| 1. |
- Allentoft, Morten E., et al.
(författare)
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Population genomics of post-glacial western Eurasia
- 2024
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 625:7994, s. 301-311
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Tidskriftsartikel (refereegranskat)abstract
- Western Eurasia witnessed several large-scale human migrations during the Holocene1–5. Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes—mainly from the Mesolithic and Neolithic periods—from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a ‘great divide’ genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 bp, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 bp, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a ‘Neolithic steppe’ cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations.
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| 2. |
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| 3. |
- Concina, B., et al.
(författare)
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Delayed ionisation of C-76
- 2006
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Ingår i: INTERNATIONAL JOURNAL OF MASS SPECTROMETRY. - : Elsevier BV. - 1387-3806. ; 252:2, s. 96-99
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Dittmer, Staffan, 1970, et al.
(författare)
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In situ Raman studies of single-walled carbon nanotubes grown by local
- 2008
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 457
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Tidskriftsartikel (refereegranskat)abstract
- Using in situ Raman spectroscopy we investigate single wall carbon nanotube growth on Mo electrodes, using a highly localized resistive heating technique. Small diameter semiconducting single wall nanotubes grow very rapidly when the catalyst support is heated to a temperature of 800 C. The G/D ratio shows an interesting time-dependent behaviour. It first decreases, indicating the presence of amorphous carbon and then significantly increases again after ca. 5 min growth while retaining the position and shape expected for predominantly semiconducting carbon nanotubes.
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| 5. |
- Gromov, Andrei, 1959, et al.
(författare)
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Covalent Amino functionalisation of single walled carbon nanotubes
- 2005
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Ingår i: J. Materials Chem. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 15, s. 3334-3339
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Tidskriftsartikel (refereegranskat)abstract
- Chemical transformation of single-wall carbon nanotubes (SWNT), edge-terminated with carboxylic groups, to SWNT species with amino groups directly attached to the tube open ends has been performed. Different synthetic approaches have been investigated. The reaction products were characterised by FTIR, Raman spectroscopy, XPS and SEM.
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| 6. |
- Gromov, Sergey P, et al.
(författare)
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Synthesis, Structure, Spectroscopic Studies, and Complexation of Novel Crown Ether Butadienyl Dyes
- 2002
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Ingår i: Helvetica Chimica Acta. ; 85:1, s. 60-81
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Tidskriftsartikel (refereegranskat)abstract
- Butadienyl dyes of the benzothiazole series with various fragments of benzocrown ethers 1a-c were synthesized for the first time. The structures and spectral properties of crown-containing butadienyl dyes and their complexes with alkali and alkaline-earth metal cations were studied by X-ray diffraction analysis and 1H-NMR, UV/VIS, and resonance Raman spectroscopy. To interpret the experimental results, quantum-chemical calculations were performed. In the case of Sr2+ and Ba2+ ions, the formation of strong sandwich complexes [M(1b)2]2+ of an unusual structure involving stacking interactions was established; the dye molecules are arranged one above another in the complex according to the head-to-head' pattern.
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| 7. |
- Hedén, Martin, 1976, et al.
(författare)
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Thermal radiation from CN+ and La@CN
- 2005
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Ingår i: J. Chem. Phys.. - : AIP Publishing. - 0021-9606. ; 123
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Tidskriftsartikel (refereegranskat)abstract
- The radiative cooling of positively charged fullerene and endohedral fullerene fragments of C60, C70, C84, and La@C82 has been measured in a time-of-flight mass spectrometer. The radiative cooling is measured via its influence on the metastable decay. The emissivity extracted from the data is between 4×10–4 and 13×10–4. These values agree fairly well with the emissivity calculated from considering the low-energy tail of the surface plasmon. No major difference is found in the emission behavior of empty and endohedral fullerenes.
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| 8. |
- Lassesson, Andreas, 1976, et al.
(författare)
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A femtosecond laser study of the endoral fullerenes Li@C60 and La@C82
- 2005
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Ingår i: Eur. Phys. J. D. - : Springer Science and Business Media LLC. - 1434-6060. ; 34, s. 205-209
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Tidskriftsartikel (refereegranskat)abstract
- The endohedral fullerenes La@C82 and Li@C60 have been studied in the gas phase with femtosecond laser excitation. The two molecules show qualitatively the same behaviour with respect to ion yield vs. pulse energy, but markedly different fragmentation patterns, with La@C82 fragmenting via the shrink-wrap mechanism and Li@C60 predominantly losing the metal atom in the first fragmentation step. The ion yields and electron energy distributions of La@C82 agree well with a recently developed model for fs laser ionisation of C60.
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| 9. |
- Lassesson, Andreas, 1976, et al.
(författare)
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Formation of small lanthanum-carbide ions from laser induced fragmentation of La@C-82
- 2003
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 119:11, s. 5591-5600
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Tidskriftsartikel (refereegranskat)abstract
- The fragmentation behavior of the endohedral metallofullerene La@C-82 was studied using gas phase time-of-flight mass spectrometry. The results were compared with the fragmentation of C-60. When the metallofullerene was excited by a 337 nm ns laser, small lanthanum-carbide fragments LaCn+, n=0-6, were detected. A simple statistical maximum entropy model was used to simulate the excitation energy dependence of the loss of the LaCn+ molecules as well as C-2 evaporation to form smaller metallofullerenes. By comparing experimental ion intensities with the model, the appearance energies of LaCn+, n=0-6, were found to lie above 65 eV. The lanthanum-carbide fragments ejected from La@C-82 decrease in size with increasing internal energy. The ejection of La+ and LaC2+ is preferred at the expense of larger fragments such as LaC4+ and metallofullerenes at the higher excitation. (C) 2003 American Institute of Physics.
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| 10. |
- Lassesson, Andreas, 1976, et al.
(författare)
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Investigations into the fragmentation and ionization of highly excited La@C-82
- 2002
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 1089-7690 .- 0021-9606. ; 117:21, s. 9811-9817
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Tidskriftsartikel (refereegranskat)abstract
- We report the first measurements of delayed ionization of the metallofullerene La@C-82. When highly excited in laser desorption, La@C-82 was found to ionize over several microseconds. The rate of delayed ionization of La@C-82 was compared to C-60 under the same extraction conditions, and found to be significantly different. A theoretical model was used for the fitting of the ion signal of the two fullerenes. The metallofullerene results can be fitted well over a time window
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