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76. Chemical Instability of an Interface between Silver and Bi2Se3 Topological Insulator at Room TemperatureKatja Ferfolja, Matjaž Valant, Iuliia Mikulska, Sandra Gardonio, Mattia Fanetti, 2018, original scientific article Abstract: Understanding an interaction at an interface between a topological insulator and a metal is of critical importance when designing electronic and spintronic devices or when such systems are used in catalysis. In this paper, we report on a chemical instability of the interface between Bi2Se3 and Ag studied by X-ray powder diffraction and electron microscopy. We present strong experimental evidence of a redox solid-state reaction occurring at the interface with kinetics that is significant already at room temperature. The reaction yields Ag2Se, AgBiSe2, and Bi. The unexpected room-temperature chemical instability of the interface should be considered for all future theoretical and applicative studies involving the interface between Bi2Se3 and Ag.
Keywords: topological insulators, Ag, thin metal films, interfaces, redox reaction
Published in RUNG: 17.06.2020; Views: 2949; Downloads: 0
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77. Physiological responses of garden cress (L. sativum) to different types of microplasticsSara Pignattelli, Andrea Broccoli, Monia Renzi, 2020, original scientific article Abstract: In this study, for the first time, acute and chronic toxicity caused by four different kinds of microplastics: polypropylene
(PP), polyethylene (PE), polyvinylchloride (PVC), and a commercial mixture (PE + PVC) on Lepidium sativum were evaluated. Parameters considered were: i) biometric parameters (e.g. percentage inhibition of seed germination, plant height, leaf number and fresh biomass productions); and ii) oxidative stress (e.g. levels of hydrogen peroxide, glutathione, and ascorbic acid). On plants exposed to chronic stress chlorophylls, carotenoids, aminolaevulinic acid, and proline productions were, also, evaluated. PVC resulted the most toxic than other plastic materials tested. This study represents the first paper highlighting microplastics are able to produce oxidative burst in tested plants and could represent an important starting point for future researches on biochemical effects of microplastic in terrestrial environments such as agroecosystems.
Keywords: Polypropylene
Polyethylene
Polyvinylchloride
Plastic packaging
Microplastics
Plant exposure
Published in RUNG: 24.04.2020; Views: 2870; Downloads: 0
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78. Development of encapsulation techniques for the production and conservation of synthetic seeds in ornamental plantsYelda Ozden-Tokatli, Anna De Carlo, Fusun Gumusel, Sara Pignattelli, Maurizio Lambardi, 2008, original scientific article Abstract: The synthetic seed ("synseed") technology, initially developed through the encapsulation of somatic embryos, is now available for the use with non-embryogenic in vitro-derived explants, such as buds and nodal segments. For ornamental plants, to date there are few reports dealing with the production and the conservation of synseeds. Hence, the present study was conducted to develop an efficient encapsulation protocol for apical and axillary buds from various ornamental shrubs, i.e., oleander (Nerium oleander L.), photinia (Photinia fraseri Dress.), and lilac (Syringa vulgaris L.). For encapsulation, apical and axillary buds were excised, directly immersed in a Na-alginate solution, and then released dropwise in 100 mM CaCl2 center dot 2H(2)O for bead hardening. With photinia, best results were achieved when the synseeds were prepared using 3% Na-alginate, beads hardened for 30 min and germinated on hormone-free or BA-containing gelled MS medium. Thus, up to 92% of synseeds germinated and converted to shoots in a period of 10-11 days. The synthetic seeds of lilac, containing apical buds, showed a shorter germination time when 10-30 g 1(-1) sucrose was included in their "artificial endosperm". Successful medium-term conservation was then achieved with the storage of synthetic seeds at 4 degrees C in the dark on gelled MS medium, where up to 75% (oleander) and and 9 1 % (photinia) synseeds still germinated after 2 or 3 months of cold storage, respectively. Moreover, promising results have been obtained with the cryopreservation of photinia apical buds by means of the technique of "encapsulation-dehydration".
Keywords: conservation, cryopreservation, encapsulation, ornamentals, synthetic seeds
Published in RUNG: 20.04.2020; Views: 2853; Downloads: 0
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79. Cadmium phytoextraction potential of different Alyssum speciesRita Barzanti, Ilaria Colzi, Miluscia Arnetoli, Alessia Gallo, Sara Pignattelli, Roberto Gabbrielli, Cristina Gonnelli, 2011, original scientific article Abstract: This work was planned for providing useful information about the possibility of using serpentine adapted plants for phytoextraction of cadmium, element scarcely represented in such metalliferous environment. To this aim, we investigated variation in cadmium tolerance, accumulation and translocation in three Alyssum plants with different phenotypes: Alyssum bertolonii, that is a serpentine endemic nickel hyper-accumulator, and two populations of Alyssum montanum, one adapted and one not adapted to serpentine soils.
Plants were hydroponically cultivated in presence of increasing concentrations of CdSO(4) for two weeks. For the metal concentration used in the experiments, the three different Alyssum populations showed variation in cadmium tolerance, accumulation and content. The serpentine adapted population of A. montanum showed statistically higher cadmium tolerance and accumulation than A. bertolonii and the population of A. montanum not adapted to serpentine soil thus deserving to be investigated for phytoextraction purposes. Furthermore, as for the kinetic parameters of the cadmium uptake system, A. montanum serpentine population presented a low apparent K(m) value, suggesting a high affinity for this metal of its uptake system, whereas the V(max) values were not significantly different among the plants.
Present data revealed metallicolous plants are also suitable for the phytoremediation of metals under-represented in the environment of their initial origin. Nonetheless, field trials on real contaminated soils are essential.
Keywords: Alyssum, Cadmium, Tolerance, Accumulation, Phytoextraction
Published in RUNG: 20.04.2020; Views: 2939; Downloads: 0
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80. Silver nanoparticles enter the tree stem faster through leaves than through rootsClaudia Cocozza, Annalisa Perone, Cristiana Giordano, Maria Cristina Salvatici, Sara Pignattelli, Aida Raio, Marcus Schaub, Kruno Sever, John L. Innes, Roberto Tognetti, Paolo Cherubini, 2019, original scientific article Abstract: A major environmental pollution problem is the release into the atmosphere of particulate matter, including nanoparticles (NPs), which causes serious hazards to human and ecosystem health, particularly in urban areas. However, knowledge about the uptake, translocation and accumulation of NPs in plant tissues is almost completely lacking. The uptake of silver nanoparticles (Ag-NPs) and their transport and accumulation in the leaves, stems and roots of three different tree species, downy oak (Quercus pubescens Willd.), Scots pine (Pinus sylvestris L.) and black poplar (Populus nigra L.), were assessed. In the experiment, Ag- NPs were supplied separately to the leaves (via spraying, the foliar treatment) and roots (via watering, the root treatment) of the three species. Uptake, transport and accumulation of Ag were investigated through spectroscopy. The concentration of Ag in the stem was higher in the foliar than in the root treatment, and
in poplar more than in oak and pine. Foliar treatment with Ag-NPs reduced aboveground biomass and stem length in poplars, but not in oaks or pines. Species-specific signals of oxidative stress were observed; foliar treatment of oak caused the accumulation of H2O2 in leaves, and both foliar and root treatments of poplar led to increased O2− in leaves.
Ag-NPs affected leaf and root bacteria and fungi; in the case of leaves, foliar treatment reduced bacterial populations in
oak and poplar and fungi populations in pine, and in the case of roots, root treatment reduced bacteria and increased fungi in poplar. Species-specific mechanisms of interaction, transport, allocation and storage of NPs in trees were found.
We demonstrated definitively that NPs enter into the tree stem through leaves faster than through roots in all of the
investigated tree species.
Keywords: Ag-NPs, pathway of uptake, Pinus sylvestris L., Populus nigra L., Quercus pubescens Willd.
Published in RUNG: 20.04.2020; Views: 2925; Downloads: 0
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