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Ciesa F.,University of Parma | Ciesa F.,University of Konstanz | Ciesa F.,Centro per la Sperimentazione Agraria e Forestale Laimburg | Plech A.,University of Konstanz | And 6 more authors.
Journal of Physical Chemistry C | Year: 2010

Gold nanoparticles protected with thiolate Calix[4]arenes hosts were synthesized through an exchange reaction in toluene, starting from tetraoctyl ammonium bromide stabilized gold nanoparticles having a mean core size of ∼6 nm. In low polar solvents, these new Calix[4]arene-coated nanoparticles are able to self-assemble through supramolecular interactions with dialkyl dipyridinium-based guests (2-3). The guest-induced selfassembly process between nanoparticles has been studied using UV-vis spectroscopy, dynamic light scattering, and TEM measurements. The size and the solubility of the aggregates strongly depend on the length and rigidity of the bifunctional guest used as "supramolecular linker" between the nanoparticles. In particular, the long and flexible guest 2 gives rise to superaggregates of nanoparticles that remain soluble in common low polar solvents. © 2010 American Chemical Society.

Parker M.,UK Institute of Food Research | Guerra W.,Centro per la Sperimentazione Agraria e Forestale Laimburg
Acta Horticulturae | Year: 2010

Mature apples of 'Fuji' and 'Fuji' sports sourced from around the world contain unusual clumps of multicellular branched callus hairs between the parenchyma cells of the outer cortex. The hairs are similar morphologically to the white tufts found in the seed locules of some cultivars and to the aerial cells of apple callus grown on solid culture medium. Callus hairs were found to be particularly well developed in 'Fuji Suprema' from Brazil, and least developed in 'Fuji' from China. Hairs are also found in fruit of close relatives of 'Fuji' and some unrelated cultivars. Callus hairs proliferate in intercellular air spaces and also in larger cavities or lacunae which may have poor connectivity with other air spaces. In these locations they have the potential to restrict or modify the flow of oxygen and carbon dioxide in the outer part of apples, and thus may be one of the factors contributing to internal browning, a post-harvest disorder to which large or late-picked 'Fuji' in modified atmosphere storage are known to be vulnerable. The callus hairs are found within 17 mm of the skin and frequently contain starch even when starch has been metabolised from the surrounding parenchyma during ripening. The vacuoles of callus hairs are rich in autofluorescent compounds and may accumulate red pigment, particularly when growing close to the skin of deep red 'Fuji Suprema'. Initial observations with immunogold labelling have detected low levels of the allergen Mal d 3 associated with the plasmalemma of callus hairs. In corking disorders, callus hairs can invade necrotic cells and proliferate inside them.

Polverigiani S.,Marche Polytechnic University | Massetani F.,Marche Polytechnic University | Neri D.,Marche Polytechnic University | Perilli A.,Centro per la Sperimentazione Agraria e Forestale Laimburg | And 2 more authors.
Acta Horticulturae | Year: 2013

Soil management techniques play an important role in limiting root competition and improving soil structure, biodiversity and nutrient richness, aiming for optimal root growth and activity. In a high-density apple orchard (Malus ×domestica), four different soil management techniques were applied both in the tree row and the drive alley: turfgrass (Festuca sp.); multi-species ground cover (Festuca sp., Polygonum fagopyrum, Medicago sativa); shallow tillage; and shallow tillage plus compost amendment. Averaged across treatments, 60% of observed roots were localized between 0.1 to 0.3 m soil depths. Tillage effectively contained herbaceous root growth and, together with the compost amendment, induced a shift of root allocation to deeper soil layers and increased average root diameter. Multi-species ground cover inhibited apple root growth during the first year of the experiment. The strongest inhibition was recorded during the two peaks of apple root growth in late spring and early autumn. The same periods were also characterized by the highest rate of ground cover root production. The understorey ground cover did not compromise above ground plant performance measured either as shoot growth or as yield and fruit quality.

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