We investigate the existence of solutions to viscous ergodic Mean Field Games systems in bounded domains with Neumann boundary conditions and local, possibly aggregative couplings. In particular we ...exploit the associated variational structure and search for constrained minimizers of a suitable functional. Depending on the growth of the coupling, we detect the existence of global minimizers in the mass subcritical and critical case, and of local minimizers in the mass supercritical case, notably up to the Sobolev critical case.
Bipolar Membrane Reverse Electrodialysis (BMRED) can be used to produce electricity exploiting acid-base neutralization, thus representing a valuable route in reusing waste streams. The present work ...investigates the performance of a lab-scale BMRED module under several operating conditions. By feeding the stack with 1 M HCl and NaOH streams, a maximum power density of ~17 W m−2 was obtained at 100 A m−2 with a 10-triplet stack with a flow velocity of 1 cm s−1, while an energy density of ~10 kWh m−3 acid could be extracted by a complete neutralization. Parasitic currents along feed and drain manifolds significantly affected the performance of the stack when equipped with a higher number of triplets. The apparent permselectivity at 1 M acid and base decreased from 93% with the five-triplet stack to 54% with the 38-triplet stack, which exhibited lower values (~35% less) of power density. An important role may be played also by the presence of NaCl in the acidic and alkaline solutions. With a low number of triplets, the added salt had almost negligible effects. However, with a higher number of triplets it led to a reduction of 23.4–45.7% in power density. The risk of membrane delamination is another aspect that can limit the process performance. However, overall, the present results highlight the high potential of BMRED systems as a productive way of neutralizing waste solutions for energy harvesting.
Wastewaters generated by crude oil extraction processes, called “produced waters” (PWs), are complex solutions that contain organic compounds, mainly hydrocarbons, and often exhibit high salinity. ...The large amounts of PWs represent a global issue because of their environmental impact. An approach widely used in the oil industry is the reinjection of this wastewater into the extraction wells after a suitable treatment. The high salt concentration of such solutions may be used in salinity gradient technologies to produce green electricity. Among these technologies, reverse electrodialysis (RED) is one of the most promising. In this work, the application of RED for energy generation from two different real oil industry brines was investigated. An experimental campaign was performed by testing 10 × 10 cm2 units in long-run continuous operations, monitoring the performance for more than 25 days. Fouling phenomena, occurring during the continuous operation, decrease the unit performance and several anti-fouling strategies were adopted to tackle this issue. As a result, a positive net power density for up to 18 days of continuous operation was obtained. A maximum power density of about 2.5 W/m2 was observed, demonstrating how the RED technology could be an important strategy to harvest energy from an industrial waste.
Produced waters (PWs) are waste streams generated during the crude oil extraction processes. The management of these wastewaters is complicated by the large volumes extracted during the oil recovery ...operations: these depends on the life of the oil-well: typically, 3 barrels of PWs on average are produced for each barrel of oil extracted. After oil separation, PWs are usually re-injected into the well, but this approach is not always possible without a preliminary and suitable treatment. Bioremediation techniques might be a good option, but they fail due to the PWs high salinity, which inhibit bacteria growth and metabolism. Thus, reducing their salinity upstream a bioremediation unit is a matter of crucial importance. To this aim, Assisted Reverse electrodialysis (ARED) along with the use of a dilute stream typically available on site is here proposed as a novel solution. In ARED an additional voltage is applied in the same direction of the salinity gradient through the membranes in order to enhance the passage of ions from the PW to the diluted solution, thus significantly reducing the required membrane area. An experimental campaign was carried out in order to assess the process feasibility. A fixed volume of real PWs was fed to a laboratory scale ARED unit. Each experimental test lasted for three days to reduce the salinity down to about 20 g l-1, a value compatible with the biomass metabolism for a downstream bioremediation step. Two different types of commercial membranes were tested and relevant energy consumptions were calculated. The long-runs performed did not show a significant loss of efficiency due to fouling, thus suggesting that ARED might a suitable technology for a pre-dilution of produced waters.
During summer 2014, three hypersaline brines were discovered in two frozen lakes of Boulder Clay (Northern Victoria Valley, Antarctica). Ongoing research seeks to gain novel insights on the microbial ...ecology of such environments, in order to further the understanding of life adaptation to extreme conditions. To this aim, the abundance of prokaryotic cells (including cell morphologies and size for biomass conversion), the amount of viable cells (in terms of membrane-intact cells and respiring cells), the viral count, the physiological profiles at community level and the main microbial enzymatic activities were described. The brines differed each other in terms of prokaryotic cells’ abundance, size, and viability as well as viral abundance. Cell morphotypes and metabolic responses also varied among the brine samples. Underground interconnections were likely to occur, with the microbial community becoming more abundant and structured to better exploit the limited resource availability. Overall, complex interactions among multiple environmental factors, including marine water origin, depth horizon, isolation time of the brines, and climatic variations, reflected on the microbial community distribution patterns and highlighted the need to preserve these niches of extreme life.
The sea bottom acts as a key natural archive where the memory of long-term timescale environmental changes is recorded. This study discusses some ecological and chemical features of fjord sediments ...that were explored during the AREX cruise carried out in the Svalbard archipelago in the summer of 2021. The activity rates of the enzymes leucine aminopeptidase (LAP), beta-glucosidase (GLU), and alkaline phosphatase (AP) and community-level physiological profiles (CLPPs) were studied with the aim of determining the functional diversity of the benthic microbial community, while bacterial isolates were screened for their susceptibility to antibiotics in order to explore the role of these extreme environments as potential reservoirs of antibiotic resistance. Enzyme activity rates were obtained using fluorogenic substrates, and CLPPs were obtained using Biolog Ecoplates; antibiotic susceptibility assays were performed through the standard disk diffusion method. Spatial trends observed in the functional profiles of the microbial community suggested variability in the microbial community’s composition, presumably related to the patchy distribution of organic substrates. Complex carbon sources, carbohydrates, and amino acids were the organic polymers preferentially metabolized by the microbial community. Multi-resistance to enrofloxacin and tetracycline was detected in all of the examined samples, stressing the role of sediments as a potential reservoir of chemical wastes ascribable to antibiotic residuals. This study provides new insights on the health status of fjord sediments of West Spitsbergen, applying a dual ecological and biochemical approach. Microbial communities in the fjord sediments showed globally a good functional diversity, suggesting their versatility to rapidly react to changing conditions. The lack of significant diversification among the three studied areas suggests that microbial variables alone cannot be suitable descriptors of sediment health, and that additional measures (i.e., physical–chemical characteristics) should be taken to better define environmental status.
Background Ultrasound (US) guidance provides the unique opportunity to control the puncture zone of the artery during transfemoral transcatheter aortic valve replacement and may decrease major ...vascular complications (VC) and life-threatening or major bleeding complications. This study aimed to evaluate the clinical impact of US guidance using a propensity score-matched comparison. Methods and Results US guidance was implemented as the default approach for all transfemoral transcatheter aortic valve replacement cases in our institution in June 2013. We defined 3 groups of consecutive patients according to the method of puncture (fluoroscopic/US guidance) and the use of a transcatheter heart valve. Patients in the US-guided second-generation group (Sapien XT Edwards Lifesciences, Irvine, CA, Corevalve Medtronic, Dublin, Ireland) were successfully 1:1 matched with patients in the fluoroscope-guided second-generation group (n=95) with propensity score matching. In a second analysis we described the consecutive patients of the US-guided third-generation group (Evolut-R Medtronic, Sapien 3 Edwards Lifesciences, n=308). All vascular and bleeding complications were reduced in the US-guided second-generation group compared with the fluoroscope-guided second-generation group: VC (16.8% versus 6.3%;
=0.023); life-threatening or major bleeding (22.1% versus 6%;
=0.004); and VC related to vascular access (12.6% versus 4.2%;
=0.052). In the US-guided third-generation group the rates of major VC and life-threatening or major bleeding were 3.2% (95% CI, 1.6% to 5.9%) and 3.6% (95% CI, 1.8% to 6.3%). In the overall population (n=546), life-threatening or major bleeding was associated with a 1.7-fold increased mortality risk (
=0.02). Conclusions We demonstrated that US guidance effectively reduced VC and bleeding complications for transfemoral transcatheter aortic valve replacement and should be considered the standard puncture method. Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02628509.
Polar marine environments host a complex assemblage of cold-adapted auto- and heterotrophic microorganisms that affect water biogeochemistry and ecosystem functions. However, due to logistical ...difficulties, remote regions like those in close proximity to glaciers have received little attention, resulting in a paucity of microbiological data. To fill these gaps and obtain novel insights into microbial structure and function in Arctic regions, a survey of microbial communities in an area close to the Blomstrandbreen glacier in Kongsfjorden (Svalbard Archipelago; Arctic Ocean) was carried out during an early summer period. An Unmanned Autonomous Vehicle designed to safely obtain seawater samples from offshore-glacier transects (PROTEUS, Portable RObotic Technology for Unmanned Surveys) was equipped with an automatic remotely-controlled water multi-sampler so that it could sample just beneath the glacier, where access from the sea is difficult and dangerous. The samples were analysed by image analysis for the abundance of total prokaryotes, viable and respiring cells, their morphological traits and biomass; by flow cytometry for autotrophic and prokaryotic cells (with high and low nucleic acid contents) as well as virus-like particle counts; by BIOLOG ECOPLATES for potential community metabolism; and by fluorimetry for potential enzymatic activity rates on organic polymers. Contextually, the main physical and chemical (temperature, salinity, pH, dissolved oxygen and nutrients) parameters were detected. Altogether, besides the PROTEUS vehicle’s suitability for collecting samples from otherwise inaccessible sites, the multivariate analysis of the overall dataset allowed the identification of three main sub-regions differently affected by the haline gradient (close to the glacier) or terrigenous inputs coming from the coast. A complex microbiological scenario was depicted by different patterns of microbial abundance and metabolism among the transects, suggesting that ice melting and Atlantic water inflow differently supported microbial growth.
A regression-based approach was used to test the suitability of a range of parameters, including total prokaryotic cell abundance and biomass, as lipopolysaccharide (LPS) content, and exoenzymatic ...activities (leucine aminopeptidase, LAP, beta-glucosidase, ß-G, and alkaline phosphatase, AP) as predictors of heterotrophic prokaryotic production (HPP) in the Ross Sea epipelagic waters. A close association between HPP and protein hydrolysis mediated by enzymatic activity (LAP), and to a lower significance level with the other variables, was recorded. Three multiple regression equations were developed from two microbial datasets collected during middle austral summer periods. All showed a good predictive ability for HPP, and this was further validated through a comparison between the predicted and the observed HPP values. The obtained regression equations proved to represent a promising example of empirical models for further predictive studies in the Ross Sea where—through the incorporation of additional microbiological and environmental parameters—the developed models could find a practical application to cover the entire austral summer period.
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