State Equilibrium Research Articles

Sorption studies of 4-NP onto goethite: effects of contact time, pH, concentration, ionic strength and temperature

The effects of different state variables (contact time, pH, concentration, ionic strength and temperature) were investigated on the adsorption of 4-nitrophenol (4-NP) onto goethite for its potential utilization in mitigating water pollution. The results suggested that the adsorption of 4-NP reached a quasi-steady state equilibrium at 24 h and followed pseudo-second order kinetics. The computed value of pseudo-second order rate coefficient for adsorption of 4-NP on goethite was 447.57 kg mM−1 h−1. Adsorption of 4-NP on goethite was higher when the solution pH was < pHzpc of goethite and near pKa(7.15)of 4-NP and vice versa. The effect of concentration of 4-NP on adsorption revealed the heterogeneity of sorption sites on goethite surface; highly selective sites of higher bonding energy up to sorption density of 1.42 mM kg−1 and lower selectivity sites of lesser bonding energy for sorption density above 2.07 mM kg−1. An increase in ionic strength, increased the adsorption of 4-NP on goethite but an increase in temperature decreased the adsorption. The changes in thermodynamic parameters indicated that adsorption of 4-NP was a spontaneous and exothermic reaction with an increase in the entropy of the system. Based on these results, the optimal conditions for the maximal removal of 4-NP were 6.7–7.0 pH, 0.015–0.02 ionic strength, 15 °C temperature with 1: 100 goethite (sorbent)-solution ratio.

A Magnetic Force Microscopy Study of Patterned T-Shaped Structures.

The study of patterned magnetic elements that can sustain more than one bit of the information is an important research line for developing new routes in magnetic storage and magnetic logic devices. Previous Monte Carlo studies of T-shaped magnetic nanostructures revealed the equilibrium and evolution of magnetic states that could be found as a result of the strong configurational anisotropy of these systems. In this work, for the first time, such behavior of T-shaped magnetic nanostructures is experimentally studied. In particular, T-shaped Co nanostructures have been produced by electron beam lithography using a single step lift-off process over Si substrates. The existence of four magnetic stable states has been proven by Magnetic Force Microscopy (MFM) and the analysis was complemented by Micromagnetic Simulations. The results confirmed that even for what can be considered large structures, with μm sizes, such four stable magnetic states can be achieved, and therefore two magnetic bits of information can be stored. We also addressed how to write and read those bits.

Stochastic model predictive control for remanufacturing system management

Uncertainties in the quality, quantity, and operational time of used products pose a challenge to the management of remanufacturing systems. In addition, it becomes a necessity to optimize the operation of the remanufacturing system to balance the quality of products, remanufacturing efficiency, and service level. In this study, a stochastic discrete-time dynamical model is proposed to represent a remanufacturing system, where the relationship between the market satisfaction, inventory status, and operational actions is explicitly modeled. This includes production and inventory planning, resource allocation and acquisition. To handle uncertainties, a stochastic model predictive control approach is proposed to plan the actions that optimize the remanufacturing efficiency. Our results in the simulation examples show that: (a) without supplies, the remanufacturing system has better stability and robustness than a conventional manufacturing system with the same initial stocks; and (b) with insufficient initial stocks, the remanufacturing system demands fewer and more gradual supplies, thereby keeping the system stable. Finally, a sensitivity analysis is conducted for testing the performance of the remanufacturing system. By changing the operational action capacity, different state equilibria are discovered, which correspond to distinct system response characteristics. The study reveals notable managerial insights and effects of product commonality, demand patterns, and operational actions scheduling on the efficiency of the remanufacturing system.

Optimization of charging strategy for lithium-ion battery packs based on complete battery pack model

This study focuses on a charging strategy for battery packs, as battery pack charge control is crucial for battery management system. First, a single-battery model based on electrothermal aging coupling is proposed; subsequently, a battery pack cooling model and battery pack equilibrium management model are combined to form a complete battery pack model that describes the state parameters of the battery pack and the interaction between the individual batteries in the battery pack. Then, a multi-objective optimal charging strategy considering charging time, aging, and energy loss is proposed, and the equilibrium management, temperature, and battery parameters are restricted. A genetic algorithm method was used to optimize the adaptive multi-phase constant-current constant-voltage charging strategy. A fast charging strategy based on the shortest charging time is proposed. The results show that the fast charging strategy can significantly reduce charging time but leads to aging and increases energy loss. The contradictory relation between charging time and aging and the interaction between charging time and energy loss are revealed. The balance optimization charging strategy appears on the left side of the Pareto curve. Finally, a balanced charging strategy considering charging time, aging, and energy loss is obtained. In comparison with single batteries with the same average initial current charging, the constant current phase order decreases because of battery pack state parameters and equilibrium management, resulting in different charging strategies.

Long-Term Behavior of Dynamic Equilibria in Fluid Queuing Networks

Steady State in Equilibrium for Flows over Time

Zero absolute vorticity state in thermal equilibrium as a hydrodynamic analog of the quantum harmonic oscillator ground state

Here, we point out on an intriguing mapping between the quantum harmonic oscillator ground state and the zero absolute vorticity plane Couette flow of a Boltzmann-like density distributed ideal gas in thermal equilibrium. The mapping is obtained when the gas is embedded in a rotating frame whose rotation rate is equal to half of the frequency of the quantum harmonic oscillator.

OUTWARD HABITS AND ENVIRONMENTAL QUALITY IN AN OVERLAPPING GENERATIONS MODEL

Outward habit formation affects consumption decisions. Since consumption displays a negative environmental externality, outward habits has as well an (adverse) effect on the environment. This research paper centers around the theoretical linkage between the combination of both externalities (environmental deterioration and outward habits). The objective of this study is to examine the impacts of outward habits on the state of the environment in the context of an overlapping generations economy. In our study, environmental quality is a public good negatively affected by consumption activity and positively affected by maintenance investment. With outward habit formation, the build-up level of average past consumption in the economy at large influences the current utility of an individual consumer. Thus, individuals draw utility not only from their own level of current consumption, but also from its level relative to the average consumption in the economy. How does outward habit influence the state of the environment? We analyze this question using an overlapping generations model with outward habit and environmental quality in the utility function. In steady state equilibrium allocation, we show that whether outward habits are destructive to the environment depends on the degrees of outward habit formation and the size of the economy.

Subtractive versus Multiplicative Habits in Environmental Economics

The present paper presents overlapping generations set-up with internal habits in consumption and the presence of environmental quality in the utility function. The modeling of habits implies that the consumer preferences are influenced not only by a household’s own current consumption, but also by their personal past consumption. Our main objective is to study and compare the impacts of first subtractive second multiplicative internal habits on the environmental quality and the capital accumulation through a comparative static behavior at the stable steady state equilibrium. By changing the way the habit is specified, we have shown that introducing habit can lead to different findings regarding the capital and the environment.

Effect of geometric and magnetic boundary conditions on magnetic islands in 3D force-free ideal MHD equilibria

Three-dimensional boundary features and magnetic perturbations affect the magnetic topology of the force-free ideal MHD equilibria formed within a given volume. The use of the PSI-Tet 3D finite-element equilibrium code reveals the existence of magnetic islands inside such equilibria within boundaries with three-dimensional features in configurations that directly depend on the natures of those features. The nature and limits of the influence of such features are explored, as is the influence of flux boundary conditions to qualitatively identify the structure of magnetic islands in Taylor state equilibria with three-dimensional boundary conditions.

To lie or not to lie: Super-relaxing with myosins.

Since the discovery of muscle in the 19th century, myosins as molecular motors have been extensively studied. However, in the last decade, a new functional super-relaxed (SRX) state of myosin has been discovered, which has a 10-fold slower ATP turnover rate than the already-known non-actin-bound, disordered relaxed (DRX) state. These two states are in dynamic equilibrium under resting muscle conditions and are thought to be significant contributors to adaptive thermogenesis in skeletal muscle and can act as a reserve pool that may be recruited when there is a sustained demand for increased cardiac muscle power. This report provides an evolutionary perspective of how striated muscle contraction is regulated by modulating this myosin DRX↔SRX state equilibrium. We further discuss this equilibrium with respect to different physiological and pathophysiological perturbations, including insults causing hypertrophic cardiomyopathy, and small-molecule effectors that modulate muscle contractility in diseased pathology.

Heat exchange and fluctuation in Gaussian thermal states in the quantum realm

The celebrated exchange fluctuation theorem—proposed by Jarzynski and Wójcik (2004 Phys. Rev. Lett. 92 230602) for heat exchange between two systems in thermal equilibrium at different temperatures—is explored here for quantum Gaussian states in thermal equilibrium. We employ the Wigner distribution function formalism for quantum states, which exhibits a close resemblance to the classical phase-space trajectory description, to arrive at a formal Jarzynski–Wójcik result. For two Gaussian states in thermal equilibrium at two different temperatures kept in contact with each other for a fixed duration of time, we show that the Jarzynski–Wójcik-like relation reduces to the corresponding classical result in the limit ℏ → 0.

Novel Effect of Tau N-Terminal Mutation, R5L, on Microtubule Mediated Condensation

Understanding the physiological function of the intrinsically disordered microtubule associated protein (MAP) Tau has proven challenging. Tau, primarily expressed in neurons, is known to have a variety of axonal functions, including regulation of microtubule dynamics and modulation of kinesin motor motility. Interestingly, research on the microtubule binding behavior of Tau reveals that Tau binds to the microtubule surface in a dynamic equilibrium between static and diffusive states. Although it is understood that the binding state equilibrium plays a role in physiological Tau function, such as modulation of kinesin motility, it is less understood how disease associated mutations affect Tau binding behavior and function. The canonical theory states that mutations in Tau reduce Tau affinity for the microtubule. Here, we investigate the role of an N-terminal disease associated mutation in Tau, R5L, using an in vitro reconstituted system for single molecule Total Internal Reflection Fluorescence (smTIRF) Microscopy. Contrary to the canonical theory, we determined the R5L mutation does not reduce Tau affinity for the microtubule. Rather, the R5L mutation reduces the total amount of Tau bound to the microtubule at saturating conditions. Our data suggests the R5L mutation reduces Tau:Tau interactions, decreasing the ability of R5L-Tau to form larger order complexes, known as “Tau condensates.” Currently, we are determining the mechanism by which this occurs, potentially due to a structural change associated with the R5L mutation. Altogether, these results challenge the current paradigm of how mutations in Tau lead to disease.

Seeking Out Heterogeneous Hydrogen Bonding in a Self-Assembled 2D Cocrystal of Croconic Acid and Benzimidazole on Au(111)

A two-dimensional (2D) hydrogen-bonded cocrystal was synthesized from croconic acid (CA) and benzimidazole (BI) on a gold surface under ultrahigh vacuum conditions. The network domains have a 1:1 CA/BI stoichiometry, can be synthesized over a range of temperatures, and contain one-dimensional chains of molecules connected by heterogeneous hydrogen bonds. Density functional theory (DFT) computations suggest that a tautomeric salt-like structure, with deprotonated CA and protonated BI, is the most stable model, which creates heterogeneous N–H···O contacts instead of N···H–O ones. The homogeneity of the network’s appearance in scanning tunneling microscopy (STM) and a habitual change in the STM features under certain tip conditions indicate that there is an equilibrium of tautomeric molecular states that may be influenced to some degree by STM stimuli. Overall, this study demonstrates how careful consideration of the precursor molecules can tune the architecture within a family of cocrystal networks and introduce desired bonding motifs that haven’t been achieved by solution-based synthesis for these species, such as the heterogeneous hydrogen bonds herein.

Imidazopyridine-Based 5-HT6 Receptor Neutral Antagonists: Impact of N1-Benzyl and N1-Phenylsulfonyl Fragments on Different Receptor Conformational States.

G-protein coupled receptors (GPCRs) exist in an equilibrium of multiple conformational states, including different active states, which depend on the nature of the bound ligand. In consequence, different conformational states can initiate specific signal transduction pathways. The study identified compound 7e, which acts as a potent 5-hydroxytryptamine type 6 receptor (5-HT6R) neutral antagonist at Gs and does not impact neurite growth (process controlled by Cdk5). MD simulations highlighted receptor conformational changes for 7e and inverse agonist PZ-1444. In cell-based assays, neutral antagonists of the 5-HT6R (7e and CPPQ), but not inverse agonists (SB-258585, intepirdine, PZ-1444), displayed glioprotective properties against 6-hydroxydopamine-induced and doxorubicin-induced cytotoxicity. These suggest that targeting the activated conformational state of the 5-HT6R with neutral antagonists implicates the protecting properties of astrocytes. Additionally, 7e prevented scopolamine-induced learning deficits in the novel object recognition test in rats. We propose 7e as a probe for further understanding of the functional outcomes of different states of the 5-HT6R.

Optimization of a coconut oil extraction process with supercritical CO2 considering economical and thermal variables

Supercritical fluid extraction (SFE) with CO2 as solvent has demonstrated to be friendlier with the environment than traditional extraction processes and technically feasible. However, the required CO2 thermodynamic cycles at high pressures (in critical point surroundings) demand high energy consumption. Therefore, in this research a rigorous economic and thermic optimization for coconut oil SFE was proposed. A novel combination of CO2 empirical state equations, equilibrium and mass transfer models (expressed as ordinary differential equations) of coconut oil SFE were synthesized with raw material and manufacture costs in an optimization problem. The unitary cost of the extracted coconut oil was defined as target function for minimization, with productivity and yield as constrains. The optimal results provide the low cycle temperature, CO2 flow, the extraction vessel volume and the extraction time, that minimize the target variable and satisfy constrains.

Long-lived triplet charge-separated state in naphthalenediimide based donor-acceptor systems.

1,4,5,8-Naphthalenediimides (NDIs) are widely used motifs to design multichromophoric architectures due to their ease of functionalisation, their high oxidative power and the stability of their radical anion. The NDI building block can be incorporated in supramolecular systems by either core or imide functionalization. We report on the charge-transfer dynamics of a series of electron donor–acceptor dyads consisting of a NDI chromophore with one or two donors linked at the axial, imide position. Photo-population of the core-centred π–π* state is followed by ultrafast electron transfer from the electron donor to the NDI. Due to a solvent dependent singlet–triplet equilibrium inherent to the NDI core, both singlet and triplet charge-separated states are populated. We demonstrate that long-lived charge separation in the triplet state can be achieved by controlling the mutual orientation of the donor–acceptor sub-units. By extending this study to a supramolecular NDI-based cage, we also show that the triplet charge-separation yield can be increased by tuning the environment.

State and Local Economic Policy in Equilibrium

State and Local Economic Policy in Equilibrium

Dynamics of quantum discord based on linear entropy and negativity of qutrit-qubit system under classical dephasing environments

A reliable analytical method to evaluate the non-classical correlations based on linear entropy for an arbitrary qudit-qubit quantum state is proposed. The linear entropy is used to overcome the difficulty encountered with the computability of quantum discord based on von Neumann entropy. The quantum discord based on linear entropy is employed to derive the quantum correlations for a qutrit-qubit system undergoing global (bilocal + collective) classical dephasing environment. Our studies were focused mainly on a particular initial qutrit-qubit state in thermal equilibrium at a temperature T. The obtained amount of quantum discord (QD) is then compared with the measurement-induced disturbance (MID) and logarithmic negativity (LN). The analysis shows that both QD and MID are more robust than entanglement (LN) against the decoherence effect. Besides, the system exhibits interesting behaviors. As for instance, freezing dynamics and entanglement sudden death (ESD). The method developed in this paper to quantify quantum correlations is reliable because it allows us to consider analytically the arbitrary qutrit-qubit quantum states in the classical dephasing environment.

Протолитическое равновесие возбужденных состояний флуоресцеина

The protolytic equilibrium of the excited states of fluorescein depends not only on the equilibrium in the ground state, but also on the efficiency of photoexcitation, relaxation and proton transfer in the excited state. Due to the competing rate of radiative and nonradiative processes occurring in a mixture of protolytic forms, there is still a problem of identifying the fluorescent characteristics of individual forms of fluorescein. In this work, the stationary distribution of the concentrations of the ground and excited states of the cation, a number of tautomers of the neutral form, monoanion and dianion of fluorescein under continuous photoexcitation was simulated. The pH values of the predominant existence of excited states of individual protolytic forms were determined, which were confirmed by steady-state fluorescence measurements. Possible reasons for the discrepancies in the published data on the fluorescent properties of individual protolytic forms of fluorescein are discussed, refined data on the spectral shape and lifetimes of the quinoid and monoanion of fluorescein are obtained.

Cooperation‐Based Modeling of Sustainable Development: An Approach from Filippov’s Systems

The concept of Sustainable Development has given rise to multiple interpretations. In this article, it is proposed that Sustainable Development should be interpreted as the capacity of territory, community, or landscape to conserve the notion of well‐being that its population has agreed upon. To see the implications of this interpretation, a Brander and Taylor model, to evaluate the implications that extractivist policies have over an isolated community and cooperating communities, is proposed. For an isolated community and through a bifurcation analysis in which the Hopf bifurcation and the heteroclinic cycle bifurcation are detected, 4 prospective scenarios are found, but only one is sustainable under different extraction policies. In the case of cooperation, the exchange between communities is considered by coupling two models such as the one defined for the isolated community, with the condition that their transfers of renewable resources involve conservation policies. Since human decisions do not occur in a continuum, but rather through jumps, the mathematical model of cooperation used is a Filippov System, in which the dynamics could involve two switching manifolds of codimension one and one switching manifold of codimension two. The exchange in the cooperation model, for specific parameter arrangements, exhibits n‐periodic orbits and chaos. It is notable that, in the cases in which the system shows sliding, it could be interpreted as a recovery delay related to the time needed by the deficit community to recover, until its dependence on the other community stops. It is concluded (1) that a sustainability analysis depends on the way well‐being is defined because every definition of well‐being is not necessarily sustainable, (2) that sustainability can be visualized as invariant sets in the nonzero region of the space of states (equilibrium points, n‐periodic orbits, and strange attractors), and (3) that exchange is key to the prevalence of the human being in time. The results question us on whether Sustainable Development is only to keep us alive or if it also implies doing it with dignity.