mechanical strain
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2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Jaeyeon Wee ◽  
Hyang Kim ◽  
Sang-Jin Shin ◽  
Taeyong Lee ◽  
Seung Yeol Lee

Abstract Background Organogenesis from tonsil-derived mesenchymal cells (TMSCs) has been reported, wherein tenogenic markers are expressed depending on the chemical stimulation during tenogenesis. However, there are insufficient studies on the mechanical strain stimulation for tenogenic cell differentiation of TMSCs, although these cells possess advantages as a cell source for generating tendinous tissue. The purpose of this study was to investigate the effects of mechanical strain and transforming growth factor-beta 3 (TGF-β3) on the tenogenic differentiation of TMSCs and evaluate the expression of tendon-related genes and extracellular matrix (ECM) components, such as collagen. Results mRNA expression of tenogenic genes was significantly higher when the mechanical strain was applied than under static conditions. Moreover, mRNA expression of tenogenic genes was significantly higher with TGF-β3 treatment than without. mRNA expression of osteogenic and chondrogenic genes was not significantly different among different mechanical strain intensities. In cells without TGF-β3 treatment, double-stranded DNA concentration decreased, while the amount of normalized collagen increased as the intensity of mechanical strain increased. Conclusions Mechanical strain and TGF-β3 have significant effects on TMSC differentiation into tenocytes. Mechanical strain stimulates the differentiation of TMSCs, particularly into tenocytes, and cell differentiation, rather than proliferation. However, a combination of these two did not have a synergistic effect on differentiation. In other words, mechanical loading did not stimulate the differentiation of TMSCs with TGF-β3 supplementation. The effect of mechanical loading with TGF-β3 treatment on TMSC differentiation can be manipulated according to the differentiation stage of TMSCs. Moreover, TMSCs have the potential to be used for cell banking, and compared to other mesenchymal stem cells, they can be procured from patients via less invasive procedures.


Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 119
Author(s):  
Farid Sayar Irani ◽  
Ali Hosseinpour Shafaghi ◽  
Melih Can Tasdelen ◽  
Tugce Delipinar ◽  
Ceyda Elcin Kaya ◽  
...  

High accuracy measurement of mechanical strain is critical and broadly practiced in several application areas including structural health monitoring, industrial process control, manufacturing, avionics and the automotive industry, to name a few. Strain sensors, otherwise known as strain gauges, are fueled by various nanomaterials, among which graphene has attracted great interest in recent years, due to its unique electro-mechanical characteristics. Graphene shows not only exceptional physical properties but also has remarkable mechanical properties, such as piezoresistivity, which makes it a perfect candidate for strain sensing applications. In the present review, we provide an in-depth overview of the latest studies focusing on graphene and its strain sensing mechanism along with various applications. We start by providing a description of the fundamental properties, synthesis techniques and characterization methods of graphene, and then build forward to the discussion of numerous types of graphene-based strain sensors with side-by-side tabular comparison in terms of figures-of-merit, including strain range and sensitivity, otherwise referred to as the gauge factor. We demonstrate the material synthesis, device fabrication and integration challenges for researchers to achieve both wide strain range and high sensitivity in graphene-based strain sensors. Last of all, several applications of graphene-based strain sensors for different purposes are described. All in all, the evolutionary process of graphene-based strain sensors in recent years, as well as the upcoming challenges and future directions for emerging studies are highlighted.


2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Mei Wu ◽  
Xiaowei Zhang ◽  
Xiaomei Li ◽  
Ke Qu ◽  
Yuanwei Sun ◽  
...  

AbstractFlexoelectricity is a type of ubiquitous and prominent electromechanical coupling, pertaining to the electrical polarization response to mechanical strain gradients that is not restricted by the symmetry of materials. However, large elastic deformation is usually difficult to achieve in most solids, and the strain gradient at minuscule is challenging to control. Here, we exploit the exotic structural inhomogeneity of grain boundary to achieve a huge strain gradient (~1.2 nm−1) within 3–4-unit cells, and thus obtain atomic-scale flexoelectric polarization of up to ~38 μC cm−2 at a 24° LaAlO3 grain boundary. Accompanied by the generation of the nanoscale flexoelectricity, the electronic structures of grain boundaries also become different. Hence, the flexoelectric effect at grain boundaries is essential to understand the electrical activities of oxide ceramics. We further demonstrate that for different materials, altering the misorientation angles of grain boundaries enables tunable strain gradients at the atomic scale. The engineering of grain boundaries thus provides a general and feasible pathway to achieve tunable flexoelectricity.


2022 ◽  
Author(s):  
Serafino Caruso ◽  
Luigino Filice

Abstract The evolution of grain size and component mechanical behaviour are fundamental aspects to analyse and control when manufacturing processes are considered. In this context, severe plastic deformation (SPD) processes, in which a high shear strain is imposed on the material, are recognized as the main techniques to achieve microstructural changes and material strengthening by the recrystallization, attracting both academic and industrial investigation activities. At the same time, nowadays, sustainable manufacturing design is one of the main responsibilities of the researchers looking at UN2030 agenda and the modern industrial paradigms. In this paper a new severe SPD process is proposed with the aim to steer manufacturing to fourth industrial revolution using some of Industry 4.0 pillars. In particular, additive manufacturing (AM) and numerical simulations were setup as controlling and monitoring techniques in manufacturing process of wires.Strengthening effect (yield and ultimate tensile strength, plasticity and hardness) and microstructural evolution (continuous dynamic recrystallization -CDRX-) due to severe plastic deformation were experimentally analysed and numerically investigated by an innovative finite element (FE) model able to validate the effectiveness of a properly modified process for ultra-fine aluminium alloy AA6101 wires production designed with the aim to avoid any post manufacturing costly thermal treatment.The study provides an accurate experimental study and numerical prediction of the thermo-mechanical and microstructural phenomena that occur during an advanced large plastic deformation process; it shows how the combination of smart manufacturing and simulations control represents the key to renew the traditional manufacturing methods in the perspective of the Industry 4.0, connecting and integrating the manufacturing process for the industrial evolution in production.


Author(s):  
Imrich Gablech ◽  
Jan Brodský ◽  
Petr Vyroubal ◽  
Jakub Piastek ◽  
Miroslav Bartošík ◽  
...  

Cells ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 185
Author(s):  
Tillie-Louise Hackett ◽  
Noamie R. T. F. Vriesde ◽  
May AL-Fouadi ◽  
Leila Mostaco-Guidolin ◽  
Delaram Maftoun ◽  
...  

The extracellular matrix (ECM) supports lung tissue architecture and physiology by providing mechanical stability and elastic recoil. Over the last several decades, it has become increasingly clear that the stiffness of the ECM governs many cellular processes, including cell-phenotype and functions during development, healing, and disease. Of all the lung ECM proteins, collagen-I is the most abundant and provides tensile strength. In many fibrotic lung diseases, the expression of collagen is increased which affects the stiffness of the surrounding environment. The goal of this study was to assess the effect on fibroblast morphology, cell death, and inflammation when exposed to 2D and 3D low (0.4 mg/mL) versus high (2.0 mg/mL) collagen-I-matrix environments that model the mechanics of the breathing lung. This study demonstrates that human fetal lung fibroblasts (HFL1), grown in a 3D collagen type-I environment compared to a 2D one, do not form cells with a myofibroblast morphology, express less F-actin stress fibers, exhibit less cell death, and significantly produce less pro-inflammatory IL-6 and IL-8 cytokines. Exposure to mechanical strain to mimic breathing (0.2 Hz) led to the loss of HFL1 fibroblast dendritic extensions as well as F-actin stress fibers within the cell cytoskeleton, but did not influence cytokine production or cell death. This dynamic assay gives researchers the ability to consider the assessment of the mechanodynamic nature of the lung ECM environment in disease-relevant models and the potential of mechano-pharmacology to identify therapeutic targets for treatment.


SICOT-J ◽  
2022 ◽  
Vol 8 ◽  
pp. 1
Author(s):  
Katherine Wang ◽  
Eustathios Kenanidis ◽  
Zakareya Gamie ◽  
Khurram Suleman ◽  
Mark Miodownik ◽  
...  

Introduction: Our understanding of the impact of the stem fixation method in total hip arthroplasty (THA) on the subsequent management of periprosthetic femoral fractures (PFF) is still limited. This study aimed to investigate and quantify the effect of the stem fixation method, i.e., cemented vs. uncemented THA, on the management of Vancouver Type B1 periprosthetic femoral fractures with the same plate. Methods: Eight laboratory models of synthetic femora were divided into two groups and implanted with either a cemented or uncemented hip prosthesis. The overall stiffness and strain distribution were measured under an anatomical one-legged stance. All eight specimens underwent an osteotomy to simulate Vancouver type B1 PFF’s. Fractures were then fixed using the same extramedullary plate and screws. The same measurements and fracture movement were taken under the same loading conditions. Results: Highlighted that the uncemented THA and PFF fixation constructs had a lower overall stiffness. Subsequently, the mechanical strain on the fracture plate for the uncemented construct was higher compared to the cemented constructs. Conclusion: PFF fixation of a Vancouver type B1 fracture using a plate may have a higher risk of failure in uncemented THAs.


Author(s):  
Basem Ishak ◽  
Clifford A. Pierre ◽  
Darius Ansari ◽  
Stefan Lachkar ◽  
Alexander von Glinski ◽  
...  

AbstractL5 nerve palsy is a well-known complication following reduction of high-grade spondylolisthesis. While several mechanisms for its occurrence have been proposed, the hypothesis of L5 nerve root strain or displacement secondary to mechanical reduction remains poorly studied. The aim of this cadaveric study is to determine changes in morphologic parameters of the L5 nerve root during simulated intraoperative reduction of high-grade spondylolisthesis. A standard posterior approach to the lumbosacral junction was performed in eight fresh-frozen cadavers with lumbosacral or lumbopelvic screw fixation. Wide decompressions of the spinal canal and L5 nerve roots with complete facetectomies were accomplished with full exposure of the L5 nerve roots. A 100% translational slip was provoked by release of the iliolumbar ligaments and cutting the disc with the attached anterior longitudinal ligament. To evaluate the path of the L5 nerves during reduction maneuvers, metal bars were inserted bilaterally at the inferomedial aspects of the L5 pedicle at a distance of 10 mm from the midpoint of the L5 pedicle screws. There was no measurable change in length of the L5 nerve roots after 50% and 100% reduction of spondylolisthesis. Mechanical strain or displacement during reduction is an unlikely cause of L5 nerve root injury. Further anatomical or physiological studies are necessary to explore alternative mechanisms of L5 nerve palsy in the setting of high-grade spondylolisthesis correction, and surgeons should favor extensive surgical decompression of the L5 nerve roots when feasible.


Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 222
Author(s):  
Torkan Shafighfard ◽  
Magdalena Mieloszyk

This study investigates the thermo-mechanical behaviour of additively manufactured Carbon Fiber Reinforced Polymer (CFRP) with embedded Fibre Bragg Grating (FBG) sensors with respect to their feasibility for utilising them under thermal loading. This was conducted through the Finite Element Method (FEM) inside an ABAQUS environment. Numerical simulation was complemented by several experimental investigations in order to verify the computational results achieved for the specimens exposed to thermal loading. FBG sensors, incorporated into the material by embedding technique, were employed to measure the strains of the samples subjected to elevated temperatures. It was shown that the strains given by numerical simulation were in good agreement with the experimental investigation except for a few errors due to the defects created within the layers during Additive Manufacturing (AM) process. It was concluded that the embedding FBG sensors were capable of identifying thermo-mechanical strain accurately for 3D-printed composite structures. Therefore, the findings of this article could be further developed for other types of material and loading conditions.


Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 7
Author(s):  
Penghua Zhu ◽  
Jie Zhu ◽  
Xiaofei Xue ◽  
Yongtao Song

Recently, the stretchable piezoresistive composites have become a focus in the fields of the biomechanical sensing and human posture recognition because they can be directly and conformally attached to bodies and clothes. Here, we present a stretchable piezoresistive thread sensor (SPTS) based on Ag plated glass microspheres (Ag@GMs)/solid rubber (SR) composite, which was prepared using new shear dispersion and extrusion vulcanization technology. The SPTS has the high gauge factors (7.8~11.1) over a large stretching range (0–50%) and approximate linear curves about the relative change of resistance versus the applied strain. Meanwhile, the SPTS demonstrates that the hysteresis is as low as 2.6% and has great stability during 1000 stretching/releasing cycles at 50% strain. Considering the excellent mechanical strain-driven characteristic, the SPTS was carried out to monitor posture recognitions and facial movements. Moreover, the novel SPTS can be successfully integrated with software and hardware information modules to realize an intelligent gesture recognition system, which can promptly and accurately reflect the produced electrical signals about digital gestures, and successfully be translated into text and voice. This work demonstrates great progress in stretchable piezoresistive sensors and provides a new strategy for achieving a real-time and effective-communication intelligent gesture recognition system.


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