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The content of harmonic current increases with an increase in the number of power electronic devices in power grid. When a generator is directly connected to the power grid through a step-up transformer, the influence of the harmonic currents on the generator is inevitable. To study the influences of harmonics on generators, a 24-MW bulb tubular turbine generator is taken as an example in this paper. A 2-D transient electromagnetic field model is established. Through a comparative analysis of the data of experiments and simulations, the correctness of the model is verified. The values of the air gap magnetic density, torque and losses of the generator under various conditions are calculated using the finite element method. Taking the rated condition as a reference, the influence of the harmonic currents on the magnetic flux density is analyzed. It is confirmed that the time harmonic is a key factor affecting the generator performance. At the same time, the effects of harmonic currents on the torque ripple, average torque and eddy current loss of the generator are studied, and the mechanism of the variation of the eddy current loss is also discussed. [ABSTRACT FROM AUTHOR]

Aberrant expression of microRNAs (miRNAs) underlies a spectrum of human diseases including organ fibrosis, and hepatic stellate cells (HSCs) are the main effectors of hepatic fibrosis. Here, we showed that the expression of host miR-351 in HSCs was markedly reduced during the early stage of Schistosoma infection. However, this expression was significantly increased during the later stage of infection (after 52 d of infection). The elevated levels of miR-351 promoted hepatic fibrosis by targeting the vitamin D receptor (VDR), which is an antagonist of SMAD signaling. Importantly, efficient and sustained inhibition of miR-351 in liver tissues using the highly hepatotropic recombinant adeno-associated virus serotype 8 (rAAV8), alleviated the hepatic fibrosis, partially protecting the host from lethal schistosomiasis. In addition, we found that miR-351 is negatively regulated by IFN-γ in HSCs during infection. At the early stage of infection, the elevated levels of IFN-γ inhibited the expression of miR-351 in HSCs through activation of signal transducer and activator of transcription 1 and induction of IFN regulatory factor 2, which binds the promotor of pre-miR-351. Our study provides insights into the mechanisms by which miR-351 regulates schistosomiasis hepatic fibrosis and highlights the potential of rAAV8-mediated miR-351 inhibition as a therapeutic intervention for fibrotic diseases. [ABSTRACT FROM AUTHOR]

In order to analyze the influence of three-phase asymmetrical operation of a generator on its stable operation, firstly, taking a 24-MW bulb turbine generator as an example, the 2-D transient electromagnetic field model is established. Through the comparison analysis of the experimental results and simulation data, the correctness of the model is verified. Secondly, the values of air gap flux density, torque and loss in different conditions are obtained by using the finite element method. The effects of asymmetric three-phase current on air gap flux density, torque and loss are determined. Thirdly, the corresponding relationships between the three-phase current unbalance degree and torque ripple, eddy current loss are established, and the variations of torque ripple and eddy current loss are given when the three-phase current unbalance degree is changed. The result shows that the asymmetry three-phase current makes the torque ripple and eddy current loss increase dramatically, which seriously threaten the safe and stable operation of the generator. Finally, the further study on the torque ripple and eddy current loss of the generator under different current distributions and the same three-phase unbalance degree identifies that the content of negative sequence current is a key factor to affect the torque ripple and eddy current loss. [ABSTRACT FROM AUTHOR]

The major reasons that cause the damage of damper bars in the leeward side are found in this paper. It provides a route for the structure optimization design of a hydro generator. Firstly, capacity of a 24 MW bulb tubular turbine generator is taken as an example in this paper. The transient electromagnetic field model is established, and the correctness of the model is verified by the comparison of experimental results and simulation data. Secondly, when the generator is operated at rated condition, the eddy current density distributions of damper bars are studied. And the asymmetric phenomenon of the eddy current density on damper bars is discovered. The change laws of the eddy currents in damper bars are determined through further analysis. Thirdly, through the study of eddy current distributions under different conditions, it is confirmed that the stator slots and armature reaction are the main factors to affect the asymmetric distribution of the eddy current in damper bars. Finally, the studies of the magnetic density distribution and theoretical analysis revealed the asymmetric distribution mechanism of eddy current density. [ABSTRACT FROM AUTHOR]

According to the fluid mechanics and rolling theory, the rolling interface friction dynamic characteristics and their influence on rolling speed, rolling load, roller material, rolling temperature and oil properties were studied respectively with lubrication or without lubrication in hot rolling. The two-dimensional Reynolds equation was established for steady and unsteady rolling friction interface. Through the research of rolling interface friction characteristics influence on the mill vibration, we found that when the lubrication film thickness in the roll gap was thicker, the friction coefficient was lower, its damping effect and system stability was worse. And if the rolling speed is greater than a certain value, the rolling interface friction coefficient will fall sharply with the increase of rolling speed and produces the self-excited vibration caused by negative damping. So the contrast test with different rolling interface has been carried out, such as the emulsion is open or close, high chromium cast iron/high speed steel roller is put to use, high chromium cast iron roller is grinded finely or coarsely, rolling speed is normal/reduced. And the results showed that it had an obvious effect on the mill vibration suppression by the adoption of the emulsion close and high speed steel roller. [ABSTRACT FROM AUTHOR]

The controlled exfoliation of transition metal dichalcogenides (TMDs) into pristine single- or few-layer nanosheets remains a significant barrier to fundamental studies and device applications of TMDs. Here we report a novel strategy for exfoliating crystalline MoS2 into suspensions of nanosheets with retention of the semiconducting 2H phase. The controlled reaction of MoS2 with substoichiometric amounts n-butyllithium results in intercalation of the edges of the crystals, which are then readily exfoliated in a 45 vol % ethanol-water solution. Surprisingly, the resulting colloidal suspension of nanosheets was found (by electron microscopy and atomic force microscopy) to consist mostly of trilayers. The efficiency of exfoliation of the pre-intercalated sample is increased by at least 1 order of magnitude relative to the starting MoS2 microcrystals, with a mass yield of the dispersed nanosheets of 11-15%. [ABSTRACT FROM AUTHOR]

Exfoliated 2H molybdenum disulfide(MoS2) has unique properties and potential applicationsin a wide range of fields, but corresponding studies have been hamperedby the lack of effective routes to it in bulk quantities. This studypresents a rapid and efficient route to obtain exfoliated 2H MoS2, which combines fast sonication-assisted lithium intercalationand infrared (IR) laser-induced phase reversion. We found that thecomplete lithium intercalation of MoS2with butyllithiumcould be effected within 1.5 h with the aid of sonication. The 2Hto 1T phase transition that occurs during the lithium intercalationcould be also reversed by IR laser irradiation with a DVD opticaldrive. [ABSTRACT FROM AUTHOR]

Strip mill vibration greatly affects the quality of products, rolling productivity, and even cause strip broken or equipment damage. In order to explore the serious vibration phenomena occured in CSP (Compact Strip Production) hot strip mill when rolling thin container strips, in this paper we established a mill main drive system nonlinear torsional vibration model, and emphatically studied the influence of rolling load, multi-stand coupling (tension) and interface friction on the torsional vibration of the system; Based on numerical simulation, field measurement and signal time-frequency analysis (Wigner-Ville distribution), we analyzed the mills torsional vibration and horizontal vibration characteristics, the influence of multi-stand coupling (tension) on the rolls torsional vibration. [ABSTRACT FROM AUTHOR]

Mesoporous Cu2O spheres with a large pore size (LP-Cu2O) bring out a better performance towards the photocatalytic aza-Henry reaction than Cu2O spheres with a small pore size (SP-Cu2O). This work highlights the internal diffusion coefficient as a critical parameter for the fabrication of porous photocatalysts. [ABSTRACT FROM AUTHOR]

Efficient recovery of nanocatalysts, especially the graphene supported noblemetal catalysts, is a challenge. In this study, we report a simple one-step route to prepare the graphene supported Pt/Ni nanocatalysts with ideal superparamagnetic properties. We demonstrated that they had excellent catalytic activities in the catalytic reduction of aromatic nitro compounds and could be easily separated from the reaction mixtures by applying an external magnetic field. [ABSTRACT FROM AUTHOR]

Graphene sheets decorated with metal/metal oxide nanoparticles are gaining increasing attention. In this study, sulfhydrylated graphene was prepared by reducing the sulfonic acid groups on sulfonated graphene to thiol groups. We evaluated its ability to anchor different metal/metal oxide nanoparticles by simply mixing the sulfhydrylated graphene with the corresponding pre-prepared metal/metal oxide nanoparticles. The sulfhydrylated graphene and its nanohybrids were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). We demonstrate that the obtained sulfhydrylated graphene can act as a general platform to anchor different kinds of metal/metal oxide nanoparticles with different shapes, structures or properties through thiol–metal bonds. These novel hybrids will render graphene with additional interesting properties and potential applications. [ABSTRACT FROM AUTHOR]

We have developed a one-step method to prepare robust and smart gold nanoparticles (AuNPs) utilizing poly(N-isopropylacrylamide) (PNIPAAm)-grafted dextran (DexPNI) viaa “grafting-onto” approach. Using NaBH4as a reducing agent, and DexPNI as a nucleating and stabilizing agent, the AuNPs can be obtained at ambient temperature within a short reaction time. Different features of AuNPs, such as their morphologies, optical properties and temperature-responsive behaviours are found to be dependent on the dosage of the gold precursor. The DexPNI-stabilized AuNPs not only show excellent stability against heat, high salt concentration and extreme pH, but could also be readily redispersed after freeze-drying. UV measurements and kinetic analysis of the AuNPs-catalyzed reduction of 4-nitrophenol at different temperatures illuminated that the optical properties and catalytic activity of AuNPs are closely related to temperature. Compared with previously reported diffusion-regulated nanoreacters, our AuNPs provide a unique opportunity to control the reaction rate in an inverse temperature-responsive manner at 32–35 °C, and further switch off the reaction at temperatures higher than 35 °C. These temperature-responsive properties could be used to create a smart sensor and catalyst, acting as an optical temperature alarm and recloser when the reaction temperature accidentally goes beyond the limit value. By using monomers and colloidal precursors other than NIPAAm and HAuCl4, it will be straightforward to extend the present route to build a variety of robust and smart nanomaterials with unprecedented properties. [ABSTRACT FROM AUTHOR]

Objective: To observe the efficacy and adverse reactions of acupuncture and psychological treatment of attention deficit hyperactivity disorder (ADHD) in children. Methods: 120 diagnosed patients were randomly divided into two groups, one an integrated group, receiving acupuncture and psychological therapy, another a drug group, receiving methylphenidate hydrochloride therapy. Treatment was administered for 12 weeks. Connexion scale was determined before treatment and re-examined proceeding the 8th and 12th weeks during treatment. Results: Acupuncture and psychological therapy showed better hyperactivity index score than drug therapy alone. Conclusions: Satisfactory results could be eventually obtained by acupuncture plus psychotherapy, and which showed important medical significance in preventing and treating ADHD in children. [ABSTRACT FROM AUTHOR]

A Cu2O based multi-layered photocathode was fabricated with a layer-by-layer assembly method for enhanced photoelectrochemical (PEC) hydrogen evolution. Au was first electrodeposited on the fluorine-doped tin oxide glass to decrease the electrochemical impedance of the Cu2O photocathode. A layer of TiO2 was then coated to increase the light-to-electricity energy conversion efficiency and the chemical stability by forming a p–n junction with Cu2O. Exfoliated WS2 nanosheets obtained from lithium insertion were then coated as the electron acceptor to facilitate the hydrogen evolution. This photocathode is effective for PEC hydrogen evolution, and a photocurrent of −10 mA cm−2 can be obtained at −0.33 V versus RHE in a phosphorus buffer (pH = 6.0) under visible light (λ ≥ 420 nm, 100 mW cm−2) on the optimized photocathode. [ABSTRACT FROM AUTHOR]

Exfoliated molybdenum disulfide (MoS2) has unique 2H phase and semiconductor properties and potential applications across a wide range of fields. However, the chemically exfoliated MoS2 nanosheets from LixMoS2 have a 1T phase, and searching for a fast route to get processable 2H-MoS2 nanosheets and its nanocomposites is still an urgent task. This study reports on a simple, fast and efficient microwave strategy to achieve the 1T to 2H phase conversion of MoS2 and the successful preparation of processable 2H-MoS2 nanosheets and their nanocomposites. The method here may be easily changed to achieve the phase change of other exfoliated TMDs. [ABSTRACT FROM AUTHOR]

Attributed to its distinctive dahlia-flowerlike structure and already desirable size (usually <100 nm), carbon nanohorn assemblies (CNHs), a new member of the fullerene family, are a potential vehicle for intracellular delivery. This paper shows that isolated CNHs and nanoscale CNH agglomerates can be successfully isolated by a copolymer (Gum Arabic) through steric stabilization. In vitrostudy shows that the modified CNHs are nontoxic and may be used as a promising vehicle for intracellular delivery. [ABSTRACT FROM AUTHOR]

Hypothesis: Na 5 V 12 O 32 (NVO) is a potential cathode for aqueous zinc ion batteries (AZIBs). However, it suffers severe capacity decay due to the dissolution of the active material. The structural design may be an effective solution to the problem., Experiments: Herein, we construct a typical two-dimensional hierarchical structure of Na 5 V 12 O 32 @graphene (NVO@G) via a facile molten salt method., Findings: The capacity fading problem is solved by the in-situ conversion of NVO@G to a more stable hierarchical system during cycling. The in-situ formed zinc pyrovanadate (Zn 3 V 2 O 7 (OH) 2 ·2H 2 O, ZVO) nanosheets on the surface of graphene exhibits excellent zinc-ion storage stability. The presence of graphene induces the growth of NVO nanobelts to construct the typical two-dimensional hierarchical structure. Additionally, the in-situ conversion makes the formed ZVO nanosheets contact with graphene better. Benefitting from the hierarchical nanostructure and in-situ phase conversion, the NVO@G electrode shows excellent long-term stability (96.4% retention after 340 cycles at 0.3 A g -1 , 85.7% retention after 4400 cycles at 5 A g -1 ) and high zinc ion storage capacity (220 mAh g -1 at 0.3 A g -1 ), which is superior to those of most electrode materials previously reported., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Xiaobin Fan reports financial support was provided by the National Natural Science Funds of China. Xiaobin Fan reports financial support was provided by Innovative Research Group Project of the National Natural Science Foundation of China., (Copyright © 2022 Elsevier Inc. All rights reserved.)