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The CO 2 bioelectromethanosynthesis via two-chamber microbial electrolysis cell (MEC) holds tremendous potential to solve the energy crisis and mitigate the greenhouse gas emissions. However, the membrane fouling is still a big challenge for CO 2 bioelectromethanosynthesis owing to the poor proton diffusion across membrane and high inter-resistance. In this study, a new MEC bioreactor with biogas recirculation unit was designed in the cathode chamber to enhance secondary-dissolution of CO2 while mitigating the contaminant adhesion on membrane surface. Biogas recirculation improved CO 2 re-dissolution, reduced concentration polarization, and facilitated the proton transmembrane diffusion. This resulted in a remarkable increase in the cathodic methane production rate from 0.4 mL/L·d to 8.5 mL/L·d. A robust syntrophic relationship between anodic organic-degrading bacteria (Firmicutes 5.29%, Bacteroidetes 25.90%, and Proteobacteria 6.08%) and cathodic methane-producing archaea (Methanobacterium 65.58%) enabled simultaneous organic degradation, high CO 2 bioelectromethanosynthesis, and renewable energy storage. [Display omitted] • The biogas circulation unit was introduced in MECs to prevent membrane fouling. • Great increase in cathode methane yield was achieved due to the biogas unit. • Shear-scouring effect reduced proton exchange membrane contamination. • Biodegradation of organic matters supplied the sufficient e−/H+ for CO 2 methanation. • Microbial symbiosis enabled organic degradation, and simultaneous CO 2 methanation. [ABSTRACT FROM AUTHOR]

The mystery of appendage regeneration has fascinated humans for centuries, while the underlying regulatory mechanisms remain unclear. In this study, we establish a transcriptional landscape of regenerating leg in the American cockroach, Periplaneta americana , an ideal model in appendage regeneration studies showing remarkable regeneration capacity. Through a large-scale in vivo screening, we identify multiple signaling pathways and transcription factors controlling leg regeneration. Specifically, zfh-2 and bowl contribute to blastema cell proliferation and morphogenesis in two transcriptional cascades: bone morphogenetic protein (BMP)/JAK-STAT- zfh-2-B-H2 and Notch- drm/bowl-bab1. Notably, we find zfh-2 is working as a direct target of BMP signaling to promote cell proliferation in the blastema. These mechanisms might be conserved in the appendage regeneration of vertebrates from an evolutionary perspective. Overall, our findings reveal that two crucial transcriptional cascades orchestrate distinct cockroach leg regeneration processes, significantly advancing the comprehension of molecular mechanism in appendage regeneration. [Display omitted] • A transcriptional profile of regenerating leg was established in cockroach • Multiple signaling pathways and transcription factors are required for leg regeneration • Two transcriptional cascades orchestrate blastema cell proliferation and morphogenesis Cockroaches serve as excellent insect models for investigating innovative regenerative processes due to their extraordinary regenerative capabilities. Ren et al. demonstrate how two transcriptional cascades, formed with signaling pathways and transcription factors known as BMP/JAK-STAT- zfh-2-B-H2 and Notch- drm/bowl-bab1 , orchestrate blastema cell proliferation and morphogenesis processes in cockroach leg regeneration. [ABSTRACT FROM AUTHOR]

Each carbon-based material, due to the discrepancy in critical properties, has distinct capability to enrich electroactive microbes able to electrosynthesize methane from CO 2 . To optimize electromethanogenesis process, this study physically prepared and examined several carbon-based cathode materials: carbon stick (CS), CS twined by Ti wire (CS-Ti) or covered with carbon fiber (CS-CF), graphite felt (CS-GF) and carbon cloth (CS-CC). CS-GF electrode had constantly stable methane production (75.8 mL/L/d at −0.9 V vs. Ag/AgCl) while CS-CC showed a suppressed performance over time caused by the desposition of inorganic shell. Electrode material properties affected biofilms growth, cell-electrode contact behaviors and electron exchange. Methane formation with CS-CC biocathode was H 2 -concnetration dependent; CS-GF cathode possessed high antifouling properties and extensive space, enriching the microorganisms capable of catalyzing electromethanogenesis through more efficient non-H 2 route. This study re-interpreted the application potentials of carbon-based materials in CO 2 electroreduction and electrofuel recovery, providing valuable guidance for materials’ selection. [ABSTRACT FROM AUTHOR]

The CO 2 concentration of a Tianjin primary school classroom is measured in winter. The average values reach 1904 ppm and 2415 ppm near the end of the first and second lessons, respectively. Hence, to meet the primary standard of 1000 ppm from "Specification of indoor air quality for classroom of elementary and secondary school" (T/CAQI27-2017), a new energy saving ventilation system assisted by transpired solar air collectors is proposed. The energy saving ventilation system is comprehensively analyzed not only in term of ventilation effect but also in terms of energy savings, environmental protection and economic effects. The conclusions demonstrate that the indoor average values of CO 2 concentration for the new system are all reduced to below 1000 ppm in November, December, January, February and March, according to the data provided by Tianjin Eco-Environmental Monitoring Center from 2011 to 2013. The average value of hourly solar fractions can be as high as 34.3% over a heating season. Although the economic effect of the new system is not the best, both its energy saving effect and environmental protection effect are significant. • An energy saving ventilation system using solar air heating technology is proposed. • Indoor average CO 2 concentrations in whole winter are all reduced to below 1000 ppm. • Average value of hourly solar fraction can be as high as 34.3% over a heating season. • A comprehensive analysis of the new system is made compared to three other systems. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Current status of MECs for CO 2 electromethanogenesis was summarized. • The working principles of CO 2 electromethanogenesis were summarized. • Several test methods was proposed to analyze the properties. • The critical factors effecting CH 4 production have been discussed. Abstract Given the aggravated greenhouse effect caused by CO 2 and the current energy shortage, CO 2 capture and reuse has been gaining ever-increasing concerns. Microbial Electrolysis Cells (MECs) has been considered to be a promising alternative to recycle CO 2 bioelectrochemically to low-carbon electrofuels such as CH 4 by combining electroactive microorganisms with electrochemical stimulation, enabling both CO 2 fixation and energy recovery. In spite of the numerous efforts dedicated in this field in recent years, there are still many problems that hinder CO 2 bioelectroconversion technique from the scaling-up and potential industrialization. This review comprehensively summarized the working principles, extracellular electron transfers behaviors, and the critical factors limiting the wide-spread utilization of CO 2 electromethanogenesis. Various characterization and electrochemical testing methods for helping to uncover the underlying mechanisms in CO 2 electromethanogenesis have been introduced. In addition, future research needs for pushing forward the development of MECs technology in real-world CO 2 fixation and recycling were elaborated. [ABSTRACT FROM AUTHOR]

Relative to the easier removal of accumulated dust on the outside of solar devices, it's very difficult to clean up the internal dust particles. So, from the aspect of ensuring the long-term high-performance operation of transpired solar air collector, the paper investigates the tilt angle effects on the dust accumulation amount of glazing cover inner surface and associated reduction in collector performance. In process, various forces causing the dust particles move to the inner surface and collide with them and then deposit, are thoroughly analyzed. To estimate the heat collected loss induced by dust, an empirical relationship predicting the light transmittance reduction has been explored, valid for relatively small dust accumulation amount. The results indicate that mainly under the force of gravity, the dust deposition density on the inner surface increases with the tilt angle. However, in view of the difference of solar irradiance in five tilt angles at the same time, it is not that the higher the dust deposition density, the lower the temperature rise from collector inlet to outlet. Hence, the tilt angle should be determined based on the comprehensive evaluation of the resulting changes of solar irradiance and dust accumulation amount, combined with local meteorological conditions. [ABSTRACT FROM AUTHOR]