Search Results
160 Szöcs, F. (2002): Walnut free radicals studied by ESR. J. Fd Sci. , 67 , 953–955. Szöcs F
Loschen , G. ( 1985 ): Oxygen-centered free radicals as mediators of inflammation . In: Sies , H. (ed.) Oxidative Stress . Academic Press , New York , pp. 405 – 437 . Freeman
Nagy, I. Z.: Semiconduction of proteins as an attribute of the living state: the ideas of Albert Szent-Györgyi revisited in light of the recent knowledge regarding oxygen free radicals. Exp
276 Sanchez-Moreno, C., Larrauri, J. A. & Saura-Calixto, A. (1999): Free radical scavenging capacity and inhibition of lipid oxidation of wines, grapes juices and related phenolic
168 Késmárky G., Tóth K., Vajda G. és mtsai: Hemorheological and oxygen free radical associated alterations during and after percutaneous transluminal coronary angioplasty
Abdel Rahman, M., Blázovics A., Ágoston M. és mtsai: A chemiluminescent study for detection of free radicals in gallbladder bile in gallstone diseases. Ces. a Slov Gastroent., 1995, 49 , 7–13. Ágoston M
Abstract
Thermal analysis (TA) is useful for studying the reaction and thermal properties of free radical cured photopolymers. Starting with reactive liquid monomers, the photocuring reactions are initiated by the interaction of UV radiation with an added photoinitiator to form free radicals. The monomers generally are acrylates or methacrylates. Some of the important characteristics of these systems that can be illustrated by TA methods are: 1) the polymers are heterogeneous with more than one phase present even when only one monomer is involved; 2) because of this heterogeneity they have unusually broad glass transitions; 3) the degree of conversion achieved in many UV cured systems is in the 60–80% range, so that considerable residual monomer is often present; 4) partially cured, vitrified samples contain trapped free radicals that will continue to react slowly; 5) when a partially cured photopolymer is heated above its current T g a reaction exotherm is evident. Some other aspects of photocuring are not easily disclosed by thermal analysis. Studying fast photoreactions by DSC may not give valid kinetic data because the reaction occurs faster than the DSC instrument time constant. Optical methods (IR, Raman) can be used to advantage in such cases. While photocuring resins are usually exposed to light at ambient temperatures, the local temperature in the resin will be quite elevated, resulting in T g values that are much higher than ambient. This has been demonstrated by thermal modeling of the reaction and verified by infrared thermography.
Abstract
The effect of gamma-irradiation on some new hydrazones of terpenoids using electron spin resonance (ESR) is reported. Gamma-irradiation of three derivates of hydrazone and of compounds resulting from the condensation of these derivates with terpenoids produces stable free radicals at room temperature. The analysis of the ESR parameters (g-factors and hyperfine coupling) and the simulation performed lead us to conclude that free radicals are of form R–N–NH2 (arising from hydrazine derivates) and R–N–N=R
(arising from condensation compounds). The thermal stability of formed radicals is discussed and the activation energy involved in the process of recombination of free radicals is calculated.
Abstract
The free radical polymerizations of higher n-alkyl methacrylates were not investigated in detail until now. In this work, the courses of the isothermal free radical bulk polymerization of dodecyl, quatrodecyl and hexadecyl methacrylates were investigated by differential scanning calorimetry. The effects of the polymerization temperature and the alkyl group length in the esters on the monomer conversions during polymerization were studied. It was found that the polymerization rate vs. time curves have two maxima. The free radical polymerizations of above-mentioned monomers proceed with slightly expressed gel effect at the temperatures below 90°C, at initiator concentration 1 mass% in monomer.
Abstract
The effect of free radicals obtained in hydroxyl and cerium(IV)-nitrilotriacetic acid free radical generating systems on contractile proteins (actin, myosin and their complexes in glycerinated muscle fibres) was studied using differential scanning calorimetry and spin trapping electron paramagnetic resonance technique. The analysis of spectra showed that selective attack of thiol groups – Cys-257 and Cys-374 residues of actin, and among others Cys-707 residue of myosin – and random attack of sidechains of the main proteins of muscle tissue produced structural and functional changes, which affected the ATP hydrolysis cycle and very likely the dynamics of actin. The melting curves obtained on protein systems support the view that global conformational changes accompany the local damage of free radicals.
