Optimizing electrochemically active microorganisms as a key player in the bioelectrochemical system: Identification methods and pathways to large-scale implementation.

The rapid global economic growth driven by industrialization and population expansion has resulted in significant issues, including reliance on fossil fuels, energy scarcity, water crises, and environmental emissions. To address these issues, bioelectrochemical systems (BES) have emerged as a dual-purpose solution, harnessing electrochemical processes and the capabilities of electrochemically active microorganisms (EAM) to simultaneously recover energy and treat wastewater. This review examines critical performance factors in BES, including inoculum selection, pretreatment methods, electrodes, and operational conditions. Further, authors explore innovative approaches to suppress methanogens and simultaneously enhance the EAM in mixed cultures. Additionally, advanced techniques for detecting EAM are discussed. The rapid detection of EAM facilitates the selection of suitable inoculum sources and optimization of enrichment strategies in BESs. This optimization is essential for facilitating the successful scaling up of BES applications, contributing substantially to the realization of clean energy and sustainable wastewater treatment. This analysis introduces a novel viewpoint by amalgamating contemporary research on the selective enrichment of EAM in mixed cultures. It encompasses identification and detection techniques, along with methodologies tailored for the selective enrichment of EAM, geared explicitly toward upscaling applications in BES.

Tailoring a highly conductive and super-hydrophilic electrode for biocatalytic performance of microbial electrolysis cells.

Bioelectrochemical hydrogen production via microbial electrolysis cells (MECs) has attracted attention as the next generation of technology for the hydrogen economy. MECs work by electrochemically active bacteria reducing organic compounds at the anode. However, the hydrophobic nature of carbon-based anodes suppresses the release of the produced gas and water penetration, which significantly reduces the possibility of microbial attachment. Consequently, a limited surface area of the anode is used, which decreases hydrogen production efficiency. In this study, the bifunctional material poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) was applied to the surface of a three-dimensional carbon felt anode to enhance the hydrogen production efficiency of an MEC owing to the high conductivity of PEDOT and super-hydrophilicity of PSS. In experiments, the PEDOT:PSS-modified anode almost doubled the hydrogen production efficiency of the MEC compared with the control anode owing to the increased capacitance current (239.3 %) and biofilm formation (220.7 %). The modified anode reduced the time required for the MEC to reach a steady state of hydrogen production by 14 days compared to the control anode. Microbial community profiles demonstrated that the modified anode had a greater abundance of electrochemically active bacteria than the control anode. This simple method could be widely applied to various bioelectrochemical systems (e.g., microbial fuel cells and solar cells) and to scaling up MECs.

The Relationship between Future Anxiety Due to COVID-19 and Vigilance: The Role of Message Fatigue and Autonomy Satisfaction.

How does future anxiety caused by the COVID-19 pandemic relate to people's willingness to remain vigilant and adhere to preventive measures? We examined the mediating role of message fatigue and the moderating role of autonomy satisfaction in the relationship between future anxiety due to COVID-19 and willingness to remain vigilant. A cross-sectional online survey was conducted with adults residing in the United States in June 2021 when numerous U.S. states re-opened following the CDC's relaxed guidelines for fully vaccinated individuals. Our data showed that message fatigue mediated the relationship between future anxiety due to the pandemic and willingness to remain vigilant. The data further revealed that autonomy satisfaction significantly moderated the mediation. Namely, the role of message fatigue in the indirect relationship between future anxiety and willingness to remain vigilant was significant only among people low to moderate in autonomy satisfaction; its role in the indirect path was not significant for those high in autonomy satisfaction. Notably, independent of the mechanism involving message fatigue, future anxiety was directly and positively associated with willingness to remain vigilant regardless of the levels of autonomy satisfaction. Implications of these findings are discussed in light of psychological and behavioral responses to the current pandemic and policy directions.

Scalability of microbial electrochemical technologies: Applications and challenges.

During wastewater treatment, microbial electrochemical technologies (METs) are a promising means for in situ energy harvesting and resource recovery. The primary constraint for such systems is scaling them up from the laboratory to practical applications. Currently, most research (∼90%) has been limited to benchtop models because of bioelectrochemical, economic, and engineering design limitations. Field trials, i.e., 1.5 m3 bioelectric toilet, 1000 L microbial electrolysis cell and industrial applications of METs have been conducted, and their results serve as positive indicators of their readiness for practical applications. Multiple startup companies have invested in the pilot-scale demonstrations of METs for industrial effluent treatment. Recently, advances in membrane/electrode modification, understanding of microbe-electrode interaction, and feasibility of electrochemical redox reactions have provided new directions for realizing the practical application. This study reviews the scaling-up challenges, success stories for onsite use, and readiness level of METs for commercialization that is inexpensive and sustainable.

Tracking microbial community shifts during recovery process in overloaded anaerobic digesters under biological and non-biological supplementation strategies.

Anaerobic digestion encounters operational instability due to fluctuations in organic loading. Propionic acid (HPr) is frequently accumulated due to its unfavorable reaction thermodynamics. Here, 'specific' bioaugmentation using HPr enrichment cultures (three different injection regimes of quantity and frequency) was compared with 'non-specific' bioaugmentation using anaerobic sludge, and with non-biological supplementation of magnetite or coenzyme M. The specific bioaugmentation treatments showed superior recovery responses during continuous feeding after a peak overload. A 'one-shot' bioaugmentation with enrichment showed the best remediation, with ~25% recovery time and >10% CH4 conversion efficiency compared to the control. Consecutive bioaugmentation showed evidence of increased stability of the introduced community. Families Synergistaceae, Syntrophobacteraceae, and Kosmotogaceae were likely responsible for HPr-oxidation, in potential syntrophy with Methanoculleus and Methanobacterium. The different supplementation strategies can be considered to reduce the effect of start-up or overload in anaerobic digesters based on the availability of supplementation resources.

A review on self-sustainable microbial electrolysis cells for electro-biohydrogen production via coupling with carbon-neutral renewable energy technologies.

Microbial electrolysis cell (MEC) technology is a promising bioelectrochemical hydrogen production technology that utilizes anodic bio-catalytic oxidation and cathodic reduction processes. MECs require a lower external energy input than water electrolysis; however, as they also require the application of external power sources, this inevitably renders MEC systems a less sustainable option. This issue is the main obstacle hindering the practical application of MECs. Therefore, this review aims to introduce a self-sustainable MEC technology by combining conventional MECs with advanced carbon-neutral technologies, such as solar-, microbial-, osmotic-, and thermoelectric-powers (and their combinations). Moreover, new approaches to overcome the thermodynamic barriers and attain self-sustaining MECs are discussed in detail, thereby providing a working principle, current challenges, and future perspective in the field. This review provides comprehensive insights into reliable hydrogen production as well as the latest trends towards self-sustainable MECs for practical application.

Methanogenesis stimulation and inhibition for the production of different target electrobiofuels in microbial electrolysis cells through an on-demand control strategy using the coenzyme M and 2-bromoethanesulfonate.

Electron allocation through the suppression or the stimulation of methanogenesis is critical for microbial electrolysis cells (MECs) to produce the desired target product (e.g., CH4 or H2). In this study, selective methanogenesis control using the coenzyme M (CoM) and 2-bromoethanesulfonate (2-BES) was investigated in a two-chambered MEC to evaluate the effect of CoM and 2-BES on the production of different electrobiofuels, net energy conversion efficiency and microbial community structure. Because the CoM is a crucial methyl-group carrier in the final process of methanogenesis, it was postulated that CoM would stimulate methanogenic activity at the anode, while a structural analog of the CoM (i.e., 2-BES) was expected to improve cathodic H2 yield using electrons conserved because of methanogen inhibition (electron equivalence: 8 mol e- = 1 mol CH4 = 4 mol H2). CoM injection in MECs significantly enhanced their CH4 production rate, purity, and yield by 4.5-fold, 14.5%, and 76.1%, respectively, compared to the control. Moreover, microbial community analysis indicated that Methanosaeta, the major acetoclastic methanogen, continued to dominate the microbial community but steadily decreased in relative abundance after the CoM injection. On the other hand, drastic increases in hydrogenotrophic methanogens, such as Methanoculleus and Methanolinea, were observed along with potential syntrophic acetate-oxidizing bacteria. In contrast, CH4 production in the 2-BES injected trials was significantly inhibited by 79.5%, resulting in a corresponding increase of H2 production by 145.5% compared to the control. Unlike the CoM, the microbial community did not noticeably change when 2-BES was injected, although the population size gradually decreased over time. Also, a single injection of CoM and 2-BES, even at low concentrations (500 µM), enabled the desired allocation of electrons as characterized by a high sensitivity, fast response, and negligible interference. In terms of energy conversion efficiency, methanogenesis stimulation approach resulted in higher net energy production than inhibition approach, whereas the remained electrons were not fully converted to hydrogen in case of the inhibition trial, thus producing less energy.

Hooked on Facebook: The Role of Social Anxiety and Need for Social Assurance in Problematic Use of Facebook.

There is a growing concern that excessive and uncontrolled use of Facebook not only interferes with performance at school or work but also poses threats to physical and psychological well-being. The present research investigated how two individual difference variables--social anxiety and need for social assurance--affect problematic use of Facebook. Drawing on the basic premises of the social skill model of problematic Internet use, we hypothesized that social anxiety and need for social assurance would be positively correlated with problematic use of Facebook. Furthermore, it was predicted that need for social assurance would moderate the relationship between social anxiety and problematic use. A cross-sectional online survey was conducted with a college student sample in the United States (N=243) to test the proposed hypotheses. Results showed that both social anxiety and need for social assurance had a significant positive association with problematic use of Facebook. More importantly, the data demonstrated that need for social assurance served as a significant moderator of the relationship between social anxiety and problematic Facebook use. The positive association between social anxiety and problematic Facebook use was significant only for Facebook users with medium to high levels of need for social assurance but not for those with a low level of need for social assurance. Theoretical and practical implications of these findings were discussed.

"Whose second life is this?" How avatar-based racial cues shape ethno-racial minorities' perception of virtual worlds.

Research on social identity contingencies suggests that situational cues, such as a numerical representation of social identities in a given social environment, can trigger identity-associated threat for individuals whose social identity is marginalized. Given that popular virtual worlds (e.g., Second Life [SL]) are often criticized for White-avatar dominance or White bias, we examined the psychological effects of the alleged White dominance in avatar-based virtual worlds by conducting two experiments in which participants read fictitious profiles of SL resident avatars. White and non-White participants were randomly assigned to view either a set of White-dominant avatar profiles or a set of racially diverse ones. After reading the profiles, participants had an opportunity to customize avatars using the SL interface. The findings of Experiment 1 (n=59) revealed that non-White participants exposed to the White-dominant avatar profiles, when compared with those exposed to the racially diverse profiles, reported significantly lower levels of sense of belonging and intention to participate in SL. Experiment 2 (n=64) demonstrated that non-White participants exposed to the White-dominant avatar profiles gave significantly higher estimation of the White user population within SL; the data also showed that exposure to the White-dominant avatar profiles resulted in a greater sense of limitation on skin customization among non-White participants than among White participants. The present research suggests that ethno-racial minorities, when exposed to avatar-based cues that signal White dominance, may perceive the virtual world as identity threatening, thereby feeling psychologically disconnected and detached from it. Implications regarding racial/ethnic diversity in virtual worlds are discussed.