1,721,332 research outputs found
Thermal neutron imaging through XRQA2 GAFCHROMIC films coupled with a cadmium radiator
No full textA simple and inexpensive method to perform passive thermal neutron imaging on large areas was developed on the basis of XRQA2 GAFCHROMIC films, commonly employed for quality assurance in radiology. To enhance their thermal neutron response, the sensitive face of film was coupled with a 1 mm thick cadmium radiator, forming a sandwich. By exchanging the order of Cd filter and sensitive film with respect to the incident neutron beam direction, two different configurations (beam-Cd-film and beam-film-Cd) were identified. These configurations were tested at thermal neutrons fluence values in the range 109-1010 cm-2, using the ex-core radial thermal neutron column of the ENEA Casaccia - TRIGA reactor. The results are presented in this work. © 2015 Elsevier B.V
Experimental characterization of semiconductor-based thermal neutron detectors
No full textIn the framework of NESCOFI@BTF and NEURAPID projects, active thermal neutron detectors were manufactured by depositing appropriate thickness of 6LiF on commercially available windowless p-i-n diodes. Detectors with different radiator thickness, ranging from 5 to 62 μm, were manufactured by evaporation-based deposition technique and exposed to known values of thermal neutron fluence in two thermal neutron facilities exhibiting different irradiation geometries. The following properties of the detector response were investigated and presented in this work: thickness dependence, impact of parasitic effects (photons and epithermal neutrons), linearity, isotropy, and radiation damage following exposure to large fluence (in the order of 1012 cm-2). © 2015 Elsevier B.V. All rights reserved
Optical and electrical characterizations of graphene nanoplatelet coatings on low density polyethylene
No full textCoatings of graphene nanoplatelets (GNPs) were deposited on a low density polyethylene (LDPE) substrate by a micromechanical method based on rubbing graphite platelets against the surface of the polymer. Transmission electron microscopy measurements reveal that the coatings were composed of nanoplatelets containing 13-30 graphene layers. Thermal gravimetric analysis shows that the investigated GNP coatings on LDPE (GNP/LDPE) samples are thermally stable up to 250 °C. Optical spectra of these samples, compared to those of pristine LDPE in the ultraviolet-visible-near-infrared range, indicate an increase in both reflectance and absorptance. On the other hand, the coating is able to markedly improve the surface conductivity of the polymeric substrate, indeed in the case of electrical contacts in the coplanar configuration (1 cm long and spaced 1 mm), the resistance of LDPE is 1015Ω, while that of GNP/LDPE is 670 Ω. Electrical measurements under white light illumination point out a decrease in the conductance and a linear behavior of the photoconductance as a function of the optical power density. GNP/LDPE materials can be used for their optical, electrical, thermal, and flexibility properties in large area plastic electronics and optoelectronics. © 2017 Author(s)
Microwave signal conditioning through non reciprocal phase shifting
No full textTwo non-reciprocal microwave signal conditioning circuits, a non-reciprocal phase shifter and a quasi-circulator, are proposed as based on the use of active microwave devices. Analytical expressions are derived to demonstrate the principles of operation and prototypes are presented both in hybrid and monolithic form. The hybrid structures operate in the L-band, whereas the monolithic ones are designed for X-band operation, and demonstrate the compactness and performance of the proposed topologie
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Industrial mineral occurrences associated with the Cenozoic volcanics of Sardinia (Italy): Geological, mineralogical, geochemical features and genetic implications
No full textApplication of integrated acoustic and mineralogical techniques for the characterization of building stones in monumental structures
No full textLarvae of Sulcascaris sulcata (Nematoda: Anisakidae), a parasite of sea turtles, infect the edible purple dye murex Bolinus brandaris in the Tyrrhenian Sea
No full textAnisakid nematodes are among the most common helminth parasites of the marine realm, particularly important for their implications with human infections and/or allergies. Members of the Anisakidae use aquatic mammals, birds and fish as definitive hosts, and crustaceans, fish and molluscs as intermediate/paratenic hosts. Sulcascaris sulcata, the only species in the monotypic genus Sulcascaris, represents the exception being a parasite of sea turtles as adult. The recent findings of larvae of S. sulcata in scallops (Pecten jacobeus and Aequipecten opercularis) and Mediterranean mussels Mytilus galloprovincialis intended for human consumption from the Mediterranean Sea caused concern regarding the sanitary control of edible molluscs and consumer safety. Herein, we investigated the larval anisakids collected from the purple dye murex, Bolinus brandaris, harvested for human consumption from the Central Mediterranean Sea (Tyrrhenian Sea). Morphological study and sequence analysis of the internal transcribed spacer regions of the ribosomal DNA and the mitochondrial cytochrome c oxidase subunit 2 gene locus revealed the occurrence of fourth stage larvae of S. sulcata in 16% of the purple dye murex examined. The present study adds the purple dye murex to the list of the known intermediate hosts of this parasite in the Mediterranean Sea and the northern coast of Campania region as site where individuals of loggerhead turtle and purple dye murex may become infected. This is the first study reporting an anisakid nematode in edible gastropods. Epidemiological features of infection in the purple dye murex and implications for gastropod safety and risk for consumers are discussed
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