Magnetic exchange mechanism for electronic gap opening in graphene

We show within a local self-consistent mean-field treatment that a random distribution of magnetic adatoms can open a robust gap in the electronic spectrum of graphene. The electronic gap results from the interplay between the nature of the graphene sublattice structure and the exchange interaction between adatoms.The size of the gap depends on the strength of the exchange interaction between carriers and localized spins and can be controlled by both temperature and external magnetic field. Furthermore, we show that an external magnetic field creates an imbalance of spin-up and spin-down carriers at the Fermi level, making doped graphene suitable for spin injection and other spintronic applications.Comment: 5 pages, 5 figure

Produção de sementes de guandu.

bitstream/CPPSE/17295/1/Documentos69.pd

Phenolic composition of commercial açaí pulps.

Este estudo teve como objetivo determinar a composição fenólica de três polpas de açaí comerciais, provenientes de Belém, Pará, Brasil. As antocianinas e os compostos não-antociânicos foram determinados por cromatografia líquida de alta eficiência acoplada a um detector de arranjo de diodos. A antocianina 3-rutinosídeo foi a principal antocianina presente em amostras de polpa de açaí liofilizados. A amostra comercial C apresentou a maior quantidade de cianidina 3-glicosídeo e cianidina 3-rutinosídeo ( 18.942 mg g-1 e 34.397 mg g-1 de amostra liofilizada, respectivamente). O conteúdo de compostos fenólicos variou significativamente entre as amostras comerciais e o ácido vanílico apresentou a maior concentração nas amostras estudadas

Development, uncertainty estimation and application of a LC-MS/MS method for simultaneous determination of acrylamide and 4hydroxy2,5-dimethyl-3(2H)-furanone in baby food.

Acrylamide, a heatgenerated food contaminant, has been associated with neurotoxic effects in humans and was classified under group 2A as a probable human carcinogen by the International Agency Research on Cancer (IARC) [1]. Additionally, hydroxy2,5dimethyl3(2H)furanone (DMHF), a furanic compound, has demonstrated genotoxic effects in vitro as also in vivo [2]. In this study, a new accurate liquid chromatographytandem mass spectrometry method was developed for simultaneous analysis of acrylamide and DMHF in baby food. To the best of our knowledge, this is the first study on DMHF in baby foods as well as pioneer in acrylamide monitoring in baby foods from Brazil. For this, a sample preparation method was optimized, which involves acetonitrile-based extraction, followed by dispersive solidphase extraction (dSPE) using primary and secondary amine sorbent (PSA) and then, a final cleanup of extract by solid phase extraction (SPE). An ACQUITY ultraperformance liquid chromatography (UPLC) system interfaced to a Quattro Premier XE triple quadrupole mass spectrometer with electrospray ionization (ESI) source (WATERS) was employed for analysis. The chromatographic separation was achieved on a C8 column (150 mm x 2.1 mm i.d., 5?m particle size) at 30ºC with a flow rate of 0.2 ml/min, and the injection volume was 20 ?l. The mobile phases consisted of MilliQ water (A) and acetonitrile (B), both containing 0.01% of formic acid, and the elution gradient employed was as follows: 0 min, 5% B? 5 min, 50% B? 5.1 min, 100% B? 6?10 min 5% B, resulting in a total run time of 10 min. Data acquisition was carried out in selective reaction monitoring (SRM) mode employing ESI in positive mode, whose conditions were: capillary voltage 3 KV? temperatures of source at 120°C and desolvation at 400°C and gas flow 500 L/h. The collision energy and cone voltage were 10 and 25 V. The m/z 55 and 44 (acrylamide) and m/z 101 and 83 (DMHF) were used respectively for quantitative and confirmative purposes. As a great result, the optimized sample preparation method provided sufficient removal of potential analytical interfering commonly present in fruitbased matrices, the amino acid valine, without affecting the sensitivity, trueness and precision of the method. Limits of detection (LOD) and quantification (LOQ) of 10 and 20 ?g/kg were obtained for both analytes. Linearity in solventonly and matrixmatched calibration curves was achieved in the range between 10 and 300 ?g/kg, with determination coefficients higher than 0.99. Matrix effects, calculated from slopes obtained for solvent and matrixmatched calibrations, were observed for acrylamide (?45%) and DMHF(?11%). Recoveries between 75 and 115% were obtained for the two studied compounds from blank baby foods spiked at 20 (LOQ), 100 and 200 ?g/kg. Precision, under repeatability and withinlaboratory reproducibility conditions, was verified with RSD values < 20%. In addition, by using data obtained from inhouse validation, was possible to estimate the expanded measurement uncertainty for the levels of acrylamide and DMHF detected in the samples, whose values were lower than 25%. The applicability of proposed analytical method was evaluated by analyzing 20 baby food samples available in Brazilian markets

Development and validation of a new standard area diagram set to estimate severity of soybean rust.

Título em português: Desenvolvimento e validação de uma nova escala diagramática para estimar severidade de ferrugem asiática da soja

Vitamin A in diets for Nile tilapia.

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Dietary vitamin supplementation decrease stress caused by high stocking density, and boosts immunological system of farmed fish. A studied was carried out to determine vitamin A requirements of Nile tilapia (Oreochromis niloticus) in an all male group (13.8 ± 1.2 g) and a mixed sex population (9.8 ± 2.3 g). Fish stocked in 100-L plastic aquaria (26.0 ± 1.0ºC) were fed to near satiety, twice a day, seven days a week, during 75 days with vitamin A-free, semi-purified diets supplemented with 0; 600; 1,200; 1,800; 2,400; 3,000; 3,600; 4,200; 4,800 and 5,400 International Units (IU) of retinyl palmitate (30% vitamin A) per kg of diet in a completely randomized experimental design, factorial arrangement 2c10 (n = 4). Deficiency signs of vitamin A were observed in fish fed 0 to 1.200 IU vitamin A kg-1 diet; moderate signs were observed in fish fed diets with 1.800 to 3.600 IU vitamin A kg-1 diet; no interactions group*level (p 0.05). A group effect was observed regarding all performance variables (p 0,05). Foi observado efeito de grupo no desempenho dos peixes (p < 0,0001). Foi detectado o retinol hepático através de HPLC somente no grupo alimentado com 5.400 UI de retinol kg-1 de dieta, caracterizando assim que o mesmo foi utilizado e armazenado. A quantidade de 5.400 IU de retinol kg-1 de dieta é a mínima recomendada para tilápia do Nilo.666751756Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP_Brasi

Produção de álcool etílico de colmos de sorgo sacarino em microdestilaria.

A producao de etanol a partir de acucares fermentesciveis de fontes renovaveis de energia, despontou como a mais viavel para substituir os combustiveis derivados de petroleo. As tecnologias para transformar carboidratos em etanol sao bem conhecidos desde longa data, sendo utilizadas como principais fontes de obtencao de acucares fermentesciveis a cana-de-acucar e a beterraba acucareira. Entretanto, nao ha nenhuma limitacao no uso do sorgo sacarino como materia-prima para producao de etanol. Com o aumento do interesse em um melhor uso desta nova fonte de biomassa energetica, informacoes adicionais devem ser obtidas para avaliar o real potencial dessa nova fonte renovavel de energia. Pelo fato de se adaptar as condicoes climaticas diversas, rapido crescimento, moderada exigencia de agua e elevado conteudo de carboidrato, o sorgo sacarino podera vir a se constituir em uma cultura de alto valor para as regioes tropicais e sub-tropicais. Nos experimentos a cultivar de sorgo sacarino BR-505, originaria da cultivar norte-americana Wray, foi plantada nos anos agricolas de 1984/85 e 1985/86, para avaliar o seu comportamento como materia-prima para producao de alcool etilico em microdestilaria. Amostras de colmos foram retiradas por algumas semanas, a partir do aparecimento das paniculas ate que os graos atingissem o estadio firme, que ocorreu 120 dias apos o plantio. Foram determinados nos colmos os teores de acucares redutores, acucares totais e sacarose. O teor em acucares redutores decresceu durante a maturacao do grao, provavelmente pelo fato de ser assimilado na forma de outros metabolicos. O teor em sacarose aumentou significativamente atingindo valores altos quando os graos estavam maduros, bem firmes. Deste modo, e possivel cultivar o sorgo sacarino com dupla finalidade: uso dos colmos para producao de etanol, e uso dos graos para racao animal e/ou consumo humano. Foram obtidos rendimentos de colmos e folhas de 40-50 t.ha no estadio de maturacao completa das paniculas, com uma producao adicional de graos de 2, 5-3, 5 t/ha. Os colmos e folhas foram processadas em uma microdestilaria com sistema de difusao, obtendo-se alta taxa de extracao de acucares fermentesciveis, que permitiu a obtencao de cerca de 50 litros de etanol por tonelada de materia-prima

A Nomadic Testbed for Teaching Computer Architecture

A nomadic laboratory or testbed, based on Raspberry Pi 3 computers and Arduino microcontrollers, has been developed in order to teach subjects related to computer architecture. The testbed can be transported to the classroom. Students can access it through the available network, which can be a wireless LAN, wired LAN o a custom network. The student can access without constraints to the platforms, therefore there are a wide range of possible experiments. This laboratory was used during 2017 for practical works in the course Introduction to Technology, and during 2018 in the course Computers Architecture at Universidad Nacional of Cuyo. Some of the experiments that are been carried out by students are: to explore and analyse the architecture of the computers through Linux commands, write and run programs on different programing languages, input and output operations through memory mapped addressing and isolated addressing, write interrupt service routines in order to service interrupts, multithreading programing, explore memory maps, CPU features, etc. This paper describes the testbed architecture, experiments performed by students in the mentioned subjects, present the students feedback, and describes the possible methods in order to integrate it to a remote laboratory.XVII Workshop Tecnología Informática Aplicada en Educación (WTIAE)Red de Universidades con Carreras en Informática (RedUNCI