The adsorption of fibrinogen can be used as a quick indicator of surface haemocompatibility because of its prominent role in coagulation and platelet adhesion. In this work the molecular interaction between fibrinogen...The adsorption of fibrinogen can be used as a quick indicator of surface haemocompatibility because of its prominent role in coagulation and platelet adhesion. In this work the molecular interaction between fibrinogen and a modified titanium oxide surface/platelet has been studied by quartz crystal microbalanee with dissipation （QCM-D） in situ. In order to further characterize the conformation of adsorbed fibrinogen, αC and γ-chain antibody were used to check the orientation and denaturation of fibrinogen on solid surface. QCM-D investiga- tions revealed the fibrinogen have the trend to adsorb on hydropllilic surface in a side-on orientation by positively charged αC domains, which would reduce the exposure of platelet bonding site on γ chain and enable less platelet adhesion and be activated. These obser- vations suggest that certain conformations of adsorbed fibrinogen are less platelet adhesive than others, which opens a possibility for creating a non-platelet adhesive substrates.展开更多
Chitosan/poly(ε-caprolactone) (PCL) blend films in different mass ratios were prepared using the chitosan/PCL mixture solutions in 80 vol.-% acetic acid by spin coating. Their surface micromorphologies were assessed ...Chitosan/poly(ε-caprolactone) (PCL) blend films in different mass ratios were prepared using the chitosan/PCL mixture solutions in 80 vol.-% acetic acid by spin coating. Their surface micromorphologies were assessed by atomic force microscopy (AFM). It was found that the micromorphology of chitosan/PCL blend films was in large extent related to the mass ratio of chitosan. 25 wt% chitosan/PCL blend film presented microphase separation. The protein adsorption of bovine serum albumin (BSA) onto chitosan/PCL blend films was investigated by using quartz crystal microbalance with dissipation monitoring (QCM-D) in real time. The results suggested that the amount of adsorbed BSA on the chitosan/PCL blend films decreased with the addition of chitosan, but the structure and viscoelastic properties of the adsorbed BSA layers were greatly affected by the surface micromorphology of chitosan/PCL blend films. BSA absorbed on the 25 wt% chitosan/PCL blend film with microphase separa- tion showed larger adsorption reversibility, and preferred to form a loose, dissipative layer in comparison with those on other chitosan/PCL blend films without microphase separation.展开更多
Ions in brine significantly affect EOR.However,the mechanism of EOR with different brine is still controversial.By Combining Molecular Dynamics(MD)method and Quartz Crystal Microbalance with Dissipation(QCM-D)technolo...Ions in brine significantly affect EOR.However,the mechanism of EOR with different brine is still controversial.By Combining Molecular Dynamics(MD)method and Quartz Crystal Microbalance with Dissipation(QCM-D)technology to analyze ions distribution and the mechanisms in detaching acidic components on the sandstone,an effective method to determine the detaching capacity was established.The results show that detaching capacity is related to ions distribution and hydration capacity.In the oil/brine/rock system,ions far from the rock are favorable for detaching,while ions near the rock are unfavorable for detaching due to ion bridging effect.The hydrogen bond between water and naphthenic acid is key to detaching.Cations strengthen the detaching by forming hydrated ions with water,and the detaching capacity is negatively correlated with hydrated ions radius and positively correlated with the water coordination number.The detaching determination coefficient was established by considering the ions distribution,ions types,and hydration strength,then verified by QCM-D.The brine detaching capacity with different Ca^(2+)/Mg^(2+)ratios was predicted based on MD and detaching determination coefficient,and verified by QCM-D.The optimal Ca^(2+)/Mg^(2+)ratio gave 7:3.This study provides theoretical guidance for targeted regulation of brine composition to improve the recovery of tight sandstone reservoir.展开更多
On the basis of thin film lubrication theory, the influence of fluid film(disordered film), ordered film and adsorbed film on tribological behavior of lubricating oil in thin-film lubrication(TFL) regime was studied. ...On the basis of thin film lubrication theory, the influence of fluid film(disordered film), ordered film and adsorbed film on tribological behavior of lubricating oil in thin-film lubrication(TFL) regime was studied. The μ-L(friction coefficient versus load) curves of different oil viscosity and additive dosage were obtained by a high frequency reciprocating test rig and the adsorption capacity of additive on steel surface were measured by QCM-D. Based on the Stribeck curve and thin film lubrication theory model, some conclusions can be drawn up, namely:(1) The μ-L curves and the parameters of L0 and μ0, obtained from the high frequency reciprocating test rig with ball-disc contact, can be used to study tribological behaviors of lubricating oil under TFL conditions.(2) In comparison with the high viscosity base fluid, the lower one can enter into TFL regime under lower load and keeps a lower friction coefficient in TFL regime.(3) The polar molecules in additive formulation produce ordered adsorbed layer on steel surface to reduce friction coefficient. And in TFL regime, the molecule's polarity, layer thickness and saturation degree on steel surface probably can influence lubricant's tribological behaviors between the moving interfaces. Moreover, the further study would be focused on the competitive adsorption of different additives, the formation of dual- and/or tri-molecular adsorption layers, and other aspects.展开更多
The effects of surface adsorption of bovine serum albumin(BSA) and human gamma-globulin(HGG) on the tribological performance of a DLC film were investigated using a quartz crystal microbalance with dissipation(QCM-D),...The effects of surface adsorption of bovine serum albumin(BSA) and human gamma-globulin(HGG) on the tribological performance of a DLC film were investigated using a quartz crystal microbalance with dissipation(QCM-D), a ball-on-disk reciprocating tribometer, and a three-electrode electrochemical cell. The results showed that the wear depth in the BSA solution was higher than that in the HGG solution. In the HGG solution, the HGG-adsorbed layer could act as a lubricating layer and protect the DLC film from wear. The wear volume of DLC film in BSA and HGG mixture solution was higher than that in single HGG solution. This may be because the BSA molecules inhibit the formation of HGG adsorbed layer during sliding.展开更多
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.9732011CB606200 and No.81330031） and Fundamentat Research Funds for the Central Universities （No.SWJTU11CX054）. The authors gratefully acknowledge assistance of Mr. Hai-bei Liu at Qsense company for consulting.
文摘The adsorption of fibrinogen can be used as a quick indicator of surface haemocompatibility because of its prominent role in coagulation and platelet adhesion. In this work the molecular interaction between fibrinogen and a modified titanium oxide surface/platelet has been studied by quartz crystal microbalanee with dissipation （QCM-D） in situ. In order to further characterize the conformation of adsorbed fibrinogen, αC and γ-chain antibody were used to check the orientation and denaturation of fibrinogen on solid surface. QCM-D investiga- tions revealed the fibrinogen have the trend to adsorb on hydropllilic surface in a side-on orientation by positively charged αC domains, which would reduce the exposure of platelet bonding site on γ chain and enable less platelet adhesion and be activated. These obser- vations suggest that certain conformations of adsorbed fibrinogen are less platelet adhesive than others, which opens a possibility for creating a non-platelet adhesive substrates.
基金Supported by the National Natural Science Foundation of China(Grant No.20504018)the National High Technology Research and Development Program of China(863 Program)(Grant No.2007AA09Z440)
文摘Chitosan/poly(ε-caprolactone) (PCL) blend films in different mass ratios were prepared using the chitosan/PCL mixture solutions in 80 vol.-% acetic acid by spin coating. Their surface micromorphologies were assessed by atomic force microscopy (AFM). It was found that the micromorphology of chitosan/PCL blend films was in large extent related to the mass ratio of chitosan. 25 wt% chitosan/PCL blend film presented microphase separation. The protein adsorption of bovine serum albumin (BSA) onto chitosan/PCL blend films was investigated by using quartz crystal microbalance with dissipation monitoring (QCM-D) in real time. The results suggested that the amount of adsorbed BSA on the chitosan/PCL blend films decreased with the addition of chitosan, but the structure and viscoelastic properties of the adsorbed BSA layers were greatly affected by the surface micromorphology of chitosan/PCL blend films. BSA absorbed on the 25 wt% chitosan/PCL blend film with microphase separa- tion showed larger adsorption reversibility, and preferred to form a loose, dissipative layer in comparison with those on other chitosan/PCL blend films without microphase separation.
基金financial supports by the National Natural Science Foundation of China(No.52074316)Science Foundation of China University of Petroleum,Beijing(No.2462018QNXZ01)+1 种基金Open Fund(No.SXCU-201905)of Shaanxi Cooperative Innovation Center of Unconventional Oil and Gas Exploration and Development(Xi’an Shiyou University)Major Science and Technology Project of China National Petroleum Corporation(No.2019E-2608)
文摘Ions in brine significantly affect EOR.However,the mechanism of EOR with different brine is still controversial.By Combining Molecular Dynamics(MD)method and Quartz Crystal Microbalance with Dissipation(QCM-D)technology to analyze ions distribution and the mechanisms in detaching acidic components on the sandstone,an effective method to determine the detaching capacity was established.The results show that detaching capacity is related to ions distribution and hydration capacity.In the oil/brine/rock system,ions far from the rock are favorable for detaching,while ions near the rock are unfavorable for detaching due to ion bridging effect.The hydrogen bond between water and naphthenic acid is key to detaching.Cations strengthen the detaching by forming hydrated ions with water,and the detaching capacity is negatively correlated with hydrated ions radius and positively correlated with the water coordination number.The detaching determination coefficient was established by considering the ions distribution,ions types,and hydration strength,then verified by QCM-D.The brine detaching capacity with different Ca^(2+)/Mg^(2+)ratios was predicted based on MD and detaching determination coefficient,and verified by QCM-D.The optimal Ca^(2+)/Mg^(2+)ratio gave 7:3.This study provides theoretical guidance for targeted regulation of brine composition to improve the recovery of tight sandstone reservoir.
基金the PetroChina for its financial support (Grant number: 2011B-2503-2)
文摘On the basis of thin film lubrication theory, the influence of fluid film(disordered film), ordered film and adsorbed film on tribological behavior of lubricating oil in thin-film lubrication(TFL) regime was studied. The μ-L(friction coefficient versus load) curves of different oil viscosity and additive dosage were obtained by a high frequency reciprocating test rig and the adsorption capacity of additive on steel surface were measured by QCM-D. Based on the Stribeck curve and thin film lubrication theory model, some conclusions can be drawn up, namely:(1) The μ-L curves and the parameters of L0 and μ0, obtained from the high frequency reciprocating test rig with ball-disc contact, can be used to study tribological behaviors of lubricating oil under TFL conditions.(2) In comparison with the high viscosity base fluid, the lower one can enter into TFL regime under lower load and keeps a lower friction coefficient in TFL regime.(3) The polar molecules in additive formulation produce ordered adsorbed layer on steel surface to reduce friction coefficient. And in TFL regime, the molecule's polarity, layer thickness and saturation degree on steel surface probably can influence lubricant's tribological behaviors between the moving interfaces. Moreover, the further study would be focused on the competitive adsorption of different additives, the formation of dual- and/or tri-molecular adsorption layers, and other aspects.
基金Funded by the National Natural Science Foundation of China(No.31570958)Science and Technology Support Program of Sichuan Province(No.2016SZ0007)
文摘The effects of surface adsorption of bovine serum albumin(BSA) and human gamma-globulin(HGG) on the tribological performance of a DLC film were investigated using a quartz crystal microbalance with dissipation(QCM-D), a ball-on-disk reciprocating tribometer, and a three-electrode electrochemical cell. The results showed that the wear depth in the BSA solution was higher than that in the HGG solution. In the HGG solution, the HGG-adsorbed layer could act as a lubricating layer and protect the DLC film from wear. The wear volume of DLC film in BSA and HGG mixture solution was higher than that in single HGG solution. This may be because the BSA molecules inhibit the formation of HGG adsorbed layer during sliding.
