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Wyszukujesz frazę "humic" wg kryterium: Temat


Wyświetlanie 1-5 z 5
Tytuł:
Ultraweak chemiluminescence from gamma-irradiated humic acids
Autorzy:
Goraczko, W.
Slawinski, J.
Powiązania:
https://bibliotekanauki.pl/articles/147312.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
chemilumiscence
gamma irradiation
humic acid
Opis:
Dried humic acid and its aqueous solution in 0.1 M Na2CO3 were gamma-irradiated with 1 90 kGy from 60Co. Thereafter, a secondary ultraweak radiation in the spectral range of gamma = 340 650 nm from aqueous solutions was recorded as long-lived chemiluminescence (CL). Only for absorbed doses lower than 10 kGy low intensity signals of the CL decay were measurable. For absorbed doses higher than 40 kGy residual flat and weak signals are observed. Humic acid irradiated in the dry form did not reveal statistically significant CL. Absorption spectra (gamma = 240 800 nm) of irradiated solutions indicated the occurrence of a dominant degradation process of the humic acid macromolecular components. The effect of H2O2 and CL enhancers (luminol and lucigenin) on the intensity and kinetics of CL proved the participation of reactive oxygen species and the free radical mechanism in the CL and degradation processes. The dose-effect relationship (i.e. gamma-radiation absorbed dose vs. intensity of gamma-radiation-induced CL) showes a non-linear shape, especially in the range of 1-10 kGy, which suggests complex radical mechanisms. A possible ecological significance of the observed phenomena is briefly discussed.
Źródło:
Nukleonika; 2004, 49, 4; 143-147
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The impact of humic substances on the liposome structures : ESR method
Autorzy:
Man, D.
Pisarek, I.
Braczkowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/147392.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
EYL liposome
ESR method
humic substances
Opis:
In this paper the changes of membrane fluidity of liposome with additions of humic substances (humic and fulvic acids) were examined. Liposome were done by the sonication of lecithin EYL. Concentrations of humic substances in attitude to EYL varied between 0–10% of weight. The technique of electron spin resonance (ESR) were used for the examination followed by three spin probes with a variety placement of the membrane located. TEMPO probe melted in the hydrophobic membrane and in the aquatic solution which allowed to determine the spectroscopic partition parameter (F), indicating the changes that occur in water-lipid interphase. Probe 5-DOXYL placed directly under the heads of polar lipids and the order parameter measuring by the TII showed the changing of membrane fluidity at surface area. 16-DOXYL probe penetrated the middle of the lipid bilayer membrane and allowed to determine the rotational correlation time τ parameter, which gives us information about changing of the liquidity lipid bilayer. Studies showed that the tested humic substances significantly changed the membrane fluidity of liposome. The dynamics of this process depends on both: the fraction of humic substances and its quality and quantity as well as the placement area of the membrane.
Źródło:
Nukleonika; 2013, 58, 3; 439-442
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the radiocesium behavior in a small humic lake (Lithuania)
Autorzy:
Tarasiuk, N.
Moisejenkova, A.
Koviazina, E.
Karpicz, R.
Astrauskiene, N.
Powiązania:
https://bibliotekanauki.pl/articles/148132.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
radiocesium
lake
closed
humic
sediment
tench
Opis:
Peculiarities of radiocesium contamination of a small humic lake, which became meromictic some thirty-five years ago due to the inflow of a large amount of humic water, are presented. The lake consists of two separate water layers, which do not intermix. A lower water layer of the lake below some 3-m depth is stagnant and anaerobic, and radiocesium load of the sediments is mainly caused by nuclear weapons fallout. The radiocesium load of the sediments of the upper monomictic water layer is significantly larger due to additional contamination after the Chernobyl accident. Radiocesium activity concentrations in lake water increase with depth, and even in the surface layer, they are commonly the largest among the neighboring lakes with transparent water. It is shown that bottom areas of the monomictic part of the lake with the elevated radiocesium deepening into sediments are related to the favorite sites of the tench (Tinca tinca) winter torpor. Sediment bioturbation and redistribution due to tench activities distort naturally formed radiocesium vertical profiles and they cannot be used for estimations of sedimentation rates and sediment chronology. The studied lake can be useful as an analogous model in analyzing structural and radiological consequences of humic water inflows to closed lakes. Concerning extreme radiological situations in closed humic lakes related to their specific vertical structure, they may be treated as critical objects in assessing the risk to humans after radionuclide deposition events.
Źródło:
Nukleonika; 2009, 54, 3; 211-220
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of humic acids on EYL liposome membranes : ESR method
Autorzy:
Pytel, B.
Filipiak, A.
Pisarek, I.
Olchawa, R.
Man, D.
Powiązania:
https://bibliotekanauki.pl/articles/146924.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
EYL liposomes
ESR method
humic substances
Opis:
In this paper, the effects of model (commercial) and natural (extracted from peat) humic substances on the membrane of liposomes formed with egg yolk lecithin (EYL) are presented. In our research, mass concentrations of fulvic and humic acids were used, which in relation to lecithin varied from 0% to 13%. To study membrane fluidity, electron spin resonance (EPR) was used with two spin probes, penetrating various regions of the lipid bilayer. The effects of model and natural humic substances (humic acids – HAs and fulvic acids – FAs) on the lipid membrane in different regions were researched: the lipid-water interphase, and in the middle of the lipid bilayer. It was shown that FA and HA impact the fluidity of liposome membranes in different ways. Increased mass concentrations of HAs decreased membrane fluidity in both acids: extracted from peat and the model. However, increased mass concentration of FAs extracted from peat, decreased membrane fluidity in the surface region, at the same time stiffening the central part of the bilayer. Increasing the concentration of FAs extracted from peat had the opposite effect when compared to model FA. This effect may be related to the complexation of xenobiotics present in the soil environment and their impact on biological membranes.
Źródło:
Nukleonika; 2015, 60, No. 3, part 1; 455-459
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model radioisotope experiments on the influence of acid rain on 65Zn binding with humic acid
Autorzy:
Koczorowska, E.
Mieloch, M.
Slawinski, J.
Powiązania:
https://bibliotekanauki.pl/articles/147092.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
acid rain
complexation
humic acid
sulphuric acid
zinc
Opis:
Acid rain formed first of all from sulphur oxide emitted by natural and anthropogenic sources, may change the biological equilibrium and the metal stoppage in the soil. The model experiments were performed to determine the influence of acid rain on zinc bond with humic acid (HA). The samples were prepared in glass columns with quartz sand and overlaid HA or HA+65Zn radioisotope that simulates natural conditions. Then, solutions of H2SO4 were introduced into the sand HA layer. Zinc was washed with diluted (10 4 10 3 M) sulphuric acid as the simulation of acid rain. The recovery of injected radiotracer ions in eluates was found to depend on pH of simulated acid rain. The results help to evaluate the migration behaviour of zinc in the presence of HA and H2SO4. The model studies illustrate the considerable influence of sulphuric acid on chemical degradation of HA.
Źródło:
Nukleonika; 2002, 47, 4; 167-171
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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