27,645 research outputs found

    Contribuição de bactérias diazotrópicas na cultura da bananeira: perspectivas de utilização na produção integrada.

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    Esta pesquisa objetivou avaliar a ocorrência de bactérias diazotróficas na cultura da bananeira no Estado do Ceará (Brasil), selecionar bactérias diazotróficas endofíticas em associação com mudas da cultivar Grande Naine, avaliar produção de bananas nas cultivares Grande Naine (subgrupo Cavendish), Ambrosia, Buccaner e Calypso (subgrupo Gros Michel) em resposta à inoculação de bactéria selecionada em mudas e verificar o potencial de bactéria diazotrófica na proteção de plantas da cultivar Maçã contra o fungo Fusarium oxysporum f. sp. cubense, causador da fusariose na bananeira. As bananeiras das cultivares Pacovan e Prata (subgrupo Prata) e Couruda (subgrupo Figo) plantadas no Ceará estavam associadas de bactérias diazotróficas relacionadas aos gêneros Burkholderia e Herbaspirillum. Em experimento com mudas micropropagadas da cultivar Grande Naine constatou-se que bactérias endofíticas do tipo Burkholderia variam em eficiência na promoção do crescimento das plantas. A inoculação do isolado de bactéria relacionada a B. cepacia AB202 em mudas resultou no aumento de produtividade das cultivares dos subgrupos Cavendish (2.900kg ha- 1) e Gros Michel (1.400kg ha-1). Na cultivar Maçã, a tecnologia permitiu reduzir a incidência de fusariose em 7,4% (113 plantas por ha). Estes resultados confirmam a influência de bactérias diazotróficas na cultura da bananeira, sugerindo a possibilidade do uso desta tecnologia por viveiristas e produtores de banana em busca da produção integrada de frutas.bitstream/CNPMA/5376/1/boletim_16.pd

    A tunable, dual mode field-effect or single electron transistor

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    A dual mode device behaving either as a field-effect transistor or a single electron transistor (SET) has been fabricated using silicon-on-insulator metal oxide semiconductor technology. Depending on the back gate polarisation, an electron island is accumulated under the front gate of the device (SET regime), or a field-effect transistor is obtained by pinching off a bottom channel with a negative front gate voltage. The gradual transition between these two cases is observed. This dual function uses both vertical and horizontal tunable potential gradients in non-overlapped silicon-on-insulator channel

    Triphilic ionic-liquid mixtures: fluorinated and non-fluorinated aprotic ionic-liquid mixtures

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    We present here the possibility of forming triphilic mixtures from alkyl- and fluoroalkylimidazolium ionic liquids, thus, macroscopically homogeneous mixtures for which instead of the often observed two domainspolar and nonpolarthree stable microphases are present: polar, lipophilic, and fluorous ones. The fluorinated side chains of the cations indeed self-associate and form domains that are segregated from those of the polar and alkyl domains. To enable miscibility, despite the generally preferred macroscopic separation between fluorous and alkyl moieties, the importance of strong hydrogen bonding is shown. As the long-range structure in the alkyl and fluoroalkyl domains is dependent on the composition of the liquid, we propose that the heterogeneous, triphilic structure can be easily tuned by the molar ratio of the components. We believe that further development may allow the design of switchable, smart liquids that change their properties in a predictable way according to their composition or even their environment

    Polarographic Behaviour of +6 Uranium in a Mixture of Salycilic and Sulphuric Acid

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    The half- wave potential, the diffusion coefficient and the diffusion current constant of + 6 uranium in the supporting electrolyte containing 1.60 g/l salicylic acid, 0.4% v v sulphuric acid and 0.009 % thymol (as maximum suppressor) have been determined. The electrocapillary curve of mercury in this electrolyte is also given

    Contacting single bundles of carbon nanotubes with alternating electric fields

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    Single bundles of carbon nanotubes have been selectively deposited from suspensions onto sub-micron electrodes with alternating electric fields. We explore the resulting contacts using several solvents and delineate the differences between Au and Ag as electrode materials. Alignment of the bundles between electrodes occurs at frequencies above 1 kHz. Control over the number of trapped bundles is achieved by choosing an electrode material which interacts strongly with the chemical functional groups of the carbon nanotubes, with superior contacts being formed with Ag electrodes.Comment: 4 pages, RevTe

    Polarographic Behaviour of +6 Uranium in a Mixture of Salycilic and Sulphuric Acid

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    The half- wave potential, the diffusion coefficient and the diffusion current constant of + 6 uranium in the supporting electrolyte containing 1.60 g/l salicylic acid, 0.4% v v sulphuric acid and 0.009 % thymol (as maximum suppressor) have been determined. The electrocapillary curve of mercury in this electrolyte is also given

    Is My Exercise Partner Similar Enough? Partner Characteristics as a Moderator of the Köhler Effect in Exergames

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    Objective: Recent research has shown the Köhler motivation gain effect (working at a task with a more capable partner where one's performance is indispensable to the group) leads to greater effort in partnered exercise videogame play. The purpose of this article was to examine potential moderators of the Köhler effect by exploring dissimilarities in one's partner's appearance, namely, having an older partner (compared with a same-age partner) and having a heavier-weight partner (compared with a same-weight partner). Subjects and Methods: One hundred fifty-three male and female college students completed a series of plank exercises using the “EyeToy: Kinetic™” for the PlayStation® 2 (Sony, Tokyo, Japan). Participants first completed the exercises individually and, after a rest, completed the same exercises with a virtually present partner. Exercise persistence, subjective effort, self-efficacy beliefs, enjoyment, and intentions to exercise were recorded and analyzed. Results: A significant Köhler motivation gain was observed in all partner conditions (compared with individual controls) such that participants with a partner held the plank exercises longer (P<0.001) and reported higher subjective effort (P<0.01). These results were unmoderated by partner's age and weight, with one exception: Males tended to persist longer when paired with an obese partner (P=0.08). Conclusions: These results suggest that differences in age and weight do not attenuate the Köhler effect in exergames and may even strengthen it

    Backbone of complex networks of corporations: The flow of control

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    We present a methodology to extract the backbone of complex networks based on the weight and direction of links, as well as on nontopological properties of nodes. We show how the methodology can be applied in general to networks in which mass or energy is flowing along the links. In particular, the procedure enables us to address important questions in economics, namely, how control and wealth are structured and concentrated across national markets. We report on the first cross-country investigation of ownership networks, focusing on the stock markets of 48 countries around the world. On the one hand, our analysis confirms results expected on the basis of the literature on corporate control, namely, that in Anglo-Saxon countries control tends to be dispersed among numerous shareholders. On the other hand, it also reveals that in the same countries, control is found to be highly concentrated at the global level, namely, lying in the hands of very few important shareholders. Interestingly, the exact opposite is observed for European countries. These results have previously not been reported as they are not observable without the kind of network analysis developed here.Comment: 24 pages, 12 figures, 2nd version (text made more concise and readable, results unchanged

    Treatment of Polarographic Data by the Method of Least-squares. II. Simultaneous Estimation of the Diffusion Current and the Half-wave Potential

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    By applying the method of least squares it is possible to estimate simultaneously the diffusion current and the half-wave potential with precision which exceeds that of the usual graphical methods. The method described in this paper is particularly suitable for analysing composite current-voltage curves. An example is given of the analysis of the composite curve obtained with a solution containing thallous and lead ions in 0.1 N KC
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