Analog Systems Research Articles

Development of corn starch-sodium alginate emulsion gels as animal fat substitute: Effect of oil concentration

Emulsion gels were prepared utilizing corn starch (CS), sodium alginate (SA), and corn oil through calcium ion induction for animal-fat analogs. The influence of oil concentration on the rheological properties, microstructure and lipid oxidation of the emulsion gel was analyzed. Results revealed that the emulsion gel containing 30% (v/v) oil exhibited no surplus oil leakage and demonstrated the highest gel strength. The results of the small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) test proved that the emulsion gel exhibited the greatest elasticity and deformation resistance when the oil content was 30% (v/v), imparting suitable mouth feel and transport stability as an animal fat substitute. Microstructure analysis indicated that SA crosslinked with Ca2+ to generate a network structure accompanied by the reinforcing effect of starch granules, enabling the dense network to capture an optimal quantity of oil to form a uniform gel network structure. Furthermore, the emulsion gel exhibited markedly lower lipid oxidation compared to bulk oil after 14 days of storage. As a new fat analog system, the CS-SA emulsion gel holds promising potential for applications in the food industry.

Rock avalanches in northeastern Baffin Island, Canada: understanding low occurrence amid high hazard potential

Rock avalanches in fjord environments can cause direct catastrophic damage and trigger secondary submarine landslides and tsunamis. These are well-documented in Greenland, Norway, and Alaska but have gone largely unreported in the extensive fjord terrain of the eastern Canadian Arctic. We provide the first inventory of rock avalanche deposits in northeastern Baffin Island—a region characterized by moderate to high seismic hazard, steep and high-walled fjords and glacial valleys, active deglaciation, and observed climate warming. Over a broad study area of ~60,000 km2, one sixth of the terrain had sufficient slope height and gradient to potentially generate rock avalanches. Within that hazard zone, we identified eight rock avalanche deposits at six locations. Only three rock avalanche deposits at two locations are dated, using aerial imagery (1958-present), to the last century while five deposits at four locations are inferred as syn- to post-glacial, likely occurring shortly after local debuttressing. These total numbers fall well below documented inventories from Greenland, Norway, and Alaska. We hypothesize that (1) continuous permafrost persists throughout this region and continues to act as a stabilizing factor and (2) rock mass quality is high in areas of most extreme relief contrast within the study region relative to analogous high-latitude fjord systems such as those in southwestern Greenland. We suggest that Baffin Island is currently in a period of quasi-stability that follows the intense instability during initial deglaciation, yet precedes the higher anticipated slope instability that may occur during permafrost degradation.

Beyond numbers: visual and textual diversity in the online art database

ABSTRACT This study investigates visual and textual diversity in the online art database with Nationalmuseum as a case study. It combines quantitative and qualitative methods to characterize different types of representations and analyse how such variations can be connected to different circumstances for digitization. As shown, database records have varied over time and they mirror institutional attitudes and priorities. Artworks which have been activated by being on display, recently acceded, or undergone conservation are typically rich in visual and textual information. As this study shows there is a need to look at digitization beyond numbers as the processes of representing art collections online are steered by different cultural factors. It is evident that the already esteemed, popular, activated artworks in the museum are also more extensively represented online. In effect, digitization does not seem to broaden the access to the visual heritage but rather amplify existing biases in the analogue systems.

Design and implementation of an innovative single-phase direct AC-AC bipolar voltage buck converter with enhanced control topology

Direct AC–AC converters are strong candidates in the power converting system to regulate grid voltage against the perturbation in the line voltage and to acquire frequency regulation at discrete step levels in variable speed drivers for industrial systems. All such applications require the inverted and non-inverted form of the input voltage across the output with voltage-regulating capabilities. The required value of the output frequency is gained with the proper arrangement of the number of positive and negative pulses of the input voltage across the output terminals. The period of each such pulse for low-frequency operation is almost the same as the half period of the input grid or utility voltage. These output pulses are generated by converting the positive and negative input half cycles in noninverting and inverting forms as per requirement. There is no control complication to generate control signals used to adjust the load frequency as the operating period of the switching devices is normally greater than the period of the source voltage. However, high-frequency pulse width modulated (PWM) control signals are used to regulate the output voltage. The size of the inductor and capacitor is inversely related to the value of the switching frequency. Similarly, the ripple contents of voltage and currents in these filtering components are also inversely linked with PWM frequency. These constraints motivate the circuit designer to select high PWM frequency. However, the alignment of the high-frequency control input with the variation in the input source voltage is a big challenge for a design engineer as the switching period of a high-frequency signal normally lies in the microsecond. It is also required to operate some high-frequency devices for various half cycles of the source voltage, creating control complications as the polarities of the half cycles are continuously changing. This requires at least the generation of two high-frequency signals for different intervals. The interruption of the filtering inductor current is a big source of high voltage surges in circuits where the high-frequency transistors operate in a complementary way. This may be due to internal defects in the switching transistors or some unnecessary inherent delay in their control signals. In this research work, a simplified AC–AC converter is developed that does not need alignment of high-frequency control with the polarity of the source voltage. With this approach, high-frequency signals can be generated with the help of any analog or digital control system. By applying this technique, only one high-frequency control signal is generated and applied in AC circuits, as in a DC converter, without applying a highly sensitive polarity sensing circuit. So, controlling complications is drastically simplified. The circuit and configuration always avoid the current interruption problem of filtering the inductor. The proposed control and circuit topology are tested both in computer-based simulation and practically developed circuits. The results obtained from these platforms endorse the effectiveness and validation of the proposed work.

Movement patterns of Murray cod (Maccullochella peelii) and golden perch (Macquaria ambigua) in a northern Murray–Darling Basin dryland river

Context Dryland rivers are unique ecosystems, where drought and flood play an important role in shaping the ecosystem. River regulation has altered the natural flow regime in many of these systems, affecting migration cues and connectivity for many species. Aims To quantify the discharge-related movements of Murray cod and golden perch within the Condamine–Balonne River subject to differing levels of river regulation. Methods We quantified flow regime variability, river regulation and fish movement to develop generalised additive mixed models to predict movement probability for Murray cod and golden perch. Results Both species showed strong positive relationships between discharge and movement. Murray cod did not show any association with river regulation; however, medium-sized individuals were significantly more likely to move than were smaller or larger fish. Golden perch movements varied among levels of regulation, were more likely to move as body weight increased and showed seasonality of movement, moving less during winter. Conclusions This study presents the largely unobserved movement behaviours of fish across a gradient of river regulation and environmental conditions in the northern Murray–Darling Basin. Implications This information is valuable for informing policy and management decisions that may affect species’ life-history requirements in analogous river systems.

Construction of stable two-sided interface via the addition of phenylboric acid in Lithium-ion batteries

Electrolyte additive engineering is one of the most useful approaches to improve the interfacial property of electrode material in Li-ion batteries (LIBs), which plays a vital role in the mass transport during the electrochemical process. Boron-based electrolyte additives have a good application prospect, however exploring new additives with lower-cost and higher efficiency is still needed. In this study, Phenyl boric acid (PBA), acting as a two-sided interface modifier, is introduced to LiNi0.5Co0.2Mn0.3O2/SiC batteries. Through both theoretical calculations and experimental measurements, it is found that PBA could be preferentially reduced on the SiC anode and induce the formation of B-rich solid electrolyte interphase (SEI), which efficiently protects the anode material from the parasitic reaction. Besides, PBA can be sacrificially oxidized before other salt/solvent decomposition, achieving a highly-reversible lithiation/delithiation process at the cathode. Benefiting from these synergistic effects, the target Si-C/Li half-cells achieve a 2.5 % improvement in average coulomb efficiency of 100 cycles, while the capacity retention rate of NCM/Li half-cells and NCM/Si-C full cells increase by 21.4 % and 15.8 %, respectively. This work provides an effective approach to ameliorating the electrode interface chemistry of LIBs employing Si-based anodes Ni-rich cathodes and another analogous battery systems.

Application of locally regularized extremal shift to the problem of realization of a prescribed motion

Abstract A controlled system of differential equations under the action of an unknown disturbance is considered. The problem discussed in the paper consists in constructing algorithms for forming a control that provides the realization of a prescribed motion for any admissible disturbance. Namely these algorithms should provide the closeness in the metric of the space of differentiable functions of a phase trajectory of a given controlled system and some etalon trajectory of an analogous system functioning when any outer actions are absent. As the space of admissible disturbances, we take the space of measurable square integrable (with respect to the Euclidean norm) functions. The cases of inaccurate measurements of phase trajectories of both systems at all times and at discrete times are under study. Two computer oriented algorithms for solving the problem are designed. The algorithms are based on the (well-known in the theory of guaranteed control) method of extremal shift. In the process, its local (at each time of control correction) regularization is performed by the method of smoothing functional (the Tikhonov method). In addition, estimates for algorithm’s convergence rate are presented.

First principle evaluations on perovskite-type sodium trifluorides, NaMF3 (M= V, Mn, Fe, Co, Ni, and Cu), as electrode materials for Na-ion batteries

This ab initio study investigates the structural, Na diffusion channels, electrochemical, and electrical properties of NaMF3 (M= V, Mn, Fe, Co, Ni, and Cu) for as novel electrode materials for Na-ion batteries, using density functional theory (DFT) calculations. The stability and structural changes are evaluated during (de)sodiation. Considering electrochemical potential of the materials by Fermi and internal energy approaches, NaNiF3 and NaVF3 have the highest and lowest voltages, respectively. The electrical properties of the materials are examined in terms of intrinsic- and extrinsic-like band gaps. For comprehensiveness, the electrical rate-capability is estimated using two different approaches, i.e. Delta and CCTB. Consequently, utilizing various DFT approaches and evaluating properties, each considered material has its own advantages and drawbacks to be used as Na-ion electrode. Using a general perspective, this paper ranks the materials as NaCuF3, NaCoF3, NaVF3, NaMnF3, NaFeF3, and NaNiF3, respectively. This study opens a new landscape for future investigations about these promising intercalation electrode materials and also the other analogous systems.

Theoretical and experimental studies of CO2 hydrogenation to methanol on TM/In2O3-ZrO2 catalysts (TM = Cu, Ni and Pd): Mechanism analysis and quantitative description of MSI

Amidst the escalating concerns surrounding energy and environmental issues, the hydrotreatment of emitted CO2 and conversion into C1 products, such as methanol, have emerged as a pivotal strategy for effective mitigation. Previous investigations have identified the potential of indium-zirconium oxide catalysts doped with transition metals (TMs) for methanol synthesis. However, a comprehensive understanding of the impact of different TM loadings on catalytic performance, as well as a quantitative elucidation of the degree of metal-support interaction (MSI) between TM and substrate, necessitates further exploration. A multifaceted approach covering density functional theory (DFT) calculation, experimental validation and machine learning (ML) analysis is employed in this study to elucidate the underlying principles of MSI influence on hydrogenation, culminating in two general models for predicting the activation energy representing the degree of MSI. Consistent findings from theoretical calculations and experimental results demonstrate that, in comparison to Cu and Pd, Ni doped In2O3-ZrO2 catalyst shows superior performance both in thermodynamics and kinetics. This enhancement is attributed to the strong degree of MSI relationship between thermodynamically stable Ni and substrate, consequently leading to the enhancement in reducibility. Moreover, a three-layer framework is constructed to predict the activation energy in the formate pathway, which facilitates the evaluation of MSI degree in TM-loaded catalysts. To sum up, this work provides guidance for CO2 hydrogenation studies and quantitative analysis of MSI, contributing to a heightened understanding of the interaction mechanisms in analogous research systems.

Effect of 3D printer, implant analog and angulation on the accuracy of analog position in implant casts

Objectives: To evaluate the accumulative effect of 3D printer, implant analog systems, and implant angulation on the accuracy of analog position in implant casts.Methods: A reference cast, presenting a case of a three-unit implant-supported prosthesis, was scanned with a coordinate measurement machine, producing the first reference data set (CMM, n = 1). The second reference data set (n = 10) was prepared using an intraoral scanner (IOS) (Trios4). Test quadrant casts were produced using three DLP type 3D printers, Max (MAX UV385), Pro (PRO 4K65 UV), and Nex (NextDent 5100), and three implant analog systems, El (Elos), Nt (Nt-trading), and St (Straumann) (n = 90). Stone casts were also produced via analog impressions (Stone, n = 10). After digitization, the accuracy of 3D distance, local angulation (angle between implants) and global angulation (angle between the implant center axis and an axis perpendicular to the global plane) was evaluated by comparing the reference (CMM, IOS), test (3D print), and control (Stone) groups using metrology software. Data were statistically analyzed using three-way ANOVA and Tukey`s tests (α = 0.05).Results: IOS was truer in 3D implant distance and more precise in capturing local angulation than Stone (p ≤ 0.05). Other measurements were similar between both groups (p > 0.05). The amount of error introduced in the workflow by IOS and 3D printing was mostly similar (p > 0.05). 3D printed casts had similar or even higher accuracy than Stone group (p > 0.05). In most cases, higher trueness was achieved when using PRO 4K65 UV 3D printer and Elos implant analog system (p ≤ 0.05).Conclusion: 3D printer, implant analog system, and implant angulation have a significant effect on the accuracy of analog position in implant casts. Limited-span implant-supported cases could be reproduced digitally with similar accuracy as conventional methods.Clinical significance: A fully digital workflow with a carefully selected 3D printer and implant analog system can increase the accuracy of digitally produced implant casts with comparable accuracy to conventional workflow.

A Briefly Survey in Electronics System Design

In this paper, it will be tried to briefely talk about electronic system design. In these 20 years, electronic system such as other sciences has improved. From analog and digital circuits toward nano bio systems. It will be discussed the main methods of electronic system design not only in analog and digital systems but also about nano and bio electronics systems.

Sonoluminescence: Photon production in time-dependent analog systems

Sonoluminescence is a well-known laboratory phenomenon where an oscillating gas bubble in the appropriate environment periodically emits a flash of light in the visible frequency range. In this work, we study the system in the framework of analog gravity. We model the oscillating bubble in terms of analog geometry and propose a nonminimal coupling prescription of the electromagnetic field with the geometry. The geometry behaves as an analogous oscillating time-dependent background in which repeated flux of photons are produced in a wide frequency range through parametric resonance from quantum vacuum. Due to our numerical limitation, we could reach the frequency up to ∼105 m−1. However, we numerically fit the spectrum in a polynomial form including the observed frequency range around ∼107 m−1. Our current analysis seems to suggest that parametric resonance in analog background may play a fundamental role in explaining such phenomena in the quantum field theory framework. Published by the American Physical Society 2024

Quantifying flow regime impacts on hydrodynamic heat transfer in rough-walled rock fractures

Hydrodynamic heat transfer in rock fractures is crucial for many geophysical processes and engineering activities, notably in harnessing geothermal energy. Despite extensive research, characterizing hydrodynamic heat transfer in rock fractures, complicated by their geometric heterogeneity, remains a formidable challenge. To address this challenge, we experimentally investigated the hydrodynamic heat transfer in rock fractures with diverse geometric features at steady-state elevated temperatures. We found that both heterogeneous fracture geometry and elevated temperatures promote the transition of fracture flow from a linear to nonlinear regime. This flow regime transition enhances the heterogeneity of heat transfer intensity within the fracture and exacerbates the increase in heat transfer efficiency with flow rate. At a fortyfold increase in flow rate, the heat transfer coefficient in the most heterogeneous fracture rises by approximately 72 times, compared to about 28 times in the least heterogeneous one. Leveraging experimental data, we developed parametric models linking heat transfer coefficients, outflow temperature, and heat recovery rate to flow rate and geometric features, yielding a theoretical formulation for the maximal heat recovery rate. By introducing the concept of an energy conversion rate, we quantitatively evaluated the effect of nonlinear flow resistance on heat extraction feasibility, revealing that energy conversion rates in highly heterogeneous fractures can be up to 452 times lower than in less heterogeneous ones. This highlights the pivotal role of flow resistance in heat extraction feasibility. Our findings are instrumental for understanding and predicting the hydrodynamic heat transfer within fractured geothermal reservoirs and analogous hydro-thermal systems.

Entropy generation analysis of microrotating Casson’s nanofluid with Darcy–Forchheimer porous media using a neural computing based on Levenberg–Marquardt algorithm

PurposeThe purpose of this paper is to showcase the utilization of the magnetohydrodynamics-microrotating Casson’s nanofluid flow model (MHD-MRCNFM) in examining the impact of an inclined magnetic field within a porous medium on a nonlinear stretching plate. This investigation is conducted by using neural networking techniques, specifically using neural networks-backpropagated with the Levenberg–Marquardt scheme (NN-BLMS).Design/methodology/approachThe initial nonlinear coupled PDEs system that represented the MRCNFM is transformed into an analogous nonlinear ODEs system by the adoption of similarity variables. The reference data set is created by varying important MHD-MRCNFM parameters using the renowned Lobatto IIIA solver. The numerical reference data are used in validation, testing and training sets to locate and analyze the estimated outcome of the created NN-LMA and its comparison with the corresponding reference solution. With mean squared error curves, error histogram analysis and a regression index, better performance is consistently demonstrated. Mu is a controller that controls the complete training process, and the NN-BLMS mainly concentrates on the higher precision of nonlinear systems.FindingsThe peculiar behavior of the appropriate physical parameters on nondimensional shapes is demonstrated and explored via sketches and tables. For escalating amounts of inclination angle and Brinkman number, a viable entropy profile is accomplished. The angular velocity curve grows as the rotation viscosity and surface condition factors rise. The dominance of friction-induced irreversibility is observed in the vicinity of the sheet, whereas in the farthest region, the situation is reversed with heat transfer playing a more significant role in causing irreversibilities.Originality/valueTo improve the efficiency of any thermodynamic system, it is essential to identify and track the sources of irreversible heat losses. Therefore, the authors analyze both flow phenomena and heat transport, with a particular focus on evaluating the generation of entropy within the system.

Exploring Design Tradeoffs and Rate Gain Regions in Full-Duplex Wireless Communications

Conventional HD wireless networks operated by using distinct time slots or frequency (freq.) sub-bands for transmission and reception within the same family. Therefore, the wireless research community aims to develop FD operation to enable simultaneous transmission along with reception inside a single time/ freq. channel. This research aims to conduct an analytical investigation of the conditions under which real FD systems may attain higher data rates compared to analogous HD systems. The primary obstacle in real FD systems is to the uncancelled self-interference (SI) signal, which arises due to a confluence of hardware along with implementation defects. First, provide a signal model that encompasses the impact of notable impairments, including oscillator phase noise (PN), along with low-noise amplifier (LNA) noise figure, along with mixer noise, along with analog-to-digital converter quantization noise. The rate gain area (RGA) is examined in this research using the comprehensive signal model. A~1.2x to ~1.4x that of HD systems for short-range applications like class-3 Bluetooth. To get the same rate gain with Class-1 Bluetooth, −70dB in-band PN must be paired with 50dB passive SI suppression.

Reduced dimensional Monte Carlo method: Preliminary integrations.

A technique for reducing the number of integrals in a Monte Carlo calculation is introduced. For integrations relying on classical or mean-field trajectories with local weighting functions, it is possible to integrate analytically at least half of the integration variables prior to setting up the particular Monte Carlo calculation of interest, in some cases more. Proper accounting of invariant phase space structures shows that the system's dynamics is reducible into composite stable and unstable degrees of freedom. Stable degrees of freedom behave locally in the reduced dimensional phase space exactly as an analogous integrable system would. Classification of the unstable degrees of freedom is dependent upon the degree of chaos present in the dynamics. The techniques for deriving the requisite canonical coordinate transformations are developed and shown to block diagonalize the stability matrix into irreducible parts. In doing so, it is demonstrated how to reduce the amount of sampling directions necessary in a Monte Carlo simulation. The technique is illustrated by calculating return probabilities and expectation values for different dynamical regimes of a two-degrees-of-freedom coupled quartic oscillator within a classical Wigner method framework.

Shape matters: Convection and entropy generation in magneto-hydrodynamic nanofluid flow in constraint-based analogous annular thermal systems

This work analyzes the performance of annular thermal systems of distinct geometries to understand their shape impacts using a novel constraint-based methodology. This research fills the gap in the literature by analyzing the geometrical shape impact of magnetohydrodynamic CuO/water nanofluid flow on fluid flow, heat transfer, and thermodynamic irreversibility. Through computational simulations, the outcome results demonstrate that the circular annuli (Case 1 and Case 2) outperform the analogous square system in terms of fluid velocity, heat transfer, and irreversibility. The analysis is carried out for a range of Rayleigh numbers (Ra = 103 to 106), nanoparticle concentrations (ζ = 0 to 4%), magnetic fields (Ha = 0 to 100), and magnetic field inclinations (γ = 0° to 180°). Additionally, a significant improvement in heat transfer is observed by augmenting nanoparticles of the working fluid, while the magnetic field intensity plays a crucial role in controlling fluid flow and heat transfer. The study provides valuable insights into how various parameters affect the nanofluidic heat and flow characteristics of equivalent annular geometries and contributes to the development of more efficient and effective designs of thermal systems. The novelty of the study lies in its comprehensive approach in the use of a constraint-based methodology that matches the flow areas or cooling lengths while maintaining the same heating length to analyze the impact of geometric shapes on heat transport and accompanying irreversibility during MHD nanofluid flow. Furthermore, the energy-flux vectors are utilized to delve into the insights. The maximum value of heat transfer noted for Case 1 and Case 2 is approximately 7% and 11%, respectively, compared to the square annulus (Base Case). The inclusion of nanoparticles in the carrier fluid causes a significant enhancement in heat transfer by up to 11%, compared to pure fluid (ζ = 0).

A New Dissociative Galaxy Cluster Merger: RM J150822.0+575515.2

Galaxy cluster mergers that exhibit clear dissociation between their dark matter, intracluster gas, and stellar components are great laboratories for probing dark matter properties. Mergers that are binary and in the plane of the sky have the additional advantage of being simpler to model, allowing for a better understanding of the merger dynamics. We report the discovery of a galaxy cluster merger with all these characteristics and present a multiwavelength analysis of the system, which was found via a search in the redMaPPer optical cluster catalog. We perform a galaxy redshift survey to confirm the two subclusters are at the same redshift (0.541, with 368 ± 519 km s−1 line-of-sight velocity difference between them). The X-ray morphology shows two surface brightness peaks between the brightest cluster galaxies (BCGs). We construct weak-lensing mass maps that reveal a mass peak associated with each subcluster. Fitting Navarro–Frenk–White profiles to the lensing data, we find masses of M 200c = 36 ± 11 × 1013 and 38 ± 11 × 1013 M ⊙ h −1 for the southern and northern subclusters, respectively. From the mass maps, we infer that the two mass peaks are separated by 520−125+162 kpc along the merger axis, whereas the two BCGs are separated by 697 kpc. We also present deep GMRT 650 MHz data to search for a radio relic or halo and find none. Using the observed merger parameters, we find analog systems in cosmological n-body simulations and infer that this system is observed between 96 and 236 Myr after pericenter, with the merger axis within 28° of the plane of the sky.

In the beginning, there was the analogue. An alternative history of the beginnings of computer art

Since the late 1960s, the historiography of computer art has been developing a canon that is progressively broadening. However, this canon reveals significant blind spots, particularly due to the predominant success of digital computers leading to computer art being almost exclusively identified with digital technology. This identification overlooks other significant classes of computers, notably analogue and hybrid systems, leaving the contributions, artworks, and ideas of many early pioneers in the field unrecognized. Consequently, the history of art created with analogue and hybrid computers remains largely unexplored both in art history and media archaeology. This article seeks to illuminate this relatively obscure chapter of history by introducing the individuals and projects that utilized analogue computers, drawing on previously unknown historical sources. The aim is to underscore the historical significance of a technology that is currently experiencing a resurgence of interest in the field of computer science. The findings reveal that before the advent of artistic experiments with digital computers, analogue computers were the subject of pioneering exploration. The real-time intuitive operation of analogue computers was a unique advantage, foreshadowing a human-machine relationship now commonplace with digital technology. The narrative of the analogue computer constitutes an essential domain for understanding the diversity of computing technologies at the dawn of the computer age. Despite the scarcity of sources documenting these artistic endeavors, this article serves as a call to action for further research in this neglected area.

Bioenergetics of iron snow fueling life on Europa

The main sources of redox gradients supporting high-productivity life in the Europan and other icy ocean world oceans were proposed to be photolytically derived oxidants, such as reactive oxygen species (ROS) from the icy shell, and reductants (Fe(II), S(-II), CH4, H2) from bottom waters reacting with a (ultra)mafic seafloor. Important roadblocks to maintaining life, however, are that the degree of ocean mixing to combine redox species is unknown, and ROS damage biomolecules. Here, we envisage a unique solution using an acid mine drainage (AMD)-filled pit lakes analog system for the Europan ocean, which previous models predicted to be acidic. We hypothesize that surface-generated ROS oxidize dissolved Fe(II) resulting in Fe(III) (hydr)oxide precipitates, that settle to the seafloor as "iron snow." The iron snow provides a respiratory substrate for anaerobic microorganisms ("breathing iron"), and limits harmful ROS exposure since they are now neutralized at the ice-water interface. Based on this scenario, we calculated Gibbs energies and maximal biomass productivities of various anaerobic metabolisms for a range of pH, temperatures, and H2 fluxes. Productivity by iron reducers was greater for most environmental conditions considered, whereas sulfate reducers and methanogens were more favored at high pH. Participation of Fe in the metabolic redox processes is largely neglected in most models of Europan biogeochemistry. Our model overcomes important conceptual roadblocks to life in icy ocean worlds and broadens the potential metabolic diversity, thus increasing total primary productivity, the diversity and volume of habitable environmental niches and, ultimately, the probability of biosignature detection.