Results 31 to 40 of about 67,641 (245)

Núcleos exóticos e síntese dos elementos químicos

Química Nova, 2012
We have around ninety chemical elements available in nature, which were produced mainly by nuclear reactions inside stars. The fusion reactions are the main synthesis process which generates the light and intermediate masses elements.
Nilton Teruya, Sérgio Barbosa Duarte
doaj   +1 more source

Magellanic Clouds Cepheids: Thorium Abundances [PDF]

Journal of Astronomy and Space Sciences, 2018
The analysis of the high-resolution spectra of 31 Magellanic Clouds Cepheid variables enabled the identification of thorium lines. The abundances of thorium were found with spectrum synthesis method. The calculated thorium abundances exhibit correlations
Yeuncheol Jeong, Alexander V. Yushchenko, Vira F. Gopka, Volodymyr O. Yushchenko, Valery V. Kovtyukh, Svetlana V. Vasil’eva   +5 more
doaj   +1 more source

Inhomogeneous Big-Bang Nucleosynthesis in Light of Recent Observations [PDF]

, 1998
We consider inhomogeneous big bang nucleosynthesis in light of the present observational situation. Different observations of He-4 and D disagree with each other, and depending on which set of observations one uses, the estimated primordial He-4 ...
Kainulainen, K., Kurki-Suonio, H., Sihvola, E.   +2 more
core   +2 more sources

Hydrogen Tunneling in Stoichiometric and Catalytic Reactions involving Transition Metals

ChemCatChem, Volume 15, Issue 24, December 19, 2023., 2023
An overview on the importance of the participation of hydrogen tunneling in E−H bond activation reactions (E=C, O, Si…) mediated by transition metals is presented. Understanding when hydrogen tunneling occurs can be a powerful tool for designing new catalysts to perform challenging reactions.
Jon M. Matxain, Miguel A. Huertos
wiley   +1 more source

s-Processing in Asymptotic Giant Branch Stars in the Light of Revised Neutron-Capture Cross Sections

Universe, 2021
Current AGB stellar models provide an adequate description of the s-process nucleosynthesis that occurs. Nonetheless, they still suffer from many uncertainties related to the modeling of the 13C pocket formation and the adopted nuclear reaction rates ...
Diego Vescovi, René Reifarth
doaj   +1 more source

Presupernova Evolution and Explosive Nucleosynthesis of Rotating Massive Stars in the Metallicity Range −3 ≤ [Fe/H] ≤ 0 [PDF]

Astrophysical Journal Supplement Series, 2018
We present a new grid of presupernova models of massive stars extending in mass between 13 and 120 , covering four metallicities (i.e., [Fe/H] = 0, −1, −2, and −3) and three initial rotation velocities (i.e., 0, 150, and 300 km s−1).
M. Limongi, A. Chieffi
semanticscholar   +1 more source

Updating constraints on f(T) teleparallel cosmology and the consistency with big bang nucleosynthesis [PDF]

, 2020
We focus on viable f(T) teleparallel cosmological models, namely power law, exponential and square-root exponential, carrying out a detailed study of their evolution at all scales.
M. Benetti, S. Capozziello, G. Lambiase
semanticscholar   +1 more source

A Proposal for a Low‐Frequency Axion Search in the 1–2 μ$\umu$ eV Range and Below with the BabyIAXO Magnet

Annalen der Physik, Volume 535, Issue 12, December 2023., 2023
This article describes the implementation of low‐frequency axion haloscope setups inside the future BabyIAXO magnet. The RADES proposal has a potential sensitivity to the axion‐photon coupling down to values corresponding to the KSVZ model, in the mass range between 1 and 2 μ$\umu$eV.
Saiyd Ahyoune, Alejandro Álvarez Melcón, Sergio Arguedas Cuendis, Sergio Calatroni, Cristian Cogollos, Jack Devlin, Alejandro Díaz‐Morcillo, David Díez‐Ibáñez, Babette Döbrich, Javier Galindo, Juan Daniel Gallego, Jose María García‐Barceló, Benito Gimeno, Jessica Golm, Yikun Gu, Louis Herwig, Igor Garcia Irastorza, Antonio Jose Lozano‐Guerrero, Chloé Malbrunot, Jordi Miralda‐Escudé, Juan Monzó‐Cabrera, Pablo Navarro, Jose Ramón Navarro‐Madrid, Javier Redondo, José Reina‐Valero, Kristof Schmieden, Tim Schneemann, Marc Siodlaczek, Stefan Ulmer, Walter Wuensch   +29 more
wiley   +1 more source

Prospect for measurements of (γ, n) reaction cross-sections of p-nuclei at ELI-NP

Frontiers in Astronomy and Space Sciences, 2023
The gamma beam system under construction at the ELI-NP facility in Romania is projected to give the nuclear physics community access to an experimental system providing a high-intensity, narrow bandwidth photon beam at variable energy.
P.-A. Söderström, A. Kuşoğlu, A. Kuşoğlu, D. Testov   +3 more
doaj   +1 more source

Kinetics of the tautomerization of thioimidic acids R−C(SH)NH → R−C(S)NH2: For R = H, F, HO, CN, NC, H2N, HC(O), HC(S), HC≡ C, CH3, CF3, H2C=CH, HOCH2, H2NCH2,CH3C(O), C2H5, (CH3)2CH, C6H5

International Journal of Chemical Kinetics, Volume 55, Issue 11, Page 731-742, November 2023., 2023
Abstract The kinetics of the tautomerization of thio‐imidic acids RC(SH)NH were determined at low (50–300 K) and high (500–1500 K) temperatures as R was varied to encompass mono‐ and diatomic species H, F, HO, NC, CN through H2N, HC(O), HC(S), HC≡ C, H3C, F3C, HOCH2, H2C=CH, CH3C(O), H2NCH2 and including ethyl, isopropyl and phenyl groups. The presence
Judith Würmel, John M. Simmie
wiley   +1 more source