73 research outputs found

    Probing nonlocal effects in metals with graphene plasmons

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    In this paper we analyze the effects of nonlocality on the optical properties of a system consisting of a thin metallic film separated from a graphene sheet by a hexagonal boron nitride (hBN) layer. We show that nonlocal effects in the metal have a strong impact on the spectrum of the surface plasmon-polaritons on graphene. If the graphene sheet is shaped into a grating, we show that the extinction curves can be used to shed light on the importance of nonlocal effects in metals. Therefore, graphene surface plasmons emerge as a tool for probing nonlocal effects in metallic nanostructures, including thin metallic films. As a byproduct of our study, we show that nonlocal effects lead to smaller losses for the graphene plasmons than what is predicted by a local calculation. We show that these effects can be very well mimicked using a local theory with an effective spacer thickness larger than its actual value.The authors thank Sébastien Nanot and Itai Epstein for valuable discussions and comments. E.J.C.D., Yu.V.B. and N.M.R.P. acknowledge support from the European Commission through the project GrapheneDriven Revolutions in ICT and Beyond (Ref. No. 785219), and from the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Financing UID/FIS/04650/2013. E.J.C.D. acknowledges FCT for the grant CFUM-BI-14/2016. D.A.I. acknowledges the FPI grant BES-2014-068504. F.H.L.K. acknowledges financial support from the Government of Catalonia trough the SGR grant (2014-SGR-1535), and from the Spanish Ministry of Economy and Competitiveness, through the Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0522), support by Fundacio Cellex Barcelona, CERCA Programme / Generalitat de Catalunya and the Mineco grants Ramn y Cajal (RYC-2012-12281) and Plan Nacional (FIS201347161-P and FIS2014-59639-JIN). Furthermore, the research leading to these results has received funding from the European Union Seventh Framework Programme under grant agreement no.696656 Graphene Flagship, the ERC starting grant (307806, CarbonLight), and project GRASP (FP7-ICT-2013-613024-GRASP). N. A. M. is a VILLUM Investigator supported by VILLUM FONDEN (grant No. 16498). Center for Nano Optics is financially supported by the University of Southern Denmark (SDU 2020 funding). Center for Nanostructured Graphene is supported by the Danish National Research Foundation (DNRF103).info:eu-repo/semantics/publishedVersio

    The Effect of Different Severities of Diet Dilution and Using a Supplemental Enzyme on Performance of Broiler Chickens

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    In this study the effect of diet dilution in 16-20 d of age and using a multi-enzyme (Endofeed-W) on performance, carcass characteristics and some blood parameters of broiler chickens (Cobb 500, commercial strain) was studied. This experiment was conducted as a factorial arrangement 2×3 in a completely randomized design with 3 replicates and 8 chicks in each replicate. Experimental diets contained 0, 20 and 40 percent rice hulls and 2 levels of enzyme (0, 500 mg/Kg). These diets contained 3000, 2400, 1800 Kcal/Kg metabolizable energy, and 21, 16.8 and 12.6 % crude protein, respectively. In other days of experiment, the chicks were fed in according to Cobb 500 rearing guideline. During feed restriction and whole period of rearing (1-44d), diet diluting up to 20% decreased feed conversion ratio (

    The Effect of Different Levels of Crude Protein and Threonine on Performance and Immune system of Broiler Chickens during Starter and Grower Periods

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    This experiment was conducted to evaluate the effect of different levels of crude protein and threonine on performance, carcass characteristics and immune system of broiler chickens during starter (7-24) and grower (25-42) periods. A total of 288 male broiler chicks of Ross 308 strain were used in a completely randomized design with factorial arrangement (2×4) with three replicates in each treatment. Experimental diets were included two levels of protein (Ross 308 guideline recommendation and 5% lower than the recommendation) and four levels of threonine (90, 100, 110, 120 of NRC recommendation). At starter period, threonine levels had a significant effect on feed conversion ratio (

    The Effect of Dietary Supplementation of Prebiotic and Probiotic on Performance, Humoral Immunity Responses and Egg Hatchability in Broiler Breeders

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    In this experiment, the influence of prebiotic and probiotic supplementation in the broiler breeder diets on body weight, mortality, feed intake, egg production, hatchability and humoral immunity response was investigated. A total number of 13140 female and 1260 male breeders (Cobb 500) with 26 wks of age were allocated to three treatments with six replicates (800 birds each replicate). Breeders were fed control basal diet, basal diet supplemented with prebiotic (mannan oligosaccharide) or probiotic (Protexin®) for 17 weeks. Body weight, feed intake and egg production were measured weekly during 26-40 wks of age. The hatchability of eggs was recorded on weeks 38, 39, and 40. Antibody production was recorded after 8 wks of prebiotic and probiotic supplementation. Prebiotic supplementation did not affect feed intake, the percentages of egg production and settable eggs percents. Prebiotic increased egg hatchability and reduced the percentages of infertile eggs, as well as dead embryo-in-shells. Antibody titers against influenza and reovirus were higher in prebiotic fed group, but there were no significant differences among the other blood antibody titers. Probiotic had no significant effect on the considered parameters. In conclusion, findings of present study showed that prebiotic improved egg hatchability and humoral immunity of broiler breeders
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