Nickel

About: Nickel is a research topic. Over the lifetime, 79308 publications have been published within this topic receiving 1210058 citations. The topic is also known as: Ni & element 28.

Nickel carcinogenesis: epigenetics and hypoxia signaling.

Abstract: Both water soluble and insoluble nickel compounds have been implicated in the etiology of human lung and nasal cancers. Water insoluble nickel compounds have been shown to enter cells by phagocytosis and are contained in cytoplasmic vacuoles, which are acidified thus accelerating the dissolution of soluble nickel from the particles. Using Newport Green, a dye that fluoresces when ionic nickel is bound, we have shown that following exposure (48-72 h) of human lung (A549) cells to NiS particles, most of the nickel is contained in the nucleus, while cells exposed to soluble NiCl2 exhibit most of the ions localized in the cytoplasm. This effect is consistent with previously published reports showing that short-term exposure of cells to crystalline nickel particles (1-3 days) is able to epigenetically silence target genes placed near heterochromatin, while similar short-term exposure to soluble nickel compounds are not able to induce silencing of genes placed near heterochromatin. However, a 3 week exposure of cells to soluble NiCl2 is also able to induce gene silencing. A similar effect was found in yeast cells where nickel was able to silence the URA-3 gene placed near (1.3 kb) a telomere silencing element, but not when the gene was placed farther away from the silencing element (2.0 kb). In addition to epigenetic effects, nickel compounds activate hypoxia signaling pathways. The mechanism of this effect involves the ability of either soluble or insoluble nickel compounds to block iron uptake leading to cellular iron depletion, directly affect iron containing enzymes, or both. This results in the inhibition of a variety of iron-dependent enzymes, such as aconitase and the HIF proline hydroxylases (PHD1-3). The inhibition of the HIF proline hydroxylases stabilizes the HIF protein and activates hypoxic signaling. Additional studies have shown that nickel and hypoxia decrease histone acetylation and increase the methylation of H3 lysine 9. These events are involved in gene silencing and hypoxia can also cause these effects in human cells. It is hypothesised that the state of hypoxia either by low oxygen tension or as a result of agents that signal hypoxia under normal oxygen tension (iron chelation, nickel and cobalt) results in low levels of acetyl CoA, which is a substrate for histone and other protein acetylation. This effect may in part be responsible for the gene silencing following nickel exposure and during hypoxia.

Alkaline free electroless deposition

Abstract: Alkali-free layers of pure metals such as copper, nickel and cobalt were deposited on noble metal or noble metal sensitized substrates by electroless deposition using pure quaternary ammonium hydroxides or quaternary phosphonium hydroxides to generate the hydroxyl ion (OH - ) needed to produce electrons for the metal reduction. Using the new alkaline-free electroless compositions, uniform, continuous and reproducible metal layers were selectively deposited with excellent electrical properties. With the improved compositions and process, nanosize copper lines having widths in the range of 100 to 500 nm were prepared.

Local Structure and Cation Ordering in O3 Lithium Nickel Manganese Oxides with Stoichiometry Li [ Ni x Mn ( 2 − x ) / 3Li ( 1 − 2x ) / 3 ] O 2 NMR Studies and First Principles Calculations

Abstract: Short-range ordering in Li[Ni x Mn ( 2 - x ) / 3 Li ( 1 - 2 x ) / 3 ]O 2 was investigated with 6 Li NMR and first principles structure computations. NMR indicates that the tendency for Ni 2 + to replace Li + in the Li + layers decreases with decreasing nickel content. Li in the Ni/Mn layers preferentially occupies sites near Mn 4 + and avoids the Ni 2 + ions, leading to nonrandom configurations. Calculations indicate that the ground state of Li(Ni 0 . 5 Mn 0 . 5 )O 2 contains zigzag rows of Ni 2 + and Mn 4 + ions. Although a disordering temperature of approximately 1000 K is calculated, ordered fragments persist above the phase transition and these materials contain significant short-range order, even when quenched from high temperature.

[Ni2O(l-Asp)(H2O)2]·4H2O: A Homochiral 1D Helical Chain Hybrid Compound with Extended Ni−O−Ni Bonding

Abstract: The hydrothermally synthesized 1D homochiral nickel aspartate oxide [Ni2O(l-Asp)(H2O)2]·4H2O is based on infinite helical chains of edge- and corner-sharing nickel octahedra. It represents the first example of a chiral one-dimensional compound with an extended helical TM−O−TM subnetwork synthesized as an optically pure product. Its structure was determined ab initio by real-space methods from laboratory powder diffraction data.

A Porphyrin Fused to Four Anthracenes

Abstract: We have synthesized a fused tetraanthracenylporphyrin by oxidation of a meso-anthracenyl nickel(II) porphyrin with FeCl3. This compound exhibits an intense red-shifted absorption spectrum (λmax = 1417 nm; e = 1.2 × 105 M−1 cm−1) and a small electrochemical HOMO−LUMO gap (0.61 eV). The crystal structure shows that it forms π-stacked dimers with a short Ni···Ni distance (3.32 A).