Showing papers on "Zinc published in 2017"

Rechargeable aqueous zinc-manganese dioxide batteries with high energy and power densities

Abstract: Although alkaline zinc-manganese dioxide batteries have dominated the primary battery applications, it is challenging to make them rechargeable. Here we report a high-performance rechargeable zinc-manganese dioxide system with an aqueous mild-acidic zinc triflate electrolyte. We demonstrate that the tunnel structured manganese dioxide polymorphs undergo a phase transition to layered zinc-buserite on first discharging, thus allowing subsequent intercalation of zinc cations in the latter structure. Based on this electrode mechanism, we formulate an aqueous zinc/manganese triflate electrolyte that enables the formation of a protective porous manganese oxide layer. The cathode exhibits a high reversible capacity of 225 mAh g−1 and long-term cyclability with 94% capacity retention over 2000 cycles. Remarkably, the pouch zinc-manganese dioxide battery delivers a total energy density of 75.2 Wh kg−1. As a result of the superior battery performance, the high safety of aqueous electrolyte, the facile cell assembly and the cost benefit of the source materials, this zinc-manganese dioxide system is believed to be promising for large-scale energy storage applications. The development of rechargeable aqueous zinc batteries are challenging but promising for energy storage applications. With a mild-acidic triflate electrolyte, here the authors show a high-performance Zn-MnO2 battery in which the MnO2 cathode undergoes Zn2+ (de)intercalation.

Rechargeable nickel–3D zinc batteries: An energy-dense, safer alternative to lithium-ion

Abstract: The next generation of high-performance batteries should include alternative chemistries that are inherently safer to operate than nonaqueous lithium-based batteries. Aqueous zinc-based batteries can answer that challenge because monolithic zinc sponge anodes can be cycled in nickel–zinc alkaline cells hundreds to thousands of times without undergoing passivation or macroscale dendrite formation. We demonstrate that the three-dimensional (3D) zinc form-factor elevates the performance of nickel–zinc alkaline cells in three fields of use: (i) >90% theoretical depth of discharge (DODZn) in primary (single-use) cells, (ii) >100 high-rate cycles at 40% DODZn at lithium-ion–commensurate specific energy, and (iii) the tens of thousands of power-demanding duty cycles required for start-stop microhybrid vehicles.

Removal of Heavy Metals from Industrial Wastewaters: A Review

Abstract: Heavy metals like arsenic, copper, cadmium, chromium, nickel, zinc, lead, and mercury are major pollutants of fresh water reservoirs because of their toxic, non-biodegradable, and persistent nature. The industrial growth is the major source of heavy metals introducing such pollutants into different segments of the environment including air, water, soil, and biosphere. Heavy metals are easily absorbed by fishes and vegetables due to their high solubility in the aquatic environments. Hence, they may accumulate in the human body by means of the food chain. Various methods have been developed and used for water and wastewater treatment to decrease heavy metal concentrations. These technologies include membrane filtration, ion-exchange, adsorption, chemical precipitation, nanotechnology treatments, electrochemical and advanced oxidation processes. In this review, the methods as well as their mechanisms and efficiency are discussed.

Highly active zinc catalyst for the controlled polymerization of lactide.

Abstract: We report the preparation, structural characterization, and detailed lactide polymerization behavior of a new Zn(II) alkoxide complex, (L(1)ZnOEt)(2) (L(1) = 2,4-di-tert-butyl-6-{[(2'-dimethylaminoethyl)methylamino]methyl}phenolate). While an X-ray crystal structure revealed the complex to be dimeric in the solid state, nuclear magnetic resonance and mass spectrometric analyses showed that the monomeric form L(1)ZnOEt predominates in solution. The polymerization of lactide using this complex proceeded with good molecular weight control and gave relatively narrow molecular weight distribution polylactide, even at catalyst loadings of <0.1% that yielded M(n) as high as 130 kg mol(-)(1). The effect of impurities on the molecular weight of the product polymers was accounted for using a simple model. Detailed kinetic studies of the polymerization reaction enabled integral and nonintegral orders in L(1)ZnOEt to be distinguished and the empirical rate law to be elucidated, -d[LA]/dt = k(p)[L(1)ZnOEt][LA]. These studies also showed that L(1)ZnOEt polymerizes lactide at a rate faster than any other Zn-containing system reported previously. This work provides important mechanistic information pertaining to the polymerization of lactide and other cyclic esters by discrete metal alkoxide complexes.

Zinc as a Gatekeeper of Immune Function

Abstract: After the discovery of zinc deficiency in the 1960s, it soon became clear that zinc is essential for the function of the immune system. Zinc ions are involved in regulating intracellular signaling pathways in innate and adaptive immune cells. Zinc homeostasis is largely controlled via the expression and action of zinc “importers” (ZIP 1–14), zinc “exporters” (ZnT 1–10), and zinc-binding proteins. Anti-inflammatory and anti-oxidant properties of zinc have long been documented, however, underlying mechanisms are still not entirely clear. Here, we report molecular mechanisms underlying the development of a pro-inflammatory phenotype during zinc deficiency. Furthermore, we describe links between altered zinc homeostasis and disease development. Consequently, the benefits of zinc supplementation for a malfunctioning immune system become clear. This article will focus on underlying mechanisms responsible for the regulation of cellular signaling by alterations in zinc homeostasis. Effects of fast zinc flux, intermediate “zinc waves”, and late homeostatic zinc signals will be discriminated. Description of zinc homeostasis-related effects on the activation of key signaling molecules, as well as on epigenetic modifications, are included to emphasize the role of zinc as a gatekeeper of immune function.

Suppression of Dendrite Formation and Corrosion on Zinc Anode of Secondary Aqueous Batteries

Abstract: Novel zinc anodes are synthesized via electroplating with organic additives in the plating solution. The selected organic additives are cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyethylene-glycol (PEG-8000), and thiourea (TU). The synthesized zinc anode materials, namely, Zn-CTAB, Zn-SDS, Zn-PEG, and Zn-TU, are characterized by powder X-ray diffraction and scanning electron microscopy. The results show that each additive produces distinctively different crystallographic orientation and surface texture. The surface electrochemical activity is characterized by linear polarization when the zinc is in contact with the battery’s electrolyte. Tafel fitting on the linear polarization data reveals that the synthetic zinc materials using organic additives all exhibit 6–30 times lower corrosion currents. When using Zn-SDS as the anode in the rechargeable hybrid aqueous battery, the float current decreases as much as 2.5 times. The batteries with Zn-SDS, Zn-PEG, and Zn-TU anodes display ...

Antioxidant and anti-inflammatory effects of zinc. Zinc-dependent NF-κB signaling

Abstract: Zinc is a nutritionally fundamental trace element, essential to the structure and function of numerous macromolecules, including enzymes regulating cellular processes and cellular signaling pathways. The mineral modulates immune response and exhibits antioxidant and anti-inflammatory activity. Zinc retards oxidative processes on a long-term basis by inducing the expression of metallothioneins. These metal-binding cysteine-rich proteins are responsible for maintaining zinc-related cell homeostasis and act as potent electrophilic scavengers and cytoprotective agents. Furthermore, zinc increases the activation of antioxidant proteins and enzymes, such as glutathione and catalase. On the other hand, zinc exerts its antioxidant effect via two acute mechanisms, one of which is the stabilization of protein sulfhydryls against oxidation. The second mechanism consists in antagonizing transition metal-catalyzed reactions. Zinc can exchange redox active metals, such as copper and iron, in certain binding sites and attenuate cellular site-specific oxidative injury. Studies have demonstrated that physiological reconstitution of zinc restrains immune activation, whereas zinc deficiency, in the setting of severe infection, provokes a systemic increase in NF-κB activation. In vitro studies have shown that zinc decreases NF-κB activation and its target genes, such as TNF-α and IL-1β, and increases the gene expression of A20 and PPAR-α, the two zinc finger proteins with anti-inflammatory properties. Alternative NF-κB inhibitory mechanism is initiated by the inhibition of cyclic nucleotide phosphodiesterase, whereas another presumed mechanism consists in inhibition of IκB kinase in response to infection by zinc ions that have been imported into cells by ZIP8.

Zinc and Oxidative Stress: Current Mechanisms.

Abstract: Oxidative stress is a metabolic dysfunction that favors the oxidation of biomolecules, contributing to the oxidative damage of cells and tissues. This consequently contributes to the development of several chronic diseases. In particular, zinc is one of the most relevant minerals to human health, because of its antioxidant properties. This review aims to provide updated information about the mechanisms involved in the protective role of zinc against oxidative stress. Zinc acts as a co-factor for important enzymes involved in the proper functioning of the antioxidant defense system. In addition, zinc protects cells against oxidative damage, acts in the stabilization of membranes and inhibits the enzyme nicotinamide adenine dinucleotide phosphate oxidase (NADPH-Oxidase). Zinc also induces the synthesis of metallothioneins, which are proteins effective in reducing hydroxyl radicals and sequestering reactive oxygen species (ROS) produced in stressful situations, such as in type 2 diabetes, obesity and cancer. Literature provides strong evidence for the role of zinc in the protection against oxidative stress in several diseases.

Surfactant widens the electrochemical window of an aqueous electrolyte for better rechargeable aqueous sodium/zinc battery

Abstract: Aqueous rechargeable batteries have received significant attention because of their low-cost and security. However, the narrow electrochemical stability window (about 1.23 V) of the aqueous electrolyte sets a limit on their energy output. Herein, we have developed an aqueous rechargeable hybrid battery using Na2MnFe(CN)6 nanocubes as the cathode and a zinc metal sheet as the anode, which delivered a high energy density of 170 W h kg−1 and a capacity retention of 75% over 2000 cycles with an operating voltage of up to 2.0 V. By adding sodium dodecyl sulfate (SDS) to the aqueous electrolyte, the electrochemical stability window of the electrolyte was expanded to about 2.5 V. The results of the experiments and calculations based on the density functional theory indicate that SDS can not only inhibit the decomposition of water, suppress the dissolution of Mn and the corrosion of zinc but also increase the cycle life and rate capability. The low-cost, high energy density, and long cycle life of the battery suggest that it is a promising candidate for energy storage applications.

Zinc in Cellular Regulation: The Nature and Significance of "Zinc Signals"

Abstract: In the last decade, we witnessed discoveries that established Zn2+ as a second major signalling metal ion in the transmission of information within cells and in communication between cells. Together with Ca2+ and Mg2+, Zn2+ covers biological regulation with redox-inert metal ions over many orders of magnitude in concentrations. The regulatory functions of zinc ions, together with their functions as a cofactor in about three thousand zinc metalloproteins, impact virtually all aspects of cell biology. This article attempts to define the regulatory functions of zinc ions, and focuses on the nature of zinc signals and zinc signalling in pathways where zinc ions are either extracellular stimuli or intracellular messengers. These pathways interact with Ca2+, redox, and phosphorylation signalling. The regulatory functions of zinc require a complex system of precise homeostatic control for transients, subcellular distribution and traffic, organellar homeostasis, and vesicular storage and exocytosis of zinc ions.

Green-low-cost rechargeable aqueous zinc-ion batteries using hollow porous spinel ZnMn2O4 as the cathode material

Abstract: Rechargeable aqueous zinc-ion batteries (ZIBs) have been receiving much attention recently due to their potential large-scale applications for energy storage, although only a few cathode materials have been reported as the intercalation hosts for divalent Zn2+ ions. Here, we report competitive ZIBs based on hollow porous ZnMn2O4 as the cathode and zinc as the anode. ZnMn2O4 is firstly prepared through a solvothermal carbon template dispersed by polyvinyl pyrrolidone, followed by an annealing process. The galvanostatic charge–discharge measurement demonstrates that a reversible discharge capacity of 106.5 mA h g−1 at 100 mA g−1 after 300 cycles can be achieved with no capacity decay after the addition of 0.05 mol L−1 of MnSO4 into the electrolyte. Meanwhile, it exhibits a high capacity of 70.2 mA h g−1 at a large current density of 3200 mA g−1. The excellent cycle and rate performances are attributed to the synergistic effect of the deficient spinel structure of hollow porous ZnMn2O4 with residual carbon distribution and the inhibition of Mn dissolution during the charge/discharge process.

The Prospects of Zinc as a Structural Material for Biodegradable Implants—A Review Paper

Abstract: In the last decade, iron and magnesium, both pure and alloyed, have been extensively studied as potential biodegradable metals for medical applications However, broad experience with these material systems has uncovered critical limitations in terms of their suitability for clinical applications Recently, zinc and zinc-based alloys have been proposed as new additions to the list of degradable metals and as promising alternatives to magnesium and iron The main byproduct of zinc metal corrosion, Zn2+, is highly regulated within physiological systems and plays a critical role in numerous fundamental cellular processes Zn2+ released from an implant may suppress harmful smooth muscle cells and restenosis in arteries, while stimulating beneficial osteogenesis in bone An important limitation of pure zinc as a potential biodegradable structural support, however, lies in its low strength (σUTS ~ 30 MPa) and plasticity (e < 025%) that are insufficient for most medical device applications Developing high strength and ductility zinc with sufficient hardness, while retaining its biocompatibility, is one of the main goals of metallurgical engineering This paper will review and compare the biocompatibility, corrosion behavior and mechanical properties of pure zinc, as well as currently researched zinc alloys

An ultrastable zinc(II)–organic framework as a recyclable multi-responsive luminescent sensor for Cr(III), Cr(VI) and 4-nitrophenol in the aqueous phase with high selectivity and sensitivity

Abstract: A 2D zinc(II) metal–organic framework (Zn-MOF-1) formulated as [Zn(L)(H2O)]·H2O (1) (H2L = 5-(2-methylpyridin-4-yl)isophthalic acid) with blue fluorescence has been successfully obtained under hydrothermal conditions. Zn-MOF-1 contains microporous parallelogram channels with accessible Lewis-base sites, coordinated water molecules and uncoordinated carboxylates, which are easy to anchor and recognise various analytes. The fluorescence investigations demonstrated that the blue-light-emitting behaviour of Zn-MOF-1 possesses excellent water and pH stability. More importantly, this is the first reported recyclable multi-responsive Zn-MOF fluorescence sensor for Cr(III), Cr(VI) (CrO42−/Cr2O72− ions) and 4-NP (4-nitrophenol) simultaneously with high selectivity and sensitivity and low detection limits in aqueous solution through fluorescence quenching. Furthermore, the mechanism for the selective sensing of Cr3+, CrO42−, Cr2O72− or 4-NP can mainly be explained by the competition between the absorption of the analytes and the excitation/emission of Zn-MOF-1, and the electronic interactions between Zn-MOF-1 and the analytes.

Luminescent Zn(II) Coordination Polymers for Highly Selective Sensing of Cr(III) and Cr(VI) in Water.

Abstract: Three photoluminescent zinc coordination polymers (CPs), {[Zn2(tpeb)2(2,5-tdc)(2,5-Htdc)2]·2H2O}n (1), {[Zn2(tpeb)2(1,4-ndc)(1,4-Hndc)2]·2.6H2O}n (2), and {[Zn2(tpeb)2(2,3-ndc)2]·H2O}n (3) (tpeb = 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene, 2,5-tdc = 2,5-thiophenedicarboxylic acid, 1,4-ndc = 1,4-naphthalenedicarboxylic acid, and 2,3-ndc = 2,3-naphthalenedicarboxylic acid) were prepared from reactions of Zn(NO3)2·6H2O with tpeb and 2,5-H2tdc, 1,4-H2ndc, or 2,3-H2ndc under solvothermal conditions. Compound 1 has a two-dimensional (2D) grid-like network formed from bridging 1D [Zn(tpeb)]n chains via 2,5-tdc dianions. 2 and 3 possess similar one-dimensional (1D) double-chain structures derived from bridging the [Zn(tpeb)]n chains via pairs of 1,4-ndc or 2,3-ndc ligands. The solid-state, visible emission by 1–3 was quenched by Cr3+, CrO42–, and Cr2O72– ions in water with detection limits by the most responsive complex 3 of 0.88 ppb for Cr3+ and 2.623 ppb for Cr2O72– (pH = 3) or 1.734 ppb for CrO42– (pH = 12). Thes...

Biosynthesis of zinc oxide nanoparticles using leaf extract of Calotropis gigantea : characterization and its evaluation on tree seedling growth in nursery stage

Abstract: Green synthesis of zinc oxide nanoparticles was carried out using Calotropis leaf extract with zinc acetate salt in the presence of 2 M NaOH. The combination of 200 mM zinc acetate salt and 15 ml of leaf extract was ideal for the synthesis of less than 20 nm size of highly monodisperse crystalline nanoparticles. Synthesized nanoparticles were characterized through UV–Vis spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), EDX (energy dispersive X-ray), and AFM (atomic force microscopy). Effects of biogenic zinc oxide (ZnO) nanoparticles on growth and development of tree seedlings in nursery stage were studied in open-air trenches. The UV–Vis absorption maxima showed peak near 350 nm, which is characteristic of ZnO nanoparticles. DLS data showed that single peak is at 11 nm (100%) and Polydispersity Index is 0.245. XRD analysis showed that these are highly crystalline ZnO nanoparticles having an average size of 10 nm. FTIR spectra were recorded to identify the biomolecules involved in the synthesis process, which showed absorption bands at 4307, 3390, 2825, 871, 439, and 420 cm−1. SEM images showed that the particles were spherical in nature. The presence of zinc and oxygen was confirmed by EDX and the atomic % of zinc and oxygen were 33.31 and 68.69, respectively. 2D and 3D images of ZnO nanoparticles were obtained by AFM studies, which indicated that these are monodisperse having size ranges between 1.5 and 8.5 nm. Significant enhancement of growth was observed in Neem (Azadirachta indica), Karanj (Pongamia pinnata), and Milkwood-pine (Alstonia scholaris) seedlings in foliar spraying ZnO nanoparticles to nursery stage of tree seedlings. Out of the three treated saplings, Alstonia scholaris showed maximum height development.

Zinc Signals and Immunity.

Abstract: Zinc homeostasis is crucial for an adequate function of the immune system. Zinc deficiency as well as zinc excess result in severe disturbances in immune cell numbers and activities, which can result in increased susceptibility to infections and development of especially inflammatory diseases. This review focuses on the role of zinc in regulating intracellular signaling pathways in innate as well as adaptive immune cells. Main underlying molecular mechanisms and targets affected by altered zinc homeostasis, including kinases, caspases, phosphatases, and phosphodiesterases, will be highlighted in this article. In addition, the interplay of zinc homeostasis and the redox metabolism in affecting intracellular signaling will be emphasized. Key signaling pathways will be described in detail for the different cell types of the immune system. In this, effects of fast zinc flux, taking place within a few seconds to minutes will be distinguish from slower types of zinc signals, also designated as “zinc waves”, and late homeostatic zinc signals regarding prolonged changes in intracellular zinc.

The emerging role of zinc transporters in cellular homeostasis and cancer

Abstract: Zinc is an essential micronutrient that plays a role in the structural or enzymatic functions of many cellular proteins. Cellular zinc homeostasis involves the opposing action of two families of metal transporters: the ZnT (SLC30) family that functions to reduce cytoplasmic zinc concentrations and the ZIP (SLC39) family that functions to increase cytoplasmic zinc concentrations. Fluctuations in intracellular zinc levels mediated by these transporter families affect signaling pathways involved in normal cell development, growth, differentiation and death. Consequently, changes in zinc transporter localization and function resulting in zinc dyshomeostasis have pathophysiological effects. Zinc dyshomeostasis has been implicated in the progression of cancer. Here we review recent progress toward understanding the structural basis for zinc transport by ZnT and ZIP family proteins, as well as highlight the roles of zinc as a signaling molecule in physiological conditions and in various cancers. As zinc is emerging as an important signaling molecule in the development and progression of cancer, the ZnT and ZIP transporters that regulate cellular zinc homeostasis are promising candidates for targeted cancer therapy.

Encapsulation of zinc hexacyanoferrate nanocubes with manganese oxide nanosheets for high-performance rechargeable zinc ion batteries

Abstract: With the rapid development of rechargeable zinc ion (Zn-ion) batteries, it is essential to understand and modulate the energy storage process of the active component to maximize the battery performance. In this research, manganese oxide (MnO2) wrapped zinc hexacyanoferrate (ZnHCF) nanocubes (ZnHCF@MnO2) were prepared using an in situ co-precipitation method. The resulting composite with a unique structure was able to modulate the Zn-ion storage because of the incorporation of capacitive and intercalative properties of both components together with the redox reactions, benefiting from the synergistic effects. Thus, the encapsulation of ZnHCF nanocubes with MnO2 nanosheets gives a high discharge capability for Zn-ion storage with an operation voltage as high as ∼1.7 V. Impressively, the flexible quasi-solid-state Zn-ion battery was assembled using a neutral polymer gel electrolyte, and this resulted in a battery which had potential applications for specific wearable electronics.