Phytoextraction of Cr(VI) from soil using Portulaca oleracea

Cr(VI) represents an environmental challenge in both soil and water as it is soluble and bioavailable over a wide range of pH. In previous investigations, Portulaca oleracea (a plant local to the United Arab Emirates (UAE)) demonstrated particular ability for the phytoextraction of Cr(VI) from calcareous soil of the UAE. In this publication, the results of the evaluation of P. oleracea phytoextraction of Cr(VI) from UAE soil at higher concentrations are reported. P. oleracea was exposed to nine different concentrations of Cr(VI) in soil from 0 to 400 mg kg−1. The uptake of Cr(VI) increased as its concentration in soil increased between 50 and 400 mg kg−1, with the most efficient removal in the range from 150 to 200 mg kg−1. The total chromium concentrations exceeded 4600 mg kg−1 in roots and 1400 mg kg−1 in stems, confirming the role of P. oleracea as an effective Cr(VI) accumulator. More than 95% of the accumulated Cr(VI) was reduced to the less toxic Cr(III) within the plant

Fluorimetric determination of iron using 5-(4-methoxyphenylazo)-8-(4-toluenesulfonamido)quinoline

A highly sensitive and relatively interference-free fluorimetric method for the determination of iron(III) is described. The method is based on the reaction between iron(III) and 5-(4-methoxyphenylazo)-8- (4-toluenesulfonamido)quinoline in the presence of cetyltrimethylammonium bromide. The fluorescence intensity (ex = 317 nm, em = 534 nm) is linear up to 3 µM (170 ng ml–1) iron(III) in aqueous solution with a repeatability (RSD) of 3.2% at a concentration of 180 nM (10 ng ml–1) and a detection limit (3s) of 2 nM (0.12 ng ml–1). The influence of reaction variables and the effect of interfering ions are reported. The proposed procedure was applied to the determination of trace amounts of iron(III) and total iron in tap water, canal water and wine samples without the need for preconcentration, pre-separation or organic solvent extractio

Investigation of the Cancer Cluster of Galaxies

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A structural study of dithizone coordination chemistry

Dithizone, since its discovery in 1878, has become essential in colorimetric assays for numerous transition metal ions. However, despite it being a vital reagent its coordination chemistry is not fully understood. Here we give insight into the binary complexes of dithizone, which contain two different metal ions, and the secondary complexes with Cu(II) which can either involve reduction of the metal ion or double deprotonation of dithizone giving the self-assembled [(H-DPTC)8Cu8] and [(DPTC)4Cu4] species respectively

A kinetic study of the enhancement of solution chemiluminescence of glyoxylic acid oxidation by manganese species

In order to study the mechanism of the enhancement of solution chemiluminescence, the kinetics of the decay of the oxidant and the chemiluminescence emission were followed for oxidations by permanganate, manganese dioxide sol and Mn3+(aq) of glyoxylic acid, using stopped-flow spectrophotometry. Results are reported for the glyoxylic acid oxidized under pseudo first-order conditions and in an acidic medium at 25 °C. For permanganate under these conditions, the decay is sigmoidal, consistent with autocatalysis, and for manganese dioxide sol and Mn3+ it is pseudo first order. The effects of the presence of aqueous formaldehyde and Mn2+ were observed and a fit to a simple mechanism is discussed. It is concluded that chemiluminescent enhancement in these systems is best explained by reaction kinetic

Micro-raman scattering properties of highly oriented ain films

Micro-Raman scattering by highly oriented crystalline aluminum nitride has been measured. Phonon modes in AIN were identified in different scattering geometry configurations and scattering polarizations. The phonon modes revealed that aluminum nitride films are highly oriented with the wurtzite c-axis direction normal to the film plane. The Raman scattering modes are broadened and shifted due to grain boundaries and other defects in the films. The defect scattering was analysed using the phonon confinement model. These results were compared with results obtained from X-ray diffraction powder patterns and high-resolution transmission electron microscopy