31 research outputs found

    Nickel Sulfide Freestanding Holey Films as Air-Breathing Electrodes for Flexible Zn–Air Batteries

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    In this work, a combination of bottom-up electrochemical deposition and top-down electrochemical etching strategies followed by a subsequent sulfuration treatment was employed to rationally synthesize a nickel sulfide (NiS<sub><i>x</i></sub>) freestanding holey film (FHF). Owing to the holey structure along with the optimal electrochemically active surface area and active sites, the as-prepared NiS<sub><i>x</i></sub> FHF showed an impressive bifunctional electrocatalytic performance toward both oxygen evolution and reduction reactions. The holey and freestanding features provide the NiS<sub><i>x</i></sub> FHF with promising characteristics to be used as an ideal air-breathing cathode in flexible Zn–air batteries (ZABs). As a proof-of-concept, the rationally designed NiS<sub><i>x</i></sub> FHF achieved remarkable rechargeability and flexibility in a ZAB configuration

    Oxidation as a Facile Strategy To Reduce the Surface Charge and Toxicity of Polyethyleneimine Gene Carriers

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    Polyethyleneimine (PEI) is widely regarded as one of the most efficient non-viral transfection agents commercially available. However, a key concern is its pronounced cytotoxicity, ascribed mainly to its high amine content and cationic charge density. Significant past efforts to mitigate its toxicity usually involved lengthy synthetic procedures. We now propose a simple strategy using hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) to oxidize the amine groups. PEI/DNA complexes were first formed before some amine groups were removed with H<sub>2</sub>O<sub>2</sub>. This reduced surface charge while the remaining cationic charges still allowed for efficient transfection. The DNA was not damaged and remained bound after oxidation. Furthermore, H<sub>2</sub>O<sub>2</sub> was quantitatively removed with sodium pyruvate prior to cell culture. Oxidized complexes caused no cytotoxicity even at high polymer concentrations. Compared to non-oxidized complexes used at subtoxic doses, oxidized complexes mediated significantly more GFP expression. A key strength of this approach is its simplicity as it involves only simple mixing of solutions. This strategy promises to further realize the potential of using PEI for the delivery of nucleic acids or other cargos

    The Mechanism and Fine-Tuning of Chiral Plexcitons in the Strong Coupling Regime

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    Chiral plexcitons, produced by the strong interaction between plasmonic nanocavities and chiral molecules, can provide a promising direction for controlling chiroptical responses on the nanoscale. Here, we reveal the chiral origin and electromagnetic hybridization process in chiral strongly coupled systems. The mechanism and unique advantages of chiral plexcitons for fine-tuning circular dichroism (CD) responses are demonstrated, providing a rule for controlling chiral light–matter interactions in complex chiral nanosystems. Furthermore, we experimentally demonstrate the fine-tuning of chiral plexcitons in hybrid systems consisting of plasmonic nanoparticles and chiral J-aggregates. Continuous and precise tuning of the CD resonance positions was successfully achieved in a given structure. Compared with the previous work, the CD spectral tuning accuracy has been improved by an order of magnitude, which can reach the level of 1 nm. Our findings provide a feasible strategy and theoretical basis for accurately controlling chirality in multiple dimensions

    Supplemental Data 1

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    Stratigraphic information and locality of Catenipora specimens for morphometric analysis

    An Asymmetric Supercapacitor with Both Ultra-High Gravimetric and Volumetric Energy Density Based on 3D Ni(OH)<sub>2</sub>/MnO<sub>2</sub>@Carbon Nanotube and Activated Polyaniline-Derived Carbon

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    Development of a supercapacitor device with both high gravimetric and volumetric energy density is one of the most important requirements for their practical application in energy storage/conversion systems. Currently, improvement of the gravimetric/volumetric energy density of a supercapacitor is restricted by the insufficient utilization of positive materials at high loading density and the inferior capacitive behavior of negative electrodes. To solve these problems, we elaborately designed and prepared a 3D core–shell structured Ni­(OH)<sub>2</sub>/MnO<sub>2</sub>@carbon nanotube (CNT) composite via a facile solvothermal process by using the thermal chemical vapor deposition grown-CNTs as support. Owing to the superiorities of core–shell architecture in improving the service efficiency of pseudocapacitive materials at high loading density, the prepared Ni­(OH)<sub>2</sub>/MnO<sub>2</sub>@CNT electrode demonstrated a high capacitance value of 2648 F g<sup>–1</sup> (1 A g<sup>–1</sup>) at a high loading density of 6.52 mg cm<sup>–2</sup>. Coupled with high-performance activated polyaniline-derived carbon (APDC, 400 F g<sup>–1</sup> at 1 A g<sup>–1</sup>), the assembled Ni­(OH)<sub>2</sub>/MnO<sub>2</sub>@CNT//APDC asymmetric device delivered both high gravimetric and volumetric energy density (126.4 Wh kg<sup>–1</sup> and 10.9 mWh cm<sup>–3</sup>, respectively), together with superb rate performance and cycling lifetime. Moreover, we demonstrate an effective approach for building a high-performance supercapacitor with high gravimetric/volumetric energy density

    Enhancing Electron Transfer and Electrocatalytic Activity on Crystalline Carbon-Conjugated g‑C<sub>3</sub>N<sub>4</sub>

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    Carbon nitride (g-C<sub>3</sub>N<sub>4</sub>) materials are electro-activated for oxygen reduction (ORR) and oxygen evolution (OER) reactions when they are supported by conductive carbons. However, the electrocatalytic process on semiconductor-based heterostructures such as carbon-supported g-C<sub>3</sub>N<sub>4</sub> still suffers from a huge energy loss because of poor electron mobility. Here, we demonstrated a concept that the conjugation of g-C<sub>3</sub>N<sub>4</sub> with crystalline carbon can improve the in-plane electron mobility and make interior triazine units more electro-active for ORR and OER. As a result, the Co metal coordinated g-C<sub>3</sub>N<sub>4</sub> with crystalline carbons (Co–C<sub>3</sub>N<sub>4</sub>/C) showed a remarkable electrocatalytic performance toward both ORR and OER. For example, it displayed an onset potential of 0.95 V for ORR and an overpotential of 1.65 V for OER at 10 mA cm<sup>–2</sup>, which are comparable and even better than those of benchmark Pt, RuO<sub>2</sub>, and other carbon nitride-based electrocatalysts. As a proof-of-concept application, we employed this catalyst as an air electrode in the rechargeable aluminum-air battery, which showed more rechargeable and practicable than those of Pt/C and RuO<sub>2</sub> catalysts in two-electrode coin battery. The characterization results identified that the good performance of Co–C<sub>3</sub>N<sub>4</sub>/C was primarily attributed to the enhanced in-plane electron mobility by crystalline carbon conjugation and the Co-coordinated g-C<sub>3</sub>N<sub>4</sub> along with nitrogen-doped carbons

    Detection of G‑Quadruplex Structures Formed by G‑Rich Sequences from Rice Genome and Transcriptome Using Combined Probes

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    Putative G-quadruplex (G4) forming sequences (PQS) are highly prevalent in the genome and transcriptome of various organisms and are considered as potential regulation elements in many biological processes by forming G4 structures. The formation of G4 structures highly depends on the sequences and the environment. In most cases, it is difficult to predict G4 formation by PQS, especially PQS containing G2 tracts. Therefore, the experimental identification of G4 formation is essential in the study of G4-related biological functions. Herein, we report a rapid and simple method for the detection of G4 structures by using a pair of complementary reporters, hemin and BMSP. This method was applied to detect G4 structures formed by PQS (DNA and RNA) searched in the genome and transcriptome of Oryza sativa. Unlike most of the reported G4 probes that only recognize part of G4 structures, the proposed method based on combined probes positively responded to almost all G4 conformations, including parallel, antiparallel, and mixed/hybrid G4, but did not respond to non-G4 sequences. This method shows potential for high-throughput identification of G4 structures in genome and transcriptome. Furthermore, BMSP was observed to drive some PQS to form more stable G4 structures or induce the G4 formation of some PQS that cannot form G4 in normal physiological conditions, which may provide a powerful molecular tool for gene regulation
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