Mathematical Simulation and Parametric Study of Flow of a Microbicidal Gel Between Elastic Boundaries

2011 ◽  
Author(s):  
Sunil Karri ◽  
Sarah L. Kieweg
Keyword(s):  
Active Ingredient ◽  
Flow Behavior ◽  
Great Promise ◽  
Delivery Vehicle ◽  
Polymeric Liquid ◽  
Vaginal Tissue ◽  
Tissue Properties ◽  
Sexually Transmitted ◽  
Polymeric Delivery ◽  
External Forces

Topical microbicides, the next generation prevention tool for HIV and other sexually transmitted pathogens, hold great promise if the target vaginal or rectal epithelium is coated effectively. A microbicide consists of an active ingredient within a polymeric delivery vehicle (e.g. polymeric liquid or ‘gel’). Most research in the field of microbicides has been limited to the development of an active ingredient and many microbicidal trails have failed in the past. Thus, there is a need to design a delivery vehicle that optimizes the efficacy of a microbicidal agent. The effectiveness of the gel depends on the gel’s rheological properties as well as the vaginal tissue properties, vaginal geometry, and external forces like gravity. A good design must take these factors in to consideration and a better understanding of the gel’s flow behavior over the epithelium is important before proceeding with clinical trials.

Instrument and Method for Visualizing and Characterizing Gravity-Induced Flow of Gels in an Environment Simulating Aspects of the Vaginal Lumen

2008 ◽  
Author(s):  
Vitaly O. Kheyfets ◽  
Sarah L. Kieweg
Keyword(s):  
Drug Delivery ◽  
Structural Integrity ◽  
Physical Barrier ◽  
Delivery Vehicle ◽  
Sexually Transmitted ◽  
Effective Barrier ◽  
Induced Flow ◽  
External Forces ◽  
Prevention Of Hiv ◽  
Specific Amount

Developing a mechanism capable of protecting the vaginal or rectal epithelium from sexually transmitted pathogens can be an effective tool in the prevention of HIV infection [1]. One such tool can come in the form of a microbicide gel, which provides a physical barrier and acts as a delivery vehicle for its active ingredient [1]. In order for the microbicide to be an effective barrier and delivery vehicle, it must have the capability to coat the epithelium for a specific amount of time and sustain its structural integrity under the influence of gravity and other perturbation forces. In addition, to be used as a drug delivery vehicle the microbicide must serve the following functions: coat the surface completely without leaving any of the surface exposed, stay on the surface while influenced by external forces such as gravity and squeezing, and must be able to contain potent concentrations of one or more active microbicidal ingredients.

Free Surface Coating Flows of Non-Newtonian Gels: 3-D Numerical Simulation of Gravity-Induced Flow

2007 ◽  
Author(s):  
Vitaly O. Kheyfets ◽  
Sarah L. Kieweg
Keyword(s):  
Structural Integrity ◽  
Physical Barrier ◽  
Delivery Vehicle ◽  
Coating Flows ◽  
Sexually Transmitted ◽  
Effective Barrier ◽  
Induced Flow ◽  
External Forces ◽  
Prevention Of Hiv ◽  
Specific Amount

Developing a mechanism capable of protecting the vaginal or rectal epithelium from sexually transmitted pathogens can be an effective tool in the prevention of HIV infection [1]. One such tool can come in the form of a microbicide gel, used to provide a physical barrier and act as a delivery vehicle for its active ingredient [1]. In order for the microbicide to be an effective barrier and delivery vehicle it must have the capability to coat the epithelium for a specific amount of time and sustain its structural integrity under the influence of gravity and other perturbation forces. In addition, to be used as a drug delivery vehicle the microbicide must serve the following functions: coat the surface completely without leaving any of the surface exposed, stay on the surface while influenced by external forces such as gravity and squeezing, and must be able to contain potent concentrations of one or more active microbicidal ingredients.

scholarly journals Mechanical Enhancement of Cytocompatible 3D Scaffolds, Consisting of Hydroxyapatite Nanocrystals and Natural Biomolecules, Through Physical Cross-Linking

2020 ◽  
Vol 7 (3) ◽  
pp. 96
Author(s):  
Despoina Brasinika ◽  
Elias P. Koumoulos ◽  
Kyriaki Kyriakidou ◽  
Eleni Gkartzou ◽  
Maria Kritikou ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Cell Attachment ◽  
Great Promise ◽  
Porous Network ◽  
Mechanical Reinforcement ◽  
Experimental Conditions ◽  
Tissue Properties ◽  
Human Osteosarcoma Cells ◽  
Hydroxyapatite Nanocrystals ◽  
Physical Crosslinking

Bioinspired scaffolds mimicking natural bone-tissue properties holds great promise in tissue engineering applications towards bone regeneration. Within this work, a way to reinforce mechanical behavior of bioinspired bone scaffolds was examined by applying a physical crosslinking method. Scaffolds consisted of hydroxyapatite nanocrystals, biomimetically synthesized in the presence of collagen and l-arginine. Scaffolds were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), microcomputed tomography, and nanoindentation. Results revealed scaffolds with bone-like nanostructure and composition, thus an inherent enhanced cytocompatibility. Evaluation of porosity proved the development of interconnected porous network with bimodal pore size distribution. Mechanical reinforcement was achieved through physical crosslinking with riboflavin irradiation, and nanoindentation tests indicated that within the experimental conditions of 45% humidity and 37 °C, photo-crosslinking led to an increase in the scaffold’s mechanical properties. Elastic modulus and hardness were augmented, and specifically elastic modulus values were doubled, approaching equivalent values of trabecular bone. Cytocompatibility of the scaffolds was assessed using MG63 human osteosarcoma cells. Cell viability was evaluated by double staining and MTT assay, while attachment and morphology were investigated by SEM. The results suggested that scaffolds provided a cell friendly environment with high levels of viability, thus supporting cell attachment, spreading and proliferation.

scholarly journals Applying biophysical models to understand the role of white matter in cognitive development

2018 ◽  
Author(s):  
Elizabeth Huber ◽  
Rafael Neto Henriques ◽  
Julia P. Owen ◽  
Ariel Rokem ◽  
Jason D. Yeatman
Keyword(s):  
White Matter ◽  
Cognitive Development ◽  
Diffusion Mri ◽  
Reading Skill ◽  
Great Promise ◽  
Model Parameters ◽  
Biophysical Modeling ◽  
Tissue Properties ◽  
Biophysical Models ◽  
Specific Tissue

AbstractDiffusion MRI (dMRI) holds great promise for illuminating the biological changes that underpin cognitive development. The diffusion of water molecules probes the cellular structure of brain tissue, and biophysical modeling of the diffusion signal can be used to make inferences about specific tissue properties that vary over development or predict cognitive performance. However, applying these models to study development requires that the parameters can be reliably estimated given the constraints of data collection with children. Here we collect repeated scans using a multi-shell diffusion MRI protocol in a group of children (ages 7-12) and use two popular biophysical models to characterize axonal properties. We first assess the scan-rescan reliability of model parameters and show that axon water faction can be reliably estimated from a relatively fast acquisition, without applying spatial smoothing or de-noising. We then investigate developmental changes in the white matter, and individual differences in white matter that correlate with reading skill. Specifically, we test the hypothesis that previously reported correlations between reading skill and diffusion anisotropy in the corpus callosum reflect increased axon density in poor readers. Both models support this interpretation, highlighting the utility of biophysical models for testing specific hypotheses about cognitive development.

Design and Fabrication of Biodegradable Polymer Devices to Engineer Tubular Tissues

1994 ◽  
Vol 3 (2) ◽  
pp. 203-210 ◽  
Author(s):  
D. J. Mooney ◽  
G. Organ ◽  
J. P. Vacanti ◽  
R. Langer
Keyword(s):  
Cell Delivery ◽  
Intestinal Epithelial ◽  
Delivery Vehicle ◽  
Porous Films ◽  
Polymer Devices ◽  
Epithelial Cell Layer ◽  
Polymeric Delivery ◽  
Specific Tissue

Engineering new tissues by transplanting cells on polymeric delivery devices is one approach to alleviate the vast shortage of donor tissue. However, it will be necessary to fabricate cell delivery devices that deliver cells to a given location and promote the formation of specific tissue structures from the transplanted cells and the host tissue. This report describes the design and fabrication of a polymeric device for guiding the development of tubular vascularized tissues, which may be useful for engineering a variety of tissues including intestine, blood vessels, tracheas, and ureters. Porous films of poly (d, l-lactic-co-glycolic acid) have been formed and fabricated into tubes capable of resisting compressional forces in vitro and in vivo. These devices promote the ingrowth of fibrovascular tissue following implantation into recipient animals, resulting in a vascularized, tubular tissue. To investigate the utility of these devices as cell delivery devices, enterocytes (intestinal epithelial cells) were seeded onto the devices in vitro. Enterocytes were found to attach to these devices and form an organized epithelial cell layer. These results suggest that these devices may be an appropriate delivery vehicle for transplanting cells and engineering new tubular tissues.

scholarly journals Variable Curvature Modelling Method of Continuum Robots with Contraints

2021 ◽  
Author(s):  
Peng Chen ◽  
Yi Yu ◽  
Yuwang Liu
Keyword(s):  
Degrees Of Freedom ◽  
Human Robot Interaction ◽  
Great Promise ◽  
Complex Deformation ◽  
Continuum Robots ◽  
Mechanics Model ◽  
Variable Curvature ◽  
Main Challenge ◽  
High Flexibility ◽  
External Forces

Abstract The inherent compliance of continuum robots holds great promise in the fields of soft manipulation and safe human-robot interaction. This compliance reduces the risk of damage to the manipulated object and the surroundings. However, continuum robots have theoretically infinite degrees of freedom, and this high flexibility usually leads to complex deformations with external forces and positional constraints. How to describe this complex deformation is the main challenge for modelling continuum robots. In this study, we investigated a novel variable curvature modeling method for continuum robots, considering external forces and positional constraints. The robot configuration curve is described by the developed mechanics model, and then the robot is fitted to the curve. To validate the model, a 10-section continuum robot prototype with a length of 1 m was developed. The ability of the robot to reach the target points and track complex trajectories with load verified the feasibility and accuracy of the model. The ratio of the average position error of the robot endpoint to the robot length was less than 2.38%. This work may serve a new perspective for design analysis and motion control of continuum robots.

Thin Film Flow of Polymeric Anti-HIV Microbicides: Comparison of 3-D Numerical and Experimental Simulations

2011 ◽  
Author(s):  
Vitaly O. Kheyfets ◽  
Sarah L. Kieweg
Keyword(s):  
Hiv Transmission ◽  
Initial Conditions ◽  
Lateral Spreading ◽  
Unprotected Sex ◽  
Thin Film Flow ◽  
Delivery Vehicle ◽  
Topical Formulation ◽  
Polymeric Liquid ◽  
Pharmaceutical Agent ◽  
Effective Delivery

In 2008, approximately 33.4 million people were living with HIV worldwide[1]. The rate of infection increases by about 5 million people per year[2], with a significant portion resulting from unprotected sex. A microbicide is a topical formulation that consists of a pharmaceutical agent suspended in a delivery vehicle (e.g. a polymeric liquid also called a “microbicide gel”), and could be a potential tool for preventing HIV transmission during intercourse. The vehicle itself can act as a physical barrier and, if designed with ideal physicochemical properties, might eliminate the need for a pharmaceutical agent altogether. In fact, a vehicle’s ability to coat the epithelium has been singled out as a crucial variable, which might dictate the microbicide’s efficacy[3]. Our overall objective is to develop an effective delivery vehicle that is capable of coating the vaginal epithelium under the influence of gravity, shearing, and compressive forces. The objective of this study is to numerically simulate the evolution of the 3-D free surface of a non-Newtonian fluid spreading under the influence of gravity. In addition, we aim to compare the spreading characteristics of the numerical model with experimental data, while incorporating similar initial conditions. Here, we present the advantages of accounting for lateral spreading in the numerical simulation.

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