Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "Gamma Irradiation" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 29
Tytuł:
Effect of gamma irradiation on plants in interaction with arbuscular mycorrhizae
Autorzy:
Ene, M.
Trandafir, L.
Alexandru, M.
Powiązania:
https://bibliotekanauki.pl/articles/148043.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
tomato
mutant
gamma irradiation
mycorrhiza defective
Opis:
Arbuscular mycorrhizae are endogenous fungi that form symbiotic association with the vast majority of vascular plants. They help to increase the nutrient uptake, especially phosphorus and to exploit a larger area of soil. Also, they improve soil aggregation, contribute to nutrient cycling processes in plants and improve their tolerance of heavy metal contamination or drought, as well as their susceptibility to root pathogens or herbivores. These fungi colonize the root epidermis and outer cortical layers and release bioactive molecules. The transcriptome and the proteome of plants are substantially altered. They have evolved multiple mechanisms that result in improvements in plant resistance to disease and plant growth and productivity, being included in a lot of combination of biofertilizers. In order to study these mechanisms, gamma irradiation was used to create mutants that are defective in their association. Culture under in vitro conditions is presented as method for maintaining the useful mutants in pure line.
Źródło:
Nukleonika; 2009, 54, 2; 89-92
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Effect of steaming, microwave treatment and gamma-irradioation on rapeseed microstructure
Wpływ parowania, mikrofal i promieniowania na mikrostrukturę nasion rzepaku
Autorzy:
Fornal, J.
Jousselin-Hosaja, M.
Kozłowska, H.
Powiązania:
https://bibliotekanauki.pl/articles/1399000.pdf
Data publikacji:
1987
Wydawca:
Instytut Rozrodu Zwierząt i Badań Żywności Polskiej Akademii Nauk w Olsztynie
Tematy:
electron microscopy
rapeseed
steaming
gamma-irradiation
microwaves
Opis:
Structural changes in rapeseed following hydrothermal treatment are reported . SEM and TEM micrographs revealed significant changes in the seed microstructure. It was found that the intensity of these changes depends on the kind of treatment.
W prezentowanej pracy przedstawiono wyniki badań zmian mikrostruktury nasion rzepaku poddanych wybranym procesom mającym na celu inaktywację enzymu tioglukozydazy. Za pomocą skaningowego i transmisyjnego mikroskopu elektronowego wykazano zróżnicowany wpływ tych procesów na podstawowe składniki chemiczne nasion rzepaku - białko i tłuszcz. W kontrolnych nasionach rzepaku odmiany Skrzeszowicki zaobserwowano wy stępowanie dwóch typów ciał białkowych. Różniły się one głównie wielkością i rodzajem powierzchni (fot. 1-3). Wysunięto przypuszczenie, że ciała te mogą mieć znaczenie w lokalizacji tzw. ,,bomby olejku gorczycznego". Wykazano, że parowanie nasion w warstwie fluidalnej oraz działanie mikrofal powodują praktycznie identyczne zmiany mikrostruktury. Przejawiają się one w silnej denaturacji ciał białkowych, gromadzeniu się masy białkowe j w centralnej części komórki, a tłuszczu w pobliżu ścian komórkowych (fot. 4-7). Zastosowanie promieniowania γ spowodowało jedynie nieznaczną denaturację ciał białkowych, a także miało minimalny wpływ na zanik membran wokół kropel tłuszczu (fot. 8 i 9).
Źródło:
Acta Alimentaria Polonica; 1987, 13, 4; 299-308
0137-1495
Pojawia się w:
Acta Alimentaria Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of hydroperoxides in aqueous solutions containing surfactants by the ferrous oxidation-xylenol orange method
Autorzy:
Meisner, Piotr
Gębicki, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/1040551.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
surfactants
FOX method
hydroperoxides
gamma-irradiation
Opis:
Some surfactants widely used as additives in food, pharmaceuticals, and cosmetic formulations are susceptible to peroxidation resulting in accumulation of hydroperoxides (HP). Our investigation was aimed to study the possible influence of different surfactants on the proportionality and reproducibility of the ferrous oxidation-xylenol orange method developed originally for the determination of hydroperoxides. We also attempted to apply this method to determine hydroperoxides produced radiolytically in surfactant molecules. From our preliminary studies we conclude that the method can be applied for determination of hydroperoxides in systems containing non-ionic or anionic surfactants provided careful calibration is performed for each surfactant.
Źródło:
Acta Biochimica Polonica; 2009, 56, 3; 523-527
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Archives decontamination by gamma irradiation
Autorzy:
Bratu, E.
Moise, I. V.
Cutrubinis, M.
Virgolici, M.
Powiązania:
https://bibliotekanauki.pl/articles/148039.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
decontaminatio
archives
gamma irradiation
treatment
tests
Opis:
The treatment of archives with gamma irradiation is an efficient and environmental friendly alternative for biological decontamination of large volume of archives. It substitutes the use of chemicals for conservation and contributes to safer workplaces. This work is targeting documents from recent archives where the value of information is not obsolete and may become an important historical and cultural testimony. For a successful treatment, an optimal absorbed dose has to be established. An excessive dose may damage papers and an insufficient one will not reduce bioburden to the desired level. An interdisciplinary team was performing various physical and chemical tests in order to evaluate deterioration of paper at high doses. In the case of natural disaster, it is not excluded the “emergency” treatment for documents in immediate danger of total destruction.
Źródło:
Nukleonika; 2009, 54, 2; 77-84
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degradation and detoxifi cation of 2-chlorophenol aqueous solutions using ionizing gamma radiation
Autorzy:
Basfar, A. A.
Muneer, M.
Alsager, O. A.
Powiązania:
https://bibliotekanauki.pl/articles/148378.pdf
Data publikacji:
2017
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
2-chlorophenol
degradation
detoxification
gamma irradiation
aqueous solution
Opis:
Chlorophenols are compounds with high toxicity, poor biodegradability, and carcinogenic and recalcitrant properties. This work studies, for the first time, the destruction and detoxification of 2-chlorophenol (2-CP) in water using 60Co gamma radiation under different conditions including varied radiation doses, addition of hydrogen peroxide (H2O2), and varied pH values. High-performance liquid chromatography (HPLC) and ion chromatography (IC) confirmed a successful degradation of 2-CP to primarily yield phenol molecules and chloride anions. A radiation dose as low as 25 kGy achieved approximately 90% removal of 50–150 ppm of 2-CP in neutral water. However, the addition of a strong oxidizer such as H2O2 to 2-CP solutions reduced the required dose to achieve 90% removal to at least 1.3-fold. The reduction in radiation doses was also observed in acidic and alkaline media, reducing the required doses of 90% removal to at least 0.4-fold. It was imperative to study the toxicity levels of the oxidation by-products to provide directions for the potential applicability of this technology in water treatment. Toxicology Microtox® bioassay indicated a significant reduction in the toxicity of the degradation by-products and the detoxification was further enhanced by the addition of H2O2 and changing the pH to more acidic or alkaline conditions. These findings will contribute to the knowledge of the removal and detoxification of such challenging environmental contaminant and could be potentially applied to other biologically resistant compounds.
Źródło:
Nukleonika; 2017, 62, 1; 61-68
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gamma irradiation used on adult Tetranychus urticae Koch as a quarantine treatment
Autorzy:
Osouli, S.
Nejad, K.H.I.
Ziaie, F.
Moghaddam, M.
Powiązania:
https://bibliotekanauki.pl/articles/65503.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gamma-irradiation
adult
Tetranychus urticae
quarantine treatment
sterility
Opis:
The effect of gamma radiation with 0, 200, 250, 300, 350, 400, and 450 Gy intensities on the longevity, total number of eggs, and the percent of hatched eggs laid by irradiated females of Tetranychus urticae Koch (Tetranychidae) was evaluated. Two different groups (0–24 h old and 48–72 h old) of adult females were irradiated. The results showed that 350 and 300 Gy doses significantly reduced the longevity of the 0–24 h old females and the 48–72 h old females. The younger females were more tolerant at lower dose rates than the older females. There was a quadratic relationship between dose rates and young females, while it was linear in older females. The total number of eggs laid by females of both ages was significantly reduced with a linear trend by 250 Gy irradiation. The eggs laid by females of both the 0–24 h olds and the 48–72 h olds lost their hatchability when the dose rate was 350 Gy. It was concluded, that applying a dose rate of 320 Gy on one of the mates (male or female) before mating, or a 300 Gy on both of them, would be sufficient to cause sterility in adult mites.
Źródło:
Journal of Plant Protection Research; 2014, 54, 2
1427-4345
Pojawia się w:
Journal of Plant Protection Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evidence of Stress Recovery in Free-Living Ciliate Colpoda cucullus: The Repair Capability of Resting Cysts to Damage Caused by Gamma Irradiation
Autorzy:
Sogame, Yoichiro
Saito, Ryota
Koizumi, Ryota
Shimizu, Taiga
Ono, Taiki
Powiązania:
https://bibliotekanauki.pl/articles/52073946.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
Tematy:
Stress recovery
Colpoda
Cryptobiosis
Resting cyst
Gamma irradiation
Opis:
In this study, we report that the unicellular free-living protist Colpoda cucullus in the resting cyst (cryptobiosis) repairs stress damage. We previously demonstrated that resting cysts of Colpoda cucullus have extreme tolerance to gamma irradiation and can revert to vegetative cells after irradiation. Such irradiated cysts gradually excyst, suggesting that stress repair mechanisms are active during excystment or in the resting cyst. Herein we provide bioassay evidence that the rate of excystment of irradiated cysts is elevated by subsequent incubation, thereby indicating that cells injured by gamma irradiation can repair themselves in the resting cyst, whereas irradiated dry cysts cannot.
Źródło:
Acta Protozoologica; 2019, 58, 1; 25-29
0065-1583
1689-0027
Pojawia się w:
Acta Protozoologica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The use of gamma irradiation to stimulate bioactive compound synthesis in Inonotus obliquus submerged cultures
Autorzy:
Petre, Alexandru
Ene, Mihaela
Negut, Daniel Constantin
Gatea, Florentina
Vamanu, Emanuel
Powiązania:
https://bibliotekanauki.pl/articles/2055677.pdf
Data publikacji:
2021
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
gamma irradiation
Chaga
medicinal fungi
metabolite synthesis
bioactive compounds
Opis:
Inonotus obliquus is a parasite on the birch and other trees and is also a well-known medicinal mushroom. Its sterile conk is highly sought for its bioactive compounds such as phenols, polysaccharides, triterpenoids, and steroids. It was traditionally used to treat various gastrointestinal diseases, viral and parasitic infections, to counteract the progression of cancers, and to stimulate the immune system. We used acute gamma irradiation, followed by short-term submerged cultivation, as an oxidative stress inducer to enhance the synthesis of mycelial metabolites. The 300 Gy and 400 Gy doses showed the best results across the whole experimental design. Each assayed criterion had a different corresponding optimal stimulation dose. In one experiment, sublethal doses of irradiation triggered the dry weight of the cultured mycelium to increase by 19.764%. The free radical scavenging potential of the mycelium extracts increased by 79.83%. The total phenolic content of mycelium extracts and culture broth increased by 55.7% and 62.987%, respectively. The total flavonoid and sinapinic acid content of the broth increased by 934.678% and 590.395%, respectively. As such, gamma irradiation pretreatment of the mycelial inoculum proved an interesting, economically and environmentally effective tool for stimulating secondary metabolite synthesis in submerged mycelium cultures.
Źródło:
Nukleonika; 2021, 66, 3; 83--90
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of gamma irradiation on microbiological and nutritional properties of the freeze-dried berries
Autorzy:
Mašić, Slobodan
Vujčić, Ivica
Powiązania:
https://bibliotekanauki.pl/articles/2055687.pdf
Data publikacji:
2021
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
freeze-drying
gamma irradiation
lyophilization
microbiological properties
nutritional properties
Opis:
Lyophilization or freeze-drying is the technique of removing ice or other frozen solvents from a material through sublimation and the removal of bound water molecules through the process of desorption. Drying occurs in an absolute vacuum at temperatures from –40°C to –50°C. This technique is often used for the conservation of fruits, especially berries. During this process, the water changes from frozen to gaseous, with no thawing. Due to low temperatures and the high vacuum, most microorganisms are rendered inactive during the lyophilization process. However, ifthere is a necessity to destroy all microorganisms from treated food, subsequent irradiation with gamma rays is an appropriate method. This paper investigated the influence of different doses of gamma radiation on lyophilized berries’ microbiological characteristics. It was shown that the radiation dose of 7 kGy is suffi cient to eliminate the total number of microorganisms (excluding molds) to the extent that the number falls below the permitted limit according t o the law on the microbiological safety of foodstuffs of the Republic of Serbia, and 5 kGy is enough for molds to be rendered inactive. It was also concluded that gamma irradiation does not affect the nutritional value of lyophilized berries.
Źródło:
Nukleonika; 2021, 66, 4; 221--225
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gamma-induced grafting of rice straw cellulose with polyvinylpyrrolidone
Indukowane promieniowaniem gamma szczepienie celulozy ze słomy ryżowej poliwinylopirolidonem
Autorzy:
Suhartini, Meri
Tachrim, Zetryana Puteri
Anggarini, Niken Hayudanti
Rahmawati, Rahmawati
Prasetyani, Amanda
Melawati, June
Deswita
Sugeng, Bambang
Powiązania:
https://bibliotekanauki.pl/articles/2202631.pdf
Data publikacji:
2022
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
cellulose
polyvinylpyrrolidone
gamma irradiation
graft copolymerizatio
celuloza
poliwinylopirolidon
promieniowanie gamma
kopolimeryzacja szczepiona
Opis:
Cellulose obtained from rice straw was grafted with polyvinylpyrrolidone (Cell-g-PVP). The process was induced by gamma simultaneous irradiation (Co-60). The presence of the grafted PVP chains was confirmed by FT-IR, XRD and EDS methods. The influence of the irradiation dose (20 and 30 kGy) on the reaction efficiency and thermal stability of Cell-g-PVP was investigated. The grafting yield at the dose of 30 kGy was about 56%. The higher dose of radiation resulted in better thermal stability. The AAS results showed that Ni(II), Cu(II), and Cr(II) ions can be adsorbed by Cell-g-PVP. The order of ion metals adsorption capacity of Cell-g-PVP was Cu(II) > Ni(II) > Cr(II). The adsorption isotherm of Cu(II) metal ion using the Cell-g-PVP followed the Langmuir adsorption isotherm whereas the chemical adsorption and the adsorption energy were constant on all sides of the copolymer.
Celulozę otrzymaną ze słomy ryżowej poddano szczepieniu poliwinylopirolidonem (Cell-g-PVP). Proces indukowano promieniowaniem gamma (Co-60). Obecność zaszczepionych łańcuchów PVP potwierdzono metodami FT-IR, XRD i EDS. Zbadano wpływ wielkości dawki promieniowania (20 i 30 kGy) na wydajność reakcji istabilność termiczną Cell-g-PVP. Stopień zaszczepienia przy dawce 30 kGy wynosił ok. 56%. Większa dawka promieniowania skutkowała większą stabilnością termiczną. Metodą AAS oceniono właściwości adsorpcyjne Cell-g-PVP względem jonów Ni(II), Cu(II) i Cr(II). Zdolność do adsorpcji zmniejszała się w szeregu Cu(II) > Ni(II) > Cr(II). Izoterma adsorpcji jonów Cu(II) miała przebieg zgodny z izotermą adsorpcji Langmuira.
Źródło:
Polimery; 2022, 67, 9; 450--456
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of gamma-irradiation on aqueous solutions of Apollofix dyes
Autorzy:
Solpan, D.
Torun, M.
Güven, O.
Powiązania:
https://bibliotekanauki.pl/articles/147642.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
gamma irradiation
Apollofix dyes
decoloration
organic pollutants degradation
wastewater treatment
Opis:
Radiation processing has been considered as a promising process for the treatment of textile industry waste effluents. In this study, the possibility of using gamma-rays to degrade and decolorize Apollofix dyes in water has been investigated. Two different Apollofix dyes, Apollofix Red (AR) and Apollofix Yellow (AY) in aqueous solutions were irradiated in air with doses from 1.0 kGy to 8.0 kGy at a 0.14 kGy/h of dose rate. The change in absorption spectra, pH, chemical oxygen demand (COD), biological oxygen demand (BOD) and the degree of decoloration (percent reduction in optical density) were examined in the presence and absence of H2O2. The absorption bands at 534 nm and 420 nm for AR and AY were observed to decrease rapidly with increasing irradiation dose. The degree of decoloration of each dye solution with irradiation dose was estimated as 100 percent for the lower concentration (50 ppm) dye solutions. The complete decoloration was observed after 2.0 kGy and 1.0 kGy doses for AR and AY dyes. The COD and BOD reduction and the change of pH for all dye solutions on irradiation showed similar behavior.
Źródło:
Nukleonika; 2007, 52, 3; 109-113
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Excitation Functions of Longer and Shorter Lived Radionuclides
Autorzy:
Noori, S.
Akkurt, İ.
Demir, N.
Powiązania:
https://bibliotekanauki.pl/articles/1031916.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
Radionuclides
Gamma Irradiation
TALYS 1.6 nuclear reaction simulation code
Opis:
Nuclear reactions, which are very important from the point of view of human health, may occur during the production of the radiation sources, used in radiotherapy. The nuclear reaction data are needed in the radioisotope production procedure. The total cross section is also important in accelerator technology, in view of radiation protection and safety. In general, the significance of the cross section data for nuclear reactions in radionuclide production programs is firmly established. Gamma irradiation tracers can offer a large amount of information about the anatomy of different organs in the human body. The main purpose of this work was to compare the cross section of longer-shorter lived radionuclides. Theoretical excitation functions have been calculated with TALYS 1.6 nuclear reaction simulation code. The calculated results have been discussed and compared with the experimental data.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 1186-1188
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies of colored varieties of Brazilian quartz produced by gamma radiation
Autorzy:
Enokihara, Cyro T.
Schultz-Güttler, Rainer A.
R. Rela, Paulo
Calvo, Wilson A. P.
Powiązania:
https://bibliotekanauki.pl/articles/971525.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
gemstone treatment
quartz color enhancements
color centers
quartz gamma irradiation
Opis:
Quartz occurs in Brazil mainly in two geological environments, called pegmatitic and hydrothermal. The quartz of hydrothermal origin occurs mainly in geodes in the basaltic rocks of the Parana Basin and the quartz formed in fracture systems of the Espinhaço Range. Quartz of pegmatitic origin forms often the core of pegmatites. The detailed mechanism of color center formation of these two types of quartz will be investigated by spectroscopic and chemical analysis. Until yet, it can be shown that due to chemical differences of the nature of mineral forming fluids, the two types behave differently. All quartz contains mainly traces of iron, aluminum, lithium and some amounts of water. The quartz of hydrothermal origin incorporated much structurally bound water, and despite some similarities with the chemical composition of pegmatitic quartz, this high water content is the reason for the formation of silanol radicals, giving green color to the quartz. The main difference in chemical composition of pegmatitic quartz is the presence of higher amounts of Al and Li, responsible for the brownish and yellowish colors formed by irradiation.
Źródło:
Nukleonika; 2013, 58, 4; 469-474
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron paramagnetic resonance studies on silver atoms and clusters in regularly interstratified clay minerals
Autorzy:
Yamada, H.
Sadlo, J.
Tamura, K.
Shimomura, S.
Turek, J.
Michalik, J.
Powiązania:
https://bibliotekanauki.pl/articles/147360.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
EPR spectroscopy
regularly interstratified clay minerals
silver atoms
gamma irradiation
Opis:
The formation and stabilization of reduced silver species in the regularly interstratified clay minerals, trioctahedral smectite/chlorite (tri-Sm/Ch) and dioctahedral smectite/mica (di-Sm/M), have been studied by electron paramagnetic resonance (EPR) spectroscopy. Both minerals loaded with Ag+ cations after degassing and dehydration were g-irradiated at 77 K and monitored by EPR as the temperature increased. Some samples were exposed to water or methanol vapor after dehydration. In both hydrated and dehydrated samples only the doublets assigned to Ag0 atoms were observed with no evidence of the formation of Ag clusters. However, the EPR parameters of silver atoms in both matrices are different. In tri-Sm/Ch the narrow anisotropic EPR lines overlap with the broader isotropic lines, whereas in di-Sm/M only broad lines are recorded. The hyperfine splitting - Aiso(Ag0) is larger in tri-Sm/Ch than in di-Sm/M. Also the stability of Ag0 in both clay minerals is distinctly different. Ag0 doublet in di-Sm/M disappears completely above 230 K, whereas in tri-Sm/Ch it is still recorded at 310 K. It is proposed, basing on the EPR results that Ag0 atoms appear at different sites in both matrices: - in tri-Sm/Ch in the middle of smectite interlayer and in hexagonal cavities in the silicate sheets of tetrahedron layer and in di-Sm/M in hexagonal cavities only. When samples had been exposed to methanol before irradiation, the silver clusters become stabilized in the interlayer sites. In tri- Sm/Ch matrix the silver dimer Ag2+ formed by g-irradiation at 77 K is transformed to tetrameric cluster, Ag43+ at 150 K. In di-Sm/M the radiation-induced silver agglomeration proceeds in a similar way, but with a slower rate and Ag tetramer is formed only above 190 K. In both clay minerals, Ag43+ clusters decay above 250 K.
Źródło:
Nukleonika; 2004, 49, 4; 131-136
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 29

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies