Developments in microbial fuel cell modeling Ortiz-Martínez, V.M.; Salar-García, M.J.; de los Ríos, A.P. ...
Chemical engineering journal (Lausanne, Switzerland : 1996),
07/2015, Letnik:
271
Journal Article
Recenzirano
•Modeling is a powerful tool for the in-depth study and optimization of MFCs.•MFC modeling allows valuable data to be collected for decision-making.•MFC models can be classified according to the ...approach they follow and their complexity.•MFC modeling studies remain scarce compared with experimental works.
Microbial Fuel Cells (MFCs) offer promising prospects in the field of renewable energy since green electrical power is produced by the microbial activity and wastewater is treated simultaneously. MFCs are complex devices whose study requires an interdisciplinary approach as many processes of a diverse nature are involved. Interest in MFC has significantly increased in recent decades, and much scientific effort has been dedicated to making this technology more efficient. However, the focus has been on experimental work, and MFC modeling has tended to be neglected, and only recently has it received more attention with a consequent rise in the number of new MFC models available. Modeling is an effective tool for gaining a better understanding of MFCs, since it has many advantages in terms of cost and time savings. The present article looks at the state of modeling and simulation of MFCs and outlines and classifies the most prominent models described in the literature. Since modeling approaches can vary greatly from case to case, this work will summarize the advantages and drawbacks of each approach, including not only models based on classic approaches but also those using mathematical optimization techniques.
The development of monitoring systems for rotating machines is the ability to accurately detect different faults in an incipient state. The most popular rotating machine in industry is the ...squirrel-cage induction motor, and the failure on such motors may have severe consequences in costs, product quality, and safety. Most of the condition-monitoring techniques for induction motors focus on a single specific fault. The identification of two or more combined faults has been rarely considered, in spite of being a very usual situation in real rotary machines. On the other hand, information entropy is a signal processing technique that has recently proved its suitability for fault detection on induction motors, and fuzzy logic analysis has extensively been used in combination with several processing techniques in improving the diagnosis of a single isolated fault. The contribution of this paper is a novel methodology that is suitable for hardware implementation, which merges information entropy analysis with fuzzy logic inference to identify faults like bearing defects, unbalance, broken rotor bars, and combinations of faults by analyzing one phase of the induction motor steady-state current signal. The proposed methodology shows satisfactory results that prove its suitability for online detection of single and multiple combined faults in an automatic way through its hardware implementation in a field programmable gate array device.
Inflammatory arthritis defines a family of diseases influenced by reproductive hormones. Vasoinhibin, a fragment of the hormone prolactin (PRL), has antiangiogenic and proinflammatory properties. We ...recently showed that vasoinhibin reduces joint inflammation and bone loss in severe antigen-induced arthritis (AIA) by an indirect mechanism involving the inhibition of pannus vascularization. This unexpected finding led us to hypothesize that a severe level of inflammation in AIA obscured the direct proinflammatory action of vasoinhibin while allowing the indirect anti-inflammatory effect via its antiangiogenic properties. In agreement with this hypothesis, here we show that the intra-articular injection of an adeno-associated virus type-2 vector encoding vasoinhibin reduced joint inflammation in a severe AIA condition, but elevated joint inflammation in a mild AIA model. The proinflammatory effect, unmasked in mild AIA, resulted in joint swelling, enhanced leukocyte infiltration, and upregulation of expression of genes encoding proinflammatory mediators (Il1b, Il6, Inos, Mmp3), adhesion molecule (Icam1), and chemokines (Cxcl1, Cxcl2, Cxcl3, Ccl2). Furthermore, vasoinhibin induced the expression of proinflammatory mediators and chemokines in cultured synovial fibroblasts through nuclear factor-κB. Finally, matrix metalloproteases and cathepsin D, upregulated in the arthritic joint, cleaved PRL to vasoinhibin, and vasoinhibin levels increased in the circulation of mice subjected to AIA. We suggest that vasoinhibin is generated during inflammatory arthritis and acts on synovial fibroblasts and endothelial cells to initially promote and later inhibit inflammation, respectively. These opposite effects may work together to help keep joint inflammation under balance.
The relevance of power quality (PQ) issues has recently augmented because of the increased use of power electronic equipment, which results in a voltage deviation and current waveforms. The PQ ...monitoring is covered by two main subjects: the development of PQ indices to quantify the power supply quality and the electrical disturbances detection such as harmonics, sags, swells, etc., which allows knowing the conditions of the electric power systems. In this study, a review of techniques and methodologies developed for PQ analysis and power disturbance classification is presented in order to show their major characteristics.
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•An alternative cathode using TiO2 nanotubes.•Determination of the structural, morphological and electronic characteristics of the cathode.•Effect of crystalline structure on MFCs ...performances.
In the present work, amorphous and crystalline TiO2 nanotubes (TiNT) were fabricated via anodization and characterized as an alternative cathode for Microbial Fuel Cells (MFCs). The morphology of TiNT is characterized by scanning electron microscopy (SEM). The crystalline structure and chemical composition are examined by X-ray diffraction (XRD) and Energy dispersive X-ray spectroscopy (EDX). The electrical conductivity characteristics were examined by electrochemical impedance spectroscopy (EIS). MFCs based on the alternative cathodes were evaluated in terms of energy generation and wastewater treatment. The performances of the as-anodized nanotubes and TiNT annealed at 450°C and at 550°C were investigated in double-chamber MFCs with carbon rod and graphite granules as anode and polymer inclusion membrane based on ionic liquid as separator. Industrial wastewater was the source of carbon and inoculum for the experiments. The as grown amorphous nanotubes exhibited the best output power density of 15.16mWm−2. The results reported here indicate that the specific surface area and the oxygen vacancies of the TiNT cathode can influence the MFCs performance together, because both factors play crucial role in the oxygen reduction reaction (ORR). As-anodized TiNT, due to its higher specific surface provide more active sites for electrode reactions.
The final oxygen demand (COD) for all systems achieved a COD removal within the interval 54–71% after 10days. This approved the suitability of MFCs for wastewater treatment.
The Mediterranean Sea shows a peculiar anomaly in its nutrient pattern compared to the global ocean, as there is decrease in nutrient concentration from west to east. This feature has been attributed ...to the antiestuarine circulation at the Strait of Gibraltar, where an eastward flow of Atlantic nutrient‐poor surface waters is compensated by a westward countercurrent of Mediterranean nutrient‐rich deep waters. This water exchange has been suggested as the ultimate cause for the oligotrophy of the Mediterranean basin, even though only a few studies have accurately examined the magnitude of the nutrient flux through the Strait of Gibraltar. In this work, data from the Gibraltar Fixed Time series (GIFT) between 2005 and 2008 were used to assess nutrient distributions. Applying a two‐layer model of water mass exchange and using the Mediterranean outflow recorded in situ, the net export of nutrients from the Mediterranean to the Atlantic was calculated as 139 and 4.8 Gmol yr−1 of nitrate and phosphate, respectively. The results also demonstrated that the Atlantic inflow is not nutrient depleted and in particular contains significant levels of phosphate, which is the limiting factor for biological productivity in the eastern Mediterranean. The distribution of the quasi‐conservative parameter N* in the western and eastern basins indicated that nitrate‐deficient surface waters are transformed into phosphate‐deficient bottom waters by internal cycling processes. Therefore, phosphate depletion in the Mediterranean does not have its origin in the entry of a phosphorus‐impoverished Atlantic inflow through the Strait of Gibraltar.
Key Points
Role of the Strait of Gibraltar in the nutrient cycle of the Mediterranean
Biogeochemical fluxes between the Atlantic Ocean and the Mediterranean Sea
Budget of nutrients in the Mediterranean Sea
•MnO2-based cathodes for their application in single-chamber MFCs.•CNTs as support materials improve MFC performance compared with black acetylene.•PTFE as binder for MnO2-based cathodes greatly ...affects MFC performance.•Significant COD and heavy metal removal in MFCs using MnO2-based cathodes.•Pressure method as preferable cathode construction technique versus spraying.
Microbial Fuel Cells (MFCs) are a promising technology that offers new opportunities for bioenergy generation with simultaneous wastewater treatment. The search for new and inexpensive catalysts that replace precious metal-based materials for their application in air-cathode single-chamber MFCs is crucial for improving the efficiency of this technology and, thus, for its commercialization and scaling-up in the field of wastewater treatment. In this work, several types of cathodes consisting of a mixture of MnO2 as catalyst material and two different additive conductor supports, carbon nanotubes (CNTs) and acetylene black (AB), respectively, are investigated in single-chamber MFCs, in the presence and in the absence of a polymer binder, polytetrafluoroethylene (PTFE), both in terms of power performance and wastewater treatment (COD and heavy metal removal). Furthermore, the influence of two preparation methods to fix the above mixtures onto carbon cloth electrodes, spraying and mechanical pressure techniques, are compared to optimize cathode construction. Maximum values of current and power densities were observed for the cathode based on MnO2/CNT/PTFE prepared by mechanical pressure, 1.536mAdm−3 and 511.11mWm−3, respectively. This cathode configuration achieved the maximum chemical oxygen demand (COD) removal with a value of 77% after 240h of MFC operation using wastewater as fuel. The analysis of the removal of heavy metals (63Cu, 66Zn, 111Cd, 121Sb, 208Pb, 55Mn and 56Fe) from wastewater in the different MFC types offered removal efficiencies within the interval 60–97% for most of the metals studied.
•Non-edible Jatropha oil to produce biodiesel in supercritical methanol.•Maximum FAME yield of 99.5wt% is obtained at 325°C, 90min and 42:1 methanol/oil.•Thermal decomposition is evidenced at the ...temperature of 350°C.•The maximum thermal cracking degree (24.16%) is obtained at 350°C and 90min.•The individual FAMEs thermally degraded are oleic and linoleic.
Recent years have seen great efforts made to optimise the production of biodiesel as an alternative to fossil fuel. This study looks at the optimal conditions for producing second generation biodiesel in supercritical methanol from Jatropha oil. Triglyceride conversion and the yield of monoglycerides, diglycerides and fatty acid methyl esters (FAMEs) are analysed for different ranges of temperature and time. The maximum conversion of triglycerides (100wt%) and maximum yield of FAMEs (99.5mol%) were achieved at 325°C with a reaction time of 90min. The thermal decomposition of the biodiesel produced was greatest (24.16%) at 350°C and 90min. Quantification of individual methyl esters showed that the fatty acid chains affected by temperature were those of oleic and linoleic acids. Finally, a lineal regression model was applied to predict the effect of temperature on the biodiesel produced.
The nuclear protein high-mobility group box 1 (HMGB1) can be passively released by necrotic cells or secreted actively by several cell types to regulate immune and inflammatory responses, as well as ...tissue remodeling. We herein aimed to characterize the effect of insulin resistance on HMGB1 in adipose tissue and to examine its potential role as a metabolic regulator in β-pancreatic cells.
Plasma HMGB1 concentration and adipose HMGB1 expression were assessed in relation to obesity and insulin resistance. Cultured adipocytes from lean and obese patients were used to investigate the intracellular distribution and factors regulating HMGB1 release, as well as to test its effects on adipogenesis and lipid metabolism. A regulatory role for HMGB1 in insulin secretion was also investigated.
Circulating HMGB1 was positively associated with body mass index, while adipose HMGB1 mRNA levels correlated with the expression of inflammatory markers. Insulin resistance modified the intracellular distribution of HMGB1 in human adipocytes, with HMGB1 being predominantly nuclear in lean and obese normoglycemic individuals while localized to the cytosol in obese patients with type 2 diabetes. Adipocytes from lean individuals exposed to conditioned media from lipopolysaccharide-stimulated macrophages induced HMGB1 redistribution to the cytoplasm and release. HMGB1 treatment had no effect on differentiation and lipid metabolism in adipocytes. However, HMGB1, whose circulating levels correlated with postload insulin concentration, increased both insulin release and intracellular Ca(2+) concentration in INS-1 cells.
These findings show, for the first time, that HMGB1 expression and release by human adipocytes is altered by inflammatory conditions as those imposed by obesity and insulin resistance. Our data reveal a novel role for HMGB1 as a stimulatory factor of insulin secretion of β-pancreatic cells.
Two major subsets of human Mo are identified based on CD14 and CD16 expression: the classical CD16(-) Mo and the minor CD14(+)CD16(+) Mo. In vitro studies suggested distinct function and ...differentiation potential for each cell population. However, the in vivo relevance of these findings remains unclear. To evaluate the development and function of human Mo in an in vivo model, we transferred both Mo subpopulations into the peritoneum of immunocompromised mice in homeostatic or inflammatory conditions. Inflammation was induced with soluble LPS or particulate zymosan. CD16(+) were more phagocytic and produced higher amounts of TNF and IL-6 than CD16(-) Mo early after transfer with zymosan. They also produced higher levels of β2-defensin in any condition evaluated, which could represent a new marker for this subpopulation. In contrast, differentiating CD16(-) Mo (24 h after transfer) acquired greater APC capacity in LPS-induced peritonitis, whereas none of the Mo subsets attained this ability with zymosan. CX(3)CL1 supported the survival of both Mo subsets in vivo. Similar Mo subpopulations were present in human peritonitis. These results support the idea of specialized roles of the Mo subset, where CD16(+) might act in an immediate innate immune response, whereas CD16(-) could have a major role as APCs.
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