Neuromechanical characterization of brain damage in response to head impact and pathological changes

Abstract

Traumatic injuries to the central nervous system (brain and spinal cord) have received special attention because of their devastating socio-economical cost. Functional and morphological damage of brain is the most intricate phenomenon in the body. It is the major cause of disability and death. The paper involves constitutive modeling and computational investigations towards an understanding the mechanical and functional failure of brain due to the traumatic (head impact) and pathological (brain tumor) events within the framework of continuum damage mechanics of brain. Development of brain damage has been analyzed at the organ scale with the whole brain, tissue scale with white and gray tissue, and cellular scale with an individual neuron. The mechanisms of neurodamage growth have been specified in response to head impact and brain tumor. Swelling due to electrical activity of nervous cells under electrophysiological impairments, and elastoplastic deformation and creep under mechanical loading of the brain have been analyzed. The constitutive laws of neuromechanical behavior at large strains have been developed, and tension-compression asymmetry, as well as, initial anisotropy of brain tissue was taken into account. Implementation details of the integrated neuromechanical constitutive model including the Hodgkin-Huxley model for voltage into ABAQUS, ANSYS and in-house developed software have been considered in a form of the computer-based structural modeling tools for analyzing stress distributions over time in healthy and diseased brains, for neurodamage analysis and for lifetime predictions of diseased brains. The outcome of this analysis will be how the neuromechanical simulations applied to the head impact and brain tumor therapies may assist medical specialists with their decisions during planning and application of medical surgeries.

Quantum, molecular and continuum modeling in nonlinear mechanics of viruses

“…The next source of tension elements is the chromatin-genome association that is highly extensible in the attempt to return to a state of maximal entropy [147]. Thus, viruses belong to a broad class of natural and artificial materials with different behavior under tension, and compression [1,2,3,27,61,148,149,150,151,152,153,154,155,156,157,158,159,160]. Second, the 29  shells are approximately two times stiffer along the short axis (particle lying on its side) than along the long one (upright particle).…”

“…In the past reviews [1,2,3,4], we focused the attention of readers on the nonlinear biomechanics of hard and soft tissues of living organisms. Due to the appearance of a number of important research questions [5] related to the recent outbreak of the 2019 novel coronavirus SARS-CoV-2 and fast spread of the disease COVID-19 around the world, we decided to present in this overview the applications of nonlinear mechanics to such biological structures as viruses.…”