Supercritical carbon dioxide (ScCO2) fracturing technology has been increasingly emphasized in the development of unconventional oil and gas resources due to its advantages of anhydrous fabrication ...of complex seam networks and geological sequestration of CO2. However, previous studies have mostly focused on the geometry, number, and type of inorganic mineral fractures, and rarely paid attention to the changes in the seepage structure within organic matter (OM). To characterize the nanoscale microstructural changes of OM induced by H2O-ScCO2, this study obtained the variation rule of mechanical properties of OM with adsorbed water saturation based on nanoindentation test, and the continuous change of elastic modulus and morphology of the OM in the same region after dry, water-wet, and water-ScCO2 treatments was compared by atomic force microscopy (AFM). Elastic modulus and hardness of OM were calculated by Oliver-Pharr and Hertz methods, and the average roughness, root mean square roughness, and kurtosis were obtained based on 3D morphology. The results showed that elastic modulus and hardness were negatively and nonlinearly correlated with water saturation. Although the AFM-measured elastic modulus of OM microphases of the dry, water-wet, and water-ScCO2-treated shale were all highly discrete and non-homogeneous, they were generally normally distributed, and the mean values of the elastic modulus decreased sequentially. It is determined that water-ScCO2 coupling make OM matrix undergo superimposed dissolution. It is shown that ScCO2 and water synergistically change the microstructure of shale OM, and the weakening of mechanical properties and the increase of surface roughness are very favorable for geological sequestration and long-term storage of CO2.
•Young's modulus and hardness of organic matter showed a nonlinear negative correlation with water content.•Young's modulus and morphological changes of organic matter were analyzed at the nanoscale by in-situ AFM.•Water swelling decreased the roughness and Young's modulus of the organic matter.•The coupling of water and ScCO2 complicated the morphology and decreased Young's modulus of the organic matter.
Hf6Ta2O17 ceramics are successfully prepared by solid state reaction and pressureless sintering. The mechanical properties and the calcium-magnesium-alumino-silicate (CMAS) corrosion behavior of ...Hf6Ta2O17 ceramics are studied. The hardness, elastic modulus and fracture toughness of Hf6Ta2O17 ceramics are 18.45 GPa, 273.42 GPa and 2.6–3.1 MPa m1/2, respectively. As the Hf6Ta2O17 ceramics are attacked by CMAS, the reaction layer and dense layer are formed on the ceramic surface, which prevents the further infiltration of molten CMAS. HfSiO4 and Ca2Hf7O16 are confirmed as the main reaction products of Hf6Ta2O17 and CMAS. Hf6Ta2O17 ceramics exhibit better CMAS corrosion resistance than 8 wt% yttria stabilized zirconia (8YSZ) ceramics, which is attributed to the dense structure formed by corrosion products (hafnium tantalum oxide and Ca2Hf7O16) and lower theoretical optical basicity (OB) value. Furthermore, Hf6Ta2O17/YSZ double ceramic top coat thermal barrier coatings (TBCs) are successfully prepared by plasma spraying, and the thermal cycling performance is investigated. Hf6Ta2O17/YSZ double-layers TBCs has good thermal cycling performance as 8YSZ single-layer TBCs.
The advancement of magnesium alloys has historically faced challenges due to their inherently low modulus and the inverse relationship between modulus and ductility. In this study, an ...Mg-15Gd-8Y–11Al-0.3Mn alloy containing Al2RE phases was developed through an in-situ synthesis process, exhibiting exceptional mechanical properties, including a high elastic modulus of 57.6 GPa coupled with a satisfactory elongation of 7.3 %. The findings indicate the presence of polygonal Al2RE phases of varying sizes within the alloy, with α-Mg observed in some Al2RE phases, forming a coherent interface. The grain size of the alloy was refined, and the dimensions of the Al2RE particles were reduced through the extrusion process. The effective strain transfer between α-Mg and Al2RE, facilitated by the coherent interface, endowed the alloy with commendable ductility, even at a substantial Al2RE volume fraction of 23 %. Furthermore, the formation of the Al2RE phase was identified as the key contributor to the alloy's enhanced modulus. This study provides novel insights for the engineering of high-modulus magnesium alloys, thereby paving the way into their broader industrial application.
•Magnesium alloys with high modulus and good mechanical properties were prepared using the in-situ autogenic method.•The increase in the alloy's Young's modulus is attributed to the formation of Al2RE particles.•The strengthening mechanism and fracture characteristics of the high-modulus magnesium alloy produced by in-situ autogenesis were revealed.
The used and broken windshield panels of the Alto 800 (A8), Hyundai i20 (H2), and Maruti Suzuki Eeco (ME) have been taken to study their structural, optical, and mechanical characteristics. Fourier ...transform infrared and Raman spectroscopy investigation revealed the increment of Q3 and Q4 units instead of Q1 and Q2 units when K2O and MgO content increases in the windshield glasses. The transparency is highest for A8 glass due to the higher content of Q1 and Q2, making the glass network more open. This windshield glass panel is less rigid with lower hardness than other windshield glasses. The highest optical band gap is found at nearly 3.66 eV for the ME sample. However, the A8 windshield glass is thermally more stable and it can bear more temperature variation and harsh environmental conditions. The present study would help to design better windshield glasses.
Cardiomyocytes sense and shape their mechanical environment, contributing to its dynamics by their passive and active mechanical properties. While axial forces generated by contracting cardiomyocytes ...have been amply investigated, the corresponding radial mechanics remain poorly characterized. Our aim is to simultaneously monitor passive and active forces, both axially and radially, in cardiomyocytes freshly isolated from adult mouse ventricles. To do so, we combine a carbon fibre (CF) set-up with a custom-made atomic force microscope (AFM). CF allows us to apply stretch and to record passive and active forces in the axial direction. The AFM, modified for frontal access to fit in CF, is used to characterize radial cell mechanics. We show that stretch increases the radial elastic modulus of cardiomyocytes. We further find that during contraction, cardiomyocytes generate radial forces that are reduced, but not abolished, when cells are forced to contract near isometrically. Radial forces may contribute to ventricular wall thickening during contraction, together with the dynamic re-orientation of cells and sheetlets in the myocardium. This new approach for characterizing cell mechanics allows one to obtain a more detailed picture of the balance of axial and radial mechanics in cardiomyocytes at rest, during stretch, and during contraction.
This article is part of the theme issue ‘The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease’.
Various corneal diseases are strongly associated with corneal biomechanical characteristics, and early measurement of patients' corneal biomechanics can be utilized in their diagnosis and treatment. ...Measurement methods for corneal biomechanical characteristics are classified into ex vivo and in vivo. Some of these methods can directly measure certain corneal biomechanical parameters, while others require indirect calculation through alternative methods. However, due to diversities in measurement techniques and environmental conditions, significant differences may exist in the corneal mechanical properties measured by these two methods. Therefore, comprehensive research on current measurement methods and the exploration of novel measurement techniques may have great clinical significance. The corneal elastic modulus, a critical indicator in corneal biomechanics, reflects the cornea's ability to return to its initial shape after undergoing stress. This review aims to provide a comprehensive summary of the corneal elastic modulus, which is a critical biomechanical parameter, and discuss its direct, indirect, and potential measurement methods and clinical applications.
•This paper reviews the ex vivo and in vivo measurement methods and clinical applications of corneal elastic modulus.
Collagen forms fibrous networks that reinforce tissues and provide an extracellular matrix for cells. These networks exhibit remarkable strain-stiffening properties that tailor the mechanical ...functions of tissues and regulate cell behavior. Recent models explain this nonlinear behavior as an intrinsic feature of disordered networks of stiff fibers. Here, we experimentally validate this theoretical framework by measuring the elastic properties of collagen networks over a wide range of self-assembly conditions. We show that the model allows us to quantitatively relate both the linear and nonlinear elastic behavior of collagen networks to their underlying architecture. Specifically, we identify the local coordination number (or connectivity) 〈z〉 as a key architectural parameter that governs the elastic response of collagen. The network elastic response reveals that 〈z〉 decreases from 3.5 to 3 as the polymerization temperature is raised from 26 to 37°C while being weakly dependent on concentration. We furthermore infer a Young’s modulus of 1.1 MPa for the collagen fibrils from the linear modulus. Scanning electron microscopy confirms that 〈z〉 is between three and four but is unable to detect the subtle changes in 〈z〉 with polymerization conditions that rheology is sensitive to. Finally, we show that, consistent with the model, the initial stress-stiffening response of collagen networks is controlled by the negative normal stress that builds up under shear. Our work provides a predictive framework to facilitate future studies of the regulatory effect of extracellular matrix molecules on collagen mechanics. Moreover, our findings can aid mechanobiological studies of wound healing, fibrosis, and cancer metastasis, which require collagen matrices with tunable mechanical properties.
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•TPMS parameter influences on elastic modulus and anisotropy were analyzed.•Isotropic TPMS were designed by the proposed Curvature-Wall thickness adjustment method.•Composite TPMS was ...proposed for units with performances far from the target to generate isotropic TPMS.
Recently, triply periodic minimal surface (TPMS) is emerging as an ideal tool to generate porous structures. Yet, most of the current work only focuses on controlling the elastic modulus by the relative density. For special engineering applications, such as porous bone implants or energy absorbers, the generated porous TPMS may still be broken due to anisotropy. In this work, two strategies are proposed to design isotropic TPMS structures. The numerical homogenization theory and finite element analysis methods are utilized to study the relationship between TPMS parameters and the elastic modulus or anisotropy properties. Based on that, a Curvature-Wall thickness (CW) adjustment method is proposed for sheet TPMS structures whose performances are close to isotropy properties. In virtue of the constructed design map, both elastic modulus and anisotropy properties can be controlled. For sheet TPMS structures whose performances are far from the isotropy properties, the TPMS units can be combined to generate composite TPMS, which can be further designed by the proposed Curvature-Wall thickness adjustment method. Experimental results verify the effectiveness and accuracy of the proposed approaches. Appropriate elastic modulus and ideal isotropy properties can be acquired at the same time.
A proper immune response is key for the successful implantation of biomaterials, and designing and fabricating biomaterials to regulate immune responses is the future trend. In this work, three ...different nanostructures were constructed on the surface of titanium using a hydrothermal method, and through a series of in vitro and in vivo experiments, we found that the aspect ratio of nanostructures can affect the elastic modulus of a material surface and further regulate immune cell behaviors. This work demonstrates that nanostructures with a higher aspect ratio can endow a material surface with a lower elastic modulus, which was confirmed by experiments and theoretical analyses. The deflection of nanostructures under the cell adsorption force is a substantial factor in stretching macrophages to enhance cell adhesion and spreading, further inducing macrophage polarization toward the M1 phenotype and leading to intense immune responses. In contrast, a nanostructure with a lower aspect ratio on a material surface leads to a higher surface elastic modulus, making deflection of the material difficult and creating a surface that is not conducive to macrophage adhesion and spreading, thus reducing the immune response. Moreover, molecular biology experiments indicated that regulation of the immune response by the elastic modulus is primarily related to the NF-κB signaling pathway. These findings suggest that the immune response can be regulated by constructing nanostructural surfaces with the proper elastic modulus through their influence on cell adhesion and spreading, which provides new insights into the surface design of biomaterials.
In this study, experimental investigations were carried out to estimate the mechanical and microstructural properties of polypropylene (PP) and steel fiber reinforced geopolymer mortar. Two ...industrial by-products are used as binders to produce the geopolymer composites, i.e., fly ash (FA) and ground granulated blast furnace slag (GGBFS). Different percentages of PP and steel fibers are used in geopolymer mortars to find the mechanical properties such as compressive, splitting tensile and flexural strengths were investigated to understand the strength behavior. However, the compressive elastic modulus values were estimated through the proposed equation based on the compressive strength of the fiber reinforced geopolymer composite samples. Moreover, to understand the geopolymeic reaction, microstructural studies, i.e., scanning electron microscopy (SEM), were conducted. The experimental results revealed that the addition of PP fibers up to 2.0% (volume fraction) enhanced the flexural properties of geopolymer mortar samples. The compressive strength of the steel fiber-reinforced geopolymer composite reached a maximum of 2.5% volume fraction, being a 13.26% improvement over the control mix. The flexural toughness index of the PP and steel fiber reinforced composites improved with increasing the fraction. However, steel fiber reinforced geopolymer samples are shown better flexural toughness compared to PP fibers. The SEM analysis of the geopolymer control mix achieved a good degree of geopolymerization and both the fibers yielded a considerable interfacial bonding with the geopolymer paste.
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