RESUMOJacaranda puberula, conhecida como caroba, é uma espécie que apresenta potencial de uso para recomposição de áreas degradadas, por possuir rápido crescimento, agressividade e adaptar-se bem a solos arenosos e argilosos, ocorrendo em capoeiras e capoeirões. Com o intuito de se obter informações sobre espécies potenciais para uso em restauração de ambiente ripário foi estudado, no viveiro da prefeitura do município de Colombo, o desenvolvimento de mudas de Jacaranda puberula submetidas a 0, 30, 50 e 70% de sombreamento. Foram avaliadas as seguintes variáveis: altura (60, 90 e 120 dias) e diâmetro de coleto (90 e 120 dias) de 21 mudas e, área foliar e peso seco da raiz e parte aérea de seis mudas por tratamento, no final do experimento (120 dias após a repicagem). Mudas expostas a pleno sol apresentaram alto índice de mortalidade, portanto esse tratamento não foi discutido e comparado aos demais. O tratamento com 30% de sombreamento mostrou-se superior aos demais em todas as variáveis, sendo recomendado para a produção de mudas de Jacaranda puberula nas condições testadas. Já as menores médias das variáveis analisadas foram obtidas aos 120 dias para o sombreamento de 70%, indicando que esse tratamento não é recomendável para a produção de mudas dessa espécie em viveiro. A melhor condição para a introdução dessa espécie em uma área a ser recuperada é em clareiras (30 a 50% de sombreamento), uma vez que, na naturezas, também pode ser observado que a sua ocorrência em geral não é a pleno sol.Palavras-chave: sombreamento; produção de mudas; floresta ripária. ABSTRACTJacaranda puberula, known as caroba, is a species that presents potential use for the recovery of degraded areas, since it possesses fast growth and adapts well to sandy and loamy soils. It presents great aggressiveness in secondary forests and it can be used as urban tree because it produces beautiful lilac flowers. With the intention of obtaining information about potential species for use in recovery of riparian forest, were tested in the nursery of the city hall of the municipal district of Colombo, the development of seedlings of Jacaranda puberula submitted at 30, 50 and 70% of shading. There were used 40 seedlings by treatment and there were evaluated the following parameters: height (60, 90 and 120 days) and diameter (90 and 120 days) of all seedlings, leaf area and root and shoot dry weight of 6 seedlings per treatment. The largest averages of the analyzed variables were obtained for the 30% shading, except for root dry weight. The seedlings exposed to full sun presented high mortality rate and was not compared to the others. The smallest averages of the analyzed variables, except for height, were observed for the shading of 70%, indicating that this treatment is not advisable for the production of seedlings of this species in nursery. The best condition for planting the seedlings appears to be in open areas with shading of 30 to 50%, since its natural occurrence is not at full exposure.

The great interest in the study of diamond-like carbon films (a-C:H) is justified by its mechanical and tribological properties. However, the high internal stress of the film results in its difficult adhesion to the metallic substrate, which can be solved by nitrogen incorporation in the a-C:H film, allowing a formed film of lower internal stress. The objective of this work is to evaluate the influence of flow (20, 30 and 40sccm), CH 4 /Ar ratio (90/10 and 70/30) and voltage (400, 500, 600 and 700 V) in the a-C:H formation. For the best condition of the film, we studied the effect of nitrogen incorporation in the hardness and wear resistance of the a-C:H(N), modifying the nitrogen percentage in the treatment at 10% to 60% N 2 . The treatments were carried out in the Ti 6 Al 4 V substrate by DC-PECVD for two hours. For good adhesion of the films on the substrate, a silicon interlayer must be produced. The increase in the voltage above 600 V increases the I D /I G and film thickness, causing its delamination, and the gas ratio did not influence the a-C:H characteristics. The a-C:H film deposited with 30 sccm, 90/10 and 500 V was characterized as a-C:H (hard), with properties such as the hardness of 17 GPa, 30% H, 39% sp 3 and I D /I G ratio of 0.58. Since nitrogen reduced the deposition rate, the total gas flow for the production of a-C:H(N) was performed with 40 sccm. The Raman spectra of a-C:H(N) films showed changes in D band intensity and displacement in relation to the nitrogen-free film spectrum, evidencing the incorporation of nitrogen in the film. The XPS analysis showed the linear increase of the nitrogen incorporation in the a-C:H(N) film with the increase of the amount of the N 2 gas in the treatment, which caused, in general, a decrease in the amount of C-C sp 3 bonding, increasing the adhesion of the film in the substrate and not necessarily the low wear resistance of the formed film.According to Robertson [4] the DLC film that presents hydrogen concentrations between 30 and 50% receives the nomenclature of hydrogenated amorphous carbon (a-C:H), and presents lower hardness and internal stress than ta-C, facilitating the adhesion process of the film in the metallic substrates. This occurs due to sp 2 bonds formed in detriment of sp 3 bonds.The DLC films have been used in a variety of applications due to their notable properties, as protective coatings against wear and corrosion, in optical windows (optical filters), data storage hard drives, high performance automotive parts, coatings for biomedical products and electromechanical microdevices [9][10][11][12].However, as reported by Chen et al [13] and confirmed by Cemin et al [11], the high intrinsic compressive stress of the film, the high variation of the elastic coefficient, the difference in thermal expansion and the low chemical affinity between DLC and substrate difficult the adhesion process of the DLC film mainly when deposited on metallic surfaces. Thus, the use of techniques as oxide layer removal and the use of film interlayer previously to ...

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In this paper, we present an alternative method to obtain thin films for coating protection on the surface of the AA2524-T3 Al-alloy by using the Layer-by-Layer (LbL) technique. The LbL films were fabricated by alternated immersion of the Al-alloy into a poly(styrene sulfonate) (PSS) and polyaniline nanoparticles (PAni-NPs) solutions, obtaining a PAni-NPs/PSS bilayer architecture. The LbL films were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), electrochemical and micro-abrasive wear tests. The results show that the number of bilayers promotes shifts to less negative potentials, indicating an optimized system, in which the best performance was observed for a 15-bilayer PAni/PSS LbL film. The pitting potential (E pit) values shifted 130 mV (from-610 mV to-480 mV) in comparing a bare Al-alloy. The predominantly wear mechanism for AA2524-T3 with PAni-NPs/PSS bilayers was scratching whereas for the bare material there was an equivalence between scratching and rolling mechanisms. The results proved that the incorporation of PAni-NPS by the LbL method may be propitious as protective coating against corrosion in AA2524-T3 alloy.

The aim of this work was to develop a device for plasma nitriding treatment and to verify its efficiency by using P20 steel. The influence of the main treatment parameters on the formed layer was verified through commissioning tests. The ionic nitriding treatments were performed in the surface of P20 steel with 80% N 2 and 20% H 2 , using a DC voltage source and a pulsed current DC voltage source. It was observed the formation of a heterogeneous layer with edge effect when the treatment was carried out with DC voltage source; the opposite effect was observed for the DC voltage source pulsed current. The results show that the voltage directly influences the treatment temperature while the pressure determines the formation of the cathodic sheath, acting on the uniformity of the cathodic luminescence and on the uniformity of the layer produced. It was possible to observe a relation of the temperature with the hardness, while the time was significant in the thickness of the formed layer. It is concluded that the built equipment showed efficiency for the purposes it was designed and its best performance occurred with the use of pulsed current DC voltage source.

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