Reverse Stress Research Articles

Hydroalcoholic Extract of Centella asiatica and Madecassic Acid Reverse Depressive-Like Behaviors, Inflammation and Oxidative Stress in Adult Rats Submitted to Stress in Early Life.

Major depressive disorder (MDD) is a severe disorder that causes enormous loss of quality of life, and among the factors underlying MDD is stress in maternal deprivation (MD). In addition, classic pharmacotherapy has presented severe adverse effects. Centella asiatica (C. asiatica) demonstrates a potential neuroprotective effect but has not yet been evaluated in MD models. This study aimed to evaluate the effect of C. asiatica extract and the active compound madecassic acid on possible depressive-like behavior, inflammation, and oxidative stress in the hippocampus and serum of young rats submitted to MD in the first days of life. Rats (after the first day of birth) were separated from the mother for 3h a day for 10days. When adults, these animals were divided into groups and submitted to treatment for 14days. After subjecting the animals to protocols of locomotor activity in the open field and behavioral despair in the forced swimming test, researchers then euthanized the animals. The hippocampus and serum were collected and analyzed for the inflammatory cytokines and oxidative markers. The C. asiatica extract and active compound reversed or reduced depressive-like behaviors, inflammation in the hippocampus, and oxidative stress in serum and hippocampus. These results suggest that C. asiatica and madecassic acid have potential antidepressant action, at least partially, through anti-inflammatory and antioxidant profiles.

Residual stress in air-plasma-sprayed thermal barrier coatings under long-term high-temperature oxidation

The accumulated residual stress in yttria-stabilized zirconia top coat (YSZ TC) and thermally grown oxide (TGO) is regarded as the key driving force for the delamination of air-plasma-sprayed thermal barrier coating system (APS-TBCs). In this study, the synchronous evolution of residual stress of both YSZ TC and TGO, as well as the TGO thickness, are characterized via the Raman spectroscopy (RS) and photoluminescence piezo-spectroscopy (PLPS) methods. For the APS-TBCs where one surface is coated with YSZ TC, while the other surface remains directly exposed to high temperature, the service life can be categorized into four distinct stages: the early stage with tensile stress state (0–40 h), the medium stage with reversal compressive stress state (40–100 h), the late stage with re-inverted tensile stress (100–140 h), and the final stage with compressive stress state (140–300 h). Such stress reversal phenomenon may be attributed to the competition between the growth of TGO and substrate oxide (SO). It is advisable to apply an oxidation-resistant coating on the inner wall of high-temperature blade cooling passages, to prevent the formation of SO and consequently avoid complex stress transitions during high-temperature service of the APS-TBC, ultimately preventing local stress concentration-induced cracking and delamination.

Finite element analyses of failure of fiber reinforced polymer-concrete interface considering the concrete tension–compression softening effect

The concrete near the shear failure surface of the FRP (fiber reinforced polymer)-concrete interface is subjected to both tensile and compressive biaxial stress. However, existing finite element methods of the interfacial failure behavior of FRP-concrete interface to describe the tension–compression softening effect of concrete failure are not sufficiently accurate, and some detailed results may not be reflected. To address these issues, a finite element analysis method is proposed that accurately considers the tension–compression softening effect on concrete failure. The effectiveness of the method is demonstrated through analysis of literature data from experiments on plain concrete failure, FRP-concrete interface shear, and three-point bending. The method accurately reflects the generation of interfacial discontinuous micro-cracks, the oscillation singularity of stress field near the interfacial crack tip, the phenomenon of interface mismatch, the dispersion observed in the bond-slip curves, and the phenomenon of interfacial shear stress reversal. Moreover, this finite element analysis method is applied to the double shear experiments of the fully-bonded FRP-concrete interface under different boundary conditions, and the reasons for the different failure modes observed in the specimens are explained. The results indicate that considering the biaxial effect on concrete failure strength in numerical analysis can more accurately and comprehensively describe the shear failure behavior of the FRP-concrete interface.

Reversal of restraint stress caused dendritic atropy in rats by Nardostachys jatamansi

Reversal of restraint stress caused dendritic atropy in rats by Nardostachys jatamansi

Second-order deformation behaviors of free-rotational tension after free-end torsion for rolled AZ31B magnesium alloy

The accompanying dimensional change caused by the second-order deformation behaviors severely limits the accuracy of the size and shape control of the structural components. The effect of the microstructure evolution mechanism on the second-order deformation behaviors (e.g., Swift effect, inverse Swift effect) of magnesium (Mg) alloys has not been systematically reported. Therefore, in this study, in order to promote the precision forming , the deformation mechanisms of the second-order mechanical behaviors of rolled AZ31B Mg alloy were systematically investigated by employing the specifically designed multi-degree of freedom and multi-axial force-field coupling loading mode. The free-end torsion (FET) experiments were carried out in the range of 30°–90° along the transverse direction (TD) at room temperature and the free-rotatial tension was performed after FET. The Swift effect of axial shortening was observed during FET, and the cumulative effect of misfit strain caused by tensile twinning is the main reason for the Swift effect. Meanwhile, obvious inverse Swift effect was detected in the free-rotatial tension. It is found that the external reverse residual shear stress dominates the rapid reverse rotation of the first stage in the inverse Swift effect, and the nonlinear distribution of the residual shear strain increases this reverse rotation. The competitive effect of detwinning caused by reverse rotation and prismatic slip leads to a slow reverse rotation. The prismatic slip provides the driving force for the inverse Swift effect in the positive rotation stage until the residual shear stress is completely released.

Calorie restriction anti-hypertrophic effects are associated with improved mitochondrial content, blockage of Ca2+-induced mitochondrial damage, and lower reverse electron transport-mediated oxidative stress

Calorie restriction is a nutritional intervention that reproducibly protects against the maladaptive consequences of cardiovascular diseases. Pathological cardiac hypertrophy leads to cellular growth, dysfunction (with mitochondrial dysregulation), and oxidative stress. The mechanisms behind the cardiovascular protective effects of calorie restriction are still under investigation. In this study, we show that this dietetic intervention prevents cardiac protein elevation, avoids fetal gene reprogramming (atrial natriuretic peptide), and blocks the increase in heart weight per tibia length index (HW/TL) seen in isoproterenol-induced cardiac hypertrophy. Our findings suggest that calorie restriction inhibits cardiac pathological growth while also lowering mitochondrial reverse electron transport-induced hydrogen peroxide formation and improving mitochondrial content. Calorie restriction also attenuated the opening of the Ca2+-induced mitochondrial permeability transition pore. We also found that calorie restriction blocked the negative correlation of antioxidant enzymes (superoxide dimutase and glutatione peroxidase activity) and HW/TL, leading to the maintenance of protein sulphydryls and glutathione levels. Given the nature of isoproterenol-induced cardiac hypertrophy, we investigated whether calorie restriction could alter cardiac beta-adrenergic sensitivity. Using isolated rat hearts in a Langendorff system, we found that calorie restricted hearts have preserved beta-adrenergic signaling. In contrast, hypertrophic hearts (treated for seven days with isoproterenol) were insensitive to beta-adrenergic activation using isoproterenol (50 nM). Despite protecting against cardiac hypertrophy, calorie restriction did not alter the lack of responsiveness to isoproterenol in isolated hearts harvested from isoproterenol-treated rats. These results suggest (through a series of mitochondrial, oxidative stress, and cardiac hemodynamic studies) that calorie restriction possesses beneficial effects against hypertrophic cardiomyopathy.

Low stress packaging of the small three-axis gyro

High-precision combined three-axis MEMS gyroscope is popular because of its high integration and miniaturization, but it also puts forward higher requirements for packaging. In this paper, the designed stress isolation structure is bonded between the MEMS chip and the package substrate according to the low stress method, which said the external stress is blocked and offset by the reverse stress generated by the elastic beam in the stress isolation structure, so as to ensure that the MEMS chip is kept in a low stress state. Simulation results show that the stress isolation structure can block 93.3% of the stress transmitted by the outside world. In the actual test, the stress isolation structure can also ensure that the output of the single-axis module of the three-axis gyro is stable and reliable, so as to improve the survival rate of the product.

Abstract 7094: Clinical metabolomics reveals baseline biomarkers of hepatic dysfunction correlating with irregular drug-induced ALT and bilirubin elevations

Abstract AZD4573 is a highly potent and selective Cyclin-Dependent Kinase 9 inhibitor. The AZD4573 First-in-Human (FIH) study revealed variable alanine transaminase (ALT) and/or bilirubin elevation and a clear correlation to dose or PK exposure could not be defined. While concurrent ALT elevation ≥3x upper limit of normal (ULN) and bilirubin elevation ≥2x ULN (potential Hy’s law) is a biochemical finding indicating potential drug-induced liver injury, quantitative modeling disconnected ALT and bilirubin elevation demonstrating that the observations were not Hy’s Law cases. Furthermore, we implemented a targeted metabolomics workflow to investigate the ALT and bilirubin elevation mechanism and identify predictive biomarkers to better understand and/or predict any hepatic stress liabilities associated with AZD4573 clinical development. We implemented an established metabolomics methodology to 359 samples from 15 patients yielding 47,000 total data points. Data was separated into 98 different dosing intervals from the 15 patients to identify the ALT and bilirubin-associated metabolic changes conserved across all patients while incorporating metabolic differences in individual patents with ALT and bilirubin elevation in only a fraction of multiple doses. Orthogonal Partial Least Squares modeling identified several metabolites and pathways altered as a function of maximum ALT or bilirubin levels. Post-dose conjugated bile acids were elevated when ALT and bilirubin were elevated. Pre-dose creatine levels were decreased when ALT and bilirubin elevation occurred, and pre-dose glutamate levels were elevated when ALT elevation occurred. Pre-dose decreased total carnitines and kynurenine pathway activation were observed when ALT and bilirubin elevation occurred, but the effect did not reach statistical significance. Elevated bile acids are an established characteristic of cholestasis and suggest cholestasis as a probable mechanism for AZD4573-induced reversible liver stress. Interestingly, decreased creatine, glutamate elevation, decreased total carnitine, and kynurenine pathway activation are all associated with some form of liver stress or disfunction which may explain the irregular ALT and bilirubin elevations observed in patients receiving AZD4573; while ALT itself is a biomarker of liver damage, these pre-dose biochemical changes may illuminate potential preceding liver stress. Dosing patients already experiencing higher liver stress levels may be more susceptible to drug-induced ALT and bilirubin elevation, and patients with increasing in-study liver stress may only present at later doses. This work demonstrates metabolomics utility to elucidate possible mechanisms of liver toxicity as well as to identify potential predictive biomarkers for further investigation to explore individual patient risk in clinical studies. Citation Format: John K. Meissen, Kevin Contrepois, Sophie Regan, Jennifer Tan, Alison J. Foster, Jiaqi Yuan, Shringi Sharma, Dominic Williams, Anton I. Rosenbaum. Clinical metabolomics reveals baseline biomarkers of hepatic dysfunction correlating with irregular drug-induced ALT and bilirubin elevations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7094.

Synergistic effect of electrical bias and proton irradiation on the electrical performance of β-Ga2O3 p–n diode

The synergistic impact of reverse bias stress and 3 MeV proton irradiation on the β-Ga2O3 p–n diode has been studied from the perspective of the defect in this work. The forward current density (JF) is significantly decreased with the increase in proton irradiation fluence. According to the deep-level transient spectroscopy results, the increase in the acceptor-like trap with an energy level of EC-0.75 eV within the β-Ga2O3 drift layer, which is most likely to be Ga vacancy-related defects, can be the key origin of the device degradation. The increase in these acceptor-like traps results in the carrier concentration reduction, which in turn leads to a decrease in JF. Furthermore, compared with the case of proton irradiation with no bias, the introduction of −100 V electrical stress induced a nearly double decrease in JF. Based on the capacitance–voltage (C–V) measurement, with the support of the electric field, the carrier removal rate increased from 335 to 600 cm−1. Similar to the above-mentioned phenomenon, the trap concentration also increased significantly. We propose a hypothesis elucidating the synergistic effect of electrical stress and proton irradiation through the behavior of recoil nuclei under the electric field.

On the Unloading‐Induced Fault Reactivation: The Effect of Stress Path on Failure Criterion and Rupture Dynamics

AbstractFault reactivations induced by deep excavation can pose significant challenges to underground construction or resource extraction. Laboratory experiments on rock faults demonstrate that unloading‐induced fault reactivations obey the Coulomb failure criterion derived from loading‐induced events. However, the effect of stress path during unloading on the failure criterion and rupture dynamics of fault reactivations remains poorly understood. Here, we present findings from a series of laboratory experiments aimed at elucidating the effect of the unloading path on the failure criterion and rupture dynamics of fault reactivations. We conducted experiments under various stress conditions, examining two cases of unloading paths. In Case I, we unloaded the minimum principal stress, while in Case II, the maximum principal stress was unloaded. Strain gauges and high‐speed photography were employed to capture the transient dynamic rupture process. Our investigations have yielded new insights into the effect of unloading path on the rupture dynamics when the fault is reactivated. In Case I, we observed fault reactivations resembling those loading‐induced events characterized by forward sliding. Conversely, in Case II, fault reactivations associated with stress reversal produce mild reversed sliding with lower stress drop and rupture velocity. Furthermore, we find that there is a remarkable reduction in static friction for reversed sliding, indicating that the failure criterion for fault reactivation is influenced by the stress path. We demonstrate that enhanced stress heterogeneity, caused by stress reversal, serves as a mechanism for reduced static friction. These findings contribute to our understanding of the mechanisms underlying fault reactivations, particularly those involving reversed sliding.

Evaluation of the effect of cannabidiol on the THLE-2 liver cell line exposed to lead

Environmental and soil pollution increase the likelihood of human exposure to toxic metals. Therefore, there is a need for new methods and substances to protect individuals against the harmful effects caused by toxic metals. The study is the first to aim at determining the protective effect of cannabidiol (CBD) against oxidative stress and inflammation induced by toxic metal exposure in Transformed Human Liver Epithelial-2 (THLE-2) cell lines representing healthy liver cells. The IC50 value was determined by exposing THLE-2 human liver healthy cell line to different molarities of lead (Pb) using the XTT kit. The protective efficacy of CBD was assessed by adding 5 μM CBD in addition to the Pb doses determined at IC50 levels to the Pb groups created in cell lines. The levels of GSH, MDA, MPO, CAT, TNF-α, IL-1β, and IL-6 in cell lines were determined using ELISA kits. The inhibition of toxic metal entry into the cells by CBD was assessed through ICP-MS analysis. The IC50 value for Pb was determined as 10 μM in 2D cell lines and 25 μM in 3D cell lines. It was observed that the application of 5 μM concentration of CBD, along with the determined IC50 doses for Pb, increased the cell proliferation rate. Furthermore, the decrease in GSH and CAT levels and the increase in MDA, MPO, TNF-α, IL-1β, and IL-6 levels observed in cell lines treated only with Pb were reversed with the application of CBD. The ICP-MS analysis revealed that CBD reduced the cellular uptake of Pb. The reversal of oxidative stress and inflammation induced by Pb, the increase in cell proliferation, and the reduction in the cellular uptake of toxic metals by CBD can be considered as strong evidence for the protective use of CBD in Pb exposures.

The 2024 Mj 7.6 Noto Peninsula, Japan earthquake caused by the fluid flow in the crust

On January 1, 2024 ​at 16:10:09 JST, an Mj 7.6 earthquake struck the Noto Peninsula in the southern part of the Sea of Japan. This location has been experiencing an earthquake swarm for more than three years. Here, we provide an overview of this earthquake, focusing on the slip distribution of the mainshock and its relationship with the preceding swarm. We also reexamined the source areas of other large earthquakes that occurred around the Sea of Japan in the past and compared them with the Matsushiro earthquake swarm in central Japan from 1964 to 1968. The difference between the Matsushiro earthquake swarm and the Noto earthquake swarm is the surrounding stress field. The Matsushiro earthquake swarm was a strike-slip stress field, so the cracks in the crust were oriented vertically. This allowed fluids seeped from the depths to rise and flow out to the surface. On the other hand, the Noto area was a reverse fault stress field. Therefore, the cracks in the earth's crust were oriented horizontally. Fluids flowing underground in deep areas could not rise and spread over a wide area in the horizontal plane. This may have caused a large amount of fluid to accumulate underground, triggering a large earthquake. Although our proposed mechanism does not take into account other complex geological conditions into consideration, it may provide a simple way to explain why the Noto swarm is followed by a large earthquake while other swarms are not.

Rate sensitive plasticity-based damage model for concrete under dynamic loading

In this manuscript, a rate-sensitive plasticity-based damage model for concrete subjected to dynamic loads is presented. The developed rate-sensitive damage model incorporates the key experimental evidence related to strain rate and damage rate. With increasing strain rates, the model is able to predict a decrease in the rate of damage evolution due to artificial stiffening effects together with a final higher level of damage. The major contribution of the work is to include the effect of damage rate, strain rate and also to consider all the physical mechanisms of damage. This is achieved by using a power law model to relate the rate of damage to the equivalent plastic strain rate. The damage parameter considers hydrostatic, tension and compression damage. Such a damage definition helps in the prediction of pulverized damage due to a loss in cohesive strength at increased hydrostatic stress, shear-induced compressive damage and tensile microcracking. Strong volumetric deformation of the material that includes hydrostatic and compaction damage is also considered in the model. Because hydrostatic damage accounts for the reduction in stiffness and compaction damage accounts for the increase in stiffness under pure compressive loading. A strain rate-dependent failure surface is considered and with increasing strain rate there is an increase in the size of the failure surface which is capped at an upper limiting value. The incremental effective stress-strain relationship is defined in terms of rate of damage, accumulated damage and viscosity parameters reflecting the inherent inertial, thermal and viscous mechanisms respectively. The stress-strain relationship in the model also accounts for stress reversals that occur due to interference of an incident and reflected wave, by including a Heaviside function. The developed model is implemented in LS-DYNA using vectorized UMAT. Verification, validation and parameterization of the developed model have been made through several numerical analyses.

Optimization method of refracturing timing for old shale gas wells

Based on the elastic theory of porous media, embedded discrete fracture model and finite volume method, and considering the micro-seepage mechanism of shale gas, a fully coupled seepage-geomechanical model suitable for fractured shale gas reservoirs is established, the optimization method of refracturing timing is proposed, and the influencing factors of refracturing timing are analyzed based on the data from shale gas well in Fuling of Sichuan Basin. The results show that due to the depletion of formation pressure, the percentage of the maximum horizontal principal stress reversal area in the total area increases and then decreases with time. The closer the area is to the hydraulic fracture, the shorter the time for the peak of the stress reversal area percentage curve to appear, and the shorter the time for the final zero return (to the initial state). The optimum time of refracturing is affected by matrix permeability, initial stress difference and natural fracture approach angle. The larger the matrix permeability and initial stress difference is, the shorter the time for stress reversal area percentage curve to reach peak and return to the initial state, and the earlier the time to take refracturing measures. The larger the natural fracture approach angle is, the more difficult it is for stress reversal to occur near the fracture, and the earlier the optimum refracturing time is. The more likely the stress reversal occurs at the far end of the artificial fracture, the later the optimal time of refracturing is. Reservoirs with low matrix permeability have a rapid decrease in single well productivity. To ensure economic efficiency, measures such as shut-in or gas injection can be taken to restore the stress, and refracturing can be implemented in advance.

Acromial bony adaptations in rotator cuff tear arthropathy facilitates acromial stress fracture following reverse total shoulder arthroplasty

BackgroundAcromial stress fractures (ASFs) after reverse total shoulder arthroplasty (RSA) can have a potentially devastating impact on shoulder function. They are often difficult to effectively treat. Multiple studies have shown a higher incidence of ASF after RSA in patients with cuff tear arthropathy (CTA). This study introduces and explores a new hypothesis. Our hypothesis is that 1) patients with CTA experience a preoperative pathologic superiorly directed force on their acromion, and 2) this leads to acromial bending moments on the acromion that are very different from patients with glenohumeral osteoarthritis (GHOA) and after RSA, and finally 3) these pathologic loads may result in abnormal bony remodeling and adaptations in CTA, which may then predispose patients to ASF after RSA. MethodsA finite element analysis model was developed to compare three loading conditions on the acromion: preoperative CTA, preoperative GHOA, and postoperative-RSA. Regions of the highest tensile and compressive stresses were identified and compared between groups. ResultsThe finite element analysis model presented shows that patients with a preoperative diagnosis of CTA experience a stress distribution reversal after RSA, whereas GHOA patients do not. The results support that in CTA, the humerus produces pathologic strains and torques on the acromion. Over time, the acromion may slowly remodel in response, resulting in bony adaptations. Abrupt reversal of stresses and strains in CTA after RSA may lead to ASFs, as the acromion has adapted to a different stress pattern. ConclusionThis study introduces one potential contributing factor for the higher rates of ASF after RSA in patients with a preoperative diagnosis of CTA; understanding this phenomenon is the first step to preventing it. Once the forces seen in CTA are abruptly reversed after RSA, the biological race is on between the formation of an acromial stress fracture and the body’s ability to again remodel the acromion to accommodate its new loading state. Additional clinical studies are needed to further investigate this new theory.

Shadow loans and regulatory arbitrage: Evidence from China

This paper examines how Chinese banks used on-balance sheet shadow loans for regulatory arbitrage and whether the financial market priced in the banks’ use of shadow loans and the resulting vulnerabilities in 2014–2022. It finds that banks chose to window dress their regulatory capital ratio by using shadow loans when their capital adequacy ratio was close to the regulatory minimum. It also shows that banks with a higher shadow loan ratio or a lower breakeven non-performing loan ratio obtained from reverse stress testing faced higher wholesale funding costs. Finally, after the announcement of a rare bank failure event, more vulnerable banks witnessed lower cumulative stock and bond returns.

On the insignificance of dislocations in reverse bias degradation of lateral GaN-on-Si devices

The role of threading dislocations in the intrinsic degradation of lateral GaN devices during high reverse bias stress tests (RBSTs) is largely unknown. We now present the results on lateral p-GaN/AlGaN/2DEG heterojunctions with a width of 200 μm in GaN-on-Si. A time-dependent permanent degradation of the heterojunction under high reverse bias and elevated temperatures can be observed, ultimately leading to a hard breakdown and device destruction. By using an integrated series p-GaN resistor, the device is protected from destruction and, consequently, the influence of dislocations on the degradation mechanism could be studied. Localization by emission microscopy could show that the transient current increase during a RBST is the result of the creation of a limited amount of highly localized leakage paths along the whole device width. We could establish a 1:1 correlation of leakage sites with a structural material degradation within the AlGaN barrier for nine individual positions on two different devices by planar transmission electron microscopy analysis. To unambiguously show whether dislocations in GaN-on-Si even should be considered a potential trigger for the RBST degradation in lateral heterojunctions, a combined planar and cross-sectional lamella approach was used for the first time for larger devices. This enabled the visualization of the three-dimensional propagation path of the dislocations close to the degradation sites. It was found that there is no statistically significant link between the material degradation and pre-existing dislocations. Our findings offer new insights into the GaN-on-Si material system, upon which upcoming power technologies are built upon.

Experimental investigation of mechanical properties of NiTi superelastic shape memory alloy cables

As a self-centering element in a recoverable functional structure, shape memory alloys (SMAs) usually require a large diameter to provide sufficient bearing capacity, and pre-strain is applied to obtain good self-centering performance and initial stiffness. This study aims to explore the mechanical properties of large-diameter NiTi SMA cables and their potential applications in recoverable functional structures. Through the uniaxial tensile test of 11 SMA cables with 7 × 7 × 1.0 mm, the mechanical properties of SMA cables under different strain amplitudes, cyclic loading effects, loading rates, and different pre-strain modes were evaluated. The results indicate that the energy dissipation capacity of SMA cable increases with the increase of strain amplitude, but at the same time, it will reduce its self-centering capabilities. The equivalent viscous damping ratio decreases after the SMA cable enters the martensitic hardening stage. The residual strain of SMA cable depends on the combined effect of strain amplitude and number of cycles. The larger the strain amplitude and the number of cycles, the more significant the degradation of self-centering performance. After 20 times of constant amplitude loading and unloading, the mechanical properties of SMA cable are relatively stable. The reverse phase transformation stress of the pre-strained SMA cable gradually decreases with the increase of the tensile strain amplitude. The pre-strained SMA cable exhibits a stable restoring force strength in the sub-cycle, and the residual strain is zero. The test results support experimental data for applying large-diameter SMA cables in recoverable functional structures.

Структурно-имитационная модель деформирования сплавов с памятью формы. Часть 2. Описание эффекта реверсивной памяти формы

Within the framework of a one-dimensional structural-simulation model for deformation of shape memory alloys during thermoelastic phase transformations, an adequate description of the process of changes in strains during direct transformation under the influence of reverse stresses and the effect of reverse shape memory has been performed

Tailoring hierarchical pore structures in carbon scaffolds for hydrogen storage of nanoconfined magnesium

Various carbon scaffolds have been developed for the nanoconfinement of Mg/MgH2 to achieve the synergistic effects of nanosizing-induced kinetic improvement, Mg-scaffold interaction-induced catalytic enhancement, and mechanical stress-driven thermodynamic stability tuning for advanced hydrogen storage. Yet, systematic studies linking the chemo-structural features of the carbon scaffolds and the hydrogen storage properties of Mg/MgH2 nanoparticles within the scaffolds remain largely unexplored. Here, we investigate the pore-dependent Mg nanoconfinement and its hydrogen storage behavior using hollow carbon nanospheres (HCNs) as scaffolds, dictated by their distinct pore properties. Contrary to the conventional wisdom of nanoconfinement, the Mg nanoparticles confined by the HCN with large mesopores exhibit faster hydrogen sorption kinetics and improved thermodynamic characteristics than those with small mesopores. The detailed analyses reveal that the interplay between reversible mechanical stress upon hydrogenation and nanosizing-induced facile kinetics leads to the observed experimental results. Ab initio computations further show that compressive stress retards bulk diffusion while at the same time enhances the surface hydrogen desorption, suggesting the need for stress optimization within the composite. Our study provides a design guideline for Mg strain engineering and the subsequent carbon scaffold structures for hydrogen storage, possibly leading to advanced hydrogen storage of confined Mg.