In vitro Pharmacological Activity of Chromenes in Disk of Helianthus annuus

[Objectives]The anti-tumor,anti-bacterial,anti-acetylcholinesterase and anti-α-glucosidase activity in vitro of five chromenes isolated from Helianthus annuus disk was studied,in order to provide reference for the development and utilization of H.annuus disk resources.[Methods]The effect of different concentrations of chromenes on the survival rate of leukemia HL-60 cells,lung cancer A549 cells,liver cancer SMMC-7721 cells,breast cancer MCF-7 cells and colon cancer SW480 cells was detected by MTS method,and the IC50 was calculated.The inhibitory activity of chromenes against Escherichia coli,Staphylococcus aureus subsp.aureus,Salmonella enterica subsp.enterica,Pseudomonas aeruginosa and Candida albicans was detected by microdilution method.The DTNB substrate method was used to detect the inhibitory activity of chromenes on acetylcholine.The PNPG substrate method was used to detect the inhibitory activity of chromenes onα-glucosidase.[Results]The five chromenes had no obvious in vitro inhibitory activity on the five kinds of tumor cells,with IC50 greater than 40μM.The five chromenes had no obvious in vitro inhibitory activity against the four kinds of bacteria and C.albicans.The five chromenes had certain inhibitory activity on acetylcholinesterase,and among them,6-acetyl-2,2-dimethylchromene and 6-acetyl-7-hydroxy-2,3-dimethylchromene showed strong inhibitory activity on acetylcholinesterase,with IC50 of 28.253 and 16.945μM,respectively,both smaller than that(0.275μM)of the positive control tacrine(P<0.01).The five chromenes showed good inhibitory effect onα-glucosidase,and among them,7-hydroxy-6-hydroxyacetyl-2,2-dimethylchromene and 6-acetyl-7-hydroxy-2,3-dimethylchromene had stronger inhibitory activity,with IC50 of 20.240 and 21.052μM,respectively,significantly better than that(169.780μM)of the positive control acarbose(P<0.01).[Conclusions]The five chromenes in H.annuus disk have certain in vitro inhibitory activity against acetylcholinesterase andα-glucosidase and certain potential in fighting neurodegenerative diseases and diabetes.

Coordinated Capacitor Voltage Balancing Method for Cascaded H-bridge Inverter with Supercapacitor and DC-DC Stage

Cascaded H-bridge inverter(CHBI) with supercapacitors(SCs) and dc-dc stage shows significant promise for medium to high voltage energy storage applications. This paper investigates the voltage balance of capacitors within the CHBI, including both the dc-link capacitors and SCs. Balance control over the dc-link capacitor voltages is realized by the dcdc stage in each submodule(SM), while a hybrid modulation strategy(HMS) is implemented in the H-bridge to balance the SC voltages among the SMs. Meanwhile, the dc-link voltage fluctuations are analyzed under the HMS. A virtual voltage variable is introduced to coordinate the balancing of dc-link capacitor voltages and SC voltages. Compared to the balancing method that solely considers the SC voltages, the presented method reduces the dc-link voltage fluctuations without affecting the voltage balance of SCs. Finally, both simulation and experimental results verify the effectiveness of the presented method.

Upregulation of the glycine-rich protein-encoding gene GhGRPL enhances plant tolerance to abiotic and biotic stressors by promoting secondary cell wall development

Abiotic and biotic stressors adversely affect plant survival,biomass generation,and crop yields.As the global availability of arable land declines and the impacts of global warming intensify,such stressors may have increasingly pronounced effects on agricultural productivity.Currently,researchers face the overarching challenge of comprehensively enhancing plant resilience to abiotic and biotic stressors.The secondary cell wall plays a crucial role in bolstering the stress resistance of plants.To increase plant resistance to stress through genetic manipulation of the secondary cell wall,we cloned a cell wall protein designated glycine-rich protein-like(GhGRPL)from cotton fibers,and found that it is specifically expressed during the period of secondary cell wall biosynthesis.Notably,this protein differs from its Arabidopsis homolog,AtGRP,since its glycine-rich domain is deficient in glycine residues.GhGRPL is involved in secondary cell wall deposition.Upregulation of GhGRPL enhances lignin accumulation and,consequently,the thickness of the secondary cell walls,thereby increasing the plant’s resistance to abiotic stressors,such as drought and salinity,and biotic threats,including Verticillium dahliae infection.Conversely,interference with GhGRPL expression in cotton reduces lignin accumulation and compromises that resistance.Taken together,our findings elucidate the role of GhGRPL in regulating secondary cell wall development through its influence on lignin deposition,which,in turn,reinforces cell wall robustness and impermeability.These findings highlight the promising near-future prospect of adopting GhGRPL as a viable,effective approach for enhancing plant resilience to abiotic and biotic stress factors.

A Loss-model-based Efficiency Optimization Control Method for Induction Traction System of High-speed Train under Emergency Self-propelled Mode

Increasing attention has been paid to the efficiency improvement of the induction traction system of high-speed trains due to the high demand for energy saving. In emergency self-propelled mode, however, the dc-link voltage and the traction power of the motor are significantly reduced, resulting in decreased traction efficiency due to the low load and low speed operations. Aiming to tackle this problem, a novel efficiency improved control method is introduced to the emergency mode of high-speed train traction system in this paper. In the proposed method, a total loss model of induction motor considering the behaviors of both iron and copper loss is established. An improved iterative algorithm with decreased computational burden is then introduced, resulting in a fast solving of the optimal flux reference for loss minimization at each control period. In addition, considering the parameter variation problem due to the low load and low speed operations, a parameter estimation method is integrated to improve the controller's robustness. The effectiveness of the proposed method on efficiency improvement at low voltage and low load conditions is demonstrated by simulated and experimental results.

Coordinated Control of Second-order Harmonic Voltage and Current Fluctuations in Cascaded H-bridge Inverter with Supercapacitor and DC-DC Stage at Variable Output Frequencies

In the cascaded H-bridge inverter(CHBI)with supercapacitor and dc-dc stage,inherent second-order harmonic power flows through each submodule(SM),causing fluctuations in both the dc-link voltage and the dc-dc current.There exist limitations in handling these fluctuations at variable output frequencies when employing proportional-integral(PI)control to the dc-dc stage.This paper aims to coordinately control these second-order harmonic voltage and current fluctuations in the CHBI.The presented method configures a specific second-order harmonic voltage reference,equipped with a maximum voltage fluctuation constraint and a suitable phase,for the dc-dc stage.A PI-resonant controller is used to track the configured reference.This allows for regulating the second-order harmonic fluctuation in the average dc-link voltage among the SMs within a certain value.Importantly,the second-order harmonic fluctuation in the dc-dc current can also be reduced.Simulation and experimental results demonstrate the effectiveness of the presented method.

Analysis on Physical Mechanism of Sound Generation inside Cavities Based on Acoustic Analogy Method

Analysis of coupling aerodynamics and acoustics are performed to investigate the self-sustained oscillation and aerodynamic noise in two-dimensional flow past a cavity with length to depth ratio of 2 at subsonic speeds. The large eddy simulation (LES) equations and integral formulation of Ffowcs-Williams and Hawings (FW-H) are solved for the cavity with same conditions as experiments. The obtained density-field agrees well with Krishnamurty’s experimental schlieren photograph, which simulates flow-field distributions and the direction of sound wave radiation. The simulated self-sustained oscillation modes inside the cavity agree with Rossiter’s and Heller’s predicated results, which indicate frequency characteristics are obtained. Moreover, the results indicate that the feedback mechanism that new shedding-vortexes induced by propagation of sound wave created by the impingement of the shedding-vortexes in the shear-layer and rear cavity face leads to self-sustained oscillation and high noise inside the cavity. The peak acoustic pressure occurs in the first oscillation mode and the most of sound energy focuses on the low-frequency region.

Identification and Analysis of Chemical Components in Zhideke Granules by UPLC-Q-Orbitrap HRMS

[Objectives]To identify and analyze chemical components in Zhideke Granules by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry(UPLC-Q-Orbitrap HRMS).[Methods]Zhideke Granules were isolated on a Thermo Hypersil Gold C18 column(2.1 mm×100 mm,1.9μm).The mobile phase was 0.1%formic acid acetonitrile and 0.1%formic acid aqueous solution(containing 10 mmol ammonium acetate)with gradient elution.Chemical components in Zhideke Granules were rapidly isolated and identified by HRMS in the positive and negative ion mode with full scan data-dependent two stage threshold-triggered mass modes(Full MS/dd-MS2).[Results]The secondary fragment ion information of the target compound was selected and compared with the compound reported in the databases and related literatures for further confirmation.In total,30 chemical compounds were identified,including 12 flavonoids and glycosides,9 organic acids,3 nitrogen-containing compounds,and 6 other components.[Conclusions]In this study,the UPLC-Q-Orbitrap HRMS was used for the first time to analyze the chemical components in Zhideke Granules.It is intended to provide a reference for the quality evaluation and further study of pharmacodynamic materials of Zhideke Granules.

Advances in Inductively Coupled Power Transfer Technology for Rail Transit

Traditional power supply method for moving electric railway vehicles is based on contact type power collection technology.This sometimes cannot meet the requirements of modern rail transportation.A new wireless power transfer(WPT)technology can offer significant benefits in modern rail transportation particularly in some stringent environments.This paper reviews the status and the development of rail transit power supply technology,and introduces a new challenging technology--inductive power transfer(IPT)technology for rail transit.Tesla established the underpinning of IPT technology and creatively and significantly demonstrated power transfer by using highly resonant tuned coils long time ago.However,only in recent years the IPT technology has been significantly improved including the transfer air-gap length,transfer efficiency,coupling factor,power transfer capability and so on.This is mainly due to innovative semiconductor switches,higher control frequency,better coil designs and high performance material,new track and vehicle construction techniques.Recent advances in IPT for rail transit and major milestones of the developments are summarized in this paper.Some important technical issues such as coupling coil structures,power supply schemes,segmentation switching techniques for long-distance power supply,and bidirectional IPT systems for braking energy feedback are discussed.

Characteristics Investigation of Single-Sided Ironless PMLSM Based on Halbach Array for Medium-Speed Maglev Train

This paper investigates characteristics of ironless permanent magnet linear synchronous motor(PMLSM)based on Halbach array used for medium-speed(200km/h)maglev train.Long primary ironless coil is laid in the middle of track and the Halbach permanent magnet array is attached to the bottom of each bogie as a source of traction,U-shape electromagnets at the both sides of the train for levitation.Two dimensional analytical model of single-sided ironless PMLSM based on Halbach array is established,using linear overlay method,the no-load air gap magnetic field is calculated firstly,winding current density distribution is obtained for calculating the characteristics of thrust and normal force against power angle,including force characteristics with equal and unequal pole pitch,the influence of steel sleeper,etc.Besides,the mathematical model for this type motor is built by 3D finite element method,the traction characteristics of medium-speed maglev under maximum speed 200km/h are calculated.The characteristics of this type motor are satisfactory owing to there is no detent force in the motor and thrust force reach maximum meanwhile normal force can be eliminated.Calculation method is verified by comparing finite element results,experimental result on a 200kW type motor further validates the accuracy of calculation and some important conclusions are obtained.

Fiber-specific increase of carotenoid content promotes cotton fiber elongation by increasing abscisic acid and ethylene biosynthesis

Cotton fiber is a raw material for the global textile industry and fiber quality is essential to its industrial application.Carotenoids are plant secondary metabolites that may serve as dietary components,regulate light harvesting,and scavenge reactive oxygen species.Although carotenoids accumulate predominantly in rapidly elongating cotton fibers,their roles in cotton fiber development remain poorly understood.In this study,a fiber-specific promoter proSCFP was applied to drive the expression of GhOR1Del,a positive regulator of carotenoid accumulation,to upregulate the carotenoid level in cotton fiber in planta.Fiber length,strength,and fineness were increased in proSCFP:GhOR1Del transgenic cotton and abscisic acid(ABA)and ethylene contents were increased in elongating fibers.The ABA downstream regulator GhbZIP27a stimulated the expression of the ethylene synthase gene GhACO3 by binding to its promoter,suggesting that ABA promoted fiber elongation by increasing ethylene production.These findings suggest the involvement of carotenoids and ABA signaling in promoting cotton fiber elongation and provide a strategy for improving cotton fiber quality.

GC-MS Analysis and Antibacterial Activity Study of Volatile Oil from 11 Kinds of Aurantii Fructus Immaturus Processed Products

[Objectives]To study the volatile components and antibacterial effects of 11 kinds of Aurantii Fructus Immaturus processed products.[Methods]11 kinds of Aurantii Fructus Immaturus processed products were obtained according to the traditional processing method,the volatile oil was extracted by steam distillation,and the composition of volatile oil in the 11 kinds of processed products was analyzed by gas chromatography-mass spectrometry(GC-MS).the relative percentage content of each component in these 11 kinds of processed products was determined using the peak area normalization.The drug sensitivity activity of the volatile oil of these 11 kinds of processed products was tested using the K-B paper diffusion method and the minimum inhibition volume fraction of volatile oil of these 11 kinds of processed products was tested using the microdilution method.[Results]The highest yield of volatile oil of 11 kinds of these processed products was baking(5.193%),and the lowest was stir-bake to scorch(1.998%).A total of 36 chemical components were identified from the volatile oils of these 11 kinds of processed products.The components with the most volatile oil were stir-bake to scorch(24 kinds),and the components with the least volatile oil were the method of processing with rice-washed water(15 kinds).They contain 8 kinds of common chemical components,such as limonene,linalool,myrcene,α-pinene.The highest content of limonene came from processing with honey(60.93%),the lowest came from processing with rice-washed water(55.25%);the highest content of linalool came from processing with rice-washed water(7.139%),the lowest came from processing with honey(5.436%);the highest content of myrcene came from processing with honey(1.899%),the lowest came from stir-bake to scorch(1.632%);the highest content ofα-pinene came from raw Aurantii Fructus Immaturus(2.355%),and the lowest came from stir-bake to scorch(1.618%).The volatile oil of these 11 kinds of Aurantii Fructus Immaturus processed products has good antibacterial effect on Escherichia coli and Staphylococcus aureus.[Conclusions]The oil yields of volatile oils of 11 kinds of Aurantii Fructus Immaturus processed products are different,the content of limonene is significantly different,and the changes of other chemical components and their contents are not significantly different.The volatile oil of 11 kinds of Aurantii Fructus Immaturus processed products has certain antibacterial effect.

Research Progress of Natural Active Components against Damage from UV Radiation

The sun's ultraviolet(UV)rays are extremely harmful to the skin.In addition to causing sunburn and aging,excessive UV radiation can also lead to benign or malignant skin tumors.This paper reviews the researches on natural active components against damage from UV radiation,and summarizes the types of compounds,research methods and mechanisms of action.Moreover,the main problems in current research are put forward,and the possible development direction in the future is discussed.

A Novel Voltage Balancing Method of Modular Multilevel Converters

In this paper, a novel voltage balancing method of modular multilevel converters (MMCs) is proposed. This method divides the voltages of sub-module capacitors in each arm into several groups and the voltage balancing is based on these groups. The proposed method can save sorting time greatly compared with the conventional method. Simulation results on a MMC based three-phase inverter show validity of the proposed method.

NODULATION TRIO in Medicago truncatula:Unveiling the redundant roles of MtLYK2,MtLYK3,and MtLYK2bis

The legume–rhizobial symbiosis is a distinctive model in plant–microbe interactions.Despite being foreign invaders,rhizobia are acknowledged as“friends”by compatible host plants,leading to mutualistic endosymbiosis(Cao et al.,2017).

Message from Editors

ELECTRIFIED transportation in automotive,railway,aviation and navigation has received more and more attention in recent years.Innovations in energy efficiency,speed and performance of all kinds of transportation vehicles are hot topics both in academia and industry.The corresponding researches relate to the design and control of electrical machines,power converters and energy storage systems.

A Novel Pulse Density Modulation with Semi-bridgeless Active Rectifier in Inductive Power Transfer System for Rail Vehicle

In this paper,a novel pulse density modulation(PDM)with semi-bridgeless active rectifier(S-BAR)in inductive power transfer(IPT)system for rail vehicle is proposed.It is to reduce switching losses of the active rectifier in pickups.In the control method,the insulated-gate bipolar transistors(IGBTs)in the S-BAR are controlled by synchronous PDM signals,so that zero-voltage switching(ZVS)and zero-current switching(ZCS)can be achieved in the whole output power range.The output power is regulated by changing the pulse density(PD)of the S-BAR since the it is almost linear proportional with the PD in high quality factor of pickup side.The communication device between the primary side and pickup side is not necessary anymore.The detailed theoretical analyses of the PDM method are provided,and its advantages are shown in a 7.5kW IPT prototype for rail vehicle.The experimental results are presented to verify the analysis and demonstrate the performance.The overall efficiency of the system by PDM control is 74.2%which is improved by 4%compared with phase shift(PS)control at light load.

Observation of topological rainbow in non-Hermitian systems

Topological photonic states have promising applications in slow light,photon sorting,and optical buffering.However,realizing such states in non-Hermitian systems has been challenging due to their complexity and elusive properties.In this work,we have experimentally realized a topological rainbow in non-Hermitian photonic crystals by controlling loss in the microwave frequency range for what we believe is the first time.We reveal that the lossy photonic crystal provides a reliable platform for the study of non-Hermitian photonics,and loss is also taken as a degree of freedom to modulate topological states,both theoretically and experimentally.This work opens a way for the construction of a nonHermitian photonic crystal platform,will greatly promote the development of topological photonic devices,and will lay a foundation for the real-world applications.

In-situ Fluid Phase Variation along the Thermal Maturation Gradient in Shale Petroleum Systems and Its Impact on Well Production Performance

In-situ fluid phase behavior is important in determining hydrocarbon contents and the multiphase flow through shale reservoirs.The gas-to-oil ratio(GOR) has been recognized as a critical indicator of fluid types.However,little is known about the impact of fluid phase variation across the thermal maturity on shale oil/gas production(e.g.,estimated ultimate recovery,EUR).According to the specific gravity ratio of oil/gas,the producing GOR was converted and normalized into a mass fraction of gas in total hydrocarbons(MGOR) to compare North American shale oil/gas plays with Chinese shale oil and hybrid gas-condensate plays.A correlation between MGOR,the fluid phases,and production data was established to identify five phase stages of flow.MGORvaries systematically with the different production zones,which shows promise in rapidly indicating the well production performance and high production stages of shale oil/gas plays.The hybrid shale gas condensate index,Tmax,and total gas contents were integrated to present the fluid types and maturity of shale gas-condensates,which indicates fluid phase and production variation across thermal evolution.The results offer a unique perspective on the shale oil reservoir producibility based on the impact of GOR on fluid phases and EUR from the dominant global oil/gas plays.

Study on driver’s braking intention identification based on functional near-infrared spectroscopy

Purpose–Cooperative driving refers to a notion that intelligent system sharing controlling with human driver and completing driving task together.One of the key technologies is that the intelligent system can identify the driver’s driving intention in real time to implement consistent driving decisions.The purpose of this study is to establish a driver intention prediction model.Design/methodology/approach–The authors used the NIRx device to measure the cerebral cortex activities for identifying the driver’s braking intention.The experiment was carried out in a virtual reality environment.During the experiment,the driving simulator recorded the driving data and the functional near-infrared spectroscopy(fNIRS)device recorded the changes in hemoglobin concentration in the cerebral cortex.After the experiment,the driver’s braking intention identification model was established through the principal component analysis and back propagation neural network.Findings–The research results showed that the accuracy of the model established in this paper was 80.39 per cent.And,the model could identify the driver’s braking intent prior to his braking operation.Research limitations/implications–The limitation of this study was that the experimental environment was ideal and did not consider the surrounding traffic.At the same time,other actions of the driver were not taken into account when establishing the braking intention recognition model.Besides,the verification results obtained in this paper could only reflect the results of a few drivers’identification of braking intention.Practical implications–This study can be used as a reference for future research on driving intention through fNIRS,and it also has a positive effect on the research of brain-controlled driving.At the same time,it has developed new frontiers for intention recognition of cooperative driving.Social implications–This study explores new directions for future brain-controlled driving and wheelchairs.Originality/value–The driver’s driving intention was predicted through the fNIRS device for the first time.