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Non-aqueous redox flow batteries (NARFBs) have been attracting much attention because they can significantly increase power and energy density compared to conventional RFBs. In this study, novel pore-filled anion-exchange membranes (PFAEMs) for application to a NAPFB employing metal polypyridyl complexes (i.e., Fe(bpy)32+/Fe(bpy)33+ and Co(bpy)32+/Co(bpy)33+) as the redox species are successfully developed. A porous polyethylene support with excellent solvent resistance and mechanical strength is used for membrane fabrication. The PFAEMs are prepared by filling an ionic liquid monomer containing an imidazolium group and a crosslinking agent into the pores of the support film and then performing in situ photopolymerization. As a result, the prepared membranes exhibit excellent mechanical strength and stability in a non-aqueous medium as well as high ion conductivity. In addition, a low crossover rate for redox ion species is observed for the prepared membranes because they have relatively low swelling characteristics in non-aqueous electrolyte solutions and low affinity for the metal-complex redox species compared to a commercial membrane. Consequently, the PFAEM is revealed to possess superior battery performance than a commercial membrane in the NARFB tests, showing high energy efficiency of about 85% and stable operation for 100 cycles.

In this study, the optimal fabrication parameters of a heterogeneous anion-exchange membrane (AEM) using an ionomer binder are investigated to improve the performance of continuous electrodeionization (CEDI) for producing ultrapure water. Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is selected as the base material for preparing the ionomer binder and quaternized to have various ion exchange capacities (IECs). The optimal content of ion-exchange resin (IER) powder according to the IEC of the ionomer binder is then determined through systematic analyses. In conclusion, it is revealed that a heterogeneous AEM with optimal performance can be fabricated when the IEC of the ionomer binder is lowered and the content of IER powder is also lower than that of conventional heterogeneous membranes. Moreover, crosslinked quaternized PPO (QPPO) nanofiber powder is used as an additive to improve ion conductivity without deteriorating the mechanical properties of the membrane. The membrane fabricated under optimal conditions exhibits significantly lower electrical resistance (4.6 Ω cm2) despite a low IER content (30 wt%) compared to the commercial membrane (IONAC MA-3475, 13.6 Ω cm2) while also demonstrating moderate tensile strength (9.7 MPa) and a high transport number (ca. 0.97). Furthermore, it is proven that the prepared membrane exhibits a superior ion removal rate (99.86%) and lower energy consumption (0.35 kWh) compared to the commercial membrane (99.76% and 0.4 kWh, respectively) in CEDI experiments.

In this study, novel pore-filled anion-exchange membranes (PFAEMs) modified with polypyrrole (PPy) and reduced graphene oxide (rGO) were developed to improve the energy harvesting performance of reverse electrodialysis (RED). The surface-modified PFAEMs were fabricated by varying the contents of PPy and rGO through simple spin coating and chemical/thermal treatments. It was confirmed that the PPy and PPy/rGO layers introduced on the membrane surface did not significantly increase the electrical resistance of the membrane and could effectively control surface characteristics, such as structural tightness, hydrophilicity, and electrostatic repulsion. The PPy/rGO-modified PFAEM showed excellent monovalent ion selectivity, more than four times higher than that of the commercial membrane (AMX, Astom Corp., Tokyo, Japan). This means that the PPy/rGO layer can effectively reduce the permeation of multivalent ions with a high charge intensity and a relatively large hydration radius compared to monovalent ions. The results of evaluating the performance of the surface-modified PFAEMs by applying them to a RED cell revealed that the decrease in potential difference occurring in the membrane was reduced by effectively suppressing the uphill transport of multivalent ions. Consequently, the PPy/rGO-modified membrane exhibited a 5.43% higher power density than the AMX membrane.

Water-splitting electrodialysis (WSED) process using bipolar membranes (BPMs) is attracting attention as an eco-friendly and efficient electro-membrane process that can produce acids and bases from salt solutions. BPMs are a key component of the WSED process and should satisfy the requirements of high water-splitting capability, physicochemical stability, low membrane cost, etc. The water-splitting performance of BPMs can be determined by the catalytic materials introduced at the bipolar junction. Therefore, in this study, several kinds of iron metal compounds (i.e., Fe(OH)3, Fe(OH)3@Fe3O4, Fe(OH)2EDTA, and Fe3O4@ZIF-8) were prepared and the catalytic activities for water-splitting reactions in BPMs were systematically analyzed. In addition, the pore-filling method was applied to fabricate low-cost/high-performance BPMs, and the 50 μm-thick BPMs prepared on the basis of PE porous support showed several times superior toughness compared to Fumatech FBM membrane. Through various electrochemical analyses, it was proven that Fe(OH)2EDTA has the highest catalytic activity for water-splitting reactions and the best physical and electrochemical stabilities among the considered metal compounds. This is the result of stable complex formation between Fe and EDTA ligand, increase in hydrophilicity, and catalytic water-splitting reactions by weak acid and base groups included in EDTA as well as iron hydroxide. It was also confirmed that the hydrophilicity of the catalyst materials introduced to the bipolar junction plays a critical role in the water-splitting reactions of BPM.

Illegal open burning, which is criticized as a leading source of air pollutants among agricultural activities, currently requires constant effort and attention from countries around the world. A speciation analysis method is required to examine the harmful effects of particulate matter generated by incineration on the human body. In this study, to simulate open-air incineration, infrastructure for incineration tests complying with US EPA method 5G was built, and a large-area analysis was conducted on the particulate matter through automated SEM-EDS. For test specimens, waste mulching LDPE collected by Korea Environment Corporation Dangjin Office was used. To raise the identifiability of analyzed particles, the specimen was sampled on a plate made of Ag, which has a high atomic number, three times. Metal particulate matter showed a high reaction to C and C-O. The ratio of metal particulate matters that reacted to C and C-O was in the order of Cu (94.1%) > Fe (83.3%) > Al (79.7%). In this study, it was verified that waste mulching adsorbs metal chemicals originating from the soil due to its properties and deterioration, and that when it is incinerated, it emits particulate matter containing transition metals and other metals that contribute to excessive ROS production and reduction.

Ion-exchange membranes (IEMs) are a core component that greatly affects the performance of electrochemical energy conversion processes such as reverse electrodialysis (RED) and all-vanadium redox flow battery (VRFB). The IEMs used in electrochemical energy conversion processes require low mass transfer resistance, high permselectivity, excellent durability, and also need to be inexpensive to manufacture. Therefore, in this study, thin-reinforced anion-exchange membranes with excellent physical and chemical stabilities were developed by filling a polyethylene porous substrate with functional monomers, and through in situ polymerization and post-treatments. In particular, the thin-reinforced membranes were made to have a high ion-exchange capacity and a limited degree of swelling at the same time through a double cross-linking reaction. The prepared membranes were shown to possess both strong tensile strength (>120 MPa) and low electrical resistance (2). As a result of applying them to RED and VRFB, the performances were shown to be superior to those of the commercial membrane (AMX, Astom Corp., Japan) in the optimal composition. In addition, the prepared membranes were found to have high oxidation stability, enough for practical applications.

Recently, metallic particulate pollutants floating underground have been reported to negatively affect the human body. Thus, there is an urgent need for a public health policy pertaining to the air quality in subway stations. In this study, we investigated whether a vegetation biofilter is effective in reducing metal particle contaminants, especially iron oxide. After selecting a subway station, a vegetation biofilter system was installed, and samples were collected three times, at three intake areas and one exhaust area. The average weight ratio of the detected elements was calculated. The iron oxide reduction effect was evaluated using the Wilcoxon signed rank test. In the return air, C, O, and Fe were detected at 64.9, 27.3, and 5.2 wt.%, respectively; in the supply air, C, O, and Fe were detected at 67.2, 30.4, and 0.7 wt.%, respectively. The difference in the average Fe weight ratio was statistically significant. Air quality has a considerable effect on human health. We confirmed the possibility of reducing Fe in particulate matter using biofilters. However, we could not confirm whether the air quality was improved enough to not have a negative effect on the human body. This should be elucidated through follow-up studies.

In this work, we developed pore-filled ion-exchange membranes (PFIEMs) fabricated for the application to an all-vanadium redox flow battery (VRFB) by filling a hydrocarbon-based ionomer containing a fluorine moiety into the pores of a porous polyethylene (PE) substrate having excellent physical and chemical stabilities. The prepared PFIEMs were shown to possess superior tensile strength (i.e., 136.6 MPa for anion-exchange membrane; 129.9 MPa for cation-exchange membrane) and lower electrical resistance compared with commercial membranes by employing a thin porous PE substrate as a reinforcing material. In addition, by introducing a fluorine moiety into the filling ionomer along with the use of the porous PE substrate, the oxidation stability of the PFIEMs could be greatly improved, and the permeability of vanadium ions could also be significantly reduced. As a result of the evaluation of the charge–discharge performance in the VRFB, it was revealed that the higher the fluorine content in the PFIEMs was, the higher the current efficiency was. Moreover, the voltage efficiency of the PFIEMs was shown to be higher than those of the commercial membranes due to the lower electrical resistance. Consequently, both of the pore-filled anion- and cation-exchange membranes showed superior charge–discharge performances in the VRFB compared with those of hydrocarbon-based commercial membranes.

Proton-exchange membrane fuel cells (PEMFCs) are the heart of promising hydrogen-fueled electric vehicles, and should lower their price and further improve durability. Therefore, it is necessary to enhance the performances of the proton-exchange membrane (PEM), which is a key component of a PEMFC. In this study, novel pore-filled proton-exchange membranes (PFPEMs) were developed, in which a partially fluorinated ionomer with high cross-linking density is combined with a porous polytetrafluoroethylene (PTFE) substrate. By using a thin and tough porous PTFE substrate film, it was possible to easily fabricate a composite membrane possessing sufficient physical strength and low mass transfer resistance. Therefore, it was expected that the manufacturing method would be simple and suitable for a continuous process, thereby significantly reducing the membrane price. In addition, by using a tri-functional cross-linker, the cross-linking density was increased. The oxidation stability was greatly enhanced by introducing a fluorine moiety into the polymer backbone, and the compatibility with the perfluorinated ionomer binder was also improved. The prepared PFPEMs showed stable PEMFC performance (as maximum power density) equivalent to 72% of Nafion 212. It is noted that the conductivity of the PFPEMs corresponds to 58–63% of that of Nafion 212. Thus, it is expected that a higher fuel cell performance could be achieved when the membrane resistance is further lowered.

Abstract This study demonstrates multithreshold engineering of a solution-processed heterojunction electrochemical transistor using a blend of n-type CdSe tetrapod-shaped nanocrystals (TpNCs) and an n-type polymeric organic semiconductor (OSC). The unique geometry of TpNCs enables a broad concentration range of charge percolation, where charge transfer between TpNC and OSC domains determines multiple threshold voltages. The OSC domain’s threshold voltage shifts from 1 to −1 V as TpNC content increases, while the TpNC domain maintains a threshold above 1.5 V. This allows for stable intermediate states, crucial for multivalued logic operations. Charge percolation and photoluminescence studies show selective charge redistribution, shifting the threshold voltages in the polymer networks. Ternary logic gates, including TNOT, TNAND, and TNOR, based on these heterojunction transistors, were also demonstrated, highlighting the potential of this approach for advanced logic applications.

In this work, high-performance pore-filled anion-exchange membranes (PFAEMs) with double cross-linking structures have been successfully developed for application to promising electrochemical energy conversion systems, such as alkaline direct liquid fuel cells (ADLFCs) and vanadium redox flow batteries (VRFBs). Specifically, two kinds of porous polytetrafluoroethylene (PTFE) substrates, with different hydrophilicities, were utilized for the membrane fabrication. The PTFE-based PFAEMs revealed, both excellent electrochemical characteristics, and chemical stability in harsh environments. It was proven that the use of a hydrophilic porous substrate is more desirable for the efficient power generation of ADLFCs, mainly owing to the facilitated transport of hydroxyl ions through the membrane, showing an excellent maximum power density of around 400 mW cm−2 at 60 °C. In the case of VRFB, however, the battery cell employing the hydrophobic PTFE-based PFAEM exhibited the highest energy efficiency (87%, cf. AMX = 82%) among the tested membranes, because the crossover rate of vanadium redox species through the membrane most significantly affects the VRFB efficiency. The results imply that the properties of a porous substrate for preparing the membranes should match the operating environment, for successful applications to electrochemical energy conversion processes.

With advances in robotic technology, the complexity of control of robot has been increasing owing to fundamental von Neumann bottlenecks. Here, we demonstrate coordinated movement by a fully parallel-processable synaptic array with reduced control complexity.

Ultrahigh-resolution patterning with high-throughput and high-fidelity is highly in demand for expanding the potential of OLEDs. Here, the authors report that silicone-incorporated organic light-emitting semiconductors can achieve anisotropic lithography via reactive ion etching-coupled photolithography, for ultrahigh-density RGB OLED arrays.

Abstract Conventional bioinert bone grafts often have led to failure in osseointegration due to low bioactivity, thus much effort has been made up to date to find alternatives. Recently, MXene nanoparticles (NPs) have shown prominent results as a rising material by possessing an osteogenic potential to facilitate the bioactivity of bone grafts or scaffolds, which can be attributed to the unique repeating atomic structure of two carbon layers existing between three titanium layers. In this study, we produced MXene NPs-integrated the ternary nanofibrous matrices of poly(L-lactide-co-ε-caprolactone, PLCL) and collagen (Col) decorated with MXene NPs (i.e., PLCL/Col/MXene), as novel scaffolds for bone tissue engineering, via electrospinning to explore the potential benefits for the spontaneous osteogenic differentiation of MC3T3-E1 preosteoblasts. The cultured cells on the physicochemical properties of the nanofibrous PLCL/Col/MXene-based materials revealed favorable interactions with the supportive matrices, highly suitable for the growth and survival of preosteoblasts. Furthermore, the combinatorial ternary material system of the PLCL/Col/MXene nanofibers obviously promoted spontaneous osteodifferentiation with positive cellular responses by providing effective microenvironments for osteogenesis. Therefore, our results suggest that the unprecedented biofunctional advantages of the MXene-integrated PLCL/Col nanofibrous matrices can be expanded to a wide range of strategies for the development of effective scaffolds in bone tissue regeneration. Graphical Abstract

Contemporary advances in three-dimensional (3D) bioprinting technologies have enabled the fabrication of tailored live 3D tissue mimetics. Furthermore, the development of advanced bioink materials has been highlighted to accurately reproduce the composition of a native extracellular matrix and mimic the intrinsic properties of laden cells. Recent research has shown that MXene is one of promising nanobiomaterials with osteogenic activity for bone grafts and scaffolds due to its unique atomic structure of three titanium layers between two carbon layers. In this study, the MXene-incorporated gelatin methacryloyl (GelMA) and hyaluronic acid methacryloyl (HAMA) (i.e., GelMA/HAMA-MXene) bioinks were prepared to explore if they have the potential to enable the spontaneous osteodifferentiation of human mesenchymal stem cells (hMSCs) when the hMSCs-laden GelMA/HAMA-MXene bioinks were 3D printed. The physicochemical and rheological characteristics of the GelMA/HAMA-MXene hydrogels were proven to be unprecedentedly favorable supportive matrices suited for the growth and survival of hMSCs. Furthermore, hMSCs were shown to spontaneously differentiate into osteoblasts within GelMA-HAMA/MXene composites to provide favorable microenvironments for osteogenesis. Therefore, our results suggest that the remarkable biofunctional advantages of the MXene-incorporated GelMA/HAMA bioink can be utilized in a wide range of strategies for the development of effective scaffolds in bone tissue regeneration.

Designing high-resolution displays based on colloidal quantum dots remains a challenge. Here, the authors demonstrate a photo-patterning method to develop CdSe-based core-shell quantum dots patterns of red, green and blue colours with diameters ranging from 7 to 20 nm and resolution of 1400 pixels per inch.

To enable the large-area manufacture of solution-processed organic electronics, direct photocrosslinking processes has emerged as a promising technology solution. Here, the authors report an efficient universal crosslinking agent for micropatterning of stacked multi-layered organic electronics.

Several cues, including wettability, surface morphology, and porosity, affect the cellular behaviors on nanofibrous scaffolds. However, a challenging task is determining the more influential parameter on cellular behaviors. Herein, we prepared two sets of polycaprolactone (PCL)-based electrospun nanofibrous scaffolds, viz. surface morphology-altered PCL (SMA PCL) scaffolds and hydrophilic PCL-chitosan scaffolds with different chitosan content. We further investigated the scaffolds' cell attachment and proliferation ability to determine which is a predominant factor, wettability, or surface morphology? Water contact angle and alternative current impedance analyses revealed that incorporating chitosan to PCL increased the wettability and dielectric properties. In contrast, alterations in surface morphology did not show any significant changes to the properties mentioned above of neat PCL. Different solvent compositions (CHCl3/DMSO) caused cylindrical and smooth PCL nanofiber to adopt porous, wristed, or flat fibrous structures. The fibroblasts cell studies revealed that both PCL-chitosan and SMA PCL scaffolds had similar cell proliferation profiles on day 1. However, the former scaffolds showed a statistically significant difference from the latter ones on days 3 and 5. In conclusion, we suggest that increasing the wettability of nanofibrous scaffolds is more influential in directing cellular behaviors than surface morphology modification.

In this paper, we propose a novel voltage programmed pixel circuit based on amorphous-indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs) for active-matrix organic light-emitting displays. Through the extensive simulation work based on a-IGZO TFT and OLED models, we confirm that the proposed pixel circuit can compensate for threshold voltage variations of TFTs and OLED degradation over wide dynamic range (~104) of OLED current as well as achieve a high pixel aperture ratio with the suppressed OLED current error rate below 9%.

The zero (0-D) and one-dimensional (1-D) carbon nanomaterials have gained attention among researchers because they exhibit a larger surface area to volume ratio, and a smaller size. Furthermore, carbon is ubiquitously present in all living organisms. However, toxicity is a major concern while utilizing carbon nanomaterials for biomedical applications such as drug delivery, biosensing, and tissue regeneration. In the present review, we have summarized some of the recent findings of cellular and animal level toxicity studies of 0-D (carbon quantum dot, graphene quantum dot, nanodiamond, and carbon black) and 1-D (single-walled and multi-walled carbon nanotubes) carbon nanomaterials. The in vitro toxicity of carbon nanomaterials was exemplified in normal and cancer cell lines including fibroblasts, osteoblasts, macrophages, epithelial and endothelial cells of different sources. Similarly, the in vivo studies were illustrated in several animal species such as rats, mice, zebrafish, planktons and, guinea pigs, at various concentrations, route of administrations and exposure of nanoparticles. In addition, we have described the unique properties and commercial usage, as well as the similarities and differences among the nanoparticles. The aim of the current review is not only to signify the importance of studying the toxicity of 0-D and 1-D carbon nanomaterials, but also to emphasize the perspectives, future challenges and possible directions in the field.

Owing to the astonishing properties of non-harmful viruses, tissue regeneration using virus-based biomimetic materials has been an emerging trend recently. The selective peptide expression and enrichment of the desired peptide on the surface, monodispersion, self-assembly, and ease of genetic and chemical modification properties have allowed viruses to take a long stride in biomedical applications. Researchers have published many reviews so far describing unusual properties of virus-based nanoparticles, phage display, modification, and possible biomedical applications, including biosensors, bioimaging, tissue regeneration, and drug delivery, however the integration of the virus into different biomaterials for the application of tissue regeneration is not yet discussed in detail. This review will focus on various morphologies of virus-incorporated biomimetic nanocomposites in tissue regeneration and highlight the progress, challenges, and future directions in this area.