Browsing by Author "Xiao, Xianghui"

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    Alcohol exposure decreases osteopontin expression during fracture healing and osteopontin-mediated mesenchymal stem cell migration in vitro
    (BMC, 2018-04-27) Natoli, Roman M.; Yu, Henry; Meislin, Megan Conti-Mica; Abbasnia, Pegah; Roper, Philip; Vuchkovska, Aleksandra; Xiao, Xianghui; Stock, Stuart R.; Callaci, John J.; Orthopaedic Surgery, School of Medicine
    BACKGROUND: Alcohol consumption is a risk factor for impaired fracture healing, though the mechanism(s) by which this occurs are not well understood. Our laboratory has previously shown that episodic alcohol exposure of rodents negatively affects fracture callus development, callus biomechanics, and cellular signaling which regulates stem cell differentiation. Here, we examine whether alcohol alters chemokine expression and/or signaling activity in the mouse fracture callus during early fracture healing. METHODS: A mouse model for alcohol-impaired tibia fracture healing was utilized. Early fracture callus was examined for alcohol-effects on tissue composition, expression of chemokines involved in MSC migration to the fracture site, and biomechanics. The effects of alcohol on MSC migration and cell adhesion receptors were examined in an in vitro system. RESULTS: Mice exposed to alcohol showed decreased evidence of external callus formation, decreased callus-related osteopontin (OPN) expression levels, and decreased biomechanical stiffness. Alcohol exposure decreased rOPN-mediated MSC migration and integrin β1 receptor expression in vitro. CONCLUSIONS: The effects of alcohol exposure demonstrated here on fracture callus-associated OPN expression, rOPN-mediated MSC migration in vitro, and MSC integrin β1 receptor expression in vitro have not been previously reported. Understanding the effects of alcohol exposure on the early stages of fracture repair may allow timely initiation of treatment to mitigate the long-term complications of delayed healing and/or fracture non-union.
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    Kinetic Monte Carlo simulation of sintering behavior of additively manufactured stainless steel powder particles using reconstructed microstructures from synchrotron X-ray microtomography
    (Elsevier, 2019-06-01) Zhang, Yi; Xiao, Xianghui; Zhang, Jing; Mechanical Engineering and Energy, School of Engineering and Technology
    In this study, the sintering behavior of additively manufactured stainless steel powder particles is simulated using a three-dimensional kinetic Monte Carlo (kMC) model. The initial microstructure of powder particles is reconstructed using micro-CT images from the Argonne National Laboratory’s synchrotron X-ray microtomography facility. Using the model, the sintering characteristics of the powder, including its relative density, neck growth, and grain coarsening, are quantitatively analyzed. Sintering temperature directly affects the rate of densification and grain growth and coarsening. Higher temperature results in faster densification and grain growth. Additionally, the relationship between grain coarsening and densification is analyzed. It is observed that when the relative density is below 0.70, the powder particles undergo densification; whereas when the relative density is higher than 0.70, grain coarsening is the main mechanism.
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    Phase Field Modeling of Coupled Phase Separation and Diffusion-Induced Stress in Lithium Iron Phosphate Particles Reconstructed From Synchrotron Nano X-ray Tomography
    (ASME, 2019-11) Wu, Linmin; Xiao, Xianghui; Zhang, Jing; Mechanical Engineering and Energy, School of Engineering and Technology
    In this study, the phase separation phenomenon and diffusion-induced stresses in lithium iron phosphate (LiFePO4) particles under a potentiostatic discharging process have been simulated using the phase field method. The realistic particles reconstructed from synchrotron nano X-ray tomography along with idealized spherical and ellipsoid shaped particles were studied. The results show that stress and diffusion process in particles are strongly influenced by particle shapes, especially at the initial lithiation stage. Stresses in the realistic particles are higher than that in the idealized spherical ones by at least 30%. The diffusion-induced hydrostatic stress has a strong relationship with lithium ion concentration. The hydrostatic stresses and first principal stresses tend to shift from lower values to higher values as the particle takes in more lithium ions. Additionally, the diffusion-induced stresses are related to the maximum concentration difference in the particle. High concentration difference will cause high stresses. In ellipsoid particles, the stress levels increase with the aspect ratios. The model provides a design tool to optimize the performance of cathode materials with phase separation phenomena.
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    Three-Dimensional Finite Element Study on Stress Generation in Synchrotron X-Ray Tomography Reconstructed Nickel-Manganese-Cobalt Based Half Cell
    (Elsevier, 2016-12) Wu, Linmin; Xiao, Xianghui; Wen, Youhai; Zhang, Jing; Department of Mechanical Engineering, School of Engineering and Technology
    In this study, the stress generation caused by phase transitions and lithium intercalation of nickel-manganese-cobalt (NMC) based half cell with realistic 3D microstructures has been studied using finite element method. The electrochemical properties and discharged curves under various C rates are studied. The potential drops significantly with the increase of C rates. During the discharge process, for particles isolated from the conductive channels, several particles with no lithium ion intercalation are observed. For particles in the electrochemical network, the lithium ion concentration increases during the discharge process. The stress generation inside NMC particles is calculated coupled with lithium diffusion and phase transitions. The results show the stresses near the concave and convex regions are the highest. The neck regions of the connected particles can break and form several isolated particles. If the isolated particles are not connected with the electrically conductive materials such as carbon and binder, the capacity loses in battery. For isolated particles in the conductive channel, cracks are more likely to form on the surface. Moreover, stresses inside the particles increase dramatically when considering phase transitions. The phase transitions introduce an abrupt volume change and generate the strain mismatch, causing the stresses increase.