Results 51 to 60 of about 7,461,069 (375)

Reactions of Graphene Nano-Flakes in Materials Chemistry and Astrophysics

Physchem, 2022
The elucidation of the mechanism of the chemical evolution of the universe is one of the most important themes in astrophysics. Polycyclic aromatic hydrocarbons (PAHs) provide a two-dimensional reaction field in a three-dimensional interstellar space ...
Hiroto Tachikawa, Tetsuji Iyama
doaj   +1 more source

THE APPEARANCE OF LIFE [PDF]

Filozofia i Nauka
The article presents the hypothesis of the origin of life. All the basic ideas of the 20th century research program in this area can be found there: the extrapolation of Darwinism into the area of chemical evolution, the influence of solar energy, the ...
Richard Krzymowski
doaj   +1 more source

Volatile Organic Compounds of Bryophytes from Peninsular Malaysia and Their Roles in Bryophytes

Plants, 2022
Volatile emissions from 22 bryophyte species from Peninsular Malaysia were collected using a dynamic headspace technique and analyzed by gas chromatography–mass spectrometry (GC-MS).
Chin Wen Koid, Nur Fariza M. Shaipulah, Gaik Ee Lee, S. Robbert Gradstein, Yoshinori Asakawa, Yosie Andriani, Arifullah Mohammed, Nik Norhazrina, Poh Wai Chia, Muhammad Zulhimi Ramlee   +9 more
doaj   +1 more source

Mapping the Galactic Metallicity Gradient with Open Clusters: The State-of-the-Art and Future Challenges

Universe, 2022
In this paper, we make use of data collected for open cluster members by high-resolution spectroscopic surveys and programmes (i.e., APOGEE, Gaia-ESO, GALAH, OCCASO, and SPA). These data have been homogenised and then analysed as a whole.
Lorenzo Spina, Laura Magrini, Katia Cunha   +2 more
doaj   +1 more source

Chemical evolution of a protoplanetary disk [PDF]

, 2011
In this paper we review recent progress in our understanding of the chemical evolution of protoplanetary disks. Current observational constraints and theoretical modeling on the chemical composition of gas and dust in these systems are presented.
Agúndez, Aikawa, Bergin, Bisschop, Bouvier, Bradley, Brownlee, d'Hendecourt, Dartois, Dmitry A. Semenov, Dutrey, Dutrey, Dutrey, Gail, Gail, Guilloteau, Güdel, Habart, Habing, Hartquist, Hersant, Ilgner, Keller, Lee, Leger, Lin, Markwick, Nomura, Panić, Piétu, Piétu, Semenov, Semenov, Shakura, Thi, Tielens, Tscharnuter, van den Ancker, van der Plas, van Dishoeck, van Zadelhoff, Visser, Visser, Wehrstedt, Williams, Woodall, Öberg   +46 more
core   +1 more source

A High-Pressure, High-Temperature Flow Reactor Simulating the Hadean Earth Environment, with Application to the Pressure Dependence of the Cleavage of Avocado Viroid Hammerhead Ribozyme

Life, 2022
The RNA world hypothesis suggests that chemical networks consisting of functional RNA molecules could have constructed a primitive life-like system leading a first living system.
Kunio Kawamura, Mari Ogawa, Noriko Konagaya, Yoshimi Maruoka, Jean-François Lambert, Louis M. P. Ter-Ovanessian, Jacques Vergne, Guy Hervé, Marie-Christine Maurel   +8 more
doaj   +1 more source

Setting the volatile composition of (exo)planet-building material. Does chemical evolution in disk midplanes matter? [PDF]

, 2016
[Abridged] Chemical evolution in the protoplanetary disk midplane can modify the composition of ices and gases. We have investigated if and how chemical evolution affects the abundances and distributions of key volatile species in the midplane of a ...
C. Eistrup, C. Walsh, E. Dishoeck
semanticscholar   +1 more source

Prebiotic Chemistry: Geochemical Context and Reaction Screening

Life, 2013
The origin of life on Earth is widely believed to have required the reactions of organic compounds and their self- and/or environmental organization. What those compounds were remains open to debate, as do the environment in and process or processes by ...
Henderson James Cleaves
doaj   +1 more source

Hypernova Nucleosynthesis and Galactic Chemical Evolution [PDF]

, 2001
We study nucleosynthesis in 'hypernovae', i.e., supernovae with very large explosion energies ($ \gsim 10^{52} $ ergs) for both spherical and aspherical explosions.
AI Macfadyen, AM Khokhlov, B Paczynski, C Sneden, D Argast, F-K Thielemann, G Nelemans, H Umeda, H Umeda, I Hachisu, I Hachisu, J Sollerman, K Iwamoto, K Iwamoto, K Iwamoto, K Maeda, K Maeda, K Nomoto, K Nomoto, K Nomoto, LAJ Blake, LM Germany, M Hashimoto, Nakamura, P Podsiadlowski, PA Mazzali, S Nagataki, SG Ryan, Shigeyama. T., amp Tsujimoto, T, TG Tsuru, V Bromm, WD Arnett, WN Brandt   +32 more
core   +2 more sources

Origin of the Reductive Tricarboxylic Acid (rTCA) Cycle-Type CO2 Fixation: A Perspective

Life, 2017
The reductive tricarboxylic acid (rTCA) cycle is among the most plausible candidates for the first autotrophic metabolism in the earliest life. Extant enzymes fixing CO2 in this cycle contain cofactors at the catalytic centers, but it is unlikely that ...
Norio Kitadai, Masafumi Kameya, Kosuke Fujishima   +2 more
doaj   +1 more source