Chemo-mechanical Properties Research Articles

Micro-chemomechanical properties of red mud binder and its effect on concrete

Red mud is a hazardous waste generated from alumina production, and its safe disposal is a worldwide issue. Although some previous studies have reused red mud in cement-based composites, there is still a lack of research on the nano-scale chemomechanical properties of red mud binders. In this paper, atomic force microscopy with innovative QI™ mode, quantitative backscattered electron image, and quantitative x-ray diffraction analysis are conducted to uncover that Young's modulus of the C-(A)-S-H phase was decreased due to high content of red mud. The high porosity of corresponding binders allowed C-(A)-S-H gel to grow relatively unimpededly, resulting in lower packing density and lower modulus. The incorporation of red mud promoted the formation of aluminium-bearing phases and increased both Al/Ca, Si/Ca, and Fe/Ca ratio of formed C-(A)-S-H gel, especially for calcined red mud. At a moderate replacement ratio, the unreacted red mud enhanced the skeleton of the binder matrix with a filler effect. However, in concrete block samples, the size of red mud was insufficient to transfer the stress over limestone particles to mitigate the weak zones of blocks, and the reactivity of red mud always played a critical factor. Besides, recycling red mud in concrete blocks with a dry mix method overcomes the issue of workability reduction.

Degradation of chemical and mechanical properties of cements with different formulations in CO2-containing HTHP downhole environment

The increasing energy demand has pushed oil and gas exploration and development limits to extremely challenging and harsher HTHP (High Temperature and High Pressure) environments. Maintaining wellbore integrity in these environments, particularly in HPHT reservoirs with corrosive gases, presents a significant challenge. Robust risk evaluation and mitigation strategies are required to address these reservoirs' safety, economic, and environmental uncertainties. This study investigates chemo-mechanical properties degradations of class G oil well cement blended with silica fume, liquid silica, and latex when exposed to high temperature (150 °C) and high partial pressure of CO2 saturated brine. The result shows that these admixtures surround the cement grains and fill the interstitial spaces between the cement particles to form a dense crystal system of C–S–H. Consequently, the cement's percentage of pore voids, permeability, and the content of alkali compounds reduce, resulting in increased resistance to CO2 corrosion. Liquid silica, a specially prepared silica suspension, is a more effective alternative to silica fume in protecting oil well cement against CO2 chemical degradation. Micro-indentation analysis shows a significant deterioration in the mechanical properties of the cement, including average elastic modulus and hardness, particularly in the outer zones in direct contact with corrosive fluids. This study highlights the significance of incorporating admixtures to mitigate the effects of CO2 corrosion in HPHT environments and provides a valuable technique for quantitatively evaluating the mechanical-chemical degradation of cement sheath.

Construction of Planar Gliding Restriction Buffer and Kinetic Self-Accelerator Stabilizing Single-Crystalline LiNi0.9Co0.05Mn0.05O2 Cathode.

The single-crystalline Ni-rich cathode has aroused much attention for extenuating the cycling and safety crises in comparison to the polycrystalline cathode. However, planar gliding and kinetic hindrance hinder its chemo-mechanical properties with cycling, which induce delamination cracking and damage the mechanical integrity in single crystals. Herein, a robust Li2.64(Sc0.9Ti0.1)2(PO4)3 (LSTP) ion/electron conductive network was constructed to decorate single-crystal LiNi0.9Co0.05Mn0.05O2 (SC90) particles. Via physicochemical characterizations and theoretical calculations, this LSTP coating that evenly grows on the SC90 particle with good lattice matching and strong bonding effectively restricts the anisotropic lattice collapse along the c-axis and the cation mixing activity of SC90, thus suppressing planar gliding and delamination cracking during repeated high-voltage lithiation/delithiation processes. Moreover, such a 3D LSTP network can also facilitate the lithium-ion transport and prevent the electrolyte's corrosion, lightening the kinetic hindrance and triggering the surface phase transformation. Combined with the Li metal anode, the LSTP-modified SC90 cell exhibits a desirable capacity retention of 90.5% at 5 C after 300 cycles and stabilizes the operation at 4.3/4.5 V. Our results provide surface modification engineering to mitigate planar gliding and kinetic hindrance of the single-crystalline ultra-high Ni-rich cathode, which inspires peers to design other layered cathode materials.

Structural changes in myosin affect chemo-mechanical properties of the myosin-actin interaction.

Mutations in the genes encoding striated muscle myosins lead to a variety of diseases including hypertrophic (HCM) and dilated (DCM) cardiomyopathies (MYH7) and distal arthrogryposis syndromes (MYH3 and MYH8). We have used a muscle myoblast cell line to express and purify recombinant human beta-cardiac myosin and human embryonic skeletal muscle myosins, comparing the WT versions of these proteins with an array of disease-causing variants. HCM-causing mutations in the beta-cardiac motor domain often destabilize a folded back, autoinhibited state of myosin, leading to an increase in the number of heads available within the sarcomere to interact with actin and produce force, which in turn results in the hypercontractility characteristic of HCM. Destabilization is seen for mutations that alter residues involved in the regions of myosin important for forming the intramolecular contacts in the folded back state. However, mutations affecting residues remote from these interfaces can also increase the number of available heads by destabilizing the pre-power stroke state of myosin that enables formation of the folded back state. HCM mutations that affect only myosin motor function without affecting the stability of the folded back state are less common. In contrast, we have studied a variety of DCM-causing mutations and found that most DCM-mutant myosins exhibit decreases in one or more aspects of motor function, including actin-activated ATPase activity and in vitro gliding velocity. Current efforts focus on correlating the effects of distal arthrogryposis syndrome-causing mutations on MYH3 biomechanical function and contrasting the effects of these mutations with paralogous mutations in MYH7.

Planar Gliding and Vacancy Condensation: The Role of Dislocations in the Chemomechanical Degradation of Layered Transition-Metal Oxides

Stacking faults driven by dislocations have been observed in layered transition-metal oxide cathodes both in cycled and uncycled materials. The reversibility of stacking-sequence changes directly impacts the material performance. Irreversible glide due to lattice invariance or local compositional changes can initiate a catastrophic sequence of degradation mechanisms. In this study we compare the chemomechanical properties of LiCoO2 and LiNiO2 by combining density functional theory and anisotropic linear elasticity theory. We calculate stacking fault energies as a function of Li content and quantify the extent to which excess Ni hinders stacking-sequence changes. We then characterize screw dislocations, which mediate stacking-sequence changes, and find a peculiarly compliant behavior of LiNiO2 due to the interaction of Jahn–Teller distortions with the dislocation strain field. Finally, we analyze the tendency of vacancies to segregate along dislocation lines. This study represents the first instance of explicit ab initio atomistic dislocation models in layered oxides and paves the way for the understanding and optimization of the chemomechanical behavior of cathode active materials during battery operation.

Perspectives of Machine Learning Development on Kerogen Molecular Model Reconstruction and Shale Oil/Gas Exploitation

The shale revolution has provided abundant shale oil/gas resources for the world, but the efficient, sustainable, and environmentally friendly exploitation of shale oil/gas is still challenging. Kerogen is the primary hydrocarbon source of shale oil/gas. The research on the kerogen chemo-mechanical properties significantly influences the development of shale oil/gas extraction technology. Rapid reconstruction of the kerogen molecular models is the most effective way to study the generation mechanism of shale oil/gas from the bottom-up molecular level. However, due to the combinatorial explosion problem, the reconstruction complexity of kerogen increases sharply because of the kerogen’s characteristics of complex origin, large molecular weight, and diverse functional groups. The traditional kerogen molecular reconstruction methods require professionals to comprehensively analyze various experimental information to approximate the actual kerogen molecular models through trial-and-error. So, the traditional methods are time and material-consuming and extremely inefficient. These shortcomings make researchers spend too much strength on the reconstruction of kerogen molecular models and cannot focus on the study of kerogen chemo-mechanical properties. For the past few years, state-of-the-art machine learning (ML) methods have been applied to intelligently reconstruct the kerogen molecular models through high-throughput and predict shale oil/gas production mechanisms. Although the current work is still in the infancy stage, ML methods are believed to be the most promising way to solve the drawbacks of traditional methods and reconstruct kerogen in reliable and large molecular weight. Hence, mechano-energetics is proposed to study the efficient development and utilization of energy based on mechanics and ML. This paper briefly reviews the development history of kerogen molecular model reconstruction methods and the research of ML in the fields of kerogen reconstruction and shale oil/gas exploitation. Some recommendations for further ML-based work are also suggested. We are convinced that the ML methods will accelerate the research of kerogen and promote the significant development of unconventional oil/gas exploitation technologies.

Resolving Charge Distribution for Compositionally Heterogeneous Layered Cathode Materials

Rechargeable batteries are built on the foundation of redox-active compounds. Thus, understanding charge compensation mechanisms represents one of the most critical research directions in developing battery materials. Due to the compositional versatility of Li-containing layered cathode, i.e., LiNi1-x-yMnxCoyO2 (NMC), one can tune the TMs (transition metals) composition to satisfy various demands. As the Ni/Mn/Co stoichiometry moves across the compositional space, the charge compensation mechanism also gradually evolves due to the changing of TM 3d orbital energy levels. Thus, tailoring TMs stoichiometry has become effective to fine-tune battery performance. In a previous study, we found that NMCs with a highly heterogeneous TM distribution still exhibited a globally layered structure.1Another study on dopant distribution also suggests that the heterogeneous dopant can positively impact battery performance.2 Our previous studies show that the charge heterogeneity can result in local stress hotspots and exacerbate the chemomechanical breakdown of NMC particles.3 When the compositional heterogeneity prevails in individual NMC particles, charge distribution likely exhibits a heterogeneous pattern due to distinct redox reactions in domains with different TM stoichiometries. Thus, we believe that understanding the interplay between compositional heterogeneity and its impact on charge distribution may provide insights into engineering compositional heterogeneity to achieve desired charge distribution. Herein, in this work, we designed the compositionally heterogeneous NMC cathode with the ensemble-average layered structure as the platform to investigate the charge distribution with single-particle spectroscopic imaging measurements.4 We establish the relationship between charge distribution and local compositional heterogeneity at the single-particle level. The local Mn and Ni concentrations in individual NMC particles are positively and negatively correlated with the electrochemically induced Ni oxidation, respectively, whereas the Co concentration does not impose a clear effect on the Ni oxidation. The resulting material delivers excellent reversible capacity, rate capability, and cycle life at high operating voltages. Engineering Ni/Mn/Co distribution in NMC particles may provide a path toward controlling the charge distribution and thus chemomechanical properties of polycrystalline battery particles. Lin, F.; Nordlund, D.; Markus, I. M.; Weng, T.-C.; Xin, H. L.; Doeff, M. M., Profiling the nanoscale gradient in stoichiometric layered cathode particles for lithium-ion batteries. Energy & Environmental Science 2014, 7 (9), 3077-3085. Mu, L.; Zhang, R.; Kan, W. H.; Zhang, Y.; Li, L.; Kuai, C.; Zydlewski, B.; Rahman, M. M.; Sun, C.-J.; Sainio, S.; Avdeev, M.; Nordlund, D.; Xin, H. L.; Lin, F., Dopant Distribution in Co-Free High-Energy Layered Cathode Materials. Chemistry of Materials 2019, 31 (23), 9769-9776. Yang, Y.; Xu, R.; Zhang, K.; Lee, S.-J.; Mu, L.; Liu, P.; Waters, C. K.; Spence, S.; Xu, Z.; Wei, C.; Kautz, D. J.; Yuan, Q.; Dong, Y.; Yu, Y.-S.; Xiao, X.; Lee, H.-K.; Pianetta, P.; Cloetens, P.; Lee, J.-S.; Zhao, K.; Lin, F.; Liu, Y., Quantification of Heterogeneous Degradation in Li-Ion Batteries. Advanced Energy Materials 2019, 9 (25), 1900674. Mu, L.; Zhang, J.; Xu, Y.; Wei, C.; Rahman, M. M.; Nordlund, D.; Liu, Y.; Lin, F., Resolving Charge Distribution for Compositionally Heterogeneous Battery Cathode Materials. Nano Letters 2022, 22 (3), 1278-1286.

(Battery Division Early Career Award Sponsored by Neware Technology Limited) Design, Synthesis, and Characterization of Cathode Microstructures in Lithium Batteries

The propagation of redox reactions governs the electrochemical properties of battery materials and their critical performance metrics in battery cells. The recent research progress, especially aided by advanced analytical techniques, has revealed that incomplete and heterogeneous redox reactions prevail in many electrode materials. Advanced high-capacity cathode materials are mostly polycrystalline materials that exhibit complex charge distribution (the valence state distribution of the redox-active cations) due to the presence of numerous constituting grains and grain boundaries. The redox reactions in individual grains typically do not proceed concurrently due to their distinct geometric locations in polycrystalline particles. As a result, these unsynchronized local redox events collectively induce heterogeneous and anisotropic charge distribution, building up intergranular and intragranular stress. Therefore, these polycrystalline materials may exhibit weak mechanical stability, leading to undesired chemomechanical breakdown during battery operation. Grain engineering in polycrystalline materials provides a large playground to modulate the materials properties beyond controlling the chemical composition, and electronic and crystal structures. In particular, the anisotropic ion-conducting pathways in layered oxides make the grain crystallographic orientation a critical factor in determining the modality of the redox reactions in these materials.This presentation will discuss our recent progress in the design, synthesis, and characterization of cathode microstructures in lithium batteries.First, we will discuss how the charge distribution is guided by grain crystallographic orientations in polycrystalline battery materials. We elucidate the spatially resolved charge distribution in lithium layered oxides with different grain crystallographic arrangements and establish a model to quantify their charge distributions. While the holistic “surface-to-bulk” charge distribution prevails in polycrystalline particles, the crystallographic orientation-guided redox reaction governs the charge distribution in the local charged nanodomains. Compared to the randomly oriented grains, the radially aligned grains exhibit a lower cell polarization and higher capacity retention upon battery cycling. The radially aligned grains create less tortuous lithium-ion pathways, thus improving the charge homogeneity as statistically quantified from over 20 million nanodomains in polycrystalline particles. This study provides an improved understanding of the charge distribution and chemomechanical properties of polycrystalline battery materials.Second, we will discuss how the grain arrangement affects the thermal stability of polycrystalline cathode materials in rechargeable batteries. We performed a systematic in situ study on the Ni-rich polycrystalline cathode materials to investigate the fundamental degradation mechanism of charged cathodes at elevated temperatures, which is essential for tailoring material properties and improving performance. Using multiple microscopy, scattering, thermal, and electrochemical probes, we decoupled the major contributors to the thermal instability from intertwined factors. Based on our findings, the cathode grain microstructure has a forgotten yet important role in the thermal stability of polycrystalline rechargeable batteries. Oxygen release, as an important process during the thermal runaway, can be regulated through engineering grain arrangements. The grain arrangement can modulate the macroscopic crystallographic transformation pattern and oxygen diffusion length in layered cathodes to offer more possibilities for cathode material design and synthesis.Third, we will discuss our new understanding of particle behaviors in composite cathodes. We capture and quantify the particle motion during the solidification of battery electrodes and reveal the statistics of the dynamically evolving motion in the drying process, which has been challenging to resolve. We discover that the particle motion exhibits a strong dependence on its geometric location within a drying electrode. Our results also imply that the final electrode quality can be controlled by balancing the solvent evaporation rate and the particle mobility in the region close to the drying surface. We formulate a network evolution model to interpret the regulation and equilibration between electrochemical activity and mechanical damage of these particles. Through statistical analysis of thousands of particles using x-ray phase-contrast holotomography in a Ni-rich cathode, we found that the local network heterogeneity results in asynchronous activities in the early cycles, and subsequently the particle assemblies move toward a synchronous behavior. Our study pinpoints the chemomechanical behavior of individual particles and enables better designs of the conductive network to optimize the utility of all the particles during operation.

A Thermodynamically Consistent, Phase-Field Electro-Chemo-Mechanical Theory with Account for Damage in Solids: Application to Metal Filament Growth in Solid-State Batteries

Solid-state batteries (SSBs) present a promising technology and have attracted significant research attention owing to their superior properties including increased energy density (3860 mAh), wider electrochemical window (0-5V) and safer electrolyte design. From a safety standpoint, SSBs are particularly appealing in that replacement of flammable conventional organic electrolytes with highly conductive, mechanically stiff inorganic solid-state electrolytes (SSEs) can alleviate failure due to short circuit or ignition. However, operation of SSBs is hampered by numerous chemo-mechanical challenges [1 - 4], the most critical one associated with metal filament growth across the SSE.Filament protrusions can initiate at perturbations of the interface or microstructural heterogeneities and subsequently grow through the SSE, causing the battery to short-circuit. It is critical to understand from both an experimental and modeling perspective the interplay of various mechanisms including morphology of the SSE microstructure, elastic-viscoplastic behavior of Li-metal, critical current density and stack pressure on the morphology of filamentary protrusions across the SSE. While much has been done to understand the interplay of aforementioned mechanisms from an experimental standpoint [5,6], theoretical frameworks on modeling of filaments growth in SSBs are still at their infancy and typically simplify dendrites as pressurized cracks under a linear-elastic fracture mechanics (LEFM) approach [7-8]. In this work, we propose a thermodynamically consistent phase-field reaction-diffusion-damage theory to investigate the morphology of filament growth across the SSE under varying chemo-mechanical operational conditions. The theory is fully coupled with electrodeposition at the Li metal-SSE interface impacting mechanical deformation, stress generation and subsequent fracture of the SSE. Conversely, electrodeposition kinetics are affected by mechanical stresses through a thermodynamically consistent, physically motivated driving force that distinguishes the role of various chemical, electrical and mechanical contributions. Concurrently, the theory captures the interplay between crack propagation and electrodeposition phenomena by tracking the damage and reaction field using separate phase-field variables such that metal growth is preceded by and confined to damaged regions within the SSE accessible by Li-metal. This is a critical feature of the theory and confirms experimental observations that the crack front propagates ahead of Li. We specialize the theory and study the role of variations of chemo-mechanical properties (i.e. applied electric potential, SSE fracture energy) on the morphology of metal filament growth and map operational conditions to distinguish between domains of i) stable vs. unstable growth ii) intergranular vs. transgranular growth mode. In doing so, the proposed framework provides a quantitative understanding on mechanisms dictating metal filament growth in SSEs and identifies mitigation strategies to employ in future SSB designs for successful operation.

Effect of a polymerization inhibitor on the chemomechanical properties and consistency of experimental resin composites.

This study investigated the effect of butylated hydroxytoluene (BHT) inhibitor on degree of conversion (DC), flexural strength (FS), flexural modulus (FM), Knoop microhardness (KH), microhardness reduction (HR), and consistency of experimental resin composites at different BHT concentrations: C0 (control-0%); C0.01 (0.01%); C0.025 (0.025%); C0.05 (0.05%); C0.1 (0.1%); and C0.5 (0.5%). For the consistency, the composites were tested immediately after being exposed to a dental chair headlight (0, 20, 40 and 60 s). Data concerning DC, FS, FM, KH, and HR were submitted to one-way ANOVA, while the consistency data was submitted to 2-way ANOVA; mean values were then compared (Tukey's test; α=0.05). The KH, FS and FM analyses showed no significant difference among the composites tested. For DC, C0 showed the highest mean value (74.2%) and differed only from C0.5 (67.2%). For HR, C0.5 showed the lowest mean (13.09%) value and differed from C0 (26.4%) and C0.01 (24.87). The consistency analysis showed no difference among C0.05, C0.1 and C0.5, considering 0 and 20 s of light exposure, while C0 (14.07 mm), C0.01 (13.97 mm), and C0.025 (14.18 mm) showed higher mean values at 0 s when compared to 20 s (12.67, 12.77 and 13.05 mm, respectivelly). Polymerization occurred within 40 s of light exposure for C0, C0.01, C0.025, and C0.05 and within 60 s for C0.1. In conclusion, the BHT concentrations had no significant influence on FS, FM and KH. The higher the BHT concentration, the longer was its handling time under light, with a significant improvement in the HR, but a decrease in DC. Therefore, BHT at 0.1% showed the best outcomes concerning all the BHT concentrations tested.

Crystallographic Design of Intercalation Materials

AbstractIntercalation materials are promising candidates for reversible energy storage and are, for example, used as lithium-battery electrodes, hydrogen-storage compounds, and electrochromic materials. An important issue preventing the more widespread use of these materials is that they undergo structural transformations (of up to ∼10% lattice strains) during intercalation, which expand the material, nucleate microcracks, and, ultimately, lead to material failure. Besides the structural transformation of lattices, the crystallographic texture of the intercalation material plays a key role in governing ion-transport properties, generating phase separation microstructures, and elastically interacting with crystal defects. In this review, I provide an overview of how the structural transformation of lattices, phase transformation microstructures, and crystallographic defects affect the chemo-mechanical properties of intercalation materials. In each section, I identify the key challenges and opportunities to crystallographically design intercalation compounds to improve their properties and lifespans. I predominantly cite examples from the literature of intercalation cathodes used in rechargeable batteries, however, the identified challenges and opportunities are transferable to a broader range of intercalation compounds.

Kinetic Origin of Planar Gliding in Single-Crystalline Ni-Rich Cathodes.

Single-crystalline Ni-rich cathodes with high capacity have drawn much attention for mitigating cycling and safety crisis of their polycrystalline analogues. However, planar gliding and intragranular cracking tend to occur in single crystals with cycling, which undermine cathode integrity and therefore cause capacity degradation. Herein, we intensively investigate the origin and evolution of the gliding phenomenon in single-crystalline Ni-rich cathodes. Discrete or continuous gliding forms are revealed with new surface exposure including the gliding plane (003) and reconstructed (-108) under surface energy drive. It is also demonstrated that the gliding process is the in-plane migration of transition metal ions, and reducing oxygen vacancies will increase the migration energy barrier by which gliding and microcracking can be restrained. The designed cathode with less oxygen deficiency exhibits outstanding cycling performance with an 80.8% capacity retention after 1000 cycles in pouch cells. Our findings provide an insight into the relationship between defect control and chemomechanical properties of single-crystalline Ni-rich cathodes.

Chemomechanical Properties of Electrospun Polyvinyl Acetate (PVAc) Fiber Mat and its Application in Water-Triggered Self-folding

Chemomechanical Properties of Electrospun Polyvinyl Acetate (PVAc) Fiber Mat and its Application in Water-Triggered Self-folding

Distinct actin–tropomyosin cofilament populations drive the functional diversification of cytoskeletal myosin motor complexes

SummaryThe effects of N-terminal acetylation of the high molecular weight tropomyosin isoforms Tpm1.6 and Tpm2.1 and the low molecular weight isoforms Tpm1.12, Tpm3.1, and Tpm4.2 on the actin affinity and the thermal stability of actin-tropomyosin cofilaments are described. Furthermore, we show how the exchange of cytoskeletal tropomyosin isoforms and their N-terminal acetylation affects the kinetic and chemomechanical properties of cytoskeletal actin-tropomyosin-myosin complexes. Our results reveal the extent to which the different actin-tropomyosin-myosin complexes differ in their kinetic and functional properties. The maximum sliding velocity of the actin filament as well as the optimal motor density for continuous unidirectional movement, parameters that were previously considered to be unique and invariant properties of each myosin isoform, are shown to be influenced by the exchange of the tropomyosin isoform and the N-terminal acetylation of tropomyosin.

Cardiac ventricular myosin and slow skeletal myosin exhibit dissimilar chemomechanical properties despite bearing the same myosin heavy chain isoform

The myosin II motors are ATP-powered force-generating machines driving cardiac and muscle contraction. Myosin II heavy chain isoform-beta (β-MyHC) is primarily expressed in the ventricular myocardium and in slow-twitch muscle fibers, such as M. soleus. M. soleus–derived myosin II (SolM-II) is often used as an alternative to the ventricular β-cardiac myosin (βM-II); however, the direct assessment of biochemical and mechanical features of the native myosins is limited. By employing optical trapping, we examined the mechanochemical properties of native myosins isolated from the rabbit heart ventricle and soleus muscles at the single-molecule level. We found purified motors from the two tissue sources, despite expressing the same MyHC isoform, displayed distinct motile and ATPase kinetic properties. We demonstrate βM-II was approximately threefold faster in the actin filament–gliding assay than SolM-II. The maximum actomyosin (AM) detachment rate derived in single-molecule assays was also approximately threefold higher in βM-II, while the power stroke size and stiffness of the “AM rigor” crossbridge for both myosins were comparable. Our analysis revealed a higher AM detachment rate for βM-II, corresponding to the enhanced ADP release rates from the crossbridge, likely responsible for the observed differences in the motility driven by these myosins. Finally, we observed a distinct myosin light chain 1 isoform (MLC1sa) that associates with SolM-II, which might contribute to the observed kinetics differences between βM-II and SolM-II. These results have important implications for the choice of tissue sources and justify prerequisites for the correct myosin heavy and light chains to study cardiomyopathies.

Chemical reactions of carbonate-rich mudstones with aqueous CO2 and their impacts on rock's local microstructural and chemo-mechanical properties

Assessment of the structural integrity of carbonate-rich rocks subjected to acidic brine strongly relies on the understanding of the coupling between the chemical changes and the alteration of the mechanical properties of rocks. This study aims at an integrated microscale chemo-mechanical and microstructural characterization of carbonate mudstones exposed to CO2-rich brine under high pressure and high temperature conditions. Digital image analysis was performed on X-ray micro-computed tomography (micro-CT) images to realize microstructural evolution and spatial distribution of pores and different material phases. This approach showed three distinct regions of porosity and carbonate content (resulting from dissolution and precipitation of calcium carbonates), which are critical for understanding the mechanical alteration of the rocks being investigated. Detailed analysis of the micro-CT images also revealed the preferred precipitation of calcium carbonates in pores parallel to the flow/reaction direction. Microscale chemo-mechanical testing performed using coupled grid nanoindentation and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) complemented the micro-CT results: dissolution zones close to the reacted surface were found to have lower hardness and indentation modulus while an increased values in adjacent precipitation zones was observed. Also, the thickness of the precipitation zones was found to be considerably higher in the direction of the bedding planes, which needs special attention in laminated rocks like shales and mudstones. The microstructural and mechanical properties of the microscale regions and the layered structure are expected to influence the overall mechanical properties and integrity of the rock. These results enhance our understanding of the microscale origin of the macroscopic mechanical alteration of carbonate-rich mudstones subjected to acidic brine.

Cryo‐Electron Tomography of Highly Deformable and Adherent Solid‐Electrolyte Interphase Exoskeleton in Li‐Metal Batteries with Ether‐Based Electrolyte (Adv. Mater. 13/2022)

Solid Electrolyte Interphase The solid electrolyte interphase (SEI) plays a critical role in determining the cycling stability of lithium-metal anodes. However, viewing the SEI in batteries remains extremely challenging due to its supersensitivity to the electron beam under a microscope. In article number 2108252, Ju Li, Meng Gu, and co-workers develop an ultralow-dosage cryo-TEM protocol to directly visualize the SEI in 3D at different charging states, revealing surprising and fundamentally significant results for the SEI. The optimized chemo-mechanical properties of the SEI contribute significantly to the superior performances of Li-metal batteries.

Highly Stretchable Hydrogels as Wearable and Implantable Sensors for Recording Physiological and Brain Neural Signals.

Recording electrophysiological information such as brain neural signals is of great importance in health monitoring and disease diagnosis. However, foreign body response and performance loss over time are major challenges stemming from the chemomechanical mismatch between sensors and tissues. Herein, microgels are utilized as large crosslinking centers in hydrogel networks to modulate the tradeoff between modulus and fatigue resistance/stretchability for producing hydrogels that closely match chemomechanical properties of neural tissues. The hydrogels exhibit notably different characteristics compared to nanoparticles reinforced hydrogels. The hydrogels exhibit relatively low modulus, good stretchability, and outstanding fatigue resistance. It is demonstrated that the hydrogels are well suited for fashioning into wearable and implantable sensors that can obtain physiological pressure signals, record the local field potentials in rat brains, and transmit signals through the injured peripheral nerves of rats. The hydrogels exhibit good chemomechanical match to tissues, negligible foreign body response, and minimal signal attenuation over an extended time, and as such is successfully demonstrated for use as long‐term implantable sensory devices. This work facilitates a deeper understanding of biohybrid interfaces, while also advancing the technical design concepts for implantable neural probes that efficiently obtain physiological information.

Exposure of crumb rubber modified bitumen to UV radiation: A waste-based sunscreen for roads

The degradation of asphalt roads due to heat and moisture is well studied, but very little focus has been given to the effects of high energy transmitted by sunlight UV radiations. This study aims to investigate the effect of UV radiations on the chemo-mechanical properties of neat and modified bitumen with different concentrations of crumb rubber and compare it to that of thermal ageing. Samples were aged in the Q-Lab weatherometer for 869 h at 0.89 Wm-2, equivalent to one year of UV radiations energy in the city of Melbourne, Australia, in 2019. Fourier transformation infrared (FTIR) spectroscopy was used for analysing the changes of chemical bonds before and after ageing. It was found that thermal ageing results in the development of carbonyl and sulfoxide oxides while evaporates the volatile components as depicted from the decreasing value of aliphaticity index. On the other hand, UV ageing mainly targets components with bond energy lower than 413 kJ/mol, i.e., C–C, C–O and C–H that usually consist of aliphatic chains of hydrocarbons. The rheological test results revealed that both thermal and UV ageing produce stiffer materials as depicted from the upward shift of the master curves. However, this shift reduces with the increase in CR concentration. All unaged samples were found to lay well below the Glover-Rowe onset damage envelope, however, as the samples underwent thermal ageing, they moved towards the onset damage zone. With the addition of UV ageing, the standard bitumen was only 13.2 kPa away from the ‘onset damage’ threshold while crumb rubber modified bitumen was almost 60 kPa away from the damage zone. Moreover, if neat bitumen is to be modified with 22.5% of CR, it can reduce the damage produced by UV and thermal ageing by approximately 50%, hence showing greater resistance to the thermal and solar radiation degradation.

How Water Content Can Influence the Chemomechanical Properties and Physical Degradation under Aging of Experimental Adhesives.

Objective To evaluate the physicochemical (sorption (SOR), solubility (SOL), and degree of conversion (DC)) and mechanical (flexural strength (FS), modulus of elasticity (ME), and compressive strength (CS)) properties of adhesives with different water contents (D2O). Materials and Methods An adhesive was formulated: 55 wt% BisGMA, 45 wt% HEMA, 0.5 wt% camphorquinone, 0.5 wt% EDMAB, and 1.0 wt% DPIHP. D2O was added into the adhesives (0 wt%, 10 wt%, and 16 wt%). DC was monitored through the FTIR. FS, ME, CS, SOR, and SOL were tested. The adhesive samples were aged in deionized water, ethanol, and acetone. Data were submitted to ANOVA and Tukey's tests (5%). Results For DC, the 0 wt% group showed a significant reduction (68.09 ± 0.14A) compared with the 10 wt% (87.07 ± 0.81B) and 16 wt% groups (89.87 ± 0.24B); 10 wt% showed the highest FS (MPa) mean values (141.6 ± 6.71B) compared with the 0 wt% (109.4 ± 20.5A) and 16 wt% (107.8 ± 15.8A). For the CS (MPa) and ME (GPa), the 16 wt% showed the lowest mean values (98.8 ± 18.0B and 2.2 ± 0.3B, respectively) compared with the 10 wt% and 0 wt%. For the SOR, 16 wt% of water showed the highest mean values and the ethanol showed the lowest mean values of SOL regardless of water content. Conclusion The amount of water content and the types of aging solvents significantly affect the adhesive properties.