Behavior Mechanism Research Articles

A Universal Interfacial Reconstruction Strategy Based on Converting Residual Alkali for Sodium Layered Oxide Cathodes: Marvelous Air Stability, Reversible Anion Redox, and Practical Full Cell.

Mn-based layered oxide cathodes have attracted widespread attention due to high capacity and low cost, however, poor air stability, irreversible phase transitions, and slow kinetics inhibit their practical application. Here, we propose a universal interfacial reconstruction strategy based on converting residual alkali to tunnel phase Na0.44MnO2 for addressing the above mentioned issue simultaneously, using O3 NaNi0.4Fe0.2Mn0.4O2@2 mol % Na0.44MnO2 (NaNFM@NMO) as the prototype material. The optimized material exhibits an initial capacity and energy density comparable with lithium-ion batteries. The reversible anionic redox behavior and charge compensation mechanism of NaNFM@NMO were analyzed and verified by soft X-ray absorption spectrum and in situ X-ray absorption spectrum. Due to the intrinsic stability of the tunnel structure, excellent air stability and highly reversible structure evolution of the NaNFM@NMO cathode material are achieved, which are confirmed by contact angle test, rigorous aging test, and in situ X-ray diffraction. More importantly, the NaNFM@NMO cathode demonstrates a great match with the nonpresodiated hard carbon anode and shows excellent electrochemical performance of the full cell. Additionally, such a strategy could be also applied to modify P2-type cathodes, showing superior universality and good prospects in industrialized production. Overall, the proposed strategy could improve air stability while remaining interfacial and bulk stable simultaneously and will open up a whole new field for the optimization of other electrode materials.

School Innovation Culture as Predictor of Teachers’ Research Competence

The study assessed the school innovation culture and teachers' research competence in selected higher education institutions in Hunan, China. It assessed the culture of school innovation using the sub-variables strategy, support mechanism, structure, and creative behavior. To assess research competence, the study used the sub-variables research methodology, ethics, and utilization of research. The study also determined the predictive role of innovation culture on teachers' research competence. The study involved 305 teacher respondents selected randomly from a total population of 1460 teachers. The researcher developed the instrument used for data gathering. It was validated, pilot tested, and showed acceptable reliability results. The findings revealed a weak innovation culture in the schools investigated. The respondents assessed innovation culture as weak in all its sub-variables. It implies a lack of organized effort to foster an innovation culture in the investigated schools. The findings also showed poor research competence among the respondents. They have poor competence in research methodology, ethics, and utilization. Based on the results of the multiple linear regression analysis, the study concluded that school innovation culture has a predictive influence on teachers' research competence. This implies that a weak school innovation culture has a negative impact on the research competence of teachers. The study highlights the need to strengthen innovation culture to increase school research productivity.

WASTE EGGSHELL AND SAWDUST AS REINFORCEMENTS FOR SUSTAINABLE POLYESTER COMPOSITES: MECHANICAL CHARACTERIZATION AND ENVIRONMENTAL DURABILITY ASSESSMENT

This research endeavor undertakes an experimental investigation into the bending and tensile properties of polyester composites reinforced with waste eggshell powder and sawdust particles at 35 wt.%. Valorizing these waste materials as reinforcements contributes to sustainable practices, waste minimization, and environmental pollution mitigation. Composite samples were fabricated using hand lay-up and compression molding techniques. The effects of environmental exposure to water, acidic, and basic media immersion on the mechanical performance were evaluated to assess durability. Experimental characterization through tensile and three-point bending tests determined mechanical properties, stress-strain behavior, and failure mechanisms. Additionally, finite element analysis (FEA) simulations complemented the experiments by providing insights into stress distributions, deformations, and potential failure initiation sites within the composites under flexural loading. The computational models accurately captured the reinforcing effects of the waste materials and the degradation induced by environmental exposure, validating the experimental trends. Incorporating waste natural fibers significantly enhanced polyester's bending strength by 140% (sawdust) and 75% (eggshell), and tensile strength by 13% (sawdust) and 10% (eggshell). However, environmental exposure degraded properties to varying extents, with water immersion reducing tensile strength by 63% (sawdust) and 3% (eggshell), and flexural strength by 63% (sawdust) and 3% (eggshell). The acidic medium caused 58% (sawdust) and 23% (eggshell) reductions in tensile strength, and similar flexural strength degradations. Strikingly, the basic medium decreased eggshell composite tensile strength by 170% and flexural strength by 6%, while sawdust composite strengths declined by 44%.

Static Recrystallization Behavior and Twin Formation Mechanism of Fe–Mn–Cr–N Steel During Medium Temperature Annealing

Static Recrystallization Behavior and Twin Formation Mechanism of Fe–Mn–Cr–N Steel During Medium Temperature Annealing

Vehicle-To-Grid (V2G) Charging and Discharging Strategies of an Integrated Supply–Demand Mechanism and User Behavior: A Recurrent Proximal Policy Optimization Approach

With the increasing global demand for renewable energy and heightened environmental awareness, electric vehicles (EVs) are rapidly becoming a popular clean and efficient mode of transportation. However, the widespread adoption of EVs has presented several challenges, such as the lagging development of charging infrastructure, the impact on the power grid, and the dynamic changes in user charging behavior. To address these issues, this paper first proposes a vehicle-to-grid (V2G) optimization framework that responds to regional dynamic pricing. It also considers power balancing in charging and discharging stations when a large number of EVs are involved in scheduling, with the aim of maximizing the benefits for EV owners. Next, by leveraging the interaction between environmental states and the dynamic behavior of EVs, we design an optimization algorithm that combines the recurrent proximal policy optimization (RPPO) algorithm and long short-term memory (LSTM) networks. This approach enhances system convergence and improves grid stability while maximizing benefits for EV owners. Finally, a simulation platform is used to validate the practical application of the RPPO algorithm in optimizing V2G and grid-to-vehicle (G2V) charging strategies, providing significant theoretical foundations and technical support for the development of smart grids and sustainable transportation systems.

Understanding Electric Current Effects on Tribological Behaviors of Instantaneous Current-Carrying Pair With Recurrence Plot

Abstract Armature–rail instantaneous current-carrying friction in electromagnetic launchers refers to a sliding electric-mechanical impact friction and transition-induced arc erosion on a millisecond time scale. To reveal the electric current (50–300 A) effects on friction behavior and wear mechanism, the instantaneous current-carrying friction tests were performed with Al 1060 and Brass H62. Given the short nonlinear friction-induced signals, the friction behavior, including the time-domain information and system state, was comprehensively analyzed via frictional sound pressure (FSP), recurrence plot (RP), and recurrence quantification analysis (RQA). The wear topography was observed and characterized by the multifractal spectrum. Recurrence analyses demonstrate that as the current increases, the nonstationarity of the system state weakens, and the complexity and unpredictability enhance. Higher currents reduce the FSP amplitude, i.e., enhance the interfacial lubrication effect, but intensify electrical wear and surface roughness. This signifies a wear mechanism transition from abrasive wear and slight adhesive wear to arc ablation, fatigue wear, and severe adhesive wear. The widening spectrum width implies that the irregularity and fluctuation of the topography are enhanced with the current. RP patterns and RQA quantifiers correlate with the wear damage state. The results provide a reference for antiwear design and online degradation tracking of the rail.

A synthetic study of cracking behavior and fracture mechanism of sandstone containing two non-connected fissures under uniaxial compression

A synthetic study of cracking behavior and fracture mechanism of sandstone containing two non-connected fissures under uniaxial compression

Integration of electric vehicles in smart grids: Challenges and opportunities in achieving carbon neutrality goals

Abstract. The integration of electric vehicles (EVs) into smart grids represents a pivotal shift towards sustainable transportation, offering substantial environmental benefits and new challenges for grid stability and energy management. This paper proposes a dual-layer economic dispatch model emphasizing source-load collaboration for carbon reduction, utilizing carbon trading mechanisms and demand response strategies to enhance grid stability and carbon efficiency. The Vehicle-to-Grid (V2G) technology emerges as a key solution, enabling EVs to contribute to grid reliability and facilitating renewable energy integration. Through analysis of EV charging behavior and demand response mechanisms, the study underscores the critical role of EVs in achieving carbon neutrality goals and the necessity of innovative solutions to integrate EVs seamlessly into the grid. This research highlights the importance of collaborative efforts among policymakers, utilities, and stakeholders to address the challenges and seize the opportunities presented by EV integration, paving the way for a low-carbon energy future.

Exploring the influence of metal oxides on the pyrolytic behavior and decomposition mechanism of the green gas generating agent 5-Aminotetrazole

5-Aminotetrazole (5AT) is widely used as a green gas-generating agent in fire extinguishers, but it exhibits low combustion stability. To enhance its combustion rate and modify gas production performance, this study investigated the catalytic effects of adding different metal oxides (Bi2O3, PbO, TiO2, and CoO) on its pyrolysis process and decomposition mechanism. The pyrolysis behavior and pyrolysis products of 5AT were studied by simultaneous thermal analyzer (thermogravimetry - differential thermal analysis, TG-DTA) and TG-FTIR/MS (mass spectrometry and fourier transform infrared spectroscopy) hyphenated instrument. Isoconversional methods were used to calculated kinetic parameters, and reaction mechanism was also speculated by combining the experimental and calculational results. The experimental results indicated that Bi2O3, PbO, TiO2 and CoO have minimal impact on the ring opening reaction process of 5AT, but they catalyzed the polymer decomposition process of 5AT, especially CoO. Consequently, the addition of metal oxides as catalysts to 5AT holds significant potential for improving its thermal safety and enhancing its suitability as a solid propellant gas generator.

A magnetic epitope-imprinted microsphere used for selective separation and rapid detection of SHV-type β-lactamases in bacteria: a novel strategy of antimicrobial resistance detection

BackgroundThe production of β-lactamases is the most prevalent resistance mechanism for β-lactam antibiotics in Gram-negative bacteria. Presently, over 4900 β-lactamases have been discovered, and they are categorized into hundreds of families. In each enzyme family, amino acid substitutions result in subtle changes to enzyme hydrolysis profiles; in contrast, certain conserved sequences retained by all of the family members can serve as important markers for enzyme family identification.ResultsThe SHV family was chosen as the study object. First, a unique 10-mer peptide was identified as SHV family's epitope by an approach of protein fingerprint analysis. Then, an SHV-specific magnetic epitope-imprinted gel polymer (MEI-GP) was prepared by an epitope surface imprinting technique, and its sorption behavior and recognition mechanism for template epitope and SHV were both elaborated. Finally, the MEI-GP was successfully applied to selectively extract SHV from bacteria, and the extracted SHV was submitted to MALDI-TOF MS for specific determination. By following this strategy, other β-lactamase families can also be specifically detected. According to the molecular weight displayed in mass spectra, the kind of β-lactamase and its associated hydrolysis profile on β-lactams can be easily identified. Based on this, an initial drug option scheme can be quickly formulated for antimicrobial therapy. From protein extraction to medication guidance reporting, the mean time to detection (MTTD) was less than 2 h, which is much faster than conventional phenotype-based methods (at least 16–20 h) and gene-based techniques (usually about 8 h).ConclusionsThis enzyme-specific detection strategy combined the specificity of epitope imprinting with the sensitivity of mass spectrometry, enabling β-lactamase to be selectively extracted from bacteria and clearly presented in mass spectra. Compared with other drug resistance detection methods, this technique has good specificity, high sensitivity (≤ 15 mg of bacteria), a short MTTD (less than 2 h), and simple operation, and therefore has a broad application prospect in clinical medicine.Graphical

Investigation of Ductility and Damage Behavior of C/GFRP Composite Laminates under Bending Loads

Carbon and glass fabric reinforced polymer (C/GFRP) composites are extensively used in aerospace and sports industry because of their exceptional properties. However, during service, static and dynamic bending loads can ensue damage in composites affecting their strength, stiffness and energy absorption. Carbon fiber composites, being inherently brittle, are prone to sudden catastrophic fracture without ductile-like behavior of metals. This study investigates mechanical behavior and damage mechanisms of woven C/GFRP composites in on- and off-axis orientations during bending. Initially, bending tests with quasi-static loading were performed, followed by dynamic ones using an Izod impact testing apparatus. Results showed distinct behavior in on-axis CFRP laminates with brittle fracture. Off-axis CFRP samples and both on- and off-axis GFRP laminates showed signs of damage and non-linear behavior, yet they retained their ability to bear loads. Significantly, off-axis specimens of both types and on-axis GFRP laminates exhibited enhanced energy absorption capabilities without experiencing fracture, undergoing pseudo-ductile deformation. CFRP specimens were analyzed with micro-computed tomography (micro-CT), provided insights into prevalent damage modes such as matrix mircocracking, debonding of tows, delamination and breakage of fabric. While on-axis CFRP laminates experienced brittle fracture, off-axis specimens exhibited a ductile-like response attributed to matrix plasticity, cracking and fiber trellising before eventual failure.

Pull-out behavior and failure mechanism of steel expansion anchors in high-performance steel fiber reinforced concrete(HPSFRC)

Past research on the pull-out performance of anchors mainly focuses on normal concrete(NC) concretes. New design methods are needed for the pull-out performance of anchors in the concretes of new cementitious materials with high strength and toughness. Accordingly, the pull-out behavior of torque-controlled expansion anchor(TCE) in high-performance steel fiber reinforced concrete(HPSFRC) concrete with different fiber content and installation conditions(embedment depth and anchor diameter) was investigated. The focus was on the failure modes, crack morphology, and load-displacement behavior(including pull-out load-bearing capacity, anchorage stiffness, and anchorage toughness). The addition of fibers leads to increased load-bearing capacity and toughness, reduced stiffness, and all failure modes exhibited ductile cracking and sufficient tensile ductility. Both diameter and depth had a positive impact on load-bearing capacity. A broader database based on literature and this study was analyzed for further exploration of the effects of fibers. The accuracy of predicting load-bearing capacity was compared between two empirical models(concrete capacity design-CCD and Toth models) and the proposed modified model. The CCD model greatly underestimates capacity, and the Toth model is unsuitable for high fiber content(exceeds 2.0 %) HPSFRC scenarios. The modified model showed the best bearing capacity prediction for anchors on HPSFRC concretes, with a mean ratio of predicted values to experimental values reaching 1.01–1.08 and a coefficient of dispersion below 15.0 %.

Multi-energy Field-Assisted Water Jet Strengthening 2519a Dynamic Impact Behavior and High Cycle Fatigue Enhancement Mechanism

Multi-energy Field-Assisted Water Jet Strengthening 2519a Dynamic Impact Behavior and High Cycle Fatigue Enhancement Mechanism

Enhancing the emulsification performance of hempseed protein hydrolysate through the incorporation of sugar beet pectin: Role of interaction mechanism and interfacial behavior

Enhancing the emulsification performance of hempseed protein hydrolysate through the incorporation of sugar beet pectin: Role of interaction mechanism and interfacial behavior

Low cycle fatigue behavior and deformation mechanism of Ti–6Al–4V-0.55Fe alloy under the control of strain and stress amplitudes

Low cycle fatigue behavior and deformation mechanism of Ti–6Al–4V-0.55Fe alloy under the control of strain and stress amplitudes

Effect of strain amplitude on the low cycle fatigue behavior and deformation mechanisms in alloy SU-263 at elevated temperature

The past studies in the low cycle fatigue (LCF) behavior of a γ′ strengthened nickel-based superalloy SU-263 were restricted to a maximum temperature of 923 K, though their service conditions far exceed this limit. In the present work, the LCF behavior of SU-263 is investigated at 1023 K with strain amplitude varying from ± 0.3% to ± 0.8% at 1023 K. During fatigue, the alloy displayed initial cyclic hardening followed by softening. The fatigue life decreased drastically with increasing strain amplitude. The alloy depicted gradual initial hardening at low strain amplitudes and sharp initial hardening at higher strain amplitudes, along with extensive softening until fracture. Significant increases in slip band density, stacking faults, dislocation network formation, and dislocation-dislocation and dislocation-precipitate interactions were identified as the deformation mechanisms responsible for cyclic hardening. In contrast, dislocation annihilation and shearing of γ′ precipitates were found to control cyclic softening. Dislocation-precipitate interactions were associated with looping at low strain amplitudes, while precipitate shearing occurred at high strain amplitudes. The alloy exhibited a tendency bilinear strain-life behavior in the Coffin-Manson plot with the corresponding shift in the fracture mode at ± 0.5% strain amplitude. At strain amplitudes below ± 0.5%, the alloy showed a mixed mode of failure, predominantly transgranular in nature, while at high strain amplitudes, the failure becomes predominantly intergranular.

Thermal decomposition behavior and kinetic mechanism of waste phosphors during sodium hydroxide roasting

Waste phosphors are critical rare earth secondary resources, and their recycling can help alleviate the depletion of rare earth mineral resources. However, stable Al–Mg spinel structures exist in waste phosphors. The direct acid leaching method remains difficult to use for leaching cerium and terbium. In this paper, the waste phosphors were first pretreated via alkali roasting. NaOH was used as an alkali roasting agent, thus achieving the decomposition of the Al–Mg spinel structure. On the basis of thermodynamic calculations, thermal decomposition experiments were performed. The results showed that when the temperature was greater than 500°C, the waste phosphors could be decomposed into MgO, Eu2O3, Y2O3, CeO2, Tb4O7, NaAlO2, and BaO. The Ce3+ and Tb3+ in the waste phosphors were partially oxidized to Ce4+ and Tb4+, respectively, during the roasting process. The BET surface area and the average pore diameter for the roasted products also increased. Under the conditions of roasting temperature at 900°C, NaOH/sample mass ratio of 2.5, and roasting time of 150min, the leaching efficiencies of Y, Eu, Ce, and Tb could reach 99.4%, 99.1%, 98.5%, and 98.8%. The decomposition process of waste phosphors conformed to the unreacted shrinking core model. In addition, the conversion processes of Ce and Tb depended on the chemical reaction. The results may provide a new direction of development for the resource utilization of waste phosphors.

Drainage behavior and entrainment mechanisms in oil mist separation applications—A review

Drainage behavior and entrainment mechanisms in oil mist separation applications—A review

Molecular dynamics study on the mechanical behavior and deformation mechanism of gradient oxygen content nano-polycrystalline α-T

Molecular dynamics study on the mechanical behavior and deformation mechanism of gradient oxygen content nano-polycrystalline α-T

Fabrication and characterization of SiC-reinforced magnesium-matrix composites with honeycomb structures and anisotropic properties

This study presents a novel approach for fabricating SiC-reinforced magnesium matrix composites by combining digital light processing (DLP) with pressureless infiltration. Pre-oxidation of SiC powder enhanced its wettability with the magnesium alloy, enabling the near-net-shape fabrication of honeycomb Mg-based composites with precisely controlled SiC and Al2O3 powder ratios. The influence of varying ceramic content on the microstructure and compressive properties of the composites was investigated, revealing significant mechanical anisotropy. A combined approach utilizing fracture morphology analysis and finite element simulations elucidated the compressive behavior and failure mechanisms of the composites under different loading directions. This work not only offers a promising route for on-demand design and fabrication of Mg-based composites but also provides valuable insights into understanding the mechanical behavior of architected composites.