Detection of antibacterial activity of essential oil components by TLC-bioautography using luminescent bacteria

The aim of the present study was the chemical characterization of some medically relevant essential oils (tea tree, clove, cinnamon bark, thyme and eucalyptus) and the investigation of antibacterial effect of the components of these oils by use of a direct bioautographic method. Thin layer chromatography (TLC) was combined with biological detection in this process. The chemical composition of the oils was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Eucalyptol (84.2%) was the main component of the essential oil of eucalyptus, eugenol (83.7%) of clove oil, and trans-cinnamic aldehyde (73.2%), thymol (49.9%) and terpinen-4-ol (45.8%) of cinnamon bark, thyme and tea tree oils, respectively. Antibacterial activity of the separated components of these oils, as well as their pure main components (eucalyptol, eugenol, trans-cinnamic aldehyde and thymol) was observed against the Gram-negative luminescence tagged plant pathogenic bacterium Pseudomonas syringae pv. maculicola (Psmlux) and the Gram-negative, naturally luminescent marine bacterium Vibrio fischeri. On the whole, the antibacterial activity of the essential oils could be related to their main components, but the minor constituents may be involved in this process. Trans-cinnamic aldehyde and eugenol were the most active compounds in TLC-bioautography. The sensitivity of TLC-bioautographic method can be improved with using luminescent test bacteria. This method is more cost-effective and provides more reliable results in comparison with conventional microbiological methods, e.g. disc-diffusion technique

The Geography of Fear: A Latitudinal Gradient in Anti-Predator Escape Distances of Birds across Europe

All animals flee from potential predators, and the distance at which this happens is optimized so the benefits from staying are balanced against the costs of flight. Because predator diversity and abundance decreases with increasing latitude, and differs between rural and urban areas, we should expect escape distance when a predator approached the individual to decrease with latitude and depend on urbanization. We measured the distance at which individual birds fled (flight initiation distance, FID, which represents a reliable and previously validated surrogate measure of response to predation risk) following a standardized protocol in nine pairs of rural and urban sites along a ca. 3000 km gradient from Southern Spain to Northern Finland during the breeding seasons 2009–2010. Raptor abundance was estimated by means of standard point counts at the same sites where FID information was recorded. Data on body mass and phylogenetic relationships among bird species sampled were extracted from the literature. An analysis of 12,495 flight distances of 714 populations of 159 species showed that mean FID decreased with increasing latitude after accounting for body size and phylogenetic effects. This decrease was paralleled by a similar cline in an index of the abundance of raptors. Urban populations had consistently shorter FIDs, supporting previous findings. The difference between rural and urban habitats decreased with increasing latitude, also paralleling raptor abundance trends. Overall, the latitudinal gradient in bird fear was explained by raptor abundance gradients, with additional small effects of latitude and intermediate effects of habitat. This study provides the first empirical documentation of a latitudinal trend in anti-predator behavior, which correlated positively with a similar trend in the abundance of predators.TG was supported by the Human Frontier Science Program (RGY69/07) and MSM6198959212. JJ was supported by the EU Regional Development Foundation for the project (A31026). MD was funded by the project RISKDISP (CGL2009-08430) of the Spanish Ministerio de Ciencia e Innovación. GM was supported by TÁMOP-4.2.1./B-09/1-KMR-2010-0005 and TÁMOP-4.2.2./B-10/1-2010-0023 grants

A STOCHASTIC MODEL FOR A/D CONVERTERS

It is shown that a modified feedback measuring circuit for ADC-s can perform as a measuring system for ADC channel profile measurements (i.e. measurement of the stochastic behaviour). A mathematical model of the measurement is given. The measured data are used for constructing a stochastic model of the ADC. which provides us with information about ADC errors

Synthese, Aufbau und Eigenschaften käfigartiger vinyl- und allylsilylierter Kieselsäuren

Durch Umsatz des Tetramethylammoniumsilicats [N(CH3)4]8Si8O20 · 69 H2O mit Vinyldimethylchlorsilan (I) bzw. Divinyltetramethyldisiloxan oder Allydimethylchlorsilan wurden der Vinyldimethylsilylkieselsäureester [CH2CHCH2(CH3)2Si]8Si8O20 und Allyldimethylsilyl-kieselsäureester [CH2CHCH2(CH3)2Si]8Si8O20 erhalten. Mit Hilfe der Gaschromatographie, Massenspektroskopie sowie 1H-und 29Si-NMR wurden die Verbindungen charakterisiert und eine käfigartig aufgebaute Doppelvierring (D4R)-Struktur des Kieselsäuregerüsts nachgewiesen, an deren 8 terminalen O-Atomen des Kieselsäuregerüsts nachgewiesen, an deren 8 terminalen O-Atomen des Kieselsäuregerüsts Vinyldimethylsiyl- bzw. Allydimethylsilylgruppen gebunden sind. Durch Silylierung mit I und Trimethylchlorsilan sind in Abhängigkeit vom Mischungsverhältnis Vinyldimethylsilytrimethysily1-D4R-Kieselsäureester mit einer mittleren Anzahl ungesättigter Gruppen < 8 herzustellen

Microwave assisted heterogeneous catalysis: effects of varying oxygen concentrations on the oxidative coupling of methane

The oxidative coupling of methane was investigated over alumina supported La2O3/CeO2 catalysts under microwave dielectric heating conditions at different oxygen concentrations. It was observed that, at a given temperature using microwave heating, selectivities for both ethane and ethylene were notably higher when oxygen was absent than that in oxygen/methane mixtures. The differences were attributed to the localised heating of microwave radiation resulting in temperature inhomogeneity in the catalyst bed. A simplified model was used to estimate the temperature inhomogeneity; the temperature at the centre of the catalyst bed was 85 °C greater than that at the periphery when the catalyst was heated by microwaves in a gas mixture with an oxygen concentration of 12.5% (v/v), and the temperature difference was estimated to be 168 °C in the absence of oxygen

Nueva procuratela ecuestre en Carteia: a propósito de un hallazgo epigráfico en el complejo termal

En este artículo presentamos una nueva inscripción hallada en diciembre de 2002 en "Carteia (provincia Baetica)", en la que se da a conocer una nueva procuratela ecuestre y otras particularidades dignas de interés.In this paper the authors offer an unpublished latin Inscription found in "Carteia (provincia Baetica)" in december 2002. This Inscription contents a new equestris charge and other interesting particularities

Special Libraries, September 1976

Volume 67, Issue 9https://scholarworks.sjsu.edu/sla_sl_1976/1007/thumbnail.jp

Special Libraries, July-August 1971

Volume 62, Issue 7-8https://scholarworks.sjsu.edu/sla_sl_1971/1005/thumbnail.jp