The insulator-to-metal transition in dense fluid hydrogen is an essential phenomenon in the study of gas giant planetary interiors and the physical and chemical behavior of highly compressed condensed matter. Using direct fast laser spectroscopy techniques to probe hydrogen and deuterium precompressed in a diamond anvil cell and laser heated on microsecond timescales, an onset of metal-like reflectance is observed in the visible spectral range at >150 GPa and ≥ 3000 K. The reflectance increases rapidly with decreasing photon energy indicating free-electron metallic behavior with a plasma edge in the visible spectral range at high temperatures. The reflectance spectra also suggest much longer electronic collision time (≥1 fs) than previously inferred, implying that metallic hydrogen at the conditions studied is not in the regime of saturated conductivity (Mott-Ioffe-Regel limit). The results confirm the existence of a semiconducting intermediate fluid hydrogen state en route to metallization.
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http://dx.doi.org/10.1002/advs.201901668 | DOI Listing |
Amino Acids
January 2025
Laboratory of Molecular Biology and Immunology, Department of Pharmacy, University of Patras, 26500, Rio-Patras, Greece.
Taurine, although not a coding amino acid, is the most common free amino acid in the body. Taurine has multiple and complex functions in protecting mitochondria against oxidative-nitrosative stress. In this comprehensive review paper, we introduce a novel potential role for taurine in protecting from deuterium (heavy hydrogen) toxicity.
View Article and Find Full Text PDFMol Cell Proteomics
January 2025
Broad Institute of MIT & Harvard, Cambridge, MA. Electronic address:
Despite the widespread use of MS for hydrogen/deuterium exchange measurements, no systematic, large-scale study has been conducted to compare the observed exchange rates in protein-derived, unstructured peptides measured by MS to the predicted exchange rates calculated from NMR-derived values and how neighboring residues and post-translational modifications influence those exchange rates. In this study, we sought to test the accuracy of predicted values by performing hydrogen exchange measurements on whole cell digests to generate an unbiased dataset of 563 unique peptides derived from naturally-occurring protein sequences. A remarkable 97% of observed exchange rates of peptides are within two-fold of predicted values.
View Article and Find Full Text PDFJ Org Chem
January 2025
School of Chemistry, IGCME, The Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, Guangdong Provincial Key Laboratory of Chiral Molecules and Drug Discovery, Sun Yat-sen University, Guangzhou 510006, People's Republic of China.
The ligand-free Lewis acid-mediated regioselective hydroamination and hydroarylation of styrenes have been successfully developed in the presence of isatins or heterocyclic aryl compounds such as benzothiophenes and benzofurans. The reactions tolerate a variety of functional groups and afford the corresponding products in moderate to good yields. Deuterium labeling experiments show that the functionalized hydrogen of styrenes was derived from the nitrogen-hydrogen of the substrates in the hydroamination.
View Article and Find Full Text PDFSci Rep
January 2025
Leibniz Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Str. 17, 10315, Berlin, Germany.
Wind turbines used to combat climate change pose a green-green dilemma when endangered and protected wildlife species are killed by collisions with rotating blades. Here, we investigated the geographic origin of bats killed by wind turbines along an east-west transect in France to determine the spatial extent of this conflict in Western Europe. We analysed stable hydrogen isotopes in the fur keratin of 60 common noctule bats (Nyctalus noctula) killed by wind turbines during summer migration in four regions of France to predict their geographic origin using models based on precipitation isoscapes.
View Article and Find Full Text PDFDalton Trans
January 2025
Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Arama-ki-Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan.
A new approach for hydrogen isotope separation using an unsaturated organometallic complex was proposed. Adsorption measurements of [Mn(dppe)(CO)(N)](BArF) (Mn-dppe) (dppe = 1,2-bis(diphenylphosphino)ethane, BArF = B[CH(3,5-CF)]) using H and D revealed a significant difference in the adsorption enthalpy of H/D at much higher room temperatures than in previous studies, with D molecules being more strongly adsorbed on unsaturated metal sites. Mixed gas adsorption isotherms were calculated at each temperature using IAST, and it was predicted that D uptake was much larger than H uptake.
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