Cooperative Coefficient Research Articles

Biomechanical evaluation of flash-frozen and cryo-sectioned papillary muscle samples by using sinusoidal analysis: cross-bridge kinetics and the effect of partial Ca2+ activation.

We examined the integrity of flash-frozen and cryo-sectioned cardiac muscle preparations (introduced by Feng and Jin, 2020) by assessing tension transients in response to sinusoidal length changes at varying frequencies (1-100Hz) at 25°C. Using 70-μm-thick sections, we isolated fiber preparations to study cross-bridge (CB) kinetics: preparations were activated by saturating Ca2+ as well as varying concentrations of ATP and phosphate (Pi). Our results showed that, compared to ordinary skinned fibers, in-series stiffness decreased to 1/2, which resulted in a decrease of isometric tension to 62%, but CB kinetics and Ca2+ sensitivity were little affected. The pCa study demonstrated that the rate constant of the force generation step (2πb) is proportionate to [Ca2+] at < 5μM, suggesting that the activation mechanism can be described by a simple second order reaction. We also found that tension, stiffness, and magnitude parameters are related to [Ca2+] by the Hill equation, with a cooperativity coefficient of 4-5, which is consistent with the fact that Ca2+ activation mechanisms involve cooperative multimolecular interactions. Our results support the long-held hypothesis that Process C (Phase 2) represents the CB detachment step, and Process B (Phase 3) represents the force generation step. Moreover, we discovered that constant H may represent the work-performing step in cardiac preparations. Our experiments demonstrate excellent CB kinetics with two well-defined exponentials that can be more distinguished than those found using ordinary skinned fibers. Flash-frozen and cryo-sectioned preparations are especiallysuitable for multi-institutionalcollaborations nationally and internationally because of their ease of transportation.

Analysis of Multi-Modal Public Transit Competing Relationships and Evolutionary Mechanisms in Cities in Cold Regions

In order to reveal the characteristics of the competition and cooperation of multi-modal public transportation in the cities of cold areas and to study the competitive relationship of multi-modal public transportation in cold areas, the urban public transportation system in cold areas is divided into three sub-systems, namely, conventional buses, urban mass transit, and cabs, to analyze the competitive relationship and evolution mechanism of multi-modal public transportation in cities of cold areas. We construct a multi-modal public transit Lotka–Volterra competitiveness model, considering that conventional buses and urban mass transit are mainly dominant in urban public transit systems in cold regions, and introduce the competitive influence effect coefficients and cooperative influence effect coefficients to analyze the mechanism of the evolution of the competitiveness between conventional buses and urban mass transit. The data on traffic supply and demand and travel of the Harbin bus system, a typical city in China, are collected, and the simulation analysis of multi-modal competing relationship and evolution mechanism of conventional bus and urban mass transit competition is carried out, respectively, with Harbin as the research object. The results show that the constructed model can better describe the multi-modal bus competition relationship and evolution mechanism.

Research on collaborative innovation cooperation strategies of manufacturing digital ecosystem from the perspective of multiple stakeholders

The digital ecosystem has hastened the fusion of manufacturing and digital technology in realizing product and service value. However, due to the coordination dilemmas within the digital ecosystem such as risk sharing, competition and cooperation among stakeholders, this study aims to explore the collaborative innovation cooperation strategies of multiple stakeholders, and to investigate the interaction effects of differential incentives on each other's strategies. By constructing a dynamic differential game model, this study solves the optimal innovation efforts, digital servitization levels and innovation benefits under different cooperation intensities, and analyzes the influence of various factors on the total innovation benefits of the digital ecosystem. It is found that under different decision-making modes, the influence of incentive subsidy coefficient and cost-sharing coefficient on the innovation efforts and innovation benefits of multiple stakeholders is different. Under the decentralized decision-making mode, the incentive mechanism positively promotes the innovation efforts of both parties of cooperative enterprises, while the local government is not affected, while under the centralized decision-making mode, the incentive mechanism positively affects the innovation efforts and innovation benefits of all three parties. Specifically, under the Stackelberg game, both the innovation efforts and innovation benefits achieve Pareto improvement, while under the cooperative game, the total system innovation benefits reach Pareto optimality and the optimal strategy is realized. In addition, an optimal range exists for the benefit distribution coefficient and the policy guidance coefficient. Furthermore, factors like the cooperative benefit impact coefficient, innovation capability coefficient, and policy guidance coefficient have a positive effect on the total system innovation benefits. Conversely, factors like the discount rate, technology decay coefficient, and innovation input coefficient inhibit the growth of the total system innovation benefits. The value provides theoretical support for collaborative innovation cooperation in the digital ecosystem, thus facilitating the progress of digital transformation in manufacturing.

Dynamic all-optical memory switching based on atomic optical bistable behavior in a three level Λ-type atomic system

We theoretically investigate the atomic optical bistability (AOB) in a three-level Λ-type atomic system confined in a unidirectional optical ring cavity. The role of the intensity or detuning of the control field on AOB is explored, and results show that absorption, dispersion, and nonlinearity can be modified significantly by the control field due to quantum coherence and interference in multilevel atomic systems. Thus, tuning the intensity or detuning of the control field can manipulate the switch-up and switch-down thresholds, as well as the area of the bistable hysteresis loop. According to the controllability of AOB, we design various schemes to realize dynamical all-optical switching between the high and low outputs of two bistable curves for a fixed cavity input. In addition, dynamical all-optical memory switching can be implemented by adding a pulse sequence for the intensity or detuning of the control field. For appropriate parameters, such as the cooperative coefficient, the extinction ratio of the switching can be improved dramatically.

Cross-diffusion mediated Spatiotemporal patterns in a predator–prey system with hunting cooperation and fear effect

Cooperation during hunting is a common predation plan of action among several large predators to increase their biomass raising capturing potential which can also produce fear in the prey and dispersal-influenced pattern creation is also relevant from both a fundamental and an applied standpoint. Considering these, we present a modified Leslie–Gower predator–prey model incorporating fear, intra-specific competition and hunting cooperation of predators following Berec’s encounter-driven functional response in presence of cross-diffusion. In the non-spatial system, biologically feasible equilibria and their stability conditions are derived. Taking the level of fear as bifurcation parameter, occurrence of limit cycle via Hopf bifurcation and the stability of limit cycle computing Lyapunov coefficient are discussed. In diffusive model, spacial focus on Turing instability conditions and to determine the relevant intervals at which various patterns will begin to appear. In the two dimensional spatial domain, under Neumann boundary condition, various Turing patterns such as spot, stripe, mixture of spot and stripe, labyrinth patterns are emerged varying fear, hunting cooperation and cross-diffusion coefficient. Hopf–Turing region is also a centre for several complex patterns. The numerical simulations indicate that the patterns are in same or opposite phase according to the sign of cross-diffusion coefficient. Intra-specific competition among predators tend the system towards stability. Cross-diffusion causes a paradox to population density with raising fear and hunting cooperation.

Optimal decisions in power battery swapping closed-loop supply chain under different innovation investment modes

This paper researches the impact of different innovation investment modes on the closed-loop supply chain (CLSC) profit and pricing decisions under an uncertain recycling quality background. Furthermore, we construct a battery swapping CLSC under three innovation investment modes. The research results show that: (1) Under the cooperative innovation investment mode, the decision variables and CLSC system profit all reach the optimal level. (2) Increasing the subscription duration can promote the reduction of subscription price, which is beneficial to the improvement of innovation investment level. (3) When the innovation cooperation coefficient is within a certain range, it will promote the increase of profits for the CLSC. (4) The balanced battery ratio is an important factor affecting enterprise decision-making, and it has a more significant impact on the battery swapping operator. (5) The power battery manufacturer can dynamically adjust the echelon utilization quality threshold according to the echelon utilization value to achieve optimal profit.

The Appropriate Scale of Competition Between Online Taxis and Taxis Based on the Lotka-Volterra Evolutionary Model

In order to determine the optimal scale for urban ride-hailing services and taxis while promoting their sustainable growth, we have developed a Lotka-Volterra evolutionary model that accounts for the competitive, cooperative, and mixed dynamics between these two entities. This model is rooted in the theory of synergistic evolution and is supported by data simulation and analysis. By employing this model, we can identify the appropriate size for urban ride-hailing services and taxis when they reach equilibrium under different environmental conditions. The study’s findings reveal that the evolutionary outcomes of online ride-hailing services and traditional taxis are closely linked to the competitive impact coefficient and the cooperative effect coefficient. In highly competitive environments, intense rivalry can lead to the elimination of the less competitive party, while the dominant player ultimately attains a specific size threshold. As competition moderates, both entities can achieve a balanced and stable coexistence in the market. In cooperative environments, both online ride-hailing services and traditional taxis have more room for development, which facilitates the integration of existing and innovative business models. In environments marked by competition, the development trends of both entities mirror those in competitive settings, but cooperation can slow down the decline of the less competitive party. In conclusion, we propose strategies to foster fair competition between online ride-hailing services and traditional taxis, consider the coexistence of old and new business models, and promote their integrated development.

Additive-Free Method for Enhancing the Volume Phase Transition Rate in Light-Responsive Hydrogels: A Study of Micro-Nano Bubble Water on PNIPAM-co-AAc Hydrogels.

Light-responsive hydrogels containing light-thermal convertible pigments have received interest for their possible applications in light-responsive shutters, valves, drug delivery systems, etc. However, their utility is limited by the slow response time. In this study, we investigated the use of micro-nano bubble water as a preparation solvent to accelerate the volume phase transition kinetics of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-AAc) hydrogels. The hydrogels were characterized by dynamic light scattering (DLS) and dissolved oxygen (DO) measurements. The mechanical properties, surface morphology, and chemical composition of the hydrogels were analyzed by Young's modulus measurements, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy, respectively. The results showed that hydrogels prepared with bubble water changed the volume transition rate by more than two orders of magnitude by simply changing the standing time of the bubble water for only a few hours. The cooperative diffusion coefficients obtained from the light-induced volume transition kinetics correlated linearly with Young's modulus and metastable state swelling ratio. Our results suggest that bubbles act as efficient water channels, thereby modulating the response rate and providing a simple, additive-free method for preparing hydrogels with a wide range of response rates.

Role of Allee Effect, Hunting Cooperation, and Dispersal to Prey–Predator Model

In prey–predator interaction, many factors, such as the fear effect, Allee effect, cooperative hunting, and group behavior, can influence the population dynamics. Hence, studying these factors in prey–predator makes the model more realistic. In this paper, we have proposed the prey–predator model having herd and Allee effect in prey population, where predators follow hunting cooperation. We have employed temporal analysis to examine the role of the Allee effect and hunting cooperation. Furthermore, we have extended the analysis to spatiotemporal analysis to examine the role of dispersal and the type of spatial structure formed by the population due to random movement. We first discuss the proposed model’s existence and positivity, then the stability of the existing equilibrium points through Routh–Hurwitz criteria. The temporal analysis is carried out through Hopf-bifurcation at the coexistence equilibrium point by considering the Allee threshold ([Formula: see text]), hunting cooperation ([Formula: see text]), and attack rate ([Formula: see text]) as controlled parameters. With the addition of diffusion to the model, we examine the spatial model stability and derive the Turing instability condition, which will give rise to various Turing patterns. Finally, numerical simulations are performed to validate the analytical results. The theoretical study and numerical simulation results demonstrate that the Allee effect, hunting cooperation, and diffusion coefficient are sensitive parameters to the model’s stability.

A multi-objective optimal power management strategy for enhancement of battery and propellers lifespan in all-electric ships

This paper proposes a multi-objective optimum approach for the participation of the propulsion system in mitigating the All-Electric Ship (AES) power system fluctuations. This strategy optimally balances the propellers torque/speed change and the energy storages charge/discharge rate to obtain an economically-efficient operating point. The method aims to minimize the propeller mechanical fatigue and the battery loss of life (LoL) according to their investment costs, while other operational constraints are considered. For this purpose, a novel index, called the Propulsion System Cooperation Coefficient (PSCC), is developed. This index adjusts the magnitude of the propeller speed/torque variations regarding the AES investment costs, components LoL, and power quality. A straightforward procedure is proposed to acquire this coefficient during an operating condition. The simulations revealed that the proposed multidisciplinary approach remarkably reduces the AES operation and maintenance expenditures associated with the loss of life of the mechanical and electrical equipment. This outcome holds with the vessel being either operational or at the design level. Since the proposed strategy demonstrated that addressing mechanical fatigue damage is significant in a demand-side control approach, it can also benefit the terrestrial microgrids power management systems.

Theoretical Analysis of Flexural Time-Varying Properties of Aluminum Alloy-Reinforced RC Beam under Atmospheric Environment

This paper aims to reveal the degradation of the flexural load capacity of reinforced concrete (RC) beams reinforced with aluminum alloy (AA) under atmospheric conditions. For the same, first, time-varying models of the flexural load capacity of RC beams were developed before and after reinforcement with AA and steel plate based on the time-varying properties of the materials. Subsequently, upon collecting existing test data, the reliability of the models was verified. Finally, the parameters of AA-reinforced and steel plate-reinforced RC beams were analyzed to investigate the influence of factors such as concrete cover depth, cross-sectional area of reinforcing material, and cooperative working coefficient of reinforcing material and concrete (demonstrate the ability of reinforcement material and concrete to work together) on the remaining service life, rust initiation time, and cracking time. The results show that under atmospheric environment, the flexural time-varying degradation model for RC beam can be divided into three stages: pre-rusting, rusting-pre-cracking, and post-cracking, with differences in the dominant factors at each stage. In terms of long-term performance, AA reinforcement is significantly more efficient than steel plate reinforcement. This study provides some theoretical basis for the design of AA reinforcement in the atmospheric environment.

Optimized Cooperative Control of Error Port-Controlled Hamiltonian and Adaptive Backstepping Sliding Mode for a Multi-Joint Industrial Robot

Robot joints driven by permanent magnet synchronous motors (PMSM) often cannot have both superior accuracy and rapidity when they track target signals. The robot joints have fine dynamic characteristics and poor steady-state characteristics when the signal controller is used, or they have fine steady-state characteristics and poor dynamic characteristics when the energy controller is used. It is hard to make robot joints that have both superior dynamic and steady-state characteristics at once using a single control method. In order to solve this problem, the strategy of optimized cooperative control is proposed. First, an error port-controlled Hamiltonian (EPCH) energy controller and an adaptive backstepping sliding mode (ABSM) signal controller are designed. Second, an optimized cooperative control coefficient based on the position error of a robot joint is designed; this enables the system to switch smoothly between the EPCH energy controller and ABSM signal controller. Next, the strategy of optimized cooperative control is designed. In this way, robot systems can combine the advantages of the EPCH energy controller and the ABSM signal controller. Finally, simulation results demonstrate that using the strategy of optimized cooperative control gives robot joints outstanding control performance in terms of tracking accuracy and response rapidity.

Functionalized Cortical Bone-Inspired Composites Adapt to the Mechanical and Biological Properties of the Edentulous Area to Resist Fretting Wear.

Dental implants with long-term success of osseointegration have always been the goal, however, difficulties exist. The accumulation of fretting damage at the implant-bone interface often gets overlooked. Commonly used titanium is approximately 7-fold harder and stiffer than cortical bone. Stress shielding caused by the mismatching of the elastic modulus aggravates fretting at the interface, which is accompanied by the risk of the formation of proinflammatory metal debris and implant loosening. Thus, the authors explore functionalized cortical bone-inspired composites (FCBIC) with a hierarchical structure at multiple scales, that exhibit good mechanical and biological adaptivity with cortical bone. The design is inspired by nature, combining brittle minerals with organic molecules to maintain machinability, which helps to acquire excellent energy-dissipating capability. It therefore has the comparable hardness and elastic modulus, strength, and elastic-plastic deformation to cortical bone. Meanwhile, this cortical bone analogy exhibits excellent osteoinduction and osseointegration abilities. These two properties also facilitate each other to resist fretting wear, and therefore improve the success rate of implantation. Based on these results, the biological-mechanical co-operation coefficient is proposed to describe the coupling between these two factors for designing the optimized dental implants.

Locally generalised multi-agent reinforcement learning for demand and capacity balancing with customised neural networks

Reinforcement Learning (RL) techniques are being studied to solve the Demand and Capacity Balancing (DCB) problems to fully exploit their computational performance. A locally generalised Multi-Agent Reinforcement Learning (MARL) for real-world DCB problems is proposed. The proposed method can deploy trained agents directly to unseen scenarios in a specific Air Traffic Flow Management (ATFM) region to quickly obtain a satisfactory solution. In this method, agents of all flights in a scenario form a multi-agent decision-making system based on partial observation. The trained agent with the customised neural network can be deployed directly on the corresponding flight, allowing it to solve the DCB problem jointly. A cooperation coefficient is introduced in the reward function, which is used to adjust the agent’s cooperation preference in a multi-agent system, thereby controlling the distribution of flight delay time allocation. A multi-iteration mechanism is designed for the DCB decision-making framework to deal with problems arising from non-stationarity in MARL and to ensure that all hotspots are eliminated. Experiments based on large-scale high-complexity real-world scenarios are conducted to verify the effectiveness and efficiency of the method. From a statistical point of view, it is proven that the proposed method is generalised within the scope of the flights and sectors of interest, and its optimisation performance outperforms the standard computer-assisted slot allocation and state-of-the-art RL-based DCB methods. The sensitivity analysis preliminarily reveals the effect of the cooperation coefficient on delay time allocation.

Coordination of two competing closed-loop supply chains: A cooperative game approach

In the development of end-of-life (EOL) products recycling, coordinating competing closed-loop supply chains (CLSCs) with restricted coalition has become an important topic that has yet to be thoroughly investigated. In this study, we first investigate the possible coalitions for two CLSCs composed of manufacturers and third-party recyclers under a restricted coalition structure, which is used for deriving the characteristic functions representing the bargaining powers of different coalitions and allocating the overall profits. Subsequently, to fairly allocate the maximal profit, we establish a cooperative game in the form of characteristic function for the two CLSCs and use an advanced solution concept (average tree value) to coordinate them. We find that: compared to other non-cooperative and partial cooperative models, the centralized model can always achieve the best performance, e.g., the highest recovery rate. And the profit of the fully centralized model increases linearly with the increase of the cooperation coefficient. When the third-party recyclers of two CLSCs form alliance, the profit of the manufacturer is positively or negatively correlated with the cooperation coefficient due to the difference of the model and price elasticity coefficient. Under the cooperation of two CLSCs third-party recyclers, the relationship between the profit of the third-party recycler, the profit of the single chain system or the profit of the double chain system and the cooperation coefficient increases first and then decreases, but the inflection point is different. The coordination of two competing CLSCs can be well addressed by the allocation scheme proposed in this study, while satisfying the collective and individual rationalities.

Mathematical Modeling and Dynamical Analysis for Tumor Cells and Tumor Propagating Cells Controlled by G9a Inhibitors

It is of critical importance to comprehend the biological environment and core tumor populations when trying to design successful therapeutic solutions for fighting cancers. In several diseases, G9a has been recognized as a novel epigenetic therapeutic target, and its blockage can shift tumor cells (TCs) toward tumor propagating cells (TPCs). This study combines mathematical modeling based on ordinary differential equations and dynamical analysis to quantitatively and qualitatively understand the interactions among G9a, TCs, and TPCs, denoted as G9a-TC-TPC. We propose four different dynamical systems with the impact of the strong Allee effect, named the Hill–Hill system, Logistic–Logistic system, Hill–Logistic system and Logistic–Hill system, to simulate different biological processes through the Hill functions and the Logistic functions that are often used in the models of biological systems. Based on theoretical analysis of these models, including the positivity, boundedness and stability of equilibria, we find that the Hill–Logistic system can display bistable states that correspond to the wild-type tumors and the aggressive tumors. Consequently, we use bifurcation analysis and numerical simulations to illustrate the complicated dynamical behavior of this system. It has been shown that under a specific therapy that changes the relative apoptotic rate of TCs (G9a suppresses the apoptosis of TCs), which can affect the bistability and instability of the system, the wide-type state can be obtained. We also discover that the relative handling time of TCs and TPCs can cooperatively enhance bistability, whereas the cooperative coefficient of feedback can contribute to all tumor cells moving from high-level monostability to bistable states in a restricted region, then to low-level stable states. These results offer new insights for more precisely understanding epigenetic therapy treatments with G9a.

산업연관분석을 통한 물류산업의 경제적 효과에 대한 분석

The purpose of this study is to make econometric analysis on the economic effects of China’s logistics industry by using the China industry association table, and provide help for the promotion of China’s logistics industry policy in the future. For this reason, 17 industrial fields, including 5 fields of transportation equipment and 12 fields of transportation service industry, are classified as logistics industry in the 2020 industrial association table issued by the China Bureau of statistics in 2022, and the industrial association table of China’s logistics industry for all 28 industries is compiled and analyzed. The analysis results show that, first of all, the production inducement coefficient of China’s logistics industry is 2.7956, and the line cooperation coefficient is 4.6270, indicating that China’s logistics industry is a basic strategic industry supporting the development of national economy. Second, the influence coefficient (backward chain effect) of China’s logistics industry is 1.0466, and the sensitivity coefficient (forward chain effect) is 1.7322, both greater than 1. China’s logistics industry is an intermediate demand manufacturing industry. Third, the final demand of China’s logistics industry is 8382 billion yuan for input into the national economy. The total production induced amount is 626916.8 trillion yuan (38783.5 trillion yuan, 6.2%) and the value-added induced amount is 224227.75 billion yuan (13718.8 trillion yuan, 6.1%) respectively. The income induced amount is 11420.4 trillion yuan (691.34 billion yuan, 6.1%) respectively, The induced amount of production tax is 23469.2 billion yuan (1379.3 trillion yuan, 5.9%) in the logistics industry. Fourth, China’s logistics industry has a total of 30627 labor inducing effects, including 849 direct labor inducing personnel and 29778 indirect labor inducing personnel, showing its role as an employment creating industry.

Rapid Actuation of Thermo-Responsive Polymer Networks: Investigation of the Transition Kinetics.

The swelling and collapsing of thermo-responsive poly(N-isopropylacrylamide)-based polymer (pNIPAAm) networks are investigated in order to reveal the dependency on their kinetics and maximum possible actuation speed. The pNIPAAm-based network was attached as thin hydrogel film to lithographically prepared gold nanoparticle arrays to exploit their localized surface plasmon resonance (LSPR) for rapid local heating. The same substrate also served for LSPR-based monitoring of the reversible collapsing and swelling of the pNIPAAm network through its pronounced refractive index changes. The obtained data reveal signatures of multiple phases during the volume transition, which are driven by the diffusion of water molecules into and out of the network structure and by polymer chain re-arrangement. For the micrometer-thick hydrogel film in the swollen state, the layer can respond as fast as several milliseconds depending on the strength of the heating optical pulse and on the tuning of the ambient temperature with respect to the lower critical solution temperature of the polymer. Distinct differences in the time constants of swelling and collapse are observed and attributed to the dependence of the cooperative diffusion coefficient of polymer chains on polymer volume fraction. The reported results may provide guidelines for novel miniature actuator designs and micromachines that take advantages of the non-reciprocal temperature-induced volume transitions in thermo-responsive hydrogel materials.

A robust method for designing multistable systems by embedding bistable subsystems

Although multistability is an important dynamic property of a wide range of complex systems, it is still a challenge to develop mathematical models for realising high order multistability using realistic regulatory mechanisms. To address this issue, we propose a robust method to develop multistable mathematical models by embedding bistable models together. Using the GATA1-GATA2-PU.1 module in hematopoiesis as the test system, we first develop a tristable model based on two bistable models without any high cooperative coefficients, and then modify the tristable model based on experimentally determined mechanisms. The modified model successfully realises four stable steady states and accurately reflects a recent experimental observation showing four transcriptional states. In addition, we develop a stochastic model, and stochastic simulations successfully realise the experimental observations in single cells. These results suggest that the proposed method is a general approach to develop mathematical models for realising multistability and heterogeneity in complex systems.

Ontogeny of hemoglobin‑oxygen binding and multiplicity in the obligate air-breathing fish Arapaima gigas

The evolutionary and ontogenetic changes from water- to air-breathing result in major changes in the cardiorespiratory systems. However, the potential changes in hemoglobin's (Hb) oxygen binding properties during ontogenetic transitions to air-breathing remain poorly understood. Here we investigated Hb multiplicity and O2 binding in hemolysates and Hb components from juveniles and adults of the obligate air-breathing pirarucu (Arapaima gigas) that starts life as water-breathing hatchlings. Contrasting with previous electrophoresis studies that report one or two isoHbs in adults, isoelectric focusing (IEF) resolved the hemolysates from both stages into four major bands, which exhibited identical O2 binding properties (i.e. O2 affinities, cooperativity coefficients, and sensitivities to pH and the major organic phosphate effectors), also as compared to the cofactor-free hemolysates. Of note, the multiplicity pattern recurred upon reanalyses of the most-abundant fractions isolated from the juvenile and the adult stages, suggesting possible stabilization of different quaternary states with different isoelectric points during the purification procedure. The study demonstrates unchanged Hb-O2 binding properties during development, despite the pronounced differences in O2 availability between the two media, which harmonizes with findings based on a broader spectrum of interspecific comparisons. Taken together, these results disclose that obligate air-breathing in Arapaima is not contingent upon changes in Hb multiplicity and O2 binding characteristics.