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Wyświetlanie 1-15 z 68
Tytuł:
Lycopene as a guardian of redox signalling
Autorzy:
Palozza, Paola
Catalano, Assunta
Simone, Rossella
Cittadini, Achille
Powiązania:
https://bibliotekanauki.pl/articles/1039763.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
ROS
intracellular redox status
redox signal
antioxidant
lycopene
Opis:
It has been suggested that lycopene, the major carotenoid found in tomato, exhibits health-beneficial effects by virtue of its antioxidant activity. However, recent literature suggests that lycopene can actually "perform" roles independent of such capacity and involving a direct modulation of redox signalling. Reactive oxygen species are known to act as second messengers in the modulation of cellular signalling leading to gene expression changes and pharmacological responses. Lycopene may control redox-sensitive molecular targets, affecting enzyme activities and expressions and modulating the activation of MAPKs and transcription factors, such as NF-κB and AP-1, Nrf2.
Źródło:
Acta Biochimica Polonica; 2012, 59, 1; 21-25
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Developmental changes in the levels and redox potentials of main hemolymph thiols/disulfides in the Jamaican field cricket Gryllus assimilis
Autorzy:
Sadowska-Bartosz, Izabela
Furmaniak, Paulina
Bieszczad-Bedrejczuk, Edyta
Bartosz, Grzegorz
Głowacki, Rafał
Powiązania:
https://bibliotekanauki.pl/articles/1038598.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
insect
Gryllus assimilis
hemolymph
glutathione
cysteine
homocysteine
redox potential
redox environment
Opis:
Main thiols and disulfides were determined in the hemolymph of the Jamaican field cricket Gryllus assimilis at various developmental stages. On the basis of these data, redox potentials of the glutathione, cysteine and homocysteine redox systems were calculated. The concentrations of all thiols studied decreased during development (at a stage of 6 molts) with respect to young crickets, and increased again in adult insects. Redox potentials of the glutathione and cysteine systems increased from values of -131.0±5.6 mV and -86.9±17.1 mV, respectively in young crickets to -58.0±3.6 mV and -36.1±4.2 mV, respectively, at the stage of 6 molts and decreased to values of -110.4±24.8 mV and -66.3±12.2 mV, respectively, in adult insects. Redox potentials of the glutathione and cysteine systems in the hemolymph of young and adult insects were similar to those reported for human plasma.
Źródło:
Acta Biochimica Polonica; 2017, 64, 3; 503-506
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Redox changes affect growth and gene expression in maize
Autorzy:
Gulyas, Z.
Boldizsar, A.
Szalai, G.
Kocsy, G.
Galiba, G.
Powiązania:
https://bibliotekanauki.pl/articles/81154.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
conference
redox change
gene expression
maize
root
glutathione level
redox potential
thioredoxin
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:
In vitro inhibition of topoisomerase IIα by reduced glutathione
Autorzy:
Delwar, Zahid
Vita, Marina
Siden, Åke
Cruz, Mabel
Yakisich, Juan
Powiązania:
https://bibliotekanauki.pl/articles/1039933.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
DNA topoisomerases
glutathione
redox regulation
Opis:
In most cells, the major intracellular redox buffer is glutathione (GSH) and its disulfide-oxidized (GSSG) form. The GSH/GSSG system maintains the intracellular redox balance and the essential thiol status of proteins by thiol disulfide exchange. Topoisomerases are thiol proteins and are a target of thiol-reactive substances. In this study, the inhibitory effect of physiological concentration of GSH and GSSG on topoisomerase IIα activity in vitro was investigated. GSH (0-10 mM) inhibited topoisomerase IIα in a concentration-dependent manner while GSSG (1-100 µM) had no significant effect. These findings suggest that the GSH/GSSG system could have a potential in vivo role in regulating topoisomerase IIα activity.
Źródło:
Acta Biochimica Polonica; 2011, 58, 2; 265-267
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Monitoring the Evolution of Redox Changes in Sediments made Possible by Electrochemical Multilayer Probes
Autorzy:
Popa, Radu
Moga, Ioana Corina
Nealson, Kenneth H.
Cimpoiasu, V.M.
Powiązania:
https://bibliotekanauki.pl/articles/2134093.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sensor
sediments
SPEAR
multielectrode
redox interface
Opis:
Marine sediments with rapid oxic/anoxic transitions are difficult to monitor in real time. Organic overload that may lead to anoxia and buildup of hydrogen sulfide can be caused by a variety of factors such as sewage spills, harbor water stagnation, algal blooms and the vicinity of aquaculture operations. We have tested a novel multiprobe technology (named SPEAR) on marine sediments to evaluate its performance in monitoring sediments and overlaying water. Our results show the ability of the SPEAR probes to distinguish electrochemical changes at 2-3 mm scale and at hourly cycles. SPEAR probes have the ability to identify redox interfaces and redox transition zones in sediments, but do not use micromanipulators (which are cumbersome in field and underwater applications). We propose that the best target habitats for SPEAR-type monitoring are rapidly evolving muddy deposits and sediments near aquaculture operations where pollution with organics stresses the ecosystem.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 3; 1037--1041
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of ovalbumin on pyrite flotation in the absence and presence of metal ions
Autorzy:
Guler, T.
Sahbudak, K.
Akdemir, U.
Cetinkaya, S.
Powiązania:
https://bibliotekanauki.pl/articles/110499.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pyrite
ovalbumin
metal ion
flotation
redox potential
Opis:
Recovery of gangue pyrite and its accidental activation are vital issues in flotation of complex sulfide ores. This work was performed by cyclic voltammetry (CV) and flotation tests to elucidate applicability of ovalbumin (OVA) as depressant for pyrite. The synergetic effect of metal ions in addition to its possible use in case of accidental activation by metal ions. CV tests stated that OVA adsorbed irreversibly on pyrite, and restricted electron transfer up to moderately oxidizing potentials due to electrostatic interaction together with weak hydrophobic interactions. At highly oxidizing potentials, adsorption occurred through electrochemical mechanisms through formation of metal-OVA chelates. Rate of pyrite depression with OVA was found to be potential dependent reaching its peak point around moderately oxidizing potentials both in absence and presence of metal ions. Electrochemically active metals display synergetic effect with OVA on pyrite depression, whereas noble metals activate pyrite and reduced depressing potency of OVA.
Źródło:
Physicochemical Problems of Mineral Processing; 2014, 50, 1; 31-40
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soil Redox Potential and its Impact on Microorganisms and Plants of Wetlands
Autorzy:
Tokarz, E.
Urban, D.
Powiązania:
https://bibliotekanauki.pl/articles/125438.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
redox potential
peatland
microbial communities
enzymatic activity
Opis:
Although peatlands cover only 3% of the Earth’s surface, they constitute a huge reservoir of carbon. It is estimated that they accumulate one third of carbon contained in all types of soils worldwide. Therefore, knowledge of the physical, chemical, and biological properties of peat is important for prevention of peat degradation and release of carbon stored as CO2 into the atmosphere. In organic soils, water plays a very important role as a protective factor against mineralisation of organic matter. Therefore, organic soils are characterised by high specificity and dissimilarity from mineral soils. The hydrological factor induces a variety of changes in the physical and chemical properties, e.g. low redox potential or low oxygen content in soil pores. Many soil processes are determined by the soil oxygenation status, which can be measured with various indicators as well as direct and indirect measurements. One of the indirect methods is measurement of the redox potential. The oxidation-reduction potential (redox potential or Eh) is a measure of the ratio of oxidised to reduced forms in a solution. This parameter is inextricably linked to oxygen supply and the processes of consumption thereof by microorganisms and plant roots. Therefore, the redox potential is used as an indicator of the oxygenation status and the content of biogenic forms and toxins in the soil environment and sediments. In the case of submerged soils, penetration of atmospheric oxygen into the soil is limited due to low rates of oxygen diffusion and, hence, low redox potential, which inhibits plant growth through inhibition of respiration and production of toxins in reducing conditions. The aim of this article is (1) to the show soil-plant-soil microorganism interactions taking place on peatbogs in the context of redox potential, (2) to investigate the responses of plants and soil microorganisms to the changing redox potential, and (3) to demonstrate the mechanisms of plant adaptation to the reducing conditions prevailing in peatbogs.
Źródło:
Journal of Ecological Engineering; 2015, 16, 3; 20-30
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metabolic parameters in young turkeys fed diets with different inclusion levels of copper nanoparticles
Autorzy:
Kozłowski, K.
Jankowski, J.
Otowski, K.
Zduńczyk, Z.
Ognik, K.
Powiązania:
https://bibliotekanauki.pl/articles/2087738.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nano-copper
turkey
blood
liver
redox status
Źródło:
Polish Journal of Veterinary Sciences; 2018, 21, 2; 245-253
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of citrus flavanones on the redox homeostasis in cells exposed to oxidative stress – studies in vitro
Wpływ flawanonów cytrusowych na homeostazę redoks komórek narażonych na stres oksydacyjny – badania in vitro
Autorzy:
Kurzeja, Ewa
Synowiec-Wojtarowicz, Agnieszka
Spiołek, Katarzyna
Derewniuk, Małgorzata
Pawłowska-Góral, Katarzyna
Powiązania:
https://bibliotekanauki.pl/articles/1035565.pdf
Data publikacji:
2016
Wydawca:
Instytut Medycyny Wsi
Tematy:
"cell culture"
"flavanones"
"oxidative stress"
"redox homeostasis"
Opis:
Introduction: Flavanones (an important group of antioxidants in citrus fruits) are beneficial for health, which is connected with their anti-inflammatory, anti-atherogenic and anti-carcinogenic properties. The present study was undertaken to investigate whether – and in what way – the presence of flavanones influences the redox homeostasis of fibroblasts and alleviates the effects of oxidative stress. Material and methods: The study was conducted on murine fibroblast cell cultures with the addition of flavanones (hesperidin, hesperetin, naringin, naringenin), exposed to oxidative stress (Fe/Asc). In cell homogenates, the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx) was measured; in the medium, the concentration of nitric oxide was measured. Results and conclusion: Our results demonstrate that the addition of naringenin, hesperetin, naringin and hesperidin has a protective effect on cells subjected to oxidative stress The changes observed are particularly visible in the case of aglycone forms of both compounds. Despite the protective properties against oxidative stress which flavanones display, we determined distrubances in redox homeostasis in comparison to the control culture.
Wstęp: Flawanony, będące głównymi związkami bioaktywnymi cytrusów, wykazują działanie prozdrowotne, co wynika z ich właściwości przeciwzapalnych, przeciwmiażdżycowych i przeciwnowotworowych. Celem badania była ocena wpływu flawanonów na homeostazę redoks fibroblastów oraz czy ich obecność łagodzi skutki stresu oksydacyjnego. Materiały i metody: Badanie przeprowadzono na hodowlach mysich fibroblastów z dodatkiem flawanonów (hesperydyna, hesperetyna, naringina, naringenina) poddanych stresowi oksydacyjnemu (Fe/Asc). W homogenatach komórkowych oznaczono aktywność dysmutazy ponadtlenkowej (SOD) i peroksydazy glutationowej (GPx), a bezpośrednio w pożywce stężenie tlenku azotu. Wyniki i wnioski: Wyniki naszej pracy wskazują, że dodatek naringeniny, hesperetyny, naringiny i hesperydyny działa ochronnie na komórki poddane stresowi oksydacyjnemu. Pomimo stwierdzonego ochronnego działania flawanonów zaobserwowaliśmy również zaburzenie homeostazy redoks w odniesieniu do hodowli kontrolnej.
Źródło:
Medycyna Środowiskowa - Environmental Medicine; 2016, 19, 2; 32-39
1505-7054
2084-6312
Pojawia się w:
Medycyna Środowiskowa - Environmental Medicine
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:
Constraints of the MAX4781 CMOS Solution for Electrode Switching in Multilayer Electrochemical Probes
Autorzy:
Cimpoiasu, V.M.
Radulescu, F.
Nealson, K.H.
Moga, Ioana Corina
Popa, R.
Powiązania:
https://bibliotekanauki.pl/articles/2106598.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sensor
SPEAR
multielectrode
redox interface
sediments
electrochemical gradients
Opis:
The most common means to analyze redox gradients in sediments is by push/pulling electrochemical probes through sediment’ strata while repeating measurements. Yet, as electrodes move up and down they disrupt the texture of the sediment layers thus biasing subsequent measurements. This makes it difficult to obtain reproducible measurements or to study the evolution of electrochemical gradients. One solution for solving this problem is to eliminate actuators and electrode movements altogether, while instead deploying probes with numerous electrodes positioned at various depths in the sediment. This mode of operation requires electrode switching. We discuss an electrode-switching solution for multi-electrode probes, based on Complementary Metal-Oxide-Semiconductor (CMOS) multiplexors. In this solution, electrodes can be individually activated in any order, sequence or time frame through digital software commands. We discuss constraints of CMOS-based multilayer electrochemical probes during cyclic voltammetry.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 2; 691--694
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Interactions of dietary carotenoids with singlet oxygen (1O2) and free radicals: potential effects for human health
Autorzy:
Böhm, Fritz
Edge, Ruth
Truscott, T
Powiązania:
https://bibliotekanauki.pl/articles/1039764.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
dietary carotenoids
singlet oxygen
free radicals
redox potentials
Opis:
The dietary carotenoids provide photoprotection to photosynthetic organisms, the eye and the skin. The protection mechanisms involve both quenching of singlet oxygen and of damaging free radicals. The mechanisms for singlet oxygen quenching and protection against free radicals are quite different - indeed, under some conditions, quenching of free radicals can lead to a switch from a beneficial anti-oxidant process to damaging pro-oxidative situation. Furthermore, while skin protection involves β-carotene or lycopene from a tomato-rich diet, protection of the macula involves the hydroxyl-carotenoids (xanthophylls) zeaxanthin and lutein. Time resolved studies of singlet oxygen and free radicals and their interaction with carotenoids via pulsed laser and fast electron spectroscopy (pulse radiolysis) and the possible involvement of amino acids are discussed and used to (1) speculate on the anti- and pro-oxidative mechanisms, (2) determine the most efficient singlet oxygen quencher and (3) demonstrate the benefits to photoprotection of the eye from the xanthophylls rather than from hydrocarbon carotenoids such as β-carotene.
Źródło:
Acta Biochimica Polonica; 2012, 59, 1; 27-30
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The key role of the redox status in regulation of metabolism in photosynthesizing organisms
Autorzy:
Kornas, Andrzej
Kuźniak, Elżbieta
Ślesak, Ireneusz
Miszalski, Zbigniew
Powiązania:
https://bibliotekanauki.pl/articles/1040395.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
evolution
chloroplast
ROS
redox status
photosynthesis
hydrogen peroxide
Opis:
The redox status of the cell is described by the ratio of reduced to non-reduced compounds. Redox reactions which determine the redox state are an essential feature of all living beings on Earth. However, the first life forms evolved under strongly anoxic conditions of the young Earth, and the redox status probably was based on iron and sulphur compounds. Nowadays, redox reactions in cells have developed in strict connection to molecular oxygen and its derivatives i.e. reactive oxygen species (ROS). Oxygen has started to accumulate on the Earth due to oxygenic photosynthesis. All aspects of aerobic life involve ROS, reactive nitrogen species (RNS), antioxidants and redox regulation. Many different redox-active compounds are involved in the complex of redox processes, including pyridine nucleotides, thioredoxins, glutaredoxins and other thiol/disulphide-containing proteins. Redox regulation is integrated with the redox-reactions in photosynthesis and respiration to achieve an overall energy balance and to maintain a reduced state necessary for the biosynthetic pathways that are reductive in nature. It underlies the physiological and developmental flexibility in plant response to environmental signals.
Źródło:
Acta Biochimica Polonica; 2010, 57, 2; 143-151
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
XAFS in the tracking of reactions in aqueous solution: a case of redox reaction between [AuCl4]- complex ions and ethanol
Metoda XAFS w badaniach reakcji zachodzących w roztworach wodnych: przykład reakcji redoks pomiędzy jonami kompleksowymi [AuCl4]- i alkoholem etylowym
Autorzy:
Pacławski, K.
Sikora, M.
Powiązania:
https://bibliotekanauki.pl/articles/355830.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
XAFS
XANES
redox reaction
gold complex ions
ethanol
Opis:
In this work the potential application of synchrotron radiation in the studies of reaction kinetics in aqueous phase were presented. After short introduction describing principles of technique and potential application of XAFS for the structural studies of reacting species, the experimental results of kinetic measurements of reaction between gold(III) chloride complex ions and ethanol were presented. Analyzing the changes of absorption intensity in the XANES spectra registered at Au-L &sub3; edge during the reaction, the change of the valence state of Au central atom (form 3+to 0) of reacting complex ion was determined. Moreover, empirical XANES data gave the chance to register the kinetic curve and to determine the rate constant of the studied reaction. It was found that reaction is relatively slow (second-order rate constant k = 3.66 · 10 &sup-5; M ;sup-1;s) and lead to the gold metallic phase formation in the system. Applying the continuous-flow method, within the first 600 ms of reaction the changes in XANES spectra were registered. From the obtained results, supported with numerical calculations, two intermediate forms of adducts appearing prior the electron transfer were suggested. It was concluded that when the classic methods, e.g. UV-Vis spectrophotometry, cannot be applied to studies of kinetics of reactions in aqueous solution, the XAFS technique can be a valuable and substitutive (or supplementary) tool for such measurements.
W pracy przedstawiono potencjalne możliwości zastosowania promieniowania synchrotronowego w badaniach nad kinetyka reakcji przebiegających w roztworach wodnych. We wstępie, omówiono podstawy techniki rentgenowskiej analizy struktury nadsubtelnej (XAFS) i jej możliwości zastosowania w badaniach strukturalnych związków chemicznych w fazie ciekłej. Zaprezentowano również dane eksperymentalne z pomiarów XAFS dotyczące kinetyki reakcji pomiędzy chlorkowymi kompleksami złota(III) i alkoholem etylowym. Z analizy zmian intensywności absorpcji widm XANES rejestrowanych przy krawędzi L &sub3; złota określono zmianę stopnia utlenienia atomu centralnego Au (z 3+ do 0) reagującego kompleksu. Ponadto, dane empiryczne pozwoliły na wyznaczenie krzywej kinetycznej oraz określenie drugorzędowej wartości stałej szybkości reakcji (k = 3.66 ·10 &sup-5; M &sup-1;s). W wyniku analizy widm XANES potwierdzono powstawanie faza metalicznej złota w układzie. Stosując metodę ciągłego przepływu reagentów, zarejestrowano zmiany w widmie XANES w ciągu 600 ms od rozpoczęcia reakcji.Na podstawie zarejestrowanych widm oraz przeprowadzonych obliczeń numerycznych zasugerowano dwie możliwe struktury adduktu tworzącego się przed właściwym transferem elektronu w reakcji redoks. Z przeprowadzonych eksperymentów wynika, ze w układach, w których nie jest możliwe stosowanie spektrofotometrii UV-Vis, metoda XAFS może być zastępczym i obiecującym narzędziem do badań kinetyki reakcji.
Źródło:
Archives of Metallurgy and Materials; 2012, 57, 4; 1011-1020
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
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