Polypyrrole/polyacrylonitrile composite films: Dielectric, spectrophotometric and morphologic characterization

Spectrophotometric, morphologic and dielectric properties of polyacrylonitrile (PAN) composite films in the presence of pyrrole derivatives were reported in this paper. The composite films were fabricated by oxidative polymerization of pyrrole (Py), N-methyl pyrrole (NMPy) and N-phenyl pyrrole (NPhPy) by cerium(IV) on polyacrylonitrile matrix. The effect of temperature on the dielectric properties was studied in the frequency range from 0.05 Hz up to 10 MHz and in the temperature range from 0 °C up to 250 °C. Conductivity was increased with temperature due to increase of the mobility of charge carriers in the composite films. By increasing the temperature, the dipoles become free and respond to the applied electric field in composite structure; thus, the polarization and dielectric constant increases. PNPhPy-PAN composite films exhibited the highest dielectric constant, AC conductivity and tan delta.     

Effects of Nutrient Antagonism and Synergism on Yield and Fertilizer Use Efficiency

Interaction among plant nutrients can yield antagonistic or synergistic outcomes that influence nutrient use efficiency. To provide insight on this phenomenon, peer-reviewed articles were selected that quantified the interaction effects of nutrients on crop yield levels. In total 94 articles were selected that described 117 interactions between all macro- and micronutrients for different agricultural crops. In 43 cases the interaction was synergistic, in 17 cases the interaction was antagonistic, and in 35 cases the interaction was zero-interaction; the other 23 cases were non-significant (16) or showed a negative response (7). Generally: (a) when the availability of two nutrients is characterized as deficient, a large increase in yield can be expected by diminishing these deficiencies: (b) for most macronutrients the mutual interactions on yield levels are synergistic; and (c) antagonistic effects on yield are often found for divalent cations. Knowledge of nutrient interactions can guide fertilizer design and optimization of fertilization strategies for high yields and high nutrient use efficiencies.     

Spatial Distribution of Ambrosia-Beetle Catches: A Possibly Useful Knowledge to Improve Mass-Trapping

Several species of ambrosia beetles (Coleoptera: Scolytidae) have recently started attacking standing, living beeches (Fagus sylvatica) in southern Belgium. In 2001, 1.3 million m³ of apparently healthy trees were struck. So far the outbreak has been limited to the Ardenne, and partly the Gaume, areas, and Brussels has been untouched. The city of Brussels is surrounded by a vast 4300 ha forest, mainly planted with beech, the Forêt de Soignes, of invaluable ecological and recreational value, of which 1600 ha belong to the regional authorities. In the spring 2001, these latter commissionned a study to assess the new threat to the forest. A 500 m×500 m grid of small traps, baited with ethanol and lineatin, was deployed over the regional part of the forest. The main species caught were Trypodendron domesticum, Anisandrus dispar and, in high numbers, Xylosandrus germanus, an exotic species of Asian origin found for the first time in Belgium in 1994. Whilst there was a consistent homogeneity between catches within the same sites (2 traps/site, distant by 2–6 m), there were no spatial relationships between catches at larger distances for T. domesticum and A. dispar. For X. germanus, spatial autocorrelations were observed within distances of 2000 m, suggesting that this species has sufficient mobility to cover this range. The planning of the 2002 trapping campaign will take this information into account: the traps will be deployed within a smaller grid.     

Successful mechanical eradication of spotted bass (Micropterus punctulatus (Rafinesque, 1819)) from a South African river

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Towards sustainable forest management in the European Union through polycentric forest governance and an integrated landscape approach

Context

Achieving sustainable development as an inclusive societal process, and securing sustainability and resilience of human societies as well as the natural environment are wicked problems. Realising sustainable forest management (SFM) policy in local landscapes is one example.

Objectives

Using the European Union as a case study for the implementation of SFM policy across multiple governance levels in different contexts, we discuss the benefits of adopting an integrated landscape approach with place and space, partnership and sustainability as three pillars.

Methods

We map the institutional frameworks for implementing SFM policy within all EU member states. Next, we analyse whether or not there is EU-level forest governance, and how power is distributed among EU, member state and operational levels.

Results

Mechanisms to steer a centralized forest governance approach towards SFM in the EU are marginal. Instead, there is a polycentric forest governance with 90 national and sub-national governments, which create and implement own and EU-wide SFM-related policies. Additionally, both among and within regional governance units there is a large variation in governance arrangements linked to land ownership at the operational level.

Conclusions

To effectively translate EU-wide SFM and SFM-related policies into action in local landscapes, it is crucial to acknowledge that there are different land ownership structures, landscape histories and alternative value chains based on multiple ecosystem services. Therefore regionally adapted landscape approaches engaging multiple stakeholders and actors through evidence-based landscape governance and stewardship towards sustainable forest landscape management are needed. Model Forest, Long-Term Socio-Ecological Research platform and Biosphere Reserve are three of many examples.

     

First detection of Bursaphelenchus mucronatus (Nematoda: Aphelenchoididae) on Monochamus sutor (Coleoptera: Cerambycidae) in Romania

As a result of the detection of the pinewood nematode Bursaphelenchus xylophilus in Portugal, and its subsequent spread to Spain, intense surveys were conducted to screen for the presence of Bursaphelenchus species in Romania. Herein, we report recent surveys of insects potentially vectoring Bursaphelenchus species collected using trap trees or pheromone‐baited traps placed in the forest. Trap felled spruce trees (Picea abies) and pheromone‐baited traps were installed in six different counties in Romania (Bra?ov, Sibiu, Suceava, Hunedoara, Timi? and Dâmbovi?a). Ten different species of insects distributed among Curculionidae and Cerambycidae were obtained. Nematodes were extracted from insects and observed to validate the presence of Bursaphelenchus specimens. One female identified as Monochamus sutor was the only specimen carrying nematodes in the genus Bursaphelenchus. Nematodes were identified as B. mucronatus based on morphological and molecular features. This is the first detection and report of natural spread of B. mucronatus in Romania. The absence of B. xylophilus was confirmed in the areas of Romania surveyed in this work.     

The adoption of drones in German agriculture: a structural equation model

Drones are one of the latest tools to have been added to farmers’ precision agriculture technology tool kit. Despite the proclaimed benefits, adoption rates of drones are low and literature regarding the adoption of drones in agriculture is scarce. Therefore, this study investigates whether an extended Technology Acceptance Model (TAM) can contribute to the understanding of latent factors influencing farmers’ intention to adopt a drone. The sample of 167 German farmers was collected in 2019 via an online survey. Using partial least squares structural equation modelling and a binary model, the TAM explains 69% of the variance in the intention to use a drone by German farmers. According to the results, raising farmers’ awareness of farm-specific areas of drone application and the confidence level of using a drone can increase farmers’ intention to adopt a drone. The results are of interest for agribusinesses developing drones as well as selling or providing drones. Furthermore, the results are of interest for researchers in precision agriculture technologies.

     

Removal of Copper Ions from Simulated Wastewaters Using Different Bicomponent Polymer Membranes

Polybrominated diphenyl ethers (PBDEs) are a class of global flame retardants whose residues have markedly increased in fish and human tissues during the last decade. They belong to persistent and toxic contaminants which need more attention and toxicological study as their degradation in the environment is not well understood. This study characterizes 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) bioconcentration, elimination and biotransformation in juvenile turbot Psetta maxima, in order to evaluate the risk of its bioaccumulation in the marine environment. During this study, juvenile turbot were exposed to environmentally relevant BDE-47 concentrations from 0.001 to 1 μg/L for 16 days via aqueous exposure. This study found that juvenile turbot bioconcentrated and biotransformed BDE-47. There was no difference in standard length or weight between control and exposed fish. Uptake and elimination of BDE-47 by the turbot during exposure were examined in controlled laboratory experiments. Bioconcentration of BDE-47 was similar in fish from all treatment groups. Bioconcentration was rapid and increased with exposure time, since the bioconcentration factor (BCF) was higher. However, elimination was slower in comparison and low elimination was detected after 10 days in clean water. BDE-47 concentration in water influences the BCF. Half-life ranged between 37 and 108 days and theoretical times t ₉₀ could range from 120 to 358 days. The present study demonstrates a stepwise debromination of BDE-47 to BDE-28.