GAS-CHROMATOGRAPHIC IDENTIFICATION OF PHENYLALKANES AND BICYCLIC HYDROCARBONS.
Abstract Retention indices and their temperature coefficients have been measured with Silicone Oil DC 710 and Emulphor O as liquid phases. Some experimental rules are put forward.
Strahlungschemie der Kohlenwasserstoffe. 12. Mitteilung. Benzol-Toluol und deuterierte Verbindungen†
Further information on the radiation chemistry of aromatic liquids was obtained by a detailed analysis applied mainly to the dimeric products formed by the gamma irradiation of mixtures of benzene and toluene and their deutero- compounds (benzene-d/sub 6/-toluene-d/sub 0/ and benzene-d/sub 0/toluene- alpha - d/sub 3/). Diphenylmethane types of molecules were not formed by a reaction of dehydroaromatic species (benzene). The different products were generally produced according to the expected mixture law when corrections are allowed for the competing chemical reactions. In the perdeuterobenzene-toluene system, however, an energy transfer from benzene-d/sub 6/ to toluene is postulated to explain the yields obtained, The isomer distribution of the three phenyltoluenes can be compared with the statistical values. (auth)
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.