Biomaterials in nature often exhibit hierarchical chiral structures with an intriguing mechanism involving hierarchical chirality transfer from molecular to supramolecular and the nano- or microscale ...level. To mimic the cross-level chirality transfer, we present here one kind of host–guest complex system built of β-cyclodextrin (β-CD), sodium dodecyl sulfate (SDS), and fluorescent dyes, which show multilevel chirality, including molecular chirality of β-CD, induced supramolecular chirality of β-CD/SDS host–guest complexes, a chiral lattice self-assembled nanosheet, mesoscopic chirality of an assembled helical tube, induced chirality of a dye-doped chiral tube. The hierarchical chirality involved a chiral lattice self-assembly process, which can be identified by small-angle X-ray scattering, optical studies, circular dichroism, and circularly polarized luminescence spectral measurements. Benefiting from the chiral lattice self-assembly, intense circularly polarized luminescence was observed from the achiral dye-doped complexes with a large dissymmetry factor up to +0.1. This work thus provides a feasible insight for developing hierarchical chiroptical materials based on the lattice self-assembly.
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The carbon layers wrapped CoFe alloy (C/CoFe-30-650) exhibits high bifunctional catalysis for both ORR and OER, and the rechargeable ZABs with this catalyst has an excellent stability during 20,000 ...charging-discharging cycles.
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Developing high active and stable bifunctional electrocatalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential for the development of rechargeable Zn-air batteries. Herein, a facile strategy to synthesize the porous carbon layers wrapped CoFe alloy (C/CoFe) through the pyrolysis of a homogeneous mixture containing Co, Fe ions and N-doped carbon quantum dots (N-doped CQDs) was reported. The prepared carbon layers with multi-level pore structures provides more active sites and optimizes the homogeneity of the electron and mass transport. In addition, the carbon layers, which is doped by Co/Fe/N atoms, is responsible for high ORR activity, while the CoFe alloy plays a vital role in OER performance. The as-synthesized catalyst exhibits an excellent bifunctionality for electrochemical oxygen reactions, which is comparable to the commercial Pt/C and IrO2 benchmarks. Owing to the carbon layers protects CoFe alloy nanoparticles from the harsh environment, the rechargeable Zn–air battery with the C/CoFe catalyst delivers excellent stability during 20,000 charging-discharging cycles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We report a large-size (4-inch) optical exceptional point structure at visible frequencies by designing a multilayer structure of absorbing and non-absorbing dielectrics. The optical exceptional ...point was implemented as indicated by the realized unidirectional reflectionless light transport at a wafer scale. The associated abrupt phase transition is theoretically and experimentally confirmed when crossing over the exceptional point in wavelengths. The large scale demonstration of phase transition around exceptional points will open new possibilities in important applications in free space optical devices.
An amphiphilic dendron containing three dendrite L‐glutamic acid units and a long alkyl chain was synthesized by a convergent method. It was found that the dendron could form hydrogels over a wide pH ...range from 2 to 13. Moreover, accompanying the pH change, the compounds self‐assembled into various chiral structures: from helical nanotube, helical nanotube with a string of beads, and coiled superhelix to dendrite nanostructures, such as pine, feather, etc. A series of characterizations based on TEM observations, X‐ray diffraction and FTIR spectroscopic measurements revealed that the dendron formed a bilayer first and then hierarchically self‐assembled into various chiral nanostructures. The four carboxylic acid groups and three amide groups played an important role in the self‐assembly. The interaction between the multiamide groups stabilized the bilayer structures, whereas the ionization degree of the carboxylic acids was responsible for the formation of various chiral structures. The work presented a hydrogel system with wide pH adaptability and showed the regulation on chiral structures by simple pH variations.
Supramolecular hydrogels: An amphiphilic dendron containing three dendrite L‐glutamic acid units and a long alkyl chain was found to form hydrogels over a wide pH range from 2 to 13. Accompanying the pH change, the compounds self‐assembled into various chiral structures: from helical nanotube, helical nanotube with a string of beads, and coiled superhelix to dendrite nanostructures, such as pine and feather (see figure).
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Water-based rechargeable metal-air batteries play an important role in the storage and conversion of renewable electric energy. However, the sluggish kinetics of the oxygen reduction reaction (ORR) ...and oxygen evolution reaction (OER) have limited the practical application of rechargeable metal-air batteries. Most of reviews were focused on single functional electrocatalysts while few on bifunctional electrocatalysts. It is indispensable but challenging to design a bifunctional electrocatalyst that is active and stable to the two reactions. Recently, attempts to develop high active bifunctional electrocatalysts for both ORR and OER increase rapidly. Much work is focused on the micro-nano design of advanced structures to improve the performance of bifunctional electrocatalyst. Transition-metal materials, carbon materials and composite materials, and the methods developed to prepare micro-nano structures, such as electrochemical methods, chemical vapor deposition, hydrothermal methods and template methods are reported in literatures. Additionally, many strategies, such as adjustments of electronic structures, oxygen defects, metal-oxygen bonds, interfacial strain, nano composites, heteroatom doping etc., have been used extensively to design bifunctional electrocatalysts. To well understand the achievements in the recent literatures, this review focuses on the micro-nano structural design of materials, and the related methods and strategies are classed into two groups for the improvement of intrinsic and apparent activities. The fine adjustment of nano structures and an in-depth understanding of the reaction mechanism are also discussed briefly.
Cost-effective and highly active ORR and OER catalysts are critical for the utilization of renewable electric energy. Intrinsic activity and apparent activity are closely related to the micro-nano structures of bifunctional electrocatalysts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Anaerobic digestion has been widely applied throughout the world for lignocellulosic biomass treatment and energy recovery. However, the solid digestate from anaerobic digestion still contains a ...rather large fraction of poorly anaerobic degradable lignocellulosic fibers due to inhibition of lignin, which deeply limits the bioenergy production from lignocelullosic biomass. Therefore, a novel fungal pretreatment method using P. sajor-caju and T. versicolor was investigated to advance the solid-state fermentation of solid digestate and improve the production of fermentative volatile fatty acids (VFAs). The results showed that a maximum VFA yield of 240 mg COD/g VS was obtained from solid digestate pretreated by P. sajor-caju in 6 weeks, which was 1.17-fold and 1.24-fold higher than that of the autoclaved group and raw substrate, respectively. The mechanisms indicated that these fungal strains could grow on the solid digestate and secrete ligninolytic enzymes such as laccase and manganese peroxidase to degrade lignin in different extents. Besides, fungal pretreatment substantially changed the solid digestate characteristics such as cellulose/lignin ratio and the presence of specific functional groups. Moreover, fungal pretreatment using P. sajor-caju effectively damaged the structure and increased surface area and pore size of the solid digestate, which is beneficial to further VFA production.
•Solid digestate was pretreated by fungi for enhancing VFA production.•Fungal strains significantly influenced chemical composition of substrate.•P. sajor-caju pretreatment improved VFA yield from solid digestate by 117%–124%.•Acetate and propionate were dominant compositions in fermentative VFA spectrums.
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We propose an explicit isogeometric topology optimization approach based on Moving Morphable Components (MMCs). The prescribed design domain is discretized using a NURBS patch and NURBS-based ...Isogeometric Analysis (IGA) method is adopted for structural response analysis and sensitivity analysis. We employ the MMCs to represent the geometries of structural components (a subset of the design domain) with use of explicit design parameters. The central coordinates, half-length, half-width, and inclined angles of MMCs are taken as design variables. The proposed method not only inherits the explicitness of the MMC-based topology optimization, but also embraces the merits of the Isogeometric Analysis (IGA) such as a tighter link with Computer-Aided Design (CAD) and higher-order continuity of the basis functions. Several numerical examples illustrate that the presented method based on IGA is more robust and stable than FEM-based topology optimization using MMCs.
•We proposed an isogeometric topology optimization approach using moving morphable components.•NURBS-based Isogeometric Analysis (IGA) is adopted for structural response analysis and sensitivity analysis.•The presented method inherits the explicit representation of MMC and the higher accuracy of IGA.•The proposed approach improves the numerical stability significantly.
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Due to the interest in the origin of life and the need to synthesize new functional materials, the study of the origin of chirality has been given significant attention. The mechanism of chirality ...transfer at molecular and supramolecular levels remains underexplored. Herein, we study the mechanism of chirality transfer of N, N'-bis (octadecyl)-
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-(anthracene-9-carboxamide)-glutamic diamide (
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-GAn) supramolecular chiral self-assembled at the air/water interface by chiral sum-frequency generation vibrational spectroscopy (chiral SFG) and molecular dynamics (MD) simulations. We observe long-range chirality transfer in the systems. The chirality of C
-H is transferred first to amide groups and then transferred to the anthracene unit, through intermolecular hydrogen bonds and π-π stacking to produce an antiparallel β-sheet-like structure, and finally it is transferred to the end of hydrophobic alkyl chains at the interface. These results are relevant for understanding the chirality origin in supramolecular systems and the rational design of supramolecular chiral materials.
Mixed ionic‐electronic conducting (MIEC) membranes have gained growing interest recently for various promising environmental and energy applications, such as H2 and O2 production, CO2 reduction, O2 ...and H2 separation, CO2 separation, membrane reactors for production of chemicals, cathode development for solid oxide fuel cells, solar‐driven evaporation and energy‐saving regeneration as well as electrolyzer cells for power‐to‐X technologies. The purpose of this roadmap, written by international specialists in their fields, is to present a snapshot of the state‐of‐the‐art, and provide opinions on the future challenges and opportunities in this complex multidisciplinary research field. As the fundamentals of using MIEC membranes for various applications become increasingly challenging tasks, particularly in view of the growing interdisciplinary nature of this field, a better understanding of the underlying physical and chemical processes is also crucial to enable the career advancement of the next generation of researchers. As an integrated and combined article, it is hoped that this roadmap, covering all these aspects, will be informative to support further progress in academics as well as in the industry‐oriented research toward commercialization of MIEC membranes for different applications.
The roadmap involving multidisciplinary research fields, presented by various global experts in their fields, is intended to give an overview on the status and breakthroughs of this evolving and growing interdisciplinary field and provide insights into the challenges driven by the research needs and opportunities in the diverse and rich field of using mixed ionic‐electronic conducting membranes.
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