Identification and effects of mixed infection of Potyvirus isolates with Cucumber mosaic virus in cucurbits.

Mixed infections in cucurbits are frequently observed in natural conditions between viruses from the Potyvirus genus and Cucumber mosaic virus (CMV), which significantly decreases productivity. The objectives of the present study was to compare the host range of PRSV-W, WMV, and ZYMV isolates and evaluate the effects of mixed infections with CMV in zucchini plants (Cucurbita pepo L.). Host range studies comprising 23 plant species confirmed some similarities and biological differences among the isolates of PRSV-W, ZYMV, and WMV. RT-PCR confirmed the amplification of DNA fragments of the PRSV-W, WMV, and ZYMV coat protein gene (cp) and cytoplasm inclusion gene (ci). The virus interaction studies in zucchini Caserta plants indicated synergistic interactions, particularly among species from the Potyvirus genus, and some CMV interference with some virus combinations.

Potyvirus causando mosaico em plantas daninhas nas culturas do milho e do sorgo.

2016

Synthesis, characterization, and application of PHB-based gels for cultural heritage conservation

The aim of my master thesis is developing novel, greener approaches for the cleaning of artworks: such treatment consists in the removal of old varnish layers which tend to discolor or darken with time, thus allowing replacement with a new protecting coat. While protocols presently applied can be effective in the cleaning of the artworks, none of them take into account conservators’ health safety and environmental issues. Thus, using biomass-derived components, which are non-toxic and reusable and/or compostable might bring into the heritage conservation an additional awareness about safety and environmental claiming. The laboratory work for the thesis is a collaborative work between different groups. The biggest part of the work was at the Polymer group where gels were synthesized using Polyhydroxybutyrate (PHB) from sustainable resources and green solvents. The use of the gels might help to reduce the volatilization of solvents and contributes to the localization of the cleaning action. After the preparation of the gels, different characterization methods were used in order to estimate their properties and shelf-life. Finally, the work was completed on the application of the gels on sculpture, coated with undesired layers to be removed. Here, pre-mapping of the areas of interest was realized with different optical techniques, followed by the application of the gels for the cleaning and analyzing the effectiveness of cleaning.

Development of a colorimetric indicator label for food oxidation based on hexanal detection

In this work, a colorimetric indicator for food oxidation based on the detection of hexanal in gas-phase, has been developed. In fact, in recent years, the food packaging industry has evolved towards new generation of packaging, like active and intelligent. According to literature (Pangloli P. et al. 2002), hexanal is the main product of a fatty acid oxidation: the linoleic acid. So, it was chosen to analyse two kinds of potato chips, fried in two different oils with high concentration of linoleic acid: olive oil and sunflower oil. Five different formulas were prepared and their colour change when exposed to hexanal in gas phase was evaluated. The formulas evaluations were first conducted on filter paper labels. The next step was to select the thickener to add to the formula, in order to coat a polypropylene film, more appropriate than the filter paper for a production at industrial scale. Three kinds of thickeners were tested: a cellulose derivative, an ethylene vinyl-alcohol and a polyvinyl alcohol. To obtain the final labels with the autoadhesive layer, the polypropylene film with the selected formula and thickener was coat with a water based adhesive. For both filter paper and polypropylene labels, with and without autoadhesive layer, the detection limit and the detection time were measured. For the selected formula on filter paper labels, the stability was evaluated, when conserved on the dark or on the light, in order to determine the storage time. Both potato chips samples, stocked at the same conditions, were analysed using an optimised Headspace-Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) method, in order to determine the concentration of volatilized hexanal. With the aim to establish if the hexanal can be considered as an indicator of the end of potato chips shelf life, sensory evaluation was conducted each day of HS-SPME-GC-MS analysis.

Laser cladding and its potential to reduce particulate matter emissions from the automotive and locomotive sector

Laser Cladding (LC) is an emerging technology which is used both for coating applications as well as near-net shape fabrication. Despite its significant advantages, such as low dilution and metallurgical bond with the substrate, it still faces issues such as process control and repeatability, which restricts the extension to its applications. The following thesis evaluates the LC technology and tests its potential to be applied to reduce particulate matter emissions from the automotive and locomotive sector. The evaluation of LC technology was carried out for the deposition of multi-layer and multi-track coatings. 316L stainless steel coatings were deposited to study the minimisation of geometric distortions in thin-walled samples. Laser power, as well as scan strategy, were the main variables to achieve this goal. The use of constant power, reduction at successive layers, a control loop control system, and two different scan strategies were studied. The closed-loop control system was found to be practical only when coupled with the correct scan strategy for the deposition of thin walls. Three overlapped layers of aluminium bronze were deposited onto a structural steel pipe for multitrack coatings. The effect of laser power, scan speed and hatch distance on the final geometry of coating were studied independently, and a combined parameter was established to effectively control each geometrical characteristic (clad width, clad height and percentage of dilution). LC was then applied to coat commercial GCI brake discs with tool steel. The optical micrography showed that even with preheating, the cracks that originated from the substrate towards the coating were still present. The commercial brake discs emitted airborne particles whose concentration and size depended on the test conditions used for simulation in the laboratory. The contact of LC cladded wheel with rail emitted significantly less ultra-fine particles while maintaining the acceptable values of coefficient of friction.

Study and implementation of control strategies for polymerization processes assisted by atmospheric pressure plasma jets

In recent years, polymerization processes assisted by atmospheric pressure plasma jets (APPJs) have received increasing attention in numerous industrially relevant sectors since they allow to coat complex 3D substrates without requiring expensive vacuum systems. Therefore, advancing the comprehension of these processes has become a high priority topic of research. This PhD dissertation is focused on the study and the implementation of control strategies for a polymerization process assisted by an atmospheric pressure single electrode plasma jet. In the first section, a study of the validity of the Yasuda parameter (W/FM) as controlling parameter in the polymerization process assisted by the plasma jet and an aerosolized fluorinated silane precursor is proposed. The surface characterization of coatings deposited under different W/FM values reveals the presence of two very well-known deposition domains, thus suggesting the validity of W/FM as controlling parameter. In addition, the key role of the Yasuda parameter in the process is further demonstrated since coatings deposited under the same W/FM exhibit similar properties, regardless of how W/FM is obtained. In the second section, the development of a methodology for measuring the energy of reactions in the polymerization process assisted by the plasma jet and vaporized hexamethyldisiloxane is presented. The values of energy per precursor molecule are calculated through the identification and resolution of a proper equivalent electrical circuit. To validate the methodology, these energy values are correlated to the bond energies in the precursor molecule and to the properties of deposited thin films. It is shown that the precursor fragmentation in the discharge and the coating characteristics can be successfully explained according to the obtained values of energy per molecule. Through a detailed discussion of the limits and the potentialities of both the control strategies, this dissertation provides useful insights into the control of polymerization processes assisted by APPJs.

Applied genomics in livestock: genome-wide association studies and population genomics analysis in pig and rabbit breeds

The domestication and selection processes in pigs and rabbits have resulted in the constitution of multiple breeds with broad phenotypic diversity. Population genomics analysis and Genome-wide association study analysis can be utilized to gain insights into the ancestral origins, genetic diversity, and the presence of lethal mutations across these diverse breeds. In this thesis, we analysed the dataset obtained from three Italian Pig breeds to detect deleterious alleles. We screened the dataset for genetic markers showing homozygous deficiency using two approaches single marker and haplotype-based approach. Moreover, Genome-wide association study analyses were performed to detect genetic markers associated with pigs' reproductive traits. In rabbits, we investigated the application of SNP bead chip for detection signatures of selection in rabbits using different methods. This analysis was implemented for the first time in different fancy and meet rabbit breeds. Multiple approaches were utilized for the detection of the selection of signatures including Fst analysis, ROH analysis, PCAdapt analysis, and haplotype-based analysis. The analysis in pigs was able to identify five putative deleterious SNPs and nine putative deleterious haplotypes in the analysed Italian Pig breeds. The genomic regions of the detected putative deleterious genomic markers harboring loss of function variants such as the Frameshift variant, start lost, and splice donor variant. Those variants are close to important candidate genes such as IGF2BP1, ADGRL4, and HGF. In rabbits, multiple genomic regions were detected to be under selection of signature. These genomic regions harbor candidate genes associated with coat color phenotype (MC1R, TYR, and ASIP), hair structure (LIPH), and body size (HMGA2 and COL2A1). The described results in rabbits and pigs could be used to improve breeding programs by excluding the deleterious genetic markers carriers and incorporating candidate genes for coat color, body size, and meat production in rabbit breeding programs to enhance desired traits