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Finite elements analysis

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https://www.readbyqxmd.com/read/28346898/modelling-of-escherichia-coli-concentrations-in-bathing-water-at-microtidal-coasts
#1
A Palazón, I López, L Aragonés, Y Villacampa, F J Navarro-González
Monitoring of the quality of bathing water in line with the European Commission bathing water directive (Directive 2006/7/EC) is a significant economic expense for those countries with great lengths of coastline. In this study a numerical model based on finite elements is generated whose objective is partially substituting the microbiological analysis of the quality of coastal bathing waters. According to a study of the concentration of Escherichia coli in 299 Spanish Mediterranean beaches, it was established that the most important variables that influence the concentration are: monthly sunshine hours, mean monthly precipitation, number of goat cattle heads, population density, presence of Posidonia oceanica, UV, urbanization level, type of sediment, wastewater treatment ratio, salinity, distance to the nearest discharge, and wave height perpendicular to the coast...
March 24, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28343925/influence-of-alveolar-bone-loss-and-cement-layer-thickness-on-the-biomechanical-behavior-of-endodontically-treated-maxillary-incisors-a-3-dimensional-finite-element-analysis
#2
Amanda Maria de Oliveira Dal Piva, João Paulo Mendes Tribst, Rodrigo Othávio de Assunção E Souza, Alexandre Luiz Souto Borges
INTRODUCTION: In order to understand the mechanical behavior of a weakened incisor, this study aimed to evaluate the stress distribution caused by different alveolar bone heights and cement layer thickness. METHODS: A finite element analysis was conducted for this investigation. An intact maxillary central incisor was initially modeled, and the bone of the models was modified in order to simulate 4 levels of bone height: BL0 (no bone loss), BL1 (1/3 bone loss), BL2 (1/2 bone loss), and BL3 (2/3 bone loss)...
March 23, 2017: Journal of Endodontics
https://www.readbyqxmd.com/read/28342586/biomechanical-analysis-of-the-fixation-systems-for-anterior-column-and-posterior-hemi-transverse-acetabular-fractures
#3
Jianyin Lei, Pengfei Dong, Zhiqiang Li, Feng Zhu, Zhihua Wang, Xianhua Cai
OBJECTIVE: The aim of this study was to evaluate the biomechanical properties of common fixation systems for complex acetabular fractures. METHODS: A finite element (FE) pelvic model with anterior column and posterior hemi-transverse acetabular fractures was created. Three common fixation systems were used to fix the posterior wall acetabular fractures: 1. Anterior column plate combined with posterior column screws (group I), 2. Anterior column plate combined with quadrilateral area screws (group II) and 3...
March 22, 2017: Acta Orthopaedica et Traumatologica Turcica
https://www.readbyqxmd.com/read/28342508/gender-smoking-body-size-and-aneurysm-geometry-influence-the-biomechanical-rupture-risk-of-abdominal-aortic-aneurysms-as-estimated-by-finite-element-analysis
#4
Moritz Lindquist Liljeqvist, Rebecka Hultgren, Antti Siika, T Christian Gasser, Joy Roy
OBJECTIVE: Finite element analysis (FEA) has been suggested to be superior to maximal diameter measurements in predicting rupture of abdominal aortic aneurysms (AAAs). Our objective was to investigate to what extent previously described rupture risk factors were associated with FEA-estimated rupture risk. METHODS: One hundred forty-six patients with an asymptomatic AAA of a 40- to 60-mm diameter were retrospectively identified and consecutively included. The patients' computed tomography angiograms were analyzed by FEA without (neutral) and with (specific) input of patient-specific mean arterial pressure (MAP), gender, family history, and age...
April 2017: Journal of Vascular Surgery
https://www.readbyqxmd.com/read/28342408/finite-element-method-based-study-for-effect-of-adult-degenerative-scoliosis-on-the-spinal-vibration-characteristics
#5
Ming Xu, James Yang, Isador Lieberman, Ram Haddas
Finite element analysis was used to investigate the responses of five healthy subjects and five adult degenerative scoliosis (ADS) subjects to cyclic vibration. The dynamic responses of the healthy and scoliotic spines to the sinusoidal cyclic vibrations have been investigated in previous studies by simulation or experimental approaches. However, no simulation or experimental results were available for the ADS subjects. The effect of the ADS on the vibrational characteristics of spines remained unknown. The objective of this study was to compare differences of the dynamic responses to the cyclic vibration input between the healthy subjects and subjects with ADS...
March 22, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28341899/cortical-microstructure-compensates-for-smaller-bone-size-in-young-caribbean-hispanic-versus-non-hispanic-white-men
#6
M D Walker, A Kepley, K Nishiyama, B Zhou, E Guo, T L Nickolas
Hispanic men have smaller bone size but thicker and denser cortices compared to white men, leading to similar mechanical competence. INTRODUCTION: The purpose of this study was to assess differences in vBMD and microarchitecture in young Caribbean Hispanic (n = 30) and non-Hispanic Caucasian (n = 30) men. METHODS: We measured areal bone mineral density (aBMD) at the spine, total hip (TH), femoral neck (FN), and forearm by dual-energy X-ray absorptiometry (DXA) and bone geometry, mass, microarchitecture, and mechanical competence by high-resolution peripheral quantitative computed tomography (HRpQCT), individual trabecula segmentation (ITS), and finite element analysis (FEA)...
March 24, 2017: Osteoporosis International
https://www.readbyqxmd.com/read/28341150/in-vitro-and-in-silico-characterization-of-fibrous-scaffolds-comprising-alternate-colistin-sulfate-loaded-and-heat-treated-polyvinyl-alcohol-nanofibrous-sheets
#7
István Sebe, Eszter Ostorházi, Zsolt Bodai, Zsuzsanna Eke, József Szakács, Norbert Krisztián Kovács, Romána Zelkó
A multilayer mat for dispensing colistin sulfate through a body surface was prepared by electrospinning. The fabricated system comprised various polyvinyl alcohol fibrous layers prepared with or without the active ingredient. One of the electrospun layers contained water-soluble colistin sulfate and the other was prepared from the same polymer type and composition without the active drug and was finally heat-treated. The heat treatment modified the supramolecular structure and conferred the polymer nanofibre with the rate-controlling function...
March 21, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28335263/enhanced-deposition-uniformity-via-an-auxiliary-electrode-in-massive-electrospinning
#8
Dezhi Wu, Zhiming Xiao, Lei Deng, Yu Sun, Qiulin Tan, Linxi Dong, Shaohua Huang, Rui Zhu, Yifang Liu, Wanxi Zheng, Yang Zhao, Lingyun Wang, Daoheng Sun
Uniform deposition of nanofibers in the massive electrospinning process is critical in the industrial applications of nanofibers. Tip-Induced Electrospinning (TIE) is a cost-effective large-scale nanofiber-manufacturing method, but it has poor deposition uniformity. An auxiliary conductive electrode connected to the emitting electrode was introduced to improve the deposition uniformity of the nanofibers. The effects of the auxiliary electrode shape, the tilted angles and the position of the boat-like electrode on the electric field distribution, the diameter of the nanofibers, the jet control and the deposition uniformity were explored by using finite element analysis of the electric field and experiments...
July 22, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28334367/modeling-of-stiffness-and-strength-of-bone-at-nanoscale
#9
Diab W Abueidda, Fereshteh A Sabet, Iwona M Jasiuk
Two distinct geometrical models of bone at nanoscale (collagen fibril and mineral platelets) are analyzed computationally. In the first model (Model I) minerals are periodically distributed in a staggered manner in a collagen matrix while in the second model (Model II) minerals form continuous layers outside the collagen fibril. Elastic modulus and strength of bone at the nanoscale, represented by these two models, are studied using a finite element software Abaqus. The analysis employs a traction-separation law (cohesive surface modeling) at various interfaces in the models to account for interfacial delaminations...
March 23, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28333370/influence-of-nickel-titanium-rotary-systems-with-varying-tapers-on-the-biomechanical-behaviour-of-maxillary-first-premolars-under-occlusal-forces-a-finite-element-analysis-study
#10
S Askerbeyli Ors, A Serper
AIM: To evaluate the effect of three nickel-titanium (Ni-Ti) rotary systems with varying tapers on stress distribution and to analyse potential fracture patterns as well as the volume of fracture-susceptible regions in two-rooted maxillary premolars. METHODOLOGY: The root canals of three single-rooted premolars were prepared with either HeroShaper (Micro-Mega, Besançon, France) to (size 30, .04 taper), Revo-S (Micro-Mega) to AS30 (size 30, .06 taper) or ProTaper Universal (Dentsply Maillefer, Ballaigeus, Switzerland) to F3 (size 30, ...
March 23, 2017: International Endodontic Journal
https://www.readbyqxmd.com/read/28330989/form-function-relationships-in-dragonfly-mandibles-under-an-evolutionary-perspective
#11
Alexander Blanke, Helmut Schmitz, Alessandra Patera, Hugo Dutel, Michael J Fagan
Functional requirements may constrain phenotypic diversification or foster it. For insect mouthparts, the quantification of the relationship between shape and function in an evolutionary framework remained largely unexplored. Here, the question of a functional influence on phenotypic diversification for dragonfly mandibles is assessed with a large-scale biomechanical analysis covering nearly all anisopteran families, using finite element analysis in combination with geometric morphometrics. A constraining effect of phylogeny could be found for shape, the mandibular mechanical advantage (MA), and certain mechanical joint parameters, while stresses and strains, the majority of joint parameters and size are influenced by shared ancestry...
March 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28330449/a-cross-sectional-study-of-the-effects-of-load-carriage-on-running-characteristics-and-tibial-mechanical-stress-implications-for-stress-fracture-injuries-in-women
#12
Chun Xu, Amy Silder, Ju Zhang, Jaques Reifman, Ginu Unnikrishnan
BACKGROUND: Load carriage is associated with musculoskeletal injuries, such as stress fractures, during military basic combat training. By investigating the influence of load carriage during exercises on the kinematics and kinetics of the body and on the biomechanical responses of bones, such as the tibia, we can quantify the role of load carriage on bone health. METHODS: We conducted a cross-sectional study using an integrated musculoskeletal-finite-element model to analyze how the amount of load carriage in women affected the kinematics and kinetics of the body, as well as the tibial mechanical stress during running...
March 23, 2017: BMC Musculoskeletal Disorders
https://www.readbyqxmd.com/read/28328510/investigation-and-modeling-of-capacitive-human-body-communication
#13
Xiao-Qi Zhu, Yong-Xin Guo, Wen Wu
This paper presents a systematic investigation of the capacitive human body communication (HBC). The measurement of HBC channels is performed using a novel battery-powered system to eliminate the effects of baluns, cables and instruments. To verify the measured results, a numerical model incorporating the entire HBC system is established. Besides, it is demonstrated that both the impedance and path gain bandwidths of HBC channels is affected by the electrode configuration. Based on the analysis of the simulated electric field distribution, an equivalent circuit model is proposed and the circuit parameters are extracted using the finite element method...
April 2017: IEEE Transactions on Biomedical Circuits and Systems
https://www.readbyqxmd.com/read/28326732/-three-dimensional-finite-element-analyses-of-the-deep-wedge-shaped-defective-premolars-restored-with-different-methods
#14
Zhao Ling, Yang Liyuan, Liu Cuiling, Gao Xu
OBJECTIVE: The objective of this paper is to analyze the stress distribution in the deep wedge-shaped defective mandibular first premolars restored with different methods. METHODS: Three-dimensional finite element models of mandibular first premolar with deep wedge-shaped defect were created. The model, which was untreated after root canal treatment, served as the control group. Then, according to different treatment designs, four experimental groups were established as follows: resin filling (A), post restoration after resin filling (B), crown restoration after resin filling (C), and post and crown restoration after resin filling (D)...
February 1, 2017: Hua Xi Kou Qiang Yi Xue za Zhi, Huaxi Kouqiang Yixue Zazhi, West China Journal of Stomatology
https://www.readbyqxmd.com/read/28326710/-finite-elemental-analysis-of-the-influence-of-mandibular-plane-angle-on-the-stress-distribution-of-implant-tooth
#15
Xing Weibin, Zheng Shuxian, Yang Shiyi
OBJECTIVE: Finite elemental analysis of the mechanical characteristics of a first mandibular implant molar under different mandibular plane angles determines the load conditions on the implant, thereby providing guidance for clinical application. METHODS: CT data of three mandibular plane angles (low, average, high) were collected. A finite elemental combination model of a dental implant was constructed. The orthogonal experimental research was designed. Results followed data collection and analysis...
October 1, 2016: Hua Xi Kou Qiang Yi Xue za Zhi, Huaxi Kouqiang Yixue Zazhi, West China Journal of Stomatology
https://www.readbyqxmd.com/read/28325640/computed-tomography-based-3-dimensional-finite-element-analyses-of-various-types-of-plates-placed-for-a-virtually-reduced-unilateral-condylar-fracture-of-the-mandible-of-a-patient
#16
Kazuhiro Murakami, Kazuhiko Yamamoto, Tsutomu Sugiura, Satoshi Horita, Yumiko Matsusue, Tadaaki Kirita
PURPOSE: This study was performed to evaluate stresses in various types of plates placed for a virtually reduced unilateral condylar fracture of the mandible using computed tomography-based 3-dimensional finite element (FE) models of a patient to select the optimal plate system. MATERIALS AND METHODS: A computed tomography-based FE model of the mandible of a patient with a unilateral condylar fracture was constructed. The fracture was virtually reduced and fixed with 1 straight titanium plate; 2 straight titanium plates; 2 straight poly-L-lactic acid plates; and 4-hole (box), 5-hole (strut), and 7-hole (lambda) condylar plates...
February 24, 2017: Journal of Oral and Maxillofacial Surgery
https://www.readbyqxmd.com/read/28324978/influence-of-electrode-configuration-on-the-electric-field-distribution-during-transcutaneous-spinal-direct-current-stimulation-of-the-cervical-spine
#17
Sofia R Fernandes, Ricardo Salvador, Cornelia Wenger, Mamede A de Carvalho, Pedro C Miranda
Transcutaneous spinal direct current stimulation (tsDCS) is a recent technique with promising neuromodulatory effects on spinal neuronal circuitry. The main objective of the present study was to perform a finite element analysis of the electric field distribution in tsDCS in the cervical spine region, with varying electrode configurations and geometry. A computational model of a human trunk was generated with nine tissue meshes. Three electrode configurations were tested: A) rectangular saline-soaked sponge target and return electrodes placed over C3 and T3 spinous processes, respectively; B1) circular saline-soaked sponge target and return electrodes placed over C7 spinous process and right deltoid muscle, respectively; B2) same configuration as B1, considering circular shaped electrodes with sponge and rubber layers and a small circular connector on the top surface...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28324958/ultrafast-oscillatory-flow-pcr-for-amplication-of-urine-short-tandem-repeats
#18
Haoyu Tang, Tao Dong
The short tandem repeats (STRs) in human urine which is the most sensitive body fluid can be serviced as biomarkers for the individual identification. PCR microchips are automated, sensitive and rapid. In this report, COMSOL with Finite Element Analysis (FEA) is employed to study the temperature distribution of the base layer to optimize the structure of the microfluidic chip. Meanwhile, the oscillatory PCR microdevice is preliminary tested by DNA samples extracted from urine with the FTA papers and CSF1PO, TPOX, TH01 Multiplex kits...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28323704/minimizing-pedicle-screw-pullout-risks-a-detailed-biomechanical-analysis-of-screw-design-and-placement
#19
Rohan-Jean Bianco, Pierre-Jean Arnoux, Eric Wagnac, Jean-Marc Mac-Thiong, Carl-Éric Aubin
STUDY DESIGN: Detailed biomechanical analysis of the anchorage performance provided by different pedicle screw designs and placement strategies under pullout loading. OBJECTIVE: To biomechanically characterize the specific effects of surgeon-specific pedicle screw design parameters on anchorage performance using a finite element model. SUMMARY OF BACKGROUND DATA: Pedicle screw fixation is commonly used in the treatment of spinal pathologies...
April 2017: Clinical Spine Surgery
https://www.readbyqxmd.com/read/28323703/biomechanical-effects-of-human-lumbar-discography-in-vitro-experiments-and-their-finite-element-validation
#20
Kristen E Lipscomb, Nesrin Sarigul-Klijn, Eric Klineberg, Vivek Mohan
STUDY DESIGN: An experimental and computational finite element analysis of human lumbar spine discography and its resulting effects on disk biomechanics. OBJECTIVE: To characterize the changes in stress and displacement of the human lumbar spine disks after puncture due to discography. SUMMARY OF BACKGROUND DATA: Discography of the intervertebral disk (IVD) may be used to diagnose pathology of the disk and determine whether it may be a source for chronic back pain...
April 2017: Clinical Spine Surgery
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