| Riccardo Sacco, Dipartimento di Matematica, Politecnico Milano, Italy | 140 | Riccardo Sacco, Dipartimento di Matematica, Politecnico Milano, Italy | Zoom | <p><strong>​Mode:</strong> Virtual (<a href="https://udel.zoom.us/j/98758622578" target="_blank">Zoom​</a>)<br><strong></strong></p><b>Speaker: </b>Riccardo Sacco, Dipartimento di Matematica, Politecnico Milano, Italy (riccardo.sacco@polimi.it)<br><br><b>Title: </b>Modeling and Simulation of Retinal Neuron Depolarization Using Organic Polymer Nanoparticles<br><br><b>Abstract: </b>In this talk we formulate and numerically investigate a model of the process of retinal neuron depolarization driven by a retinal prosthesis made of organic polymer nanoparticles (NP).<br>The model consists of a nonlinearly coupled system of elliptic partial differential equations for the electric potential, the number densities of charge carriers photogenerated in the NP bulk and the molar densities of ions moving by electrodiffusion in the aqueous solution surrounding the NP.<br><br><div>The nonlinear coupling among the dependent variables throughout the computational domain is mathematically expressed by nonlinear transmission conditions across the interfaces separating the aqueous solution from NP and retinal neuron. The proposed model is solved in stationary conditions and in one spatial dimension by means of a solution map which is a modification of the Gummel Decoupled algorithm conventionally used in inorganic semiconductor simulation.  System discretization is conducted using the Finite Element Method, with stabilization terms to prevent spurious unphysical oscillations in the electric potential and ensure positivity of carrier and ion concentrations.<br>Model predictions suggest that the combined effect of NP polarization and resistivity of the NP-neuron interface results in neuron depolarization and supports the efficacy of organic NPs in the design and development of retinal prostheses.</div><div><br></div><div>This work is in collaboration with Greta Chiaravallii (<a href="mailto:greta.chiaravalli@polimi.it">greta.chiaravalli@polimi.it</a>) and Guglielmo Lanzani (<a href="mailto:Guglielmo.lanzani@iit.it">guglielmo.lanzani@iit.it</a>), Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy, and Department of Physics, Politecnico di Milano, Milano, Italy.<br></div> | 12/10/2021 3:10:00 PM | 12/10/2021 3:55:00 PM | | |
| Binan Gu, Department of Mathematical Sciences, New Jersey Institute of Technology | 139 | Binan Gu, Department of Mathematical Sciences, New Jersey Institute of Technology | 336 Ewing Hall and on Zoom | <p><strong>​Mode:</strong> In-person and <a href="https://udel.zoom.us/j/98758622578" target="_blank">Zoom​</a><br><strong></strong></p><p><strong>Title:</strong> Graphical Representation of Membrane Filtration</p><p><strong>Abstract:</strong> We study the performance of a membrane filter represented by a pore network based on two criteria: 1) total volumetric throughput and 2) accumulated foulant concentration. We first formulate the governing equations of fluid flow on a general network, and we model adsorptive fouling by imposing an advection equation on each pore (edge) and imposing conservation of fluid and foulant volumetric flow rate at each pore junction (vertex), which yields a system of partial differential equations. We study the influence of three geometric network parameters on filter performance: 1) average number of neighbors of each vertex; 2) initial total void volume of the pore network; and 3) tortuosity of the network. We find that total volumetric throughput has a stronger dependence on the initial void volume than on average number of neighbors. Tortuosity turns out to be a universal parameter, leading to almost perfect collapse of all results for a variety of different network architectures. In particular, the accumulated foulant concentration shows an exponential decay as tortuosity increases.​<br></p> | 12/3/2021 3:10:00 PM | 12/3/2021 3:55:00 PM | | |
| Riku Paananen, Helsinki Eye Lab, Ophthalmology, University of Helsinki and Helsinki University Hospital | 138 | Riku Paananen, Helsinki Eye Lab, Ophthalmology, University of Helsinki and Helsinki University Hospital | Zoom | <b>​Mode: </b>Virtual (<a href="https://udel.zoom.us/j/98758622578" target="_blank">Zoom​</a>)<br><b><br></b><div><b>Title: </b>Insights into lipid structures from molecular dynamics simulations<br><b><br></b></div><div><b>Abstract:</b> Self-assembly of lipids gives rise to various structures such as micelles, bilayers, vesicles, monolayers, and other more complex systems. These lipid structures play a key role in various biological processes, such as acting as structural components of cells, or forming protective barriers in the skin or the surface of the eye. Molecular dynamics (MD) simulations are a powerful computational tool in studying such lipid systems, since they can provide atomic-level details, which are often difficult to access via experimental techniques.<br><br>This talk provides a general introduction into studying lipid systems with MD simulations, followed by specific examples of how these techniques have been utilized to study the different questions related to biological systems. Often the best results can be obtained when MD simulations are combined with experimental approaches to provide a more in-depth view of the system. Examples include utilizing MD simulations to study tear film lipid layer structure and evaporation resistance, lateral heterogeneity in lung surfactant monolayers, and nanoscale structure of cellular membranes.<br></div> | 11/12/2021 3:10:00 PM | 11/12/2021 3:55:00 PM | | |
| Hangjie Ji, Department of Mathematics, North Carolina State University | 137 | Hangjie Ji, Department of Mathematics, North Carolina State University | Zoom | <p><strong>​Mode:</strong> <a href="https://udel.zoom.us/j/98758622578" target="_blank" title="Zoom room">Zoom​</a> Only (pass code needed, contact organizer)<br><strong></strong><span class="wrap-text"><strong>Title:</strong> Dynamics of thin liquid films on vertical cylindrical fibers<br><strong>Abstract:</strong> Thin
liquid films flowing down vertical fibers spontaneously exhibit complex
interfacial dynamics, creating irregular wavy patterns and traveling
liquid droplets. Such dynamics is a fundamental component in many
engineering applications, including mass and heat exchangers for thermal
desalination and water vapor and particle capture. Recent experiments
present a wealth of new dynamics that illustrate the need for more
advanced theory. In this talk, I will first present a study of a full
lubrication model that includes slip boundary conditions, nonlinear
curvature terms, and a film stabilization term. This model better
explains the observed velocity and stability of traveling droplets in
experiments and their transition to isolated droplets. Next, I will
discuss thermally-driven droplet coalescence induced by an inhomogeneous
temperature field along the fiber. To characterize the flow regime
transition caused by varying nozzle geometries, I will also present a
study of a weighted residual integral boundary-layer model that
incorporates moderate inertia. Analytical results on traveling wave
solutions to the fiber coating models will also be discussed.</span><br></p> | 10/29/2021 2:10:00 PM | 10/29/2021 2:55:00 PM | | |
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