Mechanics Of Formation Research Articles

A Dynamic Volumetric Heat Source Model for Laser Additive Manufacturing

Melt pool scale models of laser powder bed fusion (LPBF) offer insights into the process-structure-property relationships in additive manufacturing (AM). These models often neglect physical phenomena such as vapor cavity formation and fluid mechanics to reduce computational demands. Instead, volumetric heat source models are used to represent the effects that these phenomena have on the predicted melt pool dimensions. Generally, the dimensions and effective absorption of the volumetric heat source are calibrated to reproduce melt pool dimensions observed in metallographic cross sections taken from single-track experiments on bare plate. However, the transient nature of LPBF often deviates the melt pool dimensions from the assumed steady-state conditions of single-track experiments, motivating the need for a volumetric heat source model that more generally considers the dynamic relationship between melt pool shape and laser-material interactions. Here, we introduce a two-parameter volumetric heat source model that integrates several existing models into a generalized mathematical expression, providing independent control over the radial heat distribution via the parameter k and the volumetric shape of the heat source via the parameter m. This parameterization enables the calibration of melt pool shape predictions through simultaneous adjustment of these parameters, while keeping the radial heat source dimensions consistent with the experimental spot size (D4σ) and constraining the heat source depth and absorption to physically derived expressions for cavities. Consequently, the proposed volumetric heat source model adapts to changes in the local melt pool conditions due to scanning strategy and part geometry by dynamically adjusting the heat source depth and absorption. We demonstrate the capabilities of the proposed model through comparisons with a collection of experiments from the Additive Manufacturing Benchmark (AMBench).

Activation patterns of intracellular signaling pathways in cardiac hypertrophy induced by different exercise modes in rats

Abstract Introduction Cardiac remodeling and hypertrophy cause as adaptive responses to physiological and pathological stimuli. Physiological cardiac hypertrophy is characterized by normal or enhanced cardiac function and myocardial metabolism, and induces concentric and eccentric hypertrophy by different exercise modes, without cardiac dysfunction and fibrosis. Each formative mechanism of cardiac hypertrophy is regulated by distinct and/or similar cellular signaling pathways. Activation of cardiac intracellular signaling pathway of phosphoinositide 3- kinase (PI3K) is involved in an underlying mechanism of developed eccentric cardiac hypertrophy by aerobic exercise training (AT). However, the activation patterns of intracellular signaling pathways of physiological cardiac hypertrophy by different exercise modes remain unclear. Purpose The purpose of this study was to investigate the activation patterns of intracellular signaling pathways in cardiac hypertrophy induced by different exercise modes, including AT, resistance training (RT), and high intensity interval training (HIIT). Methods Forty male 10-week-old Sprague-Dawley (SD) rats were divided into four groups; sedentary control (Con, n=10), AT (treadmill running, 60 min at 30 m/min, 5 days/wk for 8 wk, n=10), RT (ladder climbing, 8-10 sets/day, 3 d/wk for 8 wk, n=10), HIIT (14 repeats of 20-s swimming session with 10-s pause between sessions, 4 d/wk for 6 wk from 12-wk-old, n=10) groups. As a cardiac hypertrophic intracellular signaling pathways, PI3K protein expression level and mTOR and MAPK (ERK1/2, JNK1/2 and p38) phosphorylation levels in rat hearts were measured by Western blotting analysis. Results The hearts of rats in each training group developed cardiac hypertrophy. Moreover, the enzyme activity of oxidative phosphorylation in the skeletal muscle was promoted in the AT group, the oxidative phosphorylation and glycolytic enzyme activities were promoted in the HIIT group, and muscle hypertrophy occurred in the RT group. Levels of PI3K protein expression and mTOR phosphorylation in the heart were significantly higher in the AT, RT, and HIIT groups as compared to the Con group (each p<0.05). Additionally, p38 phosphorylation level in the heart was significantly higher in the RT group as compared to the Con, AT, and HIIT groups (each p<0.05). Furthermore, p44 ERK phosphorylation level in the heart of the RT group was significantly higher than that in the AT and HIIT groups (each p<0.05), but p42 ERK phosphorylation level did not differ among four groups. JNK1/2 (p46/p54) phosphorylation level in the heart was significantly higher in the RT group as compared to the Con group (p<0.05). Conclusion These findings suggest that the activation of PI3K-mTOR signaling pathway in the heart may be involved in the development of AT, RT and HIIT-induced cardiac hypertrophy, and the MAPK signaling activation may affect the development of cardiac hypertrophy by RT.

Chinese Accounting Standards Convergence with International Financial Reporting Standards

As the global economy becomes more integrated, Chinese Accounting Standards (CAS) are gradually moving towards convergence with International Financial Reporting Standards (IFRS). So far, CAS and IFRS do still have a number of variations including content, format and setup mechanisms. This paper analyzes three main differences in the content between CAS and IFRS regarding the financial instrument, biological asset, and lease measurement. These differences may cause problems for international practitioners and investors. In addition, the paper discusses the influences of the global convergence of CAS and the challenges faced by the technology industry, listed companies, and government. It is recommended that China need to consider the domestic economic situation and policies when adopting IFRS, and properly adjust the content of the standard accordingly, so as to better meet the domestic needs and development prospects. And industries should balance convergence and market challenges and work together to shape a practical and comprehensive China accounting system to enable China to develop globally further.

Implications of soil waterlogging for crop quality: A meta-analysis

Soil waterlogging in many arable regions of the world challenge the quantum and quality of crop production. While previous studies have assessed the impact of waterlogging on crop yields, understanding of how waterlogging implicates with crop quality remains in its infancy. Here, we conduct a systematic literature review and meta-analysis to assess how waterlogging influences grain quality. We also explore the role of engineering and agronomic strategies for alleviating adverse effects of waterlogging. We reveal that soil waterlogging has less impacts on grain quality than on yield; the latter decreasing by an average of 23 %, while average grain protein and starch content of waterlogged crops reduced by 6.7 % and 7.3 %, respectively. We attribute these differences to underlying mechanics of yield and grain quality formation, as well as biological processes conferring adaptation, plasticity and recovery. Reduced grain quality under waterlogging is associated with decreased activity of enzymes involved in leaf nitrogen and carbon metabolism. Unlike yields however, grain quality suffers less deterioration with prolonged waterlogging, with ultimate effects realized being a function of species-specific tolerance, timing and duration of waterlogging relative to crop stage, soil type and growing season weather. We underscore the potential in engineering and/or agronomic interventions for alleviating detrimental effects of waterlogging.

Features of Forming the Legal Consciousness in the Modern Settings and Its Influence on the State of Lawfulness

Introduction. The Constitution of the Russian Federation defines the benchmarks ensuring an appropriate level of development for the important spheres of life, a high living standard, which requires a comprehensive approach to forming the human potential of the generations of the Russian citizens. The quintessence of the Russian statehood strategic development implies minimisation of the prerequisites inducing formation of the destructive legal consciousness in citizens, which obstructs achievement of the legal order in the country. In the National Security Strategy of the Russian Federation, among the list of national interests, a significant place is allocated to saving the people of Russia, to development of the human potential. The state strategic planning document had defined the following goals: upbringing a harmoniously developed and socially responsible citizen, forming in the society the attitude of intolerance to illegal activities. No doubt, in Russia, the trend of the power exercising mechanism to undergo modern institutional changes is caused by the social modernization and is targeted at the conceptual ideas of the constitutionalism. The economic and socio-political transformations inevitably affect not only formation of the legal environment, but also structuring the public consciousness, which concepts predetermine the development of the reasoned and practically oriented legal solutions. The state of the public perception of the legal phenomena should be constantly monitored due to the continuous impact imposed on it by the transformations in the state structure of the governmental and administrative authorities. The scientific understanding of these processes should not be underestimated, otherwise this can cause the psychological turbulence of a significant part of the population in choosing the behavioural patterns of lawful behaviour. In the context of transformation of the social determination process, which is attributed with a complicated range of the antisocially-motivated impacts, significantly limiting the preventive social and law enforcement potential, the present research is relevant due to the special importance assigned to precise, steady and uniform application of the legislative provisions, the degree of their functional social harmonisation in the social relation regulation mechanism. The deformations of the citizens’ legal consciousness are the factors hindering the achievement of the high efficiency in implementation of the fundamental principles of the supremacy of law. The research aims at investigating the functional role of the legal consciousness in the legal regulation mechanism of the modern social formations, at analysing the problems of exercising the state policy in the frame of forming the positive perception of the legal phenomena among the citizens and revealing the interrelations of the legal consciousness deformations and stimulation of the legitimate behavioural variation.Materials and Methods. The article analyses the results of the research of the native and foreign scientists on the regularities in the public perception of the state and legal phenomena and impact thereof on the legitimate behavioural variation. The general scientific and specific scientific methods were used in the research, such as the statistical method and the method of system analysis of data characteristic of the phenomena affecting the state of lawfulness in Russia.Results. The regularities in the functional role of the legal consciousness within the mechanism of legal regulation of the social relations have been acknowledged. The substance of the legal consciousness interrelations with the legal ideology and legal psychology has been revealed. The problems of efficiency of the state policy in forming the civil legal consciousness have been determined. It has been proposed to integrate into the scholarly discourse such a type of legal consciousness deformation as legal dementia, which predetermines the state of lawfulness in the modern Russian society.Discussion and Conclusion. The practical side of the legal consciousness reflects the behavioural attitudes of a person, his readiness to use in practice his theoretical knowledge and value assessments. The law-related feelings, emotions, ideas, principles, attitudes that have become a part of a person’s legal consciousness, subsequently determine his actions in the legal framework. To ensure protection of the national mental values and to prevent emergence of the destructive attitudes in the society, changes in the educational, scientific, cultural and other spheres should be made taking into account the historical traditions and the experience accumulated by the Russian society. Unfortunately, nowadays, among the main problems of the lawmaking and law enforcement processes in Russia are weak scientific and analytical justification of the draft laws, low quality of laws, acute legal collisions within the law system, violations of the intra-system relations that result in a tendency of citizens’ legal estrangement.

Synergetic Vectors of Development of Individual Forensic Theories in the context of Modern Criminal Proceedings (a Preliminary Aspect)

A rapidly developing society determines the need to adjust well-established approaches to understanding and regulating crime prevention mechanisms. It should be noted that the modern criminal policy of the state is on the verge of systemic changes. Balance of public and private interests; authority and independence of subjects of criminal proceedings; means of combating crime and social control; public and secret methods of exposing criminals; conflict and compromise; defense and prosecution; complex and simplified procedural forms of legal proceedings; inevitability of criminal prosecution and conciliation procedures; verbal and digital technologies in legal proceedings; professional skills and technical means — these are the few systemic formations, the content of which requires a modern rethinking with dew regard to prevailing realities of the functioning of society. And here the key supporting role in the formation of effective technologies for solving the problems of modern criminal proceedings, as a mechanism of complex systemic formations operating in the context of multifactorial law enforcement practice, belongs to criminalistic science. At the same time, an important tool in understanding and modeling promising vectors of the development of a system of private forensic theories is the synergetic approach, which significantly complements the wellestablished structural and systemic method in scientific knowledge. The use of the synergetics methodology makes it possible to identify not only the intrastructural connections of the system of forensic knowledge, but also to assess how such a system as a whole is affected by external (legal, ideological, etc.) factors. And the most important thing is to ensure the harmonious (regarding the changing realities of law enforcement practice) progressive development of individual private forensic theories.

Water-gas shift activity of atomically embedded transition-metals on AlN support: A DFT investigation

Single-Atom Catalysts (SACs) have piqued the interest of the global research community due to their remarkable catalytic activity in some key industrial chemical reactions. Herein, the catalytic efficacy of transition metals (TMs) embedded AlN (M@AlN; M = Ni, Pd, Pt, Cu, Ag, Au) are examined towards water–gas shift (WGS) reaction by employing first-principles-based, spin-polarized, van der Waals corrected, density functional theory (DFT) calculations. The strong interactions between M-atoms and AlN substrate (at Al-d site) and the higher diffusion barrier of M-atoms over AlN specifies the steadfast-stability of M@AlN. Further, the abstemious interplay between reactants (CO, OH, H2O, CO + OH and CO + H2O) corroborates the potency of M@AlN in harbouring the reactants. Then, to contemplate the activity of M@AlN towards WGS reaction, a well-established formate mechanism and a fairly novel OH-assistive mechanism, were considered. Predominantly, the OH-assistive mechanism determined to be more favourable than the formate mechanism. Precisely, the Au@AlN and Cu@AlN systems are deemed as most active and competent SACs for WGS reaction via OH-assistive mechanism with the required activation energy (Ea) of rate determining step (RDS) reckoned to be 0.14 eV and 0.21 eV, respectively. Moreover, the linearity of Ea with co-adsorption energy of CO–OH molecules (Eads(CO + OH)) and d-band centre (εd) substantiate the findings. Also, the comparison between Ea and reaction energy (ER) certifies the workability of Au/Cu@AlN towards WGS reaction. Wherefore, the investigation under discussion connotes Au/Cu@AlN can be a cogent, practicably applicable SACs for WGS reaction.

Inquiry into Teaching Listening and Speaking in High School English Classes Based on an Activity Perspective

This paper conducts an in-depth analysis of the issues present in current high school English listening and speaking classes and proposes corresponding improvements. Firstly, it identifies the challenges faced by high school English listening and speaking instruction, including inadequate emphasis on training listening and speaking skills by teachers, lack of operational and measurable course objectives, monotonous forms of activity organization, limitations in the use of listening materials and tools, weak connections between introductory segments and thematic content, failure to understand listening and speaking discourse based on thematic significance, neglect of teaching learning strategies, absence of learning activities in authentic contexts, and singular evaluation methods. Subsequently, a series of suggestions for enhancing teaching quality and efficiency are put forward, such as designing instruction around thematic contexts that integrate listening, speaking, reading, viewing, and writing skills; fostering the development of students’ core competencies, particularly language ability and cultural awareness; conducting comprehensive, interconnected, and practical learning activities; utilizing modern information technology to create a culturally rich learning environment; and implementing formative and multifaceted evaluation mechanisms. These improvement measures aim to enhance students’ listening and speaking abilities and cultivate them as lifelong learners with good listening and speaking habits.

Bridging scales in multiscale bubble growth dynamics with correlated fluctuations using neural operator learning

The intricate process of bubble growth dynamics involves a broad spectrum of physical phenomena from microscale mechanics of bubble formation to macroscale interplay between bubbles and surrounding thermo-hydrodynamics. Traditional bubble dynamics models including atomistic approaches and continuum-based methods segment the bubble dynamics into distinct scale-specific models. To bridge the gap between microscale stochastic fluid models and continuum-based fluid models for bubble dynamics, we develop a composite neural operator model to unify the analysis of nonlinear bubble dynamics across microscale and macroscale regimes by integrating a many-body dissipative particle dynamics (mDPD) model with a continuum-based Rayleigh–Plesset (RP) model through a novel neural network architecture, which consists of a deep operator network for learning the mean behavior of bubble growth subject to pressure variations and a long short-term memory network for learning the statistical features of correlated fluctuations in microscale bubble dynamics. Training and testing data are generated by conducting mDPD and RP simulations for nonlinear bubble dynamics with initial bubble radii ranging from 0.1 to 1.5 micrometers. The results show that the trained composite neural operator model can accurately predict bubble dynamics across scales, with a 99% predictive accuracy for the time evolution of the bubble radius under varying external pressure while containing correct size-dependent stochastic fluctuations in microscale bubble growth dynamics. The composite neural operator is the first deep learning surrogate for multiscale bubble growth dynamics that can capture correct stochastic fluctuations in microscopic fluid phenomena, which sets a new direction for future research in multiscale fluid dynamics modeling.

Pt and Mo2C nanoparticles embedded in hollow carbon nanofibers as an effective electrocatalyst for hydrogen evolution reaction in acidic and alkaline electrolytes

Efficient catalysts for water electrolysis are essential for the advancement of hydrogen energy, aiding in carbon neutrality. Herein, a novel Pt and Mo2C embedded in hollow carbon nanofibers (referred to as Pt/Mo2C-HCNFs) electrocatalyst is devised and manufactured by coaxial electrostatic spinning and subsequent carbonization process in this work. Molybdenum carbide (Mo2C) and Pt share similar electronic structures, Mo2C is thought to be a possible alternative to Pt in hydrogen evolution reaction (HER). The synergistic interaction between Pt nanoparticles (NPs) and Mo2C NPs, the abundance of active sites, the hollow structure, the exceptional conductivity of carbon nanofibers, and the suppression of nanoparticle agglomeration by carbon nanofibers jointly make Pt/Mo2C-HCNFs exhibit excellent HER performances in both acidic and alkaline electrolytes. At a current density of 10 mA cm−2, the overpotentials of Pt/Mo2C-HCNFs in acidic and alkaline electrolytes are respectively 27 and 41 mV, demonstrating superior HER performance compared to commercial 20 wt% Pt/C. Electrocatalytic mechanisms are reasonably advanced. The formative mechanisms of the Pt/Mo2C-HCNFs are proposed, and corresponding technology is founded. This work offers a novel approach for synthesizing simple, efficient, and cost-effective Pt-based electrocatalysts.

Intermittent cyclic stretch of engineered ligaments drives hierarchical collagen fiber maturation in a dose- and organizational-dependent manner

Hierarchical collagen fibers are the primary source of strength in tendons and ligaments; however, these fibers largely do not regenerate after injury or with repair, resulting in limited treatment options. We previously developed a static culture system that guides ACL fibroblasts to produce native-sized fibers and early fascicles by 6 weeks. These constructs are promising ligament replacements, but further maturation is needed. Mechanical cues are critical for development in vivo and in engineered tissues; however, the effect on larger fiber and fascicle formation is largely unknown. Our objective was to investigate whether intermittent cyclic stretch, mimicking rapid muscle activity, drives further maturation in our system to create stronger engineered replacements and to explore whether cyclic loading has differential effects on cells at different degrees of collagen organization to better inform engineered tissue maturation protocols. Constructs were loaded with an established intermittent cyclic loading regime at 5 or 10 % strain for up to 6 weeks and compared to static controls. Cyclic loading drove cells to increase hierarchical collagen organization, collagen crimp, and tissue tensile properties, ultimately producing constructs that matched or exceeded immature ACL properties. Further, the effect of loading on cells varied depending on degree of organization. Specifically, 10 % load drove early improvements in tensile properties and composition, while 5 % load was more beneficial later in culture, suggesting a shift in mechanotransduction. This study provides new insight into how cyclic loading affects cell-driven hierarchical fiber formation and maturation, which will help to develop better rehabilitation protocols and engineer stronger replacements. Statement of significanceCollagen fibers are the primary source of strength and function in tendons and ligaments throughout the body. These fibers have limited regenerate after injury, with repair, and in engineered replacements, reducing treatment options. Cyclic load has been shown to improve fibril level alignment, but its effect at the larger fiber and fascicle length-scale is largely unknown. Here, we demonstrate intermittent cyclic loading increases cell-driven hierarchical fiber formation and tissue mechanics, producing engineered replacements with similar organization and mechanics as immature ACLs. This study provides new insight into how cyclic loading affects cell-driven fiber maturation. A better understanding of how mechanical cues regulate fiber formation will help to develop better engineered replacements and rehabilitation protocols to drive repair after injury.

Don’t squeeze me! Exploring the mechanisms and boundary conditions between social crowding and uncivilised tourist behaviour

ABSTRACT Many studies have revealed that social crowding may adversely affect tourists. However, the mechanisms by which social crowding negatively affects the psychology and behaviour of tourists, especially those in natural area destinations, and strategies for mitigating these impacts remain unclear. To address these issues, a mixed method approach was employed, consisting of two studies. Study 1 conducted semi-structured interviews and thematic analysis to identify the critical variables and their potential relations. The results showed that social crowding can stimulate negative tourists’ psychological and behavioural responses. Tourists’ moral identity may also be a boundary factor. To verify the relationship between the variables, study 2 used a survey to explore the formative mechanism and boundary conditions of social crowding on uncivilised tourist behaviour. The empirical findings indicated that: (1) social crowding significantly influences uncivilised tourist behaviour; (2) negative emotions play a partial mediating role in uncivilised tourist behaviour; (3) moral identity negatively moderates the impact of negative emotions towards uncivilised tourist behaviour; (4) the indirect effect of negative emotions was also moderated by moral identity. Theoretically, this paper examines the relationship and boundary conditions between social crowding and uncivilised tourist behaviour. Practically, the research provides suggestions for natural area destination flow management.

Corporate Embodiment as the Pedagogical Foundation of the Pentecostal Tradition

Abstract This article examines the pedagogical foundations of Pentecostal theology that are responsible for shaping and sustaining this theological tradition. The formative mechanisms of the Pentecostal tradition are found in the embodied logic of corporately embedded patterns of spiritual practices formed around the “full gospel” of Jesus Christ. The article traces how the Pentecostal tradition emerges from and yields practices associated with the apostolic experience of Jesus intensified with Pentecost by categorizing the dominant corporate forms of embodying the doctrines of salvation, sanctification, Spirit baptism, divine healing, and the expectation of God’s kingdom. This typology suggests that the corporate embodiment of faith identifies most closely the particular contribution of the Pentecostal movement to the Christian life.

How different of the rhizospheric and endophytic microbial compositions in watermelons with different fruit shapes.

Fruit shape is an important character of watermelon. And the compositions of rhizospheric and endophytic microorganisms of watermelon with different fruit shape also remains unclear. To elucidate the biological mechanism of watermelon fruit shape formations, the rhizospheric and endophytic microbial community compositions between oval (OW) and circular watermelons (CW) were analyzed. The results showed that except of the rhizospheric bacterial richness (P < 0.05), the rhizospheric and endophytic microbial (bacterial and fungal) diversity were not statistically significant between OW and CW (P > 0.05). However, the endophytic microbial (bacterial and fungal) compositions were significantly different. Firstly, Bacillus, Rhodanobacter, Cupriavidus, Luteimonas, and Devosia were the unique soil dominant bacterial genera in rhizospheres of circular watermelon (CW); In contrast, Nocardioides, Ensifer, and Saccharomonospora were the special soil dominant bacterial genera in rhizospheres of oval watermelons (OW); Meanwhile, Cephalotrichum, Neocosmospora, Phialosimplex, and Papulaspora were the unique soil dominant fungal genera in rhizospheres of circular watermelon (CW); By contrast, Acremonium, Cladosporium, Cryptococcus_f__Tremellaceae, Sodiomyces, Microascus, Conocybe, Sporidiobolus, and Acremonium were the unique soil dominant fungal genera in rhizospheres of oval watermelons (OW). Additionally, Lechevalieria, Pseudorhodoferax, Pseudomonas, Massilia, Flavobacterium, Aeromicrobium, Stenotrophomonas, Pseudonocardia, Novosphingobium, Melittangium, and Herpetosiphon were the unique dominant endophytic bacterial genera in stems of CW; In contrast, Falsirhodobacter, Kocuria, and Kineosporia were the special dominant endophytic genera in stems of OW; Moreover, Lectera and Fusarium were the unique dominant endophytic fungal genera in stems of CW; By contrast, Cercospora only was the special dominant endophytic fungal genus in stems of OW. All above results suggested that watermelons with different fruit shapes exactly recruited various microorganisms in rhizospheres and stems. Meanwhile, the enrichments of the different rhizosphric and endophytic microorganisms could be speculated in relating to watermelon fruit shapes formation.

The role of Ga and Y on binary Al2O3-Y2O3 and Al2O3-Ga2O3 mixed oxides nanoparticles towards potential Ni water-gas shift catalysts

This work focuses on the study of binary Al2O3-Y2O3-x and Al2O3-Ga2O3-x mixed oxides with varying Y2O3 or Ga2O3 nominal loading (x=25, 50) prepared by hydrothermal synthesis assisted by Triton X-100. The mixed oxides were used to prepare Ni-based (5 wt%) catalysts for the Water Gas Shift Reaction. The Al2O3 sample presented urchin-like hollow nanosphere morphology, which evolved to solid nanospheres with Y2O3 or Ga2O3 in the mixed oxides. The physicochemical characterization indicated good integration of the mixed oxides, especially on the low-content additive oxides. The theoretical results confirmed that Ga goes deeper into the alumina matrix than Y, partially explaining the XPS and HRTEM results in which the Ni dispersion was better in the Ni/AlGa-x samples. The FTIR in-situ measurements of the reaction allowed us to propose that the reaction occurs minimally through the carbonyl mechanism at low temperatures (<300 °C) and the formate mechanism at high temperatures (>300 °C).

Hydrodynamic performance analysis of formations of dual three-dimensional undulating fins

The work seeks to understand the hydrodynamic performance and interaction mechanisms of double-fin formations. A high-resolution numerical technique based on the constraint immersed boundary method is used for simulating the 3D double-fin system. Comprehensive analysis is carried out, focusing on the hydrodynamic performance of formations with various arrangements, phase differences, and spatial distances. The result shows that the side-by-side formation can suppress the thrust of the fins while reducing energy consumption. The tandem formation notably enhances the thrust for the fin positioned at the rear, albeit at the cost of increased energy consumption. In the tandem formation with a small spacing, the following fin can obtain a thrust increase of 28% and an efficiency increase of 10%, independent of the phase difference. The thrust enhancement in the tandem formation is related to the suction-based propulsion mechanism induced by hydrodynamic interactions. However, the interaction mechanism between the two side-by-side fins resembles the so-called channelling effect. The unilateral channel flow perturbs the pressure equilibrium on either side of the fin, potentially imposing additional resistance on the undulating fin, with effects depending on the phase difference. The study offers new insights into understanding the collective behaviours of undulating fins.

A new class of single-phase multiferroics: Bismuth-based layered supercell oxide thin films—Current progress and future perspectives

Multiferroic materials, where ferroelectric and magnetic orders coexist, have ignited substantial research interest due to the achievable manipulation of magnetic orders using external electric fields, a feature that has garnered serious interest for memory storage applications. Nonetheless, naturally occurring single-phase multiferroic materials are scarce, thus constraining options for practical use. Over the last decade, bismuth-based layered supercell (LSC) oxides have emerged as novel candidates for multiferroics, catalyzing extensive investigations in this domain. Additionally, these LSC systems are known for their anisotropic structures and optical properties, making them promising for application in optics such as polarizers, beam splitters, and modulators. This thorough review explores the development and current advancements in multiferroic bismuth-based LSC materials. It covers the diverse nature of LSCs, detailing their microstructure, properties, and the mechanics of self-assembly formation. It also highlights the remarkable multifunctional characteristics of LSC-based nanocomposites, with a particular focus on their applications in electronics and optics. Moreover, this review examines the significant potential of LSCs in practical applications, particularly through their integration onto silicon and flexible substrates via heteroepitaxy and film transfer techniques. Finally, it offers insights into potential future research avenues and the broader implications of these versatile LSC materials.

Understanding the Reverse Water Gas Shift Reaction over Mo2C MXene Catalyst: A Holistic Computational Analysis

AbstractPristine Mo2C MXene has been proposed as an heterogeneous catalysis of the reverse water gas shift (RWGS) reaction. The present computational study aims at understanding its catalytic performance and reaction mechanisms tackling its thermodynamics, kinetics, and surface dynamic effects, combining Gibbs free energy profiles gained by density functional theory (DFT), mean‐field kinetics by microkinetic modeling, and rare‐event steps by kinetic Monte Carlo (kMC). The RWGS endergonicity goes for the use of high temperatures and reactants partial pressures to make the reaction exergonic. Gibbs free energy profiles show a preference for redox mechanism, whereas microkinetic simulations favor a low‐temperature preference of formate mechanism. The kMC reveals simultaneous operating redox and formate pathways, where surface coverage disfavors redox favoring the formate pathway. A peak performance is found at 700 K, in line with reported experiments, where the formation of surface O2* is found to be key, acting as a reservoir for O* adatoms while freeing surface sites upon O2* formation. Even though high turnover frequencies are predicted, the system could benefit from swing operando conditions, alternating CO production steps with H2 reduction regeneration steps, and/or ways to reduce the surface O2* and so to have more active catalytic sites.

Multiscale Mineralization in the Leopard Gecko Eggshell

AbstractReptilian (non‐avian) eggshell biomineralization is markedly different from avian eggshells. Despite discontinuous/variable mineralization, the reptilian eggshell (like in birds) is responsible for protective and developmental functions of the egg as part of a highly successful reproduction strategy. Using multiscale imaging and characterization methods including X‐ray and electron microscopy/tomography, a 3D overview of eggshell ultrastructure in the gekkotan Eublepharis macularius – the common leopard gecko is provided. Eggshell mineral is shown to be sensitive to aqueous preparations, where cryogenic methods are essential for accurate mineral and organic preservation. Interwoven with the mineral are underlying organic fibers involved in the formation of complex hierarchical order in the eggshell, including nucleation and growth of mineral. The calcitic mineral phase of the eggshell takes on three microstructural motifs at the shell surface: nodular scutes (≈40 µm), intermittent blunt or star‐shaped mineral rosettes (≈1 mm), and smaller mineral corollas (≈10 µm). Individual scutes have two hierarchical mineral structures – mineral nanospheres (≈500 nm) and mineral nanodomains (≈40 nm). Diverse and variable biomineralization features of reptilian eggshells likely reflect the importance of differences in ecology and physiology on egg formation, survival, and eggshell mechanics, and are likely related to hydration sensitivity, structural organic‐inorganic interactions, and mineral polymorphism.

Highly stable FeNiMnCaO catalyst for integrated CO2 capture and hydrogenation to CO

The integrated CO2 capture from flue gas and hydrogenation can be realized by the consecutive calcium-looping (CaL) and reverse-water–gas-shift (RWGS) reactions. However, the incompatibility between the catalysis and adsorption components aggravates the sintering and deactivation of metal particles and CaO base material during the high-temperature process. Herein, we prepared a highly efficient and stable FeNiMnCaO material via a modified sol–gel method for in situ CaL and RWGS reaction, exhibiting a CO2 adsorption capacity of 13.2 mmol g−1 at 40 cycles with 58.0 % CO2 conversion and 100 % CO selectivity at 700 °C. The highly-dispersed Fe and Ni species in the developed catalyst not only suppressed the sintering of MnCaO, but also synergistically benefited the RWGS reaction, where FeOx species promoted CO2 adsorption and metallic Ni facilitated H2 dissociation. The reaction followed the H-assisted association formate mechanism, in which adsorption of CO2 occurred at the FeOx-CaO interface with the aid of the hydroxyl surface groups to form bidentate bicarbonates, followed by dehydration to bidentate formate and decomposition to CO and H2O in the presence of Ni-dissociated reactive H* species.