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https://www.readbyqxmd.com/read/29156631/morphology-and-mechanical-properties-of-polyimide-films-the-effects-of-uv-irradiation-on-microscale-surface
#1
Changzi Qu, Junsong Hu, Xing Liu, Zheng Li, Yanhuai Ding
As an attractive dielectric material, polyimide has been widely used in the field of electronics, aerospace, and automobiles due to its useful mechanical properties and good chemical resistance. UV irradiation was considered to be the main factor related to the damage and failure of polyimide. Here the effects of UV irradiation on the surface morphology and microscale mechanical properties of polyimide films are characterized by atomic force microscopy (AFM). The surface roughness of the UV-irradiated samples developed and the mechanical properties degraded with the radiation dose increased...
November 20, 2017: Materials
https://www.readbyqxmd.com/read/29155558/correlated-absorption-and-scattering-spectroscopy-of-individual-pt-decorated-au-nanorods-reveals-strong-excitation-enhancement-in-the-non-plasmonic-metal
#2
Anneli Joplin, Seyyed Ali Hosseini Jebeli, Eric Sung, Nathan Diemler, Patrick J Straney, Mustafa Yorulmaz, Wei-Shun Chang, Jill E Millstone, Stephan Link
Bimetallic nanocatalysts have the potential to surmount current limitations in industrial catalysis if their electronic and optical properties can be effectively controlled. However, improving the performance of bimetallic photocatalysts requires a functional understanding of how the intricacies of their morphology and composition dictate every element of their optical response. In this work, we examine Au and Pt-decorated Au nanorods on a single particle level to ascertain how Pt influences the plasmon resonance of the bimetallic nanostructure...
November 20, 2017: ACS Nano
https://www.readbyqxmd.com/read/29154211/quasi-static-and-dynamic-motions-of-the-columellar-footplate-in-ostrich-struthio-camelus-measured-ex%C3%A2-vivo
#3
Pieter G G Muyshondt, Raf Claes, Peter Aerts, Joris J J Dirckx
The nature of the movement of the columellar footplate (CFP) in birds is still a matter of ongoing debate. Some sources claim that rocking motion is dominant, while others propose a largely piston-like motion. In this study, motions of the CFP are experimentally investigated in the ostrich using a post-mortem approach. For quasi-static loads, micro-CT scans of ostrich heads were made under positive and negative middle-ear pressures of 1 kPa. For dynamic loads, laser Doppler vibrometry was used to measure the velocity on multiple locations of the CFP as a function of excitation frequency from 0...
November 9, 2017: Hearing Research
https://www.readbyqxmd.com/read/29154046/simulation-of-guided-wave-ultrasound-propagation-in-composite-laminates-benchmark-comparisons-of-numerical-codes-and-experiment
#4
Cara A C Leckey, Kevin R Wheeler, Vasyl N Hafiychuk, Halyna Hafiychuk, Doğan A Timuçin
Ultrasonic wave methods constitute the leading physical mechanism for nondestructive evaluation (NDE) and structural health monitoring (SHM) of solid composite materials, such as carbon fiber reinforced polymer (CFRP) laminates. Computational models of ultrasonic wave excitation, propagation, and scattering in CFRP composites can be extremely valuable in designing practicable NDE and SHM hardware, software, and methodologies that accomplish the desired accuracy, reliability, efficiency, and coverage. The development and application of ultrasonic simulation approaches for composite materials is an active area of research in the field of NDE...
November 4, 2017: Ultrasonics
https://www.readbyqxmd.com/read/29153706/load-sharing-in-the-lumbosacral-spine-in-neutral-standing-flexed-postures-a-combined-finite-element-and-inverse-static-study
#5
Tao Liu, Kinda Khalaf, Sadegh Naserkhaki, Marwan El-Rich
Understanding load-sharing in the spine during in-vivo conditions is critical for better spinal implant design and testing. Previous studies of load-sharing that considered actual spinal geometry applied compressive follower load, with or without moment, to simulate muscle forces. Other studies used musculoskeletal models, which include muscle forces, but model the discs by simple beams or spherical joints and ignore the articular facet joints. This study investigated load-sharing in neutral standing and flexed postures using a detailed Finite Element (FE) model of the ligamentous lumbosacral spine, where muscle forces, gravity loads and intra-abdominal pressure, as predicted by a musculoskeletal model of the upper body, are input into the FE model...
November 6, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/29152021/forging-property-processing-map-and-mesoscale-microstructural-evolution-modeling-of-a-ti-17-alloy-with-a-lamellar-%C3%AE-%C3%AE-starting-microstructure
#6
Hiroaki Matsumoto, Daiki Naito, Kento Miyoshi, Kenta Yamanaka, Akihiko Chiba, Yoko Yamabe-Mitarai
This work identifies microstructural conversion mechanisms during hot deformation (at temperatures ranging from 750 °C to 1050 °C and strain rates ranging from 10(-3) s(-1) to 1 s(-1)) of a Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti-17) alloy with a lamellar starting microstructure and establishes constitutive formulae for predicting the microstructural evolution using finite-element analysis. In the α phase, lamellae kinking is the dominant mode in the higher strain rate region and dynamic globularization frequently occurs at higher temperatures...
2017: Science and Technology of Advanced Materials
https://www.readbyqxmd.com/read/29151673/the-perfectly-matched-layer-absorbing-boundary-for-fluid-structure-interactions-using-the-immersed-finite-element-method
#7
Jubiao Yang, Feimi Yu, Michael Krane, Lucy T Zhang
In this work, a non-reflective boundary condition, the Perfectly Matched Layer (PML) technique, is adapted and implemented in a fluid-structure interaction numerical framework to demonstrate that proper boundary conditions are not only necessary to capture correct wave propagations in a flow field, but also its interacted solid behavior and responses. While most research on the topics of the non-reflective boundary conditions are focused on fluids, little effort has been done in a fluid-structure interaction setting...
January 2018: Journal of Fluids and Structures
https://www.readbyqxmd.com/read/29151621/error-analysis-for-discretizations-of-parabolic-problems-using-continuous-finite-elements-in-time-and-mixed-finite-elements-in-space
#8
Markus Bause, Florin A Radu, Uwe Köcher
Variational time discretization schemes are getting of increasing importance for the accurate numerical approximation of transient phenomena. The applicability and value of mixed finite element methods in space for simulating transport processes have been demonstrated in a wide class of works. We consider a family of continuous Galerkin-Petrov time discretization schemes that is combined with a mixed finite element approximation of the spatial variables. The existence and uniqueness of the semidiscrete approximation and of the fully discrete solution are established...
2017: Numer Math (Heidelb)
https://www.readbyqxmd.com/read/29151459/the-ball-on-disk-cyclic-wear-of-cad-cam-machinable-dental-composite-and-ceramic-materials
#9
Kazuyuki Handa, Natsuko Murakami, Toshiki Yamazaki, Hidekazu Takahashi, Noriyuki Wakabayashi
The purpose of this study was to investigate the wear volume and the principal strain of machinable dental composite and ceramics in simulated mastication. A ball-on-disk wear test was performed for 3,000 cycles in water, using nine ball/disk combinations of three commercial CAD/CAM materials: feldspathic, lithium disilicate glass ceramics, and a highly loaded composite material (n = 7 for each combination). The wear volume was optically measured using a digital scanner and analyzed for statistical differences based on the materials (α = 0...
November 17, 2017: Journal of Oral Science
https://www.readbyqxmd.com/read/29150765/finite-element-design-optimization-of-a-hyaluronic-acid-based-hydrogel-drug-delivery-device-for-improved-retention
#10
Jourdan Colter, Barbara Wirostko, Brittany Coats
Drug-loaded hydrogel devices are emerging as an effective means of localized and sustained drug delivery for the treatment of corneal conditions and injuries. One such device uses a novel, thiolated crosslinked carboxymethylated, hyaluronic acid-based hydrogel (CMHA-S) film to deliver drug to the ocular surface upon placement into the inferior fornix of the eye. While proven to be very safe and effective, the CMHA-S film tends to dislodge in the highly-lubricated ocular environment, thereby reducing drug delivery efficiency and drug efficacy...
November 17, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/29150134/stress-generation-in-mandibular-anterior-teeth-restored-with-different-types-of-post-and-core-at-various-levels-of-ferrule
#11
Anatolii Savychuk, Marianthi Manda, Christos Galanis, Christofer Provatidis, Petros Koidis
STATEMENT OF PROBLEM: Pertinent evidence regarding the mechanical integrity of mandibular anterior teeth restored with a post-and-core is limited. PURPOSE: The purpose of this finite element analysis study was to compare the impact of the post type (glass fiber post-and-resin core or cast post-and-core) along with the ferrule effect on the stress fields generated in endodontically treated mandibular lateral incisors and canines. MATERIAL AND METHODS: Three-dimensional models of the segmented mandible were developed...
November 15, 2017: Journal of Prosthetic Dentistry
https://www.readbyqxmd.com/read/29148579/a-step-by-step-review-on-patient-specific-biomechanical-finite-element-models-for-breast-mri-to-x-ray-mammography-registration
#12
REVIEW
Eloy García, Yago Diez, Oliver Diaz, Xavier Lladó, Robert Martí, Joan Martí, Arnau Oliver
Breast magnetic resonance imaging (MRI) and X-ray mammography are two image modalities widely used for the early detection and diagnosis of breast diseases in women. The combination of these modalities leads to a more accurate diagnosis and treatment of breast diseases. The aim of this paper is to review the registration between breast MRI and X-ray mammographic images using patient-specific finite element-based biomechanical models. Specifically, a biomechanical model is obtained from the patient's MRI volume and is subsequently used to mimic the mammographic acquisition...
November 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/29147717/the-role-of-hierarchical-design-and-morphology-in-the-mechanical-response-of-diatom-inspired-structures-via-simulation
#13
Alejandro Gutiérrez, Metin G Guney, Gary K Fedder, Lilian P Dávila
Diatoms are microscopic algae with intricate shell morphologies and features ranging from the nanometer to the micrometer scale, which have been proposed as templates for drug delivery carriers, optical devices, and metamaterials design. Several studies have found that diatom shells show unique mechanical properties such as high specific strength and resilience. One hypothesis is that these properties stem from the structural arrangement of the material at the nanometer and micrometer length scales, challenging the concept between what constitutes a "material" versus a "structure"...
November 17, 2017: Biomaterials Science
https://www.readbyqxmd.com/read/29146077/finite-analytic-method-for-modeling-variably-saturated-flows
#14
Zaiyong Zhang, Wenke Wang, Chengcheng Gong, Tian-Chyi Jim Yeh, Zhoufeng Wang, Yu-Li Wang, Li Chen
This paper develops a finite analytic method (FAM) for solving the two-dimensional Richards' equation. The FAM incorporates the analytic solution in local elements to formulate the algebraic representation of the partial differential equation of unsaturated flow so as to effectively control both numerical oscillation and dispersion. The FAM model is then verified using four examples, in which the numerical solutions are compared with analytical solutions, solutions from VSAFT2, and observational data from a field experiment...
November 13, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29145437/assessment-of-the-suitability-of-biodegradable-rods-for-use-in-posterior-lumbar-fusion-an-in-vitro-biomechanical-evaluation-and-finite-element-analysis
#15
Fon-Yih Tsuang, Yueh-Ying Hsieh, Yi-Jie Kuo, Chia-Hsien Chen, Feng-Huei Lin, Chen-Sheng Chen, Chang-Jung Chiang
Interbody fusion with posterior instrumentation is a common method for treating lumbar degenerative disc diseases. However, the high rigidity of the fusion construct may produce abnormal stresses at the adjacent segment and lead to adjacent segment degeneration (ASD). As such, biodegradable implants are becoming more popular for use in orthopaedic surgery. These implants offer sufficient stability for fusion but at a reduced stiffness. Tailored to degrade over a specific timeframe, biodegradable implants could potentially mitigate the drawbacks of conventional stiff constructs and reduce the loading on adjacent segments...
2017: PloS One
https://www.readbyqxmd.com/read/29144991/finite-element-simulation-on-posterior-tibial-tendinopathy-load-transfer-alteration-and-implications-to-the-onset-of-pes-planus
#16
Duo Wai-Chi Wong, Yan Wang, Aaron Kam-Lun Leung, Ming Yang, Ming Zhang
BACKGROUND: Posterior tibial tendinopathy is a challenging foot condition resulting in pes planus, which is difficult to diagnose in the early stage. Prior to the deformity, abnormal internal load transfer and soft tissue attenuation are anticipated. The objective of this study was to investigate the internal load transfer and strain of the ligaments with posterior tibial tendinopathy, and the implications to pes planus and other deformities. METHODS: A three-dimensional finite element model of the foot and ankle was reconstructed from magnetic resonance images of a 28-year-old normal female...
November 3, 2017: Clinical Biomechanics
https://www.readbyqxmd.com/read/29144380/a-passive-and-wireless-sensor-for-bone-plate-strain-monitoring
#17
Yisong Tan, Jiale Hu, Limin Ren, Jianhua Zhu, Jiaqi Yang, Di Liu
This paper reports on a sensor for monitoring bone plate strain in real time. The detected bone plate strain could be used for judging the healing state of fractures in patients. The sensor consists of a magnetoelastic material, which can be wirelessly connected and passively embedded. In order to verify the effectiveness of the sensor, a tibia-bone plate-screw (TBS) model was established using the finite element analysis method. A variation of the bone plate strain was obtained via this model. A goat hindquarter tibia was selected as the bone fracture model in the experiment...
November 16, 2017: Sensors
https://www.readbyqxmd.com/read/29144308/numerical-simulation-of-filtration-performance-in-submerged-membrane-bioreactors-effect-of-particle-packed-structure
#18
Zhidong Wang, Kuizu Su, Tong Shu, Weihong Wang
It is widely known that the accumulation of solid matter forming a cake layer on the membrane surface is one of the major limitations of the filtration performance in submerged membrane bioreactors (SMBR). This study is focused on the influence of the cake porosity of different particle microscopic packed structures on the filtration performance of hollow fiber systems. An integrated model based on the finite element method to simulate numerically the flow in an SMBR is presented. The model coupled the Navier-Stokes and Darcy Brinkman equations to simulate a complete filtration run...
November 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/29143828/large-stretchability-and-failure-mechanism-of-graphene-kirigami-under-tension
#19
Zhujiang Hua, Yang Zhao, Shuhong Dong, Peishi Yu, Yu Liu, Ning Wei, Junhua Zhao
From the macro- to the nanoscale, kirigami structures show novel and tunable properties by tailoring the original two-dimensional sheets. In this study, the large stretchability and failure behavior in graphene nanoribbon kirigami (GNR-k) are obtained using the finite element (FE) method and molecular dynamics (MD) simulations. The carbon-carbon bond in the FE method is equivalent to a nonlinear Timoshenko beam based on the Tersoff-Brenner potential. All the results from the present FE method are in reasonable agreement with those from our MD simulations using the REBO potential...
November 16, 2017: Soft Matter
https://www.readbyqxmd.com/read/29142645/effect-of-implant-and-occlusal-load-location-on-stress-distribution-in-locator-attachments-of-mandibular-overdenture-a-finite-element-study
#20
Angel Alvarez-Arenal, Ignacio Gonzalez-Gonzalez, Hector deLlanos-Lanchares, Elena Martin-Fernandez, Aritza Brizuela-Velasco, Joseba Ellacuria-Echebarria
PURPOSE: The aim of this study is to evaluate and compare the stress distribution in Locator attachments in mandibular two-implant overdentures according to implant locations and different loading conditions. MATERIALS AND METHODS: Four three-dimensional finite element models were created, simulating two osseointegrated implants in the mandible to support two Locator attachments and an overdenture. The models simulated an overdenture with implants located in the position of the level of lateral incisors, canines, second premolars, and crossed implant...
October 2017: Journal of Advanced Prosthodontics
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