scholarly journals Cardiomyocyte mechanodynamics under conditions of actin remodelling

2019 ◽  
Vol 374 (1786) ◽  
pp. 20190081 ◽  
Author(s):  
Ricardo H. Pires ◽  
Nithya Shree ◽  
Emmanuel Manu ◽  
Ewa Guzniczak ◽  
Oliver Otto
Keyword(s):  
Stem Cells ◽  
Real Time ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Mechanical Analysis ◽  
Adherent Cells ◽  
Filamentous Actin ◽  
Important Indicator ◽  
Compound Exposure

The mechanical performance of cardiomyocytes (CMs) is an important indicator of their maturation state and of primary importance for the development of therapies based on cardiac stem cells. As the mechanical analysis of adherent cells at high-throughput remains challenging, we explore the applicability of real-time deformability cytometry (RT-DC) to probe cardiomyocytes in suspension. RT-DC is a microfluidic technology allowing for real-time mechanical analysis of thousands of cells with a throughput exceeding 1000 cells per second. For CMs derived from human-induced pluripotent stem cells, we determined a Young's modulus of 1.25 ± 0.08 kPa which is in close range to previous reports. Upon challenging the cytoskeleton with cytochalasin D (CytoD) to induce filamentous actin depolymerization, we distinguish three different regimes in cellular elasticity. Transitions are observed below 10 nM and above 10 3 nM and are characterized by a decrease in Young's modulus. These regimes can be linked to cytoskeletal and sarcomeric actin contributions by CM contractility measurements at varying CytoD concentrations, where we observe a significant reduction in pulse duration only above 10 3 nM while no change is found for compound exposure at lower concentrations. Comparing our results to mechanical cell measurements using atomic force microscopy, we demonstrate for the first time to our knowledge, the feasibility of using a microfluidic technique to measure mechanical properties of large samples of adherent cells while linking our results to the composition of the cytoskeletal network. This article is part of a discussion meeting issue ‘Single cell ecology'.

Calorimetric and Thermomechanical Properties of Titanium-Based Orthodontic Wires: DSC–DMA Relationship to Predict the Elastic Modulus

2011 ◽  
Vol 26 (7) ◽  
pp. 829-844 ◽  
Author(s):  
Giuliana Laino ◽  
Roberto De Santis ◽  
Antonio Gloria ◽  
Teresa Russo ◽  
David Suárez Quintanilla ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Experimental Tests ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Scanning Calorimetry ◽  
Orthodontic Wires ◽  
Gum Metal

Orthodontic treatment is strongly dependent on the loads developed by metal wires, and the choice of an orthodontic archwire should be based on its mechanical performance. The desire of both orthodontists and engineers would be to predict the mechanical behavior of archwires. To this aim, Gum Metal (Toyota Central R&L Labs., Inc.), TMA (ORMCO), 35°C Copper NiTi (SDS ORMCO), Thermalloy Plus (Rocky Mountain), Nitinol SE (3M Unitek), and NiTi (SDS ORMCO) were tested according to dynamic mechanical analysis and differential scanning calorimetry. A model was also developed to predict the elastic modulus of superelastic wires. Results from experimental tests have highlighted that superelastic wires are very sensitive to temperature variations occurring in the oral environment, while the proposed model seems to be reliable to predict the Young’s modulus allowing to correlate calorimetric and mechanical data. Furthermore, Gum Metal wire behaves as an elastic material with a very low Young’s modulus, and it can be particularly useful for the initial stage of orthodontic treatments.

Indentation Tests for Sintered Silver in Die-Attach Interconnection After Thermal Cycling

2021 ◽  
Author(s):  
Fei Qin ◽  
Shuai Zhao ◽  
Yanwei Dai ◽  
Lingyun Liu ◽  
Tong An ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Silver Layer ◽  
Thermal Cycles ◽  
Nano Indentation ◽  
Die Attach ◽  
Indentation Tests ◽  
Sintered Silver

Abstract Thermo-mechanical reliability assessment for sintered silver is a crucial issue as sintered silver is a promising candidate of die-attachment materials for power devices. In this paper, the nano-indentation tests are performed for sintered silver in typical die-attach interconnection under different thermal cycles. Based on thermal cycling test, the Young's modulus and hardness of sintered silver layer have been presented. It is found that the Young's modulus and hardness of sintered silver layer changes slightly although the microstructure of sintered silver also presents some variations. The stress and strain curves for different thermal cycling tests for sintered silver based on reverse analysis of nano-indentation are also given. The results show that the elastoplastic constitutive equations change significantly after thermal cycling tests, and the yielding stress decreases remarkably after 70 thermal cycles. The experimental investigation also show that the cracking behaviors of sintered silver depends on its geometry characteristics, which implies that the possible optimization of sintered silver layer could enhance its thermo-mechanical performance.

scholarly journals Loss of clathrin heavy chain enhances actin-dependent stiffness of mouse embryonic stem cells

2020 ◽  
Author(s):  
Ridim D Mote ◽  
Jyoti Yadav ◽  
Surya Bansi Singh ◽  
Mahak Tiwari ◽  
Shivprasad Patil ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Young’S Modulus ◽  
Heavy Chain ◽  
Young's Modulus ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cells ◽  
Actin Binding ◽  
Clathrin Heavy Chain

AbstractMouse embryonic stem cells (mESCs) display unique mechanical properties, including low cell stiffness, and specific responses to features of the underlying substratum. Using atomic force microscopy (AFM), we demonstrate that mESCs lacking the clathrin heavy chain (Cltc), display higher Young’s modulus, indicative of greater cellular stiffness, in comparison to WT mESCs. We have previously shown that mESCs lacking Cltc display a loss of pluripotency, and an initiation of differentiation. The increased stiffness observed in these cells was accompanied by the presence of actin stress fibres and accumulation of the inactive, phosphorylated, actin binding protein, Cofilin. Treatment of Cltc knockdown mESCs with actin polymerization inhibitors resulted in a decrease in the Young’s modulus, to values similar to those obtained with WT mESCs. However, the expression profile of pluripotency factors was not rescued. This indicates that a restoration of mechanical properties, through modulation of the actin cytoskeleton, may not always be accompanied by a change in the expression of critical transcription factors that regulate the state of a stem cell, and that this may be dependent on the presence of active endocytosis in a cell.

The impact of body position and exercise on the measurement of liver Young’s modulus by real-time shear wave elastography

2021 ◽  
pp. 1-10
Author(s):  
Xia Jiang ◽  
Li Li ◽  
Hong-Yuan Xue
Keyword(s):  
Healthy Volunteers ◽  
Real Time ◽  
Young’S Modulus ◽  
Shear Wave ◽  
Supine Position ◽  
Young's Modulus ◽  
Body Position ◽  
Shear Wave Elastography ◽  
Lateral Position ◽  
Left Lateral Position

BACKGROUND: In the past ten years, liver biopsies have been used as a method to accurately diagnose the stage of fibrosis. OBJECTIVE: This study aimed to evaluate whether body position and exercise affect the measurement of liver Young’s modulus of healthy volunteers by real-time shear wave elastography (RT-SWE). Methods: RT-SWE was used to measure liver Young’s modulus in the supine and left lateral positions of 70 healthy volunteers at rest and measure the liver Young’s modulus in the lying position before exercise, and at zero, five, and ten minutes of rest after exercise. RESULTS: The liver Young’s modulus in the left lateral position was significantly higher than in the supine position (P< 0.05), and the measured value in the supine position was more stable than the left lateral position. The liver Young’s modulus measured at zero minutes after exercise was significantly higher than that measured before exercise (P< 0.05). The liver Young’s modulus measured at five minutes after exercise was significantly higher than that measured at zero minutes after exercise (P<0.05) and was not statistically different from the measured value before exercise (P> 0.05). The liver Young’s modulus measured at ten minutes after exercise was significantly higher from that measured at zero minutes after exercise (P< 0.05) and was not statistically different from the measured value at five minutes after exercise (P> 0.05). CONCLUSION: Body position and exercise have a significant impact on the measurement of liver Young’s modulus. It is recommended that the examinees take a supine position during the measurement, and measurement should be conducted at least ten minutes after exercise.

scholarly journals AFM-based Analysis of Wharton’s Jelly Mesenchymal Stem Cells

2019 ◽  
Vol 20 (18) ◽  
pp. 4351
Author(s):  
Renata Szydlak ◽  
Marcin Majka ◽  
Małgorzata Lekka ◽  
Marta Kot ◽  
Piotr Laidler
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Wharton’S Jelly ◽  
In Vitro Cultivation ◽  
Multipotent Stem Cells ◽  
Wharton's Jelly ◽  
Migration Potential

Wharton’s jelly mesenchymal stem cells (WJ-MSCs) are multipotent stem cells that can be used in regenerative medicine. However, to reach the high therapeutic efficacy of WJ-MSCs, it is necessary to obtain a large amount of MSCs, which requires their extensive in vitro culturing. Numerous studies have shown that in vitro expansion of MSCs can lead to changes in cell behavior; cells lose their ability to proliferate, differentiate and migrate. One of the important measures of cells’ migration potential is their elasticity, determined by atomic force microscopy (AFM) and quantified by Young’s modulus. This work describes the elasticity of WJ-MSCs during in vitro cultivation. To identify the properties that enable transmigration, the deformability of WJ-MSCs that were able to migrate across the endothelial monolayer or Matrigel was analyzed by AFM. We showed that WJ-MSCs displayed differences in deformability during in vitro cultivation. This phenomenon seems to be strongly correlated with the organization of F-actin and reflects the changes characteristic for stem cell maturation. Furthermore, the results confirm the relationship between the deformability of WJ-MSCs and their migration potential and suggest the use of Young’s modulus as one of the measures of competency of MSCs with respect to their possible use in therapy.

scholarly journals Kinetics of Capability Aging in Ti-13Nb-13Zr Alloy

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 693 ◽  
Author(s):  
Myoungjae Lee ◽  
In-Su Kim ◽  
Young Hoon Moon ◽  
Hyun Sik Yoon ◽  
Chan Hee Park ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Solution Treatment ◽  
High Strength ◽  
Biomedical Implant ◽  
13Zr Alloy ◽  
American Society ◽  
Kinetics Of

Metals for biomedical implant applications require a simultaneous achievement of high strength and low Young’s modulus from the viewpoints of mechanical properties. The American Society for Testing and Materials (ASTM) standards suggest two types of processing methods to confer such a mechanical performance to Ti-13Nb-13Zr alloy: solution treatment (ST) and capability aging (CA). This study elucidated the kinetics of CA process in Ti-13Nb-13Zr alloy. Microstructural evolution and mechanical change were investigated depending on the CA duration from 10 min to 6 h. The initial ST alloy possessed the full α′-martensitic structure, leading to a low strength, low Young’s modulus, and high ductility. Increasing CA duration increased mechanical strength and Young’s modulus in exchange for the reduction of ductility. Such a tendency is attributed to the decomposition of α′ martensite into (α+β) structure, particularly hard α precipitates. Mechanical compatibility (i.e., Young’s modulus compensated with a mechanical strength) of Ti-13Nb-13Zr alloy rarely increased by changing CA duration, suggestive of the intrinsic limit of static heat treatment.

Graphene oxide and zinc oxide decorated chitosan nanocomposite biofilms for packaging applications

2020 ◽  
Vol 40 (2) ◽  
pp. 152-157 ◽  
Author(s):  
Pınar Terzioglu ◽  
Yasin Altin ◽  
Ayse Kalemtas ◽  
Ayse Celik Bedeloglu
Keyword(s):  
Tensile Strength ◽  
Zinc Oxide ◽  
Graphene Oxide ◽  
Composite Film ◽  
Young’S Modulus ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Chitosan Film ◽  
Oxide Composite ◽  
Wide Range

AbstractRecently, due to sustainable development and environmental protection policies, there is increasing interest in the development of new biodegradable polymer-based multifunctional composites. Chitosan is one of the most remarkable and preferred biopolymers, which is environmentally friendly as well as renewable, biocompatible, and inexpensive. Though it has a wide range of potential applications, the major limitation of chitosan – the problem of poor mechanical performance – needs to be solved. In this work, graphene oxide was first produced and then used to manufacture a chitosan/graphene oxide/zinc oxide composite film through a casting method. The properties of the chitosan film and the chitosan/graphene oxide/zinc oxide composite film were investigated using Fourier transform infrared spectroscopy, mechanical, thermal gravimetric, and ultraviolet (UV)-visible spectroscopy analyses. The results showed that the incorporation of graphene oxide and zinc oxide into the chitosan matrix resulted in enhanced mechanical properties and thermal stability of chitosan biocomposite films. The graphene oxide- and zinc oxide-reinforced chitosan film showed 2527 MPa and 55.72 MPa of Young’s modulus and tensile strength, respectively, while neat chitosan showed only 1549 MPa and 37.91 MPa of Young’s modulus and tensile strength, respectively. Conversely, the addition of graphene oxide decreased the transmittance, notably in the UV region.

scholarly journals Cholesterol-Dependent Modulation of Stem Cell Biomechanics: Application to Adipogenesis

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Shan Sun ◽  
Djanybek Adyshev ◽  
Steven Dudek ◽  
Amit Paul ◽  
Andrew McColloch ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Stem Cell ◽  
Young’S Modulus ◽  
Cell Mechanics ◽  
Young's Modulus ◽  
Adipogenic Differentiation ◽  
Stem Cell Differentiation ◽  
Cell Stiffness ◽  
Cholesterol Depletion

Cell mechanics has been shown to regulate stem cell differentiation. We have previously reported that altered cell stiffness of mesenchymal stem cells can delay or facilitate biochemically directed differentiation. One of the factors that can affect the cell stiffness is cholesterol. However, the effect of cholesterol on differentiation of human mesenchymal stem cells remains elusive. In this paper, we demonstrate that cholesterol is involved in the modulation of the cell stiffness and subsequent adipogenic differentiation. Rapid cytoskeletal actin reorganization was evident and correlated with the cell's Young's modulus measured using atomic force microscopy. In addition, the level of membrane-bound cholesterol was found to increase during adipogenic differentiation and inversely varied with the cell stiffness. Furthermore, cholesterol played a key role in the regulation of the cell morphology and biomechanics, suggesting its crucial involvement in mechanotransduction. To better understand the underlying mechanisms, we investigated the effect of cholesterol on the membrane–cytoskeleton linker proteins (ezrin and moesin). Cholesterol depletion was found to upregulate the ezrin expression which promoted cell spreading, increased Young's modulus, and hindered adipogenesis. In contrast, cholesterol enrichment increased the moesin expression, decreased Young's modulus, and induced cell rounding and facilitated adipogenesis. Taken together, cholesterol appears to regulate the stem cell mechanics and adipogenesis through the membrane-associated linker proteins.

Evaluation of Mechanical Properties of Regenerated Bone by Nanoindentation Technique

2010 ◽  
Vol 654-656 ◽  
pp. 2220-2224 ◽  
Author(s):  
Takuya Ishimoto ◽  
Takayoshi Nakano
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Bone Tissue ◽  
Material Properties ◽  
Mechanical Performance ◽  
Young's Modulus ◽  
Mechanical Tests ◽  
Long Bone ◽  
Nanoindentation Technique ◽  
Intact Bone

To evaluate the material parameters of regenerated bone, it is important to clarify the mechanical performance of the regenerated portion. In general, the shape and size of regenerated bone tissue is heterogeneous. It is often difficult to elucidate material properties by means of conventional mechanical tests such as compressive and/or tensile tests and bending tests. The nanoindentation technique has been utilized to evaluate the material properties of small or microstructured materials because they do not necessarily require a large well-designed specimen. Thus, this technique may be useful for the evaluation of the material properties of regenerated bone tissue. In this study, this technique was applied for the assessment of the Young’s modulus and hardness of regenerated and intact long bones of a rabbit. The regenerated bone exhibited a significantly lower Young’s modulus and hardness than the intact bone. The regenerated long bone also exhibited impaired mechanical properties, which may have been caused by the difference in the nano-organization of its collagen fibers and mineral crystals (the main components of bone tissue), from that of the intact bone.

Effective Young’s Modulus of Syntactic Foams with Hollow Glass Microspheres

2010 ◽  
Vol 29-32 ◽  
pp. 607-612 ◽  
Author(s):  
Chang Jun He ◽  
Hui Jian Li ◽  
Wei Yu ◽  
Xi Liang ◽  
Hai Yan Peng
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Mechanical Analysis ◽  
Particulate Composites ◽  
Syntactic Foams ◽  
Glass Microspheres ◽  
Hollow Glass Microspheres ◽  
Hollow Glass ◽  
Young’S Moduli ◽  
Effective Young's Moduli

. The Young’s modulus of syntactic foams were studied both the experiment and the theory. The compressive test and dynamic mechanical analysis were progressed for a few of specimens, which were made of the syntactic foams with the epoxy resin and hollow glass microspheres (HGMs). the equations for Young’s modulus of concentrated particulate composites were derived using a differential scheme of an infinitely dilute system, and were employed to prediction the Young’s modulus of syntactic foams. The computed effective Young’s moduli were compared with the experimental results, the prediction values were between the lower and upper bounds of the experimental data, and the prediction model was acceptable and can estimate the Young’s modulus of syntactic foams.

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