Covers of generalized quadrangles

We solve a problem posed by Cardinali and Sastry (Elliptic ovoids and their rosettes in a classical generalized quadrangle of even order. Proc. Indian Acad. Sci. Math. Sci. 126 (2016), 591-612) about factorization of 2-covers of finite classical generalized quadrangles (GQs). To that end, we develop a general theory of cover factorization for GQs, and in particular, we study the isomorphism problem for such covers and associated geometries. As a byproduct, we obtain new results about semi-partial geometries coming from theta-covers, and consider related problems

Sistemas de información geográfica aplicados a estudios de corrosión atmosférica

Los Sistemas de Información Geográfica (SIG´s) han dado cuenta del manejo y registro de inventarios geográficos así como del monitoreo y análisis de variables ambientales. De ahí que sea posible usarlos, apoyados en análisis espaciales y estadísticos, en el estudio de la corrosión y su influencia sobre sistemas como el energético nacional. En este trabajo se muestra cómo, a partir de muestreos puntuales de los diferentes agentes corrosivos en zonas geográficas estratégicas, pueden establecerse tendencias del comportamiento espacial de dichos elementos, generándose mapas que permiten hacer estimaciones acerca de la vida útil de los materiales en distintas zonas del país

Microbiology and Nitrogen Cycle in the Benthic Sediments of a Glacial Oligotrophic Deep Andean Lake as Analog of Ancient Martian Lake-Beds

Potential benthic habitats of early Mars lakes, probably oligotrophic, could range from hydrothermal to cold sediments. Dynamic processes in the water column (such as turbidity or UV penetration) as well as in the benthic bed (temperature gradients, turbation, or sedimentation rate) contribute to supply nutrients to a potential microbial ecosystem. High altitude, oligotrophic, and deep Andean lakes with active deglaciation processes and recent or past volcanic activity are natural models to assess the feasibility of life in other planetary lake/ocean environments and to develop technology for their exploration. We sampled the benthic sediments (down to 269 m depth) of the oligotrophic lake Laguna Negra (Central Andes, Chile) to investigate its ecosystem through geochemical, biomarker profiling, and molecular ecology studies. The chemistry of the benthic water was similar to the rest of the water column, except for variable amounts of ammonium (up to 2.8 ppm) and nitrate (up to 0.13 ppm). A life detector chip with a 300-antibody microarray revealed the presence of biomass in the form of exopolysaccharides and other microbial markers associated to several phylogenetic groups and potential microaerobic and anaerobic metabolisms such as nitrate reduction. DNA analyses showed that 27% of the Archaea sequences corresponded to a group of ammonia-oxidizing archaea (AOA) similar (97%) to Nitrosopumilus spp. and Nitrosoarchaeum spp. (Thaumarchaeota), and 4% of Bacteria sequences to nitrite-oxidizing bacteria from the Nitrospira genus, suggesting a coupling between ammonia and nitrite oxidation. Mesocosm experiments with the specific AOA inhibitor 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) demonstrated an AOA-associated ammonia oxidation activity with the simultaneous accumulation of nitrate and sulfate. The results showed a rich benthic microbial community dominated by microaerobic and anaerobic metabolisms thriving under aphotic, low temperature (4°C), and relatively high pressure, that might be a suitable terrestrial analog of other planetary settings

Decolourisation and Biodegradation of Textile Di-azo Dye Congo Red by Chryseobacterium geocarposphaerae DD3

In the present study, Chryseobacterium geocarposphaerae DD3 isolated from textile industry dye effluent in West Bengal, India, displayed significant tolerance to sulfonated di-azo dye Congo red (CR), up to 500 ppm. The optimum decolourisation revealed that C. geocarposphaerae DD3 was capable of 96.52% decolourisation of 0.2 g L−1 CR within 12 h of treatment in the presence of 5 g L−1 glucose as supplementary carbon source. Biodegradation analysis of decolourised CR containing water was investigated by FTIR, MS and 1H NMR, which confirmed the absence of azo bond as well as the toxic aromatic amines. Further, phytotoxicity analysis was performed to assess the toxicity of CR before and after bacterial treatment. Growth indexes of Vigna radiata L. seed confirmed that the biodegraded water was non-phytotoxic in comparison to the control CR solution. Multivariate analyses confirmed the same, showing significant differences between measured plant health indicators for CR solutions, whereas no significant differences were found between distilled and treated water. This study is novel as it is the first report of dye degradation by C. geocarposphaerae and may lead to a sustainable way of treating dye-contaminated water in the near future

Sistemas de información geográfica aplicados a estudios de corrosión atmosférica.

Geographic Information Systems (GIS´s) has been used for the register and management of geographic data, as well as for monitoring and analysis of environmental parameters. Hence, it is possible to employ GIS, based on spatial and statistical analysis, for the study of corrosion and its effect on systems such as electric power national system. In this work it is shown how, from discrete sampling of the different corrosive agents in strategic sites, it is possible to obtain trends for the spatial behavior of those variables, to finally generate maps which allow making assessments about life-in-service of materials in different zones of the country.Los Sistemas de Información Geográfica (SIG´s) han dado cuenta del manejo y registro de inventarios geográficos así como del monitoreo y análisis de variables ambientales. De ahí que sea posible usarlos, apoyados en análisis espaciales y estadísticos, en el estudio de la corrosión y su influencia sobre sistemas como el energético nacional. En este trabajo se muestra cómo, a partir de muestreos puntuales de los diferentes agentes corrosivos en zonas geográficas estratégicas, pueden establecerse tendencias del comportamiento espacial de dichos elementos, generándose mapas que permiten hacer estimaciones acerca de la vida útil de los materiales en distintas zonas del país

Stress Dependent Biofilm Formation and Bioactive Melanin Pigment Production by a Thermophilic <i>Bacillus</i> Species from Chilean Hot Spring

Thermophilic bacteria able to survive extreme temperature stress are of great biotechnological interest due to their extracellular production of bioactive molecules as a part of a survival strategy, or by intracellular modifications. In the present study, thermophilic Bacillus haynesii CamB6, isolated from a Chilean hot spring, was studied for the formation of different stress response molecules. The polymeric pigment produced by the bacterial strain was characterized by different physicochemical techniques. On exposure to ranges of temperature (50–60 °C), pH (5.0–7.0), and sources of nitrogen and carbon (1–5 g·L−1), the bacteria responded with a biofilm network formation in a hydrophobic polystyrene surface. Biofilm formation under fed-batch conditions was also statistically validated. The bacteria showed a planktonic pellicle network formation in the presence of induced hypoxia and salinity stress (19.45 g·L−1) under static conditions. Salinity stress also resulted in the intracellular response of brown pigment production. The pigment was structurally and functionally characterized by UV-Vis absorbance and the presence of different characteristic peaks via FTIR analysis (bacterial pyomelanin fingerprints) were assessed. A high thermal stability and TGA profile indicated the brown pigment was a probable pyomelanin candidate. Micropyrolysis (Py-GC/MS) showed that isoprene, pyrrole, benzene, pyridine, and their derivatives were the major components detected. In addition, acetic acid, indole, phenol, and its derivatives were observed. The absence of sulfocompounds in the pyrolyzed products agreed with those reported in the literature for pyomelanin. The pigment surface morphology was analyzed via SEM, and the elemental composition via EDS also demonstrated the similarity of the brown pigment to that of the melanin family. The pyomelanin pigment was observed to be bioactive with promising antioxidant capacity (H2O2, Fe2+) compared to the standard antioxidant molecules. In conclusion, B. haynesii CamB6 demonstrated the formation of several biomolecules as a stress response mechanism that is bioactive, showing its probable biotechnological applications in future

Compostaje de residuos vitivinícolas. Avanzando hacia una industria circular

En una vitivinicultura circular, mediante el compostaje de materia orgánica, se conservan los nutrientes, la estructura y la diversidad del suelo del viñedo, y se valorizan los residuos industriales. En este contexto, el objetivo de este trabajo fue optimizar la eficiencia y calidad de la producción de compost. En un proyecto colaborativo entre 3 bodegas, se evaluó un compostaje de volteo tradicional en conjunto con una tecnología de cubierta permeable, sustratos alternativos como residuos de tomate y manzana, así como estiércol y urea como fuente adicional de nitrógeno, y además el efecto de organismos comerciales como aceleradores del compostaje de residuos vitivinícolas. El uso de una cubierta permeable redujo el requerimiento de agua en un 17%. La adición de orujo de manzana y tomate generó un compost más estable y rico en N, en comparación con los sistemas que utilizan solo orujo. La aplicación de estiércol avícola y urea aumentó principalmente en el contenido respectivo de P y N. La inoculación adicional con microorganismos comerciales no generó diferencias en el compost. En cuanto a las poblaciones de microorganismos naturales, no se encontraron diferencias entre los tratamientos en bacterias beneficiosas fijadoras de nitrógeno como Nitrospira y Nitrosomas

An Update of Knowledge of the Bacterial Assemblages Associated with the Mexican Caribbean Corals <i>Acropora palmata</i>, <i>Orbicella faveolata,</i> and <i>Porites porites</i>

In this study, the bacterial microbiota associated with apparently healthy corals of Acropora palmata, Orbicella faveolata, and Porites porites and the surrounding seawater and sediment were evaluated via the MiSeq Illumina sequencing of the V4 region of 16S rRNA at three reef sites in the Mexican Caribbean. Bacterial assemblages associated with apparently healthy corals and sediments showed no significant differences between sites. The colonies of A. palmata showed a dominance of families Amoebophilaceae, Spirochaetaceae, Myxococcaceae, and Cyclobacteriaceae. Meanwhile, the colonies of O. faveolata and P. porites revealed a high prevalence of the Rhodobacteraceae and Kiloniellaceae families. The families Rhodobacteraceae, Cryomorphaceae, Cyanobiaceae, and Flavobacteriaceae were predominant in seawater samples, while Pirellulaceae, Nitrosococcaceae, and Woeseiaceae were predominant in sediments. Variations in A. palmata bacterial assemblages were correlated with salinity, sea surface temperature, and depth. These variables, along with nitrate, phosphate, and ammonium concentrations, were also correlated with changes in the bacterial composition of P. porites, seawater, and sediments. However, none of the environmental variables were related to the bacterial taxa of O. faveolata. Aerobic chemoheterotrophy and fermentation, followed by nitrate reduction and ureolysis, were the metabolic functions with the highest occurrence in the bacterial assemblages associated with all substrates