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Finite elements analysis

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https://www.readbyqxmd.com/read/28222045/validation-of-scaffold-design-optimization-in-bone-tissue-engineering-finite-element-modeling-versus-designed-experiments
#1
Nicholas Uth, Jens Mueller, Byran Smucker, Azizeh-Mitra Yousefi
This study reports the development of biological/synthetic scaffolds for bone tissue engineering (TE) via 3D bioplotting. These scaffolds were composed of poly(L-lactic-co-glycolic acid) (PLGA), type I collagen, and nano-hydroxyapatite (nHA) in an attempt to mimic the extracellular matrix of bone. The solvent used for processing the scaffolds was 1,1,1,3,3,3-hexafluoro-2-propanol. The produced scaffolds were characterized by scanning electron microscopy, microcomputed tomography, thermogravimetric analysis, and unconfined compression test...
February 21, 2017: Biofabrication
https://www.readbyqxmd.com/read/28222002/friction-reduction-through-ultrasonic-vibration-part-1-modelling-intermittent-contact
#2
Eric Vezzoli, Zlatko Virdih, Vincenzo Giamundo, Betty Lemaire-Semail, Frederic Giraud, Tomaz Rodic, Djordje Peric, Michael Adams
Ultrasonic vibration is employed to modify the friction of a finger pad in way that induces haptic sensations. A combination of intermittent contact and squeeze film levitation has been previously proposed as the most probable mechanism. In this paper, in order to understand the underlying principles that govern friction modulation by intermittent contact, numerical models based on finite element (FE) analysis and also a spring-Coulombic slider are developed. The physical input parameters for the FE model are optimised by measuring the contact phase shift between a finger pad and a vibrating plate...
February 17, 2017: IEEE Transactions on Haptics
https://www.readbyqxmd.com/read/28218642/theoretical-analysis-of-an-optical-accelerometer-based-on-resonant-optical-tunneling-effect
#3
Aoqun Jian, Chongguang Wei, Lifang Guo, Jie Hu, Jun Tang, Jun Liu, Xuming Zhang, Shengbo Sang
Acceleration is a significant parameter for monitoring the status of a given objects. This paper presents a novel linear acceleration sensor that functions via a unique physical mechanism, the resonant optical tunneling effect (ROTE). The accelerometer consists of a fixed frame, two elastic cantilevers, and a major cylindrical mass comprised of a resonant cavity that is separated by two air tunneling gaps in the middle. The performance of the proposed sensor was analyzed with a simplified mathematical model, and simulated using finite element modeling...
February 17, 2017: Sensors
https://www.readbyqxmd.com/read/28217410/design-and-analysis-of-a-field-modulated-magnetic-screw-for-artificial-heart
#4
Zhijian Ling, Jinghua Ji, Fangqun Wang, Fangfang Bian
This paper proposes a new electromechanical energy conversion system, called Field Modulated Magnetic Screw (FMMS) as a high force density linear actuator for artificial heart. This device is based on the concept of magnetic screw and linear magnetic gear. The proposed FMMS consists of three parts with the outer and inner carrying the radially magnetized helically permanent-magnet (PM), and the intermediate having a set of helically ferromagnetic pole pieces, which modulate the magnetic fields produced by the PMs...
May 2017: AIP Advances
https://www.readbyqxmd.com/read/28216846/three-dimensional-finite-element-analysis-of-the-stress-distribution-pattern-in-a-mandibular-first-molar-tooth-restored-with-five-different-restorative-materials
#5
Kathleen Manuela D'souza, Meena Ajay Aras
INTRODUCTION: Badly broken or structurally compromised posterior teeth are frequently associated with crown/root fracture. Numerous restorative materials have been used to fabricate indirect full-coverage restorations for such teeth. This study aims to evaluate and compare the effect of restorative materials on the stress distribution pattern in a mandibular first molar tooth, under varying loading conditions and to compare the stress distribution pattern in five commonly used indirect restorative materials...
January 2017: Journal of Indian Prosthodontic Society
https://www.readbyqxmd.com/read/28212388/multiple-processes-in-two-dimensional-visual-statistical-learning
#6
Eiichi Hoshino, Ken Mogi
Knowledge about the arrangement of visual elements is an important aspect of perception. This study investigates whether humans learn rules of two-dimensional abstract patterns (exemplars) generated from Reber's artificial grammar. The key question is whether the subjects can implicitly learn them without explicit instructions, and, if so, how they use the acquired knowledge to judge new patterns (probes) in relation to their finite experience of the exemplars. The analysis was conducted using dissimilarities among patterns, which are defined with n-gram probabilities and the Levenshtein distance...
2017: PloS One
https://www.readbyqxmd.com/read/28209345/multiobjective-optimization-of-cartilage-stress-for-non-invasive-patient-specific-recommendations-of-high-tibial-osteotomy-correction-angle-a-novel-method-to-investigate-alignment-correction
#7
Keke Zheng, Corey J Scholes, Junning Chen, David Parker, Qing Li
Medial opening wedge high tibial osteotomy (MOWHTO) is a surgical procedure to treat knee osteoarthritis associated with varus deformity. However, the ideal final alignment of the Hip-Knee-Ankle (HKA) angle in the frontal plane, that maximizes procedural success and post-operative knee function, remains controversial. Therefore, the purpose of this study was to introduce a subject-specific modeling procedure in determining the biomechanical effects of MOWHTO alignment on tibiofemoral cartilage stress distribution...
February 13, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28208996/stress-distribution-under-commercial-denture-liners-a-finite-element-and-clinical-analysis
#8
Rahul Shrivastava, Saurabh Chaturvedi, Ashok Kumar Verma, Mariyum Ali, Amrita Nagendra, Mudita Chaturvedi
INTRODUCTION: Previous studies have shown that 20-30% of denture users have been dissatisfied with their dentures. AIM: To evaluate the stress pattern under elastic and viscoelastic denture liners using 3-Dimensional Finite Element Analysis (FEA) and its clinical correlation using a questionnaire. MATERIALS AND METHODS: The study had both in-vitro and in-vivo phases. In in-vitro phase fabrication of a virtual parametric model of edentulous maxilla and dentures with overlying mucosa was made...
December 2016: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28208112/systematic-mechanical-evaluation-of-electrospun-gelatin-meshes
#9
Annabel L Butcher, Ching Theng Koh, Michelle L Oyen
Electrospinning is a simple and efficient process for producing sub-micron fibres. However, the process has many variables, and their effects on the non-woven mesh of fibres is complex. In particular, the effects on the mechanical properties of the fibre meshes are poorly understood. This paper conducts a parametric study, where the concentration and bloom strength of the gelatin solutions are varied, while all electrospinning process parameters are held constant. The effects on the fibrous meshes are monitored using scanning electron microscopy and mechanical testing under uniaxial tension...
February 7, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28204985/comparison-of-strain-measurement-in-the-mouse-forearm-using-subject-specific-finite-element-models-strain-gaging-and-digital-image-correlation
#10
Mark Begonia, Mark Dallas, Mark L Johnson, Ganesh Thiagarajan
Mechanical loading in bone leads to the activation of bone-forming pathways that are most likely associated with a minimum strain threshold being experienced by the osteocyte. To investigate the correlation between cellular response and mechanical stimuli, researchers must develop accurate ways to measure/compute strain both externally on the bone surface and internally at the osteocyte level. This study investigates the use of finite element (FE) models to compute bone surface strains on the mouse forearm...
February 15, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28198781/biomechanical-analysis-of-two-level-cervical-disc-replacement-with-a-stand-alone-u-shaped-disc-implant
#11
Yang Li, Guy R Fogel, Zhenhua Liao, Rajnesh Tyagi, Gaolong Zhang, Weiqiang Liu
STUDY DESIGN: Biomechanical study using a three-dimensional nonlinear finite element (FE) model. OBJECTIVE: To analyze biomechanical changes with three prostheses based on two-level arthroplasty and to verify the biomechanical efficiency of dynamic cervical implants (DCIs) with a stand-alone U-shaped structure. SUMMARY OF BACKGROUND DATA: Few studies have compared biomechanical behavior of various prostheses as they relate to clinical results after two-level total disc replacement (TDR)...
February 14, 2017: Spine
https://www.readbyqxmd.com/read/28197969/functional-parallel-factor-analysis-for-functions-of-one-and-two-dimensional-arguments
#12
Ji Yeh Choi, Heungsun Hwang, Marieke E Timmerman
Parallel factor analysis (PARAFAC) is a useful multivariate method for decomposing three-way data that consist of three different types of entities simultaneously. This method estimates trilinear components, each of which is a low-dimensional representation of a set of entities, often called a mode, to explain the maximum variance of the data. Functional PARAFAC permits the entities in different modes to be smooth functions or curves, varying over a continuum, rather than a collection of unconnected responses...
February 14, 2017: Psychometrika
https://www.readbyqxmd.com/read/28195345/in-vivo-measurements-of-human-neck-skin-elasticity-using-mri-and-finite-element-modeling
#13
Yunqiang An, Changjin Ji, Yong Li, Jianxia Wang, Xinyue Zhang, Yaqi Huang
PURPOSE: The assessment of mechanical properties of the human skin is very important in investigating the mechanism of obstructive sleep apnea, a common disorder characterized by repetitive collapse and obstruction of the upper airway during sleep. In this study, a unique method, combining magnetic resonance imaging (MRI) and finite element modeling (FEM), was developed to obtain the value of the in vivo elastic modulus of the neck skin. MEHTHOD: A total of 22 subjects, 16 males and 6 females, were recruited to participate in the MRI studies...
February 13, 2017: Medical Physics
https://www.readbyqxmd.com/read/28192498/correction-preserving-posterior-complex-can-prevent-adjacent-segment-disease-following-posterior-lumbar-interbody-fusion-surgeries-a-finite-element-analysis
#14
Yun-Peng Huang, Cheng-Fei Du, Cheng-Kung Cheng, Zheng-Cheng Zhong, Xuan-Wei Chen, Gui Wu, Zhe-Chen Li, Jin-Duo Ye, Jian-Hua Lin, Li Zhen Wang
[This corrects the article DOI: 10.1371/journal.pone.0166452.].
2017: PloS One
https://www.readbyqxmd.com/read/28191927/foldectures-3d-molecular-architectures-from-self-assembly-of-peptide-foldamers
#15
Sung Hyun Yoo, Hee-Seung Lee
The wide range of fascinating supramolecular architectures found in nature, from DNA double helices to giant protein shells, inspires researchers to mimic the diverse shapes and functions of natural systems. Thus, a variety of artificial molecular platforms have been developed by assembling DNA-, peptide-, and protein-based building blocks for medicinal and biological applications. There has also been a significant interest in the research of non-natural oligomers (i.e., foldamers) that fold into well-defined secondary structures analogous to those found in proteins, because the assemblies of foldamers are expected not only to form biomimetic supramolecular architectures that resemble those of nature but also to display unique functions and unprecedented topologies at the same time due to their different folding propensities from those of natural building blocks...
February 13, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28190816/fracture-resistance-of-zirconia-composite-veneered-crowns-in-comparison-with-zirconia-porcelain-crowns
#16
Omar Alsadon, David Patrick, Anthony Johnson, Sarah Pollington, Duncan Wood
The objectives were to evaluate the fracture resistance and stress concentration in zirconia/composite veneered crowns in comparison to zirconia/porcelain crowns using occlusal fracture resistance and by stress analysis using finite element analysis method. Zirconia substructures were divided into two groups based on the veneering material. A static load was applied occlusally using a ball indenter and the load to fracture was recorded in Newtons (N). The same crown design was used to create 3D crown models and evaluated using FEA...
February 11, 2017: Dental Materials Journal
https://www.readbyqxmd.com/read/28188469/investigation-of-interaction-phenomena-between-crural-fascia-and-muscles-by-using-a-three-dimensional-numerical-model
#17
Piero G Pavan, Paola Pachera, Antonella Forestiero, Arturo N Natali
The focus of this work is the numerical modeling of the anterior compartment of the human leg with particular attention to crural fascia. Interaction phenomena between fascia and muscles are of clinical interest to explain some pathologies, as the compartment syndrome. A first step to enhance knowledge on this topic consists in the investigation of fascia biomechanical role and its interaction with muscles in physiological conditions. A three-dimensional finite element model of the anterior compartment is developed based on anatomical data, detailing the structural conformation of crural fascia, composed of three layers, and modeling the muscles as a unique structure...
February 10, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28188386/improved-identifiability-of-myocardial-material-parameters-by-an-energy-based-cost-function
#18
Anastasia Nasopoulou, Anoop Shetty, Jack Lee, David Nordsletten, C Aldo Rinaldi, Pablo Lamata, Steven Niederer
Myocardial stiffness is a valuable clinical biomarker for the monitoring and stratification of heart failure (HF). Cardiac finite element models provide a biomechanical framework for the assessment of stiffness through the determination of the myocardial constitutive model parameters. The reported parameter intercorrelations in popular constitutive relations, however, obstruct the unique estimation of material parameters and limit the reliable translation of this stiffness metric to clinical practice. Focusing on the role of the cost function (CF) in parameter identifiability, we investigate the performance of a set of geometric indices (based on displacements, strains, cavity volume, wall thickness and apicobasal dimension of the ventricle) and a novel CF derived from energy conservation...
February 10, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28187321/development-and-parameter-identification-of-a-visco-hyperelastic-model-for-the-periodontal-ligament
#19
Huixiang Huang, Wencheng Tang, Qiyan Tan, Bin Yan
The present study developed and implemented a new visco-hyperelastic model that is capable of predicting the time-dependent biomechanical behavior of the periodontal ligament. The constitutive model has been implemented into the finite element package ABAQUS by means of a user-defined material subroutine (UMAT). The stress response is decomposed into two constitutive parts in parallel which are a hyperelastic and a time-dependent viscoelastic stress response. In order to identify the model parameters, the indentation equation based on V-W hyperelastic model and the indentation creep model are developed...
January 31, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28185295/irreversible-electroporation-for-the-ablation-of-pancreatic-malignancies-a-patient-specific-methodology
#20
Eduardo L Latouche, Michael B Sano, Melvin F Lorenzo, Rafael V Davalos, Robert C G Martin
BACKGROUND AND OBJECTIVES: Irreversible Electroporation (IRE) is a focal ablation technique highly attractive to surgical oncologists due to its non-thermal nature that allows for eradication of unresectable tumors in a minimally invasive procedure. In this study, our group sought to address the challenge of predicting the ablation volume with IRE for pancreatic procedures. METHODS: In compliance with HIPAA and hospital IRB approval, we established a pre-treatment planning methodology for IRE procedures in pancreas, which optimized treatment protocols for individual cases of locally advanced pancreatic cancer (LAPC)...
February 10, 2017: Journal of Surgical Oncology
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