Vibration risk evaluation in hand-held harvesters for olives

This research aims to evaluate the vibration transmitted to the hand-arm system by two electric portable harvesters, different for size and teeth features of the harvesting head. Moreover, being the bars of the two machines telescopic, they were operated at minimum and maximum length. The acceleration was measured, at different times, in two points, 1 m apart, next to the hand positions. Finally, measurements were carried out both at no load, in standard controlled conditions, and in field, under ordinary working conditions. To smooth the influence of external factors, the machines were operated by the same operator. The results showed that the greater and heavier harvesting head produced significantly higher acceleration at no load (10.7 m/s2 vs. 5.5 m/s2), and comparable acceleration at load (13.9 vs. 14.2 m/s2). On average, the vibration was significantly higher at load (14.0 vs. 8.1 m/s2). The difference between the two bar lengths was not statistically significant: 9.4 m/s2 when using the minimum length and 9.8 m/s2 when using the maximum one. Finally, the difference between the two measuring points was affected by the bar length: it was statistically significant when using the bar at its minimum length only. As far as the components are concerned, at no load the highest acceleration was measured along the bar axis for both harvesting heads (9.2 m/s2 for the greater head and 4.2 m/s2 for the smaller one). At load all the three components were comparable in the greater head (about 7.8 m/s2) whereas the x component was predominant in the other one (11.4 vs. 4.8 (y) and 6.6 m/s2 (z))

Ping-Pong Electron Transfer through DNA

Herein we describe a novel Ir system that is able to promote the reduction of pyrimidine bases from a distance without the presence of an external quencher. Instead, DNA-mediated ET is triggered by DNA-mediated HT. Thus, photoactivation of these Ir assemblies results in both a forward and a reverse pattern for charge migration, which we term ping-pong electron transfer through DNA (Scheme 1)

Simulation of Water Sensitive Papers for Spray Analysis

Aim of this study was to simulate the water sensitive paper (WSP) behaviour for estimate the unitary spray deposition on the target at varying spray features and target coverage.  WSP images were produced assuming some simplifying hypotheses: spherical drops and circular stains randomly placed on the images. Sprays were described in terms of probability distribution function (PDF) of drop size (log-normal and Rosin-Rammler), coefficient of variation of diameters (CV), arithmetic mean diameter (AMD), and volume median diameter (VMD).  The results from the simulations showed that the overlap between stains was independent of spray features: when the percentage of covered surface of WSP images ranged from 4.7 up to 61.6%, the overlap between stains ranged from 0.3 up to 33.4%.   On the contrary, unitary deposit (volume per square centimetre, mL cm-2) and particle density (number of distinct particles per square centimetre, cm-2) could be obtained from the percentage of covered surface if CV, AMD, VMD and PDF were known.  However, assuming as spray parameter the VMD, the drop size distribution had almost no effect on the unitary deposit: with the same percentage of covered surface, the Rosin-Rammler PDF provided an estimate of the unitary deposit higher than log-normal distribution between 5 and 7% only

Operator Dermal Exposure to Pesticides in Tomato and Strawberry Greenhouses from Hand-Held Sprayers

Protection of greenhouse crops in southern Italy usually requires 15–20 phytosanitary treatments per year, with volume rates in the range of 1000–2000 L ha1, depending on the plant growth stage. The most widespread sprayers are hand-held, high-pressure devices, which may expose operators to high levels of pesticides. This paper, also with the aim to lead toward a more sustainable use of greenhouses in agricultural productions, including some aspects of workers’ safety, reports the results of experimental tests aimed at measuring the amount of the mixture deposited on the worker’s body (potential dermal exposure, PDE) during pesticide applications to tomato and strawberry plants in a protected environment. Experimental tests on tomatoes were carried out taking into account two plant growth stages (flowering and senescence), two types of spray lance, two working pressures (1 and 2 MPa), and two walking directions (forwards and backwards). Those on the strawberries were carried out at the maturity of the fruit growth stage, comparing two hand-held sprayers (a standard spray gun and a short hand-held spray boom equipped with two nozzles) and working according to the common practice: forwards movement of the operator and high pressure (2 MPa). The results showed that with the tomato plants, the most important factor in reducing the deposit on the operator was the walking direction: on average, the PDE was 718 mL per 1000 L of the sprayed mixture (0.72h) while walking forwards and 133 mL (0.13h) while walking backwards. The reduction factor ranged from 3.0 at the flowering growth stage to 7.2 at the senescence growth stage. With respect to the strawberry plants, the PDE was significantly higher when the operator used the short hand-held spray boom (887 mL per 1000 L of the sprayed mixture, equivalent to 0.89h), rather than the spray gun (344 mL, 0.34h). In both cases, the most exposed body parts were the lower limbs, which accounted for 89–94% of the total PDE

Modelling Spray Pressure Effects on Droplet Size Distribution from Agricultural Nozzles

For spray applications, drop size is the most important feature as it affects all aspects of a phytosanitary treatment: biological efficacy, environmental pollution, and operator safety. In turn, drop size distribution depends on nozzle type, liquid properties, and working pressure. In this research, three nozzles were studied under ordinary working conditions and the effect of pressure on drop size distribution was assessed. The nozzles under test, all from Albuz (France), were an orange hollow cone nozzle ATR 80 (European color code), an air induction flat spray nozzle AVI 11003, and an air induction hollow cone nozzle TVI 8002. The ATR 80 and the TVI 8002 nozzles were tested at four pressure values: 0.3, 0.5, 1.0, and 1.5 MPa; the AVI 11003 nozzle was tested at 0.3 and 0.5 MPa. The drop size measurement technique was based on the liquid immersion method by using a custom-made test bench; spray quality parameters were computed by means of suitable functions written in R language. Results showed that an increase in working pressure caused an increase in drop pulverization regardless of the type of nozzle, and drop pulverization was higher for the turbulence nozzle than for the two air induction nozzles. Based on skewness and kurtosis values, the theoretical gamma distribution was the most adapt to fit the experimental data. The scale parameter showed a decreasing trend with the increase in the pressure, a clear index of higher drop pulverization

FEM Analysis of Effects of Mechanical Impact Parameters on Fruit Characteristics

Mechanical impact on fresh agriculture commodities may be a criterial issue during mechanical processes such as grading, sorting, conveying, packing or transport. The applications of electronic measuring devices in form of artificial fruits like ‘Instrumented Spheres’ (IS) are an aid to quantify influences of mechanical impact on the value of fruit, vegetable and potato. Additionally, modelling and simulation of impact on fruits helps to identify those influencing parameters. In this study, modelling and simulation runs were performed based on the Finite Element Method (FEM). For dropping tests an ‘Acceleration Measuring Unit’ (AMU) was used which can be implemented into real or artificial fruits to measure the accelerations upon impact. The test stand was equipped with a force sensor. The relevant parameters Young moduli, density, mass, fruit dimensions, and dropping test heights were varied for the tests. FEM simulation results were compared with measured acceleration values of the AMU and force values of the test stand. On dropping potato tubers with mass of 100‑120 g from 25 cm height onto steel plates, the impact force ranged from 190 to 220 N. Simulations showed that the impact force in similar conditions (mass of 102‑113 g and Young moduli of 2.5‑3.5 MPa) ranged from 198 to 242 N, which is in good agreement with the experimental results. When the tuber mass was 190‑210 g, the measured impact force varied from 310 to 325 N. Simulations for masses of 199–221 g resulted in impact forces of 306‑325 N, again in good agreement with the experimental results. However, AMU acceleration values ranged from 922‑932 m s-2, for masses of 100‑200 g, to 765‑824 m s-2 for masses of 190‑210 g. Simulations, in similar conditions, provided acceleration values of 1934‑2314 m s-2 for masses of 102‑221 g (Young moduli 2.5‑3.5 MPa) and ranging from 1497 to 1843 m s-2 for masses of 199‑221 g, which are about twice as high than measured, probably due to effects from imperfect fit when implanted the AMU into the test fruit

The Enantiopure 1,2-Diphenylethylenediamine (DPEDA) Motif in the Development of Organocatalysts for Asymmetric Reactions: Advances in the Last 20 Years

1,2-Diphenylethylenediamine (DPEDA) is a privileged chiral scaffold being used in the construction of a broad variety of organocatalysts and ligands for enantioselective organic reactions. This molecule gave a significant contribution in the synthesis of structurally different bi/multifunctional organocatalysts. DPEDA played an essential role in the development of organocatalysts capable of yielding important information on the different reaction mechanisms, like enamine, iminium, hydrogen-bonding and anion-binding catalysis. The aim of the present review is to highlight and summarize the achievements reached in the last 20 years (2004–2024) in the chemistry of DPEDA-based organocatalysts for asymmetric synthesis