Rice (Oryza sativa L.) is an important cereal crop in Venezuela and is planted on approximately 200,000 ha. Fungal diseases caused by the Helminthosporium complex of fungi are considered a major constraint to rice production. In 2005, a blotter method was used to identify fungi associated with rice seed. Seeds (150) of cv. INIA-017 were placed on a plate with moistened filter paper and incubated at 26 ± 2°C with a 12-h light/12-h dark cycle for 5 days until fungal sporulation. Single spores were transferred to 2% water agar (WA). Germinated spores were then transferred to potato dextrose agar (PDA), and resultant colonies were preserved until used. To induce sporulation, 4-mm-diameter discs were cut from 72-h-old cultures, transferred to WA, and incubated at 26 ± 2°C for 48 h (modified technique of Alcorn [1]). Discolored seed yielded isolates of Bipolaris oryzae (Berda de Haan) Shoemaker and Exserohilum rostratum (Drechs.) Leonard and Suggs (2). Pathogenicity tests were performed on 60-day-old rice plants of cv. Blue Bonnet 50. Four plants per pot were used for each isolate. Before inoculation, plants were placed in humidity chambers for 48 h. Spores were harvested from discs into a beaker containing 50 mL of a dilute gelatin solution (Gelatin Difco; 5 g/100 mL of sterile distilled water [SDW]). Spore suspensions were filtered through cheesecloth and adjusted to 7 × 104 spores per ml. The inoculated plants were placed in humidity chambers for 72 h. Control plants were sprayed with SDW. Inoculated plants were removed from humidity chambers and placed on a greenhouse bench. Plants inoculated with B. oryzae were symptomatic 5 days after inoculation; resultant lesions were red-brown with chlorotic borders. Lesions subsequently turned gray with reddish borders and were rhombic in shape. Plants inoculated with E. rotratum were symptomatic 7 days after inoculation with elliptical lesions that were orange-brown along venation. These lesions turned gray with reddish borders. Both fungi were reisolated from symptomatic leaf tissue. To our knowledge, this is the first report of E. rostratum from rice in Venezuela. References: (1) J. L. Alcorn. Mycotaxon. 17:1, 1983. (2) A. Sivanesam. Mycol. Pap. 158, 1987.

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BACKGROUND: Air pollution in big cities is becoming a global problem due to its negative consequences on human health and the ecosystem. Currently, some materials available promise successful gases pollutants removal, by reacting with them through photocatalysis when sunlight irradiates them. The most studied and applied material is TiO 2 ; due to its chemical stability and availability, it is widely incorporated into cements, bricks, coatings, etc. RESULTS: In this study, powders of titanium dioxide were synthesized through the sol-gel method using tetraisopropoxide with and without organic acids. Their photocatalytic activity was determined by the colorimetric method, following the standard UNI-11259, and by the NO abatement test using the international standard ISO-22197-1. The results of the colorimetric test indicate that all the samples are photoactive according to the criteria stablished in the standard. Additionally, a similar photocatalytic performance was evidenced in the NO abatement tests for all the samples despite the differences in their particle sizes and in their crystalline phase distributions obtained without and with the different organic acids used in the synthesis process.CONCLUSION: The particles synthesized show that the use of organic acids influences the decrease in particle size; moreover, in the case of citric acid, a favourable effect on the appearance of the rutile phase is perceived. All the samples were photoactive and their photocatalytic performance, evaluated under a NO atmosphere, were not negatively affected by the largest particle size (150 nm) nor by the rutile phase content (42 wt.%).

RESUMENMediante la tecnología de proyección térmica por combustión oxiacetilénica se aplicaron sobre sustratos de acero al carbono AISI-SAE 1020 recubrimientos cerámicos a partir de residuos de catalizadores utilizados en procesos de refinación en la industria del petróleo. La adherencia y la dureza de los recubrimientos fueron evaluadas según las normas C633-01(2008) y ASTM C1327-08 respectivamente, con valores de adhesión que oscilan entre 2,9 y 17,7 MPa y valores de microdureza Vickers entre 5,4 y 8 GPa.Los resultados obtenidos permiten visualizar su posible aplicación industrial en componentes que requieran resistencia al desgaste, a las altas temperaturas o al choque térmico, a un costo menor que los elaborados con materias primas comerciales, debido a la re-utilización de los residuos sólidos en la elaboración de los recubrimientos y generando valor agregado como solución tecnológica al impacto ambientalmente negativo que generan los residuos de los catalizadores. Palabras claves:Recubrimientos cerámicos, proyección térmica, residuos de refinación. ABSTRACTCeramic coatings were elaborated onto carbon steel substrates by oxy-fuel thermal spraying process from catalysts waste used in petroleum refining. The adhesion and micro-hardness Vickers were evaluated according to ASTM C633-01(2008) and ASTM C1327-08 standards respectively, with adhesion values varying between 2,9 and 17,7 MPa and values of microhardness Vickers between 5,4 and 8 GPa. The results obtained indicate that these coatings could be used in industrial applications, mainly in components requiring resistance to wear and thermal shock or high temperatures, at a low cost due to reuse of solid waste as raw materials in the production of coatings, and giving a technological solution to environment problems produced by these catalysts waste.

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