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1

Radicals initiated by gamma rays in selected amino acids and collagen

Przybytniak Grażyna., Sadło Jarosław, Dąbrowska Małgorzata, Zimek Zbigniew

Nukleonika

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2019

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Vol. 64, No. 1

11--17

EN

Calf skin collagen and three amino acids essential for its structure, namely glycine, L-proline and 4-hydroxyl-L-proline, were irradiated with gamma rays up to a dose of 10 kGy. Conversion of radicals over time or after thermal annealing to selected temperatures was monitored by X-band electron paramagnetic resonance (EPR) spectroscopy. Some experimental spectra were compared with signals simulated based on literature data from the electron nuclear double resonance (ENDOR) studies. The following phenomena were confi rmed in the tested amino acids: abstraction of hydrogen atom (glycine, proline, hydroxyproline, collagen), deamination (glycine, hydroxyproline), decarboxylation (hydroxyproline). Chain scission at glycine residues, radiation-induced decomposition of side groups and oxidative degradation were observed in irradiated collagen. The decay of radicals in collagen saturated with water occurred at lower temperatures than in macromolecules having only structural water. The paramagnetic centres were the most stable in an oxygen-free atmosphere (vacuum). Radical processes deteriorated the structure of collagen; hence, radiation sterilization of skin grafts requires careful pros and cons analysis.

2

Annealing and Ni content effects on EPR and structural properties of Zn1–xNixO aerogel nanoparticles

Sayari A., El Mir L.

Materials Science Poland

|

2017

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Vol. 35, No. 3

454--462

EN

Zn1–xNixO aerogel nanopowders with nickel concentration in the range of 0.05 ≤ x ≤ 0.25, were synthesized by the sol-gel processing technique and post-annealed in air at 500 ˚C. Structural, vibrational, thermal and magnetic properties of the as-prepared and annealed Zn1–xNixO powdered samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman scattering, thermal gravimetric analysis (TGA) and electron paramagnetic resonance (EPR) spectroscopy. In addition to the ZnNiO phase, XRD analysis revealed the formation of a secondary NiO phase when the Ni content was greater than or equal to 10 %. The TEM images confirm that the particle size is in the range of 20 nm to 40 nm, in accordance with XRD results, and the particles are well dispersed. Raman scattering measurements confirm the wurtzite structure of the synthesized Zn1–xNixO nanopowders and show that intrinsic host-lattice defects are activated when Ni2+ ions are substituted to the Zn sites. Room temperature ferromagnetic order was observed in all of the samples and was strongly dependent on the Ni content and thermal annealing. These results indicate that the observed room temperature ferromagnetism in ZnNiO may be attributed to the substitutional incorporation of Ni at Zn sites.

3

Review. High pressure techniques used in the paramagnetic resonances

Krupska A., Krupski M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2016

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Vol. 64, nr 1

135--141

EN

The aim of this review-paper is to overview high pressure techniques used in the magnetic resonances in laboratories. In this review, we would like to show the techniques that lead yielding high pressure applicable in the paramagnetic resonances. We would like to draw your attention to the separation of the effects resulting from the pressure and effects from the temperature, thereby separate the volume phonon contribution. Our main intention is to show the impact of high pressure on the structure of matter, in particular on its fundamental level.

4

Oxidative stability of the lipid fraction in cookies : the EPR study

Zawada K., Kozłowska M., Żbikowska A.

Nukleonika

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2015

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Vol. 60, No. 3, part 1

469--473

EN

Cookies are a group of convenient food products that are popular among consumers. They may contain high amounts of fats, which can be prone to oxidation. To retard the oxidative deterioration, synthetic and natural antioxidants may be added. Herb and spice extracts can be sources of natural biologically active substances with antioxidant activity. In this work, electron paramagnetic resonance spectroscopy was used to monitor the lipid oxidation in cookies with rosemary and thyme extracts subjected to the storage in elevated temperature. It was shown that thyme extract can be used as a natural antioxidant source for the preparation of bakery products, while the rosemary extract should be used with care in fat-rich products exposed to high temperatures.

5

Multifrequency EPR study on radiation induced centers in calcium carbonates labeled with 13C

Sadło J., Bugaj A., Strzelczak G., Sterniczuk M., Jaegermann Z.

Nukleonika

|

2015

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Vol. 60, No. 3, part 1

429--434

EN

In calcite and aragonite, γ-irradiated at 77 K, several paramagnetic centers were generated and detected by EPR spectroscopy; in calcite, CO3 – (orthorhombic symmetry, bulk and bonded to surface), CO3 3–, NO3 2–, O3 –, and in aragonite CO2 – (isotropic and orthorhombic symmetry) depending on the type of calcium carbonate used. For calcium carbonates enriched with 13C more detailed information about the formed radicals was possible to be obtained. In both natural (white coral) and synthetic aragonite the same radicals were identifi ed with main differences in the properties of CO2 – radicals. An application of Q-band EPR allowed to avoid the signals overlap giving the characteristics of radical anisotropy.

6

EPR examination of free radicals thermally formed in vaselinum flavum

Ramos P., Pilawa B.

Nukleonika

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2015

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Vol. 60, No. 3, part 1

443--447

EN

The popular pharmaceutical base used in pharmacy – vaselinum flavum – was studied by an X-band (9.3 GHz) EPR spectrometer in the range of microwave power of 2.2–70 mW. The samples were sterilized in hot air oven at temperatures: 160°C (120 min), 170°C (60 min), and 180°C (30 min). The aim of this work was to determine properties and free radical concentrations in vaselinum flavum thermally sterilized at different conditions. The changes in free radical system in vaselinum flavum during storage were analyzed. Free radicals were found in all the heated samples. The lowest free radical concentration was obtained for vaselinum flavum heated at 180°C for 30 min; so these parameters are proposed for the thermal sterilization of this pharmaceutical base. Interactions with oxygen decreased free radical concentration in vaselinum flavum during storage. Strong quenching of free radicals in vaselinum flavum was observed after 2 days for the samples sterilized at temperatures 160 and 180°C. Such an effect for vaselinum flavum heated at temperature 170°C was observed later, 13 days after sterilization. Fast spin-lattice relaxation processes exist in thermally sterilized vaselinum flavum. The EPR lines of heated vaselinum flavum were homogeneously broadened. EPR spectroscopy and its use for examining the thermal sterilization process in pharmacy was confirmed.

7

Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer from Sepia offi cinalis : EPR examination

Zdybel M., Pilawa B.

Nukleonika

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2015

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Vol. 60, No. 3, part 1

483--488

EN

Free radicals in synthetic melanin and melanin from Sepia officinalis were studied by electron paramagnetic resonance (EPR) spectroscopy. The effect of time of ultraviolet (UV) irradiation on free radicals in these melanins was tested. The samples were exposed to UV during 15, 30, and 60 minutes. EPR spectra were measured with microwaves from an X-band (9.3 GHz) in the range of microwave power of 2.2–70 mW. The performed EPR examinations indicate that high concentrations (~1021–1022 spin/g) of o-semiquinone free radicals with g factors of 2.0039–2.0045 exist in all the tested samples. For nonirradiated samples, free radical concentration was higher in natural melanin than in synthetic melanin. UV irradiation caused the increase of free radical concentrations in synthetic melanin samples and this effect depends on the time of irradiation. The largest free radical formation in the both melanins was obtained for 60 min of UV irradiation. Free radical concentrations after the UV irradiation of melanins during 30 min were lower than during irradiation by 15 min, and probably this effect was the result of recombination of the radiatively formed free radicals. EPR lines of the tested samples broadened with increasing microwave power, so these lines were homogeneously broadened. The two types of melanins differed in the time of spin-lattice relaxation processes. Slower spin-lattice relaxation processes exist in melanin from Sepia officinalis than in synthetic melanin. UV irradiation did not change the time of spin-lattice relaxation processes in the tested melanins. The performed studies confirmed the usefulness of EPR spectroscopy in cosmetology and medicine.

8

EPR study of γ-irradiated feather keratin and human fingernails concerning retrospective dose assessment

Strzelczak G., Sterniczuk M., Sadło J., Kowalska M., Michalik J.

Nukleonika

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2013

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Vol. 58, No. 4

505--509

EN

In this paper we report the results of comparative EPR studies on free radicals generated in γ-irradiated powder samples of feather keratin powder and human fingernails. In degassed samples of both materials irradiated at 77 K the major component of EPR spectrum represents sulphur-centred radicals in cysteine residues. It quickly decays after air admission at room temperature while a singlet assigned to semiquinone melanin radicals remains the only one seen. The singlet recorded with fingernails decays slowly at room temperature and might be potentially useful for dose assessment by EPR. The advantages and limitations of fingernails EPR dosimetry are discussed.

9

Separation of groups of free radicals from noised EPR spectrum using genetic algorithm and gradient method

Bernas M., Ramos P.

Journal of Medical Informatics & Technologies

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2013

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Vol. 22

117--123

EN

Different groups of free radicals exist in biological material like animal tissues or plants parts. The processes like heating or cooling creates additional types of free radicals groups in this organic matter, due to changes in chemical bonds. The paper proposes a method to determine types and concentrations of different groups of free radicals in the matter processed in various temperatures. The method extracts the spectrum of free radicals using electron paramagnetic resonance with the microwave power of 2.2 mW. Then an automatic method to find a best possible fit using limited number of theoretical mathematical functions is proposed. The match is found using spectrum filtration, and a genetic algorithm implementation supported by a Gradient Method. The obtained results were compared against the samples prepared by an expert. Finally, some remarks were given and new possibilities for future research were proposed.

10

Action of Some Organomercury Compounds on Photosynthesis in Spinach Chloroplasts

Šeršeň F., Kráľová K.

Ecological Chemistry and Engineering. S

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2013

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Vol. 20, nr 3

489--498

EN

The effects of five organomercury compounds (methylmercuric chloride, phenylmercuric acetate, phenylmercuric borate, phenylmercuric citrate and diphenylmercury) on photosynthetic electron transport (PET) in spinach chloroplasts were investigated. The IC50 values of organomercury compounds related to PET inhibition in spinach chloroplasts varied in the range from 468 mmol dm-3 to 942 mmol dm-3 and were approximately by one order higher than the corresponding value determined for HgCl2 applied also in DMSO solution (IC50 = 58 mmol dm-3). Due to extremely low aqueous solubility of diphenylmercury, the corresponding IC50 value could not be determined. Using EPR spectroscopy as probable sites of action of organomercury compounds in photosynthetic apparatus ferredoxin on the acceptor side of PS 1 and the quinone electron acceptors QA or QB on the reducing side of PS 2 were suggested.

PL

Zbadano wpływ pięciu związków rtęcioorganicznych (chlorku metylortęci, octanu fenylortęci, boranu fenylortęci, cytrynianu fenylortęci i difenylortęci) na fotosyntetyczny transport elektronów (PET) w chloroplastach szpinaku. Wartości IC50 dla związków rtęcioorganicznych związanych z inhibicją PET w chloroplastach szpinaku zmieniała się w zakresie od 468 do 942 μmol dm-3 i była w przybliżeniu o rząd większa od odpowiedniej wartości określonej dla HgCl2, stosowanego również w roztworze DMSO (IC50 = 58 μmol dm-3). Ze względu na bardzo małą rozpuszczalność difenylortęci w wodzie odpowiednia wartość IC50 nie może być określona. Wyniki badań za pomocą spektroskopii EPR pozwoliły na zaproponowanie prawdopodobnych miejsc działania związków rtęci w procesie fotosyntezy ferredoksyny po stronie akceptora PS 1 i chinonowego akceptora elektronów QA lub QB po stronie redukującej PS 2.

11

A helical-coil resonator magnetically coupled with microstrip transmission line for EPR spectroscopy

Mossakowski M., Koprowski J.

Materiały Elektroniczne

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2009

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T. 37, nr 4

3-8

EN

This simple resonator consists of silver wire formed as coil of two turns. Compared to cavity resonators working in the same frequency band, our resonator is substantially smaller - 0.8 mm inner diameter and 0.2 mm wire diameter (AWG of 32). The coil is suspended over the microstrip supply line which is connected to EPR spectrometer. The whole apparatus is an X band EPR probe for biological tissue research. The main advantage of our project in this simple construction of the probe is the convenient resonator's coupling and supplying RF power by a microstrip line. Simulations and real measurements of electromagnetic field distribution revealed impressive symmetry and an enormous magnetic field concentration along resonator's main axis where tissue samples are placed. The A factor for this resonator is over 20Gs/√W. Analysis of resonance circuit shows a very wide resonance band (small quality factor - about 300). This is the desired feature in pulse EPR spectroscopy.

PL

Opisany rezonator zbudowany został ze srebrnego drutu o średnicy 0.2 mm uformowanego w dwuzwojową cewkę o wewnętrznej średnicy 0.8 mm. W porównaniu do rezonatorów wnękowych pracujących w tym samym zakresie częstotliwości, przedstawiony rezonator helikalny stanowi niewielki ich ułamek objętości. Cewka jest zawieszona nad linią mikropaskową podłączoną do mostka mikrofalowego spektrometru EPR. Rezonator zbudowany został z przeznaczeniem do badań uwodnionych próbek biologicznych w paśmie X. Głównym zamierzeniem autorów było udoskonalenie sprzężenia rezonatora z mikropaskową linią zasilającą. Przeprowadzone symulacje i rzeczywiste pomiary rozkładu pola elektromagnetycznego ujawniły dużą symetrię i olbrzymią koncentrację pola magnetycznego wzdłuż głównej osi rezonatora, w miejscu gdzie znajduje się badana próbka. Współczynnik A dla opisanego rezonatora przewyższa wartość 20 GS/√W, natomiast pasmo rezonansowe jest bardzo szerokie - mała dobroć układu - 300. Powyższe cechy rezonatora są pożądane w impulsowej spektroskopii EPR.

12

Wpływ ogrzewania w temperaturze 180°C na paramagnetyczne właściwości diklofenaku - badania EPR

Ramos P., Pilawa B., Wilczyński S., Czyż K., Adamczyk J.

Engineering of Biomaterials

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2009

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Vol. 12, no. 87

7-12

PL

Przeprowadzono badania wolnych rodników powstających w diklofenaku podczas ogrzewania w temperaturze 180°C. Jako technikę badawczą zastosowano spektroskopię elektronowego rezonansu paramagnetycznego (EPR). Dla wyjściowej próbki diklofenaku nie poddanego obróbce termicznej nie obserwowano widm EPR. Asymetryczne linie EPR rejestrowano natomiast w przypadku ogrzewanego diklofenaku. Zbadano wpływ czasu przechowywania na właściwości i koncentrację wolnych rodników w ogrzewanym diklofenaku. Stwierdzono, że w diklofenaku poddanym obróbce termicznej występuje duża ilość wolnych rodników (∼10(19) spin/g). Koncentracja wolnych rodników w ogrzewanym diklofenaku rośnie podczas przechowywania próbki. Oddziaływania wolne rodniki - tkanki mogą być odpowiedzialne za efekty toksyczne w organizmie oraz zmiany struktury biomateriałów. Obróbkę termiczną w przypadku diklofenaku należy więc odrzucić jako metodę sterylizacji leku. W pracy opisano wpływ mocy mikrofalowej na kształt, amplitudę i szerokość linii EPR dikofenaku. Metodą ciągłego nasycenia mikrofalowego linii EPR wykazano, że w diklofenaku zachodzą wolne procesy relaksacji spin-sieć.

EN

Electron paramagnetic resonance (EPR) examinations of free radicals formed in diclofenac heated at 180°C were performed. EPR spectrum for the non-heated sample was not obtained. Asymmetrical EPR lines were measured for the studied heated drug. Properties and free radicals concentration in heated diclofenac during storage of the sample were studied. High amount of free radicals (∼10(19) spin/g) characterizes diclofenac after heating of the sample. Free radicals concentration in heated diclofenac increases with increasing storage time of the sample. Free radicals - tissues interactions may be accompanied by toxic effects in organisms and changes of biomaterial's structure, so thermal sterilization is rather rejected as sterlization process for diclofenac. Influence of microwave power on lineshape, amplitudes and linewidth of EPR spectra was described. Continuous microwave saturation of EPR lines points out that slow spin-lattice relaxation processes exist in the heated diclofenac.

13

Wolne rodniki w sterylizowanym termicznie verapamilu

Ramos P., Pepliński P., Pilawa B.

Engineering of Biomaterials

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2009

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Vol. 12, no. 89-91

162--164

PL

Zbadano generowanie wolnych rodników w werapamilu podczas sterylizacji termiczne w temperaturze 180 stopni C. Koncentrację i właściwości wolnych rodników analizowano z zastosowaniem spektroskopii elektronowego rezonansu paramagnetycznego (EPR) na pasmo X (9.3 GHz). Wykazano, że w procesie sterylizacji termicznej powstają w werapamilu stabilne wolne rodniki. Wolne procesy relaksacji spin-sieć oraz silne oddziaływania dipolowe występują w werapamilu. Badania metodą EPR wykazały, że sterylizacja wysokotemperaturowa nie jest zalecana dla werapamilu.

EN

Free radical formation in verapamil during thermal sterilization at temperature 180 degrees of C was studied. Concentration and properties of free radicals were examined by the use of electron paramagnetic resonance (EPR) spectroscopy at X-band (9.3GHz). It was stated that stable free radicals are formed during thermal sterilization of verapamil. Slow spin-lattice relaxation processes and strong dipolar interactions exist in verapamil.EPR studies showed that sterilization at high temperature is not recommended for verapamil.

14

Powstawanie wolnych rodników podczas rozkładu termicznego monoazotanu izosorbitolu

Ramos P., Pilawa B., Kawka M.

Engineering of Biomaterials

|

2009

|

Vol. 12, no. 89-91

156--159

PL

Wykonano badania wolnych rodników generowanych w monazotanie izosorbitolu pod wpływem wysokiej temperatury. Wyznaczono metodą elektronowego rezonansu paramagnetycznego (EPR) koncentrację wolnych rodników w próbce. Zbadano wpływ mocy mikrofalowej na kształt widm EPR monoazotanu izosorbitolu. Analizowano procesy relaksacji spin-spin i spin-sieć. Określono wpływ czasu przechowywania próbki po rozkładzie termicznym na wolne rodniki w leku.

EN

Studies of free radicals formed in isosorbide mononitrate upon high temperature were performed.. Free radical concentration in the sample was determined by electron paramagnetic resonance (EPR) method. Influence of microwave power on lineshape of EPR spectra of isisorbide mononitrate was examined. Spin-spin and spin-lattice relaxation proccesses were analysed. The effect of storage time of the sample on free radicals in the drug was determined.

15

Badania Rhizoma calami metodą EPR

Pawłowska-Góral K., Kurzeja E., Pilawa B., Ramos P.

Engineering of Biomaterials

|

2009

|

Vol. 12, no. 89-91

159--161

PL

Przeprowadzono badania Rhizoma calami z zastosowaniem spektroskopii elektronowego rezonansu paramagnetycznego (EPR) na pasmo X (9.3 GHz). Porównano koncentrację i właściwości centrów paramagnetycznych w próbkach wyjściowych oraz sterylizowanych parą wodną. Wykazano, że wolne rodniki występują w obydwu badanych próbkach roślinnych. Ciągłe nasycenie mikrofalowe linii EPR wykazało jednorodne rozmieszczenie wolnych rodników oraz wolne procesy relaksacji spin-sieć w Rhizoma calami.

EN

Rhizoma calami was examined by electron paramagnetic resonance (EPR) spectroscopy at X-band (9.3 GHz). Concentration and properties of paramagnetic centers in the original sample and sample sterilized by water vapour were compared. It was stated that free radicals exist in both the studied plant samples. Continuous microwave saturation of EPR lines proved homogeneous distribution of free radicals and slow spin-lattice relaxation processes in Rhizoma calami.

16

Zastosowanie spektroskopii EPR do badania deksametazonu sterylizowanego termicznie

Kościelniak M., Pilawa B., Wilczyński S.

Engineering of Biomaterials

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2008

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Vol. 11, no. 81-84

55--56

PL

Spektroskopię elektronowego rezonansu paramagnetycznego (EPR) zastosowano do oceny optymalnych warunków sterylizacji deksametazonu. Sterylizację sproszkowanego leku wykonano w suchym powietrzu w temperaturze 180°C w czasie wynoszącym 30 minut. Celem pracy jest określenie właściwości wolnorodnikowych sterylizowanego deksametazonu. Optymalnym warunkom sterylizacji powinno towarzyszyć powstawanie niewielkiej ilości wolnych rodników w substancji leczniczej, które mogą powodować szereg efektów ubocznych podczas farmakoterapii. Deksametazon jest syntetycznym glikokortykosteroidem z grupy hormonów steroidowych. Wykazuje silne działanie przeciwzapalne i immunosresyjne. Jest silniejszy ok. 20-30 -krotnie przewyższając hydrokortyzon i 4-5 krotnie niż prednizolon. Deksametazon hamuje zapalenie i obrzęk tkanki, dlatego jest używany do leczenia zapaleń o szerokim zakresie chorób auto-immunologicznych takich zapalenie stawów itp. Jest również aplikowany małych ilościach przed lub po zabiegach dentystycznych. W onkologii deksametazon jest podawany w trakcie chemioterapii [1,2]. Strukturę chemiczną deksametazonu przedstawiono na RYSUNKU 1. Pomiary widm wykonano za pomocą spektrometru EPR Firmy RADIOPAN (Poznań) przy modulacji pola magnetycznego wynoszącej 100kHz. Częstotliwość promieniowania mikrofalowego wynosiła 9.3GHz. Widma EPR w postaci pierwszej pochodnej rejestrowano w szerokim zakresie mocy mikrofalowej 0.7- 70mW. Analizowano parametry widm EPR oraz koncentrację wolnych rodników w sterylizowanym leku. Zbadano zmiany koncentracji i parametrów widm EPR wraz ze wzrostem czasu przechowywania leku sterylizowanego w 180°C przez 30 minut. Wyznaczono zależność amplitudy i szerokości linii EPR od mocy mikrofalowej. Analizowano wpływ mocy mikrofalowej na kształt i asymetrię widm EPR. Próbki deksametazonu nie poddane działaniu wysokiej temperatury nie dawały sygnału EPR. Widma EPR deksametazonu sterylizowanego w 180°C przez 30 minut wykazywały złożony charakter (RYS.2). Wskazuje to, że w sterylizowanym deksametazonie występuje kilka rodzajów wolnych rodników. Rejestrowane widma EPR stanowią superpozycję linii składowych pochodzących od poszczególnych typów wolnych rodników. Zbadano wpływ mocy mikrofalowej na amplitudę i szerokość linii EPR termicznie sterylizowanego deksametazonu. Zaobserwowano zmianę kształtu widm EPR wraz z mocą mikrofalową. Wraz ze wzrostem mocy mikrofalowej rośnie amplituda linii EPR deksametazonu. Podobną zależność zarejestrowano dla szerokości linii EPR. Taki charakter zamian wskazuje na jednorodne rozmieszczenie centrów paramagnetycznych w termicznie sterylizowanym deksametazonie (RYS. 3 i 4). Linie EPR różnych grup wolnych rodników nasycają się przy innej mocy mikrofalowej. Wolne rodniki w sterylizowanym deksametazonie są stabilne. Nie obserwowano szybkiego zaniku wolnych rodników z czasem przechowywania próbki. Badania EPR wskazują na niewielką zależność asymetrii linii EPR od mocy mikrofalowej. Moc mikrofalowa nieznacznie wpływa na wszystkie analizowane parametry IA1-A2I, IA1/A2I, IB1-B2I, IB1/B2I wyznaczone w pracy w celu oceny asymetrii linii EPR.

EN

Electron paramagnetic resonance (EPR) spectroscopy was applied to examine optimal sterilization conditions of dexamethasone. Sterilization of powdered dexamethasone was done in dry air at temperature 180°C during the time of 30 minutes. The aim of this work was to determine free radical properties of sterilized dexamethasone. It is expected that optima conditions of sterilization is accompanied by formation of low amount of free radicals in drug which can cause many side effects during pharmacotherapy. Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid hormones. It acts as an anti-inflammatory and immunosuppressant. Its potency is about 20-30 times that of hydrocortisone and 4-5 times of prednisone. Dexamethasone inhibit the inflammatory and the edema of the tissue, so its making useful for the treatment of a wide range of inflammatory and auto-immune conditions such as rheumatoid arthritis ect. It is also given in small amounts before and/or after some forms of dental surgery. In oncology dexamethasone, it is given to cancer patients undergoing chemotherapy [1,2]. Chemical structure of dexamethasone is presented in FIGURE 1. Measurements of spectra were done by the use of EPR spectrometer produced by RADIOPAN Firm (Poznań) with modulation of magnetic field of 100 kHz. Microwave frequency of 9.3GHz was applied. The first-derivative EPR spectra were recorded with microwave power of the wide range of 0.7-70mW. Parameters of EPR spectra and free radical concentration in the sterilized drug were analyzed. Changes of free radical concentration and EPR parameters with increasing of storage time after heating of the drug at 180°C were evaluated. Changes of amplitud es and linewidths of EPR spectra with microwave power were determined. The influence of microwave power on lineshape of EPR spectra and line asymmetry was analyzed. Samples of dexamethasone not heated with high temperature gave no EPR signals. EPR spectra of dexamethasone sterilized in 180°C during 30 minutes reveal complex structure (FIG. 2). It was stated that several types of free radicals exist in the sterilized drug. Its EPR spectra reveal multi-component structure. The recorded EPR spectra are superposition of component lines of the individual types of free radicals. Influence of microwave power on amplitude and linewidths thermally sterilized dexamethasone was tested. Changes of EPR lineshapes with microwave power were observed. Amplitude of EPR line increase with microwave power increasing. Similar relationship for linewidths of EPR lines was recorded. This kind of relationship evidence on homogenous location of paramagnetic centers in thermally sterilized dexam-ethasone (FIG. 3 and 4). EPR lines of the individual groups of free radicals saturate at different microwave powers. Free radicals in sterilized dexamethasone are stabile. EPR studies indicate on small influence of microwave power on line asymmetry. Microwave power only slightly affects on all analyzed parameters IA1-A2I, IA1/A2I, IB1-B2I, IB1/B2I determined to evaluate line asymmetry.

17

Structural and Spectroscopic Characterization of Mixed Ligand Complex: Bis(quinoline-2-carboxylato)bis(imidazole)manganese(II)

Dobrzyńska D., Jerzykiewicz L., Jezierska J., Słoniec E.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 11

1789-1797

EN

A new complex, [Mn(quin-2-c)2(Him)2] (quin-2-c = quinoline-2-carboxylate ion, Him = imidazole), was synthesized by self assembly and its structure was determined by X-ray analysis. The compound crystallizes in the centrosymmetric space group C2/c with the Mn atom on a twofold axis, a = 18.091(6) Alfa; b = 10.125(4) Alfa; c = 13.708(5) Alfa; Beta= 111.73(3)graduate; V = 2332.5(15) Alfa3 and Z = 4 (T = 100 K). Strong hydrogen bonds between imidazole moieties and carboxylate groups connect themolecules of the complex into the 1D chains extending parallel to the c axis. The interchain contacts of the C-HźźźO, C-HźźźN,piźźźpi and C-Hźźźpi type influence the architecture of the crystal. The complex was characterized by thermal analysis, and by EPR and IR spectroscopy.

18

Electron paramagnetic resonance studies on silver atoms and clusters in regularly interstratified clay minerals

Yamada H., Sadlo J., Tamura K., Shimomura S., Turek J., Michalik J.

Nukleonika

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2004

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Vol. 49, nr 4

131-136

EN

The formation and stabilization of reduced silver species in the regularly interstratified clay minerals, trioctahedral smectite/chlorite (tri-Sm/Ch) and dioctahedral smectite/mica (di-Sm/M), have been studied by electron paramagnetic resonance (EPR) spectroscopy. Both minerals loaded with Ag+ cations after degassing and dehydration were g-irradiated at 77 K and monitored by EPR as the temperature increased. Some samples were exposed to water or methanol vapor after dehydration. In both hydrated and dehydrated samples only the doublets assigned to Ag0 atoms were observed with no evidence of the formation of Ag clusters. However, the EPR parameters of silver atoms in both matrices are different. In tri-Sm/Ch the narrow anisotropic EPR lines overlap with the broader isotropic lines, whereas in di-Sm/M only broad lines are recorded. The hyperfine splitting - Aiso(Ag0) is larger in tri-Sm/Ch than in di-Sm/M. Also the stability of Ag0 in both clay minerals is distinctly different. Ag0 doublet in di-Sm/M disappears completely above 230 K, whereas in tri-Sm/Ch it is still recorded at 310 K. It is proposed, basing on the EPR results that Ag0 atoms appear at different sites in both matrices: - in tri-Sm/Ch in the middle of smectite interlayer and in hexagonal cavities in the silicate sheets of tetrahedron layer and in di-Sm/M in hexagonal cavities only. When samples had been exposed to methanol before irradiation, the silver clusters become stabilized in the interlayer sites. In tri- Sm/Ch matrix the silver dimer Ag2+ formed by g-irradiation at 77 K is transformed to tetrameric cluster, Ag43+ at 150 K. In di-Sm/M the radiation-induced silver agglomeration proceeds in a similar way, but with a slower rate and Ag tetramer is formed only above 190 K. In both clay minerals, Ag43+ clusters decay above 250 K.

19

Struktura fizyczna węgli kamiennych w świetle badań spektroskopii EPR, ultradźwiękowej i optycznej

Krzesińska M., Pilawa B., Pusz S.

Karbo

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2004

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Nr 2

64-67

PL

Celem przeprowadzonych badań było uzyskanie informacji dotyczących struktury węgli kamiennych o szerokim stopniu uwęglenia, przy zastosowaniu następujących fizycznych metod doświadczalnych: akustyka molekularna, mikroskopia optyczna i spektroskopia elektronowego rezonansu paramagnetycznego. Wyznaczono wiele parametrów fizycznych: gęstość rzeczywistą, porowatość, prędkość ultradźwięków, dynamiczny moduł sprężystości, refleksyjność, parametry EPR. Zaobserwowano wyraźną zależność badanych parametrów struktury fizycznej węgli (kształt widm EPR, koncentracja centrów paramagnetycznych, prędkość ultradźwięków, zdolność odbicia światła, gęstość rzeczywista, porowatość) od stopnia metamorfizmu badanych węgli. Uzyskane rezultaty odniesiono do fizycznych modeli struktury węgla kamiennego.

EN

The aim of this study was to get information about coal structure within the wide rank using for the same samples the following physical methods: molecular acoustic, optical microscopy and electron paramagnetic resonance spectroscopy. Various physical parameters: true density, porosity, ultrasonic velocity, dynamic elastic modulus, reflectance and total concentration of paramagnetic centers were determined for coals of wide rank. Ultrasonic velocities measurements were performed using an ultrasonic tester CT1 (Unipan-Ultrasonic) based on the transmission method. The heads of 100 kHz were used. Microscopic studies were made using reflected light microscope Axioskop (Opton-Zeiss, Germany) with polarized light Lambda =546 nm, in immersion oil. The EPR spectra of the evacuated coal samples (104 Torr) were measured using an X-band (9,3 GHz) electron paramagnetic resonance spectrometer with magnetic modulation frequency of 100 kHz. True density was determined using a helium pycnometer type 1305 MicromeriticsŽ (USA). A clear dependences of coal structure parameters (shape of EPR spectra, concentration of paramagnetic centers, ultrasonic velocity, reflectance, true density, porosity) on carbon content of coals were observed. Obtained results were related to physical models of coal structure.

20

Typy centrów paramagnetycznych a właściwości sprężyste i optyczne węgli kamiennych

Pilawa B., Pusz S., Krzesińska M., Kwiecińska B.

Karbo

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2003

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Nr 4

224-227

PL

Wyznaczono dynamiczny moduł sprężystości, zdolność odbicia światła oraz parametry widm elektronowego rezonansu paramagnetycznego (EPR) dla szerokiego zakresu węgli kamiennych (83,5-94,9 % mas. C). Celem pracy było znalezienie różnych grup centrów paramagnetycznych w badanych węglach kamiennych oraz porównanie właściwości centrów paramagnetycznych z właściwościami elastycznymi i optycznymi próbek. W badanych węglach kamiennych znaleziono trzy różne grupy centrów paramagnetycznych, odpowiedzialne za szerokie linie Gaussa ( AB : 0,87-0,98 mT, g: 2,0031 -2,0037), szerokie linie Lorentza l (AB : 0,43-0,54 mT, g: 2,0030-2,0035) oraz wąskie linie Lorentza 2 (DeltaBpp: 0,08-0,14 mT, g: 2,0029-2,0030). Koncentracje centrów paramagnetycznych odpowiedzialnych za szerokie linie EPR malej ą wraz ze wzrostem anizotropii sprężystej węgla kamiennego. Szerokości linii wszystkich rodzajów centrów paramagnetycznych maleją ze wzrostem gęstości rzeczywistej węgla kamiennego. Zaobserwowano spadek wartości współczynnika g szerokiej linii Gaussa i szerokiej linii Lorentza l wraz ze wzrostem zawartości pierwiastka C w węglu oraz wraz ze wzrostem średniej zdolności odbicia światła węgla.

EN

Dynamic elastic moduli, optical reflectance and electron paramagnetic resonance (EPR) spectra parameters were determined for a wide rank coals (83,5-94,9 wt % C). The aim of this work was to find different groups of paramagnetic centers in the studied coals and to compare the feature of the paramagnetic centers with elastic and optical properties of coal. Three different groups of paramagnetic centers with broad Gauss (Delta Bpp 0,87-0,98 mT, g: 2,0031 -2,0037), broad Lorentz 1 (DeltaB: 0,43-0,54 mT, g: 2,0030-2,0035), and narrow Lorentzian 2 (AB : 0,08-0,14 mT, g: 2,0029-2,0030) lines were found in the studied coals. Concentrations of paramagnetic centers responsible for broad EPR lines decrease with increasing elastic anisotropy of coal. Linewidths of all types of paramagnetic centers decrease with increase of coal density. Decrease of g factor of broad Gauss and broad Lorentz 1 lines with increasing both a carbon content and mean reflectance was observed. KURZEJA L., MUSZYŃSKI J., DUBER S., SZELUGA U.: New carbon nanotubes/polymer composites and their properties.