Coordination-driven self-assembly has emerged as a powerful bottom-up approach to construct various supramolecular architectures with increasing complexity and functionality. Tetraphenylethylene ...(TPE) has been incorporated into metallo-supramolecules to build luminescent materials based on aggregation-induced emission. We herein report three generations of ligands with full conjugation of TPE with 2,2':6',2″-terpyridine (TPY) to construct emissive materials. Due to the bulky size of TPY substituents, the intramolecular rotations of ligands are partially restricted even in dilute solution, thus leading to emission in both solution and aggregation states. Furthermore, TPE-TPY ligands are assembled with Cd(II) to introduce additional restriction of intramolecular rotation and immobilize fluorophores into rosette-like metallo-supramolecules ranging from generation 1-3 (G1-G3). More importantly, the fluorescent behavior of TPE-TPY ligands is preserved in these rosettes, which display tunable emissive properties with respect to different generations, particularly, pure white-light emission for G2.
Inspired by the unique structure and function of the natural chloride channel (ClC) selectivity filter, we present herein the design of a ClC‐type single channel molecule. This channel displays high ...ion transport activity with half‐maximal effective concentration, EC50, of 0.10 μM, or 0.075 mol % (channel molecule to lipid ratio), as determined by fluorescent analysis using lucigenin‐encapsulated vesicles. Planar bilayer lipid membrane conductance measurements indicated an excellent Cl−/K+ selectivity with a permeability ratio P
Cl-
${{_{{\rm Cl}{^{- }}}$
/P
K+
${{_{{\rm K}{^{+}}}$
up to 12.31, which is comparable with the chloride selectivity of natural ClC proteins. Moreover, high anion/anion selectivity (P
Cl-
${{_{{\rm Cl}{^{- }}}$
/P
Br-
${{_{{\rm Br}{^{- }}}$
=66.21) and pH‐dependent conductance and ion selectivity of the channel molecule were revealed. The ClC‐like transport behavior is contributed by the cooperation of hydrogen bonding and anion–π interactions in the central macrocyclic skeleton, and by the existence of pH‐responsive terminal phenylalanine residues.
An artificial anion channel with chloride selectivity comparable to that of natural chloride channel (ClC) proteins was achieved by rational engineering of the central active region of an hourglass‐shaped single‐molecule structure. By incorporating terminal pH‐sensitive groups, our artificial anion channel also mimicked the pH‐responsive feature of natural ClC proteins.
Photocleavage of H2O into clean and storable H2 fuel by photoelectrochemical (PEC) cell is a vital part of the sustainable hydrogen economy. However, thus far one of the limitations confronted by PEC ...cell to preferable performance is the insufficient behavior of photoanode for water oxidation half‐reaction. One of the strategies to elevate the photoanode performance is integrating with an oxygen evolution catalyst (OEC) to remove the bottleneck of the water oxidation kinetics. Herein, an ultrafine cobalt iron oxide (CIO) nanocrystalline is reported as a novel OEC for photoelectrochemical water splitting. The CIO evenly distributing on the surface of hematite nanorod arrays not only greatly facilitates the surface hole injection, but also promotes the charge separation along with passivating the surface states. Such combined effects of CIO finally lead to an impressive 1.71 fold enhancement on the photocurrent density at 1.23 VRHE and ≈170 mV negative shift of onset potential, even overwhelms the commonly utilized Co‐Pi. Along with its excellent long‐term stability, the CIO possesses a great potential application in PEC water splitting devices.
One design for multiple effects: ultrafine CoFe2O4 (CIO) nanoparticles are synthesized as an efficient water oxidation co‐catalyst for α‐Fe2O3 photoelectrode to achieve comprehensive promotions on photoelectrochemical water splitting performances.
Although the taxonomic composition of the human microbiome varies tremendously across individuals, its gene composition or functional capacity is highly conserved - implying an ecological property ...known as functional redundancy. Such functional redundancy has been hypothesized to underlie the stability and resilience of the human microbiome, but this hypothesis has never been quantitatively tested. The origin of functional redundancy is still elusive. Here, we investigate the basis for functional redundancy in the human microbiome by analyzing its genomic content network - a bipartite graph that links microbes to the genes in their genomes. We find that this network exhibits several topological features that favor high functional redundancy. Furthermore, we develop a simple genome evolution model to generate genomic content network, finding that moderate selection pressure and high horizontal gene transfer rate are necessary to generate genomic content networks with key topological features that favor high functional redundancy. Finally, we analyze data from two published studies of fecal microbiota transplantation (FMT), finding that high functional redundancy of the recipient's pre-FMT microbiota raises barriers to donor microbiota engraftment. This work elucidates the potential ecological and evolutionary processes that create and maintain functional redundancy in the human microbiome and contribute to its resilience.
The particle swarm optimization (PSO) algorithm, in which individuals collaborate with their interacted neighbors like bird flocking to search for the optima, has been successfully applied in a wide ...range of fields pertaining to searching and convergence. Here we employ the scale-free network to represent the inter-individual interactions in the population, named SF-PSO. In contrast to the traditional PSO with fully-connected topology or regular topology, the scale-free topology used in SF-PSO incorporates the diversity of individuals in searching and information dissemination ability, leading to a quite different optimization process. Systematic results with respect to several standard test functions demonstrate that SF-PSO gives rise to a better balance between the convergence speed and the optimum quality, accounting for its much better performance than that of the traditional PSO algorithms. We further explore the dynamical searching process microscopically, finding that the cooperation of hub nodes and non-hub nodes play a crucial role in optimizing the convergence process. Our work may have implications in computational intelligence and complex networks.
Halide perovskite single-crystals have recently been widely highlighted to possess high light harvesting capability and superior charge transport behaviour, which further enable their attractive ...performance in photovoltaics. However, their application in photoelectrochemical cells has not yet been reported. Here, a methylammonium lead bromide MAPbBr
single-crystal thin film is reported as a photoanode with potential application in photoelectrochemical organic synthesis, 2,5-dimethoxy-2,5-dihydrofuran. Depositing an ultrathin Al
O
layer is found to effectively passivate perovskite surface defects. Thus, the nearly 5-fold increase in photoelectrochemical performance with the saturated current being increased from 1.2 to 5.5 mA cm
is mainly attributed to suppressed trap-assisted recombination for MAPbBr
single-crystal thin film/Al
O
. In addition, Ti
-species-rich titanium deposition has been introduced not only as a protective film but also as a catalytic layer to further advance performance and stability. As an encouraging result, the photoelectrochemical performance and stability of MAPbBr
single-crystal thin film/Al
O
/Ti-based photoanode have been significantly improved for 6 h continuous dimethoxydihydrofuran evolution test with a high Faraday efficiency of 93%.
Tin‐based perovskite solar cells (Sn‐PSCs) have emerged as promising environmentally viable photovoltaic technologies, but still suffer from severe non‐radiative recombination loss due to the ...presence of abundant deep‐level defects in the perovskite film and under‐optimized carrier dynamics throughout the device. Herein, we healed the structural imperfections of Sn perovskites in an “inside‐out” manner by incorporating a new class of biocompatible chelating agent with multidentate claws, namely, 2‐Guanidinoacetic acid (GAA), which passivated a variety of deep‐level Sn‐related and I‐related defects, cooperatively reinforced the passivation efficacy, released the lattice strain, improved the structural toughness, and promoted the carrier transport of Sn perovskites. Encouragingly, an efficiency of 13.7 % with a small voltage deficit of ≈0.47 V has been achieved for the GAA‐modified Sn‐PSCs. GAA modification also extended the lifespan of Sn‐PSCs over 1200 hours.
Chemical modification of tin perovskites by biocompatible multidentate chelators realized “inside‐out” healing of structural imperfections and manipulation of carrier dynamics, delivering an efficiency up to 13.70 % with enhanced long‐term stability over 1200 h.
Glacial–interglacial changes in the distribution of C₃/C₄ vegetation on the Chinese Loess Plateau have been related to East Asian summer monsoon intensity and position, and could provide insights ...into future changes caused by global warming. Here, we present δ13C records of bulk organic matter since the Last Glacial Maximum (LGM) from 21 loess sections across the Loess Plateau. The δ13C values (range: −25‰ to −16‰) increased gradually both from the LGM to the mid-Holocene in each section and from northwest to southeast in each time interval. During the LGM, C₄ biomass increased from <5% in the northwest to 10–20% in the southeast, while during the mid-Holocene C₄ vegetation increased throughout the Plateau, with estimated biomass increasing from 10% to 20% in the northwest to >40% in the southeast. The spatial pattern of C₄ biomass in both the LGM and the mid-Holocene closely resembles that of modern warm-season precipitation, and thus can serve as a robust analog for the contemporary East Asian summer monsoon rain belt. Using the 10–20% isolines for C₄ biomass in the cold LGM as a reference, we derived a minimum 300-km northwestward migration of the monsoon rain belt for the warm Holocene. Our results strongly support the prediction that Earth’s thermal equator will move northward in a warmer world. The southward displacement of the monsoon rain belt and the drying trend observed during the last few decades in northern China will soon reverse as global warming continues.
•Evaluating environmental effects due to foundation pit dewatering by numerical simulation.•Impact on the environmental effects considering the interaction between the waterproof curtain and pumping ...wells.•Optimized depth of the waterproof curtain is evaluated, including the effective, suggested and control value.•Determining the optimized depth of the waterproof curtain according to the filter length of the pumping wells.
Dewatering using a combination of waterproof curtain and pumping wells is commonly adopted to ensure the stability of foundation pits in multi-aquifer strata. However, dewatering is likely to result in environmental problems. This paper investigates the impact on surroundings owing to the interaction between the waterproof curtain and pumping wells by numerical simulation. The depth of the diaphragm wall penetrating the dewatering aquifer (D) and the filter length of pumping wells (L) are varied in the simulation. The relationship between approximate hydraulic gradient (Δi) or ground settlement outside the foundation pit (S) with curtain depth ratio RD (D over the thickness of the dewatering confined aquifer Ha) or filter length ratio RL (L/Ha) can be divided into three change parts, namely initial gradual, middle sharp and final gentle part. Three values of RD and RL, namely effective, suggested and control value, are proposed. RD and RL should vary between the effective and control value. The suggested value of RD and RL is recommended in actual engineering by comprehensive consideration. The effective, suggested and control value of RD can be calculated by a linear equation according to the value of RL.
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