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
The aim of this study was to investigate the inhibitory effect of heparin/fibronectin （Hep/Fn） complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium...The aim of this study was to investigate the inhibitory effect of heparin/fibronectin （Hep/Fn） complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium （Ti） surfaces, with subsequent X-ray photoelectron spectroscopy （XPS）, Toluidine Blue 0 （TBO） and immunohistochemistry methods were used to characterize surface properties. Smooth muscle cell （SMC） cultures were used to evaluate the effect of Hep/Fn complexes on SMC proliferation. Results showed that Hep/Fn complexes successfully immobilized onto Ti surfaces and resulted in an inhibition of SMC proliferation. This study suggests that Hep/Fn surface-immobilized biomaterials develop as a new generation of biomaterials to prevent neointimal hyperplasia, particularly for use in cardiovascular implants.展开更多
Ti-Cu films with different Cu concentrations were fabricated by high-power pulsed magnetron sputtering（HPPMS） to release copper ions and catalyze NO to improve the blood compatibility. The Cu concentrations of films...Ti-Cu films with different Cu concentrations were fabricated by high-power pulsed magnetron sputtering（HPPMS） to release copper ions and catalyze NO to improve the blood compatibility. The Cu concentrations of films were 25.7 at% and 68.8 at%. Pure Ti films were also fabricated. Copper release, catalytic release of nitric oxide（NO）, and blood platelet adhesion of Ti-Cu films were studied. Ti-Cu films released copper ions in PBS solution and more Cu ions were released from films with 68.8 at% Cu. Ti-Cu films had excellent ability of catalytical decomposition of exogenous donor S-nitroso-N-acetyl-DL-penicillamine（SNAP） and as a result, nitric oxide（NO） was generated. The NO generation catalyzed by Ti-Cu films was significantly higher than that by pure Ti films. This was more eminent in the Ti-Cu films with 68.8 at% Cu. The platelet adhesion and activation of Ti-Cu films were significantly inhibited compared to that of pure Ti films in the presence of SNAP. The Ti-Cu film fabricated by HPPMS showed the ability of releasing Cu ions to catalyze SNAP to generate NO to inhibit platelet adhesion and activation.展开更多
For high-power impulse magnetron sputtering(HIPIMS),the peak power applied to the target is of great importance for regulating the ionization degree of the metal target and ion/atom flux ratio.In this work,chromium(Cr...For high-power impulse magnetron sputtering(HIPIMS),the peak power applied to the target is of great importance for regulating the ionization degree of the metal target and ion/atom flux ratio.In this work,chromium(Cr)films were deposited on 316-L stainless steel substrates and silicon(100) wafers with different peak powers by HIPIMS.The relationship between peak target power and properties of Cr films was explored in detail.The resulting structure and mechanical properties of deposited Cr films were characterized by X-ray diffraction(XRD),transmission electron microscope(TEM),atomic force microscopy(AFM),indentation hardness and scratch tester.The results indicate that the ionization degree of metal target and ion/atom flux ratio increase with the increase in peak power but without the loss of deposition rate at the same time.At low ionization degree,the deposited Cr film has low compressive residual stress and low hardness but good adhesion strength.When the ionization degree of target metal increases with increasing peak power,Cr film exhibits finer size and smoother surface with improved hardness but decreased adhesion strength.展开更多
The adsorption behavior of heparin and fibronectin was studied by quartz crystal microbalance with dissipation(QCM-D), and the interaction between heparin and fibronectin was evaluated using immunochemistry and isothe...The adsorption behavior of heparin and fibronectin was studied by quartz crystal microbalance with dissipation(QCM-D), and the interaction between heparin and fibronectin was evaluated using immunochemistry and isothermal titration calorimetry(ITC) measurement. The results showed that there was competitive adsorption between heparin and fibronectin, and the preadsorption of fibronectin could prevent subsequent heparin adsorption to some extent, and the adsorbed Hep/Fn complex on the surface was in a rigid form. The bioactivity of heparin and fibronectin could be affected by the bulk concentration of each, and both heparin and fibronectin in Hep/Fn complex formed under p H 4 condition displayed larger bioactivity than that formed under p H 7 condition. Moreover, the fibronectin showed more exposed cell-binding sites at the p H value lower than physiological condition. The results of ITC further suggested that the interaction between heparin and fibronectin under p H 4 was stronger than under p H 7, and the complex was also more stable. The study brings forth the detailed interaction between heparin and fibronectin, which will be helpful for better understanding the interaction mechanism of the two biomolecules. The results may be potentially useful for the development of new generation of cardiovascular biomaterials.展开更多
In this study,three types of bionic texture surfaces were designed,based on the microstructure of tree frog and gecko feet,for two typical prosthetic substrates:silicone rubber and thermoplastic polyurethane elastomer...In this study,three types of bionic texture surfaces were designed,based on the microstructure of tree frog and gecko feet,for two typical prosthetic substrates:silicone rubber and thermoplastic polyurethane elastomer(TPU).The surface energy of all bionic texture surfaces,and the relative displacement and energy dissipation of the reciprocating friction between these bionic surfaces and skin,were investigated.The results revealed that the bionic texture of the prosthetic socket surface had an obvious influence on the surface characteristics and reciprocating characteristics of friction with the skin.According to the comprehensive weight rating method,the optimal bionic textures for the silicone rubber substrate were a regular hexagonal prism and a quadrangular prism;for the TPU substrate,only the regular quadrangular prism texture was optimal.These textures can effectively increase the surface energy of the surface of the prosthetic socket,thereby increasing its adhesion to skin and reducing the dissipation of friction energy when it interacts with the stump.This bionic prosthetic socket surface design helps improve the adaptation between the prosthetic socket and the stump.展开更多
The micromechanical properties of soft tissue can be used as markers for the physiological state and function of the tissue.Deep understanding of the micromechanics of soft tissue,such as the oesophagus,is of great si...The micromechanical properties of soft tissue can be used as markers for the physiological state and function of the tissue.Deep understanding of the micromechanics of soft tissue,such as the oesophagus,is of great significance to the design of artificial oesophagi,endoscope materials and coatings for medical devices.Here,the micromechanical properties of oesophageal mucosa were studied under different loading rates,deflections,and dwell time by using atomic force microscopy.The micromechanical properties of soft tissue included elastic modulus,plasticity and adhesion force.Results showed that the micromechanical properties changed with increasing loading rate,deflection and dwell time.The micromechanical properties of oesophageal mucosa were related to time-dependent behaviours,such as contact stress,energy transformation,and strain gradient plasticity.Furthermore,the heterogeneity of oesophageal mucosa affected the micromechanical properties.The force mapping mode was a reliable and effective means to study the micromechanical properties of soft tissue.The results can provide a basis and technical support for the diagnosis of oesophageal diseases from a microscale as well as a material design perspective.展开更多
Low shape matching and high stress shielding rates between bone plate and human bone are not conducive to the primary healing of fracture.In this study,taking the fracture site of the lower one‐third of human tibia a...Low shape matching and high stress shielding rates between bone plate and human bone are not conducive to the primary healing of fracture.In this study,taking the fracture site of the lower one‐third of human tibia as an application case,six types of personalised Ti6Al4V tibial plates with grooved surface were designed and evaluated by reverse en-gineering and finite element analysis.The results showed that the grooved design can reduce the stress shielding rate of bone plate and promote the facture healing.Among the six types of bone plates,the‘OUT-MI’bone plate has the lowest stress shielding rate and the most uniform stress distribution.Meanwhile,with the increasing tibial load during the convalescence,the average stress and maximum axial displacement of the tibial fracture surface increased,which can effectively improve the bone regeneration in the tibial fracture area.Moreover,there was no significant difference in four-point bending performance between the‘OUT-MI’bone plate and the‘STR-BE’bone plate,indicating that the mechanical properties of this bone plate were reliable.The results provide a theoretical basis for the design of fracture fixation plates on clinical treatment.展开更多
The endoscopy is the most direct and effective means for digestive tract diseases.Medical workers can conduct a series of manipulations with the help of endoscope,including checking,removing,stripping the diseased tis...The endoscopy is the most direct and effective means for digestive tract diseases.Medical workers can conduct a series of manipulations with the help of endoscope,including checking,removing,stripping the diseased tissue or placing the stent.In order to understand the frictional behaviour at the endoscope-oesophagus interface,the finite-element model was analysed by Abaqus in this study.Considering the different modelling conditions,the total force due to frictional stress,frictional dissipation and the maximum Mises stress for the whole model were studied.Results showed that with the increasing amplitude,coefficient of friction and decreasing diameter,the total forces due to the frictional stress and the FD increased obviously.It did not present a clear difference with the variable distance for overlapping parts(region L).The positions of maximum Mises stress for the whole model under different conditions mainly focused on the initial part of the region R.The maximum Mises stress between different diameters showed a big difference.The results can provide the basic data for the finite-element modelling of frictional behaviour of human tissue.展开更多
Material viscoelasticity is of particular importance for polymers,biotissues and many others,due to the significant influence not only on the elastic response of structures,but also on their failure mechanism in actua...Material viscoelasticity is of particular importance for polymers,biotissues and many others,due to the significant influence not only on the elastic response of structures,but also on their failure mechanism in actual applications.In this study,the experimental tests by nanoindentations are cate gorized according to the objective parameter combined with the indenter sha pe into four distinct cases,and the Fractional Derivative Zener model(FDZM)is employed to characterize this time-dependent property.The explicit data-fitting formulas are derived to determine the relaxation modulus and creep compliance te sted with the conical and spherical inde nters.Besides,a fitting scheme is provided to facilitate the identification of these viscoelastic parameters.In comparison with the general methods adopting the Prony series or empirical models,two silent merits present:(1)fewer model coefficients necessitate being determined based on the experimental data;(2)the relaxation modulus G(t)and the creep compliance J(t)can be obtained through one indentation test,and their exact interconversion is guaranteed as well.Several sets of experimental data are applied to examine the validity of the developed approach,and three more examples are adopted to demonstrate the exact interconversion between G(t)and J(t).A few concluding remarks are drawn eventually.展开更多
Slippage is a common phenomenon between laparoscopic graspers and tissues during minimally invasive surgery,which may lead to inefficient surgical operations,prolonged operation time,and increased patient suffering.Th...Slippage is a common phenomenon between laparoscopic graspers and tissues during minimally invasive surgery,which may lead to inefficient surgical operations,prolonged operation time,and increased patient suffering.The stability factors related to the friction behaviour between laparoscopic graspers and the large intestine,including bio-surface liquids,pulling angle,and surface profile of graspers,were studied.The friction behav-iour at the large intestine-grasper interface was tested using a UMT-II tribometer under the conditions of clamping force of 1-4 N,sliding displacement of 15 mm,and sliding velocity of 2 mm/s to simulate the grasping and pulling operations of soft tissue.The results showed that the bio-surface liquid(serum)of the large intestine significantly decreased the friction coefficient,thus reducing the grasping efficiency.A pulling angle of 15°could generate the peak frictional force and enhance the grasping stability.The frictional force increased with the ratio of the profile surface area of the grasper.These results demonstrate that the grasping stability can be improved by changing either the bio-surface liquid condition or the pulling angle.In addition,a grasper with a larger profile surface area can also prevent slippage due to its significant influence on the pressure distribution and actual contact area for tissue retention.展开更多
CO2 and O2 were employed as reactive gases to fabricate carbon-doped titanium oxide films using DC reactive magnetron sputtering. Microstructure, composition and optical band gap of the films were investigated by X-ra...CO2 and O2 were employed as reactive gases to fabricate carbon-doped titanium oxide films using DC reactive magnetron sputtering. Microstructure, composition and optical band gap of the films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and UV-visible spectrophotometer, respectively. The results showed that carbon-doped titanium monoxide films （C-TiO） with a carbon concentration of 5.8 at.% were obtained in an AffCO2 mixed atmosphere. However, carbon-doped futile and anatase （C-TiO2） with a carbon concentration of about 1.4 at.% were obtained in an Ar/CO2/O2 mixed atmosphere. The optical band gaps of C-TiO and C-TiO2 were about 2.6 and 2.9 eV, respectively. Both of them were narrower than that of pure TiO2 films. Films with narrowed optical band gap energy are promising in promoting their photo-catalytic activity.展开更多
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.
基金supported by the financial support of Natural Science Research Program of Jiangsu Education Department(No.13KJB310014)Natural Science Foundation of Jiangsu Province(BK20140429)the Natural Science Foundation of Nantong University(No.14ZY015,No.13R23)
文摘The aim of this study was to investigate the inhibitory effect of heparin/fibronectin （Hep/Fn） complexes on neointimal hyperplasia following endovascular intervention. Hep/Fn complexes were immobilized onto titanium （Ti） surfaces, with subsequent X-ray photoelectron spectroscopy （XPS）, Toluidine Blue 0 （TBO） and immunohistochemistry methods were used to characterize surface properties. Smooth muscle cell （SMC） cultures were used to evaluate the effect of Hep/Fn complexes on SMC proliferation. Results showed that Hep/Fn complexes successfully immobilized onto Ti surfaces and resulted in an inhibition of SMC proliferation. This study suggests that Hep/Fn surface-immobilized biomaterials develop as a new generation of biomaterials to prevent neointimal hyperplasia, particularly for use in cardiovascular implants.
基金Funded by the National Natural Science Foundation of China(No.31300787)the National Natural Science Foundation of China China Academy of Engineering Physics(NSAF No.U1330113)+1 种基金the Overseas Famous Teacher Program of Chinese Education Ministry(MS2010XNJT070)the Qingmiao Plan of SWJTU 2015(No.A0920502051517-6)
文摘Ti-Cu films with different Cu concentrations were fabricated by high-power pulsed magnetron sputtering（HPPMS） to release copper ions and catalyze NO to improve the blood compatibility. The Cu concentrations of films were 25.7 at% and 68.8 at%. Pure Ti films were also fabricated. Copper release, catalytic release of nitric oxide（NO）, and blood platelet adhesion of Ti-Cu films were studied. Ti-Cu films released copper ions in PBS solution and more Cu ions were released from films with 68.8 at% Cu. Ti-Cu films had excellent ability of catalytical decomposition of exogenous donor S-nitroso-N-acetyl-DL-penicillamine（SNAP） and as a result, nitric oxide（NO） was generated. The NO generation catalyzed by Ti-Cu films was significantly higher than that by pure Ti films. This was more eminent in the Ti-Cu films with 68.8 at% Cu. The platelet adhesion and activation of Ti-Cu films were significantly inhibited compared to that of pure Ti films in the presence of SNAP. The Ti-Cu film fabricated by HPPMS showed the ability of releasing Cu ions to catalyze SNAP to generate NO to inhibit platelet adhesion and activation.
基金financially supported by Joint Fund of National Natural Science Foundation of China and China Academy of Engineering Physics (No.U1330113)the National Natural Science Foundation of China (No.31300787)the Overseas Famous Teacher Program of Chinese Education Ministry (No. MS2010XNJT070)。
文摘For high-power impulse magnetron sputtering(HIPIMS),the peak power applied to the target is of great importance for regulating the ionization degree of the metal target and ion/atom flux ratio.In this work,chromium(Cr)films were deposited on 316-L stainless steel substrates and silicon(100) wafers with different peak powers by HIPIMS.The relationship between peak target power and properties of Cr films was explored in detail.The resulting structure and mechanical properties of deposited Cr films were characterized by X-ray diffraction(XRD),transmission electron microscope(TEM),atomic force microscopy(AFM),indentation hardness and scratch tester.The results indicate that the ionization degree of metal target and ion/atom flux ratio increase with the increase in peak power but without the loss of deposition rate at the same time.At low ionization degree,the deposited Cr film has low compressive residual stress and low hardness but good adhesion strength.When the ionization degree of target metal increases with increasing peak power,Cr film exhibits finer size and smoother surface with improved hardness but decreased adhesion strength.
基金Funded by the Natural Science Research Program of Jiangsu Education Department(No.13KJB310014)Natural Science Research Program of Jiangsu Province(No.BK20140429)
文摘The adsorption behavior of heparin and fibronectin was studied by quartz crystal microbalance with dissipation(QCM-D), and the interaction between heparin and fibronectin was evaluated using immunochemistry and isothermal titration calorimetry(ITC) measurement. The results showed that there was competitive adsorption between heparin and fibronectin, and the preadsorption of fibronectin could prevent subsequent heparin adsorption to some extent, and the adsorbed Hep/Fn complex on the surface was in a rigid form. The bioactivity of heparin and fibronectin could be affected by the bulk concentration of each, and both heparin and fibronectin in Hep/Fn complex formed under p H 4 condition displayed larger bioactivity than that formed under p H 7 condition. Moreover, the fibronectin showed more exposed cell-binding sites at the p H value lower than physiological condition. The results of ITC further suggested that the interaction between heparin and fibronectin under p H 4 was stronger than under p H 7, and the complex was also more stable. The study brings forth the detailed interaction between heparin and fibronectin, which will be helpful for better understanding the interaction mechanism of the two biomolecules. The results may be potentially useful for the development of new generation of cardiovascular biomaterials.
基金This work was supported by National Natural Science Foundation of China(no.51675447)Sichuan science and technology program of China(no.2018JY0552)China Assistive Devices and Technology Centre(no.CJFJRRB10-2018).
文摘In this study,three types of bionic texture surfaces were designed,based on the microstructure of tree frog and gecko feet,for two typical prosthetic substrates:silicone rubber and thermoplastic polyurethane elastomer(TPU).The surface energy of all bionic texture surfaces,and the relative displacement and energy dissipation of the reciprocating friction between these bionic surfaces and skin,were investigated.The results revealed that the bionic texture of the prosthetic socket surface had an obvious influence on the surface characteristics and reciprocating characteristics of friction with the skin.According to the comprehensive weight rating method,the optimal bionic textures for the silicone rubber substrate were a regular hexagonal prism and a quadrangular prism;for the TPU substrate,only the regular quadrangular prism texture was optimal.These textures can effectively increase the surface energy of the surface of the prosthetic socket,thereby increasing its adhesion to skin and reducing the dissipation of friction energy when it interacts with the stump.This bionic prosthetic socket surface design helps improve the adaptation between the prosthetic socket and the stump.
基金supported by the National Natural Science Foundation of China(no.51675447).
文摘The micromechanical properties of soft tissue can be used as markers for the physiological state and function of the tissue.Deep understanding of the micromechanics of soft tissue,such as the oesophagus,is of great significance to the design of artificial oesophagi,endoscope materials and coatings for medical devices.Here,the micromechanical properties of oesophageal mucosa were studied under different loading rates,deflections,and dwell time by using atomic force microscopy.The micromechanical properties of soft tissue included elastic modulus,plasticity and adhesion force.Results showed that the micromechanical properties changed with increasing loading rate,deflection and dwell time.The micromechanical properties of oesophageal mucosa were related to time-dependent behaviours,such as contact stress,energy transformation,and strain gradient plasticity.Furthermore,the heterogeneity of oesophageal mucosa affected the micromechanical properties.The force mapping mode was a reliable and effective means to study the micromechanical properties of soft tissue.The results can provide a basis and technical support for the diagnosis of oesophageal diseases from a microscale as well as a material design perspective.
基金This work was supported by the Key R&D project of Sichuan Province(2018JY0552)National Natural Science Foundation of China(No.51,675,447).
文摘Low shape matching and high stress shielding rates between bone plate and human bone are not conducive to the primary healing of fracture.In this study,taking the fracture site of the lower one‐third of human tibia as an application case,six types of personalised Ti6Al4V tibial plates with grooved surface were designed and evaluated by reverse en-gineering and finite element analysis.The results showed that the grooved design can reduce the stress shielding rate of bone plate and promote the facture healing.Among the six types of bone plates,the‘OUT-MI’bone plate has the lowest stress shielding rate and the most uniform stress distribution.Meanwhile,with the increasing tibial load during the convalescence,the average stress and maximum axial displacement of the tibial fracture surface increased,which can effectively improve the bone regeneration in the tibial fracture area.Moreover,there was no significant difference in four-point bending performance between the‘OUT-MI’bone plate and the‘STR-BE’bone plate,indicating that the mechanical properties of this bone plate were reliable.The results provide a theoretical basis for the design of fracture fixation plates on clinical treatment.
基金supported by the National Natural Science Foundation of China(nos.51675447).
文摘The endoscopy is the most direct and effective means for digestive tract diseases.Medical workers can conduct a series of manipulations with the help of endoscope,including checking,removing,stripping the diseased tissue or placing the stent.In order to understand the frictional behaviour at the endoscope-oesophagus interface,the finite-element model was analysed by Abaqus in this study.Considering the different modelling conditions,the total force due to frictional stress,frictional dissipation and the maximum Mises stress for the whole model were studied.Results showed that with the increasing amplitude,coefficient of friction and decreasing diameter,the total forces due to the frictional stress and the FD increased obviously.It did not present a clear difference with the variable distance for overlapping parts(region L).The positions of maximum Mises stress for the whole model under different conditions mainly focused on the initial part of the region R.The maximum Mises stress between different diameters showed a big difference.The results can provide the basic data for the finite-element modelling of frictional behaviour of human tissue.
基金National Natural Science Foundation of China(grant nos.51290291,51675447,51305362,11772274)the Young Scientific Innovation Team of Science and Technology of Sichuan(grant no.2017TD0017)the Fundamental Research Funds for the Central Universities(grant no.2682016CX024)。
文摘Material viscoelasticity is of particular importance for polymers,biotissues and many others,due to the significant influence not only on the elastic response of structures,but also on their failure mechanism in actual applications.In this study,the experimental tests by nanoindentations are cate gorized according to the objective parameter combined with the indenter sha pe into four distinct cases,and the Fractional Derivative Zener model(FDZM)is employed to characterize this time-dependent property.The explicit data-fitting formulas are derived to determine the relaxation modulus and creep compliance te sted with the conical and spherical inde nters.Besides,a fitting scheme is provided to facilitate the identification of these viscoelastic parameters.In comparison with the general methods adopting the Prony series or empirical models,two silent merits present:(1)fewer model coefficients necessitate being determined based on the experimental data;(2)the relaxation modulus G(t)and the creep compliance J(t)can be obtained through one indentation test,and their exact interconversion is guaranteed as well.Several sets of experimental data are applied to examine the validity of the developed approach,and three more examples are adopted to demonstrate the exact interconversion between G(t)and J(t).A few concluding remarks are drawn eventually.
基金The Key R&D project of Sichuan Province,Grant/Award Number:2018JY0552National Natural Science Foundation of China,Grant/Award Number:51675447。
文摘Slippage is a common phenomenon between laparoscopic graspers and tissues during minimally invasive surgery,which may lead to inefficient surgical operations,prolonged operation time,and increased patient suffering.The stability factors related to the friction behaviour between laparoscopic graspers and the large intestine,including bio-surface liquids,pulling angle,and surface profile of graspers,were studied.The friction behav-iour at the large intestine-grasper interface was tested using a UMT-II tribometer under the conditions of clamping force of 1-4 N,sliding displacement of 15 mm,and sliding velocity of 2 mm/s to simulate the grasping and pulling operations of soft tissue.The results showed that the bio-surface liquid(serum)of the large intestine significantly decreased the friction coefficient,thus reducing the grasping efficiency.A pulling angle of 15°could generate the peak frictional force and enhance the grasping stability.The frictional force increased with the ratio of the profile surface area of the grasper.These results demonstrate that the grasping stability can be improved by changing either the bio-surface liquid condition or the pulling angle.In addition,a grasper with a larger profile surface area can also prevent slippage due to its significant influence on the pressure distribution and actual contact area for tissue retention.
基金supported by the National Natural Science Foundation of China (Nos.81171462 and 51062002)the Sichuan Youth Science & Technology Foundation for Distinguished Young Scholars (No.2012JQ0001)the Fundamental Research Funds for the Central Universities (Nos.SWJTU11CX078 and SWJTU12ZT08)
文摘CO2 and O2 were employed as reactive gases to fabricate carbon-doped titanium oxide films using DC reactive magnetron sputtering. Microstructure, composition and optical band gap of the films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and UV-visible spectrophotometer, respectively. The results showed that carbon-doped titanium monoxide films （C-TiO） with a carbon concentration of 5.8 at.% were obtained in an AffCO2 mixed atmosphere. However, carbon-doped futile and anatase （C-TiO2） with a carbon concentration of about 1.4 at.% were obtained in an Ar/CO2/O2 mixed atmosphere. The optical band gaps of C-TiO and C-TiO2 were about 2.6 and 2.9 eV, respectively. Both of them were narrower than that of pure TiO2 films. Films with narrowed optical band gap energy are promising in promoting their photo-catalytic activity.
