| 1. |
- Hassellöv, Martin, 1970, et al.
(author)
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REACH missar nano!
- 2009
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In: Miljöforskning. ; 2009:3-4
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Journal article (other academic/artistic)
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| 2. |
- Monks, P. S., et al.
(author)
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Atmospheric composition change : global and regional air quality
- 2009
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 43:33, s. 5268-5350
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Research review (peer-reviewed)abstract
- Air quality transcends all scales with in the atmosphere from the local to the global with handovers and feedbacks at each scale interaction. Air quality has manifold effects on health, ecosystems heritage and, climate. In this review the state of scientific understanding in relation to global and regional air quality is outlined. The review discusses air quality, in terms of emissions, processing and transport of trace gases and aerosols. New insights into the characterization of both natural and anthropogenic emissions are reviewed looking at both natural (e.g. dust and lightning) as well as plant emissions. Trends in anthropogenic emissions both by region and globally are discussed as well as biomass burning emissions. In terms of chemical processing the major air quality elements of ozone, non-methane hydrocarbons, nitrogen oxides and aerosols are covered. A number of topics are presented as a way of integrating the process view into the atmospheric context; these include the atmospheric oxidation efficiency, halogen and HOx chemistry, nighttime chemistry, tropical chemistry, heat waves, megacities, biomass burning and the regional hot spot of the Mediterranean. New findings with respect to the transport of pollutants across the scales are discussed, in particular the move to quantify the impact of long-range transport on regional air quality. Gaps and research questions that remain intractable are identified. The review concludes with a focus of research and policy questions for the coming decade. In particular, the policy challenges for concerted air quality and climate change policy (co-benefit) are discussed.
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| 3. |
- Nadvornik, Milan, et al.
(author)
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Syntheses, X-ray, MSn, NMR and CD structure determination of nickel(II) complexes of Schiff bases of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide and aromatic α-amino acids
- 2008
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In: Polyhedron. - : Elsevier BV. - 0277-5387. ; 27:17, s. 3477-3483
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Journal article (peer-reviewed)abstract
- A preparative procedure for the synthesis of an important chiral synthon of side-chain protected tyrosine was developed and optimised for the minimisation of nickel salts waste. While preparing a similar side-chain protected tryptophan synthon, an unexpected low stability was found of the Boc-protective group of the tryptophan aromatic nitrogen during purification on silica gel. X-ray crystal structure determination, tandem mass spectrometry (MS/MS) and NMR were applied for the elucidation of the structures of the prepared complexes and by-products. Stereochemistry of products of α-methylation of the complexes was assessed using a model tyrosine-derived compound.
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| 4. |
- Retegan Vollmer, Teodora, 1979
(author)
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Investigations of Solvent Systems Based on bis-triazine-bipyridine (BTBP) - class Ligands for the Separation of Actinides from Lanthanides
- 2009
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Doctoral thesis (other academic/artistic)abstract
- Shortages of fossil fuel and other political movements contributed to the nuclear energy “renaissance”.Nuclear energy, however, is not free of challenges, one of them being nuclear waste management. The “once-through” cycle, where the nuclear fuel is used once in the reactor, cooled and finnaly disposed for about 100 000 years is currently used in most of the world. Reprocessing is another alternative, by making new fuel from separated uranium, MOX (Mixed Oxyde fuel). However, the storage time remains the same.An alternative to the storage time and radiotoxicity is partitioning and transmutation (P&T) concept. Transmutation is defined as the transformation of one radionuclide into another by changing its nuclear structure. The partitioning is the process of separation nuclides from the rest of the waste and involves a separation process which utilize an organic solvent containing one or several molecules and a diluent for extraction purposes. Among the last extractant families developed in Europe, used for partitioning, the 6,6’-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]triazin-3-yl)-[2,2’]bipyridine (BTBP) is the most promising molecule for an eventual industrial application. The present work focuses on several aspects insufficiently studied before in relation to a BTBP based extraction system. These aspects include: the importance of the diluents regarding both the extraction capabilities of the formed system with different metals, the role of the diluents in complex formation , the importance of the side groups added to the molecule to facilitate dissolution, easing the phase transfer and thus enhancing the extraction capabilities and also the role of the side groups in complex formation.
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| 5. |
- Camerani, Maria Caterina, et al.
(author)
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Determination of the cd-bearing phases in municipal solid waste and Biomass single fly ash particles using SR-mu XRF Spectroscopy
- 2007
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 79:17, s. 6496-6506
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Journal article (peer-reviewed)abstract
- By using an excitation energy of 27.0 keV, synchrotron radiation-induced micro-X-ray fluorescence (SR-mu XRF) is employed to extract information regarding the composition and distribution of Cd-bearing phases in municipal solid waste (MSW) and biomass fly ashes. Significance of observation is based on statistics of totally more than 100 individual MSW and biomass fly ash particles from a fluidized bed combustion (FBC) plant. Cd concentrations in the parts-per-million range are determined. In general, although previous leaching studies have indicated Cd to be predominant in the smaller-size ash particles, in the present study Cd is more evenly distributed throughout all the particle sizes. For MSW fly ashes, results indicate the presence of Cd mainly as CdBr2 hot-spots, whereas for biomass fly ashes, which exhibit lower CdX2 concentration, a thin Cd layer on/in the particles is reported. For both ashes, Ca-containing matrixes are found to be the main Cd-bearing phases. Support for this observation is found from independent first-principles periodic density functional theory calculations. The observations are condensed into a schematic mechanism for Cd adsorption on the fly ash particles.
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| 6. |
- Brohede, Samuel, 1977, et al.
(author)
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Internal consistency in the Odin stratospheric ozone products
- 2007
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In: Canadian Journal of Physics. - 0008-4204 .- 1208-6045. ; 85:11, s. 1275-1285
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Journal article (peer-reviewed)abstract
- The two independent instruments on the Odin satellite, the Optical Spectrograph and Infrared Imaging System (OSIRIS) and the Sub-Millimetre Radiometer (SMR) produce atmospheric profiles of various atmospheric species including stratospheric ozone. Comparisons are made between OSIRIS version 3.0 and SMR version 2.1 ozone data to evaluate the consistency of the Odin ozone data sets. Results show good agreement between OSIRIS and SMR in the range 25–40 km, where systematic differences are less than 15% for all latitudes and seasons. Larger systematic differences are seen below 25 km, which can be explained by the increase of various error sources and lower signals. The random differences are between 20–30% in the middle stratosphere. Differences between Odin up-scans and down-scans or AM and PM are insignificant in the middle stratosphere. Furthermore, there is little variation from year to year, but a slight positive trend in the differences (OSIRIS minus SMR) of 0.045 ppmv/year at 30 km over validation period (2002–2006). The fact that the two fundamentally different measurement techniques, (absorption spectroscopy of scattering sunlight and emission measurements in the sub-millimetre region) agree so well, provides confidence in the robustness of both techniques.
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| 7. |
- Casari, Barbara M., et al.
(author)
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New Aquapentachlorochromate(III) Compounds: K2[CrCl5(H2O)] and (NH4)2[CrCl5(H2O)]
- 2006
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In: Zeitschrift für Anorganische und Allgemeine Chemie. - 0044-2313 .- 1521-3749. ; 632:1, s. 101-106
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Journal article (peer-reviewed)abstract
- Synthesis and crystal structures of two new compounds, K2[CrCl5(H2O)] (I) and (NH4)2[CrCl5(H2O)] (II) are reported. Both compounds were prepared from chromium(VI) salts by two different methods and reaction pathways of these syntheses are suggested. The crystal structures of these two aquapentachlorochromates(III) have been determined from three dimensional X-ray data collected at low temperature, 173 K. The two structures are isomorphous and their unit cell dimensions are quite similar. They are orthorhombic, space groups Pnma, with Z = 4. Both structures are composed of [CrCl5(H2O)]2- units held together by the counterion framework. The coordination around the chromium ion deviates from a regular octahedron due to the shorter equatorial chromium-oxygen bond.
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| 8. |
- Ivanov, S.A., et al.
(author)
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The magnetoelectric perovskite Sr2CoMoO6: An insight from neutron powder diffraction
- 2005
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In: Materials Research Bulletin. - : Elsevier BV. - 0025-5408. ; 40, s. 840-849
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Journal article (peer-reviewed)abstract
- A study of the crystallographic and magnetic structure of the double perovskite Sr2CoMoO6 (SCMO) has been carried out on a polycrystalline sample using neutron powder diffraction (NPD) data between 10 and 700 K. An analysis of the NPD patterns at room temperature has shown that this compound crystallises in the tetragonal space group I4/m with a = 5.5616(1) Å and c = 7.9470(2) Å and has a 1:1 ordered arrangement of Co and Mo at the B-sites. This compound undergoes a I4/m → Fm3m improper ferroelectric phase transition near 560 K. A low-temperature antiferromagnetic ordering (below TN = 36 K) has been followed from sequential NPD data analysis. The antiferromagnetic structure is defined by the propagation vector k = (1/2, 0, 1/2). In addition to the obtained experimental results on magnetic and electric properties some aspects of magnetoelectricity in this perovskite are also discussed.
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| 9. |
- Ul Islam Zafar, Muhammad Qamar, 2007
(author)
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Oxygen Carriers Materials for Chemical-Looping Technologies
- 2007
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Doctoral thesis (other academic/artistic)abstract
- Carbon dioxide is the gas which contributes most to the greenhouse effect. It is released in large quantities from fossil fuel-based power plants around the world. It is generally accepted that a rapid decrease in the emissions of carbon dioxide is needed. One method to achieve rapid reductions in the emissions and still use fossil fuels is to capture and store the carbon dioxide. However, the separation of carbon dioxide from a flue gas stream of a power plant is an expensive and energy-intensive process resulting in a large decrease in efficiency. Thus there is a need to find cheaper and more efficient methods to perform the separation. Chemical-looping combustion (CLC) and chemical-looping reforming (CLR) are innovative technologies for power and hydrogen production from natural gas with the capture of carbon dioxide. In CLC, CO2 is inherently separated from other flue gas components i.e. N2 and O2 with minor energy losses. With some modifications CLC can be modified for production of hydrogen, i.e. CLR. Both processes involve the use of an oxygen carrier that transfers oxygen from combustion air to the fuel. Two inter-connected fluidized beds, a fuel and an air reactor, are used in the process. Whereas the natural gas is fully oxidized to CO2 and H2O in the fuel reactor for CLC, it is only partially oxidized by the metal oxide in the fuel reactor for CLR, resulting in a mixture of H2, CO2, CO and H2O. The exit stream from the fuel reactor can be sent to a water gas shift reactor to get an undiluted stream of CO2 and H2. The reduced metal oxide is sent into the air reactor where it is oxidized by air. The oxidation reaction is exothermic resulting in heat production in the air reactor. This heat is used to maintain the oxygen carrier particles at the high temperature necessary for the endothermic reaction in the fuel reactor. The hot gases exiting from the air reactor can be used for power production. For the chemical-looping technologies to become successful it is important to find suitable oxygen carriers. This thesis focuses on the development and reactivity testing of such oxygen carriers. For CLR, metal oxides based on Ni, Cu, Mn and Fe were prepared by impregnation on SiO2 and MgAl2O4 and tested in a laboratory fluidized bed reactor as well as a thermo gravimetric analyzer (TGA). The particles were exposed to alternating reducing (50% CH4/ 50% H2O) and oxidizing (5% O2) conditions. With respect to the metal oxides on the SiO2 support, the particles based on NiO and CuO showed the highest reactivity, whereas Fe2O3 and Mn2O3 showed signs of deactivation as function of cycle number, likely due to the formation of metallic silicates. Only NiO showed high selectivity toward H2. All the MgAl2O4-supported metal oxides exhibited high reactivity under reducing and oxidizing conditions. In contrast to the SiO2 based particles, no deactivation as a function of cycle number was seen for any of these oxygen carriers. Reduction and oxidation kinetics of oxygen carriers of NiO/MgAl2O4 and Mn3O4/Mg-ZrO2 for CLC were investigated using methane and air in a TGA. At high temperature both oxygen carriers reacted rapidly under both reducing and oxidizing conditions and the reaction rate was a function of the temperature and concentration of reacting gas. However, it was found that NiO/MgAl2O4 may not be feasible to be used below 900 °C due to low reactivity. The reactions were modelled using the shrinking-core model for spherical grains assuming chemical reaction control and the kinetic parameters were calculated for both oxygen carriers. From the kinetic parameters the solid inventories in a real CLC system were calculated. The minimum solid inventories needed were 22 kg/MWf for NiO/MgAl2O4 and 135 kg/MWf for Mn3O4/Mg-ZrO2. These masses are very low compared to other oxygen carriers investigated previously, and thus both type of particles are very promising for a real CLC system.
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| 10. |
- Haley, C. S., et al.
(author)
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Status of the Odin/OSIRIS stratospheric O3 and NO2 data products
- 2007
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In: Canadian Journal of Physics. - 0008-4204 .- 1208-6045. ; 85:11, s. 1177-1194
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Journal article (peer-reviewed)abstract
- This paper describes the status of the stratospheric ozone and nitrogen dioxide data products from the Optical Spectrograph and InfraRed Imager System (OSIRIS) instrument on the Odin satellite. The current version of the data products is 3.0, covering the period from November 2001 to the present. The O3 and NO2 retrieval methods are reviewed along with an overview of the error analyses and geophysical validation status.
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