scholarly journals New Attempts to Understand Nanodiamond Stardust

2012 ◽  
Vol 29 (2) ◽  
pp. 90-97 ◽  
Author(s):  
U. Ott ◽  
A. Besmehn ◽  
K. Farouqi ◽  
O. Hallmann ◽  
P. Hoppe ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Trace Elements ◽  
Secondary Ion Mass Spectrometry ◽  
History Of ◽  
Sims Analysis ◽  
R Process ◽  
Bulk Diamond ◽  
Neutron Burst ◽  
Secondary Ion ◽  
Separation Model

AbstractWe report on a concerted effort aimed at understanding the origin and history of the pre-solar nanodiamonds in meteorites including the astrophysical sources of the observed isotopic abundance signatures. This includes measurement of light elements by secondary ion mass spectrometry (SIMS), analysis of additional heavy trace elements by accelerator mass spectrometry (AMS) and dynamic calculations of r-process nucleosynthesis with updated nuclear properties. Results obtained indicate that: (i) there is no evidence for the former presence of now-extinct 26Al and 44Ti in our diamond samples other than what can be attributed to silicon carbide and other ‘impurities’, and this does not offer support for a supernova (SN) origin but neither does it negate it; (ii) analysis by AMS of platinum in ‘bulk diamond’ yields an overabundance of r-only 198Pt that at face value seems more consistent with the neutron burst than with the separation model for the origin of heavy trace elements in the diamonds, although this conclusion is not firm given analytical uncertainties; (iii) if the Xe–H pattern was established by an unadulterated r-process, it must have been a strong variant of the main r-process, which possibly could also account for the new observations in platinum.

scholarly journals Mechanisms of lipid preservation in archaeological clay ceramics revealed by mass spectrometry imaging

2020 ◽  
Vol 117 (26) ◽  
pp. 14688-14693
Author(s):  
Simon Hammann ◽  
David J. Scurr ◽  
Morgan R. Alexander ◽  
Lucy J. E. Cramp
Keyword(s):  
Mass Spectrometry ◽  
Cross Sections ◽  
Secondary Ion Mass Spectrometry ◽  
Ceramic Vessels ◽  
Sims Analysis ◽  
Clay Ceramics ◽  
Available Information ◽  
Secondary Ion ◽  
Inorganic Matrix

Traces of lipids, absorbed and preserved for millennia within the inorganic matrix of ceramic vessels, act as molecular fossils and provide manifold information about past people’s subsistence, diet, and rituals. It is widely assumed that lipids become preserved after adsorption into nano- to micrometer-sized pores, but to this day the distribution of these lipids in the ceramics was virtually unknown, which severely limits our understanding about the process of lipid preservation. Here we use secondary ion mass spectrometry (SIMS) imaging for directin situanalysis of lipids absorbed in 700- to 2,000-y-old archaeological pottery. After sectioning from larger sherds, wall cross-sections of smaller fragments were used for SIMS analysis. Lipids were found in relatively large zones of 5- to 400-µm diameter, which does not support the notion of absorption only into individual nanometer-scale pores but indicates that more macroscopic structures in the ceramics are involved in lipid preservation as well. Furthermore, lipids were found concentrated on calcium carbonate inclusions in the ceramics, which suggests that precipitation of fatty acids as calcium salts is an important aspect of lipid preservation in archaeological samples. This has important implications for analytical methods based on extraction of lipids from archaeological ceramics and needs to be considered to maximize the yield and available information from each unique sample.

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