Differences in the Microarchitectural and Histomorphologic Characteristics Between Glucocorticoid-induced Osteonecrosis of Femoral Head and Alcohol-induced Osteonecrosis of Femoral Head

AimsTo analyze microarchitecture and histomorphology characteristics of different regions in femoral heads from patients with glucocorticoid-induced osteonecrosis of femoral head (GIONFH) and alcohol-induced osteonecrosis of femoral head (AIONFH). MethodsPatients diagnosed with GIONFH and AIONFH were recruited. Femoral heads were obtained after total hip replacement. Micro-CT was applied to evaluate the microstructure of 9 regions of interest (ROIs) in the femoral head. Along the supero-inferior orientation, the femoral head was divided into necrotic region, reactive interface, and normal region; along the medio-lateral orientation, the femoral head was divided into medial region, central region and lateral region. Decalcified and undecalcified bone histology were then performed to assess histopathological alterations and bone remodeling levels. Results42 GIONFH patients (50 hips) and 43 AIONFH patients (50 hips) anticipated in the study. In the necrotic region, most of the microarchitectural parameters did not differ significantly between GIONFH and AIONFH, whereas both the reactive interface and normal region illustrated significant differences in the microstructure and histomorphometry. The reactive interface and normal region exhibited a less sclerotic microarchitecture, but a higher bone remodeling level in GIONFH as compared with AIONFH. Despite similar necrotic pathological manifestations, subchondral trabecular microfracture in the necrotic region was more severe and vasculature of the reactive interface was more abundant in GIONFH. ConclusionsAlthough these two subtypes of ONFH shared similar microarchitecture and pathological features in the necrotic region, GIONFH exhibited a less sclerotic microarchitecture and a more active bone metabolic status in both the reactive interface and normal region.

EFFECTS OF STOICHIOMETRY ON PROPERTIES OF DGEBF/DETDA EPOXY USING MOLECULAR DYNAMICS

This article details the molecular modeling of full and off-stoichiometry models of the DGEBF/DETDA epoxy system using Molecular Dynamics to predict the mechanical properties as a function of the crosslinking density. The Reactive Interface Force Field (IFF-R) is implemented in this work to simulate mechanical deformation. The “fix bond/react” command in LAMMPS is used to simulate crosslinking between epoxy monomers. The results show that the predicted mass density, volumetric shrinkage, and bulk modulus have a strong dependence on the stoichiometry of the epoxy.

PROCESS MODELLING THE CURE OF BISPHENOL-A EPOXY/JEFFAMINE SYSTEM USING ICME

The prediction of thermo-mechanical properties of a thermoset resin at different stages of cure is a complex process. An Integrated Computational Material Engineering (ICME) approach is used to predict the properties of a EPON828/Jeffamine D230 system. The proposed framework integrates two length scales - nano and microscale. Molecular Dynamics (MD) is used to predict the volume shrinkage and mechanical properties of the epoxy resin as a function of the progressing crosslink density at room temperature using the Reactive Interface forcefield (IFF-R). The predicted resin properties show good agreement with the literature, proving that IFF-R can be reliably used for this purpose. Once characterized, the predicted properties are used to further predict the effects of cure shrinkage and property transformation on the bulk-level composite residual stresses. P. P. DESHPANDE

MOLECULAR DYNAMICS SIMULATION OF POLYBENZOXAZINE RESIN FOR PROCESS MODELING

In this work, Molecular Dynamics (MD) simulations are performed to predict the physical properties (gelation point, mass density, volumetric shrinkage) and mechanical properties (Bulk modulus, Shear modulus, Young’s Modulus, Poisson’s ratio) of a PolyBenzoxazine (PBZ) resin system as a function of crosslinking density. The molecular models are developed using the Reactive Interface Force Field (IFF-R). The results obtained from MD are in good agreement with the experimental data.