Search results for "trapping"
showing 10 items of 266 documents
Photoreactivity of Iron-Doped Titanium Dioxide Powders for Dinitrogen Reduction to Ammonia
1989
The production of NH3 from N2 and H2O on Fe/TiO2 has been studied in a continuous photoreactor under UV radiation. An ESR study of the catalysts shows that Fe3+ ions are better electron traps than Ti4+ ions. This trapping can be irreversible if the corresponding holes originate stable species adsorbed on the catalyst surface. The charge separation, thus favoured by the Fe3+ ions, helps the N2 adsorption by its reaction with surface species activated by holes. The best activity is found when no excess Fe is segregated at the surface; overall turnover for N2 reduction as high as 6 e−/Fe atom can be reached before catalyst deactivation.
Trapping and Immobilization of DNA Molecules Between Nanoelectrodes
2011
DNA is one of the most promising molecules for nanoscale bottom-up fabrication. For both scientific studies and fabrication of devices, it is desirable to be able to manipulate DNA molecules, or self--assembled DNA constructions, at the single unit level. Efficient methods are needed for precisely attaching the single unit to the external measurement setup or the device structure. So far, this has often been too cumbersome to achieve, and consequently most of the scientific studies are based on a statistical analysis or measurements done for a sample containing numerous molecules in liquid or in a dry state. Here, we explain a method for trapping and attaching nanoscale double-stranded DNA …
High-contrast sub-Doppler absorption spikes in a hot atomic vapor cell exposed to a dual-frequency laser field
2017
International audience; The saturated absorption technique is an elegant method widely used in atomic and molecular physics for high-resolution spectroscopy, laser frequency standards and metrology purposes. We have recently discovered that a saturated absorption scheme with a dual-frequency laser can lead to a significant sign reversal of the usual Doppler-free dip, yielding a deep enhanced-absorption spike. In this paper, we report detailed experimental investigations of this phenomenon, together with a full in-depth theoretical description. It is shown that several physical effects can support or oppose the formation of the high-contrast central spike in the absorption profile. The physi…
Habitat Determinants and Density of the Endemic Sicilian Rock Partridge Alectoris graeca whitakeri on Mt. Etna, Sicily, Italy
2022
The assessment of the conservation status of a species is the first step to prevent local extinction and to plan appropriate, effective and scientifically sound conservation actions, hence knowledge of the distribution, population trends and characteristics of preferred habitat is crucial for the conservation of a species. Galliformes are facing increasing threats related to overhunting, habitat loss and fragmentation, and human disturbance. The Sicilian Rock Partridge (hereafter Rock Partridge) Alectoris graeca whitakeri is a significant conservation unit endemic to Sicily (Italy) classified as Near Threatened by the IUCN due to a decreasing population. Few studies have been conducted on t…
The effect of the Spanish Law of Political Parties (LPP) on the attitude of the Basque Country population towards ETA: A dynamic modelling approach
2013
Abstract In June 2002, the Spanish Government passed the “Law of Political Parties” (LPP) with the aim, among others, of preventing parties giving political support to terrorist organizations. This law affected the Basque nationalist party “Batasuna”, due to its proved relation with ETA. In this paper, taking data from the Euskobarometro (Basque Country survey) related to the attitude of the Basque population towards ETA, we propose a dynamic model for the pre-LPP scenario. This model will be extrapolated to the future in order to predict what would have happened to the attitude of the Basque population if the law had not been passed. These model predictions will be compared to post-LPP dat…
Determinants of jaguar occupancy at the northern range edge
2020
Identifying factors promoting jaguar (Panthera onca) occupancy is crucial for planning effective conservation and management actions that can contribute to long-term population viability. We used camera-trapping and modeled factors affecting detection and occupancy for jaguars in Sonora at 149 sites during August-November 2008 and 2009. We measured 24 covariates presumed to affect detection (n = 6) and occupancy (n = 18) at camera sites, including sampling period and various habitat characteristics. We obtained 29 jaguar detections at 19 sites (naive occupancy = 0.12) in 5455 trap-days of effort. Jaguar detectability (p = 0.16 +/- 0.05) was negatively affected by human presence and varied b…
Deep traps in InGaN/GaN single quantum well structures grown with and without InGaN underlayers
2020
The electrical properties and deep trap spectra were compared for near-UV GaN/InGaN quantum well (QW) structures grown on free-standing GaN substrates. The structures differed by the presence or absence of a thin (110 nm) InGaN layer inserted between the high temperature GaN buffer and the QW region. Capacitance-voltage profiling with monochromatic illumination showed that in the InGaN underlayer (UL), the density of deep traps with optical threshold near 1.5 eV was much higher than in the QW and higher than for structures without InGaN. Irradiation with 5 MeV electrons strongly increased the concentration of these 1.5 eV traps in the QWs, with the increase more pronounced for samples witho…
Responses of Rhynchophorus ferrugineus adults to selected synthetic palm esters: electroantennographic studies and trap catches in an urban environme…
2011
The Red Palm Weevil (RPW), Rhynchophorus ferrugineus Olivier, accidentally introduced in the European countries facing the Mediterranean basin, is becoming the most serious pest for ornamental palms in the urban environment. In our work we tested electroantennogram (EAG) and behavioural responses of RPW adults to five selected synthetic palm esters: ethyl propionate, ethyl butyrate, ethyl isobutyrate, ethyl lactate and ethyl acetate. EAG bioassays showed higher sensitivity of female antennae compared to male antennae for test compounds. Differences were also recorded in the EAG responses using different esters and doses. Ethyl propionate was the synthetic ester that elicited the strongest r…
Free-volume Study in GeS2-Ga2S3-CsCl Chalcohalide Glasses Using Positron Annihilation Technique
2015
Abstract Positron annihilation lifetime spectroscopy combined with Doppler broadening of annihilation radiation was applied to study free-volume entities in Ge-Ga-S glasses having different amount of CsCl additives. It is shown that the structural changes caused by CsCl additives can be adequately described by positron trapping modes determined within two-state model. The results testify in a favor of rather unchanged nature of corresponding free-volume voids responsible for positron trapping in the studied glasses, when mainly concentration of these traps is a subject to most significant changes with composition.
Supplementing air with CO2 stripped from recirculating aquaculture improves growth of two green microalgae in aquaculture wastewater
2023
To improve sustainability and to implement the principles of circular economy in aquaculture, we tested the possibility to boost the capture of nitrate by two green microalgal species from recirculating aquaculture system's (RAS) wastewater by supplementing air with carbon dioxide stripped from a RAS. Carbon dioxide addition increased cell densities of Monoraphidium griffithii and Haematococcus pluvialis in photobioreactors during 9-day growing periods. However, growth rates and nitrate uptake rates were only improved for M. griffithii. Addition of CO2 decreased pH of the medium with M. griffithii which likely also affected positively on algal growth and nutrient uptake. These laboratory sc…