Baraneedharan, P., Shankari, D., Arulraj, A., Sephra, P. J., Mangalaraja, R. V., & Khalid, M. (2023). Nanoengineering of MXeneBased FieldEffect Transistor Gas Sensors: Advancements in NextGeneration Electronic Devices. J. Electrochem. Soc., 180(10), 107501.
Abstract: In recent years, TwoDimensional (2D) materials have gained significant attention for their distinctive physical and chemical properties, positioning them as promising contenders for the next generation of electronic technologies. One notable group within these materials is MXenes, which have exhibited remarkable breakthroughs across various technological domains, including catalysis, renewable energy, electronics, sensors, fuel cells, and supercapacitors. By making subtle modifications to the surface termination, introducing metal ions, precise etching timing, and applying surface functionalization, the characteristics of MXenes can be finetuned to achieve desired band structures, rendering them suitable for sensor design. This review focuses on the strategic development of gas sensors based on FieldEffect Transistors (FETs), thoroughly examining the latest progress in MXenebased material design and addressing associated challenges and future prospects. The review aims to provide a comprehensive overview of MXene, summarizing its current applications and advancements in FETbased gas sensing.

Canessa, E., & Riolo, R. L. (2006). An agentbased model of the impact of computermediated communication on organizational culture and performance: an example of the application of complex systems analysis tools to the study of CIS. J. Inf. Technol., 21(4), 272–283.
Abstract: Organizations that make use of computer information systems (CIS) are prototypical complex adaptive systems (CAS). This paper shows how an approach from Complexity Science, exploratory agentbased modeling (ABM), can be used to study the impact of two different modes of use of computermediated communication (CMC) on organizational culture (OC) and performance. The ABM includes stylized representations of (a) agents communicating with other agents to complete tasks; (b) an OC consisting of the distribution of agent traits, changing as agents communicate; (c) the effect of OC on communication effectiveness (CE), and (d) the effect of CE on task completion times, that is, performance. If CMC is used in a broad mode, that is, to contact and collaborate with many, new agents, the development of a strong OC is slowed, leading to decreased CE and poorer performance early on. If CMC is used in a local mode, repeatedly contacting the same agents, a strong OC develops rapidly, leading to increased CE and high performance early on. However, if CMC is used in a broad mode over longer time periods, a strong OC can develop over a wider set of agents, leading to an OC that is stronger than an OC which develops with local CMC use. Thus broad use of CMC results in overall CE and performance that is higher than is generated by local use of CMC. We also discuss how the dynamics generated by an ABM can lead to a deeper understanding of the behavior of a CAS, for example, allowing us to better design empirical longitudinal studies.

Cominetti, R., Quattropani, M., & Scarsini, M. (2022). The BuckPassing Game. Math. Oper. Res., Early Access.
Abstract: We consider two classes of games in which players are the vertices of a directed graph. Initially, nature chooses one player according to some fixed distribution and gives the player a buck. This player passes the buck to one of the player's outneighbors in the graph. The procedure is repeated indefinitely. In one class of games, each player wants to minimize the asymptotic expected frequency of times that the player receives the buck. In the other class of games, the player wants to maximize it. The PageRank game is a particular case of these maximizing games. We consider deterministic and stochastic versions of the game, depending on how players select the neighbor to which to pass the buck. In both cases, we prove the existence of pure equilibria that do not depend on the initial distribution; this is achieved by showing the existence of a generalized ordinal potential. If the graph on which the game is played admits a Hamiltonian cycle, then this is the outcome of priorfive Nash equilibrium in the minimizing game. For the minimizing game, we then use the price of anarchy and stability to measure fairness of these equilibria.

Cominetti, R., Scarsini, M., Schroder, M., & StierMoses, N. (2022). Approximation and Convergence of Large Atomic Congestion Games. Math. Oper. Res., Early Access.
Abstract: We consider the question of whether and in what sense, Wardrop equilibria provide a good approximation for Nash equilibria in atomic unsplittable congestion games with a large number of small players. We examine two different definitions of small players. In the first setting, we consider games in which each player's weight is small. We prove that when the number of players goes to infinity and their weights to zero, the random flows in all (mixed) Nash equilibria for the finite games converge in distribution to the set of Wardrop equilibria of the corresponding nonatomic limit game. In the second setting, we consider an increasing number of players with a unit weight that participate in the game with a decreasingly small probability. In this case, the Nash equilibrium flows converge in total variation toward Poisson random variables whose expected values are War drop equilibria of a different nonatomic game with suitably defined costs. The latter can be viewed as symmetric equilibria in a Poisson game in the sense of Myerson, establishing a plausible connection between the Wardrop model for routing games and the stochastic fluctuations observed in real traffic. In both settings, we provide explicit approximation bounds, and we study the convergence of the price of anarchy. Beyond the case of congestion games, we prove a general result on the convergence of large games with random players toward Poisson games.

Dumett, M. A., & Cominetti, R. (2018). On The Stability Of An Adaptive Learning Dynamics In Traffic Games. J. Dyn. Games, 5(4), 265–282.
Abstract: This paper investigates the dynamic stability of an adaptive learning procedure in a traffic game. Using the RouthHurwitz criterion we study the stability of the rest points of the corresponding mean field dynamics. In the special case with two routes and two players we provide a full description of the number and nature of these rest points as well as the global asymptotic behavior of the dynamics. Depending on the parameters of the model, we find that there are either one, two or three equilibria and we show that in all cases the mean field trajectories converge towards a rest point for almost all initial conditions.

Eswaramoorthy, N., Arulraj, A., Mangalaraja, R. V., Pitchaiya, S., & Rajaram, K. (2022). Nanoscale interfacial engineering of 1D gC3 N4 enables effective and thermally stable HTLfree carbonbased perovskite solar cells with aging for 100 hours. Int. J. Energy Res., 46(14), 20194–20205.
Abstract: Carbonbased perovskite solar cells (PSCs) have exhibited unprecedented progress in the past decades, however, the deficit of opencircuit voltage and nonradiative recombination losses are the dominating limiting factors in scaling up the devices in view of commercialization. The researchers and scientists recognize the dominating factors and propose different themes to overcome the limiting factors. Among the different solutions, interfacial engineering of PSCs between the interfaces of transporting layer (electron or hole) and perovskite influences the reduction of nonradiative recombination losses with improvement in device efficiency. In this work, onedimensional (1D) graphitic carbon nitride (gC3N4) is synthesized through simple pyrolysis using two different mediums (ethanol and ethylene glycol). 1D gC3N4 is interfaced between electron transport layer and perovskite absorber influences effectively in finetuning the work function by aligning the energy level of the fabricated mixed halide PSCs. Nanoscale engineered 1D gC3N4 interfacial layer supports boosting the power conversion efficiency of the PSCs to 5.20% and 7.14% for tube and layered tube structures at ambient conditions. Further, the interfacial layer aids in improving thermal (tube: similar to 59.80%; layered tube: similar to 74.50%) and photostability (tube: similar to 78.65%; layered tube: similar to 87.25%) characteristics of the fabricated devices for 100 h duration at ambient conditions.

Goles, E., Lobos, F., Montealegre, P., Ruivo, E. L. P., & de Oliveira, P. P. B. (2020). Computational Complexity of the Stability Problem for Elementary Cellular Automata. J. Cell. Autom., 15(4), 261–304.
Abstract: Given an elementary cellular automaton and a cell v, we define the stability decision problem as the determination of whether or not the state of cell v will ever change, at least once, during the time evolution of the rule, over a finite input configuration. Here, we perform the study of the entire elementary cellular automata rule space, for the two possible decision cases of the problem, namely, changes in v from state 0 to 1 (0 > 1), and the other way round (1 > 0). Out of the 256 elementary cellular automata, we show that for all of them, at least one of the two decision problems is in the NC complexity class.

Gonzalez, E., & Villena, M. J. (2011). Spatial attrition modeling: Stability conditions for a 2D + t FD formulation. Comput. Math. Appl., 61(11), 3246–3257.
Abstract: A new general formulation for the spatial modeling of combat is presented, where the main drivers are movement attitudes and struggle evolution. This model in its simplest form is represented by a linear set of two coupled partial differential equations for two independent functions of the space and time variables. Even though the problem has a linear shape, nonnegative values for the two functions render this problem as nonlinear. In contrast with other attempts, this model ensures stability and theoretical consistency with the original Lanchester Equations, allowing for a better understanding and interpretation of the spatial modeling. As a numerical illustration a simple combat situation is developed. The model is calibrated to simulate different troop movement tactics that allow an invader force to provoke maximum damage at a minimum cost. The analysis provided here reviews the tradeoff between spatial grid and time stepping for attrition cases and then extends it to a new method for guaranteeing good numerical behavior when the solution is expected to grow along the time variable. There is a wide variety of spatial problems that could benefit from this analysis. (C) 2011 Elsevier Ltd. All rights reserved.

GonzalezOlivares, E., GonzalezYanez, B., BecerraKlix, R., & RamosJiliberto, R. (2017). Multiple stable states in a model based on predatorinduced defenses. Ecol. Complex., 32, 111–120.
Abstract: A large variety of antipredator defenses are exhibited by plants, animals and microbes in nature. A deep understanding of the dynamic consequences of prey responses to predation risk is essential for building a comprehensive theory of food webs. Here we present a simple classification of prey defenses based on the sensitivity of prey immunity to predation respect to abundances of prey and predators. Only three out of six defense types have been analytically studied in the context of predatorprey dynamics, which reveals a serious gap in our current knowledge of ecological interactions. In this study we present a mathematical analysis on a widely occurring type of prey defense whose behavior has not been established in exact terms. The study model considers prey whose average immunity to predators is enhanced by predator abundance. This case, known as inducible defenses, has been reported for a wide array of species. Our results reveal a rich dynamic behavior, in which the predatorprey system exhibits either one, two or three positive equilibrium points, with up to two attractors. Thus, inducible defenses constitute a mechanism that could drive alternative stable states even in very simple food web models. (C) 2017 Elsevier B.V. All rights reserved.

Gordon, M. A., Vargas, F. J., & Peters, A. A. (2021). Comparison of Simple Strategies for Vehicular Platooning With Lossy Communication. IEEE Access, 9, 103996–104010.
Abstract: This paper studies vehicle platooning with communication channels subject to random data loss. We focus on homogeneous discretetime platoons in a predecessorfollowing topology with a constant time headway policy. We assume that each agent in the platoon sends its current position to the immediate follower through a lossy channel modeled as a Bernoulli process. To reduce the negative effects of data loss over the string stability and performance of the platoon, we use simple strategies that modify the measurement, error, and control signals of the feedback control loop, in each vehicle, when a dropout occurs. Such strategies are based on holding the previous value, dropping to zero, or replacing with a prediction based on a simple linear extrapolation. We performed a simulationbased comparison among a set of different strategies, and found that some strategies are favorable in terms of performance, while some others present improvements for string stabilization. These results strongly suggest that proper design of compensation schemes for the communications of interconnected multiagent systems plays an important role in their performance and their scalability properties.

Gordon, M. A., Vargas, F. J., & Peters, A. A. (2023). Mean square stability conditions for platoons with lossy intervehicle communication channels. Automatica, 147, 110710.
Abstract: This paper studies the meansquare stability of heterogeneous LTI vehicular platoons with intervehicle communication channels affected by random data loss. We consider a discretetime platoon system with predecessor following topology and a constant timeheadway spacing policy. Lossy channels are modeled by Bernoulli processes and allowed to be correlated in space. We make use of a class of compensation strategies to reduce the effect of data loss. Necessary and sufficient conditions are derived to guarantee the convergence of the mean and variance of the tracking errors, which depend not only on the controller design but also on the compensation strategy and the probabilities of successful transmission. We illustrate the theoretical results through numerical simulations, describing different platoon behaviors. We also provide insights on the meansquare stability as a necessary condition for string stability in this stochastic setting.(c) 2022 Elsevier Ltd. All rights reserved.

Grieves, N., Bouchy, F., UlmerMoll, S., Gill, S., Anderson, D. R., Psaridi, A., et al. (2023). An old warm Jupiter orbiting the metalpoor Gdwarf TOI5542. Astron. Astrophys., 668, A29.
Abstract: We report the discovery of a 1.32(0.10)(+0.10)M(Jup) planet orbiting on a 75.12 day period around the G3V 10.8(3.6)(+2.1) Gyr old star TOI5542 (TIC 466206508; TYC 908612101). The planet was first detected by the Transiting Exoplanet Survey Satellite (TESS) as a single transit event in TESS Sector 13. A second transit was observed 376 days later in TESS Sector 27. The planetary nature of the object has been confirmed by groundbased spectroscopic and radial velocity observations from the CORALIE and HARPS spectrographs. A third transit event was detected by the groundbased facilities NGTS, EulerCam, and SAAO. We find the planet has a radius of 1.009(0.035)(+0.036)R(Jup) and an insolation of 9.6(0.8)(+0.9)S(circle plus), along with a circular orbit that most likely formed via disk migration or in situ formation, rather than higheccentricity migration mechanisms. Our analysis of the HARPS spectra yields a host star metallicity of [Fe/H] = 0.21 +/ 0.08, which does not follow the traditional trend of high host star metallicity for giant planets and does not bolster studies suggesting a difference among low and highmass giant planet host star metallicities. Additionally, when analyzing a sample of 216 wellcharacterized giant planets, we find that both high masses (4 MJup < Mp < 13 MJup) and low masses (0.5 MJup < Mp < 4 MJup), as well as both both warm (P > 10 days) and hot (P < 10 days) giant planets are preferentially located around metalrich stars (mean [Fe/H] > 0.1). TOI5542b is one of the oldest known warm Jupiters and it is cool enough to be unaffected by inflation due to stellar incident flux, making it a valuable contribution in the context of planetary composition and formation studies.

Han, Z. Y., Chen, H., He, C. L., Dodbiba, G., Otsuki, A., Wei, Y. Z., et al. (2023). Nanobubble size distribution measurement by interactive force apparatus under an electric field. Sci. Rep., 13(1), 3663.
Abstract: Nanobubbles have been applied in many fields, such as environmental cleaning, material production, agriculture, and medicine. However, the measured nanobubble sizes differed among the measurement methods, such as dynamic light scattering, particle trajectory, and resonance mass methods. Additionally, the measurement methods were limited with respect to the bubble concentration, refractive index of liquid, and liquid color. Here, a novel interactive force measurement method for bulk nanobubble size measurement was developed by measuring the force between two electrodes filled with bulk nanobubblecontaining liquid under an electric field when the electrode distance was changed in the nm scale with piezoelectric equipment. The nanobubble size was measured with a bubble gas diameter and also an effective water thin film layer covered with a gas bubble that was estimated to be approximately 10 nm based on the difference between the median diameter of the particle trajectory method and this method. This method could also be applied to the solid particle size distribution measurement in a solution.

Krapp, L., GarridoDeutelmoser, J., BenítezLlambay, P., & Kratter, K. M. (2024). A Fast Secondorder Solver for Stiff Multifluid Dust and Gas Hydrodynamics. Astrophys. J. Suppl. Ser., 271(1), 7.
Abstract: We present MDIRK: a multifluid secondorder diagonally implicit RungeKutta method to study momentum transfer between gas and an arbitrary number (N) of dust species. The method integrates the equations of hydrodynamics with an implicitexplicit scheme and solves the stiff source term in the momentum equation with a diagonally implicit, asymptotically stable RungeKutta method (DIRK). In particular, DIRK admits a simple analytical solution that can be evaluated with O(N) operations, instead of standard matrix inversion, which is O(N)3 . Therefore, the analytical solution significantly reduces the computational cost of the multifluid method, making it suitable for studying the dynamics of systems with particlesize distributions. We demonstrate that the method conserves momentum to machine precision and converges to the correct equilibrium solution with constant external acceleration. To validate our numerical method we present a series of simple hydrodynamic tests, including damping of sound waves, dusty shocks, a multifluid dusty Jeans instability, and a steadystate gasdust drift calculation. The simplicity of MDIRK lays the groundwork to build fast highorder, asymptotically stable multifluid methods.

Kumar, M. P., Sasikumar, M., Arulraj, A., Rajasudha, V., Murugadoss, G., Kumar, M. R., et al. (2022). NiFe Layered Double Hydroxide Electrocatalyst Prepared via an Electrochemical Deposition Method for the Oxygen Evolution Reaction. Catalysts, 12(11), 1470.
Abstract: Herein, we aimed to obtain NiFe layered double hydroxide (LDH) with a controlled phase and surface morphology as a highly active and stable oxygen evolution catalyst via the electrochemical deposition method, which was thermodynamically stable for the oxygen evolution reaction (OER) in an alkaline medium. The NiFeLDH sample was analyzed by sophisticated instruments and tested as an electrocatalyst on Toray carbon (TC). The NiFeLDH electrocatalyst showed an excellent performance with lower overpotential of 0.27 V at 35 mA cm(2) and higher density of 125 mA cm(2) for OER in the 1 M KOH electrolyte solution. Moreover, the prepared catalyst exhibited unpredictable longtime stability for 700 h. From our knowledge, NiFeLDH is a robust highly stable electrocatalyst compared to the recent reports.

Martinez, C., Briones, F., Rojas, P., Aguilar, C., Guzman, D., & Ordonez, S. (2017). Microstructural and mechanical characterization of copper, nickel, and Cubased alloys obtained by mechanical alloying and hot pressing. Mater. Lett., 209, 509–512.
Abstract: Mechanical alloying and uniaxial compaction were used to obtain configurations of: elemental powders of Cu and Ni; binary alloys (CuNi and CuZr); and a ternary alloy (CuNiZr) under the same mechanical milling and hot pressing conditions. Microstructure and mechanical properties of these were investigated. According to XRD results, hot pressing process increases crystallite size and decreases microstrain in the compact samples, due to the release of crystalline defects without crystallization of amorphous alloys. The milled powder samples have a higher hardness than the unmilled samples, since crystal defects are incorporated into microstructural refinement during milling. The ternary alloy Cu40Ni10Zr had the highest hardness of all systems studied, reaching 689 HV0.5. Compression tests at 5% strain determined that Zrcontaining samples (amorphous phase) become more fragile after processing, and have the lowest values of compressive strength. In contrast, Ni samples and CuNi binary alloys are more resistant to compression. (

Moffat, R., Caceres, C., & Tapia, E. (2021). Rock Pillar Design Using a Masonry Equivalent Numerical Model. Energies, 14(4), 890.
Abstract: In underground mining, the design of rock pillars is of crucial importance as these are structures that allow safe mining by maintaining the stability of the surrounding excavations. Pillar design is often a complex task, as it involves estimating the loads at depths and the strength of the rock mass fabric, which depend on the intact strength of the rock and the shape of the pillar in terms of the aspect ratio (width/height). The design also depends on the number, persistence, orientation, and strength of the discontinuities with respect to the orientation and magnitude of the stresses present. Solutions to this engineering problem are based on one or more of the following approaches: empirical design methods, practical experience, and/or numerical modeling. Based on the similarities between masonry structures and rock mass characteristics, an equivalent approach is proposed as the one commonly used in masonry but applied to rock pillar design. Numerical models using different geometric configurations and state of stresses are carried out using a finite difference numerical approach with an adapted masonry model applied to rocks. The results show the capability of the numerical approach to replicate common types of pillar failure modes and stability thresholds as those observed in practice.

MontalvaMedel, M., Ledger, T., Ruz, G. A., & Goles, E. (2021). Lac Operon Boolean Models: Dynamical Robustness and Alternative Improvements. Mathematics, 9(6), 600.
Abstract: In VelizCuba and Stigler 2011, Boolean models were proposed for the lac operon in Escherichia coli capable of reproducing the operon being OFF, ON and bistable for three (low, medium and high) and two (low and high) parameters, representing the concentration ranges of lactose and glucose, respectively. Of these 6 possible combinations of parameters, 5 produce results that match with the biological experiments of Ozbudak et al., 2004. In the remaining one, the models predict the operon being OFF while biological experiments show a bistable behavior. In this paper, we first explore the robustness of two such models in the sense of how much its attractors change against any deterministic update schedule. We prove mathematically that, in cases where there is no bistability, all the dynamics in both models lack limit cycles while, when bistability appears, one model presents 30% of its dynamics with limit cycles while the other only 23%. Secondly, we propose two alternative improvements consisting of biologically supported modifications; one in which both models match with Ozbudak et al., 2004 in all 6 combinations of parameters and, the other one, where we increase the number of parameters to 9, matching in all these cases with the biological experiments of Ozbudak et al., 2004.

ValenzuelaHeredia, D., Panatt, C.:, Belmonte, M., Franchi, O., Crutchik, D., Dumais, J., VazquezPadin, J. R., et al. (2022). Performance of a twostage partial nitritationanammox system treating the supernatant of a sludge anaerobic digester pretreated by a thermal hydrolysis process. Chem. Eng. J., 429, 131301.
Abstract: A twostage system (partial nitritation (PN) and anammox processes) was used to remove nitrogen from the dewatering liquor originating from the thermal hydrolysis/anaerobic digestion (THP/AD) of municipal WWTP sludge. Two strategies were tested to start up the PN reactor: 1) maintaining a fixed hydraulic retention time (HRT) and increasing the ammonium loading rate (ALR) by decreasing the feeding dilution ratio and 2) feeding undiluted dewatering liquor and gradually decreasing the HRT. With diluted feeding, the reactor performance had destabilization episodes that were statistically correlated with the application of high specific ammonium (> 0.6 g NH4+N/(g TSS.d)) and organic (> 0.7 g COD/(g TSS.d)) loading rates. The second strategy allowed stable PN reactor operation while treating ALR up to 4.8 g NH4+N/(L.d) and demonstrating that dilution of THP/AD effluents is not required. The operating conditions promoted the presence of free nitrous acid levels (> 0.14 mg HNO2N/L) inside the PN reactor that inhibited the proliferation of nitrite oxidizing bacteria.
Batch activity tests showed that the inhibitory effects of organic compounds present in the THP/AD dewatering liquor on the ammonia oxidizing bacteria activity can be removed in the PN reactor. Thus, aerobic pretreatment would not be necessary when twostage systems are used. The PN reactor effluent was successfully treated by an anammox reactor.
An economic analysis showed that using twostage systems is advantageous for treating THP/AD dewatering liquor. The implementation of an aerobic pretreatment unit is recommended for WWTPs capacities higher than 5.10(5) inhabitants equivalent when onestage systems are used.

VeraDamian, Y., Vidal, C., & GonzalezOlivares, E. (2019). Dynamics and bifurcations of a modified LeslieGowertype model considering a BeddingtonDeAngelis functional response. Math. Meth. Appl. Sci., 42(9), 3179–3210.
Abstract: In this paper, a planar system of ordinary differential equations is considered, which is a modified LeslieGower model, considering a BeddingtonDeAngelis functional response. It generates a complex dynamics of the predatorprey interactions according to the associated parameters. From the system obtained, we characterize all the equilibria and its local behavior, and the existence of a trapping set is proved. We describe different types of bifurcations (such as Hopf, BogdanovTakens, and homoclinic bifurcation), and the existence of limit cycles is shown. Analytic proofs are provided for all results. Ecological implications and a set of numerical simulations supporting the mathematical results are also presented.
