926 research outputs found

    Adsorption of arsenate on Fe-(hydr)oxide

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    Adsorption using metal oxide materials has been demonstrated to be an effective technique to remove hazardous materials from water, due to its easy operation, low cost, and high efficiency. The high number of oxyanions in aquatic ecosystems causes serious pollution problems. Removal of arsenate (H2AsO4 -), is one of the major concerns, since it is a highly toxic anion for life. Within the metal oxides, the iron oxide is considered as a suitable material for the elimination of oxyanions. The adsorption of H2AsO4 - on Fe-(hydr)oxide is through the formation of inner or outer sphere complexes. In this work, through computational methods, a complete characterization of the adsorbed surface complexes was performed. Three different pH conditions were simulated (acidic, intermediate and basic), and it was found that, the thermodynamic favourability of the different adsorbed complexes was directly related to the pH. Monodentate complex (MM1) was the most thermodynamically favourable complex with an adsorption energy of -96.0kJ/mol under intermediate pH conditions. © Published under licence by IOP Publishing Ltd

    Zaštitna aluminijska prevlaka izvedena izravno u ljevačkom kalupu na čeliku otpornom prema puzanju

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    The structure of coatings and their ability to protect the castings made of G-X25NiCrSi 36-17 (DIN 17006) cast steel against carburization have been described. Al-Cu and Al-Si protective coatings, produced directly in a casting mould, have a considerable thickness (400 - 2000 µm), and complex multiphase structure. Its main structural constituents are: (Fe, Ni, Cr), (Fe, Ni, Cr), Al(Ni, Fe), carbides M23C6 and M7C3. In Al-Si ferritic coatings are also present: (Ni, Fe), (Fe, Al, Ni, Cr) and (Cr, Si)3Ni2Si. Carburisation changes substantially the structure of coatings, what results in an increase of the amount of (Fe, Ni, Cr) or (Ni, Fe) and carbides, and a decrease of the amount of (Fe, Ni, Cr) and Al(Ni, Fe). Apart from above mentioned changes, the investigated coatings reduce the carbon diffusion by 20 - 65 % Al-Cu, about 55 % Al-Si (austenitic), and 75 % Al-Si (ferritic), so they can provide a temporary protection against high-temperature corrosion.U radu je opisana struktura prevlaka i njihova sposobnost lijevanja od G-X25NiCrSi 36-17 (DIN 17006) u svrhu zaštite protiv naugljičavanja. Zaštitne prevlake Al-Cu i Al-Si, napravljene izravno u ljevačkom kalupu, imaju znatnu debljinu (400 - 2000 µm) i složenu multifaznu strukturu. Glavni strukturni element su: g(Fe, Ni, Cr), a(Fe, Ni, Cr), bAl(Ni, Fe), karbidi M23C6 i M7C3. U feritnim prevlakama Al-Si prisutni su i: g(Ni, Fe), a(Fe, Al, Ni, Cr) i (Cr, S)3Ni2Si. Naugljičavanje mijenja suštinu strukture prevalaka, a to dovodi do povećanja količine g(Fe, Ni, Cr) ili g(Ni, Fe) i karbida, a smanjuje količinu a(Fe, Ni, Cr) i bAl(Ni, Fe). Neovisno o gore spomenutim promjenama prevlake smanjuju difuziju ugljika za 20-60 % Al-Cu, oko 55 % Al-Si (austenitni) i 75 % Al-Si (feritni) pa mogu osigurati privremenu zaštitu protiv korozije na visokoj temperaturi

    A survey of land suitable for Townsville stylo in the North Kimberley of W.A. 1973

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    The aims of the survey were to - (a) define the extent and actual location of country suitable for the production of non-indigenous pastures; in particular to classify the land for its suitability for Townsville stylo (Styioaanthes hurniiia). (b) map the areas so defined on a land system basis. The area surveyed covered approximately 88 000 sq.km (33 968 sq.miles) and included most of the catchments of the Carson, Drysdale, King Edward, Prince Regent, Charnley, Isdell and Chapman Rivers. It covered the country between latitude 14°S and 17°S and longitude 124°30\u27E and 127°30\u27E.https://researchlibrary.agric.wa.gov.au/books/1008/thumbnail.jp

    Evaporation kinetics of Mg2SiO4 crystals and melts from molecular dynamics simulations

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    Computer simulations based on the molecular dynamics (MD) technique were used to study the mechanisms and kinetics of free evaporation from crystalline and molten forsterite (i.e., Mg2SiO4) on an atomic level. The interatomic potential employed for these simulations reproduces the energetics of bonding in forsterite and in gas-phase MgO and SiO2 reasonably accurately. Results of the simulation include predicted evaporation rates, diffusion rates, and reaction mechanisms for Mg2SiO4(s or l) yields 2Mg(g) + 20(g) + SiO2(g)

    Speciation of Lanthanide Metal Ion Dopants in Microcrystalline All-Inorganic Halide Perovskite CsPbCl3

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    Lanthanides are versatile modulators of optoelectronic properties owing to their narrow optical emission spectra across the visible and near-infrared range. Their use in metal halide perovskites (MHPs) has recently gained prominence, although their fate in these materials has not yet been established at the atomic level. We use cesium-133 solid-state NMR to establish the speciation of all nonradioactive lanthanide ions (La3+, Ce3+, Pr3+, Nd3+, Sm3+, Sm2+, Eu3+, Eu2+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+) in microcrystalline CsPbCl3. Our results show that all lanthanides incorporate into the perovskite structure of CsPbCl3 regardless of their oxidation state (+2, +3).</p

    4-(4-Methylbenzoyl)-6-(4-methylbenzylidene)-3-phenyl-2-oxa-3-azabicyclo 3. 3.0-oct-7-ene

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    The title compound, C28H25NO2, is a minor product resulting from a 1,3-dipolar nitrone-fulvene 3+2 cyclo-addition
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