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https://www.readbyqxmd.com/read/28448922/affine-and-non-affine-deformations-quantified-in-cytoskeletal-networks-through-three-dimensional-form-finding-model
#1
Yifan Wang, Jinghai Gong, Denis Wirtz, Benjamin W Schafer
Actin filaments and cross-linkers are main components of cytoskeletal networks in eukaryotic cells, and they support bending moments and axial forces respectively. A three-dimensional form-finding model is proposed in this work to investigate affine and non-affine deformations in cytoskeletal networks. In recent studies, modeling of cytoskeletal networks turns out to be a key piece in the cell mechanics puzzle. We used form-finding analysis to compute and analyze cytoskeletal models. A three-dimensional model is much more flexible and contains more elements than a two-dimensional model, and non-linear finite element analysis is difficult to converge...
April 20, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28448273/magnetic-induction-spectroscopy-mis-probe-design-for-cervical-tissue-measurements
#2
Jau-Yi Wang, Timothy Healey, Anthony Barker, Brian Brown, Chris Monk, Dilly Anumba
OBJECTIVE: Gradiometers have the advantage of increasing measuring sensitivity, which is particularly useful in magnetic induction spectroscopy (MIS) for bio-impedance measurements. Traditional gradiometers use a pair of field sensing coils equally distant and on opposite sides of a drive coil, which provides high immunity to interference. In this paper, a ferrite-cored coaxial gradiometer probe of 29 mm diameter has been developed for measuring the impedance spectra of cervical tissues in vivo...
April 27, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28448124/bioinspired-engineering-of-poly-ethylene-glycol-hydrogels-and-natural-protein-fibers-for-layered-heart-valve-constructs
#3
Qian Li, Yun Bai, Tao Jin, Shuo Wang, Wei Cui, Ilinca Stanciulescu, Rui Yang, Hemin Nie, Linshan Wang, Xing Zhang
Layered constructs from poly(ethylene glycol) (PEG) hydrogels and chicken eggshell membranes (ESMs) are fabricated, which can be further crosslinked by glutaraldehyde (GA) to form GA-PEG-ESM composites. Our results indicate that ESMs composed of protein fibrous networks show elastic moduli ~3.3-5.0 MPa and elongation percentages ~47-56%, close to human heart valve leaflets. Finite element simulations reveal obvious stress concentration on a partial number of fibers in the GA-crosslinked ESM (GA-ESM) samples, which can be alleviated by efficient stress distribution among multiple layers of ESMs embedded in PEG hydrogels...
April 27, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28448052/an-in-vitro-organ-culture-model-of-the-murine-intervertebral-disc
#4
Jennifer W Liu, Kevin H Lin, Christian Weber, Sameer Bhalla, Sean Kelso, Kaixi Wang, Simon Y Tang
Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices...
April 11, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28447456/numerical-modeling-of-electroosmotic-push-pull-perfusion-and-assessment-of-its-application-to-quantitative-determination-of-enzymatic-activity-in-the-extracellular-space-of-mammalian-tissue
#5
Yangguang Ou, Stephen G Weber
Many sampling methods have been developed to measure the extracellular concentrations of solutes in the extracellular space of mammalian tissue. However, few have been used to quantitatively study the various processes, such as enzymatic degradation, that determines the fate of these solutes. For a method to be useful in this pursuit, it must be able to 1) perfuse tissue and collect the perfusate for quantitative analysis of the solutes introduced and reaction products produced, 2) control the average residence time of the active solutes, and 3) have the appropriate spatial resolution for the process of interest...
April 27, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28446371/beware-of-the-toilet-the-risk-for-a-deep-tissue-injury-during-toilet-sitting
#6
Maayan Lustig, Ayelet Levy, Kara Kopplin, Zehava Ovadia-Blechman, Amit Gefen
A pressure injury (PrI) compromises quality of life and can be life-threatening. The fundamental cause of PrIs is sustained deformations in weight-bearing soft tissues, e.g., during prolonged sitting on inadequate surfaces such as a toilet seat. In nursing homes and geriatric facilities, patients need assistance using the restroom, and patients being left on the toilet for tens-of-minutes is a real-world scenario, unfortunately. Nevertheless, there are no published studies regarding sustained tissue loads during toilet sitting and their effects on tissue physiology...
April 23, 2017: Journal of Tissue Viability
https://www.readbyqxmd.com/read/28446031/influences-of-geometrical-and-mechanical-properties-of-bone-tissues-in-mandible-behaviour-experimental-and-numerical-predictions
#7
A Ramos, Yi Nyashin, M Mesnard
The properties and geometry of bone in the mandible play a key role in mandible behaviour during a person's lifetime, and attention needs to be paid to the influence of bone properties. We analysed the effect of bone geometry, size and bone properties in mandible behaviour, experimenting on cadaveric mandibles and FE models. The study was developed using the geometry of a cadaveric mandible without teeth. Three models of cadaveric condyles were experimentally tested with instrumented with four rosettes, and a condyle reaction of 300 N...
April 26, 2017: Computer Methods in Biomechanics and Biomedical Engineering
https://www.readbyqxmd.com/read/28444997/a-holistic-view-of-the-effects-of-episiotomy-on-pelvic-floor
#8
Dulce A Oliveira, Marco P L Parente, Begoña Calvo, Teresa Mascarenhas, Renato M Natal Jorge
Vaginal delivery is commonly accepted as a risk factor in pelvic floor dysfunction (PFD), however, other obstetric procedures (episiotomy) are still controversial. In this work, to analyze the relationship between episiotomy and pelvic floor function, a finite element model (FEM) of the pelvic cavity is used considering the pelvic floor muscles (PFM) with damaged regions from spontaneous vaginal delivery, and from deliveries with episiotomy. Common features assessed at screening of PFD are evaluated during numerical simulations of both Valsalva maneuver and contraction...
April 26, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28444478/the-association-between-geometry-and-wall-stress-in-emergently-repaired-abdominal-aortic-aneurysms
#9
Sathyajeeth S Chauhan, Carlos A Gutierrez, Mirunalini Thirugnanasambandam, Victor De Oliveira, Satish C Muluk, Mark K Eskandari, Ender A Finol
Abdominal aortic aneurysm (AAA) is a prevalent cardiovascular disease characterized by the focal dilation of the aorta, which supplies blood to all the organs and tissues in the systemic circulation. With the AAA increasing in diameter over time, the risk of aneurysm rupture is generally associated with the size of the aneurysm. If diagnosed on time, intervention is recommended to prevent AAA rupture. The criterion to decide on surgical intervention is determined by measuring the maximum diameter of the aneurysm relative to the critical value of 5...
April 25, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/28443694/fractal-features-and-surface-micromorphology-of-unworn-surfaces-of-rigid-gas-permeable-contact-lenses
#10
Ştefan Ţălu, Miroslaw Bramowicz, Slawomir Kulesza, Ilenia Fiorillo, Stefano Giovanzana
PURPOSE: The aim of this exploratory study was to investigate the micromorphology of surfaces of rigid gas permeable (RGP) contact lenses (CLs) using atomic force microscopy (AFM) followed by fractal analysis. MATERIALS AND METHODS: In order to characterize in a quantitative manner the micromorphology of surfaces of new and unworn RGP CLs made of twelve different materials, AFM was taken and then analyzed using fractal methods. Surface topography was sampled in an intermittent-contact mode in air, on square areas of 5 × 5 µm(2) (MultiMode with Nanoscope V (Bruker)...
April 26, 2017: Current Eye Research
https://www.readbyqxmd.com/read/28443571/numerical-optimization-of-the-position-in-femoral-head-of-proximal-locking-screws-of-proximal-femoral-nail-system-biomechanical-study
#11
Mehmet Nuri Konya, Özgür Verim
BACKGROUND: Proximal femoral fracture rates are increasing due to osteoporosis and traffic accident. Proximal femoral nails are routinely used in the treatment of these fractures on the proximal femur. AIMS: The present study aimed to compare various combination and to determine ideal proximal lag screw (PLS) position on the pertrochanteric fractures (AO classification 31-A1) of femur by using optimised finite element analysis. STUDY DESIGN: Biomechanical Study...
April 6, 2017: Balkan Medical Journal
https://www.readbyqxmd.com/read/28442713/a-self-consistent-spin-diffusion-model-for-micromagnetics
#12
Claas Abert, Michele Ruggeri, Florian Bruckner, Christoph Vogler, Aurelien Manchon, Dirk Praetorius, Dieter Suess
We propose a three-dimensional micromagnetic model that dynamically solves the Landau-Lifshitz-Gilbert equation coupled to the full spin-diffusion equation. In contrast to previous methods, we solve for the magnetization dynamics and the electric potential in a self-consistent fashion. This treatment allows for an accurate description of magnetization dependent resistance changes. Moreover, the presented algorithm describes both spin accumulation due to smooth magnetization transitions and due to material interfaces as in multilayer structures...
December 21, 2016: Scientific Reports
https://www.readbyqxmd.com/read/28442297/vertebral-and-femoral-bone-mineral-density-and-bone-strength-in-prostate-cancer-patients-assessed-in-phantomless-pet-ct-examinations
#13
Benedikt J Schwaiger, David L Kopperdahl, Lorenzo Nardo, Luca Facchetti, Alexandra S Gersing, Jan Neumann, Kwang J Lee, Tony M Keaveny, Thomas M Link
PURPOSE: Bone fracture risk assessed ancillary to positron emission tomography with computed tomography co-registration (PET/CT) could provide substantial clinical value to oncology patients with elevated fracture risk without introducing additional radiation dose. The purpose of our study was to investigate the feasibility of obtaining valid measurements of bone mineral density (BMD) and finite element analysis-derived bone strength of the hip and spine using PET/CT examinations of prostate cancer patients by comparing against values obtained using routine multidetector-row computed tomography (MDCT) scans-as validated in previous studies-as a reference standard...
April 22, 2017: Bone
https://www.readbyqxmd.com/read/28441328/a-gradient-field-pulsed-eddy-current-probe-for-evaluation-of-hidden-material-degradation-in-conductive-structures-based-on-lift-off-invariance
#14
Yong Li, Haoqing Jing, Ilham Mukriz Zainal Abidin, Bei Yan
Coated conductive structures are widely adopted in such engineering fields as aerospace, nuclear energy, etc. The hostile and corrosive environment leaves in-service coated conductive structures vulnerable to Hidden Material Degradation (HMD) occurring under the protection coating. It is highly demanded that HMD can be non-intrusively assessed using non-destructive evaluation techniques. In light of the advantages of Gradient-field Pulsed Eddy Current technique (GPEC) over other non-destructive evaluation methods in corrosion evaluation, in this paper the GPEC probe for quantitative evaluation of HMD is intensively investigated...
April 25, 2017: Sensors
https://www.readbyqxmd.com/read/28440627/composite-micro-posts-with-high-dry-adhesion-strength
#15
Helen K Minsky, Kevin T Turner
Interfaces with enhanced and tunable adhesion have applications in a broad range of fields, including microtransfer printing of semiconductors, grippers on robots, and component handling in manufacturing. Here, a composite post structure with a stiff core and compliant shell is used to achieve enhanced adhesion under normal loading. Loading the composite structure in shear significantly reduces the effective adhesion strength, thus providing tunability. The composite posts can be used as stamps in microtransfer printing processes or as building blocks of large area tunable surfaces composed of arrays of posts...
April 25, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28439162/evaluating-the-effect-of-minimizing-screws-on-stabilization-of-symphysis-mandibular-fracture-by-3d-finite-element-analysis
#16
Ghias Kharmanda, Mohamed-Yaser Kharma
PURPOSE: The objective of this work is to integrate structural optimization and reliability concepts into mini-plate fixation strategy used in symphysis mandibular fractures. The structural reliability levels are next estimated when considering a single failure mode and multiple failure modes. PATIENTS AND METHODS: A 3-dimensional finite element model is developed in order to evaluate the ability of reducing the negative effect due to the stabilization of the fracture...
June 2017: Journal of Maxillofacial and Oral Surgery
https://www.readbyqxmd.com/read/28438031/mri-based-finite-element-modeling-of-facial-mimics-a-case-study-on-the-paired-zygomaticus-major-muscles
#17
Ang-Xiao Fan, Stéphanie Dakpé, Tien Tuan Dao, Philippe Pouletaut, Mohamed Rachik, Marie Christine Ho Ba Tho
Finite element simulation of facial mimics provides objective indicators about soft tissue functions for improving diagnosis, treatment and follow-up of facial disorders. There is a lack of in vivo experimental data for model development and validation. In this study, the contribution of the paired Zygomaticus Major (ZM) muscle contraction on the facial mimics was investigated using in vivo experimental data derived from MRI. Maximal relative differences of 7.7% and 37% were noted between MRI-based measurements and numerical outcomes for ZM and skin deformation behaviors respectively...
April 24, 2017: Computer Methods in Biomechanics and Biomedical Engineering
https://www.readbyqxmd.com/read/28437985/scattering-of-surface-plasmon-polaritons-at-a-planar-interface-by-an-embedded-dielectric-nanocube
#18
Seojun Lee, Hyungchae Kim, Jongcheon Lee, Changsoon Kim
We investigate scattering of surface plasmon polaritons (SPPs) at a planar metal-dielectric interface by a dielectric nanocube embedded in the metal layer using finite element method-based simulations. The scattering characteristics of the embedded nanocube, such as the scattering and absorption cross sections, far-field scattering patterns, reflectance, and transmittance, are calculated as functions of the wavelength of the incident SPP waves in the visible range. The main features of the characteristics are explained in connection with the excitation of plasmonic eigenmodes of the embedded nanocube...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437916/multiband-selective-absorbers-made-of-1d-periodic-ag-sio-sub-2-sub-ag-core-shell-coaxial-cylinders-horizontally-lying-on-a-planar-substrate
#19
Yi Zhao, Ceji Fu
In this paper, we present a one-dimensional periodic microstructure for multiband selective absorbers of thermal radiation. The microstructure is made of Ag/SiO<sub>2</sub>/Ag core/shell coaxial cylinders horizontally lying on top of a SiO<sub>2</sub> dielectric spacer and an opaque silver substrate. The spectral-directional absorptivity of the proposed structure was numerically investigated with the finite element based Comsol Multiphysics software. Multiband selective absorption in the wavenumber range from 2500 to 20000 cm<sup>-1</sup> for TM-wave incidence was obtained...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437902/high-performance-temperature-sensing-using-a-selectively-filled-solid-core-photonic-crystal-fiber-with-a-central-air-bore
#20
J Ma, H H Yu, X Jiang, D S Jiang
A high-performance temperature sensor based on mode-coupling principle is proposed using a selectively filled, solid-core photonic crystal fiber with a central air-bore. The fibers are fabricated using the "stack-and-draw" method, with a micro scale central bore deliberately kept during the drawing procedure. The addition of the central air-bore enhances the mode-coupling efficiency between the fundamental core mode and modes in the high-index liquid-filled holes in the fiber cladding, therefore, the fiber can be used for a novel sensing architecture, when cladding holes are selectively filled with temperature sensitive liquids...
April 17, 2017: Optics Express
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