To evaluate the effects of ocular biometric variables on corneal biomechanical properties. A total of 102 eyes of 102 participants were enrolled in this cross-sectional study. The axial length (AL) was determined by an IOL master 500 and measurements of corneal biomechanical properties were performed using Corvis ST, integrated with pentacam results. Aging and corneal steepening were associated with less corneal deformability and higher movement of the entire eye. Longer AL corresponded with greater deformability and lower corneal viscous damping properties and less whole eye movement (all P-values < 0.05). In contrast to mean keratometry (Mean K) and corneal diameter, anterior chamber depth (ACD) and AL have a significant effect on corneal biomechanical parameters. Corneal biomechanical index (CBI) was not significantly correlated with any of biometric parameters. Stress–strain index (SSI) was significantly correlated with age (r = 0.470), spherical equivalent (SE) (r = 0.537), AL (r = -0.534) and ACD (r = −0.316) (all P-values < 0.001). In normal individuals, several parameters such as age, ACD, AL and Mean K have a great impact on corneal biomechanical properties; thereby, these effects should be taken into account prior to interpretation of corneal biomechanics, particularly in older ages and eyes with longer AL and steeper cornea.

Vascular network formation and sustenance in both normal and pathological froms of angiogenesis has been a focus of research in developmental biology. The assembly and remodeling of vascular structures play major roles in numerous pathologies, including the angiogenesis of tumors. Endothelial morphogenesis is dependent on a number of chemical and mechanical stimuli and cell–cell signaling. To understand the nature of angiogenesis and vasculogenesis, many models have been developed to simulate these phenomena based on the defined responses of endothelial cells to these stimuli. Among the mechanical signals affecting these cells, flow-related stresses, including shear stress, play a major role in migration, elongation, attachment to the matrix and neighboring cells, and eventually the morphogenesis of vascular networks. Here, we proposed a model to describe the cellular responses to shear and tensile stress induced by fluid flow, which can describe some of the morphological behaviors observed in in vitro and in vivo studies. The lattice Boltzmann method was utilized to model the flow, and the cellular Potts model was used to simulate the cellular responses to the flow. This model is based on the hypothesis that endothelial cell binding energy to the matrix is regulated by shear stress and tensile stress acting on the attachment site and is increased by shear stress and decreased by tensile stress. It was demonstrated that these rules can predict the development of vascular networks and the sustenance of lumens and regression in the low flow regions. The results of this study can be further improved to investigate endothelial dysfunctions, such as atherosclerosis, as well as tumor angiogenesis and vascular permeability, which are directly related to the flow rate and endothelial responses to shear stresses.

Topography of extracellular matrix plays a major role in many biological events including tissue healing, morphogenesis and growth. It is known that matrix constitution and mechanical properties are deciding factors in governing the fate of its inhabitant cells. Besides the direct mechanical cues, matrices also facilitate the release and uptake of certain chemicals and participate in cell-cell and cell- ECM crosstalk. Mechanical strains in the matrix are proved to direct endothelial cell migration and elongation leading to angiogenesis, and there is a consensus that matrix stiffness, fiber density and fiber orientation can enhance angiogenesis in the preferred direction of stiffness gradient. In this study, we specifically investigated the role of topography in guidance of endothelial self-reorganization prompted by the effect of fluid flow hindrance and facilitation in certain directions. We adopted our previous model of fluid flow guided angiogenesis for cellular responses. Lattice Boltzmann model of fluid flow was adopted and modified to study the effect of unidirectional and randomly oriented fibers. To study the effect of fiber orientation, we customized a previously proposed model of porosity in lattice Boltzmann to suit this purpose. This model could reproduce the effects of fiber orientations in matrix on endothelial migration and vasculogenesis. Simulations showed better confluency of formed lumens when prescribed flow is in the direction of fiber orientation. These results can have further implications in understanding endothelial complications in certain diseases as well as in tumor angiogenesis and metastasis.

In this work, liberation of cisplatin molecules from interior of a nanotube due to entrance of an Ag-nanowire inside it was simulated by classical molecular dynamics method. The aim of this simulation was investigation on the effects of diameter, chirality, and composition of the nanotube, as well as the influence of temperature on this process. For this purpose, single walled carbon, boron nitride, and silicon carbide nanotube were considered. In order for a more concise comparison of the results, a new parameter namely efficiency of drug release, was introduced. The results demonstrated that the efficiency of drug release is sensitive to its adsorption on outer surface of the nanotube. Moreover, this efficiency is also sensitive to the nanotube composition and its diameter. For the effect of nanotube composition, the results indicated that silicon carbide nanotube has the least efficiency for drug release, due to its strong drug-nanotube. Also, the most important acting forces on drug delivery are van der Waals interactions. Finally, the kinetic of drug release is fast and is not related to the structural parameters of the nanotube and temperature, significantly.