Diseño de un proyecto de investigación básico

Nos proponemos que los estudiantes entren en contacto con las actividades de investigación y que, de manera autónoma, aunque guiados por el profesor, encuentren la respuesta a una pregunta mediante el desarrollo del método científico, haciendo uso también de unos procedimientos básicos para la elaboración de un proyecto de investigación.We propose that the students come in contact with the activities of research and that, in an autonomous manner, while guided by the professor, to find the answer to a question through the development of the scientific method, by using a few basic procedures for the preparation of a research project

Mecanismos iónicos de acoplamiento en la secreción pancreática

El objetivo de este trabajo de investigación ha sido determinar el papel que juegan iones como el Ca2+ y el Mg2+, así como el pH intracelular en la secreción pancreática estimulada por un secretagogo, la CCK, un neurotransmisor, la ACh, y un agente modulador como es la histamina, mensajeros intercelulares que se sabe utilizan la misma vía de acoplamiento, la vía del metabolismo de los inositoles fosfato de membrana asociado a calcio. Para ello se han utilizado células acinares procedentes de pancreas de rata Wisiar, que se cargaban con biosondas fluorescentes sensibles a las concentraciones plasmáticas, tanto básales como en respuesta a los secretagogos citados, de Ca2+ y Mg2+ y al pH.Proyecto DGICYT PB91-0463Ministerio de Educación y Ciencia (PB91-0463

Alternative start-up strategies for the Bioelectrosynthesis of acetate

Carbon capture and utilization at biocathodes provides a solution to minimize CO2 emissions meanwhile commodity chemicals are being generating from an inexpensive substrate. The aim of this work is to develop biocathodes for MES systems capable of making use of CO2 in order to generate valuable chemicals. The biocathodes were inoculated using two different inocula and following two different strategies. These different start-up conditions showed distinct electrical behavior in three of the four cases. These microbial electro-synthesis systems (MES) were capable of achieving an acetic acid production between 70-196mg/L depending on the strategy. The use of a river mud inoculum resulted in a sharp enrichment, and when the potential was invert to force it to work as a biocathode, the biofilm got mostly specific in acetic acid producing bacteria, Acterobacteraceae, and some hydrogen generating bacteria. The hydrogenotrophic methanogen Methanobacteriaceae, was the only family identified on the cathode. However, the use of an anaerobic digestion inoculum resulted in a highly diverse biofilm and in a lower acetic acid production with hydrogen detected. The Archaeal population was inhibited under this condition. To conclude it is observed that specialisation of biofilm in certain Eubacterial families improves bioelectrosynthesis, and acetic acid production in particular. In addition, it is highlighted that being the Archaeal community quite similar within both biofilms, the dominant families on the cathode biofilms were drastically different, likely due to the difference in the Eubacterial microorganisms. Thanks “Junta de Castilla y Leon” for postdoctoral contract associated to project ref: LE060U16. The authors acknowledge the funding of the Spanish “Ministerio de Economía y Competitividad” via project CTQ2015-68925-R

Reduced graphene oxide improves the performance of a methanogenic biocathode

.Microbial electrosynthesis (MES), a sub-branch of bioelectrochemical processes, takes advantage of a certain type of electroactive microorganism to produce added value products (such as methane) from carbon dioxide (CO2). The aim of this study is to quantify the benefits of using a carbon felt electrode modified with reduced graphene-oxide (rgoCF) as a methanogenic biocathode. The current density generated by the rgoCF was almost 30% higher than in the control carbon felt electrode (CF). In addition, charge transfer and ohmic resistances were, on average, 50% lower in the rgoCF electrode. These improvements were accompanied by a larger presence of bacteria (31% larger) and archaea (18% larger) in the rgoCF electrode. The microbial communities were dominated by hydrogenotrophic methanogenic archaea (Methanobacterium) and, to a lesser extent, by a low-diversity group of bacteria in both biocathodes. Finally, it was estimated that for a CO2 feeding rate in the range 15–30 g CO2 per m2 of electrode per day, it is possible to produce a high-quality biogas (>95% methane concentrationS

La utilización del feedback en disminución progresiva en el aprendizaje de la respuesta de reacción

La frecuencia relativa del conocimiento de los resultados (CR) consiste en la proporción de información en relación al número total de ensayos. Una frecuencia baja de CR provoca un buen aprendizaje, pero suele ser perjudicial para la ejecución. En el siguiente trabajo se pone a prueba una forma de distribuir la información en disminución progresiva, siendo alta al principio y baja al final de la práctica, ayudando al sujeto en la adquisición de la tarea y evitando los efectos nocivos de una guía excesiva. Se compararon cuatro grupos en el aprendizaje de la salida de atletismo, utilizando el mismo sistema automatizado que Oña y sus colaboradores exponen en diversos trabajos.The relative frequency of knowledge of results (KR) is the proportion of information to the total number of trials. A lower frequency of KR causes a good learning, but uses to be detrimental to practice performance. In this work, a way of distributing the information in progressive decrease is examined, being high at the beginning and low at the end of the practice, helping the subject in the acquisition of the task and avoiding the noxious effects of an excessive guide. Four groups were compared in the learning of the exit of athletics, using the same automated system that Oña and col. expose in different works

Understanding nitrogen recovery from wastewater with a high nitrogen concentration using microbial electrolysis cells

9 p.This study was aimed at understanding the effect of applied voltage, catholyte and reactor scale on nitrogen recovery from two different organic wastes (digestate and pig slurry) by means of microbial electrolysis cell (MEC) technology. For this purpose, MEC sizes of 100, 500 and 1000 mL were tested at applied voltages of 0.6, 1 and 1.4 V using either a phosphate-buffered solution or NaCl solution as the catholyte. By increasing the reactor size from 500 mL to 1000 mL, a decrease in the ammonia recovery efficiency from 47 to 42 % was observed. The results also showed that the phosphate-buffered solution is preferable as the catholyte and that the voltage applied does not have a noticeable effect on current production and ammonia recovery. Low biodegradability of the wastes was identified as the main bottleneck. This research was supported by the European Union Horizon 2020 Research and Innovation Programme (GA nº 668128-Newfert-H2020-BBI-PPP-2014-1). Financing: This project has received funding from the Bio Based Industries Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 66812

Impact of the start-up process on the microbial communities in biocathodes for electrosynthesis

[EN]This study elucidates the impact of the start-up strategies on the microbial communities that evolve on the biofilm of a biocathode. Using reductive start-up potentials and a highly diverse inoculum, this start-up failed to produce any biofilm. When a less species richness inoculum from an anaerobic environment was used with the same reductive initial potential, a specialised biofilm was formed and a highly productive biocathode was developed in terms of acetic acid and also current production. However, using oxidative start-up potential led to rapid electroactive biofilm development, although the final composition of the biofilm was highly dependent on the inoculum used. So, using the diverse RM inoculum, a final specialised biofilm grew on the electrode, also giving high acetate and current generation. However, when using the less species richness AD inoculum, it was found that a nonspecialised biofilm was developed and lower acetic acid production was found. Importantly, a higher specialisation of the biofilm leads to an improvement in acetate generation, probably due to lowered influence of undesirable secondary methabolic pathways. Moreover, it has been shown that the coupling of H2 producing bacteria and acetic acid bacteria play an important role in acetate productionSIThis research was possible thanks to the financial support of the ‘Ministerio de Economía y Competitividad’ project ref: CTQ2015-68925-R, cofinanced by FEDER funds. Raúl Mateos thanks the Spanish ‘Ministerio de Educación, Cultura y Deporte’ for the FPU Grant (FPU14/01573). Ana Sotres thanks the regional ‘Junta de Castilla y León’ for the postdoctoral contract associated with project ref: LE060U16

Optimization, Stability, and Entropy in Endoreversible Heat Engines

[EN]The stability of endoreversible heat engines has been extensively studied in the literature. In this paper, an alternative dynamic equations system was obtained by using restitution forces that bring the system back to the stationary state. The departing point is the assumption that the system has a stationary fixed point, along with a Taylor expansion in the first order of the input/output heat fluxes, without further specifications regarding the properties of the working fluid or the heat device specifications. Specific cases of the Newton and the phenomenological heat transfer laws in a Carnot-like heat engine model were analyzed. It was shown that the evolution of the trajectories toward the stationary state have relevant consequences on the performance of the system. A major role was played by the symmetries/asymmetries of the conductance ratio shc of the heat transfer law associated with the input/output heat exchanges. Accordingly, threemain behaviorswere observed: (1) For small shc values, the thermodynamic trajectories evolved near the endoreversible limit, improving the efficiency and power output values with a decrease in entropy generation; (2) for large shc values, the thermodynamic trajectories evolved either near the Pareto front or near the endoreversible limit, and in both cases, they improved the efficiency and power values with a decrease in entropy generation; (3) for the symmetric case (shc = 1), the trajectories evolved either with increasing entropy generation tending toward the Pareto front or with a decrease in entropy generation tending toward the endoreversible limit. Moreover, it was shown that the total entropy generation can define a time scale for both the operation cycle time and the relaxation characteristic time.Junta de Castilla y León, Project No. SA017P1

Pilot-scale bioelectrochemical system for simultaneous nitrogen and carbon removal in urban wastewater treatment plants

[EN] This study aims to characterize the performance of a 150 L bioelectrochemical system-based plant, during the simultaneous carbon and nitrogen removal from several waste streams of wastewater treatment plants. The bioelectrochemical system (BES) contained five electrode pairs (operated hydraulically and electrically in parallel) and was fed with either wastewater, centrate (nutrient-rich liquid stream produced during the dewatering of digested biomass), or a mixture of both over 63 days, with a hydraulic retention time of one day. Total organic carbon and total nitrogen removal rates averaged 80% and 70%, respectively, with a specific energy consumption of 0.18 kWh·m−3 (BES + ancillary equipment). This work also underlines the challenges of using BES for nitrogen removal, highlighting the limitations of the current design, and suggesting some strategies for improvement.SIMinisterio de Educación, Cultura y Deport

The impact of externally added hydrogen gas on microbial electrosynthesis from CO2

Hydrogen is a key versatile biomolecule in microbial electrosynthesis (MES). It can be directly produced by electrolysis to be used as an intermediate, directly biosynthesize by electroactive microorganisms from protons and electrons, or externally added to drive other bioelectrochemical or biological reactions. The aim of this study is to bring further understanding on how externally added hydrogen impacts product formation on MES. Two double-chamber microbial electrolysis cells were built in 500mL modified Schott-Duran bottles (Figure 1A). The cathode consisted of a 175 cm2 carbon felt (+1V vs. Ag/AgCl) and a platinum wire was used as counter electrode. The cathode was inoculated according to the procedure detailed in Bajracharya et al. 2017, and following the acclimation period the biocathode was fed with a gas mixture containing 20% H2 / 20% N2 / 60% CO2. After 2 weeks of operation hydrogen was removed from the feed ( 20% N2 / 80% CO2). When the cell was fed with the hydrogen-containing mixture, acetate and ethanol concentrations (Figure 1B) grew steadily with time (composition ratio around 1:1 (w/w)). This behavior suggested that hydrogen was acting as a reducing agent driving direct production of ethanol, or even its production from acetate. However, when hydrogen was removed from the feed, ethanol concentration declined, while acetate concentration sharply increased showing CO2-acetate selectivities near 100%. These results indicate how ethanol production is highly dependent on externally-added hydrogen, while the synthesis of acetate only requires the cathode as a source of electrons. A.Sotres thanks “Junta de Castilla y Leon” for postdoctoral contract associated to project ref: LE060U16, cofinanced by FEDER fund