Influence of cerium (IV) ions on the mechanism of organosilane polymerization and on the improvement of its barrier properties

In this work, the effect of cerium (IV) ammonium nitrate (CAN) addition on the polymerization of bis-[triethoxysilyl]ethane (BTSE) film applied on carbon steel was studied. The electrochemical characterization of the films was carried out in 0.1 mol L(-1) NaCl solution by open-circuit potential measurements, anodic and cathodic polarization curves and electrochemical impedance spectroscopy (EIS). Morphological and chemical characterization were performed by atomic force microscopy (AFM), contact angle measurements, infrared-spectroscopy, nuclear magnetic resonance and thermogravimetric analysis. The results have clearly shown the improvement on the protective properties of the Ce(4+) modified film as a consequence of the formation of a more uniform and densely reticulated silane film. A mechanism is proposed to explain the accelerating role of Ce(4+) ions on the cross-linking of the silane layer. (C) 2008 Elsevier Ltd. All rights reserved.

Brachiaria species affecting soil nitrification

O processo de nitrificação pode conduzir a perdas substanciais do nitrogênio aplicado por meio da lixiviação de nitrato e emissão de N2O. A regulação da nitrificação pode ser uma estratégia para melhorar a recuperação do N e aumentar sua eficiência agronômica. O objetivo deste trabalho foi avaliar a habilidade de espécies do gênero Brachiaria de inibir o processo de nitrificação no solo. O experimento foi realizado em casa de vegetação, em vasos contendo 10 dm³ de um Latossolo Vermelho. Os tratamentos foram constituídos do cultivo de três espécies forrageiras (Brachiaria brizantha, B. ruziziensis e B. decumbens) e quatro doses de N (0, 100, 200 e 300 mg/vaso), além da testemunha (sem a presença das forrageiras). Na ausência do cultivo de forrageiras, todos os níveis de adubação nitrogenada proporcionaram maior teor de N-NO3- no solo, reflexo da nitrificação. A mineralização da matéria orgânica supriu boa parte da necessidade de absorção de N pelas forrageiras estudadas, e a B. brizantha alterou a nitrificação em sua rizosfera, no entanto esse efeito não foi de magnitude suficiente para alterar o teor de N-NH4+ presente no volume total de solo do vaso.

Produção e qualidade do milheto semeado em duas épocas e adubado com nitrogênio

O trabalho foi conduzido na FCAV-UNESP, câmpus de Jaboticabal, com o objetivo de avaliar as características fisiológicas de crescimento, produção de matéria seca (MS) e teores de proteína bruta (PB), fibra em detergente ácido (FDA) e digestibilidade in vitro da matéria seca (DIVMS) de dois genótipos de milheto (Pennisetum americanum) cultivar Comum e CMS 02/Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), semeados em duas épocas (23/11/94 e 10/3/95) e submetidos a quatro doses de N (0; 75; 150 e 225 kg ha-1). O delineamento experimental adotado foi o de blocos ao acaso, com parcelas subdivididas, e três repetições. Na primeira época de semeadura, a cv. Comum apresentou produção de MS total significativamente superior (6.995 kg ha-1) à do genótipo CMS 02 (6.177 kg ha-1), e a aplicação de 150 kg ha-1 foi a dose mais adequada nesse período. Na segunda época de semeadura, a produção de MS total dos genótipos foi, em média, de 2.799 kg ha-1, e a adubação nitrogenada não revelou efeito significativo. Plantas da primeira época de semeadura apresentaram, nos dois primeiros cortes, alta produção de folhas, cujos teores de PB foram superiores a 20%, e os valores de DIVMS em torno de 70%.

Épocas de aplicação de nitrogênio para híbridos de mamona no sistema plantio direto em safrinha

The castor bean cultivation has a high demand for nitrogen, in addition, the efficiency of nitrogen fertilization in most cases is low, so that this essential nutrient is provided at the appropriate time. The objective was to study the time nitrogen application in castor bean hybrids under no-till system in off-season. The experiment was carried out in an experimental area located in Botucatu, São Paulo State, Brazil, for two growing off-seasons (2006 and 2007). The experimental design was a randomized block in split plot design, with four replications. The plots were constituted by two castor bean hybrids (Lyra/Savana in 2006 and Lyra/Sara in 2007). Six combination of times out rates (0-0, 0-100, 100-0, 30-70, 70-30, 50-50 kg ha-1 of N) side dressing nitrogen fertilization constituted the subplots. The N source used was ammonium nitrate, applied 20 days after emergence and 40 days after emergence. Measurements were carried out: dry matter production of shoots, nitrate and ammonium leaf, leaf analysis, yield components and nitrogen factor utilization. The highest grain yield was obtained to the hybrid Lyra with nitrogen fertilization. In 2006 the highest nitrogen utilization factor to the hybrid Lyra was obtained with the form 70-30 and in the 2007 with 50-50.

Fluorapatite solubilization by Aspergillus niger in vinasse medium

Fluorapatite solubilization by Aspergillus niger using diluted vinasse at a relative density of 45° Brix may be an alternative to the usual processes for obtaining soluble phosphate. After 13 days of culture, a production of 1.2g l-1 soluble phosphate was obtained for 5g l-1 fluorapatite added to the vinasse, as well as production of 11 gl-1 dry mycelial mass and a substantial reduction of the polluting components of the medium, i.e. a 78 and 94% reduction of total and reducing sugars, respectively, and a 48 and 80% reduction of total and soluble solids, respectively. In less diluted medium, increased sugar content led to a greater production of dry mass but also to a reduction of soluble phosphate content. When fluorapatite concentration in vinasse was increased from 5.0 to 7.5 or 10.0 g l-1, soluble phosphate accumulation increased by 0.28 and 0.15 g l-1, respectively. Addition of ammonium nitrate or rotary shaking of the culture mixture did not lead to the production of larger amounts of soluble phosphate than obtained in the absence of these factors. © 1990.

Control of amylase production and growth characteristics of Aspergillus ochraceus

The growth and the extracellular amylase production by Aspergillus ochraceus were studied in a stationary culture medium. Maximum growth rate of this fungus was found after 5 days of incubation at 30° C, but maximum amylase production was obtained after 2 days. The highest amylase production were attained with lactose, maltose, xylose and starch as carbon sources. The extracellular amylase production and mycelial growth were influenced by the concentration of starch. Other carbohydrates supported growth but did not induce amylase synthesis and glucose repressed it, indicating catabolite repression in this microorganism. The presence of both mechanisms of induction and repression suggests that at least these multiple forms of regulation are present in A. ochraceus. Of the nitrogen sources tested, casaminoacids, ammonium nitrate and sodium nitrate stimulated the highest yield of amylase. Optimal amylase production was obtained at pH 5.0, but enzyme activity was found only in the 4.0-6.0 pH range. These results were probably due to the inhibitory effect of NH 4 +-N in the culture medium.

Mitigation of N2O emissions from grassland by nitrification inhibitor and actilith F2 applied with fertilizer and cattle slurry

Nitrous oxide (N2O) is involved in both ozone destruction and global warming. In agricultural soils it is produced by nitrification and denitrification mainly after fertilization. Nitrification inhibitors have been proposed as one of the management tools for the reduction of the potential hazards of fertilizer-derived N2O. Addition of nitrification inhibitors to fertilizers maintains soil N in ammonium form, thereby gaseous N losses by nitrification and denitrification are less likely to occur and there is increased N utilization by the sward. We present a study aimed to evaluate the effectiveness of the nitrification inhibitor dicyandiamide (DCD) and of the slurry additive Actilith F2 on N2O emissions following application of calcium ammonium nitrate or cattle slurry to a mixed clover/ryegrass sward in the Basque Country. The results indicate that large differences in N2O emission occur depending on fertilizer type and the presence or absence of a nitrification inhibitor. There is considerable scope for immediate reduction of emissions by applying DCD with calcium ammonium nitrate or cattle slurry. DCD, applied at 25 kg ha-1, reduced the amount of N lost as N2O by 60% and 42% when applied with cattle slurry and calcium ammonium nitrate, respectively. Actilith F2 did not reduce N2O emissions and it produced a long lasting mineralization of previously immobilized added N.

Produção de Brachiaria brizantha e Panicum maximum com milho e adubação nitrogenada

In places characterized with high temperatures and rain occurrence in great intensity in the summer, but with dry winter, the major limitations for the sustainability of no tillage systems are low production of straw during fall-spring period and the fast decomposition during the rain season. To try to solve the problem, intercropped cultures of grains with forage species has presented reliable results; because offer vegetal covering to the next sowing, giving sustainability to the no tillage system. However, being a recent technology, its needed further studies in different areas involved for this system of production. Thus, this study had the objective 1) to evaluate the production of corn grain at different periods of intercropping with Brachiaria brizantha and Panicum maximum in no tillage system, and 2) aimed to evaluate the performance of forage at different periods of intercropping and the responses to nitrogen fertilization after the harvest of the corn, assessing mass productivity and quality. The experiment was carried out at the Lageado experimental farm, School of Agricultural Sciences, Botucatu campus belonged to São Paulo State University (UNESP) in structuralized Red Nitosol (Afisol). The experimental design was randomized blocks with four replications. The treatments were composed for four systems of no tillage involving corn: 1) single corn; 2) corn with Brachiaria brizantha cv. Marandu intercropped in the sowing; 3) corn with Brachiaria brizantha cv. Marandu intercropped with the fertilization of covering; 4) corn with Panicum maximum cv. Mombaça intercropped in the sowing and 5) corn with Panicum maximum cv. Mombaça intercropped with the fertilization of covering. After the harvest of the corn, it was applied, in equivalent quantities of nitrogen, ammonium nitrate in covering in doses of 0, 30, 60 and 120 kg ha-1, determining the forage mass productivity and quality. The simultaneous tillage of corn with P. maximum cv. Mombaça in the sowing compromises the grain productivity. When sowed in intercropping, B. brizantha presents a fiber concentration reduction and greater TDN concentration during the fall-spring period. Regarding benefits of intercropped cultures seeking to use in systems of production like agriculture-pasture integration, the best intercropping to be utilized is corn sown simultaneously with B. brizantha cv. Marandu.

Utilização de nitrato de amônio e de uréia como fontes de nitrogênio na micropropagação de amoreira-preta

The high cost allied to the difficulty in the acquisition of the ammonium nitrate has been taking the accomplishment of works looking for an alternative for the substitution of this source of nitrogen. It was aimed at to study the technical viability of the substitution of the ammonium nitrate for urea, as source of nitrogen in the culture media for the blackberry in vitro cv. Tupy (Rubus sp). Nodal segments were used, already established in vitro, were inoculated in culture media MS and 50% MS, added of 1.0 mg. dm-3 of BAP, solidified with 6 g.dm-3 of agar, pH was adjusted for 5,8 and sterilized to 121 °C and 0,1 MPa for 20 min. The treatments consisted of the substitution of 0; 20; 40; 60; 80 and 100% of NH4NO3 for urea, and the swinging of nitrogen supplied by the culture media MS it was not altered. The explants were maintained by 60 days in growth room with temperature of 27±1 °C, photoperiod of 16 h and luminous intensity of 32 mmol m'2 s'1. The experiment was arranged in a completely randomized design, in factorial (6 x 2) using four repetitions with 16 plants each one. From the obtained results it can be concluded that the urea doesn't substitute NH 4NO3 in the culture media MS as nitrogen source in the culture vitro of blackberry.

Diagnóstico da qualidade da água na microbacia do córrego recanto, em americana, no estado de São Paulo

The environmental degradation observed in the Piracicaba, Capivari and Jundiaí watershed has been one of the principal preoccupations of the environmental agencies in the state of São Paulo, Brazil. In this context, there is inserted the Americana county which is cut by streams of unsuitable quality for the human consumption and other uses. The main goal of the present work was evaluated the water quality of the Recanto Creek, affluent of the Quilombo stream, at the Americana county, state of São Paulo, Brazil. The research was developed in the period from March of 2007 to March of 2008, when it was measured the flow and the following physical-chemical water quality parameters: temperature; turbidity; pH; dissolved oxygen (OD); phosphorus (P); ammonia nitrogen (NH 4); nitrate (NO 3); chemical demand of oxygen (DQO), besides total coliforms. The results demonstrated a variation of the flow from 34.3 to 375.2 L s -1, during the evaluated period. The parameters dissolved oxygen, phosphorus, ammonia nitrogen and nitrate presented values out of the limits recommended for rivers of class 3, like the Recanto Creek, suggesting water pollution due to the organic matter disposal.

Produção de rúcula e acúmulo de nitrato em função da adubação nitrogenada

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of mineralizer agents on the growth of crystalline CeO 2 nanospheres by the microwave-hydrothermal method

Cystalline ceria (CeO2) nanoparticles have been synthesized by a simple and fast microwave-assisted hydrothermal (MAH) under NaOH, KOH, and NH4OH mineralizers added to a cerium ammonium nitrate aqueous solution. The products were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transformed-IR and Raman spectroscopies. Rietveld refinement reveals a cubic structure with a space group Fm3m while infrared data showed few traces of nitrates. Field emission scanning microcopy (FEG-SEM) revealed a homogeneous size distribution of nanometric CeO2 nanoparticles. The MAH process in KOH and NaOH showed most effective to dehydrate the adsorbed water and decrease the hydrogen bonding effect leaving a weakly agglomerated powder of hydrated ceria. TEM micrographs of CeO2 synthesized under MAH conditions reveal particles well-dispersed and homogeneously distributed. The MAH enabled cerium oxide to be synthesized at 100 °C for 8 min. © 2012 Elsevier B.V. All rights reserved.

Produção e teores de nutrientes no capim braquiária adubado com nitrogênio e enxofre

Among the production factors, adequate fertilization is an important tool to raise the productivity of pastoral systems and consequently increase the share of Brazil in the supply chain of primary agricultural products at the global level. The objective of this study was to evaluate the interaction of nitrogen and sulfur fertilization in Brachiaria decumbens Stapf. The experiment in pots with Dystrophic Oxisol was evaluated in a completely randomized design with four replications in a 5 x 3 factorial arrangement, involving five N doses (0, 100, 200, 400, and 800 mg dm-3) in the form of ammonium nitrate and three S doses (0, 20 and 80 mg dm-3) in the form of calcium sulfate, with a total of 15 treatments. In the treatments with low S dose, calcium was provided as calcium chloride, to ensure a homogeneous Ca supply in all treatments. The results showed that the tiller production and dry weight of green leaves and of stems + sheaths and total dry weight were favored by the combination of N and S fertilizer, while the proportion of dry leaves was reduced. Nitrogen fertilization raised the N contents in green leaves and stems + sheaths and reduced K contents in fresh and dry leaves. The response to S rates in the N content of green leaves was quadratic.

Effect of soaking time on the photoluminescence properties of cerium oxide nanoparticles

The structural and photoluminescence properties at room temperature of CeO2 nanoparticles synthesized by a microwave-assisted hydrothermal method (MAH) under different soaking times on KOH mineralizer added to a cerium ammonium nitrate aqueous solution were undertaken. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) and photoluminescence (PL) measurements were employed. XRD revealed that the nanoparticles are free of secondary phases and crystallize in the cubic structure. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. The most intense PL emission was obtained for nanoparticles which represent a lower particle size. © 2013 Elsevier Ltd and Techna Group S.r.l.

Floral induction of mango 'Tommy Atkins' at submedio São Francisco Region, Brazil

Irregular production is a major problem in mango. In an attempt to overcome irregular bearing, effects of two antigibberellins on flowering were evaluated, uniconazole (0.25 g of active ingredient per meter of canopy tree diameter) and paclobutrazol (1.0 g of active ingredient per meter of canopy tree diameter). Treatments were applied as a soil drench using 2 L of solution per tree, in a commercial orchard of 'Tommy Atkins' mango. Treatments were applied after the second vegetative flush commenced, subsequent to pruning. Branch growth was evaluated every 30 days after treatment application up to a maximum period of 90 days. The flowering percentage was recorded at 130 days. Ammonium nitrate (NH4NO3) as a foliar spray (concentration of 0.75%) was applied five times at seven day intervals from 95 to 100 days after treatment application as a dormancy breaking treatment. It was found that both paclobutrazol (PBZ) and uniconazole (UCZ) significantly inhibited the development of vegetative growth compared to the control. Both treatments resulted in identical rates of flowering shoots, 87%; based on results, it can be concluded that the application of antigibberellins (PBZ and UCZ) inhibit vegetative development in mango 'Tommy Atkins', and promote high levels of flowering. Additional tests are being carried out in other farms to confirm these findings, for different cultivars and seasons. © ISHS 2013.