Shale gas reservoirs typically contain numerous nanoscale pores,with pore size playing a significant role in influencing the gas behavior.To better understand the related mechanisms,this study employs the Gauge-GEMC m...Shale gas reservoirs typically contain numerous nanoscale pores,with pore size playing a significant role in influencing the gas behavior.To better understand the related mechanisms,this study employs the Gauge-GEMC molecular simulation method to systematically analyze the effects of various pore sizes(5,10,20,and 40 nm)on the phase behavior and dew point pressure of the shale gas reservoir components.The simulation results reveal that when pore sizes are smaller than 40 nm,the dew point pressure increases significantly as the pore size decreases.For instance,the dew point pressure in 5 nmpores is 20.3%higher than undermacroscopic conditions.Additionally,larger hydrocarbon molecules exhibit a tendency to aggregate in smaller pores,particularly in the 5–10 nm range,where the relative concentration of heavy hydrocarbons(C_(4+))increases markedly.Moreover,as the pore size becomes larger,the component distribution gradually aligns with experimental results observed under macroscopic conditions.This study demonstrates that pore effects are more pronounced for smaller sizes,directly influencing the aggregation of heavy hydrocarbons and the rise in dew point pressure.These phenomena could significantly impact the diffusivity of shale gas reservoirs and the recovery of condensate gas.The findings provide new theoretical insights into phase behavior changes in nanopores,offering valuable guidance for optimizing shale gas reservoir extraction strategies.展开更多
Considering the interactions between fluid molecules and pore walls,variations in critical properties,capillary forces,and the influence of the adsorbed phase,this study investigates the phase behavior of the CO_(2)-s...Considering the interactions between fluid molecules and pore walls,variations in critical properties,capillary forces,and the influence of the adsorbed phase,this study investigates the phase behavior of the CO_(2)-shale oil within nanopores by utilizing a modified Peng-Robinson(PR)equation of state alongside a three-phase(gas-liquid-adsorbed)equilibrium calculation method.The results reveal that nano-confinement effects of the pores lead to a decrease in both critical temperature and critical pressure of fluids as pore size diminishes.Specifically,CO_(2) acts to inhibit the reduction of the critical temperature of the system while promoting the decrease in critical pressure.Furthermore,an increase in the mole fraction of CO_(2) causes the critical point of the system to shift leftward and reduces the area of the phase envelope.In the shale reservoirs of Block A in Gulong of the Daqing Oilfield,China,pronounced confinement effects are observed.At a pore diameter of 10 nm,reservoir fluids progressively exhibit characteristics typical of condensate gas reservoirs.Notably,the CO_(2) content in liquid in 10 nm pores increases by 20.0%compared to that in 100 nm pores,while the CO_(2) content in gas decreases by 10.8%.These findings indicate that confinement effects enhance CO_(2) mass transfer within nanopores,thereby facilitating CO_(2) sequestration and improving microscopic oil recovery.展开更多
Excessive Fe^(3+) ion concentrations in wastewater pose a long-standing threat to human health.Achieving low-cost,high-efficiency quantification of Fe^(3+) ion concentration in unknown solutions can guide environmenta...Excessive Fe^(3+) ion concentrations in wastewater pose a long-standing threat to human health.Achieving low-cost,high-efficiency quantification of Fe^(3+) ion concentration in unknown solutions can guide environmental management decisions and optimize water treatment processes.In this study,by leveraging the rapid,real-time detection capabilities of nanopores and the specific chemical binding affinity of tannic acid to Fe^(3+),a linear relationship between the ion current and Fe^(3+) ion concentration was established.Utilizing this linear relationship,quantification of Fe^(3+) ion concentration in unknown solutions was achieved.Furthermore,ethylenediaminetetraacetic acid disodium salt was employed to displace Fe^(3+) from the nanopores,allowing them to be restored to their initial conditions and reused for Fe^(3+) ion quantification.The reusable bioinspired nanopores remain functional over 330 days of storage.This recycling capability and the long-term stability of the nanopores contribute to a significant reduction in costs.This study provides a strategy for the quantification of unknown Fe^(3+) concentration using nanopores,with potential applications in environmental assessment,health monitoring,and so forth.展开更多
Biomimetic nanozymes opens up new opportunities for sensitive,rapid and field detection of organophosphorus pesticides(OPs).However,it still remains challenges in how to improve the sensitivity and stability of biomim...Biomimetic nanozymes opens up new opportunities for sensitive,rapid and field detection of organophosphorus pesticides(OPs).However,it still remains challenges in how to improve the sensitivity and stability of biomimetic nanozymes under harsh conditions.Herein,we synthesized a novel biomimetic nanozyme composed of hemin and bovine serum albumin(BSA)in the nanopores of poly-l-lysine methacryloyl(PLMA)inverse opal hydrogel(PLMA-Hemin-BSA).PLMA-Hemin-BSA achieves superior peroxidase-like activity and shows high stability due to the confinement effect.A multi-enzyme cascade reaction was constructed for the colorimetric detection of five widely used OPs by integrating PLMAHemin-BSA with natural choline oxidase and acetylcholinesterase.The detection limits for dichlorvos,chlorpyrifos,paraoxon,methamidophos,and parathion were as low as 0.024,0.073,0.12,0.56,and 1.4 ng/mL,respectively.More importantly,the average recovery rates and the relative standard deviations(RSD)of chlorpyrifos in paddy water,soil and wheat samples were 86.62%-100.13%and 2.08%-8.65%,which meet the standard of the International Union of Pure and Applied Chemistry(IUPAC,recoveries of 70%-120%with RSD<20%).This study represented advanced methods toward enhancing the activity and stability of biomimetic nanozymes via spatial nanopores-assisted strategy.展开更多
Constant-current anodization of pure aluminum was carried out in non-corrosive capacitor working electrolytes to study the formation mechanism of nanopores in the anodic oxide films.Through comparative experiments,nan...Constant-current anodization of pure aluminum was carried out in non-corrosive capacitor working electrolytes to study the formation mechanism of nanopores in the anodic oxide films.Through comparative experiments,nanopores are found in the anodic films formed in the electrolytes after high-temperature storage(HTS)at 130°C for 240 h.A comparison of the voltage-time curves suggests that the formation of nanopores results from the decrease in formation efficiency of anodic oxide films rather than the corrosion of the electrolytes.FT-IR and UV spectra analysis shows that carboxylate and ethylene glycol in electrolytes can easily react by esterification at high temperatures.Combining the electronic current theory and oxygen bubble mold effect,the change in electrolyte composition could increase the electronic current in the anodizing process.The electronic current decreases the formation efficiency of anodic oxide films,and oxygen bubbles accompanying electronic current lead to the formation of nanopores in the dense films.The continuous electronic current and oxygen bubbles are the prerequisites for the formation of porous anodic oxides rather than the traditional field-assisted dissolution model.展开更多
It is acknowledged that injecting CO_(2) into oil reservoirs and saline aquifers for storage is a practical and affordable method for CO_(2) sequestration.Most CO_(2) produced from industrial exhaust contains impurity...It is acknowledged that injecting CO_(2) into oil reservoirs and saline aquifers for storage is a practical and affordable method for CO_(2) sequestration.Most CO_(2) produced from industrial exhaust contains impurity gases such as H_(2)S that might impact CO_(2) sequestration due to competitive adsorption.This study makes a commendable effort to explore the adsorption behavior of CO_(2)/H_(2)S mixtures in calcite slit nanopores.Grand Canonical Monte Carlo(GCMC)simulation is employed to reveal the adsorption of CO_(2),H_(2)S as well as their binary mixtures in calcite nanopores.Results show that the increase in pressure and temperature can promote and inhibit the adsorption capacity of CO_(2) and H_(2)S in calcite nanopores,respectively.CO_(2)exhibits stronger adsorption on calcite surface than H_(2)S.Electrostatic energy plays the dominating role in the adsorption behavior.Electrostatic energy accounts for 97.11%of the CO_(2)-calcite interaction energy and 56.33%of the H_(2)S-calcite interaction energy at 10 MPa and 323.15 K.The presence of H_(2)S inhibits the CO_(2) adsorption in calcite nanopores due to competitive adsorption,and a higher mole fraction of H_(2)S leads to less CO_(2) adsorption.The quantity of CO_(2) adsorbed is lessened by approximately 33%when the mole fraction of H_(2)S reaches 0.25.CO_(2) molecules preferentially occupy the regions near the po re wall and H_(2)S molecules tend to reside at the center of nanopore even when the molar ratio of CO_(2) is low,indicating that CO_(2) has an adsorption priority on the calcite surface over H_(2)S.In addition,moisture can weaken the adsorption of both CO_(2) and H_(2)S,while CO_(2) is more affected.More interestingly,we find that pure CO_(2) is more suitable to be sequestrated in the shallower formations,i.e.,500-1500 m,whereas CO_(2)with H_(2)S impurity should be settled in the deeper reservoirs.展开更多
Nanopore sequencing harnesses changes in ionic current as nucleotides traverse a nanopore,enabling real-time decoding of DNA/RNA sequences.The instruments for the dynamic behavior of substances in the nanopore on the ...Nanopore sequencing harnesses changes in ionic current as nucleotides traverse a nanopore,enabling real-time decoding of DNA/RNA sequences.The instruments for the dynamic behavior of substances in the nanopore on the molecular scale are still very limited experimentally.This study employs all-atom molecular dynamics(MD)simulations to explore the impact of charge densities on graphene nanopore in the translocation of single-stranded DNA(ssDNA).We find that the magnitude of graphene’s charge,rather than the charge disparity between ssDNA and graphene,significantly influences ssDNA adsorption and translocation speed.Specifically,high negative charge densities on graphene nanopores are shown to substantially slow down ssDNA translocation,highlighting the importance of hydrodynamic effects and electrostatic repulsions.This indicates translocation is crucial for achieving distinct ionic current blockades,which plays a central role for DNA sequencing accuracy.Our findings suggest that negatively charged graphene nanopores hold considerable potential for optimizing DNA sequencing,marking a critical advancement in this field.展开更多
During the development of shale gas,various issues such as low individual well production,rapid decline,limited reservoir control,and low recovery rates have arisen.Enhancing shale gas reservoir recovery rates has con...During the development of shale gas,various issues such as low individual well production,rapid decline,limited reservoir control,and low recovery rates have arisen.Enhancing shale gas reservoir recovery rates has consistently been a focal point and challenge within the industry.Therefore,this paper employs molecular dynamic(MD)simulation methods to study the adsorption and diffusion characteristics of CH_(4)/CO_(2)at different temperatures and mixing ratios.It compares the effects of temperature and CH_(4)/CO_(2)molar ratio changes on the selectivity coefficient,adsorption capacity,and diffusion coefficient of CH_(4)/CO_(2).The paper also plots the displacement interface and the function of CH_(4)/CO_(2)injection/residual amounts over time.Furthermore,it analyzes the adsorption capacity of molecules on the graphene surface,the migration capacity of molecules in the slit,and the displacement process of CH_(4)by CO_(2)on the nanoscale,revealing the microscopic mechanism of CH_(4)/CO_(2)competitive adsorption and displacement.The research results indicate that the influence of temperature on the selectivity coefficient is not significant,with an average decrease of 3%for every 20 K rise in temperature.Pressure has a more pronounced effect on the selectivity coefficient,with values around 1.4 at low pressures and around 1.2 at high pressures.Elevating the mole fraction of CO_(2)in the binary gas mixture results in an increase in the total adsorption amount and an accelerated variation of adsorption amount with pressure.As the CH_(4)mole fraction rises,the diffusion coefficient of CH_(4)increases,while the diffusion coefficient of CO_(2)diminishes with an increasing CO_(2)mole fraction.Under identical conditions,CO_(2)exhibits a stronger adsorption capacity over CH_(4)in shale organic nanopores,resulting in a concave moon-shaped displacement interface in the model.The larger the pre-adsorption pressure of CO_(2),the more intense the movement of CO_(2)along the graphene surface,and the faster the diffusion speed of CO_(2)along the wall.In a displacement pore(the pore space used to provide the displacement location or site)with a diameter of 3 nm,at smaller pressure differentials(≤10 MPa),the residual amount of CH_(4)remains relatively stable without substantial alteration.However,at a pressure differential of 20 MPa,the residual amount of CH_(4)decreases rapidly,and the displacement efficiency significantly improves.展开更多
Nearly equiatomic nickel–titanium(NiTi) alloy is an ideal implant biomaterial because of its shape memory effect, superelasticity, low elastic modulus as well as other desirable properties.However, it is prone to inf...Nearly equiatomic nickel–titanium(NiTi) alloy is an ideal implant biomaterial because of its shape memory effect, superelasticity, low elastic modulus as well as other desirable properties.However, it is prone to infection because of its poor antibacterial ability.The present work incorporated Cu into Ni–Ti–O nanopores(NP–Cu) anodically grown on the NiTi alloy to enhance its antibacterial ability, which was realized through electrodeposition.Our results show that incorporation of Cu(0.78 at%–2.37 at%)has little influence on the NP diameter, length and morphology.The release level of Cu ions is in line with loadage which may be responsible for the improved antibacterial ability of the NiTi alloy to combat possible bacterial infection in vivo.Meanwhile, the NP–Cu shows better cytocompatibility and even can promote proliferation of bone marrow mesenchymal stem cells(BMSCs),up-regulate collagen secretion and extracellular matrix mineralization when compared with Cu-free sample.Better antibacterial ability and cytocompatibility of the NP–Cu render them to be promising when serving as NiTi implant coatings.展开更多
The flow behavior of pressure-driven water infiltration through graphene-based slit nanopores has been studied by molecular simulation.The simulated flow rate is close to the experimental values,which demonstrates the...The flow behavior of pressure-driven water infiltration through graphene-based slit nanopores has been studied by molecular simulation.The simulated flow rate is close to the experimental values,which demonstrates the reasonability of simulation results.Water molecules can spontaneously infiltrate into the nanopores,but an external driving force is generally required to pass through the whole pores.The exit of nanopore has a large obstruction on the water effusion.The flow velocity within the graphene nanochannels does not display monotonous dependence upon the pore width,indicating that the flow is related to the microscopic structures of water confined in the nanopores.Extensive structures of confined water are characterized in order to understand the flow behavior.This simulation improves the understanding of graphene-based nanofluidics,which helps in developing a new type of membrane separation technique.展开更多
Organic-rich shale resources remain an important source of hydrocarbons considering their substantial contribution to crude oil and natural gas production around the world. Moreover, as part of mitigating the greenhou...Organic-rich shale resources remain an important source of hydrocarbons considering their substantial contribution to crude oil and natural gas production around the world. Moreover, as part of mitigating the greenhouse gas effects due to the emissions of carbon dioxide （CO2） gas, organic-rich shales are considered a possible alternate geologic storage. This is due to the adsorptive properties of organic ke- rogen and clay minerals within the shale matrix. Therefore, this research looks at evaluating the seques- tration potential of carbon dioxide （CO2） gas in kerogen nanopores with the use of the lattice Boltzmann method under varying experimental pressures and different pore sizes. Gas flow in micro/nano pores differ in hydrodynamics due to the dominant pore wall effects, as the mean free path （λ） of the gas molecules become comparable to the characteristic length （H） of the pores. In so doing, the traditional computational methods break down beyond the continuum region, and the lattice Boltzmann method （LBM） is employed. The lattice Boltzmann method is a mesoscopic numerical method for fluid system, where a unit of gas particles is assigned a discrete distribution function （/）. The particles stream along de- fined lattice links and collide locally at the lattice sites to conserve mass and momentum. The effects of gas-wall collisions （Knudsen layer effects） is incorporated into the LBM through an effective-relaxation- time model, and the discontinuous velocity at the pore walls is resolved with a slip boundary condition. Above all, the time lag （slip effect） created by CO2 gas molecules due to adsorption and desorption over a time period, and the surface diffusion as a result of the adsorption-gradient are captured by an adsorption isotherm and included in our LBM. Implementing the Langmuir adsorption isotherm at the pore walls for both CO2 gas revealed the underlying flow mechanism for CO2 gas in a typical kerogen nano-pore is dominated by the slip flow regime. Increasing the equilibrium pressure, increases the mass flux due to ad- sorption. On the other hand, an increase in the nano-pore size caused further increase in the mass flux due to free gas and that due to adsorbed gas. Thus, in the kerogen nano-pores, CO2 gas molecules are more adsorptive indicating a possible multi-layer adsorption. Therefore, this study not only provides a clear un- derstanding of the underlying flow mechanism of CO2 in kerogen nano-pores, but also provides a potential alternative means to mitigate the greenhouse gas effect （GHG） by sequestering CO2 in organic-rich shales.展开更多
With the increasing demand for petroleum,shale oil with considerable reserves has become an important part of global oil resources.The shale oil reservoir has a large number of nanopores and a complicated mineral comp...With the increasing demand for petroleum,shale oil with considerable reserves has become an important part of global oil resources.The shale oil reservoir has a large number of nanopores and a complicated mineral composition,and the effect of nanopore confinement and pore type usually makes the effective development of shale oil challenging.For a shale oil reservoir,CO_(2) flooding can effectively reduce the oil viscosity and improve the reservoir properties,which can thus improve the recovery performance.In this study,the method of non-equilibrium molecular dynamics(NEMD)simulation is used to simulate the CO_(2) flooding process in the nanoscale pores of shale oil reservoir.The performance difference between the organic kerogen slit nanopore and four types of inorganic nanopores is discussed.Thus,the effects of nanopore type and displacement velocity on the nanoscale displacement behavior of CO_(2) are analyzed.Results indicate that the CO_(2) flooding process of different inorganic pores is different.In comparison,the displacement efficiency of light oil components is higher,and the transport distance is longer.The intermolecular interaction can significantly affect the CO_(2) displacement behavior in nanopores.The CO_(2) displacement efficiency is shown as montmorillonite,feldspar>quartz>calcite>kerogen.On the other hand,it is found that a lower displacement velocity can benefit the miscibility process between alkane and CO_(2),which is conducive to the overall displacement process of CO_(2).The displacement efficiency can significantly decrease with the increase in displacement velocity.But once the displacement velocity is very high,the strong driving force can promote the alkane to move forward,and the displacement efficiency will recover slightly.This study further reveals the microscopic oil displacement mechanism of CO_(2) in shale nanopores,which is of great significance for the effective development of shale oil reservoirs by using the method of CO_(2) injection.展开更多
A biosensor device, built from graphene nanoribbons （GNRs） with nanopores, was designed and studied by first- principles quantum transport simulation. We have demonstrated the intrinsic transport properties of the d...A biosensor device, built from graphene nanoribbons （GNRs） with nanopores, was designed and studied by first- principles quantum transport simulation. We have demonstrated the intrinsic transport properties of the device and the effect of different nucleobases on device properties when they are located in the nanopores of GNRs. It was found that the device＇s current changes remarkably with the species of nucleobases, which originates from their different chemical compositions and coupling strengths with GNRs. In addition, our first-principles results clearly reveal that the distinguished ability of a device＇s current depends on the position of the pore to some extent. These results may present a new way to read off the nucleobases sequence of a single-stranded DNA （ssDNA） molecule by such GNRs-based device with designed nanopores展开更多
Electrochemical anodization(EA)is a simple and cost-effective technique to fabricate controlled nanostructures on Ti substrates,such as TiO_(2)nanotubes and nanopores.Electrolyte aging of organic EA electrolytes(repea...Electrochemical anodization(EA)is a simple and cost-effective technique to fabricate controlled nanostructures on Ti substrates,such as TiO_(2)nanotubes and nanopores.Electrolyte aging of organic EA electrolytes(repeated EA using non-target Ti before EA of target Ti)is recognized to influence the characteristics of the anodized nanostructures.However,there is limited information about how surface topography and electrolyte aging dictate the formation and characteristics of the anodized nanostructures.In the current study,short-time EA(starting at 10 s)of micro-machined Ti substrates was performed with electrolytes of various ages(fresh/unused,15 h aged and 30 h aged),followed by evaluation of the TiO_(2)nanopores(TNPs)characteristics in terms of topography,chemistry,stability and protein adhesion.The results showed that aligned TNPs were obtained earlier(120 s)with fresh electrolyte as compared to the aged electrolyte EA(600 s).Interestingly,TNPs fabricated using fresh electrolyte(at lower EA times)showed favorable wettability,protein adhesion capacity and mechanical properties compared with aged electrolyte counterparts.The findings of the study demonstrate how nanopore formation differs between fresh and aged electrolytes when performing EA of micro-machined Ti,which provides an improved understanding of electrolyte aging and its influence on anodized nanostructures.展开更多
Latent heat storage performance of a layered perovskite-type compound, 1-C14H29NH3）2ZnCl4（C14Zn）,embedded in a series of silica gel（SG） with pore sizes of d = 15–200 nm is investigated using differential scannin...Latent heat storage performance of a layered perovskite-type compound, 1-C14H29NH3）2ZnCl4（C14Zn）,embedded in a series of silica gel（SG） with pore sizes of d = 15–200 nm is investigated using differential scanning calorimetry（DSC）, and powder X-ray diffractions（XRD）. C14Zn in the nanopores of silica gel shows size-dependent phase transition temperature, enthalpy change and supercooling. They have a stable transition temperature and heat capacity at each size in a short-term thermal cycling. Similar Xray diffraction patterns are observed for the nano-sized and the bulk C（14）Zn. The encapsulation of a phase change material in nanopores is a new way of tuning its thermal energy storage properties for a wider range of temperature regulation.展开更多
Solid-state nanopore in analytical chemistry has developed rapidly in the 1990s and it is proved to be a versatile new tool for bioanalytical chemistry. The research field of solid-state nanopore starts from mimicking...Solid-state nanopore in analytical chemistry has developed rapidly in the 1990s and it is proved to be a versatile new tool for bioanalytical chemistry. The research field of solid-state nanopore starts from mimicking the biological nanopore in living cells. Understanding the transport mechanism of biological nanopore in vivo is a big challenge because of the experimental difficulty, so it is essential to establish the basic research of artificial nanopores in vitro especially for the analysis of ions and small molecules. The performance of solid-state nanopores could be evaluated by monitoring currents when ions and molecules passed through. The comparison of the two types of nanopores based on current-derived information can reveal the principle of biological nanopores, while the solid-state nanopores are applied into practical bioanalysis. In this review, we focus on the researches of the solid-state nanopores in the fabrication process and in the analysis of ions and small molecules. Fabrication methods of nanopores,ion transport mechanism, small molecule analysis and theoretical studies are discussed in detail.展开更多
The Qingshankou Formation shale oil in the Gulong Sag is an important oil and gas reservoir in the Daqing oilfield,with geological resources of 15.1 billion tons.The fabric of shale can reflect not only its genesis bu...The Qingshankou Formation shale oil in the Gulong Sag is an important oil and gas reservoir in the Daqing oilfield,with geological resources of 15.1 billion tons.The fabric of shale can reflect not only its genesis but also the nature of the reservoir space,its physical properties,oil content,and development value.Here,the characteristics of clay minerals in the Gulong shale oil reservoir were studied via electron microscopy,with the primary focus on the microfabrics and reservoir space;thereafter,the in situ accumulation was studied and discussed.Electron backscattering patterns revealed that nanometer pores and fissures were well developed in the Gulong shale oil reservoir.The nano pores were mostly 20-50 nm in diameter(median 20-30 nm),irregularly shaped,mostly,polygonal,and connected with nanofissures.The widths of nanofissures ranged mostly between 10-50 nm(median 20-30 nm);moreover,these fissures were mainly formed by F-F condensation of clay sheets(clay domains).The coagulation of clays was closely related to organic matter,especially algae.The clay colloids were negatively charged due to isocrystalline replacement;hence,metal cations were absorbed around the clay,forming a positive clay group.The positively charged clays subsequently adsorbed negatively charged humic acid(organic matter)and initially degraded algae to form an organic clay flocculant.When the organic clay flocculates reached the threshold for hydrocarbon generation and expulsion,the volume of organic matter decreased by 87%;thereafter,the generated and expelled hydrocarbon filled the nearby pores formed by this contraction.Moreover,the discharged hydrocarbon could not migrate due to capillary resistance(~12 MPa)of the nanopores;hence,the nanopores formed a unique continuous in situ reservoir within the Gulong shale oil.This study demonstrated that the Gulong shale oil reservoir is an actual clay-type shale reservoir with numerous nanopore and fissures.During coagulation,a large amount of organic matter(including layered algae)was absorbed by the clay,forming an organic clay condensate that could have provided the material foundation for hydrocarbon generation at a later stage.Thermal simulation experiments revealed that the volume of organic matter decreased sharply after hydrocarbon generation and expulsion.展开更多
A polymeric nanopore membrane with selective ionic transport has been proposed as a potential device to convert the chemical potential energy in salinity gradients to electrical power. However, its energy conversion e...A polymeric nanopore membrane with selective ionic transport has been proposed as a potential device to convert the chemical potential energy in salinity gradients to electrical power. However, its energy conversion efficiency and power density are often limited due to the challenge in reliably controlling the size of the nanopores with the conventional chemical etching method. Here we report that without chemical etching, polyimide （PI） membranes irradiated with GeV heavy ions have negatively charged nanopores, showing nearly perfect selectivity for cations over anions, and they can generate electrical power from salinity gradients. We further demonstrate that the power generation efficiency of the PI membrane approaches the theoretical limit, and the maximum power density reaches 130m W/m2 with a modified etching method, outperforming the previous energy conversion device that was made of polymeric nanopore membranes.展开更多
Ca^(2+)/Na+separation is a common problem in industrial applications,biological and medical fields.However,Ca^(2+)and Na+have similar ionic radii and hydration radii,thus Ca^(2+)/Na+separation is challenging.Inspired ...Ca^(2+)/Na+separation is a common problem in industrial applications,biological and medical fields.However,Ca^(2+)and Na+have similar ionic radii and hydration radii,thus Ca^(2+)/Na+separation is challenging.Inspired by biological channels,group modification is one of the effective methods to improve the separation performance.In this work,molecular dynamics simulations were performed to investigate the effects of different functional groups(COO,NH3+)on the separation performance of Ca^(2+)and Na+through graphene nanopores under an electric field.The pristine graphene nanopore was used for comparison.Results showed that three types of nanopores preferred Ca^(2+)to Na+,and Ca^(2+)/Na+selectivity followed the order of GE-COO(4.06)>GE(1.85)>GE-NH3+(1.63).Detailed analysis of ionic hydration microstructure shows that different nanopores result in different hydration factors for the second hydration layer of Ca^(2+)and the first layer of Na+.Such different hydration factors corresponding to the dehydration ability can effectively evaluate the separation performance.In addition,the breaking of hydrogen bonds between water molecules due to electrostatic effects can directly affect the dehydration ability.Therefore,the electrostatic effect generated by group modification will affect the ionic hydration microstructure,thus reflecting the differences in dehydration ability.This in turn affects the permeable and separation performance of cations.The results of this work provide perceptive guidelines for the application of graphene-based membranes in ion separation.展开更多
Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a nove...Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a novel transient model to describe oil transport in unsteady and steady states. The model incorporates the effect of the critical shift density, apparent viscosity, slip length, and alkane property, as well as pore tortuosity and surface roughness. We evaluated our model through a comparison with other models, experiments, and molecular dynamics simulations. The results show that the development rates of the volume flows of C_(6)–C_(12) alkane confined in inorganic nanopores and C_(12) alkane confined in organic nanopores were faster than that of the corresponding bulk alkane. In addition, the critical drift density positively promoted the volume flow development rate in the unsteady state and negatively inhibited the mass flow rate in the steady state. This effect was clearest in pores with a smaller radius and lower-energy wall and in alkane with shorter chain lengths. Furthermore, both the nanoconfinement effect and pore structure determined whether the volume flow enhancement rate was greater than or less than 1. The rate increased or decreased with time and was controlled mainly by the nanoconfinement effect. Moreover, as the wall energy increased, the flow inhibition effect increased;as the carbon number of alkane increased, the flow promotion effect increased. The results indicate that the proposed model can accurately describe oil transport in shale nanopores.展开更多
基金financially supported by the Hubei Province Education Department of China(Project Name:Research on the Formation Mechanism and Microscopic Characteristics of Tight Dolomite Reservoirs in Salt Lake Basins:A Case Study of the Xingouzui Formation in the Jianghan Basin,Grant No.B2020032).
文摘Shale gas reservoirs typically contain numerous nanoscale pores,with pore size playing a significant role in influencing the gas behavior.To better understand the related mechanisms,this study employs the Gauge-GEMC molecular simulation method to systematically analyze the effects of various pore sizes(5,10,20,and 40 nm)on the phase behavior and dew point pressure of the shale gas reservoir components.The simulation results reveal that when pore sizes are smaller than 40 nm,the dew point pressure increases significantly as the pore size decreases.For instance,the dew point pressure in 5 nmpores is 20.3%higher than undermacroscopic conditions.Additionally,larger hydrocarbon molecules exhibit a tendency to aggregate in smaller pores,particularly in the 5–10 nm range,where the relative concentration of heavy hydrocarbons(C_(4+))increases markedly.Moreover,as the pore size becomes larger,the component distribution gradually aligns with experimental results observed under macroscopic conditions.This study demonstrates that pore effects are more pronounced for smaller sizes,directly influencing the aggregation of heavy hydrocarbons and the rise in dew point pressure.These phenomena could significantly impact the diffusivity of shale gas reservoirs and the recovery of condensate gas.The findings provide new theoretical insights into phase behavior changes in nanopores,offering valuable guidance for optimizing shale gas reservoir extraction strategies.
基金Supported by the National Natural Science Foundation of China Joint Fund(U22B2075).
文摘Considering the interactions between fluid molecules and pore walls,variations in critical properties,capillary forces,and the influence of the adsorbed phase,this study investigates the phase behavior of the CO_(2)-shale oil within nanopores by utilizing a modified Peng-Robinson(PR)equation of state alongside a three-phase(gas-liquid-adsorbed)equilibrium calculation method.The results reveal that nano-confinement effects of the pores lead to a decrease in both critical temperature and critical pressure of fluids as pore size diminishes.Specifically,CO_(2) acts to inhibit the reduction of the critical temperature of the system while promoting the decrease in critical pressure.Furthermore,an increase in the mole fraction of CO_(2) causes the critical point of the system to shift leftward and reduces the area of the phase envelope.In the shale reservoirs of Block A in Gulong of the Daqing Oilfield,China,pronounced confinement effects are observed.At a pore diameter of 10 nm,reservoir fluids progressively exhibit characteristics typical of condensate gas reservoirs.Notably,the CO_(2) content in liquid in 10 nm pores increases by 20.0%compared to that in 100 nm pores,while the CO_(2) content in gas decreases by 10.8%.These findings indicate that confinement effects enhance CO_(2) mass transfer within nanopores,thereby facilitating CO_(2) sequestration and improving microscopic oil recovery.
基金supported by the National Natural Science Foundation of China(Nos.52303380,52025132,52273305,22205185,21621091,22021001,and 22121001)Fundamental Research Funds for the Central Universities(No.20720240041)+3 种基金the 111 Project(Nos.B17027 and B16029)the National Science Foundation of Fujian Province of China(No.2022J02059)the Science and Technology Projects of Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(No.RD2022070601)the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘Excessive Fe^(3+) ion concentrations in wastewater pose a long-standing threat to human health.Achieving low-cost,high-efficiency quantification of Fe^(3+) ion concentration in unknown solutions can guide environmental management decisions and optimize water treatment processes.In this study,by leveraging the rapid,real-time detection capabilities of nanopores and the specific chemical binding affinity of tannic acid to Fe^(3+),a linear relationship between the ion current and Fe^(3+) ion concentration was established.Utilizing this linear relationship,quantification of Fe^(3+) ion concentration in unknown solutions was achieved.Furthermore,ethylenediaminetetraacetic acid disodium salt was employed to displace Fe^(3+) from the nanopores,allowing them to be restored to their initial conditions and reused for Fe^(3+) ion quantification.The reusable bioinspired nanopores remain functional over 330 days of storage.This recycling capability and the long-term stability of the nanopores contribute to a significant reduction in costs.This study provides a strategy for the quantification of unknown Fe^(3+) concentration using nanopores,with potential applications in environmental assessment,health monitoring,and so forth.
基金supported by the National Natural Science Foundation of China(Nos.22125606 and 22241604)Chinese Academy of Sciences Project for Young Scientists in Basic Research(No.YSBR-086)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XBD0750000)the Research Start-up Funding Project of Kashi University(No.GCC2024ZK-014)。
文摘Biomimetic nanozymes opens up new opportunities for sensitive,rapid and field detection of organophosphorus pesticides(OPs).However,it still remains challenges in how to improve the sensitivity and stability of biomimetic nanozymes under harsh conditions.Herein,we synthesized a novel biomimetic nanozyme composed of hemin and bovine serum albumin(BSA)in the nanopores of poly-l-lysine methacryloyl(PLMA)inverse opal hydrogel(PLMA-Hemin-BSA).PLMA-Hemin-BSA achieves superior peroxidase-like activity and shows high stability due to the confinement effect.A multi-enzyme cascade reaction was constructed for the colorimetric detection of five widely used OPs by integrating PLMAHemin-BSA with natural choline oxidase and acetylcholinesterase.The detection limits for dichlorvos,chlorpyrifos,paraoxon,methamidophos,and parathion were as low as 0.024,0.073,0.12,0.56,and 1.4 ng/mL,respectively.More importantly,the average recovery rates and the relative standard deviations(RSD)of chlorpyrifos in paddy water,soil and wheat samples were 86.62%-100.13%and 2.08%-8.65%,which meet the standard of the International Union of Pure and Applied Chemistry(IUPAC,recoveries of 70%-120%with RSD<20%).This study represented advanced methods toward enhancing the activity and stability of biomimetic nanozymes via spatial nanopores-assisted strategy.
基金financially supported by the National Natural Science Foundation of China(Nos.51777097,51577093)。
文摘Constant-current anodization of pure aluminum was carried out in non-corrosive capacitor working electrolytes to study the formation mechanism of nanopores in the anodic oxide films.Through comparative experiments,nanopores are found in the anodic films formed in the electrolytes after high-temperature storage(HTS)at 130°C for 240 h.A comparison of the voltage-time curves suggests that the formation of nanopores results from the decrease in formation efficiency of anodic oxide films rather than the corrosion of the electrolytes.FT-IR and UV spectra analysis shows that carboxylate and ethylene glycol in electrolytes can easily react by esterification at high temperatures.Combining the electronic current theory and oxygen bubble mold effect,the change in electrolyte composition could increase the electronic current in the anodizing process.The electronic current decreases the formation efficiency of anodic oxide films,and oxygen bubbles accompanying electronic current lead to the formation of nanopores in the dense films.The continuous electronic current and oxygen bubbles are the prerequisites for the formation of porous anodic oxides rather than the traditional field-assisted dissolution model.
基金financial support from the National Natural Science Foundation of China (Grant No.52004320)the Science Foundation of China University of Petroleum,Beijing (No.2462021QNXZ012,No.2462022BJRC001,and No.2462021YJRC012)the funding from the State Key Laboratory of Petroleum Resources and Engineering (No.PRP/indep-1-2103)。
文摘It is acknowledged that injecting CO_(2) into oil reservoirs and saline aquifers for storage is a practical and affordable method for CO_(2) sequestration.Most CO_(2) produced from industrial exhaust contains impurity gases such as H_(2)S that might impact CO_(2) sequestration due to competitive adsorption.This study makes a commendable effort to explore the adsorption behavior of CO_(2)/H_(2)S mixtures in calcite slit nanopores.Grand Canonical Monte Carlo(GCMC)simulation is employed to reveal the adsorption of CO_(2),H_(2)S as well as their binary mixtures in calcite nanopores.Results show that the increase in pressure and temperature can promote and inhibit the adsorption capacity of CO_(2) and H_(2)S in calcite nanopores,respectively.CO_(2)exhibits stronger adsorption on calcite surface than H_(2)S.Electrostatic energy plays the dominating role in the adsorption behavior.Electrostatic energy accounts for 97.11%of the CO_(2)-calcite interaction energy and 56.33%of the H_(2)S-calcite interaction energy at 10 MPa and 323.15 K.The presence of H_(2)S inhibits the CO_(2) adsorption in calcite nanopores due to competitive adsorption,and a higher mole fraction of H_(2)S leads to less CO_(2) adsorption.The quantity of CO_(2) adsorbed is lessened by approximately 33%when the mole fraction of H_(2)S reaches 0.25.CO_(2) molecules preferentially occupy the regions near the po re wall and H_(2)S molecules tend to reside at the center of nanopore even when the molar ratio of CO_(2) is low,indicating that CO_(2) has an adsorption priority on the calcite surface over H_(2)S.In addition,moisture can weaken the adsorption of both CO_(2) and H_(2)S,while CO_(2) is more affected.More interestingly,we find that pure CO_(2) is more suitable to be sequestrated in the shallower formations,i.e.,500-1500 m,whereas CO_(2)with H_(2)S impurity should be settled in the deeper reservoirs.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.22373025 and 22227804).
文摘Nanopore sequencing harnesses changes in ionic current as nucleotides traverse a nanopore,enabling real-time decoding of DNA/RNA sequences.The instruments for the dynamic behavior of substances in the nanopore on the molecular scale are still very limited experimentally.This study employs all-atom molecular dynamics(MD)simulations to explore the impact of charge densities on graphene nanopore in the translocation of single-stranded DNA(ssDNA).We find that the magnitude of graphene’s charge,rather than the charge disparity between ssDNA and graphene,significantly influences ssDNA adsorption and translocation speed.Specifically,high negative charge densities on graphene nanopores are shown to substantially slow down ssDNA translocation,highlighting the importance of hydrodynamic effects and electrostatic repulsions.This indicates translocation is crucial for achieving distinct ionic current blockades,which plays a central role for DNA sequencing accuracy.Our findings suggest that negatively charged graphene nanopores hold considerable potential for optimizing DNA sequencing,marking a critical advancement in this field.
基金supported by the National Natural Science Foundation of China(Grant No.52222402,52234003 and 52074235)Sichuan Science and Technology Program(NO:2022JDJQ0009 and No.2023NSFSC0934)+2 种基金the Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(Grant No.2020CX020202)the Deep Marine Shale Gas Efficient Development Overseas Expertise Introduction Center for Discipline Innovation(111 Center)the China Postdoctoral Science Foundation(Grant No.2022M722638).
文摘During the development of shale gas,various issues such as low individual well production,rapid decline,limited reservoir control,and low recovery rates have arisen.Enhancing shale gas reservoir recovery rates has consistently been a focal point and challenge within the industry.Therefore,this paper employs molecular dynamic(MD)simulation methods to study the adsorption and diffusion characteristics of CH_(4)/CO_(2)at different temperatures and mixing ratios.It compares the effects of temperature and CH_(4)/CO_(2)molar ratio changes on the selectivity coefficient,adsorption capacity,and diffusion coefficient of CH_(4)/CO_(2).The paper also plots the displacement interface and the function of CH_(4)/CO_(2)injection/residual amounts over time.Furthermore,it analyzes the adsorption capacity of molecules on the graphene surface,the migration capacity of molecules in the slit,and the displacement process of CH_(4)by CO_(2)on the nanoscale,revealing the microscopic mechanism of CH_(4)/CO_(2)competitive adsorption and displacement.The research results indicate that the influence of temperature on the selectivity coefficient is not significant,with an average decrease of 3%for every 20 K rise in temperature.Pressure has a more pronounced effect on the selectivity coefficient,with values around 1.4 at low pressures and around 1.2 at high pressures.Elevating the mole fraction of CO_(2)in the binary gas mixture results in an increase in the total adsorption amount and an accelerated variation of adsorption amount with pressure.As the CH_(4)mole fraction rises,the diffusion coefficient of CH_(4)increases,while the diffusion coefficient of CO_(2)diminishes with an increasing CO_(2)mole fraction.Under identical conditions,CO_(2)exhibits a stronger adsorption capacity over CH_(4)in shale organic nanopores,resulting in a concave moon-shaped displacement interface in the model.The larger the pre-adsorption pressure of CO_(2),the more intense the movement of CO_(2)along the graphene surface,and the faster the diffusion speed of CO_(2)along the wall.In a displacement pore(the pore space used to provide the displacement location or site)with a diameter of 3 nm,at smaller pressure differentials(≤10 MPa),the residual amount of CH_(4)remains relatively stable without substantial alteration.However,at a pressure differential of 20 MPa,the residual amount of CH_(4)decreases rapidly,and the displacement efficiency significantly improves.
基金financially supported by the Fund for Shanxi ‘‘1331 Project’’ Key Innovative Research Team (No.1331KIRT)the Natural Science Foundation of Shanxi Province (No.201801D121093)the Key Innovative Research Team in Science and Technology of Shanxi Province (No.201805D131001)
文摘Nearly equiatomic nickel–titanium(NiTi) alloy is an ideal implant biomaterial because of its shape memory effect, superelasticity, low elastic modulus as well as other desirable properties.However, it is prone to infection because of its poor antibacterial ability.The present work incorporated Cu into Ni–Ti–O nanopores(NP–Cu) anodically grown on the NiTi alloy to enhance its antibacterial ability, which was realized through electrodeposition.Our results show that incorporation of Cu(0.78 at%–2.37 at%)has little influence on the NP diameter, length and morphology.The release level of Cu ions is in line with loadage which may be responsible for the improved antibacterial ability of the NiTi alloy to combat possible bacterial infection in vivo.Meanwhile, the NP–Cu shows better cytocompatibility and even can promote proliferation of bone marrow mesenchymal stem cells(BMSCs),up-regulate collagen secretion and extracellular matrix mineralization when compared with Cu-free sample.Better antibacterial ability and cytocompatibility of the NP–Cu render them to be promising when serving as NiTi implant coatings.
基金Supported by the National Natural Science Foundation of China(21376116)A PAPD Project of Jiangsu Higher Education Institution
文摘The flow behavior of pressure-driven water infiltration through graphene-based slit nanopores has been studied by molecular simulation.The simulated flow rate is close to the experimental values,which demonstrates the reasonability of simulation results.Water molecules can spontaneously infiltrate into the nanopores,but an external driving force is generally required to pass through the whole pores.The exit of nanopore has a large obstruction on the water effusion.The flow velocity within the graphene nanochannels does not display monotonous dependence upon the pore width,indicating that the flow is related to the microscopic structures of water confined in the nanopores.Extensive structures of confined water are characterized in order to understand the flow behavior.This simulation improves the understanding of graphene-based nanofluidics,which helps in developing a new type of membrane separation technique.
基金support of the Tertiary Oil Recovery Program (TORP)the Kansas Interdisciplinary Carbonates Consortium (KICC) at the University of Kansas
文摘Organic-rich shale resources remain an important source of hydrocarbons considering their substantial contribution to crude oil and natural gas production around the world. Moreover, as part of mitigating the greenhouse gas effects due to the emissions of carbon dioxide （CO2） gas, organic-rich shales are considered a possible alternate geologic storage. This is due to the adsorptive properties of organic ke- rogen and clay minerals within the shale matrix. Therefore, this research looks at evaluating the seques- tration potential of carbon dioxide （CO2） gas in kerogen nanopores with the use of the lattice Boltzmann method under varying experimental pressures and different pore sizes. Gas flow in micro/nano pores differ in hydrodynamics due to the dominant pore wall effects, as the mean free path （λ） of the gas molecules become comparable to the characteristic length （H） of the pores. In so doing, the traditional computational methods break down beyond the continuum region, and the lattice Boltzmann method （LBM） is employed. The lattice Boltzmann method is a mesoscopic numerical method for fluid system, where a unit of gas particles is assigned a discrete distribution function （/）. The particles stream along de- fined lattice links and collide locally at the lattice sites to conserve mass and momentum. The effects of gas-wall collisions （Knudsen layer effects） is incorporated into the LBM through an effective-relaxation- time model, and the discontinuous velocity at the pore walls is resolved with a slip boundary condition. Above all, the time lag （slip effect） created by CO2 gas molecules due to adsorption and desorption over a time period, and the surface diffusion as a result of the adsorption-gradient are captured by an adsorption isotherm and included in our LBM. Implementing the Langmuir adsorption isotherm at the pore walls for both CO2 gas revealed the underlying flow mechanism for CO2 gas in a typical kerogen nano-pore is dominated by the slip flow regime. Increasing the equilibrium pressure, increases the mass flux due to ad- sorption. On the other hand, an increase in the nano-pore size caused further increase in the mass flux due to free gas and that due to adsorbed gas. Thus, in the kerogen nano-pores, CO2 gas molecules are more adsorptive indicating a possible multi-layer adsorption. Therefore, this study not only provides a clear un- derstanding of the underlying flow mechanism of CO2 in kerogen nano-pores, but also provides a potential alternative means to mitigate the greenhouse gas effect （GHG） by sequestering CO2 in organic-rich shales.
基金supported by the National Natural Science Foundation of China(No.52004303)Beijing Natural Science Foundation(No.3212020).
文摘With the increasing demand for petroleum,shale oil with considerable reserves has become an important part of global oil resources.The shale oil reservoir has a large number of nanopores and a complicated mineral composition,and the effect of nanopore confinement and pore type usually makes the effective development of shale oil challenging.For a shale oil reservoir,CO_(2) flooding can effectively reduce the oil viscosity and improve the reservoir properties,which can thus improve the recovery performance.In this study,the method of non-equilibrium molecular dynamics(NEMD)simulation is used to simulate the CO_(2) flooding process in the nanoscale pores of shale oil reservoir.The performance difference between the organic kerogen slit nanopore and four types of inorganic nanopores is discussed.Thus,the effects of nanopore type and displacement velocity on the nanoscale displacement behavior of CO_(2) are analyzed.Results indicate that the CO_(2) flooding process of different inorganic pores is different.In comparison,the displacement efficiency of light oil components is higher,and the transport distance is longer.The intermolecular interaction can significantly affect the CO_(2) displacement behavior in nanopores.The CO_(2) displacement efficiency is shown as montmorillonite,feldspar>quartz>calcite>kerogen.On the other hand,it is found that a lower displacement velocity can benefit the miscibility process between alkane and CO_(2),which is conducive to the overall displacement process of CO_(2).The displacement efficiency can significantly decrease with the increase in displacement velocity.But once the displacement velocity is very high,the strong driving force can promote the alkane to move forward,and the displacement efficiency will recover slightly.This study further reveals the microscopic oil displacement mechanism of CO_(2) in shale nanopores,which is of great significance for the effective development of shale oil reservoirs by using the method of CO_(2) injection.
基金Project supported by the Major Research Plan from the Ministry of Science and Technology of China(Grant No.2011CB921900)the China Postdoctoral Science Foundation(Grant Nos.20090460145 and 201003009)+2 种基金the Fundamental Research Funds for the Central Universities of China(Grant No.201012200053)the Science and Technology Program of Hunan Province of China (Grant No.2010DFJ411)the Science Development Foundation of Central South University,China(Grant Nos.08SDF02 and 09SDF09)
文摘A biosensor device, built from graphene nanoribbons （GNRs） with nanopores, was designed and studied by first- principles quantum transport simulation. We have demonstrated the intrinsic transport properties of the device and the effect of different nucleobases on device properties when they are located in the nanopores of GNRs. It was found that the device＇s current changes remarkably with the species of nucleobases, which originates from their different chemical compositions and coupling strengths with GNRs. In addition, our first-principles results clearly reveal that the distinguished ability of a device＇s current depends on the position of the pore to some extent. These results may present a new way to read off the nucleobases sequence of a single-stranded DNA （ssDNA） molecule by such GNRs-based device with designed nanopores
基金supported by the UQ Graduate School Scholarships(UQGSS),funded by the University of Queenslandsupported by the National Health and Medical Research Council(NHMRC)Early Career Fellowship(APP1140699)supported by a grant from the ITI Foundation,Switzerland。
文摘Electrochemical anodization(EA)is a simple and cost-effective technique to fabricate controlled nanostructures on Ti substrates,such as TiO_(2)nanotubes and nanopores.Electrolyte aging of organic EA electrolytes(repeated EA using non-target Ti before EA of target Ti)is recognized to influence the characteristics of the anodized nanostructures.However,there is limited information about how surface topography and electrolyte aging dictate the formation and characteristics of the anodized nanostructures.In the current study,short-time EA(starting at 10 s)of micro-machined Ti substrates was performed with electrolytes of various ages(fresh/unused,15 h aged and 30 h aged),followed by evaluation of the TiO_(2)nanopores(TNPs)characteristics in terms of topography,chemistry,stability and protein adhesion.The results showed that aligned TNPs were obtained earlier(120 s)with fresh electrolyte as compared to the aged electrolyte EA(600 s).Interestingly,TNPs fabricated using fresh electrolyte(at lower EA times)showed favorable wettability,protein adhesion capacity and mechanical properties compared with aged electrolyte counterparts.The findings of the study demonstrate how nanopore formation differs between fresh and aged electrolytes when performing EA of micro-machined Ti,which provides an improved understanding of electrolyte aging and its influence on anodized nanostructures.
基金financial support from National Natural Science Found of China (No. 21273138)
文摘Latent heat storage performance of a layered perovskite-type compound, 1-C14H29NH3）2ZnCl4（C14Zn）,embedded in a series of silica gel（SG） with pore sizes of d = 15–200 nm is investigated using differential scanning calorimetry（DSC）, and powder X-ray diffractions（XRD）. C14Zn in the nanopores of silica gel shows size-dependent phase transition temperature, enthalpy change and supercooling. They have a stable transition temperature and heat capacity at each size in a short-term thermal cycling. Similar Xray diffraction patterns are observed for the nano-sized and the bulk C（14）Zn. The encapsulation of a phase change material in nanopores is a new way of tuning its thermal energy storage properties for a wider range of temperature regulation.
基金financially supported by the National Natural Science Foundation of China (No. 21505076)the Young Elite Scholar Support (YESS) Program from China Association for Science and Technology (No. YESS20150009)+2 种基金the Program of Jiangsu Specially-Appointed Professor, the Natural Science Foundation of Jiangsu Province of China (No. BK20150967)the Innovation Team Program of Jiangsu Province of Chinathe Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Solid-state nanopore in analytical chemistry has developed rapidly in the 1990s and it is proved to be a versatile new tool for bioanalytical chemistry. The research field of solid-state nanopore starts from mimicking the biological nanopore in living cells. Understanding the transport mechanism of biological nanopore in vivo is a big challenge because of the experimental difficulty, so it is essential to establish the basic research of artificial nanopores in vitro especially for the analysis of ions and small molecules. The performance of solid-state nanopores could be evaluated by monitoring currents when ions and molecules passed through. The comparison of the two types of nanopores based on current-derived information can reveal the principle of biological nanopores, while the solid-state nanopores are applied into practical bioanalysis. In this review, we focus on the researches of the solid-state nanopores in the fabrication process and in the analysis of ions and small molecules. Fabrication methods of nanopores,ion transport mechanism, small molecule analysis and theoretical studies are discussed in detail.
基金National Science and Technology Major project“Main controlling factors of large lithologic reservoir formation and favorable zone evaluation(2017ZX05001-002)”。
文摘The Qingshankou Formation shale oil in the Gulong Sag is an important oil and gas reservoir in the Daqing oilfield,with geological resources of 15.1 billion tons.The fabric of shale can reflect not only its genesis but also the nature of the reservoir space,its physical properties,oil content,and development value.Here,the characteristics of clay minerals in the Gulong shale oil reservoir were studied via electron microscopy,with the primary focus on the microfabrics and reservoir space;thereafter,the in situ accumulation was studied and discussed.Electron backscattering patterns revealed that nanometer pores and fissures were well developed in the Gulong shale oil reservoir.The nano pores were mostly 20-50 nm in diameter(median 20-30 nm),irregularly shaped,mostly,polygonal,and connected with nanofissures.The widths of nanofissures ranged mostly between 10-50 nm(median 20-30 nm);moreover,these fissures were mainly formed by F-F condensation of clay sheets(clay domains).The coagulation of clays was closely related to organic matter,especially algae.The clay colloids were negatively charged due to isocrystalline replacement;hence,metal cations were absorbed around the clay,forming a positive clay group.The positively charged clays subsequently adsorbed negatively charged humic acid(organic matter)and initially degraded algae to form an organic clay flocculant.When the organic clay flocculates reached the threshold for hydrocarbon generation and expulsion,the volume of organic matter decreased by 87%;thereafter,the generated and expelled hydrocarbon filled the nearby pores formed by this contraction.Moreover,the discharged hydrocarbon could not migrate due to capillary resistance(~12 MPa)of the nanopores;hence,the nanopores formed a unique continuous in situ reservoir within the Gulong shale oil.This study demonstrated that the Gulong shale oil reservoir is an actual clay-type shale reservoir with numerous nanopore and fissures.During coagulation,a large amount of organic matter(including layered algae)was absorbed by the clay,forming an organic clay condensate that could have provided the material foundation for hydrocarbon generation at a later stage.Thermal simulation experiments revealed that the volume of organic matter decreased sharply after hydrocarbon generation and expulsion.
基金Supported by the National Natural Science Foundation of China under Grant No 11335003
文摘A polymeric nanopore membrane with selective ionic transport has been proposed as a potential device to convert the chemical potential energy in salinity gradients to electrical power. However, its energy conversion efficiency and power density are often limited due to the challenge in reliably controlling the size of the nanopores with the conventional chemical etching method. Here we report that without chemical etching, polyimide （PI） membranes irradiated with GeV heavy ions have negatively charged nanopores, showing nearly perfect selectivity for cations over anions, and they can generate electrical power from salinity gradients. We further demonstrate that the power generation efficiency of the PI membrane approaches the theoretical limit, and the maximum power density reaches 130m W/m2 with a modified etching method, outperforming the previous energy conversion device that was made of polymeric nanopore membranes.
基金supported by the National Science Foundation of China(21878144,21838004 and 21776123)the Foundation for Innovative Research Groups of the National Natural Science Foun-dation of China(21921006).
文摘Ca^(2+)/Na+separation is a common problem in industrial applications,biological and medical fields.However,Ca^(2+)and Na+have similar ionic radii and hydration radii,thus Ca^(2+)/Na+separation is challenging.Inspired by biological channels,group modification is one of the effective methods to improve the separation performance.In this work,molecular dynamics simulations were performed to investigate the effects of different functional groups(COO,NH3+)on the separation performance of Ca^(2+)and Na+through graphene nanopores under an electric field.The pristine graphene nanopore was used for comparison.Results showed that three types of nanopores preferred Ca^(2+)to Na+,and Ca^(2+)/Na+selectivity followed the order of GE-COO(4.06)>GE(1.85)>GE-NH3+(1.63).Detailed analysis of ionic hydration microstructure shows that different nanopores result in different hydration factors for the second hydration layer of Ca^(2+)and the first layer of Na+.Such different hydration factors corresponding to the dehydration ability can effectively evaluate the separation performance.In addition,the breaking of hydrogen bonds between water molecules due to electrostatic effects can directly affect the dehydration ability.Therefore,the electrostatic effect generated by group modification will affect the ionic hydration microstructure,thus reflecting the differences in dehydration ability.This in turn affects the permeable and separation performance of cations.The results of this work provide perceptive guidelines for the application of graphene-based membranes in ion separation.
基金supported by the National Natural Science Foundation for Youths of China(Grant No.12201374)the Scientific Research Foundation of Education Department of Shaanxi Province(Grant No.22JK0315)+2 种基金the Research Foundation for the Doctoral Program of Shaanxi University of Technology(Grant No.SLGRCQD2136)the Key R&D Plan,Shaanxi Province(2022GY-138)the Science and Technology Plan Project,Guizhou Province([2022]ZD005).
文摘Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a novel transient model to describe oil transport in unsteady and steady states. The model incorporates the effect of the critical shift density, apparent viscosity, slip length, and alkane property, as well as pore tortuosity and surface roughness. We evaluated our model through a comparison with other models, experiments, and molecular dynamics simulations. The results show that the development rates of the volume flows of C_(6)–C_(12) alkane confined in inorganic nanopores and C_(12) alkane confined in organic nanopores were faster than that of the corresponding bulk alkane. In addition, the critical drift density positively promoted the volume flow development rate in the unsteady state and negatively inhibited the mass flow rate in the steady state. This effect was clearest in pores with a smaller radius and lower-energy wall and in alkane with shorter chain lengths. Furthermore, both the nanoconfinement effect and pore structure determined whether the volume flow enhancement rate was greater than or less than 1. The rate increased or decreased with time and was controlled mainly by the nanoconfinement effect. Moreover, as the wall energy increased, the flow inhibition effect increased;as the carbon number of alkane increased, the flow promotion effect increased. The results indicate that the proposed model can accurately describe oil transport in shale nanopores.
