基于先进生物材料的心肌细胞力–电微环境体外构建

心血管疾病是当前全球范围内导致人类死亡的首要原因,心肌组织工程的发展为心血管疾病的治疗,尤其是心肌组织再生修复提供了最有潜力的解决方案.心血管疾病的发生发展与细胞力–电微环境的变化密切相关.近十几年,随着先进生物材料和微纳生物制造技术的发展,越来越多的研究表明,细胞力–电微环境的调控对工程化心肌组织的成熟和功能化以及心肌组织再生修复具有重要意义.本文首先阐明了在体心肌细胞所处力学微环境的生物学基础以及电信号的传导过程,包括正常和疾病状态下心肌细胞所处的力–电微环境.其次调研了用于心肌组织工程的先进生物材料的研究现状.最后总结用于基底硬度与应力应变细胞微环境以及细胞电学微环境的构建和调控,以及细胞对力–电微环境的生物学响应.     

Engineering mechanical-electrical cell microenvironment in myocardium using advanced biomaterials

心血管疾病是当前全球范围内导致人类死亡的首要原因, 心肌组织工程的发展为心血管疾病的治疗, 尤其是心肌组织再生修复提供了最有潜力的解决方案.心血管疾病的发生发展与细胞力--电微环境的变化密切相关. 近十几年, 随着先进生物材料和微纳生物制造技术的发展, 越来越多的研究表明, 细胞力--电微环境的调控对工程化心肌组织的成熟和功能化以及心肌组织再生修复具有重要意义. 本文首先阐明了在体心肌细胞所处力学微环境的生物学基础以及电信号的传导过程, 包括正常和疾病状态下心肌细胞所处的力--电微环境.其次调研了用于心肌组织工程的先进生物材料的研究现状.最后总结用于基底硬度与应力应变细胞微环境以及细胞电学微环境的构建和调控, 以及细胞对力--电微环境的生物学响应.%     

Modelling tire-moist terrain interaction using advanced computational techniques

This paper focuses on predicting and analyzing the tire-moist terrain interaction. The moist terrain (sand) is modelled using Smoothed-Particle Hydrodynamics (SPH) technique. The SPH basic interpolation technique is described, and the necessary interpolation equations are implemented. The soil is modelled using the hydrodynamic elastic-plastic material, while the water is modelled using Murnaghan equation of state. The numerical interaction between both materials is defined using Darcy’s law. The soil moisturizing technique consists of layering water particles on top of sand particles and pressurizing the water into the sand. The moisturizing technique is examined using the direct shear-strength test, and validated against physical measurement carried out in a laboratory under similar soil conditions and bulk density. Finally, the results and the effect of moisture content on tire-moist terrain interaction are discussed and investigated using a previously modelled and validated off-road truck tire size 315/80R22.5.     

Imaging oxygen microenvironment in hydrogel microwell array

Hydrogel microwell arrays (HMAs) have been wildly used for engineering cell microenvironment by providing well-controlled biophysical and biochemical cues (e.g., three dimensional (3D) physical boundary, biomolecule coating) for cells. Among these cues, the oxygen microenvironment has shown great effect on the cellular physiological processes. However, it is currently technically challenging to characterize the local oxygen microenvironment within HMAs. Here, we prepared HMAs with different crosslinking concentrations to adjust the structural and physical properties of HMAs. Then we introduced a scanning electrochemical microscopy (SECM)-based electrochemical method to map the surface topography and oxygen microenvironment around HMAs. The SECM results show both the 3D topography and the oxygen permeability of HMAs in aqueous solution. The obtained oxygen permeability of HMAs increases with increasing the crosslinking concentration, and the microwell boundaries show the highest oxygen permeability throughout HMAs. This work demonstrates that SECM offers a high spatial resolution and in-situ method for characterization of the topography and the local oxygen permeability of HMAs, which can provide useful information for better engineering cell microenvironment through optimizing HMAs design.     

肿瘤及其微环境的力学问题

肿瘤微环境包括肿瘤细胞、间质细胞、细胞外基质等.其在肿瘤的生长和发展过程中起着关键作用.肿瘤的微环境与正常组织的微环境有着显著的不同.肿瘤中的压应力对微环境有着多方面的影响, 例如, 可调控血管与淋巴管的功能, 造成代谢异常和间质高压, 压缩间隙基质, 增大药物输运的困难, 促进间质细胞变异并诱导肿瘤细胞转移. 因此, 肿瘤中的力学因素引起了广泛关注.本文总结了肿瘤及其微环境力学问题的研究进展, 讨论了肿瘤微环境中应力产生、药物输运、肿瘤转移等问题, 介绍了肿瘤微环境正常化的策略及其对肿瘤治疗的意义.      

The mechanical problems in tumor and tumor microenvironment

肿瘤微环境包括肿瘤细胞、间质细胞、细胞外基质等.其在肿瘤的生长和发展过程中起着关键作用.肿瘤的微环境与正常组织的微环境有着显著的不同.肿瘤中的压应力对微环境有着多方面的影响, 例如, 可调控血管与淋巴管的功能, 造成代谢异常和间质高压, 压缩间隙基质, 增大药物输运的困难, 促进间质细胞变异并诱导肿瘤细胞转移. 因此, 肿瘤中的力学因素引起了广泛关注.本文总结了肿瘤及其微环境力学问题的研究进展, 讨论了肿瘤微环境中应力产生、药物输运、肿瘤转移等问题, 介绍了肿瘤微环境正常化的策略及其对肿瘤治疗的意义.     

Development and validation of off-road tire-gravelly soil interaction using advanced computational techniques

This paper presents a novel modelling technique to compute the interaction between an 8x4 off-road truck and gravelly soil (sand with gravel soil). The off-road truck tire size 315/80R22.5 is modelled using the Finite Element Analysis (FEA) technique and validated using manufacturer-provided data in static and dynamic responses. The gravelly soil is modelled using Smoothed-Particle Hydrodynamics (SPH) technique and calibrated against physical measurements using pressure-sinkage and direct shear-strength tests. The tire-gravelly soil interaction is captured using the node symmetric node to segment with edge treatment algorithm deployed for interaction between FEA and SPH elements. The model setup consists of four tires presenting the four axles of the truck, the first tire is a free-rolling steering tire, the second and third tires are driven tires and the fourth tire is a free-rolling push tire. The truck tires-gravelly soil interaction is computed and validated against physical measurements performed in Göteborg, Sweden. The effect of gravelly soil compaction and truck loading on the tire performance is discussed and investigated.     

Towards a real-time pneumatic tire performance prediction using an advanced tire-ice interface model

Icy road conditions and tire operational parameters play a vital role in determining the overall performance of a vehicle. This study builds on prior work in the researchers’ group. The Advanced Tire-Ice Interface Model (ATIIM) simulates the temperature rise in the contact patch based on the measured pressure distribution and the thermal properties of the tread compound and of the ice surface. It has the capability to simulate the height of the thin water film created from the melted ice, to predict the tractive performance, and to estimate the viscous friction due to the water layer and the influence of braking operations, including the locked wheel condition. The experimental investigation included measuring the bulk temperature distribution in the contact patch to validate the temperature rise simulations of the ATIIM. As shown by the simulations and the test data, a rise in temperature was observed from the leading edge to the trailing edge of the contact patch. As the wheel load increases, the difference in temperature rise increases, as also reflected in the experimental study. When the temperature difference was significant, a thin water film was observed that resulted in a reduction of friction, which was simulated using the ATIIM.     

Role of endothelial cells in the regulation of mechanical microenvironment on tumor progression

Acta Mechanica Sinica - Majority of cancer patients die from cancer metastases. The physical stimulation produced by microenvironment regulates invasive behavior of cancer cells. Blood vessel is...     

Simulations of flow through open cell metal foams using an idealized periodic cell structure

A new approach to modeling the flow through a porous medium with a well defined structure is presented. This approach entailed modeling an idealized open cell metal foam based on a fundamental periodic unit of eight cells and solving the flow through the three-dimensional cellular unit. To model an infinitely large matrix, periodic boundary conditions were set on the walls parallel to the flow direction, while a pseudo-periodic boundary condition with a prescribed volumetric flow rate was set over the inlet–outlet pair of the unit cell. The pressure drop data of the flow through the cellular unit were then compared on a length-normalized basis against experimental data. The pressure drop values predicted by the simulations were consistently 25% lower than the values obtained in the experiments on a similar foam and under identical flow conditions. One explanation for the discrepancy between the two sets of data is the lack of pressure drop increasing wall effects in the simulations. The increase in the pressure drop from wall effects in the simulation was quantified.