ABSTRACT This study aimed to evaluate the effect of water supply and sowing time on yield and yield components of two corn hybrids grown during offseason in the region of Dourados-MS, Brazil. The experimental design was randomized blocks in sub-divided plots, with four replications. In the main plot, two sowing dates were defined (2013 crop year: February 27 and March 27; and 2014 crop year: March 18 and April 5). In subplots, irrigation management systems were defined (irrigated and rainfed). Hybrids AS 1555 and AS 1590 were grown in the sub-plots. The parameters evaluated were plant height, ear insertion height, stem diameter, ear length and diameter, 100-grain weight, and grain yield. Regardless of irrigation and hybrid used, sowing time significantly affected corn yield, which responded to climate changes throughout crop cycle. Water supply increased corn yield, with the highest value being of 9338 kg ha-1 (156 bags ha-1) and obtained when irrigated AS 1555 hybrid was sown on February 27, 2013.

The crystallographic structural analysis of the magnetite of a steatite rock at 298 K, (saturation magnetization, σ = 95.0 J T-1 kg-1) showed two cubic networks and, below Verwey temperature (TV ca.120 K) a monoclinic structure, basing on their cell dimensions and different transitional behaviors when reducing the temperature. A monoclinic structure was identified from their cell dimensions and different transition behaviors when reducing the temperature. The average chemical formula of this almost stoichiometric magnetite was deduced from the chemical analysis, 298 K-Mössbauer and the structural refinement. The Rietveld fitting of the 298 K X-ray pattern is Fe 3 + Fe 0 . 95 3 + Fe 0 . 88 2 + Cr 0 . 04 3 + Al 0 . 04 3 + Mg 0 . 05 2 + Ni 0 . 02 2 + ⊗ 0 . 02 O 4, where [ ] and { } stand for cations in tetrahedral and octahedral coordination symmetries, respectively. The crystallographic structure below TV in this magnetite was observed from synchrotron X-ray diffraction data (XRD), collected at 15 K. It was identified three structures: two cubic (space group, Fd3m), with significantly different lattice parameters, and one monoclinic (P2/c).

Resumo Alumina é comumente utilizada em blindagens compostas. Apresenta baixa tenacidade à fratura e esta propriedade está relacionada à resistência a múltiplos disparos. Com o intuito de melhorar a durabilidade em campo uma alternativa seria utilizar cerâmicas multicamadas. Neste estudo foi avaliado o desempenho balístico de estruturas multicamadas à base de alumina/epóxi e o efeito da adição de fibra de vidro como material de reforço. Os resultados foram comparados com placas de alumina individual de mesma espessura total que os sistemas multicamadas. O desempenho balístico dos painéis em mosaico de Al2O3/Al foi avaliado por meio de ensaio balístico DOP (depth of penetration) com projétil 7,62 mm perfurante. Os resultados indicaram que as placas individuais apresentaram melhor desempenho. No caso das estruturas Al2O3/epóxi, a resistência balística diminuiu com a redução da espessura das lâminas de alumina e com o aumento da camada de epóxi. A fibra de vidro não apresentou efeito significativo no desempenho.

Abstract Alumina is commonly used in composite shields. It presents low fracture toughness and this property is related to resistance to multiple shots. In order to improve the lifetime in applications, an alternative would be the use of multilayer ceramics. This study evaluated the ballistic performance of multilayer alumina/epoxy structures and the effect of glass fiber as a reinforcing material. The results were compared to individual alumina plates of the same total thickness as multilayer systems. The ballistic performance of the Al2O3/Al mosaic panels was evaluated using a DOP (depth of penetration) ballistic test with the 7.62 mm armor-piercing projectile. The results indicated that the individual plate showed better performance. In the case of Al2O3/epoxy structures, the ballistic resistance decreased with the reduction of the thickness of the alumina layer and with the increase of the epoxy layer. The glass fiber showed no improvement in ballistic performance.

The oil from the macaúba (Acrocomia aculeata) fruit, a native palm in Brazil, has a real potential for the industrial production of biodiesel. This report describes an experimental work devoted to monitor the chemical behavior of the fatty acid methyl esters from oil of the macaúba fruit kernel and the leaching of metal elements into the biodiesel put in contact with the ASTM A283 grade C and API X65 carbon steels, used to build fuel storage tanks and biodiesel pipelines. The mean values of esters contents points that the analytical precision from atomic absorption measurements was not enough to support a statistically reliable interpretation of the chemical leaching of metals into the biodiesel; a more accurate set of data must be obtained with more sensitive chemical analytical techniques. From the Mössbauer data, the surface of the non - galvanized steels in contact with this biodiesel for up to 105 days tend to be somehow protected against most oxidative reactions even in direct contact with air, although few amount magnetite (Fe3O4) was detected.

Resumo Neste trabalho investigaram-se cerâmicas quimicamente ligadas com quatro resíduos industriais: areia de fundição, casca cerâmica, escória de níquel e tijolo refratário MgO-C. O sistema foi composto (% em massa) por 17% de fosfato monopotássico, 12% de magnésia cáustica e 71% de resíduo. Foram empregados três tempos de cura (1, 7 e 28 dias). A fase K-estruvita foi identificada por difratometria de raios X e microscopia eletrônica de varredura. A resistência à compressão aumentou com o tempo de cura, variando entre 7 e 17 MPa. As formulações contendo casca de cerâmica e escória de níquel, no entanto, apresentaram os melhores resultados devido à maior densidade relativa apresentada e aos cristais em forma de placa nas microestruturas obtidas. Os resultados mostraram ser possível a incorporação de resíduos industriais para a obtenção de cerâmicas quimicamente ligadas usando-se a técnica de cimento ácido-base.

Abstract In this work, chemically bonded ceramics were studied from four different industrial waste: foundry sand, ceramic shell, nickel slag and MgO-C refractory brick. The system consisted of 17 wt% of monopotassium phosphate, 12 wt% of caustic magnesia and incorporating 71 wt% of waste. Three curing times were tested (1, 7 and 28 days). K-struvite crystalline phase was identified by X-ray diffraction and scanning electron microscopy. The compressive strength increased with the curing time, ranging from 7 to 17 MPa. The formulations containing ceramic shell and nickel slag, nevertheless, showed the best results because of the higher relative density presented and the plate-type crystals in the microstructures obtained. The results showed that it is possible to incorporate industrial waste to obtain chemically bonded ceramics using the acid-base cement technique.

A magnetic catalyst (sample MCat) consisting of KI supported on a mixture of silica and maghemite (γ-Fe2O3) was prepared and used in the transesterification reaction for the synthesis of biodiesel. The energy dispersive X-ray spectrum of the catalyst showed signals due to Si, Fe, K, and I. Powder X-ray diffraction data revealed the amorphous nature of the SiO2 and the duly impregnation of the support with KI. 57Fe Mössbauer spectroscopy and magnetization measurements confirmed the ferrimagnetic iron oxide in the catalyst to be maghemite. N2 adsorption-desorption data indicated that the silica is mesoporous with a specific area of 352 m2 g-1, enabling the impregnation of 40 and 11 wt.% of KI and maghemite, respectively, according to the chemical composition obtained by the X-ray fluorescence measurements. The MCat was found to be efficient in the transesterification reaction in the macaúba and soybean oils. The MCat was easily removed from the reaction medium, with a hand magnet, and efficiently reused for more four consecutive reaction cycles. The good catalytic activity along with its magnetic behavior, high chemical stability and recyclability make the MCat a suitable material for the green synthesis of biodiesel.

A review of most of the reported studies on the use of iron oxides as catalyst in specific processes, namely Haber-Bosch reaction, Fischer-Tropsch synthesis, Fenton oxidation and photolytic molecular splitting of water to produce gaseous hydrogen, was carried out. An essential overview is thus presented, intending to address the fundamental meaning, as well as the corresponding chemical mechanisms, and perspectives on new technological potentialities of natural and synthetic iron oxides, more specifically hematite (α-Fe2O3), goethite (α-FeOOH), magnetite (Fe3O4) and maghemite (γ-Fe2O3), in heterogeneous catalysis.

Coffee ringspot is a minor coffee disease caused by the nuclear type of Brevipalpus mite-transmitted virus, Coffee ringspot virus (CoRSV). Recently outbreaks of the disease in some growing regions of the state of Minas Gerais, Brazil, were registered with qualitative and quantitative yield losses. Coffea arabica was the only species registered as natural host. A survey was made on a germplasm collection of Coffea and related species kept at the Centro de Café "Alcides Carvalho", Instituto Agronômico, Campinas, state of São Paulo (SP), Brazil, to assess natural susceptibility of Coffee species, other than C. arabica and some interspecific hybrids of Coffea as well as other non-Coffea plant species to the Coffee ringspot virus (CoRSV). The following plants were found with ringspot symptoms on their leaves and/or fruits besides C. arabica L.: C. kapakata (IAC 4511), C. dewevrei cv. Excelsa, C. canephora cv. Robusta, hybrid derivative of the C. arabica × C. racemosa (IAC1195-5-6-2), C. arabica × C. dewerei (Piatã IAC 387), Híbrido de Timor CIFC 832/1 (derivative from a natural crossing between C. arabica × C. canephora) and C. racemosa. Also Psilanthus ebracteolatus, a species close to the genus Coffee was also found with ringspot lesions on their leaves. All these plants were also found infested by Brevipalpus mites identified as B. phoenicis. Infection of these plants by CoRSV was confirmed by the observation of characteristic cytopathic effects in the tissues of the lesion and by RT-PCR using a pair of primer specific for CoRSV. Only with C. racemosa RT-PCR failed to amplify the CoRSV genome. The susceptibility of P. ebracteolatus to CoRSV adds new dimension regarding its controversial taxonomic position.

In this work is evaluated the performance of etched fiber Bragg gratings, assembled in different configurations to operate as a refractometric sensor, in the analysis of water-ethanol mixtures. Two fiber Bragg gratings operating close to 1300 nm and 1500 nm were wet-etched and employed in the sensor design. Four configurations for the refractometric sensor were studied, in dual-wavelength and single-wavelength operation modes, and at two sample temperatures. Calibration curves were determined for the range between 0.0 and 100.0 % v/v of water in ethanol, and the sensor performance for each configuration was analyzed by comparing its sensitivity, conformity, repeatability and combined uncertainty. The best results showed that the sensor can be used to measure the ethanol-water concentration with combined uncertainty of 2.8 % v/v for the range up to 80.0 % v/v of ethanol concentration and 7.0 % v/v of uncertainty for the range above 80.0 % v/v of ethanol concentration for the single-wavelength operation mode at two temperatures.

This work aimed at putting in evidence the influence of the pH on the chemical nature and properties of the synthesized magnetic nanocomposites. Saturation magnetization measurements evidenced a marked difference of the magnetic behavior of samples, depending on the final pH of the solution after reaction. Magnetite and maghemite in different proportions were the main magnetic iron oxides actually identified. Synthesis with final pH between 9.7-10.6 produced nearly pure magnetite with little or no other associated iron oxide. Under other synthetic conditions, goethite also appears in proportions that depended upon the pH of the synthesis medium.

Este trabalho aborda a influência do pH do meio de reação, no procedimento de revestimento de nanopartículas magnéticas de magnetita, preparadas por redução-precipitação de cloreto férrico. O material de partida foi parcialmente reduzido a sal ferroso, por reação com Na2SO3, antes da alcalinização, com amônia. As partículas foram revestidas, pelo método sol-gel, a partir de solução aquosa de amônia ou ácido clorídrico, para promover a hidrólise catalisada por base ou ácido, respectivamente. Os materiais, de óxidos de ferro e de nanopartículas magnéticas revestidas, assim produzidos, foram caracterizados por difração de raios X, método do pó, por infravermelho com transformada de Fourier e por potencial zeta para a determinação do pH do ponto isoelétrico (pH IEP). A diferença observada do pH IEP em solução de KCl para amostras de sílica pura (2,0), magnetita (5,0) e para a magnetita revestida por sílica (2,3) confirma que o processo de revestimento foi efetivo, uma vez que as propriedades de carga de superfície das nanopartículas magnéticas revestidas são próximas às da sílica pura, apesar de o espectro de infravermelho com transformada de Fourier não evidenciar padrões espectrais característicos de ligações Fe-O-Si.

This paper investigates the influence of reaction medium pH on silica-coating of magnetite nanoparticles. Magnetite nanoparticles were prepared by means of a reduction-precipitation method using ferric chloride as a starting material, which was partially reduced to ferrous salts by Na2SO3 before alkalinizing with ammonia. The particles were coated by sol-gel method with either ammonia or HCl aqueous solutions for either base- or acid-catalyzed hydrolysis, respectively. Powder X-ray diffraction, Fourier-transform infrared, and Zeta Potential were used for the characterization of oxides and of the coated magnetic nanoparticles. The observed difference of pH IEP in KCl solution for pure silica (2.0), magnetite (5.0), and silica-coated magnetite (2.3) samples confirms that the coating process was effective since the charge surface properties of coated magnetic nanoparticles are close to that of pure silica, even though the Fourier-transform infrared spectra did not evidence the formation of Fe-O-Si bonds.

RESUMO Ustilago operta, agente causal do carvão, constitui séria ameaça para a produção de sementes de braquiária. O objetivo do presente trabalho foi avaliar a incidência deste patógeno em sementes comerciais de Brachiaria spp. Foram analisados lotes de sementes de cultivares de B. brizantha, B. decumbens, B. humidicola e B. ruziziensis, produzidos em BA, GO, MG, MS, MT e SP, nas safras 20042005 e 2005-2006, e destinados ao comércio interno. Também foi verificada a ocorrência de carvão em alguns lotes de alta pureza, destinados à exportação. Para detecção do patógeno, foram analisadas 400 sementes/lote/safra, em quatro repetições de 100, as quais foram cortadas longitudinalmente e observadas sob lupa para a presença de massa pulverulenta negra, composta por estruturas do fungo. U. operta foi detectado em 32% e 28% dos lotes de sementes de braquiária produzidos em 2004-2005 e 2005-2006, respectivamente. Em 2004-2005, as maiores incidências de carvão nas sementes de ‘Marandu’ foram verificadas nos lotes produzidos em Barreiras, BA (7,3%) e Paraíso, MS (2,3%). Na safra seguinte, lotes de ‘Marandu’ produzidos em Rio Verde, GO, apresentaram a maior porcentagem de sementes com sinais de carvão. Sinais de carvão foram verificados nas sementes de ‘Xaráes’ produzidas em regiões de MG e MS, em ambas as safras (incidência ≤ 1%). Em um lote de ‘Basilisk’ (origem: Paraíso, MS, 2004-2005) constatou-se incidência de carvão nas sementes (1%), constituindo o primeiro registro da interação U. operta B. decumbens. O carvão não foi detectado em sementes de ‘Humidicola’ e ‘Ruziziensis’. A presença de U. operta em lotes de sementes de ‘Marandu’ com alta pureza foi confirmada.

ABSTRACT Ustilago operta, causal agent of smut, represents a serious risk to the seed production of brachyaria grass. The objective of this work was to evaluate the incidence of smut in commercial seeds of Brachiaria spp. seeds of cultivars of B. brizantha, B. decumbens, B. humidicola, andB. ruziziensis, destined for the internal market, produced in BA, GO, MG, MS, MT and SP, Brazil, during 2004–2005 and 2005–2006. The occurrence of smut in lots of high purity, destined for the external market, was also analyzed. After a longitudinal cut, 400 seeds/lot/harvest, divided in 4 repetitions of 100, were examined under a stereomicroscope for the presence of a black pulverulent mass, composed of fungal structures. The frequency of U. operta in lots produced in 2004–2005 and 2005–2005 was 32% and 28%, respectively. In the 2004–2005 harvest, the highest incidences of smut in Marandu seeds were observed in lots produced in Barreiras, BA (7.3%) and Paraíso, MS (2.3%). In the next harvest, the highest number of smut-contaminated seeds was detected in lots of Marandu seeds produced in Rio Verde, GO. Smut signals were detected in Xaraés seeds produced in regions of MG and MS (incidence ≤ 1%), in both harvests. In one lot of Basilisk (origin: Paraíso, MS, 2004–2005) there was observed an incidence of smut in seeds (1%). This constitutes the first report of the U. operta – B. decumbens interaction. The smut was not visualized in Humidicola and Ruziziensis seeds. The occurrence of U. operta in lots of high-purity Marandu seeds was confirmed.

A produção de pectinases de 40 isolados de Colletotrichum gloeosporioides, obtidos de Stylosanthes spp. em diferentes regiões produtoras, foi estimada por meio de difusão enzimática em meio específico e mensuração do halo de degradação de pectina. Em todos os isolados havia atividade pectinolítica, sendo divididos em cinco grupos distintos. Na maior parte dos isolados notou-se moderada atividade de pectinases. Em geral, isolados de Camapuã-MS tiveram menor diversidade genética para a produção de enzimas pécticas. Com base na atividade pectinolítica, isolados do patógeno foram selecionados e inoculados em genótipos de S. capitata (GC1081, GC1084, GC1086 e GC1094), S. scabra (GC1496) e S. macrocephala (GC1511), visando analisar a influência das pectinases na agressividade ao hospedeiro. Inicialmente, instalou-se ensaio de agressividade com os isolados CG656, CG657, CG687, CG706 e CG707, sendo constatada agressividade diferenciada apenas quando inoculados em S. scabra. Enquanto CG657, CG706 e CG707 foram os mais agressivos, CG656 foi o menos agressivo. Outro teste de agressividade avaliou os isolados CG768, CG769, CG772, CG775, CG779 e CG781. Estes se diferenciaram quanto à agressividade ao S. capitata (GC1081 e GC1094) e S. macrocephala (GC1511). Em geral, CG768 comportou-se como pouco agressivo, enquanto que CG772, CG775 e CG781 como os mais agressivos. Para ambos, nos ensaios de agressividade, não se evidenciou aumento da severidade da antracnose com o aumento da atividade pectinolítica. Nas condições analisadas, a agressividade de C. gloeosporioides ao estilosantes não foi influenciada pelas enzimas pécticas.

Pectinolytic activity of 40 isolates of Colletotrichum gloeosporioides obtained from Stylosanthes spp.lesions, in distinct producing regions, was estimated through the enzymatic diffusion in pectin-medium free of glucose, and measured by pectin degradation. All isolates showed pectinolytic activity, and were divided in five groups. Moderate production of pectic enzymes was evidenced in the majority of the isolates. In general, isolates from Camapua-MS presented low genetic diversity for the production of pectinases. Taking into account the activity of pectinases, isolates of the pathogen were selected and inoculated in S. capitata (GC1081, GC1084, GC1086 and GC1094), S. scabra (GC1496) and S. macrocephala (GC1511). Thus, the enzyme influence on aggressiveness to the host was evaluated. Initially, aggressiveness test was installed with the isolates CG656, CG657, CG687, CG706 and CG707. Differences in aggressiveness were observed only when the isolates were inoculated in S. scabra. The isolates CG657, CG706 and CG707 were the most aggressive, and CG656 was the least aggressive. Another aggressiveness test was established to evaluate the isolates CG768, CG769, CG772, CG775, CG779 and CG781. These isolates showed differences in their aggressiveness when inoculated in S. capitata (GC1081 and GC1094) and S. macrocephala (GC1511). In general, CG768 exhibited the lowest while, CG772, CG775 and CG781 the highest aggressiveness. In both aggressiveness tests, there were no evidences for a direct correlation of anthracnose increase in severity with the of the pectinolytic activity. For the conditions evaluated, the pectic enzymes did not influence the aggressiveness of C. gloeosporioides to the stylo.

In order to understand the genetic responses resulting from physiological changes that occur in plants displaying citrus variegated chlorosis (CVC) symptoms, we adopted a strategy of comparing two EST libraries from sweet orange [Citrus sinensis (L.) Osbeck]. One of them was prepared with plants showing typical CVC symptoms caused by Xylella fastidiosa and the other with non-inoculated plants. We obtained 15,944 ESTs by sequencing the two cDNA libraries. Using an in silico hybridization strategy, 37 genes were found to have significant variation at the transcriptional level. Within this subset, 21 were up-regulated and 16 were down-regulated in plants with CVC. The main functional categories of the down-regulated transcripts in plants with CVC were associated with metabolism, protein modification, energy and transport facilitation. The majority of the up-regulated transcripts were associated with metabolism and defense response. Some transcripts associated with adaptation to stress conditions were up-regulated in plants with CVC and could explain why plants remain alive even under severe water and nutritional stress. Others of the up-regulated transcripts are related to defense response suggesting that sweet orange plants activate their defense machinery. The genes associated with stress response might be expressed as part of a secondary response related to physiological alterations caused by the infection.

Leprosis, caused by Citrus leprosis virus, cytoplasmic type (CiLV-C), is the main viral disease in the Brazilian citrus industry. This occurs because of the widespread source of inoculum and the year-round presence of the vector, the tenuipalpid mite Brevipalpus phoenicis, in citrus plants. In addition, while some Citrus species are resistant to CiLV-C, C. sinensis, the main cultivated species in the country, is extremely susceptible to the disease. The main objective of this work was to identify genes in C. sinensis cv. Pêra plants that were differentially expressed after the host was challenged with CiLV-C. In order to accomplish that, cDNA libraries were constructed from healthy and CiLV-inoculated sweet orange leaves. Two hundred and fifty-four genes were found to differ significantly in terms of expression, with 193 of them induced and 61 repressed after inoculation. Here we discuss the possible roles of a sub-set of these genes involved in metabolism, energy, signaling and cell rescue, defense and virulence, and indicate which kind of response may take place in the initial steps of the disease. Although the symptoms induced by CiLV-C in its compatible interaction with sweet orange resemble those of hypersensitive response (HR) in incompatible interactions, our data indicate that, apparently, the manifestation of leprosis symptoms should not be considered HR.