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tensile stress

M Edama, I Kageyama, M Nakamura, T Kikumoto, E Nakamura, W Ito, T Takabayashi, T Inai, H Onishi
In this study, detailed investigations of the shape of the inferior patellar pole, the site of the patellar tendon attachment, and the length and course of the patellar tendon were performed with the aim of examining the anatomical factors involved in the developmental mechanism of patellar tendinitis.  The investigation examined 100 legs from 50 cadavers. The inferior patellar pole was classified into three types: Pointed, Intermediate, and Blunt. The attachment of the patellar tendon to the inferior patellar pole was classified into two types: an anterior and a posterior...
February 16, 2017: Scandinavian Journal of Medicine & Science in Sports
Zhongrui Li, Zhiyong Liang
A series of flattened-nanotube reinforced thermoplastic composites are sizably fabricated as a function of buckypaper loading. The effects of the volume fraction, nanotube alignment and length on the tensile performance of the composites are factored into a general expression. The incorporation of self-reinforcing polyphenylene resin (Parmax) into a highly aligned buckypaper frame at an optimal weight ratio boosts the tensile strength and Young's modulus of the buckypaper/Parmax composite to 1145 MPa and 150 GPa, respectively, far exceeding those of Parmax and aligned buckypaper individually...
February 13, 2017: Scientific Reports
Bohayra Mortazavi, Masoud Shahrokhi, Meysam Makaremi, Timon Rabczuk
Transition metal carbides include a wide variety of materials with attractive properties that are suitable for numerous and diverse applications. A most recent experimental advance could provide a path toward the successful synthesis of large-area and high-quality ultrathin Mo2C membranes with superconducting properties. In the present study, we used first-principles density functional theory calculations to explore the mechanical and optical response of single-layer and free-standing Mo2C. Uniaxial tensile simulations along the armchair and zigzag directions were conducted and we found that while the elastic properties are close along various loading directions, the nonlinear regimes in stress-strain curves are considerably different...
February 16, 2017: Nanotechnology
Ho Yong Um, Byung Ho Park, Dong-Hyun Ahn, Mohamed Ibrahim Abd El Aal, Jaechan Park, Hyoung Seop Kim
Severe plastic deformation (SPD) has recently been advanced as the main process for fabricating bulk ultrafine grained or nanocrystalline metallic materials, which present much higher strength and better bio-compatibility than coarse-grained counterparts. Medical devices, such as aneurysm clips and dental implants, require high mechanical and biological performance (e.g., stiffness, yield strength, fatigue resistance, and bio-compatibility). These requirements match well the characteristics of SPD-processed materials...
February 6, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Atsushi Kubo, Yoshitaka Umeno
Experiments of crack propagation in rubbers have shown that a discontinuous jump of crack propagation velocity can occur as energy release rate increases, which is known as the "mode transition" phenomenon. Although it is believed that the mode transition is strongly related to the mechanical properties, the nature of the mode transition had not been revealed. In this study, dynamic crack propagation on an elastomer was investigated using the finite element method (FEM) with a hyperviscoelastic material model...
February 10, 2017: Scientific Reports
Yu Chai, Shanshan Su, Dong Yan, Mihrimah Ozkan, Roger Lake, Cengiz S Ozkan
Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS2 (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS2 field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area...
February 10, 2017: Scientific Reports
Qi Xing, Zichen Qian, Mitchell Tahtinen, Ai Hui Yap, Keegan Yates, Feng Zhao
There is a large demand for tissue engineered vascular grafts for the application of vascular reconstruction surgery or in vitro drug screening tissue model. The extracellular matrix (ECM) composition along with the structural and mechanical anisotropy of native blood vessels is critical to their functional performance. The objective of this study is to develop a biomimetic vascular graft recapitulating the anisotropic features of native blood vessels by employing nanofibrous aligned fibroblast-derived ECM and human mesenchymal stem cells (hMSCs)...
February 9, 2017: Advanced Healthcare Materials
Sudhanshu Shekhar Behera, Urmimala Das, Awanish Kumar, Akalabya Bissoyi, Abhishek Kumar Singh
The microbial infection and growth of fibroblasts are the critical factors for the effective wound healing. The natural polymer-based dressing membranes may mimic extracellular matrix to support the survival, proliferation and differentiation of fibroblasts. The present study deals with the preparation of chitosan/titanium dioxide (CS/TiO2) composite membranes with different degree of TiO2 incorporation, and their characterization in terms of morphology, ultrastructure, thermal behavior and mechanical properties with SEM, FTIR, XRD and tensile strength analyses...
February 4, 2017: International Journal of Biological Macromolecules
Kuan Wang, Huihao Wang, Zhen Deng, Zhengyan Li, Hongsheng Zhan, Wenxin Niu
BACKGROUND: Cervical traction is commonly used for treating neck pain. However, few studies have investigated the biomechanical impact such traction has on soft tissues. OBJECTIVES: To analyze the biomechanics of cervical traction therapy in a supine position with and without neck support (NS and non-NS). METHODS: A finite element model of the cervical spine was constructed to investigate the mechanism behind cervical traction therapy. An axial traction force of 100-N was loaded on the upper surface of C0 to simulate traction weight...
January 16, 2017: Musculoskelet Sci Pract
Wen Li, Yanhui Liu, Wanghui Ding, Tan Long, Jiejun Shi
OBJECTIVE: To study the protein expression of HIF-2α in condylar chondrocytes under the different stress loading, to investigate the possible effects of HIF-2α involved in the mortality of condylar chondrocytes under overloaded- stress. MATERIALS AND METHODS: Chondrocytes were isolated from TMJ condylar cartilage and cultured in hypoxia-incubator. Chondrocytes were divided into 4 groups: 0, 1000, 2000, 3000 ustrain group, which was subjected to cyclic tensile strain (CTS) of 0...
January 18, 2017: Archives of Oral Biology
Kai Xu, Lara A Kuntz, Peter Foehr, Katharina Kuempel, Alexandra Wagner, Jutta Tuebel, Constantin V Deimling, Rainer H Burgkart
Interfaces between tendon/ligament and bone ("entheses") are highly specialized tissues that allow for stress transfer between mechanically dissimilar materials. Entheses show very low regenerative capacity resulting in high incidences of failure after surgical repair. Tissue engineering is a promising approach to recover functionality of entheses. Here, we established a protocol to decellularize porcine entheses as scaffolds for enthesis tissue engineering. Chemical detergents as well as physical treatments were investigated with regard to their efficiency to decellularize 2 mm thick porcine Achilles tendon entheses...
2017: PloS One
Nuša Pukšič, Monika Jenko, Matjaž Godec, Paul J McGuiness
While a lot is known about the deformation of metallic surfaces from experiments, elasticity theory and simulations, this investigation represents the first molecular-dynamics-based simulation of uniaxial deformation for the vicinal surfaces in a comparison of copper and nickel. These vicinal surfaces are composed of terraces divided by equidistant, mono-atomic steps. The periodicity of vicinals makes them good candidates for the study of the surface steps' influences on surface dynamics. The simulations of tensile and compressive uniaxial deformations were performed for the (1 1 19) vicinal surfaces...
February 7, 2017: Scientific Reports
Adam B Rosen, Jupil Ko, Kathy J Simpson, Cathleen N Brown
OBJECTIVE: To determine if patellar tendon straps altered quadriceps' muscle activity during a drop-jump landing in males with and without patellar tendinopathy. DESIGN: Case-control. SETTINGS: Biomechanics Research Laboratory. PARTICIPANTS: Twenty recreationally-active males participated: ten (age = 21.3 ± 2.4 years, height = 182.8 ± 5.3 cm, mass = 81.7 ± 8.6 kg) with patellar tendinopathy; ten (age = 22...
September 13, 2016: Physical Therapy in Sport
Sonia Bansal, Sai Mandalapu, Céline Aeppli, Feini Qu, Spencer E Szczesny, Robert L Mauck, Miltiadis H Zgonis
: The meniscus is comprised of circumferentially aligned fibers that resist the tensile forces within the meniscus (i.e., hoop stress) that develop during loading of the knee. Although these circumferential fibers are severed by radial meniscal tears, tibial contact stresses do not increase until the tear reaches ∼90% of the meniscus width, suggesting that the severed circumferential fibers still bear load and maintain the mechanical functionality of the meniscus. Recent data demonstrates that the interfibrillar matrix can transfer strain energy to disconnected fibrils in tendon fascicles...
January 31, 2017: Acta Biomaterialia
Hsi-Chao Chen, Po-Wei Cheng, Kuo-Ting Huang
Transparent conductive Al-doped ZnO (AZO) thin films were deposited on polyethylene terephthalate (PET) and polycarbonate (PC) substrates using radio frequency (RF) magnetron sputtering. The biaxial stress was measured with a double beam shadow moiré interferometer, and x-ray diffraction (XRD) was used to investigate the crystal orientation of ZnO. The substrate temperature was varied from room temperature to 150°C in steps of 25°C. The experimental results showed that the residual and shearing stresses increased with the increase in substrate temperature...
February 1, 2017: Applied Optics
Jinlong Zhang, Xiaoqing Bu, Bin Ma, Hongfei Jiao, Xinbin Cheng, Zhanshan Wang
The thermomechanical property of the hafnium/silica antireflection (AR) coatings on lithium triborate (LBO) crystal was investigated by simulation and experiment. From the analysis of the stress and fracture toughness, it was found that the crack originated due to the high tensile stress in hafnium coating. Then we proposed the approaches of decreasing the deposition temperature and substituting the hafnium layers with alumina to improve the mechanical stability of AR coatings on LBO crystals, and cracks were effectively suppressed...
February 1, 2017: Applied Optics
Masashi Takegami, Ryota Nakano, Hiroshi Murotani
The time variation in the internal stress of optical thin films composed of lanthanum titanium oxide (H4) deposited by ion-beam assisted deposition (IAD) and electron beam deposition was observed over a period of 10 years after deposition, and it was found that the internal stresses in the optical thin films can be controlled by optimizing the IAD conditions. Both tensile stress and compressive stress could be created by IAD, and the chemical bonding state of Ti may affect the stress behavior. The network size of the chemical bonds may affect the stress direction...
February 1, 2017: Applied Optics
Wei-Bo Liao, Ya-Chen Chang, Cheng-Chung Jaing, Ching-Long Cheng, Cheng-Chung Lee, Hung-Sen Wei, Chien-Cheng Kuo
SiO<sub>x</sub>C<sub>y</sub> thin films were deposited by plasma polymerization. The stress of the deposited SiO<sub>x</sub>C<sub>y</sub> thin films can be modified by adjusting the beam current, the anode voltage, and the flow rate of hexamethyldisiloxane (HMDSO) gas and oxygen. Reducing the beam current or increasing the flow rate of HMDSO gas increased the linear/cage structure ratio and turned the stress of the SiO<sub>x</sub>C<sub>y</sub> thin films from compressive to tensile...
February 1, 2017: Applied Optics
Svetlana Shestaeva, Astrid Bingel, Peter Munzert, Lilit Ghazaryan, Christian Patzig, Andreas Tünnermann, Adriana Szeghalmi
Structural, optical, and mechanical properties of Al<sub>2</sub>O<sub>3</sub>, SiO<sub>2</sub>, and HfO<sub>2</sub> materials prepared by plasma-enhanced atomic layer deposition (PEALD) were investigated. Residual stress poses significant challenges for optical coatings since it may lead to mechanical failure, but in-depth understanding of these properties is still missing for PEALD coatings. The tensile stress of PEALD alumina films decreases with increasing deposition temperature and is approximately 100 MPa lower than the stress in thermally grown films...
February 1, 2017: Applied Optics
Mauro Fittipaldi, Landon R Grace
The thermoplastic elastomer Poly(Styrene-block-Isobutylene-block-Styrene) (SIBS) is highly biocompatible, which has led to its use in several commercially-available implants. However, lipid-induced degradation has been previously identified as a primary cause of failure in long-term SIBS implants subject to mechanical loading. Thus, understanding the mechanisms and extent of lipid-induced damage and the role of styrene-isobutylene ratio and molecular weight is critical to improving longevity of SIBS-based implants in order to fully exploit the biocompatibility advantages...
January 24, 2017: Journal of the Mechanical Behavior of Biomedical Materials
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