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    Wyświetlanie 1-81 z 81
    Tytuł:
    Slow positron beam at the JINR, Dubna
    Autorzy:
    Horodek, P.
    Kobets, A. G.
    Meshkov, I. N.
    Sidorin, A. A.
    Orlov, O. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/147134.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron beam
    positron injector
    Opis:
    The Low Energy Positron Toroidal Accumulator (LEPTA) at the Joint Institute for Nuclear Research (JINR) proposed for generation of positronium in flight has been adopted for positron annihilation spectroscopy (PAS). The positron injector generates continuous slow positron beam with positron energy range between 50 eV and 35 keV. The radioactive 22Na isotope is used. In distinction to popular tungsten foil, here the solid neon is used as moderator. It allows to obtain the beam intensity of about 105 e+/s width energy spectrum characterized by full width at half maximum (FWHM) of 3.4 eV and a tail to lower energies of about 30 eV. The paper covers the characteristic of variable energy positron beam at the LEPTA facility: parameters, the rule of moderation, scheme of injector, and transportation of positrons into the sample chamber. Recent status of the project and its development in the field of PAS is discussed. As an example, the measurement of the positron diffusion length in pure iron is demonstrated.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 725-728
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Understanding electron-positron momentum densities in solids : effect of the positron distribution
    Autorzy:
    Rubaszek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/147180.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    electronic band structure
    positron states
    Opis:
    The influence of the positron distribution on the electron-positron (e-p) momentum densities (MDs) is studied in terms of the l (l = s, p, d, f) character of the initial electronic state. The effect of the positron is discussed for momenta in the extended and reduced zone scheme on the example of Al (simple metal), Cu (metal with almost filled d shell), and Cr (transition metal). Present result indicates a weak sensitivity of the e-p MD inside the central Fermi surface to the positron charge density for the delocalized s and p electrons. In the case of d states, the effect of the positron on the relevant contribution to the e-p MD directly reflects the degree of localization of d electrons in the electron density of states.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 759-763
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of neoplastic therapy on the investigated blood using positron annihilation lifetime spectroscopy
    Autorzy:
    Pietrzak, R.
    Borbulak, S.
    Szatanik, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/147997.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    blood
    positron annihilation
    Opis:
    The influence of neoplastic radiotherapy and chemotherapy was investigated using annihilation lifetime spectroscopy in blood types 0 Rh+ -AB Rh+. Changes in the parameters of the longest lived component of the spectrum were analyzed depending on the time between the moment of taking the blood sample from a patient and that of taking measurements, and also the time passing from the cessation of radio- and chemotherapy.
    Źródło:
    Nukleonika; 2013, 58, 1; 199-202
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The implantation profile of positrons emitted in beta plus decay of 48V in water
    Autorzy:
    Dryzek, J.
    Horodek, P.
    Dryzek, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/148130.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron implantation range in water
    V-48 positron emitter
    Opis:
    The experimental technique based on scanning of positron implantation profile, hereafter referred to as the DSIP is used for the determination of linear absorption coefficient for positrons emitted from a 48V source into water. This coefficient is equal to 1/(299š62) mi m–1. The determined value is in agreement with the one obtained from the computer simulations using the well known EGS nrc 4.0 and GEANT4 codes. The experimental technique was used for the determination of linear absorption coefficients for 48V positrons in materials of biological origin. The presented data can be useful for PET studies because of similarities of the 18F and 48V positron implantation profiles.
    Źródło:
    Nukleonika; 2009, 54, 4; 223-226
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Uniqueness of studies on electron densities in the extended momentum space
    Autorzy:
    Kontrym-Sznajd, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/148018.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electron-positron momentum densities
    Compton scattering
    extended momentum space
    positron annihilation
    Opis:
    This work draws attention to the fact that by measuring electronic structure via angular correlation of positron radiation (ACAR) and Compton scattering experiments one probes electron densities in the extended momentum space, directly related to the electron Bloch wave functions. Presenting some examples of electron densities in the extended and reduced momentum spaces, it is demonstrated what kind of information concerning the electronic structure can be obtained depending on the considered space. It is also shown how the knowledge of the symmetry selection rules allows to separate various Fermi surfaces and establish Fermi momenta.
    Źródło:
    Nukleonika; 2013, 58, 1; 203-206
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    New Porosimetric Method Based on the 3γ Annihilation Rate. Applications to Materials Science and Medical Imaging
    Autorzy:
    Jasińska, B.
    Zgardzińska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1033228.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    positron annihilation
    positronium
    3γ annihilation
    porosity
    positron emission tomography
    medical imaging
    Opis:
    A new parameter δ based on 3γ annihilation is proposed. It describes the porosity of the materials containing small intermolecular voids below 1 nm. It can be applied to material investigation to compare changes in the material porosity depending on temperature or pressure as well as to study of ageing or manufacturing processes. Particularly it is dedicated to prepare the new imaging method and can be used during positron emission tomography diagnosis allowing determination the kind or stage of pathogenic alteration.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1616-1619
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron lifetime calculations for some elements on the base of the GGAPHNC approximation
    Autorzy:
    Boroński, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/146330.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    electronic structure
    Opis:
    In studies of several interesting materials by positron annihilation technique the theoretical values of positron lifetimes in bulk and defected elements are useful. These lifetimes are often calculated within the GGA approximation. In this approximation the results of Arponen and Pajanne calculations for the positron in an electron gas are used. It is known, however, that when using the LDA approximation for the calculations of positron lifetime in real metals, Arponen and Pajanne values yield worse agreement with experimental data than the results obtained on the basis of PHNC formalism. Therefore, in this paper the appropriate PHNC formulas are incorporated into the GGA approximation and the calculations have been performed for some metals: bulk as well as containing monovacancies. The comparison of the lifetimes found in this way to the ones based on the previous method is promising for the applicability of the new algorithm.
    Źródło:
    Nukleonika; 2010, 55, 1; 9-12
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Momentum distributions in positron annihilation with tightly bound electrons in Al
    Autorzy:
    Boroński, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/148016.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    electronic structure
    Opis:
    An approach based on Carbotte, Salvadori and Chiba two-body schemes for calculation of electron-positron (e-p) momentum densities ro(p) for core electrons in solids is developed. The approach allows to avoid such common approximations as the local density approximation (LDA) etc. in determination of ro(p) of deeper atomic shells and reduces the contribution to ro(p) for higher momenta. Thus, the final calculations of the Doppler spectra of annihilation radiation yield lower values for greater momenta than those obtained within the LDA scheme. The exemplary calculations for Al are presented.
    Źródło:
    Nukleonika; 2013, 58, 1; 211-214
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Some remarks on positron/positronium diffusion models
    Autorzy:
    Świątkowski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/148428.pdf
    Data publikacji:
    2003
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    diffusion
    diffusion length
    positron
    positronium
    Opis:
    Positrons thermalized near the sample boundary (as well as Ps atoms formed in the sample) can reach the boundary as a result of diffusive movement. Observations of such effects as positron reemission or positron surface trapping as well as positronium emission allow one to calculate respective diffusion lengths. From the presented analysis it follows that some models used in such calculations give quite wrong results.
    Źródło:
    Nukleonika; 2003, 48, 3; 141-144
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron-annihilation and photoluminescence studies of nanostructured ZrO2
    Autorzy:
    Fidelus, J. D.
    Karbowski, A.
    Mariazzi, S.
    Brusa, R. S.
    Karwasz, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/146313.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    zirconia nanopowders
    photoluminescence
    Opis:
    In the present work, photoluminescence and Doppler broadening depth-resolved positron annihilation spectroscopy was performed on pure zirconia nanopowders. Zirconia nanopowders were grown by a hydrothermal microwave-driven process followed by annealing in oxygen atmosphere. Photoluminescence under 274 nm wavelength excitation from a 150 W high-pressure Xe exhibits similar spectra, in the region from 320 to 820 nm, although its intensity depends on the annealing. Positron annihilation Doppler-broadening spectra show low values of the normalized S-parameter, varying little with the depth, from 0.495 on the surface to 0.47-0.49 in bulk. Both high the annealing temperature and oxygen concentrations, lead to low bulk S-values. The ortho-positronium (o-Ps) fraction is about 10-11% for all samples on the surface, whereas it is reduced to 7-8% in the bulk for samples annealed at 700°C and 5-6% for samples annealed at 800°C. Both photoluminescence (PL) and positron studies show the presence of defects in all samples. The o-Ps signal suggests a high porosity of samples, particularly at a depth down to 10 nm.
    Źródło:
    Nukleonika; 2010, 55, 1; 85-89
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation studies of mesoporous iron modified MCM-41 silica
    Autorzy:
    Wiertel, M.
    Surowiec, Z.
    Budzyński, M.
    Gac, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/147950.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    iron
    MCM-41 silica mesoporous materials
    N2 sorption
    positron annihilation
    positron lifetime spectra
    Opis:
    MCM-41 silica materials modified by iron incorporation in the stage of its synthesis were investigated. The aim of the studies was determination of the nature of iron species and the influence of its content on the structural changes of materials and following the changes of their properties. For this purpose, the N2 sorption/desorption method and positron annihilation lifetime spectroscopy (PALS) were used. Disappearance of the longest-lived ortho-positronium (o-Ps) component (tau5) present in the PALS spectra of the initial MCM-41 material in the spectra of Fe-modified MCM-41 measured in vacuum is a result of a strong chemical o-Ps quenching and/or the Ps inhibition mechanism. Filling of pores by air or N2 at ambient pressure causes reappearance of the (tau5) component with lifetime shortened in comparison to that observed in vacuum for pure MCM-41 to the extent which can be explained by usual paramagnetic quenching in air. In contrary to the tendency observed for (tau5) lifetime which is practically independent of Fe content, the relevant intensity I5 monotonically decreases. This fact suggests that only inhibition of Ps formation occurs for the samples in air. Observed anti-quenching effect of air seems to be a result of competition of two processes : neutralization of surface active centres acting as inhibitors and considerably weaker paramagnetic quenching by O2 molecules.
    Źródło:
    Nukleonika; 2013, 58, 1; 245-250
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of magnetic field on the corrosion of iron as studied by positron annihilation
    Autorzy:
    Pietrzak, R.
    Szatanik, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/146285.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    corrosion
    magnetic field
    positron annihilation
    Opis:
    Lifetime spectra of positron annihilation in iron corroded in a water solution of HCl and in vapour above its surface have been investigated with emphasis on the effect of corrosion time and environment (solution or vapour) as well as of the presence and orientation of the magnetic field on the measured positron annihilation parameters. All the registered positron lifetime spectra consist of two components. For corroded samples, the intensities of the two components as well as the corresponding values of the mean positron lifetime, differ from those for uncorroded material. The corrosion-induced changes in the positron annihilation parameters depend on the corrosion environment (solution or vapour) and on the presence and direction of external magnetic field.
    Źródło:
    Nukleonika; 2010, 55, 1; 31-34
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of low temperature on the free volume in polyethylene by positron annihilation
    Autorzy:
    Osoba, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/146305.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    polymers
    free volume
    Opis:
    Positron lifetime measurements were performed as a function of temperature in thermo-shrunken, modified polyethylene. Mean volume of free volume cavities in the investigated polymer was estimated from the results of the measurements. This mean volume turned out to be a smooth function of temperature (from room temperature to 8.5 K). The effect of trapping of free electrons, produced during positron irradiation, was observed at lowered temperature.
    Źródło:
    Nukleonika; 2010, 55, 1; 69-72
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of corrosion defects in titanium by positron annihilation
    Autorzy:
    Pietrzak, R.
    Szatanik, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/147338.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation spectroscopy
    corrosion defects
    Opis:
    The positron annihilation method was used to study the formation of defects in titanium samples during their corrosion in the vapor of a 3% HCl solution. In particular, the distribution of defects depending on the distance from the corroding surface and the impact of an external magnetic fi eld on the concentration of vacancies forming during the corrosion of titanium layers close to the surface were determined.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 755-758
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation in precious and common opals
    Autorzy:
    Chojcan, J.
    Sachanbiński, M.
    Idczak, R.
    Konieczny, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/148010.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    opal-A
    porosity
    positron annihilation
    Opis:
    The nano-porosity structure of several non-crystalline opal samples of different origin was investigated with positronium atoms. The obtained data show that the structure depends on both the kind of opal (precious, common or hyalite) as well as the place of its creation (sedimentary or volcanic rocks). The sizes of the pores "seen" by positronium atoms are relatively small, not greater than about 1 nm for all studied samples which may suggest that the pores are located inside the silica matter from which the samples are made. Moreover, the pores detected in the "sedimentary" precious opals are smaller and have less diverse sizes than those found in 'sedimentary" common opals and "volcanic' precious opals.
    Źródło:
    Nukleonika; 2013, 58, 1; 225-228
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation in liquid crystals
    Autorzy:
    Dryzek, E.
    Juszyńska-Gałązka, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/148118.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    liquid crystals
    positron annihilation
    phase transitions
    Opis:
    Positron annihilation studies of liquid crystals are reviewed with particular reference to thermotropic liquid crystals with rod-like molecules. The studies of compounds exhibiting smectic A or smectic E phases indicate that local arrangement of dipole molecules play an important role because high electron density at the end group of molecules can influence substantially formation and annihilation of positronium. The obtained ortho-positronium lifetimes in these phases can be explained by antiparallel pairing of molecules in case of the smectic A phase or a structure with a nanosegregation of alkyl chains and others parts of molecules into sublayers and liquid-like state of alkyl chains in case of the smectic E phase.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 703-708
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies of stainless steel exposed to sandblasting
    Autorzy:
    Horodek, P.
    Eseev, M. K.
    Kobets, A. G.
    Powiązania:
    https://bibliotekanauki.pl/articles/147075.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    stainless steel
    sandblasting
    defects
    positron beam
    Opis:
    The influence of sandblasting on surface and subsurface of stainless steel is investigated using variable energy positron beam (VEP), positron annihilation spectroscopy (PAS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Samples of stainless steel were blasted using 110 μm particles of Al2O3 under different pressure and time duration. In the case of sandblasting for 90 s, the reduction of positron diffusion length depending on the applied pressure was observed. Sandblasting during 30 s leads only to the reduction of positron diffusion length to about 60 nm for all samples. Positron lifetimes close to 170 ps measured using positrons emitted directly from the source point to the presence of vacancies on the dislocation lines. SEM and AFM images show that surface roughness depends rather on pressure of sandblasting than time of exposition.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 721-724
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modern radiation techniques for treatment of head and neck cancers
    Autorzy:
    Kiprian, Dorota
    Powiązania:
    https://bibliotekanauki.pl/articles/1401820.pdf
    Data publikacji:
    2015
    Wydawca:
    Index Copernicus International
    Tematy:
    positron emission tomography
    radiotherapy
    throat
    apoptosis
    Opis:
    Alongside surgery, radiation therapy remains the mainstay of treatment for head and neck cancers.  Because the head and neck contain a number of critically important structures, it is crucial to try to curtail the adverse effects of radiation therapy by increasing its precision. Such precise radiation techniques include the three-dimensional conformal as well as highly conformal radiotherapy. The latter includes, for instance, intensity modulated radiation therapy (IMRT), stereotactic radiation, and proton-beam therapy. All of the above-mentioned techniques are available in Poland and give the opportunity of a more aggressive treatment that lead to improved outcomes, curtailment of adverse effects, and by that, a better quality of life.
    Źródło:
    Polski Przegląd Otorynolaryngologiczny; 2015, 4, 4; 1-10
    2084-5308
    2300-7338
    Pojawia się w:
    Polski Przegląd Otorynolaryngologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron study of the structure of nonadecane-tricosane mixed solid
    Autorzy:
    Zgardzińska, B.
    Goworek, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/146297.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    n-alkanes
    binary mixture
    Opis:
    Positron annihilation lifetime and intensity were measured as a function of temperature for a binary mixture of two normal alkanes. The rotator phase is preceded by the range of about 7 K, in which one observes instability of spectrum parameters. In that range the mixed solid, being initially introduced into rotator phase, transforms to a rigid one in the time scale of several hours.
    Źródło:
    Nukleonika; 2010, 55, 1; 47-49
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Toward a European Network of Positron Laboratories
    Autorzy:
    Karwasz, G. P.
    Brusa, R. S.
    Egger, W.
    Ogorodnikova, O. V.
    Powiązania:
    https://bibliotekanauki.pl/articles/146548.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron beams
    material science
    thermonuclear reaction
    Opis:
    Some applications of controlled-energy positron beams in material studies are discussed. In porous organic polysilicates, measurements of 3γ annihilation by Doppler broadening (DB) method at the Trento University allowed to trace pore closing and filling by water vapor. In silicon coimplanted by He+ and H+, DB data combined with positron lifetime measurements at the München pulsed positron beam allowed to explain Si blistering. Presently measured samples of W for applications in thermonuclear reactors, irradiated by W+ and electrons, show vast changes of positron lifetimes, indicating complex dynamics of defects.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 733-739
    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:
    Annealing behaviour of plastically deformed stainless steel 1.4307 studied by positron annihilation methods
    Autorzy:
    Dryzek, E.
    Sarnek, M.
    Siemek, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/148014.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    plastic deformation
    positron annihilation
    stainless steel
    Opis:
    Isochronal and isothermal annealing of stainless steel 1.4307 samples deformed by compression were investigated using Doppler broadening measurements of the annihilation line. We made an attempt to describe the obtained dependencies in terms of vacancy migration and sinking to the grain boundaries. The model assumed spherical grains with a homogeneous initial distribution of vacancies. The model was capable of following the isochronal annealing data quite accurately. However, the obtained activation energy of vacancy migration equal to 0.44 plus or minus 0.05 eV seemed too low. The isothermal annealing dependency was reproduced less precisely. The reason for this may be the presence of the alfa'-martensite particles in the samples, which can introduce additional defects seen by positrons in the temperature range in which the martensite reversion takes place.
    Źródło:
    Nukleonika; 2013, 58, 1; 215-219
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The detection of reverse accumulation effect in the positron annihilation profile of stack of aluminum and silver foils
    Autorzy:
    Dryzek, J.
    Siemek, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/148620.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron implantation profile
    stack of foils
    Opis:
    The implantation profile of positrons emitted from 22Na into a stack of aluminum and silver foils is the subject of the presented report. The characteristic dimple in the profile behind the Ag foil was detected. This effect arises from the differences in the linear absorption coefficient of aluminum and silver. The good agreement between the theoretical profile obtained within the multiscattering model and experimental one was achieved. The observed phenomenon can affect the positron annihilation characteristics measured for the inhomogeneous samples.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 713-716
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Photo-oxidative Aging Behaviors of Acrylic Coatings during UV Irradiation Investigated by Positron Annihilation Spectroscopy
    Autorzy:
    Zhao, Xipo
    Cai, Xiaolin
    Liu, Chang
    Chen, Ting
    He, Chunqing
    Fang, Pengfei
    Peng, Shaoxian
    Powiązania:
    https://bibliotekanauki.pl/articles/1033253.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    Acrylic coating
    UV irradiation
    positron annihilation spectroscopy
    Opis:
    Slow positron annihilation spectroscopy, contact angle and scanning electron microscope (SEM) were employed to investigate the surface polarity and morphologies as functions of aging time in acrylic coatings during UV-a irradiation. The S parameter plots of each exposed sample are lower than that of the virgin sample in the whole range of E. The S parameter plots become lower as the exposing longer time, indicated that the irradiation generated more polar groups and increased the oxidation layer depth. Combined with surface morphology and the surface energy of acrylic coating, the variation of contact angle, and surface energy, polar component and dispersive component is related with surface polarity and morphologies.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1527-1530
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Developing New Routine for Processing Two-Dimensional Coincidence Doppler Energy Spectra and Evaluation of Electron Subsystem Properties in Metals
    Autorzy:
    Stepanov, P.
    Stepanov, S.
    Byakov, V.
    Selim, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/1033257.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    Positron annihilation
    Doppler broadening
    metals
    core electrons
    Opis:
    A digital coincidence Doppler broadening (CDB) spectrometer consisting of two HPGe detectors is assembled; the energy resolution of each detector is 1.1 keV at energies near the annihilation line. Two desktop applications for CDB spectra processing are developed. TLIST Processor converts two-dimensional CDB spectra into one-dimensional spectra. Another tool SW Calculator deconvolutes the experimental CDB spectra into contributions from positron annihilation with valence, core and conduction band electrons. The program estimates the energies of the corresponding electrons and evaluates S and W parameters of the CDB spectra.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1628-1633
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of electronelectron correlations on positron-electron momentum density distributions
    Autorzy:
    Boroński, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/146328.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    electronic structure
    many-body physics
    Opis:
    The calculations of the influence of the self-energy effects on the electron-positron (e-p) enhancement factors and the e-p momentum distributions are presented. The approach bases on the novel formulation of the Bethe- -Goldstone (B-G) equation for the positron in an electron gas where the scattering of the electrons into the states below the Fermi surface due to the self-energy effects is allowed. This equation has been solved and the corresponding e-p enhancement factors and momentum distributions have been found. The agreement between the absolute values of the theoretical calculations and experimental data has improved noticeably.
    Źródło:
    Nukleonika; 2010, 55, 1; 3-8
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    PALS investigations of free volumes thermal expansion of J-PET plastic scintillator synthesized in polystyrene matrix
    Autorzy:
    Wieczorek, A.
    Zgardzińska, B.
    Jasińska, B.
    Gorgol, M.
    Bednarski, T.
    Białas, P.
    Czerwiński, E.
    Gajos, A.
    Kamińska, D.
    Kapłon, Ł.
    Kochanowski, A.
    Korcyl, G.
    Kowalski, P.
    Kozik, T.
    Krzemień, W.
    Kubicz, E.
    Niedźwiecki, S.
    Pałka, M.
    Raczyński, L.
    Rudy, Z.
    Rundel, O.
    Sharma, N. G.
    Silarski, M.
    Silarski, A.
    Strzelecki, A.
    Wiślicki, W.
    Zieliński, M.
    Moskal, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/147132.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    free volume
    positron annihilation
    polystyrene
    positronium
    scintillator
    Opis:
    The polystyrene doped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260, 283, and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the significant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 777-781
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spectacular efficacy of neoadjuvant chemotherapy in a patient with cervical cancer of IB2 grade according to FIGO 2009
    Spektakularna skuteczność chemioterapii neoadiuwantowej u pacjentki z rozpoznaniem raka szyjki macicy w stopniu IB2 według FIGO 2009 r.
    Autorzy:
    Kaźmierczak, Kamila
    Nowakowski, Błażej
    Kufel-Grabowska, Joanna
    Cholewiński, Witold
    Powiązania:
    https://bibliotekanauki.pl/articles/1035650.pdf
    Data publikacji:
    2020
    Wydawca:
    Medical Education
    Tematy:
    cervical cancer
    neoadjuvant chemotherapy
    positron emission tomography
    Opis:
    The presented case report is an example of a spectacular effect of induction systemic treatment in a patient with locally advanced cervical cancer of IB2 grade according to FIGO 2009 (International Federation of Gynecologist and Obstetrician). The effect of induction chemotherapy (three series in paclitaxel/24 h + cisplatin regimen at an interval of three weeks) was the total metabolic response of the primary tumor and nodal lesions found in FDG-PET/CT (18F-fluorodeoxyglucose – positron emission tomography combined with computed tomography) as well as an image of total regression of the tumor in the obtained postoperative histopathological examination.
    Przedstawiony opis przypadku jest przykładem spektakularnego efektu zastosowania chemioterapii neoadiuwantowej (NACT, neoadjuvant chemotherapy) u pacjentki z miejscowo zaawansowanym rakiem szyjki macicy w stopniu IB2 według FIGO 2009 r. (International Federation of Gynecologist and Obstetrician). Efektem zastosowanej chemioterapii indukcyjnej (trzech serii w schemacie paklitaksel/24 h + cisplatyna w odstępie 3-tygodniowym) była całkowita odpowiedź metaboliczna guza pierwotnego i zmian węzłowych stwierdzona w badaniu FDG-PET/CT (18F-fluorodeoksyglukoza – pozytonowa tomografia emisyjna połączona z tomografią komputerową), a także obraz całkowitej odpowiedzi patologicznej w otrzymanym pooperacyjnym badaniu histopatologicznym.
    Źródło:
    OncoReview; 2020, 10, 2; 69-76
    2450-6125
    Pojawia się w:
    OncoReview
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gamma Induced Positron Annihilation: History, Current, and Future Developments
    Autorzy:
    Selim, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030020.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    gamma induced positron spectroscopy
    positron transient measurements
    thermal neutron capture
    proton capture
    electron accelerator
    Van de Graaff accelerator
    Opis:
    Positron annihilation spectroscopy is often performed using radioactive sources for bulk measurements or positron beams for depth resolved measurements. Both have many advantages and great capabilities for a variety of applications. In the recent history, we have shown that positron annihilation spectroscopy can be carried out directly using high energy photons without the need for positron source or positron beam. This approach brings unique capabilities for some specific applications and promotes the use of positron annihilation spectroscopy in new areas of materials science and probably in industrial applications. Some of the important applications include developing new nondestructive highly penetrating sensitive probe for structural and engineering materials. It can also greatly advance positron applications in bulk semiconductors, electronic and photonic materials as well as in polymers, ceramics, and liquids. The recently developed γ-induced positron spectroscopy in HZDR in Dresden provides an example of an excellent facility for many of these applications. When incorporated with pulsed accelerators, γ-induced positron annihilation spectroscopy may trigger novel studies of transient states in matter and explore several solid-state processes that take place on short time scale. In this article I will review the history and development of the technique and its incorporation in a wide range of accelerators including table top electron accelerators, pulsed electron accelerators, and Van de Graaff accelerators. Then I will introduce a design for a new γ-induced positron annihilation spectroscopy facility based on using small nuclear research reactors or neutron generators. The paper presents all the possible approaches for γ-induced positron annihilation spectroscopy and discusses its potential and limitations to guide the efforts in further development of the technique and illustrate the unique aspects that the technique can bring to positron science and applications.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1450-1455
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Compact cyclotrons for the production of tracers and radiopharmaceuticals
    Autorzy:
    Paans, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/146155.pdf
    Data publikacji:
    2003
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron emission tomography (PET)
    cyclotron
    radionuclide production
    Opis:
    Positron Emission Tomography (PET) is a method for determining biochemical and physiological processes in vivo in a quantitative manner. The most commonly used radionuclides are 11C, 13N, 15O and 18F, with respective half-lives of approximately 20 min, 10 min, 2 min, and 110 min. 18F labeled FDG (fluoro-2-deoxy-D-glucose) is now the most frequently used radiopharmaceutical and finds its application prominently in the field of oncology. Originally, the production of these radionuclides was performed with the existing accelerators, designed for nuclear physics, but with increasing interest in the PET methodology specially designed PET-production cyclotrons became available. The nuclear reactions involved are (p,n), (d,n), (p,a) and (d,a) and the thresholds for the nuclear reactions involved are 5 to 6 MeV. Based on these values and on other parameters, a proton 15 to 20 MeV cyclotron is often chosen. Since the half-life of a radionuclide limits the production time, the maximum beam current is an important parameter, together with the target construction, for the ultimate yield obtainable. In the development of special PET production cyclotrons, attention has also been paid to improve the extraction efficiency and the possibility of multiple extractions by designing negative ion cyclotrons. Commercial cyclotrons can often be acquired as an easy to operate integrated radionuclide production unit including targetry and some units. Regional FDG factories are nowadays being created to fulfil the demand for PET radiopharmaceutics. The possible choices in commercially available cyclotrons for the production of PET radionuclides will be discussed.
    Źródło:
    Nukleonika; 2003, 48,suppl.2; 169-172
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation studies of high-manganese steel deformed by rolling
    Autorzy:
    Dryzek, E.
    Sarnek, M.
    Wróbel, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/146593.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    plastic deformation
    positron annihilation
    high-manganese steel
    Opis:
    Positron annihilation spectroscopy (PAS) has been used to study the annealing behavior of cold rolled Fe – 21 wt% Mn steel with 0.05 wt% C. After the initial annealing of defects shown by Doppler broadening of the annihilation line, a slight increase in the annihilation line shape parameter, i.e., the so-called S parameter and then its decrease in the temperature range between 225◦C and 450◦C indicates generation of new defects and their subsequent annealing. This temperature range coincides with X-ray diffraction measurements, which indicate reversion of deformation-induced ε-martensite. However, for annealing in this temperature range with slow cooling of the sample, the formation of ferrite already starts. The results are compared with our previous results for deformed austenitic stainless steel 1.4301 (EN) where only reversion of deformation-induced α'-martensite was detected.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 709-712
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The POCOBIO Database for Computed Scattering Cross-Sections for Positron Collisions with Biomolecular Systems
    Autorzy:
    Franz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030032.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    positron-molecule scattering
    quantum calculations
    molecular gases
    Opis:
    The design of a database for positron interactions with biomolecular systems is outlined. The database contains only scattering cross-sections, which are derived from theory. The data model is defined in a very flexible way, which facilitates the usage of weakly bound clusters of molecules and molecular systems with many tautomeric forms.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1478-1481
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Badania strukturalne materiałów stosowanych do ochrony przed zagrożeniami pyłami w środowisku pracy za pomocą spektroskopii czasu życia pozytonów
    Study structural materials used for protection against risks dust environmental work with life time spectroscopy positron
    Autorzy:
    Pach, K.
    Filipecki, J.
    Zawada, D.
    Golis, E.
    Hyla, M.
    Krasowski, J.
    Kokot, L.
    Dymarek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/103557.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
    Tematy:
    spektroskopia
    pozyton
    filtry przeciwpyłowe
    spectroscopy
    positron
    dust filters
    Opis:
    Źródłem zanieczyszczeń pyłowych na stanowiskach pracy są procesy pyłotwórcze oraz przypadkowe rozpylanie warstwy pyłu osiadłego na powierzchniach pomieszczeń, maszyn i podłogach. Działania profilaktyczne mają za zadanie (techniczne i medyczne) zapobieganie przede wszystkim przypadkom pylicy płuc oraz zmianom nowotworowym. Profilaktyka techniczna dotyczy stosowania urządzeń odpylających i wentylacji, a także indywidualnych ochron dróg oddechowych (maski). W związku ze wspomnianymi zagrożeniami występującymi w środowisku pracy, w którym występują zanieczyszczenia pyłowe, przeprowadzone zostały badania, mające na celu określenie różnic strukturalnych w materiałach używanych do filtrów przeciwpyłowych stosowanych dla bezpieczeństwa w środowisku pracy. W badaniach zostały wykorzystane dwie półmaski filtrujące ZFO wykonane w Centralnym Instytucie Ochrony Pracy w Państwowym Instytucie Badawczym. Pomiary badanych materiałów przeprowadzane zostały za pomocą spektrometru czasów życia pozytonów firmy ORTEC. Wyniki badań wykazały różnice w strukturze badanych półmasek filtrujących.
    The source of dust pollution in the workplace are the processes of dustproducing and accidental spraying a layer of dust settled on the surfaces of premises, equipment and floors. Preventive measures are designed to (technical and medical) prevention mainly cases of pneumoconiosis and malignant changes. Prevention Technical relates to the use of dedusting devices and ventilation, as well as individual respiratory protection (masks). In connection with these hazards in the work environment, where there are dust pollution were carried out studies to determine the structural differences in the materials used for dust filters used for safety in the work environment. The studies were used two respirators ZFO made at the Central Institute for Labour Protection National Research Institute Measurements of test materials were carried out by means of positron lifetime spectrometer company ORTEC. The results showed differences in the structure of the tested respirators.
    Źródło:
    Prace Naukowe Akademii im. Jana Długosza w Częstochowie. Technika, Informatyka, Inżynieria Bezpieczeństwa; 2016, T. 4; 309-318
    2300-5343
    Pojawia się w:
    Prace Naukowe Akademii im. Jana Długosza w Częstochowie. Technika, Informatyka, Inżynieria Bezpieczeństwa
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Free-Volume Evolution of 1-Propanol Confined in Variously Filled Regular Mesopores of SBA-15 Matrix
    Autorzy:
    Šauša, O.
    Lukešová, M.
    Švajdlenková, H.
    Bartoš, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1033259.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    positron annihilation
    1-propanol
    confined systems
    free-volume
    Opis:
    The free-volume of 1-propanol (1-PrOH) confined in a regular mesoporous SBA-15 matrix was investigated by desorption experiment at room temperature and over a wide temperature range, from 15 K up to 350 K, for four different contents of 1-PrOH in the pores. The gradual desorption of 1-PrOH from the mesopores as well as the free volume temperature dependences have shown that the polar molecules of 1-PrOH located at the inner polar surface of the SBA-15 matrix are more strongly bound to the matrix surface. The subsequent discussion of the annihilation and free-volume characteristics follows.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1572-1574
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation, quality control and biodistribution studies of [61Cu]-oxinate for PET tumor imaging
    Autorzy:
    Jalilian, A. R.
    Zolghadri, S.
    Faghihi, R.
    Yousefnia, H.
    Garousi, J.
    Shafaii, K.
    Bolourinovin, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/148094.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    copper-61
    8-hydroxyquinoline
    positron emission tomography
    fibrosarcoma
    Opis:
    Targeting apoptosis is an interesting issue in molecular imaging and various modalities have been presented. However, recent experiences in nuclear pharmacy demonstrated the application of small tracer molecules is more desired. This work was conducted for production of a radiolabeled copper complex, i.e. 61Cu-oxinate as a potential PET tracer for apoptosis imaging in oncology. Cu-61 was prepared by natural zinc target irradiation with 22 MeV protons (150 miA) via the natZn(p, xn)61Cu nuclear reaction with a yield of 3.33 mCi/miAh. In order to obtain the best labeling method, optimization reactions were performed for pH, temperature and concentration followed by solid phase extraction. Biodistribution of the tracer was studied in wild-type and fibrosarcoma bearing mice. Under the optimized conditions, radio-thin-layer chromatography (RTLC) and HPLC showed radiochemical purities of 99.99% and 97% respectively (with a minimum specific activity of 16 Ci/mM). Biodistribution of the tracer in fibrosarcoma bearing mice demonstrated a significant tumor uptake after 3 h. Tumor:blood and tumor:muscle ratios were 2.0 and 6.0 after 3 h, respectively.
    Źródło:
    Nukleonika; 2009, 54, 3; 175-179
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of hydrogen concentration on positron lifetime and electrical resistivity in vanadium-hydrogen systems
    Autorzy:
    Pietrzak, R.
    Szatanik, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/146289.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron lifetime
    resistivity
    V-H system
    annihilation parameters
    Opis:
    Positron lifetime spectra and electrical resistivity of the vanadium-hydrogen systems with hydrogen concentration ranging from 0 to 0.29 at.H/at.V have been investigated. The range of hydrogen concentrations under investigation included the single alfa phase and a mixture of the alfa and beta phases of V-H system. The registered positron lifetime spectra were analysed by decomposition into two components. A distinct change in the annihilation parameters has been found after exceeding the boundary concentration of hydrogen in vanadium corresponding to the phase transition alfa (alfa+ beta). Correlation of changes in the parameters of the positron lifetime spectrum and in the electrical resistivity resulting from the changes in hydrogen concentration, has been revealed.
    Źródło:
    Nukleonika; 2010, 55, 1; 35-39
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ortho-positronium in liquid alkanes
    Autorzy:
    Zgardzińska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/146291.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    liquid alkanes
    bubble model
    surface tension
    Opis:
    Positron lifetime spectra were measured for a series of odd-numbered liquid n-alkanes (C7H16, C9H20, C13H28 and C19H40) in a broad range of temperature. According to the “bubble model” the ortho-positronium (o-Ps) lifetime is determined by surface tension. Bubble radius was calculated using the Tao-Eldrup model and compared to the radius expected from the surface tension of liquid. The radii are not identical, their difference rises with temperature. If one assumes the difference of radii as constant, the o-Ps lifetime calculated from the Tao-Eldrup model rises faster than the experimental one. The distinct rise of the difference of radii has no physical explanation in the accepted o-Ps annihilation model. This effect can be the result of radiation chemistry processes not taken into account so far in the bubble model.
    Źródło:
    Nukleonika; 2010, 55, 1; 41-46
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electron traps in long-chain alkanes
    Autorzy:
    Pietrow, M.
    Wawryszczuk, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/146299.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    PALS
    positron annihilation
    electron traps
    quenching by light
    Opis:
    Positron lifetime spectra in long-chain alkanes were measured at various wavelengths of light illuminating the samples as a function of temperature, storage time. It was found that in n-alkanes with carbon chain longer than 30 atoms two kinds of electron traps exist; the depth of shallower of them is less than 0.52 eV. They are discharged already at a temperature of 120 K.
    Źródło:
    Nukleonika; 2010, 55, 1; 51-55
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of the compress sensing theory for improvement of the TOF resolution in a novel J-PET instrument
    Autorzy:
    Raczyński, L.
    Moskal, P.
    Kowalski, P.
    Wiślicki, W.
    Bednarski, T.
    Białas, P.
    Czerwiński, E.
    Gajos, A.
    Kapłon, Ł.
    Kochanowski, A.
    Korcyl, G.
    Kowal, J.
    Kozik, T.
    Krzemień, W.
    Kubicz, E.
    Niedźwiecki, S.
    Pałka, M.
    Rudy, Z.
    Salabura, P.
    Gupta-Sharma, N.
    Silarski, M.
    Słomski, A.
    Smyrski, J.
    Strzelecki, A.
    Wieczorek, A.
    Zieliński, M.
    Zoń, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/146280.pdf
    Data publikacji:
    2016
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    compressed sensing
    positron emission tomography
    time-of-flight
    Opis:
    Nowadays, in positron emission tomography (PET) systems, a time of fl ight (TOF) information is used to improve the image reconstruction process. In TOF-PET, fast detectors are able to measure the difference in the arrival time of the two gamma rays, with the precision enabling to shorten signifi cantly a range along the line-of-response (LOR) where the annihilation occurred. In the new concept, called J-PET scanner, gamma rays are detected in plastic scintillators. In a single strip of J-PET system, time values are obtained by probing signals in the amplitude domain. Owing to compressive sensing (CS) theory, information about the shape and amplitude of the signals is recovered. In this paper, we demonstrate that based on the acquired signals parameters, a better signal normalization may be provided in order to improve the TOF resolution. The procedure was tested using large sample of data registered by a dedicated detection setup enabling sampling of signals with 50-ps intervals. Experimental setup provided irradiation of a chosen position in the plastic scintillator strip with annihilation gamma quanta.
    Źródło:
    Nukleonika; 2016, 61, 1; 35-39
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monte Carlo simulation of the positron implantation profiles in the layered samples
    Autorzy:
    Dryzek, J.
    Horodek, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/146332.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron implantation
    implantation profile
    GEANT4 tool kit
    Opis:
    Theoretical studies of the positron implantation profiles in the layered samples are presented. Simulations performed using a GEANT4 tool kit revealed accumulation of positrons in denser layer embedded by less dens environment. This effect is significant for implantation profiles of slow positrons formed in a beam. Nevertheless, it is also present in conventional experiments, where positrons are emitted from radioactive nuclei. In some cases the diffusion process, which follows the implantation and thermalization processes, can smear this effect. However, defects on the interfaces or differences in the positron affinity can sustain it.
    Źródło:
    Nukleonika; 2010, 55, 1; 13-16
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation and biological evaluation of [61Cu]bleomycin complex as a possible PET radiopharmaceutical in normal and fibrosarcoma-bearing animals
    Autorzy:
    Jalilian, A. R.
    Zandi, H.
    Sardari, D.
    Akhlaghi, M.
    Kamali-Dehghan, M.
    Shafaei, K.
    Majdabadi, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/148090.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    radiopharmaceutical
    copper-61
    bleomycin
    positron emission tomography
    fibrosarcoma
    Opis:
    [61Cu]bleomycin ([61Cu]BLM) was prepared using [61Cu]CuCl2 produced via natZn(p,x)61Cu. [61Cu]BLM was prepared under optimized conditions (room temperature, 45 min, 0.1 mg bleomycin for 92.5–370 MBq 61CuCl2) with radiochemical purity over 98% shown by HPLC and RTLC. [61Cu]BLM was administered into normal and tumor bearing rodents up to 210 min followed by biodistribution and co-incidence imaging studies. A significant tumor/non tumor accumulation was observed either by animal sacrification or an imaging method. [61Cu]BLM can be a potential PET radiotracer for tumor imaging.
    Źródło:
    Nukleonika; 2009, 54, 2; 135-141
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Human tissue investigations using PALS technique - free radicals influence
    Autorzy:
    Jasińska, B.
    Zgardzińska, B.
    Chołubek, G.
    Pietrow, M.
    Gorgol, M.
    Wiktor, K.
    Wysogląd, K.
    Białas, P.
    Curceanu, C.
    Czerwiński, E.
    Dulski, K.
    Gajos, A.
    Głowacz, B.
    Hiesmayr, B.
    Jodłowska-Jędrych, B.
    Kamińska, D.
    Korcyl, G.
    Kowalski, P.
    Kozik, T.
    Krawczyk, N.
    Krzemień, W.
    Kubicz, E.
    Mohammed, Muhsin
    Pawlik-Niedźwiecka, M.
    Niedźwiecki, S.
    Pałka, M.
    Raczyński, L.
    Rudy, Z.
    Sharma, N.
    Sharma, S.
    Shopa, R.
    Silarski, M.
    Skurzok, M.
    Wieczorek, A.
    Wiktor, H.
    Wiślicki, W.
    Zieliński, M.
    Moskal, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1057941.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    positron annihilation
    positronium
    free radicals
    tissues
    uterine leiomyomas
    Opis:
    The positron annihilation lifetime spectroscopy was applied to the samples of the human uterine leiomyomas and the normal myometrium tissues taken from the selected place of the uterus during a surgery. The method indicated differences in values of the measured positron annihilation lifetime spectroscopy parameters (lifetimes and intensities) between healthy and diseased tissue samples. The additional measurements were performed either in darkness or in presence of visible light which influenced the free radicals present in both kind of tissues and, as a result, made changes in free annihilation and o-Ps decay lifetime and intensity values.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1556-1558
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron Annihilation Studies of the Free Volumes in Nylon12/PVA Films Treated by Supercritical Carbon Dioxide
    Autorzy:
    Li, Jingjing
    Yin, Chongshan
    Zhou, Yawei
    Li, Gang
    Yeh, Jen-taut
    He, Chunqing
    Powiązania:
    https://bibliotekanauki.pl/articles/1033920.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    Nylon12/PVA
    ScCO₂
    positron annihilation
    free volume
    relaxation
    Opis:
    Free volume variations of Nylon12/Polyvinyl alcohol (Nylon12/PVA) blends treated in supercritical carbon dioxide (ScCO₂) were investigated using positron annihilation lifetime spectroscopy. It is found that o-Ps lifetime τ₃ and the corresponding intensity I₃ in Nylon12/PVA decrease with increase of the PVA content. Being treated in ScCO₂ at 50°C and 20 MPa for 1 h, the free volume holes in Nylon12/PVA blends expand to different extents depending on the weight ratio of PVA. After releasing of CO₂, the free volume size decreases as a function of the elapsed time due to the molecular relaxation, and the relaxation time constant depends on the content of PVA in the blends.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1552-1555
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation and speed of sound in the systems containing beta-cyclodextrin
    Autorzy:
    Jerie, K.
    Baranowski, A.
    Burakowski, A.
    Gliński, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/146303.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    sound speed
    compressibility
    positron annihilation
    cyclodextrin
    alcohol
    inclusion compounds
    Opis:
    Positron annihilation measurements were performed in aqueous solutions of beta-cyclodextrin, as well as in solid mixtures of this sugar with a long-chained alcohol, n-nonanol. Additionally, acoustic (sound speed, density and compressibility) experiments were done in aqueous beta-cyclodextrin and tert-butanol systems and in a three-component water-beta-cyclodextrin-tert-butanol system. The results show that in aqueous solution cyclodextrin does not form inclusive complexes with alcohol, while solid sugar-alcohol mixtures undergo slow changes in time, most probably caused by exchange of guest between interior and exterior of the host molecule.
    Źródło:
    Nukleonika; 2010, 55, 1; 65-68
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation in bioactive glass/poly(glycolide-co-L-lactide) composites
    Autorzy:
    Dryzek, E.
    Cholewa-Kowalska, K.
    Pamuła, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/146311.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    poly(glycolide-co-L-lactide)
    bioglass
    composites
    positron annihilation
    Opis:
    Composites made of bioactive glasses and resorbable polymers are promising biomaterials for bone tissue regeneration. In this study several types of composites produced from bioactive glasses, differing in chemical composition (A2 and S2) and poly(glycolide-co-lactide) (PGLA) were obtained. The resulting composite materials were investigated with positron lifetime spectroscopy and Doppler broadening of annihilation line. It was found that for the composites made of S2 bioglass the intensity of the third positron lifetime component coming from the positronium (Ps) annihilation decreased with increasing in volume fraction of bioglass particles exhibiting behaviour characteristic of microcomposites. For the composites produced from A2 bioglass, such a dependence was not found. The differences obtained may be connected with chemical composition of the bioglass and/or its crystallinity.
    Źródło:
    Nukleonika; 2010, 55, 1; 79-83
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of heat treatment on point defect concentration in Fe-Al and Fe-Al-Cr systems
    Autorzy:
    Kansy, J.
    Hanc, A.
    Giebel, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/146336.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    Fe-Al
    Fe-Al-Cr
    point defects
    Opis:
    FeAl alloys of nominal Al content 28, 38 and 45 at.% and Fe28Al5Cr with minor alloying elements added to improve their application properties are studied by positron annihilation lifetime analysis. The lifetime spectra of samples FeXAl with X greater-than or equal to 38 (both quenched and cooled with furnace) are described by a single lifetime component related to the saturated positron trapping by quenched-in vacancies of concentration much higher than 100 ppm. A very strong dependence of retained vacancy concentration on the rate of cooling is shown for Fe28Al and Fe28Al5Cr alloys. After quenching, the concentration is of the order of 10.4 whereas in samples slowly cooled it is reduced to 10.5. The chromium addition to Fe28Al5Cr dismisses the vacancies concentration in comparison to the concentration in Fe28Al after the same heat treatment.
    Źródło:
    Nukleonika; 2010, 55, 1; 21-25
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monte Carlo calculations of positron implantation profiles and backscattering probabilities in gold
    Autorzy:
    Aydin, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/147555.pdf
    Data publikacji:
    2001
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    backscattering
    computer simulation
    incoming angle
    mean penetration depth
    positron
    Opis:
    The transport of charged particles through matter is worth considering for various applications. In this work, backscattering probabilities and mean penetration depths were calculated from the implantation profiles for positrons of energies 1-75 keV entering normally at various angles into a semi-infinite gold target. The theoretical results of backscattering probability and mean penetration depth are compared with other published [1, 3, 4, 10, 11, 13]. Monte Carlo calculations and experimental results for the semi-infinite gold target. In general, good agreement is observed.
    Źródło:
    Nukleonika; 2001, 46, 3; 87-90
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spektroskopia anihilacji pozytonow w Zjednoczonym Instytucie Badań Jądrowych w Dubnej
    Positron Annihilation Spectroscopy at Joint Institute for Nuclear Research in Dubna
    Autorzy:
    Horodek, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/214281.pdf
    Data publikacji:
    2016
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    spektroskopia anihilacji pozytonów
    defekty struktury krystalicznej
    wiązka powolnych pozytonów
    przykłady zastosowań
    positron annihilation spectroscopy
    lattice defects
    slow positron beam
    examples of application
    Opis:
    W artykule przedstawiono spektroskopię anihilacji pozytonów, jako metodę dedykowaną do badań defektów struktury krystalicznej. Omówiono jej podstawy fizyczne i zaprezentowano technikę dopplerowskiego poszerzenia linii anihilacyjnej. Wskazano zakres stosowalności odnosząc się do najnowszych rozwiązań opartych na tzw. wiązkach powolnych pozytonów. Idea takiej wiązki, działającej w Laboratorium Problemów Jądrowych im. Dzhelepova w Zjednoczonym Instytucie Badań Jądrowych w Dubnej, została szerzej zaprezentowana. Przedstawiono zasadę działania oraz przykłady zastosowań z podstawami analizy otrzymywanych wyników.
    Positron annihilation spectroscopy (PAS) as a method dedicated to study structural defects was presented. Physical basics of PAS and the Doppler broadening of annihilation line technique were discussed. Application range based on the newest technology, namely slow positron beams was presented. The idea of the beam, working at Dzhelepov Laboratory of Nuclear Problems at Joint Institute for Nuclear Research, along with the basic analysis of the results were described in details.
    Źródło:
    Postępy Techniki Jądrowej; 2016, 2; 18-23
    0551-6846
    Pojawia się w:
    Postępy Techniki Jądrowej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of free volumes and light transmission in hydrogel and silicone-hydrogel polymer contact lenses
    Autorzy:
    Kocela, A.
    Miedzinski, R.
    Filipecka, K.
    Filipecki, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/173601.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    positron annihilation
    UV-vis-NIR
    polymers
    contact lenses
    free volume
    Opis:
    The free volume holes and light transmission of hydrogel and silicone-hydrogel polymer contact lenses were investigated. As the material, the Proclear family (omafilcon A) of hydrogel contact lenses and the Biofinity family (comfilcon A) of silicone-hydrogel contact lenses were used. Positron annihilation lifetime spectroscopy was used to characterize geometrical sizes and fractions of the free volume holes in the investigated samples. There was a clear difference in the size of free volume holes and the fractional free volume between silicone-hydrogel and hydrogel polymer contact lenses. These changes are shown by a thorough analysis of the long-lived component of lifetime of ortho-positronium. At the same time, UV-vis-NIR in the spectral range 200-1000 nm studies were performed on the same samples of contact lenses spectrometry.
    Źródło:
    Optica Applicata; 2016, 46, 1; 35-45
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modification influence on the structural parameters of polymer ophthalmic materials
    Autorzy:
    Chamerski, K.
    Korzekwa, W.
    Miedzinski, R.
    Filipecki, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/174664.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    intraocular lenses
    IOLs
    positron annihilation
    UV-vis-NIR
    polymers
    biomaterials
    Opis:
    Studies on polymer materials used in ophthalmological surgery as intraocular implants are presented in this paper. The material under investigation were brand new lenses provided by Alcon. The first lens, model SA60AT, was the basis structure, whereas the other one, model SN60AT, was a structure with an added modification in the form of a blue light chromophore. Results obtained with the use of the positron annihilation lifetime spectroscopy, as well as UV-vis-NIR methods, showed that the structure modified by the chromophore becomes more packed, while the results obtained by means of the UV-vis-NIR methods showed that the modification restricts the blue light transmission.
    Źródło:
    Optica Applicata; 2016, 46, 1; 47-55
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monte Carlo calculations of low energy positrons in silicon
    Autorzy:
    Aydin, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/148795.pdf
    Data publikacji:
    2005
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    Monte Carlo method
    positron transmission
    backscattering
    angular distribution
    energy distribution
    Opis:
    Theoretical data for positron scattering from a thin silicon film and semi-infinite silicon are presented as a function of incident and outgoing angles and energies. These theoretical data of the scattering processes of low energy positrons penetrating into silicon were performed by Monte Carlo simulation. The simulation is based on the use of different types of differential cross sections for individual elastic and inelastic scattering i) inelastic scattering; Gryzinski's excitation function to simulate the energy loss and Liljequist's model to calculate the inelastic scattering cross section, ii) elastic scattering; the screened Rutherford differential cross section with the spin-relativistic factor. In calculations on positron traversing matter, it is important to know the transmission through medium, their path lengths, and their energy and angular distribution through matter. The simulation results are well agreed with experiments.
    Źródło:
    Nukleonika; 2005, 50, 1; 37-42
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Biodegradable polyester blend and copolyesters studied by positron annihilation and other methods
    Autorzy:
    Dębowska, M.
    Rudzińska-Girulska, J.
    Serwadczak, M.
    Kiersnowski, A.
    Pigłowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/146301.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    mixing of polymers
    polyesters
    transesterification
    positron annihilation
    positronium
    free volume
    Opis:
    Two polyesters, i.e. an aromatic one: poly(butylene terephthalate) – PBT and an aliphatic one: poly(ĺ- -caprolactone) – PCL were mixed in melt to obtain a biodegradable product. DSC, 1H NMR, SEM, WAXS, SAXS, BOD and PALS measurements were performed to study the homopolymers as well as their physical blend and copolyesters. The latter were obtained due to the transesterification reaction. Ortho-positronium (o-Ps) annihilation lifetimes were used to create the distributions of free volume. The progressive changes in probability density function of free volume, i.e. increase in large free volume holes contribution to the total free volume, appearing when going from the homopolymers to the blend and then to the copolyesters reflect the influence of: the addition of aliphatic polyester, the weight fraction of it in the composition and transesterification. The higher contribution of larger free volume holes corresponds well with the reduced crystallinity of compositions revealed in X-ray diffraction and the worsening of the regularity of structure of the macromolecules involved in formation of crystals, deduced from the 1H NMR.
    Źródło:
    Nukleonika; 2010, 55, 1; 57-64
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Development of [66Ga]oxine complex; a possible PET tracer
    Autorzy:
    Jalilian, A.
    Rowshanfarzad, P.
    Sabet, M.
    Rahiminejad-Kisomi, A.
    Rajamand, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/146276.pdf
    Data publikacji:
    2006
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    gallium-66
    oxine
    positron emission tomography
    blood cell labeling
    stability
    Opis:
    The aim of this work is development of a possible blood cell labeling agent for ultimate use in PET. Gallium-66 (T1/2 = 9.49 h) is an interesting radionuclide that has a potential for positron emission tomography (PET) imaging of biological processes with intermediate to slow target tissue uptake. Oxine has been labeled with this radionuclide in the form of [66Ga]gallium chloride for its possible diagnostic properties. In this study, 66Ga was produced at a 30 MeV cyclotron (IBA-Cyclone 30) via the 66Zn(p,n)66Ga reaction. The production yield was 445.5 MBq/mAh. The [66Ga]oxine complex was obtained at pH = 5 in phosphate buffer medium at 37°C in 10 min. Radio-TLC showed a radiochemical purity of more than 98 š 2%. The chemical stability of the complex was checked in vitro with a specific activity of 1113 GBq/mmol. The serum stability and log P of the complex were calculated. The produced [66Ga]oxine can be used for diagnostic studies, due to its desirable physico-chemical properties both in vitro and in vivo according to internationally accepted limits.
    Źródło:
    Nukleonika; 2006, 51, 3; 155-159
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    GEANT4 simulation of implantation profiles for positrons injected in solids from radioactive sources 22Na and 68Ge/68Ga
    Autorzy:
    Horodek, P.
    Dryzek, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/146334.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    implantation profile
    absorption coefficient
    GEANT4 tool kit
    Opis:
    We calculated theoretically the mass absorption coefficients for positrons emitted from the commonly used sources 22Na and 68Ge/68Ga in numerous materials. For this purpose, we used the tool kit GEANT4 which allows to generate the implantation profile. An excellent agreement between the experimental profile and the calculated one was achieved. The calculated values of the mass absorption coefficients coincide well with the experimental values determined by the DSIP method.
    Źródło:
    Nukleonika; 2010, 55, 1; 17-19
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Production of 18F by proton irradiation of C6H6NF and C6H5NF2
    Autorzy:
    Běták, E.
    Mikołajczak, R.
    Staniszewska, J.
    Mikołajewski, S.
    Rurarz, E.
    Wojtkowska, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/147609.pdf
    Data publikacji:
    2011
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    radiopharmaceuticals
    positron emitters
    radiochemistry
    18F
    cyclotron
    production cross section
    Opis:
    Fluorin--18 can be produced directly by the (p,pn) reaction and also indirectly by the (p,2n) reaction on the 19F target. The overall cross section for both routes is 108 plus or minus 20 mb at 22.5 plus or minus 2.5 MeV. In this work, we obtained 18F, using 25 MeV protons on 2\--fluoroaniline and 2,4-difluoroaniline targets. The chemical separation yield was 46 š 7% and 47 plus or minus 12% for 2-fluoroaniline and 2,4-difluoroaniline, respectively. Low-current 1 h irradiations led to 90 mi Ci of 18F produced from 2-fluoroaniline bombarded with a 70 nA beam (in good agreement with the theoretical value, 96 mi Ci) and to 76 mi Ci of 18F in case of 2,4-difluoroaniline and a 33 nA beam (prediction 85 mi Ci). Both values are close to the thick target result reported by Dmitriev and Molin [4] for 22 MeV protons.
    Źródło:
    Nukleonika; 2011, 56, 4; 269-276
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation study of iron oxide nanoparticles in mesoporous silica MCM-41 template
    Autorzy:
    Surowiec, Z.
    Wiertel, M.
    Zaleski, R.
    Budzyński, M.
    Goworek, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/148449.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation
    Mössbauer effect
    MCM-41 porous silica
    superparamagnetic nanoparticles
    Opis:
    The subject of investigation were the samples obtained by impregnation of MCM-41 template with an aqueous solution prepared from Fe(NO3)3ź9H2O. As a result of such a procedure, iron oxides deposits on MCM-41 were formed. The Mössbauer studies revealed an occurrence of Fe3O4 nanocrystallites in the both ferri- and superparamagnetic states. Almost 80% small particles exist in a paramagnetic state. The positron annihilation lifetime spectroscopy (PALS) spectra were measured in air or in vacuum. The long-lived ortho-positronium (o-Ps) components and their intensities are time dependent due to air molecules interaction with iron oxide nanocrystallites and silica walls surfaces. The adsorption of air on the nanocrystallites surface causes a total screening of their surface and a raise of the o-Ps lifetime values. Observed anti-quenching effect is a result of competition of two phenomena: practically switching off a pick-off mechanism related to interaction of o-Ps with magnetite nanoparticles and considerably weaker usual quenching by paramagnetic oxygen molecules.
    Źródło:
    Nukleonika; 2010, 55, 1; 91-96
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Ultraviolet Absorber on Photo-Degradation of Epoxy Coating Studied by Slow Positron Beam
    Autorzy:
    Wang, Zheng
    Liu, Fuwei
    Li, Jingjing
    He, Chunqing
    Peng, Xiangyang
    Huang, Zhen
    Fang, Pengfei
    Powiązania:
    https://bibliotekanauki.pl/articles/1033239.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    epoxy coating
    photo-degradation
    ultraviolet absorber
    slow positron beam
    microstructure
    Opis:
    The photo-degradation progress of epoxy coating and the effect of ultraviolet absorber under UV-B irradiation have been investigated in slow positron beam and by the Fourier transform infrared spectrometer. After 120 h of irradiation, the value of S parameter in sample bulk is reduced while compared with the virgin sample. The result is mostly due to post-cure process happening in this initial irradiation stage. As the irradiation time increases to 360 h, the S parameter decreases sharply. This is due to the growth of carbonyl group and the generation of free radical. After 528 h or longer time of irradiation, a very low S value was obtained near sample surface, indicating the formation of a dead surface layer. Positron results also reveal that the addition of ultraviolet absorber suppresses the development of the dead layer after long-term UV-B irradiation. Ultraviolet absorber has a suppressing effect on generation of polar groups towards sample bulk. The addition of ultraviolet absorber is a key factor that affects the photo-degradation of epoxy coating.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1523-1526
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nuclear data for the cyclotron production of 66Ga, 86Y, 76Br, 64Cu and 43Sc in PET imaging
    Autorzy:
    Sadeghi, M.
    Enferadi, M.
    Aref, M.
    Jafari, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/148630.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    production yields
    excitation function
    positron emitters
    ALICE/ASH
    TALYS-1.2
    Opis:
    Positron emission tomography (PET) is a powerful diagnostic tool, which provides superior spatial resolution and an opportunity to obtain quantitative information concerning distribution of radioactivity in vivo. Most interesting positron emitters for the purpose of diagnose are 64Cu, 124I, 18F, 86Y, 48V, 52Mn, 140Pr, 72As, 74As, 89Zr, 82Sr, 68Ga, 66Ga, 45Ti, 76Br and 82Rb. Aim of the presented study is to compare the calculated cross sections of several radioisotopes of positron emitters as follows 86Y, 43Sc, 64Cu, 66Ga and 76Br with incident proton energy up to 30 MeV. In this work, excitation function of positron emitters via the 86Sr(p,n)86Y, 43Ca(p,n)43Sc, 66Zn(p,n)66Ga, 64Ni(p,n)64Cu and 76Se(p,n)76Br reactions were calculated by ALICE/ASH 0.1 (GDH model and hybrid model) and TALYS-1.2 (equilibrium and pre-equilibrium) codes and compared to existing data. Requisite for optimal thicknesses of targets were obtained by the stopping and range of ions in matter (SRIM) code for each reaction.
    Źródło:
    Nukleonika; 2010, 55, 3; 293-302
    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:
    PALS investigation of resorcinol under high pressure
    Autorzy:
    Tydda, M.
    Jasińska, B.
    Pieniążek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/147999.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    free volume
    ortho-positronium (o-Ps)
    pressure
    positron annihilation lifetime spectroscopy (PALS)
    Opis:
    Two kinds of measurements were conducted with resorcinol at high pressure : the first one with the use of a mechanical press and the second one with the use of a gaseous compressor. In the second case, due to some gas penetrating the material structure, the lifetime spectra obtained were difficult to analyze. The free volumes in resorcinol were influenced both by high pressure and the gas coming into the crystallographic structure.
    Źródło:
    Nukleonika; 2013, 58, 1; 195-198
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of the free volume sizes and shapes determined from crystallographic and PALS data
    Autorzy:
    Tydda, M.
    Jasińska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/146378.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    benzenediols
    free volume
    molecular crystals olanzapine
    positron annihilation
    positronium
    positronium diffusion coefficient
    Opis:
    Two different classes of molecular crystals were investigated. The first group was benzenediols, which are characterized by the same chemical composition but a different organization of their crystallographic structures; all of the compounds from this group have only one kind of free volumes. The second class was represented by olanzapine, which has more complex chemical composition and two kinds of free volumes in the structure. The o-Ps lifetime values determined from positron annihilation lifetime spectroscopy (PALS) measurements agree quite well with those calculated for sizes found from crystallographic data for benzenediols (agreement within 10% of the lifetime values). For olanzapine, a good agreement is observed in the case of cuboidal free volumes, while for the other kind of void, the agreement is less satisfactory. Positronium diffusion coefficient determined from o-Ps redistribution in olanzapine agrees with these found for polymers.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 771-775
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preliminary design and simulation of a spherical brain PET system (SBPET) with liquid xenon as scintillator
    Autorzy:
    Moghaddam, N. M.
    Karimian, A.
    Mostajaboddavati, S. M.
    Vondervoort, E.
    Sossi, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/146444.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron emission tomography (PET)
    Monte Carlo simulation
    GATE
    liquid xenon
    brain imaging
    Opis:
    Preliminary design of a spherical brain PET (SBPET) using liquid xenon (LXe) as detector is considered in this research work. The major advantage of a spherical design is the large solid angle of acceptance which improves the sensitivity and increases signal-to-noise ratio (SNR) of the image. The use of a liquid active medium enabled us to design a spherical detector. LXe, due to the intrinsic physical properties, is an excellent liquid medium for accurate tracking of gamma rays in the relevant energy range. The performance of SBPET was evaluated by Monte Carlo simulation tools (GATE) and compared to ECAT HRRT. The numerical results showed the SBPET has a sensitivity of 1.14% and spatial resolution of ~2.7 mm FWHM which is superior to ECAT HRRT especially at high-count rates.
    Źródło:
    Nukleonika; 2009, 54, 1; 33-38
    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:
    Zastosowanie PET/CT w neurologii
    PET/CT in neurology
    Autorzy:
    Cegła, Paulina
    Chrapko, Beata
    Pietrasz, Katarzyna
    Cholewiński, Witold
    Powiązania:
    https://bibliotekanauki.pl/articles/986633.pdf
    Data publikacji:
    2019
    Wydawca:
    Indygo Zahir Media
    Tematy:
    pozytonowa tomografia emisyjna
    neurologia
    obrazowanie molekularne
    positron emission tomography
    neurology
    molecular imaging
    Opis:
    Pozytonowa tomografia emisyjna w połączeniu z tomografią komputerową (positron emission tomography/computed tomography, PET/CT) jest techniką dostarczającą informacji na temat różnych procesów zachodzących w ośrodkowym układzie nerwowym (OUN). Pozwala na ocenę metabolizmu glukozy (18F-fluorodeoksyglukoza, 18F-FDG), układu dopaminergicznego (18F-DOPA) czy wychwytu aminokwasów (18F-fluoroetylotyrozyna, 18F-FET). Celem niniejszej pracy jest omówienie zastosowania techniki PET/CT w zaburzeniach neurologicznych w oparciu o analizę piśmiennictwa.
    Positron emission tomography/computed tomography (PET/ CT) is an imaging technique used for assessment of different metabolic processes of central nervous system (CNS). Allows to evaluate glucose metabolism (18F-Fluorodeoxyglucose, 18F-FDG), dopaminergic pathway integrity (18F-dihydroxyphenylalanine, 18F-DOPA) and amino acid uptake (18F-fluoroethylo-thyrosine, 18F-FET). The aim of this review is to discuss the usefulness of the PET/CT method in the neurological disorders based on literature review.
    Źródło:
    Inżynier i Fizyk Medyczny; 2019, 8, 2; 79-83
    2300-1410
    Pojawia się w:
    Inżynier i Fizyk Medyczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    PET and SPECT imaging as a solid guide to detect and discriminate atypical phenotypes of neurodegenerative disorders
    Autorzy:
    Ruffini, Livia
    Zilioli, Alessandro
    Cervati, Veronica
    Lauretani, Fulvio
    Misirocchi, Francesco
    Maggio, Marcello
    Migliari, Silvia
    Graziani, Tiziano
    Cidda, Carla
    Baldari, Giorgio
    Spallazzi, Marco
    Scarlattei, Maura
    Powiązania:
    https://bibliotekanauki.pl/articles/40521373.pdf
    Data publikacji:
    2024-03-30
    Wydawca:
    Uniwersytet Rzeszowski. Wydawnictwo Uniwersytetu Rzeszowskiego
    Tematy:
    atypical phenotypes
    neurodegenerative diseases
    positron emission tomography
    single photon emission computed tomography
    Opis:
    Introduction and aim. Atypical or mixed presentations of neurodegenerative disorders may postpone or confound the final diagnosis. Molecular imaging with positron emission tomography (PET) and single photon emission computed tomography (SPECT) radioligands provide target-specific information and may anticipate the diagnosis by “in vivo” detection of the neuropathological substrate, as Aβ deposition, nigrostriatal dopaminergic depletion or tau inclusions. This concise review will discuss the potential of PET and SPECT imaging as a solid guide to better characterize atypical phenotypes of neurodegeneration in the clinical routine, with the potential to drive personalized interventions, improve cohort uniformity for clinical trials, and serve as biomarkers for targeted molecular therapies. Material and methods. Literature search was performed focusing on the role of PET and SPECT imaging in assessing atypical phenotypes of neurodegeneration, using the electronic source of database PubMed/MEDLINE and the web-based search engines Google, Google Scholar. Analysis of the literature. New disease-modifying drugs may increase their effect with early initiation, which is especially important in working persons and younger subjects presenting atypical symptoms. In older individuals, the coexistence of neurodegeneration, age-related changes, cerebrovascular lesions, or depression makes challenging a definitive diagnosis. Quantitative tools able to measure tracer distribution increase the accuracy of molecular neuroimaging creating topographic maps that compare subject’s data with healthy controls databases. Conclusion. Atypical phenotypes may be associated with quantitative key-pattern allowing a more precise and early diagnosis of the neurodegenerative disorder. Finally, quantitative assessment of the pathological substrates allows us to track the disease process and measure treatment response.
    Źródło:
    European Journal of Clinical and Experimental Medicine; 2024, 22, 1; 201-221
    2544-2406
    2544-1361
    Pojawia się w:
    European Journal of Clinical and Experimental Medicine
    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:
    Studies of unicellular microorganisms Saccharomyces cerevisiae by means of positron annihilation lifetime spectroscopy
    Autorzy:
    Kubicz, E.
    Jasińska, B.
    Zgardzińska, B.
    Bednarski, T.
    Białas, P.
    Czerwiński, E.
    Gajos, A.
    Gorgol, M.
    Kamińska, D.
    Kapłon, Ł.
    Kochanowski, A.
    Korcyl, G.
    Kowalski, P.
    Kozik, T.
    Krzemień, W.
    Niedźwiecki, S.
    Pałka, M.
    Raczyński, L.
    Rajfur, Z.
    Rudy, Z.
    Rundel, O.
    Sharma, N. G.
    Silarski, M.
    Słomski, A.
    Strzelecki, A.
    Wieczorek, A.
    Wiślicki, W.
    Zieliński, M.
    Moskal, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/147902.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    environmental scanning electron microscopy (ESEM)
    free volume
    inverted microscopy
    positron annihilation
    positronium
    yeasts
    Opis:
    Results of positron annihilation lifetime spectroscopy (PALS) and microscopic studies on simple microorganisms, brewing yeasts, are presented. Lifetime of ortho-positronium (o-Ps) were found to change from 2.4 to 2.9 ns (longer-lived component) for lyophilized and aqueous yeasts, respectively. Also hygroscopicity of yeasts in time was examined, allowing to check how water – the main component of the cell – affects PALS parameters, thus lifetime of o-Ps were found to change from 1.2 to 1.4 ns (shorter-lived component) for the dried yeasts. The time sufficient to hydrate the cells was found below 10 hours. In the presence of liquid water, an indication of reorganization of yeast in the molecular scale was observed. Microscopic images of the lyophilized, dried, and wet yeasts with best possible resolution were obtained using inverted microscopy (IM) and environmental scanning electron microscopy (ESEM) methods. As a result, visible changes to the surface of the cell me mbrane were observed in ESEM images.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 749-753
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Photoluminescence and positron annihilation lifetime studies on pellets of ZnO nanocrystals
    Autorzy:
    Karbowski, A.
    Fedus, K.
    Patyk, J.
    Bujak, Ł.
    Służewski, K.
    Karwasz, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/148001.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    photoluminescence (PL)
    positron annihilation lifetime spectroscopy (PALS)
    X-ray diffraction (XRD)
    ZnO nanocrystals
    Opis:
    We explore the interrelationships between the X-ray diffraction patterns, the photoluminescence spectra and the positron lifetimes obtained from circular pellets composed of commercial ZnO nanoparticles. The experimental results are studied as a function of thermal treatment at different temperatures. X-ray diffractograms reveal the temperature- independent wurtzite phase structure of nanocrystals and show huge enlargement of ZnO grains after annealing at temperatures higher than 700 centigrade. Photoluminescence measurements exhibit two emission bands : a near band edge emission in UV (small tilde 378 nm) and a defect-related broad visible peak with a maximum in the green region ( small tilde 502 nm). The significant enhancement of the green emission at the expense of UV luminescence is observed after sample sintering at 800 and 1000 centigrade. The positron annihilation lifetime spectroscopy (PALS) is applied in order to study the thermally induced evolution of defects. The lifetime components show a step-like dependence on the thermal treatment, but do not follow exactly the variation in crystallographic phases and only vaguely follow differences in photoluminescence. The positron data indicate therefore some additional structural and/or defect changes. The possible origin of green luminescence from ZnO pellets is discussed.
    Źródło:
    Nukleonika; 2013, 58, 1; 189-194
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Porosity structure in photon active glasses
    Autorzy:
    Jasińska, B.
    Śniegocka, M.
    Reisfeld, R.
    Zigansky, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/147953.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    glass
    ortho-positronium (o-Ps)
    porosity
    positron annihilation lifetime spectroscopy (PALS)
    sol-gel technique
    Opis:
    Two kinds of photon active glasses were investigated using positron annihilation lifetime spectroscopy (PALS). Both kinds of glasses were prepared using a sol-gel technique, doped by complex of ruthenium tris bipyridyl chloride. Glasses differed from the initial matrix: the first one was prepared using silicon oxide while the second one - zircon oxide. The ortho-positronium (o-Ps) lifetime and intensities were determined from lifetime spectra. Different porosity structure concluded from PALS measurements was found in both cases. In the silica based glasses small free volumes (angstrom size) and pores (from 1 to 10 nm) existed in the material. On the contrary, in zirconia based glasses small intermolecular voids were produced in the structure only, independently of the way of material preparation.
    Źródło:
    Nukleonika; 2013, 58, 1; 241-244
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    PALS investigations of matrix Vycor glass doped with molecules of luminescent dye and silver nanoparticles. Discrepancies from the ETE model
    Autorzy:
    Gorgol, M.
    Jasińska, B.
    Reisfeld, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/147152.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    positron annihilation lifetime spectroscopy (PALS)
    porous glass
    lumogen dye ROT-305
    silver nanoparticles
    Vycor glass
    Opis:
    A thermal stability of three materials: undoped reference Vycor glass, glass filled with ROT-305 red dye, and silver nanoparticles was investigated by positron annihilation lifetime spectroscopy (PALS) in a broad temperature range (from 93 to 473 K). The attempt of pore size calculations from the ortho-positronium lifetime data was performed using the extended Tao-Eldrup (ETE) model. Below room temperature, a significant decrease in lifetime values of the longest-lived component was found for all the samples. This effect could not be explained by thermal shrinkage of the material and is probably caused by interaction of -Ps with a Vycor glass matrix. The greatest discrepancy from the ETE model predictions was observed for the reference glass. Doping the base material with dye molecules and silver nanoparticles resulted in similar small decrease in this discrepancy. After reheating the samples to the room temperature, the PALS components returned to the initial values. In the temperature range of 293–473 K, quite good agreement between PALS results and the ETE model predictions was observed for the reference glass and the glass incorporated with dye molecules. The observed small discrepancy in this range could possibly be partly explained by thermal expansion of the material. For the glass doped with silver nanoparticles, a significant change in PALS parameters was observed in the temperature range from 403 to 473 K.
    Źródło:
    Nukleonika; 2015, 60, No. 4, part 1; 717-720
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Badanie wpływu domieszki Gd na stopień zdefektowania struktury szkła tellurowego
    Studying influence of element Gd on voids degree of structure the tellurite glass
    Autorzy:
    Filipecki, J.
    Golis, E.
    Kotynia, K.
    Chamerski, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/168534.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Ceramiki i Materiałów Budowlanych
    Tematy:
    szkła tellurowe
    defekty
    anihilacja
    spektroskopia czasów życia pozytonu
    tellurite glasses
    defects
    annihilation
    positron lifetime spectroscopy
    Opis:
    Materiałem badawczym było szkło tellurowe. Badaniom poddano szkło bazowe TeO2-P2O3-ZnO-LiNbO3 oraz szkło domieszkowane gadolinem (TeO2-P2O3-ZnO-LiNbO3)(Gd2O3). W celu dokonania analizy własności strukturalnych wykorzystano metodę pomiarów czasów życia pozytonów PALS (Positron Annihilation Lifetime Spectroscopy). W proponowanej metodzie możliwa jest identyfikacja defektów strukturalnych trudnych do wychwycenia innymi tradycyjnymi metodami pomiarowymi. Przeprowadzone badania wykazały istnienie dwóch składowych czasów życia pozytonów τ1 i τ2. W oparciu o model dwustanowy obliczono parametry wychwytu pozytonów, które pozwalają wyciągnąć wnioski o charakterze i stopniu zdefektowania badanych szkieł tellurowych.
    The tellurite glass such as: TeO2-P2O3-ZnOLiNbO3 as a reference glass and (TeO2-P2O3-ZnO-LiNbO3)(Gd2O3) has been studied. The positron lifetime PALS (Positron Annihilation Lifetime Spectroscopy) was used to analyze the structural properties of tellurite glasses. The proposed method, can identify structural defects which are difficult to capture by other traditional methods. The study showed the existence of two components τ1 and ττ. The basis of the two-state model parameters were calculated capture of positrons, which allow you to draw conclusions about the nature and degree of defect studied tellurite glasses.
    Źródło:
    Szkło i Ceramika; 2015, R. 66, nr 1, 1; 17-19
    0039-8144
    Pojawia się w:
    Szkło i Ceramika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Estimate of the Crystallite Size for Nanocrystalline AISI 316L Stainless Steel and Armco Iron Processed by Hydrostatic Extrusion Using Variable Energy Positron Beam
    Autorzy:
    Sarnek, M.
    Dryzek, E.
    Horodek, P.
    Pachla, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/1033950.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    stainless steel
    Armco iron
    plastic deformation
    hydrostatic extrusion
    variable energy positron beam
    X-ray diffraction
    Opis:
    The paper presents the results of research of nanocrystalline AISI 316L type stainless steel and nanocrystalline Armco pure iron processed by severe plastic deformation using hydrostatic extrusion method. Surface and subsurface of the steel samples extruded at different pressure were investigated using variable energy positron beam. It enabled us to determine the positron diffusion length and compare its values with those for annealed AISI 304 stainless steel. Furthermore positron lifetime and microhardness were measured for all the samples and X-ray diffraction was used to estimate the crystallite size.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1598-1601
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    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:
    Track Effects in Positronium Formation
    Autorzy:
    Stepanov, S.
    Byakov, V.
    Duplâtre, G.
    Stepanov, P.
    Bokov, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030026.pdf
    Data publikacji:
    2017-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    positron
    positronium
    annihilation
    ion-electron recombination
    solvation
    mobility
    external electric field
    track effects
    polar and nonpolar liquids
    Opis:
    We discuss some aspects important for interpretation of the Ps formation process in liquids and molecular media: (1) inhomogeneity of intratrack reactions and parameters of the e⁺ track, (2) final states of e⁺, its solvation in polar and nonpolar liquids, relation to e⁺ mobility, (3) quasi-neutrality of the e⁺ blob and its ambipolar outdiffusion, (4) appearance of the "in-blob" and "out-of-the-blob" positron fractions, and (5) electric field effect on Ps formation.
    Źródło:
    Acta Physica Polonica A; 2017, 132, 5; 1461-1465
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Positron annihilation study of structural relaxation and crystallization of glassified milk fat
    Autorzy:
    Rashevskaya, T.
    Guly, I.
    Pryadko, M.
    Nishchenko, M.
    Likhtorovich, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/25394.pdf
    Data publikacji:
    2000
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    positron annihilation technique
    milk fat
    physical property
    plasticity
    consistency
    crystallization
    nutrition product
    butter
    amorphism
    consistence zob.consistency
    crystalline
    elasticity
    Źródło:
    International Agrophysics; 2000, 14, 2
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    PF-6 an effective plasma focus as a source of ionizing radiation and plasma streams for application in material technology, biology and medicine
    Autorzy:
    Gribkov, V.
    Dubrovsky, A.
    Scholz, M.
    Jednorog, S.
    Karpiński, L.
    Tomaszewski, K.
    Paduch, M.
    Miklaszewski, R.
    Pimenov, V.
    Ivanov, L. I.
    Dyomina, E. V.
    Maslyaev, S. A.
    Orlova, M. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/147424.pdf
    Data publikacji:
    2006
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    dense plasma focus (DPF)
    ion beam
    plasma beam
    X-ray beams
    surface damage
    microlithography
    radioenzymology
    positron emission tomography (PET)
    Opis:
    A review of results on the design and operation of the new efficient Dense Plasma Focus device PF-6 of medium size (transportable) having bank energy of ca. 7 kJ and possessing a long lifetime is presented. New data on the interaction of the pulsed fast ion beams and dense plasma streams generated at this apparatus with various materials are given. These results are compared with the analogous information received at the biggest facility PF-1000. It is shown that it is possible to have about the same power flux density (in the range of 105 109 W/cm2) in both devices however in different areas. Doses of soft X-rays produced by the device within the resists for the goals of microlithography and micromachining appear to be several times less that it is with the conventional X-ray tube. In biological application of this device, medium- and hard-energy X-rays are exploited in the field of radioenzymology. It was found that the necessary dose producing activation/inactivation of enzymes can be by several orders of magnitude lower if used at a high-power flux density in comparison with those received with isotope sources. In medicine, short-life isotope production for the goals of the positron emission tomography (medicine diagnostics) is possible by means of the fast ions generated within DPF. All these experiments are discussed in the framework of pulsed radiation physics and chemistry in its perfect sense thereto the criteria are formulated.
    Źródło:
    Nukleonika; 2006, 51, 1; 55-62
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analiza porównawcza struktury wewnętrznej implantów hydrofilowych oraz hydrofobowych stosowanych w chirurgii okulistycznej metodą spektroskopii czasów życia pozytonów
    Comparative analysis of internal structures of hydrophilic and hydrophobic implants applied in ophthalmology by means of positron annihilation lifetime spectroscopy
    Autorzy:
    Chamerski, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/134780.pdf
    Data publikacji:
    2015
    Wydawca:
    ADVSEO
    Tematy:
    soczewki wewnątrzgałkowe
    anihilacja pozytonów
    wolna objętość
    wielozadaniowość
    hydrofilowość
    hydrofobowość
    chromofory
    intraocular lenses
    positron annihilation
    free volume
    multivacancies
    hydrophilicity
    hydrophobicity
    chromophores
    Opis:
    In presented work internal structures of intraocular lenses were analyzed in terms of defectiveness degree. Studies were conducted by means of positron annihilation lifetime spectroscopy method PALS. The aim of the work was determination of basic parameters describing annihilation centers in research materials, such as positron lifetime in bulk material, mean positron lifetime in the internal structure, positron trapping rate by trapping centers as well as free volumes dimensions. In obtained results differences in free volumes and positron traps concentrations between hydrophilic and hydrophobic materials were noted. Furthermore, comparison of materials with and without blue light chromophores revealed differences in positron trapping rate by multivacancy-like free spaces. Achieved results were referenced for mechanical properties of the studied materials.
    Źródło:
    Technical Issues; 2015, 3; 3-10
    2392-3954
    Pojawia się w:
    Technical Issues
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Choroba Bourneville'a-Pringle'a - opis przypadku
    Morbus Bourneville-pringle – case report
    Autorzy:
    Dryla, Przemysław
    Wojtuń, Stanisław
    Gil, Jerzy
    Jałocha, Łukasz
    Wojtkowiak, Marek
    Błaszak, Antoni
    Powiązania:
    https://bibliotekanauki.pl/articles/1031081.pdf
    Data publikacji:
    2008
    Wydawca:
    Medical Communications
    Tematy:
    tuberous sclerosis complex
    bourneville-pringle syndrome
    computer tomography
    positron emission tomography
    endoscopy
    stwardnienie guzowate
    choroba bourneville’a-pringle’a
    tomografia komputerowa
    pozytronowa tomografia emisyjna
    endoskopia
    Opis:
    Tuberous sclerosis complex (TSC), known as Bourneville-Pringle syndrome, is a genetically conditioned multiple organ disease associated with mental retardation and epilepsy. It could be found in any ethnic groups and races in both sexes. It is estimated that about 2 million people suffer from the disease in the world. Clinical manifestations in the disease could be various. Many signs appear along with the natural development of a child. Lesions that could be found in the disease are associated with skin, nervous system, eye bulbs, heart, kidneys, liver and intestines. These could take form of cysts as well as tumours that could become malignant. Histologically these are fibromas, lipomas, myomas or vasolipomyomas. Specific organ lesions do not require histological confirmation. TSC diagnosis could be established on Gomez criteria established on TSC Consensus in Annapolis in 1998. TSC diagnosis could be assumed as final, when two major criteria are met or one major and two minor. There are no pathognomonic signs of TSC. That means many signs should be taken into account, sometimes hard to find in not highly specialized assessment. Many specialists and specific tests should take part in diagnosis establishment (dermatologic, neurologic, oculistic, cardiologic, endoscopic and imaging procedures – USG, CT, MRI, PET-CT). Family background and often assessment of family members is essential for diagnosis establishment. Therapeutic indications for specific organ lesions need individual approach. Treatment of the illness could be only palliative. It is based on surgical procedures of malignant tumours resection and antiepileptic treatment. In the paper authors discuss case of woman with liver lesions. Those weren’t assessed histologically because of the high risk of hemorrhagic complications. Follow-up was planned with use of imaging procedures. Discussed case shows that during decision making process risk assessment of imaging procedures should be taken into account.
    Stwardnienie guzowate (tuberous sclerosis complex, TSC), nazywane chorobą Bourneville’a-Pringle’a to wielo-narządowa choroba uwarunkowana genetycznie, związana z upośledzeniem umysłowym i padaczką. Spotykane jest we wszystkich grupach etnicznych i rasowych, jednakowo często u obojga płci. Szacuje się, że występuje u około 2 milionów osób na świecie. Zmienność obrazu klinicznego w stwardnieniu guzowatym jest bardzo duża. Wiele objawów pojawia się wraz z rozwojem dziecka. Zmiany dotyczą głównie skóry oraz układu nerwowego, a także gałek ocznych, serca, nerek, wątroby i jelit. Mogą przyjmować postać torbieli i guzów wykazujących nierzadko tendencję do transformacji w nowotwory złośliwe. Pod względem histopatologicznym są to włókniaki, tłuszczaki, mięśniaki, naczyniakotłuszczakomięśniaki. Poszczególne zmiany narządowe z reguły nie wymagają potwierdzenia histopatologicznego. Diagnoza TSC standardowo stawiana jest na podstawie zmienionych kryteriów Gomeza ustalonych na TSC Consensus Conference w Annapolis w 1998 roku. Rozpoznanie TSC uważa się za ostateczne, gdy spełnione są dwa większe kryteria albo jedno większe i dwa mniejsze. Nie ma patognomonicznych dla TSC objawów, co oznacza, że diagnoza musi uwzględniać liczne objawy, często nieuchwytne w niespecjalistycznym badaniu lekarskim. W rozpoznaniu konieczne są współpraca wielu specjalistów oraz wykonanie badań wielokierunkowych (badanie dermatologiczne, neurologiczne, okulistyczne, kardiologiczne, badania endoskopowe, badania obrazowe - USG, TK, MRI, PET-CT). Kluczowe jest dokładne zebranie wywiadu rodzinnego i nierzadko przebadanie pozostałych członków rodziny. Leczenie chorych ze stwardnieniem guzowatym jest objawowe i polega na chirurgicznym usuwaniu guzów złośliwych i podawaniu leków przeciwpadaczkowych. Zalecenia terapeutyczne dla poszczególnych zmian narządowych wymagają indywidualnego rozpatrzenia. W pracy omówiono przypadek chorej kobiety, u której stwierdzono zmiany ogniskowe wątroby. Chociaż istniało podejrzenie ich złośliwego charakteru, nie zostało ono zweryfikowane histopatologicznie z powodu wysokiego ryzyka powikłań krwotocznych. U pacjentki zaplanowano badania kontrolne z wykorzystaniem badań obrazowych. Omawiany przypadek pokazuje, że czasami w podejmowaniu decyzji trzeba uwzględnić ryzyko stosowanych metod diagnostycznych.
    Źródło:
    Pediatria i Medycyna Rodzinna; 2008, 4, 3; 189-194
    1734-1531
    2451-0742
    Pojawia się w:
    Pediatria i Medycyna Rodzinna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Interpolation-based reconstruction methods for tomographic imaging in 3D positron emission tomography
    Autorzy:
    Li, Y.
    Kummert, A.
    Boschen, F.
    Herzog, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/908045.pdf
    Data publikacji:
    2008
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    rekonstrukcja tomograficzna
    interpolacja dwuwymiarowa
    twierdzenie o przekroju Fouriera
    szereg rozdzielczy
    tomographic reconstruction
    three-dimensional positron emission tomography
    Fourier slice theorem
    frequency sample distribution
    two-dimensional interpolation
    inverse distance weighting
    gridding method
    Opis:
    Positron Emission Tomography (PET) is considered a key diagnostic tool in neuroscience, by means of which valuable insight into the metabolism function in vivo may be gained. Due to the underlying physical nature of PET, 3D imaging techniques in terms of a 3D measuring mode are intrinsically demanded to assure satisfying resolutions of the reconstructed images. However, incorporating additional cross-plane measurements, which are specific for the 3D measuring mode, usually imposes an excessive amount of projection data and significantly complicates the reconstruction procedure. For this reason, interpolation-based reconstruction methods deserve a thorough investigation, whose crucial parts are the interpolating processes in the 3D frequency domain. The benefit of such approaches is apparently short reconstruction duration, which can, however, only be achieved at the expense of accepting the inaccuracies associated with the interpolating process. In the present paper, two distinct approaches to the realization of the interpolating procedure are proposed and analyzed. The first one refers to a direct approach based on linear averaging (inverse distance weighting), and the second one refers to an indirect approach based on two-dimensional convolution (gridding method). In particular, attention is paid to two aspects of the gridding method. The first aspect is the choice of the two-dimensional convolution function applied, and the second one is the correct discretization of the underlying continuous convolution. In this respect, the geometrical structure named the Voronoi diagram and its computational construction are considered. At the end, results of performed simulation studies are presented and discussed.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2008, 18, 1; 63-73
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Polypropylene/polyhedral oligomeric silsesquioxane nanocomposites – study of free volumes, crystallinity degree and mass flow rate
    Nanokompozyty polipropylen/poliedryczne oligomeryczne silseskwioksany – badania objętości swobodnych, stopnia krystaliczności oraz masowego wskaźnika szybkości płynięcia
    Autorzy:
    Niemczyk, A.
    Dziubek, K.
    Czaja, K.
    Szatanik, R.
    Szołyga, M.
    Dutkiewicz, M.
    Marciniec, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/947285.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
    Tematy:
    nanocomposites
    polypropylene
    polyhedral oligomeric silsesquioxanes (POSS)
    positron annihilation lifetime spectroscopy (PALS)
    crystallinity degree
    mass flow rate
    polipropylen
    poliedryczne oligomeryczne silseskwioksany (POSS)
    spektroskopia czasów życia pozytonów (PALS)
    stopień krystaliczności
    masowy wskaźnik szybkości płynięcia
    nanokompozyty
    Opis:
    Polypropylene/polyhedral oligomeric silsesquioxane (PP/POSS) nanocomposites were prepared by the melt blending method. Positron Annihilation Lifetime Spectroscopy (PALS) was used to study the effects of the structure and of the amount of POSS on the free volumes in PP. The PALS parameters: o-Ps lifetime and its intensity, were compared to the crystallinity degree and to the mass flow rate (MFR) of nanocomposites. The presence of POSS nanofillers affected the PP microstructure and the size and number of free volumes in the polymer. The crystallinity degree was decreased and the intensity of o-Ps component was increased by increasing POSS contents. The MFR values increased for nanocomposites, thus POSS nanoparticles can act as plasticizers and generate more free volumes in PP.
    Nanokompozyty polipropylen/poliedryczne oligomeryczne silseskwioksany (PP/POSS) przygotowano metodą mieszania w stanie stopionym polimeru. Wpływ struktury oraz ilości zastosowanych nanonapełniaczy POSS na objętości swobodne w polipropylenie określono z zastosowaniem spektroskopii czasów życia pozytonów (PALS). Ustalono zależności pomiędzy parametrami PALS: czasem życia o-Ps (τ3) inatężeniem (I3) składowej o-Ps oraz wartościami stopnia krystaliczności (Xc) i masowego wskaźnika szybkości płynięcia (MFR) badanych materiałów. Obecność nanonapełniaczy POSS wpłynęła na liczbę i rozmiary objętości swobodnych w polimerze, co spowodowało zmianę mikrostruktury osnowy polipropylenowej. Wraz ze zwiększaniem zawartości napełniaczy POSS zmniejszał się stopień krystaliczności kompozytów, zwiększało natężenie składowej o-Ps, adodatkowo wzrastała wartość MFR – nanocząstki POSS pełniły w układzie rolę plastyfikatorów.
    Źródło:
    Polimery; 2016, 61, 9; 610-615
    0032-2725
    Pojawia się w:
    Polimery
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    International Linear Collider Global and Local Implications
    Autorzy:
    Romaniuk, R. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/226596.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ILC
    ILC-GDE
    LCC
    SRF
    accelerators
    particle colliders
    linacs
    superconductivity
    high energy physics experiments
    elementary particles
    hadrons
    electron beams
    positron beams
    microwave resonant cavities
    high power 1,3 GHz systems
    superconducting RF electronics
    Opis:
    ILC machine–International Liner Collider, is one of two accelerators e+e-just under design and advanced consideration to be built with final energy of colliding electron and positron beams over 1 TeV. An alternative project to ILC is CLIC in CERN The ILC machine is an important complementary addition for the research potential of the LHC accelerator complex. The required length of ILC is minimally 30 km, but some versions of the TDR estimates mention nearly 50km. Superconducting RF linacs will be built using well established 1,3 GHz TESLA technology using ultrapure niobium or Nb3Sn resonant microwave cavities of RRR class, of ultimate finesse, working with gradients over 35MV/m, while some versions of the design mention ultimate confinement as high as 50MV/m. Several teams from Poland (Kraków. Warszawa, Wrocław – IFJ-PAN, AGH, UJ, NCBJ, UW, PW, PWr, INT-PAN) participate in the global design effort for this machine – including detectors, cryogenics, and SRF systems. Now it seems that the ILC machine will be built in Japan, during the period of 2016-2026. If true, Japan will turn to a world super-power in accelerator technology no.3 after CERN and USA. The paper summarizes the state-of-the-art of technical and administration activities around the immense ILC and CLIC machines, with emphasis on potential participation of Polish teams in the global effort of newly established LCC –The Linear Collider Consortium.
    Źródło:
    International Journal of Electronics and Telecommunications; 2014, 60, 2; 181-185
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-81 z 81

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