33 research outputs found

    Novel layered 2D materials for ultrafast photonics

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    A range of new 2D materials have recently been reported, including topological insulators, transitionmetal dichalcogenides, black phosphorus, MXenes, and metal-organic frameworks, which have demonstrated high optical nonlinearity and Pauli blocking for widespread use as saturable absorbers in pulsed lasers. 2D materials are emerging as a promising platform for ultrashort- pulse fiber laser technology. This review presents a catalog of the various pulsed laser applications based on the series of emerging 2D materials. In addition, novel optical devices using layered materials, such as optical modulators, optical switches, and all-optical devices, are also included. It is anticipated that the development of 2D materials will intensify in the future, providing potentially new and wide-ranging efficacy for 2D materials in ultrafast photonic technology

    High-sensitivity salinity sensor based on optical microfiber coil resonator

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    A simple, compact, and high-sensitivity optical sensor for salinity measurement is reported based on an optical microfiber coil resonator (MCR). The MCR is manufactured by initially wrapping microfiber on a polymethylmethacrylate (PMMA) rod, which is dissolved to leave a hollow cylindrical fluidic channel within the coil for measurement. Based on the light propagation through the MCR, the device’s spectrum moves to long wavelengths with increased salinity in the fluid. The MCR device’s sensitivity can reach up to 15.587 nm/% with a resolution of 1.28 × 10-3%. It is also confirmed that the temperature dependence is 79.87 pm/°C, which results from the strong thermal-expansion coefficient of the low refractive index epoxy. The experimental results indicate that the device can be widely used as a high sensitivity salinity sensor in water and other liquids due to its stability, compactness, electromagnetic immunity, and high sensitivity

    Insights into Shape Selectivity and Acidity Control in NiO-Loaded Mesoporous SBA-15 Nanoreactors for Catalytic Conversion of Cellulose to 5‑Hydroxymethylfurfural

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    Facilitated isomerization of cellulose hydrolysis intermediate glucose without unexpected byproducts, which is the rate-determining step in the production of high-value-added biofuels, enables the efficient production of 5-hydroxymethylfurfural (5-HMF) from cellulose. In this work, considering the essential role of the acidity control and shape selectivity of a zeolite catalyst, a NiO-loaded mesoporous NiO/poly(vinyl pyrrolidone) (PVP)-phosphotungstic acid (HPA)@SBA-15 nanoreactor was prepared. This SBA-15 nanoreactor with a pore size of 5.47 nm reduced the concentration of byproducts formic acid (FA) and levulinic acid (LA) through shape selection for intermediates. Well-defined NiO nanoparticles (Ni-to-carrier mass ratio was 1:1) provided the NiO/PVP-HPA@SBA-15 nanoreactor a high Lewis acidity of 99.29 μmol g–1 for glucose catalytic isomerization, resulting in an increase in total reducing sugar (TRS) yield by 5 times. Such a nanoreactor remarkably improved the reaction efficiency of 5-HMF production from cellulose (a 5-HMF selectivity of 95.81%) in the 1-butyl-3-methylimidazolium chloride ([BMIM]Cl)/valerolactone (GVL) biphasic system

    Efficient Genome Editing in Most <i>Staphylococcus aureus</i> by Using the Restriction-Modification System Silent CRISPR-Cas9 Toolkit

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    Staphylococcus aureus is a clinically important pathogen that threatens human health due to its strong pathogenicity and drug resistance, leading to meningitis, endocarditis, and skin and soft tissue infections. Genetic manipulation in S. aureus is a powerful approach for characterizing the molecular mechanisms of bacterial drug resistance, pathogenicity, and virulence. However, a strong restriction barrier presents a major obstacle to the extensive utilization of genetic manipulation tools in clinical isolates of S. aureus. Here, we constructed a restriction-modification (RM) system silent CRISPR-Cas9 toolkit that synonymously eliminated the type I RM targets of S. aureus from plasmids, downsized plasmids using minicircle technology, and combined with a plasmid artificial modification (PAM) method to circumvent the type II RM system. The RM-silent CRISPR-Cas9 toolkit enables a significant improvement in transformation (105–106 transformants per microgram plasmid in strains we tested) and high-success efficiency editing for gene deletion (knockout strain obtained in one-round electroporation) in a wide range of S. aureus species including clinical isolates of unknown genetic background. The RM-silent CRISPR-Cas9 toolkits could expedite the process of mutant construction in most S. aureus strains, and this approach could be applied to the design of other genetic toolkit plasmids for utilization in a wider range of S. aureus strains

    Investigation of temperature dependence of microfibre coil resonators

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    The temperature-sensitive performance of a microfibre coil resonator (MCR) is thoroughly investigated. The MCR is fabricated by wrapping a microfibre on a PMMA rod coated with a UV-curable low refractive index epoxy. The temperature sensitivity is measured by investigating the correlation between the shift of the resonant wavelength and the surrounding temperature. It is determined that a range of parameters of the MCRs, including the gap between two adjacent rings, the diameter of the supporting rod, the number of rings, and the diameter of the microfibre have a great influence on the temperature sensitivity of the MCRs. By optimizing the fabrication parameters of MCRs, such as the gap of the adjacent microrings and the diameter of supporting rod etc, the maximum temperature sensitivity obtained is 237.31 pm/oC, which is about 2.3 times higher than that of MCR embedded in EFIRON UV-373 polymer and 23 times higher than that of MCR embedded in Teflon because of the strong thermo-optic and thermal expansion effects of the low refractive index epoxy and the supporting rod used in the experiments. Theoretical (numerical) simulation and experiment results are considered in the assessment of the optical performance improvement of MCR-based optical fibre temperature sensors

    Fabrication of Supported Cuprous Sites at Low Temperatures: An Efficient, Controllable Strategy Using Vapor-Induced Reduction

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    Selective reduction of supported CuO to Cu<sub>2</sub>O was realized using the strategy of vapor-induced reduction, in which HCHO/H<sub>2</sub>O vapor diffuses into the pores of the support and interacts with predispersed CuO. This new strategy allows the fabrication of supported cuprous sites at much lower temperatures within a short time, avoids the formation of Cu(0) with a Cu­(I) yield of nearly 100%, and results in materials with good adsorption performance, which is impossible to achieve by conventional methods

    Efficient Genome Editing in Most <i>Staphylococcus aureus</i> by Using the Restriction-Modification System Silent CRISPR-Cas9 Toolkit

    No full text
    Staphylococcus aureus is a clinically important pathogen that threatens human health due to its strong pathogenicity and drug resistance, leading to meningitis, endocarditis, and skin and soft tissue infections. Genetic manipulation in S. aureus is a powerful approach for characterizing the molecular mechanisms of bacterial drug resistance, pathogenicity, and virulence. However, a strong restriction barrier presents a major obstacle to the extensive utilization of genetic manipulation tools in clinical isolates of S. aureus. Here, we constructed a restriction-modification (RM) system silent CRISPR-Cas9 toolkit that synonymously eliminated the type I RM targets of S. aureus from plasmids, downsized plasmids using minicircle technology, and combined with a plasmid artificial modification (PAM) method to circumvent the type II RM system. The RM-silent CRISPR-Cas9 toolkit enables a significant improvement in transformation (105–106 transformants per microgram plasmid in strains we tested) and high-success efficiency editing for gene deletion (knockout strain obtained in one-round electroporation) in a wide range of S. aureus species including clinical isolates of unknown genetic background. The RM-silent CRISPR-Cas9 toolkits could expedite the process of mutant construction in most S. aureus strains, and this approach could be applied to the design of other genetic toolkit plasmids for utilization in a wider range of S. aureus strains

    Data_Sheet_1_Of its five acyl carrier proteins, only AcpP1 functions in Ralstonia solanacearum fatty acid synthesis.docx

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    The fatty acid synthesis (FAS) pathway is essential for bacterial survival. Acyl carrier proteins (ACPs), donors of acyl moieties, play a central role in FAS and are considered potential targets for the development of antibacterial agents. Ralstonia solanacearum, a primary phytopathogenic bacterium, causes bacterial wilt in more than 200 plant species. The genome of R. solanacearum contains five annotated acp genes, acpP1, acpP2, acpP3, acpP4, and acpP5. In this study, we characterized the five putative ACPs and confirmed that only AcpP1 is involved in FAS and is necessary for the growth of R. solanacearum. We also found that AcpP2 and AcpP4 participate in the polyketide synthesis pathway. Unexpectedly, the disruption of four acp genes (acpP2, acpP3, acpP4, and acpP5) allowed the mutant strain to grow as well as the wild-type strain, but attenuated the bacterium’s pathogenicity in the host plant tomato, suggesting that these four ACPs contribute to the virulence of R. solanacearum through mechanisms other than the FAS pathway.</p

    Designed Synthesis and Electrochemical Performance Regulation of the Hierarchical Hollow Structure Cu<sub>2</sub>S/Cu<sub>7</sub>S<sub>4</sub>/NC Anode for Hybrid Supercapacitors

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    Copper-based compounds have attracted increasing attention as electrode materials for rechargeable devices, but their poor conductivity and insufficient stability inhibit their further development. Herein, an effective method has been proposed to improve the electrochemical properties of the copper-based electrodes by coating carbon materials and generating unique micro/nanostructures. The prepared Cu2S/Cu7S4/NC with hierarchical hollow structure possesses excellent electrochemical performance, attributing to the composition and structure optimization. The superior charge storage performance has been assessed by theoretical and experimental research. Specifically, the Cu2S/Cu7S4/NC exhibits remarkably higher electrical conductivity and lower adsorption-free energy for O* and OH* than those of Cu2O. Moreover, the Cu2S/Cu7S4/NC delivers a high specific capacitance of 1261.3 F·g–1 at the current density of 1 A·g–1 and also has great rate performance at higher current densities, which are much better than those of the Cu2O nanocubes. In addition, the assembled hybrid supercapacitor using Cu2S/Cu7S4/NC as the anode exhibits great energy density, power density, and cycling stability. This study has proposed a novel and feasible method for the synthesis of high-performance copper-based electrodes and their electrochemical performance regulation, which is of great significance for the advancement of high-quality electrode materials and rechargeable devices
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