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    Wyświetlanie 1-12 z 12
    Tytuł:
    Study on radiation-induced radicals giving rise to stable EPR signal suitable for the detection of irradiation in L-sorbose-containing fruits
    Autorzy:
    Guzik, G. P.
    Stachowicz, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/146498.pdf
    Data publikacji:
    2016
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    sorbose
    crystallite
    electron paramagnetic resonance (EPR)
    EPR
    irradiation
    Opis:
    The stable and complex EPR signals produced by the action of ionizing radiation on crystalline L-sorbose (C6H12O6) separated from rowan berries (Sorbus aucuparia) were studied. Isothermal heating of the samples at the temperature close to the melting point of L-sorbose (140°C) results in the modification and simplification of the EPR signal involved. In the EPR signal of heated L-sorbose, the isotropic quartet was distinguished. In the differential spectrum obtained by subtraction of normalized spectra of unheated and heated L-sorbose, the isotropic doublet was identified in addition. The DFT fitting offers the probable assignment of the EPR signals to specifi c radical structures.
    Źródło:
    Nukleonika; 2016, 61, 4; 461-465
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Alanine dosimetry of 60 MeV proton beam - preliminary results
    Autorzy:
    Michalec, B.
    Mierzwińska, G.
    Sowa, U.
    Ptaszkiewicz, M.
    Nowak, T.
    Swakoń, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/146730.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    alanine
    dosimetry
    electron paramagnetic resonance (EPR)
    proton beam
    Opis:
    Electron paramagnetic resonance (EPR) spectrometry (X-band) was used to determine the dose absorbed in alanine detectors, of different shapes and different alanine content, irradiated with Co-60 gamma rays and in a 60 MeV proton beam. The goal of our study was to confirm applicability of alanine as a passive detector in therapeutic proton beam. In the paper dose response characteristic and relative efficiency of alanine are shown. The study confirmed that alanine detectors with a high alanine content (ca. 95%) may be a useful and convenient tool for dose measurements in proton beams, used for eye cancer treatment.
    Źródło:
    Nukleonika; 2012, 57, 4; 503-506
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Identification of irradiated dried fruits using EPR spectroscopy
    Autorzy:
    Guzik, G. P.
    Stachowicz, W.
    Michalik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/148844.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    dried fruits
    electron paramagnetic resonance (EPR)
    fructose
    glucose
    irradiation
    Opis:
    The dominating carbohydrates in fruits are monosaccharides like fructose, glucose, sorbose and mannose. In dehydrated fruits, concentration of monosaccharides is higher than in fresh fruits resulting in the formation of sugar crystallites. In most of dried fruits, crystalline fructose, and glucose dominate and appear in proportion near to 1:1. Irradiation of dried fruits stimulates radiation chemical processes resulting in the formation of new chemical products and free radicals giving rise to multicomponent EPR signal which can be detected for a long period of time. For that reason, it is used as a marker for the detection of radiation treatment of dried fruits. It has been found that EPR spectra recorded in dried banana, pineapple, papaya, and fig samples resemble the EPR spectrum obtained by computer addition of fructose and glucose spectra taken in proportion 1:1. The decay of radiation induced EPR signals proceeds in dried fruits fast during the first month of observation and becomes much slower and almost negligible after prolonged storage. However, it remains intense enough for EPR detection even one year after processing. The radiation induced EPR signal is easily detected in dried fruits exposed to 0.5 kGy of gamma rays. Thus, the EPR method of the detection of irradiated fruits can be used for the control of dried fruits undergoing quarantine treatment with 200–300 Gy of ionizing radiation.
    Źródło:
    Nukleonika; 2015, 60, No. 3, part 2; 627-631
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of the fraction of paramagnetic centers not-fulfilling the Curie law in coal macerals by the two-temperature EPR measurement method
    Autorzy:
    Słowik, G. P.
    Więckowski, A. B.
    Powiązania:
    https://bibliotekanauki.pl/articles/146892.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electron paramagnetic resonance (EPR)
    macerals
    two-temperature EPR measurement
    Opis:
    Two-temperature electron paramagnetic resonance (EPR) measurements, applied to determine the relative contributions of paramagnetic centers – fulfilling and not-fulfilling the Curie law, were carried out. The measurements were made on the macerals – exinite and vitrinite, separated from clarain of the Polish medium- -rank coal (85.6 wt% C). The two-temperature EPR measurements, presented in this work, were performed respectively, at temperatures: T1 = 293 K and T2 = 173 K for exinite, and T1 = 293 K and T2 = 153 K for vitrinite. The relative contributions X of spins not-fulfilling the Curie law present in the studied macerals were calculated. A comparison of different methods of calculating the relative contributions of paramagnetic centers – fulfilling and not-fulfilling the Curie law, present in exinite and vitrinite studied by EPR was made.
    Źródło:
    Nukleonika; 2015, 60, No. 3, part 1; 389-393
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR measurements of ceramic cores used in the aircraft industry
    Autorzy:
    Stefaniuk, I.
    Rogalska, I..
    Potera, P.
    Wróbel, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/148814.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    Al2O3
    electron paramagnetic resonance (EPR)
    mullite
    nanopowders
    Opis:
    In this work the electron paramagnetic resonance (EPR) spectra of Al2O3 and ZrO2 powders were measured for different size of grains (0.074, 0.044 mm) as well as the mullites (0.07 and 0.12 mm). Also were investigated the ceramic cores. The measurements were performed at room temperature and in the temperature range from 140 up to 380 K. The main purpose of this work was to investigate the possible relationships between the EPR spectra and the size of powder grains as well as the identification of EPR spectra in view of the potential application of EPR technique as a fingerprinting method.
    Źródło:
    Nukleonika; 2013, 58, 3; 391-395
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Localized states in nanocarbons
    Autorzy:
    Kempiński, W.
    Kempiński, M.
    Markowski, D.
    Łoś, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/148234.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    activated carbon fibers (ACF)
    carbon nanotubes
    electron paramagnetic resonance (EPR)
    fullerenes
    Opis:
    Localization phenomenon is studied in different modern nanocarbon materials: pristine C60, C60-fullerides, carbon nanotubes and graphene-based structures in the form of activated carbon fibers built of quantum dot-like basic structural units. Two experimental methods are used to define the localization and population control of spins (charge carriers) in the nanocarbon materials – electron paramagnetic resonance (EPR) and direct current (d.c.) electrical conductivity measurements. Results are discussed in the frame of the possible applications of the aforementioned materials in the molecular electronics or spintronics.
    Źródło:
    Nukleonika; 2013, 58, 3; 371-373
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR study of guanidine zinc sulphate crystals
    Autorzy:
    Gruszka, K.
    Hrabański, R.
    Ozga, J.
    Czapla, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/146384.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electron paramagnetic resonance (EPR)
    zero-field splitting (ZFS)
    transition ions in crystals
    Opis:
    X-band electron paramagnetic resonance (EPR) investigations of Mn2+-doped guanidine zinc sulphate [C(NH2)3]2Zn(SO4)2 – abbreviated as GZS – are presented. The EPR spectrum in the temperature range 273–393 K exhibits a group of five fine structure transitions each splits into six hyperfine components. The angular variation of EPR spectra reveals the presence of only one magnetic complex, which correspond to one distinct site of Mn2+ ions in the crystal lattice. From the observed EPR spectrum, the spin-Hamiltonian parameters have been evaluated. The variation of zero-field splitting (ZFS) parameter, intensity and line width with temperature are measured and discussed.
    Źródło:
    Nukleonika; 2013, 58, 3; 387-390
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR study of ZnO:Co thin films grown by the PLD method
    Autorzy:
    Cieniek, B.
    Stefaniuk, I.
    Virt, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/146744.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electron paramagnetic resonance (EPR)
    diluted magnetic semiconductor (DMS)
    ZnO:Co
    Curie temperature
    Opis:
    We have studied magnetic properties of zinc-oxide composite doped with a relatively high concentration (4%) of Co ions. Samples were obtained by the pulsed laser deposition (PLD) method with different parameters of the laser ablation. For various samples, the power of laser was changed as well as the temperature of sample heating. Electron paramagnetic resonance (EPR) measurements were carried out and temperature dependence of the EPR spectra was obtained. Analysis of the temperature dependences of the integral intensity of EPR spectra was carried out using the Curie-Weiss law. Fitting yields the following values θCW = 150 K and C = 1.6710, where C is the Curie constant, and θCW is the paramagnetic Curie temperature.
    Źródło:
    Nukleonika; 2013, 58, 3; 359-363
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR study on sugar radicals utilized for detection of radiation treatment of food
    Autorzy:
    Guzik, G. P.
    Stachowicz, W.
    Michalik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/146706.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    density functional theory (DFT)
    dried fruits
    electron paramagnetic resonance (EPR)
    irradiation
    mannose
    sorbose
    Opis:
    Radicals produced by ionizing radiation in sugars, the components of dried and raw fruits give rise to stable multicomponent electron paramagnetic resonance (EPR) signals unidentified so far. The subject of the present EPR study is to identify the radicals stabilized in gamma-irradiated crystalline sugars, D(+)mannose and L(-)sorbose extracted from cranberries (Vaccininum oxycoccos) and rowan berries (Sorbus aucuparia), respectively. EPR measurements and density functional theory (DFT) simulations were employed for that purpose.
    Źródło:
    Nukleonika; 2012, 57, 4; 545-549
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Bloch - Siegert shift in the Rabi oscillations on the “dressed” electron spin states
    Autorzy:
    Fedaruk, R.
    Kolasa, A.
    Saiko, A. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/146386.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electron paramagnetic resonance (EPR)
    Bloch-Siegert shift
    Rabi oscillation
    bichromatic field
    dressed state
    spin qubit
    Opis:
    Using electron paramagnetic resonance (EPR) at Rabi frequencies, we study the Bloch-Siegert effect in the coherent dynamics of electron spin states driven by a bichromatic radiation consisting of a transverse microwave (MW) and longitudinal radio frequency (RF) fields. The Rabi oscillations on the electron spin states “dressed” by the MW field are observed at the double resonance, when the MW frequency equals the Larmor frequency of the spin system and the frequency ωrf of the RF field is close to the Rabi frequency ω1 in the MW field. The dispersive (|ωrf – ω1| ~ ωrf, ω1) and near-resonant (ωrf ≈ ω1) regimes are investigated. We demonstrate that the Bloch-Siegert shift increases with increasing RF amplitude and at the fixed RF amplitude it has the largest values in the “low-frequency” (ωrf < ω1) range of the dispersive regime. Experimental results were obtained in the time-resolved EPR for E’1 centres in quartz.
    Źródło:
    Nukleonika; 2013, 58, 3; 375-378
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modification of the hydrogen bonding network at the reversed micelles interface by near infrared radiation
    Autorzy:
    Walski, T.
    Gałecka, T.
    Grzeszczuk-Kuć, K.
    Komorowska, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/148832.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electron paramagnetic resonance (EPR)
    hydrogen bonds
    near infrared radiation (NIR)
    cetyltrimethylammonium bromide (TCAB) reverse micelles
    TEMPO-palmitate spin probe
    water structure modification
    Opis:
    The purpose of this paper is to prove that near infrared radiation (NIR) modifies hydrogen bonds localized in the interface of reversed micelles. The degree of modification of the hydrogen bonds was monitored by TEMPO-palmitate spin probe introduced into the structure of reverse micelles formed by cetyltrimethylammonium bromide (CTAB) (TCAB/phosphate buffer/isooctane/hexanol and TCAB/NaCl/isooctane/hexanol (W = 15)). Electron paramagnetic resonance (EPR) spectra were performed on the argonated samples. The isotropic tumbling correlation time (τc) and the hyperfine coupling constant A+ = h0 – h+1 (h+1, and h0 correspond to the low-, and centre-field lines, respectively) were determined from the EPR spectra as a quantitative measure for monitoring the action of NIR radiation. A+ values depend on the composition of the water pool (1.640 mT for phosphate buffer and 1.630 mT for NaCl). NIR irradiation led to decrease in A+. This parameter reached the same value for both solutions (1.625 ± 0.003 and 1.626 ± 0.003 mT) after exposition to NIR. The tumbling correlation time after exposure to NIR decreased for TCAB/phosphate buffer/ isooctane/hexanol reversed micelles from 2.10 × 10–10 s to 1.44 × 10–10 s but did not change for TCAB/NaCl/isooctane/ hexanol). The results obtained confirm the possibility of modification of the hydrogen bonds by NIR radiation.
    Źródło:
    Nukleonika; 2013, 58, 3; 435-438
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electron paramagnetic resonance studies of manganese and cobalt ions in YAlO3 crystals
    Autorzy:
    Stefaniuk, I.
    Rogalska, I
    Suchocki, A
    Berkowski, M.
    Cieniek, B.
    Potera, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/174068.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    electron paramagnetic resonance (EPR)
    spin Hamiltonian
    Mn2+
    Mn4+
    Co2+
    Fe3+
    Cr3+
    Nd3+ and Er3+ ions
    YAlO3 (YAP) crystals
    Opis:
    The results of X-band electron paramagnetic resonance measurements of Mn2+ and Mn4+ ions in YAlO3 (YAP) crystals in the temperature range 100–300 K are presented. Additionally, we observe electron paramagnetic resonance spectra of unintentional impurities Fe3+ and Cr3+ in YAP crystals. The angular dependence for Mn ions in YAP crystals can be presented. We aim at obtaining a better insight into the spectroscopic properties of paramagnetic Mn centers and structural information about their nearest environment in YAP host and at determining the valence of manganese ion. In this paper we compare electron paramagnetic resonance spectra for Co and Mn ions in YAP crystals.
    Źródło:
    Optica Applicata; 2014, 44, 1; 113-121
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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