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Ultra high sulfate loads and iron precision dosing for hydrogen sulfide management: A mass balance assessment and microbial structure implications in anaerobic bioreactors

Wed, 01 Jan 2025 00:00:00 GMT

Título: Ultra high sulfate loads and iron precision dosing for hydrogen sulfide management: A mass balance assessment and microbial structure implications in anaerobic bioreactors Autor: Girardi, Valentina; Tondo, María Laura; Balaban, Cecilia Lucía; Herrero, María Sol; Olivera, Camila; Salvatierra, Lucas Matías Resumen: This article presents an original and detailed study of semi continuous lab-scale anaerobic bioreactors subjected to Sulfate Loads Rates (SLRs) >130 mgSO4 2− /day.Lreactor. At these sulfate inputs, hydrogen sulfide yield by bacterial conversion can reach concentrations above 400 mg/L in the liquid phase and more than 25,000 ppm in gas phase, respectively. Both values comprise significant technical challenges in biogas plants as well as health and environmental concerns. In order to control sulfide in liquid phase, two bioreactors were treated with opposite ferric dosing strategies: one underwent five consecutive cycles of shock precipitation of hydrogen sulfide, reducing peak levels from ~400 mg/L to <40 mg/L; the other involved the application of a more continuous and fine-tuned dosing strategy to manage sulfide concentrations across different stepwise levels: 400–300, 300–200, 200–100, and 100 to <10 mg/L. A third bioreactor, without iron addition, stabilized at ~250 mg/L H2S and 10,000 ppm in biogas over 140 days. A detailed sulfur mass balance enabled analysis of sulfate-to-sulfide conversion rates, Henry’s con stants between liquid and gas phases, and Fe3+/S2− molar ratios for both strategies. Values of 0.99 and 0.65 were obtained, matching with the stoichiometry of FeS during shock precipitation and FeS + S0 and/or Fe2S3 in stepwise precipitation, respectively. High-throughput sequencing of the 16S rRNA gene revealed subtle yet significant changes in the microbial community structures within bioreactors subjected to high sulfate loads and iron addition. Furthermore, the authors characterized the late-stage microbial response following methanogenic process inhibition and the cessation of biogas production.

Innovative and Healthy Cookies Enriched with Blueberry Leaf Powder

Wed, 01 Jan 2025 00:00:00 GMT

Título: Innovative and Healthy Cookies Enriched with Blueberry Leaf Powder Autor: Santuccione, Francesco Antonio; Soazo, Marina; Llopart, Emilce; Rossi, Matías; Verdini, Roxana Andrea; Pittia, Paola; Pérez, Leonardo Martín Resumen: Blueberry (Vaccinium spp.) leaves, a residual biomass of pruning, are a rich source of polyphenols, fiber, and minerals. In this study, blueberry leaf powder (BBLP) was incorporated into wheat/soy flour-based cookies to develop antioxidant- and fiber-enriched bakery products. BBLP exhibited 8.2% protein, 44% dietary fiber (predominantly insoluble), and high antioxidant activity (2109 ± 20 mg gallic acid equivalents/100 g sample; 6251 ± 42 µmol Trolox equivalents/100 g). Four cookies’ formulations were prepared by replacing 0%, 2.5%, 5.0%, and 7.5% of the flour blend with BBLP. The total phenolic content, total antioxidant content, physical properties (weight, diameter, thickness, volume, hardness, and color), chemical composition (moisture, ash, minerals, protein, carbohydrate, fat, and fiber content), and sensory properties (taste, texture, aroma, and overall acceptability) were analyzed. All BBLP-enriched cookies qualified as a “source of fiber” according to Codex Alimentarius guidelines and EU Regulation (EC) No 1924/2006 on nutrition and health claims for foods. The addition of BBLP significantly affected the cookies’ diameter, thickness, volume, and hardness, likely due to its high insoluble fiber content. Moreover, as BBLP levels increased, the surface color darkened progressively, with increased redness and decreased yellowness attributed to the presence of anthocyanins. Accordingly, BBLP-enriched cookies showed increased antioxidant capacity, proportional to the amount of BBLP added, indicating good retention of the bioactive compounds after baking. Sensory evaluation using Quantitative Descriptive Analysis revealed that cookies with 2.5% BBLP were rated with the highest acceptability scores, whereas higher concentrations imparted noticeable herbal notes and a darker color, decreasing overall acceptability. In conclusion, BBLP can be effectively incorporated at 2.5% to enhance the nutritional quality and antioxidant potential of cookies without compromising sensory appeal, contributing to sustainable food innovation by valorizing residual agricultural biomass.

Exploring ethical competence in academia: SNA of informal communication among professors to foster ethics education

Wed, 01 Jan 2025 00:00:00 GMT

Título: Exploring ethical competence in academia: SNA of informal communication among professors to foster ethics education Autor: Marín, María Alejandra; Vignale, Jorge; Gaiazzi, Pablo; Zinoni, María José; Casiello, Francisco Alejandro Resumen: Casual conversations between faculty members in places like faculty lounges and collaborative events are essential for sharing knowledge, working together, and building a sense of community within academic institutions. Social Network Analysis (SNA) of informal professor communications plays a vital role in fostering students’ ethical competence and critical skills development. It identifies influential nodes that shape the ethical discourse, to promote independent thinking and valid ethical principles, preparing students for real-world challenges. In the contemporary landscape of academia, fostering ethical competence among professors is a paramount objective. Ethical dilemmas often permeate scholarly pursuits, necessitating a comprehensive understanding of ethical principles and effective communication channels for their dissemination. This study proposes an innovative approach to address this imperative: employing SNA to examine informal communication patterns among professors within academic institutions in a collaborative manner. By leveraging SNA, this research aims to elucidate the intricate web of informal interactions among faculty members and identify central figures or clusters that influence ethical discourse within academic circles. Through a mixed-methods approach integrating quantitative metrics and qualitative insights, the study seeks to uncover hidden dynamics, influential nodes, and information flow patterns within the social fabric of academia. By elucidating the informal networks through which ethical norms and values are transmitted, institutions can develop targeted interventions to enhance ethical competence among faculty members.

Overcoming the ring tension: computational approaches to stereochemical assignments and geometrical insights in small heterocycles

Wed, 01 Jan 2025 00:00:00 GMT

Título: Overcoming the ring tension: computational approaches to stereochemical assignments and geometrical insights in small heterocycles Autor: Luciano, Ezequiel R.; Amichetti, Milagros; Sarotti, Ariel M.; Zanardi, María M. Resumen: In this study, we evaluate the performance of the DP4+ and MM-DP4+ methods on molecules featuring small heterocyclic rings. A dataset of 71 molecules containing three- and four-membered heterocycles, known for their stereochemical assignment challenges, was analyzed. We compared molecular geometries optimized at different computational levels, including MMFF and B3LYP/6-31G*, to assess deviations in key geometric parameters relative to the heterocycle structures. Furthermore, the geometric properties of these molecules were investigated using various force fields to evaluate their differences. Our aim was to assess the reliability of B3LYP/6-31G* in comparison with more accurate methods and to elucidate how different force fields influence in geometric precision.