Marco Lauricella

Different regimes of the uniaxial elongation of electrically charged viscoelastic jets due to dissipative air drag

Abstract We investigate the effects of dissipative air drag on the dynamics of electrified jets in the initial stage of the electrospinning process. The main idea is to use a Brownian noise to model air drag effects on the uniaxial elongation of the jets. The developed numerical model is used to probe the dynamics of electrified polymer jets at different conditions of air drag force, showing that the dynamics of the charged jet is strongly biased by the presence of air drag forces. This study provides prospective beneficial implications for improving forthcoming electrospinning experiments.

JETSPIN: A specific-purpose open-source software for simulations of nanofiber electrospinning ☆

Abstract We present the open-source computer program JETSPIN, specifically designed to simulate the electrospinning process of nanofibers. Its capabilities are shown with proper reference to the underlying model, as well as a description of the relevant input variables and associated test-case simulations. The various interactions included in the electrospinning model implemented in JETSPIN are discussed in detail. The code is designed to exploit different computational architectures, from single to parallel processor workstations. This paper provides an overview of JETSPIN, focusing primarily on its structure, parallel implementations, functionality, performance, and availability. Program summary Program title : JETSPIN Catalogue identifier : AEXQ_v1_0 Program summary URL : http://cpc.cs.qub.ac.uk/summaries/AEXQ_v1_0.html Program obtainable from : CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions : Open Software License v. 3.0 No. of lines in distributed program, including test data, etc. : 12996 No. of bytes in distributed program, including test data, etc. : 120019 Distribution format : tar.gz Programming language : Fortran 90. Computer : All Linux based workstations and parallel supercomputers, Windows and Apple machines. Operating system : Linux, OS X, Windows. Has the code been vectorized or parallelized? : Code is parallelized RAM : 2+ Gigabytes Classification : 4.3, 7.7, 10, 12. Nature of problem : Dynamics of the electrospinning process to produce nanofibers Solution method : Numerical solutions to the equations of motion of a Lagrangian discrete model Running time : A few seconds up to several hours, depending on size of the underlying jet representation.

Mechanistic modelling of drug release from multi-layer capsules

We propose a novel in silico model for computing drug release from multi-layer capsules. The diffusion problem in such heterogeneous layer-by-layer composite medium is described by a system of coupled partial differential equations, which we solve analytically using separation of variables. In addition to the conventional partitioning and mass transfer interlayer conditions, we consider a surface finite mass transfer resistance, which corresponds to the case of a coated capsule. The drug concentration in the core and through all the layers, as well as in the external release medium, is given in terms of a Fourier series that we compute numerically to describe and characterize the drug release mechanism.

Nonlinear Langevin model for the early-stage dynamics of electrospinning jets

We present a nonlinear Langevin model to investigate the early-stage dynamics of electrified polymer jets in electrospinning experiments. In particular, we study the effects of air drag force on the uniaxial elongation of the charged jet, right after ejection from the nozzle. Numerical simulations show that the elongation of the jet filament close to the injection point is significantly affected by the nonlinear drag exerted by the surrounding air. These results provide useful insights for the optimal design of current and future electrospinning experiments.

Three-Dimensional Model for Electrospinning Processes in Controlled Gas Counterflow

We study the effects of a controlled gas flow on the dynamics of electrified jets in the electrospinning process. The main idea is to model the air drag effects of the gas flow by using a nonlinear Langevin-like approach. The model is employed to investigate the dynamics of electrified polymer jets at different conditions of air drag force, showing that a controlled gas counterflow can lead to a decrease of the average diameter of electrospun fibers, and potentially to an improvement of the quality of electrospun products. We probe the influence of air drag effects on the bending instabilities of the jet and on its angular fluctuations during the process. The insights provided by this study might prove useful for the design of future electrospinning experiments and polymer nanofiber materials.

Effects of orthogonal rotating electric fields on electrospinning process

Electrospinning is a nanotechnology process whereby an external electric field is used to accelerate and stretch a charged polymer jet, so as to produce fibers with nanoscale diameters. In quest of a further reduction in the cross section of electrified jets hence of a better control on the morphology of the resulting electrospun fibers, we explore the effects of an external rotating electric field orthogonal to the jet direction. Through extensive particle simulations, it is shown that by a proper tuning of the electric field amplitude and frequency, a reduction of up to a

Iontophoretic transdermal drug delivery: a multi-layered approach

30 \%

Dynamic mesh refinement for discrete models of jet electro-hydrodynamics

in the aforementioned radius can be obtained, thereby opening new perspectives in the design of future ultra-thin electrospun fibres. Applications can be envisaged in the fields of nanophotonic components as well as for designing new and improved filtration materials.

Lattice propagators and Haldane-Wu fractional statistics

We present a multi-layer mathematical model to describe the transdermal drug release from an iontophoretic system. The Nernst-Planck equation describes the basic convection-diffusion process, with the electric potential obtained by solving the Laplaces equation. These equations are complemented with suitable interface and boundary conditions in a multi-domain. The stability of the mathematical problem is discussed in different scenarios and a finite-difference method is used to solve the coupled system. Numerical experiments are included to illustrate the drug dynamics under different conditions.

Effects of nanoparticles on the dynamic morphology of electrified jets

Nowadays, several models of unidimensional fluid jets exploit discrete element methods. In some cases, as for models aiming at describing the electrospinning nanofabrication process of polymer fibers, discrete element methods suffer a non constant resolution of the jet representation. We develop a dynamic mesh-refinement method for the numerical study of the electro-hydrodynamic behavior of charged jets using discrete element methods. To this purpose, we import ideas and techniques from the string method originally developed in the framework of free-energy landscape simulations. The mesh-refined discrete element method is demonstrated for the case of electrospinning applications.