Development of a compact torus injection system for the Keda Torus eXperiment

A compact torus injection system,KTX-CTI,has been developed for the planned injection experiments on the Keda Torus e Xperiment(KTX)reversed field pinch(RFP)device to investigate the physics and engineering issues associated with interaction between a compact torus(CT)and RFP.The key interests include fueling directly into the reactor center,confinement improvement,and the injection of momentum and helicity into the RFP discharges.The CT velocity and mass have been measured using a multichannel optical fiber interferometer,and for the first time the time evolution of the CT density profile during CT propagation is obtained.The effects of discharge parameters on the number of injected particles,CT velocity and CT density have been characterized:the maximum hydrogen CT plasma mass,m,CTis 50μg,corresponding to 30%of the mass in a typical KTX plasma;the CT velocity exceeds 120 km s-1.It is observed for the first time that multiple CTs can be produced and emitted during a very short period(<100μs)in one discharge,which is significant for the future study of repetitive CT injection,even with an ultra-high frequency.

Sensitivity of two drug-resistant bacteria to low-temperature air plasma in catheterassociated urinary tract infections under different environments

The high incidence of catheter-associated urinary tract infections,which are dominated by drugresistant bacteria,has attracted an increasing number of researchers interested in solving this public health problem.The purpose of this study was to explore the killing effect of lowtemperature air plasma(LTAP)on extended-spectrum beta-lactamase-producing Escherichia coli and high level gentamycin resistance enterococci under two simulated environments in vitro.The results showed that the survival rate of these two kinds of bacteria decreased to less than20%after being treated by LTAP in different environments for 5 min.A comparison of the LTAP treatments showed that the killing efficacy of the two kinds of bacteria in the early stage(0-1 min)was up to 50%.Moreover,the results of transmission electron microscopy,reactive nitrogen species measurement,and a temperature test indicated that the bactericidal effect of the LTAP treatment on the two kinds of bacteria worked through the destruction of the ribosome and other organelles inside the bacteria,rather than the thermal effect,to achieve sterilization.

Construction of an Hα diagnostic system and its application to determine neutral hydrogen densities on the Keda Torus eXperiment

A 10-channel Hα diagnostic system has been designed with the rapid response rate of 300 kHz, spatial resolution of about 40 mm, and overlap between adjacent channels of about 3%, and it has been implemented successfully on Keda Torus eXperiment(KTX), a newly constructed, reversed field pinch(RFP) experimental device at the University of Science and Technology of China(USTC). This diagnostic system is a very important tool for the initial KTX operations. It is compact,with an aperture slit replacing the traditional optical lens system. A flexural interference filter is designed to prevent the center wavelength from shifting too much as the increase of angle from vertical incidence. To eliminate the stray light,the interior of the system is covered with the black aluminum foil having a very high absorptivity. Using the Hαemission data, together with the profiles of electron temperature and density obtained from the Langmuir probe, the neutral density profiles have been calculated for KTX plasmas. The rapid response rate and good spatial resolution of this Hαdiagnostic system will be beneficial for many studies in RFP plasma physics.

Fast radial scanning probe system on KTX

A fast radial scanning probe system was constructed for the Keda Torus eXperiment(KTX)to measure the profiles of boundary plasma parameters such as floating potential,electron density,temperature,transport fluxes,etc.The scanning probe system is driven by slow and fast motion mechanisms,corresponding to the stand-by movement of a stepping motor and the fast scanning movement of a high-torque servo-motor,respectively.In fast scanning,the scanner drives the probe radially up to 20 cm at a maximum velocity of 4.0 m s-1.A noncontact magnetic grating ruler with a high spatial resolution of 5μm is used for the displacement measurement.New scanning probe can reach the center of plasmas rapidly.The comparison of plasma floating potential profiles obtained by a fixed radial rake probe and the single scanning probe suggests that the high-speed scanning probe system is reliable for measuring edge plasma parameter profiles on the KTX device.

Difference analysis in terahertz wave propagation in thermochemical nonequilibrium plasma sheath under different hypersonic vehicle shapes

Research on terahertz communication under different vehicles has important guiding significance for the design of future hypersonic vehicle and Radio Frequency(RF)blackout.In this paper,a joint simulation model of plasma flow under thermochemical nonequilibrium state and terahertz transmission is developed to investigate the differences in terahertz wave transmission characteristics under different vehicle shapes and the related mechanisms.By comparing the plasma sheath characteristics and terahertz transmission among HIFIRE-5b(Hypersonic International Flight Research Experimentation-5b),RAM C(Radio Attenuation Measurement C)and ARD(Atmospheric Reentry Demonstrator)vehicles,it is found that the sheath thickness and electron density of ARD vehicles is significantly larger than that of HIFIRE-5b and RAM C vehicles,resulting in greater terahertz wave attenuation.Collision absorption plays a major role in the terahertz attenuation of vehicles,and the contribution of reflection effects is only observed in the ARD vehicle due to its larger plasma sheath thickness and spatial structure variation.Based on the above comparison results,a shape design scheme of reducing the vehicle head and tail for mitigating RF blackout is proposed,and the scheme is proved by further analyzing the effects of different vehicle heads and tails on the terahertz communication.With the decrease of the head radius and tail width of hypersonic vehicle,the wave attenuation at the same terahertz frequency decreases,and the contribution of reflection effect to wave attenuation gradually disappears.Therefore,the shape design scheme of reducing the vehicle head and tail can effectively alleviate the RF blackout problem,which provides an important reference value for future hypersonic vehicle design.

Reducing the carbon emissions from Qianxi tomato fruits preservation by cold atmospheric plasma

China has pledged to reach its dual-carbon goals(i.e.,carbon peak and carbon neutrality)at the end of 2060.To reduce carbon emission in food preservation industry,the preservation effects of cold atmospheric plasma intermittent treatment(1 min/6 h each day,PL4)combined with 15℃ and 4℃ only on Qianxi tomato fruits during 7 d storage were investigated.Results indicated that the firmness,L*,sensory taste,glutathione(GSH)content,mineral(Fe,P,K)content,polyphenol oxidase activity of PL4 tomatoes were significantly increased than that in Control during earlier period storage,with worse weight loss,titratable acid,a*,b*,lycopene content,·OH radical scavenging capacity and same moisture content,total soluble solids,polysaccharide content,total phenolics content,total flavonoid content,ascorbic acid content,1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity,pectin methylesterase activity.Moreover,the power and R134a consumption of PL4 were highly decreased by around 56.4 kW·h and 0.3 g respectively during whole storage as compared to Control,and reduced more than 99.8%carbon emission based on equipment using stage.All in all,this study illustrated that PL4 treatment can be applied as an ecofriendly,low carbon and sustainable preservation strategy for short-term storage of fruits under 4℃ or higher temperature.

Nanostructured Conductive Polypyrrole for Antibacterial Components in Flexible Wearable Devices

The power generated by flexible wearable devices(FWDs)is normally insufficient to eradicate bacteria,and many conventional antibacterial strategies are also not suitable for flexible and wearable applications because of the strict mechanical and electrical requirements.Here,polypyrrole(PPy),a conductive polymer with a high mass density,is used to form a nanostructured surface on FWDs for antibacterial purposes.The conductive films with PPy nanorods(PNRs)are found to sterilize 98.2±1.6%of Staphylococcus aureus and 99.6±0.2%of Escherichia coli upon mild electrification(1 V).Bacteria killing stems from membrane stress produced by the PNRs and membrane depolarization caused by electrical neutralization.Additionally,the PNR films exhibit excellent biosafety and electrical stability.The results represent pioneering work in fabricating antibacterial components for FWDs by comprehensively taking into consideration the required conductivity,mechanical properties,and biosafety.

Facilely Fabricating Superhydrophobic Resin-based Coatings with Lower Water Freezing Temperature and Ice Adhesion for Anti-icing Application

This work is focused on the development of a facile strategy to fabricate superhydrophobic coatings,which are characterized with lower water freezing temperature and lower ice adhesion.First,a kind o f polyacrylic acid(PAA)based resin material is synthesized as the coating-matrix.Then the functionally-modified S i02 nanoparticles are added to regulate the surface morphology for obtaining the ideal superhydrophobicity.The as-synthesized resin coatings possess strong bonding strength with metal substrate,and the surface hierarchical morphologies(10 wt% SiO2 nanoparticles)induce the robust superhydrophobicity with a high water contact angle of 152°.Also,the superhydrophobic coatings are endowed with high icephobicity,and the freezing temperature of reference water droplet is reduced to-20.33℃ comparing with that(-13.83℃)on the coatings without additive nanoparticles.Furthermore,the ice adhesion strength on the superhydrophobic coatings is only 250 kPa,exhibiting the great ability of ice repellence.

Facilely fabricating superhydrophobic coated-mesh materials for effective oil-water separation:Effect of mesh size towards various organic liquids

Effective oil-water separation is a continuous pursuit,not only for scientific research but also for engineering application,because oil spills are causing the great pollution in the current ocean environment.Here we reported a superhydrophobic coated-mesh,where the coatings were composed of fluorinated silica(F-SiO2)and polydimethylsiloxane(PDMS),demonstrating the excellent oil-water separation ability towards various organic liquids.The introduction of F-SiO2 could well induce a certain extent of microscopic roughness,leading to the remarkable water repellence.The resultant coatings exhibited the robust superhydrophobicity with the water contact angle reaching 155.9°±1.0°.On this basis,the pore size of polyethylene terephthalate(PET)mesh materials(as a substrate)was mainly discussed with the great oil-water separation efficiency of as high as 98%towards various organic liquids.Also,under the assistance of physical model,it was confirmed that there was a mechanical relation between pore size and organic liquids,where the main connotation was the matching issue of surface tension of organic liquids with the geometrical mechanic(induced by the pore size of the superhydrophobic coated-mesh).This work on the size effect of superhydrophobic coated-mesh materials on various organic liquids is beneficial to the design and manu facture of ideal oil-water separation materials.

Green Synthesis of Mechanical Robust Superhydrophobic CNT@PU Coatings with High Flexibility for Extensive Applications

Superhydrophobic coatings with high flexibility and mechanical durability can well address many practical application problems.To this end,we proposed and fabricated a kind of bio-based superhydrophobic(multi-walled carbon nanotubes)CNT@PU(polyurethane)coatings.It was demonstrated that the CNT@PU coatings with 64%soft segment content possessed the preferable bonding strength(5B)with metal substrates.The multi-walled carbon nanotubes,as additive materials,were used to construct the microscopic structures of the coating surfaces,which made polyurethane surface superhydrophobic(water contact angle being 156.9°,and water sliding angle being 4.3°).Furthermore,the high bonding strength between CNT and coating matrix led to robust mechanical durability of supertiydrophobic CNT@PU coatings,and the coatings remained superhydrophobicity after 10 cycles of abrasion under 100 g load pressure.Also,the superhydrophobic coatings could well resist 5 cycles of tape-peeling action,and presented outstanding flexibility.The supernydrophobic CNT@PU coatings with high flexibility and mechanical durability could be applied to various substrates suggesting their big potential in future real-world application.

Cold air plasma:A potential strategy for inducing apoptosis of rheumatoid arthritis fibroblast‐like synoviocytes

Rheumatoid arthritis(RA)is an autoimmune disease of the joints characterised by synovial hyperplasia and chronic inflammation.Rheumatoid arthritis fibroblast‐like synoviocytes(RA‐FLS)cells are the dominant cell type in the hyperplastic synovial membrane,which play a key role in the pathogenesis of RA.They can invade cartilage,cause inflammation,destroy joints,and show tumour‐like anti‐apoptosis characteristics.Thus,the purpose of this study is to investigate the effect of cold air plasma(CAP)on RA‐FLS cells.The results showed that CAP treatment for 120 s could significantly reduce the viability of RA‐FLS cells,increase the content of intracellular reactive ox-ygen species(ROS),and significantly down‐regulate the ratio of apoptosis‐related protein Bcl‐2 to Bax.In this study,a novel approach of inducing apoptosis in RA‐FLS cells using CAP was proposed,which may provide a new choice for joint tar-geting therapy of RA.