The nitridation of ZnO nanowires

ZnO nanowires (NWs) with diameters of 50 to 250 nm and lengths of several micrometres have been grown by reactive vapour transport via the reaction of Zn with oxygen on 1 nm Au/Si(001) at 550°C under an inert flow of Ar. These exhibited clear peaks in the X-ray diffraction corresponding to the hexagonal wurtzite crystal structure of ZnO and a photoluminescence spectrum with a peak at 3.3 eV corresponding to band edge emission close to 3.2 eV determined from the abrupt onset in the absorption-transmission through ZnO NWs grown on 0.5 nm Au/quartz. We find that the post growth nitridation of ZnO NWs under a steady flow of NH3 at temperatures ≤600°C promotes the formation of a ZnO/Zn3N2 core-shell structure as suggested by the suppression of the peaks related to ZnO and the emergence of new ones corresponding to the cubic crystal structure of Zn3N2 while maintaining their integrity. Higher temperatures lead to the complete elimination of the ZnO NWs. We discuss the effect of nitridation time, flow of NH3, ramp rate and hydrogen on the conversion and propose a mechanism for the nitridation

Composition and enantiomeric analysis of the essential oil of the fruits and the leaves of Pistacia vera from Greece

The essential oils of the fruits and the leaves of pistachio (Pistacia vera L.) were analyzed by GC and GC/MS. Fresh unripe pistachio fruits were richer in essential oil (0.5 %, w/w) than the leaves (0.1 %, w/w). Twenty one compounds were identified in the essential oil of the fruits and the major components were (+)-α-pinene (54.6 %) and terpinolene (31.2 %). The enantiomeric ratio of the major constituents of the essential oil of the fruits was determined using chiral GC/MS and it was found that the (+)/(-)-α-pinene ratio was 99.5:0.5, (+)/(-)-limonene 80:20, (+)/(-)-β-pinene 96:4, and (+)/(-)-α-terpineol 0:100. Thirty three compounds were identified in the essential oil of the leaves and the major components were found to be α-pinene (30.0 %), terpinolene (17.6 %) and bornyl acetate (11.3 %). © 2007 by MDPI

Antioxidative, antiradical, and antimicrobial activities of extracts from Antep Pistachio hulls

Pistacia vera L. is the only genus of more than ten in Pistacia species consumed as a nut and has commercial value. Turkey is one of the homelands of the pistachio species, and they are named Antep pistachio. When Antep pistachios are processed into nuts, their reddish purple hulls are removed as a waste after the processing. In this research, Antep pistachio hull samples extracted by methanol, ethanol and water were tested for antioxidant and antiradical (IC(50) value) potentials, and antimicrobial activities as well. The values of total phenolic content of methanol extracts of Antep pistachio hull was 167.49 +/- A 0.48 mg gallic acid equivalent (GAE)/g dry extract. The ethanol and aqueous extract of the pistachio hulls were determined as 89.87 +/- A 0.44 and 31.73 +/- A 0.21 mg GAE/g dry extract, respectively. The antioxidant activities of extracts were evaluated by the phosphomolybdenum method. The highest antioxidant activity of the hull extracts was determined in the methanol extracted samples (152.10 +/- A 0.19 mg ascorbic acid equivalent (AAE)/g dry extract), while the lowest value was in the ethanol extracts (15.19 +/- A 0.00 mg AAE/g dry extract). The values of IC(50) in methanol, ethanol and aqueous extracts of the pistachio hulls were 16.01, 21.62 and 24.45 mu g/ml, respectively. The highest antiradical activity was in the methanol extract of Antep pistachio hulls. In this research, the pistachio hull extracts were tested for antimicrobial activities against total 15 microorganisms, 13 bacteria and 2 yeasts. The aqueous extract of the hull was the most ineffective extract against the microorganisms tested. The methanol and ethanol extracts of the pistachio hulls, which had limited antimicrobial effect against the bacteria, Mycobacterium smegmatis, Salmonella typhimurium, Proteus mirabilis and Yersinia enterocolitica, and the yeasts, Saccharomyces cerevisiae and Candida albicans, and were effective on the other microorganisms constituted inhibition zones diameter as between 10 and 39 mm. All extracts of the pistachio hulls exhibited antimicrobial activity against Listeria monocytogenes (6-38 mm) and Escherichia coli O157: H7 (8-28 mm). In conclusion, the hulls of Antep pistachio can be evaluated as a potential antimicrobial and antioxidant resource in the food systems