Unraveling the significance of cobalt on transformation kinetics,crystallography and impact toughness in high-strength steels

This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.

Depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite

The depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite still lacked in-depth insight.Therefore,the depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite was further systematically investigated with experiments and density functional theory(DFT)calculations.The X-ray photoelectric spectroscopy(XPS)results,DFT calculation results,and frontier molecular orbital analysis indicated that sulfite ions were difficult to be adsorbed on sphalerite surface,suggesting that sulfite ions achieved depression effects on sphalerite through other non-adsorption mechanisms.First,the oxygen content in the surface of sphalerite treated with sulfite ions in creased,which enhanced the hydrophilicity of the sphalerite and further increased the difference in hydrophilicity between sphalerite and galena.Then,sulfite ions were chelated with lead ions to form PbSO_(3)in solution.The hydrophilic PbSO_(3)was more easily adsorbed on sphalerite than galena.The interaction between sulfite ions and lead ions could effectively inhibit the activation of sphalerite.In addition the UV spectrum showed that after adding sulfite ions,the peak of perxanthate in the sphalerite treated xanthate solution was significantly stronger than that in the galena with xanthate solution,indicating that xanthate interacted more readily with sulfite ions and oxygen mo lecules within the sphalerite system,leading to the formation of perxanthate.However,sulfite ions hardly depressed the flotation of ga lena and could promote the flotation of galena to some extent.This study deepened the understanding of the depression mechanism o sulfite ions on sphalerite and Pb^(2+)activated sphalerite.

Impact fracturing of rock-like material using carbon dioxide under different temperatures and pressures

Unconventional resources (oil, gas, and geothermal) are often buried deep underground within dense rock strata and complex geological structures, making it increasingly difficult to create volumetric fractures through conventional hydraulic fracturing. This paper introduces a novel method of supercritical energetic fluid thermal shock fracturing. It pioneers a CO_(2) deflagration impact triaxial pneumatic fracturing experimental system, using high-strength similar materials to simulate deep, hard rock masses. The study investigates the rock-breaking process and crack propagation patterns under supercritical CO_(2) thermal shock, revealing and discussing the types of thermal shock-induced fractures, their formation conditions, and discrimination criteria. The research indicates that higher supercritical CO_(2) thermal shock pressures and faster pressure release rates facilitate the formation of radial branching fractures, circumferential cracks, and branch cracks. Typically, CO_(2) thermal shock generates 3–5 radial main cracks, which is significantly more than the single main crack formed by hydraulic fracturing. The formation of branched cracks is often caused by compression-shear failure and occurs under relatively harsh conditions, determined by the confining pressure, rock properties, peak thermal shock pressure, and the pressure sustained post-decompression. The findings are expected to offer a safe, efficient, and controllable shockwave method of supercritical fluid thermal shock fracturing for the exploitation of deep unconventional oil and gas resources.

Decoding molecular mechanisms:brain aging and Alzheimer's disease

The complex morphological,anatomical,physiological,and chemical mechanisms within the aging brain have been the hot topic of research for centuries.The aging process alters the brain structure that affects functions and cognitions,but the worsening of such processes contributes to the pathogenesis of neurodegenerative disorders,such as Alzheimer's disease.Beyond these observable,mild morphological shifts,significant functional modifications in neurotransmission and neuronal activity critically influence the aging brain.Understanding these changes is important for maintaining cognitive health,especially given the increasing prevalence of age-related conditions that affect cognition.This review aims to explore the age-induced changes in brain plasticity and molecular processes,differentiating normal aging from the pathogenesis of Alzheimer's disease,thereby providing insights into predicting the risk of dementia,particularly Alzheimer's disease.

Pyroptosis,ferroptosis,and autophagy in spinal cord injury:regulatory mechanisms and therapeutic targets

Regulated cell death is a form of cell death that is actively controlled by biomolecules.Several studies have shown that regulated cell death plays a key role after spinal cord injury.Pyroptosis and ferroptosis are newly discovered types of regulated cell deaths that have been shown to exacerbate inflammation and lead to cell death in damaged spinal cords.Autophagy,a complex form of cell death that is interconnected with various regulated cell death mechanisms,has garnered significant attention in the study of spinal cord injury.This injury triggers not only cell death but also cellular survival responses.Multiple signaling pathways play pivotal roles in influencing the processes of both deterioration and repair in spinal cord injury by regulating pyroptosis,ferroptosis,and autophagy.Therefore,this review aims to comprehensively examine the mechanisms underlying regulated cell deaths,the signaling pathways that modulate these mechanisms,and the potential therapeutic targets for spinal cord injury.Our analysis suggests that targeting the common regulatory signaling pathways of different regulated cell deaths could be a promising strategy to promote cell survival and enhance the repair of spinal cord injury.Moreover,a holistic approach that incorporates multiple regulated cell deaths and their regulatory pathways presents a promising multi-target therapeutic strategy for the management of spinal cord injury.

Innovative dispersion techniques of graphene nanoplatelets(GNPs)through mechanical stirring and ultrasonication:Impact on morphological,mechanical,and thermal properties of epoxy nanocomposites

Graphene nanoplatelets(GNPs)have attracted tremendous interest due to their unique properties and bonding capabilities.This study focuses on the effect of GNP dispersion on the mechanical,thermal,and morphological behavior of GNP/epoxy nanocomposites.This study aims to understand how the dispersion of GNPs affects the properties of epoxy nanocomposite and to identify the best dispersion approach for improving mechanical performance.A solvent mixing technique that includes mechanical stirring and ultrasonication was used for producing the nanocomposites.Fourier transform infrared spectroscopy was used to investigate the interaction between GNPs and the epoxy matrix.The measurements of density and moisture content were used to confirm that GNPs were successfully incorporated into the nanocomposite.The findings showed that GNPs are successfully dispersed in the epoxy matrix by combining mechanical stirring and ultrasonication in a single step,producing well-dispersed nanocomposites with improved mechanical properties.Particularly,the nanocomposites at a low GNP loading of 0.1 wt%,demonstrate superior mechanical strength,as shown by increased tensile properties,including improved Young's modulus(1.86 GPa),strength(57.31 MPa),and elongation at break(4.98).The nanocomposite with 0.25 wt%GNP loading performs better,according to the viscoelastic analysis and flexural properties(113.18 MPa).Except for the nanocomposite with a 0.5 wt%GNP loading,which has a higher thermal breakdown temperature,the thermal characteristics do not significantly alter.The effective dispersion of GNPs in the epoxy matrix and low agglomeration is confirmed by the morphological characterization.The findings help with filler selection and identifying the best dispersion approach,which improves mechanical performance.The effective integration of GNPs and their interaction with the epoxy matrix provides the doorway for additional investigation and the development of sophisticated nanocomposites.In fields like aerospace,automotive,and electronics where higher mechanical performance and functionality are required,GNPs'improved mechanical properties and successful dispersion present exciting potential.

A Three-Dimensional SPH Simulation of Lander Footpad Impact on a Lunar Regolith Bed

Landing spacecraft experience significant impact forces during landing,resulting in large deformation and failure in the soil surface,which severely affects landing safety and stability.This paper establishes a smoothed particle hydrodynamics(SPH)model based on the theory of soil elastoplastic constitutive relations to describe the process of a lander’s footpad impacting lunar regolith vertically.The model can provide engineering indices such as impact load and penetration depth,and illustrate the large deformation and crater characteristics of the regolith.A detailed analysis of the response of the footpad and lunar regolith during landing reveals that the process can be broadly divided into two stages of rapid penetration and oscillatory attenuation.Furthermore,there are significant similarities in the landing process under different landing velocities and footpad masses.The research investigates the large deformation and crater characteristics of the lunar regolith bed.The results demonstrate two failure modes in the regolith.Under the impact of a footpad with a smaller mass,the final failure surface of the regolith exhibits a bowl-shaped profile with a uniformly open mouth.In contrast,under the impact of a footpad with a larger mass,the final failure surface of the regolith presents an urn-shaped profile with a large abdomen and a small opening.However,the impact craters in both scenarios show a bowl-like distribution.In cases of high-velocity impacts,the impact crater exhibits obvious blocky spalling on its sides.The SPH model developed in this study can be applied to predict the large deformation and failure response of lunar soil under the impact of rigid structures as well as the impact load and penetration depth.It effectively predicts the dynamic response of the landing process,which is expected to provide a reference for engineering design.

Concurrent occurrence of adenocarcinoma and urothelial carcinoma of the prostate:Coexistence mechanisms from multiple perspectives

This article discusses the coexistence of prostate adenocarcinoma and prostate urothelial carcinoma.Combining existing literature and research results,the potential mechanisms of the co-occurrence of these two cancers are explored,including the role of androgen receptor,gene mutations,and their complex interactions in cell signaling pathways,etc.Also,the hypothesis of prostate cancer transformation into urothelial carcinoma is explained from some perspectives,including tumor multipotent stem cell differentiation,epithelial-mesenchymal transition,mesenchymal-epithelial transition,and other mechanisms.Ultimately,the goal is to provide more accurate diagnoses and more personalized treatments in clinical practice,as well as to lay the foundation for improving patient prognoses in the future.

Mesoscopic fracture damage evolution and fractal damage constitutive model of heat-treated red sandstone under direct tensile impact loadings

Understanding the mesoscopic tensile fracture damage of rock is the basis of evaluating the deterioration process of mechanical properties of heat-damaged rock. For this, tensile tests of rocks under high-temperature treatment were conducted with a ϕ75 mm split Hopkinson tension bar (SHTB) to investigate the mesoscopic fracture and damage properties of rock. An improved scanning electron microscopy (SEM) experimental method was used to analyze the tensile fracture surfaces of rock samples. Qualitative and quantitative analyses were performed to assess evolution of mesoscopic damage of heat-damaged rock under tensile loading. A constitutive model describing the mesoscopic fractal damage under thermo-mechanical coupling was established. The results showed that the high temperatures significantly reduced the tensile strength and fracture surface roughness of the red sandstone. The three-dimensional (3D) reconstruction of the fracture surface of the samples that experienced tensile failure at 900 °C showed a flat surface. The standard deviation of elevation and slope angle of specimen fracture surface first increased and then decreased with increasing temperature. The threshold for brittle fracture of the heat-damaged red sandstone specimens was 600 °C. Beyond this threshold temperature, local ductile fracture occurred, resulting in plastic deformation of the fracture surface during tensile fracturing. With increase of temperature, the internal meso-structure of samples was strengthened slightly at first and then deteriorated gradually, which was consistent with the change of macroscopic mechanical properties of red sandstone. The mesoscopic characteristics, such as the number, mean side length, maximum area, porosity, and fractal dimension of crack, exhibited an initial decline, followed by a gradual increase. The development of microcracks in samples had significant influence on mesoscopic fractal dimension. The mesoscopic fractal characteristics were used to establish a mesoscopic fractal damage constitutive model for red sandstone, and the agreement between the theoretical and experimental results validated the proposed model.

Travelling characteristics of road vehicles on single-level rail-cum-road bridge under the dynamic and aerodynamic impact of travelling trains

Aerodynamic and dynamic interference from trains is a key issue of concern for the safety of road vehicles travelling on single-level rail-cum road bridges.Based on the wind-road vehicle-train-bridge(WRTB)coupled vibration system developed herein,this study examines the dynamic characteristics when road vehicles meet trains in this situation.The influence of load combination,vehicle type and vehicle location is analyzed.A method to obtain the aerodynamic load of road vehicles encountering the train at an arbitrary wind speed is proposed.The results show that due to the windproof facilities and the large line distance between the railway and highway,the aerodynamic and dynamic influence of trains on road vehicles is slight,and the vibration of road vehicles depends on the road roughness.Among the road vehicles discussed,the bus is the easiest to rollover,and the truck-trailer is the easiest to sideslip.Compared with the aerodynamic impact of trains,the crosswind has a more significant influence on road vehicles.The first peak/valley value of aerodynamic loads determines the maximum dynamic response,and the quick method is optimized based on this conclusion.Test cases show that the optimized method can produce conservative results and can be used for relevant research or engineering applications.

Acupuncture for postoperative ileus:Advancement and underlying mechanisms

Postoperative ileus(POI)remains a prevalent and significant challenge following abdominal surgeries,precipitating patient distress,prolonged hospital stays,and escalated medical expenditures.Conventionally addressed via pharmacological interventions,POI is increasingly being explored through adjunctive therapeutic strategies,with acupuncture gaining recognition as a promising option.Acupuncture has demonstrated encouraging potential in promoting gastrointestinal motility in patients with POI.Moreover,recent research has shed light on the therapeutic mechanisms underlying its efficacy.This article aims to present a comprehensive overview of acupuncture as a treatment for POI,highlighting advancements in clinical research and recent elucidations of its mechanistic underpinnings.It aspires to contribute a pivotal reference point for scholars and enthusiasts keen on garnering a deeper understanding of acupuncture’s role in managing POI.

Study on damage mechanism and damage distribution of the rear plate under impact of debris cloud

The debris cloud generated by the hypervelocity impact(HVI)of orbiting space debris directly threatens the spacecraft.A full understanding of the damage mechanism of rear plate is useful for the optimal design of protective structures.In this study,the hypervelocity yaw impact of a cylindrical aluminum projectile on a double-layer aluminum plate is simulated by the FE-SPH adaptive method,and the damage process of the rear plate under the impact of the debris cloud is analyzed based on the debris cloud structure.The damage process can be divided into the main impact stage of the debris cloud and the structural response of the rear plate.The main impact stage lasts a short time and is the basis of the rear plate damage.In the stage of structure response,the continuous deformation and inertial motion of the rear plate dominate the perforation of the rear plate.We further analyze the damage mechanism and damage distribution characteristics of the rear plate in detail.Moreover,the connection between velocity space and position space of the debris cloud is established,which promotes the general analysis of the damage law of debris cloud.Based on the relationship,the features of typical damage areas are identified by the localized fine analysis.Both the cumulative effect and structural response cause the perforation of rear plate;in the non-perforated area,cratering by the impact of hazardous fragments is the main damage mode of the rear plate.

Vibration safety assessment and parameter analysis of buried oil pipelines based on vibration isolation holes under strong surface impact

Strong surface impact will produce strong vibration,which will pose a threat to the safety of nearby buried pipelines and other important lifeline projects.Based on the verified numerical method,a comprehensive numerical parameter analysis is conducted on the key influencing factors of the vibration isolation hole(VIH),which include hole diameter,hole net spacing,hole depth,hole number,hole arrangement,and soil parameters.The results indicate that a smaller ratio of net spacing to hole diameter,the deeper the hole,the multi-row hole,the hole adoption of staggered arrangements,and better site soil conditions can enhance the efficiency of the VIH barrier.The average maximum vibration reduction efficiency within the vibration isolation area can reach 42.2%.The vibration safety of adjacent oil pipelines during a dynamic compaction projection was evaluated according to existing standards,and the measurement of the VIH was recommended to reduce excessive vibration.The single-row vibration isolation scheme and three-row staggered arrangement with the same hole parameters are suggested according to different cases.The research findings can serve as a reference for the vibration safety analysis,assessment,and control of adjacent underground facilities under the influence of strong surface impact loads.

Research progress on the physiological,biochemical and molecular regulatory mechanisms of fruit tree responses to high-temperature stress

Fruit trees face various adverse environmental factors,such as extreme hydrothermal changes,soil salinization and low precipitation,leading to different types of stress.High temperature is one of the main factors affecting the growth of fruit trees,and an appropriate ambient temperature is a necessary condition for the normal growth and development of fruit trees.Since the 20th century,due to the intensification of the greenhouse effect and global warming,there has been a significant increase in the occurrence and duration of extreme hot weather in summer has been occurring frequently and for longer durations.Thus,the growth and production of fruit trees are affected by severe hightemperature stress.Therefore,this paper primarily summarized the impacts of high-temperature stress on fruit growth and development,flowering,fruiting,fruit setting and quality.It also discussed the physiological and biochemical responses of fruit trees to high-temperature stress,research progress on the molecular mechanisms and signal transduction pathways underlying fruit tree resistance to heat or high temperature,and research on the investigation of relevant metabolites of fruit trees under stress conditions.The future research directions were discussed,and prospects and potential difficulties were proposed to serve a reference for further investigation on the high-temperature tolerance of fruit trees.

Investigation of magnesium phosphate cement on river dredged sludge with varying humic acid content and solidification mechanism

This paper investigated the use of magnesium phosphate cement (MPC) for solidifying sludge with different humic acid (HA) content (ranging from 0 to 4.5%) and explored the solidification mechanism. Fluidity, setting time, unconfined compressive strength (UCS), the strength formation mechanism, and the spontaneous imbibition process of solidified sludge (SS) were studied. The results indicate that MPC can be used as a low-alkalinity curing agent. As the HA content increases, fluidity and setting time also increase, while hydration temperature and strength decrease. Additionally, the failure mode of SS transitions from brittleness to ductility. The strength of SS is composed of the cementation strength provided by MPC hydration products, matric suction, osmotic suction, and the structural strength of the sludge. MPC reduces the structural strength caused by the shrinkage of pure sludge under the action of matric suction, but the incorporation of MPC significantly improved the strength when the sludge is eroded by water. X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the sludge and MPC can form a dense solid body, forming various hydration products, and synergistically improve the mechanical properties of the sludge.

Using fracture mechanics method to analyze the failure mechanism and equilibrium equation of interfacial loess-mudstone landslides

Loess-mudstone landslides are common in the Loess Plateau.Investigations into the mechanical theory of loess-mudstone landslides have become a challenging undertaking due to the distinctive interfacial properties of loess-mudstone and the unique water sensitivity characteristics of mudstone.Hence,it is imperative to develop innovative mechanical models and mathematical equations specifically tailored to loess-mudstone landslides.In this study,we analyze the fracture mechanism of the loess-mudstone sliding zone using plastic fracture mechanics and develop a unique fracture yield model.To calculate the energy release rate during the expansion of the loess-mudstone interface tip region,the shear fracture energy G is applied,which reflects both the yield failure criterion and the fracture failure criterion.To better understand the instability mechanism of loess-mudstone landslides,equilibrium equations based on G are established for tractive,compressive,and tensile loess-mudstone landslides.Based on the equilibrium equation,the critical length Lc of the sliding zone can be used for the safety evaluation of loess-mudstone landslides.In this way,this study proposes a new method for determining the failure mechanism and equilibrium equation of loessmudstone landslides,which resolves their starting mechanism,mechanical equilibrium equations,and safety evaluation indicators,thus justifying the scientific significance and practical value of this research.

Impact and mechanism of bisphosphonate depressant 1-hydroxypropane-1,1-diphosphonic acid on flotation decalcification of dolomite-rich magnesite ore

Given the depletion of high-quality magnesite deposits and the rising demand for high-end magnesium materials,the separation and utilization of high-calcium magnesite ores have become essential.However,the similar surface properties and solubility of semi-soluble salt-type minerals,pose significant challenges for the utilization of dolomite-rich magnesite resources.In this study,1-hydroxypropane-1,1-di phosphonic acid(HPDP)was identified for the first time as a high-performance depressant for dolomite.Various tests,including contact angle measurements,ζ potential analysis,X-ray photoelectron spectroscopy,and atomic force microscopy,were conducted to elucidate the interfacial interaction mechanisms of HPDP on the surfaces of the two minerals at different scales.Additionally,molecular modeling calculations were used to detail the spatial matching relationship between HPDP and the crystal faces of the two minerals.It was emphasized that HPDP specifically adsorbed onto the dolomite surface by forming calcium phosphonate,ensuring that the dolomite surface remained hydrophilic and sank.Moreover,it was found that the adsorption strength of HPDP on the mineral surfaces depended on the activity of the metal sites and their spatial distribution.These findings provide a theoretical foundation for the molecular design of flotation reagents for high-calcium magnesite ores.

Enhanced damage mechanism of reinforced concrete targets impacted by reactive PELE: An analytical model and experimental validation

Compared with PELE with inert fillings such as polyethylene and nylon,reactive PELE(RPELE)shows excellent damage effects when impacting concrete targets due to the filling deflagration reaction.In present work,an analytical model describing the jacket deformation and concrete target damage impacted by RPELE was presented,in which the radial rarefaction and filling deflagration reaction were considered.The impact tests of RPELE on concrete target in the 592-1012 m/s were carried out to verify the analytical model.Based on the analytical model,the angle-length evolution mechanism of the jacket bending-curling deformation was revealed,and the concrete target damage was further analyzed.One can find out that the average prediction errors of the front crater,opening and back crater are 6.8%,8.5%and 7.1%,respectively.Moreover,the effects of radial rarefaction and deflagration were discussed.It was found that the neglect of radial rarefaction overestimates the jacket deformation and concrete target damage,while the deflagration reaction of filling increases the diameter of the front crater,opening and back crater by 25.4%,24.3%and 31.1%,respectively.The research provides a valuable reference for understanding and predicting the jacket deformation and concrete target damage impacted by RPELE.

Generation Mechanism and Social Impact of Knowledge in the Era of"New Quality Productivity"

The changes in knowledge forms in the era of"new quality productivity"are closely related to the development of society.With the rise of the Internet,"the world of dataism is coming".The traditional knowledge production model is undergoing fundamental changes in structure and nature.The most prominent change is that knowledge is becoming increasingly inseparable from data networks.The collaborative production of knowledge based on the Internet is becoming increasingly common,and Wikipedia is a prominent example of this.Wikipedia makes the networked production of knowledge possible by utilizing collective intelligence and data connectivity.Wiki users are commonly referred to as"wiki".This paper conducted interviews with 30 Wiki users and used content analysis to statistically analyze the interview records,in order to study the significance and value of the Wiki knowledge production model for online users,and to glimpse the impact of the knowledge structure changes in the era of"dataism"on social change.

Correction:Impact of Transition Metal Layer Vacancy on the Structure and Performance of P2 Type Layered Sodium Cathode Material

Following publication of the original article[1],the authors reported that the author Hun-Gi Jung should be affiliated as 3,4 and 5 instead of 4 and 5.The author’s name“A.-Yeon Kim”needed to be updated to“A-Yeon Kim”,removing the period.The correct author’s name and affiliation have been provided in this Correction.The original article[1]has been corrected.