Quantification of the foreign body reaction by means of a miniaturized imaging window for intravital nonlinear microscopy

Brand new biomaterials, intended to be used on humans, must undergo in vivo quantification standardized, expensive and unethical procedures mainly based on histopathological analysis, from dissections, as defined by the ISO 10993 normative set. The aim is to prove the biomaterials biocompatibility. There exist no methods based on intravital microscopy able to satisfy the normative quantification requirements both reducing the number of employed animals and related costs. We developed a miniaturized imaging window, the Microatlas, which allows subcutaneous repeated observations in vivo of the foreign body reactions, for example to the implantation of a biomaterial. Confocal and twophoton microscopy inspections at Microatlas implantation sites demonstrated growth of the recipient tissue inside the microgrids both with micro vascularization formation and collagen generation. In conclusion, the Microatlas guided in vivo a quantifiable localized reaction inside its microscaffold, both in terms of cell repopulation, collagen and capillary formation as a probable foreign body reaction.

Mesoscale Modeling of Al/Ni Composites

Granular composite formulations involving metal/metal [1,2] (intermetallic) reactions have been investigated for a number of applications. Interfaces between metallic particles have been attributed particular importance due to their ability to form localized hotspots, where the local temperature of the granular composite may significantly exceed the global temperature, leading to a localized reaction initiation that may initiate a global reaction.3 Understanding of the response of metal/metal granular composites to mechanical loading can be greatly facilitated by mesoscale modeling in which the underlying composite structure of the components is clearly resolved. For the Al/Ni composite discussed in this study, this involves explicitly resolving Al and Ni particles and intermetallic (Al/Al, Ni/Ni and Al/Ni) interfaces. In this work we utilize an idealized but realistic model for an Al/Ni composite using EOS, constitutive and interfacial models informed by molecular dynamics (MD) simulations. The Al/Ni microstructures are subjected to uniaxial compressive loading up to 30 GPa, shock loading up to 70 GPa (2000 m/s) and impact loading at 2000 m/s, and the mechanical and thermal response of the composite are analyzed.

Evolution of detonation formation initiated by a spatially distributed, transient energy source

Detonations usually form through either direct initiation or deflagration-to-detonation transition (DDT). In this work, a detonation initiation process is introduced that shows attributes from each of these two processes. Energy is deposited into a finite volume of fluid in an amount of time that is similar to the acoustic time scale of the heated fluid volume. Two-dimensional simulations of the reactive Euler equations are used to solve for the evolving detonation initiation process. The results show behaviour similar to both direct initiation and DDT. Localized reaction transients are shown to be intimately related to the appearance of a detonation. Thermomechanical concepts are used to provide physical interpretations of the computational results in terms of the interaction between compressibility phenomena on the acoustic time scale and localized, spatially resolved, chemical energy addition on a heat-addition time scale.

Fujita Exponent for a Nonlinear Degenerate Parabolic Equation with Localized Source

This paper is devoted to understand the blow-up properties of reaction-diffusion equations which combine a localized reaction term with nonlinear diffusion. In particular, we study the critical exponent of ap-Laplacian equation with a localized reaction. We obtain the Fujita exponentqcof the equation.