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Wyświetlanie 1-7 z 7
Tytuł:
Why are variations in bromine isotope compositions in the Earths history larger than chlorine isotope compositions?
Autorzy:
Eggenkamp, Hans
Powiązania:
https://bibliotekanauki.pl/articles/763372.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
chlorine isotopes
bromine isotopes
Phanerozoic
redox
Opis:
In this paper we discuss the marked discrepancy in global chlorine and bromine isotope variations. While, based on experimentally and theoretically determined fractionation factors, it is expected that bromine isotope variations should be, depending on the process, 2 to 7 times less than chlorine isotope variations it is observed that in formation brines the isotope variations of bromine are at least of the same size as chlorine isotope variations, and regularly even larger. In this paper we argue that this is caused by the fact that oxidation-reduction processes play a more important role in bromine isotope geochemistry than in chlorine isotope geochemistry. Due to the fact that the bromide ion is more easily to oxidise than the chloride ion Rayleigh effects can cause the observed larger variations in bromine isotope geochemistry. In this paper we propose that biochemical reactions (oxidation of bromide ions to methyl bromide) may be the major cause for this effect. Although we do not yet understand the full processes that take place we show that oxidation-reduction processes must be the main effect to explain the differences between the two isotope systems and propose that more research is developed to understand how the processes cause the observed variations.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio AAA – Physica; 2015, 70
0137-6861
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio AAA – Physica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chemical Reduction of Gold(III) Bromide Complexes Using Sodium Nitrite - Kinetic Aspects
Autorzy:
Pacławski, K.
Powiązania:
https://bibliotekanauki.pl/articles/354755.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kinetics
mechanism
redox
gold complexes
sodium nitrite
Opis:
In this work, the spectrophotometric studies on the kinetics of redox reaction between gold(III) bromide complexes and sodium nitrite, were carried out. From the kinetic curves collected under different conditions of reactants concentration, addition of bromide ions, temperature, pH and ionic strength, corresponding rate constants have been determined. The obtained results suggest the complex path of the [AuBr4]- reduction consisting of two parallel, bimolecular reactions where different reductant species (HNO2 and NO2-) take place and consecutive step with the metallic gold production. The second-order rate constants at 20°C are equal to 2.948 and 0.191 M-1·s-1, respectively. The values of activation enthalpy and activation entropy for the first and the second parallel step of the reaction were found to be ΔH = 29.18 kJ·mol-1 and ΔS = –13.95 J·mol-1·K, and ΔH‡ = 40.75 kJ·mol-1 and ΔS‡ = –31.06 J·mol-1·K, respectively. It was found that the reaction accelerates significantly with the increase of pH and is inhibited with the increase of Br- concentration. The substitutive, inner-sphere mechanism of electron transfer in the studied system was also suggested.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 2; 667-675
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical and experimental ground of the fuel energy efficiency improvement by an activation of the burning reaction molecules - reagents
Autorzy:
Kovalyshyn, B.
Powiązania:
https://bibliotekanauki.pl/articles/410674.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Oddział w Lublinie PAN
Tematy:
wysokie napięcia
pole elektryczne
wydajność energetyczna
high voltage
electric field
activation
energy efficiency
redox
Opis:
In theory and experimentally a method of fuel options energy efficiency rise due to an activation of burning reaction molecules-reagents under high voltage electric field action is grounded. A variant of the technical realization of the offered method is described.
Źródło:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes; 2012, 1, 1; 63-66
2084-5715
Pojawia się w:
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fenomen kambryjskich łupków z Burgess w Górach Skalistych (Kanada) : przegląd fauny, środowiska sedymentacji i zjawisk tafonomicznych
The Cambrian Burgess Shale phenomenon of the Rocky Mountains (Canada) : an overview of the fauna, sedimentary and taphonomic conditions
Autorzy:
Śliwiński, M. G.
Żylińska, A.
Powiązania:
https://bibliotekanauki.pl/articles/2075033.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Cambrian
Burgess Shale
Rocky Mountains
Lagerstätten
redox
kambr
łupki z Burgess
Góry Skaliste
natlenienie wód
Opis:
The Burgess Shale of the Canadian Rocky Mts is one of the most well-known occurrences of Cambrian strata exhibiting exceptional preservation of a soft-bodied fauna. While Lagerstätten of the Burgess Shale-type fauna have been recognized in almost all parts of the world and in all Cambrian series, the circumstances and mechanisms allowing for such a unique mode of preservation have remained enigmatic. Of particular debate has been the reconstruction of prevailing redox conditions. This brief contribution overviews the fauna and recent advances towards understanding the sedimentary and taphonomic conditions prevailing during deposition.
Źródło:
Przegląd Geologiczny; 2013, 61, 12; 746--754
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prediction of indels and SNP’s in coding regions of glutathione peroxidases - an important enzyme in redox homeostasis of plants
Autorzy:
Ganguli, S.
Datta, A.
Powiązania:
https://bibliotekanauki.pl/articles/11303.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
prediction
indel
single nucleotide polymorphism
coding region
glutathione peroxidase
enzyme
redox
homeostasis
plant
genotype
stress tolerance
Opis:
Plant glutathione peroxidases are an important class of enzymes which play key roles in the stress adaptability of plants both in context of biotic and abiotic stress pathways. They have been over the years much studied in animals since the catalytic residues are comprised of selenocysteine a variant amino acid which is ribosomally encoded with the help of an RNA structural element known as SECIS. Various workers over the years have shown that plant glutathione peroxidases play active roles in ROS sequestration, lipid hydroperoxidation as well as regulate glutathione levels. However, each plant has various patterns of glutathione peroxidase expression and action and in some plants certain isoforms have not been detected at all. This work focuses on the prediction and identification of single nucleotide polymorphisms (SNPs) and INDELs in the coding regions of plant glutathione peroxidases, with the help of a Bayesian based algorithm subsequently validated. A large number of informative sites were detected 279 of which had variant frequency of ≥ 50 %. This data should be beneficial for future studies involving genetic manipulation and population based breeding experiments.
Źródło:
International Letters of Natural Sciences; 2014, 02
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Redox and nitric oxide (NO) homeostasis differentially regulated in tomato roots and leaves under salinity stress
Autorzy:
Manai, J.
Gouia, H.
Corpas, F.
Powiązania:
https://bibliotekanauki.pl/articles/80844.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
nitric oxide
redox
homeostasis
tomato
Solanum lycopersicum
root
leaf
salinity stress
plant growth
S-nitrosoglutathione
glutathione peroxidase
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2013, 94, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Framboidy pirytowe jako wskaźniki paleośrodowiska
Pyrite framboids as paleoenvironmental indicators
Autorzy:
Zatoń, M.
Rakociński, M.
Marynowski, L.
Powiązania:
https://bibliotekanauki.pl/articles/2074589.pdf
Data publikacji:
2008
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
framboidy pirytowe
redoks
warunki środowiskowe oksyczne
warunki środowiskowe dysoksyczne
warunki środowiskowe euksyniczne
jura
dewon
Polska
pyrite framboids
redox
euxinia
anoxia
dysoxia
Jurassic
Devonian
Polska
Opis:
The problemof application of pyrite framboids in reconstructions of the redox conditions is presented. The characteristics of pyrite framboids, their origin and principles of application in paleoenvironmental interpretations are given. The pyrite framboid diameter distribution as indicators of redox conditions was presented on the examples of the Middle Jurassic (Upper Bajocian-Lower Bathonian) ore-bearing clays of the Polish Jura, and Upper Devonian (Middle and Upper Famennian) dark grey and black shales from Kowala (Holy Cross Mountains). It has been shown, that during the sedimentation of the ore-bearing clays, the pyrite framboids formed in the sediment, below the oxic water column; however, some episodic oscillation around the dysoxic conditions cannot be entirely excluded. During the sedimentation of the Middle Famennian dark grey shales, the redox conditions at the sea-floor oscillated around dysoxia. In both examples, the framboids are characterized by wide range of their diameters and the presence of large, >10 "my"m, framboids. On the contrary, the Upper Famennian black shales, representing the Hangenberg event, were deposited below the euxinic conditions in the water column. It is indicated by a high frequency of small-size framboids, far below 6 "my"m in diameter, and the lack of the large ones. The overlying shales, on the other hand, show the transition to more oxic conditions. The redox conditions interpreted above are in agreement with the independent biomarker analyses and paleontological observations.
Źródło:
Przegląd Geologiczny; 2008, 56, 2; 158-164
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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