56016 research outputs found
Sort by
Lifetime-configurable soft robots via photodegradable silicone elastomer composites
No full textDeveloping soft robots that can control their own life cycle and degrade on-demand while maintaining hyper elasticity is a notable research challenge. On-demand degradable soft robots, which conserve their original functionality during operation and rapidly degrade under specific external stimulation, present the opportunity to self-direct the disappearance of temporary robots. This study proposes soft robots and materials that exhibit excellent mechanical stretchability and can degrade under ultraviolet light by mixing a fluoride-generating diphenyliodonium hexafluorophosphate with a silicone resin. Spectroscopic analysis revealed the mechanism of Si-O-Si backbone cleavage using fluoride ion (F-) and thermal analysis indicated accelerated decomposition at elevated temperatures. In addition, we demonstrated a robotics application by fabricating electronics integrated gaiting robot and a fully closed-loop trigger disintegration robot for autonomous, application-oriented functionalities. This study provides a simple yet novel strategy for designing life cycle mimicking soft robotics that can be applied to reduce soft robotics waste, explore hazardous areas, and ensure hardware security with on demand destructive material platforms
Identification and comparison of the local physicochemical structures of transition metal-based layered double hydroxides for high performance electrochemical oxygen evolution reactions
No full textLayered double hydroxides (LDHs) have attracted considerable attention as a cost effective alternative to the precious iridium- and ruthenium-based electrocatalysts for an oxygen evolution reaction (OER), a bottleneck of water electrolysis for sustainable hydrogen production. Despite their excellent OER performance, the structural and electronic properties of LDHs, particularly during the OER process, remain to be poorly understood. In this study, a series of LDH catalysts is investigated through in situ X-ray absorption fine structure analyses and density functional theory (DFT) calculations. Our experimental results reveal that the LDH catalyst with equal amounts of Ni and Fe (NF-LDH) exhibits the highest OER activity and catalytic life span when compared with its counterparts having equal amounts of Ni and Co (NC-LDH) and Ni only (Ni-LDH). The NF-LDH shows a markedly enhanced OER kinetics compared to the NC-LDH and the Ni-LDH, as proven by the lower overpotentials of 180, 240, and 310 mV, respectively, and the Tafel slopes of 35.1, 43.4, and 62.7 mV dec???1, respectively. The DFT calculations demonstrate that the lowest overpotential of the NF-LDH is associated with the active sites located at the edge planes of NF-LDH in contrast to those located at the basal planes of Ni-LDH and NC-LDH. The current study pinpoints the active sites on various LDHs and presents strategies for optimizing the OER performance of the LDH catalysts
Octafluoronaphthalene as a thermal-annealing-free volatile solid additive enables high-performance organic solar cells
No full textA thermal annealing-free solid additive octafluoronaphthalene was developed for high-performance organic solar cells. In an additive-modified device, an impressive power conversion efficiency of 18.59% from 17.27% was achieved with simultaneously enhanced current density from 26.86 to 27.53 mA cm-2 and fill factor from 74.34% to 78.85%. Power conversion efficiency of 18.59% from 17.27% has been achieved using thermal annealing-free solid additive octafluoronaphthalene-modified organic solar cells
Comparison of the opposite behaviours of Korean heatwaves with extreme hot sea surface temperatures in August 2016 and 2022
No full textIn South Korea, an unprecedented heatwave occurred in August 2016. That year, sea surface temperature (SST) in the Korean marginal seas (KMS) was remarkably higher than that in climatology, and upper-level anticyclonic circulations favoured this heatwave. More recently, similar conditions that can expect the frequent occurrence of heatwaves prevailed in August 2022. However, the opposite extreme phenomenon, heatwave days below climatology, occurred with the emergence of a stationary rainband in South Korea. This study aims to understand the two different behaviours of heatwaves in Korea under the same hot SST conditions in the KMS. The most pronounced difference between these two extreme cases is the existence of moisture flux related to the western North Pacific summer monsoon (WNPSM). Although the WNPSM is not generally highly correlated with temperature and precipitation in Korea, their relationship is particularly strong when hot SST conditions develop in the KMS. This SST condition, combined with the WNPSM, plays a role in determining this anomalous moisture flux in Korea. Enough tropical moisture flux occurred to build a stationary front with declining heatwave days during August 2022. In contrast, extremely dry and hot weather was more likely in 2016 due to inactive moisture fluxes from the western North Pacific
Upcycling of plastic waste into carbon nanotubes as efficient battery additives
No full textCarbon nanotubes (CNTs) were produced from waste face masks and non-recyclable mixed plastic waste via pyrolysis-chemical vapor deposition (CVD). The yield and properties of the prepared CNTs depended on the feedstock and catalyst used. CoMo/MgO and FeMo/MgO were proven suitable catalysts for producing few-walled and multi-walled CNTs, respectively, regardless of the feedstock. Both mask waste and the FeMo/MgO catalyst led to excellent carbon yield (516.7 wt%) and CNT purity (97.9 wt%). The resulting CNTs were mixed with LiNi0.8Co0.1Mn0.1O2 (NCM811) active material and poly(vinylidene fluoride) binder to fabricate cathodes. Electrochemical measurements showed that CNTs grown on the FeMo/MgO catalyst outperformed commercial carbon black and CNTs. C1-C3 hydrocarbons and H2 present in the plastic pyrolysis gas can be directly used for CNT production without gas separation or purification, therefore, the proposed pyrolysis-CVD process is favorable for efficient plastic upcycling and advanced battery applications. Carbon nanotubes (CNTs) were produced from waste face mask and non-recyclable mixed plastic waste via pyrolysis-chemical vapor deposition (CVD)
Short-range end resection requires ATAD5-mediated PCNA unloading for faithful homologous recombination
No full textHomologous recombination (HR) requires bidirectional end resection initiated by a nick formed close to a DNA double-strand break (DSB), dysregulation favoring error-prone DNA end-joining pathways. Here we investigate the role of the ATAD5, a PCNA unloading protein, in short-range end resection, long-range resection not being affected by ATAD5 deficiency. Rapid PCNA loading onto DNA at DSB sites depends on the RFC PCNA loader complex and MRE11-RAD50-NBS1 nuclease complexes bound to CtIP. Based on our cytological analyses and on an in vitro system for short-range end resection, we propose that PCNA unloading by ATAD5 is required for the completion of short-range resection. Hampering PCNA unloading also leads to failure to remove the KU70/80 complex from the termini of DSBs hindering DNA repair synthesis and the completion of HR. In line with this model, ATAD5-depleted cells are defective for HR, show increased sensitivity to camptothecin, a drug forming protein-DNA adducts, and an augmented dependency on end-joining pathways. Our study highlights the importance of PCNA regulation at DSB for proper end resection and HR. Graphical Abstrac
