| 1. |
- Grinko, A. A., et al.
(författare)
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Sediment Organic Matter in Areas of Intense Methane Release in the Laptev Sea : Characteristics of Molecular Composition
- 2020
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Ingår i: Russian Geology and Geophysics. - 1068-7971 .- 1878-030X. ; 61:4, s. 456-477
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Tidskriftsartikel (refereegranskat)abstract
- We present results of study of the molecular composition of organic matter (OM) in the bottom sediments of the Laptev Sea by gas chromatography-mass spectrometry, isotope gas chromatography-mass spectrometry, and Rock-Eval pyrolytic analysis. The OM of all collected sediment samples shows a significant terrigenous contribution. Compounds that are biomarkers of methanotrophic microorganisms arc also found. A positive correlation between the contents of the studied biomarkers and the contents of pelite and total organic carbon is observed at the sites with documented intense methane bubbling. For example, the average content of C30 hopenes at the methane stations is twice higher than that at the background ones. The average content of C32 alpha beta-hopanes in sediment samples from the methane seepage area is 1.5 tunes higher than that at the background stations. We suggest that the increased C30 alpha beta-hopane content (similar to 1.5 times higher within the methane seepage area) and the decreased more index relative to the C31 hopane index are due to the inflow of OM of petroleum origin. The presence of biphenyl in sediments indicates its petroleum origin, which supports our assumption of the migratory nature of petroleum hydrocarbons in the methane seepage area. Triterpenoids found in the sediment OM indicate diagenetic bacterial transformation of OM in the methane seepage areas, which shows that methane has been released for a long time. We assume the intense activity of the consortium of methanotrophs and sulfate reducers in the methane seepage areas.
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| 2. |
- Alekseev, A. Yu, et al.
(författare)
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Curvature-induced effects in semiconducting alkaline-earth metal silicide nanotubes
- 2021
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Ingår i: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 128
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Tidskriftsartikel (refereegranskat)abstract
- By means of ab-initio techniques we have investigated changes in the structure and electronic properties of alkaline-earth metal silicide (Ca2Si, Mg2Si and MgCaSi) nanotubes caused by the curvature-induced effects. It is revealed that the curvature-induced effects can: 1) stabilize Mg2Si nanotubes in a phase, which is metastable for the parent 2D Mg2Si; 2) lead to an energy gain as a result of 2D to nanotube structural transformation in the case of ternary MgCaSi nanotubes; 3) modify the band dispersion and band gaps for nanotubes with the diameters less than 30 angstrom. In addition, Mg2Si and MgCaSi nanotubes are found to be direct band-gap (0.5-1.2 eV) materials with appreciable oscillator strength of the first direct transitions.
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| 3. |
- Alekseev, A. Yu, et al.
(författare)
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Stability of 2D Alkaline-Earth Metal Silicides, Germanides and Stannides
- 2019
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Ingår i: International Journal of Nanoscience. - : World Scientific Publishing Co. Pte Ltd. - 0219-581X. ; 18:3-4
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Tidskriftsartikel (refereegranskat)abstract
- By means of ab initio calculations, we have estimated stability of 2D Me2X (Me = Mg, Ca, Sr, Ba and X = Si, Ge, Sn) in the T and Td phases, which are similar to the ones of 2D transition metal chalcogenides, in addition to their phonon spectra. The T phase is found to be more stable for 2D Ca2X, Sr2X and Ba2X, whereas the Td phase is predicted to be the ground state for 2D Mg2X. We have also discussed that imaginary frequencies in the calculated phonon spectra of 2D Me2X, which appeared in the vicinity of the Gamma point, were not necessarily associated with the dynamic instability.
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| 4. |
- Chernykh, Denis, et al.
(författare)
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NEW ACOUSTICAL TECHNIQUE TO QUANTIFY METHANE EBULLITION IN SEDIMENT WATER COLUMN : A CASE STUDY IN THE LAPTEV SEA, THE ARCTIC OCEAN
- 2018
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Ingår i: Bulletin of the Tomsk Polytechnic University - Geo Assets Engineering. - : National Research Tomsk Polytechnic University. - 2500-1019. ; 329:11, s. 153-167
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Tidskriftsartikel (refereegranskat)abstract
- The relevance of the research is caused by the need to develop a scientifically based approach to quantitative estimation of bubble transfer of methane and other gases based on acoustic techniques, which allow reliable estimate of methane flow from the bubble unloading areas by sound locators and submarine sonars. The main aim of the research is to investigate the possible application of an acoustical technique based on acoustic scattering in bubble plumes vs the acoustical technique based on calibration which was applied to quantify in situ sonar observations; to show that both techniques can be used for a quantification of methane ebullition in the bottom-water column system. Objects: gas flares or seeps - the emanations of gas in the form of rising bubbles from the seabottom, which form stable regions of their increased concentration in the water column. Methods: modification of acoustical techniques based on acoustic scattering in bubble plumes and on ist calibration which was applied by authors to quantify in situ single sonar observations. Results. We demonstrate a first attempt to use acoustical techniques based on (1) acoustic scattering in bubble plumes vs acoustical technique based on (2) calibration which was applied to quantify in situ sonar observations. It has been shown that both techniques can be used for a quatitative express-evaluation of methane ebullition in the bottom-water system in any aquatic ecosystem including seas, lakes, and rivers, while the first acoustical technique gives the bubble efflux values -20 % lower then the second acoustical technique.
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| 5. |
- Göök, A., et al.
(författare)
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Fragment characteristics from fission of U-238 and U-234 induced by 6.5-9.0 MeV bremsstrahlung
- 2011
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 851:1, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- Fission of U-238 and U-234 induced by bremsstrahlung of 6.5-9.0 MeV endpoint energy has been investigated at the superconducting Darmstadt electron linear accelerator S-DALINAC. Using a twin Frisch grid ionization chamber, fission-fragment energy and mass distributions have been determined by means of the double kinetic-energy technique. Results on the fission-fragment characteristics from U-238(gamma, f) are in agreement with results from the literature. In addition fission-fragment mass and energy distributions from U-234(gamma, f) are presented for the first time in this energy region. An analysis of fission modes within the Brosa model has been performed. The relative yield of the S 1 mode was found to be (13 +/- 3)% in U-234 and (35 +/- 2)% in U-238.
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| 6. |
- Göök, A., et al.
(författare)
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Photo-fission at the S-DALINAC
- 2009
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Ingår i: 4th international workshop on nuclear fission and fission-product spectroscopy. - : American Institute of Physics (AIP). - 9780735407145 ; , s. 351-354
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Experiments on photo-induced fission of 238U and 234U using bremsstrahlung with endpoint energies between 6 MeV and 9 MeV have been carried out at the superconducting Darmstadt electron linear accelerator S-DALINAC. A twin Frisch grid ionization chamber has been used to determine energy and mass distributions via the 2E-technique. The fission fragment emission angle, which is used to correct for energy loss in the target and backing material for a correct determination of fragment energy and mass, is deduced from the time difference between cathode and anode signals. The research program including the foreseen search for parity violation in photo-induced fission and first experimental results will be presented. © 2009 American Institute of Physics.
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| 7. |
- Kawahara, R., et al.
(författare)
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Community evaluation of glycoproteomics informatics solutions reveals high-performance search strategies for serum glycopeptide analysis
- 2021
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Ingår i: Nature Methods. - : Springer Science and Business Media LLC. - 1548-7091 .- 1548-7105. ; 18, s. 1304-1316
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Tidskriftsartikel (refereegranskat)abstract
- Glycoproteomics is a powerful yet analytically challenging research tool. Software packages aiding the interpretation of complex glycopeptide tandem mass spectra have appeared, but their relative performance remains untested. Conducted through the HUPO Human Glycoproteomics Initiative, this community study, comprising both developers and users of glycoproteomics software, evaluates solutions for system-wide glycopeptide analysis. The same mass spectrometrybased glycoproteomics datasets from human serum were shared with participants and the relative team performance for N- and O-glycopeptide data analysis was comprehensively established by orthogonal performance tests. Although the results were variable, several high-performance glycoproteomics informatics strategies were identified. Deep analysis of the data revealed key performance-associated search parameters and led to recommendations for improved 'high-coverage' and 'high-accuracy' glycoproteomics search solutions. This study concludes that diverse software packages for comprehensive glycopeptide data analysis exist, points to several high-performance search strategies and specifies key variables that will guide future software developments and assist informatics decision-making in glycoproteomics. This analysis presents the results of a community-based evaluation of existing software for large-scale glycopeptide data analysis.
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| 8. |
- Göök, A., et al.
(författare)
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Particle emission angle determination in Frisch grid ionization chambers by electron drift-time measurements
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 621:1-3, s. 401-405
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Tidskriftsartikel (refereegranskat)abstract
- The double kinetic energy measurement of fission fragments with a double-sided Frisch grid ionization chamber allows a careful determination of the emission angle, which is essential in order to apply appropriate energy-loss corrections. We present a drift-time method, which uses the time that free electrons need to drift from the location of their creation, e.g. by a fission fragment in the counting gas, to the grid, before inducing a signal on the anode. Such a measurement leaves energy and angular information fully decoupled. We demonstrate the applicability of the drift-time method for the example of the 234,238U (γ,f) reactions performed at the superconducting Darmstadt electron linear accelerator. The angular resolutions achieved with this method are comparable to those obtained with other methods.
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| 9. |
- Huang, Hongyun, et al.
(författare)
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Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)
- 2018
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 27:2, s. 310-324
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Forskningsöversikt (refereegranskat)abstract
- Cell therapy has been shown to be a key clinical therapeutic option for central nervous system diseases or damage. Standardization of clinical cell therapy procedures is an important task for professional associations devoted to cell therapy. The Chinese Branch of the International Association of Neurorestoratology (IANR) completed the first set of guidelines governing the clinical application of neurorestoration in 2011. The IANR and the Chinese Association of Neurorestoratology (CANR) collaborated to propose the current version "Clinical Cell Therapy Guidelines for Neurorestoration (IANR/CANR 2017)". The IANR council board members and CANR committee members approved this proposal on September 1, 2016, and recommend it to clinical practitioners of cellular therapy. These guidelines include items of cell type nomenclature, cell quality control, minimal suggested cell doses, patient-informed consent, indications for undergoing cell therapy, contraindications for undergoing cell therapy, documentation of procedure and therapy, safety evaluation, efficacy evaluation, policy of repeated treatments, do not charge patients for unproven therapies, basic principles of cell therapy, and publishing responsibility.
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