The European Rosetta mission has been following comet 67P/Churyumov-Gerasimenko for 2 years, studying the nucleus and coma in great detail. For most of these 2 years the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) has analysed the volatile part of the coma. With its high mass resolution and sensitivity it was able to not only detect deuterated water HDO, but also doubly deuterated water, DO and deuterated hydrogen sulfide HDS. The ratios for [HDO]/[HO], [DO]/[HDO] and [HDS]/[HS] derived from our measurements are (1.05 ± 0.14) × 10, (1.80 ± 0.9) × 10 and (1.2 ± 0.3) × 10, respectively. These results yield a very high ratio of 17 for [DO]/[HDO] relative to [HDO]/[HO]. Statistically one would expect just 1/4. Such a high value can be explained by cometary water coming unprocessed from the presolar cloud, where water is formed on grains, leading to high deuterium fractionation. The high [HDS]/[HS] ratio is compatible with upper limits determined in low-mass star-forming regions and also points to a direct correlation of cometary HS with presolar grain surface chemistry.This article is part of the themed issue 'Cometary science after Rosetta'.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5454224 | PMC |
| http://dx.doi.org/10.1098/rsta.2016.0253 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Interaction of Cyclosporin C with Dy Ions in Acetonitrile and in Complex with Dodecylphosphocholine Micelles Determined by NMR Spectroscopy.
Int J Mol Sci
December 2024
Institute of Physics, Kazan Federal University, 18 Kremlevskaya St., Kazan 420008, Russia.
The spectral characteristics of cyclosporin C (CsC) with the addition of Dy ions in acetonitrile (CDCN) and CsC with Dy incorporated into dodecylphosphocholine (DPC) micelle in deuterated water were investigated by high-resolution NMR spectroscopy. The study was focused on the interaction between Dy ions and CsC molecules in different environments. Using a combination of one-dimensional and two-dimensional NMR techniques, we obtained information on the spatial features of the peptide molecule and the interaction between CsC and the metal ion.
View Article and Find Full Text PDFShedding new light on the hidden complexity of seeds: chemically selective imaging of seed coats with stimulated Raman scattering microscopy.
Analyst
January 2025
Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK.
The seed coat plays a pivotal role in seed development and germination, acting as a protective barrier and mediating interac-tions with the external environment. Traditional histochemical techniques and analytical methods have provided valuable insights into seed coat composition and function. However, these methods often suffer from limitations such as indirect chemical signatures and lack of spatial resolution.
View Article and Find Full Text PDFA well-balanced vegan diet does not compromise daily mixed muscle protein synthesis rates when compared to an omnivorous diet in active older adults: a randomized controlled cross-over trial.
J Nutr
December 2024
Division of Human Nutrition and Health, Wageningen University, Wageningen, The Netherlands.
Background: Plant-based foods have reduced protein digestibility and frequently display unbalanced amino acid profiles. Plant-based foods are therefore considered inferior to animal-based foods in their anabolic potential. No study has assessed the anabolic potential of a vegan diet that provides a large variety of plant-based protein sources in older adults.
View Article and Find Full Text PDFReductive Zincke Reaction: Opening of Pyridinium Rings to δ-Amino Ketones via Transfer Hydrogenation.
Chemistry
December 2024
Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK.
The Zincke reaction and Birch reduction have been one of the few reactions that allow for ring opening of pyridines ever since the discovery of pyridine more than a century ago. This paper presents a new addition to the list of pyridine ring-opening reactions, reductive Zincke reaction, which affords saturated δ-amino ketones. Under the catalysis of a simple rhodium complex, pyridinium salts with diverse substituents are reduced with formic acid, ring-opened with water, transaminated with a secondary amine and further reduced to afford a wide range of δ-amino ketones, including those in which the alkane chain of the ketones is selectively deuterated or fluorinated.
View Article and Find Full Text PDFPhotocatalytic Multiple Deuteration of Polyethylene Glycol Derivatives Using Deuterium Oxide.
Chemistry
December 2024
Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka, 565-0871, Japan.
Deuterated molecules are of growing interest because of the specific characteristics of deuterium, such as stronger C-D bonds being stronger than C-H bonds. Polyethylene glycols (PEGs) are widely utilized in scientific fields (e. g.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!