Precipitation and hydrolysis of thorium in aqueous solution. V. Studies of the system: thorium Nitrate-Ammonium Oxalate

The precipitation of thorium from aqueous solution of thorium nitrate (1.25 mM) and ammonium oxalate (2.5—80 mM) was investigated at pH from 1 to 10. The following precipitates were identified with the brutto formula: Th(OH)ˇ4 and Th(Cˇ2Oˇ4)ˇ2 X 6 Hˇ2O (by means of Chemical analyses). The soluble thorium oxalato complex is formed between these two precipitates and contains 4 oxalate bound to thorium, with the simplest formula [Th(Cˇ2Oˇ4)ˇ4^4~] (as determined by coulometric titration). Using log Kˇ0 = 34.8 for the dissolution constant of thorium hydroxide in ammonium oxalate bˇ4 for thorium oxalate was obtained: 1.58 X 10^24

Fractionation of iron species and iron isotopes in the Baltic Sea euphotic zone

To indentify sources and transport mechanisms of iron in a coastal marine environment, we conducted measurements of the physiochemical speciation of Fe in the euphotic zone at three different locations in the Baltic Sea. In addition to sampling across a salinity gradient, we conducted this study over the spring and summer season. Moving from the riverine input characterized low salinity Bothnian Sea, via the Landsort Deep near Stockholm, towards the Gotland Deep in the Baltic Proper, total Fe concentrations averaged 114, 44, and 15 nM, respectively. At all three locations, a decrease in total Fe of 80–90% from early spring to summer was observed. Particulate Fe (PFe) was the dominating phase at all stations and accounted for 75–85% of the total Fe pool on average. The Fe isotope composition (δ 56Fe) of the PFe showed constant positive values in the Bothnian Sea surface waters (+0.08 to +0.20‰). Enrichment of heavy Fe in the Bothnian Sea PFe is possibly associated to input of aggregated land derived Fe-oxyhydroxides and oxidation of dissolved Fe(II). At the Landsort Deep the isotopic fractionation of PFe changed between −0.08‰ to +0.28‰ over the sampling period. The negative values in early spring indicate transport of PFe from the oxic-anoxic boundary at ∼80 m depth. The average colloidal iron fraction (CFe) showed decreasing concentrations along the salinity gradient; Bothnian Sea 15 nM; Landsort Deep 1 nM, and Gotland Deep 0.5 nM. Field Flow Fractionation data indicate that the main colloidal carrier phase for Fe in the Baltic Sea is a carbon-rich fulvic acid associated compound, likely of riverine origin. A strong positive correlation between PFe and chl-a indicates that cycling of suspended Fe is at least partially controlled by primary production. However, this relationship may not be dominated by active uptake of Fe into phytoplankton, but instead may reflect scavenging and removal of PFe during phytoplankton sedimentation

Assessing pollution in the Kola river, northwestern Russia, using metal concentrations in water and bryophytes

Intensive Cu-Ni and Fe mining and smelting in northwestern Russia constitutes a potential risk of pollution in the Kola River. We assessed the degree of pollution along the Kola River by means of overall water quality evaluation and analysis of metals in water samples (dissolved and particulate fractions) and aquatic mosses. The observed pollutant levels were compared with those in the unpolluted reference rivers. The results indicate relatively low overall contamination in the Kola River, although Cu and Ni levels are elevated relative to the reference data. Furthermore, PCA ordination models identified clear metal concentration patterns along the river. Al, Cd, Co, Fe, Pb and Zn exhibited an almost continuous increase from the headwaters to the river mouth, whereas As, Ba, Cu, Mn and Ni showed their highest concentrations in the headwaters, close to the mining areas, relatively low concentrations in the middle parts of the river and elevated concentrations at the river mouth. Bryophyte analysis appeared to be more sensitive tool for metal pollution assessment than metal concentrations in the river

A kinetic and theoretical study of the borate catalysed reactions of hydrogen peroxide: the role of dioxaborirane as the catalytic intermediate for a wide range of substrates

Our recent work has provided new insights into the equilibria and species that exist in aqueous solution at different pHs for the boric acid – hydrogen peroxide system, and the role of these species in oxidation reactions. Most recently, (M. C. Durrant, D. M. Davies and M. E. Deary, Org. Biomol. Chem., 2011, 9,7249–7254), we have produced strong theoretical and experimental evidence for the existence of a previously unreported monocyclic three membered peroxide species, dioxaborirane, that is the likely catalytic species in borate mediated electrophilic reactions of hydrogen peroxide in alkaline solution. In the present paper, we extend our study of the borate–peroxide system to look at a wide range of substrates that include substituted dimethyl anilines, methyl-p-tolyl sulfoxide, halides, hydrogen sulfide anion, thiosulfate ,thiocyanate, and hydrazine. The unusual selectivity–reactivity pattern of borate catalysed reactions compared with hydrogen peroxide and inorganic or organic peracids previously observed for theorganic sulfides (D. M. Davies, M. E. Deary, K. Quill and R. A. Smith, Chem.–Eur. J., 2005, 11, 3552–3558) is also seen with substituted dimethyl aniline nucleophiles. This provides evidence that the pattern is not due to any latent electrophilic tendency of the organic sulfides and further supports dioxaborirane being the likely reactive intermediate, thus broadening the applicability of this catalytic system. Moreover, density functional theory calculations on our proposed mechanism involving dioxaborirane are consistent with the experimental results for these substrates. Results obtained at high concentrations of both borate and hydrogen peroxide require the inclusion the diperoxodiborate dianion in the kinetic analysis .A scheme detailing our current understanding of the borate–peroxide system is presented

Iron biogeochemistry across marine systems progress from the past decade

Based on an international workshop (Gothenburg, 14–16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas

Virtual Reality in Design Processes: - a literature review of benefits, challenges, and potentials

Virtual Reality (VR) opens new possibilities in the fields of architecture, design and engineering. If combined with Building Information Modelling (BIM) or simpler 3D models, it could be possible to walk into buildings not yet built or to examine designed objects in three dimensions before they are made. This literature review examines studies in which VR was used in architecture, design and engineering as part of design processes. The review highlights promising benefits, such as increased understanding of complex issues concerning design tasks, size and dimensions. At the same time, several challenges are revealed, such as the inability of VR-systems to offer satisfactory functionalities for sketching and designing. Finally, the author discusses how VR can be implemented in relevant subjects in lower and upper secondary school.Virtual Reality (VR) opens new possibilities in the fields of architecture, design and engineering. If combined with Building Information Modelling (BIM) or simpler 3D models, it could be possible to walk into buildings not yet built or to examine designed objects in three dimensions before they are made. This literature review examines studies in which VR was used in architecture, design and engineering as part of design processes. The review highlights promising benefits, such as increased understanding of complex issues concerning design tasks, size and dimensions. At the same time, several challenges are revealed, such as the inability of VR-systems to offer satisfactory functionalities for sketching and designing. Finally, the author discusses how VR can be implemented in relevant subjects in lower and upper secondary school

Intertextuality in The Perks of Being a Wallflower: coming-of-age novels in the twentieth century

In The Perks of Being a Wallflower (1999) by Stephen Chbosky the protagonist, Charlie, reads and comments on many coming-of-age novels. This serves to invoke the converging genres of the coming-of-age novel and the Bildungsroman, and it is this feature of the novel that provides the main focus of the thesis. The chapters will provide comparative analyses of two of the works that Charlie reads: This Side of Paradise (1920) by F. Scott Fitzgerald and The Catcher in The Rye (1951) by J. D. Salinger, to show how Chbosky’s novel engages with them and how the coming-of-age novel has developed in the twentieth century. Since The Perks of Being a Wallflower is an epistolary novel and a young adult novel, central features of those genres will also be discussed