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Electronic Promotion of Methanol Synthesis over Cu-Loaded ZnO-Based Catalysts
No full textMethanol, a raw material for C1 chemistry, is industrially produced under harsh conditions using Cu/ZnO-based catalysts. The synthesis of methanol under mild conditions is a challenging subject using an improved catalyst. Here, Zn1-xSixO (ZSO) nanoparticles were synthesized by a thermal plasma method, and their work function and carrier concentration could be tuned by the Zn:Si ratio. The electrically conductive ZSO nanoparticles with a low work function enhanced the donation of electrons to loaded Cu and significantly promoted hydrogenation of CO to methanol, whereas insulating ZSO nanoparticles with a similar low work function did not. These results reveal that efficient electronic promotion by the transfer of electrons from a support to loaded Cu plays a key role in low-temperature methanol synthesis
Production of lightweight cementless binders using supplementary cementitious materials to replace autoclaved aerated concrete blocks
No full textRecently, the application of sustainable cementitious materials to improve the efficiency of buildings has become of great importance as part of carbon neutrality. This study aims to develop lightweight cementitious binders made of supplementary cementitious materials and various additives to replace autoclaved aerated concrete blocks. To this end, the mechanical properties of 36 cementless binders using fly ash (FA), fly ash cenosphere (FAC), and ground granulated blast-furnace slag were assessed. The FA or FAC activated with Ca(OH)(2) and Na2CO3 binders, which showed a density of 637.6-1576.3 kg/m(3) and a compressive strength of 7.4-65.0 MPa, were selected as representative samples, and their microstructure and thermal performance were further characterized. The results showed that FAC acted as a filler and precursor, occupying space in the binder, and reacting partially with activators simultaneously. In particular, increasing FAC content increased the porosity of the hardened matrix, remarkably reducing the weight of the binders. In addition, the thermal conductivity of the binders was significantly reduced to 0.25-0.27 W/m center dot K, which increased their thermal efficiency. This light-weight, thermally efficient cementless binder is expected to be applied to commercially available blocks
ChEAP: ChIP-exo analysis pipeline and the investigation of Escherichia coli RpoN protein-DNA interactions
No full textGenome-scale studies of the bacterial regulatory network have been leveraged by declining sequencing cost and advances in ChIP (chromatin immunoprecipitation) methods. Of which, ChIP-exo has proven competent with its near-single base-pair resolution. While several algorithms and programs have been developed for different analytical steps in ChIP-exo data processing, there is a lack of effort in incorporat-ing them into a convenient bioinformatics pipeline that is intuitive and publicly available. In this paper, we developed ChIP-exo Analysis Pipeline (ChEAP) that executes the one-step process, starting from trim-ming and aligning raw sequencing reads to visualization of ChIP-exo results. The pipeline was imple-mented on the interactive web-based Python development environment - Jupyter Notebook, which is compatible with the Google Colab cloud platform to facilitate the sharing of codes and collaboration among researchers. Additionally, users could exploit the free GPU and CPU resources allocated by Colab to carry out computing tasks regardless of the performance of their local machines. The utility of ChEAP was demonstrated with the ChIP-exo datasets of RpoN sigma factor in E. coli K-12 MG1655. To analyze two raw data files, ChEAP runtime was 2 min and 25 s. Subsequent analyses identified 113 RpoN binding sites showing a conserved RpoN binding pattern in the motif search. ChEAP application in ChIP-exo data analysis is extensive and flexible for the parallel processing of data from various organisms. (c) 2022 The Authors. Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology
Femtosecond-Resolved Imaging of a Single-Particle Phase Transition in Energy-Filtered Ultrafast Electron Microscopy
No full textUsing an energy filter in transmission electron microscopy has enabled elemental mapping at the atomic scale and improved the precision of structural determination by gating inelastic and elastic imaging electrons, respectively. Here, we use an energy filter in ultrafast electron microscopy to enhance the temporal resolution toward the domain of atomic motion. Visualizing transient structures with femtosecond temporal precision was achieved by selecting imaging electrons in a narrow energy distribution from dense chirped photoelectron packets with broad longitudinal momentum distributions and thus typically exhibiting picosecond durations. In this study, the heterogeneous ultrafast phase transitions of vanadium dioxide (VO2) nanoparticles, a representative strongly correlated system, were filmed and attributed to the emergence of a transient, low-symmetry metallic phase caused by different local strains. Our approach enables electron microscopy to access the time scale of elementary nuclear motion to visualize the onset of the structural dynamics of matter at the nanoscale
Intermittent Swimming of Two Self-Propelled Flexible Fins with Laterally Constrained Heaving Motions in a Side-by-Side Configuration
No full textInspired by the intermittent locomotion of fish schools, numerical simulations are performed with two self-propelled flexible fins in a side-by-side configuration with anti-phase oscillation actuated by laterally constrained heaving motions. For an intermittent swimming gait, one type of the half-tail-beating mode (HT mode) and two types of multiple-tail-beating modes coasting at the smallest (MTS mode) and largest (MTL mode) lateral gap distances are applied. Similar to the continuous-tail-beating mode (CT mode), equilibrium lateral gap distances between two fins with HT and MTL modes exist, whereas two fins with MTS mode do not maintain a lateral equilibrium state. Although the cycle-averaged lateral force acting on two fins with CT and MTL modes is mostly determined by an outward deflected jet and enhanced positive pressure between two fins, an added-mass lateral force related to an asymmetric flapping kinematics by passive flexibility also plays an important role in MTL mode to achieve a stable state with a lateral gap distance smaller than that in CT mode. When the cruising speed or the cycle-averaged input power is identical in a stable state, the cost of transport (COT) for two fins with MTL mode is smaller than that with CT mode due to not only a benefit from the intermittent swimming gait but also an enhanced schooling benefit with a small equilibrium lateral gap distance. The COT for two fins with CT mode is reduced further when the bending rigidity increases, whereas it is opposite with MTL mode
Discriminating active sites for the electrochemical synthesis of H2O2 by molecular functionalisation of carbon nanotubes
No full textThe electrochemical production of H2O2via the two-electron oxygen reduction reaction (2e??? ORR) has recently attracted attention as a promising alternative to the current anthraquinone process. Identification of active sites in O-doped carbon materials, which exhibit high activities and selectivities for the 2e??? ORR, is important for understanding the selective electrocatalytic process and achieving the rational design of active electrocatalysts. However, this is impeded by the heterogeneous distribution of various active sites on these catalysts. In this study, we exploited the molecular functionalisation approach to implant anthraquinone, benzoic acid, and phenol groups on carbon nanotubes and systematically compared the electrocatalytic activities and selectivities of these functional groups. Among these oxygen functional groups, the anthraquinone group showed the highest surface-area-normalised and active-site-normalised activities
Structural Stability of Stacked Disposal Containers in Silo-type Low- and Intermediate-level Waste Repository under Weight of Backfilling Materials
No full textThe long-term structural stability of radioactive-waste repositories is important for isolating radionuclides from the biosphere. The weight of backfilling materials affects the stability of these repositories. This paper reports the results of fracture experiments and simulations performed on a 1:6 scale 16-pack disposal container to investigate its structural stability. The fracture experiment was performed by piling steel balls and lead blocks atop the container. In addition, fracture experiments and finite-element simulations were performed on a container reinforced with additional poles between 200-liter drum positions. The obtained results demonstrate the structural instability of the original container under the backfilling-material weight. Moreover, the reinforced container is observed to withstand a load that exceeds the backfilling-material weight. The benchmarking between the experimental and simulation results was accomplished by comparing the yield stresses and strains observed in both cases. These results can serve as background data to relieve the compressive-strength criterion of silo-type repositories
Recent progress on MOF/MXene nanoarchitectures: A new era in coordination chemistry for energy storage and conversion
No full textThe development of urbanization and industrialization leads to rapid depletion of fossil fuels. Therefore, the production of fuel from renewable resources is highly desired. Electrotechnical energy conversion and storage is a benign technique with reliable output and is eco-friendly. Developing an exceptional electrochemical catalyst with tunable properties like a huge specific surface area, porous channels, and abundant active sites is critical points. Recently, Metal-organic frameworks (MOFs) and two-dimensional (2D) transition-metal carbides/nitrides (MXenes) have been extensively investigated in the field of electrochemical energy conversion and storage. However, advances in the research on MOFs are hampered by their limited structural stability and conventionally low electrical conductivity, whereas the practical electrochemical performance of MXenes is impeded by their low porosity, inadequate redox sites, and agglomeration. Consequently, researchers have been designing MOF/MXene nanoarchitectures to overcome the limitations in electrochemical energy conversion and storage. This review explores the recent advances in MOF/MXene nanoarchitectures design strategies, tailoring their properties based on the morphologies (0D, 1D, 2D, and 3D), and broadening their future opportunities in electrochemical energy storage (batteries, supercapacitors) and catalytic energy conversion (HER, OER, and ORR). The intercalation of MOF in between the MXene layers in the nanoarchitectures functions synergistically to address the issues associated with bare MXene and MOF in the electrochemical energy storage and conversion. This review gives a clear emphasis on the general aspects of MOF/MXene nanoarchitectures, and the future research perspectives, challenges of MOF/MXene design strategies and electrochemical applications are highlighted. (c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved
Synthesis of atomically thin sheets by the intercalation-based exfoliation of layered materials
No full textThe intercalation-based exfoliation of layered materials is a broadly applicable strategy for the scalable production of atomically thin (from mono- to few-layer) sheets, including graphene, black phosphorus, hexagonal boron nitride and transition metal dichalcogenides. This strategy typically involves the intercalation of foreign species (ions or small molecules) into the interlayer spaces of layered materials, followed by a mild exfoliation process (spontaneously or via bath sonication, stirring or manual shaking). In this Review we introduce several intercalation-based exfoliation methods and highlight the factors that influence the quality of exfoliated nanosheets. In addition, we introduce the phase-transition phenomena involved in intercalation-based exfoliation, which may induce the resultant nanosheets to differ electronically and structurally from their bulk counterparts. Finally, we discuss potential commercial applications, focusing on devices (such as various electronic, photonic, photoelectric and energy devices) and catalysis (including photocatalysis and electrocatalysis). [Figure not available: see fulltext.
