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1

An Esr Study of Free Radicals Scavenging by Red Tea

Wosiński S., Jurga J., Kruczyński Z., Górski R., Sobieralski K., Siwulski M.

Ecological Chemistry and Engineering. S

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2012

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Vol. 19, nr 1

47-54

EN

Herbal tea is known to exhibit the scavenging of free radicals responsible for cellular damage. We studied the effect of water treated with reverse osmotic filter equipped with a special dielectric ceramic composite on the antioxidant activity of red tea. Methanol solution of DPPH was added to the tea extract and the RT decay of DPPH free radicals was studied by ESR spectroscopy. Red tea brewed from tap water treated with the composite filter was found to exhibit higher radical scavenging efficiency in comparison with that of the tea brewed from tap water, mineral water and reverse osmosis water.

PL

Herbata ziołowa jest znana z własności wymiatania rodników odpowiedzialnych za uszkodzenia komórkowe. Zbadano wpływ wody poddanej filtracji metodą odwróconej osmozy z zastosowaniem dielektrycznego kompozytu ceramicznego na aktywność antyoksydacyjną czerwonej herbaty. Do ekstraktu herbaty dodawano metanolowego roztworu DPPH i badano metodą EPR zanik czasowy wolnych rodników DPPH. Czerwona herbata zaparzana na wodzie wodociągowej traktowanej filtrem kompozytowym wykazywała większą zdolność wymiatania rodników w porównaniu z herbatą zaparzaną na wodzie wodociągowej, wodzie mineralnej i wodzie z odwróconej osmozy.

2

Reactivity of cis-Diaminedichloroplatinum(II) (cis-Platin) Toward Chromium(IV)

Stawińska J., Staszak Z., Jezierska J., Cieślak-Golonka M., Daszkiewicz M.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 3

291-301

EN

The interaction of Cr(VI) compounds: K2Cr2O7 with cis-diaminedichlorplatinum(II) (cis-Platin) has been studied spectroscopically (UV-VIS, IR, FIR, ESR). It was found that the redox processes took place with the precipiation of brown Pt(IV)-Cr(III) heteropolynuclear products. The deconvolution of the electronic spectra allowed the analysis in convention of independent Pt(IV) and Cr(III) crystal fields.

3

4-Azomalononitrile Antipyrine Complexes of Some First Row Transition Metals

El-Saied F., Ayad M., Issa R., Aly S.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 7

919-926

EN

Fe(III), Co(II), Ni(II) and Cu(II) complexes of 4-azomalononitrile antipyrine have been prepared in ethanol solution and characterized by IR, electronic, and ESR spectra as well as magnetic susceptibilities and molar conductivities. The ligand behaves as a neutral bidentate one and the coordination takes place via the azomethine nitrogen and the carbonyl oxygen atom. Ligand field parameters have been calculated and structures are proposed.

4

Morphology of sulfonated polyimide ionomers from ESR spectra of paramagnetic transition metal cations and nitroxide spin probes

Motyakin M. V., Cornet N., Gebel G., Schlick S.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 4

273-292

EN

We present a study of sulfonated polyimide block ionomer membranes (SPIs) in the dry state, and swollen by water, methanol, ethanol, and dioxane. The ionomers are based on a naphthalenic dianhydride and differ in the ionic exchange capacity and the type of diamine in the hydrophobic block. The ionomers were studied by electron spin resonance (ESR) spectroscopy of the paramagnetic transition metal cations Cu "*" and VO "*", and of two nitroxide spin probes. The results indicated the existence of separate hydrophobic and hydrophilic domains in the dry and in the swollen membranes. Water clusters with a diameter < 40 A were detected in the water-swollen membranes, but the water has glassy properties and a much lower enthalpy of fusion compared to bulk water. No evidence for the presence of solvent clusters was obtained for the membranes swollen by methanol and ethanol. An ESR signal was observed in all neat SPI ionomers, and its intensity and line shape varied with ionomer structure and preparation method. The ESR intensity of this signal is higher in the membranes in acid form compared to membranes fully,.neutralized by Li* or K*. The irreversible increase of the signal intensity upon heating of the dry membranes above 360 K suggests the formation of reactive intermediates that may be involved in ionomer degradation processes.

5

Hydration and order in different aggregates of a poly(ethylene oxide) alkyl ether in aqueous solution. An ESR spin probe study

Caldararu H., Caragheorgheopol A., Schlick S.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 4

367-383

EN

The local parameters (hydration, order, viscosity) in different aggregates (mi-celle, hexagonal and lamellar liquid crystals) in the phase diagram of poly(oxyethylene) [5]-dodecylether (C12E5) in water have been measured by EPR with two series of spin probes: x-DSA, (x == 5, 7, 10, 12 and 16) and CAT n (11. == 4, 8, 11 and 16). A rather complete map of hydration ([H20]/[Ea]) along the PEa chains has been determined. It shows that the hydration of the PEa regions is very low near the PEO/hydrocarbon interface in all phases a.nd increases towards the outer region of the PEO shell with a gradient which becomes steeper in micellar phase in comparison with the lamellar phase. Temperature increase reduces the hydration levels at all measured sites. The order of the chains decreases by dilution from the lamellar to the micellar phase, but it is preserved within the frame of the la,mellar pha.se a.t two different concentrations. The ol'der degree, 5, d.ecreases in the series .5- > 7- > 10- > 12- > 16-doxyl, irrespective of tern perature, in all t)'"pes of aggrega.tes. This trend, together with decreasing hydration values, points to the insertion of the stearic acid chain in the aggregates along the normal to the interface. In samples quenched in liquid nitrogen, however, bending of the stearic acid chain was observed in a number of cases.

6

ESR study of monolayer vanadium oxide catalysts supported of different supports in relation to catalytic oxidation of methanol

Haber J., Nowak P., Serwicka E. M., Wachs I. E.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 4

337-346

EN

Vanadia monolayers deposited on various oxide supports (Zr02, Nb(2)O(5), TiO2, Al(2)O(3) and Si0(2) have been investigated with the aid of electron spin resonance. The results show that the electronic structure of reduced vanadyl species generated during methanol chemisorption depends on the nature of the supporting matrix. This is shown by changes of theBeta(2) bonding coefficient calculated from the experimentally determined ESR parameters. I t is demonstrated that the catalytic activity in methanol oxidation, ex-pressed in terms of turnover frequency (TOF), can be correlated with the latter parameter and increases with the ionicity of the vanadyl in-plane Pi-bonding system.

7

Radiation proceses in poly(ethylene terephthalate) composite materials

Sadło J., Bojarski J., Strzelczak G., Michalik J.

Nukleonika

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1999

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Vol. 44, nr 1

59-69

EN

The radiation - induced radicals in poly(ethylene terephthalate) - PET composite with polypropylene - PP and polyetherester KPEE have been studied by ESR spectroscopy. In pure PET matrix radicals are not stabilized at room temperature but in PET/PP composite (10-20% of PP) similary to pure PP matrix peroxy radicals are recorded at room temperature with the concentrations indicating that radicals formed originally in PET units are stabilized during migration along polymer chain by PP units enabling the formation of peroxy radicals. In contrast, in PET/KPEE composite materials the radical processes are the same as in PET homopolymers. The changes of polymer viscosity in melting state prove that polymer degradation is major radiation effect in the majority of composite materials.

PL

Przy użyciu spektroskopii Elektronowego Rezonansu Paramagnetycznego (EPR) badano inicjowane radiacyjnie rodniki w kompozytach polimerowych na bazie politereftalanu etylenu (PET) z domieszką polipropylenu (PP) lub kopolieteroestru (KPEE). W czystym PET wolne rodniki w temperaturze pokojowej nie stabilizują się, natomiast w kompozytach PET/PP zawierających 10 i 20% PP rejestruje się, podobnie jak w czystym PP, rodniki nadtlenkowe. Stężenie rodników w tych kompozytach jest większe niż procentowy udział polipropylenu w matrycy polimerowej. Wskazuje to, że rodniki powstające początkowo we fragmentach politereftalanowych migrują wzdłuż łańcuchów ulegając stabilizacji we fragmentach polipropylenowych w wyniku powstawania rodników nadtlenkowych. Efektu tego nie obserwuje się w kompozytach PET/KPEE, w których procesy rodnikowe przebiegają w ten sam sposób jak w homopolimerze PET. Na podstawie zmian lepkości polimerów w stanie stopionym stwierdzono, że w badanych polimerach głównym efektem radiacyjnym jest degradacja.