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Copper(ii), nickel(ii), zinc(ii) and organometallic ruthenium(ii) ([(η6-p-cym)Ru(H2O)3]2+) complexes of an N-terminally free heptapeptide containing four histidyl residues (NH2-HAVAHHH-NH2) have been studied by potentiometric and various spectroscopic techniques (UV-vis, CD, NMR and ESI-MS). The data revealed a significant selectivity in the metal binding ability of this ligand. Histamine-like coordination of the amino terminus is the primary binding mode for all metal ions but the internal histidyl residues can also contribute to the overall stability of the complexes. Copper(ii) and nickel(ii) ions are able to induce the deprotonation and coordination of the amide functions both at the amino terminus and around the internal histidyl sites, resulting in the co-existence of various coordination isomers or the formation of dinuclear complexes in the presence of excess of metal ions. [ABSTRACT FROM AUTHOR]

The most flame retardants and non-combustible non-woven fabrics are made of oxidized and carbon fibres due to their strong thermal stability. The burning of non-woven fabrics consists of complex combustion mechanisms: their surface, micro and macrostructures together define their combustion features. By microstructure, we mean oxidized polyacrylicnitrile fibres, which finally constitute the base material of the macrostructure. The macrostructure represents the different forms of the product, in which the material results during production. In this paper, the effect of the macrostructure of non-woven fabrics on flammability has been studied. It has experimentally shown that by defining the oxygen index, we can demonstrate the surface and thickness inhomogeneity, which is invisible or cannot be detected by mechanical tests. A feature of non-combustible non-woven fabrics is that their flammability depends on their thickness and area weight; however, the combustion phenomena of felt fabrics depend primarily on their macrostructure. Different oxygen contents have different combustion phenomena, thus an oxygen index can be assigned to each one. Thermoanalytical test results clearly showed the temperature at which the thermal decomposition of the fibres begins, which gives the surface flame when combusted. [ABSTRACT FROM AUTHOR]

In this work, the micro- and macro structure properties which determine the flammability of the end products (woven textiles) produced from 100% oxidized PAN fibres, based on their micro structure properties were examined. The conclusion was that the flammability of an end product can be defined and tested in two forms: one form is the oxidized PAN fibre as main product (micro structure) and the other is the woven fabric made from these fibres (macro structure). A textile produced from a certain oxidized fibre shows different flammability and oxygen index if the types of woven fabrics are different. The authors also concluded that the oxygen index, which characterises the flammability of an end product, is in correlation with the main parameters (e.g.: density) of the macro- and micro structures. Based on the results obtained it seems, that to characterise the flammability of the end products it is not enough to give only the standardized oxygen-index and it is not enough to give only the LOI parameter of the base material. [ABSTRACT FROM AUTHOR]

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Copper(ii), nickel(ii), zinc(ii) and organometallic ruthenium(ii) ([(η6-p-cym)Ru(H2O)3]2+) complexes of an N-terminally free heptapeptide containing four histidyl residues (NH2-HAVAHHH-NH2) have been studied by potentiometric and various spectroscopic techniques (UV-vis, CD, NMR and ESI-MS). The data revealed a significant selectivity in the metal binding ability of this ligand. Histamine-like coordination of the amino terminus is the primary binding mode for all metal ions but the internal histidyl residues can also contribute to the overall stability of the complexes. Copper(ii) and nickel(ii) ions are able to induce the deprotonation and coordination of the amide functions both at the amino terminus and around the internal histidyl sites, resulting in the co-existence of various coordination isomers or the formation of dinuclear complexes in the presence of excess of metal ions. [ABSTRACT FROM AUTHOR]