Electrically conductive epoxy nanocomposites containing carbonaceous fillers and in-situ generated silver nanoparticles

An epoxy resin was nanomodified with in-situ generated silver nanoparticles (Ag) and with various amounts of carbon black (CB) and carbon nanofibers (NF), in order to increase the electrical conductivity of the matrix. Differential scanning calorimetry tests revealed how the addition of both CB and NF led to a slight decrease of the glass transition temperature of the material, while electron microscopy evidenced how the dimension of CB aggregates increased with the filler content. Both flexural modulus and stress at yield were decreased by CB addition, and the introduction of Ag nanoparticles promoted an interesting improvement of the flexural resistance. CB resulted to be more effective than NF in decreasing the electrical resistance of the materials down to 103 !·cm. Therefore, a rapid heating of the CB-filled samples upon voltage application was observed, while Ag nanoparticles allowed a stabilization of the temperature for elevated voltage application times

Synergic strategies to improve the PBF-LB/M processability of a cracking-sensitive alloy

The Powder Bed Fusion-Laser Beam\Metals (PBF-LB\M) is a promising additive manufacturing process that can be used to directly produce functional components with a complex shape for a wide variety of applications. However, the layer-by-layer scanning and high cooling rates result in a high thermal gra- dient and thus, in thermally induced stresses. The stresses developed during the additive process could lead to undesirable cracking and delamination phenomena that can seriously affect the performance of the final component. The alloy composition can exacerbate crack and delamination formation, however, the need to expand the portfolio of high-strength materials processable for PBF-LB\M makes the resolu- tion of these undesirable phenomena a primary challenge in the additive manufacturing field. This works aims to systematically investigate some strategies to make processable non-standard compositions. As no standard compositions, the promising pre-alloyed AlSi10Cu8Mg composition was chosen for the present work. Based on the results obtained from a condition of severe delamination, the synergetic use of appro- priate process parameters and support structures can lead to crack-free and fully dense specimens also when platform heating is not allowed. The developed approach could also be applied to adapt other cracking-sensitive alloys for PBF-LB\M production

Enumeration and identity of Campylobacter spp. in Italian broilers

Abstract Transmission of Campylobacter to humans has been prominently associated with mishandling or improperly preparing contaminated poultry carcasses. The number of organisms per carcass represents an important measure of human exposure to the agent. Therefore, we wished to estimate this public exposure over 1 yr among Italian broiler carcasses. We sampled 213 broiler carcasses from rinse water samples collected from a single slaughterhouse. Groups of carcasses had mean processed weights ranging from 1.2 to 2.7 kg. These were produced from 22 commercial broiler chicken flocks collected from 12 different farms, 3 of which were seasonally tested. Carcasses were rinsed with sterile water, and the rinse suspension was then serially diluted and spread-plated directly onto Campy-Cefex agar plates. One to 5 typical Campylobacter colonies per plate were identified by polymerase chain reaction as Campylobacter thermo-tolerant species. The overall estimated mean count per carcass in our study was 5.16 ± 0.80 log10 cfu. This value increased in summer and autumn, as well as on carcasses collected from farms located > 100 km far from the slaughterhouse. A total of 678 Campylobacter colonies were identified by polymerase chain reaction. The majority of isolates were classified as Campylobacter jejuni (49.2%) or Campylobacter coli (47.5%). The overall number of C. jejuni was significantly higher on 1) carcasses weighing > 2 kg, 2) carcasses belonging to flocks with > 10,000 birds, and 3) carcasses collected from farms located > 100 km from the slaughterhouse. Moreover, among farms tested seasonally, C. jejuni was significantly greater than C. coli in winter. These data provide the first results of a continuing survey on Campylobacter loads and species identification from Italian broiler carcasses and represents an important baseline to estimate the human exposure to Campylobacter in Italy

CAUSA INCONSUETA DI COIN LESION

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Leggere le Indicazioni. Riflessioni e proposte per la scuola dell'infanzia

Il volume presenta il testo delle indicazioni nazionali per il curricolo della scuola dell'infanzia e del primo ciclo d'istruzione, pubblicato in forma ufficiale dal Ministero dell'Istruzione nel 2013, e ne propone un commento per quanto riguarda la parte relativa alla scuola dell'infanzia, mettendo a fuoco alcune tematiche cruciali: l'idea di scuola, di relazione educativa, di contesto, di continuità, di attività professional

Advantages of additive manufacturing for biomedical applications of polyhydroxyalkanoates

In recent years, biopolymers have been attracting the attention of researchers and special-ists from different fields, including biotechnology, material science, engineering, and medicine. The reason is the possibility of combining sustainability with scientific and technological progress. This is an extremely broad research topic, and a distinction has to be made among different classes and types of biopolymers. Polyhydroxyalkanoate (PHA) is a particular family of polyesters, synthetized by microorganisms under unbalanced growth conditions, making them both bio-based and biodegradable polymers with a thermoplastic behavior. Recently, PHAs were used more intensively in biomedical applications because of their tunable mechanical properties, cytocompatibility, adhesion for cells, and controllable biodegradability. Similarly, the 3D-printing technologies show increasing potential in this particular field of application, due to their advantages in tailor-made design, rapid prototyping, and manufacturing of complex structures. In this review, first, the synthesis and the production of PHAs are described, and different production techniques of medical implants are compared. Then, an overview is given on the most recent and relevant medical applications of PHA for drug delivery, vessel stenting, and tissue engineering. A special focus is reserved for the inno-vations brought by the introduction of additive manufacturing in this field, as compared to the traditional techniques. All of these advances are expected to have important scientific and commer-cial applications in the near future

clostridium perfringens occurrence and ribotypes in healthy broilers reared in different european countries

Abstract The main aim of this study was to investigate the occurrence and ribotypes of Clostridium perfringens in broiler flocks reared in 2 European countries that apply European Union Regulation 1831/2003. A total of 1,532 cecum contents were collected between June 2005 and November 2006 from birds belonging to 51 intensively reared flocks produced in the Czech Republic and 41 intensive production, organic, and free-range flocks reared in Italy. Clostridium perfringens was detected in 64.7 and 82.9% of the Czech Republic and Italian flocks, respectively, at mean loads ranging between 3.65 and 4.77 log10 cfu per gram of cecum content. More than 1 ribotype was identified among isolates belonging to the same flock in 57.1 and 76.5% of the Czech Republic and Italian flocks, respectively. Moreover, common ribotypes were identified between strains belonging to 2 up to 8 different flocks. In particular, 4 ribotypes were shared between strains isolated in the 2 European countries. The results of this study report on C. perfringens occurrence and mean populations in broilers reared on diets devoid of antibiotic growth promoters. Moreover, these findings show for the first time the presence of common ribotyping profiles among isolates collected from birds reared more than 1,000 km apart

Anatomo-surgical aspects and approaches fo the transposition of intercostal nerves to the brachial plexus in the treatment of traumatic radicular avulsions

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