Cultivation of hydrocarbon-tolerant microalgae in flowback wastewaters produced during hydrofracking of impermeable rocks

Huge amounts of Wastewaters (WWs) are produced yearly by the hydrofracking of impermeable rock formations for the extraction of oil or natural gas. Flowback Wastewaters (FWs) are characterized by high contents of inorganic contaminants and hydrocarbons thus representing a relevant threat for the environment. In this work three hydrocarbon-tolerant microalgae have been cultivated in flowback water generated during hydraulic fracturing to investigate their growth kinetics. All three strains could grow in FWs irrespective of the presence of oil hydrocarbons. Biomass productivity varied significantly among the strains. Ochromonas danica achieved a specific growth rate equal to 0.386 day-1 during the exponential phase and a maximum biomass productivity equal to 39 mg L-1 day-1 after 11 days of batch cultivation. Scenedesmus dimorphus was capable to grow in the FWs by achieving a biomass concentration equal to 0.5 g L-1 after about 25 days of cultivation. On the contrary, Prototheca zopfii was strongly affected by the contaminants of FWs. Ultimately, this study demonstrated that specific strains of microalgae could thrive in FWs and thus represent suitable candidates to future research activity aimed to verify the possibility to bio-remediate these harmful WWs

An empirical study of social networks metrics in object-oriented software

We study the application to object-oriented software of new metrics, derived from Social Network Analysis. Social Networks metrics, as for instance, the EGO metrics, allow to identify the role of each single node in the information flow through the network, being related to software modules and their dependencies. These metrics are compared with other traditional software metrics, like the Chidamber-Kemerer suite, and software graph metrics. We examine the empirical distributions of all the metrics, bugs included, across the software modules of several releases of two large Java systems, Eclipse and Netbeans. We provide analytical distribution functions suitable for describing and studying the observed distributions. We study also correlations among metrics and bugs. We found that the empirical distributions systematically show fat-tails for all the metrics. Moreover, the various metric distributions look very similar and consistent across all system releases and are also very similar in both the studied systems. These features appear to be typical properties of these software metrics

Multi-phase outflows in Mkn 848 observed with SDSS-MaNGA Integral Field Spectroscopy

The characterisation of galaxy-scale outflows in terms of their multi-phase nature, amount, and effects of flowing material is crucial to place constraints on models of galaxy evolution. This study can proceed only with the detailed investigation of individual targets. We present a spatially resolved spectroscopic optical data analysis of Mkn 848, a complex system consisting of two merging galaxies at z~0.04 that are separated 7.5 kpc (projected distance). Motivated by the presence of a multi-phase outflow in the north-west system revealed by the SDSS integrated spectrum, we analysed the publicly available MaNGA data, which cover almost the entire merging system, to study the physical properties of cool and warm gas in detail. Galaxy-wide outflowing gas in multiple phases is revealed for the first time in the two merging galaxies. We also detect spatially resolved resonant NaID emission associated with the outflows. The derived outflow energetics may be consistent with a scenario in which both winds are accelerated by stellar processes and AGN activity, although we favour an AGN origin given the high outflow velocities and the ionisation conditions observed in the outflow regions. Deeper observations are required, however, to better constrain the nature of these multi-phase outflows. Outflow energetics in the north-west system are strongly different between the ionised and atomic gas components, the latter of which is associated with mass outflow rate and kinetic and momentum powers that are 1-2 dex higher; those associated with the south-east galaxy are instead similar. Strong kp-scale outflows are revealed in an ongoing merger system, suggesting that feedback can potentially impact the host galaxy even in the early merger phases. The characterisation of the neutral and ionised gas phases has proved to be crucial for a comprehensive study of the outflow phenomena.Comment: 19 pages, 14 figures, accepted for publication in A&

Structured population balances to support microalgae-based processes: Review of the state-of-art and perspectives analysis

Design and optimization of microalgae processes have traditionally relied on the application of unsegregated mathematical models, thus neglecting the impact of cell-to-cell heterogeneity. However, there is experimental evidence that the latter one, including but not limited to variation in mass/size, internal composition and cell cycle phase, can play a crucial role in both cultivation and downstream processes. Population balance equations (PBEs) represent a powerful approach to develop mathematical models describing the effect of cell-to-cell heterogeneity. In this work, the potential of PBEs for the analysis and design of microalgae processes are discussed. A detailed review of PBE applications to microalgae cultivation, harvesting and disruption is reported. The review is largely focused on the application of the univariate size/mass structured PBE, where the size/mass is the only internal variable used to identify the cell state. Nonetheless, the need, addressed by few studies, for additional or alternative internal variables to identify the cell cycle phase and/or provide information about the internal composition is discussed. Through the review, the limitations of previous studies are described, and areas are identified where the development of more reliable PBE models, driven by the increasing availability of single-cell experimental data, could support the understanding and purposeful exploitation of the mechanisms determining cell-to-cell heterogeneity

Mechanochemical Treatment of Soils Contaminated by Heavy Metals in Attritor and Impact Mills: Experiments and Modeling

An integrative approach was developed to support the scale-up from lab-into pilot-scale mechano-chemical reactors for immobilize heavy metals in contaminated mining soil

A new model-aided approach for the design of packed columns for CO2 absorption in aqueous NH3 solutions

A novel model-based approach to design packed beds for CO2 absorption with NH3 is proposed and experimentally validated. The two-film theory is adopted to model gas/liquid mass transfer while the thermodynamic equilibrium among ion species is considered in the liquid. Such strategy allows to simulate both CO2 absorption and NH3 evaporation, that represent the most important aspects to improve capture efficiency and process cost-effectiveness. The resulting ODEs system is a two boundary-value problem which is solved by means of the shooting method. The model is then exploited to develop a new algorithm that, based on the adopted operating conditions, evaluates the packed bed height as a function of the desired capture efficiency. The height calculated for different combinations of operating conditions is successfully compared with the real height of the experimental column, thus confirming the reliability of the developed tool which can be run with very low computational loads

Osmotic injury and cytotoxicity for hMSCs in contact with Me2SO: The effect of cell size distribution

The paper discusses the impact of cell size on cytotoxicity and expansion lysis during the osmotic excursions resulting from the contact of hMSCs from UCB with Me2SO. It builds upon the mathematical model recently presented by the authors, which pertains to a population of cells with uniform size. The objective is to enhance the model's relevance by incorporating the more realistic scenario of cell size distribution, utilizing a Population Balance Equations approach. The study compares the capability of the multiple-sized model to the single-sized one to describe system behavior experimentally measured through cytofluorimetry and Coulter counter when, first, suspending hMSCs in hypertonic solutions of Me2SO (at varying osmolality, system temperature, and contact times), and then (at room temperature) pelleting by centrifugation before suspending the cells back to isotonic conditions. Simulations demonstrate that expansion lysis and cytotoxic effect are not affected by cell size for the specific system hMSCs/Me2SO, thus confirming what was found so far by the authors through a singlesize model. On the other hand, simulations show that, when varying the adjustable parameters of the model that are expected to change from cell to cell lineages, expansion lysis is sensitive to cell size, while cytotoxicity is not, being mainly influenced by external CPA concentration and contact duration. More specifically, it is found that smaller cells suffer expansion lysis more than larger ones. The findings suggest that different cells from hMSCs may require a multiple-sized model to assess cell damage during osmotic excursions in cryopreservation

Effects of a novel bioprocess for the cultivation Synechococcus nidulans on Mars on its biochemical composition: focus on the lipidome

In the present work, the possibility to grow the strain Synechococcus nidulans CCALA 188 on Mars using a medium mimicking a one obtainable using in situ available resources, i.e. the so-called Martian medium, under an atmosphere obtainable by pressurization of Mars CO2, is investigated. The goal is to obtain a biomass with high-value products to sustain a crewed mission to Mars. The results show that the replacement of 40% vol of Z-medium with the same volume of Martian medium does not affect the cultivation and leads to a slight improvement of biomass productivity. Under an atmosphere consisting of pure CO2 the growth rate was reduced but the strain managed to adapt by modifying its metabolism. Total proteins and carbohydrates were significantly reduced under Mars-like conditions, while lipids increased when using CO2. A balanced diet rich in antioxidants is crucial for the wealth of astronauts, and in our case, radical scavenging capacities range from 15 to 20 mmol(TEAC)/kg were observed. Under CO2, a reduction in antioxidant power is observed likely due to a decrease in photosynthetic activity. The lipidome consisted of sulfoquinovosyldiacylglycerol, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylcholine, phosphatidylglycerol, and triacylglycerol. A significant increase in the latter ones was observed under Mars simulated atmosphere