The development of new non-invasive approaches able to recognize defective food is currently a lively field of research. In particular, a simple and non-destructive method able to recognize defective hazelnuts, such as cimiciato-infected ones, in real-time is still missing. This study has been designed to detect the presence of such damaged hazelnuts. To this aim, a measurement setup based on terahertz (THz) radiation has been developed. Images of a sample of 150 hazelnuts have been acquired in the low THz range by a compact and portable active imaging system equipped with a 0.14 THz source and identified as Healthy Hazelnuts (HH) or Cimiciato Hazelnut (CH) after visual inspection. All images have been analyzed to find the average transmission of the THz radiation within the sample area. The differences in the distribution of the two populations have been used to set up a classification scheme aimed at the discrimination between healthy and injured samples. The performance of the classification scheme has been assessed through the use of the confusion matrix on 50 samples. The False Positive Rate (FPR) and True Negative Rate (TNR) are 0% and 100%, respectively. On the other hand, the True Positive Rate (TPR) and False Negative Rate (FNR) are 75% and 25%, respectively. These results are relevant from the perspective of the development of a simple, automatic, real-time method for the discrimination of cimiciato-infected hazelnuts in the processing industry.

Lanthanide ions possess various emission channels in the near-infrared region that are well known in bulk crystals but are far less studied in samples with nanometric size. In this work, we present the infrared spectroscopic characterization of various Nd-doped fluoride and sesquioxide nanocrystals, namely Nd:Y₂O₃, Nd:Lu₂O₃, Nd:Sc₂O₃, Nd:YF₃, and Nd:LuF₃. Emissions from the three main emission bands in the near-infrared region have been observed and the emission cross-sections have been calculated. Moreover, another decay channel at around 2 μm has been observed and ascribed to the ⁴F_3/2→⁴I_15/2 transition. The lifetime of the ⁴F_3/2 level has been measured under LED pumping. Emission cross-sections for the various compounds are calculated in the 1 μm, 900 nm, and 1.3 μm regions and are of the order of 10⁻²⁰ cm² in agreement with the literature results. Those in the 2 μm region are of the order of 10⁻²¹ cm².

We investigated the impact of ozone exposure on Hornbeam using a novel dual approach based on Terahertz (THz) imaging in a free-air ozone exposure experiment (three ozone levels: ambient; 1.5 times ambient; twice ambient). The research aims at unraveling the physiological responses induced by elevated ozone levels on water dynamics. THz imaging unveiled dynamic changes in leaf water content, providing a non-invasive approach to leaf water monitoring. Leaf gas exchange measurements assessed stomatal responses to light variation. Our findings showcase a compelling correlation between elevated ozone levels and reduction in photosynthetic rate and impairment of stomatal function, i.e. "stomatal sluggishness", indicative of nuanced regulatory mechanism. Stomatal sluggishness was particularly evident in Carpinus betulus (CB) compared to Ostrya carpinifolia (OC) and was linked to reduction in photosynthetic capacity. THz-based imaging techniques confirmed this result indicating a negative effect of O₃ on leaf-level total water content. In addition, spatial analysis of leaf water status using these techniques also highlighted that the negative effect of O₃ on water status was progressing even in less sensitive OC plants though visible foliar injury was not detected. In fact, OC showed a relative dry area of 1.6 ± 1.6 % in the control group and 3.8 ± 1.3 % under high ozone levels. THz-based imaging techniques provided a deep understanding of O₃ behavior in plants and may be recommended for precision biosensing in the early detection of O₃-induced damage. The integration of THz imaging and physiological analysis resulted in comprehensive understanding of Hornbeam acclimation response to ozone exposure.