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"Lai, Hong"
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Atomic cobalt as an efficient electrocatalyst in sulfur cathodes for superior room-temperature sodium-sulfur batteries
The low-cost room-temperature sodium-sulfur battery system is arousing extensive interest owing to its promise for large-scale applications. Although significant efforts have been made, resolving low sulfur reaction activity and severe polysulfide dissolution remains challenging. Here, a sulfur host comprised of atomic cobalt-decorated hollow carbon nanospheres is synthesized to enhance sulfur reactivity and to electrocatalytically reduce polysulfide into the final product, sodium sulfide. The constructed sulfur cathode delivers an initial reversible capacity of 1081 mA h g
−1
with 64.7% sulfur utilization rate; significantly, the cell retained a high reversible capacity of 508 mA h g
−1
at 100 mA g
−1
after 600 cycles. An excellent rate capability is achieved with an average capacity of 220.3 mA h g
−1
at the high current density of 5 A g
−1
. Moreover, the electrocatalytic effects of atomic cobalt are clearly evidenced by operando Raman spectroscopy, synchrotron X-ray diffraction, and density functional theory.
Room-temperature sodium-sulfur batteries hold promise, but are hindered by low reversible capacity and fast capacity fade. Here the authors construct a multifunctional sulfur host comprised of cobalt-decorated carbon nanospheres that impart attractive performance as a cathode in a sodium sulfide battery.
Journal Article
Morphology tuning of inorganic nanomaterials grown by precipitation through control of electrolytic dissociation and supersaturation
The precise control of the morphology of inorganic materials during their synthesis is important yet challenging. Here we report that the morphology of a wide range of inorganic materials, grown by rapid precipitation from a metal cation solution, can be tuned during their crystallization from one- to three-dimensional (1D to 3D) structures without the need for capping agents or templates. This control is achieved by adjusting the balance between the electrolytic dissociation (
α
) of the reactants and the supersaturation (
S
) of the solutions. Low-
α,
weak electrolytes promoted the growth of anisotropic (1D and 2D) samples, with 1D materials favoured in particular at low
S
. In contrast, isotropic 3D polyhedral structures could only be prepared in the presence of strong electrolyte reactants (
α
≈ 1) with low
S
. Using this strategy, a wide range of materials were prepared, including metal oxides, hydroxides, carbonates, molybdates, oxalates, phosphates, fluorides and iodate with a variety of morphologies.
Precipitation enables the straightforward production of a variety of inorganic materials, but the rapid reaction rates involved typically make controlling their morphologies difficult. Now, the growth of either one-, two- or three-dimensional materials has been promoted by tuning of the reactants’ electrolytic dissociation and solution supersaturation, without the need for capping agents and templates.
Journal Article
A top-down strategy for amorphization of hydroxyl compounds for electrocatalytic oxygen evolution
Amorphous materials have attracted increasing attention in diverse fields due to their unique properties, yet their controllable fabrications still remain great challenges. Here, we demonstrate a top-down strategy for the fabrications of amorphous oxides through the amorphization of hydroxides. The versatility of this strategy has been validated by the amorphizations of unitary, binary and ternary hydroxides. Detailed characterizations indicate that the amorphization process is realized by the variation of coordination environment during thermal treatment, where the M–OH octahedral structure in hydroxides evolves to M–O tetrahedral structure in amorphous oxides with the disappearance of the M–M coordination. The optimal amorphous oxide (FeCoSn(OH)
6
-300) exhibits superior oxygen evolution reaction (OER) activity in alkaline media, where the turnover frequency (TOF) value is 39.4 times higher than that of FeCoSn(OH)
6
. Moreover, the enhanced OER performance and the amorphization process are investigated with density functional theory (DFT) and molecule dynamics (MD) simulations. The reported top-down fabrication strategy for fabricating amorphous oxides, may further promote fundamental research into and practical applications of amorphous materials for catalysis.
A versatile top-down strategy has been shown to produce amorphous oxides through amorphization of corresponding hydroxides. This approach was used to generate various unitary, binary and ternary amorphous oxides for electrocatalytic oxygen evolution.
Journal Article
Circ_0008542 in osteoblast exosomes promotes osteoclast-induced bone resorption through m6A methylation
With an increasing aging society, China is the world’s fastest growing markets for oral implants. Compared with traditional oral implants, immediate implants cause marginal bone resorption and increase the failure rate of osseointegration, but the mechanism is still unknown. Therefore, it is important to further study mechanisms of tension stimulus on osteoblasts and osteoclasts at the early stage of osseointegration to promote rapid osseointegration around oral implants. The results showed that exosomes containing circ_0008542 from MC3T3-E1 cells with prolonged tensile stimulation promoted osteoclast differentiation and bone resorption. Circ_0008542 upregulated Tnfrsf11a (RANK) gene expression by acting as a miR-185-5p sponge. Meanwhile, the circ_0008542 1916-1992 bp segment exhibited increased m6A methylation levels. Inhibiting the RNA methyltransferase METTL3 or overexpressing the RNA demethylase ALKBH5 reversed osteoclast differentiation and bone resorption induced by circ_0008542. Injection of circ_0008542 + ALKBH5 into the tail vein of mice reversed the same effects in vivo. Site-directed mutagenesis study demonstrated that 1956 bp on circ_0008542 is the m6A functional site with the abovementioned biological functions. In conclusion, the RNA methylase METTL3 acts on the m6A functional site of 1956 bp in circ_0008542, promoting competitive binding of miRNA-185-5p by circ_0008542, and leading to an increase in the target gene RANK and the initiation of osteoclast bone absorption. In contrast, the RNA demethylase ALKBH5 inhibits the binding of circ_0008542 with miRNA-185-5p to correct the bone resorption process. The potential value of this study provides methods to enhance the resistance of immediate implants through use of exosomes releasing ALKBH5.
Journal Article
iProEP: A Computational Predictor for Predicting Promoter
Promoter is a fundamental DNA element located around the transcription start site (TSS) and could regulate gene transcription. Promoter recognition is of great significance in determining transcription units, studying gene structure, analyzing gene regulation mechanisms, and annotating gene functional information. Many models have already been proposed to predict promoters. However, the performances of these methods still need to be improved. In this work, we combined pseudo k-tuple nucleotide composition (PseKNC) with position-correlation scoring function (PCSF) to formulate promoter sequences of Homo sapiens (H. sapiens), Drosophila melanogaster (D. melanogaster), Caenorhabditis elegans (C. elegans), Bacillus subtilis (B. subtilis), and Escherichia coli (E. coli). Minimum Redundancy Maximum Relevance (mRMR) algorithm and increment feature selection strategy were then adopted to find out optimal feature subsets. Support vector machine (SVM) was used to distinguish between promoters and non-promoters. In the 10-fold cross-validation test, accuracies of 93.3%, 93.9%, 95.7%, 95.2%, and 93.1% were obtained for H. sapiens, D. melanogaster, C. elegans, B. subtilis, and E. coli, with the areas under receiver operating curves (AUCs) of 0.974, 0.975, 0.981, 0.988, and 0.976, respectively. Comparative results demonstrated that our method outperforms existing methods for identifying promoters. An online web server was established that can be freely accessed (http://lin-group.cn/server/iProEP/).
Journal Article
Understanding the charge transfer effects of single atoms for boosting the performance of Na-S batteries
The effective flow of electrons through bulk electrodes is crucial for achieving high-performance batteries, although the poor conductivity of homocyclic sulfur molecules results in high barriers against the passage of electrons through electrode structures. This phenomenon causes incomplete reactions and the formation of metastable products. To enhance the performance of the electrode, it is important to place substitutable electrification units to accelerate the cleavage of sulfur molecules and increase the selectivity of stable products during charging and discharging. Herein, we develop a single-atom-charging strategy to address the electron transport issues in bulk sulfur electrodes. The establishment of the synergistic interaction between the adsorption model and electronic transfer helps us achieve a high level of selectivity towards the desirable short-chain sodium polysulfides during the practical battery test. These finding indicates that the atomic manganese sites have an enhanced ability to capture and donate electrons. Additionally, the charge transfer process facilitates the rearrangement of sodium ions, thereby accelerating the kinetics of the sodium ions through the electrostatic force. These combined effects improve pathway selectivity and conversion to stable products during the redox process, leading to superior electrochemical performance for room temperature sodium-sulfur batteries.
Efficient charge transfer in sulfur electrodes is a crucial challenge for sodium-sulfur batteries. Here, the authors developed a machine-learning-assisted approach to quickly identify effective single-atom catalysts that enhance selectivity for short-chain sodium polysulfides, leading to improved battery performance.
Journal Article
Stabilization of soft soil using low-carbon alkali-activated binder
Soft soils pose significant challenges to the constructions on or within them, which are commonly stabilized with lime or ordinary Portland cement. However, these two binders are energy-intensive with high-carbon footprint. The current study presents an investigation of using an alkali-activated binder (AAB), a low-carbon cementitious material, for soft soil stabilization. Experiments including unconfined compressive strength test, compressibility test and hydraulic conductivity test were carried out to investigate the mechanical and hydraulic properties of soils stabilized with AAB of different concentrations. Microstructural characterizations of soil samples before and after AAB stabilization were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The experimental results show that the AAB can greatly improve the strength of the stabilized soil and meanwhile significantly reduce its compressibility and permeability. The strength of the stabilized soil increases with curing period and higher AAB concentration; the compressibility potential of original soil is noticeably reduced from medium to a low level after AAB stabilization; the hydraulic conductivity of soft soil stabilized with 20% AAB is more than 700 times smaller than that of the untreated. The microstructural characterizations using XRD, SEM and EDX confirm the formation of calcium aluminosiliate hydrate (CASH) gel in the stabilized soil matrix. This gel binds the soil particles and fills the voids between them and, therefore, increases the strength and reduces the compressibility and permeability of stabilized soil.
Journal Article
Physiological Effects of Neonicotinoid Insecticides on Non-Target Aquatic Animals—An Updated Review
In this paper, we review the effects of large-scale neonicotinoid contaminations in the aquatic environment on non-target aquatic invertebrate and vertebrate species. These aquatic species are the fauna widely exposed to environmental changes and chemical accumulation in bodies of water. Neonicotinoids are insecticides that target the nicotinic type acetylcholine receptors (nAChRs) in the central nervous systems (CNS) and are considered selective neurotoxins for insects. However, studies on their physiologic impacts and interactions with non-target species are limited. In researches dedicated to exploring physiologic and toxic outcomes of neonicotinoids, studies relating to the effects on vertebrate species represent a minority case compared to invertebrate species. For aquatic species, the known effects of neonicotinoids are described in the level of organismal, behavioral, genetic and physiologic toxicities. Toxicological studies were reported based on the environment of bodies of water, temperature, salinity and several other factors. There exists a knowledge gap on the relationship between toxicity outcomes to regulatory risk valuation. It has been a general observation among studies that neonicotinoid insecticides demonstrate significant toxicity to an extensive variety of invertebrates. Comprehensive analysis of data points to a generalization that field-realistic and laboratory exposures could result in different or non-comparable results in some cases. Aquatic invertebrates perform important roles in balancing a healthy ecosystem, thus rapid screening strategies are necessary to verify physiologic and toxicological impacts. So far, much of the studies describing field tests on non-target species are inadequate and in many cases, obsolete. Considering the current literature, this review addresses important information gaps relating to the impacts of neonicotinoids on the environment and spring forward policies, avoiding adverse biological and ecological effects on a range of non-target aquatic species which might further impair the whole of the aquatic ecological web.
Journal Article
Stringy scaling of multi-tensor hard string scattering amplitudes and the K-identities
A
bstract
We calculate
n
-point hard string scattering amplitudes (
HSSA
) with
n
− 2 tachyons and 2 tensor states at arbitrary mass levels. We discover the stringy scaling behavior of these
HSSA
. It is found that for
HSSA
with more than 2 transverse directions, the degree of stringy scaling dim
2
decreases comparing to the degree of stringy scaling dim
1
of the
n
− 1 tachyons and 1 tensor
HSSA
calculated previously. Moreover, we propose a set of
K
-identities which is the key to demonstrate the stringy scaling behavior of
HSSA
. We explicitly prove both the diagonal and off-diagonal
K
-identities for the 4-point
HSSA
and give numerical proofs of these
K
-identities for some higher point
HSSA
.
Journal Article