Journal of Biomechanical Engineering This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Differences in Trabecular Microarchitecture and Simplified Boundary Conditions Limit the Accuracy of Quantitative Computed Tomography-Based Finite Element Models of Vertebral Failure
This study's goal was to elucidate failure processes in the lumbar vertebra and to assess the accuracy of quantitative computed tomography (QCT)-based finite element (FE) simulations of these processes. Following QCT scanning, spine segments (n  = 27) consisting of L1 with adjacent intervertebral disks and neighboring endplates of T12 and L2 were compressed axially in a stepwise manner. A microcomputed tomography scan was performed at each loading step. The resulting time-lapse series of images was analyzed using digital volume correla tion (DVC) to quantify deformations throughout the vertebral body. While some divers...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Dynamic Hydrostatic Pressure Regulates Nucleus Pulposus Phenotypic Expression and Metabolism in a Cell Density-Dependent Manner
This study examined the effects of physiological magnitudes of HP loading applied to bovine NP cells encapsulated within three-dimensional (3D) alginate beads. Study 1: seeding density (1 M/mL versus 4 M/mL) was evaluated in unloaded and loaded (0.1  MPa, 0.1 Hz) conditions. Study 2: loading magnitude (0, 0.1, and 0.6 MPa) applied at 0.1 Hz to 1 M/mL for 7 days was evaluated. Study 1: 4 M/mL cell density had significantly lower adenosine triphosphate (ATP), glycosaminoglycan (GAG) and collagen content, and increased lactate dehydrogenase (L DH). HP loading significantly increased ATP levels, and expression of aggrecan,...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Poisson's Contraction and Fiber Kinematics in Tissue: Insight From Collagen Network Simulations
The objective of the present work is to provide additio nal insight into this relationship. To this end, results from models of random collagen networks are compared with experimental data on reconstructed collagen gels, mouse skin dermis, and the human amnion. Attention is devoted to the mechanism leading to the large Poisson's effect observed in experi ments. The results indicate that the incremental Poisson's contraction is directly related to preferential collagen orientation. The experimentally observed downturn of the incremental Poisson's ratio at larger strains is associated with the confining effect of fibers tran...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Finite Element Framework for Computational Fluid Dynamics in FEBio
This study describes the formulation and implementation of a finite element framework for computational fluid dynamics (CFD) inFEBio, a free software designed to meet the computational needs of the biomechanics and biophysics communities. This formulation models nearly incompressible flow with a compressible isothermal formulation that uses a physically realistic value for the fluid bulk modulus. It employs fluid velocity and dilatation as essential variables: The virtual work integral enforces the balance of linear momentum and the kinematic constraint between fluid velocity and dilatation, while fluid density varies with...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Primary Blast Brain Injury Mechanisms: Current Knowledge, Limitations, and Future Directions
Mild blast traumatic brain injury (bTBI) accounts for the majority of brain injury in United States service members and other military personnel worldwide. The mechanisms of primary blast brain injury continue to be disputed with little evidence to support one or a combination of theories. The main hypotheses addressed in this review are blast wave transmission through the skull orifices, direct cranial transmission, skull flexure dynamics, thoracic surge, acceleration, and cavitation. Each possible mechanism is discussed using available literature with the goal of focusing research efforts to address the limitations and c...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Kinesin and Dynein Mechanics: Measurement Methods and Research Applications
Motor proteins play critical roles in the normal function of cells and proper development of organisms. Among motor proteins, failings in the normal function of two types of proteins, kinesin and dynein, have been shown to lead many pathologies, including neurodegenerative diseases and cancers. As such, it is critical to researchers to understand the underlying mechanics and behaviors of these proteins, not only to shed light on how failures may lead to disease, but also to guide research toward novel treatment and nano-engineering solutions. To this end, many experimental techniques have been developed to measure the forc...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Biomechanics and Mechanobiology of Saphenous Vein Grafts
Within several weeks of use as coronary artery bypass grafts (CABG), saphenous veins (SV) exhibit significant intimal hyperplasia (IH). IH predisposes vessels to thrombosis and atherosclerosis, the two major modes of vein graft failure. The fact that SV do not develop significant IH in their native venous environment coupled with the rapidity with which they develop IH following grafting into the arterial circulation suggests that factors associated with the isolation and preparation of SV and/or differences between the venous and arterial environments contribute to disease progression. There is strong evidence suggesting ...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Elastic Fibers and Large Artery Mechanics in Animal Models of Development and Disease
Development of a closed circulatory system requires that large arteries adapt to the mechanical demands of high, pulsatile pressure. Elastin and collagen uniquely address these design criteria in the low and high stress regimes, resulting in a nonlinear mechanical response. Elastin is the core component of elastic fibers, which provide the artery wall with energy storage and recoil. The integrity of the elastic fiber network is affected by component insufficiency or disorganization, leading to an array of vascular pathologies and compromised mechanical behavior. In this review, we discuss how elastic fibers are formed and ...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Single-Cell Analysis Using Hyperspectral Imaging Modalities
Almost a decade ago, hyperspectral imaging (HSI) was employed by the NASA in satellite imaging applications such as remote sensing technology. This technology has since been extensively used in the exploration of minerals, agricultural purposes, water resources, and urban development needs. Due to recent advancements in optical re-construction and imaging, HSI can now be applied down to micro- and nanometer scales possibly allowing for exquisite control and analysis of single cell to complex biological systems. This short review provides a description of the working principle of the HSI technology and how HSI can be used t...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

The Statistical Segment Length of DNA: Opportunities for Biomechanical Modeling in Polymer Physics and Next-Generation Genomics
The development of bright bisintercalating dyes for deoxyribonucleic acid (DNA) in the 1990s, most notably YOYO-1, revolutionized the field of polymer physics in the ensuing years. These dyes, in conjunction with modern molecular biology techniques, permit the facile observation of polymer dynamics via fluorescence microscopy and thus direct tests of different theories of polymer dynamics. At the same time, they have played a key role in advancing an emerging next-generation method known as genome mapping in nanochannels. The effect of intercalation on the bending energy of DNA as embodied by a change in its statistical se...
Source: Journal of Biomechanical Engineering - January 12, 2018 Category: Biomedical Engineering Source Type: research

Can Measured Synergy Excitations Accurately Construct Unmeasured Muscle Excitations?
This study explores the feasibility of using muscle synergy information extracted from eight muscle EMG signals (henceforth called “included” muscle excitations) to accurately c onstruct muscle excitations from up to 16 additional EMG signals (henceforth called “excluded” muscle excitations). Using treadmill walking data collected at multiple speeds from two subjects (one healthy, one poststroke), we performed muscle synergy analysis on all possible subsets of eight inc luded muscle excitations and evaluated how well the calculated time-varying synergy excitations could construct the remaining excluded muscle excit...
Source: Journal of Biomechanical Engineering - November 15, 2017 Category: Biomedical Engineering Source Type: research

Contractile Smooth Muscle and Active Stress Generation in Porcine Common Carotids
The mechanical response of intact blood vessels to applied loads can be delineated into passive and active components using an isometric decomposition approach. Whereas the passive response is due predominantly to the extracellular matrix (ECM) proteins and amorphous ground substance, the active response depends on the presence of smooth muscle cells (SMCs) and the contractile machinery activated within those cells. To better understand determinants of active stress generation within the vascular wall, we subjected porcine common carotid arteries (CCAs) to biaxial inflation –extension testing under maximally contracted o...
Source: Journal of Biomechanical Engineering - November 9, 2017 Category: Biomedical Engineering Source Type: research

Contributions of Kinetic Energy and Viscous Dissipation to Airway Resistance in Pulmonary Inspiratory and Expiratory Airflows in Successive Symmetric Airway Models With Various Bifurcation Angles
The aim of this study was to investigate and quantify contributions of kinetic energy and viscous dissipation to airway resistance during inspiration and expiration at various flow rates in airway models of different bifurcation angles. We employed symmetric airway models up to the 20th generation with the following five different bifurcation angles at a tracheal flow rate of 20  L/min: 15 deg, 25 deg, 35 deg, 45 deg, and 55 deg. Thus, a total of ten computational fluid dynamics (CFD) simulations for both inspiration and expiration were conducted. Furthermore, we performed additional four simulations with trach...
Source: Journal of Biomechanical Engineering - November 9, 2017 Category: Biomedical Engineering Source Type: research

Mathematical Model for Tissue-Level Hypoxic Response in Microfluidic Environment
In this study, the dynamics of intracellular species inside a colony of tumor cells are investigated by varying the cell-block thickness and cell types in a microfluidic cell culture device. The oxygen transport across the cell block is modeled through diffusion, while ascorbate (AS) transport from the extracellular medium is addressed by a concentration-dependent uptake model. The extracellular and intracellular descriptions were coupled through the consumption and traffic of species from the microchannel to the cell block. Our model shows that the onset of hypoxia is possible in HeLa cell within minutes depending on the ...
Source: Journal of Biomechanical Engineering - November 9, 2017 Category: Biomedical Engineering Source Type: research