Search results for "ZINC"

Zinc isotope variations in archeological human teeth (Lapa do Santo, Brazil) reveal dietary transitions in childhood and no contamination from gloves

2020

International audience; Zinc (Zn) isotope ratios of dental enamel are a promising tracer for dietary reconstruction in archeology, but its use is still in its infancy. A recent study demonstrated a high risk of Zn contamination from nitrile, and latex gloves used during chemical sample preparation. Here we assess the potential impact of the use of such gloves during enamel sampling on the Zn isotope composition of teeth from a population of early Holocene hunter gatherers from Lapa do Santo, Lagoa Santa, Minas Gerais, Brazil. We first examined the amount of Zn and its isotopic composition released from the gloves used in this study by soaking them in weak nitric acid and water. We compared …

Inhibitoren der Korrosion 31 (1). Beitrag zur Inhibierung der Korrosion von Zink und Messing

1986

Folgende als Inhibitoren der Korrosion vom Kupfer bewahrte Verbindungen wurden bei Korrosionsstudien mit Zink und Messing eingesetzt: 2-Aminopyrimidin (A), 5-Aminotetrazolmonohydrat (B), Benzotriazol (C), Kupferron (D), 2-Mercaptopyrimidin (E), 2-Mercaptothiazolin (F), 2-Methyl-4-amino-5-cyanopyrimidin (G), Tetrazin-B (H) und Xanthanwasserstoff (I). Bei Zinkblechen wird unter Standardbedingungen in Gegenwart der Verbindungen A, B, C, E und G im Laufe von 15 Tagen Totalkorrosion beobachtet. In Anwesenheit der Verbindungen D, F und H werden prozentuale Schutzwerte von 29%, 14% und 39% beobachtet. Ein differenzierteres Bild vermitteln die pH-statisch ermittelten Saureverbrauchs-Zeit-Kurven mit…

Ab Initio Thermodynamics of Oxygen Vacancies and Zinc Interstitials in ZnO.

2015

ZnO is an important wide band gap semiconductor with potential application in various optoelectronic devices. In the current contribution, we explore the thermodynamics of oxygen vacancies and zinc interstitials in ZnO from first-principles phonon calculations. Formation enthalpies are evaluated using hybrid DFT calculations, and phonons are addressed using the PBE and the PBE+U functionals. The phonon contribution to the entropy is most dominant for oxygen vacancies, and their Gibbs formation energy increases when including phonons. Finally, inclusion of phonons decreases the Gibbs formation energy difference of the two defects and is therefore important when predicting their equilibrium c…

X-ray-absorption fine-structure study of ZnSexTe1−x alloys

2004

X-ray-absorption fine-structure experiments at different temperatures in ZnSexTe1−x (x=0, 0.1, 0.2, 0.55, 0.81, 0.93, 0.99, and 1.0) have been performed in order to obtain information about the structural relaxation and disorder effects occurring in the alloys. First and second neighbor distance distributions have been characterized at the Se and Zn K edges, using multiple-edge and multiple-scattering data analysis. The first neighbor distance distribution was found to be bimodal. The static disorder associated with the Zn–Te distance variance did not depend appreciably on composition. On the other hand, the static disorder associated with the Zn–Se distance increased as the Se content dimi…

Antibacterial, physical and mechanical properties of bonding agent containing synthesized Zinc Dimethacrylate

2019

Background The aim of this study includes synthesis of zinc dimethacrylate ionomer (ZDMA) by a new method, incorporate it into resin bonding and evaluate its antibacterial, physical and mechanical properties. Material and methods Resin adhesives containing 0 to 5% wt of ZDMA was produced and the following tests were accomplished: A: Antibacterial test: 1.Direct contact test. 2.Material aging; in both of them the bacterial colony counting were performed. B: Physical test: 1.Degree of conversion (D.C). 2.Evaluating the amount of released Zinc ion release in aqueous medium. C: Mechanical test: 1.Compressive strength test. 2.Shear bond test (enamel and dentine separately). The obtained results …

Zinc(II) complexes of amide- and urea-substituted 8-hydroxyquinolines

2002

Abstract A series of amide- and urea-substituted 8-hydroxyquinoline ligands 1–6-H are used for the formation of zinc(II) complexes. Hereby in general 2:1 complexes are obtained and the X-ray structure of [(3)2Zn] reveals the presence of a coordination polymer in the solid state. Only the derivatives of 7-amino-8-hydroxyquinoline 4-H and 5-H form trinuclear hexa-helical 6:3 complexes which exhibit interesting structural and NMR and fluorescence spectroscopic properties.

Zn(II)-alloferon complexes - Similar sequence, different coordination modes, no antibacterial activity.

2020

Often, in the search for a highly defined scientific phenomenon, a different one becomes apparent. This was also the case of this work, in the scope of which we planned to search for metal-enhanced, novel antibacterial/ antifungal compounds. Instead, we denied the existence of such and revealed the details of the bioinorganic chemistry of Zn(II)-alloferon complexes. Zinc(II) complexes of alloferon 1 and 2, ligands with a sequential difference of one amino acid only, show a substantially different coordination pattern at physiological pH. In the case of Zn(II)-alloferon 1 species, a histamine-like binding mode is observed (N-terminal amine and imidazole of His-1) and the coordination sphere …

C−C Cross-Couplings from a Cyclometalated Au(III) C∧ N Complex: Mechanistic Insights and Synthetic Developments

2021

Abstract In recent years, the reactivity of gold complexes was shown to extend well beyond π‐activation and to hold promises to achieve selective cross‐couplings in several C−C and C−E (E=heteroatom) bond forming reactions. Here, with the aim of exploiting new organometallic species for cross‐coupling reactions, we report on the Au(III)‐mediated C(sp2)−C(sp) occurring upon reaction of the cyclometalated complex [Au(CCH2N)Cl2] (1, CCH2N=2‐benzylpyridine) with AgPhCC. The reaction progress has been monitored by NMR spectroscopy, demonstrating the involvement of a number of key intermediates, whose structures have been unambiguously ascertained through 1D and 2D NMR analyses (1H, 13C, 1H‐1H CO…

Copper(II) and zinc(II) interaction with AB42: effects of metal binding on peptide’s aggregation rate and morphology of the aggregates.

2011

Nanostructure Formation on ZnSe Crystal Surface by Electrochemical Etching

2021

The article describes a simple method for nanostructuring the surface of monocrystalline zinc selenide. It is shown that the traditional electrochemical etching of n-ZnSe (111) samples in a concentrated solution of nitric acid leads to the appearance of massive etching pits and small pores on the surface. The dynamics of the process and stages of crystal dissolution has been studied. It is assumed that the porous zinc selenide obtained in this way can be used in optoelectronic structures, as well as as buffer layers for growing zinc oxide.