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Biphasic CuO-NiO solids were synthesised using mechanical activation and thermal treatment of a mixture of nickel oxalate and copper oxalate at different temperatures (400, 500, 600 and 700°C). XRD analysis identified two crystalline phases in the samples with the structures of CuO Tenorite and NiO Bunsenite, accordingly. A change in the catalytic activity with respect to CO oxidation of biphasic CuO-NiO solids obtained at different temperatures was found. The change is due to the different specific surface area of the samples on the one hand and to the possible formation of solid solutions (respectively Ni(1-x)Cux O with a cubic symmetry and Cu(1-y) Niy O with a monoclinic symmetry). The formation of these solids with a variable composition corresponds to the data of the variation in the unit cell parameters of both phases, depending on the synthesis temperature and to the EPR spectra of the samples. [ABSTRACT FROM AUTHOR]

The aim of the present study is to prove radiation processing in air dehydrated dates, prunes and figs, as well as to recommend which part of the fruit to sample. The detection method is Electron Paramagnetic Resonance (EPR) spectroscopy. Before irradiation in date stone, prune stone and flesh, and fig seeds EPR spectroscopy was detected a weak singlet line, whereas date flesh and fig flesh are EPR silent. After gamma-irradiation in date stone and flesh, and fig flesh a "sugar-like' EPR spectrum is recorded. In prune stone a typical "cellulose-like" spectrum is detected, whereas in prune flesh and fig stone only singlet line is recorded as before radiation treatment. Of research done it can be seen that the irradiation is proved in a different part of the fruit. European Protocol EN 13708 is applicable to irradiated dried dates and figs, whereas Protocol EN 1787 for dried prunes. [ABSTRACT FROM AUTHOR]

The results of electron paramagnetic resonance (EPR) study on commercially available juices from various fruits and different fruit contents: 25%, 40%, 50%, and 100%, homemade juices, nectars and concentrated fruit syrups, before and after gamma-irradiation are reported. In order to remove water from non- and irradiated samples all juices and nectars were filtered; the solid residue was washed with alcohol and dried at room temperature. Only concentrated fruit syrups were dried for 60 min at 40°C in a standard laboratory oven. All samples under study show a singlet EPR line with g=2.0025 before irradiation with exception of concentrated fruit syrups, which are EPR silent. Irradiation of juice samples gives rise to complex EPR spectra which gradually transferred to "cellulose-like" EPR spectrum from 25% to 100% fruit content. Concentrated fruit syrups show typical "sugar-like" spectra due to added saccharides. All EPR spectra are characteristic and can prove radiation treatment. The fading kinetics of radiation-induced EPR signals were studied for a period of 60 days after irradiation. [ABSTRACT FROM AUTHOR]

Gamma irradiation has been applied as an efficient and inexpensive method for the sterilization of nuts for years. However, along with the benefits of such treatment, negative effects are possible because of the formation of reactive oxygen species with a toxic effect on important biologically active substances. Because of the scarce and contradictory information in the literature about gamma-irradiated almonds, the aim of our work was the examination of the lipid changes, antioxidant activity, and oxidative stability of almonds treated by 10 and 25 kGy gamma rays, as well as changes in intensity of the EPR spectra as an indicator for the stability of radiation-induced free radicals. The results revealed no significant differences in the EPR spectra of almonds treated at 10 and 25 kGy doses, neither in their intensity nor in kinetic behaviour. The EPR signals decayed exponentially over 250 days, with a decreasing of central line by 90%, with satellite lines by about 73%. No significant changes in the fat content, fatty acids composition, and acid value of irradiated almonds were observed. However, the amount of (alpha)tocopherols decreased from 292 to 175 mg/kg, whereas the conjugated dienes and trienes increased, K 232 from 1.3 to 3 and K 268 from 0.04 to 0.15, respectively, with the increasing of irradiation dose. The same was observed for total polyphenols in defatted almonds (1374 to 1520 mg/100 g), where in vitro antioxidant activity determined by ORAC and HORAC methods increased from 100 to 156 µmol TE/g and from 61 to 86 µmol GAE/g, respectively. The oxidative stability of oil decreased from 6 to 4 h at 120 °C and from 24.6 to 18.6 h at 100 °C (measured by Rancimat equipment). The kinetic parameters characterizing the oxidative stability of oil from 10 kGy irradiated almonds were studied before and after addition of different concentrations of ascorbyl palmitate as a synergist of tocopherols. Its effectiveness was concentration-dependent, and 0.75 mM ensured the same induction period as that of non-irradiated nut oil. Further enrichment with alpha-tocopherol in equimolar ratio with palmitate did not improve the oil stability. In conclusion, gamma irradiation is an appropriate method for the treatment of almonds without significant changes in fat content and fatty acids composition. The decreasing of oxidative stability after higher irradiation could be prevented by the addition of ascorbyl palmitate.

A new natural diketopiperazine (1) was obtained from the culture broth of Microbispora aerata strain imbas-11A, isolated from penguin excrements collected on the Antarctic Livingston Island. Compound 1 was purified consecutively by solvent extraction, silica gel column chromatography and preparative HPLC. The structure of the compound was elucidated by 1D and 2D NMR experiments and mass spectrometric investigations. The absolute configuration of compound 1 was determined by amino acid analysis and NOESY correlations. A low antiproliferative and cytotoxic effect of trans-cyclo-(D-tryptophanyl-L-tyrosyl) (1) was determined with L-929 mouse fibroblast cells, K-562 human leukemia cells and HeLa human cervix carcinoma. Trans-cyclo-(D-tryptophanyl-L-tyrosyl) (1) did not show antimicrobial activity at a concentration of 50 µg per disc against Bacillus subtilis, Staphylococcus aureus, Streptomyces viridochromogenes, Escherichia coli, Candida albicans and Mucor miehei.

Streptomyces sp. strain SB9 was isolated from perm frost soil samples in Spitsbergen, Arctic Ocean; it grows in a temperature range between 4 degrees C and 28 degrees C. During the survey of biologically active metabolites biosynthesized by this strain, significant amounts of alpha,alpha-trehalose (1) and glycerol (2) were detected. The compounds were isolated from the mycelium, were chromatographically separated, and the structures were elucidated on the basis of MS and NMR measurements. A possible role of trehalose in cold adaptation of the strain was examined. It was determined that the mycelium of the strain cultivated at 4 degrees C accumulated 5-fold higher amounts of trehalose in comparison with the cells cultivated at 28 degrees C. The mesofilic reference strains, Streptomyces spectabilis NRRL 2494 and Streptomyces lividans TK64, accumulated 100-fold less trahalose than the psychrotolerant Streptomyces sp. SB9. High amounts of trehalose in the cells could be a reason for adaptation of the strain to life at Arctic conditions.

The fungus, Tritirachium sp. HKI 0317, was isolated from the Antarctic lichen Neuropogon sp. Fermentation of this strain, extraction of the culture broth, and preparative separation of produced compounds furnished 4-carboxy-5,5'-dihydroxy-3,3'-dimethyldiphenylether (1), macrosphelide A (2), and macrosphelide J (3). The structures were elucidated on the basis of MS and NMR measurements, and the previously published data for this compounds.

A new sulphur-containing natural alkaloid named microbiaeratin (1a) was isolated, together with the known microbiaeratinin (2, bacillamide) from the culture filtrate of Microbispora aerata strain IMBAS-11A. The organism was isolated from penguin excrements collected on the Antarctic Livingston Island. The structure was elucidated by one- and two-dimensional NMR experiments and mass spectrometric investigations.

Sanionins A (1) and B (2) were isolated from the moss Sanionia georgico-uncinata, collected on the Antarctic Livingston Island. The compounds 1 and 2 were purified by solvent extraction, silica gel column chromatography, and preparative HPLC, consecutively. The structures of the both compounds were elucidated by 1D and 2D NMR experiments and mass spectrometric investigations. These compounds showed activity against important Gram-positive pathogens, such as mycobacteria, multiresistant staphylococci, and vancomycin resistant enterococci. This activity is combined with antiinflammatoric activity and low cytotoxicity.

The dynamics of citric acid biosynthesis and some morphological changes of Asp. niger IM-13 in culture media containing starch hydrolysate and 3% methanol were traced. The culture developed in filamentous form and little fine pellets. Deformed hyphae with characteristic extensions were observed. The changes in Asp. niger IM-13 metabolism were studied by comparing the biomass accumulation, the utilization of reducing substances, the citric acid biosynthesis, pH and the protein content of the control and the experimental variants. A suppression of growth in the period from the 48th hour of cultivation up to the end of the process, suppression of protein synthesis in the micelium and increased synthesis of citric acid were established.