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S. Leskinen J. K. Miettinen T. Jaakkola 《Journal of Radioanalytical and Nuclear Chemistry》1987,115(2):289-298
Concentrations of239,240Pu and241Am in filtered seawater, particulate fraction and sediment were measured. Methods for determination of these nuclides were critically chequed and a new rapid method for241Am in sediment was developed. Due to seasonal variation a significant decrease of plutonium and americium concentrations in surface water takes place in summer. Americium is more efficiently associated with particulate matter than plutonium. From May 1980 to September 1984 soluble plutonium in the water was reduced to about half. The residence half-time of239,240Pu in the water of Baltic Sea is of the order of 5 years. About similar concentrations of239,240Pu and241Am were found in particulates in water as in the surface layer of the sediment. The average Kd-values for plutonium and americium were 105 and 105–106 ml/g, respectively. 相似文献
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We address an imbalanced two-component atomic Fermi gas restricted by a one-dimensional (1D) optical lattice and an external harmonic potential, within the mean-field Bogoliubov-de Gennes formalism. We show that characteristic features of the Fulde-Ferrell-Larkin-Ovchinnikov state are visible in the rf spectra and in the momentum-resolved photoemission spectra of the gas. Specially, Andreev states or midgap states can be clearly resolved, which gives a direct experimentally observable signature of the oscillating order parameter. 相似文献
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Dr. Ashley J. Holding Jingwen Xia Prof. Dr. Michael Hummel Harry Zwiers Matti Leskinen Dr. Daniel Rico del Cerro Dr. Sami Hietala Dr. Martin Nieger Dr. Marianna Kemell Jussi K. J. Helminen Dr. Vladimir Aseyev Prof. Dr. Heikki Tenhu Prof. Dr. Ilkka Kilpeläinen Dr. Alistair W. T. King 《Chemphyschem》2022,23(7):e202100635
We have identified cellulose solvents, comprised of binary mixtures of molecular solvents and ionic liquids that rapidly dissolve cellulose to high concentration and show upper-critical solution temperature (UCST)-like thermodynamic behaviour - upon cooling and micro phase-separation to roughly spherical microparticle particle-gel mixtures. This is a result of an entropy-dominant process, controllable by changing temperature, with an overall exothermic regeneration step. However, the initial dissolution of cellulose in this system, from the majority cellulose I allomorph upon increasing temperature, is also exothermic. The mixtures essentially act as ‘thermo-switchable’ gels. Upon initial dissolution and cooling, micro-scaled spherical particles are formed, the formation onset and size of which are dependent on the presence of traces of water. Wide-angle X-ray scattering (WAXS) and 13C cross-polarisation magic-angle spinning (CP-MAS) NMR spectroscopy have identified that the cellulose micro phase-separates with no remaining cellulose I allomorph and eventually forms a proportion of the cellulose II allomorph after water washing and drying. The rheological properties of these solutions demonstrate the possibility of a new type of cellulose processing, whereby morphology can be influenced by changing temperature. 相似文献
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Quantification of triacylglycerol regioisomers in oils and fat using different mass spectrometric and liquid chromatographic methods 总被引:2,自引:0,他引:2
Leskinen H Suomela JP Kallio H 《Rapid communications in mass spectrometry : RCM》2007,21(14):2361-2373
The regioisomers (sn-ABA/sn-AAB) of four triacylglycerols (TAGs), 18:2/18:2/18:1 (LLO), 18:2/18:1/18:1 (LOO), 16:0/18:1/18:1 (POO), and 16:0/16:0/18:1 (PPO), were quantified in lard, rapeseed oil, and sunflower seed oil by three different mass spectrometric methods using liquid chromatography (LC) and two different mass spectrometers. The ionization methods used were positive ion atmospheric pressure chemical ionization (APCI), positive ion electrospray ionization (ESI), and negative ion chemical ionization (NICI) with ammonia as the reagent gas. The LC/APCI-MS results with two different instrumentation types, LC/ESI-MS/MS and direct inlet ammonia NICI-MS/MS, were compared. The LC/APCI-MS method is based on the preferential formation of diacylglycerol (DAG) fragment ions during ionization by loss of sn-1/3 fatty acids from [M+H]+ ions. Similar formation of the DAG ions from [M+NH4]+ ions by collision-induced dissociation (CID) in the LC/ESI-MS/MS method and the [M-H--RCOOH-100]- ions from [M-H]- ions by CID in the direct inlet ammonia NICI-MS/MS method is observed. These methods were found to be useful and reliable in determining the regioisomeric structure of TAGs. No statistically significant differences were found between the results obtained with these methods. For LLO, LOO, and POO the proportions of sn-ABA isomer calculated from the results from all four methods were in rapeseed oil 7.7 +/- 6.5, 57.9 +/- 3.3, and 4.5 +/- 6.1%, respectively, and in sunflower seed oil 12.2 +/- 6.9, 34.0 +/- 5.2, and 1.4 +/- 2.8%, respectively. The proportions of ABA of POO and PPO in lard were 95.3 +/- 3.2 and 4.9 +/- 5.6%, respectively. This study also proved that the LC/APCI-MS/MS method examined is not applicable in the quantification of TAG regioisomers because the formation of DAG ions is not clearly dependent on the positional distribution of the fatty acids. 相似文献
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Leskinen Anumaija Gautier Celine Räty Antti Kekki Tommi Laporte Elodie Giuliani Margaux Bubendorff Jacques Laurila Julia Kurhela Kristian Fichet Pascal Salminen-Paatero Susanna 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(2):945-958
Journal of Radioanalytical and Nuclear Chemistry - This paper reports the results obtained in a Nordic Nuclear Safety Research project during the second intercomparison exercise for the... 相似文献
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Leskinen MV Yip KT Valkonen A Pihko PM 《Journal of the American Chemical Society》2012,134(13):5750-5753
The dehydrogenative β'-functionalization of α-substituted β-keto esters with indoles proceeds with high regioselectivities (C3-selective for the indole partner and β'-selective for the β-keto ester) and good yields under mild palladium catalysis at room temperature with a variety of oxidants. Two possible mechanisms involving either late or early involvement of indole are presented. 相似文献
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Leskinen Anumaija Salminen-Paatero Susanna Gautier Celine Räty Antti Tanhua-Tyrkkö Merja Fichet Pascal Kekki Tommi Zhang Wenzhong Bubendorff Jacques Laporte Elodie Lambrot Gabriel Brennetot René 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):1303-1316
Journal of Radioanalytical and Nuclear Chemistry - This paper reports the results obtained during an intercomparison exercise for the determination of difficult to measure radionuclides in... 相似文献
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Pascal Fichet Fannie Bresson Anumaija Leskinen Florence Goutelard Jussi Ikonen Marja Siitari-Kauppi 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(3):869-875
The aim of our study was to develop a sensitive analytical technique to investigate tritium traces on concrete floor, ceiling
and walls of a laboratory under dismantling process. In dismantling process, the behaviour of tritium must be followed very
closely and in particular releases to atmosphere and exposure to public must be prevented. The investigations were carried
out using liquid scintillation counting (LSC) and digital autoradiography techniques. The LSC investigations were carried
out using wipe tests. It was concluded that even though LSC technique provided accurate information on the level of contamination,
the loss of exact localisation of contamination spots was considered to be a major disadvantage in this application. The digital
autoradiography was shown to provide both quantitative information and localisation of contamination spots. The exposure time
on the digital autoradiography films were optimized, the matrix effect and the selectivity of the films were studied using
polymethylmethacrylate standards. The studies showed that the digital autoradiography technique can give quantitative results,
especially if standards of the investigated material (concrete) are used. 相似文献