Production of Cu/Diamond composites for first-wall heat sinks

Due to their suitable thermal conductivity and strength copper-based materials have been considered appropriate heat sinks for first wall panels in nuclear fusion devices. However, increased thermal conductivity and mechanical strength are demanded and the concept of property tailoring involved in the design of metal matrix composites advocates for the potential of nanodiamond dispersions in copper. Copper-nanodiamond composite materials can be produced by mechanical alloying followed by a consolidation operation. Yet, this powder metallurgy route poses several challenges: nanodiamond presents intrinsically difficult bonding with copper; contamination by milling media must be closely monitored; and full densification and microstructural homogeneity should be obtained with consolidation. The present line of work is aimed at an optimization of the processing conditions of Cu-nanodiamond composites. The challenges mentioned above have been addressed, respectively, by incorporating chromium in the matrix to form a stable carbide interlayer binding the two components; by assessing the contamination originating from the milling operation through particle-induced X-ray emission spectroscopy; and by comparing the densification obtained by spark plasma sintering with hot-extrusion data from previous studies

In‐plane shear strength of single‐lap co‐cured joints of self‐reinforced polyethylene composites

The present study introduces the analysis of single‐lap co‐cured joints of thermoplastic self‐reinforced composites made with reprocessed low‐density polyethylene (LDPE) and reinforced by ultra‐high‐molecular‐weight polyethylene (UHMWPE) fibers, along with a micromechanical analysis of its constituents. A set of optimal processing conditions for manufacturing these joints by hot‐press is proposed through a design of experiment using the response surface method to maximize their in‐plane shear strength by carrying tensile tests on co‐cured tapes. Optimal processing conditions were found at 1 bar, 115 °C, and 300 s, yielding joints with 6.88 MPa of shear strength. The shear failure is generally preceded by multiple debonding‐induced longitudinal cracks both inside and outside the joint due to accumulated transversal stress. This composite demonstrated to be an interesting structural material to be more widely applied in industry, possessing extremely elevated specific mechanical properties, progressive damage of co‐cured joints (thus avoiding unannounced catastrophic failures) and ultimate recyclability

Self-powered proton detectors based on GaN core shell p n microwires

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Produção de biomassa e valor nutricional do Cajanus cajan cv. Mandarin sob manejo orgânico e convencional.

O objetivo deste estudo foi comparar a produção de matéria seca (MS kg.ha), os teores de matéria seca (MS%), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) do Cajanus Cajan cv. Mandarin, sob manejo orgânico e convencional. No manejo orgânico foram utilizados o calcário dolomítico, gesso mineral, cama de frango, termofosfato magnesiano e termopotássio. E no manejo convencional foram utilizados o calcário dolomítico, fosfogesso, uréia, supertriplo e cloreto de potássio. Na análise estatística foi utilizado o delineamento inteiramente casualisado, no esquema de parcelas subdivididas com dois tratamentos e seis repetições. Os resultados obtidos para a MS kg.ha, MS%, FDN% e FDA% foram de 13310,7 kg.ha, 53,6%, 57,9% e 41,7% para o manejo orgânico e 13.142,3 kg.ha, 46,7%, 53,5% e 40,3% para o convencional, respectivamente. Não houve diferenças entre os manejos adotados para nenhum dos parâmetros estudados com exceção da FDN% que foi superior para a leguminosa em sistema orgânico. Abstract: The objective of this study was to compare the Dry matter production (DM kg. ha), the levels of dry matter (DM), neutral (NDF) and acid detergent fiber (FDA) of Cajanus cajan cv. Mandarin between organic and conventional management. In organic management was used the dolomitic limestone, mineral gypsum, chicken manure, magnesium thermophosphate and thermopotassium. In conventional management were used dolomitic limestone, phosphogypsum, urea, superphosphate and potassium chloride. The experiment was divided into randomized design in split plots with two treatments and six repetitions. The results obtained for the MS kg. ha, MS%, NDF% and FDA% were 13310.7 kg. ha, 53.6% 57.9% and 41.7% for the organic management and 13142. 3 kg. ha, 46.7%, 53.5% and 40.3% for the conventional respectively. No differences were found between the adopted management for any parameters studied except for the NDF% that was superior to the legumes in organic system

The nature of LINER galaxies: Ubiquitous hot old stars and rare accreting black holes

Galaxies, which often contain ionised gas, sometimes also exhibit a so-called low-ionisation nuclear emission line region (LINER). For 30 years this was attributed to a central mass-accreting supermassive black hole (AGN) of low luminosity, making LINER galaxies the largest AGN-sub-population, dominating in numbers over higher luminosity Seyfert galaxies and quasars. This, however, poses a serious problem. While the inferred energy balance is plausible, many LINERs clearly do not contain any other independent signatures of an AGN. Using integral field spectroscopic data from the CALIFA survey, we aim at comparing the observed radial surface brightness profiles with what is expected from illumination by an AGN. Essential for this analysis is a proper extraction of emission-lines, especially weak lines such as the Balmer Hb line which is superposed on an absorption trough. To accomplish this, we use the GANDALF code which simultaneously fits the underlying stellar continuum and emission lines. We show for 48 galaxies with LINER-like emission, that the radial emission-line surface brightness profiles are inconsistent with ionisation by a central point-source and hence cannot be due to an AGN alone. The most probable explanation for the excess LINER-like emission is ionisation by evolved stars during the short but very hot and energetic phase known as post-AGB. This leads us to an entirely new interpretation. Post-AGB stars are ubiquitous and their ionising effect should be potentially observable in every galaxy with gas present and stars older than ~1 Gyr, unless a stronger radiation field from young hot stars or an AGN outshines them. This means that galaxies with LINER-like emission are in fact not a class defined by a property, but rather by the absence of a property. It also explains why LINER emission is observed mostly in massive galaxies with old stars and little star formation.Comment: 8 pages, 7 figure

The Mass-Metallicity relation explored with CALIFA: I. Is there a dependence on the star formation rate?

We present the results on the study of the global and local M-Z relation based on the first data available from the CALIFA survey (150 galaxies). This survey provides integral field spectroscopy of the complete optical extent of each galaxy (up to 2-3 effective radii), with enough resolution to separate individual HII regions and/or aggregations. Nearly $\sim$3000 individual HII regions have been detected. The spectra cover the wavelength range between [OII]3727 and [SII]6731, with a sufficient signal-to-noise to derive the oxygen abundance and star-formation rate associated with each region. In addition, we have computed the integrated and spatially resolved stellar masses (and surface densities), based on SDSS photometric data. We explore the relations between the stellar mass, oxygen abundance and star-formation rate using this dataset. We derive a tight relation between the integrated stellar mass and the gas-phase abundance, with a dispersion smaller than the one already reported in the literature ($\sigma_{\Delta{\rm log(O/H)}}=$0.07 dex). Indeed, this dispersion is only slightly larger than the typical error derived for our oxygen abundances. However, we do not find any secondary relation with the star-formation rate, other than the one induced due to the primary relation of this quantity with the stellar mass. We confirm the result using the $\sim$3000 individual HII regions, for the corresponding local relations. Our results agree with the scenario in which gas recycling in galaxies, both locally and globally, is much faster than other typical timescales, like that of gas accretion by inflow and/or metal loss due to outflows. In essence, late-type/disk dominated galaxies seem to be in a quasi-steady situation, with a behavior similar to the one expected from an instantaneous recycling/closed-box model.Comment: 19 Pages, 8 figures, Accepted for Publishing in Astronomy and Astrophysics (A&A

Fertirrigação e agricultura de baixa emissão de carbono: resultados do projeto CNPq/REPENSA em São Gabriel do Oeste.

Este trabalho apresenta no âmbito do CNPq/REPENSA (Redes Nacionais de Pesquisa em Agrobiodiversidade e Sustentabilidade Agropecuária), Projeto número 562441/2010-7, ?Estruturação de rede de monitoramento e base compartilhada de dados de sistemas de produção integrada e intensiva sustentável (suinocultura-agrosilvipastoril) em assentamento de reforma agrária visando balanços favoráveis de água, energia e nutrientes?, informações norteadoras para projetos de fertirrigação para uma agricultura de baixa emissão de carbono. A fertirrigação vem se consolidando como atividade integradora de cadeias produtivas outrora dissociadas, sendo ferramenta importante de inclusão social no meio rural na borda do Pantanal (Bacia do Alto Taquari), transformando externalidades ambientais em fonte de renda e ganhos de produtividade agropecuária. Os resultados e indicadores aqui apresentados mostram que a fertirrigação com efluente de biodigestor de granjas de suínos, aqui convencionado de biofertilizante, gera impactos negativos e positivos. Os negativos recaem no potencial para eutrofização de corpos d?água por nitrogênio reativo na forma de nitratos (NO3); ambos os processos podem e devem ser substancialmente minimizados pelo uso controlado e eficiente do biofertilizante na agropecuária com doses adequadas de macro (especialmente N, P, K) e micronutrientes (Cu e Zn, entre outros) para diversasculturas, conforme discutido neste trabalho. Os impactos positivos são a manutenção do estoque de carbono no solo no longo prazo mediante manejo adequado da produção de forragem para gado (corte ou leite) ou na produção de grãos com tecnologias de conservação de solo, e o balanço favorável das emissões de gases de efeito estufa do agroecossistema como um todo pela substituição de diesel por biogás em motogeradores e motobombas, pela substituição da adubação mineral e de agrotóxicos (ambos não renováveis) e pela possibilidade de recomposição de mata proporcional à um terço dos ganhos de produtividade. Em termos de mecanismo de adaptação à mudança do clima, a restauração relativa de áreas de mata nativa favorece a recuperação e/ou manutenção de outros importantes serviços ambientais, como o aumento da agrobiodiversidade, a produção de água e incremento da polinização por insetos.bitstream/item/111107/1/BP116.pd

CALIFA : a diameter-selected sample for an integral field spectroscopy galaxy survey

JMA acknowledges support from the European Research Council Starting Grant (SEDmorph; P.I. V. Wild).We describe and discuss the selection procedure and statistical properties of the galaxy sample used by the Calar Alto Legacy Integral Field Area (CALIFA) survey, a public legacy survey of 600 galaxies using integral field spectroscopy. The CALIFA "mother sample" was selected from the Sloan Digital Sky Survey (SDSS) DR7 photometric catalogue to include all galaxies with an r-band isophotal major axis between 45 '' and 79 : 2 '' and with a redshift 0 : 005 M-r > -23 : 1 and over a stellar mass range between 10(9.7) and 10(11.4) M-circle dot. In particular, within these ranges, the diameter selection does not lead to any significant bias against - or in favour of - intrinsically large or small galaxies. Only below luminosities of M-r = -19 (or stellar masses <10(9.7) M-circle dot) is there a prevalence of galaxies with larger isophotal sizes, especially of nearly edge-on late-type galaxies, but such galaxies form <10% of the full sample. We estimate volume-corrected distribution functions in luminosities and sizes and show that these are statistically fully compatible with estimates from the full SDSS when accounting for large-scale structure. For full characterization of the sample, we also present a number of value-added quantities determined for the galaxies in the CALIFA sample. These include consistent multi-band photometry based on growth curve analyses; stellar masses; distances and quantities derived from these; morphological classifications; and an overview of available multi-wavelength photometric measurements. We also explore different ways of characterizing the environments of CALIFA galaxies, finding that the sample covers environmental conditions from the field to genuine clusters. We finally consider the expected incidence of active galactic nuclei among CALIFA galaxies given the existing pre-CALIFA data, finding that the final observed CALIFA sample will contain approximately 30 Sey2 galaxies.Peer reviewe

Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 $< p_{\rm{T}, assoc} < p_{\rm{T}, trig} <$ 5.0 GeV/$c$ is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range $|\eta|<0.9$. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

Multi-particle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider

Measurements of multi-particle azimuthal correlations (cumulants) for charged particles in p-Pb and Pb-Pb collisions are presented. They help address the question of whether there is evidence for global, flow-like, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a $|\Delta \eta|$ gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high-multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of $v_{2}\{4\}$ to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find $v_{2}\{4\} \simeq v_{2}\{6\}\neq 0$ which is indicative of a Bessel-Gaussian function for the $v_{2}$ distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a $|\Delta\eta| > 1.4$ gap is placed.Comment: 25 pages, 11 captioned figures, 3 tables, authors from page 20, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/87