Ktisis Collection: Άρθρα/Articles

Effect of pre-harvest and post-harvest conditions and treatments on plum fruit quality

Title: Effect of pre-harvest and post-harvest conditions and treatments on plum fruit quality

Authors: Manganaris, George A.; Vicente, Ariel R.; Crisosto, Carlos H.

Abstract: Plums belong to the Rosaceae family and include the European species (Prunus domestica L.), whichis consumed fresh or dried, and the Japanese species (Prunus salicina Lindell), mainly freshly consumed. Plums are considered climacteric, although some plum cultivars do not show the typicalincrease in ethylene production and respiration until late ripening. They respond to exogenousethylene, which is a key ripening regulator, while treatments with 1-methylcyclopropene (1-MCP),an ethylene action inhibitor, are effective in delaying fruit ripening. Plum fruit is characterized byhigh softening rate and, so far, the sequence of events leading to cell wall degradation, as well aschanges in the proteins responsible for these modiﬁcations, has not been thoroughly investigated.Post-harvest diseases (brown rot, grey mould and Rhizopous rot) are also a main concern in plumpost-harvest handling and storage. Prompt cooling and low-temperature storage (0 C) arerecommended to delay ripening and maintain plum fruit quality. However, when the fruit is heldfor long periods at low temperature, chilling injury (CI) symptoms, usually manifested as translucency, bleeding, ﬂesh browning and/or failure to ripen, might develop. Although softening can bedelayed by controlled and modiﬁed atmospheres, this technology is not widely used commercially,since the beneﬁts are not as pronounced as in other fruit species. Other post-harvest strategiestested to date with apparent usefulness at a laboratory scale include heat treatment, ozone,polyamine and calcium treatments, as well as fumigation with environmentally friendly compounds;such strategies might be useful under particular circumstances to complement other post-harvesttreatments. Pre-harvest treatments, such as application of synthetic auxins and calcium, regulationof canopy light conditions and orchard soil management, have been reported to affect plum fruitquality and its post-harvest behaviour. Overall, the present review discusses the inﬂuence of ﬁeldand post-harvest practices on plum fruit quality and market life.

Photorealistic large-scale urban city model reconstruction

Title: Photorealistic large-scale urban city model reconstruction

Authors: Poullis, Charalambos; You, C.

Abstract: The rapid and efficient creation of virtual environments has become a crucial part of virtual reality applications. In particular, civil and defense applications often require and employ detailed models of operations areas for training, simulations of different scenarios, planning for natural or man-made events, monitoring, surveillance, games, and films. A realistic representation of the large-scale environments is therefore imperative for the success of such applications since it increases the immersive experience of its users and helps reduce the difference between physical and virtual reality. However, the task of creating such large-scale virtual environments still remains a time-consuming and manual work. In this work, we propose a novel method for the rapid reconstruction of photorealistic large-scale virtual environments. First, a novel, extendible, parameterized geometric primitive is presented for the automatic building identification and reconstruction of building structures. In addition, buildings with complex roofs containing complex linear and nonlinear surfaces are reconstructed interactively using a linear polygonal and a nonlinear primitive, respectively. Second, we present a rendering pipeline for the composition of photorealistic textures, which unlike existing techniques, can recover missing or occluded texture information by integrating multiple information captured from different optical sensors (ground, aerial, and satellite).

Antimalarial endoperoxides: synthesis and implications of the mode of action

Title: Antimalarial endoperoxides: synthesis and implications of the mode of action

Authors: Koutsoupakis, Constantinos; Varotsis, Constantinos; Gialou, Irene

Abstract: Abstract6,7-Dioxabicyclo[3.2.2]non-8-ene 2 and 1-isopropyl-4-methyl-2,3- dioxabicyclo[2.2.2]oct-5-ene (ascaridol) 3 were prepared as simplified, endoperoxide versions of clinically used antimalarial drugs. Fourier transform infrared (FTIR) technique in conjunction with 18O 2- enriched compound 2 has been applied in probing the bonds of the endoperoxide moiety and the bonds of the rings owing to the presence of the O-O, the C-O, the O-O-C as well as the C=O modes in the spectrum. The endoperoxide moiety is especially useful in this regard because the homolytic cleavage of the O-O bond can be characterized and hence can be used to assess the vibrational properties of the O- and C-centered radicals and subsequently that of the C-C bond cleavage. The cleavage of the O-O bond, and the ability to correlate vibrational properties of the reaction products with structural properties of the isolated products suggest that infrared spectroscopy is an appropriate tool to study the mode of action of antimalarial endoperoxides.

A resonance raman study of the higher-lying electronic states of styrene vapor

Title: A resonance raman study of the higher-lying electronic states of styrene vapor

Authors: Varotsis, Constantinos; Ziegler, Lawrence

Abstract: Resonance Raman spectra of styrene vapor excited in the S2 /S3 and S4 absorption systems are reported. The lack of double bond torsional scattering activity is taken as evidence of high barriers to rotation in all the excited states examined. Consequences for styrene photoisomerization are discussed. Excitation to S2/S3 is delocalized in nature, while S4 excitation is benzene-like. The observed scattering intensities are largely in agreement with the jet absorption analysis and the results of Franck-Condon calculations