Metamaterial-enabled asymmetric negative refraction of GHz mechanical waves

Wave refraction at an interface between different materials is a basic yet fundamental phenomenon, transversal to several scientific realms – electromagnetism, gas and fluid acoustics, solid mechanics, and possibly also matter waves. Under specific circumstances, mostly enabled by structuration below the wavelength scale, i.e., through the metamaterial approach, waves undergo negative refraction, eventually enabling superlensing and transformation optics. However, presently known negative refraction systems are symmetric, in that they cannot distinguish between positive and negative angles of incidence. Exploiting a metamaterial with an asymmetric unit cell, we demonstrate that the aforementioned symmetry can be broken, ultimately relying on the specific shape of the Bloch mode isofrequency curves. Our study specialized upon a mechanical metamaterial operating at GHz frequency, which is by itself a building block for advanced technologies such as chip-scale hybrid optomechanical and electromechanical devices. However, the phenomenon is based on general wave theory concepts, and it applies to any frequency and time scale for any kind of linear waves, provided that a suitable shaping of the isofrequency contours is implemented

Nutrição aponta caminhos para eficiência e redução de custos.

Projeto: 11.11.11.111

Magneto-optic transmittance modulation observed in a hybrid graphene-split ring resonator terahertz metasurface

By placing a material in close vicinity of a resonant optical element, its intrinsic optical response can be tuned, possibly to a wide extent. Here, we show that a graphene monolayer, spaced a few tenths of nanometers from a split ring resonator metasurface, exhibits a magneto-optical response which is strongly influenced by the presence of the metasurface itself. This hybrid system holds promises in view of thin optical modulators, polarization rotators, and nonreciprocal devices, in the technologically relevant terahertz spectral range. Moreover, it could be chosen as the playground for investigating the cavity electrodynamics of Dirac fermions in the quantum regime.The work was supported in part by the European Union Graphene Flagship under grant agreement n° 604391.This is the author accepted manuscript. The final version is available from AIP via http://dx.doi.org/10.1063/1.493170

Tele-medicine versus face-to-face consultation in Endocrine Outpatients Clinic during COVID-19 outbreak: a single-center experience during the lockdown period

The COVID-19 outbreak in Italy is the major concern of Public Health in 2020: measures of containment were progressively expanded, limiting Outpatients' visit

Induced defense responses in tomato against bacterial spot by proteins synthesized by endophytic bacteria.

Some endophytes can synthesize molecules that elicit the induction of plant resistance to infection by pathogens. The objective of this study was to demonstrate that protein fractions 42 and 75 from Bacillus amyloliquefaciens and Bacillus pumilus were capable of acting as elicitors of induced resistance in tomato plants against Xanthomonas vesicatoria, following partial resolution by gel-filtration chromatography. Tomato plants sprayed with protein fractions 42 and 75 reduced, respectively, 63.5 and 56.6% of bacterial spot, compared with control plants. Additionally, these fractions promoted the increase of peroxidase (POX) and polyphenol oxidase (PPO) enzyme activities in treated plants. In SDS-PAGE stained with silver nitrate, protein fractions 42 and 75 appeared as simple bands with estimated molecular mass of 28 and 43 kDa, respectively. We report the partial characterization of two macromolecules synthesized by endophytic bacteria that act as elicitors of systemic resistance in tomato against X. vesicatoria

Integrating fungicide and biocontrol foliar spray on maize grain yield and fumonisin content.

The adoption of biocontrol is low in maize production, although it has been reported reduction in fumonisin levels when combined with fungicides. The objective of this work was to evaluate the potential of Streptomyces araujoniae (BC1) and Bacillus sp. (BC2) combined or not with the fungicide azoxystrobin+ciproconazol (FG), on grain yield, Fusarium verticillioides incidence and fumonisin (B1 and B2) content. Maize plants were sprayed two times, at V9 and R1 with Water, BC1, BC2, Fungicide alone or in different combinations two by two. All plants were inoculated with F. verticillioides. Upon harvest, treatments were evaluated for total yield, F. verticillioides grain contamination (blotter test) and total fumonisin (B1+B2) contents. FG (V9) + BC1 (R1) resulted in increased yield in three out of four field trials, while all other treatments increased yield in only two. All treatments except FG (V9 + R1) reduced F. verticillioides incidence. None of the treatments reduced fumonisin levels, but FG (V9 + R1), BC1 (V9) + FG (R1) and BC1 (V9) + BC1 (R1) resulted in higher mycotoxin content compared to the control. FG (V9) + BC1 (R1) increased yield, reduced grain contamination and didn?t contribute to higher fumonisin levels compared to control. Therefore, it can contribute to qualitative and quantitative maize grain yield improvement

Uso de alfa-amilase em dietas de frangos de corte, superestimando ou não a energia metabolizável do milho.

bitstream/item/58073/1/CUsersPiazzonDocuments457.pdfProjeto n. 10.06.21.033-01