868 research outputs found

    Formation of high entropy metal diborides using arc-melting and combinatorial approach to study quinary and quaternary solid solutions

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    High entropy metal diborides (HEBs) represent a radically new approach to extend the chemical composition window of ultra-high temperature ceramics (UHTCs). In this work, arc-melting was used to produce dense HEBs starting from UHTC powders. In order to understand the influence of each individual diboride within the quinary system (HfB2, ZrB2, TiB2, TaB2 and CrB2), we investigated five quaternary equimolar solid solutions e.g. Hf-Zr-Ti-Ta, Hf-Zr-Ti-Cr, Hf-Zr-Ta-Cr, Hf-Ti-Ta-Cr, Zr-Ti-Ta-Cr and the overall quinary equimolar combination. Arc-melting allowed a rapid screening of favorable and unfavorable combinations. The produced HEBs were free from undesired oxides and characterized by linear variation of lattice parameters typical of diborides and binary solid solutions. Because of evaporation during arc melting, CrB2 was hardly found in the solid solution, suggesting that vapor pressure should be taken into account when designing HEB compositions especially for operating temperatures exceeding 2000 °C. Finally, Vickers microhardness ranged between the typical values of starting diborides

    Growth of Wild Gilthead Seabream (Sparus aurata L.) Juveniles for Organic Aquaculture

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    The majority of organic marine fish farms currently begin the production cycle with non-organic juveniles from conventional hatcheries, permitted by the European Regulation on organic fish origin (EC 710/2009) until the end of 2016. Wild juvenile gilthead seabream (Sparus aurata) from coastal lagoons and hatcheries were experimentally reared under organic conditions, in order (1) to investigate differences in fillet lipid content and fatty acids composition, and (2) to propose a possible future source of juveniles destined for organic aquaculture. Wild juveniles were readily distinguishable by their fatty acid signature, showing significantly higher ratio levels of n-3 polyunsaturated fatty acids and n-3/n-6. Fillet lipid composition of organically fed wild S. aurata juveniles was preferable to that from domesticated juveniles. These results seem promising for organic aquaculture, where fish feed is more environmentally sustainable but is of lower nutritional qualit

    Toughening effect of non-periodic fiber distribution on crack propagation energy of UHTC composites

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    Different configurations of continuous carbon fiber-reinforced ultrahigh temperature ceramics (UHTCs), by combining coatings and matrix, were produced via electrophoretic deposition (EPD) and slurry infiltration. The toughening of non-periodic fiber distribution induced by the EPD process was investigated through work of fracture analysis. The results show that a non-periodic fiber distribution results in toughness increase from 8 MPa√m to 11 MPa√m with respect to a periodic fiber distribution. This toughness improvement does not strongly affect the flexural strength, which is mainly related to the fiber volumetric amount. It is shown that the assembling of carbon fibers into bundles (i.e. by dispersing the fibers with a non-periodic distribution) increases the crack propagation energy dissipated on the crack-wake from 0.5 kJ/m2 to 1 kJ/m2, which can be mainly ascribed to the fiber/bundle pull-out. On the other hand, the energy dissipated on the crack-tip (as fiber/matrix debonding) is fiber distribution-independent and increases from 0.3 kJ/m2 to 0.4 kJ/m2 with increasing the fiber amount from 33 vol% to 40 vol%. Finally, WoF analysis is proposed as test to evaluate pull-out toughening instead of push-in and push-out tests

    Evidence for a Sympatric Origin of Ribolla gialla, Gouais Blanc and Schiava cultivars (V. vinifera L.)

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    Ribolla gialla is an autochthonous grape variety cultivated in Friuli Venezia Giulia (Italy) and in Slovenia, and probably originated in Eastern Central Europe. Just like Ribolla gialla, the Gouais blanc and Schiava cultivars also appear to have originated in the same geographical area. To verify this hypothesis, a pool of varieties probably sharing the same historical and geographical origin were taken into account. The fingerprinting, by 35 SSR loci, of Gouais blanc, Ribolla gialla, Schiava grossa and Schiava lombarda (synonyms of Schiava bresciana), is presented and the correlation among historical, geographical and genetic information of these cultivars was investigated. Gouais blanc and Traminer, already suggested as key varieties in the development of European grape diversity and as parents for some French varieties, interestingly enough seems to be linked to Ribolla gialla. The putative parentage was verified using 58 microsatellite markers. The genetic results suggest a common geographical origin for Gouais blanc, Ribolla gialla and the Schiava group: these cultivars appear to be related through sympatric origin. The hypothesis of Ribolla gialla as a progeny of Gouais blanc and Traminer was ruled out. The data proved a second-degree relationship between Gouais blanc and Ribolla gialla and a third or more distant degree of relationships between Ribolla gialla and Traminer

    Evidence for a Sympatric Origin of Ribolla gialla, Gouais Blanc and Schiava cultivars (V. vinifera L.)

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    Ribolla gialla is an autochthonous grape variety cultivated in Friuli Venezia Giulia (Italy) and in Slovenia,and probably originated in Eastern Central Europe. Just like Ribolla gialla, the Gouais blanc and Schiavacultivars also appear to have originated in the same geographical area. To verify this hypothesis, a poolof varieties probably sharing the same historical and geographical origin were taken into account. Thefingerprinting, by 35 SSR loci, of Gouais blanc, Ribolla gialla, Schiava grossa and Schiava lombarda(synonyms of Schiava bresciana), is presented and the correlation among historical, geographical andgenetic information of these cultivars was investigated. Gouais blanc and Traminer, already suggested askey varieties in the development of European grape diversity and as parents for some French varieties,interestingly enough seems to be linked to Ribolla gialla. The putative parentage was verified using 58microsatellite markers. The genetic results suggest a common geographical origin for Gouais blanc,Ribolla gialla and the Schiava group: these cultivars appear to be related through sympatric origin. Thehypothesis of Ribolla gialla as a progeny of Gouais blanc and Traminer was ruled out. The data proved asecond-degree relationship between Gouais blanc and Ribolla gialla and a third or more distant degree ofrelationships between Ribolla gialla and Traminer

    Detection of grapevine synonyms in Lombardy and Piedmont regions (northern Italy)

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    The Italian viticulture is characterized by a high number of autochthonous varieties (about 1700), some of them renowned throughout the Country, some other only of local importance. Nevertheless, the real estimation of this biodiversity is made difficult due to the great amount of synonyms, homonyms and misnomers. The aim of this work was to undertake a comparison for varietal identity of minor, lesser cultivars in two field collections of neighboring regions (Lombardy and Piedmont) located in northern Italy, verifying synonyms in different areas. Forty-seven accessions were described by morphological (OIV descriptors) and genetic (microsatellites) characteristics. Thirty-eight varieties were identified belonging to three categories: varieties of great importance in Italy and locally misnamed, varieties important in the region of Piedmont and misnamed in Lombardy, and currently minor grapes but of historical significance in both Piedmont and Lombardy regions

    Detection of grapevine synonyms in Lombardy and Piedmont regions (northern Italy)

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    The Italian viticulture is characterized by a high number of autochthonous varieties (about 1700), some of them renowned throughout the Country, some other only of local importance. Nevertheless, the real estimation of this biodiversity is made difficult due to the great amount of synonyms, homonyms and misnomers. The aim of this work was to undertake a comparison for varietal identity of minor, lesser cultivars in two field collections of neighboring regions (Lombardy and Piedmont) located in northern Italy, verifying synonyms in different areas. Forty-seven accessions were described by morphological (OIV descriptors) and genetic (microsatellites) characteristics. Thirty-eight varieties were identified belonging to three categories: varieties of great importance in Italy and locally misnamed, varieties important in the region of Piedmont and misnamed in Lombardy, and currently minor grapes but of historical significance in both Piedmont and Lombardy regions

    Molecular approach to assess the origin of cv. Marzemino

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    DNA marker analysis was used to determine the varietal identity of Marzemino accessions in public collections and private Italian vineyards; relationships among this varietal group and Vertzami, a traditional Greek cultivar, were also investigated through SSR and AFLP approaches. Molecular results strongly support the relationship among Vertzami cultivars growing in Greece, Marzemino and several Italian accessions selected on the basis of etymological similarity. SSR data exclude a direct descent of Marzemino, or other related Italian varieties, from Vertzami; on the other hand the level of similarity among Vertzami, Marzemino and some related varieties indicates a possible common ancestor. None of the accessions is considered as common ancestor but on the basis of genomic variability in the Marzemino group and of the relationships with the other Italian cultivars a probable Italian ancestor is supposed.

    Phylogenetic analysis of grapevine cv. Ansonica growing on the island of Giglio, Italy, by AFLP and SSR markers

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    The geographic origin of the grapevine cultivar Ansonica (Vitis vinifera L.) grown on the island of Giglio, Tuscany, Italy, was investigated with molecular tools, i.e. AFLP and SSR (microsatellite) analysis. The scored polymorphic DNA bands were statistically analysed and the results were expressed in dendrograms showing the degree of genomic similarity among the tested cultivars: three Ansonica vines sampled in some of the oldest vineyards of the island, one Ansonica specimen grown in Tuscany, one Inzolia specimen grown in Sicily, 23 cultivars grown in different Mediterranean regions and 40 Greek cultivars. The results obtained from AFLP or SSR approaches led to equivalent conclusions: the three grapevines sampled in Giglio were indistinguishable and showed genetic similarity with cv. Ansonica grown in the Tuscan mainland and with cv. Inzolia from Sicily, Airen from Spain, Clairette from France and Roditis from Greece. The SSR analysis showed that Sideritis and Roditis have the highest genomic similarity with Ansonica among the 40 tested Greek cultivars. The molecular analysis gives conclusive evidence for the Greek origin of Ansonica grown on the island, as previously proposed on the basis of morphological and historical studies

    Assessment of energy return on energy investment (EROEI) of oil bearing crops for renewable fuel production

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    As reported in literature the production of biodiesel should lead to a lower energy consumption than those obtainable with its use. So, to justify its consumption, a sustainable and “low input” production should be carried out. In order to assess the sustainability of Linum usitatissimum, Camelina sativa and Brassica carinata cultivation for biodiesel production in terms of energy used compared to that obtained, the index EROEI (Energy Return On Energy Invested) has been used. At this aim, an experimental field was realised in the south-eastern Sicilian land. During the autumn-winter crop cycle, no irrigation was carried out and some suitable agricultural practices have been carried out taking into account the peculiarity of each type of used seeds. The total energy consumed for the cultivation of oil bearing crops from sowing to the production of biodiesel represents the Input of the process. In particular, this concerned the energy embodied in machinery and tools utilized, in seed, chemical fertilizer and herbicide but also the energy embodied in diesel fuels and lubricant oils. In addition, the energy consumption relating to machines and reagents required for the processes of extraction and transesterification of the vegetable oil into biodiesel have been calculated for each crops. The energy obtainable from biodiesel production, taking into account the energy used for seed pressing and for vegetable oil transesterification into biodiesel, represents the Output of the process. The ratio Output/Input gets the EROEI index which in the case of Camelina sativa and Linum usatissimum is greater than one. These results show that the cultivation of these crops for biofuels production is convenient in terms of energy return on energy investment. The EROEI index for Brassica carinata is lower than one. This could means that some factors, concerning mechanisation and climati
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