Inadequate strength and stability of active crude oil emulsions stabilized by conventional surfactants always lead to a limited plugging rate of plugging agents.Thus,to address this issue,the synthesis of amphiphilic ...Inadequate strength and stability of active crude oil emulsions stabilized by conventional surfactants always lead to a limited plugging rate of plugging agents.Thus,to address this issue,the synthesis of amphiphilic Janus nanosheets was effectively carried out for enhancing the system performances and subsequently characterized.Based on the outcomes of orthogonal tests,an assessment was conducted on the nanosheet and surfactant formulations to optimize the enhancement of emulsion properties.The experimental demonstration of the complex system has revealed its remarkable emulsifying capability,ability to decrease interfacial tension and improve rheological behavior at high temperature(80℃)and high salinity(35,000 ppm)conditions.Involving probable mechanism of the system performance enhancement is elucidated by considering the synergistic effect between surfactants and nanosheets.Furthermore,variables including water-to-oil ratio,salinity,temperature and stirring intensity during operation,which affect the properties of prepared emulsions,were investigated in detail.The efficacy and stability of the complex system in obstructing medium and high permeability cores were demonstrated.Notably,the core with a high permeability of 913.58 mD exhibited a plugging rate of 98.55%.This study establishes the foundations of medium and high permeability reservoirs plugging with novel active crude oil plugging agents in severe environments.展开更多
A new definition of the dual descriptor,namely,thethermodynamic dual descriptor,is developed within the grand canonicalpotential formalism.This new definition is formulated to describe the same △f_r(r)=β/2C[f^+(r)-f...A new definition of the dual descriptor,namely,thethermodynamic dual descriptor,is developed within the grand canonicalpotential formalism.This new definition is formulated to describe the same △f_r(r)=β/2C[f^+(r)-f^-(r)](C>0) physical phenomenon as the original definition proposed by Morell,Grand,and Toro-Labbé(J.Phys.Chem.A2005,109,205),which is characterized by a second-order response of the electron density towards an electron flux.To formulate the new definition,we performed two successive partial derivatives of the average electron density,one with respect to the average number of electrons,and the other with respect to the chemical potential of the electron reservoir.When the derivative is expressed in terms of the three-state ensemble model,in the regime of low temperatures up to temperatures of chemical interest,one finds that the thermodynamic dual descriptor can be expressed as?f_T(r)=(β/2)C[f^+(r)-f^-(r)],whereβ=1/k_BT,Cis a global quantity that depends on the temperature and global electronic properties of the molecule(the first ionization potential and the electron affinity),C=1 for systems with zero fractional charge,and C=C_ω>0(albeit very close to zero)for systems with nonzero fractional charge,,and f^+(r)and f^-(r)are the nucleophilic and electrophilic Fukui functions,respectively.The quantity within the square brackets is the original definition of the dual descriptor.As the local terms(the ones containing regioselectivity information)are equal to those of the dual descriptor,?f_T(r)has the same regioselectivity information,multiplied by the global quantity(β/2)C.This implies that the regioselectivity information contained in the original dual descriptor is preserved at all temperatures different from zero,and for any value of C>0.One of the most important features of this new definition is that it avoidsthe undesired Dirac delta behavior observed when the second order partial derivative of the average density is taken with respect to the average number of electrons,using the exact density dependence of the average number of electrons.展开更多
Nanofluid offers more opportunities and challenges over the traditional surfactant and polymer solutions during enhanced oil recovery(commonly referred to as tertiary oil recovery)due to its remarkable properties.This...Nanofluid offers more opportunities and challenges over the traditional surfactant and polymer solutions during enhanced oil recovery(commonly referred to as tertiary oil recovery)due to its remarkable properties.This review mainly discusses the preparation methods of amphiphilic nanoparticles due to their higher interface activity than sole hydrophilic or hydrophobic nanoparticles(SHNPs).The nanofluids’stability is reviewed in this work.Moreover,the mechanisms of nanofluids in enhancing oil recovery(N-EOR)in terms of interfacial tension reduction,wettability alteration,foam stabilization,emulsion stabilization,structural disjoining pressure,and depressurization-increasing injection are mainly summarized and reviewed.Also,the synergistic effects of nanofluids and traditional surfactants and polymers are discussed.Finally,nanofluids’challenges and prospects are also outlined.The nanofluids can still be regarded as an outstanding candidate for enhancing oil recovery significantly in the future although there are limitations on their applications from laboratory scale to field scale.展开更多
A bimodal mesoporous silica(BMMS) modified with amphiphilic compound(C_(19)H_(42)N)_3(PMo_(12)O_(40))(CTA-PMO) was prepared by the two-step impregnation method. Firstly, H3PMo12O40 was introduced into the bimodal meso...A bimodal mesoporous silica(BMMS) modified with amphiphilic compound(C_(19)H_(42)N)_3(PMo_(12)O_(40))(CTA-PMO) was prepared by the two-step impregnation method. Firstly, H3PMo12O40 was introduced into the bimodal mesoporous silica via impregnation, then C_(19)H_(42)NBr(CTAB) was grafted on the surface of BMMS containing H3PMo12O40 based on the chemical reaction between quaternary ammonium compound and the phosphomolybdic acid, and then the catalyst CTAPMO/BMMS was obtained. The samples were characterized by XRD, N_2 adsorption and desorption, FTIR, 31P-NMR, 29Si-NMR and TEM analyses. It is shown that the catalyst has a typical bimodal mesoporous structure, in which the small mesopore diameter is about 3.0 nm and the large mesopore diameter is about 5.0 nm. The chemical interaction happens between the Keggin structure and silica group of BMMS. Compared with the mono-modal porous Hβ and SBA-15 zeolites modified with CTA-PMO, CTA-PMO/BMMS showed better catalytic activity in the oxidative conversion of dibenzothiophene(DBT), and the desulfurization rate can reach about 94% with the help of extraction, and the catalyst can be separated by filtration and reused directly. The catalytic oxidative desulfurization mechanism on CTA-PMO/BMMS was proposed and verified.展开更多
Owing to the increasingly serious environmental issues caused by the sulfur burnt in fuel, desulfurization has become an important topic. In this work, an amphiphilic oxygen-defective tungsten oxide was synthesized by...Owing to the increasingly serious environmental issues caused by the sulfur burnt in fuel, desulfurization has become an important topic. In this work, an amphiphilic oxygen-defective tungsten oxide was synthesized by a colloidal chemistry method. The amphiphilic property and oxygen defects were well characterized, and the structure of the oxygen-defective tungsten oxide catalyst was investigated. In addition, the catalyst was employed in oxidative desulfurization system of fuel,and deep desulfurization was achieved. It was found that the very high oxidative desulfurization performance of oxygendefective tungsten oxide catalyst resulted from both the amphiphilic property and oxygen defects. This work can provide a strategy for preparation of highly active metal oxide catalysts with oxygen defects in oxidative desulfurization reaction of fuel.展开更多
Amphiphilic polymer gels are widely used in heterogeneous reservoirs for conformance control technology.However,in high temperature and high salinity of calcium and magnesium reservoirs,amphiphilic polymer gels cannot...Amphiphilic polymer gels are widely used in heterogeneous reservoirs for conformance control technology.However,in high temperature and high salinity of calcium and magnesium reservoirs,amphiphilic polymer gels cannot maintain effective performance.In this work,a novel reinforced amphiphilic polymer gel(F-PADC gel)was prepared by physically mixing polymer solution and fly ash(FA),which is an extremely low cost material.The viscoelasticity and stability of the F-PADC gel were studied by rheometry and micro-rheometry.The reinforced mechanism of FA on amphiphilic polymer gels was revealed.The results show that the addition of FA can make the gel more robust with a denser network structure.On the fifth day,the elastic modulus(G’)increases from 5.2 to 7.0 Pa and the viscosity modulus(G")increases from 0.4 to 0.6 Pa at the frequency of 1 Hz,which improves the viscoelasticity of the gel system.More importantly,the F-PADC gel does not degrade after aging at 85℃for 180 d.And its viscoelasticity increases obviously,G′and G"increase to 110.0 Pa and 3.5 Pa,respectively,showing excellent anti-aging stability.Moreover,FA amphiphilic polymer gels have a good injectivity and a perfect plugging rate of 98.86%,which is better than that of sole amphiphilic polymer gels.This novel mixed FA amphiphilic polymer gels can prove to be a better alternative to conventional polymer gels to enhance oil recovery in high temperature and high salinity reservoirs.展开更多
In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by selfassembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam)(PHCS-g-PNVCL) in aqueous medium. The employed b...In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by selfassembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam)(PHCS-g-PNVCL) in aqueous medium. The employed biocompatible amphiphilic polymer was synthesized by grafting the carboxyl terminated poly(N-vinylcaprolactam)(PNVCL-COOH) chains onto N-phthaloylchitosan(PHCS) backbone.~1H NMR and FTIR results confirmed the molecular structure of the copolymers. The morphology of the supramicelles assembled by PHCS-g-PNVCL was revealed by means of TEM and polarized light microscope. In solution, the supramicelles were very stable as monitored by DLS and zeta potential measurements. Temperature and p H presented significant influences on the size and size distribution of the supramicelles. These supramicelles with multicompartment hydrophobic cores should be ideal biomimetic systems with promising applications in drug delivery.展开更多
Bilayer membranes self-assembled from amphiphilic molecules such as lipids, surfactants, and block copolymers are ubiquitous in biological and physiochemical systems. The shape and structure of bilayer membranes depen...Bilayer membranes self-assembled from amphiphilic molecules such as lipids, surfactants, and block copolymers are ubiquitous in biological and physiochemical systems. The shape and structure of bilayer membranes depend crucially on their mechanical properties such as surface tension, bending moduli, and line tension. Understanding how the molecular properties of the amphiphiles determine the structure and mechanics of the self-assembled bilayers requires a molecularly detailed theoretical framework. The self-consistent field theory provides such a theoretical framework, which is capable of accurately predicting the mechanical parameters of self-assembled bilayer membranes. In this mini review we summarize the formulation of the self-consistent field theory, as exemplified by a model system composed of flexible amphiphilic chains dissolved in hydrophilic polymeric solvents, and its application to the study of self-assembled bilayer membranes.展开更多
Janus amphiphilic polymer nanosheets(JAPNs)with anisotropic morphology and distinctive perfor-mance have aroused widespread interest.However,due to the difficulty in synthesis and poor dispersion stability,JAPNs have ...Janus amphiphilic polymer nanosheets(JAPNs)with anisotropic morphology and distinctive perfor-mance have aroused widespread interest.However,due to the difficulty in synthesis and poor dispersion stability,JAPNs have been scarcely reported in the field of enhancing oil recovery(EOR).Herein,a kind of organic-based flexible JAPNs was prepared by paraffin emulsion methods.The lateral sizes of JAPNs were ranging from hundreds of nanometers to several micrometers and the thickness was about 3 nm.The organic-based nanosheets were equipped with remarkably flexible structures,which could improve their injection performance.The dispersion and interfacial properties of JAPNs were studied systematically.By modification of crosslinking agent containing multiple amino groups,the JAPNs had excellent hydro-philicity and salt resistance compared with conventional inorganic or composite nanosheets.The settling time of nanosuspension with NaCl and CaCl_(2) at a low salinity of 1000 mg/L was over 240 h.The value could also remain 124 h under the salinity of 10,000 mg/L NaCl.With the dual functionalities of Janus amphiphilic nature and nanoparticles'Pickering effect,JAPNs could change rock wettability and form emulsions as"colloidal surfactants",In particular,a new technology called optical microrheology was pioneered to explore the destabilization state of nanosuspensions for the first time.Since precipitation lagged behind aggregation,especially for stable suspension systems,the onset of the unstable behavior was difficult to be detected by conventional methods,which should be the indicator of reduced effec-tiveness for nanofluid products.In addition,the oil displacement experiments demonstrated that the JAPNs could enhance oil recovery by 17.14%under an ultra-low concentration of 0.005%and were more suitable for low permeability cores.The findings can help for a better understanding of the material preparation of polymer nanosheets.We also hope that this study could shed more light on the nano-flooding technology for EOR.展开更多
The N-terminal amphiphilic helices of proteins Epsin,Sarlp,and Arfl play a critical role in initiating membrane deformation.The interactions of these amphiphilic helices with the lipid membranes are investigated in th...The N-terminal amphiphilic helices of proteins Epsin,Sarlp,and Arfl play a critical role in initiating membrane deformation.The interactions of these amphiphilic helices with the lipid membranes are investigated in this study by combining the all-atom and coarse-grained simulations.In the all-atom simulations,the amphiphilic helices of Epsin and Sarlp are found to have a shallower insertion depth into the membrane than the amphiphilic helix of Arfl,but remarkably,the amphiphilic helices of Epsin and Sat lp induce higher asymmetry in the lipid packing between the two monolayers of the membrane.The insertion depth of amphiphilic helix into the membrane is determined not only by the overall hydrophobicity but also by the specific distributions of polar and non-polar residues along the helix.To directly compare their ability to deform the membrane,the coarse-grained simulations are performed to investigate the membrane deformation under the insertion of multiple helices.展开更多
基金financially supported by National Natural Science Foundation of China(52374053)Beijing Natural Science Foundation(2204092)Beijing Municipal Excellent Talent Training Funds Youth Advanced Individual Project(2018000020124G163)。
文摘Inadequate strength and stability of active crude oil emulsions stabilized by conventional surfactants always lead to a limited plugging rate of plugging agents.Thus,to address this issue,the synthesis of amphiphilic Janus nanosheets was effectively carried out for enhancing the system performances and subsequently characterized.Based on the outcomes of orthogonal tests,an assessment was conducted on the nanosheet and surfactant formulations to optimize the enhancement of emulsion properties.The experimental demonstration of the complex system has revealed its remarkable emulsifying capability,ability to decrease interfacial tension and improve rheological behavior at high temperature(80℃)and high salinity(35,000 ppm)conditions.Involving probable mechanism of the system performance enhancement is elucidated by considering the synergistic effect between surfactants and nanosheets.Furthermore,variables including water-to-oil ratio,salinity,temperature and stirring intensity during operation,which affect the properties of prepared emulsions,were investigated in detail.The efficacy and stability of the complex system in obstructing medium and high permeability cores were demonstrated.Notably,the core with a high permeability of 913.58 mD exhibited a plugging rate of 98.55%.This study establishes the foundations of medium and high permeability reservoirs plugging with novel active crude oil plugging agents in severe environments.
基金PWA thanks NSERC for support from the Canada Research Chairs, Compute Canada, and an NSERC Discovery Grant. MFP thanks Universidad Autonoma Metropolitana-Iztapalapa for a Visiting Professor Invitation. JLG and AV thank Conacyt for Grants 237045 and 128369
文摘A new definition of the dual descriptor,namely,thethermodynamic dual descriptor,is developed within the grand canonicalpotential formalism.This new definition is formulated to describe the same △f_r(r)=β/2C[f^+(r)-f^-(r)](C>0) physical phenomenon as the original definition proposed by Morell,Grand,and Toro-Labbé(J.Phys.Chem.A2005,109,205),which is characterized by a second-order response of the electron density towards an electron flux.To formulate the new definition,we performed two successive partial derivatives of the average electron density,one with respect to the average number of electrons,and the other with respect to the chemical potential of the electron reservoir.When the derivative is expressed in terms of the three-state ensemble model,in the regime of low temperatures up to temperatures of chemical interest,one finds that the thermodynamic dual descriptor can be expressed as?f_T(r)=(β/2)C[f^+(r)-f^-(r)],whereβ=1/k_BT,Cis a global quantity that depends on the temperature and global electronic properties of the molecule(the first ionization potential and the electron affinity),C=1 for systems with zero fractional charge,and C=C_ω>0(albeit very close to zero)for systems with nonzero fractional charge,,and f^+(r)and f^-(r)are the nucleophilic and electrophilic Fukui functions,respectively.The quantity within the square brackets is the original definition of the dual descriptor.As the local terms(the ones containing regioselectivity information)are equal to those of the dual descriptor,?f_T(r)has the same regioselectivity information,multiplied by the global quantity(β/2)C.This implies that the regioselectivity information contained in the original dual descriptor is preserved at all temperatures different from zero,and for any value of C>0.One of the most important features of this new definition is that it avoidsthe undesired Dirac delta behavior observed when the second order partial derivative of the average density is taken with respect to the average number of electrons,using the exact density dependence of the average number of electrons.
基金financial support of the Science Foundation of China University of PetroleumBeijing(Grant No.2462020XKBH013)+1 种基金Financial supports from the National Natural Science Foundation of China(Grant No.51804316)the Science Foundation of China University of Petroleum,Beijing(Grant No.2462017YJRC037)
文摘Nanofluid offers more opportunities and challenges over the traditional surfactant and polymer solutions during enhanced oil recovery(commonly referred to as tertiary oil recovery)due to its remarkable properties.This review mainly discusses the preparation methods of amphiphilic nanoparticles due to their higher interface activity than sole hydrophilic or hydrophobic nanoparticles(SHNPs).The nanofluids’stability is reviewed in this work.Moreover,the mechanisms of nanofluids in enhancing oil recovery(N-EOR)in terms of interfacial tension reduction,wettability alteration,foam stabilization,emulsion stabilization,structural disjoining pressure,and depressurization-increasing injection are mainly summarized and reviewed.Also,the synergistic effects of nanofluids and traditional surfactants and polymers are discussed.Finally,nanofluids’challenges and prospects are also outlined.The nanofluids can still be regarded as an outstanding candidate for enhancing oil recovery significantly in the future although there are limitations on their applications from laboratory scale to field scale.
基金financially supported by the Program for Liaoning Excellent Talents in Universities(LJQ2015062)the Fushun Science Project(FSKJHT201376)
文摘A bimodal mesoporous silica(BMMS) modified with amphiphilic compound(C_(19)H_(42)N)_3(PMo_(12)O_(40))(CTA-PMO) was prepared by the two-step impregnation method. Firstly, H3PMo12O40 was introduced into the bimodal mesoporous silica via impregnation, then C_(19)H_(42)NBr(CTAB) was grafted on the surface of BMMS containing H3PMo12O40 based on the chemical reaction between quaternary ammonium compound and the phosphomolybdic acid, and then the catalyst CTAPMO/BMMS was obtained. The samples were characterized by XRD, N_2 adsorption and desorption, FTIR, 31P-NMR, 29Si-NMR and TEM analyses. It is shown that the catalyst has a typical bimodal mesoporous structure, in which the small mesopore diameter is about 3.0 nm and the large mesopore diameter is about 5.0 nm. The chemical interaction happens between the Keggin structure and silica group of BMMS. Compared with the mono-modal porous Hβ and SBA-15 zeolites modified with CTA-PMO, CTA-PMO/BMMS showed better catalytic activity in the oxidative conversion of dibenzothiophene(DBT), and the desulfurization rate can reach about 94% with the help of extraction, and the catalyst can be separated by filtration and reused directly. The catalytic oxidative desulfurization mechanism on CTA-PMO/BMMS was proposed and verified.
基金financial support by Students’ Platform for innovation and entrepreneurship training of Jiangsu Province (201810299008z)the National Nature Science Foundation of China (Nos. 21576122, 21722604, 21766007)+1 种基金Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, Hainan Normal University (20150376)the Natural Science Foundation of Jiangsu Provincial Department of Education (17KJA150002)
文摘Owing to the increasingly serious environmental issues caused by the sulfur burnt in fuel, desulfurization has become an important topic. In this work, an amphiphilic oxygen-defective tungsten oxide was synthesized by a colloidal chemistry method. The amphiphilic property and oxygen defects were well characterized, and the structure of the oxygen-defective tungsten oxide catalyst was investigated. In addition, the catalyst was employed in oxidative desulfurization system of fuel,and deep desulfurization was achieved. It was found that the very high oxidative desulfurization performance of oxygendefective tungsten oxide catalyst resulted from both the amphiphilic property and oxygen defects. This work can provide a strategy for preparation of highly active metal oxide catalysts with oxygen defects in oxidative desulfurization reaction of fuel.
基金supported by Key Program of National Natural Science Foundation of China(No.52130401)National Natural Science Foundation of China(No.52104055)+1 种基金China National Postdoctoral Program for Innovative Talents(No.BX20200386)China Postdoctoral Science Foundation(No.2021M703586)。
文摘Amphiphilic polymer gels are widely used in heterogeneous reservoirs for conformance control technology.However,in high temperature and high salinity of calcium and magnesium reservoirs,amphiphilic polymer gels cannot maintain effective performance.In this work,a novel reinforced amphiphilic polymer gel(F-PADC gel)was prepared by physically mixing polymer solution and fly ash(FA),which is an extremely low cost material.The viscoelasticity and stability of the F-PADC gel were studied by rheometry and micro-rheometry.The reinforced mechanism of FA on amphiphilic polymer gels was revealed.The results show that the addition of FA can make the gel more robust with a denser network structure.On the fifth day,the elastic modulus(G’)increases from 5.2 to 7.0 Pa and the viscosity modulus(G")increases from 0.4 to 0.6 Pa at the frequency of 1 Hz,which improves the viscoelasticity of the gel system.More importantly,the F-PADC gel does not degrade after aging at 85℃for 180 d.And its viscoelasticity increases obviously,G′and G"increase to 110.0 Pa and 3.5 Pa,respectively,showing excellent anti-aging stability.Moreover,FA amphiphilic polymer gels have a good injectivity and a perfect plugging rate of 98.86%,which is better than that of sole amphiphilic polymer gels.This novel mixed FA amphiphilic polymer gels can prove to be a better alternative to conventional polymer gels to enhance oil recovery in high temperature and high salinity reservoirs.
基金NSFC Grants(5140306251273063 and 20774030)+4 种基金China Postdoctoral Science Foundation(2013M541485)111 Project Grant(B08021)the Fundamental Research Funds for the Central Universitiesthe higher school specialized research fund for the doctoral program(20110074110003)the Open Project of Engineering Research Center of Materials-Oriented Chemical Engineering of Xinjiang Bingtuan(2015BTRC001)for support of this work
文摘In this paper, pod-like supramicelles with multicompartment hydrophobic cores were prepared by selfassembly of amphiphilic N-phthaloylchitosan-g-poly(N-vinylcaprolactam)(PHCS-g-PNVCL) in aqueous medium. The employed biocompatible amphiphilic polymer was synthesized by grafting the carboxyl terminated poly(N-vinylcaprolactam)(PNVCL-COOH) chains onto N-phthaloylchitosan(PHCS) backbone.~1H NMR and FTIR results confirmed the molecular structure of the copolymers. The morphology of the supramicelles assembled by PHCS-g-PNVCL was revealed by means of TEM and polarized light microscope. In solution, the supramicelles were very stable as monitored by DLS and zeta potential measurements. Temperature and p H presented significant influences on the size and size distribution of the supramicelles. These supramicelles with multicompartment hydrophobic cores should be ideal biomimetic systems with promising applications in drug delivery.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11421101 and 21274005)the Natural Sciences and Engineering Research Council(NSERC)of Canada
文摘Bilayer membranes self-assembled from amphiphilic molecules such as lipids, surfactants, and block copolymers are ubiquitous in biological and physiochemical systems. The shape and structure of bilayer membranes depend crucially on their mechanical properties such as surface tension, bending moduli, and line tension. Understanding how the molecular properties of the amphiphiles determine the structure and mechanics of the self-assembled bilayers requires a molecularly detailed theoretical framework. The self-consistent field theory provides such a theoretical framework, which is capable of accurately predicting the mechanical parameters of self-assembled bilayer membranes. In this mini review we summarize the formulation of the self-consistent field theory, as exemplified by a model system composed of flexible amphiphilic chains dissolved in hydrophilic polymeric solvents, and its application to the study of self-assembled bilayer membranes.
基金supported by the National Natural Science Foundation of China(52074320)Petrochina Strategic Cooperation Science and Technology Project(ZLZX2020-01-04-03)。
文摘Janus amphiphilic polymer nanosheets(JAPNs)with anisotropic morphology and distinctive perfor-mance have aroused widespread interest.However,due to the difficulty in synthesis and poor dispersion stability,JAPNs have been scarcely reported in the field of enhancing oil recovery(EOR).Herein,a kind of organic-based flexible JAPNs was prepared by paraffin emulsion methods.The lateral sizes of JAPNs were ranging from hundreds of nanometers to several micrometers and the thickness was about 3 nm.The organic-based nanosheets were equipped with remarkably flexible structures,which could improve their injection performance.The dispersion and interfacial properties of JAPNs were studied systematically.By modification of crosslinking agent containing multiple amino groups,the JAPNs had excellent hydro-philicity and salt resistance compared with conventional inorganic or composite nanosheets.The settling time of nanosuspension with NaCl and CaCl_(2) at a low salinity of 1000 mg/L was over 240 h.The value could also remain 124 h under the salinity of 10,000 mg/L NaCl.With the dual functionalities of Janus amphiphilic nature and nanoparticles'Pickering effect,JAPNs could change rock wettability and form emulsions as"colloidal surfactants",In particular,a new technology called optical microrheology was pioneered to explore the destabilization state of nanosuspensions for the first time.Since precipitation lagged behind aggregation,especially for stable suspension systems,the onset of the unstable behavior was difficult to be detected by conventional methods,which should be the indicator of reduced effec-tiveness for nanofluid products.In addition,the oil displacement experiments demonstrated that the JAPNs could enhance oil recovery by 17.14%under an ultra-low concentration of 0.005%and were more suitable for low permeability cores.The findings can help for a better understanding of the material preparation of polymer nanosheets.We also hope that this study could shed more light on the nano-flooding technology for EOR.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91427302 and 11474155)
文摘The N-terminal amphiphilic helices of proteins Epsin,Sarlp,and Arfl play a critical role in initiating membrane deformation.The interactions of these amphiphilic helices with the lipid membranes are investigated in this study by combining the all-atom and coarse-grained simulations.In the all-atom simulations,the amphiphilic helices of Epsin and Sarlp are found to have a shallower insertion depth into the membrane than the amphiphilic helix of Arfl,but remarkably,the amphiphilic helices of Epsin and Sat lp induce higher asymmetry in the lipid packing between the two monolayers of the membrane.The insertion depth of amphiphilic helix into the membrane is determined not only by the overall hydrophobicity but also by the specific distributions of polar and non-polar residues along the helix.To directly compare their ability to deform the membrane,the coarse-grained simulations are performed to investigate the membrane deformation under the insertion of multiple helices.
