This work examines the relative importance of diffusion and the electrical time constant of the working electrode on the response time of amperometric gas sensors. The response curve of an electrochemical carbon monoxide sensor to a 200 ppm CO test gas was measured as a function of the added resistance that is in series with the working electrode to increase the time constant. It has been found that the response time increases with additional resistance. The experimental behavior was compared to the values predicted on the basis of Fick's second law of diffusion and to the values expected on the basis of the electrical properties of the sensor. The behavior of the sensor was explained using an equivalent electrical circuit, describing the time constants of the working electrode. Values obtained from this model were further compared to experimental values obtained from electrochemical impedance spectra. It has been found that the response time of the sensors depends on both the rate of diffusion and the electrical time constants of the working electrode.

In the present study, biochar from brewers’ spent grain was used, for the first time, to develop screen-printed electrodes. After having investigated the dispersion behaviour of biochar in different organic solvents, a biochar-based screen-printed electrode was prepared with the drop-casting technique. In order to understand the electrochemical potentiality and performances of the biochar/sensor tool, different electroactive species, i.e., ferricyanide, benzoquinone, epinephrine, ascorbic, and uric acids, were used. The results were compared with those of the same electrodes that were modified with commercial graphene, confirming that the proposed electrode showed improved electrochemical behaviour in terms of resolution, peak-to-peak separation, current intensity, and resistance to charge transfer. Furthermore, a tyrosinase biosensor was developed by direct immobilisation of this enzyme on the biochar/screen printed electrode, as an example of the potential of biochar for disposable biosensor development. The efficiently occurred immobilisation of the biochar on the screen printed electrode’s (SPE’s) surface was demonstrated by the observation of the working electrode with a scanning electron microscope. The detection was performed by measuring the current due to the reduction of the corresponding quinone at low potential, equal to −0.310 V for epinephrine. The experimental conditions for the tyrosinase immobilization and the analytical parameters, such as applied potential and pH of buffer, were studied and optimized. Under these conditions, the electrochemical biosensors were characterized. A linear working range of epinephrine was obtained from 0.05 up to 0.5 mM. The detection limit was 2 × 10−4 mM for the biosensor.

Biochar is generally considered as an effective soil amendment, which can improve soil organic matter and nutrients content and enhance crop productivity. In this study, biochar derived from brewers’ spent grain (BSG) was used in a pot and field experiment to assess whether its addition to soil could affect hop plant growth. The experiment was conducted in Central Italy during the period March–August 2017. Three different German cultivars of hop plant (Hallertau Magnum, Perle, Spalter spalt) were considered. Biochar was added to the pot soil at 20% level. Its effect on the roots was evaluated using multivariate image analysis (MIA) and the statistical technique of general linear models (GLM), whereas the shoots, bines length and yield using GLM. Results showed that biochar significantly improved root growth (p < 0.0001). Regarding shoots, no variability for the genotypes was observed during the vegetative period, whereas slight differences resulted before plant dormancy, especially for the Hallertau Magnum cultivar. No differences in the number of leaves or bines length were observed between the two treatments for all cultivars. The addition of biochar to the soil significantly improved yield (number of cones). These results highlighted that BSG-derived biochar can be useful to improve hop plant growth and cones production.

The provision n° A6505/29-11-2010 of the Lazio Region Agricultural Department states that the plant material resulting from the felling of palms infested by RPW (Rhynchophorus ferrugineus Olivier) must be disinfested by heat treatment or fine mechanical chipping, ensuring that the resulting materials obtained are of a size smaller than 2 cm. This paper describes changes made on one machine chipper FARMI mod. FOREST CH260 for use in the cutting of trees and palm leaves in accordance with the above mentioned provision. The analyzes carried out on the plant material shredded, according to methodology UNI CEN/TS 15149-1 - 2006, show that 94,78% of the fragments is smaller than 16 mm and a water content of 52.5%. In all fragments of the material shredded at least one of the three dimensions was less than 2 cm. A mix of chipped stipes and leaves of palm tree was tested at ENEA facilities to evaluate the ability of RPW larvae to feed and survive on this substrate. Ten plastic containers (130 liters) were filled up with 26 kg each of chipped matter and infested with larvae grouped by weight into 3 classes ranged from &lt; 0.15 g, 0.15 -;- 0.35 g and &gt; 0.35 g till 2 cm (3 containers for each class and 1 as control; 30 larvae for each container). Containers, covered with a metallic net, were kept in an isolated chamber, controlling temperature in order to maintain the substrate around 30°C. The substrate was inspected at 45 dd after infestation. No survival was recorded on the larvae, indicating that chipping technique could be a suitable method to destroy infested palm avoiding potential risks of re-infestation from the disposal sites.

Aim of study: To evaluate the susceptibility of the Rhynchophorus ferrugineus to electric discharges, to eventually use this application in synergy with other methods as part of an integrated control strategy.Area of study: Worldwide.Material and methods: Three different electric voltage intensities were applied to R. ferrugineus to investigate the insect’s susceptibility in both adult and larval stages. The transmission and diffusion of electricity within a portion of the palm tree was tested. In addition, the suitability of containment materials for handling and transportation of plant residues was tested.Main results: The results of adult test showed that the total number of eggs laid per mating couple and the number of larvae born were about 1.5 times higher in the control compared to the electrified samples. The duration of the electric discharge on larvae had a small impact on the mortality rate, while the electric voltage showed a strong impact on mortality (87% for 10 V and 99% for 15 V). The presence of a significant electric current was observed in a viable portion of stem (distance from the source of electricity 10 cm) providing a direct current with 250 V tension. Among the materials tested for the transportation of palm residues, the aluminium net sheet showed the best results in the containment of both larval and adult individuals.Research highlights: Electrocution has proven to be a system which can help in the control of red palm weevil reducing the use of synthetic chemicals.