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Bower D, Herbert E, Breedlove KM, Lacy APM, Casa D, Bowman TG. Mechanical characterization of athletic helmet shells. Sports Biomech 2024; 23:241-252. [PMID: 33660587 DOI: 10.1080/14763141.2020.1837926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 10/12/2020] [Indexed: 10/22/2022]
Abstract
Our purpose was to compare the mechanical properties of the protective outer shells of various athletic helmets in their final, fully manufactured form. Sections were taken from 3 different helmet shells (Bauer RE-AKT hockey helmet, Cascade R lacrosse helmet, and Riddell Speedflex football helmet) at 4 different locations (front, side, top, and rear) for a total of 12 test specimens. The 4 specimens from each helmet shell were potted together in epoxy resin moulds and mechanically polished. The hardness, elastic modulus and phase angle were measured using dynamic nanoindentation performed at 100 Hz with an oscillation amplitude of 1 nm (rms). Repeated ANOVA analysis was used to compare each of the dependent variables for each of the 3 helmets across the 4 different locations. The interaction between helmet type and location was significant for hardness (F6,63 = 2.84, P = 0.032, Pη2 = 0.21), elastic modulus (F6,63 = 6.412, P < 0.001, Pη2 = 0.38), and phase angle (F6,63 = 7.65, P < 0.001, Pη2 = 0.42). Polycarbonate has a higher ability to dissipate mechanical energy making it the recommended superior choice for helmet shells. In addition, the results lead us to speculate that manufacturing causes changes in the molecular weight or the distribution of fillers across locations for polyethylene but not for polycarbonate since mechanical properties are fairly uniform over the surface of football helmets, at least within a given helmet.
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Affiliation(s)
- Dane Bower
- Department of Athletic Training, University of Lynchburg, Lynchburg, VA, USA
| | - Erik Herbert
- Materials Science and Engineering, Michigan Technological University, Houghton, MI, USA
| | - Katherine M Breedlove
- Center for Clinical Spectroscopy, Brigham and Women's Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Alicia Pike M Lacy
- Department of Interdisciplinary Health Sciences, A.T. Still University, Mesa, AZ, USA
- Korey Stringer Institute, University of Connecticut, Storrs, CT, USA
| | - Douglas Casa
- Korey Stringer Institute, University of Connecticut, Storrs, CT, USA
- Department of Kinesiology, University of Connecticut, Storrs, CT, USA
| | - Thomas G Bowman
- Department of Athletic Training, University of Lynchburg, Lynchburg, VA, USA
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2
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Kolay J, Zhang P, Zhou X, Wan Z, Chieng A, Wang S. Ligand Binding-Induced Cellular Membrane Deformation is Correlated with the Changes in Membrane Stiffness. J Phys Chem B 2023; 127:9943-9953. [PMID: 37963180 PMCID: PMC10763494 DOI: 10.1021/acs.jpcb.3c06282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Study interaction between ligands and protein receptors is a key step for biomarker research and drug discovery. In situ measurement of cell surface membrane protein binding on whole cells eliminates the cost and pitfalls associated with membrane protein purification. Ligand binding to membrane protein was recently found to induce nanometer-scale cell membrane deformations, which can be monitored with real-time optical imaging to quantify ligand/protein binding kinetics. However, the insight into this phenomenon has still not been fully understood. We hypothesize that ligand binding can change membrane stiffness, which induces membrane deformation. To investigate this, cell height and membrane stiffness changes upon ligand binding are measured using atomic force microscopy (AFM). Wheat germ agglutinin (WGA) is used as a model ligand that binds to the cell surface glycoprotein. The changes in cell membrane stiffness and cell height upon ligand bindings are determined for three different cell lines (human A431, HeLa, and rat RBL-2H3) on two different substrates. AFM results show that cells become stiffer with increased height after WGA modification for all cases studied. The increase in cell membrane stiffness is further confirmed by plasmonic scattering microscopy, which shows an increased cell spring constant upon WGA binding. Therefore, this study provides direct experimental evidence that the membrane stiffness changes are directly correlated with ligand binding-induced cell membrane deformation.
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Affiliation(s)
- Jayeeta Kolay
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287, USA
| | - Pengfei Zhang
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287, USA
| | - Xinyu Zhou
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287, USA
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287, USA
| | - Zijian Wan
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287, USA
- School of Electrical, Energy and Computer Engineering, Arizona State University, Tempe, Arizona 85287, USA
| | - Andy Chieng
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287, USA
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
| | - Shaopeng Wang
- Biodesign Center for Bioelectronics and Biosensors, Arizona State University, Tempe, Arizona 85287, USA
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287, USA
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Alomari EM, Ng KW, Khatri L, Wulff SS. Effect of Physical Properties on Mechanical Behaviors of Sandstone under Uniaxial and Triaxial Compressions. Materials (Basel) 2023; 16:4867. [PMID: 37445181 DOI: 10.3390/ma16134867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 07/03/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023]
Abstract
Mechanical properties of sandstone, such as compressive strength and young's modulus, are commonly used in the design of geotechnical structures and numerical simulation of underground reservoirs using models such as the digital groundwater, equivalent porous medium, and Discrete Fracture Network (DFN) models. A better understanding of the mechanical behaviors of sandstone under different loading conditions is imperative when assessing the stability of geotechnical structures. This paper highlights the effect of the physical properties (i.e., porosity, mean grain size) and environmental conditions (i.e., water content and confining stress) on uniaxial compressive strength, triaxial compressive strength, and young's modulus of sandstone. A series of uniaxial and triaxial compression experiments are conducted on sandstone formations from Wyoming. In addition, experimental data on sandstones from the literature are compiled and integrated into this study. Prediction equations for the compressive strengths and young's modulus of sandstone are established based on commonly available physical properties and known environmental conditions. The results show that the mean Uniaxial Compressive Strength (UCS) decreases as the porosity, water content, and mean grain size increase. Furthermore, a predictive empirical relationship for the triaxial compressive strength is established under different confinements and porosity. The relationship suggests that the mean peak compressive strength increases at a higher confinement and decreases at a higher porosity. The results and recommendations provide a useful framework for evaluating the strength and deformation of most sandstone.
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Affiliation(s)
- Esraa M Alomari
- Department of Civil and Architectural Engineering and Construction Management, University of Wyoming, Laramie, WY 82071, USA
| | - Kam W Ng
- Department of Civil and Architectural Engineering and Construction Management, University of Wyoming, Laramie, WY 82071, USA
| | - Lokendra Khatri
- Department of Civil and Architectural Engineering and Construction Management, University of Wyoming, Laramie, WY 82071, USA
| | - Shaun S Wulff
- Department of Mathematics and Statistics, University of Wyoming, Laramie, WY 82071, USA
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Fathalian M, Postek E, Sadowski T. Mechanical and Electronic Properties of Al(111)/6H-SiC Interfaces: A DFT Study. Molecules 2023; 28:molecules28114345. [PMID: 37298818 DOI: 10.3390/molecules28114345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/07/2023] [Accepted: 05/16/2023] [Indexed: 06/12/2023] Open
Abstract
A density functional theory (DFT) calculation is carried out in this work to investigate the effect of vacancies on the behavior of Al(111)/6H SiC composites. Generally, DFT simulations with appropriate interface models can be an acceptable alternative to experimental methods. We developed two modes for Al/SiC superlattices: C-terminated and Si-terminated interface configurations. C and Si vacancies reduce interfacial adhesion near the interface, while Al vacancies have little effect. Supercells are stretched vertically along the z-direction to obtain tensile strength. Stress-strain diagrams illustrate that the tensile properties of the composite can be improved by the presence of a vacancy, particularly on the SiC side, compared to a composite without a vacancy. Determining the interfacial fracture toughness plays a pivotal role in evaluating the resistance of materials to failure. The fracture toughness of Al/SiC is calculated using the first principal calculations in this paper. Young's modulus (E) and surface energy (Ɣ) is calculated to obtain the fracture toughness (KIC). Young's modulus is higher for C-terminated configurations than for Si-terminated configurations. Surface energy plays a dominant role in determining the fracture toughness process. Finally, to better understand the electronic properties of this system, the density of states (DOS) is calculated.
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Affiliation(s)
- Mostafa Fathalian
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5B, 02-106 Warsaw, Poland
| | - Eligiusz Postek
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5B, 02-106 Warsaw, Poland
| | - Tomasz Sadowski
- Department of Solid Mechanics, Lublin University of Technology, 20-618 Lublin, Poland
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Xu Q, Qiang B, Pan Y, Li J, Zha L, Lu W, Wang J, Li J. ALTERATION IN SHEAR WAVE ELASTOGRAPHY IS ASSOCIATED WITH ACUTE KIDNEY INJURY: A PROSPECTIVE OBSERVATIONAL PILOT STUDY. Shock 2023; 59:375-384. [PMID: 36567550 PMCID: PMC9997638 DOI: 10.1097/shk.0000000000002070] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/06/2022] [Accepted: 12/08/2022] [Indexed: 12/27/2022]
Abstract
ABSTRACT Background: Kidney stiffness could change during kidney disease. We hypothesize that acute kidney injury (AKI) would increase renal stiffness. Therefore, evaluating kidney Young's modulus (YM; a measure of tissue stiffness) using shear wave elastography (SWE) might help to diagnose AKI. Methods: This research was divided into two studies. Study A: Male C57BL/6 mice were used to observe kidney YM changes induced by sepsis-associated AKI, which was established by cecal ligation and puncture (CLP). Study B included 54 consecutive critically ill patients with or without AKI. Changes in renal YM were observed. Results: Study A: CLP mice showed a significantly higher kidney YM compared with the sham group. The YM gradually increased from CLP 0 hours to CLP 24 hours, and presented a fair relationship with the renal tubular injury score ( R2 = 0.71) and serum creatinine ( R2 = 0.73). Study B: YM was easily accessible, and the intraclass correlation coefficient ranged from 0.62 to 0.84. Kidney YM was higher in AKI patients and gradually increased from non-AKI to AKI III patients. Furthermore, the YM in the upper, middle, and lower poles of the renal cortex presented a fair relationship with kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin ( R2 ranging from 0.4 to 0.58), and the areas under the curve of the above five indicators for the diagnosis of AKI were 0.7, 0.73, 0.70, 0.74, and 0.79, respectively. Conclusion: SWE-derived estimates of renal stiffness are higher in AKI patients and sepsis-associated AKI mice. However, it has no advantage over NGAL and KIM-1. Trial Registration: Chinese Clinical Trial Registry No: ChiCTR2200061725. Retrospectively registered July 1, 2022, https://www.chictr.org.cn/showproj.aspx?proj=169359 .
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Affiliation(s)
- Qiancheng Xu
- Department of Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
- Department of Critical Care Medicine, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui, China
- Clinical Research Center of Hubei Critical Care Medicine, Wuhan, Hubei, China
- Anhui Province Clinical Research Center for Critical Respiratory Medicine, Wuhu, Anhui, China
| | - Banghong Qiang
- Department of Ultrasound, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, Anhui, China
| | - Youjun Pan
- Department of Critical Care Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, Anhui, China
| | - Juan Li
- Department of Nephrology, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, Anhui, China
| | - Lei Zha
- Department of Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Weihua Lu
- Department of Critical Care Medicine, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, Anhui, China
- Anhui Province Clinical Research Center for Critical Respiratory Medicine, Wuhu, Anhui, China
| | - Junli Wang
- Department of Ultrasound, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, Anhui, China
| | - Jianguo Li
- Department of Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China
- Clinical Research Center of Hubei Critical Care Medicine, Wuhan, Hubei, China
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Yildirim M, Weiss AV, Schneider M. The Effect of Elasticity of Gelatin Nanoparticles on the Interaction with Macrophages. Pharmaceutics 2023; 15. [PMID: 36678828 DOI: 10.3390/pharmaceutics15010199] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 12/22/2022] [Accepted: 01/03/2023] [Indexed: 01/09/2023] Open
Abstract
Gelatin is a biocompatible, biodegradable, cheap, and nontoxic material, which is already used for pharmaceutical applications. Nanoparticles from gelatin (GNPs) are considered a promising delivery system for hydrophilic and macromolecular drugs. Mechanical properties of particles are recognized as an important parameter affecting drug carrier interaction with biological systems. GNPs offer the preparation of particles with different stiffness. GNPs were loaded with Fluorescein isothiocyanate-labeled 150 kDa dextran (FITC-dextran) yielding also different elastic properties. GNPs were visualized using atomic force microscopy (AFM), and force-distance curves from the center of the particles were evaluated for Young's modulus calculation. The prepared GNPs have Young's moduli from 4.12 MPa for soft to 9.8 MPa for stiff particles. Furthermore, cytokine release (IL-6 and TNF-α), cell viability, and cell uptake were determined on macrophage cell lines from mouse (RAW 264.7) and human (dTHP-1 cells, differentiated human monocytic THP-1 cells) origin for soft and stiff GNPs. Both particle types showed good cell compatibility and did not induce IL-6 and TNF-α release from RAW 264.7 and dTHP-1 cells. Stiffer GNPs were internalized into cells faster and to a larger extent.
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Akazawa T, Miyamoto N, Nishio H, Miyamoto-mikami E, Kinoshita M, Kobayashi Y, Nagao M, Takazawa Y. Age-related changes in mechanical properties of semitendinosus tendon used for anterior cruciate ligament reconstruction. J Orthop Surg Res 2022; 17:501. [DOI: 10.1186/s13018-022-03395-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 11/09/2022] [Indexed: 11/21/2022] Open
Abstract
Background Hamstring tendons are a popular choice for autografts in anterior cruciate ligament (ACL) reconstruction. However, there is increasing evidence that hamstring tendon autografts carry a high risk of revision and residual instability in young patients. To elucidate the reasons for the inferior outcome of the reconstructed ACL with hamstring tendon autografts in young patients, we investigated the Young’s modulus and the extent of cyclic loading-induced slackening of the semitendinosus tendon used for ACL reconstruction across a broad range of ages. Methods Twenty-six male patients (aged 17–53 years), who were scheduled for ACL reconstruction surgery using the semitendinosus tendon autograft, participated in this study. The distal portion of the harvested semitendinosus tendon, which was not used to construct the autograft, was used for cyclic tensile testing to calculate the Young’s modulus and the extent of slackening (i.e., increase in slack length). Results Spearman correlation analysis revealed that the Young’s modulus of the semitendinosus tendon was positively correlated with the patient’s age (ρ = 0.559, P = 0.003). In contrast, the extent of tendon slackening did not correlate with the patient’s age. Conclusions We demonstrated that the Young’s modulus of the semitendinosus tendon increases with age, indicating that the semitendinosus tendon used for ACL reconstruction is compliant in young patients.
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Velosa-Moncada LA, Raskin JP, Aguilera-Cortés LA, López-Huerta F, Herrera-May AL. Estimation of the Young's Modulus of Nanometer-Thick Films Using Residual Stress-Driven Bilayer Cantilevers. Nanomaterials (Basel) 2022; 12:nano12020265. [PMID: 35055286 PMCID: PMC8778095 DOI: 10.3390/nano12020265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/08/2022] [Accepted: 01/11/2022] [Indexed: 02/05/2023]
Abstract
Precise prediction of mechanical behavior of thin films at the nanoscale requires techniques that consider size effects and fabrication-related issues. Here, we propose a test methodology to estimate the Young’s modulus of nanometer-thick films using micromachined bilayer cantilevers. The bilayer cantilevers which comprise a well-known reference layer and a tested film deflect due to the relief of the residual stresses generated during the fabrication process. The mechanical relationship between the measured residual stresses and the corresponding deflections was used to characterize the tested film. Residual stresses and deflections were related using analytical and finite element models that consider intrinsic stress gradients and the use of adherence layers. The proposed methodology was applied to low pressure chemical vapor deposited silicon nitride tested films with thicknesses ranging from 46 nm to 288 nm. The estimated Young’s modulus values varying between 213.9 GPa and 288.3 GPa were consistent with nanoindentation and alternative residual stress-driven techniques. In addition, the dependence of the results on the thickness and the intrinsic stress gradient of the materials was confirmed. The proposed methodology is simple and can be used to characterize diverse materials deposited under different fabrication conditions.
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Affiliation(s)
- Luis A. Velosa-Moncada
- Micro and Nanotechnology Research Center, Universidad Veracruzana, Boca del Rio 94294, Mexico;
| | - Jean-Pierre Raskin
- Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Université Catholique de Louvain (UCL), 1348 Louvain-la-Neuve, Belgium;
| | | | - Francisco López-Huerta
- Facultad de Ingeniería Eléctrica y Electrónica, Universidad Veracruzana, Boca del Rio 94294, Mexico;
| | - Agustín L. Herrera-May
- Micro and Nanotechnology Research Center, Universidad Veracruzana, Boca del Rio 94294, Mexico;
- Maestría en Ingeniería Aplicada, Facultad de Ingeniería de la Construcción y el Hábitat, Universidad Veracruzana, Boca del Rio 94294, Mexico
- Correspondence:
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Do TD, Katsuyoshi J, Cai H, Ohashi T. Mechanical Properties of Isolated Primary Cilia Measured by Micro-tensile Test and Atomic Force Microscopy. Front Bioeng Biotechnol 2021; 9:753805. [PMID: 34858960 PMCID: PMC8632022 DOI: 10.3389/fbioe.2021.753805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/18/2021] [Indexed: 11/29/2022] Open
Abstract
Mechanotransduction is a well-known mechanism by which cells sense their surrounding mechanical environment, convert mechanical stimuli into biochemical signals, and eventually change their morphology and functions. Primary cilia are believed to be mechanosensors existing on the surface of the cell membrane and support cells to sense surrounding mechanical signals. Knowing the mechanical properties of primary cilia is essential to understand their responses, such as sensitivity to mechanical stimuli. Previous studies have so far conducted flow experiments or optical trap techniques to measure the flexural rigidity EI (E: Young’s modulus, I: second moment of inertia) of primary cilia; however, the flexural rigidity is not a material property of materials and depends on mathematical models used in the determination, leading to a discrepancy between studies. For better characterization of primary cilia mechanics, Young’s modulus should be directly and precisely measured. In this study, the tensile Young’s modulus of isolated primary cilia is, for the first time, measured by using an in-house micro-tensile tester. The different strain rates of 0.01–0.3 s−1 were applied to isolated primary cilia, which showed a strain rate–dependent Young’s modulus in the range of 69.5–240.0 kPa on average. Atomic force microscopy was also performed to measure the local Young’s modulus of primary cilia, showing the Young’s modulus within the order of tens to hundreds of kPa. This study could directly provide the global and local Young’s moduli, which will benefit better understanding of primary cilia mechanics.
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Affiliation(s)
- Tien-Dung Do
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, Sapporo, Japan
| | - Jimuro Katsuyoshi
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, Sapporo, Japan
| | - Haonai Cai
- Division of Human Mechanical Systems and Design, Graduate School of Engineering, Hokkaido University, Sapporo, Japan
| | - Toshiro Ohashi
- Division of Mechanical and Aerospace Engineering, Faculty of Engineering, Hokkaido University, Sapporo, Japan
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Du C, Li Z, Liu B. Effect of Nanopores on Mechanical Properties of the Shape Memory Alloy. Micromachines (Basel) 2021; 12:mi12050529. [PMID: 34067037 PMCID: PMC8151688 DOI: 10.3390/mi12050529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/21/2021] [Accepted: 04/24/2021] [Indexed: 11/23/2022]
Abstract
Nanoporous Shape Memory Alloys (SMA) are widely used in aerospace, military industry, medical and health and other fields. More and more attention has been paid to its mechanical properties. In particular, when the size of the pores is reduced to the nanometer level, the effect of the surface effect of the nanoporous material on the mechanical properties of the SMA will increase sharply, and the residual strain of the SMA material will change with the nanoporosity. In this work, the expression of Young’s modulus of nanopore SMA considering surface effects is first derived, which is a function of nanoporosity and nanopore size. Based on the obtained Young’s modulus, a constitutive model of nanoporous SMA considering residual strain is established. Then, the stress–strain curve of dense SMA based on the new constitutive model is drawn by numerical method. The results are in good agreement with the simulation results in the published literature. Finally, the stress-strain curves of SMA with different nanoporosities are drawn, and it is concluded that the Young’s modulus and strength limit decrease with the increase of nanoporosity.
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Norman MDA, Ferreira SA, Jowett GM, Bozec L, Gentleman E. Measuring the elastic modulus of soft culture surfaces and three-dimensional hydrogels using atomic force microscopy. Nat Protoc 2021; 16:2418-2449. [PMID: 33854255 PMCID: PMC7615740 DOI: 10.1038/s41596-021-00495-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 01/05/2021] [Indexed: 02/02/2023]
Abstract
Growing interest in exploring mechanically mediated biological phenomena has resulted in cell culture substrates and 3D matrices with variable stiffnesses becoming standard tools in biology labs. However, correlating stiffness with biological outcomes and comparing results between research groups is hampered by variability in the methods used to determine Young's (elastic) modulus, E, and by the inaccessibility of relevant mechanical engineering protocols to most biology labs. Here, we describe a protocol for measuring E of soft 2D surfaces and 3D hydrogels using atomic force microscopy (AFM) force spectroscopy. We provide instructions for preparing hydrogels with and without encapsulated live cells, and provide a method for mounting samples within the AFM. We also provide details on how to calibrate the instrument, and give step-by-step instructions for collecting force-displacement curves in both manual and automatic modes (stiffness mapping). We then provide details on how to apply either the Hertz or the Oliver-Pharr model to calculate E, and give additional instructions to aid the user in plotting data distributions and carrying out statistical analyses. We also provide instructions for inferring differential matrix remodeling activity in hydrogels containing encapsulated single cells or organoids. Our protocol is suitable for probing a range of synthetic and naturally derived polymeric hydrogels such as polyethylene glycol, polyacrylamide, hyaluronic acid, collagen, or Matrigel. Although sample preparation timings will vary, a user with introductory training to AFM will be able to use this protocol to characterize the mechanical properties of two to six soft surfaces or 3D hydrogels in a single day.
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Affiliation(s)
- Michael D. A. Norman
- Centre for Craniofacial and Regenerative Biology, King’s College London, London SE1 9RT, UK
| | - Silvia A. Ferreira
- Centre for Craniofacial and Regenerative Biology, King’s College London, London SE1 9RT, UK
| | - Geraldine M. Jowett
- Centre for Craniofacial and Regenerative Biology, King’s College London, London SE1 9RT, UK
| | - Laurent Bozec
- Faculty of Dentistry, University of Toronto, Toronto, ON M5G 1G6, Canada
| | - Eileen Gentleman
- Centre for Craniofacial and Regenerative Biology, King’s College London, London SE1 9RT, UK
- London Centre for Nanotechnology, London WC1H 0AH, UK
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Abdelkader EM, Nassar K, Melchor J, Rus G. Braiding Thermoplastic and Glass Fibers in Composite Dental Post Improves Their Mechanical Compatibility, In Vitro Experiment. Materials (Basel) 2021; 14:2294. [PMID: 33946632 PMCID: PMC8124747 DOI: 10.3390/ma14092294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/18/2021] [Accepted: 04/19/2021] [Indexed: 02/06/2023]
Abstract
Mechanical compatibility with the human dentin is a considerable issue when fabricating dental fiber posts. To this purpose, this study introduces a new method of fabricating compatible dental posts using braiding techniques of thermoplastic fibers (matrix) with glass fibers (reinforcement). Fifty fiber-reinforced composite (FRC) posts of thermoplastic yarns polypropylene (PP) braided with continuous filaments glass fibers (GFs) for reinforcement, varying in fiber volume fraction (FVF), and core types are fabricated and tested. Posts are performed using a braiding machine, and braids are placed in an aluminum mold. The filled mold is playced inside an oven at the melting temperature of the polypropylene to produce the final post's shape. An ultrasonic test is conducted to measure the shear modulus and Young's modulus of FRC post specimens by measuring the velocities of both the P-wave and S-wave. In order to ensure the accuracy of the measurements, each sample is measured three times, and then the means and standard deviations of each sample are calculated before analyzing the test results using the means of two steps, namely, clustering and comparing the P and R² values of each cluster, which revealed that FVF, fiber mass, and core type of the specimen had a significant effect on the resulted Young's and shear modulus. The results indicate that the proposed method can fabricate competitive dental posts with regard to different fabricating variables. The samples show Young's modulus ranges of from 10.08 GPa to 31.83 GPa. The following tested hypothesis is supported: the braiding technique of thermoplastic fibers with glass fibers will improve the mechanical compatibility of the resulting posts (ex vivo).
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Affiliation(s)
- Esraa M Abdelkader
- Department of Structural Mechanics, University of Granada, 18071 Granada, Spain
- Department of Textile, Faculty of Applied Arts, Helwan University, Cairo 11795, Egypt
- Department of Textile, Faculty of Applied Arts, Badr University in Cairo, Cairo 11829, Egypt
| | - Khaled Nassar
- Department of Textile, Faculty of Applied Arts, Helwan University, Cairo 11795, Egypt
- Department of Textile, Faculty of Applied Arts, Badr University in Cairo, Cairo 11829, Egypt
| | - Juan Melchor
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain
- Excellence Research Unit "ModelingNature" MNat, University of Granada, 18071 Granada, Spain
- Department of Statistics and Operations Research, University of Granada, 18071 Granada, Spain
| | - Guillermo Rus
- Department of Structural Mechanics, University of Granada, 18071 Granada, Spain
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain
- Excellence Research Unit "ModelingNature" MNat, University of Granada, 18071 Granada, Spain
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13
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Bhardwaj A, Sharma A, Suryanarayana P. Torsional moduli of transition metal dichalcogenide nanotubes from first principles. Nanotechnology 2021; 32:28LT02. [PMID: 33827066 DOI: 10.1088/1361-6528/abf59c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
We calculate the torsional moduli of single-walled transition metal dichalcogenide (TMD) nanotubes usingab initiodensity functional theory (DFT). Specifically, considering forty-five select TMD nanotubes, we perform symmetry-adapted DFT calculations to calculate the torsional moduli for the armchair and zigzag variants of these materials in the low-twist regime and at practically relevant diameters. We find that the torsional moduli follow the trend: MS2> MSe2> MTe2. In addition, the moduli display a power law dependence on diameter, with the scaling generally close to cubic, as predicted by the isotropic elastic continuum model. In particular, the shear moduli so computed are in good agreement with those predicted by the isotropic relation in terms of the Young's modulus and Poisson's ratio, both of which are also calculated using symmetry-adapted DFT. Finally, we develop a linear regression model for the torsional moduli of TMD nanotubes based on the nature/characteristics of the metal-chalcogen bond, and show that it is capable of making reasonably accurate predictions.
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Affiliation(s)
- Arpit Bhardwaj
- College of Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States of America
| | - Abhiraj Sharma
- College of Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States of America
| | - Phanish Suryanarayana
- College of Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States of America
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14
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Scheible F, Lamprecht R, Semmler M, Sutor A. Dynamic Biomechanical Analysis of Vocal Folds Using Pipette Aspiration Technique. Sensors (Basel) 2021; 21:2923. [PMID: 33919359 DOI: 10.3390/s21092923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 11/30/2022]
Abstract
The voice producing process is a complex interplay between glottal pressure, vocal folds, their elasticity and tension. The material properties of vocal folds are still insufficiently studied, because the determination of material properties in soft tissues is often difficult and connected to extensive experimental setups. To shed light on this less researched area, in this work, a dynamic pipette aspiration technique is utilized to measure the elasticity in a frequency range of 100–1000 Hz. The complex elasticity could be assessed with the phase shift between exciting pressure and tissue movement. The dynamic pipette aspiration setup has been miniaturized with regard to a future in-vivo application. The techniques were applied on 3 different porcine larynges 4 h and 1 d postmortem, in order to investigate the deterioration of the tissue over time and analyze correlation in elasticity values between vocal fold pairs. It was found that vocal fold pairs do have different absolute elasticity values but similar trends. This leads to the assumption that those trends are more important for phonation than having same absolute values.
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15
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Gupta NS, Lee KS, Labouriau A. Tuning Thermal and Mechanical Properties of Polydimethylsiloxane with Carbon Fibers. Polymers (Basel) 2021; 13:1141. [PMID: 33918388 PMCID: PMC8038219 DOI: 10.3390/polym13071141] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Revised: 04/01/2021] [Accepted: 04/01/2021] [Indexed: 02/08/2023] Open
Abstract
In order to meet the needs of constantly advancing technologies, fabricating materials with improved properties and predictable behavior has become vital. To that end, we have prepared polydimethylsiloxane (PDMS) polymer samples filled with carbon nanofibers (CFs) at 0, 0.5, 1.0, 2.0, and 4.0 CF loadings (w/w) to investigate and optimize the amount of filler needed for fabrication with improved mechanical properties. Samples were prepared using easy, cost-efficient mechanical mixing to combine the PDMS and CF filler and were then characterized by chemical (FTIR), mechanical (hardness and tension), and physical (swelling, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and coefficient of thermal expansion) analyses to determine the material properties. We found that hardness and thermal stability increased predictably, while the ultimate strength and toughness both decreased. Repeated tension caused the CF-filled PDMS samples to lose significant toughness with increasing CF loadings. The hardness and thermal degradation temperature with 4 wt.% CF loading in PDMS increased more than 40% and 25 °C, respectively, compared with the pristine PDMS sample. Additionally, dilatometer measurements showed a 20% decrease in the coefficient of thermal expansion (CTE) with a small amount of CF filler in PDMS. In this study, we were able to show the mechanical and thermal properties of PDMS can be tuned with good confidence using CFs.
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Affiliation(s)
| | | | - Andrea Labouriau
- C-CDE Chemical Diagnostics and Engineering, Los Alamos National Laboratory, Los Alamos, NM 87545, USA;
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16
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Shalabi FI, Mazher J, Khan K, Amin MN, Albaqshi A, Alamer A, Barsheed A, Alshuaibi O. Influence of Lime and Volcanic Ash on the Properties of Dune Sand as Sustainable Construction Materials. Materials (Basel) 2021; 14:645. [PMID: 33573361 DOI: 10.3390/ma14030645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 01/17/2021] [Accepted: 01/26/2021] [Indexed: 11/16/2022]
Abstract
This study focused on evaluating dune sand stabilized with lime and volcanic ash as base course materials in engineering construction. Dune sands are found in Saudi Arabia in huge quantities. Due to the high demand for construction materials, this makes them highly suitable for construction. A testing program was designed to investigate the effect of adding different percentages by weight of lime (L: 0, 2, 4, and 6%) and volcanic ash (VA: 0, 1, 3, and 5%) on the engineering properties of the stabilized mixture. Unconfined compressive strength (UCS) and California bearing ratio (CBR) tests were conducted. In addition, Raman spectroscopy and laser-scanning microscopy (LSM) tests were performed to explore the chemical characteristic, packing, and structure of the mixture. The results showed that the UCS, CBR, and the Young's modulus (Es) of the treated dune sand increased with the increase in percentage of both stabilizers. Furthermore, LSM images of mortar blended with intermediate L-to-VA blend ratio ≈0.55 (L: 6% and VA: 5%) exhibit compact packing of sand grains, indicating strong adhesion and higher cementing value. The results of the study are promising and encourage using the treated dune sand in engineering construction even with a low percentage use of lime (2%) and volcanic ash (1-3%) as stabilizers.
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17
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Dutta D, Palmer XL, Ortega-Rodas J, Balraj V, Dastider IG, Chandra S. Biomechanical and Biophysical Properties of Breast Cancer Cells Under Varying Glycemic Regimens. Breast Cancer (Auckl) 2020; 14:1178223420972362. [PMID: 33239879 PMCID: PMC7672722 DOI: 10.1177/1178223420972362] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 10/12/2020] [Indexed: 01/27/2023] Open
Abstract
Diabetes accelerates cancer cell proliferation and metastasis, particularly for cancers of the pancreas, liver, breast, colon, and skin. While pathways linking the 2 disease conditions have been explored extensively, there is a lack of information on whether there could be cytoarchitectural changes induced by glucose which predispose cancer cells to aggressive phenotypes. It was thus hypothesized that exposure to diabetes/high glucose alters the biomechanical and biophysical properties of cancer cells more than the normal cells, which aids in advancing the cancer. For this study, atomic force microscopy indentation was used through microscale probing of multiple human breast cancer cells (MCF-7, MDA-MB-231), and human normal mammary epithelial cells (MCF-10A), under different levels of glycemic stress. These were used to study both benign and malignant breast tissue behaviors. Benign cells (MCF-10A) recorded higher Young's modulus values than malignant cells (MCF-7 and MDA-231) under normoglycemic conditions, which agrees with the current literature. Moreover, exposure to high glucose (for 48 hours) decreased Young's modulus in both benign and malignant cells, to the effect that the cancer cells showed a complete loss in elasticity with high glucose. This provides a possible insight into a link between glycemic stress and cytoskeletal strength. This work suggests that reducing glycemic stress in cancer patients and those at risk can prove beneficial in restoring normal cytoskeletal structure.
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Affiliation(s)
- Diganta Dutta
- Department of Physics and Astronomy, University of Nebraska at Kearney, Kearney, NE, USA
| | - Xavier-Lewis Palmer
- Department of Biomedical Engineering, Old Dominion University, Norfolk, VA, USA
| | - Jose Ortega-Rodas
- Department of Biology, University of Nebraska at Kearney, Kearney, NE, USA
| | | | | | - Surabhi Chandra
- Department of Biology, University of Nebraska at Kearney, Kearney, NE, USA
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18
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Gao J, Luo J, Geng H, Cui K, Zhao Z, Liu L. Morphologies, Young's Modulus and Resistivity of High Aspect Ratio Tungsten Nanowires. Materials (Basel) 2020; 13:ma13173749. [PMID: 32854175 PMCID: PMC7503276 DOI: 10.3390/ma13173749] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 08/15/2020] [Accepted: 08/17/2020] [Indexed: 11/16/2022]
Abstract
High aspect ratio tungsten nanowires have been prepared by selective dissolution of Nickel-aluminum-tungsten (NiAl−W) alloys which were directionally solidified at growth rates varying from 2 to 25 μm/s with a temperature gradient of 300 K·cm−1. Young’s modulus and electrical resistivity of tungsten nanowires were measured by metallic mask template method. The results show that the tungsten nanowires with uniform diameter and high aspect ratio are well aligned. The length of tungsten nanowires increases with prolongation of etching time, and their length reaches 300 μm at 14 h. Young’s modulus of tungsten nanowires is estimated by Hertz and Sneddon models. The Sneddon model is proper for estimating the Young’s modulus, and the value of calculating Young’s modulus are 260–460 GPa which approach the value of bulk tungsten. The resistivity of tungsten nanowires is measured and fitted with Fuchs−Sondheimer (FS) + Mayadas−Shatzkes (MS) model. The fitting results show that the specific resistivity of W nanowires is a litter bigger than the bulk W, and its value decreases with decreasing diameter.
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Affiliation(s)
- Jianjun Gao
- School of Mechanical Engineering and Automation, Fuzhou University, Fu Zhou 350108, China; (J.G.); (H.G.)
| | - Jian Luo
- School of Mechanical Engineering and Automation, Fuzhou University, Fu Zhou 350108, China; (J.G.); (H.G.)
- Correspondence: ; Tel./Fax: +86-0591-22866262
| | - Haibin Geng
- School of Mechanical Engineering and Automation, Fuzhou University, Fu Zhou 350108, China; (J.G.); (H.G.)
| | - Kai Cui
- School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (K.C.); (Z.Z.)
| | - Zhilong Zhao
- School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (K.C.); (Z.Z.)
| | - Lin Liu
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China;
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19
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Shin CS, Li TJ, Lin CL. Alleviating Distortion and Improving the Young's Modulus in Two-Photon Polymerization Fabrications. Micromachines (Basel) 2018; 9:mi9120615. [PMID: 30467303 PMCID: PMC6316448 DOI: 10.3390/mi9120615] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 11/14/2018] [Accepted: 11/19/2018] [Indexed: 12/28/2022]
Abstract
Two-photon polymerization enables the extremely high resolution three-dimensional printing of micro-structures. To know the mechanical properties, and better still, to be able to adjust them is of paramount importance to ensuring the proper structural integrity of the printed products. In this work, the Young’s modulus is measured on two-photon polymerized micro-cantilever bars. Optimizing the scanning trajectory of the laser focus points is important in alleviating distortion of the printed bars. By increasing the laser power and decreasing the inter-voxel distances we can double the Young’s modulus. Post-curing with ultraviolet light can approximately quadruple the Young’s modulus. However, the resulting modulus is still only about 0.3% of that of the bulk polymerized material.
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Affiliation(s)
- Chow-Shing Shin
- Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan.
| | - Tzu-Jui Li
- Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan.
| | - Chih-Lang Lin
- Graduate Institute of Biotechnology and Biomedical Engineering, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan.
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20
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Massey GJ, Balshaw TG, Maden-Wilkinson TM, Tillin NA, Folland JP. Tendinous Tissue Adaptation to Explosive- vs. Sustained-Contraction Strength Training. Front Physiol 2018; 9:1170. [PMID: 30233387 PMCID: PMC6131493 DOI: 10.3389/fphys.2018.01170] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 08/03/2018] [Indexed: 01/06/2023] Open
Abstract
The effect of different strength training regimes, and in particular training utilizing brief explosive contractions, on tendinous tissue properties is poorly understood. This study compared the efficacy of 12 weeks of knee extensor explosive-contraction (ECT; n = 14) vs. sustained-contraction (SCT; n = 15) strength training vs. a non-training control (n = 13) to induce changes in patellar tendon and knee extensor tendon-aponeurosis stiffness and size (patellar tendon, vastus-lateralis aponeurosis, quadriceps femoris muscle) in healthy young men. Training involved 40 isometric knee extension contractions (three times/week): gradually increasing to 75% of maximum voluntary torque (MVT) before holding for 3 s (SCT), or briefly contracting as fast as possible to ∼80% MVT (ECT). Changes in patellar tendon stiffness and Young's modulus, tendon-aponeurosis complex stiffness, as well as quadriceps femoris muscle volume, vastus-lateralis aponeurosis area and patellar tendon cross-sectional area were quantified with ultrasonography, dynamometry, and magnetic resonance imaging. ECT and SCT similarly increased patellar tendon stiffness (20% vs. 16%, both p < 0.05 vs. control) and Young's modulus (22% vs. 16%, both p < 0.05 vs. control). Tendon-aponeurosis complex high-force stiffness increased only after SCT (21%; p < 0.02), while ECT resulted in greater overall elongation of the tendon-aponeurosis complex. Quadriceps muscle volume only increased after sustained-contraction training (8%; p = 0.001), with unclear effects of strength training on aponeurosis area. The changes in patellar tendon cross-sectional area after strength training were not appreciably different to control. Our results suggest brief high force muscle contractions can induce increased free tendon stiffness, though SCT is needed to increase tendon-aponeurosis complex stiffness and muscle hypertrophy.
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Affiliation(s)
- Garry J Massey
- Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Loughborough University, Loughborough, United Kingdom.,School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Thomas G Balshaw
- Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Loughborough University, Loughborough, United Kingdom.,School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, United Kingdom
| | - Thomas M Maden-Wilkinson
- School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, United Kingdom.,Faculty of Health and Wellbeing, Sheffield Hallam University, Sheffield, United Kingdom
| | - Neale A Tillin
- Department of Life Sciences, University of Roehampton, London, United Kingdom
| | - Jonathan P Folland
- Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Loughborough University, Loughborough, United Kingdom.,School of Sport, Exercise, and Health Sciences, Loughborough University, Loughborough, United Kingdom
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21
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Lipowczan M, Borowska-Wykręt D, Natonik-Białoń S, Kwiatkowska D. Growing cell walls show a gradient of elastic strain across their layers. J Exp Bot 2018; 69:4349-4362. [PMID: 29945239 PMCID: PMC6093493 DOI: 10.1093/jxb/ery237] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 06/21/2018] [Indexed: 05/16/2023]
Abstract
The relatively thick primary walls of epidermal and collenchyma cells often form waviness on the surface that faces the protoplast when they are released from the tensile in-plane stress that operates in situ. This waviness is a manifestation of buckling that results from the heterogeneity of the elastic strain across the wall. In this study, this heterogeneity was confirmed by the spontaneous bending of isolated wall fragments that were initially flat. We combined the empirical data on the formation of waviness in growing cell walls with computations of the buckled wall shapes. We chose cylindrical-shaped organs with a high degree of longitudinal tissue stress because in such organs the surface deformation that accompanies the removal of the stress is strongly anisotropic and leads to the formation of waviness in which wrinkles on the inner wall surface are always transverse to the organ axis. The computations showed that the strain heterogeneity results from individual or overlaid gradients of pre-stress and stiffness across the wall. The computed wall shapes depend on the assumed wall thickness and mechanical gradients. Thus, a quantitative analysis of the wall waviness that forms after stress removal can be used to assess the mechanical heterogeneity of the cell wall.
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Affiliation(s)
- Marcin Lipowczan
- Department of Biophysics and Morphogenesis of Plants, University of Silesia in Katowice, Katowice, Poland
| | - Dorota Borowska-Wykręt
- Department of Biophysics and Morphogenesis of Plants, University of Silesia in Katowice, Katowice, Poland
| | - Sandra Natonik-Białoń
- Department of Biophysics and Morphogenesis of Plants, University of Silesia in Katowice, Katowice, Poland
| | - Dorota Kwiatkowska
- Department of Biophysics and Morphogenesis of Plants, University of Silesia in Katowice, Katowice, Poland
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Innocenti B, Larrieu JC, Lambert P, Pianigiani S. Automatic characterization of soft tissues material properties during mechanical tests. Muscles Ligaments Tendons J 2018; 7:529-537. [PMID: 29721454 DOI: 10.11138/mltj/2017.7.4.529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Introduction The estimation of the non-linear viscoelastic characteristics of human soft tissues, such as ligaments and tendon, is often affected by the implemented procedure. This study aims at developing and validating a protocol, associated with a contactless and automatic procedure, enabling the determination of the material behavior and properties of any soft tissues. Methods Several markers were drawn onto the soft tissue specimen analyzed under uniaxial tensile test. An automatic contactless procedure, that uses a camera for recording the position of the markers during the test, was developed to compute the displacement, and the force applied, enabling the calculation of the true-stress/strain curve of the material. Young's modulus and Poisson's ratio can be calculated, on demand, for selected regions of interest of the soft tissues. The repeatability and reproducibility of the procedure were analyzed. The procedure was initially tested and verified on an artificial silicone material and later applied for investigating the mechanical behavior of a pig Achilles tendon and of a human patellar tendon. Results The procedure show a high repeatability, independent by the operator, reliability and accuracy for the tested synthetic material (with a maximum error of 3.7% for Young's modulus). Additionally, the developed protocol was also suitable for the analysis of animal and human soft tissues. Conclusion A protocol to automatically and accurately determine material properties in soft tissues was developed, tested and validated. Such approach could successfully be implemented for the mechanical characterization of any biological soft-tissue. Level of evidence V.
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Affiliation(s)
| | | | - Pierre Lambert
- BEAMS Department, Université Libre de Bruxelles, Bruxelles, Belgium
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23
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Abstract
We report quantitative photoacoustic elastography (QPAE) capable of measuring Young’s modulus of biological tissue in vivo in humans. By combining conventional PAE with a stress sensor having known stress–strain behavior, QPAE can simultaneously measure strain and stress, from which Young’s modulus is calculated. We first demonstrate the feasibility of QPAE in agar phantoms with different concentrations. The measured Young’s modulus values fit well with both the empirical expectation based on the agar concentrations and those measured in an independent standard compression test. Next, QPAE was applied to quantify the Young’s modulus of skeletal muscle in vivo in humans, showing a linear relationship between muscle stiffness and loading. The results demonstrated the capability of QPAE to assess the absolute elasticity of biological tissue noninvasively in vivo in humans, indicating its potential for tissue biomechanics studies and clinical applications.
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Affiliation(s)
- Pengfei Hai
- Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Yong Zhou
- Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Lei Gong
- Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, One Brookings Drive, St. Louis, Missouri 63130, United States
- University of Science and Technology of China, Department of Optics and Optical Engineering, Jinzhai Road 96, Hefei, Anhui 230026, China
| | - Lihong V. Wang
- Washington University in St. Louis, Department of Biomedical Engineering, Optical Imaging Laboratory, One Brookings Drive, St. Louis, Missouri 63130, United States
- Address all correspondence to: Lihong V. Wang, E-mail:
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Bayliss A, Weatherholt A, Crandall T, Farmer D, McConnell J, Crossley K, Warden S. Achilles tendon material properties are greater in the jump leg of jumping athletes. J Musculoskelet Neuronal Interact 2016; 16:105-12. [PMID: 27282454 PMCID: PMC5114353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
PURPOSE The Achilles tendon (AT) must adapt to meet changes in demands. This study explored AT adaptation by comparing properties within the jump and non-jump legs of jumping athletes. Non-jumping control athletes were included to control limb dominance effects. METHODS AT properties were assessed in the preferred (jump) and non-preferred (lead) jumping legs of male collegiate-level long and/or high jump (jumpers; n=10) and cross-country (controls; n=10) athletes. Cross-sectional area (CSA), elongation, and force during isometric contractions were used to estimate the morphological, mechanical and material properties of the ATs bilaterally. RESULTS Jumpers exposed their ATs to more force and stress than controls (all p≤0.03). AT force and stress were also greater in the jump leg of both jumpers and controls than in the lead leg (all p<0.05). Jumpers had 17.8% greater AT stiffness and 24.4% greater Young's modulus in their jump leg compared to lead leg (all p<0.05). There were no jump versus lead leg differences in AT stiffness or Young's modulus within controls (all p>0.05). CONCLUSION ATs chronically exposed to elevated mechanical loading were found to exhibit greater mechanical (stiffness) and material (Young's modulus) properties.
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Affiliation(s)
- A.J. Bayliss
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
| | - A.M. Weatherholt
- Center for Translational Musculoskeletal Research, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
| | - T.T. Crandall
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
| | - D.L. Farmer
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
| | - J.C. McConnell
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA
| | - K.M. Crossley
- School of Allied Health, College of Science, Health and Engineering, Bundoora, VIC, Australia
| | - S.J. Warden
- Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA,Center for Translational Musculoskeletal Research, School of Health and Rehabilitation Sciences, Indiana University, Indianapolis, IN 46202, USA,Corresponding author: Stuart J. Warden, Department of Physical Therapy, School of Health and Rehabilitation Sciences, Indiana University, 1140 W. Michigan Street, CF-120, Indianapolis, IN 46202, USA E-mail:
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Abstract
In this paper, novel designs of porous acetabular cups are created and tested with 3D finite element analysis (FEA). The aim is to develop a porous acetabular cup with low effective radial stiffness of the structure, which will be near to the architectural and mechanical behavior of the natural bone. For the realization of this research, a 3D-scanner technology was used for obtaining a 3D-CAD model of the pelvis bone, a 3D-CAD software for creating a porous acetabular cup, and a 3D-FEA software for virtual testing of a novel design of the porous acetabular cup. The results obtained from this research reveal that a porous acetabular cup from Ti-based alloys with 60 ± 5% porosity has the mechanical behavior and effective radial stiffness (Young's modulus in radial direction) that meet and exceed the required properties of the natural bone. The virtual testing with 3D-FEA of a novel design with porous structure during the very early stage of the design and the development of orthopedic implants, enables obtaining a new or improved biomedical implant for a relatively short time and reduced price.
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Affiliation(s)
- Ile Mircheski
- a Faculty of Mechanical Engineering , "Ss. Cyril and Methodius" University in Skopje , Skopje , Republic of Macedonia
| | - Marko Gradišar
- b HELI PRO Production and Sales of Ortopaedic Implants , Lesce , Slovenia
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26
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Zdunek A, Kozioł A, Cybulska J, Lekka M, Pieczywek PM. The stiffening of the cell walls observed during physiological softening of pears. Planta 2016; 243:519-29. [PMID: 26498014 PMCID: PMC4722064 DOI: 10.1007/s00425-015-2423-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 10/13/2015] [Indexed: 05/12/2023]
Abstract
The Young's modulus of the primary cell walls of pears decreases linearly during the pre-harvest on-tree maturation and increases during postharvest storage, and does not correlate with firmness of fruit. The determination of mechanical properties of cell walls is indispensable for understanding the mechanism of physiological softening and deterioration of quality of fruits during postharvest storage. The Young's modulus of the primary cell walls from pear fruit (Pyrus communis L., cultivars 'Conference' and 'Xenia') during pre-harvest maturation and postharvest storage in an ambient atmosphere at 2 °C followed by shelf life was studied using atomic force microscopy (AFM). The results were related to the firmness of fruits, galacturonic acid content in water, chelator, sodium carbonate and insoluble pectin fractions, polygalacturonase and pectin methylesterase activities. The Young's modulus of the primary cell walls decreased linearly during the last month of pre-harvest maturation from 3.2 ± 1.8 to 1.1 ± 0.7 MPa for 'Conference' and from 1.9 ± 1.2 to 0.2 ± 0.1 MPa for 'Xenia' which correlated with linear firmness decrease. During postharvest storage the cell wall Young's modulus increased while firmness continued to decrease. Correlation analysis for the entire period of the experiment showed a lack of straightforward relation between the Young's modulus of primary cell walls and fruit firmness. The Young's modulus of cell walls correlated negatively either with galacturonic acid content in sodium carbonate soluble pectin ('Conference') or with insoluble pectin fractions ('Xenia') and positively with polygalacturonase activity. It was therefore evidenced that covalently linked pectins play the key role for the stiffness of fruit cell walls. Based on the obtained results, the model explaining the fruit transition from firm and crispy to soft and mealy was proposed.
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Affiliation(s)
- Artur Zdunek
- />Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
| | - Arkadiusz Kozioł
- />Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
| | - Justyna Cybulska
- />Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
| | - Małgorzata Lekka
- />The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland
| | - Piotr M. Pieczywek
- />Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
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Abstract
Currently, most of the in vitro cell research is performed on rigid tissue culture polystyrene (~1 GPa), while most cells in the body are attached to a matrix that is elastic and much softer (0.1-100 kPa). Since such stiffness mismatch greatly affects cell responses, there is a strong interest in developing hydrogel materials that span a wide range of stiffness to serve as cell substrates. Polyacrylamide gels, which are inexpensive and cover the stiffness range of all soft tissues in the body, are the hydrogel of choice for many research groups. However, polyacrylamide gel preparation is lengthy, tedious, and only suitable for small batches. Here, we describe an assay which by utilizing a permanent flexible plastic film as a structural support for the gels, enables the preparation of polyacrylamide gels in a multiwell plate format. The technique is faster, more efficient, and less costly than current methods and permits the preparation of gels of custom sizes not otherwise available. As it doesn't require any specialized equipment, the method could be easily adopted by any research laboratory and would be particularly useful in research focused on understanding stiffness-dependent cell responses.
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Affiliation(s)
- Sana Syed
- Biomedical Engineering Department, Saint Louis University
| | - Amin Karadaghy
- Biomedical Engineering Department, Saint Louis University
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28
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Wang W, Li S, Min J, Yi C, Zhan Y, Li M. Nanoindentation experiments for single-layer rectangular graphene films: a molecular dynamics study. Nanoscale Res Lett 2014; 9:41. [PMID: 24447765 PMCID: PMC3903443 DOI: 10.1186/1556-276x-9-41] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 01/14/2014] [Indexed: 06/01/2023]
Abstract
A molecular dynamics study on nanoindentation experiments is carried out for some single-layer rectangular graphene films with four edges clamped. Typical load-displacement curves are obtained, and the effects of various factors including indenter radii, loading speeds, and aspect ratios of the graphene film on the simulation results are discussed. A formula describing the relationship between the load and indentation depth is obtained according to the molecular dynamics simulation results. Young's modulus and the strength of the single-layer graphene film are measured as about 1.0 TPa and 200 GPa, respectively. It is found that the graphene film ruptured in the central point at a critical indentation depth. The deformation mechanisms and dislocation activities are discussed in detail during the loading-unloading-reloading process. It is observed from the simulation results that once the loading speed is larger than the critical loading speed, the maximum force exerted on the graphene film increases and the critical indentation depth decreases with the increase of the loading speed.
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Affiliation(s)
- Weidong Wang
- School of Electrical and Mechanical Engineering, Xidian University, Xi'an 710071, China
| | - Shuai Li
- School of Electrical and Mechanical Engineering, Xidian University, Xi'an 710071, China
| | - Jiaojiao Min
- School of Electrical and Mechanical Engineering, Xidian University, Xi'an 710071, China
| | - Chenglong Yi
- School of Electrical and Mechanical Engineering, Xidian University, Xi'an 710071, China
| | - Yongjie Zhan
- Physics Department, Northwest University, Xi'an 710069, China
| | - Minglin Li
- School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350108, China
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Li J, Wang S, Manapuram RK, Singh M, Menodiado FM, Aglyamov S, Emelianov S, Twa MD, Larin KV. Dynamic optical coherence tomography measurements of elastic wave propagation in tissue-mimicking phantoms and mouse cornea in vivo. J Biomed Opt 2013; 18:121503. [PMID: 24089292 PMCID: PMC3788653 DOI: 10.1117/1.jbo.18.12.121503] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 08/31/2013] [Accepted: 09/06/2013] [Indexed: 05/18/2023]
Abstract
We demonstrate the use of phase-stabilized swept-source optical coherence tomography to assess the propagation of low-amplitude (micron-level) waves induced by a focused air-pulse system in tissue-mimicking phantoms, a contact lens, a silicone eye model, and the mouse cornea in vivo. The results show that the wave velocity can be quantified from the analysis of wave propagation, thereby enabling the estimation of the sample elasticity using the model of surface wave propagation for the tissue-mimicking phantoms. This noninvasive, noncontact measurement technique involves low-force methods of tissue excitation that can be potentially used to assess the biomechanical properties of ocular and other delicate tissues in vivo.
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Affiliation(s)
- Jiasong Li
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004
| | - Shang Wang
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004
| | - Ravi Kiran Manapuram
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton Street Stop C0800, Austin, Texas 78712
| | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004
| | - Floredes M. Menodiado
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004
| | - Salavat Aglyamov
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton Street Stop C0800, Austin, Texas 78712
| | - Stanislav Emelianov
- The University of Texas at Austin, Department of Biomedical Engineering, 107 W. Dean Keeton Street Stop C0800, Austin, Texas 78712
| | - Michael D. Twa
- University of Houston, College of Optometry, 505 J. Davis Armistead Building, Houston, Texas 77204-2020
| | - Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004
- University of Houston, Department of Mechanical Engineering, 4800 Calhoun Road, Houston, Texas 77004
- Baylor College of Medicine, Department of Molecular Physiology and Biophysics, One Baylor Plaza, Houston, Texas 77030
- Address all correspondence to: Kirill V. Larin, University of Houston, Department of Biomedical Engineering, 4800 Calhoun Road, Houston, Texas 77004. Tel: (832)842-8834; Fax: (713)743-0226; E-mail:
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Yoon S, Aglyamov S, Karpiouk A, Emelianov S. The mechanical properties of ex vivo bovine and porcine crystalline lenses: age-related changes and location-dependent variations. Ultrasound Med Biol 2013; 39:1120-7. [PMID: 23453376 PMCID: PMC3646975 DOI: 10.1016/j.ultrasmedbio.2012.12.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 11/01/2012] [Accepted: 12/15/2012] [Indexed: 05/03/2023]
Abstract
The mechanical properties of ex vivo animal lenses from three groups were evaluated: old bovine (25-30 mo old, n = 4), young bovine (6 mo old, n = 4) and young porcine (6 mo old, n = 4) eye globes. We measured the dynamics of laser-induced microbubbles created at different locations within the crystalline lenses. An impulsive acoustic radiation force was applied to the microbubble, and the microbubble displacements were measured using a custom-built high pulse repetition frequency ultrasound system. Based on the measured dynamics of the microbubbles, Young's moduli of bovine and porcine lens tissue in the vicinity of the microbubbles were reconstructed. Age-related changes and location-dependent variations in the Young's modulus of the lenses were observed. Near the center, the old bovine lenses had a Young's modulus approximately fivefold higher than that of young bovine and porcine lenses. The gradient of Young's modulus with respect to radial distance was observed in the lenses from three groups.
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Affiliation(s)
- Sangpil Yoon
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Salavat Aglyamov
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Andrei Karpiouk
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Stanislav Emelianov
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX 78712
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712
- Corresponding Author: 107 W. Dean Keeton St. Austin, TX 78712; ; +1-512-471-1733
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Zhao L, Shim JW, Dodge TR, Robling AG, Yokota H. Inactivation of Lrp5 in osteocytes reduces young's modulus and responsiveness to the mechanical loading. Bone 2013; 54:35-43. [PMID: 23356985 PMCID: PMC3602226 DOI: 10.1016/j.bone.2013.01.033] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 01/15/2013] [Accepted: 01/18/2013] [Indexed: 01/08/2023]
Abstract
Low-density-lipoprotein receptor-related protein 5 (Lrp5) is a co-receptor in Wnt signaling, which plays a critical role in development and maintenance of bone. Osteoporosis-pseudoglioma syndrome, for instance, arises from loss-of-function mutations in Lrp5, and global deletion of Lrp5 in mice results in significantly lower bone mineral density. Since osteocytes are proposed to act as a mechanosensor in the bone, we addressed a question whether a conditional loss-of-function mutation of Lrp5 selective to osteocytes (Dmp1-Cre;Lrp5(f/f)) would alter responses to ulna loading. Loading was applied to the right ulna for 3 min (360 cycles at 2Hz) at a peak force of 2.65 N for 3 consecutive days, and the contralateral ulna was used as a non-loaded control. Young's modulus was determined using a midshaft section of the femur. The results showed that compared to age-matched littermate controls, mice lacking Lrp5 in osteocytes exhibited smaller skeletal size with reduced bone mineral density and content. Compared to controls, Lrp5 deletion in osteocytes also led to a 4.6-fold reduction in Young's modulus. In response to ulna loading, mineralizing surface, mineral apposition rate, and bone formation rate were diminished in mice lacking Lrp5 in osteocytes by 52%, 85%, and 69%, respectively. Collectively, the results support the notion that the loss-of-function mutation of Lrp5 in osteocytes causes suppression of mechanoresponsiveness and reduces bone mass and Young's modulus. In summary, Lrp5-mediated Wnt signaling significantly contributes to maintenance of mechanical properties and bone mass.
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Affiliation(s)
- Liming Zhao
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, IN 46202, USA
| | - Joon W. Shim
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, IN 46202, USA
| | - Todd R. Dodge
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, IN 46202, USA
| | - Alexander G. Robling
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, IN 46202, USA
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Hiroki Yokota
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, IN 46202, USA
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Qi W, Chen R, Chou L, Liu G, Zhang J, Zhou Q, Chen Z. Phase-resolved acoustic radiation force optical coherence elastography. J Biomed Opt 2012; 17:110505. [PMID: 23123971 PMCID: PMC3487536 DOI: 10.1117/1.jbo.17.11.110505] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 09/24/2012] [Accepted: 09/26/2012] [Indexed: 05/18/2023]
Abstract
Many diseases involve changes in the biomechanical properties of tissue, and there is a close correlation between tissue elasticity and pathology. We report on the development of a phase-resolved acoustic radiation force optical coherence elastography method (ARF-OCE) to evaluate the elastic properties of tissue. This method utilizes chirped acoustic radiation force to produce excitation along the sample's axial direction, and it uses phase-resolved optical coherence tomography (OCT) to measure the vibration of the sample. Under 500-Hz square wave modulated ARF signal excitation, phase change maps of tissue mimicking phantoms are generated by the ARF-OCE method, and the resulting Young's modulus ratio is correlated with a standard compression test. The results verify that this technique could efficiently measure sample elastic properties accurately and quantitatively. Furthermore, a three-dimensional ARF-OCE image of the human atherosclerotic coronary artery is obtained. The result indicates that our dynamic phase-resolved ARF-OCE method can delineate tissues with different mechanical properties.
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Affiliation(s)
- Wenjuan Qi
- University of California, Irvine, Beckman Laser Institute, Irvine, 1002 Health Sciences Road East, California 92612
- University of California, Irvine, Department of Chemical Engineering and Materials Science, California 92697
| | - Ruimin Chen
- University of Southern California, Department of Biomedical Engineering, NIH Ultrasonic Transducer Resource Center, Los Angeles, California 90089
| | - Lidek Chou
- University of California, Irvine, Beckman Laser Institute, Irvine, 1002 Health Sciences Road East, California 92612
| | - Gangjun Liu
- University of California, Irvine, Beckman Laser Institute, Irvine, 1002 Health Sciences Road East, California 92612
| | - Jun Zhang
- University of California, Irvine, Beckman Laser Institute, Irvine, 1002 Health Sciences Road East, California 92612
| | - Qifa Zhou
- University of Southern California, Department of Biomedical Engineering, NIH Ultrasonic Transducer Resource Center, Los Angeles, California 90089
| | - Zhongping Chen
- University of California, Irvine, Beckman Laser Institute, Irvine, 1002 Health Sciences Road East, California 92612
- University of California, Irvine, Department of Chemical Engineering and Materials Science, California 92697
- University of California, Irvine, Department of Biomedical Engineering, California 92697
- Address all correspondence to: Zhongping Chen, University of California, Irvine, Beckman Laser Institute, 1002 Health Sciences Road East, California 92612. Tel: 949-824-1247; Fax: 949- 824-8413; E-mail:
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Melzer B, Seidel R, Steinbrecher T, Speck T. Structure, attachment properties, and ecological importance of the attachment system of English ivy (Hedera helix). J Exp Bot 2012; 63:191-201. [PMID: 21914660 PMCID: PMC3245459 DOI: 10.1093/jxb/err260] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 07/16/2011] [Accepted: 08/01/2011] [Indexed: 05/26/2023]
Abstract
Root climbers such as English ivy (Hedera helix) rely on specialized adventitious roots for attachment, enabling the plants to climb on a wide range of natural and artificial substrates. Despite their importance for the climbing habit, the biomechanical properties of these specialized adventitious roots compared with standard roots and their performance in the attachment to different host species or inert substrates have not been studied. Here organs and tissues involved in the attachment are characterized and their significance in regard to a broader functional and ecological aspect is discussed. Depending on the substrate, the root clusters show different types of failure modes at various frequencies, demonstrating the close interaction between the climber and its substrates. With a Young's Modulus of 109.2 MPa, the attachment roots are relatively stiff for non-woody roots. The central cylinders of the attachment roots show a high tensile strength of 38 MPa and a very high extensibility of 34%. In host trees naturally co-distributed with English ivy, a 'balanced' occurrence of failure of the attachment system of the climber and the bark of the host is found, suggesting a co-evolution of climber and host. Maximum loads of root clusters normalized by the number of roots match those of individually tested attachment roots. In comparison with most subterranean roots the properties and structure of the attachment roots of English ivy show distinct differences. There exist similarities to the properties found for roots of Galium aparine, suggesting a trend in not fully self-supporting plants towards a higher extensibility.
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Affiliation(s)
- Björn Melzer
- Plant Biomechanics Group Freiburg, Botanic Garden, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, D-79104 Freiburg, Germany.
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Cheng H, Hill PS, Siegwart DJ, Vacanti N, Lytton-Jean AKR, Cho SW, Ye A, Langer R, Anderson DG. A novel family of biodegradable poly(ester amide) elastomers. Adv Mater 2011; 23:H95-100. [PMID: 21394790 PMCID: PMC3893923 DOI: 10.1002/adma.201003482] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Indexed: 05/20/2023]
Affiliation(s)
- Hao Cheng
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA). Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
| | - Paulina S. Hill
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
| | - Daniel J. Siegwart
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
| | - Nathaniel Vacanti
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
| | - Abigail K. R. Lytton-Jean
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
| | - Seung-Woo Cho
- Department of Biotechnology, Yonsei University, Seoul 120-749 (Korea)
| | - Anne Ye
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
| | - Robert Langer
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA). Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA). Division of Health Science Technology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
| | - Daniel G. Anderson
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA). Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA). Division of Health Science Technology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (USA)
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Liu LZ, Gao HL, Zhao JJ, Lu JP. Superelasticity of Carbon Nanocoils from Atomistic Quantum Simulations. Nanoscale Res Lett 2010; 5:478-483. [PMID: 20671790 PMCID: PMC2893780 DOI: 10.1007/s11671-010-9545-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2009] [Accepted: 01/16/2010] [Indexed: 05/29/2023]
Abstract
A structural model of carbon nanocoils (CNCs) on the basis of carbon nanotubes (CNTs) was proposed. The Young's moduli and spring constants of CNCs were computed and compared with those of CNTs. Upon elongation and compression, CNCs exhibit superelastic properties that are manifested by the nearly invariant average bond lengths and the large maximum elastic strain limit. Analysis of bond angle distributions shows that the three-dimensional spiral structures of CNCs mainly account for their unique superelasticity.
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Affiliation(s)
- Li Zhao Liu
- Laboratory of Materials Modification by Laser, Electron, and Ion Beams, and College of Advanced Science and Technology, Dalian University of Technology, 116024, Dalian, China
| | - Hai Li Gao
- Laboratory of Materials Modification by Laser, Electron, and Ion Beams, and College of Advanced Science and Technology, Dalian University of Technology, 116024, Dalian, China
| | - Ji Jun Zhao
- Laboratory of Materials Modification by Laser, Electron, and Ion Beams, and College of Advanced Science and Technology, Dalian University of Technology, 116024, Dalian, China
- Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials, Huaiyin Normal University, 223300, Huaian, China
| | - Jian Ping Lu
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
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Abstract
Atomic force microscopy (AFM) was used to quantify both the nanomechanical properties of pathogenic (ATCC 51776 & EGDe) and non-pathogenic (ATCC 15313 & HCC25) Listeria monocytogenes strains and the conformational properties of their surface biopolymers. The nanomechanical properties of the various L. monocytogenes strains were quantified in terms of Young's moduli of cells. To estimate Young's moduli, the classic Hertz model of contact mechanics and a modified version of it that takes into account substrate effects were used to fit the AFM nanoindentation-force measurements collected while pushing onto the bacterial surface biopolymer brush. When compared, the classic Hertz model always predicted higher Young's moduli values of bacterial cell elasticity compared to the modified Hertz model. On average, the modified Hertz model showed that virulent strains are approximately twice as rigid (88.1 ± 14.5 KPa) as the avirulent strains (47.3 ± 7.6 kPa). To quantify the conformational properties of L. monocytogenes' strains surface biopolymers, two models were used. First, the entropic-based, statistical mechanical, random walk formulation, the wormlike chain (WLC) model was used to estimate the elastic properties of the bacterial surface molecules. The WLC model results indicated that the virulent strains are characterized by a more flexible surface biopolymers as indicated by shorter persistence lengths (L(p) = 0.21 ± 0.08 nm) compared to the avirulent strains (L(p) = 0.24 ± 0.14 nm). Second, a steric model developed to describe the repulsive forces measured between the AFM tip and bacterial surface biopolymers indicated that the virulent strains are characterized by crowded and longer biopolymer brushes compared to those of the avirulent strains. Finally, scaling relationships developed for grafted polyelectrolyte brushes indicated L. monocytogenes strains' biopolymer brushes are charged. Collectively, our data indicate that the conformational properties of the bacterial surface biopolymers and their surface densities play an important role in controlling the overall bacterial cell elasticity.
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Affiliation(s)
| | - Nehal I. Abu-Lail
- Corresponding Author: Nehal I. Abu-Lail, Ph.D., Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-2710, United States, , 509-335-4961
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Chou AI, Akintoye SO, Nicoll SB. Photo-crosslinked alginate hydrogels support enhanced matrix accumulation by nucleus pulposus cells in vivo. Osteoarthritis Cartilage 2009; 17:1377-84. [PMID: 19427928 PMCID: PMC2753687 DOI: 10.1016/j.joca.2009.04.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 02/10/2009] [Accepted: 04/16/2009] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Intervertebral disc (IVD) degeneration is a major health concern in the United States. Replacement of the nucleus pulposus (NP) with injectable biomaterials represents a potential treatment strategy for IVD degeneration. The objective of this study was to characterize the extracellular matrix (ECM) assembly and functional properties of NP cell-encapsulated, photo-crosslinked alginate hydrogels in comparison to ionically crosslinked alginate constructs. METHODS Methacrylated alginate was synthesized by esterification of hydroxyl groups with methacrylic anhydride. Bovine NP cells were encapsulated in alginate hydrogels by ionic crosslinking using CaCl(2) or through photo-crosslinking upon exposure to long-wave UV light in the presence of a photoinitiator. The hydrogels were evaluated in vitro by gross and histological analysis and in vivo using a murine subcutaneous pouch model. In vivo samples were analyzed for gene expression, ECM localization and accumulation, and equilibrium mechanical properties. RESULTS Ionically crosslinked hydrogels exhibited inferior proteoglycan accumulation in vitro and were unable to maintain structural integrity in vivo. In further studies, photo-crosslinked alginate hydrogels were implanted for up to 8 weeks to examine NP tissue formation. Photo-crosslinked hydrogels displayed temporal increases in gene expression and assembly of type II collagen and proteoglycans. Additionally, hydrogels remained intact over the duration of the study and the equilibrium Young's modulus increased from 1.24+/-0.09 kPa to 4.31+/-1.39 kPa, indicating the formation of functional matrix with properties comparable to those of the native NP. CONCLUSIONS These findings support the use of photo-crosslinked alginate hydrogels as biomaterial scaffolds for NP replacement.
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Affiliation(s)
- Alice I. Chou
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Sunday O. Akintoye
- Department of Oral Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Steven B. Nicoll
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104,Corresponding Author: Steven B. Nicoll, Ph.D., Assistant Professor, Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S. 33rd Street, Philadelphia, PA 19104-6321, Tel: 215-573-2626, Fax: 215-573-2071, , Alice I. Chou, B.S.E., 240 Skirkanich Hall, 210 S. 33rd Street, Philadelphia, PA 19104, Tel: 215-898-1958, Fax: 215-573-2071, , Sunday O. Akintoye, D.D.S., Assistant Professor, Department of Oral Medicine, 209 Robert Schattner Center, 240 S. 40th Street, Philadelphia, PA 19104, Tel: 215-898-9932, Fax: 215-573-7853,
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Manoharan MP, Lee H, Rajagopalan R, Foley HC, Haque MA. Elastic Properties of 4-6 nm-thick Glassy Carbon Thin Films. Nanoscale Res Lett 2009; 5:14-19. [PMID: 20652145 PMCID: PMC2894143 DOI: 10.1007/s11671-009-9435-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 09/02/2009] [Indexed: 05/12/2023]
Abstract
Glassy carbon is a disordered, nanoporous form of carbon with superior thermal and chemical stability in extreme environments. Freestanding glassy carbon specimens with 4-6 nm thickness and 0.5 nm average pore size were synthesized and fabricated from polyfurfuryl alcohol precursors. Elastic properties of the specimens were measured in situ inside a scanning electron microscope using a custom-built micro-electro-mechanical system. The Young's modulus, fracture stress and strain values were measured to be about 62 GPa, 870 MPa and 1.3%, respectively; showing strong size effects compared to a modulus value of 30 GPa at the bulk scale. This size effect is explained on the basis of the increased significance of surface elastic properties at the nanometer length-scale.
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Affiliation(s)
- MP Manoharan
- Department of Mechanical & Nuclear Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - H Lee
- Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - R Rajagopalan
- Materials Research Institute, The Pennsylvania State University, University Park, PA, 16802, USA
| | - HC Foley
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - MA Haque
- Department of Mechanical & Nuclear Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
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Abstract
Elastography is a new imaging modality where elastic tissue parameters related to the structural organization of normal and pathological tissues are imaged. Basic principles underlying the quasi-static elastography concept and principles are addressed. The rationale for elastographic imaging is reinforced using data on elastic properties of normal and abnormal soft tissues. The several orders of magnitude difference between the elastic modulus of normal and abnormal tissues which is the primary contrast mechanism in elastographic imaging underlines the probability of success with this imaging modality. Recent advances enabling the clinical practice of elastographic imaging in real-time on clinical ultrasound systems is also discussed.In quasi-static elastography, radiofrequency echo signals acquired before and after a small (about 1%) of applied deformation are correlated to estimate tissue displacements. Local tissue displacement vector estimates between small segments of the pre- and post-deformation signals are estimated and the corresponding strain distribution imaged. Elastographic imaging techniques are based on the hypothesis that soft tissues deform more than stiffer tissue, and these differences can be quantified in images of the tissue strain tensor or the Young's modulus.Clinical applications of quasi-static elastography have mushroomed over the last decade, with the most commonly imaged areas being the breast, prostate, thyroid, cardiac, treatment monitoring of ablation procedures and vascular imaging applications.
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Affiliation(s)
- Tomy Varghese
- Department of Medical Physics, The University of Wisconsin-Madison, Madison, WI-53706, USA
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Zhu Q, Shih WY, Shih WH. Enhanced Detection Resonance Frequency Shift of a Piezoelectric Microcantilever Sensor by a DC Bias Electric Field in Humidity Detection. Sens Actuators B Chem 2009; 138:1-4. [PMID: 20161253 PMCID: PMC2711390 DOI: 10.1016/j.snb.2009.01.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have examined the relative longitudinal flexural resonance frequency shift of a PMN-PT/tin PEMS with a DC bias electric field, E, in humidity detection. We showed that the relative resonance frequency shift could be enhanced by applying an E to the PMN-PT layer during detection. A maximum enhancement of more than three times in resonance frequency shift was observed at E = -6 kV/cm as compared to the resonance frequency shift without a bias field. The maximal relative resonance frequency shift at E = -6 kV/cm was about 1000 times larger than could be accounted for by mass loading alone.
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Affiliation(s)
- Qing Zhu
- Department of Materials Science and Engineering, Drexel University, Philadelphia, PA 19104
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Kurutz M, Donáth J, Gálos M, Varga P, Fornet B. Age- and sex-related regional compressive strength characteristics of human lumbar vertebrae in osteoporosis. J Multidiscip Healthc 2008; 1:105-21. [PMID: 21197342 PMCID: PMC3004543 DOI: 10.2147/jmdh.s4103] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE To obtain the compressive load bearing and energy absorption capacity of lumbar vertebrae of osteoporotic elderly for the everyday medical praxis in terms of the simple diagnostic data, like computed tomography (CT), densitometry, age, and sex. METHODS Compressive test of 54 osteoporotic cadaver vertebrae L1 and L2, 16 males and 38 females (age range 43-93, mean age 71.6 ± 13.3 years, mean bone mineral density (BMD) 0.377 ± 0.089 g/cm(2), mean T-score -5.57 ± 0.79, Z-score -4.05 ± 0.77) was investigated. Based on the load-displacement diagrams and the measured geometrical parameters of vertebral bodies, proportional, ultimate and yield stresses and strains, Young's modulus, ductility and energy absorption capacity were determined. Three vertebral regions were distinguished: superior, central and inferior regions, but certain parameters were calculated for the upper/ lower intermediate layers, as well. Cross-sectional areas, and certain bone tissue parameters were determined by image analysis of CT pictures of vertebrae. Sex- and age-related decline functions and trends of strength characteristics were determined. RESULTS Size-corrected failure load was 15%-25% smaller in women, proportional and ultimate stresses were about 30%-35% smaller for women in any region, and 20%-25% higher in central regions for both sexes. Young's moduli were about 30% smaller in women in any region, and 20%-25% smaller in the central region for both sexes. Small strains were higher in males, large strains were higher in females, namely, proportional strains were about 25% larger in men, yield and ultimate strains were quasi equal for sexes, break strains were 10% higher in women. Ultimate energy absorption capacity was 10%-20% higher in men; the final ductile energy absorption capacity was quasi equal for sexes in all levels. Age-dependence was stronger for men, mainly in central regions (ultimate load, male: r = -0.66, p < 0.01, female: r = -0.52, p < 0.005; ultimate stress, male: r = -0.69, p < 0.01, female: r = -0.50, p < 0.005; Young's modulus, male: r = -0.55, p < 0.05, female: r = -0.52, p < 0.005, ultimate stiffness, male: r = -0.58, p < 0.05, female: r = -0.35, p < 0.03, central ultimate absorbed energy density, male: r = -0.59, p < 0.015, female: r = -0.29, p < 0.08). CONCLUSIONS For the strongly osteoporotic population (BMD < 0.4 g/cm(2), T-score < -4) the statical variables (loads, stresses) showed significant correlation; mixed variables (stiffness, Young's modulus, energy) showed moderate correlation; kinematical variables (displacements, strains) showed no correlation with age. The strong correlation of men between BMD and aging (r = -0.82, p < 0.001) and betwen BMD and strength parameters (r = 0.8-0.9, p < 0.001) indicated linear trends in age-related strength loss for men; however, the moderate correlation of women between BMD and aging (r = -0.47, p < 0.005) and between BMD and strength parameters (r = 0.4-0.5, p < 0.005) suggested the need of nonlinear (quadratic) approximation that provided the better fit in age-related strength functions of females modelling postmenopausal disproportionalities.
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Abstract
We have developed a device entitled the 'Tissue Elastometer' (TE) for evaluating the Young's modulus of soft tissues. Soft tissue specimens are compressed between the object plate of an electronic balance and a linearly actuated indenter with a small rounded tip. The hardware of the device was designed such that a deformation model for semi-infinite media is applicable for calculating the Young's modulus of test specimens from their collected force-displacement data. Force-elongation measurements were performed on long strips of cured silicone mixtures to produce calibrated, tissue-mimicking test samples for the TE in a Young's modulus range of 10-400 kPa. When tested with the TE, the Young's moduli of the silicone samples demonstrated accuracy to within 1-10% of their calibrated values. Testing on excised tissue samples (fresh store-bought poultry breast; bovine liver, kidneys, hind shanks; porcine) was also performed, and a repeatability of elasticity measurements was demonstrated in the range of 8-14%. Results indicate that the TE can be effectively used in laboratory and clinical environments to evaluate the elasticity modulus of tissues.
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Affiliation(s)
- V. Egorov
- Artann Laboratories, Trenton, NJ, USA
| | | | - S. Kanilo
- Artann Laboratories, Trenton, NJ, USA
| | - M. Kogit
- Artann Laboratories, Trenton, NJ, USA
- Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, NJ, USA
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Zhang M, Castaneda B, Wu Z, Nigwekar P, Joseph JV, Rubens DJ, Parker KJ. Congruence of imaging estimators and mechanical measurements of viscoelastic properties of soft tissues. Ultrasound Med Biol 2007; 33:1617-31. [PMID: 17604902 PMCID: PMC2093922 DOI: 10.1016/j.ultrasmedbio.2007.04.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Revised: 03/29/2007] [Accepted: 04/19/2007] [Indexed: 05/05/2023]
Abstract
Biomechanical properties of soft tissues are important for a wide range of medical applications, such as surgical simulation and planning and detection of lesions by elasticity imaging modalities. Currently, the data in the literature is limited and conflicting. Furthermore, to assess the biomechanical properties of living tissue in vivo, reliable imaging-based estimators must be developed and verified. For these reasons, we developed and compared two independent quantitative methods--crawling wave estimator (CRE) and mechanical measurement (MM) for soft tissue characterization. The CRE method images shear wave interference patterns from which the shear wave velocity can be determined and hence the Young's modulus can be obtained. The MM method provides the complex Young's modulus of the soft tissue from which both elastic and viscous behavior can be extracted. This article presents the systematic comparison between these two techniques on the measurement of gelatin phantom, veal liver, thermal-treated veal liver and human prostate. It was observed that the Young's moduli of liver and prostate tissues slightly increase with frequency. The experimental results of the two methods are highly congruent, suggesting CRE and MM methods can be reliably used to investigate viscoelastic properties of other soft tissues, with CRE having the advantages of operating in nearly real time and in situ.
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Affiliation(s)
- Man Zhang
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA
| | - Benjamin Castaneda
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
| | - Zhe Wu
- GE Ultrasound, Wauwatosa, WI, USA
| | - Priya Nigwekar
- University of Rochester Medical Center, Rochester, NY, USA
| | - Jean V. Joseph
- University of Rochester Medical Center, Rochester, NY, USA
| | | | - Kevin J. Parker
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
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Xie H, Kim K, Aglyamov SR, Emelianov SY, O’Donnell M, Weitzel WF, Wrobleski SK, Myers DD, Wakefield TW, Rubin JM. Correspondence of ultrasound elasticity imaging to direct mechanical measurement in aging DVT in rats. Ultrasound Med Biol 2005; 31:1351-9. [PMID: 16223638 PMCID: PMC1343482 DOI: 10.1016/j.ultrasmedbio.2005.06.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Revised: 05/26/2005] [Accepted: 06/07/2005] [Indexed: 05/04/2023]
Abstract
Previous ultrasound elasticity imaging experiments supported a generally accepted concept that the hardness of deep venous thrombi increases with thrombus aging. Results also showed that this noninvasive imaging technique can accurately predict thrombus age through strain estimates, in a well-controlled animal study. In the present study, as an alternative means to characterize elastic properties of thrombi, we used a direct mechanical measurement system to estimate Young's modulus of ex vivo thrombi. Unlike conventional indentation tests, the device uses a specific compression geometry for cylindrical tissue specimens. We also proposed an approximation scheme to retrieve Young's modulus from force-displacement measurements made using the device. Finite element simulations and calibrations on tissue-mimicking phantoms validated the system. Then, using two groups of rats with surgically-induced thrombi, we further investigated the correlation between Young's modulus measured ex vivo and elasticity images reconstructed in vivo. This comparison was accomplished by converting the intrathrombus strains measured in the in vivo studies into Young's modulus estimates using a model-based approach. Good agreement between time-dependent Young's modulus estimates observed in vivo and direct measurements of Young's modulus using the mechanical device helps to confirm the ability of elasticity imaging to age deep venous thrombi for efficient treatment.
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Affiliation(s)
- Hua Xie
- Departments of Biomedical Engineering
| | - Kang Kim
- Departments of Biomedical Engineering
| | - Salavat R. Aglyamov
- Biomedical Engineering, University of Texas at Austin, Austin, TX 78712, USA
| | | | | | | | | | | | | | - Jonathan M. Rubin
- Radiology University of Michigan, Ann Arbor, MI 48109, USA
- Address correspondence to: Dr. Jonathan M. Rubin, Department of Radiology, University of Michigan Hospital, 1500 E. Medical Center Dr., Ann Arbor, MI 48109, USA,
, Phone: 734-936-4487, Fax: 734-763-9523
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Afrin R, Alam MT, Ikai A. Pretransition and progressive softening of bovine carbonic anhydrase II as probed by single molecule atomic force microscopy. Protein Sci 2005; 14:1447-57. [PMID: 15929995 PMCID: PMC2253376 DOI: 10.1110/ps.041282305] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Revised: 03/06/2005] [Accepted: 03/11/2005] [Indexed: 10/25/2022]
Abstract
To develop a simple method for probing the physical state of surface adsorbed proteins, we adopted the force curve mode of an atomic force microscope (AFM) to extract information on the mechanical properties of surface immobilized bovine carbonic anhydrase II under native conditions and in the course of guanidinium chloride-induced denaturation. A progressive increase in the population of individually softened molecules was probed under mildly to fully denaturing conditions. The use of the approach regime of force curves gave information regarding the height and rigidity of the molecule under compressive stress, whereas use of the retracting regime of the curves gave information about the tensile characteristics of the protein. The results showed that protein molecules at the beginning of the transition region possessed slightly more flattened and significantly more softened conformations compared with that of native molecules, but were still not fully denatured, in agreement with results based on solution studies. Thus the force curve mode of an AFM was shown to be sensitive enough to provide information concerning the different physical states of single molecules of globular proteins.
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Affiliation(s)
- Rehana Afrin
- Laboratory of Biodynamics, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuka, Midori-ku, Yokohama, 226-8501, Japan
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Abstract
BACKGROUND AND AIMS The relationship between composition and structure of plant primary cell walls, and cell mechanical properties is not fully understood, partly because intrinsic properties of walls such as Young's modulus cannot be obtained readily. The aim of this work is to show that Young's modulus of walls of single suspension-cultured tomato cells can be determined by modelling force-deformation data. METHODS The model simulates the compression of a cell between two flat surfaces, with the cell treated as a liquid-filled sphere with thin compressible walls. The cell wall and membrane were taken to be permeable, but the compression was so fast that water loss could be neglected in the simulations. Force-deformation data were obtained by compressing the cells in micromanipulation experiments. RESULTS Good fits were obtained between the model and low-strain experimental data, using the modulus and initial inflation of the cell as adjustable parameters. The mean Young's modulus for 2-week-old cells was found to be 2.3 +/- 0.2 GPa at pH 5. This corresponds to an instantaneous bulk modulus of elasticity of approx. 7 MPa, similar to a value found by the pressure probe method. However, Young's modulus is a better parameter, as it should depend only on the composition and structure of the cell wall, not on bulk cell behaviour. This new method has been used to show that Young's modulus of cultured tomato cell walls is at its lowest at pH 4.5, the pH optimum for expansin activity. CONCLUSIONS The linear elastic model is very suitable for estimating wall Young's modulus from micromanipulation experiments on single tomato cells. This is a powerful method for determining cell wall material properties.
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Affiliation(s)
- C. X. WANG
- Centre for Formulation Engineering, School of Engineering
| | - L. WANG
- School of Dentistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - C. R. THOMAS
- Centre for Formulation Engineering, School of Engineering
- * For correspondence. E‐mail:
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Abstract
In a previous study, we reported the upper limit of Young's modulus of the unprotected protein at the dentin/adhesive interface to be 2 GPa. In this study, to obtain a more exact value of the moduli of the components at the d/a interface, we used demineralized dentin collagen with and without adhesive infiltration. The prepared samples were analyzed using micro-Raman spectroscopy (micro RS) and scanning acoustic microscopy (SAM). Using an Olympus UH3 SAM (Olympus Co., Tokyo), measurements were recorded with a 400 MHz burst mode lens (120 degrees aperture angle; nominal lateral resolution, 2.5 microm). A series of calibration curves were prepared using the relationship between the ultrasonically measured elastic moduli of a set of known materials and their SAM response. Finally, both the bulk and bar wave elastic moduli were computed for a set of 13 materials, including polymers, ceramics, and metals. These provided the rationale for using extensional wave measurements of the elastic moduli as the basis for extrapolation of the 400 MHz SAM data to obtain Young's moduli for the samples: E = 1.76 +/- 0.00 GPa for the collagen alone; E = 1.84 +/- 0.65 GPa for the collagen infiltrated with adhesive; E = 3.4 +/- 1.00 GPa for the adhesive infiltrate.
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Affiliation(s)
- J Lawrence Katz
- Department of Biomedical Engineering, Case School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
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