Erbium-doped silicon nanocrystals grown by r.f. sputtering method: competition between oxygen and silicon to get erbium

Erbium doped micro- and nanocrystalline silicon thin films have been deposited by co-sputtering of Er and Si. Films with different crystallinity, crystallite size, hydrogen and oxygen content have been obtained in order to investigate the effect of the microstructure and composition of matrix on the near IR range at 1.54 µm Er-related photoluminescence (PL) properties. The correlation between the optical properties and microstructural parameters of the films is investigated using spectroscopic ellipsometry. It is found that the luminescent properties of these composite films can be understood on the basis of the ellipsometric analysis that reveals the films heterogeneous structure, and that Er-related PL dominates in films with 1-3 nm sized Si nanocrystals embedded in a-Si:H.INTAS Project #03-51-6486Fundação para a Ciência e a Tecnologia Project POCTI/CTM/39395/200

Interrelation between microstructure and optical properties of erbium-doped nanocrystalline thin films

Nanocrystalline silicon thin films codoped with erbium, oxygen and hydrogen have been deposited by co-sputtering of Er and Si. Films with different crystallinity, crystallite size and oxygen content have been obtained in order to investigate the effect of the microstructure on the photoluminescence properties. The correlation between the optical properties and microstructural parameters of the films is investigated by spectroscopic ellipsometry. PL response of the discussed structures covers both the visible wavelength range (a crystallite size-dependent photoluminescence detected for 5–6 nm sized nanocrystals embedded in a SiO matrix) and near IR range at 1.54 microm (Er-related PL dominating in the films with 1–3 nm sized Si nanocrystals embedded in a-Si:H). It is demonstrated that the different PL properties can be also discriminated on the basis of ellipsometric spectra

Updated distribution of Osmoderma eremita in Abruzzo (Italy) and agro-pastoral practices affecting its conservation (Coleoptera: Scarabaeidae)

New records of Osmoderma eremita (Scopoli, 1763) (Coleoptera: Scarabaeidae: Cetoniinae) are reported for Abruzzo (Italy), together with a review of its distribution in this region. O. eremita is a saproxylic beetle dependent on the presence of hollow deciduous trees with abundant wood mould in their cavities. The major threats for the species are habitat loss and fragmentation. EU Habitats Directive requests to the member States its protection and the monitoring of its conservation status. Detection of its occurrence is the first step to protect the species. The surveys have been carried out in ten sites of Abruzzo by using black cross-windows traps baited with specific pheromone. The species has been recorded for the first time in the Sant'Antonio forest and its presence is confirmed in the Peligna Valley, after a decade. The populations seem to be confined to small patches of suitable habitats. At local level, the abandonment of the pollarding practice (willow and beech forests) and the use of pollarded trees as biomass for fuel are the major threats for this species. Indeed some key actions, such as the protection of old hollow trees and the continuation of pollarding practice in rural landscape, could be key factors for the conservation strategies of the species in the study area

Presence and distribution of the brown bear (Ursus arctos) in Friuli Venezia Giulia, from 2004 to 2011, through the non-invasive genetic monitoring ad conservation implications

After having disappeared at the beginning of 1900, the brown bear has started in a late 1960s a slow process of recolonization of the north-eastern Alps, through an expansion of Dinaric population. At the end of the 1990s the University of Udine began the occasional monitoring of the species and from 2004 non-invasive genetic monitoring became systematic. In the last 8 years 217 hair traps have been activated in the region to monitore: Natisone Valleys, the Julian and Carnic Alps and Prealps. Twenty-six hair traps were monitored in all years, whereas 40 were observed only in 2004, 2007 and 2011. The 26 hair traps constantly monitored from 2004 to 2011 showed 17% of average success of hair’s collecting (brown bear samples collected/day control: BBSD). The 40 hair traps, monitored in the window period, showed 12% of BBSD. The BBSD value varied in relation to both season (highest in spring) and year, with a dramatic decline from 2008, and interaction between year and area. From 2004, 13 genotypes, through systematic hair traps monitoring, were identified, while only 2 genotypes were sampled opportunistically. It was observed a high turnover of the genotypes: only 7 genotypes were sampled for more than 2 years (47% of total), 4 genotypes (27% of the total) were sampled for 3 years or more. The annual attendance of bear have been constant from 2004 to 2007, with 5-6 genotypes present every year. In the period between 2008 and 2010 there was a drastic decrease in the successful collection at the hair traps, with and average of 1-2 animals genotyped per year. However, opportunistic samples have increased in the recent times, probably due to the arrivals of 3 genotypes from Trentino (KJ2G2 in 2009 and DG2 and MJ4 in 2011). The year 2011 showed a further increase in the presence of bears with 5 animals genotyped in Friuli Venezia Giulia. Three of these animals belonged to the Slovenian population, while the other 2 genotypes were from the Trentino population. The results seem to confirm the exchange of some individuals between the Dinaric and central alpine population. As an example, the dinaric bear M5 was genotyped in Friuli Venezia Giulia in 2008 and then sampled in 2009 and captured in 2010 in Trentino and finally slot in Slovenia in 2011. The distribution in the alpine and prealpine areas has changed year by year: from the 2004 to 2007 the Natisone Valley and the Julian prealpine areas along the border with Slovenia were the areas more used, whilst from 2009 there was an apparent higher presence of bears in the Carnian Prealps and Alps, and in the Julian Alps. This shift could be due to human disturbance (i.e hunting management), control of the species carried out in neighbouring Slovenia, with a decreasing of immigrant from dinaric populations, and new immigration of bears from the central Alps. The present work has highlighted the necessity for a trans-regional and cross-border management of the species, especially in consideration to the population control applied in Slovenia, which seem to limit the Dinaric population expansion in the Alps, and furthermore the philopatry behaviour of bear females, which implies the absence of females in Friuli Venezia Giulia and induces a movement bach to Slovenia (at least 3 bears genotyped in Italy were shot in Slovenia). All these elements seem to exert important limitations to the consolidation and stabilization of the population of brown bears in north-eastern Alps. From the methodological point of view the protocol of systematic non-invasive genetic monitoring, shared at the trans-regional and trans-boundary level, is fundamental to monitore the dynamics and distribution of bear; the protocol should follow a systematic experimental design and should be integrated with a efficient opportunistic data collection

The structure and photoluminescence of erbium-doped nanocrystalline silicon thin films produced by reactive magnetron sputtering

We have produced and studied undoped and erbium-doped nanocrystalline silicon thin films in order to evaluate the erbium influence on the film microstructure and how this correlates with the photoluminescence properties. Films were grown by reactive RF sputtering. For the doped films metallic erbium was added to the c-Si target. The structural parameters and the chemical composition of the different samples were investigated by X-ray in the grazing incidence geometry, Raman spectroscopy, ellipsometry and Rutherford Back Scattering. The effect of the nc-Si/SiOx matrix ,i.e., nc-Si volume fraction and the presence of SiO and/or SiO2 phases, on the erbium photoluminescence efficiency is discussed.(undefined

Dielectric function of nanocrystalline silicon with few nanometers (<3 nm) grain size

The dielectric function of nanocrystalline silicon (nc-Si) with crystallite size in the range of 1 to 3 nm has been determined by spectroscopic ellipsometry in the range of 1.5 to 5.5 eV. ATauc–Lorentz parameterization is used to model the nc-Si optical properties. The nc-Si dielectric function can be used to analyze nondestructively nc-Si thin films where nanocrystallites cannot be detected by x-ray diffraction and Raman spectroscopy

Spectroscopic ellipsometry study of the layer structure and impurity content in Er-doped nanocrystalline silicon thin films

Er doped nc-Si thin films have been investigated by spectroscopic ellipsometry (SE). The optical response of Er ions in a nc-Si/SiO matrix has been determined by SE, and it has been used to detect Er contents as low as 0.2 at%. The complex layered nanostructure of nc-Si:Er:O has been resolved and it has been found that it is strongly influenced by the Er-doping and the oxygen in-depth distribution profile. SE results are discussed in comparison with data obtained by the standard methods of the X-ray diffraction, Rutherford backscattering and Raman spectroscopy

Performance of SNP markers for parentage analysis in the Italian Alpine brown bear using non-invasive samples

Determination of parentage provides valuable information for the conservation of wild populations, for instance, by allowing the monitoring of breeding success and inbreeding. Between 1999 and 2002, nine brown bears (Ursus arctos) were translocated to augment the remnant population of a few surviving individuals in the Italian Alps, but only part of them reproduced, with a higher inbreeding risk occurrence in the long-time. Currently, in the Alpine population, parentage tests are assessed through the analysis of 15 microsatellite loci (STRs), but the reduction of genetic variability in future generations will need the use of additional informative markers. Single nucleotide polymorphisms (SNPs) have been proven to be useful and reliable in individual identification and family reconstruction; moreover, they can perform well on low-quality samples. In this study, we analysed 51 SNPs to generate a SNP multilocus genotype dataset of 54 Alpine brown bears (Ursus arctos) and compared its performance in parentage analysis with the validated STR dataset. We found that SNPs alone are not sufficient to determine parentage relationships, but the combination of SNPs and STRs provided unambiguous parentage assignments. The combined panel also performed better than STRs when true parents were not present in the dataset and, consequently, showed higher values of assignment probabilities

CT-GUIDED TRANSTHORACIC NEEDLE BIOPSY: ADVANTEGES IN HISTOPATHOLOGICAL AND MOLECULAR TESTS

Aim: The present study aimed to demonstrate that computed tomography-guided transthoracic needle biopsy (TTNB) is a safe procedure that gives a more accurate pre-operative tissue diagnosis for peripheral lung nodules than transthoracic needle aspiration, obtaining suitable samples for molecular test in lung adenocarcinomas. Patients and methods: Between December 2016 and March 2018 at Thoracic Surgery Department of the University of Palermo - Policlinico Paolo Giaccone Hospital, TTNB was performed in 42 patients with computed tomography-detected peripheral lung nodules &gt; 10 mm, using 16-18 -Gauge tru-Cut needles. Results: With TTNB, we have estimated an accuracy for tissue diagnosis of 97,6%. At the molecular test, EGFR overexpression and ALK mutation resulted positive for 12/23 patients with lung adenocarcinoma. Conclusion: TTNB has showed a low rate of complications and it is adoptable as standard diagnostic procedure for peripheral lung nodules