Abundance Of Zinc Research Articles

Impact of mineral and non-mineral sources of iron and sulfur on the metalloproteome of Methanosarcina barkeri.

Methanogens often inhabit sulfidic environments that favor the precipitation of transition metals such as iron (Fe) as metal sulfides, including mackinawite (FeS) and pyrite (FeS2). These metal sulfides have historically been considered biologically unavailable. Nonetheless, methanogens are commonly cultivated with sulfide (HS-) as a sulfur source, a condition that would be expected to favor metal precipitation and thus limit metal availability. Recent studies have shown that methanogens can access Fe and sulfur (S) from FeS and FeS2 to sustain growth. As such, medium supplied with FeS2 should lead to higher availability of transition metals when compared to medium supplied with HS-. Here, we examined how transition metal availability under sulfidic (i.e., cells provided with HS- as sole S source) versus non-sulfidic (cells provided with FeS2 as sole S source) conditions impact the metalloproteome of Methanosarcina barkeri Fusaro. To achieve this, we employed size exclusion chromatography coupled with inductively coupled plasma mass spectrometry and shotgun proteomics. Significant changes were observed in the composition and abundance of iron, cobalt, nickel, zinc, and molybdenum proteins. Among the differences were alterations in the stoichiometry and abundance of multisubunit protein complexes involved in methanogenesis and electron transport chains. Our data suggest that M. barkeri utilizes the minimal iron-sulfur cluster complex and canonical cysteine biosynthesis proteins when grown on FeS2 but uses the canonical Suf pathway in conjunction with the tRNA-Sep cysteine pathway for iron-sulfur cluster and cysteine biosynthesis under sulfidic growth conditions.IMPORTANCEProteins that catalyze biochemical reactions often require transition metals that can have a high affinity for sulfur, another required element for life. Thus, the availability of metals and sulfur are intertwined and can have large impacts on an organismismal biochemistry. Methanogens often occupy anoxic, sulfide-rich (euxinic) environments that favor the precipitation of transition metals as metal sulfides, thereby creating presumed metal limitation. Recently, several methanogens have been shown to acquire iron and sulfur from pyrite, an abundant iron-sulfide mineral that was traditionally considered to be unavailable to biology. The work presented here provides new insights into the distribution of metalloproteins, and metal uptake of Methanosarcina barkeri Fusaro grown under euxinic or pyritic growth conditions. Thorough characterizations of this methanogen under different metal and sulfur conditions increase our understanding of the influence of metal availability on methanogens, and presumably other anaerobes, that inhabit euxinic environments.

Mesoporous copper-doped δ-MnO2 superstructures to enable high-performance aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are competitive alternatives for large-scale energy-storage devices owing to the abundance of zinc and low cost, high theoretical specific capacity, and high safety of these batteries. High-performance and stable cathode materials in AZIBs are the key to storing Zn2+. Manganese-based cathode materials have attracted considerable attention because of their abundance, low toxicity, low cost, and abundant valence states (Mn2+, Mn3+, Mn4+, and Mn7+). However, as a typical cathode material, birnessite-MnO2 (δ-MnO2) has low conductivity and structural instability. The crystal structure may undergo severe distortion, disorder, and structural damage, leading to severe cyclic instability. In addition, its energy-storage mechanism is still unclear, and most of the reported manganese oxide-based materials do not have excellent electrochemical performance. Herein, we propose a copper-doped Cu0.05K0.11Mn0.84O2·0.54H2O (Cu2-KMO) cathode, which exhibits a large interlayer spacing, a stable structure, and accelerated reaction kinetics. This cathode was prepared using a simple hydrothermal method. The AZIB assembled using Cu2-KMO showed high specific capacity (600 mA h g−1 at 0.1 A g−1 after 75 cycles). The dissolution-deposition energy storage mechanism of Cu-KMO in AZIBs with double electron transfer was revealed using ex situ tests. The good electrochemical performance of the Cu2-KMO cathode fabricated by the doping strategy in this study provides ideas for the subsequent preparation of manganese dioxide using other strategies.

Unlocking zinc storage in silver vanadate structures for high-performance aqueous zinc batteries

Zinc-ion batteries (ZIBs) are being increasingly recognized as promising candidates for large-scale energy-storage systems owing to their stability in air, abundance of elemental zinc, low cost, and ease of handling. Although various cathode materials have been explored for ZIBs, silver vanadate stands out for its highly stable structure. However, the presence of silver in silver vanadate may hinder its electrochemical performance, necessitating activation over several cycles. In this study, we introduce an ion-exchange reaction to directly activate silver vanadate. The resulting ion-exchanged zinc vanadate demonstrates superior performance compared with silver vanadate, showcasing stable cycling behavior and high-rate capability. Remarkably, it maintains a capacity retention of 71 % even after 400 cycles. Analysis of the zinc intercalation mechanism reveals a combination of capacitive and diffusion-based processes contributing to energy storage in ZIBs. Post-cycling examinations reveal the presence of dendritic zinc anodes and confirm the stability and safety of the framework, with no silver migration to the anode side. These findings highlight the potential of ZIBs as next-generation energy-storage solutions and underscore the need for continued research in optimizing electrode materials and electrolytes for practical applications.

Utilization of sulfonated cellulose membrane for Zn ion hybrid capacitors

AbstractZinc ion hybrid capacitors (ZHCs) are regarded as sustainable energy storage devices, largely due to the abundance of zinc and its compatibility with aqueous electrolytes. Thick glass microfiber separators are commonly employed in ZHCs because they resist penetration by Zn dendrites, a prevalent issue in these devices. However, glass fiber separators not only reduce the volumetric energy but also raise environmental concerns due to their production processes, which generate significant amounts of greenhouse gases. In this study, we propose using a sulfonated cellulose membrane (SCM) derived from softwood cellulose nanofibrils as an eco‐friendly and sustainable separator for ZHCs. Utilizing this sulfonated cellulose membrane, we achieved 2000 h of continuous plating/stripping of Zn and more than 95% coulombic efficiency. Additionally, the efficacy of SCM as a separator was validated through the successful deployment of a Zn ion hybrid capacitor, which exhibited specific energies of 42 Wh/kg. The ZHC demonstrated remarkable cyclic stability, enduring over 10 000 cycles with minimal self‐discharge behavior. This study highlights the use of a cost‐effective, thin, mechanically robust, and highly cross‐linked cellulose nanofibrils membrane for ZHCs, showcasing its potential for broader utilization in various energy storage devices.

Water‐in‐Polymer Salt Electrolyte for Long‐Life Rechargeable Aqueous Zinc‐Lignin Battery

Zinc metal batteries (ZnBs) are poised as the next‐generation energy storage solution, complementing lithium‐ion batteries, thanks to their cost‐effectiveness and safety advantages. These benefits originate from the abundance of zinc and its compatibility with non‐flammable aqueous electrolytes. However, the inherent instability of zinc in aqueous environments, manifested through hydrogen evolution reactions (HER) and dendritic growth, has hindered commercialization due to poor cycling stability. Enter potassium polyacrylate (PAAK)‐based water‐in‐polymer salt electrolyte (WiPSE), a novel variant of water‐in‐salt electrolytes (WiSE), designed to mitigate side reactions associated with water redox processes, thereby enhancing the cyclic stability of ZnBs. In this study, WiPSE was employed in ZnBs featuring lignin and carbon composites as cathode materials. Our research highlights the crucial function of acrylate groups from WiPSE in stabilizing the ionic flux on the surface of the Zn electrode. This stabilization promotes the parallel deposition of Zn along the (002) plane, resulting in a significant reduction in dendritic growth. Notably, our sustainable Zn‐lignin battery showcases remarkable cyclic stability, retaining 80% of its initial capacity after 8000 cycles at a high current rate (1 A g−1) and maintaining over 75% capacity retention up to 2000 cycles at a low current rate (0.2 A g−1). This study showcases the practical application of WiPSE for the development of low‐cost, dendrite‐free, and scalable ZnBs.

Nutrient and anti-nutrient composition of durum, soft and red wheat landraces: Implications for nutrition and mineral bioavailability

Morocco possesses a significant genetic diversity of wheat cultivars in the form of landraces conserved by local farmers in several regions. This study aimed to investigate the nutritional and antinutritional composition of 75 flour samples of durum, soft, and red wheat landraces cultivated in Morocco in order to determine their nutritional value. The analysis concerned the quantification of total carbohydrates, starch, lipid, fatty acids, protein, amino acids, minerals, and dietary fibers using AOAC standards, and phytic acid and polyphenols using spectrophotometric assays. The antiradical activity was evaluated using a DPPH assay based on the chelating properties of the free radicals against minerals. The bioavailability of minerals was also estimated using molar ratios. On a dry weight basis, soft wheat flour contains higher amounts of carbohydrates (80.307 ± 0.634 g/100 g), while durum (14.007 ± 0.569 g/100 g) and red (16.452 ± 0.141 g/100 g) wheat flours contain more proteins, predominantly represented by glutamic acid and leucine. The mineral analysis revealed the abundance of iron, zinc, and calcium in soft, red, and durum wheat flours. Concerning lipids, the flour samples showed relatively low concentrations with a distinct predominance of oleic, linoleic, and palmitic acids. The quantification of antinutrients revealed the richness of red wheat flour in dietary fibers (1.763 ± 0.103 g/100 g), total polyphenols (301.609 ± 0.169 μg GAE/g), and flavonoids (80.091 ± 0.121 μg QE/g), while durum and soft wheat flours contain more tannins (60.138 ± 0.751 μg CE/g) and phytic acid (9.182 ± 0.391 mg/g), respectively. The phenolic extract derived from red wheat flour demonstrated significant antiradical activity against DPPH, with an IC50 value of 121.683 ± 0.229 μg/mL. The calculated (PA:Fe), (PA:Zn), and (PA:Ca) were below the critical values, indicating a low bioavailability of iron, zinc, and calcium in the wheat flour samples. The results showed significant differences (p < 0.05) in the amounts of nutrients and antinutrients among the studied wheat cultivars, leading to variations in the bioavailability of their mineral contents. These quantitative differences could be used to more accurately guide dietary recommendations and develop focused strategies for optimizing the bioavailability of minerals in wheat flour-based products.

Manganese homeostasis modulates fungal virulence and stress tolerance in Candida albicans.

Transition metals such as manganese provide considerable functionality across biological systems as they are used as cofactors for many catalytic enzymes. The availability of manganese is very limited inside the human body. Consequently, pathogenic microbes have evolved sophisticated mechanisms to uptake this micronutrient inside the human host to sustain their growth and cause infections. Here, we undertook a comprehensive approach to understand how manganese availability impacts the biology of the prevalent fungal pathogen, Candida albicans. We uncovered that manganese homeostasis in this pathogen modulates different biological processes that are essential for host infection which underscores the value of targeting fungal manganese homeostasis for potential antifungal therapeutics development.

Inkjet Printed Ti3C2 Electrodes for Anode-Free Zinc-Ion Battery

Additive manufacturing techniques are coming to the fore in many technological fields as cheaper and more versatile manufacturing routes alternative to the physical deposition methods. In particular, when miniaturized, thin-film or patterned structures are needed, Inkjet printing (IJP) has been widely demonstrated as suitable techniques to fabricate coated electrodes and microdevices for many applications including energy storage 1. In this regard, Zinc-ion batteries (ZIBs) are a promising alternative to the traditional lithium-ion batteries due to the abundance and low cost of zinc. In ZIBs, a metallic Zn chips is usually employed as the anode and a variety of materials, such as metal oxides or polymers, as the cathode. Zinc-ion batteries have the potential for high energy density and long cycle life, however they suffer of the well-known issue of Zn dendritic growth and poor efficiency of the plating-dissolution process 2. Ti3C2 MXene have been recently demonstrated as a high-performance “zincophilic” substrate for smooth and efficient zinc with high reversibility 3,4.In this work, we investigate inkjet-printed Ti3C2 MXene thin coatings as an ideal substrate for anode-free ZIBs. Stable aqueous Ti3C2 MXene inks were formulated and successfully inkjet printed on different substrates. The zinc metal nucleation phenomena on MXene 2D sheets were investigated by electrochemical potentiodynamic polarization techniques as well as galvanostatic ones, comparing them to a zinc metallic foil. Ex-situ electron scanning microscopy (SEM) analyses were employed to observe the plated Zn morphology after cycling at both low and high current density. Taking advantage of the smooth inkjet-printed Ti3C2 MXene coatings, electrochemical atomic force microscopy (EC-AFM) was used for the first time to perform in-operando investigation of the Zn plating process, allowing to reveal the early stage Zn plating mechanism on the as-printed Bibliography C. Li, F. Bu, Q. Wang, and X. Liu, Advanced Materials Interfaces, 9, 2201051 (2022).K. Wang, ACS Omega, 5, 10225–10227 (2020).J. M. Park et al., Journal of Energy Chemistry, 76, 187–194 (2023).Z. Gong et al., Journal of Colloid and Interface Science, 625, 700–710 (2022).

Exploring Greenockite: Occurrences and Geological Setting

Greenockite, mineral containing cadmium, is of significant scientific interest owing to its remarkable properties and potential applications in the field of science. It commonly forms in hydrothermal ore deposits as a secondary mineral due to complex cadmium-sulfur interactions influenced by temperature. Typically, it replaces zinc minerals like sphalerite, depending on the abundance of cadmium and zinc in hydrothermal fluids. Solid solubility in the ZnS CdS system occurs at high temperatures, with immiscibility observed under specific conditions. Greenockite forms at relatively low temperatures (100°C to 200°C) and is influenced by factors such as oxygen fugacity, hydrogen sulfide activity, and chloride ion content. Its hexagonal zinc blende structure results in diverse crystal forms, including rods, wires, and whiskers, often adorned with bismuth drops. Experimental studies have identified factors affecting its formation, such as solid solubility, precipitation mechanisms, pH levels, and fluid composition. Its vibrant coloration, attributed to cadmium concentration, varies from pale yellow to deep orange-red. Geologically, it is present in diverse settings, including metamorphosed zinc oxide mineralization, granites, fumaroles, pegmatites, and sediment-hosted Pb-Zn deposits, with a unique occurrence in gabbroic rock at the Babbitt deposit. In India, Greenockite has been identified in the Bagada orogenic gold prospect, situated within the Paleoproterozoic Mahakoshal belt, Central Indian Tectonic Zone (CITZ). Additionally, it is found in hydrothermal deposits of Pb-Zn mines of Zawar. It is exclusively encountered within specific geological settings, primarily as a secondary product. This paper provides a comprehensive exploration of its geological occurrences, distribution, associations, and exceptions.

Vanadium oxide/carbonized chestnut needle composites as cathode materials for advanced aqueous zinc-ion batteries

Owing to the abundance of zinc, inherent safety, simple assembly-operation and inexpensive nature, aqueous zinc ion batteries (AZIBs) as high-potential electrochemical energy devices hold marvelous development prospects. V2O3 as one of the promising AZIBs cathode materials has been severely limited due to its low electron conductivity and large volume variation during charge/discharge. In this study, the V2O3/carbonized chestnut needle (V2O3/CCN) composites were successfully prepared by a simple evaporation-induced self-assembly technique, using NH4VO3 and chestnut needle as raw materials. The introduction of biomass derived carbon not only provides a channel to ensure rapid electron/ion transport but effectively enhances the structural stability and electrical conductivity of V2O3. Benefiting from the above-mentioned positive effects, V2O3/CCN-15/2 electrode possess an exceptional discharge capacity of 431.96 mAh g−1 at 0.05 A g−1 and a fabulous cycle capability of 201.41 mAh g−1 (capacity retention of 94.27 %) at 3 A g−1 after 1000 cycles. The desirable electrochemical performance of V2O3/CCN-15/2 is proved by ex-situ testing methods. The insights provided by this investigation may contribute to the development of AZIBs cathode materials with competitive potential that are expected to play a paramount role in future large-scale energy storage.

Bi-layered calcium vanadium oxide as a cathode material for wet organic electrolyte-based rechargeable Zn-ion batteries

Zn-ion batteries attract considerable attention as a promising option for large-scale energy storage owing to their many benefits, including safety, high abundance of zinc, low fabrication costs, and ease of handling in air. However, to improve their effectiveness, three key technical challenges must be overcome: low electrolyte performance, metal dendrite formation, and a limited choice of host materials. This study introduces a new cathode material for Zn-ion batteries — double-layered Ca0.26V2O5·H2O — that exhibits outstanding performance in a wet organic electrolyte. The cathode material demonstrates an initial discharge capacity of 268.76 mAh g−1 at a rate of 0.2C and average operating voltage of 0.82 V (vs. Zn2+/Zn) with excellent capacity retention. A reversible Zn intercalation/crystal water extraction reaction is confirmed by conducting elemental and structural analyses, including powder X-ray diffraction. Furthermore, the results of bond valence sum calculations support the formation of a two-dimensional network of Zn-ion conduction pathways along the a-axis and b-axis, illustrating the electrochemical zinc intercalation into the wet organic electrolyte. Overall, this study not only introduces double-layered Ca0.26V2O5·H2O as a new cathode material for Zn-ion batteries but also provides valuable insights into the electrochemical zinc intercalation/crystal water extraction in wet organic electrolytes.

Carrier generation and collection in Zn3P2/InP heterojunction solar cells

Zinc phosphide (Zn3P2) has been lauded as a promising solar absorber material due to its functional properties and the abundance of zinc and phosphorous. In the last 4 decades, there has not been any significant improvement in the efficiencies of Zn3P2-based solar cells. This is vastly due to the limited understanding of how to tune its optoelectronic properties. Recently, significant progress has been made in the growth and characterization of the material, which has shed light on its potential. In this study, we report an energy conversion efficiency as high as 4.4% for a solar cell based on a polycrystalline Zn3P2/InP heterojunction. This device presents an open circuit voltage of 528.8 mV, 7.5% higher than the Zn3P2 homojunction record. We investigate the dominant recombination mechanisms within the film using different techniques to identify the key factors underpinning our device efficiency. In particular, we pinpoint that reduced carrier collection at the front of Zn3P2 is responsible for the reduced collection of high-energy photons. This allows us to suggest the design rules for next-generation Zn3P2-based heterojunction solar cells, which should allow us to go beyond the current conversion values.

A search for chemical anomalies of seven A-type stars

ABSTRACTWe present a chemical abundance analysis of seven A-type stars with no detailed chemical abundance measurements in the literature. High-resolution spectra of the targets – HD 2924, HD 4321, HD 26553, HD 125658, HD 137928, HD 154713, and HD 159834 – were obtained using the Coudé Echelle Spectrograph at the TÜBİTAK National Observatory. We determined the atmospheric abundances of the samples and measured the elemental abundances of C, N, O, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, and Gd. The masses of the stars were estimated based on their evolutionary tracks, and their ages were calculated using isochrones. We also calculated the radii of the stars. The abundance patterns of HD 4321, HD 125658, and HD 154713 were found to be in agreement with those of classical Am stars, with underabundant Ca and Sc, overabundant heavier elements, and moderate overabundance of iron-peak elements. We found that HD 137928 and HD 159834 have abundance characteristics similar to marginal Am-type stars. The elemental distributions of HD 2924 and HD 26553 are consistent with the pattern of normal A-type stars. The iron, nickel, and zinc abundances of HD 125658 and HD 137928 are significantly higher than those of other Am stars. These values suggest that they are among the most metal-rich Am stars.

Comparative Material and Mechanical Properties among Cicada Mouthparts: Cuticle Enhanced with Inorganic Elements Facilitates Piercing through Woody Stems for Feeding

Adult cicadas pierce woody stems with their mouthparts to feed on xylem, suggesting the presence of cuticular adaptations that could increase hardness and elastic modulus. We tested the following hypotheses: (a) the mouthpart cuticle includes inorganic elements, which augment the mechanical properties; (b) these elements are abundant in specific mouthpart structures and regions responsible for piercing wood; (c) there are correlations among elements, which could provide insights into patterns of element colocalization. We used scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to investigate mouthpart morphology and quantify the elemental composition of the cuticle among four cicada species, including periodical cicadas (Magicicada sp.). Nanoindentation was used to quantify hardness and elastic modulus of the mandibles. We found 12 inorganic elements, including colocalized manganese and zinc in the distal regions of the mandible, the structure most responsible for piercing through wood; nanoindentation determined that these regions were also significantly harder and had higher elastic modulus than other regions. Manganese and zinc abundance relates to increased hardness and stiffness as in the cuticle of other invertebrates; however, this is one of the first reports of cuticular metals among insects with piercing-sucking mouthparts (>100,000 described species). The present investigation provides insight into the feeding mechanism of cicadas, an important but understudied component of their life traits.

The protective effect and its mechanism for electrolyte additives on the anode interface in aqueous zinc-based energy storage devices

Aqueous-electrolyte-based zinc-ion batteries (ZIBs), which have significant advantages over other batteries, including low cost, high safety, high ionic conductivity, and a natural abundance of zinc, have been regarded as a potential alternative to lithium-ion batteries (LIBs). ZIBs still face some critical challenges, however, especially for building a reversible zinc anode. To address the reversibility of zinc anode, great efforts have been made on intrinsic anode engineering and anode interface modification. Less attention has been devoted to the electrolyte additives, however, which could not only significantly improve the reversibility of zinc anode, but also determine the viability and overall performance of ZIBs. This review aims to provide an overview of the two main functions of electrolyte additives, followed by details on six reasons why additives might improve the performance of ZIBs from the perspectives of creating new layers and regulating current plating/stripping processes. Furthermore, the remaining difficulties and potential directions for additives in aqueous ZIBs are also highlighted.

Effects of Cell Design Parameters on Zinc-Air Battery Performance

Zn-air batteries have attracted considerable attention from researchers owing to their high theoretical energy density and the abundance of zinc on Earth. The modification of battery component materials represent a common approach to improve battery performance. The effects of cell design on cell performance are seldom investigated. In this study, we designed four battery structures as follows. Cell 1: close-proximity electrode, Cell 2: equal-area electrode, Cell 3: large zinc electrode, and Cell 4: air channel flow. The effects of four factors: (1) carbon paste, (2) natural and forced air convection, (3) anode/cathode area ratio, and (4) anode–cathode distance were also investigated. Results showed that the addition of carbon paste on the air side of 25BC increased cell power density under forced air convection. Moreover, cell performance also improved by increasing the anode/cathode ratio and by decreasing the anode–cathode distance. These four types of cells were compared based on the oxygen reduction reaction electrode area. Cell 3 displayed the highest power density. In terms of volumetric power density, the proximity cell (Cell 1) exhibited the highest power density among the cells. Therefore, this cell configuration may be suitable for portable applications.

Non-LTE abundances of zinc in different spectral type stars and the Galactic [Zn/Fe] trend based on quantum-mechanical data on inelastic processes in zinc-hydrogen collisions

ABSTRACT We present a new model atom of Zn i-Zn ii based on the most up-to-date photoionization cross-sections, electron-impact excitation rates, and rate coefficients for the Zn i + H i and Zn ii + H− collisions. The latter were calculated using the multichannel quantum asymptotic treatment based on the Born–Oppenheimer approach. Non-LTE analysis was performed for the first time for lines of Zn i and Zn ii in the ultraviolet (UV) spectra of two very metal-poor reference stars: HD 84937 and HD 140283. We found consistent non-LTE abundance from the resonance Zn i 2138 Å line, the subordinate lines, and the lines of Zn ii. In both stars, non-LTE leads to 0.17 dex higher average abundance from Zn i, while, for Zn ii lines, non-LTE corrections are minor and do not exceed 0.06 dex. Using lines of Zn i in the high-resolution spectra, we determined the non-LTE abundances for a sample of 80 stars in the −2.5 ≤ [Fe/H] ≤ 0.2 metallicity range. The [Zn/Fe] versus [Fe/H] diagram reveals a dip, with [Zn/Fe] ≃ 0.3 in the most metal-poor stars, a close-to-solar value for [Fe/H] ∼−1.2, and increasing [Zn/Fe] up to 0.3 in the thick disc stars. The close-to-solar metallicity stars have subsolar [Zn/H] ≃ −0.1, on average. Non-LTE abundances of zinc were derived for the first time for seven reference F- to B-type stars. We provide a grid of the non-LTE abundance corrections.

Constructing robust zincophilic–channels on Zn anode for long-life Zn-ion batteries

Zn-metal anodes are promising candidates for aqueous Zn-ion batteries (ZIBs) owing to their high theoretical capacity, good electrochemical reversibility, and the natural abundance of zinc. However, dendrite growth and corrosion of Zn anodes during cycling hinder the practical application of ZIBs. In this study, we built robust zincophilic channels based on carboxylated hollow ceria (CHC) nanostructures on a Zn anode. With a robust three-dimensional nanostructure, the zincophilic–channel interfaces on the Zn anode present highly stable Zn plating/stripping cycling stability for up to 2000 h at a high current density of 3 mA cm−2. The resulting CHC@Zn//MnO2 full cell exhibits enhanced electrochemical performance.

Impact of Zn substitution on Fe(II)-induced ferrihydrite transformation pathways

Iron oxide minerals are ubiquitous in soils, sediments, and aquatic systems and influence the fate and availability of trace metals. Ferrihydrite is a common iron oxide of nanoparticulate size and poor crystallinity, serving as a thermodynamically unstable precursor to more crystalline phases. While aging induces such phase transformations, these are accelerated by the presence of dissolved Fe(II). However, the impact of trace metals on Fe(II)-catalyzed ferrihydrite phase transformations at ambient temperatures and the associated effects on trace metal speciation has seen limited study. In the present work, phase transformations of ferrihydrite that contains the trace metal zinc in its structure were investigated during aging at ambient temperature in the presence of two different Fe(II) concentrations at pH 7. X-ray diffraction reveals that low Fe(II) concentration (0.2 mM) generates hematite plus minor lepidocrocite, whereas high Fe(II) concentration (1.0 mM) produces a magnetite-lepidocrocite mixture. In both cases, a substantial fraction of ferrihydrite remains after 12 days. In contrast, zinc-free ferrihydrite forms primarily lepidocrocite and goethite in the presence of 0.2 mM Fe(II), with minor hematite and a trace of ferrihydrite remaining. For 1.0 mM Fe(II), magnetite, goethite, and lepidocrocite form when zinc is absent, leaving no residual ferrihydrite. Transformations of zinc-ferrihydrite produce a transient release of zinc to solution, but this is nearly quantitatively removed into the mineral products after 1 h. Extended X-ray absorption fine structure spectroscopy suggests that zinc partitions into the newly formed phases, with a shift from tetrahedral to a mixture of tetrahedral and octahedral coordination in the 0.2 mM Fe(II) system and taking on a spinel-like local structure in the 1.0 mM Fe(II) reaction products. This work indicates that substituting elements in ferrihydrite may play a key role in promoting the formation of hematite in low temperature systems, such as soils or sediments. In addition, the retention of zinc in the products of ferrihydrite phase transformation shows that trace metal micronutrients and contaminants may not be mobilized under circumneutral conditions despite the formation of more crystalline iron oxides. Furthermore, mass balance requires that the abundance and isotopic composition of iron oxide-associated zinc, and possibly other trace metals, in the rock record may be retained during diagenetic phase transformations of ferrihydrite if catalyzed by dissolved Fe(II).

The Abundances of Zinc and Copper in the Atmospheres of 78 Vir (A2p SrCrEu) and θ Leo (A2 IV)

Abstract Zinc and Copper abundances are rarely available for normal and Chemically Peculiar A stars because the strongest transitions of Zn ii and Cu ii fall in the mid-UV. Estimates of the abundances of zinc and copper are derived for 78 Vir (A2p SrCrEu) and θ Leo (A2 IV) using mean mid-ultraviolet spectra constructed by coadding individual spectra collected with the Long Wave Prime and Long wavelength Redundant cameras over the 18 yr of the IUE mission. The strong transition of Cu ii at 2135.98 Å is present in 78 Vir and θ Leo but definitely stronger in 78 Vir, whereas all Zn ii lines are blended. Spectral synthesis of the least blended lines yields estimates of the abundances of zinc and copper of about 4.92 and 4.95 respectively in θ Leo and 5.82 and 5.19 in 78 Vir (on a scale where log(H) = 12). There is no convincing evidence that these lines varied in the spectra analyzed for both stars.