Terahertz imaging for non-invasive classification of healthy and cimiciato-infected hazelnuts

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

Infrared Photoluminescence of Nd-Doped Sesquioxide and Fluoride Nanocrystals: A Comparative Study

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 4F3/2→4I15/2 transition. The lifetime of the 4F3/2 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

Spectroscopic study of doped nanoparticles for anti-counterfeiting applications

The work of my thesis is aimed at the optical characterization of crystal nanoparticles doped with rare earth ions for anti-counterfeiting technology. Five compositions of different crystal matrices doped with Nd, Er, Ho and YbEr were studied. The doped matrices were chosen on the basis of their physical and chemical properties like thermal properties and resistance to oxidation and degradation, while the dopants were chosen on the basis of their expected emission properties in the Visible and Near InfraRed (NIR) region such as, a large collection of atom-like emission bands, which cover the whole spectral range from UV to IR with long life times, i.e. from microseconds up to milliseconds. Furthermore, these emissions are extremely stable and produced by peculiar processes, such as upconversion or cross-relaxation. Thanks to these properties it is possible to think of creating a multi-level security code that could be spatially, spectrally and temporally encoded. A thorough spectroscopic analysis is therefore required to assess the potentialities of various compositions to this purpose. For each sample the absorption and emission spectra and the lifetime of the various levels were recorded both in visible and infrared regions. We also studied the stability of the spectroscopic features as a function of the sample around room temperature. The goal is to identify compounds that show intense and stable emissions to be used for a robust anti-counterfeiting technology

Vitexin-2-O-xyloside, raphasatin and (−)-epigallocatechin-3-gallate synergistically affect cell growth and apoptosis of colon cancer cells

Cytotoxic effects of the combination of the food components vitexin-2-O-xyloside (X), raphasatin (4-methylsulphanyl-3-butenyl isothiocyanates; G) and (-)-epigallocatechin-3-gallate (E) were investigated in colon (LoVo and CaCo-2) and breast (MDA-MB-231 and MCF-7) cancer cells. Breast cancer cells were more resistant than colon cells to X, G and E inhibition. On the contrary, marked synergistic effects among X, G and E on cell growth were found in both colon cancer cells. Further analysis revealed a G0/G1 arrest of the phase cell progression and apoptosis, linked to modulation of Bax, Bcl2, caspase-9 and poly(ADP-ribose) polymerase as well as Reactive Oxygen Species (ROS) generation in both colon cancer cells, whereas apoptosis and ROS were not significantly detected in normal human lymphocytes. We conclude that the X, G and E mixture might act by mitochondrial pathway activation of apoptosis, possibly elicited by ROS and the mixture may be effective in the chemoprevention of colon cancer

The Mechanistic Understanding of RAD51 Defibrillation: A Critical Step in BRCA2-Mediated DNA Repair by Homologous Recombination

The cytotoxic action of anticancer drugs can be potentiated by inhibiting DNA repair mechanisms. RAD51 is a crucial protein for genomic stability due to its critical role in the homologous recombination (HR) pathway. BRCA2 assists RAD51 fibrillation and defibrillation in the cytoplasm and nucleus and assists its nuclear transport. BRC4 is a peptide derived from the fourth BRC repeat of BRCA2, and it lacks the nuclear localization sequence. Here, we used BRC4 to (i) reverse RAD51 fibrillation; (ii) avoid the nuclear transport of RAD51; and (iii) inhibit HR and enhance the efficacy of chemotherapeutic treatments. Specifically, using static and dynamic light scattering, transmission electron microscopy, and microscale thermophoresis, we show that BRC4 eroded RAD51 fibrils from their termini through a “domino” mechanism and yielded monomeric RAD51 with a cumulative nanomolar affinity. Using cellular assays (BxPC-3, pancreatic cancer), we show that a myristoylated BRC4 (designed for a more efficient cell entry) abolished the formation of nuclear RAD51 foci. The present study provides a molecular description of RAD51 defibrillation, an essential step in BRCA2-mediated homologous recombination and DNA repair

Fatty acid acylated peptide therapeutics: discovery of omega-n oxidation of the lipid chain as a novel metabolic pathway in preclinical species

International audienceWe recently described C18 fatty acid acylated peptides as a new class of potent long-lasting single-chain RXFP1 agonists that displayed relaxin-like activities in vivo. Early pharmacokinetics and toxicological studies of these stearic acid acylated peptides revealed a relevant oxidative metabolism occurring in dog and minipig, and also seen at a lower extent in monkey and rat. Mass spectrometry combined to NMR spectroscopy studies revealed that the oxidation occurred, unexpectedly, on the stearic acid chain at ω-1, ω-2 and ω-3 positions. Structure-metabolism relationship studies on acylated analogues with different fatty acids lengths (C15-C20) showed that the extent of oxidation was higher with longer chains. The oxidized metabolites could be generated in vitro using liver microsomes and engineered bacterial CYPs. These systems were correlating poorly with in vivo metabolism observed across species; however, the results suggest that this biotransformation pathway might be catalyzed by some unknown CYP enzymes