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Ferreira J.A.M.,University of Coimbra | Reis P.N.B.,CCTA | Costa J.D.M.,University of Coimbra | Richardson B.C.H.,CTA Ltd. | Richardson M.O.W.,CTA Ltd.
Composites Part B: Engineering | Year: 2011

This paper presents the results of a current study concerned with the mechanical properties of a polypropylene binder resin, enhanced by nanoclay filler. The study was centred on the potential benefits obtained by the addition of specially surface treated nanoclays on the stiffness, toughness and also on static and fatigue strength. Specimens were produced by an injection moulding process with 3% in weight of nanoclay. Surface treatment of the nanoclay promotes a tendency to increase stiffness and tensile strength in comparison with composites filled by both commercial nanoclay and unfilled material. Nanoclay filling significantly improves absorbed impact energy in comparison with unfilled materials, but in contrast Gc values are significantly lower as consequence of the material embrittlement. Fatigue analysis shows that the materials tested in the present work exhibit high strain accumulation and stress release. Filled material show lower fatigue performance than unfilled polymer. However, surface treatment used on B3 composite promotes better clay dispersion and smaller particle size leading to a fatigue performance close to matrix polymer. © 2011 Elsevier Ltd. All rights reserved. Source

do Amaral T.L.,CCTA | Jasmim J.M.,Laboratorio Of Fitotecnia Do Ccta | Araujo J.S.P.,Federal Rural University of Rio de Janeiro | Thiebaut J.T.L.,LEAG | And 2 more authors.
Ciencia e Agrotecnologia | Year: 2010

The research objective was to evaluate the efficiency of substrates and fertilization levels on the growth and leaf nutrient contents of orchid hybrids of the genus Phalaenopsis. The study consisted of two experiments in carried out with industrialized coconut fiber (Sub 1) and non-industrialized coconut fiber (Sub 2), in mixture with Pinus bark and grade zero gravel (1:1:1 v/v/v) in randomized blocks. The first experiment in a split-plot scheme in time (6 and 12 months) with five replications, evaluated the hybrid RJ 343, in both substrates, under four levels of mineral fertilizer (0; 0.9; 1.2; 1.5 g L-1) and two additional treatments [leaf application of Aminon® (0.5 ml L-1) at 1.2 g L-1, in Sub1 and Sub 2]. The second one evaluated the hybrid RJ 84-2, in both substrates, with the same mineral fertilizer levels and leaf application of Aminon® (0 e 0.5 ml L-1), in a split-split-split plot scheme in time (6 and 12 months) with three replications. The number of leaves, leaf area, superficial root area, leaf, root and total dry weight, and N, P and K leaf contents were evaluated. Aminon® had no effect on the growth of the hybrids. Increase in fertilization led to increased growth, except for roots, with greater growth being observed at 1.5 g L-1 of mineral fertilizer. The Sub 2 caused greater growth of plants of the hybrid RJ 343, whereas the Sub 1 led to greater growth of the hybrid RJ 84-2. Source

Soleil D.,EMCS Engineering | Alcaras A.,Thales Alenia | Le Ho P.,CCTA | Zeigler G.,SPGS Inc. | Lambert P.,Trapil
European Corrosion Congress 2010 - EUROCORR 2010 | Year: 2010

This paper presents an example of a petroleum station where are developed typical innovated protections about the application of a new EMC concept on the electromagnetic compatibility studies and protections for systems. This concept specifically adapted on the field of large and complex sensitive installations is called the "zero method". It uses an accessible and easy process to control what happen inside of the electrical and electronical systems and consequently how to protect them. This new approach is agreed by international IEC standards particularly 62 305 -1 to 4, and applied in hospitals and research buildings, computer centers - hydroelectrical power plants, gas and petroleum plants etc ...to find quickly economic and technical performing solutions against damages caused by lightning and industrial parasitic currents effects. Source

Vasconcellos M.A.S.,Federal Rural University of Rio de Janeiro | Leitao G.R.,Federal Rural University of Rio de Janeiro | Ducatti C.,Sao Paulo State University | Carvalho A.J.C.,CCTA
Acta Horticulturae | Year: 2010

This study's objective is to evaluate the photosynthates partitioning and source-sink relationships, in vegetative and reproductive twigs of sweet passion fruit, using the carbon-13, stable isotope of carbon. The leaves of vegetative and reproductive twigs were placed in a sealed chamber and 13CO 2 were injected for 30 minutes. After six hours, the different organs of the twig were collected and immersed in liquid nitrogen (-196°C). All plant samples were oven-dried, powdered and combusted in an elemental analyzer. The results showed that the methodology was efficient to evaluate the partitioning of photosynthates. In the vegetative twigs, the new open leaves, the closed leaves and growth meristem were the principal sink for the source leaves enriched with 13CO 2. In the reproductive twigs with only flowers buds, the source-sink relationship was changed and the flowers buds turn to be the principal sink and the growing leaves were secondary sinks. The presence of young fruits changed again the source-sink relationship of the twig, and they were the principal sinks. The apical leaves, with 60% of final leaf area were also a sink for photosynthates. Source

Barreto P.A.B.,State University of Norte Fluminense | Gama-Rodrigues E.F.,CCTA | Gama-Rodrigues A.C.,CCTA | de Barros N.F.,Federal University of Vicosa | Fonseca S.,FIBRIA CELULOSE S.A.
Revista Brasileira de Ciencia do Solo | Year: 2010

To maximize the efficiency of N uptake by plants it is important to study N and C mineralization, particularly in the case of eucalyptus, which has a very low response to nitrogen fertilization. The rates of C and N mineralization and C and N mineralization potential were estimated, in soils under 1, 3, 5, and 13 year-old eucalyptus plantations with similar soil and climatic conditions. Soil from the 0-10 cm layer was sampled in November 2003. The samples were incubated under aerobic laboratory conditions for successive periods of 1, 1, 1, 2, 2, 4, 4, 4 weeks in a total of 19 weeks. The mineralized N was periodically extracted and determined colorimetrically, and the mineralized C was determined based on C-CO 2 evolution. The average accumulated N was 58 mg kg -1 soil and it did not differ significantly among ages. Potentially mineralizable N (N o) varied between 58 to 87 mg kg -1soil, which represented 3.4 to 5.2% of soil N (Ns); according to No:Ns ratio. N-NH 4 + was the predominant form of mineral N. The mineralized C differed significantly among ages (606 to 1,122 mg kg -1 C-CO 2 soil). The average potentially mineralizable C (C o) was 862 mg kg -1 C-CO 2 soil, representing 3.4% of soil organic C (Corg) according to the C o:Corg ratio. The rate and mineralization potential of C and N were not influenced by the age of the plantations. The pool of potentially mineralizable N could meet the N demand of eucalyptus in future rotations. Source

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