Exchange Mechanism Research Articles

Credibility of group manipulation in random assignments

For the random assignment problem, we introduce the notion of collusion-proofness that happens if the rule is immune to any collusion on misreporting preferences as it is either not profitable to form or profitable to betray. We characterize collusion-proofnessand prove that an assignment rule is collusion-proof if and only if it is strategy-proof and non-bossy. Therefore, the random serial dictatorship rule is immune to any collusive agreement between agents on preference misrepresentation, though it is not (weakly) group strategy-proof. This result gives us a possibility between collusion-proofness, ex-post Pareto efficiency, and equal treatment of equals. Furthermore, we proved that a large family of strategy-proof mechanisms called rank exchange mechanisms, à la Shende and Purohit (2023), are collusion-proof but group manipulable.

Robust graph mutual-assistance convolutional networks for semi-supervised node classification tasks

Graph convolutional networks (GCNs) have made substantial progress in semi-supervised learning. However, GCNs are sensitive to graph noise, making the reconstruction of imperfect graph structures essential for adapting GCNs to complex scenarios. Prevalent GCNs employ graph augmentation to generate reliable augmented graphs, thereby mining potential graph information. Since traditional GCN layers can only perform message passing independently within each graph, GCNs primarily concentrate on fusing information from the node embeddings independently learned by the reliable augmented graphs. Nevertheless, the neglect of cross-graph information exchange during message passing limits the model's inter-graph interactions ability. In this paper, we propose a GCN framework called Robust graph mutual-assistance convolutional networks (RamNet), which introduces cross-graph information exchange mechanisms into the GCN layers. First, RamNet employs a multi-metric topology augmentation strategy to generate a synthesized graph, thereby exploring more reliable information. Second, it learns inter-graph interaction information by achieving information exchange between the raw graph and the synthesized graph during message passing. Finally, in addition to utilizing a small amount of supervised information, it also captures rich self-supervision information by maximizing consistency relationship between input graphs. We conduct comprehensive experiments in both standard and noisy scenarios, highlighting the superior performance of RamNet.

A novel mechanism and model of hydrogen isotope exchange in vacancy considering nuclear quantum effects

Abstract Tritium (T) retention in plasma-facing materials (PFMs) raises significant radiological safety concerns and adversely affects the self-sustained burning of T in fusion reactors. Therefore, the removal of retained T from PFMs has become an urgent task. Hydrogen isotope (HI) exchange has proven to be an effective method for T removal. However, the microscopic mechanisms, particularly the role of isotope effects, remain insufficiently understood. For the first time, this work employs path integral molecular dynamics (PIMD) to account for the nuclear quantum effects of HIs and explore the microscopic mechanisms of HI exchange in tungsten (W) vacancies. Atomic-scale simulations reveal that the fundamental principle of HI exchange is the reduction in binding energy between HIs and vacancies as the defect filling level increases, involving two key processes: de-trapping and trapping. These processes are influenced by isotope effects, with pronounced differences observed at low temperatures. Notably, T exhibits a higher probability of de-trapping from vacancies compared to hydrogen (H), while vacancies demonstrate a stronger affinity for trapping H. In contrast, the isotope effect is less pronounced between deuterium (D) and H, leading to different exchange efficiencies between H and T, as well as between D and T. Based on these isotope effects, we proposed a detailed microscopic mechanism for HI exchange in vacancies and developed a T evolution model that accounts for variations in HI concentrations. This work advances our understanding of HI exchange for T removal applications and offers a more accurate assessment of T retention in future D-T environments.

Optimal Operation of Generation Company’s Participating in Multiple Markets with Allocation and Exchange of Energy-Consuming Rights and Carbon Credits

The proposal of the energy-consuming right (ECR) market may lead to generation companies (GenCos) facing the risk of being overcharged due to the inaccurate calculation of carbon emission reduction, since it claims the same credit as the carbon market does. To estimate the carbon emission reduction accurately for the GenCos that participate in electricity, carbon, and ECR markets simultaneously, this paper proposes a market framework where a flexible exchange mechanism between the ECR and carbon markets is specially considered. To investigate the influence of the allocation and exchange of ECR and carbon credits on the behavior of GenCos that participate in multi-type markets, a bi-level model based on the leader–follower game theory is proposed. In the upper level of the proposed model, a decision problem for maximizing the profit of GenCos is developed, which is especially constrained to the primary allocation of ECR and carbon credits. While the multi-type market clearing model and an exchange mechanism between the ECR and carbon credits are proposed in the lower level of the model. The bi-level problem is converted into the mathematical program with equilibrium constraints (MPECs) through the Karush–Kuhn–Tucker (KKT) condition to solve. The results illustrate that the interaction between the ECR market and the carbon market can improve the energy efficiency and reduce the carbon emissions of GenCos.

Implementation of network management in child protection policy: Analysis of mobilization strategy in Makassar City

This study aims to examine network management in the implementation of child protection policies in Makassar City, with a focus on mobilization strategies implemented by the Office of Women's Empowerment and Child Protection (DP3A). The research method used is a qualitative approach with data collection techniques through interviews, observations, and document studies. Informants in this study include representatives from DP3A, Makassar Police, Institute for Public Policy Studies (LSKP), and other related institutions. The results show that the mobilization strategy implemented by DP3A Makassar City, which includes motivating and rewarding networks, utilizing digital platforms, and cross-sector collaboration, has succeeded in increasing the effectiveness of child protection policy implementation. This success is in line with network management theory. DP3A Makassar City has managed to gather and utilize various resources, strengthen cross-sector collaboration, and accelerate responses to child abuse cases. The use of digital platforms and continuous evaluation are also key factors in the success of child protection efforts in Makassar City. This research provides recommendations for strengthening inter-agency coordination and collaboration through the establishment of regular coordination forums, developing efficient information and data exchange mechanisms, and establishing an integrated referral system. Future research is expected to develop a network management model or framework that can be adapted and applied in the context of child protection at the local, regional and national levels in Indonesia.

Depth-Resolved Profile of the Interfacial Ferromagnetism in CaMnO3/CaRuO3 Superlattices.

Emergent magnetic phenomena at interfaces represent a frontier in materials science, pivotal for advancing technologies in spintronics and magnetic storage. In this Letter, we utilize a suite of advanced X-ray spectroscopic and scattering techniques to investigate emergent interfacial ferromagnetism in oxide superlattices composed of antiferromagnetic CaMnO3 and paramagnetic CaRuO3. Our findings demonstrate that ferromagnetism exhibits an asymmetric profile and may extend beyond the interfacial layer into multiple unit cells of CaMnO3. Complementary density functional calculations reveal that the interfacial ferromagnetism is driven by the double exchange mechanism, facilitated by charge transfer from Ru to Mn ions. Additionally, defect chemistry, particularly the presence of oxygen vacancies, can play a crucial role in modifying the magnetic moments at the interface, possibly leading to the observed asymmetry between the top and bottom CaMnO3 interfacial magnetic layers. Our findings underscore the potential of manipulating interfacial ferromagnetism through point defect engineering.

Synthesis of some anion exchange resins for selective separation of 99Mo and 131I: A comparative study

ABSTRACT Amination of styrene-divinylbenzene (SDVB) copolymers is a traditional process for preparing strong anion exchange resins that can greatly improve their performance and applications. In the present investigation, poly(styrene-co-divinyl benzene) copolymers functionalized by various amino groups were synthesized by the amination route. The performance of synthesized exchange resins for the separation and recovery of active Mo(VI) and I(I) isotopes from their aqueous solutions was compared to that of three commercial ion exchange resins, used in the actual production of these radioisotopes in the Radioisotopes Production Facility. The morphology and structural properties of the synthesized copolymers as well as the commercial reference resins were characterized using FT−IR, SEM, TG, and XPS. The results demonstrate that the copolymer was successfully functionalized with amino groups, where trimethylamine produced amination greater than triethylamine. Furthermore, the thermal stability of synthesized anion exchanges was significantly higher than that of commercial beads. The synthesized polymer networks presented excellent radiation stability under applied experimental conditions. Compared to the reference resins, the synthesized co-polymeric beads showed enhanced adsorption capability for MoO4 2− and I− ions from an aqueous solution. Further, the uptake affinity of the networks aminated with trimethylamine for both radioisotopes, in optimal conditions, was greater than that of triethylamine aminated beads. The sorption mechanism was inferred through FT−IR and XPS analysis, and the results clarified that the separation of both radioisotopes was substantially related to the amine functional groups on the resin framework. The spectroscopic analysis illustrated that one molybdenum ion (in the form of MoO4 2−) was subjected to an ion-exchange interaction and two Cl− ions in the amine resin. A similar exchange mechanism was predicted for I− with Cl− ions. Further, the enhanced sorption of Mo(VI) could be additionally attained through coordination interactions with N atoms in the amine groups that have good chelating capability toward metal ions. The reusability performance of the synthesized exchange resins is better than that of the commercial reference resins, where they could be effectively regenerated for up to five cycles. Finally, this study presents a new technique for the separation and recovery of Mo(VI) and I(I) from irradiated low-enriched U-targets by employing highly promising amino-modified polystyrene-divinyl benzene microspheres.

Reaction-controlled triple O-isotope exchange trajectories during experimental alteration of olivine

The measurements and application of triple O-isotope system is a relatively new and powerful tool in tracing water-rock interaction, allowing to distinguish the temperature-dependent fractionation from the water amount that interacted with the rock. While the use of 18O/16O fractionation between minerals and fluids is well-established, most natural mineral-water reactions remain uncharacterized in terms of the triple isotope fractionation (17O/16O and18O/16O). The triple O-isotope approach is especially promising when it comes to natural samples, where an array of exchanged samples constrains the fluid endmembers. However, multiple exchange mechanisms are likely to occur between the reacting rock and water, which has not been investigated for triple O-isotopes. This study examines the triple O-isotope exchange between fluid and olivine experimentally, as this is a common reaction in nature and mechanisms/rates of reaction are societally important for CO2 sequestration. Water-olivine reaction in batch experiments was investigated at 275 °C at the saturated water vapor pressure of 59.5 bar. Reactants were loaded at mass ratios 0.6 to 2 and exchanged for periods of time between 44 and 1048 h. Local meteoric water and mantle olivine were taken as the initial reactants. The mineral products are brucite, serpentine and minor magnetite that occur as coatings on unreacted olivine as well as individual crystals. The progress of this dissolution-precipitation reaction was traced with the δD-δ′18O-Δ′17O values of reacted fluids and mineral products. After 1048 h of reaction, ∼50 wt% of unreacted olivine remained. In general, experimental data conforms with the triple O-isotope fractionation factors calculated for the co-existing secondary minerals forming in equilibrium with fluid. However, there is scatter and deviations in the reacted fluid compositions likely driven by the difference in relative rates of secondary mineral formation and changing modal and chemical mineral composition. We observe that brucite and magnetite form abundant aggregates early in the progress of the reaction, while chrysotile forms fine-grained coatings that become abundant later. Since individual mineral-water fractionation 103ln18/16α range over 10 ‰ with θ ranging between 0.51 and 0.53, the dynamic behavior of dissolution-precipitation mechanism during alteration of olivine is the main factor to the “wandering” triple O-isotope trajectories in our relatively short experiments.

Can informal lobbying be responsible? Evidence from Brussels

PurposeThis study links the notion of responsible strategic communication to the field of lobbying at the European (EU) level. It provides empirical findings on the relevance of informal interaction and communication in EU public affairs (PA). Focusing on functional expectations and uses tied to informality from an actors’ perspective, this study not only includes lobbyists and their attempts to gain influence on political actors but also attempts of lobbyists to control journalistic output through informal relationships and exchange mechanisms. The results are discussed with a view to further inform the concept of “responsible lobbying.”Design/methodology/approachBuilding on a theoretical background from strategic communication, informal politics and interest group research, findings from a qualitative content analysis of 43 semi-structured interviews with actors from PA (n = 27) and journalism (n = 16) at the EU level are reported, focusing on one policy case.FindingsThe study shows motives for establishing and using informality for both actor types. Functional expectations relate to a range of tasks at the core of the respective actors’ day-to-day activities: monitoring political developments, pre-negotiating policy options in protected, confidential spaces with political decision-makers, receiving relevant sectoral background information and “technical coaching” on legislative dossiers directed to journalists.Originality/valueStudies on lobbying have rarely been conducted from a strategic communications perspective, especially focusing the EU level. Albeit widely accepted, the understanding of lobbying and PA as an informal activity has not been scrutinized by academic research.

On the Chemical Stability of DNA-Stabilized Silver Nanoclusters.

DNA-stabilized silver nanoclusters (DNA-AgNCs) are atomically precise emitters, whose chemical stability is commonly defined by their stable optical response over time. Here, two isotopically pure versions (107Ag and 109Ag) of DNA2-[Ag16Cl2]8+ were mixed, and we demonstrate for the first time for DNA-AgNCs that silver atoms are continuously exchanged between individual clusters. This atom exchange was monitored by time-resolved mass spectrometry. Depending on the temperature, the exchange happens on a time scale of minutes to hours, while DNA2-[Ag16Cl2]8+ retains its ensemble spectroscopic features. Based on the time constants and the available crystal structure, we hypothesized the following exchange mechanism: formation of transient dimers followed by atom exchange between the two entities. A further and slower exchange of the swapped Ag atoms within the rest of the clusters occurs at a much slower time scale. Our findings shed new light on the meaning of chemical stability for this class of fluorophores and show that these systems can be structurally dynamic at the molecular level, while maintaining stable ensemble spectroscopic properties. Our results also explain why DNA-AgNCs are good sensors, as the dynamic nature of DNA-AgNCs allows for competing interactions, altering their optical response.

Toward a Universal Model of Hyporheic Exchange and Nutrient Cycling in Streams

AbstractIn this paper we demonstrate that several ubiquitous hyporheic exchange mechanisms can be represented simply as a one‐dimensional diffusion process, where the diffusivity decays exponentially with depth into the streambed. Based on a meta‐analysis of 106 previously published laboratory measurements of hyporheic exchange (capturing a range of bed morphologies, hydraulic conditions, streambed properties, and experimental approaches) we find that the reference diffusivity and mixing length‐scale are functions of the permeability Reynolds Number and Schmidt Number. These dimensionless numbers, in turn, can be estimated for a particular stream from the median grain size of the streambed and the stream's depth, slope, and temperature. Application of these results to a seminal study of nitrate removal in 72 headwater streams across the United States, reveals: (a) streams draining urban and agricultural landscapes have a diminished capacity for in‐stream and in‐bed mixing along with smaller subsurface storage zones compared to streams draining reference landscapes; (b) under steady‐state conditions nitrate uptake in the streambed is primarily biologically controlled; and (c) median reaction timescales for nitrate removal in the hyporheic zone are 0.5 and 20 hr for uptake by assimilation and denitrification, respectively. While further research is needed, the simplicity and extensibility of the framework described here should facilitate cross‐disciplinary discussions and inform reach‐scale studies of pollutant fate and transport and their scale‐up to watersheds and beyond.

Nucleosome flipping drives kinetic proofreading and processivity by SWR1

The yeast SWR1 complex catalyses the exchange of histone H2A–H2B dimers in nucleosomes, with Htz1–H2B dimers1, 2–3. Here we used single-molecule analysis to demonstrate two-step double exchange of the two H2A–H2B dimers in a canonical yeast nucleosome with Htz1–H2B dimers, and showed that double exchange can be processive without release of the nucleosome from the SWR1 complex. Further analysis showed that bound nucleosomes flip between two states, with each presenting a different face, and hence histone dimer, to SWR1. The bound dwell time is longer when an H2A–H2B dimer is presented for exchange than when presented with an Htz1–H2B dimer. A hexasome intermediate in the reaction is bound to the SWR1 complex in a single orientation with the ‘empty’ site presented for dimer insertion. Cryo-electron microscopy analysis revealed different populations of complexes showing nucleosomes caught ‘flipping’ between different conformations without release, each placing a different dimer into position for exchange, with the Swc2 subunit having a key role in this process. Together, the data reveal a processive mechanism for double dimer exchange that explains how SWR1 can ‘proofread’ the dimer identities within nucleosomes.

Study of structural, magnetic, and thermoelectric properties of rare earth-based CdCe2X4 (X = S, Se, Te) spinels for Spintronic and energy harvesting applications

Controlling the spin degree of freedom in electronics paves the way for novel approaches to employ, relocate, and store data at accelerated rates. In this regard, an in-depth examination of the structural, electronic, magnetic, and transport behaviour of CdCe2×4 (X = S, Se, Te) is undertaken. It is observed that ferromagnetic states exhibit higher energy release compared to antiferromagnetic states. Room temperature ferromagnetism is characterized by the Tc and spin-polarized density of states. The underlying mechanism in ferromagnetic behaviour is elicited in terms of crystal field energy, double exchange mechanism, exchange energies, and constants. The magnetic moment shift from Ce to other NM sites (Cd, X) is identified as a mechanism sustaining ferromagnetic character through electron exchange, thereby preventing clustering. Furthermore, the temperature-dependent thermoelectric properties are investigated, encompassing electrical and thermal conductivity, Seebeck coefficient, and power factor, recommending exploration of spinels as potential candidates for sustainable energy devices.

Experimental and molecular insights into ionic liquid-based recovery of valuable metals from spent lithium-ion batteries

A new type of collaborative extractants consisting of the ionic liquid (IL) 1-aminoprooyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide, ([APMIM][Tf2N]) and Cyanex 923 (C923) is first applied for selective extraction of valuable metals from spent lithium-ion batteries (LIBs). The one-stage extraction efficiencies of Co2+, Ni2+ and Mn2+ are up to 99.87 %, 97.74 %, 99.98 %, respectively, at the optimal conditions, and the high-purity Li+ was enriched at the raffinate. It is found that the extraction process follows the so-called “cation exchange mechanism”, and the molecular-level mechanism is revealed via quantum chemical (QC) calculations. The findings show that C923 plays the role of coordinating with metal ions, the cation of IL exchanges metal ions from the aqueous to organic phases, and the anion [Tf2N]- of IL can stabilize the complex species of metal ion-[Tf2N]--C923 in organic phase. This work provides new insights for the design of novel IL-based extractants for the recycling of spent LIBs.

Electron-lattice coupling effect to improve electrical transport properties of La0.7Ca0.3−xKxMnO3 (0.22 ≤ x ≤ 0.28) films via large-radius K doping

For uncooled infrared bolometers, the traditional thermal sensing materials such as vanadium oxide and amorphous silicon have a relative low value of temperature coefficient of resistivity (TCR). In contrast, perovskite manganese oxide films exhibit 3–5 times higher TCR values than traditional materials. The important challenge is to achieve both high TCR and peak TCR temperatures (Tk) at room temperature. Herein, La0.7Ca0.3−xKxMnO3 (LCKMO, 0.22 ≤ x ≤ 0.28) films were fabricated on La0.3Sr0.7Al0.65Ta0.35O3 (00l) substrates using a combined sol–gel and spin coating process. It was found that by optimizing the K doping amount at x = 0.24, on the one hand, double exchange mechanism becomes the strongest. On the other hand, with minimal lattice strain, electron scattering is inhibited, and the electron-lattice coupling effect improves. Furthermore, the film exhibits a dense surface structure and a uniform distribution of grains. Finally, TCR value reaches 15.95 % K−1 at the corresponding temperature of 283.28 K. Obviously, the prepared LCKMO films effectively combine the high TCR of La1−xCaxMnO3 with the high Tk of La1−xKxMnO3 by optimizing the K doping level. The results show that LCKMO films are a promising candidate for fabricating uncooled infrared bolometers.

Novel magnetic adsorbents based on oyster and clam shells for the removal of cadmium in soil

Magnetic adsorbents can effectively remove heavy metals from soil. However, the magnetization process may reduce availability of adsorption sites, making it challenging to balance magnetic and adsorption properties. In this study, oyster shell (OS) and clam shell (CS) material was magnetized by an improved chemical co-precipitation method. The organic matter in the shells was destroyed by calcination modification to expose new active sites, and calcinated ferro-magnetic adsorbent was produced with either ferrosodium EDTA (giving CEOS and CECS) or with iron citrate (for CCOS and CCCS). All four modified adsorbents reached adsorption equilibrium for Cd2+ in solution within 120 min, with maximum adsorption capacities ranging from 115.5 to 266.5 mg/g, giving high removal efficiencies for Cd2+. Adsorption by precipitation and cation exchange mechanisms was dominant, together contributing >60 % of all adsorption capacity, followed by complexation. When used for remediation of Cd-contaminated soil, CEOS demonstrated the best Cd removal efficiency, achieving removal rates of 46 % and 58 % for total and available Cd, respectively. This was mainly because CEOS had the highest magnetic recovery rate, of 98 %. CEOS maintained removal rates of 34 % for total Cd after regeneration and reuse three cycles, with recovery rates remaining above 90 %. Contaminated soil was treated with the novel adsorbents and in pot experiments with water spinach cultivation it was shown that both CEOS and CECS treatment significantly reduced Cd content (by up to 56 %). The magnetic adsorbents presented here demonstrate excellent performance to remove Cd from water and soil, and have promising application prospects.

Stable isotope analysis of faunal remains from Bronze Age Kaymakçı, Western Anatolia

This paper presents the results of stable carbon ( δ13C) and nitrogen ( δ15N) isotopic analysis of bulk bone collagen from faunal remains from the Bronze Age site of Kaymakçı in western Anatolia. We use the isotopic values in conjunction with zooarchaeological data and contextual archaeological information to examine human-environment interactions; in particular, animal management and husbandry. Middle and Late Bronze Age agricultural systems in western and central Anatolia remain poorly understood, and this research aims to contribute to rectifying this research gap. We obtained stable isotopic values from both wild and domestic species, including deer, hare, birds, catfish, dogs, pigs, caprids and cattle. The δ13C values range from −22.0‰ to −16.9‰ and the δ15N values range from 2.3‰ to 10.3‰. For cattle, the δ13C values suggest that some specimens were subject to different management strategies, likely related to feeding or herding patterns or even the movement of animals in and around the region through some exchange mechanism. There appears to be no fixed location or strategy for the management of caprids and, furthermore, there is evidence to suggest that the herding/management areas of some caprids overlapped with those of wild animals such as deer and hare. Variation in δ15N values for pigs may indicate that whilst some animals in the sampled assemblage were free-roaming, others were penned. For the pigs and some other herbivorous domesticated species variation in δ15N values may also point to the exploitation of the wetland areas around Lake Marmara.

Ultralong Compositional Gradient Perovskite Nanowires Fabricated by Source-Limiting Anion Exchange.

Anion exchange in halide perovskites offers prospective approaches to band gap engineering for miniaturized and integrated optoelectronic devices. However, the band engineering at the nanoscale is uncontrollable due to the rapid and random exchange nature in the liquid or gas phase. Here, we report a source-limiting mechanism in solid-state anion exchange between low-dimensional perovskites, which readily gives access to ultralong compositional gradient nanowires (NWs) with lengths of up to 100 μm. The exchanged NWs remain single-crystalline with intact morphology, while the halogen content exhibits an apparent gradient distribution, leading to a tapered energy band profile along a NW. In the dynamic study of anion behavior, it is shown that the spatial stoichiometric composition can be precisely tuned following Fick's law of diffusion. In addition, self-powered, spectrally resolved photodetectors incorporating multiple detection units within a single gradient NW are demonstrated. This work provides a feasible strategy for the realization of perovskite-based ultracompact optoelectronics, imaging sensors, and other miniaturized semiconductor devices.

Navigating the knowledge current: Unraveling the dynamics of knowledge transfer and learning in outsourcing for enhanced business streamlining

This study examines the pivotal role of knowledge transfer and continuous learning in optimizing outsourcing arrangements to achieve streamlined business operations. Amidst rapid globalization and technological advancements, outsourcing has evolved from a cost-reduction strategy to a complex mechanism involving core business functions. This dissertation explores the processes and dynamics of knowledge transfer between outsourcing partners, emphasizing their impact on operational efficiency. Using a mixed-methods approach, the research integrates qualitative insights from interviews and quantitative data from surveys to identify key factors such as trust, communication, and cultural alignment that enhance knowledge transfer effectiveness. Findings reveal a positive correlation between robust knowledge exchange mechanisms and improved business performance, supported by thematic analysis and regression models. Practical recommendations include fostering trust, implementing continuous learning programs, and aligning organizational cultures to optimize outsourcing partnerships. The study contributes to academic and practical understanding by addressing gaps in knowledge transfer literature, offering actionable strategies to mitigate challenges like knowledge loss and communication barriers. These insights enable organizations to enhance their outsourcing strategies, ensuring sustainable competitive advantage in dynamic global markets.

Cryo-EM structures of the zinc transporters ZnT3 and ZnT4 provide insights into their transport mechanisms.

Zinc transporters (ZnTs) act as H+/Zn2+ antiporters, crucial for zinc homeostasis. Brain-specific ZnT3 expressed in synaptic vesicles transports Zn2+ from the cytosol into vesicles and is essential for neurotransmission, with ZnT3 dysfunction associated with neurological disorders. Ubiquitously expressed ZnT4 localized to lysosomes facilitates the Zn2+ efflux from the cytosol to lysosomes, mitigating the cell injury risk. Despite their importance, the structures and Zn2+ transport mechanisms remain unclear. We characterized the three-dimensional structures of human ZnT3 (inward-facing) and ZnT4 (outward-facing) using cryo-electron microscopy. By combining these structures, we assessed the conformational changes that could occur within the transmembrane domain during Zn2+ transport. Our results provide a structural basis for a more comprehensive understanding of the H+/Zn2+ exchange mechanisms exhibited by ZnTs.