Photoluminescence characterization of Al/Al₂O₃/InP MIS structures passivated by anodic oxidation

Metal-insulator-semiconductor (MIS) structures were produced by electron beam heating evaporation of Al₂O₃ on InP. Polyphosphate thin films with the thickness of 100 to 150 A were used to passivate the interface InP/Insulator. Photoluminescence spectra were obtained at low temperatures at the various stages of MIS-InP structure formation. At ambient temperature, photoluminescence topography made it possible to characterize the surface state after each technological stage. The interface degradation under the effect of repeated annealing is insignificant up to the temperatures close to 350 °C. Major radiative defects detected using photoluminescence spectrum with energies ranged from 0.95 to 1.15 eV were attributed to the impurity complexes of phosphorus vacancies, concentration of which is substantially reduced in the presence of anodic oxide

A study of the corrosion behaviour and protective quality of sputtered chromium nitride coatings

Nitride based hard coatings are widely used for mechanical applications. Among these coatings, chromium nitrides are especially interesting because they combine good tribological properties with relative chemical inertness. Corrosion-resistant nitrogen-doped chromium thin films were deposited by using an industrial magnetron reactive sputtering device. A precise control of the composition has permitted separate synthesis of the defined compounds that exist in the binary diagram Cr]N: Cr N and CrN. Potentiodynamic methods were used to investigate the corrosion protection provided on AISI 304 stainless steel 2 by various coatings. At the same time, coating microstructure was investigated by XRD and SEMrEDS as well as its tribological . properties hardness and wear resistance . The CrN coatings exhibit the higher wear resistance whereas the Cr N films show the 2 better hardness. Cr N coatings or CrN coatings have an inert intrinsic behaviour either in acidic or in chloride solutions. 2 However, their capability of protecting the substrate from any corrosion is limited due to defects and porosity. However, as a function of deposition parameters, these coatings can enhance the substrate lifetime in aggressive environments

Bivoltinism in Coenagrion mercuriale (Zygoptera: Odonata) in the southern margin of its distribution range: emergence pattern and larval growth

Voltinism is an important life history trait that varies with the environment. In temperate zones, insect populations take a substantially longer time to reach the adult stage in the northern compared to the southern regions. In this study, emergence pattern and larval growth of the threatened zygopteran (Odonata)Coenagrion mercurialewere investigated in a population located in the southern limit of its distribution range in order to determine its life history strategies in a hot climate and compare them to those displayed in northern populations. There was no apparent winter diapause. The species produced two generations in a year, with the first generation emerging in mid spring and the second in late summer. The emergence pattern of the first generation was typical of a summer species and lasted 48 days. All larvae emerged by the end of May. Due to some environmental perturbations, the emergence pattern of the second generation was not surveyed, but there was evidence that the emergence season was short (21 days). Larval structure prior to the second emergence of the year showed that only 25 % of the population was in the final instar, which explains the shorter emergence season. We assume that the first eggs laid in the spring hatch and grow rapidly to reach the final instar in late summer as a consequence of higher temperatures and potential high food availability. There was a significant seasonal decline in body size in both males and females. The second generation had a significantly smaller body size, presumably due to the short growth season and/or higher growth rate

Dragonfly Conservation in the Increasingly Stressed African Mediterranean-Type Ecosystems

Freshwater habitats worldwide are experiencing many threats from environmental and anthropogenic sources, affecting biodiversity and ecosystem functioning. In Africa, particularly in Mediterranean climate zones, rapid human population growth is predicted to have great impact on natural habitats besides naturally occurring events such as unpredictable drought frequency and severity. Here, we analyze the potential correlation between odonate assemblage conservation priority (measured with the Dragonfly Biotic Index: DBI) and the magnitude of climate change and human perturbation in African regions with a dominant Mediterranean climate, namely Northern (NAR: Morocco, Algeria and Tunisia) and Southern African region (SAR: South Africa). Using a compilation of studies assessing odonate assemblages in lotic and lentic habitats of both regions (295 sites in NAR and 151 sites in SAR), we estimated DBI, temporal change in average annual temperature (T), annual precipitation (P), and human footprint index (HFI) in each site, then we tested whether sites with different levels of DBI were associated with different magnitudes of climatic and anthropogenic change. We estimated past (between 1980–1999 and 2000–2018) and future changes (between 1980–1999 and 2081–2100) in T and P based on three CMIP6 scenarios representing low (SSP126), moderate (SSP245), and high emission (SSP585), as well as the change in HFI from 1993 to 2009. We found that assemblages with higher DBI (i.e. higher conservation priority) encountered lower increase in T and slightly greater decrease in P than assemblages with lower DBI (i.e. lower conservation priority) in NAR during 1980–2018, but are projected to experience higher increase in T and lower decrease in P in future projections for 2081–2100. In SAR, the increase in T was mostly similar across assemblages but the decline in P was higher for assemblages with higher DBI during 1980–2018 and 2081–2100, suggesting that assemblages of higher conservation priority in SAR are threatened by drought. While HFI showed an overall increase in NAR but not in SAR, its temporal change showed only minor differences across assemblages with different DBI levels. We discuss the importance of management plans to mitigate the effects of climatic and anthropogenic threats, so improving conservation of odonate assemblages in these regions