Effect of the electric supply interruption on a microbial electrosynthesis system converting inorganic carbon into acetate.

Microbial electrosynthesis (MES) technology relies on the direct use of electrons to convert CO2 into long chain organic chemicals. Therefore, MES has been proposed to be coupled to the renewable electricity supply, mainly from solar and wind sources. However, those energies suffer fluctuations and interruptions of variable duration, which can have an adverse effect on MES performance. Such effects on MES has been evaluated for the first time under different interruptions time. H-cell-MES reactors were disconnected from power supply during 4, 6, 8, 16, 32 and 64 h. Interruptions affected the acetate production rate, causing a decrease of until 77% after 64 h off. However, after all the interruptions, the acetate production was restored, taking between 7 and 16 h for the reduction current to turn steady. Therefore, microbial community on MES proved to be resilient and able to recover the electro-autotrophic activity despite the duration of current supply interruptions.

Microbial communities from 20 different hydrogen-producing reactors studied by 454 pyrosequencing.

To provide new insight into the dark fermentation process, a multi-lateral study was performed to study the microbiology of 20 different lab-scale bioreactors operated in four different countries (Brazil, Chile, Mexico, and Uruguay). Samples (29) were collected from bioreactors with different configurations, operation conditions, and performances. The microbial communities were analyzed using 16S rRNA genes 454 pyrosequencing. The results showed notably uneven communities with a high predominance of a particular genus. The phylum Firmicutes predominated in most of the samples, but the phyla Thermotogae or Proteobacteria dominated in a few samples. Genera from three physiological groups were detected: high-yield hydrogen producers (Clostridium, Kosmotoga, Enterobacter), fermenters with low-hydrogen yield (mostly from Veillonelaceae), and competitors (Lactobacillus). Inocula, reactor configurations, and substrates influence the microbial communities. This is the first joint effort that evaluates hydrogen-producing reactors and operational conditions from different countries and contributes to understand the dark fermentation process.

Improvement of hydrogen production via ethanol-type fermentation in an anaerobic down-flow structured bed reactor.

Although a novel anaerobic down-flow structured bed reactor has shown feasibility and stable performance for a long-term compared to other anaerobic fixed bed systems for continuous hydrogen production, the volumetric rates and yields have so far been too low. In order to improve the performance, an operation strategy was applied by organic loading rate (OLR) variation (12-96 g COD L(-1) d(-1)). Different volumetric hydrogen rates, and yields at the same OLR indicated that the system was mainly driven by the specific organic load (SOL). When SOL was kept between 3.8 and 6.2 g sucrose g(-1) VSS d(-1), the volumetric rates raised from 0.1 to 8.9 L H2 L(-1) d(-1), and the yields were stable around 2.0 mol H2 mol(-1) converted sucrose. Furthermore, hydrogen was produced mainly via ethanol-type fermentation, reaching a total energy conversion rate of 23.40 kJ h(-1) L(-1) based on both hydrogen and ethanol production.

The use of the carbon/nitrogen ratio and specific organic loading rate as tools for improving biohydrogen production in fixed-bed reactors.

This study assessed the effect of the carbon/nitrogen (C/N) ratio on the hydrogen production from sucrose-based synthetic wastewater in upflow fixed-bed anaerobic reactors. C/N ratios of 40, 90, 140, and 190 (g C/g N) were studied using sucrose and urea as the carbon and nitrogen sources, respectively. An optimum hydrogen yield of 3.5 mol H2 mol-1 sucrose was obtained for a C/N ratio of 137 by means of mathematical adjustment. For all C/N ratios, the sucrose removal efficiency reached values greater than 80% and was stable after the transient stage. However, biogas production was not stable at all C/N ratios as a consequence of the continuous decreasing of the specific organic loading rate (SOLR) when the biomass accumulated in the fixed-bed, causing the proliferation of H2-consuming microorganisms. It was found that the application of a constant SOLR of 6.0 g sucrose g-1 VSS d-1 stabilized the system.

Actividad metanogénica específica en un reactor anaerobio - aerobio aplicado al tratamiento de agua residual doméstica / Specific methanogenic activity in an anaerobic-aerobic reactor applied to the treatment of domestic residual water

El ensayo de actividad metanogénica específica (AME) es una importante herramienta para el monitoreo de la digestión anaerobia. En este estudio se observó el comportamiento de las arqueas metanogénicas de un lodo anaerobio, bajo diferentes condiciones de oxigenación en un reactor anaerobio-aerobio de lecho fijo, operado de modo continuo con diferentes razones de recirculación de la fase líquida para remover carbono y nitrógeno, aplicado al tratamiento de aguas residuales domésticas. La aplicación del ensayo AME fue adaptado de varios autores y la medición del metano acumulado en el reactor se realizó mediante cromatografía gaseosa. Al finalizar los experimentos se observó que la presencia de oxígeno no inhibió el comportamiento de los organismos metanogénicos. Al contrario, la velocidad de producción de CH4 fue mayor en comparación con los resultados obtenidos en la fase en que el reactor operó de forma anaerobia.

Herida abdominal por arma blanca / Abdominal wounds by knife

Se hace un estudio de las heridas por arma blanca evaluadas en el Hospital Pérez Carreño

Evaluación de la eficacia y tolerancia del Saccharomyces Boulardii (Florestor) en pacientes con diarrea aguda: Un estudio multicéntrico / Evaluation of the tolerance and efficacy of saccharomyces boulardii in patients with acute diarradea: Multicentric study

Se evaluó la eficacia y la tolerancia del Florestor (Saccharomyces boulardii, dosis diaria oral 400 mg) en el síndrome de diarrea aguda, mediante un estudio clínico abierto y multicéntrico, donde se incluyeron 230 niños con edades comprendidas entre 3 meses y 5 años. La evaluación del total diario de puntos antes y después de tratamiento con Florestor mostró una diferencia estadísticamente significante (p<0,001). Esta cuantificación de la eficacia reflejó indirectamente porcentajes de curación de 91,7 por ciento a los tres días de tratamiento. Al tercer día de tratamiento, la eficacia clínica fue considerada como muy eficaz o eficaz en un 99,1 por ciento del total de pacientes. En un 96 por ciento del universo de los 230 pacientes, la tolerancia fue expresada como excelente o buena. Se concluye que florestor es un producto seguro y eficaz para el tratamiento de la diarrea aguda, no complicada, asociado a la rehidratación oral en niños ambulatorios con edades entre 3 meses y 5 años