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    Wyświetlanie 1-10 z 10
    Tytuł:
    Paramagnetic Centers in DOPA-Melanin-Dihydrostreptomycin Complexes
    Autorzy:
    Buszman, E.
    Pilawa, B.
    Zdybel, M.
    Wrześniok, D.
    Grzegorczyk, A.
    Wilczok, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2043624.pdf
    Data publikacji:
    2005-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.66.Hq
    76.30.Rn
    Opis:
    DOPA-melanin-dihydrostreptomycin complexes with drug concentrations 1×10$\text{}^{-4}$-1×10$\text{}^{-2}$ M were examined by the use of electron paramagnetic resonance spectroscopy at X-band (9.3 GHz). Dihydrostreptomycin was chosen for studies, because this aminoglycoside antibiotic causes strong toxic effects in organism. It was stated that dihydrostreptomycin generates o-semiquinone free radicals with g=2.0038 in melanin. Free radicals formation increases with increase in the antibiotic concentration. Changes of EPR lines with microwave powers pointed out that slow spin-lattice relaxation processes exist in DOPA-melanin and in its complexes with dihydrostreptomycin. The measured EPR lines were homogeneously broadened.
    Źródło:
    Acta Physica Polonica A; 2005, 108, 2; 353-356
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of pH on Paramagnetic Centers in Cladosporium cladosporioides Melanin
    Autorzy:
    Pilawa, B.
    Buszman, E.
    Gondzik, A.
    Wilczyński, S.
    Zdybel, M.
    Witoszyńska, T.
    Wilczok, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2043413.pdf
    Data publikacji:
    2005-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.66.Hq
    76.30.Rn
    Opis:
    Paramagnetic centers in melanin existing in pigmented soil fungi Cladosporium cladosporioides cultured at acidic (4, 5, 6), neutral (7), and alkaline (8) pH were studied by EPR method. o-semiquinone free radicals (g: 2.0032-2.0040) concentration in melanin biopolymer increased for pH from 4 to 6, decreased at pH 7, and reached the maximum value at pH 8. It may be expected that melanin free radicals reactions with small molecules (metal ions, drugs) are the most effective at pH between 6 and 8. Slow spin-lattice relaxation processes exist in the all studied melanin samples.
    Źródło:
    Acta Physica Polonica A; 2005, 108, 1; 147-150
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR Study of Fe$\text{}^{3+}$ Paramagnetic Centers in Doped Triglycine Sulphate Crystals
    Autorzy:
    Łoś, Sz.
    Trybuła, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2030426.pdf
    Data publikacji:
    2002-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Fc
    77.80.-e
    Opis:
    This paper presents EPR study of Fe$\text{}^{3+}$ in triglycine sulphate doped with Fe$\text{}^{3+}$ crystal. Fe$\text{}^{3 +}$ ion is in a high spin state S=5/2. EPR signal can be detected only below 200 K. At 4.2 K the EPR spectrum results from three non-equivalent sites of Fe$\text{}^{3+}$ ions. The spin Hamiltonian: H=β BĝS+D[S$\text{}_{z}^{2}$-(1/3)S(S+1)]+E(S$\text{}_{x}^{2}$-S$\text{}_{y}^{2}$) has been applied to describe the spectrum. The zero field splitting parameter in this case fulfills the condition: D≫hν. An experimental spectrum reflects clearly only two resonance transitions: |±1/2ã (the lowest Kramers doublet) and |±3/2〉 (the middle Kramers doublet). The iron complexes occupy interstitial positions in the crystal with distorted octahedral or tetrahedral co-ordination.
    Źródło:
    Acta Physica Polonica A; 2002, 101, 2; 279-287
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    ESR Studies of Paramagnetic Centers in Pharmaceutical Materials - Cefaclor and Clarithromycin as an Example
    Autorzy:
    Skowronska, A.
    Wojciechowski, M.
    Ramos, P.
    Pilawa, B.
    Kruk, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1490205.pdf
    Data publikacji:
    2012-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.15.La
    87.64.kj
    87.64.kh
    75.10.Dg
    Opis:
    Electron spin resonance (ESR) studies of two antibiotics, Cefaclor and Clarithromycin, have been performed in order to investigate concentration and dynamics of free radicals generated in these compounds due to thermal sterilization. For Cefaclor three combinations of temperature and heating time have been applied: 160°C, 170°C, 180°C for 120 min, 60 min, and 30 min, respectively, according to the pharmaceutical sterilization norm. Clarithromycin has been heated at 160°C for 120 min. The ESR lineshape has been investigated versus microwave power ranging from 2.2 mW to 70 mW. Electron spin-spin relaxation time has been estimated from the ESR lineshape analysis. Concentrations of radicals generated due to different sterilization procedures have been compared with the purpose to select the best sterilization scheme.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 2; 514-517
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of microwave power on EPR spectra of natural and synthetic dental biocompatible materials
    Autorzy:
    Adamczyk, J.
    Ramos, P.
    Pilawa, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/147235.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    EPR
    microwave saturation
    paramagnetic centers
    dental biocompatible materials
    Opis:
    Paramagnetic centers in the two exemplary synthetic and natural dental biocompatible materials applied in implantology were examined by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra were measured in the range of microwave power 2.2–70 mW. The aims of this work were to compare paramagnetic centers concentrations in different dental biocompatible materials and to determine the effect of microwave power on parameters of their EPR spectra. It is the very fi rst and innovatory examination of paramagnetic centers in these materials. It was pointed out that paramagnetic centers existed in both natural (~1018 spin/g) and synthetic (~1019 spin/g) dental biocompatible materials, but the lower free radical concentration characterized the natural sample. Continuous microwave saturation of EPR spectra indicated that faster spin-lattice relaxation processes existed in synthetic dental biocompatible materials than in natural material. Linewidths (ΔBpp) of the EPR spectra of the natural dental material slightly increased for the higher microwave powers. Such effect was not observed for the synthetic material. The broad EPR lines (ΔBpp): 2.4 mT, 3.9 mT, were measured for the natural and synthetic dental materials, respectively. Probably strong dipolar interactions between paramagnetic centers in the studied samples may be responsible for their line broadening. EPR spectroscopy is the useful experimental method in the examination of paramagnetic centers in dental biocompatible materials.
    Źródło:
    Nukleonika; 2015, 60, No. 3, part 1; 449-453
    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:
    Conditions of photodynamic therapy of tumor cells examined by carbonized coal and EPR spectroscopy
    Autorzy:
    Latocha, M.
    Pilawa, B.
    Pietrzak, R.
    Nowicki, P.
    Wachowska, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/284850.pdf
    Data publikacji:
    2008
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
    Tematy:
    centra paramagnetyczne
    PDT
    próby oksymetryczne
    EPR
    paramagnetic centers
    oximetric probes
    Opis:
    Coal samples carbonized at 600°C and TEMPO probes we applied in oximetry. EPR spectra of medium-ranked coal carbonized at 400, 500, and 700 °C were not sensitive to oxygen. Oxygen effects during photodynamic therapy of tumor cells were tested. Oximetric probes were used to examination of singlet oxygen O2 formation in melanotic CRL-1424 tumor cells irradiated by laser (500 mW, Λ = 662 nm) at the presence of photolon as the photosensitizer. Tumor cells were irradiated during 7, 15, and 30 minutes. Changes in EPR spectra of coal probe and TEMPO after excitation of oxygen O2 from triplet ground state (S=1) to diamagnetic singlet (S=0) state were analysed. Measurements of EPR spectra of coal carbonized at 60O°C and TEMPO in: control cell culture, irradiated cells, and cells irradiated at the presence of photolon, were done. After PDT intensity of EPR lines of the used oximetric probes considerably increases. It was proved that the strongest formation of singlet oxygen in the studied cells appears after 15 minutes of laser irradiation.
    Źródło:
    Engineering of Biomaterials; 2008, 11, 73; 6-8
    1429-7248
    Pojawia się w:
    Engineering of Biomaterials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of oxygen O2 on microwave saturation of EPR lines of plants carbonized at 650°c and potential application in medicine
    Autorzy:
    Pilawa, B.
    Bartłomiejczyk, S.
    Krzesińska, M.
    Pusz, S.
    Zachariasz, J.
    Wałach, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/284844.pdf
    Data publikacji:
    2008
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
    Tematy:
    karbonizacja roślin
    elektroniczny rezonans paramagnetyczny
    EPR
    nasycenie mikrofalowe
    centra paramagnetyczne
    oksymetria
    carbonized plants
    electron paramagnetic resonance
    microwave saturation
    paramagnetic centers
    oximetry
    Opis:
    Electron paramagnetic resonance spectroscopy (EPR) was used to examination of spin-lattice relaxation in vascular plants carbonized at 650°C. Application of EPR method of continuous microwave signal saturation in medicine was proposed. The first derivative EPR spectra of pyrolysed bamboo and yucca were measured for samples in air and in vacuum. Influence of microwave power in the range 0.7-100 mW on amplitudes of EPR lines were evaluated. It was stated that amplitudes of the studied carbon materials increase with increasing of microwave power in the studied range. Saturation of EPR lines was not observed, so fast spin-lattice relaxation processes exist in the analyzed materials. Changes of EPR amplitudes for samples in air were slower than for evacuated samples. This effect may be used for determination of oxygen contents in the biological cells cultures and for analysis of optimal parameters of photodynamic therapy of cancer.
    Źródło:
    Engineering of Biomaterials; 2008, 11, 73; 9-11
    1429-7248
    Pojawia się w:
    Engineering of Biomaterials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparatwe EPR analysis of oxygen interactions with plants carbonized at different temperatures
    Autorzy:
    Bartłomiejczyk, S.
    Pilawa, B.
    Krzesińska, M.
    Pusz, S.
    Zachariasz, J.
    Wałach, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/284848.pdf
    Data publikacji:
    2008
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
    Tematy:
    karbonizacja roślin
    centra paramagnetyczne
    paramagnetyczne utlenianie cząsteczek
    elektroniczny rezonans paramagnetyczny
    widma EPR
    oksymetria
    carbonized plants
    paramagnetic centers
    paramagnetic oxygen molecules
    electron paramagnetic resonance
    EPR spectra
    oximetry
    Opis:
    Carbon materials, bamboo (Bambusa vulagris) and yucca (Yucca flaccida) pyrolysed at 550°C, 750°C and 950°C, were tested as oximetric probes by electron paramagnetic resonance spectroscopy at X-band (9.3 GHz). The following parameters of the spectra: amplitude, linewidth and g-factor, were determined. Influence of oxygen molecules 02 on EPR spectra of the individual carbon materials was compared. Strong EPR spectra were recorded for samples carbonized at 550°C and weak signals were obtained for plants carbonized at higher temperatures: 750°C and 950°C. It was stated that amplitudes of EPR lines of all the carbonized plants decrease in the air environment compared to amplitudes of spectra measured in vacuum. This effect increases with degree of vacuum. Changes in the EPR spectra of samples studied in the air environment may be applied in medicine to determination of oxygen content in different cells. Because of strong resonance signals as oximetric probes we proposed bamboo and yucca carbonized at 550°C, and we rejected plants carbonized at 750°C and 950°C with Iow EPR signals.
    Źródło:
    Engineering of Biomaterials; 2008, 11, 73; 3-5
    1429-7248
    Pojawia się w:
    Engineering of Biomaterials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Paramagnetic State of Hydrogen-Passivated Double-Donor Centers in Silicon
    Autorzy:
    Gregorkiewicz, T.
    Zevenbergen, I. S.
    Martynov, Yu. V.
    Ammerlaan, C. A. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933751.pdf
    Data publikacji:
    1995-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    76.30.Lh
    61.72.Bb
    76.70.Dx
    Opis:
    Hydrogenation of two double donor centers in silicon - substitutional sulfur and thermal donor - is studied by electron paramagnetic resonance and electron-nuclear double resonance. For both centers the existence of a new paramagnetic S = 1/2 state identified as the neutral charge state of the double donor passivated with a single hydrogen atom is concluded. The microscopic structure of such complexes is discussed.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 4; 735-738
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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