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https://www.readbyqxmd.com/read/28722129/bone-strength-estimated-by-micro-finite-element-analysis-%C3%A2%C2%B5fea-is-heritable-and-shares-genetic-predisposition-with-areal-bmd-the-framingham-study
#1
David Karasik, Serkalem Demissie, Darlene Lu, Kerry E Broe, Steven K Boyd, Ching-Ti Liu, Yi-Hsiang Hsu, Mary L Bouxsein, Douglas P Kiel
Genetic factors contribute to the risk of bone fractures, partly because of effects on bone strength. High-resolution peripheral quantitative computed tomography (HR-pQCT) estimates bone strength using micro-finite element analysis (µFEA). The goal of this study was to investigate if the bone failure load estimated by HR-pQCT-based µFEA is heritable and to what extent it shares genetic regulation with areal bone mineral density (aBMD). Bone microarchitecture was measured by HR-pQCT at the ultradistal tibia and ultradistal radius in adults from the Framingham Heart Study (n = 1087, mean age 72 years; 57% women)...
July 19, 2017: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
https://www.readbyqxmd.com/read/28721951/recording-characteristics-of-electrical-impedance-myography-needle-electrodes
#2
Hyeuknam Kwon, Seward B Rutkove, Benjamin Sanchez
OBJECTIVE: The neurology and physiatry community need improved tools for the evaluation of skeletal muscle condition. Here, we evaluate needle electrical impedance myography (EIM), a new minimally invasive approach to determine muscle status that could ultimately become a bedside tool for the assessment of neuromuscular disorders. APPROACH: We design and study the recording characteristics of tetrapolar EIM needle electrodes combining theory and finite element model simulations...
July 19, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28721606/fluid-structure-finite-element-modelling-and-clinical-measurement-of-the-wideband-acoustic-input-admittance-of-the-newborn-ear-canal-and-middle-ear
#3
Hamid Motallebzadeh, Nima Maftoon, Jacob Pitaro, W Robert J Funnell, Sam J Daniel
The anatomical differences between the newborn ear and the adult one result in different input admittance responses in newborns than those in adults. Taking into account fluid-structure interactions, we have developed a finite-element model to investigate the wideband admittance responses of the ear canal and middle ear in newborns for frequencies up to 10 kHz. We have also performed admittance measurements on a group of 23 infants with ages between 14 and 28 days, for frequencies from 250 to 8000 Hz with 1/12-octave resolution...
July 18, 2017: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/28721473/biomechanics-of-the-classic-metaphyseal-lesion-finite-element-analysis
#4
Andy Tsai, Brittany Coats, Paul K Kleinman
BACKGROUND: The classic metaphyseal lesion (CML) is strongly associated with infant abuse, but the biomechanics responsible for this injury have not been rigorously studied. Radiologic and CT-pathological correlates show that the distal tibial CML always involves the cortex near the subperiosteal bone collar, with variable extension of the fracture into the medullary cavity. Therefore, it is reasonable to assume that the primary site of bone failure is cortical, rather than intramedullary...
July 18, 2017: Pediatric Radiology
https://www.readbyqxmd.com/read/28720340/mechanical-strength-and-fracture-point-of-a-dental-implant-under-certification-conditions-a-numerical-approach-by-finite-element-analysis
#5
Guillermo de la Rosa Castolo, Sonia V Guevara Perez, Pierre-Jean Arnoux, Laurent Badih, Franck Bonnet, Michel Behr
STATEMENT OF PROBLEM: Implant prosthodontics provides high-quality outcomes thanks to recent technological developments and certification procedures such as International Organization for Standardization (ISO) standard 14801. However, these certification tests are costly, and the result is highly uncertain as the influence of design variables (materials and structure) is still unknown. The design process could be significantly improved if the influence of design parameters were identified...
July 15, 2017: Journal of Prosthetic Dentistry
https://www.readbyqxmd.com/read/28720224/development-of-a-1-0-mm-id-temperature-assisted-focusing-precolumn-for-use-with-2-1-mm-id-columns
#6
Stephen R Groskreutz, Anthony R Horner, Stephen G Weber
On-column solute focusing is a simple and powerful method to decrease the influence of precolumn band spreading and increase the allowable volume injected increasing sensitivity. It relies on creating conditions so that the retention factor, k', is transiently increased during the injection process. Both solvent composition and temperature control can be used to effect solute focusing. In the case of temperature, the release of the transiently delayed solute band requires increasing the temperature rapidly and with a minimum of radial thermal gradients...
July 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28718314/techniques-of-force-and-pressure-measurement-in-the-small-joints-of-the-wrist
#7
Michael J Schreck, Meghan Kelly, Colin D Canham, John C Elfar
BACKGROUND: The alteration of forces across joints can result in instability and subsequent disability. Previous methods of force measurements such as pressure-sensitive films, load cells, and pressure-sensing transducers have been utilized to estimate biomechanical forces across joints and more recent studies have utilized a nondestructive method that allows for assessment of joint forces under ligamentous restraints. METHODS: A comprehensive review of the literature was performed to explore the numerous biomechanical methods utilized to estimate intra-articular forces...
February 1, 2017: Hand: Official Journal of the American Association for Hand Surgery
https://www.readbyqxmd.com/read/28717186/overstepping-the-upper-refractive-index-limit-to-form-ultra-narrow-photonic-nanojets
#8
Guoqiang Gu, Jun Song, Hongda Liang, Mengjie Zhao, Yue Chen, Junle Qu
In general, photonic nanojets (PNJs) occur only when the refractive index (Ri) difference between the microparticle and background media is less than 2. The minimum full width at half-maximum (FWHM) of the PNJ is ~130 nm (approximately one-third of the illumination wavelength λ = 400 nm) formed within the evanescent field region. This paper proposes and studies a method to overstep the Ri upper bound and generate ultra-narrow PNJs. Finite element method based numerical investigations and ray-optics theoretical analyses have realized ultra-narrow PNJs with FWHM as small as 114...
July 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28717163/titin-mediated-thick-filament-activation-through-a-mechanosensing-mechanism-introduces-sarcomere-length-dependencies-in-mathematical-models-of-rat-trabecula-and-whole-ventricle
#9
Lorenzo Marcucci, Takumi Washio, Toshio Yanagida
Recent experimental evidence in skeletal muscle demonstrated the existence of a thick-filament mechanosensing mechanism, acting as a second regulatory system for muscle contraction, in addition to calcium-mediated thin filament regulation. These two systems cooperate to generate force, but the extent to which their interaction is relevant in physiologically contracting muscle was not yet assessed experimentally. Therefore, we included both regulatory mechanisms in a mathematical model of rat trabecula and whole ventricle...
July 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28716401/research-on-the-parallel-load-sharing-principle-of-a-novel-self-decoupled-piezoelectric-six-dimensional-force-sensor
#10
Ying-Jun Li, Cong Yang, Gui-Cong Wang, Hui Zhang, Huan-Yong Cui, Yong-Liang Zhang
This paper presents a novel integrated piezoelectric six-dimensional force sensor which can realize dynamic measurement of multi-dimensional space load. Firstly, the composition of the sensor, the spatial layout of force-sensitive components, and measurement principle are analyzed and designed. There is no interference of piezoelectric six-dimensional force sensor in theoretical analysis. Based on the principle of actual work and deformation compatibility coherence, this paper deduces the parallel load sharing principle of the piezoelectric six-dimensional force sensor...
July 14, 2017: ISA Transactions
https://www.readbyqxmd.com/read/28715192/flexible-semitransparent-energy-harvester-with-high-pressure-sensitivity-and-power-density-based-on-laterally-aligned-pzt-single-crystal-nanowires
#11
Quan-Liang Zhao, Guang-Ping He, Jie-Jian Di, Wei-Li Song, Zhi-Ling Hou, Pei-Pei Tan, Da-Wei Wang, Mao-Sheng Cao
A flexible semitransparent energy harvester is assembled based on laterally aligned Pb(Zr0.52Ti0.48)O3 (PZT) single-crystal nanowires (NWs). Such a harvester presents the highest open-circuit voltage and a stable area power density of up to 10 V and 0.27 μW/cm(2), respectively. A high pressure sensitivity of 0.14 V/kPa is obtained in the dynamic pressure sensing, much larger than the values reported in other energy harvesters based on piezoelectric single-crystal NWs. Furthermore, theoretical and finite element analyses also confirm that the piezoelectric voltage constant g33 of PZT NWs is competitive to the lead-based bulk single crystals and ceramics, and the enhanced pressure sensitivity and power density are substantially linked to the flexible structure with laterally aligned PZT NWs...
July 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28715168/junction-less-diode-enabled-by-self-bias-effect-of-ion-gel-in-single-layer-mos2-device
#12
Muhammad Atif Khan, Servin Rathi, Jinwoo Park, Dongsuk Lim, Yoontae Lee, Sun Jin Yun, Doo Hyeb Youn, Gil-Ho Kim
The self-biasing effects of ion gel from source and drain electrodes on electrical characteristics of single layer and few layer molybdenum disulfide (MoS2) field effect transistor (FET) have been studied. The self-biasing effect of ion gel is tested for two different configurations, covered and open, where ion gel is in contact with either one or both, source and drain electrodes, respectively. In open configuration, the linear output characteristics of the pristine device becomes non-linear and on-off ratio drops by three order of magnitude due to the increase in 'off' current for both single and few layer MoS2 FETs...
July 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28713177/nitsche-s-method-for-helmholtz-problems-with-embedded-interfaces
#13
Zilong Zou, Wilkins Aquino, Isaac Harari
In this work, we use Nitsche's formulation to weakly enforce kinematic constraints at an embedded interface in Helmholtz problems. Allowing embedded interfaces in a mesh provides significant ease for discretization, especially when material interfaces have complex geometries. We provide analytical results that establish the well-posedness of Helmholtz variational problems and convergence of the corresponding finite element discretizations when Nitsche's method is used to enforce kinematic constraints. As in the analysis of conventional Helmholtz problems, we show that the inf-sup constant remains positive provided that the Nitsche's stabilization parameter is judiciously chosen...
May 18, 2017: International Journal for Numerical Methods in Engineering
https://www.readbyqxmd.com/read/28713050/the-biomechanical-impact-of-the-facet-tropism-on-the-intervertebral-disc-and-facet-joints-in-the-cervical-spine
#14
Xin Rong, Beiyu Wang, Chen Ding, Yuxiao Deng, Hua Chen, Yang Meng, Weijie Yan, Hao Liu
BACKGROUND CONTEXT: The facet tropism is defined as the angular difference between the left and right facet orientation. The facet tropism was suggested to be associated with the disc degeneration and facet degeneration in the lumbar spine. However, little is known about the relationship between the facet tropism and pathological changes in the cervical spine and the mechanism behind. PURPOSE: This study was conducted to investigate the biomechanical impact of the facet tropism on the intervertebral disc and facet joints...
July 13, 2017: Spine Journal: Official Journal of the North American Spine Society
https://www.readbyqxmd.com/read/28712877/bone-mass-microarchitecture-and-strength-are-influenced-by-race-ethnicity-in-young-adult-men-and-women
#15
Kristin L Popp, Julie M Hughes, Adriana Martinez-Betancourt, Matthew Scott, Victoria Turkington, Signe Caksa, Katelyn I Guerriere, Kathryn E Ackerman, Chun Xu, Ginu Unnikrishnan, Jaques Reifman, Mary L Bouxsein
Lower rates of fracture in both Blacks compared to Whites, and men compared to women are not completely explained by differences in bone mineral density (BMD). Prior evidence suggests that more favorable cortical bone microarchitecture may contribute to reduced fracture rates in older Black compared to White women, however it is not known whether these differences are established in young adulthood or develop during aging. Moreover, prior studies using high-resolution pQCT (HR-pQCT) have reported outcomes from a fixed-scan location, which may confound sex- and race/ethnicity-related differences in bone structure...
July 13, 2017: Bone
https://www.readbyqxmd.com/read/28711163/effects-of-the-basic-multicellular-unit-and-lamellar-thickness-on-osteonal-fatigue-life
#16
George Pellegrino, Max Roman, J Christopher Fritton
A remodeling cycle sets the size of the osteon and associated lamellae in the basic multicellular unit. Treatments and aging affect these micro-structural features. We previously demonstrated decreased fatigue life with an unexplained mechanism and decreased osteon size in cortical bone treated with high-dose bisphosphonate. Here, three finite element models were examined: type-1: a single osteon, as a homogeneous unit and with heterogeneous lamellae and interlamellae, type-2: a control, interstitial-only tissue and type-3: the osteon with cement line, set within the interstitial tissue...
June 23, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28711162/actin-cytoskeleton-stiffness-grades-metastatic-potential-of-ovarian-carcinoma-hey-a8-cells-via-nanoindentation-mapping
#17
Z L Zhou, X X Sun, J Ma, M H Tong, S K Y To, A S T Wong, A H W Ngan
Recent studies have indicated that the nanoindentation measured stiffness of carcinoma adherent cells is in general lower than normal cells, thus suggesting that cell stiffness may serve as a bio-marker for carcinoma. However, the proper establishment of such a conclusion would require biophysical understanding of the underlying mechanism of the cell stiffness. In this work, we compared the elastic moduli of the actin cytoskeletons of Hey A8 ovarian carcinoma cells with and without metastasis (HM and NM), as measured by 2D atomic force microscopy (AFM) with low-depth nanoindentation via a rate-jump method...
July 5, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28711025/three-dimensional-mechano-electrochemical-model-for-smooth-muscle-contraction-of-the-urinary-bladder
#18
Robert Seydewitz, Robin Menzel, Tobias Siebert, Markus Böl
The urinary bladder is a central organ of vertebrates and imposes, based on its extreme deformation (volume changes up to several 100%), special requirements on the overall bladder tissue. However, studies focusing on three-dimensional modelling of bladder deformation and bladder function during micturition are rare. Based on three fields, namely, the membrane potential, calcium concentration, and placement, a mechano-electrochemical-coupled, three-dimensional model describing the contractile behaviour of urinary bladder smooth muscle is presented using a strain energy function...
April 12, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28710359/computationally-informed-design-of-a-multi-axial-actuated-microfluidic-chip-device
#19
Alessio Gizzi, Sara Maria Giannitelli, Marcella Trombetta, Christian Cherubini, Simonetta Filippi, Adele De Ninno, Luca Businaro, Annamaria Gerardino, Alberto Rainer
This paper describes the computationally informed design and experimental validation of a microfluidic chip device with multi-axial stretching capabilities. The device, based on PDMS soft-lithography, consisted of a thin porous membrane, mounted between two fluidic compartments, and tensioned via a set of vacuum-driven actuators. A finite element analysis solver implementing a set of different nonlinear elastic and hyperelastic material models was used to drive the design and optimization of chip geometry and to investigate the resulting deformation patterns under multi-axial loading...
July 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28709754/nondestructive-mechanical-characterization-of-developing-biological-tissues-using-inflation-testing
#20
P J A Oomen, M A J van Kelle, C W J Oomens, C V C Bouten, S Loerakker
One of the hallmarks of biological soft tissues is their capacity to grow and remodel in response to changes in their environment. Although it is well-accepted that these processes occur at least partly to maintain a mechanical homeostasis, it remains unclear which mechanical constituent(s) determine(s) mechanical homeostasis. In the current study a nondestructive mechanical test and a two-step inverse analysis method were developed and validated to nondestructively estimate the mechanical properties of biological tissue during tissue culture...
July 5, 2017: Journal of the Mechanical Behavior of Biomedical Materials
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