Dynamical Evolution Research Articles

1 joule arbitrary pulse shape hybrid laser source

A hybrid laser source with a profiled laser pulse shape is presented. It is designed with a fiber pulse shaping system and a two-stage solid-state amplifier based on two gain modules with pulsed transverse diode pumping. The ability to control the pulse shape of the hybrid laser source pulse is demonstrated, and rectangular and stepped pulse shapes with a radiation wavelength of 1064.15 nm, duration of 20 ns, repetition rate of 2 Hz, and output energy of 1 J are obtained. The resulting shapes are achieved by controlling the temporal shape of the pulses of the master oscillator to compensate for the effect of gain saturation in solid-state amplifiers. The dynamics of the pulse shape evolution as a function of the electrical pump energy in the gain modules is traced.

Densely populated macrocyclic dicobalt sites in ladder polymers for low-overpotential oxygen reduction catalysis

Dual-atom catalysts featuring synergetic dinuclear active sites, have the potential of breaking the linear scaling relationship of the well-established single-atom catalysts for oxygen reduction reaction; however, the design of dual-atom catalysts with rationalized local microenvironment for high activity and selectivity remains a great challenge. Here we design a bisalphen ladder polymer with well-defined densely populated binuclear cobalt sites on Ketjenblack substrates. The strong electron coupling effect between the fully-conjugated ladder structure and carbon substrates enhances the electron transfer between the cobalt center and oxygen intermediates, inducing the low-to-high spin transition for the 3d electron of Co(II). In situ techniques and theoretical calculations reveal the dynamic evolution of Co2N4O2 active sites and reaction intermediates. In alkaline conditions, the catalyst exhibits impressive oxygen reduction reaction activity featuring an onset potential of 1.10 V and a half-wave potential of 1.00 V, insignificant decay after 30,000 cycles, pushing the overpotential boundaries of ORR electrocatalysis to a low level. This work provides a platform for designing efficient dual-atom catalysts with well-defined coordination and electronic structures in energy conversion technologies.

Evolution dynamics of fundamental mechanisms of wave propagation in gas bubble-liquid interactions and soliton solutions

Abstract This paper investigates the dynamics of solitary wave solutions based on the (3+1)-dimensional nonlinear wave equation with variable coefficients expressed to describe gas-bubble-liquid interactions. The generalised (1/G’)-expansion method, new solitary wave solutions for this equation have been successfully derived to better understand the underlying dynamics of wave phenomena, especially in gas-bubble-liquid systems. Thanks to this method, the results of the variations of physical parameters in the generated solutions are also emphasised. The physical dynamics of each dimension in the generated solutions allow both the dimensions to be compared with each other and the equation to be compared with the existing literature with a holistic understanding. With this application, we have also analyzed the direct effects of the viscosity of the fluid on the dispersion of the bubble. These solitary solutions have helped us to better explain the wave behavior in gas-bubble-liquid systems and provided a new perspective on the solution of nonlinear wave equations. The structure of the study contributes to a deeper understanding of wave phenomena by discussing the (3+1) dimensional variable coefficient nonlinear wave equation within the framework of both mathematical analysis and physical analysis.

The Dynamic Evolution and Knowledge Base of Agricultural Product Supply Chain Research: A Bibliometric Analysis Based on CNKI Literature

This study employs COOC bibliometric analysis, combined with a literature review, to systematically analyze the agricultural supply chain-related documents indexed in China National Knowledge Infrastructure (CNKI). The aim of the research is to reveal the developmental trajectory and current state of agricultural supply chain studies in China, as well as to identify research hotspots and the knowledge base, providing a reference for researchers in this field. The study finds that future research should enhance knowledge cooperation between universities and agricultural research institutions and expand the collaboration network with agricultural supply chain entities. It is recommended that research hotspots be accurately grasped based on national strategies, industry challenges, market demands, and the development status of the supply chain to facilitate the practical application of research outcomes.

Numerical investigation of coal pillar damage mechanisms for various width-to-height ratios

Pillar stability has garnered significant attention owing to the effects of pillars on coal resource recovery rate, coal pillar stability, and coal bump risk. This study examined the roadway stability control principles of conventional and yield coal pillars. The conventional coal pillars were designed as load-bearing structures with a high load-bearing capacity to carry most of the abutment load, while yield coal pillars were designed as buffer structures for transferring rapidly increasing abutment loads to adjacent solid coal ribs by progressive deformation. In order to analyze the features of dynamical evolution of vertical stress distribution and failure zone during loading, a meticulously validated roof–coal–floor composite mathematical model was established.The energy evolution for coal pillars under diverse w/h ratios was analyzed, and the failure energy ratio and elastic strain energy release rate were introduced to evaluate the failure severity. Furthermore, the behavior and damage mechanism differences between conventional and yield coal pillars were investigated: conventional pillars are designed as strong structures that bear most of the load while the yield pillars are designed to buffer and transfer sudden loads to nearby solid coal ribs by gradually deforming. Finally, two case studies of conventional coal pillars in the Zhulinshan coal mine and the yield coal pillars in the Tashan coal mine were reported.

Operando Unveiling of Hydrogen Spillover Mechanisms on Tungsten Oxide Surfaces.

Hydrogen spillover is an important process in catalytic hydrogenation reactions, facilitating H2 activation and modulating surface chemistry of reducible oxide catalysts. This study focuses on the operando unveiling of platinum-induced hydrogen spillover on monoclinic tungsten trioxide (γ-WO3), employing ambient pressure X-ray photoelectron spectroscopy, density functional theory calculations and microkinetic modeling to investigate the dynamic evolution of surface states at varied temperatures. At room temperature, hydrogen spillover results in the formation of W5+ and hydrogen intermediates (hydroxyl species and adsorbed water), facilitated by Pt metal clusters. With increasing temperature, water desorption, reverse hydrogen spillover and surface-to-bulk diffusion of hydrogen atoms compete with each other, leading initially to reoxidation and then further reduction of W atoms in the near-surface. The combined experimental results and simulations provide a comprehensive understanding of the mechanisms underlying hydrogen interaction with reducible metal oxides, lending insights of relevance to the design of enhanced hydrogenation catalysts.

Identification of a Novel HIV-1 Second-Generation Circulating Recombinant Form (CRF117_0107) in China.

Under the background of the main epidemic HIV strains (CRF01_AE and CRF07_BC) co-circulation in China, more HIV second-generation recombinant (SGR) strains with CRF01_AE and CRF07_BC as the backbone were also emerging. In this study, we characterize a novel HIV-1 second-generation circulating recombinant form (CRF117_0107) consisting of CRF01_AE and CRF07_BC fragments from three epidemiologically unrelated HIV-1-infected individuals. One near full-length genome (NFLG) sequence was amplified, sequenced, and spliced in two halves using RNA extracted from the plasma of a homosexual in Shenzhen, Guangdong Province. Two other NFLG sequences were obtained from the Los Alamos HIV Sequence Database under accession numbers KY201177 and MK397789, which were isolated from men who have sex with men (MSM) in Guangdong Province and Zhejiang Province, respectively. Phylogenetic analysis revealed that these NFLG sequences formed a monophyletic cluster with a high bootstrap value of 1.0. Recombination analysis demonstrated that the genome of CRF117_0107 was separated into three segments by two breakpoints. Further subregional phylogenetic analysis was performed that showed segment I+III (790-5990nt, 8295-9412nt) of CRF117_0107 originated from the CRF07_BC cluster, and Segment I+III (5991-8294nt) originated from the CRF01_AE cluster. The appearance of CRF117_0107 further highlights that HIV-1 SGR strains containing CRF01_AE and CRF07_BC will be generated more frequently and will most likely be more conducive to accelerating the spread of HIV in China. This study suggested it's essential to monitor HIV-1 second-generation CRFs among high-risk populations such as MSM for the epidemic and evolution dynamics of HIV-1 in China.

Punctuated versus gradual shifts in the multivariate evolutionary process: a test with paired radiations of scincid lizards.

As lineages become separated in time, they are expected to accumulate mutational (or developmental-genetic) differences that influence the macroevolutionary trajectories of those lineages even under similar environmental conditions. Here, we compare the dynamics of phenotypic evolution in radiations of scincid lizards from Australia and Madagascar that are separated by more than 100 million years of independent evolution and show rampant phenotypic parallelism. We collected linear measurements of the skull, limbs, and limb girdles from micro-CT scans of 94 Australian and 29 Malagasy species. Using multivariate comparative methods, we tested whether the underlying evolutionary covariance structure for this superficial parallelism was conserved and whether these patterns were consistent across distinct functional modules. Malagasy and most Australian skinks have similar covariance matrices for skull evolution. Results are ambiguous for limbs and limb girdles, as some trait subsets support different evolutionary processes and for other subsets, a shared covariance matrix could not be rejected. However, across most trait sets, the extremely speciose Australian genus Ctenotus exhibits a radically different covariance structure from all other lizards in these groups, including several closely related genera. The shift in Ctenotus demonstrates that the architecture of trait correlations can change at relatively shallow timescales and may explain the unique position of this clade in morphospace relative to other scincid lizards from both geographic regions. More generally, our results demonstrate that the multivariate evolutionary process can change dramatically in a relatively short period of time.

Time-resolved spectroscopy uncovers deprotonation-induced reconstruction in oxygen-evolution NiFe-based (oxy)hydroxides

Transition-metal layered double hydroxides are widely utilized as electrocatalysts for the oxygen evolution reaction (OER), undergoing dynamic transformation into active oxyhydroxides during electrochemical operation. Nonetheless, our understanding of the non-equilibrium structural changes that occur during this process remains limited. In this study, utilizing in situ energy-dispersive X-ray absorption spectroscopy and machine learning analysis, we reveal the occurrence of deprotonation and elucidate the role of incorporated iron in facilitating the transition from nickel-iron layered double hydroxide (NiFe LDH) into its active oxyhydroxide. Our findings demonstrate that iron substitution promotes deprotonation process within NiFe LDH, resulting in the preferential removal of protons from the specific bridged hydroxyl group (Ni2+-OH-Fe3+) linked to edge-sharing [NiO6] and [FeO6] octahedron. This deprotonation behavior drives the formation of high-valence Ni3+δ species (0 <δ < 1), which subsequently serve as the active sites, thereby ensuring efficient oxygen evolution activity. This approach offers high-resolution insights of dynamic structural evolution, overcoming the limitations of extended acquisition times and advancing our understanding of OER mechanisms.

The Importance of Gas Starvation in Driving Satellite Quenching in Galaxy Groups at z ~ 0.8

Abstract We present results from a Keck/DEIMOS survey to study satellite quenching in group environments at z ~ 0.8 within the Extended Groth Strip (EGS). We target 11 groups in the EGS with extended X-ray emission. We obtain high-quality spectroscopic redshifts for group member candidates, extending to depths over 1 order of magnitude fainter than existing DEEP2/DEEP3 spectroscopy. This depth enables the first spectroscopic measurement of the satellite quiescent fraction down to stellar masses of ~109.5 M ⊙ at this redshift. By combining an infall-based environmental quenching model, constrained by the observed quiescent fractions, with infall histories of simulated groups from the IllustrisTNG100-1-Dark simulation, we estimate environmental quenching timescales (τ quench) for the observed group population. At high stellar masses (M⋆ = 1010.5 M ⊙) we find that τ quench = 2.4 + 0.2 − 0.2 Gyr, which is consistent with previous estimates at this epoch. At lower stellar masses (M⋆ = 109.5 M ⊙), we find that τ quench = 3.1 + 0.5 − 0.4 Gyr, which is shorter than prior estimates from photometry-based investigations. These timescales are consistent with satellite quenching via starvation, provided the hot gas envelope of infalling satellites is not stripped away. We find that the evolution in the quenching timescale between 0 &lt;z &lt;1 aligns with the evolution in the dynamical time of the host halo and the total cold gas depletion time. This suggests that the doubling of the quenching timescale in groups since z ~ 1 could be related to the dynamical evolution of groups or a decrease in quenching efficiency via starvation with decreasing redshift.

Combining REBOUND and MESA: dynamical evolution of planets orbiting interacting binaries

ABSTRACT Although planets have been found orbiting binary systems, whether they can survive binary interactions is debated. While the tightest-orbit binaries should host the most dynamically stable and long-lived circumbinary planetary systems, they are also the systems that are expected to experience mass transfer, common envelope evolution, or stellar mergers. In this study, we explore the effect of stable non-conservative mass transfer on the dynamical evolution of circumbinary planets. We present a new script that seamlessly integrates binary evolution data from the 1D binary stellar evolution code mesa into the N-body simulation code rebound. This integration framework enables a comprehensive examination of the dynamical evolution of circumbinary planets orbiting mass-transferring binaries, while simultaneously accounting for the detailed stellar structure evolution. In addition, we introduce a recalibration method to mitigate numerical errors from updates of binary properties during the system’s dynamical evolution. We construct a reference binary model in which a $2.21\, \mathrm{ M}_\odot$ star loses its hydrogen-rich envelope through non-conservative mass transfer to the $1.76\, \mathrm{ M}_\odot$ companion star, creating a $0.38\, \mathrm{ M}_\odot$ subdwarf. We find the tightest stable semimajor axis for circumbinary planets to be $\simeq 2.5$ times the binary separation after mass transfer. Accounting for tides by using the interior stellar structure, we find that tidal effects become apparent after the rapid mass transfer phase and start to fade away during the latter stage of the slow mass transfer phase. Our research provides a new framework for exploring circumbinary planet dynamics in interacting binary systems.

Emergency medicine : what's new in 2024

Emergency medicine plays a crucial vital role as the gateway to the Swiss healthcare system. Although it has not yet been officially recognized with a specialist title, unlike most European countries - emergency medicine in Switzerland is characterized by robust research activity. This scientific article demonstrates a dynamic and rigorous evolution. In this edition, we present six articles authored by Swiss emergency physicians, each examining different aspects of our field. Topics include gender stereotypes, prehospital cardiac arrest, the unique needs of the older patients in emergency department, the administration of antifibrinolytics in trauma cases, and a predictive model for infectious endocarditis.

Recent Advances in the Performance and Mechanisms of High-Entropy Alloys Under Low- and High-Temperature Conditions

High-entropy alloys, since their development, have demonstrated great potential for applications in extreme temperatures. This article reviews recent progress in their mechanical performance, microstructural evolution, and deformation mechanisms at low and high temperatures. Under low-temperature conditions, the focus is on alloys with face-centered cubic, body-centered cubic, and multi-phase structures. Special attention is given to their strength, toughness, strain-hardening capacity, and plastic-toughening mechanisms in cold environments. The key roles of lattice distortion, nanoscale twin formation, and deformation-induced martensitic transformation in enhancing low-temperature performance are highlighted. Dynamic mechanical behavior, microstructural evolution, and deformation characteristics at various strain rates under cold conditions are also summarized. Research progress on transition metal-based and refractory high-entropy alloys is reviewed for high-temperature environments, emphasizing their thermal stability, oxidation resistance, and frictional properties. The discussion reveals the importance of precipitation strengthening and multi-phase microstructure design in improving high-temperature strength and elasticity. Advanced fabrication methods, including additive manufacturing and high-pressure torsion, are examined to optimize microstructures and improve service performance. Finally, this review suggests that future research should focus on understanding low-temperature toughening mechanisms and enhancing high-temperature creep resistance. Further work on cost-effective alloy design, dynamic mechanical behavior exploration, and innovative fabrication methods will be essential. These efforts will help meet engineering demands in extreme environments.

Dissociation–Precipitation Chemistry of Lithium Polysulfides and Its Correlation to Dynamic Evolution of Cathode–Electrolyte Interphase in Highly Solvating Electrolyte

Dissociation–Precipitation Chemistry of Lithium Polysulfides and Its Correlation to Dynamic Evolution of Cathode–Electrolyte Interphase in Highly Solvating Electrolyte

Advances in Oxygen Evolution Reaction Electrocatalysts via Direct Oxygen-Oxygen Radical Coupling Pathway.

Oxygen evolution reaction (OER) is a cornerstone of various electrochemical energy conversion and storage systems, including water splitting, CO2/N2 reduction, reversible fuel cells, and rechargeable metal-air batteries. OER typically proceeds through three primary mechanisms: adsorbate evolution mechanism (AEM), lattice oxygen oxidation mechanism (LOM), and oxide path mechanism (OPM). Unlike AEM and LOM, the OPM proceeds via direct oxygen-oxygen radical coupling that can bypass linear scaling relationships of reaction intermediates in AEM and avoid catalyst structural collapse in LOM, thereby enabling enhanced catalytic activity and stability. Despite its unique advantage, electrocatalysts that can drive OER via OPM remain nascent and are increasingly recognized as critical. This review discusses recent advances in OPM-based OER electrocatalysts. It starts by analyzing three reaction mechanisms that guide the design of electrocatalysts. Then, several types of novel materials, including atomic ensembles, metal oxides, perovskite oxides, and molecular complexes, are highlighted. Afterward, operando characterization techniques used to monitor the dynamic evolution of active sites and reaction intermediates are examined. The review concludes by discussing several research directions to advance OPM-based OER electrocatalysts toward practical applications.

Dynamic simulation of landscape ecological risk in Gansu’s farming-pastoral ecotone based on topographic gradients

The farming-pastoral ecotone in Gansu Province, a crucial green barrier in northwestern China, faces a conflict between economic development and environmental fragility. Scientifically assessing the landscape ecological risks in this region is essential for developing an early warning system for ecological security and ensuring the sustainable management of regional ecosystems. This study systematically analyzes the dynamic evolution patterns and clustering characteristics of landscape ecological risk along the topographic gradient in the area, using Land-Use and Land-Cover Change (LUCC) data from five periods (each period representing 10 years) between 1980 and 2020, as well as Digital Elevation Model (DEM) data. Methods such as CA-Markov and the Topographic Position Index (TPI) were employed to assess these risks. Additionally, the study simulates the spatial distribution patterns of ecological risks in future years. The results reveal that from 1980 to 2020, the area of built-up land in the farming-pastoral ecotone of Gansu Province increased by approximately 82%, with roughly 21% of the expansion occurring at the expense of grasslands and 53% from arable land. Ecological risk in the study area exhibits a spatial distribution pattern characterized by lower risk in the southwest and higher risk in the northeast. Overall, ecological risk initially increased and then decreased. The area of high-risk zones has steadily decreased by approximately 50% since 2010, primarily in regions with low topographic gradients and high human activity. In other areas, high-risk levels are directly proportional to the topographic gradient, showing a high degree of spatial clustering. Consequently, land-use planning should be tailored to local conditions, and a long-term monitoring mechanism should be established. This study provides novel insights into the spatiotemporal changes in landscape ecological risk in ecologically vulnerable areas, focusing on topographic gradients.

Dissociation-Precipitation Chemistry of Lithium Polysulfides and Its Correlation to Dynamic Evolution of Cathode-Electrolyte Interphase in Highly Solvating Electrolyte.

Lithium-sulfur (Li-S) batteries has been regarded as one of the most promising next-generation energy storage systems due to their high theoretical energy density. However, the practical application of Li-S batteries is still hindered by the unstable cathode-electrolyte interphase and the early passivation of charge product (Li2S), leading to poor cycling stability and low S utilization. Herein, we propose an electrolyte engineering strategy using highly solvating hexamethylphosphoramide (HMPA) as a co-solvent to elucidate the dissociation-precipitation chemistry of lithium polysulfides (LiPSs). The multimode optical spectroscopies confirm that this electrolyte engineering is able to effectively regulate the solvation of LiPSs to initiate a radical-assisted conversion pathway and control three-dimensional (3D) Li2S electrodeposition to boost sulfur utilization. More importantly, the dynamic evolution of cathode-electrolyte interphase, featuring with S-/P-containing species, is also assessed by both distribution of relaxation times technology and X-ray photoelectron spectroscopy, which can suppress the passivation of Li2S to enhance conversion reversibility. As a proof-of-concept, a Li-S cell with high S loading mass of 7.75 mg cm-2 demonstrates an extremely high area capacity of 7.86 mAh cm-2 at a current density of 1.30 mA cm-2 , representing a significant advancement in promoting the development of practical high-energy-density Li-S batteries.

Leveraging dynamics informed neural networks for predictive modeling of COVID-19 spread: a hybrid SEIRV-DNNs approach

A dynamics informed neural networks (DINNs) incorporating the susceptible-exposed-infectious-recovered-vaccinated (SEIRV) model was developed to enhance the understanding of the temporal evolution dynamics of infectious diseases. This work integrates differential equations with deep neural networks to predict time-varying parameters in the SEIRV model. Experimental results based on reported data from China between January 1, and December 1, 2022, demonstrate that the proposed dynamics informed neural networks (DINNs) method can accurately learn the dynamics and predict future states. Our proposed hybrid SEIRV-DNNs model can also be applied to other infectious diseases such as influenza and dengue, with some modifications to the compartments and parameters in the model to accommodate the related control measures. This approach will facilitate improving predictive modeling and optimizing public health intervention strategies.

Plastome data provides new insights into population differentiation and evolution of Ginkgo in the Sichuan Basin of China

BackgroundGinkgo biloba L., an iconic living fossil, challenges traditional views of evolutionary stasis. While nuclear genomic studies have revealed population structure across China, the evolutionary patterns reflected in maternally inherited plastomes remain unclear, particularly in the Sichuan Basin - a potential glacial refugium that may have played a crucial role in Ginkgo’s persistence.ResultsAnalysis of 227 complete plastomes, including 81 newly sampled individuals from the Sichuan Basin, revealed three distinct maternal lineages differing from known nuclear genome patterns. We identified 170 sequence variants and extensive RNA editing (235 sites) with a bias toward hydrophobic amino acid conversions, suggesting active molecular evolution. A previously undocumented haplotype (IIA2), predominant in western Sichuan Basin populations, showed close genetic affinity with rare refugial haplotypes. Western populations exhibited higher haplotypic diversity and distinctive genetic structure, supporting the basin’s role as both glacial refugium and corridor for population expansion. Ancient trees (314–784 years) provided evidence for interaction between natural processes and historical human dispersal in shaping current genetic patterns.ConclusionsOur findings demonstrate substantial genetic diversity within Sichuan Basin Ginkgo populations and reveal dynamic molecular evolution through plastome variation and RNA editing patterns, challenging the notion of evolutionary stasis in this living fossil. This study provides crucial genomic resources for understanding Ginkgo’s evolution and informs conservation strategies for this endangered species.

Modeling and Simulation of Dynamic Recrystallization Microstructure Evolution for GCr15 Steel Using the Level Set Method.

The microstructure of metallic materials plays a crucial role in determining their performance. In order to accurately predict the dynamic recrystallization (DRX) behavior and microstructural evolution during the hot deformation process of GCr15 bearing steel, a microstructural evolution model for the DRX process of GCr15 steel was established by combining the level set (LS) method with the Yoshie-Laasraoui-Jonas dislocation dynamics model. Firstly, hot compression tests were conducted on GCr15 steel using the Gleeble-1500D thermal simulator, and the hardening coefficient k1 and dynamic recovery coefficient k2 of the Yoshie-Laasraoui-Jonas model were derived from the experimental flow stress data. The effects of temperature, strain, and strain rate on DRX behavior and grain size during the hot working process of GCr15 steel were investigated. Through secondary development of the software, the established microstructural evolution model was integrated into the DIGIMU® software. Metallographic images were imported in situ to reconstruct its initial microstructure, enabling GCr15 steel DRX microstructure finite element simulation of the hot compression process. The predicted mean grain size and flow stress demonstrated a strong correlation and excellent agreement with the experimental results. The results demonstrate that the established DRX model effectively predicts the evolution of the DRX fraction and average grain size during the hot forging process and reliably forecasts DRX behavior.