Abstract The effect of synthesis parameters on the microstructural behavior and morphology during the yttrium oxide (Y2O3) formation is reported. Y2O3 crystals were produced by a modified sol-gel route assisted by polyvinyl alcohol solution varying the calcination temperature and solution pH. The crystalline phase formation was investigated using X-ray powder diffraction combined with the Rietveld refinement method. The microstructural properties were analyzed by using the Williamson-Hall formalism. The calcination temperature followed the thermal events observed in the differential thermal analysis combined with the thermogravimetric analysis of the precursor xerogel. It was seen that the combination of PVA and pH variation can be used to minimize the calcination time and temperature. The morphological analysis showed samples with different sizes and appearances depending on pH and calcination temperature. Therefore, it was shown that the parameters in the synthesis process can be used to tailor the properties of Y2O3, such as crystallite size, degree of structural ordering, and morphology, and consequently, improve the desired application. YO Y O (Y2O3 reported Y2O solgel sol gel Xray X ray method WilliamsonHall Williamson Hall formalism xerogel Therefore size ordering consequently application (Y2O

Resumo As interações entre fungos endofíticos (FEs) e suas plantas hospedeiras variam de positivas, neutras a negativas. Os resultados destas interações podem variar dependendo do órgão da planta hospedeira infectada. FEs isolados de folhas de algumas espécies de plantas têm potencial para serem usados como agentes inibidores da germinação de sementes e no controle de plantas invasoras. Os objetivos deste estudo foram identificar os FEs presentes nas folhas de Copaifera oblongifolia e avaliar o papel destes fungos na germinação das sementes e no desenvolvimento das plântulas. Um total de 11 espécies de FEs foi isolado das folhas de C. oblongifolia e identificado através da sequência dos espaçadores internos transcritos do DNA ribossomal nuclear. As espécies de FEs isoladas são generalistas e provavelmente devem ser transmitidas horizontalmente. Os resultados dos testes de germinação mostraram que filtrados destes isolados fúngicos podem afetar diferentemente a germinação das sementes e o desenvolvimento das plântulas de C. oblongifolia. As espécies Curvularia intermedia, Neofusicoccum parvum, Pseudofusicoccum stromaticum e Phomopsis sp. afetaram negativamente a germinação das sementes de C. oblongifolia. Dentre estas espécies devemos destacar que N. parvum reduziu a germinação e a sobrevivência das plântulas em 89 e 222%, respectivamente. Além disso, Cochiliobolus intermedius afetou negativamente o desenvolvimento das plântulas. Assim, o uso combinado de N. parvum e C. intermedius, ou de produtos do metabolismo destas espécies de fungos, têm potencial para serem usados no manejo de plantas invasoras.

Abstract Interactions between endophytic fungi (EFs) and their host plants range from positive to neutral to negative. The results of such interactions can vary depending on the organ of the infected host plant. EFs isolated from the leaves of some species of plants have potential for use as agents to inhibit seed germination and control invasive plants. The objectives of this study were to identify EFs present in the leaves of Copaifera oblongifolia and to evaluate the role of these fungi in seed germination and seedling development. A total of 11 species of EFs were isolated, which were identified using the internal transcribed spacers (ITS) sequence of the nuclear ribosomal DNA. The isolated species of EFs are generalists and probably are transmitted horizontally. Laboratory tests revealed that filtrates of these fungal isolates differently affect seed germination and seedling development of C. oblongifolia. The species Curvularia intermedia, Neofusicoccum parvum, Pseudofusicoccum stromaticum and Phomopsis sp. negatively affected seed germination, with N. parvum standing out for its negative effects, inhibiting seedling germination and survival in 89 and 222%, respectively. In addition, Cochliobolus intermedius negatively affected seedling development. Thus, the combined use of N. parvum and C. intermedius, or products from the metabolism of these microorganisms, in the control of invasive plants deserves attention from future studies.

Resumo Pó cerâmico de SrAl2O4:Eu3+,Dy3+ foi produzido pelo método sol-gel proteico, uma rota de sol-gel modificada que permite a formação do óxido em temperaturas mais baixas comparativamente a outros métodos. A sinterização a laser de CO2 foi utilizada como método para tratamento térmico, eficiente na redução dos íons trivalentes de európio das amostras dopadas. A análise térmica dos precursores, realizada por meio de análise térmica diferencial (DTA) e termogravimetria (TG), revelou que a cristalização da fase SrAl2O4 aconteceu em aproximadamente 1060 °C. Por difratometria de raios X verificou-se a formação de fases monoclínica e hexagonal nas amostras caracterizadas antes e após a sinterização. A técnica de espalhamento dinâmico de luz revelou a presença de partículas nanométricas, micrométricas e aglomerados de partículas, resultado este que foi confirmado por imagens de microscopia eletrônica de varredura. Micrografias da superfície de fratura de uma pastilha sinterizada a laser revelaram o alto grau de densificação possibilitado pelo tratamento térmico. Medidas de fotoluminescência revelaram que as amostras após a síntese e antes do tratamento térmico a laser apresentaram emissão com coloração avermelhada, composta de picos estreitos de emissão característicos do Eu3+ e com emissão mais intensa quando as amostras foram excitadas em 265 nm. O tratamento a laser promoveu a redução do Eu3+ para Eu2+ e este efeito foi confirmado pela presença de uma banda larga de emissão na região verde do espectro, com máximo de emissão obtido após excitação em 350 nm. O tempo de decaimento luminescente da amostra tratada termicamente chegou a alcançar aproximadamente 100 min. Por meio de medidas de fluorescência de raios X da frita adquirida e de DTA e TG da frita, do pigmento e de misturas entre os dois, foi possível observar boa compatibilidade em termos dos processos térmicos, o que apontou para um potencial uso do pigmento em placas de revestimento cerâmico.

Abstract Powder of Dy3+ co-doped SrAl2O4:Eu3+ was produced via proteic sol-gel method, a modified sol-gel route which allows the formation of oxides at lower temperatures than other methods. CO2 laser sintering was used as a method for heat treatment, effective in reducing trivalent europium ions in doped samples. Thermal analysis of the precursors, performed by TG and DTA, revealed that the crystallization of SrAl2O4 phase occurred at approximately 1060 °C. X-ray diffraction showed that the samples, before and after sintering, had monoclinic and hexagonal phases formation. DLS technique revealed the presence of nanosized and micrometric particles, and particle agglomerates, confirmed by SEM images. Micrographs of the fracture surface of a sintered pellet revealed a high degree of densification caused by heat treatment. Photoluminescence measurements showed that the samples after synthesis and before heat treatment with laser had reddish emission, composed of characteristic narrow emission lines from Eu3+ and more intense emission when the samples were excited at 265 nm. The laser treatment promoted the reduction of Eu3+ to Eu2+ and this effect was confirmed by the presence of a wide emission band in the green region of the spectrum with a maximum emission obtained after excitation at 350 nm. The luminescent decay time of the thermally treated sample was approximately 100 min. Via XRF measurements of acquired frit and DTA and TG of the frit, pigment and mixtures of both, it was noticed good compatibility in terms of thermal processes, that indicated that the pigment has a potential to be used in ceramic tiles.

The effectiveness of four systemic fungicides (azoxystrobin, 150 g·ha-1; dimethomorph, 225 g·ha-1; fosetil-Al, 2 kg·ha-1; y triforine, 285 g·ha-1) for downy mildew control (Pseudoperonospora cubensis) was evaluated in cantaloupe melon early sown at the Yucatan State, Mexico. The fungicides were sprayed at 36, 52 and 67 days after transplant (dat), and the disease intensity at 43, 60, and 75 dat, yield components, and fruit soluble solids concentration, were assessed. No significant difference on disease incidence (5.6-12.5%) was observed at 43 dat. Disease incidence (73.3%) on dimetomorph treated plots was significantly lower than in the control plots at 60 dat. Disease incidence reached 100% in all treatments in the last recorded date, 75 dat. Disease severity, measured with Horsfall-Barratt scale, was significantly lower in dimetomorph treated plants in the three dates evaluated. The final disease severity was significantly lower in plants treated with dimetomorph or fosetil-Al, in which 85 and 75%, respectively, less area under the disease progress curve (AUDPC) was observed than in the control plants. These fungicides also induced the highest number of fruits per plot, mean individual fruit weight, and total fruit yield. The fruit soluble solids concentrations were not significantly different among treatments. A linear negative effect (r²=0.84) of the disease severity (AUDPC) on the total fruit yield was found.

En siembras tempranas de melón cultivado en Yucatán se evaluó la efectividad de cuatro fungicidas sistémicos (azoxystrobin, 150 g·ha-1; dimetomorf, 225 g·ha-1; fosetil-Al, 2 kg·ha-1; y triforine, 285 g·ha-1) en el control del mildiú velloso (Pseudoperonospora cubensis Berk. & Curt.). Las aplicaciones de los fungicidas se realizaron a los 36, 52 y 67 días después del trasplante (ddt), y se llevaron a cabo tres evaluaciones (43, 60 y 75 ddt) de intensidad de la enfermedad, componentes del rendimiento y concentración de sólidos solubles en los frutos. En la evaluación a los 43 ddt no se observaron diferencias significativas en la incidencia de la enfermedad (5.6-12.5%). En la evaluación a los 60 ddt la incidencia de la enfermedad (73.3%) en las parcelas tratadas con dimetomorf fue significativamente menor al testigo. En la última evaluación, 75 ddt, la incidencia de la enfermedad alcanzó 100% en todos los tratamientos. La severidad de la enfermedad en las tres evaluaciones, medida en la escala Horsfall-Barratt, fue significativamente menor en las plantas tratadas con dimetomorf. La severidad final fue significativamente menor en las plantas tratadas con dimetomorf y fosetil-Al, las cuales presentaron 85 y 75% menor área bajo la curva del progreso de la enfermedad que el testigo, respectivamente. Estos tratamientos también presentaron mayor número de frutos por parcela, peso promedio de los frutos y rendimiento total. La concentración de sólidos solubles en los frutos no varió significativamente entre tratamientos. Se determinó que la severidad de la enfermedad (ABCPE) afecta negativamente el rendimiento de una manera lineal (r²=0.84).