Zn Ratio Research Articles

Metal Bioaccumulation by the Neotropical Clam Anomalocardia flexuosa to Estimate the Quality of Estuarine Sediments.

This investigation evaluated the bioaccumulation potential of the tropical estuarine bivalve Anomalocardia flexuosa for trace metals. To this aim, chemical and sedimentological analyses and bioaccumulation tests were performed. The sediments were mainly composed by fine-sands and mud, with variable levels of organic matter and CaCO3. Muddy sediments from a depositional site (P2) presented the highest concentrations of metals, despite SEM/AVS not indicating bioavailability. Bioaccumulation factors showed high ratios for Cd, Ni, and Zn, while associations between the contents of mud, organic matter, CaCO3 and metals in sediments and tissues of A. flexuosa were indicated by a principal component analysis. The SEM/AVS was not effective to predict the bioavailability through dissolved metals. The results showed that contaminants were bioavailable, while the performed bioaccumulation test proved to be a reliable technique for assessing sediment contamination in estuarine regions. Moreover, A. flexuosa was considered an adequate test organism for bioaccumulation studies.

Synthesis and characterization of two-dimensional (2D) nanosheet zinc aluminum layered double hydroxide (Zn/Al LDH) via an alkali-free route

The effect of different molar ratios on the synthesis of zinc aluminium layered double hydroxide (Zn/Al LDH) via an alkali-free route was carried out in this research. This method was prepared by mixing zinc nitrate solution, aluminium nitrate solution, and ammonium carbonate solution at a constant pH of 8.5 with a spanning ratio of Zn to Al from 4:1, 3:1, and 2:1. The XRD patterns showed crystal nanostructure of Zn/Al LDHs was successfully formed. The lattice parameters (a and c) were slightly increased with the increasing of Zn/Al molar ratio. A larger hexagonal platelet is observed in the SEM image align with the high molar ratio of Zn/Al synthesized. The same trend has been observed in the FTIR spectra.
 
 Keywords: Zn/Al LDH, alkali-free route, different molar ratio, XRD, SEM, FTIR

Hydrogen Sensing of Heterostructured Magnetic Nanospheres With Different Fe to Zn Molar Ratio

This article describes the fabrication of Zinc Ferrite-Zinc oxide (ZFO-ZnO) heterostructure devices and the various sensing schemes that can be exploited using the same. A solvothermal approach has been used for the synthesis of ZFO-ZnO heterostructures having different compositions. The investigation of magnetic and electric properties is performed by varying the ratio of Zn $^{2+}$ and Fe $^{3+}$ ions. These heterostructures show enhanced magnetization with (i) an increase in the concentration of Fe $^{3+}$ ions and (ii) exposure to hydrogen (H $_2$ ) gas. These fine molar ratio adjustments in magnetism are engineered to obtain desirable sensing properties. We fabricated several two-terminal devices for the study of multiple sensing schemes. These devices demonstrated a linear current-voltage characteristic, with enhanced electrical resistance when the Fe $^{3+}$ ion concentration is reduced. Keywords- Magnetic analysis, Zinc Ferrite-Zinc oxide, sensors, room temperature, heterostructures, tunability and nanotechnology

Effects of Zinc supplementation on serum copper to Zinc and CRP to albumin ratios in hemodialysis patients.

BackgroundZinc (Zn) deficiency is a common condition and could contribute to poor outcomes in hemodialysis (HD) patients. The aim of this study was to evaluate the effects of Zn supplementation on serum copper (Cu) to Zn and C-reactive protein (CRP) to albumin ratios (CAR) in HD patients.MethodsSeventy-seven HD patients were enrolled in a multicentre simple-blind randomized clinical trial. Only 37 HD patients completed the study; they were randomly divided into two groups and supplemented with zinc sulphate (n=17) or placebo (n=20) for two months. Serum Zn and Cu were measured by atomic absorption spectrophotometry. Serum albumin and hypersensitive-CRP were assessed by colorimetric and immunoturbidimetric method, respectively. Determinations were performed before and after supplementation.ResultsAfter two months of supplementation, serum Zn significantly increased, and Cu to Zn ratio decreased in Zn supplemented group, but remained unchanged in the placebo group. In parallel, serum albumin concentrations significantly increased, and CAR decreased in Zn supplemented group only.ConclusionsZn supplementation reduces Cu to Zn and CRP to albumin ratios in HD patients. These changes point towards an improvement in nutritional, oxidative and inflammatory status. The study findings suggest that correcting Zn deficiency reduces poor outcomes in HD patients.

Bifunctional Catalysts Containing Zn(II) and Imidazolium Salt Ionic Liquids for Chemical Fixation of Carbon Dioxide.

Zn(II) can efficiently promote the catalytic performance of imidazolium salt ionic liquids (imi-ILs) for the chemical fixation of CO2 into epoxides. To obtain sustainability, immobilized bifunctional catalysts containing both imi-ILs and Zn(II) were prepared using bimodal mesoporous silica (BMMs) as carrier, through grafting of Zn(OAc)2 and 1-(trimethoxysilyl)propyl-3-methylimidazolium chloride (Si-imi) separately in the nanopores. The catalysts, named as BMMs-Zn&ILs, were identified as efficient catalysts for cycloaddition reaction of CO2 into epoxides under solvent-free conditions. BMMs-Zn&ILs showed good catalytic activity, which increased with the increase of the molar ratio of Zn(II) to Si-imi. As a comparison, different catalytic systems including homogeneous imi-IL, BMMs-ILs and BMMs-Zn were studied to demonstrate different cooperation behaviors. Furthermore, the kinetics studies of homogeneous and heterogeneous bifunctional catalysts were employed to confirm the differences, as well as to support the proposed cooperative catalysis mechanism in the nanopores.

Serum and Whole Blood Cu and Zn Status in Predicting Mortality in Lung Cancer Patients.

Alterations in circulating Cu and Zn are negative predictors of survival in neoplastic patients and are known during lung cancer. However, no data on predicting mortality of lung cancer patients based on the level of these elements in the blood have been presented to date. The aims of this prospective cohort study were as follows: (i) To evaluate the disturbances in serum and whole blood Cu and Zn, (ii) to assess the relationships between serum and whole blood Cu and Zn status and clinical, sociodemographic, and nutritional data, and (iii) to investigate the association of Cu and Zn status with all-cause mortality in lung cancer. Naïve-treatment lung cancer patients (n = 167) were characterized in terms of sociodemographic, clinical, and anthropometric data and dietary intake and compared with sex-matched control subjects (n = 48). Whole blood and serum Cu and Zn status was determined by atomic absorption spectrometry. Cox proportional hazards models adjusted for multiple confounders/mediators were used to estimate the association between all-cause death and Cu and Zn status. Sex, cardiovascular disease, chronic obstructive pulmonary disease, clinical stage, and hemoglobin, platelet, and glucose concentrations significantly differentiated Cu and Zn status. All-cause mortality in lung cancer patients was positively associated with serum Cu levels, Cu:Zn ratio, and whole blood Zn levels. However, an advanced clinical stage of disease was the strongest predictor of all-cause mortality. Circulatory status of Cu and Zn might be included in routine clinical characteristics of patients with lung cancer patients as additional prognostic variables, but only after further more detail studies.

Study of trace elements (Serum Copper and Zinc) in patients of coronary artery diseases

Introduction: Previous studies suggest a protective role of the essential trace elements against cardiovascular disease, whereas wistful epidemiological data remains controversial. We aimed to investigate the alteration in concentration of zinc (Zn) and copper (Cu) in patients presented with coronary artery disease. Materials and Methods: In this case control study 100 normal healthy controls and 100 patients diagnosed with acute coronary artery diseases were enrolled. Serum copper and serum zinc concentration were measured in both the groups. Results and Observations: Serum copper concentration was significantly higher in patient of acute coronary artery disease (141.0±15.2) compared to controls (97.0±10.8). Serum zinc concentration was significantly lower in patient of acute coronary artery disease (70.0±8.8) compared to controls (100.0±13.2). And the ratio of serum Cu: Zn almost double in patient of acute coronary artery disease patients compared to normal healthy individuals. Conclusion: From the present study, it is concluded that decreased serum zinc and increased serum copper levels are associated with coronary artery disease. Moreover, results demonstrate that increased serum Cu: Zn ratio can diagnose occurrence of vascular events even in CAD patients. Keywords: Coronary artery disease, Serum copper, Serum zinc.

Solvation Structure Design for Aqueous Zn Metal Batteries.

Aqueous Zn batteries are promising energy storage devices for large-scale energy-storage due to low cost and high energy density. However, their lifespan is limited by the water decomposition and Zn dendrite growth. Here, we suppress water reduction and Zn dendrite growth in dilute aqueous electrolyte by adding dimethyl sulfoxide (DMSO) into ZnCl2-H2O, in which DMSO replaces the H2O in Zn2+ solvation sheath due to a higher Gutmann donor number (29.8) of DMSO than that (18) of H2O. The preferential solvation of DMSO with Zn2+ and strong H2O-DMSO interaction inhibit the decomposition of solvated H2O. In addition, the decomposition of solvated DMSO forms Zn12(SO4)3Cl3(OH)15·5H2O, ZnSO3, and ZnS enriched-solid electrolyte interphase (SEI) preventing Zn dendrite and further suppressing water decomposition. The ZnCl2-H2O-DMSO electrolyte enables Zn anodes in Zn||Ti half-cell to achieve a high average Coulombic efficiency of 99.5% for 400 cycles (400 h), and the Zn||MnO2 full cell with a low capacity ratio of Zn:MnO2 at 2:1 to deliver a high energy density of 212 Wh/kg (based on both cathode and anode) and maitain 95.3% of the capacity over 500 cycles at 8 C.

The performance of Cu/Zn/Zr catalysts of different Zr/(Cu+Zn) ratio for CO2 hydrogenation to methanol

A series of Cu/Zn/Zr catalysts with different Zr/(Cu + Zn) ratio were prepared by the precipitation method and tested for the synthesis of methanol (CO2/H2 mixture). The physicochemical properties of the solids were investigated by XRD, BET, H2-TPR, N2O-H2 titration, XPS and CO2-TPD techniques. An interesting “volcano- type” profile of structural and catalytic performance was demonstrated, which proved the structure sensitivity of reaction. The surface area of Cu, the surface adsorbed oxygen and the moderately strong basic sites concentration should be considered as significant activity parameters for the reaction.

Enhanced electrochemical conversion of CO2 to CO at bimetallic Ag-Zn catalysts formed on polypyrrole-coated electrode

An important strategy for reducing the impact of global CO2 emissions involves conversion technologies that transform CO2 into value-added materials. Bimetallic electrocatalysts of Zn and Ag were constructed on polypyrrole-decorated carbon paper (CP/PPy) electrodes for the improved electrochemical reduction of CO2 to CO. Bimetallic catalysts with different Zn and Ag atomic ratios were produced by the partial galvanic replacement of Zn with Ag on a CP/PPy/Zn electrode. Selectivity for the electrochemical reduction of CO2 to CO at the CP/PPy/Zn/Ag was clearly improved compared to those of the single-metal catalysts (CP/PPy(Ag or Zn)), while the hydrogen evolution reaction (HER) was suppressed. The PPy interlayer between the catalyst and CP support reduced the hydrophobicity of the carbon paper electrode, which facilitated the effective electrodeposition of Ag and Zn on the CP and suppressed the HER at the electrode. Herein, we propose Zn:Ag bimetallic composites deposited on PPy surfaces as CO-selective electrocatalysts with the optimal Zn:Ag catalyst composition suggested by electrochemical and physicochemical analyses. We experimentally confirmed that the atomically mixed Ag-Zn in the bimetallic catalysts enhanced the CO selectivity and production rate over each single metal catalyst. The developed electrocatalyst resulted in a maximum Faradaic efficiency of approximately 70% and a maximum current density of 8.6 mA/cm2 for the CO2 reduction reaction to CO in a 1 M KHCO3 aqueous solution.

Gas-sensing selectivity of n-ZnO/p-Co3O4 sensors for homogeneous reducing gas

Poor selectivity has always been the most severe challenge in the practical applications of gas sensors based on metal-oxide semiconductors (MOSs). It is difficult to distinguish CO and H2 because of the cross-sensitivity phenomenon. Herein, a series of n-ZnO/p-xCo3O4 NPs (1:x represents the molar ratio of Zn:Co) was prepared through a simple sol-gel method. Structural and material characterization were performed via X-ray diffraction (XRD) and transmission electron microscopy (TEM), while other techniques were used to assess the gas-sensing properties. The characterization results indicated that the oxides in the n-ZnO/p-0.61Co3O4 NPs formed p-n heterojunction instead of being dissolved together. The gas sensing results confirmed that the Zn:Co molar ratio influenced the gas-sensing selectivity of the n-ZnO/p-xCo3O4 NPs. Interestingly, regarding the gas-sensing behavior of n-ZnO/p-0.61Co3O4 NPs, the overall conductance of the film decreased in the presence of CO and increased in the presence of H2 at the testing temperature of 350 °C. This paper provides an approach to address the problem of poor selectivity of MOS-based gas sensors.

Synthesis, structural and photophysical properties of mixed Zn:SnO2 nanowires

The present work demonstrates the structural and photophysical properties of mixed zinc tin oxide (Zn:SnO2) nanowires (NWs) synthesized via vapor transport technique with Zn content of 10, 25 and 50 wt%. The XRD spectra reveals the tetragonal phase of SnO2 for 10 wt% Zn content, whereas a combination of tetragonal SnO2 and hexagonal ZnO phases were observed for higher Zn ratios. The SEM images reveals the formation of smooth NWs for low Zn content, whereas a combination of NWs along with spherical nanoparticles have been observed for 50 wt% Zn:SnO2 sample. The optical band gap was decreased from 3.21 eV (10% Zn:SnO2) to 2.84 eV (50% Zn:SnO2), whereas the corresponding Urbach energy increased from 971 meV to 1132 meV. The refractive index values increased from 2.28 to 2.64 when Zn content increased from 10 to 50 wt%. The absorption spectra showed a red shift and the appearance of new band with increasing Zn wt.%, signaling the formation of new electronic states below the conduction band. The fabricated films displayed a broad steady state emission with peak around 462 nm, which intensity decreased with the increasing of Zn ratio. The effective life time of charge carrier was decreased from 198 ps for 10 wt% Zn:SnO2 to 172 ps for 50 wt% Zn:SnO2.

Structural Features of ZnxMg1 – xWO4 Mixed Crystals

The structural features of a series of ZnxMg1–xWO4 mixed crystals (x = 0, 0.26, 0.41, 0.68, or 1) have been investigated using X-ray diffraction analysis and Raman spectroscopy; the luminescence properties of the grown crystals have also been studied. The dependence of the unit-cell volume on the substitution-cation concentration x is determined. It is shown that the geometric parameters of WO6 octahedra are independent of the ratio of Zn and Mg atomic concentrations in crystals. Consistency between the luminescence and structural properties of ZnxMg1–xWO4 crystals is established.

Stable Zn@ZSM-5 catalyst via a dry gel conversion process for methanol-to-aromatics reaction

Abstract A unique synthesis route to stabilize zinc species in ZSM-5 zeolite crystals was developed. Firstly, extensive mesoporosity in ZSM-5 was obtained through alkali treatment, after which Zn nanoparticles were introduced into the hierarchical ZSM-5 by impregnation. Then the sample was mixed with SiO2-sol and shaped. Finally, the Zn-fixed ZSM-5 zeolites was obtained by dry gel conversion. By this method, zinc species can be effectively stabilized in zeolite, which can not only improve the aromatic hydrocarbons selectivity, but also increase the stability of the catalyst in the reaction of methanol to aromatics (MTA). The acidity properties and the state of zinc species were studied. It was found that the catalyst possessed more Lewis acid sites and the ratio of Zn(OH)+/ZnO was increased after dry gel conversion.

Dissolved Trace Metals in the Ross Sea

The dissolved (D) trace metals zinc (Zn), cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), titanium (Ti), lanthanum (La), Yttrium (Y) and lead (Pb) were analysed via ICPMS in samples from the Ross Sea obtained during a cruise between 20 December 2013 and 5 January 2014. The concentrations of DZn, DCd, DCo, DCu, DFe, DMn, DNi and DTi were significantly lower in the Antarctic surface Water (AASW) compared to the other deeper water masses, indicating biological uptake and possibly scavenging. In the AASW, DLa and DY were higher than in Winter Water (WW). This can be explained by a spring source from ice melt followed by loss during summer and autumn, probably due to passive adsorption. Dissolved Pb was low (16 pM) and no distinction between water masses was possible. Akin to the macro-nutrients nitrate and silicate, the modified Circumpolar Deep Water (mCDW) shows elevated DCd compared to the shelf water masses. Sea ice melt and ice sheet melt released DZn, DFe, DMn, DNi, DY, DLa, and probably DPb into the Ross Sea. However, only DFe, DMn, DY and DLa are transported into the Antarctic Circumpolar Current (ACC) with the outflowing High Salinity Shelf Water (HSSW). The bottom nepheloid layer (BNL) released DFe, as well as DMn and DCu, into the HSSW whereas lateral transport from land formed a source of DMn and DFe. One station in the Ross Sea polynya was resampled after two weeks, during which time the thickness of the BNL increased, with accompanying increases in DFe and DMn near the seafloor. In the surface layer nutrients (including micro-nutrients) were depleted further. The uptake slopes/stoichiometric ratios of DZn, DCd and DCo versus phosphate indicated that the distribution of these metals is related to uptake as well as the composition of the phytoplankton community. Estimated stoichiometric ratios of Zn and Cd relative to P were higher at a station dominated by Phaeocystis antarctica than at diatom-dominated stations, implying a higher utilisation of these metals by P. antarctica.

Capacity and cycle performance of lithium ion batteries employing CoxZn1-xS/Co9S8@N-doped reduced graphene oxide as anode material

Exploiting efficient and rechargeable lithium-ion batteries (LIBs) is of great significance, which stimulates us to procure suitable electrode materials. Herein, a novel anode material is fabricated via encasing CoxZn1-xS/Co9S8 nanoparticles into N-doped reduced graphene oxide (rGO) skeleton. Owing to the open and accessible structure constructed by the conductive rGO as well as the optimized Co:Zn ratio, the as-prepared electrodes achieve good lithium storage capacity (742.2 mAh g−1 at 1 A g−1 and 222.4 mAh g−1 at 10 A g−1) and an excellent retention rate of 105.9% on 1000th cycle at 1 A g−1, making them promising anode candidate for highly reversible lithium storage in long-term cycles.

High Throughput Discovery of Effective Metal Doping in FeVO4 for Photoelectrochemical Water Splitting

FeVO4 is a potential photoanode candidate with favorable bandgap energy for absorbing visible light in the solar spectrum. However, the achieved photocurrents are still much lower than the theoretical photocurrent due to poor bulk carrier separation efficiency. Herein, the aim is to improve FeVO4 charge transport properties by searching for suitable metal doping using combinatorial methods. Thin‐film FeVO4 libraries with different doping ratios of Zn, Ni, Cr, Mo, and W are fabricated on fluorine doped tin oxide substrates using combinatorial inkjet printing and their photoelectrochemical properties screened using photoscanning droplet cell. Mo and W doping show higher current density compared with undoped FeVO4; whereas the photocurrent decreases for Ni‐ and Zn‐doped samples. The best photocurrent is achieved with 7% doping ratio of Cr. Cr is discovered as a promising dopant for the first time, which is more effective than reported Mo or W for FeVO4 photoanode. The replacement of Cr3+ to Fe3+ in FeVO4 crystal lattice helps to mainly improve the catalytic activity for charge transfer, which results in the enhancement of photoresponse of the FeVO4 photoanode.

Effects of Zn Ratio Tuning on the Structural and Transport Properties of Amorphous Indium Zinc Tin Oxide Thin Films

In this study, various indium zinc tin oxide (IZTO) films were fabricated using co-sputtering to explore amorphous transparent conducting oxides as alternatives to crystalline indium tin oxide (ITO). Various Zn ratios were tuned to study their effects on the structural evolution of IZTO. Amorphous IZTO (aIZTO) films were obtained when the Zn concentration was higher than approximately 17 at.%. X-ray diffraction and transmission electron microscopy analyses indicated that amorphous structures were formed due to the high crystallization temperatures of IZTO and nanocrystalline In2Zn5O8, which also caused aIZTO to exhibit small band gaps. On average, 87% transmittance was achieved in the visible light range. The aIZTO films had substantially higher transmittance in the infrared region than the ITO films did. Samples with Zn ratios between approximately 17 at.% and 27 at.% exhibited resistivity (approximately 3 × 10−4 Ω-cm), mobility (7 cm2 V−1 s−1), and carrier concentrations (4 × 1021 cm−3) comparable to those of crystalline ITO. Thus, the aIZTO films are promising alternative TCO materials. The mechanisms of competition between the crystallinity, oxygen deficiency, high-mobility In2Zn5O8, and electron and hole generation rates were applied to shed light on the excellent electrical and transport properties of aIZTO films.

Evolution of the Microstructure and Microsegregation in Subrapidly Solidified Mg–6Al–4Zn–1.2Sn Magnesium Alloy

The evolution of the microstructure and microsegregation in a new type of Mg–6Al–4Zn–1.2Sn (wt%) cast magnesium alloy solidified at cooling rates from 4.5 × 101 °C s−1 to 2.3 × 103 °C s−1 is investigated. The results indicate that the secondary dendrite arm spacing and the average grain sizes decrease from 14.3 to 2.9 μm and from 187 to 78 μm, respectively, as the cooling rate increases from 4.5 × 101 °C s−1 to 2.3 × 103 °C s−1. The relationship between the secondary dendrite arm spacing (λ2) and cooling rate (R) is fitted as λ2 = 69.7 × R−0.42. When the alloy solidifies in the range of cooling rates, a new quasi‐crystalline I phase is formed due to faster solidification. The microsegregation ratios of Al, Zn, and Sn elements decrease significantly with the increase in cooling rate. Compared with the specimen solidified at 4.5 × 101 °C s−1, the microsegregation ratios of Al, Zn, and Sn of that solidified at a cooling rate of 2.3 × 103 °C s−1 decrease by 37.4%, 45.7%, and 31.6%, respectively.

Effects of pyrolysis temperature on properties of swine manure biochar and its environmental risks of heavy metals

Converting swine manure into biochar has increasingly been considered a useful method to reduce heavy metal (HM) availability; however, the associated environmental risks need further exploration. In this study, swine manure was pyrolyzed at diff ;erent temperatures ranging from 200 to 700 °C; this was aimed at studying the effect of temperature on the swine manure biochar properties, while elucidating the environmental risks of HMs. The aromaticity and oxidation-resistance stability of biochar improved with an increase in the pyrolysis temperature. Cu and Zn concentration in biochar (except 200 °C) were significantly higher than manure (maximum increase of 91.9 % for Cu and 85.1 % for Zn). The residual ratios (R) of Cu and Zn gradually decreased as the temperature increased from 200 to 500 °C and increased over 500 ℃. The R of Cd decreased dramatically as the temperature increased from 200 to 700 °C (79.1 % at 200 °C versus 1.34 % at 700 °C). The HM speciation in biochar was affected by the temperature. High temperatures caused HMs to transition from unstable to stable fractions, thereby reducing the leaching toxicity and environmental risks. There was also a significant correlation between the potential ecological risk index and the O/C ratio (Regression coefficients (R2) = 0.98, P-value of a hypothesis test (p) <0.01), indicating that the O/C index is a good tool to assess the environmental risks of HMs in biochar. Based on the environmental risk assessment value, this study highlights that pyrolysis at 600 °C is probably the most optimal temperature condition for treating livestock manure with high concentrations of Cu, Cd, and Zn.