Results 131 to 140 of about 24,904 (238)

Monsoon differences in South Asia and East Asia during the penultimate deglaciation revealed by speleothem oxygen isotopes. [PDF]

Sci Rep
Zhao J, Cui J, Pan L, Luo Q, Dong X, Wang J, Wang K, Cheng H.   +7 more
europepmc   +1 more source

Water‐Derived Radical Species Initiate Six‐Electron Oxidation of Cyclic Ketones in Microdroplets

Angewandte Chemie, EarlyView.
Spontaneous six‐electron oxidation of cyclic ketones to yield dicarboxylic acids/keto acids is achieved in ethanol microdroplets containing about 2% water under ambient conditions without any metal salts, acids, or oxidants. Mechanistic studies show that trace amounts of water and molecular oxygen serve as active oxidants in this transformation ...
Muhammad Mujahid Ali, Manish Jana, William LeFever, Robert Graham Cooks   +3 more
wiley   +2 more sources

New Water Oxidation Mechanism in Photosystem II Resolves Major Experimental Controversies

Angewandte Chemie, EarlyView.
In Photosystem II Oxygen Evolving Complex, we discovered the O3‐O6 peroxide at lower energy. Assignment of the O3 ligated by histidine (His337) as a slow exchanging substrate and its coupling with O6 give the O─O bond formation mechanism most consistent with all currently available experimental data. Proposal shows how protein environment can steer the
Yulia Pushkar
wiley   +2 more sources

Mass-independent fractionation of oxygen isotopes during high-temperature condensation in cosmochemical plasmas. [PDF]

Proc Natl Acad Sci U S A
Asset N, Chaussidon M, Lombardi G, Villeneuve J, Tartèse R, Mostefaoui S, Robert F.   +6 more
europepmc   +1 more source

The relationship between CM and CO chondrites: Insights from combined analyses of titanium, chromium, and oxygen isotopes in CM, CO, and ungrouped chondrites. [PDF]

Geochim Cosmochim Acta, 2021
Torrano ZA, Schrader DL, Davidson J, Greenwood RC, Dunlap DR, Wadhwa M.   +5 more
europepmc   +1 more source

Highly Enantio‐ and Diastereoselective Synthesis of Tetrahydrofuran Frameworks via Chiral Lewis Acid‐Catalyzed Formal [3+2] Cycloaddition of Allylsilanes

Angewandte Chemie, EarlyView.
The first catalytic asymmetric formal [3+2] cycloaddition of allylsilanes delivers cis‐2,5‐disubstituted tetrahydrofuran‐3‐ones that serve as versatile intermediates for the synthesis of diverse bioactive scaffolds. ABSTRACT A formal [3+2] cycloaddition via cyclization/1,2‐hydride shift initiated by nucleophilic attack of allylsilanes has been ...
Hosung Lee, Dong Kyu Kim, Pingshan Xin, Jin Won Lee, Terim Seo, Do Hyun Ryu   +5 more
wiley   +2 more sources

Opposing seasonal trends in source water and sugar dampen intra-annual variability in tree rings oxygen isotopes. [PDF]

New Phytol
Szejner P, Tang Y, Angove C, Schiestl-Aalto P, Sahlstedt E, Young G, Nelson DB, Kahmen A, Saurer M, Rinne-Garmston KT.   +9 more
europepmc   +1 more source

Hyperpolarization of Pyridine 15N‐Oxide Molecular Probes Enabled by Parahydrogen

Angewandte Chemie, EarlyView.
Pyridine 15N‐oxides are introduced as motifs for hyperpolarization studies and biochemical applications are demonstrated. ABSTRACT Magnetic resonance (MR) is a powerful non‐invasive technique for probing structural, functional, and metabolic processes with high spatial and temporal resolution.
Ruhuai Mei, Lisa Maria Fries, Gonzalo Gabriel Rodriguez, Charlotte von Petersdorff‐Campen, Leander Konstantin May, Julius Frederik Matz, Sergey Korchak, Grysette Daher, Stefan Glöggler   +8 more
wiley   +2 more sources

Triple oxygen isotopes of lunar water unveil indigenous and cometary heritage. [PDF]

Proc Natl Acad Sci U S A
Thiemens MM, Martinez MHN, Thiemens MH.
europepmc   +1 more source

A two-stage mantle plume-sagduction origin of Archean continental crust revealed by water and oxygen isotopes of TTGs. [PDF]

Sci Adv
Zhao D, Cawood PA, Teng FZ, Zhao G, Xia XP, Sun M, Wang X.   +6 more
europepmc   +1 more source