Electrochemical exfoliation of two-dimensional layered black phosphorus and applications

With the discovery of graphene,black phosphorus(BP)has been rediscovered as a two-dimensional(2 D)layered material.Since its first preparation in 2014,2 D BP has elicited immense interest,and has exhibited excellent properties,such as distinct pleated structures in layers,adjustable direct bandgap,high carrier mobility,moderate on/off ratio,large specific surface area,and various interesting in-layer anisotropies.However,the realization of these excellent properties depends on the preparation of highquality 2 D BP sheets.Electrochemical exfoliation methods are typically performed under mild conditions,thus,these methods are convenient,controllable,and can produce high-quality 2 D BP sheets.This review summarizes research progress in BP sheets preparation through anodic,cathodic,and electrolyte exfoliation in recent years.Different exfoliating methods affect the quality of 2 D BP sheets.Moreover,possible exfoliating mechanisms and the potential applications of different exfoliating methods are summarized and discussed in detail.Lastly,the shortcomings of existing research on electrochemical exfoliation are presented,and suggestions and prospects for future research on the electrochemical exfoliation of 2 D BP are proposed.

Two-Step Preparation of Hierarchical Porous Carbon Materials Derived from Tannin for Use as an Electrode Material for Supercapacitors

The development and utilization of biomass and agroforestry processing byproducts for high-value applications have been an important topic in the field of renewable materials research.Based on this,a two-step microwave hydrothermal pre-carbonization and KOH activation method was proposed to synthesize tannin-based activated carbons with a high specific surface area,hierarchical pore structure,and good electrochemical performance.The microstructure,texture properties,and physicochemical characteristics were investigated.The results show that the prepared tannin-based activated carbons presented a hierarchical pore structure(micro-and mesopores)with a specific surface area as high as 997.46 m^(3) g^(−1).The electrochemical analysis shows that the tannin-based activated carbons have good wettability and charge transfer rates.Under the three-electrode system with 6 M KOH as the electrolyte,the active material TAC_(600-4) had a maximum specific capacitance of 171 F g^(−1)at 0.5 A g^(−1).As the current density increases to 10 A g^(−1),the specific capacitance can still be maintained at 149 F g^(−1),indicating a good rate capability.Therefore,the specific surface area and pore size of tannin-based activated carbons can be effectively adjusted by the alkali/carbon ratio,making it a promising supercapacitor electrode material and providing a new method for the high-value development of tannins in the field of electrochemical energy storage.

Prevalence and molecular characteristics of Listeria monocytogenes in cooked products and its comparison with isolates from listeriosis cases

This study aimed to investigate the prevalence and molecular characteristics ofListeria monocytogenes in cooked products in Zigong City, China. The overall occurrence of the L. monocytogenes in the ready-to-eat （RTE） shops and mutton restaurants surveyed was 16.2% （141/873）. An occurrence of 13.5% was observed in RTE pork, 6.5% in RTE vegetables, and more than 24.0% in either cooked mutton or cooked haggis. Serotype 1/2b （45.4%）, 1/2a （33.3%）, and 1/2c （14.2%） were the predominant types. By comparing the clonal complexes （CCs） based on multilocus sequence typing （MLST） of the L. monocytogenes from cooked foods in Zigong City and 33 listeriosis cases from different districts of China, CC87, CC9, CC8, and CC3 were showed to be prevalent in cooked products and CC87 and CC3 were the first two frequent types in the 33 clinic-source strains. All CC87 stains harbored the newly reported Listeria pathogenicity island 4 （LIPI-4） gene fragment ptsA, and all CC3 strains possessed the Listeria pathogenicity island 3 （LIPI-3） gene fragment llsX. These may increase the occurrence of the strains belonging to CC87 and CC3 in listeriosis cases in China and also underline the risk of infection owing to the consumption of the cooked products from Zigong. ST619 （serotype 1/2b） harbored both llsX and ptsA, indicating a potential hypervirulent sequence type in Zigong.

Frontiers in circularly polarized luminescence:molecular design,self-assembly,nanomaterials,and applications

The research in circularly polarized luminescence has attracted wide interest in recent years.Efforts on one side are directed toward the development of chiral materials with both high luminescence efficiency and dissymmetry factors,and on the other side,are focused on the exploitations of these materials in optoelectronic applications.This review summarizes the recent frontiers(mostly within five years)in the research in circularly polarized luminescence,including the development of chiral emissive materials based on organic small molecules,compounds with aggregation-induced emissions,supramolecular assemblies,liquid crystals and liquids,polymers,metal-ligand coordination complexes and assemblies,metal clusters,inorganic nanomaterials,and photon upconversion systems.In addition,recent applications of related materials in organic light-emitting devices,circularly polarized light detectors,and organic lasers and displays are also discussed.

Enhancement of municipal sludge dewaterability by electrochemical pretreatment

Electrolysis is a promising technology to improve sludge dewaterability efficiently with negligible environmental impact. To intensify the electrolytic efficiency, the effect of electrolytes(NaCl, Na_2SO_4, NaNO_3, and NaClO_4) on electrolysis pretreatment of municipal sludge and its mechanisms was investigated using Ti/PbO_2 electrodes. The electrolytes,which enhanced the production of oxidative radicals, showed a significant synergetic effect in reducing the capillary suction time(CST) of sludge. NaCl was distinguished from the other electrolytes since it formed a large amount of active chlorine species, which oxidized the sludge cells to improve the sludge dewaterability. The surface morphologies as well as the soluble proteins and polysaccharides were analyzed to unravel the underlying mechanisms of sludge dewaterability. Additionally, an economic assessment showed that NaCl addition in the electrolysis pretreatment can be a suitable technique for enhancing municipal sludge dewaterability.

Electrospinning Janus Type CoO_(x)/C Nanofibers as Electrocatalysts for Oxygen Reduction Reaction

Nanofibers with unique structures and multiple components have attracted more and more attention,which could combine multi-functions in one entity.Janus-type biphasic nanofibers with unique structure can be quickly obtained by electrospinning technology.We produced CoO_(x)/C nanofibers with Janus structure by self-made side-by-side electrospinning spinneret,combined with electrospinning technology and heat treatment.CoO_(x)/C nanofibers had a large amount of graphitic carbon distributed on one half of the Janus nanofiber,and CoO_(x)/C nanoparticles were embedded in the other half of the Janus nanofiber and distributed uniformly.CoO_(x)/C acted as ORR catalysis,and graphitic carbon,pridinc-N and CoO_(x) in CoO_(x)/C had a synergistic effect on their catalytic activity.The results confirmed that CoO_(x)/C was dominated by four-electron pathway under alkaline conditions,and the Tafel slope was lower than that of commercial Pt/C catalysts.The preparation method of this work is simple and easy,the structure is controllable,and the composition is adjustable,which provides a feasible way for preparing Janus structure nanofibers with different functions.

Staged angioplasty versus regular carotid artery stenting in patients with carotid artery stenosis at high risk of hyperperfusion:a randomised clinical trial

Background and purpose Hyperperfusion(HP)is a devastating complication associated with carotid artery stenting(CAS)or endarterectomy.The efficacy and safety of staged angioplasty(SAP)in patients with CAS at high risk of HP remains unclear.We sought to determine whether SAP is superior to regular CAS in patients with high risk of HP.Methods A randomised,multicentre open-label clinical trial with blinded outcome assessment(STEP)was conducted.Patients with severe carotid stenosis at high risk of HP were randomly assigned(1:1)to the SAP or regular CAS group.The primary endpoint was hyperperfusion syndrome(HPS)and intracerebral haemorrhage(ICH)within 30 days after the procedure.Results From November 2014 to January 2017,a total of 64 patients were enrolled in 11 centres.33 patients were allocated to the SAP group and 31 to the regular CAS group.At 30 days,the rate of primary endpoint was 0.0%(0/33)in the SAP group and 9.7%(3/31)in the regular CAS group(absolute risk reduction(ARR),9.7%;95%CI−20.1% to 0.7%;p=0.11).As one of the secondary endpoints,the incidence of HP phenomenon(HPP)was lower in the SAP group than the regular CAS group(0.0%vs 22.6%,ARR,−22.6%;95% CI−36.8%to−10.2%;p=0.04).Conclusion The rate of HPS and ICH was not significantly lower in SAP group;the extended secondary endpoint of HPP,however,significantly reduced,which suggested that SAP may be a safe and effective carotid revascularisation procedure to prevent HP.

Shoot rot of Zizania latifolia and the first record of its pathogen Pantoea ananatis in China

The aquatic grass Zizania latifolia grows symbiotically with the fungus Ustilago esculenta producing swollen structures called Jiaobai,widely cultivated in China.A new disease of Z.latifolia was found in Zhejiang Province,China.Initial lesions appeared on the leaf sheaths or sometimes on the leaves near the leaf sheaths.The lesions extended along the axis of the leaf shoots and formed long brown to dark brown streaks from the leaf sheath to the leaf,causing sheath rot and death of entire leaves on young plants.The pathogen was isolated and identified as the bacterium Pantoea ananatis,based on 16 S ribosomal RNA(r RNA)gene sequencing,multilocus sequence analysis(atp D(β-subunit of ATP synthase F1),gyr B(DNA gyrase subunit B),inf B(translation initiation factor 2),and rpo B(β-subunit of RNA polymerase)genes),and pathogenicity tests.Ultrastructural observations using scanning electron microscopy revealed that the bacterial cells colonized the vascular tissues in leaf sheaths,forming biofilms on the inner surface of vessel walls,and extended between vessel elements via the perforated plates.To achieve efficient detection and diagnosis of P.ananatis,species-specific primer pairs were designed and validated by testing closely related and unrelated species and diseased tissues of Z.latifolia.This is the first report of bacterial sheath rot disease of Z.latifolia caused by P.ananatis in China.

Multi‑color Tunable and White Circularly Polarized Luminescent Composite Nanofibers Electrospun from Chiral Helical Polymer

Circularly polarized luminescence(CPL)-active nanomaterials have attracted tremendous attention.However,it is still a big challenge to conveniently fabricate multi-color and white CPL-active nanomaterials on a large scale.Herein,a simple and scalable approach to achieve the above goals is presented.Multicolor CPL-active nanofibers are fabricated from chiral helical substituted polyacetylene,achiral fluorescent dyes and polyacrylonitrile via uniaxial electrospinning;the highest luminescence dissymmetry factor(glum)of the resulting nanofibers can reach 10^(−2).Furthermore,white CPL-active nanofibers are obtained by coaxial electrospinning,in which the resulting core-shell structure has excellent adjustability and can be utilized to physically isolate different fluorescent dyes to reduce energy transfer efficiency;therefore,stable white CPL emissions can be achieved with high g_(lum) values up to 10^(−3).Notably,the prepared white-emission CPL nanofibrous films show bright white circularly polarized light when coated on UV chips,demonstrating their future application in constructing low-cost and flexible light-emitting devices such as circularly polarized light-emitting diodes.