Presence Of Zn Ions Research Articles

Green Fluorescence Property of Chromone-based Hydrazone Towards Zn2+ Ion

Excessive concentration of Zn in the environment may lead to bad toxicological responses that can affect human health and create numerous challenges in the environment. Therefore, it is very important to develop a sensitive method such as selective chemosensors based on fluorescence property which does not require laborious work in order to detect Zn metal ion. A formylchromone-thiosemicarbazide with two chloro derivatives namely DFCTSC was synthesized from reflux reaction of 6,8-dichloroformylchromone (DCF) and thiosemicarbazide (TSC) in ethanol. The characterisation of ligand structure was determined by using spectroscopic techniques such as Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-VIS) and nuclear magnetic resonance spectroscopy (NMR). Meanwhile, the fluorescence property of DFCTSC in the presence of Zn ion was recorded using fluorescence spectrophotometer. The result showed DFCTSC has a good fluorescence behaviour towards Zn ion by giving turn-on green fluorescence at peak 500 nm and emit light when it observed under UV light. The behaviour displayed the ability of ligand to be used as a potential fluorescent chemosensor for detecting Zn2+.

Nanostructured ZnxMn3‒xO4 thin films by pulsed laser deposition: A spectroscopic and electrochemical study towards the application in aqueous Zn-ion batteries

Aqueous Zn-ion batteries (AZIBs) represent a safe and sustainable technology amongst the post-lithium systems, though the poor understanding of the material behaviour at the cathode prevents the full development of efficient AZIBs. ZnMn2O4 (ZMO) has been considered one of the cathode candidates owing to its analogy to the well-established LiMn2O4 cathode for lithium-ion batteries, however its electrochemical mechanism in the presence of Zn ions in aqueous environment is unclear and still debated. In this work, we synthesised nanostructured ZMO thin films by Pulsed Laser Deposition (PLD) and we evaluated, through extensive characterization by microscopic, spectroscopic, and diffraction techniques, how the deposition and annealing conditions affect the film properties. The self-supported nature and the high degree of control down to the nanoscale make a thin film an ideal model system to study the electrochemistry of the material in aqueous solution and to emphasize the impact of the film properties on its electrochemical response. We highlighted the crucial role of the oxygen pressure in the modulation of the film porosity and the combined effect of deposition pressure and annealing temperature to produce a film with tailored properties in terms of morphology, crystallinity, and Zn stoichiometry. A complex redox mechanism involving multiple concurrent reactions and the formation of zinc hydroxide sulphate hydrate (ZHS) was reported, as well as the influence of the film porosity on the voltammetric behaviour of the film at higher scan rate. Our results confirm the intricate electrochemical mechanism of the ZMO material, which does not merely involve the Zn2+ insertion/extraction but also the crucial participation of Mn2+ from the electrolyte, and pave the way for the nanoscale design of engineered ZMO-based electrodes.

Formation of Mn-Zn Layered Double Hydroxide - New Insights into the Charge Storage Mechanism of Near-Neutral MnO2/Zn Batteries

A relatively new type of aqueous battery that is based on MnO2/Zn chemistry in near-neutral pH electrolytes is receiving significant attention in the research community for its potential commercial applications. This chemistry offers many advantages such as relatively high cycle life [1], low cost, high natural abundance and availability of the active materials, and environmental friendliness. On the other hand, issues with the formation of parasitic Zn-layered double hydroxide (ZnLDH) creates challenges for the capacity utilization in high mass loading electrodes. Revealing the charge storage mechanism and the products of the discharge reaction would significantly help with the scaling up of this technology.At present, there is a debate on the nature of the reaction mechanism considering proton or zinc intercalation (or co-insertion of both) into the MnO2 structure, and what structural transformations occur during charge/discharge. We present new insights on the reaction mechanism and show that novel, not reported yet, Mn-Zn based layered double hydroxide (MnZnLDH, MnxZny(OH)zSO4 · 5H2O) forms during the first discharge reaction (Figure 1) [2]. MnZnLDH forms through a conversion reaction that occurs between MnO2 and Zn2+ during the first discharge plateau and it is a structural analogue of ZnLDH. Electrochemical experiments in different aqueous/organic electrolytes with and without the presence of Zn ions have shown that protons and water play significant roles in the charge-storage mechanism, while Zn ions form species at the surface rather than intercalating in the bulk of MnO2 structure. Excellent rechargeability was achieved for the ramsdellite (MnO2) and hausmannite (Mn3O4) phases, i.e., over 1000 [1] and 800 [3] cycles, respectively, without considering the formation of MnZnLDH. However, improving the reversibility of MnZnLDH transformation during the cycling will enhance the battery cycle life even further.

Alkali/zinc-activated fly ash nanocomposites for dye removal and antibacterial applications

Fly ash (FA), obtained as waste materials from industrial power plants, is generated in large quantities and low recycling. In this study, re-generation of waste FA as cost-effective materials with adsorbent and antibacterial applications was assessed. Alkaline/zinc-activated fly ash nanocomposite (A-FA/Zn) was prepared using one-pot hydrothermal technique. Those nanocomposites are characterized by high surface area and negatively surface charge, which are important influences contributing to an enhancement in adsorption capacity via increase in the number of adsorptive sites and electrostatic interaction between dye molecules-nanocomposites. Additionally, the presence of Zn ions in the prepared nanocomposites represents a key advantage with respect to enhancing antibacterial activity. The feasibility of further enhancing adsorption and antibacterial mechanisms was also examined. It is anticipated that the findings of this study will provide useful information with respect to the development of simple, eco-friendly and low-cost A-FA/Zn with multifunctional applications as organic dye removal and antibacterial purposes.

Visual bio-detection and versatile bio-imaging of zinc-ion-coordinated black phosphorus quantum dots with improved stability and bright fluorescence

Zero-dimensional black phosphorus quantum dots (BPQDs) have unique structural characteristics and excellent properties for promising applications over other BP structures. With the decrease of BP stacked layers, BP becomes much unstable and is easy to be oxidized and degraded in air and water. To prevent BP oxidation and degradation is crucial during the preparation process of highly stable BPQDs with strong fluorescence (FL). Herein, we explored a zinc-ion-coordinated strategy to achieve the emerging Zn@BPQDs with improved colloidal and FL stabilities. Zn ions can be adsorbed on BP surface via cation-π interactions, which passivates lone pair electrons of phosphorus and makes BP much stable upon exposure to air and water. Zn@BPQDs were prepared through sonication-assisted liquid-phase exfoliation of bulk BP crystals in the presence of Zn ions and solvothermal reaction of exfoliated few-layer Zn@BP nanosheets. Experimental results confirm the preparation of Zn@BPQDs with improved stability and high FL. Zn@BPQDs were used for both FL spectral detection and naked-eye visual FL detection of glutathione in practical samples. As emerging FL reagents, biocompatible Zn@BPQDs were further used for efficient in-vitro cell imaging and in-vivo imaging in natural plants and living aquatic animals.

The influence of Zn2+ on stress corrosion cracking severity in a highly sensitised Al–Mg alloy

ABSTRACTRecent work has indicated that a galvanic as well as chemical protection mechanism may control the intergranular stress corrosioncracking (IG-SCC) mitigation achieved by Zn-rich primers on Al-Mg alloys [1]. The effect of Zn salt species content added to the bulk NaCl environment on IG-SCC severity at -0.9 VSCE was evaluated using a highly susceptible condition of AA5456-H116. Linear elastic fracture mechanics-based testing demonstrated that, for a constant [Cl–], the threshold stress intensity for IG-SCC increased under these conditions and the IG-SCC growth rate was significantly suppressed with increasing stress intensity in the presence of Zn ions. Titration of ZnCl2 into Al-Mg simulated crack tip solution indicates that Zn salt species may reduce crack tip acidification and thereby raise the pH of the crack tip. These results support the combined galvanic and chemical protection that may be achieved through use of Zn-rich primers for IG-SCC mitigation on AA5456-H116.

A trimetallic organometallic precursor for efficient water oxidation

Herein, we report an iron/nickel/zinc mixed oxide as a catalyst for the electrochemical water oxidation. This catalyst was synthesized by a straightforward method for the synthesis of an iron/nickel/zinc mixed oxide through the calcination of a Fe/Ni/Zn organometallic compound. The calcined product contains Fe and Ni as crucial ions for water oxidation, accompanied by the presence of Zn ions. The removal of Zn ions from the mixed oxide provides more active sites on the surface of the catalyst. The composition of the compound was characterized by some common methods and found to be an efficient water-oxidizing catalyst. The catalyst on FTO at pH = 13 yields a current density of 12 mA/cm2 at 1.2 V (vs. Ag│AgCl). After 5 hours at 1.1 V, the electrode not only shows no decrease in performance, but also shows an increase from 4 to 7 mA/cm2 in the water oxidation activity. Tafel plot, for the electrode at pH = 13 in KOH solution (0.1 M) showed linearity for the graph of lg j vs. V with both relatively low (220.4 mV per decade) and high overpotentials (903.7 mV per decade).

Fibrillation of N-Terminal Prion Protein Fragment in Presence of Zinc Ions

Abnormal (misfolded) form of human prion protein displays high propensity towards self-association which may result in formation of insoluble fibrillar deposits in the brain, associated with the development of fatal neurodegenerative disorders, transmissible spongiform encephalopathies (TSE) [1]. The formation of such deposits can be driven by many intra- and extracellular factors. One of them can be disrupted homeostasis of metal ions. As reported previously, Zn ions bonded to N-terminal fragment regulate the interactions between N- and C-terminals [2]. Here we present structural analysis of the fragment of PrP N-terminal domain in the presence of Zn ions. Our experiments demonstrate that Zn-saturation leads to formation of N-terminal domain fibrillar structures. The fibrils were analyzed by atomic force microscopy (AFM), electron microscopy (EM), X-ray fiber diffraction and X-ray absorption spectroscopy (XAS). AFM and EM images indicated, that in the presence of zinc, PrP peptide forms long fibrillar structures. The presence of two characteristic reflections at 1.12 nm and 0.36 nm in the X-ray diffraction pattern confirmed the fibrillar nature of the studied PrP peptide. These reflections corresponded to characteristic distances in the fibrillar structure of the studied PrP peptide. Zn XAS K-edge 1s->4p transition in the edge region indicates, that Zn occupies a mononuclear site and is coordinated by light atoms (N, O). Fourier transform of χ(k) signal indicates the presence of imidazole groups in the nearest Zn shell. Our findings may shed new light on the role of zinc in TSE disorders. This work was supported by the funds from the National Science Centre (Poland) granted on the basis of decision no. 2014/15/B/ST4/04839.[1] Kovacs, G. G., & Budka, H. (2008). The American Journal of Pathology, 172(3), 555-565. [2] Spevacek, A.R., et al. (2013) Structure, 21, 236-246.

Spherical-Like Ball-by-Ball Architecture of Ni-Co-Zn-S Electrodes for Electrochemical Energy Storage Application in Supercapacitors

Spherical-like ball-by-ball architecture of Ni-Co-Zn-S was obtained through one pot simple and facile hydrothermal method without any surfactant. The as synthesized crystalline powder was characterized by using various tools like powder X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Furthermore, the electrochemical performance studies were carried out from cyclic-voltammetry (CV), galvanostatic charge–discharge (CD) and electrochemical impedance spectroscopy (EIS), within 3.5 M KOH. The consistent increment of clear redox peaks were obtained from CV characteristics due to synergic activities of Ni, Co and Zn. In addition, the presence of Zn ions into Ni and Co has increased its electronic conductivity; therefore, we could observe the superior performance. Thus, Ni-Co-Zn-S exhibited a maximum specific capacitance of 825, 680, 582, 512, 460, 432, 392 and 328 Fg−1 at 1, 2, 3, 4, 5, 6, 7 and 10 Ag−1 within 3.5 M KOH electrolyte. The obtained results are suggesting the excellent electrochemical activities with affordable rate of Ni-Co-Zn-S which is suitable electrode for device applications. Thus, our results may pave the way for the fabrication of advanced high energy storage device through a low-cost preparation to attain the extraordinary limit in energy device industry.

Tuning the morphology of ZnO nanoparticles by Zn-clusters and application on the photoreduction of Cr(VI)

The ZnO nanoparticles in a uniformed size have been applied as the photocatalysts over the reduction of Cr(VI). The morphologies of the ZnO nanoparticles are decided by the cluster type of mother sample Zn-MOFs, which are prepared with the same bi-ligands 1,3,5-benzenetricarboxylic acid (H3BTC) and phenanthroline (phen) in the presence of Zn ions. The SEM, TEM, infrared spectroscopy, thermogravimetric analysis and UV–vis study reveal the physical properties and structural information of ZnO nanoparticles. The reduction rate of Cr(VI) under the UV light irradiation indicates that the ZnO nanoparticles have higher activities with promoting reduction rate comparing with the related Zn-MOFs. The test of photocurrent approves the reduction ability of each sample.

Aggregation of sphalerite: role of zinc ions

Sphalerite from six sources is shown to aggregate at ca. pH 7–9, confirmed by different techniques (settling velocity, suspension analysis, and optical microscopy). This does not correlate with the isoelectric point, which is consistently < pH 6. A similar observation was made by Healy and Jellet [J. Colloid Interface Sci. 24 (1967) 41–46] for ZnO (and reconfirmed here), who suggested Zn hydrolysis products were responsible. The hypothesis is tested using chalcopyrite and silica suspensions in the presence of Zn ions. It is found that aggregation occurs over the same pH range, 7–9. Solution and surface analysis (extraction by EDTA) shows sphalerite released sufficient Zn ions to promote aggregation. The pH range 7–9 corresponds to hydroxide formation, suggesting this is the species responsible. Aggregation of sphalerite due to the polymerization/flocculation action of zinc hydroxide is proposed.

Nanofiller as vulcanizing aid for styrene-butadiene elastomer

The use of ZnO and stearic acid is very well known in sulfenamide accelerated sulfur vulcanization of diene elastomers. Zn-ion coated nano filler has been developed and tested, in styrene-butadiene rubber (SBR) as sulfur vulcanizing activator cum reinforcing filler. In this study Zinc oxide has been replaced by the Zn-ion coated nano silica filler with an aim to study the dual role of this nanofiller in SBR. The presence of Zn-ion on the nano silica filler surface activates the sulfur vulcanization by involving Zn++ in to the sulfurating complex formed with thiazole from sulfenamide. The increase of Zn-ion, on the nanofiller, decrease the scorch safety of the elastomer compound but increase the tensile strength, state of cure and tear strength and attain maximum at its 10% level. The presence of stearic acid increases the rate of vulcanization. Replacement of stearic acid with mono-stearate, however, increases the vulcanization rate but decrease the ultimate state of cure. A mechanistic scheme involving dual function of this nanofiller has been suggested.

Structure of cytochrome c' from Rhodobacter capsulatus strain St Louis: an unusual molecular association induced by bridging Zn ions.

Rhodobacter capsulatus strain St Louis cytochrome c' (RCCP-SL) has been crystallized and the structure solved by molecular replacement. It was refined at 2.1 A resolution to an R value of 18.4%, and compared with Rhodobacter capsulatus strain M110 cytochrome c' (RCCP-M110). Although these two proteins are very similar in sequence and structure, the intermolecular interaction is largely different. In RCCP-M110, the molecules dimerize through interaction of helix B to form an antiparallel arrangement. When crystallized in the presence of Zn ions, molecules of RCCP-SL were found to be arranged as linear polymers connected by the bridging Zn ions. The changes in conformation of the side chains induced by binding of the Zn ions, by the substitution of Glu90 for Asp90, and by the different arrangement of the molecules, are discussed in detail.

Hydrolysis of adenosine triphosphate by crystalline yeast pyrophosphatase. Effect of zinc and magnesium ions.

Schlesinger and Coon's report that crystalline yeast inorganic pyrophosphatase, in addition to its known ability to hydrolyze inorganic pyrophosphate in the presence of Mg ions, is also able to catalyze the hydrolysis of ATP and ADP in the presence of Zn ions was confirmed. A systematic study showed that the ratio of 370 of PPase-Mg over ATPase-Zn activities per milligram protein in various preparations of pyrophosphatase obtained in the course of isolation of crystalline pyrophosphatase from baker's yeast was nearly identical in all the preparations, independent of their purity. The course of hydrolysis of ATP by crystalline pyrophosphatase in the presence of Zn was carried out with the aid of ion exchange on Dowex 1. The finding of Schlesinger and Coon that the hydrolysis proceeds from ATP to ADP and then slowly to AMP was confirmed. The kinetics of the first phase of the reaction was found to depend on the molar ratio of Zn/ATP in the reaction mixture. Mg ions in the presence of Zn ions have an accelerating effect on the rate of hydrolysis of ATP. This suggests strongly that both activities-ATPase and PPase-are manifestations of the same active group in the protein molecule of crystalline pyrophosphatase.

Rotatory dispersion of inosine triphosphate and the influence of metals on ITP and ATP

The rotatory dispersions of inosine monophosphate (IMP), inosine diphosphate (IDP), and inosine triphosphate (ITP), have been determined and interpreted to indicate a folded structure of the ITP molecule, somewhat similar to that suggested for the ATP molecule. From the results obtained for the rotatory dispersion of ITP and ATP in the presence of Ca, Mg, or Zn ions, it appears that at pH 7 the combination of ATP with either Ca or Mg does not influence the optical symmetry of the molecule, but with ITP the combination with magnetium results in a product that has similar optical rotatory characteristics to ATP. These observations suggest configurational relationships that allow correlation of the physiological activities of the two molecules. The apparent alteration of the configuration of the ATP molecule in the presence of Zn ion may be used to suggest a configurational mechanism for the action of Zn ion on the 5-nucleotidase enzyme of cobra venom.