A novel modelling and simulation approach for the hindered mobility of charged particles in biological hydrogels

This article presents a novel computational model to study the selective filtering of biological hydrogels due to the surface charge and size of diffusing particles. It is the first model that includes the random three-dimensional fibre orientation and connectivity of the biopolymer network and that accounts for elastic deformations of the fibres by means of beam theory. As a key component of the model, novel formulations are proposed both for the electrostatic and repulsive steric interactions between a spherical particle and a beam. In addition to providing a thorough validation of the model, the presented computational studies yield new insights into the underlying mechanisms of hindered particle mobility, especially regarding the influence of the aforementioned aspects that are unique to this model. It is found that the precise distribution of fibre and thus charge agglomerations in the network have a crucial influence on the mobility of oppositely charged particles and gives rise to distinct motion patterns. Considering the high practical significance for instance with respect to targeted drug release or infection defence, the provided proof of concept motivates further advances of the model towards a truly predictive computational tool that allows a case- and patient-specific assessment for real (biological) systems.

Download Full-text

Numerical computation of blood flow for a patient-specific hemodialysis shunt model

Japan Journal of Industrial and Applied Mathematics ◽

10.1007/s13160-021-00469-9 ◽

2021 ◽

Author(s):

Surabhi Rathore ◽

Tomoki Uda ◽

Viet Q. H. Huynh ◽

Hiroshi Suito ◽

Toshitaka Watanabe ◽

...

Keyword(s):

Stokes Equations ◽

Three Dimensional ◽

Arteriovenous Shunt ◽

Navier Stokes ◽

Patient Specific ◽

Stabilized Finite Element ◽

Computed Tomography Scanning ◽

Outflow Boundary ◽

Stage Renal Disease ◽

End Stage

AbstractHemodialysis procedure is usually advisable for end-stage renal disease patients. This study is aimed at computational investigation of hemodynamical characteristics in three-dimensional arteriovenous shunt for hemodialysis, for which computed tomography scanning and phase-contrast magnetic resonance imaging are used. Several hemodynamical characteristics are presented and discussed depending on the patient-specific morphology and flow conditions including regurgitating flow from the distal artery caused by the construction of the arteriovenous shunt. A simple backflow prevention technique at an outflow boundary is presented, with stabilized finite element approaches for incompressible Navier–Stokes equations.

Download Full-text

Application of subject-specific adaptive mechanical loading for bone healing in a mouse tail vertebral defect

Scientific Reports ◽

10.1038/s41598-021-81132-8 ◽

2021 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Angad Malhotra ◽

Matthias Walle ◽

Graeme R. Paul ◽

Gisela A. Kuhn ◽

Ralph Müller

Keyword(s):

Mechanical Loading ◽

Bone Defect ◽

Bone Healing ◽

Three Dimensional ◽

Patient Specific ◽

Dependent Manner ◽

Micro Computed Tomography ◽

Computed Tomography Images ◽

Bone Defect Healing ◽

Subject Specific

AbstractMethods to repair bone defects arising from trauma, resection, or disease, continue to be sought after. Cyclic mechanical loading is well established to influence bone (re)modelling activity, in which bone formation and resorption are correlated to micro-scale strain. Based on this, the application of mechanical stimulation across a bone defect could improve healing. However, if ignoring the mechanical integrity of defected bone, loading regimes have a high potential to either cause damage or be ineffective. This study explores real-time finite element (rtFE) methods that use three-dimensional structural analyses from micro-computed tomography images to estimate effective peak cyclic loads in a subject-specific and time-dependent manner. It demonstrates the concept in a cyclically loaded mouse caudal vertebral bone defect model. Using rtFE analysis combined with adaptive mechanical loading, mouse bone healing was significantly improved over non-loaded controls, with no incidence of vertebral fractures. Such rtFE-driven adaptive loading regimes demonstrated here could be relevant to clinical bone defect healing scenarios, where mechanical loading can become patient-specific and more efficacious. This is achieved by accounting for initial bone defect conditions and spatio-temporal healing, both being factors that are always unique to the patient.

Download Full-text

Kidney organoid systems for studies of immune-mediated kidney diseases: challenges and opportunities

Cell and Tissue Research ◽

10.1007/s00441-021-03499-4 ◽

2021 ◽

Author(s):

Melissa C. Stein ◽

Fabian Braun ◽

Christian F. Krebs ◽

Madeleine J. Bunders

Keyword(s):

Kidney Diseases ◽

Three Dimensional ◽

Renal Tissue ◽

Chronic Kidney Diseases ◽

Immune Mediated ◽

Primary Epithelial Cell ◽

Challenges And Opportunities ◽

Underlying Mechanisms ◽

Global Population

AbstractAcute and chronic kidney diseases are major contributors to morbidity and mortality in the global population. Many nephropathies are considered to be immune-mediated with dysregulated immune responses playing an important role in the pathogenesis. At present, targeted approaches for many kidney diseases are still lacking, as the underlying mechanisms remain insufficiently understood. With the recent development of organoids—a three-dimensional, multicellular culture system, which recapitulates important aspects of human tissues—new opportunities to investigate interactions between renal cells and immune cells in the pathogenesis of kidney diseases arise. To date, kidney organoid systems, which reflect the structure and closer resemble critical aspects of the organ, have been established. Here, we highlight the recent advances in the development of kidney organoid models, including pluripotent stem cell-derived kidney organoids and primary epithelial cell-based tubuloids. The employment and further required advances of current organoid models are discussed to investigate the role of the immune system in renal tissue development, regeneration, and inflammation to identify targets for the development of novel therapeutic approaches of immune-mediated kidney diseases.

Download Full-text

Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis

Scientific Reports ◽

10.1038/s41598-021-93821-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Niksa Mohammadi Bagheri ◽

Mahmoud Kadkhodaei ◽

Shiva Pirhadi ◽

Peiman Mosaddegh

Keyword(s):

Clinical Data ◽

Three Dimensional ◽

Element Model ◽

Von Mises Stress ◽

Patient Specific ◽

Average Error ◽

Constant Thickness ◽

Arc Length ◽

Implementation Techniques ◽

Von Mises

AbstractThe implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outcomes. Thus, this study aimed to investigate the influence of ICRS implementation techniques and design on the postoperative biomechanical state and keratometry results. The clinical data of three patients with different stages and patterns of keratoconus were assessed to develop a three-dimensional (3D) patient-specific finite-element model (FEM) of the keratoconic cornea. For each patient, the exact surgery procedure definitions were interpreted in the step-by-step FEM. Then, seven surgical scenarios, including different ICRS designs (complete and incomplete segment), with two surgical implementation methods (tunnel incision and lamellar pocket cut), were simulated. The pre- and postoperative predicted results of FEM were validated with the corresponding clinical data. For the pre- and postoperative results, the average error of 0.4% and 3.7% for the mean keratometry value ($$\text {K}_{\text{mean}}$$ K mean ) were predicted. Furthermore, the difference in induced flattening effects was negligible for three ICRS types (KeraRing segment with arc-length of 355, 320, and two separate 160) of equal thickness. In contrast, the single and double progressive thickness of KeraRing 160 caused a significantly lower flattening effect compared to the same type with constant thickness. The observations indicated that the greater the segment thickness and arc-length, the lower the induced mean keratometry values. While the application of the tunnel incision method resulted in a lower $$\text {K}_{\text{mean}}$$ K mean value for moderate and advanced KC, the induced maximum Von Mises stress on the postoperative cornea exceeded the induced maximum stress on the cornea more than two to five times compared to the pocket incision and the preoperative state of the cornea. In particular, an asymmetric regional Von Mises stress on the corneal surface was generated with a progressive ICRS thickness. These findings could be an early biomechanical sign for a later corneal instability and ICRS migration. The developed methodology provided a platform to personalize ICRS refractive surgery with regard to the patient’s keratoconus stage in order to facilitate the efficiency and biomechanical stability of the surgery.

Download Full-text

Multimedia Teaching Platform for Urban Planning Utilizing 3D Technology

International Journal of Emerging Technologies in Learning (iJET) ◽

10.3991/ijet.v13i04.8259 ◽

2018 ◽

Vol 13 (04) ◽

pp. 187 ◽

Cited By ~ 1

Author(s):

Xuhui Wang ◽

Quan Zhang ◽

Yanyi Chen ◽

Shihao Liang

Keyword(s):

High Speed ◽

Three Dimensional ◽

Practical Significance ◽

Master Plan ◽

3D Technology ◽

Technology Application ◽

Teaching Platform ◽

Multimedia Teaching ◽

Effect Difference ◽

Urban Rural

In recent years, 3D technology based on computer and internet has achieved high-speed development. People have realized direct and stereo observation of realistic world. Three-dimensional and visualized characteristics of the technology fit well with the teaching objective of college architecture specialized courses. Thus, 3D model has profound practical significance for its application in urban green space system and urban rural overall planning. With “urban-rural master plan” as experimental course, through design of “urban-rural master plan” multimedia teaching platform based on 3D technology and practice of the teaching platform in course teaching, this article has applied control experiment method and statistical method to make comparative analysis on the teaching effect difference of multimedia teaching platform based on 3D technology application in “urban-rural master plan” as experimental course so as to provide theoretical and data support for 3D technology application in “urban-rural master plan” and other college architecture major courses.

Download Full-text

Mass transfer and blood flow in a patient-specific three-dimensional Willis circle

International Communications in Heat and Mass Transfer ◽

10.1016/j.icheatmasstransfer.2021.105369 ◽

2021 ◽

Vol 126 ◽

pp. 105369

Author(s):

Alessio Pignani ◽

Ivan Di Venuta ◽

Andrea Boghi ◽

Fabio Gori

Keyword(s):

Mass Transfer ◽

Blood Flow ◽

Three Dimensional ◽

Patient Specific

Download Full-text

A flexible framework for sequential estimation of model parameters in computational hemodynamics

Advanced Modeling and Simulation in Engineering Sciences ◽

10.1186/s40323-020-00186-x ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Christopher J. Arthurs ◽

Nan Xiao ◽

Philippe Moireau ◽

Tobias Schaeffter ◽

C. Alberto Figueroa

Keyword(s):

Unscented Kalman Filter ◽

Three Dimensional ◽

Synthetic Data ◽

Sequential Estimation ◽

Wall Material ◽

Patient Specific ◽

Model Parameters ◽

Computational Framework ◽

Lumped Parameter ◽

Estimation Of Model Parameters

AbstractA major challenge in constructing three dimensional patient specific hemodynamic models is the calibration of model parameters to match patient data on flow, pressure, wall motion, etc. acquired in the clinic. Current workflows are manual and time-consuming. This work presents a flexible computational framework for model parameter estimation in cardiovascular flows that relies on the following fundamental contributions. (i) A Reduced-Order Unscented Kalman Filter (ROUKF) model for data assimilation for wall material and simple lumped parameter network (LPN) boundary condition model parameters. (ii) A constrained least squares augmentation (ROUKF-CLS) for more complex LPNs. (iii) A “Netlist” implementation, supporting easy filtering of parameters in such complex LPNs. The ROUKF algorithm is demonstrated using non-invasive patient-specific data on anatomy, flow and pressure from a healthy volunteer. The ROUKF-CLS algorithm is demonstrated using synthetic data on a coronary LPN. The methods described in this paper have been implemented as part of the CRIMSON hemodynamics software package.

Download Full-text