Paint removal from steel structure is executed for shipyards of marine and offshore engineering.Due to environmental unfriendliness and unhealthy drawbacks of sand blasting technique, laser ablation technique is propo...Paint removal from steel structure is executed for shipyards of marine and offshore engineering.Due to environmental unfriendliness and unhealthy drawbacks of sand blasting technique, laser ablation technique is proposed as a substituting method.By absorbing high energy of the 1064 nm pulsed laser, the paint is vaporized quickly.The ablated debris is then collected by using a suction pump.Initial metal surface of the steel is exposed when laser beam irradiates perpendicularly and scans over it.The cleaned surface fulfills the requirements of surface preparation standards ISO 8501 of SA2.The adhesion is further characterized with pull-off test after carrying out painting with Jotamastic 87 aluminum paint.The repainting can be embedded onto the laser cleaned surface to bond much more tightly.The excellent adhesion strength of 20 MPa between repainted coating and the substrate is achieved, which is higher than what is required by shipyards applications.展开更多
One of the critical issues in gram-negative bacterial adhesion is how wettability regulates adhesion as the surface wettability varies from superhydrophilic to superhydrophobic,and what is the relevant/contributing ro...One of the critical issues in gram-negative bacterial adhesion is how wettability regulates adhesion as the surface wettability varies from superhydrophilic to superhydrophobic,and what is the relevant/contributing role of the lipopolysaccharide（LPS） outer layer of the gram-negative shell during this procedure.Herein,by avoiding the unexpected influence induced by the varied topographies,control over gram-negative bacteria adhesion by wettability is achieved on biomimetic hierarchical surfaces,which is mainly mediated by LPS layer.The study provides a methodology to have a good control over bacteria cell adhesion by properly designing wettable surface structures.This design concept is helpful for developing new generations of biomaterials in order to control a variety of diseases induced by gramnegative bacteria,which still continue to be very important and necessary in the fields of biomedicine.展开更多
Organic epoxy matrices have been widely used in the FRP reinforcing technique, but they have serious disadvantages of poor high-temperature resistance. An inorganic adhesive is invented to replace the organic adhesive...Organic epoxy matrices have been widely used in the FRP reinforcing technique, but they have serious disadvantages of poor high-temperature resistance. An inorganic adhesive is invented to replace the organic adhesive. For the inorganic adhesive at normal temperature and different high temperatures, the microstructure and phase composition are investigated by means of X-ray diffraction （XRD） and SEM respectively. Results show that inorganic adhesive can resist at least 600 ℃ high temperature. Fire-resistance performance of inorganic adhesive can meet the requirements of fiber reinforced polymer （FRP） strengthened RC structures.展开更多
This investigation was conducted to determine the feasibility of using a two-component polyurethane （PUR） adhesive, with special waterproof properties, in constructing wooden structures. We designed and conducted te...This investigation was conducted to determine the feasibility of using a two-component polyurethane （PUR） adhesive, with special waterproof properties, in constructing wooden structures. We designed and conducted tests to compare the shear strength and adhesion performance of PUR with polyvinyl acetate （PVAc） adhesive on block-shear specimens constructed of oriental beech （Fagus orientalis L.）, fir （Abies alba Mill.）, poplar （Populus deltoides Bartr.）, white oak （Quercus alba L.）, sycamore （Platanus orientalis L.） and white walnut （Juglans cinerea L.）. The values of the percentage of wood failure were also determined in specimens constructed with each adhesive. The highest shear strength values of both adhesives were obtained in specimens constructed of beech, while the lowest shear strength values were obtained in fir and poplar specimens. Average shear strength of the PUR adhesive was 16.5% higher than that of the PVAc adhesive. Specimens constructed of fir, poplar and sycamore were characterised by the highest percentages of wood failure, whereas the lowest average percentages of wood failure were obtained in beech and oak specimens. With the exception of oak specimens, there was no statistically significant difference between percentage of wood failure among the PUR and PVAc adhesives. Generally, the PUR adhesive showed an acceptable adhesion performance on wood materials used in our study.展开更多
Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and ...Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.展开更多
Nanohairs, which can be found on the epidermis of Tokay gecko＇s toes, contribute to the adhesion by means of van der Waals force, capillary force, etc. This structure has inspired many researchers to fabricate the at...Nanohairs, which can be found on the epidermis of Tokay gecko＇s toes, contribute to the adhesion by means of van der Waals force, capillary force, etc. This structure has inspired many researchers to fabricate the attachable nano-scale structures. However, the efficiency of artificial nano-scale structures is not reliable sufficiently. Moreover, the mechanical parameters related to the nano-hair attachment are not yet revealed qualitatively. The mechanical parameters which have influence on the ability of adhesive nano-hairs were investigated through numerical simulation in which only van der Waals force was considered. For the numerical analysis, finite element method was utilized and van der Waals force, assumed as 12-6 Lennard-Jones potential, was implemented as the body force term in the finite element formulation.展开更多
This review summarizes the coherent structures (CS) based on two-point correlations and their applications, with a focus on the interpretation of statistic CS and their characteristics. We review studies on this topic...This review summarizes the coherent structures (CS) based on two-point correlations and their applications, with a focus on the interpretation of statistic CS and their characteristics. We review studies on this topic, which have attracted attention in recent years, highlighting improvements, expansions, and promising future directions for two-point statistics of CS in turbulent flow. The CS is one of typical structures of turbulent flow, transporting energy from large-scale to small-scale structures. To investigate the CS in turbulent flow, a large amount of two-point correlation techniques for CS identification and visualization have been, and are currently being, intensively studied by researchers. Two-point correlations with examples and comparisons between different methods are briefly reviewed at first. Some of the uses of correlations in both Eulerian and Lagrangian frames of reference to obtain their properties at consecutive spatial locations and time events are surveyed. Two-point correlations, involving space-time correlations, two-point spatial correlations, and cross correlations, as essential to theories and models of turbulence and for the analyses of experimental and numerical turbulence data are then discussed. The velocity-vorticity correlation structure (VVCS) as one of the statistical CS based on two-point correlations is reiterated in detail. Finally, we summarize the current understanding of two-point correlations of turbulence and conclude with future issues for this field.展开更多
The limited metal-polymer interlaminar property is a significant obstacle to the advancement of Ti/Carbon Fiber(CF)/Polyether Ether Ketone(PEEK)hybrid laminates.We report for the first time a novel method by utilizing...The limited metal-polymer interlaminar property is a significant obstacle to the advancement of Ti/Carbon Fiber(CF)/Polyether Ether Ketone(PEEK)hybrid laminates.We report for the first time a novel method by utilizing the mussel-inspired Polydopamine(PDA)to introduce a strong chemical-physical bonding between titanium and PEEK.The enhanced Fiber-Metal Laminate(FML)exhibits a significant 48.82%enhancement in Interlaminar Shear Strength(ILSS).In addition,it alters the failure mode of the FML from single metal-resin interlaminar delamination to a multi-mechanism,including debonding,delamination of different composite layers,leading to a 28.57%improvement in maximum displacement.展开更多
There remain a number of unsolved problems about chemical reactions, and it is significant to explore new detection methods because they always offer some unique information about reactions from new points of view. Fo...There remain a number of unsolved problems about chemical reactions, and it is significant to explore new detection methods because they always offer some unique information about reactions from new points of view. For the first time, the solidification course of a modified two-component acrylic structural adhesive is measured by using reed-vibration mechanical spectroscopy for liquids （RMS-L） in this work, and results show that there are four sequential processes of mechanical spectra with time. The in-depth analyses indicate that RMS-L can detect in real-time the generation and disappearance of active free radicals, as well as the chemical cross-link processes in the adhesive. This kind of real-time detection will undoubtedly facilitate the study of the chemical reaction dynamics controlled by free radicals.展开更多
In dry attachment systems of spiders and geckos, van der Waals forces mediate attraction between substrate and animal tarsus. In particular, the scopula of Evarcha arcuata spiders allows for reversible attachment and ...In dry attachment systems of spiders and geckos, van der Waals forces mediate attraction between substrate and animal tarsus. In particular, the scopula of Evarcha arcuata spiders allows for reversible attachment and easy detachment to a broad range of surfaces. Hence, reproducing the scopula's roughness compatibility while maintaining anti-bunching features and dirt particle repellence behavior is a central task for a biomimetic transfer to an engineered model. In the present work we model the scopula of E. arcuata from a mechano-elastic point of view analyzing the influence of its hierarchical structure on the attachment behavior. By considering biological data of the gecko and spider, and the simulation results, the adhesive capabilities of the two animals are compared and important confirmations and new directives in order to reproduce the overall structure are found. Moreover, a possible suggestion of how the spider detaches in an easy and fast manner is proposed and supported by the results.展开更多
Cell adhesion is the basis for some cell isolation methods, and is influenced by both of the biochemical and topographic characteristics of the substrates. Herein, based on cell imprinting and click chemistry,we have ...Cell adhesion is the basis for some cell isolation methods, and is influenced by both of the biochemical and topographic characteristics of the substrates. Herein, based on cell imprinting and click chemistry,we have developed a cell-imprinted polydimethylsiloxane(PDMS) with aptamer functionalization(APTCIS). The atom force microscopic analysis results showed that the hierarchical structure matching well with the target cells is successfully introduced on the surface of the APT-CIS. By using the synergistic effects of hierarchical structure and aptamer affinity, the APT-CIS was successfully used for the selective cell adhesion, and 93.9% ± 0.8% of the captured cells could then be released. Thus, the APT-CIS holds promise in selective cell isolation and sorting fields.展开更多
In order to reduce the formaldehyde emission of formaldehyde-based wood adhesive from the source,it is aimed to develop a novel co-condensed resin of glyoxal-monomethylolurea-melamine(G-MMU-M).A series of G-MMU-M resi...In order to reduce the formaldehyde emission of formaldehyde-based wood adhesive from the source,it is aimed to develop a novel co-condensed resin of glyoxal-monomethylolurea-melamine(G-MMU-M).A series of G-MMU-M resins with various formulations of raw materials were successfully prepared.The basic properties and bonding performance of the G-MMU-M resins were determined.Furthermore,the structures of resins were characterized by FTIR,^(13)C NMR,XPS,and ESI-MS.The results show that the prepared G-MMU-M resin remains stable for 30 d,meanwhile,the dry and wet bonding strength of the plywoods bonded with the resins,solid content and viscosity are influenced greatly by the addition amount of melamine and MMU/G molar ratio.The G-MMU-M resins with MMU/G molar ratio of 0.9:1.0 and 8% melamine exhibit the highest dry and bonding strength of 1.98 MPa and 1.27 MPa,increased by 34% and 63%,respectively,in comparison with glyoxal-monomethylolurea(G-MMU)resin.In the G-MMU-M resins,there were four main oligomers including M—CH(—^(+)CH-MMU)-O-MMU,M-CH(—CH_(2)OH)-MMU-O-MMU,M—CH(—OH)—^(+)CH-MMU-O-MMU,and M—CH(—^(+)CH-MMU)-MMU-p-G.展开更多
A new phosphorylcholine, (6-hydroxy) hexyl-2-(trimethylammonio) ethyl phosphate (HTEP), was synthesized andcharasterized. Segmented polyurethane (SPU) containing phosphorylcholine structure was synthesized based ondip...A new phosphorylcholine, (6-hydroxy) hexyl-2-(trimethylammonio) ethyl phosphate (HTEP), was synthesized andcharasterized. Segmented polyurethane (SPU) containing phosphorylcholine structure was synthesized based ondiphenylmethane diisocyanate (MDI), soft segment polytetramethylene glycol (PTMG) and HTEP, with 1,4-butanediol (BD)as a chain extender. The existence of phosphorylcholine structure on the surface of SPU was revealed by attenuated totalreflectance Fourier transform infrard spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and water contactangle measurements. The blood compatibilities of the polymers were evaluated by hemolytic testing and a platelet-richplasma (PRP) adhesion experiment, which was viewed by scanning electron microscopy (SEM) with polyurethane as areference. The novel segmented polyurethane containing phosphorylcholine structure showed improved blood compatibility.展开更多
Flexible attachment actuators are popular in a wide range of applications,owing to their flexibility and highly reliable attachment.However,their reversible adhesion performance depends on the actual effective contact...Flexible attachment actuators are popular in a wide range of applications,owing to their flexibility and highly reliable attachment.However,their reversible adhesion performance depends on the actual effective contact area and peel angle during operation.Therefore,a good actuator must ensure a uniform and reliable pre-pressure load on an adhesive surface,to increase the effective contact area of the attached surface,thereby maximizing adhesion.This study was inspired by fusion bionics for designing a hierarchical attachment structure with vacuum-adsorption and dry-adhesion mechanisms.The designed structure used the normal force under the negative pressure of a suction cup as a stable source of a pre-pressure load.By optimizing the rigid and flexible structural layers of the attachment structure,a load was applied uniformly to the adhesion area;thus,reliable attachment was achieved by self-preloading.The structure achieved detachment by exploiting the large deformation of a pneumatic structure under a positive pressure.The hierarchical attachment structure achieved up to 85%of the optimal performance of the adhesive surface.Owing to its self-preloading and reliable attachment characteristics,the designed structure can be used as an attachment unit in various complex scenarios,such as small,lightweight climbing platforms and the transport of objects in long,narrow pipelines.展开更多
The computer aided engineering(CAE) analysis technique has become one of the most important means in modern automobile development due to its remarkably computing capability.With the development of CAE bussiness softw...The computer aided engineering(CAE) analysis technique has become one of the most important means in modern automobile development due to its remarkably computing capability.With the development of CAE bussiness software and intensive research on automotive development process,the CAE technique,which was only used as an auxiliary validation tool in the later product development in the past,is gradually used in each stage of product development now.Furthermore,accurate and fast analysis data can be supplied effectively.Especially in current CAE application, based on some optimization technologies such as sensitivity,feature and topology,the parametric design gradually enables a CAE engineer to be free from the condition which a convention analysis usually lags behind a design,and makes it be parallel to or even anterior to the design.Under the circumstance,the CAE resources can be maximized in each project development department,thereby promoting the project progress and quality,and creating a new philosophy of 'analysis-driven design'.展开更多
The interfacial microstructures and configurations directly affect the comprehensive properties of the composites,but their interfacial adhesion mechanism is complicated to expound by experimental methods.In this work...The interfacial microstructures and configurations directly affect the comprehensive properties of the composites,but their interfacial adhesion mechanism is complicated to expound by experimental methods.In this work,based on the stacking sequence of the Mg/Mg_(2)Y interface models,nine different Mg/Mg_(2)Y interface configurations with top site,bridge site,and hollow site(HCP)under Mg1,Mg_(2),and Y terminations were successfully constructed and systematically explored by first-principles calculations.The results showed that the Mg_(2)Y(0001)surface with Y termination is the most stable when the yttrium chemical potential()is less than-1.09 eV;otherwise,Mg_(2)Y(0001)surface with Mg1 termination is the most stable.The seven-layer Mg(0001)and eleven-layer Mg_(2)Y(0001)slabs are employed to reflect the bulk-like interior properties.Additionally,the Mg(0001)/Mg_(2)Y(0001)with the Y-HCP stacking has the largest interface thermodynamic stability with the value of 2.383 J/m^(2) in all interface configurations owing to its largest work of adhesion.In addition,the interfacial energy of Y-HCP stacking is significantly smaller than those of Mg1-HCP when is approximately less than-0.55 eV,showing that it is more stable.The thermodynamic stability of Mg/Mg_(2)Y with Y-HCP is due to Mg-Y chemical bonds formed between Mg and Y atoms.Lastly,the Mg/Mg_(2)Y interfaces are strong interfaces based on the Griffith fracture theory.展开更多
The aim of this study was to evaluate the adhesion of human fetal osteoblast cells (CRL-11372) in vitro at 24 h on commercially pure titanium (cp Ti) metal surfaces’ crystalline structure and surface roughnesses that...The aim of this study was to evaluate the adhesion of human fetal osteoblast cells (CRL-11372) in vitro at 24 h on commercially pure titanium (cp Ti) metal surfaces’ crystalline structure and surface roughnesses that are modified by polishing, sand blasting (with alumina (Al2O3)), sand blasting and coating (with titanium oxide (TiO2)), and sand blasting and etching (with oxalic acid). Modified surfaces were characterized quantitatively by a non-contacting optical profilometer in terms of their Rz and Ra values and surface profile diagrams were obtained. These surfaces were characterized qualitatively by scanning electron microscope (SEM) micrographs. The crystalline structures of the coatings were characterized by X-ray diffraction (XRD). CRL-11372 cells were cultured for 24 h and evaluated for their mean total cell counts. Cell morphologies were examined by SEM micrographs. Data were compared by Kruskal-Wallis test followed by Post Hoc LSD test comparisons. SEM micrographs showed variations among the topographies of the surfaces and the morphologies of the cells adhered to these four different surfaces. Cell adhesion was affected by neither Ti chemical composition nor surface roughness within the Ra and Rz parameters used.展开更多
Background: Two differently charged polypeptides, α-poly-L-lysine and poly-L-glutamate, have previously been shown to effectively reduce postoperative intraabdominal adhesions. Though α-poly-L-lysine showed toxicity...Background: Two differently charged polypeptides, α-poly-L-lysine and poly-L-glutamate, have previously been shown to effectively reduce postoperative intraabdominal adhesions. Though α-poly-L-lysine showed toxicity in doses too close to the lowest therapeutic dose, the aim in the present study was to investigate the possible antiadhesive effect of another four cationic polypeptides. Materials/Methods: 125 mice were studied with a standardized and reproducible adhesion model and given epsilon poly-L-lysine, lactoferrin, lysozyme and polyarginine respectively in a combination with poly-L-glutamate. Epsilon poly-L-lysine was also tested in different concentrations and as single treatment. Results: All four cationic polypeptides above showed a significantly better anti-adhesive effect than the controls receiving saline (p<0.05). Epsilon poly-L-lysine had the best antiadhesive effect of the new substances tested in the experiment. Single treatment with the epsilon poly-L-lysine showed toxic side effects. Discussion: We have shown that epsilon poly-L-lysine, polyarginine, lysozyme and lactoferrin, in descending order, all can reduce postoperative intraabdominal adhesions in mice when combined with poly-L-glutamate. There were side effects of epsilon poly-L-lysine resembling those of α-poly-L-lysine, although less toxic. The antiadhesive effect of epsilon poly-L-lysine did not reach the level of α-poly-L-lysine. Further studies will concentrate on additional investigation, trying to modify the α-poly-L-lysine to lower its toxicity. The less toxic epsilon poly-L-lysine also needs further attention in our research of antiadhesive bioactive polypeptides.展开更多
The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new...The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new protection method based on Air Breakdown and insulating adhesive layer(AB-LSP method)was designed to avoid it.In this study,a numerical method was developed to simulate the electrical breakdown,and verified by experiment results.Based on this method,a Finite Element Model(FEM)was established to investigate the effect of two factors(breakdown strength and initial ablation temperature of adhesive layer)on the LSP effectiveness.The results show that the breakdown strength impacts more to the ablation damage in composite than that of high-temperature resistance.Then,another FEM was established to predict the ablation damage by lightning strike in the AB-LSP method protected composite rotor blade.The mechanisms and potential key parameters(magnitude of lightning current,discharge channel location,adhesive layer thickness,and air gap width)that could affect the protection effectiveness were analyzed.The introduction of air breakdown changes the current conduction path and reduces explosion risk.After rational design,this method can offer effective lightning protection for composite helicopter rotor blade and other composite structures.展开更多
基金supported by the National Natural Science Foundation of China (U1609209)National Natural Science Foundation of China (61605162)+2 种基金NSFC-Liaoning Province united foundation (U1608259)National Natural Science Foundation of China (51501219)the financial support from the China Scholarship Council
文摘Paint removal from steel structure is executed for shipyards of marine and offshore engineering.Due to environmental unfriendliness and unhealthy drawbacks of sand blasting technique, laser ablation technique is proposed as a substituting method.By absorbing high energy of the 1064 nm pulsed laser, the paint is vaporized quickly.The ablated debris is then collected by using a suction pump.Initial metal surface of the steel is exposed when laser beam irradiates perpendicularly and scans over it.The cleaned surface fulfills the requirements of surface preparation standards ISO 8501 of SA2.The adhesion is further characterized with pull-off test after carrying out painting with Jotamastic 87 aluminum paint.The repainting can be embedded onto the laser cleaned surface to bond much more tightly.The excellent adhesion strength of 20 MPa between repainted coating and the substrate is achieved, which is higher than what is required by shipyards applications.
基金the NSFC(Nos.51273111,51173105,51573092)the National Basic Research Program of China(973 Program,No.2012CB933803)SJTU-UM Collaborative Research Program,the Program for Professor of Special Appointment(Eastern Scholar)at the Shanghai Institutions of Higher Learning
文摘One of the critical issues in gram-negative bacterial adhesion is how wettability regulates adhesion as the surface wettability varies from superhydrophilic to superhydrophobic,and what is the relevant/contributing role of the lipopolysaccharide（LPS） outer layer of the gram-negative shell during this procedure.Herein,by avoiding the unexpected influence induced by the varied topographies,control over gram-negative bacteria adhesion by wettability is achieved on biomimetic hierarchical surfaces,which is mainly mediated by LPS layer.The study provides a methodology to have a good control over bacteria cell adhesion by properly designing wettable surface structures.This design concept is helpful for developing new generations of biomaterials in order to control a variety of diseases induced by gramnegative bacteria,which still continue to be very important and necessary in the fields of biomedicine.
基金Funded by the National Natural Science Foundation of China(No.50678050)
文摘Organic epoxy matrices have been widely used in the FRP reinforcing technique, but they have serious disadvantages of poor high-temperature resistance. An inorganic adhesive is invented to replace the organic adhesive. For the inorganic adhesive at normal temperature and different high temperatures, the microstructure and phase composition are investigated by means of X-ray diffraction （XRD） and SEM respectively. Results show that inorganic adhesive can resist at least 600 ℃ high temperature. Fire-resistance performance of inorganic adhesive can meet the requirements of fiber reinforced polymer （FRP） strengthened RC structures.
文摘This investigation was conducted to determine the feasibility of using a two-component polyurethane （PUR） adhesive, with special waterproof properties, in constructing wooden structures. We designed and conducted tests to compare the shear strength and adhesion performance of PUR with polyvinyl acetate （PVAc） adhesive on block-shear specimens constructed of oriental beech （Fagus orientalis L.）, fir （Abies alba Mill.）, poplar （Populus deltoides Bartr.）, white oak （Quercus alba L.）, sycamore （Platanus orientalis L.） and white walnut （Juglans cinerea L.）. The values of the percentage of wood failure were also determined in specimens constructed with each adhesive. The highest shear strength values of both adhesives were obtained in specimens constructed of beech, while the lowest shear strength values were obtained in fir and poplar specimens. Average shear strength of the PUR adhesive was 16.5% higher than that of the PVAc adhesive. Specimens constructed of fir, poplar and sycamore were characterised by the highest percentages of wood failure, whereas the lowest average percentages of wood failure were obtained in beech and oak specimens. With the exception of oak specimens, there was no statistically significant difference between percentage of wood failure among the PUR and PVAc adhesives. Generally, the PUR adhesive showed an acceptable adhesion performance on wood materials used in our study.
基金Open Research Foundation of "Anhui Key Laboratory of Textile Materials",China(No.2006F2003)
文摘Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.
文摘Nanohairs, which can be found on the epidermis of Tokay gecko＇s toes, contribute to the adhesion by means of van der Waals force, capillary force, etc. This structure has inspired many researchers to fabricate the attachable nano-scale structures. However, the efficiency of artificial nano-scale structures is not reliable sufficiently. Moreover, the mechanical parameters related to the nano-hair attachment are not yet revealed qualitatively. The mechanical parameters which have influence on the ability of adhesive nano-hairs were investigated through numerical simulation in which only van der Waals force was considered. For the numerical analysis, finite element method was utilized and van der Waals force, assumed as 12-6 Lennard-Jones potential, was implemented as the body force term in the finite element formulation.
文摘This review summarizes the coherent structures (CS) based on two-point correlations and their applications, with a focus on the interpretation of statistic CS and their characteristics. We review studies on this topic, which have attracted attention in recent years, highlighting improvements, expansions, and promising future directions for two-point statistics of CS in turbulent flow. The CS is one of typical structures of turbulent flow, transporting energy from large-scale to small-scale structures. To investigate the CS in turbulent flow, a large amount of two-point correlation techniques for CS identification and visualization have been, and are currently being, intensively studied by researchers. Two-point correlations with examples and comparisons between different methods are briefly reviewed at first. Some of the uses of correlations in both Eulerian and Lagrangian frames of reference to obtain their properties at consecutive spatial locations and time events are surveyed. Two-point correlations, involving space-time correlations, two-point spatial correlations, and cross correlations, as essential to theories and models of turbulence and for the analyses of experimental and numerical turbulence data are then discussed. The velocity-vorticity correlation structure (VVCS) as one of the statistical CS based on two-point correlations is reiterated in detail. Finally, we summarize the current understanding of two-point correlations of turbulence and conclude with future issues for this field.
基金the financial supports of Fundamental Research Funds for the Central Universities,China(Nos.YWF-23-L-1012,YWF-22-L-1017)。
文摘The limited metal-polymer interlaminar property is a significant obstacle to the advancement of Ti/Carbon Fiber(CF)/Polyether Ether Ketone(PEEK)hybrid laminates.We report for the first time a novel method by utilizing the mussel-inspired Polydopamine(PDA)to introduce a strong chemical-physical bonding between titanium and PEEK.The enhanced Fiber-Metal Laminate(FML)exhibits a significant 48.82%enhancement in Interlaminar Shear Strength(ILSS).In addition,it alters the failure mode of the FML from single metal-resin interlaminar delamination to a multi-mechanism,including debonding,delamination of different composite layers,leading to a 28.57%improvement in maximum displacement.
基金supported by the Natural Science Foundations of Xinjiang Automatic Region, China (Grant Nos. 200821104, 2009211B16, and 2010211B16)the Support Program of Science and Technology of Xinjiang Automatic Region, China (Grant No. 201091112)the West-Light Foundation of the Chinese Academy of Sciences (Grant No. RCPY200906)
文摘There remain a number of unsolved problems about chemical reactions, and it is significant to explore new detection methods because they always offer some unique information about reactions from new points of view. For the first time, the solidification course of a modified two-component acrylic structural adhesive is measured by using reed-vibration mechanical spectroscopy for liquids （RMS-L） in this work, and results show that there are four sequential processes of mechanical spectra with time. The in-depth analyses indicate that RMS-L can detect in real-time the generation and disappearance of active free radicals, as well as the chemical cross-link processes in the adhesive. This kind of real-time detection will undoubtedly facilitate the study of the chemical reaction dynamics controlled by free radicals.
基金supported by the ARIADNA scheme (study ID 06/6201) of the European Space Agency
文摘In dry attachment systems of spiders and geckos, van der Waals forces mediate attraction between substrate and animal tarsus. In particular, the scopula of Evarcha arcuata spiders allows for reversible attachment and easy detachment to a broad range of surfaces. Hence, reproducing the scopula's roughness compatibility while maintaining anti-bunching features and dirt particle repellence behavior is a central task for a biomimetic transfer to an engineered model. In the present work we model the scopula of E. arcuata from a mechano-elastic point of view analyzing the influence of its hierarchical structure on the attachment behavior. By considering biological data of the gecko and spider, and the simulation results, the adhesive capabilities of the two animals are compared and important confirmations and new directives in order to reproduce the overall structure are found. Moreover, a possible suggestion of how the spider detaches in an easy and fast manner is proposed and supported by the results.
基金financial support from the National Key Research and Development Program (No. 2016YFA0501401)National Natural Science Foundation of China (Nos. 21575143 and 91543201)+1 种基金CAS Key Project in Frontier Science(No. QYZDY-SSW-SLH017)Kaiguang Yang is the member of Youth Innovation Promotion Association, CAS(No. 2017222)
文摘Cell adhesion is the basis for some cell isolation methods, and is influenced by both of the biochemical and topographic characteristics of the substrates. Herein, based on cell imprinting and click chemistry,we have developed a cell-imprinted polydimethylsiloxane(PDMS) with aptamer functionalization(APTCIS). The atom force microscopic analysis results showed that the hierarchical structure matching well with the target cells is successfully introduced on the surface of the APT-CIS. By using the synergistic effects of hierarchical structure and aptamer affinity, the APT-CIS was successfully used for the selective cell adhesion, and 93.9% ± 0.8% of the captured cells could then be released. Thus, the APT-CIS holds promise in selective cell isolation and sorting fields.
基金National Natural Science Foundation of China(31860188)Special Project of“Leading Talents of Industrial Technology”of Yunnan Ten Thousand Talents Plan(80201408)Yunnan Agricultural joint project(202101BD070001-105)are acknowledged.
文摘In order to reduce the formaldehyde emission of formaldehyde-based wood adhesive from the source,it is aimed to develop a novel co-condensed resin of glyoxal-monomethylolurea-melamine(G-MMU-M).A series of G-MMU-M resins with various formulations of raw materials were successfully prepared.The basic properties and bonding performance of the G-MMU-M resins were determined.Furthermore,the structures of resins were characterized by FTIR,^(13)C NMR,XPS,and ESI-MS.The results show that the prepared G-MMU-M resin remains stable for 30 d,meanwhile,the dry and wet bonding strength of the plywoods bonded with the resins,solid content and viscosity are influenced greatly by the addition amount of melamine and MMU/G molar ratio.The G-MMU-M resins with MMU/G molar ratio of 0.9:1.0 and 8% melamine exhibit the highest dry and bonding strength of 1.98 MPa and 1.27 MPa,increased by 34% and 63%,respectively,in comparison with glyoxal-monomethylolurea(G-MMU)resin.In the G-MMU-M resins,there were four main oligomers including M—CH(—^(+)CH-MMU)-O-MMU,M-CH(—CH_(2)OH)-MMU-O-MMU,M—CH(—OH)—^(+)CH-MMU-O-MMU,and M—CH(—^(+)CH-MMU)-MMU-p-G.
基金Supported by the Special Funds for Major State Basic Research Projects (G1999064705)
文摘A new phosphorylcholine, (6-hydroxy) hexyl-2-(trimethylammonio) ethyl phosphate (HTEP), was synthesized andcharasterized. Segmented polyurethane (SPU) containing phosphorylcholine structure was synthesized based ondiphenylmethane diisocyanate (MDI), soft segment polytetramethylene glycol (PTMG) and HTEP, with 1,4-butanediol (BD)as a chain extender. The existence of phosphorylcholine structure on the surface of SPU was revealed by attenuated totalreflectance Fourier transform infrard spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and water contactangle measurements. The blood compatibilities of the polymers were evaluated by hemolytic testing and a platelet-richplasma (PRP) adhesion experiment, which was viewed by scanning electron microscopy (SEM) with polyurethane as areference. The novel segmented polyurethane containing phosphorylcholine structure showed improved blood compatibility.
基金supported by the National Key R&D program of China(2023YFE0207000)the National Natural Science Foundation of China(Grant No.51975283 and U22B2040)the Research Fund of State Key Laboratory of Mechanics and Control for Aerospace Structures(Grant No.1005-IZD2300225).
文摘Flexible attachment actuators are popular in a wide range of applications,owing to their flexibility and highly reliable attachment.However,their reversible adhesion performance depends on the actual effective contact area and peel angle during operation.Therefore,a good actuator must ensure a uniform and reliable pre-pressure load on an adhesive surface,to increase the effective contact area of the attached surface,thereby maximizing adhesion.This study was inspired by fusion bionics for designing a hierarchical attachment structure with vacuum-adsorption and dry-adhesion mechanisms.The designed structure used the normal force under the negative pressure of a suction cup as a stable source of a pre-pressure load.By optimizing the rigid and flexible structural layers of the attachment structure,a load was applied uniformly to the adhesion area;thus,reliable attachment was achieved by self-preloading.The structure achieved detachment by exploiting the large deformation of a pneumatic structure under a positive pressure.The hierarchical attachment structure achieved up to 85%of the optimal performance of the adhesive surface.Owing to its self-preloading and reliable attachment characteristics,the designed structure can be used as an attachment unit in various complex scenarios,such as small,lightweight climbing platforms and the transport of objects in long,narrow pipelines.
文摘The computer aided engineering(CAE) analysis technique has become one of the most important means in modern automobile development due to its remarkably computing capability.With the development of CAE bussiness software and intensive research on automotive development process,the CAE technique,which was only used as an auxiliary validation tool in the later product development in the past,is gradually used in each stage of product development now.Furthermore,accurate and fast analysis data can be supplied effectively.Especially in current CAE application, based on some optimization technologies such as sensitivity,feature and topology,the parametric design gradually enables a CAE engineer to be free from the condition which a convention analysis usually lags behind a design,and makes it be parallel to or even anterior to the design.Under the circumstance,the CAE resources can be maximized in each project development department,thereby promoting the project progress and quality,and creating a new philosophy of 'analysis-driven design'.
基金supported by the National Natural Science Foundation of China (No.52225101)the Central Universities of China (2021CDJQY-040)+2 种基金the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030006)the Independent Research Project of State Key Laboratory of Mechanical Transmissions (SKLMT-ZZKT-2022Z01,SKLMT-ZZKT-2022M12)the Chongqing Special Project of Science and Technology Innovation of China (cstc2021yszx-jcyj0007).
文摘The interfacial microstructures and configurations directly affect the comprehensive properties of the composites,but their interfacial adhesion mechanism is complicated to expound by experimental methods.In this work,based on the stacking sequence of the Mg/Mg_(2)Y interface models,nine different Mg/Mg_(2)Y interface configurations with top site,bridge site,and hollow site(HCP)under Mg1,Mg_(2),and Y terminations were successfully constructed and systematically explored by first-principles calculations.The results showed that the Mg_(2)Y(0001)surface with Y termination is the most stable when the yttrium chemical potential()is less than-1.09 eV;otherwise,Mg_(2)Y(0001)surface with Mg1 termination is the most stable.The seven-layer Mg(0001)and eleven-layer Mg_(2)Y(0001)slabs are employed to reflect the bulk-like interior properties.Additionally,the Mg(0001)/Mg_(2)Y(0001)with the Y-HCP stacking has the largest interface thermodynamic stability with the value of 2.383 J/m^(2) in all interface configurations owing to its largest work of adhesion.In addition,the interfacial energy of Y-HCP stacking is significantly smaller than those of Mg1-HCP when is approximately less than-0.55 eV,showing that it is more stable.The thermodynamic stability of Mg/Mg_(2)Y with Y-HCP is due to Mg-Y chemical bonds formed between Mg and Y atoms.Lastly,the Mg/Mg_(2)Y interfaces are strong interfaces based on the Griffith fracture theory.
基金Preparation and characterization of the commercially pure titanium metal surfaces in this study were supported by The Research Support Unit of Istanbul University as the project no 1749/21122001.
文摘The aim of this study was to evaluate the adhesion of human fetal osteoblast cells (CRL-11372) in vitro at 24 h on commercially pure titanium (cp Ti) metal surfaces’ crystalline structure and surface roughnesses that are modified by polishing, sand blasting (with alumina (Al2O3)), sand blasting and coating (with titanium oxide (TiO2)), and sand blasting and etching (with oxalic acid). Modified surfaces were characterized quantitatively by a non-contacting optical profilometer in terms of their Rz and Ra values and surface profile diagrams were obtained. These surfaces were characterized qualitatively by scanning electron microscope (SEM) micrographs. The crystalline structures of the coatings were characterized by X-ray diffraction (XRD). CRL-11372 cells were cultured for 24 h and evaluated for their mean total cell counts. Cell morphologies were examined by SEM micrographs. Data were compared by Kruskal-Wallis test followed by Post Hoc LSD test comparisons. SEM micrographs showed variations among the topographies of the surfaces and the morphologies of the cells adhered to these four different surfaces. Cell adhesion was affected by neither Ti chemical composition nor surface roughness within the Ra and Rz parameters used.
文摘Background: Two differently charged polypeptides, α-poly-L-lysine and poly-L-glutamate, have previously been shown to effectively reduce postoperative intraabdominal adhesions. Though α-poly-L-lysine showed toxicity in doses too close to the lowest therapeutic dose, the aim in the present study was to investigate the possible antiadhesive effect of another four cationic polypeptides. Materials/Methods: 125 mice were studied with a standardized and reproducible adhesion model and given epsilon poly-L-lysine, lactoferrin, lysozyme and polyarginine respectively in a combination with poly-L-glutamate. Epsilon poly-L-lysine was also tested in different concentrations and as single treatment. Results: All four cationic polypeptides above showed a significantly better anti-adhesive effect than the controls receiving saline (p<0.05). Epsilon poly-L-lysine had the best antiadhesive effect of the new substances tested in the experiment. Single treatment with the epsilon poly-L-lysine showed toxic side effects. Discussion: We have shown that epsilon poly-L-lysine, polyarginine, lysozyme and lactoferrin, in descending order, all can reduce postoperative intraabdominal adhesions in mice when combined with poly-L-glutamate. There were side effects of epsilon poly-L-lysine resembling those of α-poly-L-lysine, although less toxic. The antiadhesive effect of epsilon poly-L-lysine did not reach the level of α-poly-L-lysine. Further studies will concentrate on additional investigation, trying to modify the α-poly-L-lysine to lower its toxicity. The less toxic epsilon poly-L-lysine also needs further attention in our research of antiadhesive bioactive polypeptides.
文摘The protection effectiveness of traditional Lightning Strike Protection(LSP)for composite rotor blade of helicopter can be diminished due to the explosion risk in overlapping attachment under lightning strike,so a new protection method based on Air Breakdown and insulating adhesive layer(AB-LSP method)was designed to avoid it.In this study,a numerical method was developed to simulate the electrical breakdown,and verified by experiment results.Based on this method,a Finite Element Model(FEM)was established to investigate the effect of two factors(breakdown strength and initial ablation temperature of adhesive layer)on the LSP effectiveness.The results show that the breakdown strength impacts more to the ablation damage in composite than that of high-temperature resistance.Then,another FEM was established to predict the ablation damage by lightning strike in the AB-LSP method protected composite rotor blade.The mechanisms and potential key parameters(magnitude of lightning current,discharge channel location,adhesive layer thickness,and air gap width)that could affect the protection effectiveness were analyzed.The introduction of air breakdown changes the current conduction path and reduces explosion risk.After rational design,this method can offer effective lightning protection for composite helicopter rotor blade and other composite structures.
