| 1. |
- Nyström-Larsson, Ingalill, 1969, et al.
(author)
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Materialanalys av sydsvenskt bonadsmåleri
- 2007
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In: Rapport: Sammanfattning av Riksantikvarieämbetets seminarieserie 2007 kring pågående FoU-projekt. ; , s. 23-24
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Conference paper (other academic/artistic)abstract
- Bonadsmåleriet hade sin storhetstid 1750-1850, och var influerat av medeltida kalkmåleri och bildvävnad i kyrkorna. Bonaderna var temporära och prydde stugorna till fest. Motiven kan vara både bibliska och profana. Materialet är tyger (återanvända och hopfogade) och senare även papper. Mot slutet av perioden övergår hantverket i massproduktion. Tidigare har bonaderna framför allt studerats inom humaniora (exempelvis etnologi) och ett naturvetenskapligt perspektiv har saknats. Därför finns mycket knapphändiga uppgifter om materialet. Syftet med projektet är att: • Kartlägga materialanvändningen • Tolka och förstå materialutvecklingen • Klarlägga innehållet i de otydliga trivialnamnen • Bygga upp ett referensmaterial Genomförande Ett antal frågeställningar har satts upp inför studiet: • Vilka materialval har man gjort? • Skiljer måleriteknik, färg, materialval mellan bonader, och går det att urskilja geografiska skillnader eller är det en tidsmässig utveckling? • Kan bonader attribueras utifrån materialval och färgval? • Vad är det för pigment som döljs i trivialnamnen? Skriftliga källor räcker inte för att svara på dessa frågor utan måste komplet-teras med naturvetenskapliga analyser. Diskussion kring RÄA-seminariets specifika frågeställningar På vad sätt bidrar ert projekt till kunskapsuppbyggnaden inom ert område? • Projektet är också ett pilotprojekt och den kunskap som vinns kan också appliceras på annat än bonadsmåleri. Utifrån resultaten kan man också gå vidare och titta på handelsvägar, infrastruktur etc. • En referensdatabas byggs upp och kan kanske också användas för an-nat material. På vilket sätt skulle resultaten från ert projekt kunna tillämpas mer konkret inom kulturmiljösektorn? • Ett viktigt mål är att hitta analysmetoder som inte förstör materialet, och som helst kan göras på plats så att materialet inte behöver flyttas (Raman spektroskopi). • Som konstaterades ovan kan resultaten från den kemiska analysen visa att en sådan kan komplettera traditionella historiska metoder också inom andra områden än bonadsmåleri. Frågor och öppen diskussion • Ännu har man inte hittat några speciella pigment eller färger, men analysen är inte klar. • Analysmaterialet som valts ut är signerade bonader. • Eftersom uppbyggandet av referensdatabaser är centralt i konserva-torns arbete är det viktigt att sprida resultaten av projektet.
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| 2. |
- Gejke, Cecilia, 1973, et al.
(author)
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The effect of lithium insertion on the structure of tin oxide-based glasses
- 2001
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In: Journal of Power Sources. - 0378-7753. ; 97-98, s. 226-228.
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Journal article (peer-reviewed)abstract
- Two different SnO-based glasses, Sn2B3O6.5 and Sn2B2AlO6.5, have been examd. with FT-IR and Raman spectroscopy at different stages during the first electrochemical cycle. Some disruption of the connection between borate units in the network occurred during cycling. There was also an irreversible formation of Li3BO3 that can be related to the large capacity loss.
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| 3. |
- Björnström, Joakim, 1976, et al.
(author)
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Antagonistic effect of superplasticizer and colloidal nano-silica in the hydration of Alite and Belite pastes
- 2007
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In: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 42:11, s. 3901-3907
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Journal article (peer-reviewed)abstract
- The dependence on the hydration rate for Alite and Belite clinker phases in the presence of a polycarboxylate superplasticizer PC SP upon addition of colloidal nano-silica CNS were monitored by means of Diffuse Reflectance Infrared spectroscopy DR-FTIR. Spectral signatures of clinker dissolution and product formation were acquired for both materials. The rates for the build-up of product vibrational band intensities were found to depend sensitively on addition of CNS. The hydration product was proposed to be calcium-silicate-hydrate C-S-H. Details in the spectral signatures were found to differ. Quantum chemical calculations were employed and found to be consistent with the interpretation that small clusters dominate the Alite C-S-H spectrum, whereas the Belite C-S-H spectrum results from extended polymers.
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| 4. |
- Börjesson, Karl, 1982, et al.
(author)
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Nucleic Acid Base Analog FRET-Pair Facilitating Detailed Structural Measurements in Nucleic Acid Containing Systems
- 2009
-
In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 131:12, s. 4288-4293
-
Journal article (peer-reviewed)abstract
- We present the first nucleobase analog fluorescence resonance energy transfer (FRET)-pair. The pair consists of tC O , 1,3-diaza-2- oxophenoxazine, as an energy donor and the newly developed tC nitro , 7-nitro-1,3-diaza-2-oxophenothiazine, as an energy acceptor. The FRET-pair successfully monitors distances covering up to more than one turn of the DNA duplex. Importantly, we show that the rigid stacking of the two base analogs, and consequently excellent control of their exact positions and orientations, results in a high control of the orientation factor and hence very distinct FRET changes as the number of bases separating tC O and tCnitro is varied. A set of DNA strands containing the FRET-pair at wisely chosen locations will, thus, make it possible to accurately distinguish distance- from orientation-changes using FRET. In combination with the good nucleobase analog properties, this points toward detailed studies of the inherent dynamics of nucleic acid structures. Moreover, the placement of FRET-pair chromophores inside the base stack will be a great advantage in studies where other (biomacro)molecules interact with the nucleic acid. Lastly, our study gives possibly the first truly solid experimental support to the dependence of energy transfer efficiency on orientation of involved transition dipoles as predicted by the Forster theory. © 2009 American Chemical Society.
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| 5. |
- 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
-
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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| 6. |
- Abrahamsson, Maria, et al.
(author)
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Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands.
- 2008
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In: Inorganic Chemistry. - : ACS. - 0020-1669 .- 1520-510X. ; 47:9, s. 3540-3548
-
Journal article (peer-reviewed)abstract
- The structural effect on the metal-to-ligand charge transfer (MLCT) excited-state lifetime has been investigated in bis-tridentate Ru(II)-polypyridyl complexes based on the terpyridine-like ligands [6-(2,2'-bipyridyl)](2-pyridyl)methane (1) and 2-[6-(2,2'-bipyridyl)]-2-(2-pyridyl)propane (2). A homoleptic ([Ru(2)(2)](2+)) and a heteroleptic complex ([Ru(ttpy)(2)](2+)) based on the new ligand 2 have been prepared and their photophysical and structural properties studied experimentally and theoretically and compared to the results for the previously reported [Ru(1)(2)](2+). The excited-state lifetime of the homoleptic Ru-II complex with the isopropylene-bridged ligand 2 was found to be 50 times shorter than that of the corresponding homoleptic Ru-II complex of ligand 1, containing a methylene bridge. A comparison of the ground-state geometries of the two homoleptic complexes shows that steric interactions involving the isopropylene bridges make the coordination to the central Ru-II ion less octahedral in [Ru(2)(2)](2+) than in [Ru(1)(2))(2+). Calculations indicate that the structural differences in these complexes influence their ligand field splittings as well as the relative stabilities of the triplet metal-to-ligand charge transfer ((MLCT)-M-3) and metal-centered ((MC)-M-3) excited states. The large difference in measured excited-state lifetimes for the two homoleptic Ru-II complexes is attributed to a strong influence of steric interactions on the ligand field strength, which in turn affects the activation barriers for thermal conversion from (MLCT)-M-3 states to short-lived (MC)-M-3 states.
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| 7. |
- Bohlin, Christina, et al.
(author)
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Product profiles in enzymic and non-enzymic oxidations of the lignin model compound erythro-1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol
- 2005
-
In: Journal of Molecular Catalysis - B Enzymatic. - : Elsevier BV. - 1381-1177 .- 1873-3158. ; 35:4-6, s. 100-107
-
Journal article (peer-reviewed)abstract
- The erythro form of the lignin model compound 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol (1) was oxidized with laccase/ABTS, lead(IV) tetraacetate (LTA), lignin peroxidase/H2O2, cerium(IV) ammonium nitrate (CAN) and Fenton's reagent. The product profiles obtained with the different oxidants were compared after separation, identification and quantification of the products using HPLC, UV-diode array detector and electrospray ionization mass spectrometry in positive ionization mode. The oxidants generated different product profiles that reflected their different properties. Oxidation with laccase/ABTS resulted almost exclusively in formation of 1-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxyphenoxy)-1-propanone (2). Oxidation with LTA resulted in more 3,4-dimethoxybenzaldehyde (3) than ketone 2. Lignin peroxidase and CAN gave similar product profiles and aldehyde 3 was the predominant product (only small amounts of ketone 2 were formed). Oxidation with Fenton's reagent resulted in the formation of more aldehyde 3 than ketone 2 but the yields were very low. CAN served as an excellent model for the lignin peroxidase-catalyzed oxidation, while the laccase-mediator system, LTA and Fenton's reagent provided distinctly different product profiles. Erythro-1-(3,4-dimethoxyphenyl)-1,2,3-propanetriol was present among the products obtained on oxidation with LTA, lignin peroxidase, CAN and Fenton's reagent. The differences in redox potential between the oxidants afford an explanation of the diverse product patterns but other factors may also be of importance. The reactions leading to cleavage of the β-ether bond with formation of 1-(3,4-dimethoxyphenyl)-1,2,3-propanetriol (veratrylglycerol) were found to proceed without affecting the configuration at the β-carbon atom.
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| 8. |
- 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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| 9. |
- Gejke, Cecilia, 1973, et al.
(author)
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Structural investigation of the Li+ ion insertion/extraction mechanism in Sn-based composite oxide glasses
- 2001
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In: Journal of Physics and Chemistry of Solids. - 0022-3697. ; 62, s. 1213-1218.
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Journal article (peer-reviewed)abstract
- The effect of lithium insertion for two Sn-based composite oxide glasses, Sn2BPO6 and Sn2P2O7, was examined during the first electrochemical discharge/charge cycle. Electrodes based on these glasses were analysed with micro-Raman spectroscopy at different steps during the cycle. In-situ X-ray diffraction has been used to confirm the amorphous state during the lithium insertion and extraction process. No alloy formation between Li and Sn could be discerned throughout the first cycle. It was found that when lithium enters the electrode, a reaction at the surface of the glass particles takes place resulting in Li3PO4, Li2O and SnO2 formation. The charge compensation mechanism is thought to be the reduction of Sn2+ to Sn. The formation of Li3PO4 is found to be irreversible and is as such partly responsible for the large observed capacity loss during the first cycle.
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| 10. |
- Ahlgren, Joakim, et al.
(author)
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Biogenic phosphorus in oligotropic mountain lake sediments: Differences in composition measured with NMR spectroscopy
- 2006
-
In: Water Research. - Uppsala Univ, Dept Phys & Analyt Chem, S-75124 Uppsala, Sweden. Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Uppsala Univ, Dept Organ & Biol Chem, S-75123 Uppsala, Sweden. Uppsala Univ, Dept Ecol & Evolut, EBC, S-75236 Uppsala, Sweden. : Elsevier BV. - 0043-1354 .- 1879-2448. ; :40, s. 3705-3712
-
Journal article (peer-reviewed)
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| 11. |
- Ahlgren, Joakim, et al.
(author)
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Sediment Depth Attenuation of Biogenic Phosphorus Compounds Measured by 31P NMR
- 2005
-
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
-
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
-
In: Journal of Biomolecular Screening. - : Elsevier BV. - 1087-0571 .- 1552-454X. ; 8:3, s. 247-256
-
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
-
In: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 62:18, s. 4519-4527
-
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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| 21. |
- Francisco, J D, et al.
(author)
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Liquid crystalline properties and extractability of monoolein-water systems by supercritical carbon dioxide
- 2003
-
In: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - 0927-7757. ; 213:1, s. 69-78
-
Journal article (peer-reviewed)abstract
- The influence of phase structure on the extraction recovery of monoolein from monoolein-water systems by supercritical carbon dioxide was investigated. Two monoolein-water mi tures at concentrations of 9 wt% water and 18 wt% water, respectively, were studied. H-2-NMR was used to monitor changes of the phase structures in supercritical conditions. The results showed that the phase structure and the water-monoolein interactions play a role on the extraction yield. The monoolein recovery was higher in the 9 wt% water sample in which L-alpha phase was present compared to the 18 wt% water sample in which the L-alpha melted to yield a L-2 phase. When the phase structures were the same in both samples, the extraction recovery was determined by the solubility properties of the components of the system. The changes due to the presence of supercritical carbon dioxide were shown also to depend on the water concentration of the monoolein-water mixture besides the temperature. The 18 wt% mixture showed a L-2 phase structure in all the range of the temperature investigated while the 9 wt% water mixture showed phase changes from L-alpha phase to L-2 phase in the same temperature range. (C) 200 Elsevier Science B.V. All rights reserved.
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| 22. |
- Fransson, Agneta, 1964, et al.
(author)
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Oceanic carbonate system in the climatically sensitive Amundsen and Ross Seas, Southern Ocean
- 2009
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In: 8th International Carbon dioxide conference, 13 to 19th of September 2009, Jena, Germany.
-
Conference paper (peer-reviewed)abstract
- During three expeditions (2006, 2007/2008 and 2008/2009) in the Pacific sector of the Southern Ocean in austral summer, the IB Oden acted as research platform in the climatically sensitive oceans of the Amundsen and Ross Seas. Continuous underway measurements of fCO2 and sampling of seawater were performed to study the carbonate system parameters. Along the route, we encountered both open water and heavy pack ice, starting from South Chile, crossing Drake Passage, and continuing through the Amundsen Sea to the Ross Sea. Large variability in fCO2 was observed in different areas and between years, linked to varying sea ice conditions, biological production and physical processes. Sea-air CO2 fluxes were calculated using wind speed data together with measured fCO2 in seawater and air. Total alkalinity (AT) and pH were used together with salinity and sea surface temperature to investigate the effect of CO2 in the surface water. We calculated the carbonate ion concentration [CO32-] and the saturation of aragonite (ΩAr) and calcite (ΩCa) in the surface water and found low [CO32-] and low saturation levels with regard to aragonite (ΩAr < 1.2) at several locations.
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| 23. |
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| 24. |
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| 25. |
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| 26. |
- Johnsson, Anna, 1975, et al.
(author)
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Bioligand-mediated partitioning of radionuclides to the aqueous phase
- 2008
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In: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 277:3, s. 637-644
-
Journal article (peer-reviewed)abstract
- The aqueous-phase partitioning of 59Fe, 147Pm, 234Th and 241Am by complexing compounds from subsurface bacteria has previously been studied in the presence of quartz sand. In this study the aqueous-phase partitioning of pico- to submicromolar amounts of 59Fe, 147Pm, 234Th and 241Am was analyzed in the presence of TiO2 and exudates from three species of subsurface bacteria: Pseudomonas fluorescens, Pseudomonas stutzeri, and Shewanella putrefaciens. All were grown under aerobic conditions and P. stutzeri and S. putrefaciens were grown under anaerobic conditions as well. The supernatants of the aerobic and anaerobic cultures were collected and radionuclide was added. TiO2, with BET surface area of 49.9 m2·g-1, was added to the supernatant radionuclide mix, and the pH was adjusted to approximately 8. After incubation, the amount of radionuclide in the liquid phase of the samples and controls was analyzed using scintillation method. Two types of values were calculated: solution% = the activity maintained in solution relative to the total activity, and Q-values = the quotient between the activity in samples and the activity in controls. Aerobic supernatants had solution% values between 89% and 100% for 59Fe and between 18 and 43% for 234Th. The solution% values for 241Am and 147Pm were less than 2% overall, but the Q-values were between 34 and 115 times more 241Am in bacterial supernatants than in controls. The corresponding values for 147Pm ranged from 6 to 20 times more than in the control. The solution% values for all elements in the presence of anaerobic supernatants were below 2%, but the Q-values clustered around 7 for 59Fe and ranging from 2 to 29 for 234Th, indicated that anaerobic supernatants partitioned these elements to the aqueous phase. Both aerobic and anaerobic supernatants tested positive for complexing compounds when analyzed, using the Chrome Azurol S assay. Complexation with excreted organic ligands is most likely the reason for the higher amounts of metals in samples than in the controls. Hence, aerobically and anaerobically excreted organic ligands seem able to influence the mobility of radionuclides in aerobic and anaerobic environments contaminated with these compounds.
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| 27. |
- Karlsson, Isabella, 1980, et al.
(author)
-
Photodegradation of Dibenzoylmethanes: Potential Cause of Photocontact Allergy to Sunscreens
- 2009
-
In: Chemical Research in Toxicology. - : American Chemical Society (ACS). - 0893-228X .- 1520-5010. ; 22:11, s. 1881-1892
-
Journal article (peer-reviewed)abstract
- One of the most frequently observed photoallergens today is the sunscreen agent 4-tert-butyl-4′-methoxy dibenzoylmethane (1a). The structurally similar compound, 4-isopropyldibenzoylmethane (1b), was a common cause of sunscreen allergy in the eighties and early nineties but was removed from the market in 1993 and replaced with dibenzoylmethane 1a. We have studied the photodegradation of the dibenzoylmethane 1a, to better understand how these substances cause an immune reaction. Several expected degradation products were formed and identified. Of these, arylglyoxals and benzils were of particular interest because they were unexplored as potential contact allergens. The allergenic potential of photodegraded 1a was evaluated by screening the formed arylglyoxals and benzils for their sensitizing capacity in the murine local lymph node assay. The arylglyoxals were found to be strong sensitizers. They were also found to be highly reactive toward the nucleophile arginine, which indicates that the immunogenic hapten-protein complex could be formed via an electrophilic-nucleophilic pathway. By varying the electron-withdrawing or -donating capacity of the substituent in the para position of the arylglyoxal, the electronic effects were shown to have no significant impact on either the sensitizing or the electrophilic power of arylglyoxals. Thus, a change in the substitution pattern of the parent dibenzoylmethane will not influence the sensitizing capacity of the products formed from them upon photodegradation. Furthermore, the combined studies of benzils, using the local lymph node assay and a cell proliferation assay, indicate that the benzils are cytotoxic rather than allergenic. Taken together, this study presents strong indication that photocontact allergy to dibenzoylmethanes is caused by the arylglyoxals that are formed upon photodegradation.
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| 28. |
- Kaukoranta, Päivi, et al.
(author)
-
Iridium Catalysts with Chiral Imidazole-Phosphine Ligands for Asymmetric Hydrogenation of Vinyl Fluorides and other Olefins
- 2008
-
In: Advanced Synthesis and Catalysis. - : Wiley. - 1615-4150 .- 1615-4169. ; 350:7-8, s. 1168-1176
-
Journal article (peer-reviewed)abstract
- New chiral bidentate imidazole-phosphine ligands have been prepared and evaluated for the iridium-catalysed asymmetric hydrogenation of olefins. The imidazole-phosphine-ligated iridium catalysts hydrogenated trisubstituted olefins with the same sense of enantiodiscrimination as known iridium catalysts possessing oxazole and thiazole as N-donors. The imidazole-based catalysts were shown to hydrogenate vinyl fluorides, in some cases with the highest ee values published to date.
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| 29. |
- Matveeva, E. G., et al.
(author)
-
Red blood cells do not attenuate the SPCE fluorescence in surface assays
- 2007
-
In: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 388:5-6, s. 1127-1135
-
Journal article (peer-reviewed)abstract
- We describe the positive effect of surface plasmon-coupled fluorescence emission (SPCE) on the detection of a signal from a surface immunoassay in highly absorbing or/and scattering samples. A model immunoassay using fluorescently labeled anti-rabbit antibodies that bind to rabbit immunoglobulin on a silver surface was performed, and the signal was detected in the presence of various highly absorbing and/or scattering solutions or suspensions, such as hemoglobin solution, plastic beads, and red blood cells. The results showed that a highly absorbing solution consisting of small molecules (dye, hemoglobin) attenuates the SPCE signal approximately 2-3-fold. In contrast, suspensions with the same absorption containing large particles (large beads, red blood cell suspension) attenuate the SPCE signal only slightly, approximately 5-10%. Also, a suspension of large undyed, highly scattering beads does not reduce the SPCE signal. The effects on the immunoassay signal of the sample background absorption and scattering, the size of the background particles, and the geometry of the experimental set-up are discussed. We believe that SPCE is a promising technique in the development of biosensors utilized for surface-based assays, as well as any assays performed directly in highly absorbing and/or scattering solutions without washing or separation procedures.
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| 30. |
- Midander, Klara, 1979-
(author)
-
Metal Particles – Hazard or Risk? Elaboration and Implementation of a Research Strategy from a Surface and Corrosion Perspective
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- Do metal particles (including particles of pure metals, alloys, metal oxides and compounds) pose a hazard or risk to human health? In the light of this question, this thesis summarizes results from research conducted on metal particles, and describes the elaboration and implementation of an in vitro test methodology to study metal release from particles through corrosion and dissolution processes in synthetic biological media relevant for human exposure through inhalation/ingestion and dermal contact. Bioaccessible metals are defined as the pool of released metals from particles that potentially could be made available for absorption by humans or other organisms. Studies of bioaccessible metals from different metal particles within this thesis have shown that the metal release process is influenced by material properties, particle specific properties, size distribution, surface area and morphology, as well as the chemistry of synthetic biological test media simulating various human exposure scenarios. The presence of metal particles in proximity to humans and the fact that metals can be released from particles to a varying extent is the hazard referred to in the title. The bioavailable metal fraction of the released metals (the fraction available for uptake/absorption by humans through different exposure routes) is usually significantly smaller than the bioaccessible pool of released metals, and is largely related to the chemical form and state of oxidation of the released metals. Chemical speciation measurements of released chromium for instance revealed chromium to be complexed to its non-available form in simulated lung fluids. Such measurements provide an indirect measure of the potential risk for adverse health effects, when performed at relevant experimental conditions. A more direct way to assess risks is to conduct toxicological in-vitro testing of metal particles, for instance on lung cell cultures relevant for human inhalation. Induced toxicity of metal particles on lung cells includes both the effect of the particles themselves and of the released metal fraction (including bioaccessible and bioavailable metals), the latter shown to be less predominant. The toxic response was clearly influenced by various experimental conditions such as sonication treatment of particles and the presence of serum proteins. Thorough characterization of metal particles assessing parameters including chemical surface composition, degree of agglomeration in solution, size distribution, surface area and morphology was performed and discussed in relation to generated results of bioaccessibility, bioavailability and induced toxicity. One important conclusion was that neither the surface composition nor the bulk composition can be used to assess the extent of metals released from chromium-based alloy particles. These findings emphasize that information on physical-chemical properties and surface characteristics of particles is essential for an in-depth understanding of metal release processes and for further use and interpretation of bioaccessibility data to assess hazard and reduce any risks induced by human exposure to metal particles.
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| 31. |
- Mu, Huiling, et al.
(author)
-
Fate of Chlorinated Fatty Acids in Migrating Sockeye Salmon and Their Transfer to Arctic Grayling
- 2004
-
In: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 38:21, s. 5548-5554
-
Journal article (peer-reviewed)abstract
- To investigate whether biotransport constitutes an entry route into pristine ecosystems for nonpersistent, nonvolatile xenobiotic compounds, extractable organically bound halogen in sockeye salmon (Oncorhynchus nerka) from Alaska was determined before and after spawning migration. The major organohalogen compounds in the salmon were halogenated fatty acids, predominantly chlorinated species that accounted for up to 35% of the extractable, organically bound chlorine (EOCl) in the fish tissues. The amount of chlorinated fatty acids in the salmon muscle decreased as a result of spawning migration. The decrease was correlated with that of triacylglycerols in the salmon muscle, indicating the chlorinated fatty acids to be mobilized and metabolized to approximately the same extent as the other fatty acids. Chlorinated fatty acids were also transferred to the maturing roe in a manner similar to that of the unchlorinated fatty acids. Lipids of the Arctic grayling (Thymallus arcticus), a fish resident to the spawning lake of the salmon, contained higher concentrations of chlorinated fatty acids than grayling in a lake without migratory salmon. This may reflect a food-chain transfer of the chlorinated fatty acids originating from the salmon, demonstrating a long-range transport route for this type of pollutants to pristine areas.
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| 32. |
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| 33. |
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| 34. |
- Pettersson Dahlin, Andreas, et al.
(author)
-
Capillary electrophoresis coupled to mass spectrometry from a polymer modified poly(dimethylsiloxane) microchip with an integrated graphite electrospray tip
- 2005
-
In: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 130:2, s. 193-199
-
Journal article (peer-reviewed)abstract
- Hybrid capillary-poly(dimethysiloxane) (PDMS) microchips with integrated electrospray ionization (ESI) tips were directly fabricated by casting PDMS in a mould. The shapes of the emitter tips were drilled into the mould, which produced highly reproducible three-dimensional tips. Due to the fabrication method of the microfluidic devices, no sealing was necessary and it was possible to produce a perfect channel modified by PolyE-323, an aliphatic polyamine coating agent. A variety of different coating procedures were also evaluated for the outside of the emitter tip. Dusting graphite on a thin unpolymerised PDMS layer followed by polymerisation was proven to be the most suitable procedure. The emitter tips showed excellent electrochemical properties and durabilities. The coating of the emitter was eventually passivated, but not lost, and could be regenerated by electrochemical means. The excellent electrochemical stability was further confirmed in long term electrospray experiments, in which the emitter sprayed continuously for more than 180 h. The PolyE-323 was found suitable for systems that integrate rigid fused silica and soft PDMS technology, since it simply could be applied successfully to both materials. The spray stability was confirmed from the recording of a total ion chromatogram in which the electrospray current exhibited a relative standard deviation of 3.9% for a 30 min run. CE-ESI-MS separations of peptides were carried out within 2 min using the hybrid PDMS chip resulting in similar efficiencies as for fused silica capillaries of the same length and thus with no measurable band broadening effects, originating from the PDMS emitter.
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| 35. |
- Redestig, Henning, et al.
(author)
-
Compensation for systematic cross-contribution improves normalization of mass spectrometry based metabolomics data
- 2009
-
In: Analytical Chemistry. - Washington : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 81:19, s. 7974-7980
-
Journal article (peer-reviewed)abstract
- Most mass spectrometry based metabolomics studies are semiquantitative and depend on efficient normalization techniques to suppress systematic error. A common approach is to include isotope-labeled internal standards (ISs) and then express the estimated metabolite abundances relative to the IS. Because of problems such as insufficient chromatographic resolution, however, the analytes may directly influence estimates of the IS, a phenomenon known as cross-contribution (CC). Normalization using ISs that suffer from CC effects will cause significant loss of information if the interfering analytes are associated with the studied factors. We present a novel normalization algorithm, which compensates for systematic CC effects that can be traced back to a linear association with the experimental design. The proposed method was found to be superior at purifying the signal of interest compared to current normalization methods when applied to two biological data sets and a multicomponent dilution mixture. Our method is applicable to data from randomized and designed experiments that use ISs to monitor the systematic error.
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| 36. |
- Reitzel, Kasper, et al.
(author)
-
Effects of aluminum treatment on phosphorus, carbon, and nitrogen distribution in lake sediment : A P-31 NMR study
- 2006
-
In: Water Research. - Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Uppsala Univ, Dept Analyt Chem, S-75124 Uppsala, Sweden. Uppsala Univ, Dept Organ Chem, S-75124 Uppsala, Sweden. Uppsala Univ, EBC, Dept Ecol & Evolut, S-75236 Uppsala, Sweden. : Elsevier BV. - 0043-1354 .- 1879-2448. ; 40:4, s. 647-654
-
Journal article (peer-reviewed)abstract
- The effects of aluminum (Al) treatment on sediment composition of carbon (C), nitrogen (N) and phosphorus (P) were investigated in sediment representing pre- and post-treatment years in the Danish Lake Sonderby. P-31 NMR spectroscopy analysis of EDTA-NaOH extracts revealed six functional P groups. Direct effects of the Al treatment were reflected in the orthophosphate profile revealing increased amounts of AI-P in the sediment layers representing the post-treatment period, as well as changes in organic P groups due to precipitation of phytoplankton and bacteria at the time of Al addition. Furthermore, changes in phytoplankton community structure and lowered production due to the Al treatment resulted in decreased concentrations of sediment organic P groups and total C. Exponential regressions were used to describe the diagenesis of C, N, and P in the sediment. From these regressions, half-life degradation times and C, N, and P burial rates were determined. (c) 2006 Elsevier Ltd. All rights reserved.
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| 37. |
- Stewart, Tom A., et al.
(author)
-
Enhanced Water Purification : A Single Atom Makes a Difference
- 2009
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:14, s. 5416-5422
-
Journal article (peer-reviewed)abstract
- The aluminum Keggin polycation (Al(13)) has been identified as an effective specie for neutralization and coagulation of anionic contaminants in water. In this study, we compare efficacy of the aluminum Keggin-ion to the analogues containing a single Ga-atom or single Ge-atom (GaAl(12) and GeAl(12), respectively) substituted into the center of the polycation in water-treatment studies. We investigated removal of bacteriophage (model viruses), Cryptosporidium, dissolved organic carbon (DOC), and turbidity. In every study, the order of contaminant removal efficacy trends GaAl(12) > Al(13) > GeAl(12). By ESI MS (electrospray ionization mass spectrometry), we noted the GaAl(12) deprotonates least of the three aluminum polycations, and thus probably carries the highest charge, and also optimal contaminant-neutralization ability. The ESI MS studies of the aluminum polycation solutions, as well as solid-state characterization of their resulting precipitates both reveal some conversion of Al(13) to larger polycations, Al(30) for instance. The GaAl(12) does not show any evidence for this alteration that is responsible for poor shelf life of commercial prehydrolyzed aluminum coagulants such as polyaluminum chloride. Based on these studies, we conclude that substitution of a single Ga-atom in the center of the aluminum Keggin polycation produces an optimal water-treatment product due to enhanced shelf life and efficacy in neutralization of anionic contaminants.
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| 38. |
- Söderman, Olle, et al.
(author)
-
NMR in colloid science with special emphasis on self-aggregating systems
- 2002
-
In: Magnetic Resonance in Colloids and Interface Science. Proceedings of the NATO Advanced Research Workshop. - 1402007876 ; , s. 123-138
-
Conference paper (peer-reviewed)abstract
- The purpose of this paper has been to show how NMR diffusometry can be used to convey information about structure and dynamics of complex fluids. The information can be obtained without the need to invoke complicated models. In fact, simple reasoning pertaining to how a molecule may diffuse through the studied systems allows one to chose between different conceivable solution structures and to obtain non-trivial information about solution structure
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| 39. |
- Viberg, Peter, et al.
(author)
-
Continuous full filling capillary electrochromatography: Chromatographic performance and reproducibility
- 2007
-
In: Journal of Chromatography A. - : Elsevier BV. - 0021-9673. ; 1154:1-2, s. 386-389
-
Journal article (peer-reviewed)abstract
- Continuous full filling capillary electrochromatography with nanoparticles as pseudostationary phase interfaced with electrospray ionisation mass spectrometric detection was used for reversed phase separations with very high separation efficiency. Several batches of nanoparticles were synthesised and their electrochromatographic performance were evaluated. Different parameters, such as repeatability, reproducibility, limit of detection, and peak asymmetry, were investigated yielding excellent results. The stability of the system over wide pH ranges and over time was found to be excellent. Very high separation efficiencies with over 1.1 million theoretical plates per metre were obtained. The limit of detection for the investigated dialkyl phthalates was approximately 1.0 mu mol L-1, corresponding to 3-5 fmol injected. After preparation, nanoparticle suspensions could be used without further treatment for at least an entire working day with maintained chromatographic qualities. (c) 2007 Elsevier B.V. All rights reserved.
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| 40. |
- Wang, Shijun, et al.
(author)
-
Electrochemical and Electrogenerated Chemiluminescent Studies of a Trinuclear Complex, [((phen)2Ru(dpp))2RhCl2]5+, and Its Interactions with Calf Thymus DNA
- 2009
-
In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 81:10, s. 4068-4075
-
Journal article (peer-reviewed)abstract
- The electrochemical behavior of a trinuclear ruthenium(II)-containing complex, [((phen)2Ru(dpp))2RhCl2]5+ (where phen = 1,10-phenanthroline, dpp = 2,3-bis(2-pyridyl)pyrazine), was studied in acetonitrile (MeCN) and aqueous solutions. In MeCN containing 0.10 M tetra-n-butylammonium perchlorate (TBAP), the complex displayed a reversible, overlapping RuII/III redox process with E1/2 = +1.21 V vs Ag/Ag+ (10 mM), an irreversible reduction of RhIII/I at −0.73 V vs Ag/Ag+, and two quasi-reversible dpp/dpp− couples with E1/2 = −1.11 and −1.36 V vs Ag/Ag+ at a Pt electrode with a scan rate of 50 mV s−1. In 0.20 M Tris buffer solution (pH 7.4), an irreversible, overlapping RuII/III oxidation at +1.48 V vs Ag/AgCl (3 M KCl), and an irreversible reduction of RhIII/II at −0.78 V vs Ag/AgCl were observed at a glassy carbon electrode with a scan rate of 50 mV/s. Investigations on the electrogenerated chemiluminescence (ECL) of the complex revealed that 2-(dibutylamino) ethanol (DBAE) was superior to tri-n-propylamine (TPrA) as an ECL coreactant within their entire concentration range of 10−100 mM in MeCN, and in aqueous media, as low as 1.0 nM of the complex can be detected using TPrA coreactant ECL. A maximum ECL emission of 640 nm, which is about 55 nm blue shift to its fluorescence, was observed in MeCN with DBAE as a coreactant. Interactions of the complex with calf thymus DNA (ctDNA) were conducted with a flow-cell based quartz-crystal microbalance, and a binding constant of 2.5 × 105 M−1 was calculated on the basis of the Langmuir isotherm equation.
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| 41. |
- Wilhelmsson, Marcus, 1974, et al.
(author)
-
Genetic screening using the colour change of a PNA-DNA hybrid-binding cyanine dye
- 2002
-
In: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 30:2
-
Journal article (peer-reviewed)abstract
- As the relationship between human genes and various malfunctions and diseases becomes revealed at an ever-increasing pace, the need arises for the development of rapid genetic screening methods for diagnostic purposes. Genetic diseases show great diversity. Some are caused by a few characteristic localised mutations, while others arise from a large number of variations. Hence, It. is unlikely that. a single, general diagnostic method that applies to all cases will ever exist. Instead, a combination of methods is frequently applied. Here we propose the use of a dramatic colour change that a cyanine ye, 3,3'-diethylthiadicarbocyanine, displays upon binding to DNA-PNA duplexes. This method could become an inexpensive, fast and simple genetic screening test by visual inspection, with no need for complicated equipment. Our results demonstrate that this diagnostic method may be sufficiently sensitive to discriminate between even a fully complementary and a single mutation DNA sequence.
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| 42. |
- Zettersten, Camilla, 1978-, et al.
(author)
-
Identification and Characterization of Polyphenolic Antioxidants Using On-Line Liquid Chromatography, Electrochemistry, and Electrospray Ionization Tandem Mass Spectrometry
- 2009
-
In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 81:21, s. 8968-8977
-
Journal article (peer-reviewed)abstract
- It is demonstrated that electrochemistry (EC) coupled to liquid chromatography (LC) and electrospray ionization tandem mass spectrometry (LC/EC/ESI-MS/MS) can be used to rapidly obtain information about the antioxidant activity (i.e., oxidation potential) and capacity (i.e., amount) of polyphenolic compounds, including catechin, kaempferol, resveratrol, quercetin, and quercetin glucosides. The described on-line LC/EC/ESI-MS/MS method facilitates the detection and characterization of individual antioxidants based on a combination of the obtained m/z values for the antioxidants and their oxidation products, the potential dependences for the ion intensities, and correlations between the retention times in the LC, EC, and MS chromatograms. As these results provide patterns that can be used in rapid screening for antioxidants in complex samples, the method should be a valuable complement to chemical assays commonly used to determine the total antioxidant capacity of samples. It is shown that the antioxidant capacity for a mixture of polyphenolic compounds depends on the redox potential employed in the evaluation, and this should consequently be taken into account when comparing results from different total antioxidant capacity assays. It is also demonstrated that the inherent antioxidant capacities of phenolic compounds increase with an increasing number of hydroxyl groups and that the potential needed to oxidize the remaining hydroxyl groups increases successively upon oxidation of the compound. Unlike chemical assays, which generally do not provide any information about the identities of the compounds on the molecular level, the present screening method can be used to identify individual antioxidants, rank compounds with respect to their ease of oxidation, and to study the antioxidant capacity at any redox potential of interest.
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| 43. |
- Ahlgren, Joakim, et al.
(author)
-
Sediment Phosphorus Extractants for Phosphorus-31 Nuclear Magnetic Resonance Analysis : A Quantitative Evaluation
- 2007
-
In: Journal of Environmental Quality. - Uppsala Univ, Dept Phys & Analyt Chem, S-75124 Uppsala, Sweden. Univ So Denmark, Inst Biol, DK-5230 Odense M, Denmark. Uppsala Univ, Dept Biochem & Organ Chem, S-75124 Uppsala, Sweden. Uppsala Univ, Dept Ecol & Evolut, S-75123 Uppsala, Sweden. : Wiley. - 0047-2425 .- 1537-2537. ; 36:3, s. 892-898
-
Journal article (peer-reviewed)abstract
- The influence of pre-extractant, extractant, and post-extractant on total extracted amounts of P and organic P compound groups measured with 31P nuclear magnetic resonance (31P-NMR) in lacustrine sediment was examined. The main extractants investigated were sodium hydroxide (NaOH) and sodium hydroxide ethylenediaminetetraacetic acid (NaOH-EDTA) with bicarbonate buffered dithionite (BD) or EDTA as pre-extractants. Post extractions were conducted using either NaOH or NaOH-EDTA, depending on the main extractant. Results showed that the most efficient combination of extractants for total P yield was NaOH with EDTA as pre-extractant, yielding almost 50% more than the second best procedure. The P compound groups varying the most between the different extraction procedures were polyphosphates and pyrophosphates. NaOH with BD as pre-extractant was the most efficient combination for these compound groups.
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| 44. |
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| 45. |
- Altun, Zeki, 1978-
(author)
-
New Techniques for Sample Preparation in Analytical Chemistry : Microextraction in Packed Syringe (MEPS) and Methacrylate Based Monolithic Pipette Tips
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- Sample preparation is often a bottleneck in systems for chemical analysis. The aim of this work was to investigate and develop new techniques to address some of the shortcomings of current sample preparation methods. The goal has been to provide full automation, on-line coupling to detection systems, short sample preparation times and high-throughput. In this work a new technique for sample preparation that can be connected on-line to liquid chromatography (LC) and gas chromatography (GC) has been developed. Microextraction in packed syringe (MEPS) is a new solid-phase extraction (SPE) technique that is miniaturized and can be fully automated. In MEPS approximately 1 mg of sorbent material is inserted into a gas tight syringe (100-250 μL) as a plug. Sample preparation takes place on the packed bed. Evaluation of the technique was done by the determination of local anaesthetics in human plasma samples using MEPS on-line with LC and tandem mass spectrometry (MS-MS). MEPS connected to an autosampler was fully automated and clean-up of the samples took about one minute. In addition, in the case of plasma samples the same plug of sorbent could be used for about 100 extractions before it was discarded. A further aim of this work was to increase sample preparation throughput. To do that disposable pipette tips were packed with a plug of porous polymer monoliths as sample adsorbent and were then used in connection with 96-well plates and LC-MS-MS. The evaluation of the methods was done by the analysis of local anaesthetics lidocaine and ropivacaine, and anti-cancer drug roscovitine in plasma samples. When roscovitine and lidocaine in human plasma and water samples were used as model substances, a 96-plate was handled in about two minutes. Further, disposable pipette tips may be produced at low cost and because they are used only once, carry-over is eliminated.
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| 46. |
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| 47. |
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| 48. |
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| 49. |
- Carlsson, Jenny, 1977-, et al.
(author)
-
Biosensor discrimination of meat juice from various animals using a lectin panel and ellipsometry
- 2005
-
In: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 547:2, s. 229-236
-
Journal article (peer-reviewed)abstract
- In this work, simple microcontact printed gold-wafers were used to make a lectin panel for investigation and discrimination of different meat juices from fresh meat of cattle, chicken, pig, cod, turkey and lamb. Seven different lectins were thus attached to gold surfaces using the streptavidin–biotin method. Lectins recognize and bind specifically to carbohydrate structures present on different proteins. The biorecognition was evaluated with null ellipsometry and the data obtained was related to an internal standard of lactoferrin. The data was evaluated with multivariate data analysis techniques to identify possible discrimination or grouping of data. Scanning ellipsometry was used for visualization of the binding pattern of the lectins and the meat juice proteins. The two-dimensional images obtained could be used to visualize the protein distribution, furthermore, to exclude anomalies. The results showed that the different meat juices from the six different species: cattle, chicken, pig, cod, turkey and lamb could be discriminated from each other. The results showed to be more repetitive for the mammalian meat juices. Using a simple model based on an artificial neuronal net, it was also possible to classify meat juices from the mammals investigated.
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| 50. |
- Carlsson, Jenny, 1977-, et al.
(author)
-
Investigation of sera from various species by using lectin affinity arrays and scanning ellipsometry
- 2005
-
In: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 530:2, s. 167-171
-
Journal article (peer-reviewed)abstract
- Serum proteins of different species and of different human blood groups exhibit various protein glycosylation patterns. Sera from human, pig, sheep and guinea pig have been applied to a panel of eight different lectins immobilized on a gold wafer. The biorecognition has been evaluated with scanning ellipsometry and the two-dimensional matrices obtained have been treated with image analysis and MVDA for evaluation. The results showed a clear difference in protein binding pattern between the different species and thereby separation of the different sera could be made. Dendograms indicate that human and pig sera are the most related of the four different sera investigated.
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