlayers of clay minerals were most developed,and a plenty of dissolution pores were also well developed because of high thermal evolution degree.BET specific surface area of the shale in Longmaxi Formation ranged from 3.5 to 18.1 m^(2)/g,BJH total pore volume was from 0.00234 to 0.01338 cm^(3)/g,DA specific surface area of micropores vaired from 1.3 to 7.3 m^(2)/g,and DA pore volume ranged from 0.00052 to 0.00273 cm^(3)/g.The specific surface area of micropores in the shale accounted for 23.1%-80.2%of total specific surface area with an average of 50.3%,and the pore volume of micropores accounted for 12.1%-48.5%of total pore volume with an average of 32.3%.Micropore was the main storage space in shale reservoir for methane adsorption,that because capacities of specific surface area provided by micropores were considerably greater than those provided by mesopores and macropores.Pore size distribution of the shale was complex,and multiple different peaks occurred in the pore size curves,showing two or three peaks in the range from 0 to 100 nm and four peaks occasionally.TOC had a good linear relationship with pore structure parameters of micropores,mesopores t macropores and total pores in the shale,indicating that TOC was the most important control factor for micron-to nano-pore structure in the shale.After normalization of pore structure parameters to TOC,the pore structure parameters of total pores and mesopores t macropores,had positive linear relationships with content of clay minerals but negative linear relationships with content of brittle minerals,indicating that clay minerals and brittle minerals mainly controlled development of mesopores and macropores in the shale.
基金financially supported by the Key Basic and Applied Research Program of Guangdong Province,China(2019B030302010)the National Key Research and Development Program of China(2018YFA0703605)+1 种基金the National Science Foundation of China(52122105,51971150)the Science and Technology Innovation Commission Shenzhen(RCJC20221008092730037,20220804091920001)。
基金Project supported by the National Science Foundation of China(Nos.60723004,61072013)
文摘Low-k interconnection is one of the key concepts in the development of high-speed ultra-large-scale integrated(ULSI) circuits.To determine the Young's modulus of ultra thin,low hardness and fragile low-k porous films more accurately,a wideband differential confocal configured laser detected and laser-generated surface acoustic wave(DCC/LD LSAW) detection system is developed.Based on the light deflection sensitivity detection principle, with a novel differential confocal configuration,this DCC/LD LSAW system extends the traditional laser generated surface acoustic wave(LSAW) detection system's working frequency band,making the detected SAW signals less affected by the hard substrate and providing more information about the thin porous low-k film under test.Thus it has the ability to obtain more accurate measurement results.Its detecting principle is explained and a sample of porous silica film on Si(100) is tested.A procedure of fitting an experimental SAW dispersion curve with theoretical dispersion curves was carried out in the high frequency band newly achieved by the DCC/LD LSAW system.A comparison of the measurement results of the DCC/LD LSAW with those from the traditional LSAW shows that this newly developed DCC/LD LSAW can dramatically improve the Young's modulus measuring accuracy of such porous low-k films.
文摘Agglomerated Pd catalysts with the nano-porous structure were simply prepared by one-step reduction reaction without using any stabilizer. The Pd catalysts show a high catalytic activity for the decomposition of formic acid at room temperature. Among all the Pd catalysts tested, the Pdug catalyst exhibits the highest catalytic activity. Moreover, the breakthrough of the advanced catalysts is that the above agglomerated Pd catalysts can be easily separated from the liquid system to control the catalytic reaction at any time, which may further promote the practical application of formic acid as a H2 storage material.
基金supported by the NSFC(No.42072187)CNPC(No.2019E-26).
文摘Fluid mobility has been important topic for unconventional reservoir evaluation.The tight sandstones in Chang 7 Member of the Ordos Basin has been selected to investigate the fluid mobility based on the application of core flooding-NMR combined method and core centrifugation-NMR combined method,and the porous structure is studied using optical microscope,field emission scanning electron microscope(FE-SEM),CT and mercury injection.Our results include:(i)Feldsparrock fragments dissolution pores,calcite dissolution pores,clay mineral dissolution pores,intergranular dissolution expansion pores,inter-granular pores,intra-kaolinite pores,and intra-illite/smectite mixed layer pores are developed in Chang 7 tight sandstones;3D CT pore structure shows that the pore connectivity is positively related to physical properties,and the overall storage space is connected by the throat with diameter between 0.2 and 0.3μm.The percentage of storage space connected by throats with diameter less than 100 nm can reach more than 35%.(ii)Movable fluid saturation of Chang 7 tight sandstones is between 10%and 70%,and movable oil saturation is between 10%and 50%.Movable fluid saturation may cause misunderstanding when used to evaluate fluid mobility,so it is recommended to use movable fluid porosity in the evaluation of fluid mobility.The porosity ranging from 5%to 8%is the inflection point of the fluidity and pore structure.For samples with porosity less than 8%,the movable fluid porosity is generally less than 5%.Moreover,the movable fluid is mainly concentrated in the storage space with a throat diameter of 0.1 to 1μm.For samples with porosity greater than 8%,the porosity of the movable fluid is more than 5%,and the movable fluid is mainly concentrated in the storage space with a throat diameter of 0.2 to 2μm.(iii)The movable fluid saturation measured by core flooding-NMR combined method is generally higher than that measured by core centrifugation-NMR combined method.The former can evaluate the mobility of the oil-water two-phase fluid in samples,while the latter can better reflect the pore structure and directly evaluate the movable fluid in the pore system controlled by different throat diameters.All these results will provide valuable reference for fluid mobility evaluation in tight reservoirs.
文摘1 Results The catalysts which can efficiently hydro-reform higher n-paraffin to lower isoparaffins for environmentally-friendly gasoline were studied. The catalysts were examined by the conversion of n-hexadecane, n-C16H34 to i-C6H14—i-C10H22.The tri-modally nano-porous catalysts composed of (Ni-Mo)/[γ-Al2O3], nano-oxide, and nano-crystalline zeolite had some active and selective performance because of the interface between nano-oxide and nano-zeolite. The catalyst composed of nano-crystalline MFI or BE...