Results 81 to 90 of about 7,461,069 (375)

The Mystery of Homochirality on Earth

Life
Homochirality is an obvious feature of life on Earth. On the other hand, extraterrestrial samples contain largely racemic compounds. The same is true for any common organic synthesis.
Michael G. Weller
doaj   +1 more source

Metallicity Evolution in the Early Universe [PDF]

, 2000
Observations of the damped Lya systems provide direct measurements on the chemical enrichment history of neutral gas in the early universe. In this Letter, we present new measurements for four damped Lya systems at high redshift.
Arthur M. Wolfe, Edmunds M. G., Grevesse N., Jason X. Prochaska, Le Brun V., Sneden C.   +5 more
core   +2 more sources

CONTRIBUTION OF NEUTRON STAR MERGERS TO THE r-PROCESS CHEMICAL EVOLUTION IN THE HIERARCHICAL GALAXY FORMATION [PDF]

, 2016
The main astronomical source of r-process elements has not yet been identified. One plausible site is neutron star mergers (NSMs), but from the perspective of the Galactic chemical evolution, it has been pointed out that NSMs cannot reproduce the ...
Y. Komiya, T. Shigeyama
semanticscholar   +1 more source

The Chemical Evolution of Helium [PDF]

The Astronomical Journal, 2006
19 pages, 3 figures (accepted for publication in the AJ)
openaire   +4 more sources

Insights into PI3K/AKT signaling in B cell development and chronic lymphocytic leukemia

FEBS Letters, EarlyView.
This Review explores how the phosphoinositide 3‐kinase and protein kinase B pathway shapes B cell development and drives chronic lymphocytic leukemia, a common blood cancer. It examines how signaling levels affect disease progression, addresses treatment challenges, and introduces novel experimental strategies to improve therapies and patient outcomes.
Maike Buchner
wiley   +1 more source

A plausible pathway to prebiotic peptides via amino acid amides on the primordial Earth

Earth and Planetary Physics
The prebiotic synthesis of peptides prior to ribosome-catalyzed processes remains an enigma. The synthesis of abiotic peptides from amino acids (AAs) is primarily constrained by high activation energies and unfavorable thermodynamics, necessitating the ...
DingWei Gan, XiangMin Lei, RenWu Zhou, SongSen Fu, Jing Sun, RuSen Zhou, Kostya (Ken) Ostrikov, YuFen Zhao, JianXi Ying   +8 more
doaj   +1 more source

Extragalactic Planetary Nebulae: tracers of the chemical evolution of nearby galaxies

, 2012
The study of the chemical composition of Planetary Nebulae in external galaxies is of paramount importance in the fields of stellar evolution and of the chemical enrichment history of galaxies.
Denise R. Gonçalves, Galleti, Gonçalves, Hernández-Martínez, Izotov, Kniazev, Laura Magrini, Letizia Stanghellini, Magrini, Magrini, Magrini, Magrini, Magrini, Peña, Stanghellini, Stanghellini, Suda, Yin   +17 more
core   +1 more source

Galactic chemical evolution : Carbon through zinc [PDF]

, 2006
Copyright © 2006. The American Astronomical Society. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the final published version of the work, which was originally published at https://doi.org/
Audouse J., Carretta E., Chiaki Kobayashi, de Jager C., Edvardsson B., Gratton R. G., Gratton R. G., Hideyuki Umeda, Ibata R. A., Ken’ichi Nomoto, Kodama T., Kudritzki R. P., Nissen P. E., Nozomu Tominaga, Pagel B. E. J., Prantzos N., Sneden C., Spruit H. C., Takada-Hidai M., Takada-Hidai M., Takuya Ohkubo, Tinsley B. M., Tutukov A. V.   +22 more
core   +3 more sources

The Impact of Modeling Assumptions in Galactic Chemical Evolution Models [PDF]

, 2016
We use the OMEGA galactic chemical evolution code to investigate how the assumptions used for the treatment of galactic inflows and outflows impact numerical predictions.
Benoit Côté, B. O’Shea, C. Ritter, F. Herwig, K. Venn   +4 more
semanticscholar   +1 more source

The Evolution of Chemical Symbols [PDF]

The Journal of the American Pharmaceutical Association (1912), 1918
n ...
openaire   +3 more sources