Zn Oxide Research Articles

Bottom-up designing nanostructured oxide libraries under a lab-on-chip paradigm towards a low-cost highly-selective E-nose

BackgroundThe multisensor concept has been developed as a powerful alternative to well-known gas-analytical instrumentation for applications where a fast but accurate and reliable assessment of the environment is required. The concept follows a biology-inspired approach where the selectivity towards various gases/odors is attained via pattern recognition of multisensory signal vectors. Herein, we discuss how to design a selective multisensor library based on various metal oxide nanostructures like a lab-on-chip using a simple but efficient bottom-up growth of materials over the multi-electrode chip under robust dc electrochemical protocols. ResultsIn addition to a conventional growth of oxide layers over the metal electrodes, we show that the fine nanowall-like oxide structures appear as a quasi-matrixed percolation film over the SiO2 substrate surface in the inter-electrode gaps to constitute a chemiresistive film. We have tested two directions while applying the technique to grow Co, Ni, Mn, and Zn oxides to develop on-chip sensor arrays of, (i) monoxide type employing the oxide films with gradual change of growth time, and (ii) multi-oxide type based on the four oxides. The materials were thoroughly characterized by electron microscopy, X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy/mapping to prove the composition and structure. Among tested oxides, ZnO readily appears not only at the electric potential-targeted chip zone but also in other areas to dope the films for yielding heterojunctions with other oxides that enhances a variability of functional properties in the on-chip sensor array. The gas-sensing performance of the chips has been tested versus various chemically akin alcohol vapors at the sub- and low ppm range of concentrations in a mixture with air. SignificanceWe show that the grown oxide nanostructures exhibit a high-sensitive chemiresistive signal which allows one to build a multisensor vector signal, selective to the kind of alcohols, even at sub-ppm concentrations. Moreover, the multi-oxide library yields options for a superior selectivity under LDA metrics than the gradient-grown mono-oxide one due to the versatility of materials while the low-cost growth protocols remain to be the same in both cases. The delivered method to produce multisensor arrays allows one producing low-cost but efficient electronic nose units for numerous applications.

Sulfur and metal mobilization during the life cycle of an oceanic core complex: Implications for seafloor massive sulfide deposits formation at slow and ultra-slow spreading ridges

Seafloor massive sulfide (SMS) deposits at slow and ultra-slow spreading ridges are often spatially related to, or hosted in oceanic core complexes (OCCs). The specific oceanic crust architecture, magmatism, hydrothermal fluid circulation and lithologies at OCCs, however, imply different S and metal (e.g. Cu, Zn, Co, Ni) fluxes relative to well-structured oceanic crust at-fast spreading ridges and which are not yet fully constrained. The study of S and metal distribution in the ODP Hole 735B deep drill core from the Atlantis bank allows to understand these fluxes along detachment faults and to better constrain the source zone of S and metals for OCC-related SMS deposits. Significant depletion of S, Cu, Zn and Ni are observed within the upper 250 m of the drill core where intense deformation and hydrothermal fluid circulation occurred. During the complex tectono-magmatic-hydrothermal evolution of the Atlantis Bank, four important stages are recognized for S and metal mobilization: 1) magmatic stratification leading to a higher proportion of sulfide-rich and S, Cu, Zn and Co fertile oxide gabbros in the root zone of the Atlantis Bank detachment, 2) high temperature ductile deformation leading to magmatic sulfide reworking and onset of sulfide leaching with limited metal mobilization, 3) extensive sulfide leaching and metal mobilization during amphibolite to greenschist facies metasomatism and, 4) late stage secondary sulfide precipitation and S enrichment during low temperature fluid circulation. Mass balance calculations from the source zones of the Atlantis Bank detachment highlights that metal mobilization during hydrothermal alteration of gabbroic rocks along detachment faults can fully account for the formation of OCC-related SMS deposits at slow and ultraslow spreading ridges. The Atlantis Bank detachment system, however, is gabbroic-dominated and represent the magmatic end-member of OCCs and further work is necessary for understanding metal fluxes in ultramafic-dominated detachment systems.

Nanostructural evolution by applying various fuels in combustion design of CuZnAl mixed-oxides over HZSM-5 used in one-step production of CH3–O–CH3

The influence of different fuels (urea, ethylene glycol and citric acid) in combustion-based design of nano-structured CuO–ZnO–Al2O3/HZSM-5 catalyst was investigated. The catalytic performance were evaluated in a single step production of dimethyl ether form syngas. The X-ray diffraction, Field emission scanning electron microscopy, Transmission electron microscopy, Energy-dispersive x-ray, Temperature Programmed Reduction-H2, N2 Adsorption and Desorption isotherms and Fourier-transform infrared spectroscopy techniques were used to characterize physico-chemical properties of prepared nanocatalysts. The X-ray diffraction results clarified that application of citric acid increased relative crystallinity of Cu and Zn oxides existed in catalyst structure. The Fourier-transform infrared spectroscopy results demonstrated that the zeolite structure was not destroyed after CuO–ZnO–Al2O3/HZSM-5 introduction. The Field emission scanning electron microscopy and Transmission electron microscopy images illustrated that the nanocatalyst synthesized with citric acid has the highest porosity and less population of particle agglomerations. The highest amount of surface area was obtained when citric acid was used as fuel. According to Temperature Programmed Reduction-H2 profiles, the reducibility of nanocatalyst synthesized with citric acid is higher than other samples. The activity of the fabricated nanocatalysts for syngas to Dimethyl ether process were tested at temperature and pressure range of 225–300 °C and 10–40 bar, respectively. Using citric acid as fuel led to achieve greater amount carbon monoxide conversion and Dimethyl ether yield. Furthermore, stability test represented that the activity of this nanocatalyst remained quite stable during 1060 min.

A study on the high mobility and improved reliability of pr-doped indium zinc oxide thin film transistors

Abstract It is generally accepted that there is a trade-off relationship between mobility and stability for oxide thin film transistor (TFT) devices. Different doping ratios of Ln praseodymium (Pr) into indium (In) zinc (Zn) oxide have been employed as the active layer to get 1# and 2# amorphous oxide semiconductor (AOS) TFTs in this work. The 1#-based TFTs exhibited a high mobility of 49.84 cm2 V−1 s−1 due to the increased concentration of In. By further elevating the Pr doping ratio and adjusting In/Zn ratio of the film, the 2#-based TFT obtained both a good mobility of 26.65 cm2 V−1 s−1, and a promising stability, showing a positive-bias temperature stress stability of ΔV TH = 1.56 V and a negative-bias temperature illumination stress stability of ΔV TH = −1.47 V. It was revealed that the low energy charge transfer state of Pr in 2# film absorbs the visible light, leading to suppressed photo-induced carriers and thus a good illumination reliability of the 2#-based TFTs. In practice, the LCD panel based 2# ACT TFT shows a well stable performance even under 10 000-nit illumination. The result indicates a promising strategy to accelerate the commercialization of AOS TFTs to large-panel display production.

CO2 hydrogenation over Fe-Mn-Zn spinel oxide nanohybrids precatalysts

Catalytic CO2 hydrogenation using green hydrogen is a promising approach for mitigating CO2 emissions and utilizing CO2 as a feedstock. While Fe-based catalysts produce long-chain hydrocarbons under high-pressure CO2 hydrogenation reactions, the C2+ hydrocarbon yield tends to be insufficient at low-pressure conditions over the catalyst. This study reports the enhancement of light olefin selectivity of CO2 hydrogenation over Fe-based catalysts at low pressure via nanoscale hybridization with manganese (Mn) and zinc (Zn) oxides. The resulting hybridized catalyst exhibited distinctive performance in terms of CO2 hydrogenation to light olefins at relatively low pressure (0.7 MPa) in terms of CO2 conversion rate and C2–C4 yield with high olefin rates. Mn and Zn incorporation in Fe oxide decreased the reduction temperature, forming more Fe carbide phase. CO2 adsorption capability at relevant temperatures seems to be improved when Mn and Zn are present. This mixed oxide precatalyst approach can be extended to other elements.

Effects of dietary calcium and microbial phytase on the bioavailability of two sources of zinc in broilers

ABSTRACT 1. The objective of this study was to test the effect of microbial phytase and calcium (Ca) levels on the Zn bioavailability depending on the Zn source. 2. A total of 144, one-day-old broilers received a diet containing 40 mg Zn/kg for 1 week. They were then assigned to one of the eight experimental treatments during 2 weeks. Diets contained 27 mg native Zn and were formulated according to a 2 × 2 × 2 factorial design with two added Zn sources (23 mg Zn/kg), sulphate (ZnSO4) or oxide (ZnO); two dietary Ca levels of either 6 (low) or 10 g/kg (moderate); and two microbial phytase levels, of either 0 or 750 phytase unit/kg. 3. Moderate Ca plus phytase improved body weight gain (BWG) and low Ca level without microbial phytase decreased tibia weight (Ca × Phy; p = 0.049). Zinc oxide resulted in a higher tibia development (i.e. tibia weight and length; p < 0.05) and BWG (p = 0.009) and lower FCR (p < 0.001) compared to ZnSO4. 4. Phytase improved tibia Zn concentration especially in birds given ZnSO4 compared to ZnO (Zn × Phy; p = 0.049). Moderate Ca diets improved tibial characteristics and Zn deposition compared to low Ca diets (p < 0.05). 5. Soluble Zn in the gizzard increased in the presence of phytase (p = 0.011), while higher dietary Ca reduced this in birds receiving ZnO (p = 0.004). In the jejunum, Zn solubility was higher with phytase (p = 0.008). 6. Under the conditions of this study, dietary levels of Ca and microbial phytase affect Zn availability in broilers more than the Zn source.

Oxides improve the strength of Zn-0.5Mn-0.5Mg alloys proceeded by laser powder bed fusion

Laser powder bed fusion has recently been adopted to fabricate biodegradable Zn alloys. But the mechanical properties need to be further improved to meet the requirements for natural bone implants. In this study, a ternary Zn-0.5Mn-0.5Mg biodegradable alloy is prepared by laser powder bed fusion technique. The as-printed sample shows a large compressive yield strength of 267 MPa and considerable ductility that the sample maintains its integrity after 50 % compression. The improved strength is mainly attributed to the formation of brittle Zn oxides, Mn oxides and Mg oxides which induce lattice distortion. These oxides fragment easily during the compression and reduce the stress concentration, resulting in significant ductility. More importantly, the as-printed sample shows a moderate degradation rate of 0.08 mm/year after immersing in the simulated body fluid solution for 7 days. In addition, the sample has MC3T3-E1 cell viabilities higher than 75 %, showing no-toxicity characteristic. This study demonstrates that laser powder bed fusion Zn-Mn-Mg alloy is a promising candidate for biodegradable materials and proposes a novel route to tailor the mechanical properties of additive-manufactured Zn alloys by oxides compositing.

Cu-ZnO Embedded in a Polydopamine Shell for the Generation of Antibacterial Surgical Face Masks.

A new easy protocol to functionalize the middle layer of commercial surgical face masks (FMs) with Zn and Cu oxides is proposed in order to obtain antibacterial personal protective equipment. Zinc and copper oxides were synthesized embedded in a polydopamine (PDA) shell as potential antibacterial agents; they were analyzed by XRD and TEM, revealing, in all the cases, the formation of metal oxide nanoparticles (NPs). PDA is a natural polymer appreciated for its simple and rapid synthesis, biocompatibility, and high functionalization; it is used in this work as an organic matrix that, in addition to stabilizing NPs, also acts as a diluent in the functionalization step, decreasing the metal loading on the polypropylene (PP) surface. The functionalized middle layers of the FMs were characterized by SEM, XRD, FTIR, and TXRF and tested in their bacterial-growth-inhibiting effect against Klebsiella pneumoniae and Staphylococcus aureus. Among all functionalizing agents, Cu2O-doped-ZnO NPs enclosed in PDA shell, prepared by an ultrasound-assisted method, showed the best antibacterial effect, even at low metal loading, without changing the hydrophobicity of the FM. This approach offers a sustainable solution by prolonging FM lifespan and reducing material waste.

Synergetic Combination of Carbon Xerogels, Graphene Oxide and nano‐ZnO for Aqueous and Organic Supercapacitors

Three‐dimensional carbon xerogels were synthesised via a facile approach that included the use of ZnO nanostructures both as a templating agent and as a catalyst for resorcinol–formaldehyde resin polymerisation simultaneously. Graphene oxide (GO) served as a stabilising agent during the drying and pyrolysis processes, avoiding the collapse of structure and improving the area surface. The method enabled the asobtained materials to possess optimised 3D porous structures for energy‐storage devices, such as wires or spaghetti‐like structures. Also, a high BET surface area was obtained (1661 m2•g−1) without using an additional activating agent. This great surface area improved the specific capacitance compared to materials without GO (358.1 F•g−1 vs 170.4 F•g−1). The carbon‐containing devices derived from resorcinolformaldehyde resin, GO, and Zn oxide showed better performance than the devices without GO. In particular, the sample that contained 2.5% of GO in the synthesis showed a specific capacitance of 166.6 F•g−1 at 0.5 A•g−1 and remained at ∼120 F•g−1 at 5 A•g−1. Also, it showed interesting energy density values at 0.5 A•g−1 (14.8 Wh•kg−1) and a power density of 200.7 W•kg−1. This reveals that the synthesis process made it possible to obtain composite materials with large surface areas without using a supercritical drying process.

Synthesis of NiZn-based paddle-wheel metal-organic framework and its use as a catalytic precursor for ethylene dimerization

A bimetallic pillared-layered MOF based on Ni and Zn with improved catalytic activity was synthesized and applied in the ethylene oligomerization reaction. According to the XANES spectra, the MOF possesses Ni in the 2+ oxidation state, a well-known active catalytic precursor in oligomerization systems. In addition, Ni and Zn oxide or metallic species were not identified, indicating the absence of impurity phases. µ-XRF and SEM-EDS techniques showed the homogeneous distribution of Ni and Zn species across the SBUs of the bimetallic MOF. Ni/Zn-MOF was applied in the ethylene oligomerization reaction using EASC as the co-catalyst, and the results were compared to its monometallic counterpart Ni-MOF. The bimetallic material Ni/Zn-MOF obtained a TOF corresponding to 135 ×103 h−1, which accounts for a 60 % increase in the catalytic activity achieved by Ni-MOF (85 ×103 h−1) under 15 bar of ethylene in a Parr reactor. Moreover, the results obtained in this work are remarkable compared to literature reports for Ni-based MOFs, demonstrating that the co-catalyst employed plays an important role in the catalytic activity. However, Ni/Zn-MOF showed a lower selectivity to α-C4 oligomers (36 %) against 58 % obtained by Ni-MOF. According to the reuse tests conducted, the bimetallic MOF can be reused for up to two reactions (under 5 bar ethylene in a glass reactor), although presenting a considerable loss in activity due to the formation of metallic Ni.

Comparison of Cobalt-Based Vs. Cobalt-Free Infiltrated Nano-Catalyst Cathodes for Low Temperature Solid Oxide Cells

Tailoring inexpensive cathode materials which demonstrate high catalytic activity at lower temperature is crucial for the deployment of solid oxide cells as a next generation premier clean energy source.1 Cobalt is a crucial component and widely used in the most state-of-the-art cathodes of many types of batteries, fuel cells, and electrolysis cells.2 However, due to supply chain issues, replacement of cobalt (which is the most frequently used electrocatalyst to facilitate the oxygen reduction reaction) with other transition metals that are far more available, cheaper, and have less geopolitical, environmental, and social concerns have been explored in this work.In order to overcome the lethargic oxygen reduction reaction (ORR) kinetics, various transition metal oxide electrocatalysts (Ni, Fe, and Zn) and Co (for baseline comparison) were infiltrated on porous scaffold backbone support along with SrO and PrOx. This scalable spray coated porous scaffold of mixed ionic electronic conductor (MIEC) Gd0.1Ce0.9O2- δ (GDC) electrolyte material increases triple phase boundary for ORR reaction. SEM images shown in Figure 1(a) and 1(b) confirms nano-catalyst formation inside scaffold pores.At first, multiphase Co oxide-based nano-catalysts were tested on symmetric cells for baseline data, which demonstrated an area specific resistance (ASR) of 0.08 Ωcm2 at 650°C. Ni, Fe and Zn oxides were investigated as potential replacement electrocatalysts for CoOx because they exhibited similarly low ASR on symmetric cells in the range of 0.08 to 0.16 Ωcm2 at 650°C. To further assess their ability to perform as electrocatalysts for ORR, solutions of these transition metal nitrates were infiltrated, and heat treated to form oxides into SOFC cathode scaffolds and their performance in solid oxide fuel cell operating conditions was characterized. At optimal infiltration loading, Fe and Zn exhibited peak power density of 1.0 W/cm2 and 0.5 W/cm2 with polarization ASR of ~0.03 Ωcm2 and ~0.06 Ωcm2 respectively at 650°C as shown in Figure 1(c). Fe and Zn are considered relatively non-toxic, and are very cheap, however, further optimization will be required for enhanced performance.Conversely, Ni and Co as infiltrated nano-catalyst cathodes both showed extremely low polarization ASR of ~0.01 Ωcm2 with peak power density of 1.7 and 1.9 W/cm2 respectively at 650°C, as shown in Figure 1(c). Cobalt-free Ni based cathode demonstrated remarkably high peak power density of 1 W/cm2 and 1.5 W/cm2 at 550°C and 600°C respectively. Further exploration of cobalt-free, electrocatalytically active materials may open doors to new opportunities for systems like regenerative fuel cells that can operate both as a fuel cell and electrolysis cell with integrated system for energy conversion, and storage.3 Wachsman, E. D., & Lee, K. T. (2011). Lowering the temperature of solid oxide fuel cells. Science, 334(6058), 935– https://doi.org/10.1126/science.1204090.Olivetti, E., Ceder, G., Gaustad, G., & Fu, X. (2017). Lithium-Ion battery supply chain considerations: Analysis of potential bottlenecks in critical metals. Joule, 1(2), 229–243. https://doi.org/10.1016/j.joule.2017.08.019.Thangarasu, S., Dhanabalan, K., Roh, S., Kim, S. W., Park, K., Jung, S., Kurkuri, M. D., & Jung, H. (2017). A comprehensive review on unitized regenerative fuel cells: Crucial challenges and developments. International Journal of Hydrogen Energy, 42(7), 4415–4433. https://doi.org/10.1016/j.ijhydene.2016.10.140. Figure 1

Deposition Kinetics and Characteristics of Peald Igzo Films Using Tetrahydrofuran-Adducted in & Ga Precursors

As the down-scaling of semiconductor materials, silicon compatible emerging materials have extensively researched for next generation display and 3D structured devices. In particular, oxide semiconductors are considered a promising candidate for backplane applications in display. Among them, indium-gallium-zinc oxide (IGZO) using plasma enhanced atomic layer deposition (PEALD) has excellent properties, like high mobility, low leakage current, high transparecy and low temperature processablility. However, conventional precursors for IGZO still have some prolems to solve such as low deposition rate, low thermal stability and high price. In this study, we developed indium precursor (Trimethylindium Tetrahydrofuran, DIP-4) and gallium precursor (Trimethylgallium Tetrahydrofuran, DGP-2) to overcome the shortcomings of the conventional In & Ga precursors. ALD characteristics of the films deposited using the newly developed the precursors were confirmed through the source feeding time saturation and linearity. Furthermore, the incubation time of In, Ga and Zn oxide films according to the different bottom layer was respectively verified and calculated using the developed DIP-4, DGP-2 and commercially used DEZn. In order form a multilayer IGZO thin film, application of the incubation factors at IGZO process were experimentally demonstrated. Thickness of the IGZO films can be easily controlled through modulation of the incubation factors. The physical and chemical properties of the films were analyzed by X-ray diffraction, X-ray reflectrometer, X-ray photoelectron spectroscopy, transmission electron microscope. Figure 1

An In Vitro and In Silico Study of Luteolin-Loaded Zinc Oxide Nanoparticles: Enhancing Bioactivity and Efficacy for Advanced Therapeutic Applications Against Cariogenic Microorganisms.

Introduction Recent studies have explored alternative methods to enhance caries prevention and treatment.Luteolin compound has been noted for its antimicrobial properties, while zinc nanoparticles (Zn NPs) are recognized for their potent antibacterial effects. This study investigates the synthesis, characterization, and antimicrobial efficacy of luteolin-loaded Zn oxide NPs (Luteo-ZnONPs) against cariogenic bacteria. By combining the biofilm-targeting capabilities of luteolin with the antimicrobial properties of Zn NPs, we aim to explore a novel approach for dental caries management. Methods Luteo-ZnONPswere synthesized and characterized using ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopy, confirming their successful formation and stability. Antimicrobial efficacy was assessed through minimum inhibitory concentration (MIC), demonstrating effectiveness against cariogenic bacteria such asEscherichia coli,Enterococcus faecalis, Pseudomonas aeruginosa, and Streptococcus mutans in different concentrations.The agar well plate method was employed to analyze the growth inhibitory effect of Luteo-ZnONPs (50 and 100µg/ml, respectively). Streptomycin (100µg/ml) was used as apositive control. The results (zone of inhibition (ZOI) in millimeter, mm) were represented as mean± standard deviation.One-way analysis of variance (ANOVA) was employed to detect the significance (p < 0.05) between the groups. Cytotoxicity was analyzed using the3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assayagainst MG63 cells, and doxorubicin was used as a positive control.Wilcoxon rank test was used for the statistical method. Gyrase Bwas downloaded from Protein Data Bank (PDB id: 6F86) and docked against luteolin using Autodock software (version 4.2).The binding score was presented as kcal/mol in table format. Results Characterization results showed that UV-vis spectroscopy revealed characteristic peaks, indicating the successful synthesis and stability of Luteo-ZnONPs. FTIRspectroscopy confirmed the presence of functional groups from luteolin compound interacting with the Zn NPs. It showed effective inhibition againstE. coli on 50µg/ml as 12.45 mm as ZOI and increased with concentration (100 µg/ml as 17.13 mm).It showed minimal ZOI onE. faecalis(8.12, 12.21 on 50 and 100µg/ml, respectively). The cytotoxicity of Luteo-ZnONPs was lesser than doxorubicin on MG63 cells with statistical high significance (p < 0.0014). These results showed thatLuteo-ZnONPs had effective antimicrobial nature againstEnterococcusfamily. Thus, gyrase BfromE. coliwas selected for the molecular docking analysis. The catalytic tunnel in gyrase B (E. coli, PDB: 6F86), influenced by Luteo-ZnONPs, indicated potential for novel, broad-spectrum antimicrobials via selective inhibition at conserved active sites. Conclusion The agar well plate and MIC confirmed that Luteo-ZnONPs exhibited potent antibacterial activity, especiallyat higher concentrations compared to streptomycin.One- way ANOVA demonstrated significant differences in antibacterial efficacy between treatments, validating its superior performance.Its strong interaction onin silicolevel showed the targeted mechanism of action. Luteo-ZnONPs showed lesser toxicity than doxorubicin on MG63 cells. These findings underscore the potential of its broad spectrum antimicrobial nature paving the way for its development into innovative, nontoxic therapeutic solutions.

Effects of reducing copper and zinc supplementation on the performance and mineral status of fattening pigs

Pig manure with high copper (Cu) and zinc (Zn) concentration is applied to the soil, and these trace minerals can accumulate in the topsoil and decrease its fertility. Thus, adjusting concentrations of Cu and Zn in pig diets below current maximum allowance can prevent this risk. Reduction of dietary concentrations of Cu and Zn reduces their faecal excretion since only a small portion is retained in the pig’s body. The aim of this study was to evaluate the effects of reducing concentration of dietary Cu and Zn or withdrawing their supplementation on the performance and mineral status of fattening pigs. Four dietary treatments were compared: a basal diet (WS; withdraw supplementation), with no Cu or Zn supplementation (5 and 29 mg/kg of native Cu and Zn, respectively); intermediate concentration (OINT), supplemented with Cu and Zn oxides to obtain mean dietary concentration of 7.4 and 47.5 mg/kg of Cu and Zn, respectively; and two diets supplemented with oxides (OREG) or sulphates (SREG) at concentration similar to European Union limits (i.e. 25 and 120 mg/kg of total Cu and Zn, respectively), as commonly used on commercial farms. Ninety-six pigs (24.3 ± 3.3 kg BW) were each assigned to one of the four treatments and reared in individual pens for 14 weeks (up to 110.3 ± 8.9 kg BW). Animal performances were measured, and samples of plasma (on day 1 and day 41 of experimentation and at slaughter), bones and the liver (at slaughter) were collected from all pigs. Faecal samples were collected from all pigs every 3 weeks to determine the Cu and Zn excretion. Over the entire experiment, neither the concentration nor the source of Cu and Zn influenced feed intake, BW or the feed conversion ratio. Plasma Cu and Zn concentrations were not influenced by the treatment but increased as the age of the pigs increased. Liver Cu concentration increased (P < 0.05) as dietary concentrations increased (OREG> WS). Neither the concentration nor the source of Cu and Zn influenced bone Cu and Zn concentration or physical bone parameters. However, SREG had a higher maximum load until bone breaking (P < 0.05) than OREG. As expected, faecal excretion of Cu and Zn decreased (P < 0.01) as dietary concentration decreased. Dietary Cu and Zn can be reduced without decreasing the performance or mineral status of pigs, and these results should be validated on commercial farms that have more challenging health conditions.

Enhanced Adsorption of Arsenate from Contaminated Waters by Magnesium-, Zinc- or Calcium-Modified Biochar—Modeling and Mechanisms

The adsorption of arsenate from wastewaters was investigated by applying Mg-, Zn- or Ca-modified nut residue biochar activated by nitrogen/steam. The parameters studied were the contact time, adsorbent dose, initial arsenate concentration and solution pH. The adsorption mechanism was investigated. Various analyses of the material before and after arsenate adsorption were carried out, and experimental data were simulated by applying two isotherm models. The results indicated that the maximum removal efficiency of arsenate was 29.4% at an initial concentration of 10 mg/L. The modification of biochar by Mg, Zn or Ca oxides increased the removal rate significantly, from 49.4% at 100 mg/L As5+ up to 8%, 97% and 97%, respectively. Zn-modified biochar presented an excellent performance for both low and high As5+ concentrations. All experimental data were accurately fitted by the Freundlich isotherm model (R2 = 0.94–0.97), confirming a multilayer adsorption mechanism. For a biochar dose of 2 g/L, the maximum capacity of adsorption was enhanced after Mg-, Zn- or Ca-modification from 12.4 mg/g to 35 mg/g, 50 mg/g and 49 mg/g, respectively. The potential mechanisms of adsorption were ligand exchange, chemical complexation, surface precipitation and electron coordination.

Zinc isotope fractionation during coprecipitation with amorphous iron (hydr)oxides

Coprecipitation facilitates the incorporation of Zn into the lattice of Fe (hydr)oxide, which is a crucial mechanism causing low Zn bioavailability in widespread Zn-deficient soils. Zn isotopes are a potential indicator of the coprecipitation of Zn and Fe (hydr)oxides in soils. However, the Zn isotope fractionation caused by coprecipitation with amorphous Fe (hydr)oxides (e.g., ferrihydrite) and the impact of environmentally relevant conditions remain unknown. Here, the molecular mechanism and impact factor of Zn isotope fractionation during Zn2+-Fe3+ coprecipitation under natural soil conditions (including different pH values and initial Zn/Fe ratios) were investigated by combining isotope ratio measurements, extended X-ray absorption fine structure (EXAFS) analyses, and density functional theory (DFT) geometry optimization. The results show that aqueous Zn (Znaq) can be complexed on the ferrihydrite surface (Znads) with positive isotope fractionation (Δ66Znads–aq = 0.42 ± 0.09 ‰) or directly incorporated into the ferrihydrite lattice with slightly negative isotope fractionation (Δ66Znstru-aq = −0.08 ± 0.03 ‰). In addition, over time, the surface-complexed Zn can further transform to a layered structure on the surface but exhibits limited Zn isotope fractionation. According to Zn K-edge EXAFS, the Zn isotope fractionation of surface complexation and incorporation of Znaq are related to the decrease in the Zn–O bond strength in the order surface complexed Zn (RZn–O = 2.00 Å) > aqueous Zn (RZn–O = 2.08 Å) > directly incorporated Zn (RZn–O = 2.06–2.07 Å with slight distortion). The limited Zn isotope fractionation associated with the transformation of Znads is related to the reconfiguration of Znads during the nucleation of octahedral Zn layer structures. Furthermore, the primary process controlling Zn isotope fractionation is different under varying experimental conditions, leading to distinct Zn isotope fractionation between the bulk solid and solution during Zn–Fe coprecipitation. Low pH values (5.0–6.0) and initial Zn/Fe ratios (0.01–0.02) favor the direct precipitation of Znaq, resulting in slightly negative Zn isotope fractionation between the bulk solid and solution. In contrast, high pH values (7.0–7.5) and initial Zn/Fe ratios (0.1–0.2) favor surface complexation and the transformation of Znads, leading to heavy Zn isotope enrichment in the bulk solid. These findings offer novel insights into the primary mechanism through which Fe (hydr)oxides regulate Zn bioavailability in Zn-deficient soils and provide experimental evidence supporting the potential application of Zn isotopes as an indicator for comprehending the fate of Zn controlled by Fe (hydr)oxides in soils.

Role of electrochemical cell configuration on the selectivity of CuZnAl-oxide-based electrodes for the continuous CO2 conversion: aqueous electrolyte vs. catholyte-less configuration

This research is a significant step forward in understanding how the electrochemical cell setup influences CO2 conversion. The performance of Cu–Zn–Al metal oxide-based catalysts was compared in two reactor configurations: a gas diffusion electrode (GDE) cell with an aqueous electrolyte and a Membrane Electrode Assembly (MEA) cell operating in the gas phase without catholyte. The different operations induced significant morphological and crystalline structural changes, profoundly impacting the catalytic behaviour. The MEA configuration, for instance, led to the formation of a higher Cu0/Cu1+ ratio in the catalysts, promoting C–C coupling for C2H4 production. Conversely, the GDE operation favoured alcohol (ethanol and methanol) production by balancing copper oxidation states formed in situ in the presence of the aqueous catholyte. Zn and Al oxides also played a role in stabilising the resulting Cu species, some of which remained oxidised on the electrode surface. These findings underscore the crucial influence of varying cell operation conditions on catalyst reconstruction, shaping the quantity of Cu0 + Cu1+ species formed in situ to tailor catalyst selectivity.

Micronized Zn Oxide on Carbonic Anhydrase Activity, Health, and Yield of Ratoon Sugarcane Under Tropical Conditions

Micronized Zn Oxide on Carbonic Anhydrase Activity, Health, and Yield of Ratoon Sugarcane Under Tropical Conditions

Zn Oxide Nanoparticles and Fine Particles: Synthesis, Characterization and Evaluation of the Toxic Effect on Germination and Vigour of Solanum licopersicum L.

The micronutrient Zinc (Zn) is essential for the proper growth and development of crops. Zinc oxide nanoparticles (NPs) and fine particles are presented as an emerging alternative to more traditional fertilizers. In this study, the possible toxic effect of four laboratory-synthesized ZnO NPs and fine particles with different characteristics on tomato seed germination and vigor parameters was examined in comparison to bulk ZnO. Different metal precursors were used for the chemical synthesis of the particles: Zn(NO3)2 and ZnSO4, for particles named NIT-. and SUL-., respectively. In addition, the synthesis process was modified to obtain coated particles (denoted as UW-, NIT-UW and SUL-UW) and washed particles (denoted as W-, NIT-W and SUL-W). These particles were applied at different toxic doses (0, 1.4, 2.8, 5.6 and 11.2 g L−1). The results indicated that although the constant contact time between the ZnO particles did not affect the germination capacity of the seeds, it affected the growth of roots and hypocotyls, with a higher impact on the roots’ development. This toxicity was more evident from the lowest particle dose used, although it did not prevent radicle and hypocotyl elongation during the development period studied (14 days). The synthesized coated particles (NIT-UW, SUL-UW) generated high toxicity on radicle and hypocotyl development, and this effect was observed from the first days of contact with the particles. The observed toxic effects on radicle length were minimized by the application of bulk ZnO particles. In the case of hypocotyl growth, these minor toxic effects were observed by using NIT-W particles and bulk ZnO. The possibility of positive effects on seed germination and development (radicle and hypocotyl length) when in continuous contact with ZnO, whether in fine particles, nanoparticles, or bulk sizes, was excluded. Furthermore, no benefits on germination parameters were observed by suppressing the final washing step in the particle’s synthesis process, suggesting that particle coating did not provide any advantage for seed germination under these continuous contact conditions.

Foliar-applied zinc promotes cadmium allocation from leaf surfaces to grains in rice

The accumulation of Cd by rice poses significant health risks. Foliar fertilization with Zn can reduce grain Cd contents in rice grown in Cd-contaminated soils. However, atmospheric deposition on leaves is another vector of Cd contamination, and it remains unclear how Zn application affects the allocation of such Cd. We conducted an experiment where the flag leaves of rice plants were treated with solutions with various Zn concentrations and a constant Cd concentration. The 111Cd stable isotope was used to trace the flux of foliar-applied Cd. Higher levels of foliar-applied Zn enhanced Cd efflux and grain allocation. This is attributed to limited sequestration of foliar-applied Cd in the leaf cell symplasm and increased Cd desorption from leaf cell walls when a high Zn2+ concentration occurs in the apoplast. Nonionic Zn oxide nanoparticles mitigated these effects. Additionally, the expressions of OsLCT1 and OsZIP7 in flag leaves and OsHMA2 and OsZIP7 in the uppermost nodes were upregulated under high-Zn2+ treatment, which may facilitate Cd phloem loading and grain allocation. Caution is advised in using foliar Zn in areas with high atmospheric Cd due to potential grain-contamination risks.