Initial Evolution Research Articles

Dynamic evolution of high-speed railway driver fatigue across scheduling shifts – a simulator study in China

ABSTRACT Scheduling significantly contributes to fatigue among high-speed rail (HSR) drivers, impacting both driving performance and safety. This study aims to analyse distinctiveness and evolutionary patterns of driver fatigue across different scheduling shifts, leveraging an HSR simulator and wearable devices. Through an extensive statistical examination, differences in most heart rate variability features were identified across shifts. The evolution of self-reported fatigue and physiological fatigue was investigated using a Markov chain and a hidden Markov model (HMM) that is extended using softmax regression, respectively. Results indicated a similarity in the initial fatigue state distribution and evolution trends across shifts, albeit with varying degrees of fluctuation. Morning shifts exhibited a higher likelihood of fatigue accumulation. The study revealed that even adequate pre-rest did not entirely counterbalance the impact of circadian rhythms. These findings may contribute to comprehending the temporal dynamics of driver fatigue evolution and offer insights for optimizing driver scheduling practices.

Evolutionary Conserved and Divergent Responses to Copper Zinc Superoxide Dismutase Inhibition in Plants.

After an initial evolution in a reducing environment, life got successively challenged by reactive oxygen species (ROS), especially during the great oxidation event (GOE) that followed the development of photosynthesis. Therefore, ROS are deeply intertwined into the physiological, morphological and transcriptional responses of most present-day organisms. Copper-zinc superoxide dismutases (CuZnSODs) evolved during the GOE and are present in charophytes and extant land plants, but nearly absent from chlorophytes. The chemical inhibitor of CuZnSOD, lung cancer screen 1 (LCS-1), could greatly facilitate the study of SODs in diverse plants. Here, we determined the impact of chemical inhibition of plant CuZnSOD activity, on plant growth, transcription and metabolism. We followed a comparative approach by using different plant species, including Marchantia Polymorpha and Physcomitrium patens, representing bryophytes, the sister lineage to vascular plants, and Arabidopsis thaliana. We show that LCS-1 causes oxidative stress in plants and that the inhibition of CuZnSODs provoked a similar core response that mainly impacted glutathione homoeostasis in all plant species analysed. That said, Physcomitrium and Arabidopsis, which contain multiple CuZnSOD isoforms showed a more complex and exacerbated response. In addition, an untargeted metabolomics approach revealed a specific metabolic signature for each plant species. Our comparative analysis exposes a conserved core response at the physiological and transcriptional level towards LCS-1, while the metabolic response largely varies. These differences correlate with the number and localization of the CuZnSOD isoforms present in each species.

Novel structures and collapse of solitons in nonminimally gravitating dark matter halos

Ultralight dark matter simulations predict condensates with short-range correlation, known as solitons or boson stars, at the centers of dark matter halos. This paper investigates the formation and collapse of dark matter solitons influenced by nonminimal gravitational effects, characterized by gradient-dependent self-interactions of dark matter and an additional source in Poisson's equation for gravity. Our simulations suggest that the initial evolution of dark matter resembles that without nonminimal gravitational effects. However, regions with negative potential curvature may develop, and solitons will collapse when their densities reach certain critical values for both positive and negative coupling constants. With strong nonminimal gravitational effects, we verify that linear density perturbations could grow on both large and small scales, potentially enhancing structure formation.

Dynamics of drug delivery determines course of evolution of antibiotic responses in bacteria.

To adjust to sudden shifts in conditions, microbes possess regulated genetic mechanisms that sense environmental challenges and induce the appropriate responses. The initial evolution of microbes in new environments is thought to be driven by regulatory mutations, but it is not clear how this evolution is affected by how quickly conditions change (i.e. dynamics). Here, we perform experimental evolution on continuous cultures of tetracycline resistant E. coli in different dynamical regimens of drug administration. We find that cultures evolved under gradually increasing drug concentrations acquire fine- tuning mutations adapting an alternative efflux pump to tetracycline. However, cultures that are instead periodically exposed to large drug doses evolve transposon insertions resulting in loss of regulation of the main mechanism of tetracycline resistance. A mathematical model shows that sudden drug exposures overwhelm regulated responses, which cannot induce resistance fast enough. These results help explain the frequent loss of regulation of resistance in clinical pathogens.

Deciphering the Presentation and Etiologies of Hypophysitis Highlights the Need for Repeated Systematical Investigation

Abstract Context Hypophysitis is defined as an inflammation of the pituitary gland and/or infundibulum. Objective Our aim was to characterize the initial course and evolution of patients with hypophysitis according to the different etiologies. Methods Retrospective observational study conducted in a university referral hospital center. Patients over 15 years of age were included if they had a diagnosis of hypophysitis between January 2014 and October 2023, with the exclusion of hypophysitis secondary to immune checkpoint inhibitors. Results Sixty-one patients (64% women; median age, 34 years) were included. Polyuria–polydipsia, headache, and asthenia were present in 64%, 48%, and 44% of cases respectively. At diagnosis, at least 1 anterior pituitary deficiency was present in 91.5% of cases and vasopressin deficiency in 56%. Magnetic resonance imaging was abnormal in 97% of cases. Secondary hypophysitis was found in 46% of cases (n = 28), including sarcoidosis in 28% (n = 17) and L (Langerhans) group histiocytoses in 13.1% (n = 8). Among patients with secondary hypophysitis, pituitary deficiency preceded systemic manifestations in 23% and occurred concomitantly in 23% of cases. Patients were treated in 36% of cases (glucocorticoids, surgery), without improvement of pituitary hormone deficits. Conclusion A systemic etiology of hypophysitis was found in almost half of the patients. Pituitary disorders preceded the systemic disease in a quarter of the cases. This emphasizes the importance of a systematic repeated workup looking for a secondary etiology of hypophysitis in these patients.

Effects of Water Mist on the Initial Evolution of Turbulent Premixed Hydrogen/Air Flame Kernels

In this study, a series of carrier-phase direct numerical simulations are conducted on spherical expanding premixed hydrogen/air flames with liquid water addition. An Eulerian–Lagrangian approach with two-way coupling is employed to describe the liquid–gas interaction. The impacts of preferential diffusion, the equivalence ratio, water loading, and the initial diameter of the water droplets are examined and analyzed in terms of flame evolution. It is observed that liquid water has the potential to influence flame propagation characteristics by reducing the total burning rate, flame area, and burning rate per unit area, attributed to flame cooling effects. However, these effects become discernible only under conditions where water evaporation is sufficiently intense. For the conditions investigated, the influence of preferential diffusion on flame evolution is found to be more significant than the interaction with liquid water. The results suggest that due to the slow evaporation rate of water, which is a result of its high latent heat of evaporation, the water droplets do not disturb the initial flame kernel growth significantly. This has implications for water injection concepts in internal combustion engines and for explosion mitigation.

Stress and temperature dependence of irradiation creep in zircaloy-4 studied using proton irradiation

This paper describes a series of experiments conducted to investigate the in-situ irradiation creep behavior of Zircaloy-4 using proton irradiations as a surrogate to neutrons. The first series of experiments investigated the impact of the initial irradiation-induced defect evolution during the 0 – 0.1 dpa regime on the subsequent in-situ steady-state behavior derived from experimentation. These experiments were conducted at a constant applied load of 85 MPa, a constant damage rate of 1.58 × 10−6 dpa/s, and were repeated at both 250 °C and 350 °C. We also examined the use of a ‘conditioning-irradiation’ step prior to the creep tests on the results derived from subsequent in-situ proton irradiation creep experiments. By extension, we aimed to further develop and refine optimum testing procedures when using proton irradiations to investigate the in-situ creep behavior of nuclear materials. The second series of in-situ proton irradiation experiments were conducted on two Recrystallized (RX) Zircaloy-4 samples in order to investigate the temperature and stress dependence of irradiation creep. One sample was held at a constant load while the temperature was varied in the range of 275 – 350 °C, and the other was held at a constant temperature while stress was varied in the range of 65 – 105 MPa. The associated strains and creep rates were measured at each interval and used to determine an activation temperature of 5000 ± 1700 K and a stress sensitivity exponent of 4.3 ± 0.8 for RX Zr-4 over the given temperature and stress ranges. A discussion of potential deformation mechanisms based on competition between bulk diffusion through the lattice and point defect diffusion enabling dislocation climb and glide is given: the relatively high stress dependence suggested the latter is more likely however further investigations will be required to improve the mechanistic understanding. The results presented in this manuscript, including activation temperature, stress sensitivity, and associated creep rates, determined through proton irradiation investigations are closely comparable to those determined from neutron irradiation experiments found in the literature for similar zirconium alloys at similar temperatures and stresses. Coupled with the primary-secondary creep behavior investigations presented, this demonstrates the usefulness of this approach to estimate neutron-irradiation equivalent creep behavior using in-situ proton irradiation.

An initial value insensitive constrained linear predictive evolution algorithm for gas–liquid phase equilibrium calculation problems

Heuristic algorithms are gradually becoming a type of new promising methods for solving phase equilibrium calculation problems since they do not have to calculate an initial value in advance like traditional methods such as direct Newton's method and indirect thermodynamic method. A new heuristic optimizer, constrained linear prediction evolution algorithm (CLPE) for phase equilibrium calculation under given volume, temperature, and moles (NVT-flash) is proposed in this paper. CLPE employs the total Helmholtz free energy of the NVT-flash problem as its objective function and employs the volume and moles vector of a certain phase as decision variables. Numerical experiments are conducted on four NVT-flash problems. The consistency between the experimental results and those obtained by some traditional methods verifies that the proposed CLPE is effective. The comparative advantage in computational overhead over the similar algorithms indicates the significance of this study. The success of CLPE can drive more heuristic algorithms to solve NVT-flash problems more efficiently, so as to advance the field of phase equilibrium calculation.

Respiratory Worsening at the End of a Hospital Stay for Severe Covid19 Pneumonia Revealing Pulmonary Tuberculosis

The coexistence of a viral and tuberculous respiratory infection increases mortality and the transition to a severe form in both directions. We report an observation for a 55-year-old woman with untreated diffuse interstitial pnuemopathy, investigated by immunological and infectious tests, and found negative for pulmonary tuberculosis. Bronchial biopsies revealed non-specific inflammation, responsible for chronic dyspnea. Having presented ten days previously with myalgias, fatigue, dry cough and fever, with worsening of basic dyspnoea, without digestive or neurological manifestations, she was referred to the emergency department, where physical examination showed SpO2 at 80% on room air, reduced to 92% under 15 L/mn delivered via a high-concentration mask, polypnoea at 40 cycles per minute with bilateral diffuse crackling rales on auscultation, scattering just the anterior quadrants. The initial evolution was favorable, with clinical improvement in oxygen saturation to 94% on two liters per minute of oxygen delivered by nasal cannula, with respiratory rate at 23 cycles per minute with modest effort tolerance. On day 18 of hospitalization, she presented with a febrile peak of 38.3°C, polypnoea at 33 cycles per minute, increased oxygen requirements with a flow rate of 6l/m by face mask to reach an oxygen saturation of 92%, tachycardia at 130 beats per minute, and was therefore readmitted to intensive care with high-flow nasal oxygen therapy and antibiotic therapy with imipenem and amikacin. Multiplex PCR showing no germ, and a PCR test for pulmonary tuberculosis on a sputum sample which was positive, prompting the introduction of antibacillary treatment based on a fixed quadric-association of rifampicin, isoniaside, pyrazinaamide and ethombutol. Non-specific antibiotic therapy was discontinued after improvement of the inflammatory syndrome, and antibacillary treatment is still ongoing. Conclusion: Through this observation we discuss the difficulties in terms of diagnosis, management and outcome of a coinfection by SARS-COV 19 and mycobacterium tuberculosis.

Synergistic Effects of In‐Situ‐Formed Multivalent Titanium and Mg2Ni for Improving the Hydrogen‐Storage Properties of MgH2

AbstractMagnesium hydride (MgH2) has gained significant consideration as a cost‐effective solid‐state hydrogen‐storage material with a substantial hydrogen capacity. However, its practical applications are impeded by its poor kinetics and high thermal stability. In this study, we employed a hydrothermal method and high‐temperature calcination to prepare well‐dispersed NiTiO3 nanoparticles smaller than 20 nm. Next, we investigated the effect of the NiTiO3 nanoparticles for educating the hydrogen storage performance of MgH2. The synergistic catalytic effect of multivalent titanium and Mg2Ni/Mg2NiH4 enhanced hydrogen storage performance of the MgH2 system. The addition of 5 wt % NiTiO3 lowered the initial hydrogen evolution temperature of MgH2 to 194 °C. After 12 minutes at 275 °C, the 5 wt % NiTiO3‐MgH2 composites released 6.1 wt % of hydrogen. The dehydrogenation activation energy (Ea) of the 5 wt % NiTiO3‐MgH2 composites decreased significantly to 38.78±2.1 kJ/mol. Furthermore, hydrogen uptake of 5 wt % NiTiO3‐MgH2 at 125 °C reaches 5.1 wt % in 300 s under hydrogen pressure of 20 bar. These findings introduce an innovative concept for preparing high active catalysts for improving the dehydrogenation/hydrogenation kinetics of MgH2.

Osmium and oxygen isotope constraints on magma-crust interactions and the transport of copper at the roots of arcs

The formation of copper-rich cumulates at the base of arc crusts has been proposed as a key process modulating the geochemical evolution of the continental crust and the genesis of giant ore deposits of copper. Despite the importance of these phenomena, the degree to which the lower crustal evolution of magmatic systems is influenced by open-system interaction and the assimilation of pre-existing crustal materials remains unclear. To tackle this issue, we provide direct isotopic constraints on the evolution of deep magmatic systems in arcs by measuring the osmium and oxygen isotope composition of hydrous copper-rich (∼730 μg·g−1 Cu) ultramafic cumulates formed at the base of the Acadian orogen (∼40 km deep) in the New England Appalachians (northeastern USA). The radiogenic 187Os/188Os initial ratios (ranging from 0.31 to 0.67) and the elevated δ18O values (8.97 ± 0.42 ‰ for orthopyroxene; 9.25 ± 0.26 ‰ for phlogopite) suggest a significant role of open-system magmatic differentiation, involving crustal assimilation, in the formation of these cumulates. Modeling of the 187Os/188Os and δ18O composition of the cumulates suggests that the observed isotopic compositions result from the initial evolution of parental magmas under sulfide-undersaturated conditions, followed by saturation after approximately 15% to 20% of assimilation and fractional crystallization progression. These results suggest that the assimilation of crustal material led to a drop in the magmatic system's fO2 (∼ΔFMQ < −1), triggering sulfide segregation and the formation of copper-rich cumulates. Our findings align with the hypothesis that magma-crust interactions can lead to the formation of lower crustal domains enriched with Cu, which may constitute a pre-stage in the formation of some porphyry copper deposits, particularly in collisional orogens.

Fate of supernova progenitors in massive binary systems

ABSTRACT How massive stars end their lives depends on the core mass, core angular momentum, and hydrogen envelopes at death. However, these key physical facets of stellar evolution can be severely affected by binary interactions. In turn, the effectiveness of binary interactions itself varies greatly depending on the initial conditions of the binaries, making the situation much more complex. We investigate systematically how binary interactions influence core–collapse progenitors and their fates. Binary evolution simulations are performed to survey the parameter space of supernova progenitors in solar metallicity binary systems and to delineate major evolutionary paths. We first study fixed binary mass ratios ($q=M_2/M_1$ = 0.5, 0.7, and 0.9) to elucidate the impacts of initial mass and initial separation on the outcomes, treating separately Type Ibc supernova, Type II supernova, accretion-induced collapse (AIC), rapidly rotating supernova (Ibc-R), black hole formation, and long gamma ray burst (long GRB). We then conduct 12 binary population synthesis model calculations, varying the initial condition distributions and binary evolution parameters, to estimate various supernova fractions. We obtain a Milky Way supernova rate $R_{\rm SN} = (1.78$–$2.47) \times 10^{-2} \, {\rm yr}^{-1}$ which is consistent with observations. We find the rates of AIC, Ibc-R, and long GRB to be $\sim 1/100$ the rate of regular supernovae. Our estimated long GRB rates are higher than the observed long GRB rate and close to the low luminosity GRB rate, although care must be taken considering our models are computed with solar metallicity. Furthering binary modelling and improving the inputs one by one will enable more detailed studies of these and other transients associated with massive stars.

Surface energies control the anisotropic growth of [formula omitted]-Ni(OH)2 nanoparticles in stirred reactors

Nickel hydroxides are an important family of electrode materials in the field of batteries and electrochemical energy storage. Two polymorphs, α-Ni(OH)2 and β-Ni(OH)2 have been identified, with intermediate structures also reported. However, the synthesis of the β-phase precipitants that are ideal for electrochemical applications is not trivial. The growth and morphology of the final products can widely vary with the pH. The electrochemical performance of the β-phase is sensitive to its structure and morphology, which are also sensitive to the reaction conditions. In order to better understand the initial nucleation, growth and morphological evolution of the β-phase, we present a combined experimental and theoretical study including a multiscale phase-field model for the evolution of the morphology of β-Ni(OH)2. Surface indices and energies for the phase-field modeling were obtained from density functional calculations (DFT). The developed phase-field model can reproduce the growth of β-Ni(OH)2 phase in different conditions. The model shows that the basal planes of β-Ni(OH)2 can grow in high pH but at the same time its growth is limited by other high energy prismatic surfaces.

Trace element composition of beryl from spodumene pegmatite deposits of the Kunar Province, Afghanistan

The study of trace element composition of beryl from the Chambalak and Digal deposits of the Darai Pech pegmatite feld of the Kunar province (Afghanistan) using secondary ion mass spectrometry (SIMS) revealed the sectoriality of the beryl crystal from the Chambalak deposit. The inner and outer parts of the profle are identifed as the pinacoid (0001) and prism (10 1 0) growth zones, respectively. At the boundary of these two simple forms, the Cs, Na, Ca, Fe, Mg, and V content strongly increases. The prism growth zone exhibits the growth pyramids: a decrease in the Na, Fe, V, Ni, and Cr content during growth towards the edge of the beryl crystal. The H2O and Mg content increases in the prism growth zone. No boundary between the pinacoid and prism growth zones is observed in beryl from the Digal deposit. There is a reason to consider its profle as the prism growth zone. A comparison of beryl based on the content of indicative elements, the increase of which corresponds to the fractionation trend of pegmatite melt (Cs, Li, and Rb), from pegmatite deposits of the Kunar province with beryl from other objects showed that pegmatite melt in the studied deposits was moderately fractionated corresponding to the initial evolution stages. It is shown that the content of some elements of beryl from the prism and pinacoid growth zones can fundamentally differ.

An observational cohort study examined the change point of kidney function stabilization in the initial period after transplantation

Baseline kidney function following kidney transplantation is often used in research and clinical decision-making yet is not well defined. Here, a method to determine baseline function was proposed and validated on three single-center retrospective cohorts consisting of 922 patients from Belgium (main cohort) and two validation cohorts of 987 patients from the Netherlands and 519 patients from Germany. For each transplant, a segmented regression model was fitted on the estimated glomerular filtration rate (eGFR) evolution during the first-year post-transplantation. This yielded estimates for change point timing, rate of eGFR change before and after change point and eGFR value at change point, now considered the “baseline function”. Associations of eGFR evolution with recipient/donor characteristics and the graft failure rate were assessed with linear regression and Cox regression respectively. The change point occurred on average at an eGFR value of 43.7±14.6 mL/min/1.73m2, at a median time of 6.5 days post-transplantation. Despite significant associations with several baseline donor-recipient characteristics (particularly, donor type; living vs deceased), the predictive value of these characteristics for eGFR value and timing of the change point was limited. This followed from a large heterogeneity within eGFR trajectories, which in turn indicated that favorable levels of kidney function could be reached despite a suboptimal initial evolution. Segmented regression consistently provided a good fit to early eGFR evolution, and its estimate of the change point can be a useful reference value in future analyses. Thus, our study shows that baseline kidney function after transplantation is heterogeneous and partly related to pretransplant donor characteristics.

Competition between Initial CO2 Electroreduction and Hydrogen Evolution Reaction on Cu Catalysts in Acidic Media: Role of Specifically Adsorbed Halide Anions.

The role of halide anions and competing mechanisms between initial CO2 electroreduction pathways and hydrogen evolution reaction (HER) are systematically identified at halide anions modified Cu(111)/H2O interfaces based on density functional theory calculations in this paper. The present results show that halide anions modified Cu(111)/H2O interfaces can notably enhance electroreduction activity of CO2 into CO. Simultaneously, it is concluded that the specifically adsorbed halide anions modified Cu electrodes can inhibit HER by studying competing HER mechanisms, and thus the enhanced CO2 electroreduction activity can be ascribed to the suppressed HER. The origin of enhanced CO production activity and inhibited HER is further scrutinized. The present results show that the presence of halide anions can lead to stronger CO adsorption and the increased adsorption strength of CO can explain easier CO production based on the Sabatier principle. Interestingly, the calculated results show that the presence of halide anions does not exert an effect on H adsorption strength, which is regarded as a key descriptor of HER activity, implying that halide anions modified Cu electrodes may be not able to directly lead to the inhibited HER. However, the present results indicate that co-adsorbed CO can weaken adsorption strength between H and Cu electrodes and thus result in inhibited HER and decreased HER activity. The upshift of d-band centers of surface Cu atoms due to modification of halide anions may be a reason for stronger CO adsorption, whereas the downshift of the d-band center due to the presence of co-adsorbed CO can lead to a weakening effect on H adsorption strength. Our present insights into the role of halide anions can aid in designing an optimal electrolyte and developing electrocatalysts that are more selective toward CO2 electroreduction than HER.

Sexual dimorphisms in body proportions of Masai giraffes and the evolution of the giraffe’s neck

Giraffes exhibit a large sexual dimorphism in body size. Whether sexual dimorphisms also exist in body proportions of the axial and appendicular skeleton has been debated, particularly regarding the giraffe’s iconic long neck. We examined the anatomical proportions of the neck, forelegs, hindlegs, and body trunk of the Masai giraffe (G. tippelskirchi) in captive and wild populations. We found that female Masai giraffes have proportionally longer necks relative to their forelegs than males in contradiction to the original necks-for-sex hypothesis that proposed that the evolution of the giraffe’s long neck was driven by male-male competition. However, male neck width and apparent mass are proportionally larger than females’, supporting a modification of the necks-for-sex hypothesis. Moreover, male foreleg length is proportionally longer whereas female trunk length is proportionally longer. These sexual dimorphisms were found in both captive and wild Masai giraffes. We speculate that the initial evolution of the giraffe’s long neck and legs was driven by interspecific competition and the maternal nutritional demands of gestation and lactation through natural selection to gain a competitive advantage in browsing, and then later the neck mass was further increased as a consequence of male-male competition and sexual selection. Differences in the proportions of major body components define sex phenotypes, but several giraffes display opposite-sex phenotypes with a significantly higher level of discordancy seen in captive males. We speculate that body proportion sexual dimorphisms are maintained in the wild by natural and/or sexual selection, but in captivity selection is relaxed resulting in a higher occurrence of discordances in sexual phenotypes.

CMEs evolve in the interplanetary medium to double their predicted geo-effectiveness

Context. We explore the impact of interactions between coronal mass ejections (CMEs) – known as CME–CME interactions – on Earth using remote-sensing and in situ observations and estimate the amplification of the geo-effectiveness of the individual CMEs by a factor of ∼2 due to CME–CME interactions. Aims. We present 3D reconstructions of interacting CMEs, which provide essential information on the orientation and interaction of the events. Additionally, we analysed coronal evolution of CMEs and their in situ characteristics at 1 AU to explore the impact of interactions between CMEs on their geo-effectiveness. Methods. We analysed CME interaction using white light data from LASCO and STEREO COR-A. The reported CMEs were reconstructed using the gradual cylindrical shell (GCS) model and simulated self-consistently with the physics-based 3D MHD model EUHFORIA (EUropean Heliosphere FORecasting Information Asset). By running different simulations, we estimated the geo-effectiveness of both individual and interacting CMEs using an empirical relationship method for the disturbance storm index. Results. The SOHO/LASCO spacecraft observed three CMEs erupting from the Sun within an interval of 10 h during a very active period in early November 2021. There were two partial halo CMEs that occurred on 1 Nov. 2021 at 19:00 UT and 22:00 UT, respectively, from the active region 12887 (S28W58), and a third halo CME occurred from AR 12891 (N17E03) on 2 Nov. 2021 at 02:48 UT. By combining remote observations close to the Sun, in situ data at 1 AU, and further numerical analyses of each individual CME, we are able to identify the initial and interplanetary evolution of the CMEs. Conclusions. (i) White light observations and a 3D reconstruction of the CMEs show cannibalism by CME-2 on CME-1 and a flank interaction of CME-3 with the merged CME-1 and CME-2 at 45–50 Rs. (ii) Interacting CMEs exhibit an increase in geo-effectiveness compared to an individual CME.

FeO4-Type Active Sites Grown on Fe-Doped Ni Core Surfaces during the Initial Oxygen Evolution Reactions: Fe-Doping Effect?

FeO₄-Type Active Sites Grown on Fe-Doped Ni Core Surfaces during the Initial Oxygen Evolution Reactions: Fe-Doping Effect?

Molecular insight into the decomposition mechanism and stability of CO2 hydrate in the symmetric non-flat double-plate porous media system

Unveiling the decomposition mechanism and stability of hydrate in porous media sediments is the fundamental issue related to hydrate-based CO2 capture and sequestration. In this work, Molecular Dynamics (MD) simulations were performed to study the decomposition mechanism and stability of CO2 hydrate in the porous media of symmetric non-flat double-plate system and explore its mass transfer process. The model of CO2 hydrate in porous media possessing symmetric non-flat double-plate structure was constructed using square quartz (SiO2) as the single crystal material of porous media, illustrating the decomposition mechanism and stability law of CO2 hydrate in such media system. Simulation results indicate that there exists no pretty noteworthy discrepancy between CO2 hydrate in the symmetric non-flat double-plate porous media system and pure CO2 hydrate at the aspect of the decomposition process and sequence. The decomposition process can be divided into two stages: initial cage destruction and CO2 bubble evolution. The decomposition order proceeds in an outside to inside manner generally, with CO2 hydrate decomposition in the middle layer and diagonal region taking priority. Furthermore, the distance between media layers exerts a prominent influence on CO2 hydrate decomposition, which larger distance motivates the decomposition of CO2 hydrate easier. The results also indicated that, compared with pure water system, the stability of CO2 hydrate is greater in the symmetric non-flat double-plate porous media system, with the extreme values of DC reaching 0.64 times only than pure water system. Additionally, CO2 hydrate displayed a stronger stability in the confined space. These findings are beneficial for understanding the decomposition mechanism and stability of CO2 hydrate and provide an interesting insight into geological CO2 sequestration in sediments.