scholarly journals Modelling of filamentous phage-induced antibiotic tolerance of P.aeruginosa

2021 ◽  
Author(s):  
Maria van Rossem ◽  
Sandra Wilks ◽  
Malgosia Kaczmarek ◽  
Patrick R. Secor ◽  
Giampaolo D’Alessandro
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Continuum Model ◽  
Liquid Crystalline ◽  
Reactive Diffusion ◽  
Filamentous Phage ◽  
Antibiotic Tolerance ◽  
High Concentration ◽  
Diffusion In Porous Media ◽  
Good Agreement ◽  
The Continuum

AbstractFilamentous molecules tend to spontaneously assemble into liquid crystalline droplets with a tactoid morphology in the environments with the high concentration on non-adsorbing molecules. Tactoids of filamentous Pf bacteriophage, such as those produced by Pseudomonas aeruginosa, have been linked with increased antibiotic tolerance. We modelled this system and show that tactoids, composed of filamentous Pf virions, can lead to antibiotic tolerance by acting as an adsorptive diffusion barrier. The continuum model, reminiscent of descriptions of reactive diffusion in porous media, has been solved numerically and good agreement was found with the analytical results, obtained using a homogenisation approach. We find that the formation of tactoids significantly increases antibiotic diffusion times leading to stronger antibiotic resistance.

A New Uniform Continuum Modeling of Conductive and Radiative Heat Transfer in Nuclear Pebble Bed

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Hao Wu ◽  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
Shengyao Jiang
Keyword(s):  
Heat Transfer ◽  
Continuum Model ◽  
Internal Heat ◽  
Size Factor ◽  
Conductive Heat ◽  
Heat Sources ◽  
Pebble Bed ◽  
Internal Heat Sources ◽  
Good Agreement ◽  
The Continuum

Radiative and conductive heat transfer is fairly important in the nuclear pebble bed. A continuum model is proposed here to derive the effective thermal conductivity (ETC) of pebble bed. It is a physics-based equation determined by the temperature, number density, heat transfer coefficient, and the radial distribution function (RDF). Based on a concept of continuum, this model considers the conduction and thermal radiation in nuclear pebble bed through a uniform framework and the results are in good agreement with the existing model and correlations. It indicates that the local temperature in the radiation case without internal heat sources is determined by all possible surrounding pebbles weighted by a radiative kernel function. The discrete element method (DEM) packing results are in good agreement with the solution of the continuum model. Both the conductive and radiative continuum models converge to the heat conduction in continuum mechanics at size factor μ ≪ 1.

scholarly journals Development and stability of gyrotactic plumes in bioconvection

1999 ◽  
Vol 400 ◽  
pp. 1-31 ◽  
Author(s):  
S. GHORAI ◽  
N. A. HILL
Keyword(s):  
Continuum Model ◽  
Stokes Equations ◽  
Conservation Equation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Existence And Stability ◽  
Conservative Finite Difference Scheme ◽  
Micro Organisms ◽  
Good Agreement ◽  
The Continuum

Using the continuum model of Pedley, Hill & Kessler (1988) for bioconvection in a suspension of swimming, gyrotactic micro-organisms, we investigate the existence and stability of a two-dimensional plume in tall, narrow chambers with stress-free sidewalls. The system is governed by the Navier–Stokes equations for an incompressible fluid coupled with a micro-organism conservation equation. These equations are solved numerically using a conservative finite-difference scheme. In sufficiently deep chambers, the plume is always unstable to both varicose and meandering modes. A linear stability analysis for an infinitely long plume predicts the growth rates of these instabilities, explains the mechanisms, and is in good agreement with the numerical results.

Prediction of Rotating Blade Modes from Measured Nonrotating Modal Parameters

1991 ◽  
Vol 113 (4) ◽  
pp. 441-447 ◽  
Author(s):  
Yuan-Fang Chou ◽  
Wern-Cheng Yeh
Keyword(s):  
Eigenvalue Problem ◽  
Continuum Model ◽  
Modal Parameters ◽  
Elastic Solids ◽  
Rotating Speed ◽  
Linear Elastic ◽  
Rotating Blade ◽  
Modal Coordinates ◽  
Good Agreement ◽  
The Continuum

The method presented in this paper can predict the modal parameters of a rotating blade accurately via the easily measured modal parameters of the blade in the nonrotating state. The derivation of the eigenvalue problem in nonrotating modal coordinates is based on the continuum model of general linear elastic solids such that it can be applied to complex real structures. Therefore, the modal parameters for different rotating speeds can be found without testing the blade under each different rotating speed. Experiments were conducted to check the proposed method. The results showed that the predicted characteristics were in good agreement with the measured characteristics.

scholarly journals Hierarchical modeling of mechano-chemical dynamics of epithelial sheets across cells and tissue

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yoshifumi Asakura ◽  
Yohei Kondo ◽  
Kazuhiro Aoki ◽  
Honda Naoki
Keyword(s):  
Wound Healing ◽  
Cell Migration ◽  
Continuum Model ◽  
Tissue Level ◽  
Chemical Signals ◽  
Cellular Level ◽  
Mathematical Framework ◽  
Collective Cell Migration ◽  
The Continuum ◽  
Cell Cell

AbstractCollective cell migration is a fundamental process in embryonic development and tissue homeostasis. This is a macroscopic population-level phenomenon that emerges across hierarchy from microscopic cell-cell interactions; however, the underlying mechanism remains unclear. Here, we addressed this issue by focusing on epithelial collective cell migration, driven by the mechanical force regulated by chemical signals of traveling ERK activation waves, observed in wound healing. We propose a hierarchical mathematical framework for understanding how cells are orchestrated through mechanochemical cell-cell interaction. In this framework, we mathematically transformed a particle-based model at the cellular level into a continuum model at the tissue level. The continuum model described relationships between cell migration and mechanochemical variables, namely, ERK activity gradients, cell density, and velocity field, which could be compared with live-cell imaging data. Through numerical simulations, the continuum model recapitulated the ERK wave-induced collective cell migration in wound healing. We also numerically confirmed a consistency between these two models. Thus, our hierarchical approach offers a new theoretical platform to reveal a causality between macroscopic tissue-level and microscopic cellular-level phenomena. Furthermore, our model is also capable of deriving a theoretical insight on both of mechanical and chemical signals, in the causality of tissue and cellular dynamics.

THEORETICAL CALCULATION OF pKb VALUES FOR ANILINES AND SULFONAMIDE DRUGS IN AQUEOUS SOLUTION

2012 ◽  
Vol 11 (02) ◽  
pp. 283-295 ◽  
Author(s):  
BAHRAM GHALAMI-CHOOBAR ◽  
ALI GHIAMI-SHOMAMI ◽  
PARIA NIKPARSA
Keyword(s):  
Gas Phase ◽  
Continuum Model ◽  
Correlation Equation ◽  
Polarizable Continuum Model ◽  
Free Energies ◽  
Pcm Model ◽  
Solvation Models ◽  
Polarizable Continuum ◽  
Better Than ◽  
Good Agreement

In this work, calculations of p K b values have been performed for aniline and its substituted derivatives and sulfonamide drugs by using Gaussian 98 software package. Gas-phase energies were calculated with HF /6-31 G ** and B3LYP /6-31 G ** levels of theory. Free energies of solvation have been computed using the polarizable continuum model (PCM), conductor-like polarizable continuum model (CPCM) and the integral equation formalism-polarizable continuum model (IEFPCM) at the same levels which have been used for geometry determination in the gas-phase. The results show that the calculated p K b values using the B3LYP /6-31 G ** are better than those using the corresponding HF /6-31 G **. At first, the correlation equation was found to determine the p K b values of the investigated anilines. Then, this correlation equation was used to calculate the p K b values of the sulfonamide drugs. The results obtained indicate that the PCM model is a suitable solvation model for calculating p K b values in comparison to the other solvation models. For the investigated compounds a good agreement between the experimental and the calculated p K b values was also observed.

scholarly journals Effects of an autoinducer analogue on antibiotic tolerance in Pseudomonas aeruginosa

2017 ◽  
Author(s):  
Takashi Amoh ◽  
Keiji Murakami ◽  
Reiko Kariyama ◽  
Kenji Hori ◽  
Darija Viducic ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Tolerance

scholarly journals Formulation of 2D Graphene Deformation Based on Chiral-Tube Base Vectors

2010 ◽  
Vol 2010 ◽  
pp. 1-7
Author(s):  
Bohua Sun
Keyword(s):  
Molecular Dynamics ◽  
Shell Model ◽  
Continuum Model ◽  
Real Space ◽  
Honeycomb Lattice ◽  
Mechanical Behaviors ◽  
Future Studies ◽  
Physical Components ◽  
Intrinsic Feature ◽  
The Continuum

The intrinsic feature of graphene honeycomb lattice is defined by its chiral index (n,m), which can be taken into account when using molecular dynamics. However, how to introduce the index into the continuum model of graphene is still an open problem. The present manuscript adopts the continuum shell model with single director to describe the mechanical behaviors of graphene. In order to consider the intrinsic features of the graphene honeycomb lattice—chiral index (n,m), the chiral-tube vectors of graphene in real space have been used for construction of reference unit base vectors of the shell model; therefore, the formulations will contain the chiral index automatically, or in an explicit form in physical components. The results are quite useful for future studies of graphene mechanics.

Metallic solutions of the continuum model for conducting polymers

1994 ◽  
Vol 506 (2) ◽  
pp. 92-106
Author(s):  
H. W. Streitwolf ◽  
H. Puff
Keyword(s):  
Conducting Polymers ◽  
Continuum Model ◽  
The Continuum

On the Motion of Granular Materials Due to Shear

2000 ◽  
Author(s):  
Mehrdad Massoudi ◽  
Tran X. Phuoc
Keyword(s):  
Finite Difference ◽  
Granular Materials ◽  
Continuum Model ◽  
Theory Model ◽  
Governing Equations ◽  
Flat Plates ◽  
Material Parameters ◽  
Finite Difference Technique ◽  
Linear Differential ◽  
The Continuum

Abstract In this paper we study the flow of granular materials between two horisontal flat plates where the top plate is moving with a constant speed. The constitutive relation used for the stress is based on the continuum model proposed by Rajagopal and Massoudi (1990), where the material parameters are derived using the kinetic theory model proposed by Boyle and Massoudi (1990). The governing equations are non-dimensionalized and the resulting system of non-linear differential equations is solved numerically using finite difference technique.

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