Conversion of non-van der Waals solids to 2D transition-metal chalcogenides.

Although two-dimensional (2D) atomic layers, such as transition-metal chalcogenides, have been widely synthesized using techniques such as exfoliation1-3 and vapour-phase growth4,5, it is still challenging to obtain phase-controlled 2D structures6-8. Here we demonstrate an effective synthesis strategy via the progressive transformation of non-van der Waals (non-vdW) solids to 2D vdW transition-metal chalcogenide layers with identified 2H (trigonal prismatic)/1T (octahedral) phases. The transformation, achieved by exposing non-vdW solids to chalcogen vapours, can be controlled using the enthalpies and vapour pressures of the reaction products. Heteroatom-substituted (such as yttrium and phosphorus) transition-metal chalcogenides can also be synthesized in this way, thus enabling a generic synthesis approach to engineering phase-selected 2D transition-metal chalcogenide structures with good stability at high temperatures (up to 1,373 kelvin) and achieving high-throughput production of monolayers. We anticipate that these 2D transition-metal chalcogenides will have broad applications for electronics, catalysis and energy storage.

Determination of tolfenpyrad residues in green tea by GC-MS/MS based on acetonitrile extractant, dispersion solid phase extraction purification.

Green tea is one of people's favorite drinks. However, pesticide residues in green tea can cause harm to the human body, and therefore, detection of pesticide residues in green tea is very important. In recent years, the detection of pesticide residues in tea has become a research hotspot. In this paper, a gas chromatography-mass spectrometry/mass spectrometry (GC-MS/MS) detection method of tolfenpyrad pesticide residues in green tea was established by using acetonitrile extractant, dispersive solid-phase extraction purification, temperature programming and application retention time lock with the database. After the sample was extracted with acetonitrile, then the sample was purified by QuEChERS extraction purification tube, afterward isomer B was used as the internal standard for the determination by multiple reaction monitoring mode (MRM) of GC-MS/MS. The results indicated that the experimental data accorded with the criterion on quality control of laboratoris(chemical testing of food), and the requirements of recovery, calibration curve, precision.This method was used to detect tolfenpyrad residues in actual green tea samples in multiple batches, and the satisfactory results were obtained.

Bioinspired hierarchical cross-linked graphene-silicon nanofilms via synergistic interfacial interactions as integrated negative electrodes for high-performance lithium storage.

Inspired by the intrinsic relationship between sophisticated interfacial architecture and the outstanding mechanical performance of natural nacre, a flexible, large-area and robust bioinspired reduced graphene oxide-silicon-carboxymethyl cellulose-polyacrylic acid (rGO-Si-CMC-PAA) nanocomposite film with a hierarchically laminated structure was prepared via a vacuum-assisted filtration self-assembly process and a thermal condensation reaction. The as-prepared rGO-Si-CMC-PAA films exhibited a typical orderly layered structure with a thickness of about 40 µm, and Si nanoparticles were uniformly distributed and embedded throughout the continuous graphene network. As binder-free, integrated anodes for lithium-ion batteries (LIBs), the free-standing rGO-Si-CMC-PAA films exhibited appealing electrochemical lithium storage properties with a high reversible capacity (2153.49 mA h g-1), long-term cycling stability with 63% capacity retention even after 800 cycles at 420 mA g-1, and a superior rate capability. Therefore, the bioinspired strategy of synergistic interfacial interactions of hydrogen and covalent bonding also provides a promising avenue for constructing integrated high-performance graphene-based nanocomposite films in the future.

Gradient-Distributed Nucleation Seeds on Conductive Host for a Dendrite-Free and High-Rate Lithium Metal Anode.

Much attention is paid to metal lithium as a hopeful negative material for reversible batteries with a high specific capacity. Although applying 3D hosts can relieve the dendrite growth to some extent, gradient-distributed lithium ion in 3D uniform hosts still induces uncontrolled lithium dendrites growth, especially at high lithium capacity and high current density. Herein, a 3D conductive carbon nanofiber framework with gradient-distributed ZnO particles as nucleation seeds (G-CNF) to regulate lithium deposition is proposed. Based on such a unique structure, the G-CNF electrode exhibits a high average Coulombic efficiency (CE) of 98.1% for 700 cycles at 0.5 mA cm-2 . Even at 5 mA cm-2 , the G-CNF electrode performs a stable cycling process and high CE of 96.0% for over 200 cycles. When the lithium-deposited G-CNF (G-CNF-Li) anode is applied in a full cell with a commercial LiFePO4 cathode, it exhibits a stable capacity of 115 mAh g-1 and high retention of 95.7% after 300 cycles. Through inducing the gradient-distributed nucleation seeds to counter the existing Li-ion concentration polarization, a uniform and stable lithium deposition process in the 3D host is achieved even under the condition of high current density.

Atomic Layers of MoO2 with Exposed High-Energy (010) Facets for Efficient Oxygen Reduction.

Although 2D nanocrystals with exposed high-energy facets are highly desired in the field of catalysts due to their anticipant high catalytic activities, they are difficult to be gained. Here, atomic layers of metallic molybdenum dioxide (MoO2 ) with primarily exposed high-energy (010) facet are achieved via a facile carbothermic reduction approach. The resultant MoO2 exhibits single-crystalline, monoclinic, and ultrathin features with nearly 100% exposed (010) facet, which can significantly reduce reaction barriers toward the oxygen reduction reaction. As a consequence, the atomic layers of MoO2 exhibit high electrocatalytic activity, excellent tolerance to methanol, and good stability for the oxygen reduction reaction in alkaline electrolyte, superior to commercial Pt/C catalysts. It is believed that such new transition metal oxide catalysts with exposed high-energy facets have broad applications in the areas of energy storage and conversions.

Polyhedral-Like NiMn-Layered Double Hydroxide/Porous Carbon as Electrode for Enhanced Electrochemical Performance Supercapacitors.

Polyhedral-like NiMn-layered double hydroxide/porous carbon (NiMn-LDH/PC-x) composites are successfully synthesized by hydrothermal method (x = 1, 2 means different mass percent of porous carbon (PC) in composites). The NiMn-LDH/PC-1 composites possess specific capacitance 1634 F g-1 at a current density of 1 A g-1 , and it is much better than that of pure LDH (1095 F g-1 at 1 A g-1 ). Besides, the sample can retain 84.58% of original capacitance after 3000 cycles at 15 A g-1 . An asymmetric supercapacitor with NiMn-LDH/PC-1 as anode and activated carbon as cathode is fabricated, and the supercapacitor can achieve an energy density of 18.60 Wh kg-1 at a power density of 225.03 W kg-1 . The enhanced electrochemical performance attributes to the high faradaic pseudocapacitance of NiMn-LDH, the introduction of PC, and the 3D porous structure of LDH/PC-1 composites. The introduction of PC hinders serious agglomeration of LDH and further accelerates ions transport. The encouraging results indicate that these materials are one of the most potential candidates for energy storage devices.

In situ template synthesis of hollow nanospheres assembled from NiCo2S4@C ultrathin nanosheets with high electrochemical activities for lithium storage and ORR catalysis.

Transition-metal sulfide hollow nanostructures have received intensive attention in energy-related applications due to their unique structural features and high electrochemical activities. Here, a well-designed composite of NiCo2S4@C is successfully fabricated using a facile in situ template removal method. The obtained composite shows unique microstructures of hollow nanospheres (∼650 nm in diameter) assembled from ultrathin NiCo2S4@C nanosheets, in which numerous scattered NiCo2S4 nanoparticles are embedded in ultrathin carbon nanosheets, exhibiting mesoporous features with a high surface area of 247.25 m2 g-1. When used as anode materials for LIBs, NiCo2S4@C hollow nanospheres exhibit a high reversible capacity of 1592 mA h g-1 at a current density of 500 mA g-1, enhanced cycling performance maintaining a capacity of 1178 mA h g-1 after 200 cycles, and a remarkable rate capability. Meanwhile, the hollow nanospheres display excellent catalytic activity as ORR catalysts with a four-electron pathway and superior durability to that of commercial Pt/C catalysts. Their excellent lithium storage and ORR catalysis performance can be attributed to the rational incorporation of high-activity NiCo2S4 and ultrathin carbon nanosheets, as well as unique hollow microstructures, which offer efficient electron/ion transport, an enhanced electroactive material/electrolyte contact area, numerous active sites, and excellent structural stability.

Hierarchical NiMoO4 nanowire arrays supported on macroporous graphene foam as binder-free 3D anodes for high-performance lithium storage.

Novel three-dimensional (3D) NiMoO4 nanowire arrays (NWAs) grown directly onto the surface of macroporous graphene foams (GF) with robust adhesion were synthesized via a facile chemical vapor deposition (CVD) and subsequent hydrothermal route. The as-prepared NiMoO4 nanowires are composed of ultra-small nanoparticles (∼5 nm) with a diameter of 70-150 nm and are several micrometers in length. Such as-grown NiMoO4 NWA/3DGF composites are then evaluated as monolithic electrodes for lithium-ion batteries (LIBs) without the need of binders or metal-based current collectors. Benefitting from the unique three-dimensional arrayed architecture and characteristics with a high specific surface area and more active sites which facilitate fast electron and ionic transport within the electrode, the NiMoO4 NWA/GF composites deliver a high reversible specific capacity of 1088.02 mA h g(-1) at a current density of 200 mA g(-1) and 867.86 mA h g(-1) after 150 cycles (79.77% retention of the second cycle), and excellent rate capability. With the advantages of excellent electrochemical performance and a facile synthesis method, the NiMoO4 nanowire arrays supported on 3DGF exhibit great potential as anode materials for LIBs.

NiCo2S4 nanotube arrays grown on flexible nitrogen-doped carbon foams as three-dimensional binder-free integrated anodes for high-performance lithium-ion batteries.

Binary metal sulfides, especially NiCo2S4, hold great promise as anode materials for high-performance lithium-ion batteries because of their excellent electronic conductivity and high capacity compared to mono-metal sulfides and oxides. Here, NiCo2S4 nanotube arrays are successfully grown on flexible nitrogen-doped carbon foam (NDCF) substrates with robust adhesion via a facile surfactant-assisted hydrothermal route and the subsequent sulfurization treatment. The obtained NiCo2S4/NDCF composites show unique three-dimensional architectures, in which NiCo2S4 nanotubes of ∼5 µm in length and 100 nm in width are uniformly grown on the NDCF skeletons to form arrays. When used directly as integrated anodes for lithium-ion batteries without any conductive additives and binders, the NiCo2S4/NDCF composites exhibit a high reversible capacity of 1721 mA h g(-1) at a high current density of 500 mA g(-1), enhanced cycling performance with the capacity maintained at 1182 mA h g(-1) after 100 cycles, and a remarkable rate capability. The excellent lithium storage performances of the composites could be attributed to the unique material composition, a rationally designed hollow nanostructure and an integrated smart architecture, which offer fast electron transport and ion diffusion, enhanced material/-electrolyte contact area and facile accommodation of strains during the lithium insertion and extraction process.

Optically active multi-helical erythrocyte-like Ln(OH)CO3 (Ln = La, Ce, Pr and Sm).

Hierarchical erythrocyte-like Ln(OH)CO3 with nanosized chiral structure-induced circular dichroism responses were fabricated. The CD responses were observed not only in the UV region but also in the visible region, and are assigned to the electronic transitions from the valence band to the conduction band and the mixed coupling effect between the hierarchical left-handed-assembled Ln(OH)CO3 nanorods in the multi-helical RBC-like architecture.

Vertically aligned sulfur-graphene nanowalls on substrates for ultrafast lithium-sulfur batteries.

Although lithium-sulfur batteries have gained great interest owing to their high energy density, they lack suitable electrodes capable of rapid charging and discharging to enable a high power density critical for wide applications. Here, we demonstrate a simply electrochemical assembly strategy to achieve vertically aligned sulfur-graphene (S-G) nanowall onto electrically conductive substrates. Remarkably, in each individual S-G nanowalls, sulfur nanoparticles are homogeneously anchored in between of graphene layers and ordered graphene arrays arrange perpendicularly to the substrates, which are favorable for the fast diffusions of both lithium and electron. Moreover, the hierarchical and porous structures facilate the effective accommodation of the volume change of sulfur. As a consequence, a high reversible capacity of 1261 mAh g(-1) in the first cycle and over 1210 mAh g(-1) after 120 cycles with excellent cyclability and high-rate performance (over 400 mAh g(-1) at 8C, 13.36 A g(-1)) are achieved with these S-G nanowalls as cathodes for lithium-sulfur batteries, providing the best reported rate performance for sulfur-graphene cathodes to date.

Nanocrystal-constructed mesoporous CoFe2O4 nanowire arrays aligned on flexible carbon fabric as integrated anodes with enhanced lithium storage properties.

A novel and facile two-step strategy is successfully developed for the large-scale fabrication of hierarchical mesoporous CoFe2O4 nanowire arrays (NWAs) on flexible carbon fabric as integrated anodes for highly efficient and reversible lithium storage. The synthesis involves the co-deposition of uniform bimetallic (Co, Fe) carbonate hydroxide hydrate precursor NWAs on carbon fabric and subsequent thermal transformation to spinel CoFe2O4 without damaging the morphology. The as-prepared CoFe2O4 nanowires have unique mesoporous structures, which are constructed by many interconnected nanocrystals with sizes of about 15-20 nm. The typical size of the nanowires is in the range of 70-100 nm in width and up to several micrometers in length. Such a hybrid nanostructure electrode presented here not only simplifies electrode processing, but also promises fast electron transport/collection and ion diffusion, and withstands volume variation upon prolonged charge/discharge cycling. As a result, the binder-free CoFe2O4/carbon fabric composite exhibits a high reversible capacity of 1185.75 mA h g(-1) at a current density of 200 mA g(-1), and a superior rate capability. More importantly, a reversible capacity as high as ∼950 mA h g(-1) can be retained and there is no obvious decay after 150 cycles.

Identifying the origin of Laggera crispata (Vahl) Hepper & J. R. I. Wood based on UPLC fingerprinting and chemometrics.

In this study, thirty-four samples of Laggera crispata (Vahl) Hepper & J. R. I. Wood from five main production areas in Yunnan Province, were collected for experimentation. UPLC- PDA was used to generate fingerprints and the common peaks were analysed through R and SIMCA-P. L. crispata from different origins can be distinguished by OPLS-DA and PCA. The VIP values were compared, and 8 characteristic components with great differences were obtained. It was confirmed that the two characteristic components were chrysosplenetin and artemisetin, and the quantitative analysis was performed with these two compounds from L. crispata samples with different origins. Based on the variance analysis results, the most significant difference in the content of chrysosplendin and artemisin was in Lancang and Honghe and Lancang and Simao, respectively. The chrysosplenetin can be used as an important indicator for quality control and to trace the origin of L. crispata.

An Electrochemical Perspective of Aqueous Zinc Metal Anode.

Based on the attributes of nonflammability, environmental benignity, and cost-effectiveness of aqueous electrolytes, as well as the favorable compatibility of zinc metal with them, aqueous zinc ions batteries (AZIBs) become the leading energy storage candidate to meet the requirements of safety and low cost. Yet, aqueous electrolytes, acting as a double-edged sword, also play a negative role by directly or indirectly causing various parasitic reactions at the zinc anode side. These reactions include hydrogen evolution reaction, passivation, and dendrites, resulting in poor Coulombic efficiency and short lifespan of AZIBs. A comprehensive review of aqueous electrolytes chemistry, zinc chemistry, mechanism and chemistry of parasitic reactions, and their relationship is lacking. Moreover, the understanding of strategies for suppressing parasitic reactions from an electrochemical perspective is not profound enough. In this review, firstly, the chemistry of electrolytes, zinc anodes, and parasitic reactions and their relationship in AZIBs are deeply disclosed. Subsequently, the strategies for suppressing parasitic reactions from the perspective of enhancing the inherent thermodynamic stability of electrolytes and anodes, and lowering the dynamics of parasitic reactions at Zn/electrolyte interfaces are reviewed. Lastly, the perspectives on the future development direction of aqueous electrolytes, zinc anodes, and Zn/electrolyte interfaces are presented.

Efficacy of patient-controlled hydromorphone analgesia in those undergoing uterine fibroid artery embolization via the right radial artery.

Objective: To evaluate the efficacy and safety of patient-controlled analgesia (PCA) with hydromorphone as perioperative analgesia during uterine artery embolization (UAE) via the right radial artery. Patients and methods: A total of 33 patients with uterine fibroids, who underwent UAE at the authors' hospital between June 2021 and March 2022, were selected. Hydromorphone (10 â€‹mg) was dispensed into a 100 â€‹ml PCA pump with normal saline. Pump administration was initiated 15 â€‹min before the start of the procedure, and the intraoperative dose was adjusted according to patient pain level. A numerical rating scale was used to evaluate pain immediately after embolization, 5 â€‹min after embolization, at the end of the procedure, and 6, 12, 24, 48, and 72 â€‹h after the procedure. Side effects were also observed. Results: Thirty-three patients underwent uterine artery embolization via the right radial artery. Patient pain was well controlled at all time points surveyed, and patients reported satisfaction with analgesia. The median length of hospital stay was 5 days. There were 7 cases of adverse reactions, but no serious side effects were observed. Conclusion: Patients reported positive experiences with arterial embolization of uterine fibroids via the right radial artery. Hydromorphone PCA effectively controlled pain. The PCA pump is easy to operate, has a low incidence of adverse reactions, and offers economic benefits at the patient and institutional levels.

Photoinduced silver nanoparticles/nanorings on plasmid DNA scaffolds.

Biological scaffolds are being actively explored for the synthesis of nanomaterials with novel structures and unexpected properties. Toroidal plasmid DNA separated from the Bacillus host is applied as a sacrificial mold for the synthesis of silver nanoparticles and nanorings. The photoirradiation method is applied to reduce Ag(I) on the plasmid. The nanoparticles are obtained by varying the concentration of the Ag(I) ion solution and the exposure time of the plasmid-Ag(I) complex under UV light at 254 nm and room temperature. It is found that the plasmid serves not only as a template but also as a reductant to drive the silver nucleation and deposition. The resulting nanoparticles have a face-centered cubic (fcc) crystal structure and 20-30 nm average diameter. The detailed mechanism is discussed, and other metals or alloys could also be synthesized with this method.

Bioinspired synthesis of a hollow metallic microspiral based on a spirulina bioscaffold.

Bioinspired synthesis approaches aim to take advantage of the morphology and structural features of biological materials for the development of functional micro/nanodevices. In this Letter, we report that a unicellular algae known as a Spirulina was applied as a bioscaffold for the synthesis of hollow metallic Cu microspirals with length of 200-300 µm. The electroless deposition method was employed to cover the spirulina forming the spiral. The nanomechanical properties of the spiral were investigated by using the nanoindentation technique. The results showed the hardness and elastic modulus of the spiral were 0.63-0.68 GPa and 12.35-12.63 GPa, respectively. Other metallic or alloy spirals could also be synthesized by using the spirulina as a bioscaffold with low cost and high reproducibility, and the obtained spirals could be promising materials as functional micro/nanodevices for microelectromechanical systems.

Electrochemical and Mechanical Properties of Cathodically Protected X80 Steel in Different Temperature Soil.

For the application of X80 pipelines in Northeast China, it is important to establish the correct cathodic protection (CP) potential. To achieve this, potentiodynamic polarization; electrochemical impedance spectroscopy (EIS); a slow strain rate test (SSRT); and a scanning electron microscopy (SEM) fracture morphology analysis were carried out for an X80 steel gas pipeline at several temperatures in Heilongjiang Province, China. The results show that the hydrogen evolution potential of X80 steel in soil at different temperatures was about -900 mV (vs. CSE). The generated hydrogen atoms can be adsorbed on the surface of the pipelines to reduce the surface energy, or they can be diffused into the substrate and accumulate to the critical concentration, inducing the decohesion between different structures and generating additional plastic deformation through dislocation motion. With the peak impedance potential as the minimum potential and the hydrogen embrittlement potential as the maximum potential, the CP potential of X80 steel in the soil at 30 °C, 45 °C, and 60 °C ranged from -900 mV to -1100 mV (vs. CSE), temperatures at which the X80 steel does not corrode or cause hydrogen embrittlement.

Long-term cycling stability of NiCo2S4 hollow nanowires supported on biomass-derived ultrathin N-doped carbon 3D networks as an anode for lithium-ion batteries.

A bio-based N-doped carbon 3D network is designed to fabricate a composite anode for LIBs. Benefiting from the highly active substrate and the supported NiCo2S4 hollow nanowires, the composites exhibit an ultrahigh reversible capacity of 1198 mA h g-1 after 500 cycles, holding great potential for long-term applications.

MicroRNA­29­3p regulates the ß­catenin pathway by targeting IGF1 to inhibit the proliferation of prolactinoma cells.

The present study aimed to analyze the effects and underlying mechanisms of microRNA (miR)­29­3p on the proliferation and secretory abilities of prolactinoma cells by targeting insulin­like growth factor (IGF)­1/ß­catenin. The relationship between miR­29a­3p and the survival of prolactinoma cells was analyzed with the Kaplan­Meier method in reference to The Cancer Genome Atlas. The expression levels of miR­29a­3p and IGF­1 in MMQ and GH3 cells were detected. A dual­luciferase reporter gene assay was performed to verify the combination of miR­29a­3p and IGF­1. Cells were transfected with a miR­29a­3p mimic and/or IGF­1 pcDNA3.1 to analyze the effects on the proliferation, apoptosis and secretion of prolactin (PRL) and growth hormone (GH) of prolactinoma cells. The effects on ß­catenin in the cytoplasm and nucleus were investigated by western blot analysis. The results showed that miR­29a­3p expression was low in MMQ and GH3 cells. Overexpression miR­29a­3p inhibited IGF­1 mRNA and protein expression. miR­29a­3p inhibited cell proliferation and PRL and GH expression, and promoted apoptosis by inhibiting IGF­1. Increasing the expression of miR­29a­3p increased ß­catenin levels in the cytoplasm, whereas IGF­1 promoted ß­catenin activation and entry into the nucleus, and reversed the inhibitory effects of miR­29a­3p on ß­catenin. To conclude, miR­29a­3p inhibited the proliferation and secretory abilities of prolactinoma cells by inhibiting nuclear translocation of ß­catenin via a molecular mechanism that is inseparable from IGF­1.