Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 9

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Publication available in full text mode
Content available

EPR Studies of Carbonized Cellulose - Oxygen Interactions

100%
Pilawa B., Pietrzak R., Wachowska H., Babeł K.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 1
151-154
EN
EPR examination of cellulose carbonized at 400ºC and 600ºC has been performed. The aim of this work was to search a sample useful as the oximetric probe in biology and medicine. The higher paramagnetic centers concentration characterizes cellulose carbonized at 600ºC, which was found as the sensitive oximetric probe. Quasi-chemical bonds between cellulose molecules and paramagnetic O_2 molecules decrease paramagnetic centers concentration. A linear increase in paramagnetic centers concentration and a linear decrease in EPR linewidth with increasing time of sample evacuation were observed for cellulose carbonized at 600ºC. Oxygen affects spin-lattice interactions in carbonized cellulose.
2
Publication available in full text mode
Content available

Multi-Component EPR Spectra of Coals with Different Carbon Content

100%
Pilawa B., Więckowski A., Pietrzak R., Wachowska H.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 2
403-407
EN
EPR spectra of lignite"Mequinenza" (Spain) (62.3 wt% C) and Polish orthocoking coal (87.8 wt% C) were compared. The spectra were superpositions of broad Gaussian, broad Lorentzian 1, and narrow Lorentzian 3 lines. Concentration of paramagnetic centers - mainly delocalizedπ electrons - responsible for narrow Lorentzian 3 lines increases with increase in carbon content in coal. Coal units with slow and fast spin-lattice relaxation processes exist in the two studied samples. Slow spin-lattice interactions occur in simple aromatic coal units with broad Gaussian and Lorentzian 1 lines. Fast spin-lattice relaxation processes are characteristic of large aromatic units with narrow Lorentzian 3 lines.
3
Publication available in full text mode
Content available

Effect of Laser Radiation on Free Radicals in Human Cancer G361 Cells

100%
Latocha M., Pilawa B., Zdybel M., Wilczok T.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 2
409-412
EN
EPR spectroscopy was used to the examination of free radicals evolution in cancer G361 cells during photodynamic therapy. The cancer cells were cultured with photosensitizer ALA and irradiated with 635 nm light by laser. The number of cells was determined microscopically. The decrease in the cell number and the increase in free radicals, obtained for G361 cells cultured with ALA and irradiated with laser, were stronger than relevant changes for the cells which were only irradiated with laser. The studied melanotic cells susceptible for photodynamic therapy differ from the other melanotic SK human cancer cells by fast spin-lattice relaxation processes. Slow spin-lattice relaxation processes exist in the studied earlier non susceptible for photodynamic therapy SK cells.
4
Content available remote

ESR Studies of Paramagnetic Centers in Pharmaceutical Materials - Cefaclor and Clarithromycin as an Example

88%
Skowronska A., Wojciechowski M., Ramos P., Pilawa B., Kruk D.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 2
514-517
EN
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.
5
Content available remote

Groups of Paramagnetic Centres in Reduced and Methylated Low Rank Coal

88%
Pilawa B., Wachowska H., Kozłowski M., Więckowski A., Najder-Kozdrowska L.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 3
264-267
EN
Low rank Illinois No. 6 coal was studied by electron paramagnetic resonance EPR spectroscopy. The parameters of EPR spectra (spectroscopic splitting factors g, linewidths ΔB_{pp}, concentrations of paramagnetic centres N) were measured for row and chemically treated coal (demineralized, reduced and methylated samples). The multi-component structure of experimental spectra of this coal was proved. Two groups of paramagnetic centres responsible for broad Lorentzian 1 and narrow Lorentzian 2 lines exist in studied samples. Paramagnetic centres connected with component lines revealed different behaviour during chemical treatments.
6
Content available remote

Influence of Microwave Power on EPR Signal of Melanin Radical and Copper(II) Ions in DOPA-Melanin Complexes

88%
Najder-Kozdrowska L., Pilawa B., Więckowski A., Buszman E., Wrześniok D.
|
EN
Electron paramagnetic resonance spectroscopy EPR was used for examination of microwave saturation in DOPA-melanin complexes with kanamycin and Cu(II) ions. The fast spin-lattice relaxation processes take place in system of paramagnetic metal ions. EPR signal of melanin radical saturated with growing of microwave power used during measurements. After adding Cu(II) ions a shortening of relaxation time is observed for EPR signal of melanin radical.
7
Publication available in full text mode
Content available

Effect of pH on Paramagnetic Centers in Cladosporium cladosporioides Melanin

76%
Pilawa B., Buszman E., Gondzik A., Wilczyński S., Zdybel M., Witoszyńska T., Wilczok T.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 1
147-150
EN
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.
8
Content available remote

Triplet States in DOPA-Melanin and in Its Complexes with Kanamycin and Copper Cu(II) Ions

76%
Najder-Kozdrowska L., Pilawa B., Buszman E., Więckowski A., Świątkowska L., Wrześniok D., Wojtowicz W.
|
|
issue 4
613-618
EN
The mono- and biradical forms of DOPA-melanin (DOPA-eumelanin) were studied by EPR spectroscopy in 100-300 K temperature range. The existence of triplet states in DOPA-melanin was proved. The analysis of EPR spectra has shown that in DOPA-melanin and its complexes with kanamycin and Cu^{2+} ions, two kinds of paramagnetic centres exist. The first of them are in doublet ground state with spin S = 1/2 and they obey the Curie law. The paramagnetic centres of the second group are in thermally excited triplet state with spin S = 1 and in this case the Curie law is not fulfilled.
9
Publication available in full text mode
Content available

Paramagnetic Centers in DOPA-Melanin-Dihydrostreptomycin Complexes

76%
Buszman E., Pilawa B., Zdybel M., Wrześniok D., Grzegorczyk A., Wilczok T.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 2
353-356
EN
DOPA-melanin-dihydrostreptomycin complexes with drug concentrations 1×10^{-4}-1×10^{-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.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.