Critical issues of double-metal layer coating on FBG for applications at high temperatures

Use of fiber Bragg gratings (FBGs) to monitor high temperature (HT) applications is of great interest to the research community. Standard commercial FBGs can operate up to 600 ∘ C. For applications beyond that value, specific processing of the FBGs must be adopted to allow the grating not to deteriorate. The most common technique used to process FBGs for HT applications is the regeneration procedure (RP), which typically extends their use up to 1000 ∘ C. RP involves a long-term annealing of the FBGs, to be done at a temperature ranging from 550 to 950 ∘ C. As at that temperature, the original coating of the FBGs would burn out, they shall stay uncoated, and their brittleness is a serious concern to deal with. Depositing a metal coating on the FBGs prior to process them for RP offers an effective solution to provide them with the necessary mechanical strengthening. In this paper, a procedure to provide the FBG with a bimetallic coating made by copper and nickel electrodeposition (ED) is proposed, discussing issues related to the coating morphology, adherence to the fiber, and effects on the grating spectral response. To define the processing parameters of the proposed procedure, production tests were performed on dummy samples which were used for destructive SEM-EDS analysis. As a critical step, the proposed procedure was shown to necessitate a heat treatment after the nickel ED, to remove the absorbed hydrogen. The spectral response of the FBG samples was monitored along the various steps of the proposed procedure and, as a final proof test for adherence stability of the bimetallic coating, along a heating/cooling cycle from room temperature to 1010 ∘ C. The results suggest that, given the emergence of Kirkendall voids at the copper-nickel interface, occurring at the highest temperatures (700-1010 ∘ C), the bimetallic layer could be employed as FBG coating up to 700 ∘ C

Quasilocalized gravity without asymptotic flatness

We present a toy model of a generic five-dimensional warped geometry in which the 4D graviton is not fully localized on the brane. Studying the tensor sector of metric perturbation around this background, we find that its contribution to the effective gravitational potential is of 4D type (1/r) at the intermediate scales and that at the large scales it becomes 1/r^{1+alpha}, 0<alpha=< 1 being a function of the parameters of the model (alpha=1 corresponds to the asymptotically flat geometry). Large-distance behavior of the potential is therefore not necessarily five-dimensional. Our analysis applies also to the case of quasilocalized massless particles other than graviton.Comment: 9 pages, 1 figure; to be published in Phys. Rev.

Facet-Enhanced Dielectric Sensitivity in Plasmonic Metal Oxide Nanocubes

The resonant frequency of plasmonic nanoparticles depends on the refractive index of the local environment, a property which is directly useful for sensing applications and is indicative of potential utility for other applications based on near-field enhancement of light intensity. While the morphology dependence of dielectric sensitivity has been well studied in noble metal nanoparticles, less investigated is the sensitivity of degenerately doped metal oxide nanocrystals, whose plasmon resonances lie in the near- to mid- infrared. Here, we report the dielectric sensitivity of fluorine and tin co-doped indium oxide nanocubes, its dependence on their sharp faceting that gives rise to multiple plasmonic modes, and on their tin-dopant concentration. We find that the plasmon mode associated with the nanocube corners is the most sensitive and that raising dopant concentration increases dielectric sensitivity. Comparing to finite element simulations that assume a spatially uniform free electron distribution in the nanocubes, we show that the plasmon modes associated with the edges and the faces of the nanocubes are less sensitive than expected, and that their reduced dielectric sensitivity can be rationalized by the presence of band bending and a resulting surface depletion layer. Interestingly, simulations suggest that Fermi level pinning occurs predominantly on the cube faces, reshaping the free electron volume so that the depletion layer effectively insulates the faces and edges from the surrounding environment, while the corner mode remains sensitive.This work was primarily supported by the National Science Foundation (CHE-1905263), with additional support from the Welch Foundation (F-1848), an NSF graduate research program fellowship to S. S.-Z. (DGE-2137420), and with partial support through the Center for Dynamics and Control of Materials: an NSF Materials Research Science and Engineering Center (NSF MRSEC) under Cooperative Agreement DMR-1720595.Center for Dynamics and Control of Material

Characterizing planetary systems with SPIRou: M-dwarf planet-search survey and the multiplanet systems GJ 876 and GJ 1148

SPIRou is a near-infrared spectropolarimeter and a high-precision velocimeter. The SPIRou Legacy Survey collected data from February 2019 to June 2022, half of the time devoted to a blind search for exoplanets around nearby cool stars. The aim of this paper is to present this program and an overview of its properties, and to revisit the radial velocity (RV) data of two multiplanet systems, including new visits with SPIRou. From SPIRou data, we can extract precise RVs using efficient telluric correction and line-by-line measurement techniques, and we can reconstruct stellar magnetic fields from the collection of polarized spectra using the Zeeman-Doppler imaging method. The stellar sample of our blind search in the solar neighborhood, the observing strategy, the RV noise estimates, chromatic behavior, and current limitations of SPIRou RV measurements on bright M dwarfs are described. In addition, SPIRou data over a 2.5-year time span allow us to revisit the known multiplanet systems GJ~876 and GJ~1148. For GJ~876, the new dynamical analysis including the four planets is consistent with previous models and confirms that this system is deep in the Laplace resonance and likely chaotic. The large-scale magnetic map of GJ~876 over two consecutive observing seasons is obtained and shows a dominant dipolar field with a polar strength of 30~G, which defines the magnetic environment in which the inner planet with a period of 1.94~d is embedded. For GJ~1148, we refine the known two-planet model.Comment: accepted in A&

The complete genome of Burkholderia phenoliruptrix strain BR3459a, a symbiont of Mimosa flocculosa: highlighting the coexistence of symbiotic and pathogenic genes.

Burkholderia species play an important ecological role related to xenobiosis, the promotion of plant growth, the biocontrol of agricultural diseases, and symbiotic and non-symbiotic biological nitrogen fixation. Here, we highlight our study as providing the first complete genome of a symbiotic strain of B. phenoliruptrix, BR3459a (=CLA1), which was originally isolated in Brazil from nodules of Mimosa flocculosa and is effective in fixing nitrogen in association with this leguminous species. Genomic comparisons with other pathogenic and non-pathogenic Burkholderia strains grouped B. phenoliruptrix BR3459a with plant-associated beneficial and environmental species, although it shares a high percentage of its gene repertoire with species of the B. cepacia complex (Bcc) and "pseudomallei" group. The genomic analyses showed that the bce genes involved in exopolysaccharide production are clustered together in the same genomic region, constituting part of the Group III cluster of non-pathogenic bacteria. Regarding environmental stresses, we highlight genes that might be relevant in responses to osmotic, heat, cold and general stresses. Furthermore, a number of particularly interesting genes involved in the machinery of the T1SS, T2SS, T3SS, T4ASS and T6SS secretion systems were identified. The xenobiotic properties of strain BR3459a were also investigated, and some enzymes involved in the degradation of styrene, nitrotoluene, dioxin, chlorocyclohexane, chlorobenzene and caprolactam were identified. The genomic analyses also revealed a large number of antibiotic-related genes, the most important of which were correlated with streptomycin and novobiocin. The symbiotic plasmid showed high sequence identity with the symbiotic plasmid of B. phymatum. Additionally, comparative analysis of 545 housekeeping genes among pathogenic and non-pathogenic Burkholderia species strongly supports the definition of a new genus for the second branch, which would include BR3459a. The analyses of B. phenoliruptrix BR3459a showed key property of fixing nitrogen that together with genes for high tolerance to environmental stresses might explain a successful strategy of symbiosis in the tropics. The strain also harbours interesting sets of genes with biotechnological potential. However, the resemblance of certain genes to those of pathogenic Burkholderia raise concerns about large-scale applications in agriculture or for bioremediation

Governance of ecological restoration at different scales: global, regional, sub-national

Desde su inicio formal en 1987, la restauración ecológica evolucionó de una disciplina técnica a un campo trans-episté-mico que alberga científicos, profesionales y actores sociales directamente vinculados a la toma de decisiones, es decir, a la gobernanza de la restauración. Actual-mente, los desafíos prioritarios son más bien políticos, socioculturales, económicos o territoriales, mientras que las decisiones deben estar orientadas a revertir las causas de degradación y manejar los recursos de manera sustentable. Por lo tanto, las medidas no estructurales dependen de la efectiva aplicación de la gobernanza ambiental, tanto pública como privada. En este trabajo se plantea qué gobernanza requiere la restauración, desarrollando la problemática a tres escalas: mundial, regional y sub-nacional o local. Se identifican las necesidades de gobernanza por regiones y las prioridades de gobernanza por dimensiones. Las políticas y modelos culturales de cada región tienen una alta influencia en las situaciones de degradación y sus soluciones, por lo que se recomienda que cada capítulo, red o sociedad de restauración trabaje en los problemas de gobernanza local-nacional.Fil: Zuleta, Gustavo Adolfo. Universidad Maimónides. Centro de Ciencias Naturales, Ambientales y Antropológicas. Departamento de Ecología y Ciencias Ambientales; ArgentinaFil: Hamerlynck, O.. Kenya Wetlands Biodiversity Research Team; KeniaFil: Liu, J.. Southern University Of Science And Technology; ChinaFil: Morales, N.. Universidad Mayor.; ChileFil: Dorado, A.. Universidad Maimónides. Centro de Ciencias Naturales, Ambientales y Antropológicas. Departamento de Ecología y Ciencias Ambientales; Argentina. Universidade de Sao Paulo; BrasilFil: Rovere, Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Espinoza Mendoza, Victoria Emperatriz. Universidad Maimónides. Centro de Ciencias Naturales, Ambientales y Antropológicas. Departamento de Ecología y Ciencias Ambientales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rescia A. J.. Universidad Complutense de Madrid; EspañaFil: Guida Johnson, Bárbara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Fernández Cuppari, M.. Universidad Maimónides. Centro de Ciencias Naturales, Ambientales y Antropológicas. Departamento de Ecología y Ciencias Ambientales; Argentin

The SPIRou Legacy Survey Rotation period of quiet M dwarfs from circular polarization in near-infrared spectral lines: I. The SPIRou APERO analysis

Context. The rotation period of stars is an important parameter along with mass, radius, effective temperature. It is an essential parameter for any radial velocity monitoring, as stellar activity can mimic the presence of a planet at the stellar rotation period. Several methods exist to measure it, including long sequences of photometric measurements or temporal series of stellar activity indicators. Aims. Here, we use the circular polarization in near-infrared spectral lines for a sample of 43 quiet M dwarfs and compare the measured rotation periods to those obtained with other methods. Methods. From Stokes V spectropolarimetric sequences observed with SPIRou at CFHT and the data processed with the APERO pipeline, we compute the least squares deconvolution profiles using different masks of atomic stellar lines with known Land\'e factor appropriate to the effective temperature of the star. We derive the longitudinal magnetic field to examine its possible variation along the 50 to 200 observations of each star. For determining the stellar rotation period, we apply a Gaussian process regression enabling us to determine the rotation period of stars with evolving longitudinal field. Results. Among the 43 stars of our sample, we were able to measure a rotation period for 27 stars. For 8 stars, the rotation period was previously unknown. We find a good agreement of our rotation periods with periods found in the literature based on photometry and activity indicators and confirm that near-infrared spectropolarimetry is an important tool to measure rotation periods, even for magnetically quiet stars. Furthermore, we compute ages for 20 stars of our sample using gyrochronology

Complete genome sequence of Burkholderia phenoliruptrix BR3459a (CLA1), a heat-tolerant, nitrogen-fixing symbiont of mimosa flocculosa.

The genus Burkholderia represents a challenge to the fields of taxonomy and phylogeny and, especially, to the understanding of the contrasting roles as either opportunistic pathogens or bacteria with biotechnological potential. Few genomes of nonpathogenic strains, especially of diazotrophic symbiotic bacteria, have been sequenced to improve understanding of the genus. Here, we contribute with the complete genome sequence of Burkholderia phenoliruptrix strain BR3459a (CLA1), an effective diazotrophic symbiont of the leguminous tree Mimosa flocculosa Burkart, which is endemic to South America