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| 1 | Two Dimensional Nanoscale Reciprocating Sliding Contacts of Textured Surfaces显示文摘Detailed behaviors of nanoscale textured surfaces during the reciprocating sliding contacts are still unknown although they are widely used in mechanical components to improve tribological characteristics. The current research of sliding contacts of textured surfaces mainly focuses on the experimental studies, while the cost is too high. Molecular dynamics(MD) simulation is widely used in the studies of nanoscale single-pass sliding contacts, but the CPU cost of MD simulation is also too high to simulate the reciprocating sliding contacts. In this paper, employing multiscale method which couples molecular dynamics simulation and finite element method, two dimensional nanoscale reciprocating sliding contacts of textured surfaces are investigated. Four textured surfaces with different texture shapes are designed, and a rigid cylindrical tip is used to slide on these textured surfaces. For different textured surfaces, average potential energies and average friction forces of the corresponding sliding processes are analyzed. The analyzing results show that 'running-in' stages are different for each texture, and steady friction processes are discovered for textured surfaces II, III and IV. Texture shape and sliding direction play important roles in reciprocating sliding contacts, which influence average friction forces greatly. This research can help to design textured surfaces to improve tribological behaviors in nanoscale reciprocating sliding contacts. | TONG Ruiting LIU Geng LIU Tianxiang | 2016 | Chinese Journal of Mechanical Engineering2016，29，3： | 3 |
| 2 | Friction Characteristics of Nanoscale Sliding Contacts between Multi-Asperity Tips and Textured Surfaces显示文摘Nanoscale sliding contacts of smooth surfaces or between a single asperity and a smooth surface have been widely investigated by molecular dynamics simulations,while there are few studies on the sliding contacts between two rough surfaces.Actually,the friction of two rough surfaces considering interactions between more asperities should be more realistic.By using multiscale method,friction characteristics of two dimensional nanoscale sliding contacts between rigid multi-asperity tips and elastic textured surfaces are investigated.Four nanoscale textured surfaces with different texture shapes are designed,and six multi-asperity tips composed of cylindrical asperities with different radii are used to slide on the textured surfaces.Friction forces are compared for different tips,and effects of the asperity radii on the friction characteristics are investigated.Average friction forces for all the cases are listed and compared,and effects of texture shapes of the textured surfaces are discussed.The results show that textured surface II has a better structure to reduce friction forces.The multi-asperity tips composed of asperities with R=20r0(r0=0.227 7 nm)or R=30r0get higher friction forces compared with other cases,and more atoms of the textured surfaces are taken away by these two tips,which are harmful to reduce friction or wear.For the case of R=10r0,friction forces are also high due to large contact areas,but the sliding processes are stable and few atoms are taken away by the tip.The proposed research considers interactions between more asperities to make the model approach to the real sliding contact problems.The results will help to vary or even control friction characteristics by textured surfaces,or provide references to the design of textured surfaces. | TONG Ruiting LIU Geng LIU Tianxiang | 2013 | Chinese Journal of Mechanical Engineering2013，26，6： | 3 |
| 3 | Adaptive Multiscale Method for Two-dimensional Nanoscale Adhesive Contacts显示文摘There are two separate traditional approaches to model contact problems: continuum and atomistic theory. Continuum theory is successfully used in many domains, but when the scale of the model comes to nanometer, continuum approximation meets challenges. Atomistic theory can catch the detailed behaviors of an individual atom by using molecular dynamics (MD) or quantum mechanics, although accurately, it is usually time-consuming. A multiscale method coupled MD and finite element (FE) is presented. To mesh the FE region automatically, an adaptive method based on the strain energy gradient is introduced to the multiscale method to constitute an adaptive multiscale method. Utilizing the proposed method, adhesive contacts between a rigid cylinder and an elastic substrate are studied, and the results are compared with full MD simulations. The process of FE meshes refinement shows that adaptive multiscale method can make FE mesh generation more flexible. Comparison of the displacements of boundary atoms in the overlap region with the results from full MD simulations indicates that adaptive multiscale method can transfer displacements effectively. Displacements of atoms and FE nodes on the center line of the multiscale model agree well with that of atoms in full MD simulations, which shows the continuity in the overlap region. Furthermore, the Von Mises stress contours and contact force distributions in the contact region are almost same as full MD simulations. The method presented combines multiscale method and adaptive technique, and can provide a more effective way to multiscale method and to the investigation on nanoscale contact problems. | TONG Ruiting LIU Geng LIU Lan WU Liyan | 2013 | Chinese Journal of Mechanical Engineering2013，26，3： | 2 |
| 4 | Multiscale Analysis on Two-dimensional Nanoscale Adhesive Contacts显示文摘Nanoscale adhesive contacts play a key role in micro/nano-electro-mechanical systems as the dimension of the components come to nanometer.Experimental studies on nanoscale adhesive contacts are limited by some uncertain factors and the cost of experiments is too high.Besides,nanoscale textured surfaces are difficult to process and nanoscale adhesive contacts of textured surfaces are still lack of investigation.By using multiscale method,which couples molecular dynamics simulation and finite element method,two-dimensional nanoscale adhesive contacts between a rigid cylindrical tip and an elastic substrate are investigated.For the contacts between the rigid cylindrical tip and smooth surface,Von Mises stress distributions,the maximum Von Mises stresses,and contact forces are compared for different radii to show the size effects and adhesive effects.The phenomena of hysteresis are observed and more obvious as the radii of the tip increase.The influences of indentation depth and indentation speed are also discussed.Then two series of textured surfaces are employed,and the influences of the texture asperity shape,asperity height,and asperity spacing on contact forces are studied.The contact forces comparisons show that textured surfaces can reduce contact forces effectively in the range of the two series.Contact forces of textured surfaces increase as the asperity heights increase,and textured surfaces with smaller asperity spacing will get higher contact forces.Contact forces may be controlled through textured surfaces in the future.The obtained results will help to improve contact condition and provide theory basis for texture design. | TONG Ruiting LIU Geng LIU Lan | 2012 | Chinese Journal of Mechanical Engineering2012，25，3： | 1 |
| 5 | ANALYSIS ON THERMAL ELASTO-PLASTIC ASPERITY CONTACTS OF LAYERED MEDIA显示文摘A thermal elasto-plastic asperity contact model is investigated,which takes into account the steady-state heat transfer and the asperity distortion due to thermal elasto-plastic deformations.A hard coating and a soft coating are applied to study the correlations between contact area and contact pressure,average gap and contact pressure,coating thickness and contours of the contact stress distribution,etc.The effects of material properties,coating thickness,frictional coefficient,and the heat input combinations on the stress distribution are investigated and discussed.The frictional heat input increases the maximum value of von Mises stress.Finally,the appropriate thickness of the hard coating is also discussed.To protect the substrate,one can choose hard coating and the thickness of that is suggested that can be h_c=70 R_m. | TONG Ruiting LIU Geng ZENG Quanren LIU Tianxiang | 2008 | Chinese Journal of Mechanical Engineering2008，21，2： | 1 |
| 6 | A Frictional Heat Model of Planetary Roller Screw Mechanism Considering Load Distribution显示文摘 | MA Shangjun LIU Geng TONG Ruiting | 2015 | Mechanics Based Design of Structures and Machines2015，43，： | 1 |
| 7 | Multiscale analysis on two dimensional nanoscale sliding contacts of textured surfaces显示文摘 | TONG Ruiting LIU Geng LIU Tianxiang | 2011 | Journal of Tribology2011，133，4： | 1 |
| 8 | Improving antibody affinity through in vitro mutagenesis in complementarity determining regions显示文摘High-affinity antibodies are widely used in diagnostics and for the treatment of human diseases.However,most antibodies are isolated from semi-synthetic libraries by phage display and do not possess in vivo affinity maturation,which is triggered by antigen immunization.It is therefore necessary to engineer the affinity of these antibodies by way of in vitro assaying.In this study,we optimized the affinity of two human monoclonal antibodies which were isolated by phage display in a previous related study.For the 42A1 antibody,which targets the liver cancer antigen glypican-3,the variant T57H in the second complementarity-determining region of the heavy chain(CDR-H2)exhibited a 2.6-fold improvement in affinity,as well as enhanced cell-binding activity.For the I4A3 antibody to severe acute respiratory syndrome coronavirus 2,beneficial single mutations in CDR-H2 and CDR-H3 were randomly combined to select the best synergistic mutations.Among these,the mutation S53P-S98T improved binding affinity(about 3.7 fold)and the neutralizing activity(about 12 fold)compared to the parent antibody.Taken together,single mutations of key residues in antibody CDRs were enough to increase binding affinity with improved antibody functions.The mutagenic combination of key residues in different CDRs creates additive enhancements.Therefore,this study provides a safe and effective in vitro strategy for optimizing antibody affinity. | Wei Ye Xiaoyu Liu Ruiting He Liming Gou Ming Lu Gang Yang Jiaqi Wen Xufei Wang Fang Liu Sujuan Ma Weifeng Qian Shaochang Jia Tong Ding Luan Sun Wei Gao | 2022 | The Journal of Biomedical Research2022，36，3： | 0 |
| 9 | Molecular Dynamics Simulation on Friction and Thermal Properties of FCC Copper in Nanoscale Sliding Contacts显示文摘In nanoscale sliding contact,adhesion effects and adhesive force are predominant,and high friction force will be produced.Friction energy is mainly converted into heat,and the heat will make nanomaterials become soft to affect friction behaviors,so it is important to investigate the friction and thermal properties of the nanoscale sliding contacts.A model of a nanoscale sliding contact between a rigid cylindrical tip and an FCC copper substrate is developed by molecular dynamics simulation.The thermal properties of the substrate and the friction behaviors are studied at different sliding velocities and different tip radii.The results show that at a low sliding velocity,the friction force fluctuation is mainly caused by material melting⁃solidification,while at a high sliding velocity the material melting is a main factor for the friction reduction.The average friction forces increase at initial phase and then decrease with increasing sliding velocity,and the average temperature of the substrate increases as sliding velocity increases.Increasing tip radius significantly increases the temperature,while the coupled effects of tip radius and temperature rise make friction force increase slightly. | Ruiting Tong Bin Han Tao Zhang Zefen Quan Geng Liu | 2022 | Journal of Harbin Institute of Technology(New Series)2022，29，2： | 0 |
| 10 | Application of MoS_(2)in the space environment:a review显示文摘A considerable portion of space mechanism failures are related to space tribological problems.Cold welding in high vacuum;surface erosion and collision damage caused by various radiations,high temperature oxidation under atomic oxygen(AO)bombardment;and thermal stress caused by temperature alternation all alter the physical,chemical,and friction properties of materials.In particular,the space vibration caused by alternating temperatures and microgravity environments can alter the motion of the contact body,further affecting its friction properties.Improving the friction properties of contact surfaces in the space environment is an important way to extend the service life of spacecraft.Traditional lubricants can no longer meet the lubrication requirements of the space environment.This study describes the characteristics of the space environment and the applications of solid lubricants.The friction properties of MoS_(2),a solid lubricant widely used in space,are discussed.The synergistic lubrication of MoS_(2)with surface textures or metals is presented.Advances in research on the friction properties of collision sliding contacts in the space environment are reviewed.The combination of MoS_(2)and soft metals with surface textures is introduced to reduce the effects of vibration environments on the friction properties of moving parts in space mechanisms.Finally,the challenges and future research interests of MoS_(2)films in space tribology are presented. | Menghe ZHOU Ruiting TONG Tao ZHANG Geng LIU | 2023 | Frontiers of Mechanical Engineering2023，18，3： | 0 |
| 11 | Potential mechanism exploration of San Wei Tan Xiang capsule for depression treatment by network pharmacology and molecular docking显示文摘San Wei Tan Xiang(SWTX)capsule has been proved to have significant curative effect on depression in clinic and have less side effects in the treatment.Based on network pharmacology,the mechanism of depression treatment by SWTX capsule was studied.The related targets of depression were collected in the GeneCards database.The active ingredients and potential target genes of SWTX were screened out in the TCMSP database,and the chemical formulas of the active ingredients were confirmed in the PubChem database.As a result,Oleic,quercetin,and beta-sitosterol were screened to be the main ingredients correlated with depression.And NCOA2,GABRA1,and RXRA were analyzed to be the main targets of SWTX on depression.Moreover,the results of molecular docking showed that Oleic and quercetin successfully docked with RXRA.Taken together,using the method of network pharmacology,the main active ingredients of SWTX,and its target points and related pathways on depression are initially revealed,which provides a new idea for depression treatment. | Ruiting Ma Yuanyuan Ma Ce Li Lijun Tong | 2022 | Medicine in Novel Technology and Devices2022，，4： | 0 |
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