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Wyszukujesz frazę "positron lifetime spectroscopy" wg kryterium: Wszystkie pola

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    Wyświetlanie 1-6 z 6
    Tytuł:
    Positron annihilation lifetime spectroscopy study of roller burnished magnesium alloy
    Autorzy:
    Zaleski, R.
    Zaleski, K.
    Gorgol, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/146650.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    AZ91HP magnesium alloy
    defects
    positron lifetime annihilation spectroscopy (PALS)
    roller burnishing
    Vickers hardness test
    Opis:
    The effect of roller burnishing on Vickers’ hardness and positron lifetimes in the AZ91HP magnesium alloy was studied. The microhardness increases with an increase in the burnishing force and with a decrease in the feed. The comparison of various methods of analysis of positron annihilation lifetime (PAL) spectra allowed identification of two components, which are related to solute-vacancy complexes and vacancy clusters, respectively. It was found that the increase in microhardness was related to the increase in the concentration of vacancy clusters.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 789-794
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gas filling of SBA - 15 silica micropores probed by positron annihilation lifetime spectroscopy (PALS)
    Autorzy:
    Gorgol, M.
    Zaleski, R.
    Kierys, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/147961.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    SBA-15 porous silica
    positron annihilation
    Opis:
    Positron annihilation lifetime measurements were conducted in situ while two gasses (nitrogen and oxygen, respectively) were introduced into the SBA-15 porous silica sample. Slow changes in lifetime spectra were observed during a long lasting gas interaction with the sample. Introduced gases slowly filled the free volumes, starting from the smallest ones, especially small micropores. In the presence of a gas, the rate of change of ortho-positronium (o-Ps) and unbound positron intensity was larger than the rate of change of lifetime. This suggests the existence of an additional process, which reduces the number of ortho-positronium atoms due to the interaction with the gas. Moreover, the process of filling pores with gas was slower than the process of emptying them while the gas was pumped out.
    Źródło:
    Nukleonika; 2013, 58, 1; 229-233
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation lifetime spectroscopy study of thermal processing and rehydration of dry leek (Allium porrum L.)
    Autorzy:
    Zaleski, R.
    Wawryszczuk, J.
    Sobczak, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/146309.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    lifetime spectroscopy
    food processing
    rehydration
    leek (Allium porrum L.)
    Opis:
    New application of positron annihilation lifetime spectroscopy (PALS) to development of food processing techniques is tested. Dehydrated leeks were an object of the study. Three experiments were performed consisting of evacuating air and volatile compounds from the sample, applying thermal treatment and rehydrating the sample. Distinct changes in positron lifetime spectra allowed the monitoring of alterations in the sample structure. The most likely origin of the particular components present in the spectra was able to be proposed from these data. Changes of the components were ascribed to the various processes occurring in the samples.
    Źródło:
    Nukleonika; 2010, 55, 1; 73-78
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Principles of positron porosimetry
    Autorzy:
    Zaleski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/146520.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    porous materials
    positron annihilation lifetime spectroscopy (PALS)
    positronium
    extended Tao-Eldrup model
    Opis:
    The paper deals with positron porosimetry (PP), which is based on positron annihilation lifetime spectroscopy (PALS). The numerical analysis of positron lifetime spectra for PP is more demanding than in most of other applications of PALS. The resulting intensity distributions of ortho-positronium (o-Ps) lifetimes are interpreted in terms of the extended Tao-Eldrup (ETE) model, which provides the dependence between the o-Ps lifetime and pore size. Additionally, the relation between the intensity of an o-Ps component and the pore volume allows obtaining pore size distribution (PSD). The value of the empirical parameter Δ, which is dependent on material, can be estimated from the temperature dependence of an o-Ps lifetime. The most unique feature of PP among other techniques that allow determination of PSDs is its ability to perform measurements in almost any conditions. This makes this method suitable for various in situ studies. In this review article, both the capabilities and the limitations of PP are discussed. The methods to overcome some of the limitations are presented.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 795-800
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ortho-positronium migration in mesopores of MCM-41, MSF and SBA-3
    Autorzy:
    Zaleski, R.
    Błażewicz, A.
    Kierys, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/147955.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    nitrogen adsorption/desorption
    porous materials
    positron annihilation lifetime spectroscopy (PALS)
    positronium migration
    Opis:
    Three materials: MCM-41, MSF and SBA-3 with a very similar pore diameter but different lengths of cylindrical pores were investigated using the nitrogen sorption method and positron annihilation lifetime spectroscopy. The size of primary pores and interparticle spaces obtained by both methods is similar. However, volume ratios between the discussed kinds of pores found by the above-mentioned methods differ significantly. Such discrepancy is the result of both ortho-positronium migration and the inaccessibility of the pores for nitrogen. Comparing the results of nitrogen sorption and positron annihilation lifetime spectroscopy allows us to estimate that connectivity between the primary pores and the interparticle spaces is the highest in MCM-41 and lowest in SBA-3.
    Źródło:
    Nukleonika; 2013, 58, 1; 235-240
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Porosity of Silica Monoliths with Tailored Mesopores of Ink-Bottle Shape Determined by Nitrogen Adsorption and Positron Annihilation Lifetime Spectroscopy
    Autorzy:
    Sienkiewicz, A.
    Kierys, A.
    Gorgol, M.
    Zaleski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1033934.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.05.Rm
    68.43.-h
    81.70.-q
    78.70.Bj
    36.10.Dr
    Opis:
    The comparison of pore size distributions obtained with the use of two porosimetric methods: low temperature nitrogen sorption (LN2) and positron annihilation lifetime spectroscopy (PALS), was performed for porous silica monoliths. Four investigated samples were prepared under various synthesis conditions. Nitrogen sorption showed the presence of bottle-shaped pores in all investigated samples. In addition, it seems that the presence of methanol during synthesis influences porosity to a greater extent than organic additives. Quite good agreement between the LN2 and PALS results was observed only for the silica monolith synthesized with β-cyclodextrins as pore directing agent. The biggest discrepancy in the results obtained from these two techniques was observed for the silica gel synthesized with no additives. The origin of such discrepancies, taking into account the shape of pore size distribution and deficiencies of data analysis techniques, is discussed.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1568-1571
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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