Search results for "angling"
showing 10 items of 99 documents
Sicilians are not easily hooked! first assessment of the impact of recreational fishing on the endemic sicilian pond turtle emys trinacris (Testudine…
2020
The possible impact of recreational fishing on the Sicilian pond turtle Emys trinacris was investigated in two permanent water bodies in western Sicily (Italy). Overall, 120 specimens were temporarily captured and X-rayed in order to determine the possible presence of fishhooks in their mouth, throat, or gastrointestinal tract. At the studied sites, none of the Xrayed turtles showed any evidence of ingested fishhooks or other fishing gears, thus suggesting limited impact of recreational fishing. However, the occasional but not negligible findings of E. trinacris specimens injured by fishhooks or entangled in abandoned fishing lines prove the actual existence of such impact, raising some con…
Effects of temperature on electron paramagnetic resonance of dangling oxygen bonds in amorphous silicon dioxide
2011
The properties of electron paramagnetic resonance (EPR) signal of oxygen dangling bonds in amorphous SiO2 ("non-bridging oxygen hole centers", NBOHC) in excimer laser-irradiated amorphous SiO2 were studied in the temperature range 20K to 295K. NBOHCs strongly affect optical and chemical properties of amorphous SiO2 -based (nano) structures and their surfaces. The behaviour of their EPR signal is complicated due to a nearly degenerate electronic ground state. It was found that EPR signal has a non-Curie (~1/T) T-dependence down to 40K, indicating that EPR-based concentration estimates routinely obtained at T = 77K underestimate the center concentrations at least by a factor of 1.7. The estim…
Diffusion and reactions of interstitial oxygen species in amorphous SiO2: A review
2008
This article briefly summarizes the diffusion and reactions of interstitial oxygen species in amorphous SiO 2 (a-SiO 2 ). The most common form of interstitial oxygen species is oxygen molecule (O 2 ), which is sensitively detectable via its characteristic infrared photoluminescence (PL) at 1272 nm. The PL observation of interstitial 0 2 provides key data to verify various processes related to interstitial oxygen species: the dominant role of interstitial O 2 in long-range oxygen transport in a-SiO 2 ; formation of the Frenkel defect pair (Si-Si bond and interstitial oxygen atom, 0°) by dense electronic excitation; efficient photolysis of interstitial O 2 into O° with F 2 laser light (λ= 157…
Southern Ocean areas of endemism: a reanalysis using benthic hydroids (Cnidaria, Hydrozoa)
2013
The biogeographic history of the Southern Ocean (SO) fauna is complex and poorly studied, especially the areas of endemism. We reanalyzed the data of Marques & Peña Cantero (2010), along with other geographical records of endemic benthic hydroids below 45°S. A Parsimony Analysis of Endemicity (PAE) based on 5° latitude by 5° longitude matrix with 61 species resulted in eight areas of endemism. We discuss these results in the context of different hypotheses of the evolution of the SO fauna and previously proposed biogeography patterns.
Structural, chemical and dynamical trends in graphene grain boundaries
2010
Grain boundaries are topological defects that often have a disordered character. Disorder implies that understanding general trends is more important than accurate investigations of individual grain boundaries. Here we present trends in the grain boundaries of graphene. We use density-functional tight-binding method to calculate trends in energy, atomic structure (polygon composition), chemical reactivity (dangling bond density), corrugation heights (inflection angles), and dynamical properties (vibrations), as a function of lattice orientation mismatch. The observed trends and their mutual interrelations are plausibly explained by structure, and supported by past experiments.
Role of Mobile Interstitial Oxygen Atoms in Defect Processes in Oxides: Interconversion between Oxygen-Associated Defects inSiO2Glass
2004
The role of mobile interstitial oxygen atoms (${\mathrm{O}}^{0}$) in defect processes in oxides is demonstrated by interconversion between the oxygen dangling bond and the peroxy radical (POR) in ${\mathrm{S}\mathrm{i}\mathrm{O}}_{2}$ glass. Superstoichiometric ${\mathrm{O}}^{0}$ was created by ${\mathrm{F}}_{2}$ laser photolysis of the interstitial ${\mathrm{O}}_{2}$. On annealing above $300\text{ }\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, ${\mathrm{O}}^{0}$ migrated and converted the oxygen dangling bond to POR. Exposure to 5.0 eV light converted POR back to a pair of the oxygen dangling bond and ${\mathrm{O}}^{0}$ (quantum yield: $\ensuremath{\sim}0.1$). These findings suggest that…
Ab initio calculation of wurtzite‐type GaN nanowires
2007
Ab initio calculations of wurtzite-type GaN nanowires have been performed using density functional theory. Different shapes of nanowires of with similar diameters of around 2 nm have been considered to determine the stability of the structures. The quantitative similarities in the local properties obtained and dangling bond energies of nanowires and bulk surfaces have lead to a simple model model for a calculation of effective Young's modulus of nanowires of arbitrary diameters and shapes. The size dependence of the Young's modulus reveals a softening of GaN nanowires with the decrease of the diameter. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Artificial dam lakes as suitable habitats for exotic invertebrates: Ostracoda ecology and distribution in reservoirs of the Eastern Iberian Peninsula
2014
Reservoirs are the most common deep lakes in Spain, as a consequence of water needs and dry climate. Although these aquatic systems can play an important ecological role in such an area with few large natural lakes, they can also provide new habitats for exotic species, which can colonize ecosystems that native species have not explored yet. Here we present our results for a biannual survey of the ostracod fauna from 24 reservoirs in Xuquer River basin. We check which variables affect ostracod presence, test for differences between winter and summer assemblages, and compare our data with previous available ostracod records from the same river drainage network. Our results reveal that ostrac…
Trawling disturbance effects on the trophic ecology of two co-generic Astropectinid species
2015
Physical disturbance by trawling can have both negative and positive effects on populations of scavenging benthic organisms. In the present study the impact of fishing activity on feeding behaviour of the two Astropectinids, Astropecten bispinosus and A. irregularis , was assessed based on stomach contents analysis. The study was carried out along trawled seabed highlighting the positive response of the two facultative scavengers to carrion generated by trawl disturbance. Furthermore, there was greater food specialization in areas that were more heavily exploited by trawling. This specialisation could be linked to the availability of certain prey that results from the passage of fishing gea…
Crucial dependence of excimer laser toughness of “wet” silica on excess oxygen
2011
Creation of point defects by ArF (6.4 eV) and F2 laser (7.9 eV) irradiation in synthetic “wet” silica glass thermally loaded with interstitial O2 molecules was studied by optical absorption, electron paramagnetic resonance and infrared absorption. The presence of excess oxygen caused a significant increase of laser-induced ultraviolet (UV) absorption, which was 4 times (7.9 eV-irradiation) and > 20 times stronger (ArF irradiation) as compared to O2-free samples. The spectral shape of photoinduced absorption nearly completely coincided with the spectral shape of oxygen dangling bonds (NBOHC) in 3 to 6.5 eV regions. The contribution of Si dangling bonds (E' centers) was less than few % and wa…