Slabo izražene pojave u epr spektru paramagnetičnog centra sličnog šupljini u citozin hidrokloridu

The fine phenomena in the EPR spectra of the hole-like paramagnetic centre formed in cytosine(thiocytosine)-HCl crystals upon irradiation are studied with EPR spectroscopy. The spin Hamiltonian including the electronic Zeeman term, hyperfine coupling, quadrupole coupling and the nuclear Zeeman term has been used in the second-order perturbation treatment for the interpretation of the experimental observations. It is shown that the quadrupolar term causes a detectable shift of the EPR lines and also induces the "forbidden\u27\u27 transitions. From the shift of the "allowed\u27\u27 transitions and the positions of the ``forbidden\u27\u27 transitions, the chlorine quadrupolar coupling tensor [P], has been determined.Proučavane su slabo izražene, neredovite pojave u EPR spektrima paramagnetičnog centra sličnog šupljini u ozračenim kristalima citozin hidroklorida s primjesama tiocitozina. Za objašnjenje ponašanja upotrijebljen je spinski Hamiltonijan koji se sastoji od elektronskog Zeemanovog člana, nuklearnog Zeemanovog člana, člana hiperfine i člana kvadrupolne sprege jezgre s elektronom. Pokazano je da kvadrupolni član koji potječe od klora ne samo unosi pomak EPR spektralnih linija, nego uzrokuje i pojavu dodatnih, “zabranjenih” prijelaza. Iz mjerenja slabo izraženih pomaka linija i položaja “zabranjenih” linija izračunat je kvadrupolni tenzor

The influence of the type of polymerization upon the discoloration of composites

Na stabilnost kompozita utječe sastav materijala, način polimerizacije, obrada površine, poroznost, izloženost sunčevom svjetlu, prehrana i higi­jena. Jednokomponentni materijal Heliosit i dvokomponentni Isopast pod­vrgnuti su ubrzanom starenju, da bi se metodom spektrofotometrijske refleksije utvrdila sklonost promjeni boje in vitro. Dvokomponentni ma­terijal je potamnio, što je u skladu s kliničkim iskustvom, uz izraženu poroznost. Jednokomponentni materijal je pokazao bolju stabilnost boje, a neki uzorci izbijeljenja zbog nepotpune polimerizacije. Grubo obrađeni uzorci se doimlju svjetlijima, a razlika u promjeni boje između uzorka poliranih na dva različita načina nije opažena.Color stability of composite resin materials is influenced by composition of the material, type of curing, porosity, sunlight exposure, diet, and the oral hygiene. Light cured composite material Heliosit and chemically cured isosit were analysed under conditions of accelerated aging. Differences in color change were established between these two ma­terials using the method of spectrophotometric reflection. Isopast beca­me signifficantly darker and more porous, what is in agreement with clinical experience. Heliosit has shown better color stability, and some samples blanching because of the incomplete polymerisation. The sam­ples with rough surfaces appeared linghter, and the manner of polishing have not caused differencies in color change between analysed samples

Effect of L-Carnitine Supplementation on Some Biochemical Parameters in Blood Serum of Sedentary Population

Because of its role in the transport of fatty acids from cytosol into mitochondrion, the consumption of L-carnitine became popular among athletes, and/or as a mass loss supplement. In an attempt to obtain more data on the effect of L-carnitine supplementation on some biochemical parameters in blood serum, a double-blind, placebo-controlled study was carried. Healthy volunteers with declared sedentary activities received 2 g/day of either L-carnitine or placebo for 2 weeks. L-carnitine administration did not induce statistically significant changes in blood serum concentrations of glucose, triacylglycerols, total cholesterol, HDL cholesterol and creatinine, nor affected the activity of analysed enzymes (AST, ALT, LDH, and CK). The only observed effect was a decrease in the concentration of free fatty acids in the serum from 0.439 mmol dm–3 at the beginning to 0.279 mmol dm–3 at the end of the experiment. Body mass reduction was not achieved. We conclude that L-carnitine supplementation cannot be used for body mass reduction per se, but might be involved in energy utilisation