| 11. |
- Ahlgren, Joakim, et al.
(author)
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Sediment Depth Attenuation of Biogenic Phosphorus Compounds Measured by 31P NMR
- 2005
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In: Environmental Science and Technology. - Univ Uppsala, Dept Analyt Chem, SE-75124 Uppsala, Sweden. Univ Uppsala, Dept Ecol & Evolut, Uppsala, Sweden. Univ Uppsala, Dept Organ Chem, SE-75124 Uppsala, Sweden. : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 39:3, s. 867-872
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Journal article (peer-reviewed)abstract
- Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using 31P NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these compound groups are about 10 yr for pyrophosphate and 2 decades for mono- and diesters. Probably, these compounds will be mineralized to ortho-P and is thus potentially available for recycling to the water column, supporting further growth of phytoplankton. In conclusion, 31P NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible.
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| 12. |
- Benkestock, Kurt, et al.
(author)
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Automated Nano-Electrospray Mass Spectrometry for Protein-Ligand Screening by Noncovalent Interaction Applied to Human H-FABP and A-FABP
- 2003
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In: Journal of Biomolecular Screening. - : Elsevier BV. - 1087-0571 .- 1552-454X. ; 8:3, s. 247-256
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Journal article (peer-reviewed)abstract
- A method for ligand screening by automated nano-electrospray ionization mass spectrometry (nano-ESI/MS) is described. The core of the system consisted of a chip-based platform for automated sample delivery from a 96-well plate and subsequent analysis based on noncovalent interactions. Human fatty acid binding protein, H-FABP (heart) and A-FABP (adipose), with small potential ligands was analyzed. The technique has been compared with a previously reported method based on nuclear magnetic resonance (NMR), and excellent correlation with the found hits was obtained. In the current MS screening method, the cycle time per sample was 1.1 min, which is approximately 50 times faster than NMR for single compounds and approximately 5 times faster for compound mixtures. High reproducibility was achieved, and the protein consumption was in the range of 88 to 100 picomoles per sample. Furthermore, a novel protocol for preparation of A-FABP without the natural ligand is presented. The described screening approach is suitable for ligand screening very early in the drug discovery process before conventional high-throughput screens (HTS) are developed and/or used as a secondary screening for ligands identified by HTS.
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| 13. |
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| 14. |
- Bjelosevic, Haris, et al.
(author)
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Synthesis and structural characterisation of novel platinum-based drug candidates with extended functionality by incorporation of bis(diphenylphosphino)ferrocene units as metal chelators
- 2006
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In: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 62:18, s. 4519-4527
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Journal article (peer-reviewed)abstract
- Among the metal-based anticancer drugs, cisplatin (cis-diaminedichloroplatinum(II)) is the most widely used species in therapy. Despite its clinical success, cisplatin still suffers in generating resistance, as well as being highly toxic due to poor selectivity between healthy and sick cells. By molecular design it ought to be possible to generate new cis-platinum compounds with increased selectivity and improved cellular behaviour. In this paper, we report a synthetic pathway for construction of derivatives of 1,1'-bis(diphenylphosphino)-ferrocene, together with their corresponding cis-platinum compounds with the aim testing them for their interaction capacity with respect to various DNA models. We also report a synthetic route for a nucleoside-based cis-platinum compound containing a bidentate ferrocenylphosphine derivative connected through a succinamic-based linker to the 5-position of the heterocyclic moiety of uridine. Our preliminary kinetic investigation of 5-{N-[1-[1',2-bis(diphenylphosphino)ferrocenyl]ethyl]1-N'-[prop-2-yn-3-y l]succinamide} uridinedichloroplatinum(II) showed that this compound reacted faster with the phosphorothioate containing oligonucleotides d(T(6)p(S)T-6), with an observed first-order rate constant k(obs) = (1.4 +/- 0.1) X 10(-4) s(-1), compared with the G-N7 target in d(T(7)GGT(7)), for which the observed first-order rate constant is k(obs) = (7.2 +/- 0.5) X 10(-4) s(-1). (c) 2006 Elsevier Ltd. All rights reserved.
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| 15. |
- Braungardt, C. B., et al.
(author)
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Analysis of dissolved metal fractions in coastal waters: An inter-comparison of five voltammetric in situ profiling (VIP) systems
- 2009
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In: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 114:1-2, s. 47-55
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Journal article (peer-reviewed)abstract
- This paper presents the results of an inter-comparison exercise undertaken to test the reliability and performance of a voltammetric in situ profiling system (VIP system) and carried out by partners based in Italy, Sweden, Switzerland and the UK. The VIP system was designed to allow in situ simultaneous monitoring of the dynamic fractions (i.e. the maximum potentially bioavailable fractions) of Cu(II). Pb(II) and Cd(II) in natural waters at a frequency of 2-3 analyses h(-1). The four participating groups used the VIP systems under laboratory conditions to determine dissolved concenterations of Cu, Pb and Cd in river, estuarine and coastal water reference materials (SLRS-3/4, SLEW-2/3 and CASS3/4, respectively). The accuracy of the VIP method was comparable to that of established methodologies, including inductively coupled plasma mass spectrometry and voltammetric methods using mercury-electrodes. The VIP systems were also applied to determine the dynamic fractions of the target analytes in freshly collected samples ex situ, as well as in situ in contrasting European marine waters. There was good agreement between the concentrations of the dynamic metal fractions determined in laboratory analyses, and observed during the Simultaneous deployment of up to five VIP instruments for periods of several hours in coastal waters. The simultaneous in situ deployment of two VIP instruments in an estuary showed a consistent analytical performance over several days of continuous operation. The results of this inter-comparison exercise show that the VIP system is a reliable submersible probe for accurate, sensitive and high resolution in situ monitoring of dissolved metal fractions in the picomolar (Cd, Pb) and nanomolar (Cu) concentration ranges. (C) 2009 Elsevier B.V. All rights reserved.
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| 16. |
- Bridle, Helen, 1979
(author)
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Techniques to manipulate the environment around and inside single cells
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Several methods for extending the functionality of a commercially available microfluidic system have been developed to allow for the manipulation of the extracellular and intracellular environments. The microfluidic system generates a chemically patterned laminar flow in an open volume. Objects, such as electrodes or cells, scanned through the patterned flow sequentially experience different solution environments with millisecond solution exchange times. The original device offered the advantages of access to numerous solution environments with rapid, millisecond exchange times and had proven useful in ion channel screening. The developments in this thesis allow for the delivery of complex input patterns, both in and around cells, with the possibility to update exposure patterns over time, facilitating an unprecedented level of control over the cellular environment both in terms of solution composition and temperature.In order to mimic physiologically observed oscillations, algorithms for waveform creation were devised, which allow for the generation and emulation of complex variations in the concentration of substances on relevant time (i.e. ms-to-minutes) and length scales (i.e. around sub-micrometer-to-micrometer-sized objects such as single organelles and single cells). By incorporating valves to switch between different input solutions in each flow segment, the laminar flow pattern can be updated over time. This allows for access to a greater number of different solutions, as well as the possibility of mixing solutions on-chip. Addition of resistive heating coils facilitates control of the temperature during experiments to study temperature-dependent effects and to obtain thermodynamic information such as activation energies. To control the intracellular chemistry within whole cells, in order to generate intracellular waveforms or gradients as well as screen and titrate intracellular enzymes and receptors in an in situ environment, the microfluidic system was combined with a chemical method for increasing the cell membrane permeability. The modified system(s), presented in this thesis have many biological applications, including receptor screening, investigation of receptor kinetics and studies of signaling pathways and oscillations. This system would also be useful in any application where a high degree of control over exposure patterns is required. Additionally, the development strategies described here could easily be applied to extend the function of other microfluidic devices.
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| 17. |
- 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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| 18. |
- 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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| 19. |
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| 20. |
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