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Wyświetlanie 1-5 z 5
Tytuł:
Possible role of radon in prebiotic chemistry and in early evolution of Life on Earth
Autorzy:
Zagórski, Z. P.
Powiązania:
https://bibliotekanauki.pl/articles/148902.pdf
Data publikacji:
2010
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
great oxidation event
ionizing radiation
prebiotic chemistry
radon
thoron
uranium
Opis:
Radon in the environment of early Earth was present in sites, determined by location of deposits of uranium, in very different geological formations. According to the decay of uranium-238, the total production of radon at the beginnings was twice as high as now and was continuously diminishing to the present levels. This nuclide could not play as big a role as do radioactive elements connected with the presence of high concentration of 235U, which was high enough in some places to give rise to formation of natural nuclear fission reactors (e.g. Oklo phenomenon in Africa). The main role of ionizing radiation in prebiotic chemistry and biological evolution was played by low LET (linear energy transfer) radiations, as deep penetrating sources of external energy. High LET radiations are of low penetration and could act only superficially. Radon is an exception, due to its easy transfer in the air. Therefore, it could play a role already in the cases of these early organisms which exhibited the gaseous exchange of chemical compounds with the surrounding atmosphere. The action was destructive, but, on the other hand, was also mutagenic. Nevertheless, the general quantitative effect of radon on the global scale could not be larger than of other radioactive nuclides. Presented considerations are part of the chapter by the present author on the role of nuclear and radiation chemistry in astrobiology, in the monograph published by American Scientific Publishers [1].
Źródło:
Nukleonika; 2010, 55, 4; 555-558
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Atomic structural templates of the earliest life on earth: vibration and lightning experiments with quartz and amino acids
Autorzy:
Pawlikowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/344000.pdf
Data publikacji:
2012
Wydawca:
nakł. Maciej Pawlikowski
Tematy:
quartz
acids
templates
Opis:
The atomic structure of minerals and organic molecules is remarkably similar. In particular, between minerals and amino acids, which are the building blocks of life on Earth. The hypothesis tested here is the possibility of energy transfer from minerals to amino acids, in the form of solar energy. The experiments tested the theory that the brighter intensity of light in the early Earth may have kick -started the chemical reactions needed for life. The scenario under investigation is that of light reacting with quartz sand grains exposed at the surface. The quartz grains contain water within the pore spaces, which has basic amino acid structures within in. The experiments determined that the vibration of piezoelectric quartz altered the structure of amino acid molecules.
Źródło:
Auxiliary Sciences in Archaeology, Preservation of Relics and Environmental Engineering; 2012, 14; 1-8
1689-6742
Pojawia się w:
Auxiliary Sciences in Archaeology, Preservation of Relics and Environmental Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The old and new RNA world
Autorzy:
Szweykowska-Kulinska, Z.
Powiązania:
https://bibliotekanauki.pl/articles/57730.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
Earth
RNA world hypothesis
life
ribozyme
small RNA
long noncoding RNA
Opis:
Among the numerous hypotheses offering a scenario for the origin of life on Earth, the one called “The RNA World” has gained the most attention. According to this hypothesis RNA acted as a genetic information storage material, as a catalyst of all metabolic reactions, and as a regulator of all processes in the primordial world. Various experiments show that RNA molecules could have been synthesized abiotically, with the potential to mediate a whole repertoire of metabolic reactions. Ribozymes carrying out aminoacyl-tRNA reactions have been found in SELEX (systematic evolution of ligands by exponential enrichment) approaches and the development of a ribosome from a RNA-built protoribosome is easy to imagine. Transfer RNA aminoacylation, protoribosome origin, and the availability of amino acids on early Earth allowed the genetic code to evolve. Encoded proteins most likely stabilized RNA molecules and were able to create channels across membranes. In the modern cell, DNA replaced RNA as the main depositor of genetic information and proteins carry out almost all metabolic reactions. However, RNA is still playing versatile, crucial roles in the cell. Apart from its classical functions in the cell, a huge small RNA world is controlling gene expression, chromatin condensation, response to environmental cues, and protecting the cell against the invasion of various nucleic acids forms. Long non-coding RNAs act as crucial gene expression regulators. Riboswitches act at the level of transcription, splicing or translation and mediate feedback regulation on biosynthesis and transport of the ligand they sense. Alternative splicing generates genetic variability and increases the protein repertoire in response to developmental or environmental changes. All these regulatory functions are essential in shaping cell plasticity in the changing milieu. Recent discoveries of new, unexpected and important functions of RNA molecules support the hypothesis that we live in a New RNA World.
Źródło:
Acta Societatis Botanicorum Poloniae; 2014, 83, 4
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Life Cycle Inventory (LCI) Stochastic Approach Used for Rare Earth Elements (REEs), Considering Uncertainty
Autorzy:
Sala, Dariusz
Bieda, Bogusław
Powiązania:
https://bibliotekanauki.pl/articles/2020124.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
Life cycle inventory (LCI)
stochastic approach
rare earth elements (REEs)
LCA
inwentaryzacja cyklu życia
analiza stochastyczna
pierwiastki ziem rzadkich
Opis:
The purpose of the paper is to present the results of the stochastic modelling with uncertainty performed with the use of Monte Carlo (MC) simulation with 10,000 cycles and a confidence interval of 95 %, as recommended. Analysed REEs were fitted by lognormal distributions by using the Crystal Ball® (CB) spreadsheet-based software after defining the geometric mean value (μg) and the standard deviation (σg), automatically calculated (matches) the lower, as well as, upper boundaries of lognormal distribution. The number of replications of a simulation affects the quality of the results. The principal output report provided by CB and presented in this study consists of the graphical representation in the form of the frequency chart, percentiles summary, and statistics summary. Additional CB options provide a sensitivity analysis with tornado diagrams. The data that was used for MC simulation of the LCI model includes available and published data concerning associated with the REEs. This paper discusses the results and show that the adopted approach is applicable for any REEs used in the LCI studies under uncertainty. The results obtained from this study can be used as the first step in performing a full LCA analysis and help practitioners as well as decision-makers in the environmental engineering and management.
Źródło:
Inżynieria Mineralna; 2021, 2; 283--291
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study On The Separation And Extraction Of Rare-Earth Elements From The Phosphor Recovered From End Of Life Fluorescent Lamps
Badanie separacji i ekstrakcji metali ziem rzadkich z fosforu ze zużytych świetlówek
Autorzy:
Shin, D.-W.
Kim, J. G.
Powiązania:
https://bibliotekanauki.pl/articles/351714.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
recycle
yttrium
phosphor
end of life
recykling
itr
fosfor
świetlówki
Opis:
In this study, recovered phosphor from end of life three-wavelength fluorescent lamp was selected for reuse rare earth elements in the phosphor. The effect of a type of acid, concentration, and time was investigated as solubility of rare earth elements. In addition, precipitate heat-treated was investigated as possibility of reusable phosphor. The results showed that the amount of the rare earth elements was different values depending on the type of acid, and it was investigated with concentration of acid and reaction time. After precipitation reaction, the precipitate was sintered in electric furnace in order to reuse rare earth elements as phosphor. It was confirmed that yttrium, europium, oxygen, and carbon through X-ray diffraction and inductively coupled plasma analysis. Following the results, it can assume that rare earth oxide reuse the phosphor as three-wavelength fluorescent lamp.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1257-1260
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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