Environmental concerns gather considerable academic research and private investment, namely when addressing water and energy. Wastewater treatment and reuse have become a standard practice across the ...globe. In Europe, this topic has been addressed through the European Commission policy for the environment. Microbial Fuel Cells are a useful technology for wastewater treatment. They can be used for resource scavenging and energy production. Their power output still can't counterbalance, per se, the energy expenditure on wastewater treatment stations, but it can help provide autonomy for physical, chemical, and biochemical measurements in wastewater. The true energetic potential, however, has not been fully exploited, since significant energy losses are still associated with these systems, decreasing the efficiency of this technology. As works with microbial fuel cells grow in number and diversity, an adequate review of the strategies used to apply these devices as power sources is needed.
This work explores the most relevant research, to date, about maximum power extraction from Microbial Fuel Cells, addressing, in detail, the power conditioning devices and strategies for power improvement: from single cells with passive components to cell groups and active strategies, using maximum power point tracking techniques and power converters in different operating modes.
•Benthic Microbial Fuel Cells were the first to produce energy from wastewater.•Passive and active solutions can harvest energy from Microbial Fuel Cells.•Maximum power extraction may happen without energy-intensive approaches.•The Cell's biofilm has energy, available by adjusting charging/recovering times.
The use of Microbial Fuel Cells as power sources in rural or remote locations can solve issues related with power availability and wastewater cleaning. Furthermore, the application of such technology ...in wireless smart sensors applied to wastewater treatment plants can also help in water quality monitoring, increasing the process autonomy and reliability. A trustworthy power source needs to have a predictable and repeatable behavior, which cannot be achieved without adequate models and supporting hardware for energy regulation and storage. The work herein described proposes a steady-state model, represented by an electric circuit made of passive components. This model was first applied to a specific 28 mL air-cathode Microbial Fuel Cells working with artificial wastewater and using graphite brush anodes. Afterwards, the model was further validated by applying it to a larger reactor and to other bibliographic records. The goal of the study is to propose a method for finding a Microbial Fuel Cell model to be used with maximum power point tracking research, guaranteeing the best-case scenario for Microbial Fuel Cell operation as a power source. The reactors used in this study were analyzed by relating time and voltage development, both in colonization and in polarization studies. A mathematical relationship model was developed and proposed allowing to separate MFC's behavior, concerning energy production, in to meaningful components. From the experimental data the method was used to obtain a two-component circuit model that describes the power behavior of this specific Microbial Fuel Cell topology. The same method can be used to described other MFC.
•Power development on Microbial Fuel Cells is not linear with time, external load or reactor volume.•The internal resistance of a Microbial Fuel Cell can be approximated without using a potentiostat.•The polarization curve equation can be estimated and further used for power studies.•The proposed method allows quantifying each of the power losses.•The steady-state power development of Microbial Fuel Cells can be modeled by a Voltage Source and a Resistance.
The effect of the addition of passion fruit peel powder (PFPP) on the fermentation kinetics and texture parameters, post-acidification and bacteria counts of probiotic yoghurts made with two milk ...types were evaluated during 28 days of storage at 4 °C. Milks were fermented by Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (CY340), and one strain of probiotic bacteria: Lactobacillus acidophilus (L10 and NCFM), Bifidobacterium animalis subsp. lactis (Bl04 and HN019). The addition of PFPP reduced significantly fermentation time of skim milk co-fermented by the strains L10, NCFM and HN019. At the end of 28-day shelf-life, counts of B. lactis Bl04 were about 1 Log CFU mL–1 higher in whole yoghurt fermented with PFPP regarding its control but, in general, the addition of PFPP had less influence on counts than the milk type itself. The titratable acidity in yoghurts with PFPP was significantly higher than in their respective controls, and in skim yoghurts higher than in the whole ones. The PFPP increased firmness, consistency (except for the NCFM strain of L. acidophilus) and cohesiveness of all skim yoghurts. The results point out the suitability of using passion fruit by-product in the formulation of both skim and whole probiotic yoghurts.
► The passion fruit fiber reduced the maximum acidification rate in all yoghurts. ► L. acidophilus exerted a symbiotic effect on L. delbrueckii subsp. bulgaricus. ► The milk type influenced significantly the probiotic counts during the shelf-life. ► Passion fruit fiber did not show any clear effect on probiotic counts. ► The fruit fiber increased the cohesiveness in probiotic skim yoghurts.
Purposes
The aim of this paper was to characterize elements dynamics, including resorption before leaf shedding and accumulation/release during decomposition, of two functionally different tree ...species, the N-fixing, broadleaf, deciduous black locust (
Robinia pseudoacacia
L.), and the Mediterranean black pine (
Pinus nigra
Arn.), planted on recent unconsolidated volcanic deposits.
Methods
In two paired, 40 years old stands, we investigated the stoichiometry of thirteen elements in green leaves, newly shed leaf litter, stable litter residue and soil.
Results
Black locust leaves were richer in N, P, K, Mg and Mn; black pine needles were richer in Na, Fe, Zn, Cr, and Pb. Resorption efficiency was Pb > Zn > Fe ~ N ~ Mn ~ Mg > Cd ~ K > P in black locust, and Pb ~ Cu > Zn ~ Na > Mn > K ~ Cr in black pine. Compared to black pine, black locust newly shed litter was richer in K, Na, Mn, Cu, and Ni. During decomposition, black locust leaf litter released N, K, Mg, Na, Mn, Zn, Cu and Cd, and accumulated Fe, Ni, Cr and Pb, whilst black pine needles released N, Zn and Cd, and accumulated all the other elements. Compared to black locust black pine had a stable needle litter residue richer in all elements but N, whilst the mineral soil was poorer in all elements but Pb.
Conclusions
The two functionally different tree species have distinct element dynamics from leaf to far decomposed litter. Element sequestration in the stable residue of black pine litter, likely prevents their release in the mineral soil that is thus poorer in nutrients and minor elements compared to the soil of black locust.
Aims
In Mediterranean ecosystems fire and drought are two natural disturbances that affect plant traits and generate a highly heterogeneous landscape. The objective of this research was to analyze ...leaf chemistry, one important driver of carbon and nutrients cycles, and decomposition of
Phillyrea angustifolia
L. in a landscape affected by recurrent fire disturbance.
Methods
We investigated leaf litter collected in a low-maquis at sites burned by a wildfire 10 years before the current study, at sites burned by an experimental fire 1 year before and at sites located at the edge low-maquis/gaps.
Results
The three litters differed in chemical composition, mass loss and dynamics of lignin/AUR (Acid-Unhydrolizable-Residue), nitrogen and manganese. During the early decomposition phase lignin/AUR increased in litters from sites burned 1 year before and from sites located at the edge low-maquis/gaps and decreased in litter from sites burned 10 years before. Nitrogen and manganese were immobilized in litter during the early and the middle phase of decomposition.
13
C NMR spectroscopy revealed that all the litters were rich in Alkyl-C, the fraction including waxes and cutin that are effective barriers to water loss from the leaves. Litter from sites burned 1 year before had the highest hydrophobicity and aromaticity indexes and the highest alkyl ratio, and decomposed at the lowest rate.
Conclusions
Differences of leaf chemical composition within the same plant species across an uneven landscape affect decomposition. The traditional approach and
13
C NMR spectroscopy complementarily explain decomposition pattern and give a comprehensive view of the individual drivers of litter decomposition.
Thermoelastic deformation mechanisms in polycrystalline biomedical‐grade superelastic NiTi are spatially mapped using in situ neutron diffraction during multiaxial loading and heating. The trigonal ...R‐phase is formed from the cubic phase during cooling to room temperature and subsequently deforms in compression, tension, and torsion. The resulting R‐phase variant microstructure from the variant reorientation and detwinning processes are equivalent for the corresponding strain in tension and compression, and the variant microstructure is reversible by isothermal loading. The R‐phase variant microstructure is consistent between uniaxial and torsional loading when the principal stress directions of the stress state are considered (for the crystallographic directions observed here). The variant microstructure evolution is tracked and the similarity in general behavior between uniaxial and torsional loading, in spite of the implicit heterogeneous stress state associated with torsional loading, pointed to the ability of the reversible thermoelastic transformation in NiTi to accommodate stress and strain mismatch with deformation. This ability of the R‐phase, despite its limited variants, to accommodate stress and strain and satisfy strain incompatibility in addition to the existing internal stresses has significance for reducing irrecoverable deformation mechanisms during loading and cycling through the phase transformation.
Thermoelastic deformation mechanisms in polycrystalline biomedical‐grade superelastic NiTi are spatially mapped using in situ neutron diffraction during multi‐axial loading and heating. The similarity in R‐phase variant behavior between uniaxial and torsional loading, in spite of the heterogeneous stress state associated with torsional loading, is discussed along with its ability to accommodate the resulting stress and strain mismatch.
Recent earthquakes have exposed the vulnerability of existing buildings; this is demonstrated by damage incurred after moderate-to-high magnitude earthquakes. This stresses the need to exploit ...available data from different sources to develop reliable seismic risk components. As far as it regards empirical fragility assessment, accurate estimation of ground-shaking at the location of buildings of interest is as crucial as the accurate evaluation of observed damage for these buildings. This implies that explicit consideration of the uncertainties in the prediction of ground shaking leads to more robust empirical fragility curves. In such context, the simulation-based methods can be employed to provide fragility estimates that integrate over the space of plausible ground-shaking fields. These ground-shaking fields are generated according to the joint probability distribution of ground-shaking at the location of the buildings of interest considering the spatial correlation structure in the ground motion prediction residuals and updated based on the registered ground shaking data and observed damage. As an alternative to the embedded coefficients in the ground motion prediction equations accounting for subsoil categories, stratigraphic coefficients can be applied directly to the ground motion fields at the engineering bedrock level. Empirical fragility curves obtained using the observed damage in the aftermath of Amatrice Earthquake for residential masonry buildings show that explicit consideration of the uncertainty in the prediction of ground-shaking significantly affects the results.
The development of mimetic antibodies (MA) capable of combining the high affinity and selectivity of antibodies with the small size of the peptides has enormous potential for applications in current ...biotechnology. In this work, we demonstrate that in silico MA design is possible through genetic algorithms (GA) developed from shell scripts capable of combining software commonly used for atomistic simulation. Our results demonstrate that, using the GB1 domain of the streptococcal G protein as a model, it is possible to optimize the molecular recognition capacity of a large MA population in a few generations. In the first case, GA was able to generate 10 MA with binding free energy (BFE) less than the vascular endothelial cell growth factor conjugated with the fms-type tyrosine kinase receptor. In the second case, it generated 13 MA with BFE less than that of the hepatitis C-E2 viral envelope conjugate with the antibody. Through the GA developed in this work, we demonstrate the use of a new protocol, capable of guiding experimental methods for the design of bioactive peptides that can assist in the development of new therapeutic molecules.
The aim of this study was to assess the effects of pre-operative statin therapy on cardiovascular events in the first 30-days after non-cardiac surgery.
We conducted an international, prospective, ...cohort study of patients who were ≥45 years having in-patient non-cardiac surgery. We estimated the probability of receiving statins pre-operatively using a multivariable logistic model and conducted a propensity score analysis to correct for confounding. A total of 15 478 patients were recruited at 12 centres in eight countries from August 2007 to January 2011. The matched population consisted of 2845 patients (18.4%) treated with a statin and 4492 (29.0%) controls. The pre-operative use of statins was associated with lower risk of the primary outcome, a composite of all-cause mortality, myocardial injury after non-cardiac surgery (MINS), or stroke at 30 days relative risk (RR), 0.83; 95% confidence interval (CI), 0.73-0.95; P = 0.007. Statins were also associated with a significant lower risk of all-cause mortality (RR, 0.58; 95% CI, 0.40-0.83; P = 0.003), cardiovascular mortality (RR, 0.42; 95% CI, 0.23-0.76; P = 0.004), and MINS (RR, 0.86; 95% CI, 0.73-0.98; P = 0.02). There were no statistically significant differences in the risk of myocardial infarction or stroke.
Among patients undergoing non-cardiac surgery, pre-operative statin therapy was independently associated with a lower risk of cardiovascular outcomes at 30 days. These results require confirmation in a large randomized trial.
Clinical Trials.gov NCT00512109.
Multiscale methods for second order elliptic equations based on non-overlapping domain decomposition schemes have great potential to take advantage of multi-core, state-of-the-art parallel computers. ...These methods typically involve solving local boundary value problems followed by the solution of a global interface problem. Known iterative procedures for the solution of the interface problem have typically slow convergence, increasing the overall cost of the multiscale solver. To overcome this problem we develop a scalable recursive solution method for such interface problem that replaces the global problem by a family of small interface systems associated with adjacent subdomains, in a hierarchy of nested subdomains. Then, we propose a novel parallel algorithm to implement our recursive formulation in multi-core devices using the Multiscale Robin Coupled Method by Guiraldello et al. (2018) 26, that can be seen as a generalization of several multiscale mixed methods. Through several numerical studies we show that the new algorithm is very fast and exhibits excellent strong and weak scalability. We consider very large problems, that can have billions of discretization cells, motivated by the numerical simulation of subsurface flows.
•A general recursive formulation for a family of multiscale methods.•A novel parallel implementation in three spatial dimensions.•Excellent parallel scalability for very large problems, up to 2 billion cells.•Velocity field calculation obtained with satisfactory accuracy.
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