Latest ArticlesCarbonate radical is among the most important environmental relevant reactive species which govern the transformation and fate of pharmaceutical contaminants (PCs). However, reaction rate constants between carbonate radical and most of the PCs have not been experimentally determined, and quantitative structural-activity relationships (QSARs) have not been established for rate estimation. This study applied MaxMin data processing method and used molecular fingerprints (MF) as the input of a deep neural network (DNN) to predict the rate constants between carbonate radical and organic compounds. MF parameters and the hyper-structure of the DNN were adjusted to yield satisfactory accuracy of rate prediction. The vector length of 512 bits with radius of 1 for MF and 5 hidden layers gave the best performance. The optimized MaxMin-MF-DNN model was compared with some of the most commonly used QSARs and machine learning methods, including random data splitting, molecular descriptors, supporting vector machine, decision tree, etc. Results showed that the MF-DNN model out-performed the other methods by more than 10% increase in prediction accuracy. Applying this MF-DNN model, we estimated reaction rates between carbonate radical and pharmaceuticals used in human medicine (1576) and veterinary practice (390). Among them, 46 drugs were identified as fast-reacting compounds, suggesting the important relations of their environmental fate with carbonate radical.
Unremitting and intensive researches about efficient non-precious metal electrocatalysts are necessary for large-scale commercial applications of fuel cells, while iron and nitrogen co-doped carbon (Fe-N-C) materials has become one of the most promising electrocatalysts to replace Pt-based noble metal catalysts. However, the traditional Fe-doped ZIF with rhomb dodecahedron morphology limits the exposure of active sites and the utilization of atoms, even affecting the performance of the catalyst. Herein, a Fe/N co-doped catalyst with a flower-like morphology was prepared using ferric citrate source along with secondary NH3 heat treatment. The optimal catalyst (termed as 4Fecitrate-N-C-3) showed distinguished oxygen reduction reaction (ORR) activity with a half-wave potential of 0.8 and 0.9 V (vs. RHE) in acid and alkaline media, respectively. In addition, 4Fecitrate-N-C-3 maintained more than 80% of original activity even after 50,000 s which is superior to the benchmark Pt/C. The strategy of controlling morphology and composition is meaningful for the optimization of non-precious metal electrocatalysts for ORR in fuel cells or metal-air batteries.
Two-dimensional (2D) transition metal dichalcogenide (TMD) nanosheets have attracted considerable attention owing to their diverse properties and great potential in a wide range of applications. In order to further tune their properties and then broaden their application domain, large efforts have been devoted into engineering the structures of 2D TMD nanosheets at atomic scale, especially the alloying technology. Alloying different 2D TMD nanosheets into 2D alloys not only offers the opportunities to fine-tune their physical/chemical properties, but also opens up some unique properties, which are highly desirable for wide applications including electronics, optoelectronics and catalysis. This review summarizes the recent progress in the preparation, characterization and applications of 2D alloyed TMD nanosheets.
The typical aza-BODIPYs in the dye family are known for bright fluorescence, excellent stability, and tunable absorption wavelengths. Hence, these dyes are attracting the increasing attention. Aza-BODIPYs having the maxima absorption in the near-infrared (NIR) region (650–900 nm) are very favorable for bioimaging in vivo due to the less photo-damage, deeper tissue penetration, and less interference from background auto-fluorescence by biomolecules in the living systems. Many strategies have been employed to modify the structures of the aza-BODIPY core to provide the NIR absorbing dyes. Among these, the most effective method is the fusion of the aromatic rings in aza-BODIPY system. This review allsidedly summarizes the recent development of ring-fused aza-BODIPY dyes (λabs > 700 nm) focusing on the design, synthesis, and potential applications in the NIR region since 2002.
Transitional metal selenides have high conductivity, even metal quality, which makes them great for using as electrode materials for fabricating supercapacitors. Here, hierarchical Ni3Se2 nanosheet-on-nanorods on Ni foam (NSR-Ni3Se2/Ni) was fabricated by a facile three-dimensional (3D) substrate-assisted confinement assembly method, and used as a freestanding electrode material for hybrid supercapacitors (HSCs). In this design, metallic Ni3Se2 with hybrid 1D/2D architecture could effectively enhance the active specific surface area of electrode and improve space utilization, as well as significantly facilitate electrons transport, while Ni foam served as the Ni source of Ni3Se2 and provided 3D multi-electron transport channels, thus boosting the specific capacity. The constructed hierarchical NSR-Ni3Se2 electrode delivered a superior areal specific capacity of 1.068 mAh/cm2 (7.69 F/cm2) at 2 mA/cm2 and retained 68.2% of the initial capacity when the current density increases by 15 times. Furthermore, the as-assembled NSR-Ni3Se2 device exhibited an ultrahigh energy density of 56.4 Wh/kg and high power density of 4640.3 W/kg, and a capacity retention of 92.6% even after 6000 cycles.
Li‒S batteries have shown great potential as secondary energy batteries. However, the side reaction between Li anodes and polysulfides seriously limited their practical application. Herein, the artificial protective film, which is consisted of Li-Nafion and TiO2, was designed and successfully prepared to achieve a corrosion-resistant Li anode in Li-S battery. In the composite protective film, the Li-Nafion could efficiently prevent the contact between Li anodes and polysulfides, and the incorporation of TiO2 nanoparticles into the Nafion could significantly increase the ionic conductivity and mechanical strength of the protective film. Li-Li symmetric cells with an optimal artificial protective film exhibited an extended cycle-life of 750 h at a current density of 1 mA/cm2 in Li2S8 electrolyte. Moreover, the Li‒S full battery with an optimal protective Li anode exhibited higher capacity retention of 777.4 mAh/g after 100 cycles at 0.1 C as well as better rate performance than the cell with a pure Li anode. This work provides alternative insights to suppress the side reaction for Li‒S batteries with high capacity retention.
Carbonaceous nanomaterials with porous structure have become the highly promising anode materials for potassium-ion batteries (PIBs) due to their abundant resources, low-cost, and excellent conductivity. Nevertheless, the sluggish reaction kinetics and inferior cycling life caused by the large radius of K ions severely restrict their commercial development. Herein, B,N co-doped hierarchically porous carbon nanosheets (BNPC) are achieved via a facile template-assisted route, followed by a simple one-step carbonization process. The resultant BNPC possesses a unique porous structure, large surface area, and high-level B,N co-doping. The structural features endows it with remarkable potassium storage performances, which delivers a high reversible capacity (242.2 mAh/g at 100 mA/g after 100 cycles), and long cycling stability (123.1 mAh/g at 2000 mA/g and 62.9 mAh/g at 5000 mA/g after 2000 cycles, respectively). Theoretical simulations further validate that the rich B doping into N-modified carbon configuration can greatly boost the potassium storage capability of the BNPC anode.
Organic single crystals (OSCs) have received increasing interest in the last decades for their potential applications in flexible electronics. Although there are various subtractive manufacturing methods of organic electronics, the subtractive manufacturing of OSCs is still a challenge, since OSCs are assembled via weak van-der-Waals interactions which are vulnerable and cannot afford damages and suffer the degradation of performances after the process. Here, we develop an epitaxial etching strategy which clips the OSCs and keeps high-quality crystalline nature of the resulting materials. As a result, high-quality organic micro-ribbon arrays are fabricated which maintains 89% charge mobility in average compared with original OSCs, showing great potential of this subtractive manufacturing method in future organic electronics.
Lanthipeptides are one of the largest groups of ribosomally synthesized and post-translationally modified peptides (RiPPs) and are characterized by the presence of lanthionine (Lan) or methyllanthionine residues (MeLan). Only very few lanthipeptides contain a C-terminal 2-aminovinyl-cysteine (AviCys) motif, but all of them show potent antibacterial activities. Recent advances of genome sequencing led to the rapid accumulation of new biosynthetic gene clusters (BGCs) for lanthipeptides. In this study, through our genome mining strategy, we found the AviCys containing lanthipeptides are widespread in the bacterial kingdom. A lanthipeptide-type biosynthetic gene cluster was identified from public bacterial genome database. Two new lanthipeptides, daspyromycins A and B (1 and 2) containing AviCys motif, along with two degraded products, daspyromycins C and D (3 and 4), were obtained after heterologous expression of the gene cluster in Streptomyces albus J1074. Daspyromycins A and B showed potent antimicrobial activity against a spectrum of Gram-positive and -negative bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE).
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