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An acid–base junction flow battery (ABJFB) is a new type of energy conversion system using neutralization and water dissociation in the presence of acid and base electrolytes. The bipolar membrane (BPM) is a core component in determining the performance of the ABJFB. In particular, the development of an anion exchange layer (AEL) is essential to improve the performance of the BPM. In the present study, we fabricated a novel BPM composed of aligned ion channels of a quaternary aminated poly (2,6-dimethyl-1,4-phenylene oxide) (QPPO) layer and a pellicle of the cation exchange layer (CEL). The results showed that the through-plane conductivity of the QPPO membrane prepared under an AC electric field improved from 26.78 to 120.83 mS cm−1, owing to the aligned ion channels. The fabricated BPM based on the aligned QPPO membrane showed the remarkably improved performance of water dissociation and neutralization reactions in the presence of acid and base electrolytes without delamination. The ABJFB assembled with the optimized BPM showed a high power density of 3.85 mW cm−2 under a high strength acid/base of 2 N H2SO4 and NaOH solutions. In addition, we first performed a long-term operation of 60 cycles with a high coulombic efficiency of 98.9%, energy efficiency of 55.5%, and voltage efficiency of 56.1% under 2 N H2SO4 and NaOH at a high current density of 4 mA cm−2.

In the current study, Polyimide (P84)-based polymeric membranes were fabricated and used as spargers in the bubble column reactor (BCR) to get a high gas-liquid mass transfer (GL-MT) rate of oxygen in water. Different polymeric membranes were fabricated by incorporating polyvinyl pyrrolidone (PVP) as a porogen and a Zeolitic Imidazolate Framework (ZIF-8) to induce high porosity and hydrophobicity in the membranes. The GL-MT efficiency of membranes was evaluated by measuring the overall volumetric mass transfer coefficient (k

Reverse osmosis (RO) membrane biofouling is a critical issue in seawater desalination. However, biofouling characteristics are not fully understood owing to the complex structure of the fouling layer. Therefore, the objective of this study is to investigate how the biofouling characteristics of RO membranes are associated with bacterial and archaeal communities and their physiological (surface structure, elemental composition, and thickness) and metabolic characteristics in different locations of the RO membrane element. Raw seawater, feedwater, first- and last-located RO membrane elements, and brine were collected from a full-scale (50 m3 per day) intermittently operated seawater reverse osmosis (SWRO) desalination plant. Bacteria were found to be the most dominant biofouling microorganism on the RO membrane surface rather than archaea or diatoms. This study highlights that the very first element of the RO membrane receiving inflow had fouled biofilm with more heterogeneous morphologies and chemical composition compared with the very last element of the RO membrane where the outflow is discharged. In contrast, the microbial communities in both biofilms were similar to each other during the period of desalination operation. The most dominant bacterial species in the biofilm of RO membranes were Pelagibius, Parvibaculum, Legionella, Hyphomicrobium, and Sphingomonas. Moreover, their physiological and metabolic characteristics, such as salt tolerance, high pressure tolerance, and/or oligotrophic properties may provide advantages for their adaptation and dominance in RO membrane biofilms. A substantial difference in microbial diversity was observed between the feedwater and RO membranes, suggesting that more attention should be given to the biofilm, rather than the feedwater, when investigating how biofouling is developed and eventually controlled.

A packed-bed reactor (PBR) which has recyclable internal gas and medium exchange functions for carbon monoxide (CO) fermentation was operated using an ethanol producing acetogen, Clostridium autoethanogenum DSM 10061. The PBR was designed to circulate the headspace gas, so as to achieve a higher volumetric gas–liquid mass transfer coefficient (kLa). Periodic medium exchange was performed to avoid nutrient limitations. The CO utilization rate and ethanol productivity were maximized when the medium exchange ratio was held constant, and varied linearly with the gas circulation rate. The PBR operation using 2× medium composition resulted in maximum 16.1 g L−1 ethanol titer and 0.13 g L−1 h−1 productivity. Consistent ethanol production was achieved throughout the reactor runs, confirming the stability of the PBR operation. The cost effectiveness of the PBR operation was determined based on the medium prices and the ethanol titer. The most realistic operation parameters were 0.01 h−1 (mean dilution rate) and 1.5 vvm (gas circulation rate) using 12.6 times the nutrient reinforced medium.

Bioethanol has garnered a great interest as a potential energy source, mainly due to its sustainable and green nature. Generally, bioethanol is produced through the microbial conversion of biomass and biomass derived syngas. However, the dehydration and purification steps for achieving fuel-grade ethanol from the microbial production process consume tremendous amounts of energy. This high energy consumption limits the feasibility of microbial ethanol production on the commercial scale. In this context, selection of an optimal technology for product separation is essential for successful commercialization of microbially produced bioethanol. This article presents the recent developments in dehydration and purification technologies for bioethanol production using distillation and membrane based separation. Distillation and pervaporation are analyzed on the basis of the overall energy requirement, consumption, and economics. Pervaporation-assisted distillation approaches are also examined from the perspective of process systems engineering, including factors affecting the system performance. Furthermore, the role of simulation in technological development along with available mathematical models is discussed, and commercial status of pervaporation based separation is presented. Finally, the current status of the existing technology, challenges, and future research directions are identified from the perspective of achieving process sustainability on the industrial scale. Economic comparison between distillation and different hybrid schemes revealed that integrating distillation with membrane based separation techniques reduce the bioethanol production cost. Moreover, hybrid schemes that combine distillation with pervaporation, and steam stripping with vapor permeation are proved to be the best combinations for the cheapest bioethanol production.

Microbial conversion of carbon monoxide (CO) to acetate is a promising upcycling strategy for carbon sequestration. Herein, we demonstrate that CO conversion and acetate production rates of Eubacterium limosum KIST612 strain can be improved by in silico prediction and in vivo assessment. The mimicked CO metabolic model of KIST612 predicted that overexpressing the CO dehydrogenase (CODH) increases CO conversion and acetate production rates. To validate the prediction, we constructed mutant strains overexpressing CODH gene cluster and measured their CO conversion and acetate production rates. A mutant strain (ELM031) co-overexpressing CODH, coenzyme CooC2 and ACS showed a 3.1 × increased specific CO oxidation rate as well as 1.4 × increased specific acetate production rate, compared to the wild type strain. The transcriptional and translational data with redox balance analysis showed that ELM031 has enhanced reducing potential from up-regulation of ferredoxin and related metabolism directly linked to energy conservation.

Herein, we report the heterologous expression in Escherichia coli of a Mo-Cu-containing carbon monoxide dehydrogenase (Mo-Cu CODH) from Hydrogenophaga pseudoflava, which resulted in an active protein catalyzing CO oxidation to CO2. By supplying the E. coli growth medium with Na2MoO4 (Mo) and CuSO4 (Cu), the Mo-Cu CODH metal cofactors precursors, the expressed L-subunit was found to have CO-oxidation activity even without the M- and S- subunits. This successful expression of CO-oxidizing-capable single L-subunit provides direct evidence of its role as the catalytic center of Mo-Cu CODH that has not been discovered and studied before. Subsequently, we used the expressed protein to construct a CO bio-microsensor based on a newly developed fast and sensitive Clark-type CO2 transducer using an aprotic solvent/ionic liquid electrolyte. The CO bio-microsensor exhibited a linear response to CO concentration in the 0-9 μM range, with a limit of detection (LOD) of 15 nM CO. The sensor uses a mixture of Mo-Cu CODH's L-subunit/Mo, Cu cofactors/methylene blue, confined in the enzyme chamber that is placed in front of a CO2 transducer. The optimized sensor's sensitivity and performance were retained to levels of at least 80% for 1 week of continuous polarization and operation in an aqueous medium. We have also demonstrated the use of an alkaline front-trap solution to make a completely O2/CO2 interference-free microsensor. The CO bio-microsensor developed in this study is potentially useful as an analytical tool for the detection of trace CO in dissolved form for monitoring dissolved CO concentration dynamics in natural or synthetic systems.

Summary Oriented enzyme immobilization on electrodes is crucial for interfacial electrical coupling of direct electron transfer (DET)-based enzyme-electrode systems. As inorganic-binding peptides are introduced as molecular binders and enzyme-orienting agents, inorganic-binding peptide-fused enzymes should be designed and constructed to achieve efficient DET. In this study, it is aimed to compare the effects of various gold-binding peptides (GBPs) fused to enzymes on electrocatalytic activity, bioactivity, and material-binding behaviors. Here, GBPs with identical gold-binding properties but different amino acid sequences were fused to the FAD-dependent glucose dehydrogenase gamma-alpha complex (GDHγα) to generate four GDHγα variants. The structural, biochemical, mechanical, and bioelectrochemical properties of these GDHγα variants immobilized on electrode were determined by their fused GBPs. Our results confirmed that the GBP type is vital in the design, construction, and optimization of GBP-fused enzyme-modified electrodes for facile interfacial DET and practical DET-based enzyme-electrode systems., Graphical abstract, Highlights • The four GBP sequences are genetically fused to catalytic subunit of GDHγα complex • The cofactor-surface interface was investigated with 3D models of fusion enzymes • The four systems exhibit diverse electrochemical results depending on GBP type, Electrochemistry; Bio-electrochemistry; Materials science; Materials chemistry

The objective of this study is to quickly develop collaborative mixed reality (MR) applications using 3D city models. People can collaborate with each other using holographic 3D city models through mixed reality applications based on head mounted display (HMD) devices. We have implemented a prototype of mixed reality applications using 3D city models. We used 3D geospatial data from VWorld system, a kind of geospatial open platform of South Korea. We implemented light-weight applications for a stand-alone MR device, HoloLens. Users can place reconstructed holographic 3D city models on tables, and they can explore these models with gaze and gestures. Information such as building, route, real-time weather, air condition, and POI information are visualized on 3D city models. The prototype provides spatial analysis functions such as measurement, sunlight analysis, viewshed analysis, and landscape view. Multiple users can share 3D city models and collaborate with each other using this prototype.

Digital tw,64&rsquo, 1win technology based on building a virtual digital city similar to a real one enables the simulation of urban phenomena or the design of a city. A geospatial platform is an essential supporting component of digital twin cities. In this study, we propose a planetary-scale geospatial open platform that can be used easily in the most widely used game engine environment. The proposed platform can visualize large-capacity geospatial data in real time because it organizes and manages various types of data based on quadtree tiles. The proposed rendering tile decision method provides constant geospatial data visualization according to the camera controls of the user. The platform implemented is based on Unity3D, and therefore, one can use it easily by importing the proposed asset library. The proposed geospatial platform is available on the Asset Store. We believe that the proposed platform can meet the needs of various three-dimensional (3-D) geospatial applications.

Microbial fuel cell (MFC) systems have been developed for potential use as power sources, along with several other applications, with bacteria as the prime factor enabling electrocatalytic activity. Limited voltage and current production from unit cells limit their practical applicability, so stacking multiple MFCs has been proposed as a way to increase power production. Special attention is paid to voltage reversal (VR), a common occurrence in stacked MFCs, and to identifying the mechanisms underlying this phenomenon. We also proposed realistic perspectives on stacked MFCs in an effort to control and suppress VR by balancing the kinetics in the system, such as using enriched electroactive microorganisms or altering the circuitry mode.

AIM We investigated the satisfaction and efficacy of mirabegron in patients with overactive bladder (OAB) symptoms who were unsatisfied with previous antimuscarinic treatment. METHODS This was a 12-week, open-label study of adults with OAB who had been treated with antimuscarinics within 2 years of screening and expressed dissatisfaction over poor efficacy or adverse events of antimuscarinics. All enrolled patients have received mirabegron 50 mg once daily for 12 weeks. The primary outcome was the percentage of patients reporting treatment satisfaction questions (TSQ) at week 12 ("very satisfied" or "somewhat satisfied"). Patients completed voiding diaries, Overactive Bladder Questionnaire short form (OAB-q-SF), Overactive Bladder Symptom Score (OABSS), and the global response assessment (GRA) at baseline, Week 4, and Week 12. At 12-weeks, patients were assessed for willingness to continue treatment. RESULTS The response rate of treatment satisfaction at 12 weeks was 69.3% (275/397) (95% confidence interval 64.7-73.8). Significant improvements from baseline to weeks 4 and 12 were observed in the frequency, urgency due to urinary incontinence, and urgency episodes per 24 h (all p

Asian dust (AD) events increase environmental pollution and have a detrimental effect on human health. Particulate matter with an aerodynamic diameter

Voltage reversal (VR) in series connection of multiple membrane electrode assembly installed microbial fuel cells (mMEA-MFC) is eliminated by manipulating the resistor control. Discharge test results collected from two mMEA-MFCs initially operated (designated as P1 and P2) confirm that the performance of P2 exceeds that of P1. Thus, driving P1 and P2 as serially stacked MFCs generate the VR in P1. Controlling the inserted resistor adjust the current production of P2 to maintain balance with P1, and the VR in P1 is eliminated in the operation of stacking mode. Thus, manipulating the internal resistance provide an applicable approach to suppress VR in the stacking of mMEA-MFCs system.

Direct electron transfer (DET) between enzymes and electrodes is a key issue for practical use of bioelectrocatalytic devices as a bioenergy process, such as enzymatic electrosynthesis, biosensors, and enzyme biofuel cells. To date, based on the DET of bioelectrocatalysis, less than 1% of the calculated theoretical current was transferred to final electron acceptor due to energy loss at enzyme-electrode interface. This study describes the design and construction of a synthetic glucose dehydrogenase (GDH; α and γ subunits) combined with a gold-binding peptide at its amino or carboxy terminus for direct contact between enzyme and electrode. The fused gold-binding peptide facilitated stable immobilization of GDH and constructed uniform monolayer of GDH onto a Au electrode. Depending on the fused site of binding peptide to the enzyme complex, nine combinations of recombinant GDH proteins on the electrode show significantly different direct electron-transfer efficiency across the enzyme-electrode interface. The fusion of site-specific binding peptide to the catalytic subunit (α subunit, carboxy terminus) of the enzyme complex enabled apparent direct electron transfer (DET) across the enzyme-electrode interface even in the absence of the electron-transfer subunit (i.e., β subunit having cytochrome domain). The catalytic glucose oxidation current at an onset potential of ca. (-)0.46 V vs Ag/AgCl was associated with the appearance of an flavin adenine dinucleotide (FAD)/FADH

Ceramic membranes (CMs) with different pore sizes (0.14 μm CM1, 150 kDa CM2 and 5 kDa CM3) were tested as separators in two-chamber microbial fuel cells (MFCs). The performance and ionic gradient concentration of MFCs using CMs were compared with that of cation exchange membrane (CEM), Nafion 117. MFC with CMs exhibited a higher performance than that of CEM under batch operation. The highest power density of 1790 ± 60 mW/m2, columbic efficiency (CE) of 41 ± 10% and internal resistance of 102 ± 13 Ω were obtained for MFC with CM3 under batch mode operation. The highest power density, columbic efficiency and internal resistance of MFC with CEM were found to be 1225 ± 20 mW/m2, 21 ± 1% and 400 ± 10 Ω, respectively. The highest performance of MFC with CM3 was expected due to a higher porosity of CM3 (13.8%) compared with that of CM1 (11.0%) and CM2 (11.05%). MFCs operated with catholyte containing salt solution, phosphate buffer basal medium without carbon source and yeast extract (PBBM-SA), generated lower current than with phosphate buffer (PB) as catholyte. This difference was more significant in the MFCs with the CEM Nafion 117 than with ceramic membranes. The non-selective porous ceramic membranes improved the diffusion of protons in the presence of other high concentration cations and resulted in MFC with higher performance. Hence, the porous ceramic membrane is a potential candidate separator for the development of commercial scale MFCs.

Syngas fermentation is largely dependent on acetogens that occur in various anaerobic environmental samples including soil, sediment, and feces. Here the authors report the metagenomic isolation of acetogens for C2 chemical production from syngas. Screening acetogens for C2 chemical production typically involves detecting the presence of the Wood-Ljungdahl Pathway for carbon monoxide conversion. The authors collect samples from river-bed sediments potentially having conditions suitable for carbon monoxide-converting anaerobes, and enrich the samples under carbon monoxide selection pressure. Changes in the microbial community during the experimental procedure are investigated using both amplicon and shotgun metagenome sequencing. Combined next-generation sequencing techniques enabl in situ tracking of the major acetogenic bacterial group and lead to the discovery of a 16 kb of gene cluster for WLP. The authors isolat an acetogenic clostridial strain from the enrichment culture (strain H21-9). The functional activity of H21-9 is confirmed by its high level of production of C2 chemicals from carbon monoxide (77.4 mM acetate and 2.5 mM of ethanol). This approach of incorporating experimental enrichment with metagenomic analysis can facilitate the discovery of novel strains from environmental habitats by tracking target strains during the screening process, combined with validation of their functional activity.