Modelling mass diffusion for a multi-layer sphere immersed in a semi-infinite medium: application to drug delivery

We present a general mechanistic model of mass diffusion for a composite sphere placed in a large ambient medium. The multi-layer problem is described by a system of diffusion equations coupled via interlayer boundary conditions such as those imposing a finite mass resistance at the extemal surface of the sphere. While the work is applicable to the generic problem of heat or mass transfer in a multi-layer sphere, the analysis and results are presented in the context of drug kinetics for desorbing and absorbing spherical microcapsules.

Design and testing of hydrophobic core/hydrophilic shell nano/micro particles for drug-eluting stent coating

In this study, we designed a novel drug-eluting coating for vascular implants consisting of a core coating of the anti-proliferative drug docetaxel ( DTX) and a shell coating of the platelet glycoprotein IIb/IIIa receptor monoclonal antibody SZ-21. The core/shell structure was sprayed onto the surface of 316L stainless steel stents using a coaxial electrospray process with the aim of creating a coating that exhibited a differential release of the two drugs. The prepared stents displayed a uniform coating consisting of nano/micro particles.

Mathematical models and methods in drug delivery systems

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 also the case of finite mass transfer resistance, which corresponds to the case of a coated capsule.

Mathematically modelling the stability of solid dispersions in storage

Many drugs currently on the market or in development are poorly water-soluble. This presents a serious challenge to the pharmaceutical industry because orally delivered drugs that are poorly soluble tend to pass through the gastrointestinal tract before they can fully dissolve, leading to poor drug bioavailability. One strategy to improve drug solubility is to use a solid dispersion. A solid dispersion typically consists of a hydrophobic drug embedded in a hydrophilic polymer matrix.

CHANGES OF RESTING-STATE OSCILLATORY NETWORK DYNAMICS AFTER MOTOR LEARNING: A M.E.G. DEVELOPMENTAL STUDY

Introduction : Neuroimaging studies have shown that in adults, the motor learning induced alterations of the functional connectivity assessed during Resting State Networks (RSN) is age-dependent (Mary et al., 2017). Motor learning relies on the build-up of new sensori-motor representations, which has been studied using the bar-man task in adults (Barlaam, Vaugoyeau, Fortin, Assaiante, & Schmitz, 2016; Paulignan, Dufossé, Hugon, & Massion, 1989) and in children (Schmitz et al, 2002).. The aim of this study was to investigate the modulations of functional connectivity after a motor learn

Models in fish population dynamics

The use of population dynamics models is essential to provide assessment of the fish abundance and advice on management and strategies for the fisheries. The stock-recruitment curve define the relationship between the spawning stock and the subsequent recruitment, describing nature's regulation of population size, whether or not the populations are being exploited. The two classical relations, established by Ricker and Shepherd, are: R (S) = b1S e-b2S , b1, b2 > 0 (4) R (S) = S b1 + b2Sb3 , b1, b2, b3 > 0 where S is the spawning stock and R is the recruitment, i.e.

Source-level MEG analysis of the intrinsic temporal properties of neural networks in Schizophrenia

Biological systems tend to display complex behaviour with a power-law (1/f - like) distribution. In the brain, this translates into neural activity that exhibits scale-free, temporal or spatial, properties (He, 2014). Scaleinvariance has been observed across different neuroimaging modalities and conditions (Linkenkaer-Hansen, 2001; He, 2014; Ciuciu et al. 2012). Beyond previously used features, recent electrophysiology studies have shown the presence of long-range temporal correlations (LRTCs) in the amplitude dynamics of alpha and beta oscillations (Nikulin et al. 2012).