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Wyszukujesz frazę "electron paramagnetic resonance" wg kryterium: Temat

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    Wyświetlanie 1-8 z 8
    Tytuł:
    Effect of microwave power on EPR spectra of DOPA-melanin-netilmicin complexes with different drug concentrations : a study at temperatures in the range of 125-275 K
    Autorzy:
    Zdybel, M.
    Pilawa, B.
    Buszman, E.
    Wrześniok, D.
    Krzyminiewski, R.
    Kruczyński, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/146482.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    DOPA-melanin
    electron paramagnetic resonance (EPR) spectroscopy
    free radicals
    netilmicin
    Opis:
    Electron paramagnetic resonance (EPR) spectra of the model eumelanin – DOPA-melanin complexes with netilmicin measured with a microwave power in the range 0.3–200 mW were examined. The influence of microwave power on amplitudes (A) and linewidths (ΔBpp) of the spectra was determined. The EPR spectra were recorded by a BRUKER spectrometer at temperatures 125, 175, 225 and 275 K. Continuous microwave saturation of EPR lines was used to compare the acceleration of spin-lattice relaxation processes in melanin samples. Changes of the parameters of the EPR spectra of DOPA-melanin-netilmicin complexes, with the microwave power for the samples differing in netilmicin concentrations, were observed. The effect of temperature on the changes of the EPR spectra of the analyzed melanin complexes with the microwave power was determined. The spin-lattice relaxation is faster at higher temperatures for all the tested melanin complexes.
    Źródło:
    Nukleonika; 2013, 58, 3; 407-411
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR studies of free radicals in thermally sterilized famotidine
    Autorzy:
    Ramos, P.
    Pilawa, B.
    Stroka, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/148414.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    free radicals
    thermal sterilization
    famotidine
    electron paramagnetic resonance (EPR) spectroscopy
    Opis:
    Free radicals formation in thermally sterilized famotidine was studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. The influence of temperature and time of sterilization on free radicals generated in famotidine was determined. The best sterilization conditions for the tested drug were found. Sterilization was done according to the pharmaceutical norms at temperatures 160°C (120 min), 170°C (60 min), and 180°C (30 min). It was pointed out that the optimal temperature of thermal sterilization for famotidine was 170°C and time of heating 60 min in this conditions the lowest free radicals concentration was found. The highest free radicals concentration was measured in famotidine heated at 160°C during 120 min, the long time of sterilization is responsible for this effect. Free radicals concentration changes during storage of famotidine after thermal sterilization. Its value increased with storage time for the drug sterilized at both temperatures of 170°C and 180°C. Free radicals concentration decreases from 7 days after sterilization. Complex system of free radicals with the shape of EPR lines, dependent on microwave power exist in thermally sterilized famotidine. Slow spin-lattice relaxation processes, strong dipolar interactions characterize thermally sterilized famotidine. Microwave saturation indicates that EPR lines of famotidine are homogeneously broadened. The usefulness of EPR spectroscopy to examine of the sterilized drugs was evaluated.
    Źródło:
    Nukleonika; 2013, 58, 3; 413-418
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Attaching a spin to a protein - site-directed spin labeling in structural biology
    Autorzy:
    Czogalla, Aleksander
    Pieciul, Aldona
    Jezierski, Adam
    Sikorski, Aleksander
    Powiązania:
    https://bibliotekanauki.pl/articles/1041067.pdf
    Data publikacji:
    2007
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    protein structure
    site-directed spin labeling
    electron paramagnetic resonance (EPR) spectroscopy
    Opis:
    Site-directed spin labeling and electron paramagnetic resonance spectroscopy have recently experienced an outburst of multiple applications in protein science. Numerous interesting strategies have been introduced for determining the structure of proteins and its conformational changes at the level of the backbone fold. Moreover, considerable technical development in the field makes the technique an attractive approach for the study of structure and dynamics of membrane proteins and large biological complexes at physiological conditions. This review focuses on a brief description of site-directed spin labeling-derived techniques in the context of their recent applications.
    Źródło:
    Acta Biochimica Polonica; 2007, 54, 2; 235-244
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Interaction of diatomic molecules with nickel ions inside the channels of high silica zeolites : an EPR and DFT study
    Autorzy:
    Mazur, T.
    Podolska, K.
    Pietrzyk, P.
    Sojka, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/147105.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electron paramagnetic resonance (EPR) spectroscopy
    g-tensor
    nickel
    zeolite
    small molecule activation
    Opis:
    Interaction of CO, NO, and O2 diatomics with NiII and NiI ions dispersed in ZSM-5 zeolite was investigated by electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) modelling. The resulting adducts NiI-CO, NiII-NO, and NiI-O2 were identified based on g-tensor parameters, obtained by computer fitting of the powder EPR spectra, and next ascertained by parallel relativistic DFT calculations of the corresponding g-tensor values. The structures of the NiI-CO, NiII-NO, and NiI-O2 complexes were obtained by geometry optimization with the Kohn- -Sham method. Binding of the diatomics was discussed in terms of the spin-pairing and electron density transfer events. Interaction of CO with NiI cations led to the pronounced change in the coordination and electronic structure of the NiI center, however, no redox processes were observed in agreement with the “innocent” nature of CO as a ligand. On the contrary, strong electron and spin density redistribution was observed upon NO and O2 interaction (“non-innocent ligands”) leading to the formation of the bound nitrosonium NOδ+ and superoxo O2 – species, respectively.
    Źródło:
    Nukleonika; 2013, 58, 3; 351-357
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR studies of Cladosporium cladosporioides complexes with amphotericin B
    Autorzy:
    Zdybel, M.
    Pilawa, B.
    Buszman, E.
    Witoszyńska, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/147790.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    amphotericin B
    Cladosporium cladosporioides
    electron paramagnetic resonance (EPR) spectroscopy
    free radicals
    melanin
    Opis:
    Free radicals in Cladosporium cladosporioides cultured with amphotericin B were spectroscopically studied. The effect of drug concentrations on free radicals in the fungal melanin biopolymer was examined. It was pointed out that the concentrations of free radicals in the complexes of Cladosporium cladosporioides mycelium with amphotericin B depend on the drug concentrations. Eumelanin dominates in the fungal studied samples. The slow spin-lattice relaxation processes exist in the tested samples. Free radicals take a part in the formation of Cladosporium cladosporioides mycelium complexes with amphotericin B.
    Źródło:
    Nukleonika; 2013, 58, 3; 401-405
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR spectroscopy of Cu2+ and Mn2+ in borate glasses
    Autorzy:
    Drzewiecki, A.
    Padlyak, B.
    Adamiv, V.
    Burak, Y.
    Teslyuk, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/147654.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    borate glasses
    Cu2+ paramagnetic centre
    electron paramagnetic resonance (EPR) spectroscopy
    hyperfine structure
    Mn2+ paramagnetic centre
    Opis:
    Electron paramagnetic resonance (EPR) spectra of the CaB4O7 and LiCaBO3 glasses containing 0.5 and 1.0 mol.% CuO and MnO2 impurity compounds were investigated at room temperature. The glasses with CaB4O7:Cu, LiCaBO3:Cu, CaB4O7:Mn and LiCaBO3:Mn compositions were produced from the corresponding polycrystalline compounds using standard glass synthesis and technological conditions developed by the authors. The EPR spectral parameters of the Cu2+ and Mn2+ centres in both glasses containing 0.5 and 1.0 mol.% CuO and MnO2 doping oxides were determined. Analysis of EPR spectral parameters shows that Cu impurity is incorporated into the CaB4O7 and LiCaBO3 glass network as isolated Cu2+ (3d9, 2D5/2) paramagnetic ions. The Cu2+ ions occupy Ca(Li) sites of the borate glass network coordinated by six O2− anions with geometry of elongated octahedron (D4h symmetry) due to the Jahn- -Teller effect. The EPR spectra of the Mn-doped CaB4O7 and LiCaBO3 glasses are virtually identical and typical of all oxide glasses activated with Mn2+ (3d5, 6S5/2) ions. Observed EPR spectra in the Mn-doped glasses were attributed to isolated Mn2+ (1) centres (geff ≅ 4.3) in octahedral Ca(Li) sites with a strong (fully) rhombic distortion, isolated Mn2+ (2) centres (geff ≅ 2.0) in octahedral Ca(Li) sites with nearly cubic local symmetry as well as pairs and small clusters of the Mn2+ ions, coupled by magnetic dipolar and exchange interactions. On the basis of the obtained results and analysis of referenced data, the local structure of the Cu2+ and Mn2+ centres in the borate glasses have been proposed.
    Źródło:
    Nukleonika; 2013, 58, 3; 379-385
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spectroscopic study of a bis(imidazole) (octaethylporphyrinato)iron(III) complex
    Autorzy:
    Rutkowska, I.
    Dziliński, K.
    Kaczmarzyk, T.
    Stanek, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/146898.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electron paramagnetic resonance (EPR) spectroscopy
    Mössbauer spectroscopy
    low-spin iron porphyrin
    imidazole axial ligands
    Opis:
    Low-spin ferric octaethylporphyrinatoiron complex with two imidazole axial ligands [Fe(III)(OEP)(Im)2]+ has been investigated by electron paramagnetic resonance (EPR) and Mössbauer spectroscopies. It was found that the ground spin state corresponds to the electron configuration (dxy)2 (dxz, dyz)3 and planes of the imidazole axial ligands have a parallel mutual orientation. Ethyl groups bonded to pyrrole rings, as peripheral substituents, effect on the ground electron spin state of the complex studied and the relative orientation of the the imidazole axial ligands in a similar way like the phenyl substituents bonded to meso-carbon atoms of the porphyrin macrocycle. The temperature dependence of the Mössbauer spectra is discussed in terms of magnetic relaxation processes.
    Źródło:
    Nukleonika; 2013, 58, 3; 419-423
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electron paramagnetic resonance (EPR) study of the short - living radicals generated thermally in phosphorylated maize starch with different amounts of amylose
    Autorzy:
    Bidzińska, E.
    Dyrek, K.
    Kruczała, K.
    Szczygieł, J.
    Wenda, E.
    Błaszczak, W.
    Fornal, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/147482.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    carbon centred radicals
    electron paramagnetic resonance (EPR) spectroscopy
    PBN spin trap
    starch phosphates
    thermal treatment
    Opis:
    Quantitative electron paramagnetic resonance (EPR) spectroscopy was used for the determination of a number and properties of short-living radicals generated thermally in maize starch with various amounts of amylose. The EPR spectra of radical adducts with N-tert-butyl-α-phenylnitrone (PBN) spin trap reveal the presence of three types of radicals of mobility related with their localization in the zones of various degree of crystallinity. Hylon VII, which represents a matrix with a high content of amylose, offers better conditions for free rotation of radical species, whereas waxy maize, containing almost exclusively amylopectin, exhibits more restricted dynamics.
    Źródło:
    Nukleonika; 2013, 58, 3; 429-433
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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