In order to understand lubrication mechanism at the nanoscale, researchers have used many physical experimental approaches, such as surface force apparatus, atomic force microscopy and ball-on-disk tribometer. The res...In order to understand lubrication mechanism at the nanoscale, researchers have used many physical experimental approaches, such as surface force apparatus, atomic force microscopy and ball-on-disk tribometer. The results show that the variation rules of the friction force, film thicknessand viscosity of the lubricant at the nanoscale are different from elastohydrodynamic lubrication （EHL）. It is speculated that these differences are attributed to the special arrangement of the molecules at the nanoscale. However, it is difficult to obtain the molecular orientation and distribution directly from the lubricant molecules in these experiments. In recent years, more and more attention has been paid to use new techniques to overcome the shortcomings of traditional experiments, including various spectral methods. The most representative achievements in the experimental research of molecular arrangement are reviewed in this paper： The change of film structure of a liquid crystal under confinement has been obtained using X-ray method. The molecular orientation change of lubricant films has been observed using absorption spectroscopy. Infrared spectroscopy has been used to measure the anisotropy of molecular orientation in the contact region when the lubricant film thickness is reduced to a few tens of nanometers. In situ Raman spectroscopy has been performed to measure the molecular orientation of the lubricant film semi-quantitatively. These results prove that confinement and shear in the contact region can change the arrangement of lubricant molecules. As a result, the lubrication characteristics are affected. The shortages of these works are also discussed based on practicable results. Further work is needed to separate the information of the solid-liquid interface from the bulk liquid film.展开更多
This study aimed to explore the link between block copolymers’interfacial properties and nanoscale carrier formation and found out the influence of length ratio on these characters to optimize drug delivery system.A ...This study aimed to explore the link between block copolymers’interfacial properties and nanoscale carrier formation and found out the influence of length ratio on these characters to optimize drug delivery system.A library of diblock copolymers of PEG-PCL and triblock copolymers with additional PEI(PEG-PCL-PEI)were synthesized.Subsequently,a systematic isothermal investigation was performed to explore molecular arrangements of copolymers at air/water interface.Then,structural properties and drug encapsulation in self-assembly were investigated with DLS,SLS and TEM.We found the additional hydrogen bond in the PEG-PCL-PEI contributes to film stability upon the hydrophobic interaction compared with PEG-PCL.PEG-PCL-PEI assemble into smaller micelle-like(such as PEGPCL4006-PEI)or particle-like structure(such as PEG-PCL8636-PEI)determined by their hydrophilic and hydrophobic block ratio.The distinct structural architectures of copolymer are consistent between interface and self-assembly.Despite the disparity of constituent ratio,we discovered the arrangement of both chains guarantees balanced hydrophilic-hydrophobic ratio in self-assembly to form stable construction.Meanwhile,the structural differences were found to have significant influence on model drugs incorporation including docetaxel and siRNA.Taken together,these findings indicate the correlation between molecular arrangement and self-assembly and inspire us to tune block compositions to achieve desired nanostructure and drug loading.展开更多
Polyimide(PI)films are widely used in printed circuit boards,electronic packaging,interlayer media,display panels,and other fields.Improving the thermal conductivity of PI film is of great significance to promote effe...Polyimide(PI)films are widely used in printed circuit boards,electronic packaging,interlayer media,display panels,and other fields.Improving the thermal conductivity of PI film is of great significance to promote effective heat removal in microelectronic devices.Herein,melamine cyanurate(MC)with multiple hydrogen bonds was designed and introduced into water-soluble polyamide acid(Ws-PAA)solution via an in-situ co-precipitation method.The MC supramolecule forms a chemical bond at the end of the PI chain,while also confines the adjacent chains through hydrogen bonds andπ-πconjugation,functioning as a tailor to improve the chain arrangement via this molecular welding strategy.The tailored PI/MC films exhibit anisotropic thermal conductivity(TC):the in-plane TC can reach 0.93 W/(mK)while the through-plane TC is 0.60 W/(mK).Micromorphology and structural characterizations confirm the formation of complete heat conduction pathways.The developed films also show potential application prospects functioning as heat dissipation media in microelectronic devices.展开更多
Organic photovoltaic cells(OPVs) have attracted more and more attention due to its highly potential application to solve the energy crisis considering its advantages,such as low cost and ease of large area production....Organic photovoltaic cells(OPVs) have attracted more and more attention due to its highly potential application to solve the energy crisis considering its advantages,such as low cost and ease of large area production.The power conversion efficiency(PCE) of OPVs has undergone a more than nine-fold increase from ～1.0% by Tang in 1986 to 9.2% in 2010 announced by Mitsubishi Chemical.The major challenges of obtaining high efficiency OPVs are the synthesis of new narrow band gap materials,controlling molecular arrangement,designing novel configuration cells for better photon harvesting in the active layer.In the article,we summarized the recent progress of novel narrow band gap photovoltaic materials and the effective methods to control the morphology of donor and acceptor in the blend films for high performance of OPVs.展开更多
The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical industry.Herein,we propose and validate a liquid crystal(LC)-based apt...The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical industry.Herein,we propose and validate a liquid crystal(LC)-based aptasensor for the ultrasensitive detection of Escherichia coli(E.coli),a model of Gram-negative bacteria.The nematic liquid crystal of 4-cyano-4’-pentylbiphenyl(5 CB) molecules can be orderly or disorderly arranged at the LC-aqueous interface via different stimuli,causing changes in optical texture due to birefringence.Bright schlieren texture is observed when a mixture solution of aptamer and hexadecyl trimethyl ammonium bromide(CTAB) is dripped onto the segmented LC films on a copper mesh.The specific binding of aptamers with target bacteria biomarkers liberates the CTAB molecules,which then self-assemble at the LC-aqueous interface to induce the vertical alignment of LCs.An optical transition from bright to dark is therefore achieved via the LC molecular orientation and serves as an aptasensor.Given the prominent affinity and specificity of the aptamer,the established sensitive and selective E.coli assay shows an ultralow detection limit of 27 cfu/mL.The prepared aptasensor can also be applied for the sensitive and selective determination of E.coli in fruit juice,soft drink,and cosmetic products,and shows great promise for the on-site detection of Gram-negative bacteria with high sensitivity and specificity for environmental monitoring,food safety assessment,and household chemical inspection.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51335005,51321092)
文摘In order to understand lubrication mechanism at the nanoscale, researchers have used many physical experimental approaches, such as surface force apparatus, atomic force microscopy and ball-on-disk tribometer. The results show that the variation rules of the friction force, film thicknessand viscosity of the lubricant at the nanoscale are different from elastohydrodynamic lubrication （EHL）. It is speculated that these differences are attributed to the special arrangement of the molecules at the nanoscale. However, it is difficult to obtain the molecular orientation and distribution directly from the lubricant molecules in these experiments. In recent years, more and more attention has been paid to use new techniques to overcome the shortcomings of traditional experiments, including various spectral methods. The most representative achievements in the experimental research of molecular arrangement are reviewed in this paper： The change of film structure of a liquid crystal under confinement has been obtained using X-ray method. The molecular orientation change of lubricant films has been observed using absorption spectroscopy. Infrared spectroscopy has been used to measure the anisotropy of molecular orientation in the contact region when the lubricant film thickness is reduced to a few tens of nanometers. In situ Raman spectroscopy has been performed to measure the molecular orientation of the lubricant film semi-quantitatively. These results prove that confinement and shear in the contact region can change the arrangement of lubricant molecules. As a result, the lubrication characteristics are affected. The shortages of these works are also discussed based on practicable results. Further work is needed to separate the information of the solid-liquid interface from the bulk liquid film.
基金the NSFC(Nos.81673365,81973258 and 81473156,China)the Fangzheng Foundation(China)for funding of the work
文摘This study aimed to explore the link between block copolymers’interfacial properties and nanoscale carrier formation and found out the influence of length ratio on these characters to optimize drug delivery system.A library of diblock copolymers of PEG-PCL and triblock copolymers with additional PEI(PEG-PCL-PEI)were synthesized.Subsequently,a systematic isothermal investigation was performed to explore molecular arrangements of copolymers at air/water interface.Then,structural properties and drug encapsulation in self-assembly were investigated with DLS,SLS and TEM.We found the additional hydrogen bond in the PEG-PCL-PEI contributes to film stability upon the hydrophobic interaction compared with PEG-PCL.PEG-PCL-PEI assemble into smaller micelle-like(such as PEGPCL4006-PEI)or particle-like structure(such as PEG-PCL8636-PEI)determined by their hydrophilic and hydrophobic block ratio.The distinct structural architectures of copolymer are consistent between interface and self-assembly.Despite the disparity of constituent ratio,we discovered the arrangement of both chains guarantees balanced hydrophilic-hydrophobic ratio in self-assembly to form stable construction.Meanwhile,the structural differences were found to have significant influence on model drugs incorporation including docetaxel and siRNA.Taken together,these findings indicate the correlation between molecular arrangement and self-assembly and inspire us to tune block compositions to achieve desired nanostructure and drug loading.
基金funding from the Shanghai Sailing Program (21YF1414200)
文摘Polyimide(PI)films are widely used in printed circuit boards,electronic packaging,interlayer media,display panels,and other fields.Improving the thermal conductivity of PI film is of great significance to promote effective heat removal in microelectronic devices.Herein,melamine cyanurate(MC)with multiple hydrogen bonds was designed and introduced into water-soluble polyamide acid(Ws-PAA)solution via an in-situ co-precipitation method.The MC supramolecule forms a chemical bond at the end of the PI chain,while also confines the adjacent chains through hydrogen bonds andπ-πconjugation,functioning as a tailor to improve the chain arrangement via this molecular welding strategy.The tailored PI/MC films exhibit anisotropic thermal conductivity(TC):the in-plane TC can reach 0.93 W/(mK)while the through-plane TC is 0.60 W/(mK).Micromorphology and structural characterizations confirm the formation of complete heat conduction pathways.The developed films also show potential application prospects functioning as heat dissipation media in microelectronic devices.
基金supported by the National Natural Science Foundation of China (10804006,20904057 and 21074055)the Natural Science Foundation of Beijing (2122050)+1 种基金the Basic Research Foundation of the Central Universities (2011JBM123)F. Zhang thanks the support from the "Double Hundred Talents Plan" of Beijing Jiaotong University and the State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences
文摘Organic photovoltaic cells(OPVs) have attracted more and more attention due to its highly potential application to solve the energy crisis considering its advantages,such as low cost and ease of large area production.The power conversion efficiency(PCE) of OPVs has undergone a more than nine-fold increase from ～1.0% by Tang in 1986 to 9.2% in 2010 announced by Mitsubishi Chemical.The major challenges of obtaining high efficiency OPVs are the synthesis of new narrow band gap materials,controlling molecular arrangement,designing novel configuration cells for better photon harvesting in the active layer.In the article,we summarized the recent progress of novel narrow band gap photovoltaic materials and the effective methods to control the morphology of donor and acceptor in the blend films for high performance of OPVs.
基金supported by Guangdong Province Basic and Applied Basic Research Foundation (2021A1515110236)the National Natural Science Foundation of China (62004070)+4 种基金the Science and Technology Program of Guangzhou (2019050001,202201010248)the Youth Innovation Project of Guangdong Education Department(2020KQNCX018)the Young Scholar Foundation of South China Normal University (21KJ08)the “Climbing Program” Special Funds of Guangdong Province (pdjh2022b0133)partially supported by the Science and Technology Planning Project of Guangdong Province (2020B1212060067)
文摘The sensitive and differential detection of Gram-negative bacteria is essential in food processing,environmental monitoring,and the daily chemical industry.Herein,we propose and validate a liquid crystal(LC)-based aptasensor for the ultrasensitive detection of Escherichia coli(E.coli),a model of Gram-negative bacteria.The nematic liquid crystal of 4-cyano-4’-pentylbiphenyl(5 CB) molecules can be orderly or disorderly arranged at the LC-aqueous interface via different stimuli,causing changes in optical texture due to birefringence.Bright schlieren texture is observed when a mixture solution of aptamer and hexadecyl trimethyl ammonium bromide(CTAB) is dripped onto the segmented LC films on a copper mesh.The specific binding of aptamers with target bacteria biomarkers liberates the CTAB molecules,which then self-assemble at the LC-aqueous interface to induce the vertical alignment of LCs.An optical transition from bright to dark is therefore achieved via the LC molecular orientation and serves as an aptasensor.Given the prominent affinity and specificity of the aptamer,the established sensitive and selective E.coli assay shows an ultralow detection limit of 27 cfu/mL.The prepared aptasensor can also be applied for the sensitive and selective determination of E.coli in fruit juice,soft drink,and cosmetic products,and shows great promise for the on-site detection of Gram-negative bacteria with high sensitivity and specificity for environmental monitoring,food safety assessment,and household chemical inspection.
