Strategy for managing industrial anaerobic sludge through the heterotrophic cultivation of chlorella sorokiniana: Effect of iron addition on biomass and lipid production

Microalgae provides an alternative for the valorization of industrial by-products, in which the nutritional content varies substantially and directly affects microalgae system performance. Herein, the heterotrophic cultivation of Chlorella sorokiniana was systematically studied, allowing us to detect a nutritional deficiency other than the carbon source through assessing the oxygen transfer rate for glucose or acetate fermentation. Consequently, a mathematical model of the iron co-limiting effect on heterotrophic microalgae was developed by exploring its ability to regulate the specific growth rate and yield. For instance, higher values of the specific growth rate (0.17 h−1 ) compared with those reported for the heterotrophic culture of Chlorella were obtained due to iron supplementation. Therefore, anaerobic sludge from an industrial wastewater treatment plant (a baker’s yeast company) was pretreated to obtain an extract as a media supplement for C. sorokiniana. According to the proposed model, the sludge extract allowed us to supplement iron values close to the growth activation concentration (KFe ~12 mg L−1). Therefore, a fed-batch strategy was evaluated on nitrogen-deprived cultures supplemented with the sludge extract to promote biomass formation and fatty acid synthesis. Our findings reveal that nitrogen and iron in sludge extract can supplement heterotrophic cultures of Chlorella and provide an alternative for the valorization of industrial anaerobic sludge

The correlation between photometric variability and radial velocity jitter, based on TESS and HARPS observations

The current and upcoming high precision photometric surveys such as TESS, CHEOPS, and PLATO will provide the community with thousands of new exoplanet candidates. As a consequence, the presence of such a correlation is crucial in selecting the targets with the lowest RV jitter for efficient RV follow-up of exoplanetary candidates. Studies of this type are also crucial to design optimized observational strategies to mitigate RV jitter when searching for Earth-mass exoplanets. Our goal is to assess the correlation between high-precision photometric variability measurements and high-precision RV jitter over different time scales. We analyze 171 G, K, and M stars with available TESS high precision photometric time-series and HARPS precise RVs. We derived the stellar parameters for the stars in our sample and measured the RV jitter and photometric variability. We also estimated chromospheric Ca II H $\&$ K activity indicator $log(R' _{HK})$, $\textit{v sin i}$, and the stellar rotational period. Finally, we evaluate how different stellar parameters and a RV sampling subset can have an impact on the potential correlations. We find a varying correlation between the photometric variability and RV jitter as function of time intervals between the TESS photometric observation and HARPS RV. As the time intervals of the observations considered for the analysis increases, the correlation value and significance becomes smaller and weaker, to the point that it becomes negligible. We also find that for stars with a photometric variability above 6.5 ppt the correlation is significantly stronger. We show that such a result can be due to the transition between the spot-dominated and the faculae-dominated regime. We quantified the correlations and updated the relationship between chromospheric Ca II H $\&$ K activity indicator $log(R' _{HK})$ and RV jitter.Comment: Accepted for publication in section 10. Planets and planetary systems of A&

Auctions for Renewable Energy Support II - First insights and results of the Horizon2020 project AURES II

This is the final version. Available from Funcas via the link in this recordThe Horizon2020 project AURES II aims at ensuring the effective implementation of auctions for renewable energies in the EU Member States (MS). In recent years, auction schemes for the allocation of support for renewable electricity sources (RES) have been advancing rapidly across Europe. Auctions are considered to have brought down support levels and increased planning capability for RES deployment and state budgets. In some unfortunate cases, they have, however, also resulted in delayed or unrealised projects and increased uncertainty for project developers. A variety of auction designs are still being tested and introduced in EU MS, as well as foreseen by European legislation. Therefore, there is still a need for further assessment and improvement of national auction design and implementation to ensure the future success of RES auctions in Europe. Applying different qualitative and quantitative methods in the various work packages (WPs), the AURES II project partners have already drafted and published a large number of reports and studies. This article aims at comprehensively presenting these results and provide a first overview.European Union Horizon 202

Voltammetric study of aminopurines on pencil graphite electrode in the presence of copper ions

Electrochemical oxidations of aminopurines (adenine, 2-aminopurine, 2,6-diaminopurine) and their complexes with Cu(I) on a pencil graphite electrode were investigated by means of linear sweep voltammetry (LSV) and elimination voltammetry with linear scan (EVLS). The anodic process of the Cu(I)-aminopurine complex, corresponding to the oxidation of Cu(I) to Cu(II), takes place in the potential range between 0.4 and 0.5 V (vs. Ag/AgCl/3 M KCl). At more positive potentials the aminopurines provide voltammetric peaks resulting from the oxidation of the purine ring. The stability of the accumulated complex layer was investigated by the adsorptive transfer stripping technique. © 2010 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim