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  • Frontiers Media SA  (4)
  • Berger, Daniel  (4)
Medientyp
Verlag/Herausgeber
  • Frontiers Media SA  (4)
Sprache
Erscheinungszeitraum
  • 1
    Online-Ressource
    Online-Ressource
    Frontiers Media SA ; 2022
    In:  Frontiers in Molecular Biosciences Vol. 9 ( 2022-7-18)
    In: Frontiers in Molecular Biosciences, Frontiers Media SA, Vol. 9 ( 2022-7-18)
    Kurzfassung: Covering a wide spectrum of molecules is essential for global metabolome assessment. While metabolomics assays are most frequently carried out in microbore LC-MS analysis, reducing the size of the analytical platform has proven its ability to boost sensitivity for specific - omics applications. In this study, we elaborate the impact of LC miniaturization on exploratory small-molecule LC-MS analysis, focusing on chromatographic properties with critical impact on peak picking and statistical analysis. We have assessed a panel of small molecules comprising endogenous metabolites and environmental contaminants covering three flow regimes—analytical, micro-, and nano-flow. Miniaturization to the micro-flow regime yields moderately increased sensitivity as compared to the nano setup, where median sensitivity gains around 80-fold are observed in protein-precipitated blood plasma extract. This gain resulting in higher coverage at low µg/L concentrations is compound dependent. At the same time, the nano-LC-high-resolution mass spectrometry (HRMS) approach reduces the investigated chemical space as a consequence of the trap-and-elute nano-LC platform. Finally, while all three setups show excellent retention time stabilities, rapid gradients jeopardize the peak area repeatability of the nano-LC setup. Micro-LC offers the best compromise between improving signal intensity and metabolome coverage, despite the fact that only incremental gains can be achieved. Hence, we recommend using micro-LC for wide-target small-molecule trace bioanalysis and global metabolomics of abundant samples.
    Materialart: Online-Ressource
    ISSN: 2296-889X
    Sprache: Unbekannt
    Verlag: Frontiers Media SA
    Publikationsdatum: 2022
    ZDB Id: 2814330-9
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    Frontiers Media SA ; 2023
    In:  Frontiers in Earth Science Vol. 11 ( 2023-8-3)
    In: Frontiers in Earth Science, Frontiers Media SA, Vol. 11 ( 2023-8-3)
    Kurzfassung: The Bronze Age in Central Asia was dominated by the Andronovo Culture and the Bactria-Margiana Archaeological Complex (BMAC). Both cultural entities produced bronze, however, the extent of bronze production and use varied considerably in space and time across their territories. The introduction and spread of bronze metallurgy in the region is commonly associated with the Andronovo Culture, but comparatively little is known about the copper and tin sources that were exploited to make the bronze. To shed light on this aspect, this paper examines 91 bronze artefacts from the Middle Bronze Age (MBA) and the Late Bronze Age (LBA) recovered from twenty sites of Andronovo and the BMAC through a combined evaluation of chemical and isotopic analyses. Trace element patterns and isotopic compositions of lead, tin, and copper are determined for the objects complemented by tin isotope analysis of Central Asian tin ores. The data shows a clear separation of two source areas in the MBA and LBA I: the BMAC obtained copper from polymetallic (tin-bearing) deposits in Iran (Deh Hosein, Nakhlak/Bagh Gorogh) and possibly Afghanistan, while the Andronovo Culture mainly used copper from the Tian Shan Mountains. With the transition to the LBA II, a change in the material basis can be recognised, in which the BMAC increasingly relied on metal deposits from the Andronovo territory. The most important result in this context is the analytical proof of the coextraction of copper and tin from the copper-tin mine at Mushiston, Tajikistan, and the first direct link of tin in bronze objects with a tin deposit. Mushiston apparently supplied both cultural macro regions with a “natural” bronze, which accounted for about one third of all objects analysed, but there is no indication yet that metal or ores from Mushiston were traded or used at a distance of more than 500 km. Moreover, the artefact data indicates a decline in the exploitation of the mine in the course of the developed LBA, while other copper and tin sources in the Tian Shan and probably the Hindukush were exploited. This testifies to the intensive use of the rich mineral resources of Central Asia and beyond, as well as the intensification of cultural and trade contacts between Andronovo and the BMAC.
    Materialart: Online-Ressource
    ISSN: 2296-6463
    Sprache: Unbekannt
    Verlag: Frontiers Media SA
    Publikationsdatum: 2023
    ZDB Id: 2741235-0
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Online-Ressource
    Online-Ressource
    Frontiers Media SA ; 2023
    In:  Frontiers in Earth Science Vol. 11 ( 2023-8-4)
    In: Frontiers in Earth Science, Frontiers Media SA, Vol. 11 ( 2023-8-4)
    Kurzfassung: Tin was a crucial commodity in prehistory to produce bronze, and knowledge of the origins of this metal is important for understanding cultural relations and the complexity and extent of trade. However, many aspects of the provenance of tin are still not resolved. A recent study in Science Advances 8(48) examined the historically significant tin ingots from the Uluburun shipwreck, which are key to the economy and long-distance trade of tin in the Late Bronze Age Mediterranean and beyond. Isotopic and chemical data of the objects was collected, from which a tin origin from Central Asia, particularly Mushiston in Tajikistan, and Anatolia was reconstructed. The study thereby proposed a solution to the long-standing riddle of tin provenance via scientific reasoning and comparative data. While this avenue of investigation is intriguing, this article maintains that the authors’ arguments do not support their far-reaching conclusions. Instead, it emphasises the similarities with Late and Middle Bronze Age tin ingots from Israel and Britain, and alternatively suggests a common origin of part of the Uluburun cargo with these items. South-west England is considered a very likely source region, but other tin ingots of the Uluburun wreck could also originate from Afghanistan and perhaps somewhere else.
    Materialart: Online-Ressource
    ISSN: 2296-6463
    Sprache: Unbekannt
    Verlag: Frontiers Media SA
    Publikationsdatum: 2023
    ZDB Id: 2741235-0
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Online-Ressource
    Online-Ressource
    Frontiers Media SA ; 2024
    In:  Frontiers for Young Minds Vol. 12 ( 2024-3-20)
    In: Frontiers for Young Minds, Frontiers Media SA, Vol. 12 ( 2024-3-20)
    Kurzfassung: Whenever you read books, listen to music, or watch TV, your brain is using signals made from electricity and chemicals to help you understand the world around you. Your brain is full of cells called neurons that communicate with each other through these signals. Chemicals released from neurons transmit messages to their surrounding neighbors, telling the neighbors whether they should send a signal too. But it is electricity traveling down the length of the neuron that causes the release of those chemicals in the first place. Because electricity is involved in communication between neurons, scientists can use magnets to change the flow of electricity in the brain and explore how that affects behavior. A method called transcranial magnetic stimulation allows scientists who study the brain to stimulate the brain from outside a person’s head (through the skull). This gives scientists clues about brain functioning without requiring dangerous brain surgery!
    Materialart: Online-Ressource
    ISSN: 2296-6846
    Sprache: Unbekannt
    Verlag: Frontiers Media SA
    Publikationsdatum: 2024
    ZDB Id: 2742758-4
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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