PIC simulation of plasma properties in the discharge channel of a pulsed plasma thruster with flared electrodes

Plasma in the discharge channel of a pulsed plasma thruster(PPT) with flared electrodes is simulated by a self-developed two-dimensional code. The fully particle-in-cell method with Monte Carlo collision is employed to model the particle movement and collisions and investigate the plasma properties and acceleration process. Temporal and spatial variations of the electron density distribution and the ion velocity between electrodes are calculated and analyzed in detail.The computational results of the electron number density, which is in the order of 1023 m-3,show good agreements with experimental results of a PPT named ADD SIMP-LEX. The ion velocity distributions along the center line of the channel lead to a comprehensive understanding of ions accelerated by electromagnetic field. The electron distributions of PPT with discharge voltages varying from 1300 to 2000 V are compared. The diffusion of electrons presents strong dependency on discharge voltage and implies higher degree of ionization for higher voltage.

Investigation of the self-induced magnetic field characteristics in a pulsed plasma thruster with flared electrodes

The self-induced magnetic field in a pulsed plasma thruster(PPT)with flared electrodes is investigated for a better understanding of the working process and the structural design of the thruster.A two-dimensional model of the magnetic field is built and is validated by comparing the simulated results with the experimental results in literature.The magnetic flux density in the discharge channel during the working process is presented and analyzed regarding the electrode structures.The calculated magnetic field flux density decreases from 0.8 T at the upstream to 0.1 T and below at the downstream in the discharge channel(68 J).The peak of the magnetic flux density over time lags behind the current peak,which provides evidence for the existence of a moving plasma sheet in the discharge process.The magnetic field induced by the current in the extra bending part of the anode enhances the Lorentz force,which acts on the charged particles near the propellant.Finally,the geometric study indicates that the electromagnetic impulse bit does not monotonically increase with the flared angle of the electrodes.Instead,it reaches a maximum at a certain flared angle,which could provide significant suggestions for structural optimization.

Osteoarthritis versus psoriasis arthritis: Physiopathology, cellular signaling, and therapeutic strategies

Osteoarthritis and psoriasis arthritis are two degenerative forms of arthritis that share similar yet also different manifestations at the histological,cellular,and clinical levels.Rheumatologists have marked them as two entirely distinct arthropathies.Given recent dis-coveries in disease initiation and progression,potential mechanisms,cellular signaling path-ways,and ongoing clinical therapeutics,there are now more opportunities for discovering osteoarthritis drugs.This review summarized the osteoarthritis and psoriasis arthritis signaling pathways,crosstalk between BMP,WNT,TGF-β,VEGF,TLR,and FGF signaling pathways,bio-markers,and anatomical pathologies.Through bench research,we demonstrated that regen-erative medicine is a promising alternative for treating osteoarthritis by highlighting significant scientific discoveries on entheses,multiple signaling blockers,and novel molecules such as immunoglobulin new antigen receptors targeted for potential drug evaluation.Furthermore,we offered valuable therapeutic approaches with a multidisciplinary strategy to treat patients with osteoarthritis or psoriasis arthritis in the coming future in the clinic.

心脏出生缺陷胎儿产前诊断与分级咨询后的随访研究

目的通过对心脏出生缺陷(CBD)胎儿进行准确产前诊断、分级咨询后, 结合胎儿CBD分级对其临床随访结果进行研究, 为产前-产后一体化治疗提供数据基础。方法收集2018年1月至2020年12月广东省人民医院产前诊断结果为CBD的胎儿1 971例的临床资料。按照预后、出生后可能的手术时机将胎儿CBD分成Ⅰ~Ⅵ级, 并提出分级标准及包含的常见疾病种类。随访孕妇经产前分级咨询后胎儿的结局, 计算引产率、活产率、产前产后超声诊断符合率等指标。统计各级的疾病种类构成比、不同分级胎儿的预后及一体化治疗的结局。结果本院产前诊断为CBD的胎儿1 971例, 占行胎儿心脏超声检查总人数的16.2%(1 971/12 188), 排除因其他原因引产者30例, 最终纳入本研究1 941例, 其中Ⅰ级196例(10.1%)、Ⅱ级433例(22.3%)、Ⅲ级615例(31.7%)、Ⅳ级261例(13.4%)、Ⅴ级388例(20.0%)、Ⅵ级48例(2.5%), Ⅱ级和Ⅲ级(手术时间为出生后1年内)共占54.0%(1 048/1 941)。部分病种的分布在不同分级中具有明显的占比优势, 具有代表性。1 747例成功随访的孕妇中因胎儿CBD终止妊娠者736例, 引产率为42.1%(736/1 747);死胎1例;活产1 010例, 活产率为57.8%(1 010/1 747), 无死产。活产儿中975例(96.5%, 975/1 010)产前与产后诊断一致, 漏诊3例, 误诊32例;Ⅰ~Ⅲ级(主要为严重、复杂先天性心脏病)活产儿产前与产后诊断符合率为98.5%(383/389)。258例胎儿已在出生后进行手术治疗, Ⅱ级和Ⅲ级的手术比例比较, 差异有统计学意义(χ2=47.3, P<0.001)。随着分级水平的升高, Ⅰ~Ⅴ级(除Ⅵ级外)的活产率逐渐上升, 引产率逐渐下降。经比较, Ⅰ~Ⅴ级之间引产率和活产率的差异均有统计学意义(χ2=623.6, P<0.001)。结论产前诊断和产前分级咨询是CBD胎儿产前-产后一体化治疗模式中的重要环节;根据胎儿CBD分级可以细化胎儿出生后的治疗策略, 指导分娩决策, 并可作为产前诊断及产前咨询开展是否规范合理的评价标准。

CRISPR/Cas9-based functional analysis of yellow gene in the diamondback moth,Plutella xylostella

The diamondback moth,Plutella xylostella(L.),is an economically important pest of cruciferous crops worldwide.This pest is notorious for rapid evolution of the resistance to diferent classes of insecticides,making it increasingly dificult to control.Genetics-based control approaches,through manipulation of target genes,have been reported as promising supplements or alternatives to traditional methods of pest management.Here we identified a gene of pigmentation(yellow)in P.xylostella,Pxyellow,which encodes 1674 bp complementary DNA sequence with four exons and three introns.Using the clustered regularly interspersed palindromic repeats(CRISPR)CRISPR-associated protein 9 system,we knocked out Pxyellow,targeting two sites in Exon III,to generate 272 chimeric mutants(57%of the CRISPR-treated individuals)with color-changed phenotypes of the Ist to 3rd instar larvae,pupae,and adults,indicating that Pxyellow plays an essential role in the body pigmentation of P xlostella.Fitness analysis revealed no significant difference in the oviposition of adults,the hatchability of eggs,and the weight of pupac between homozygous mutants and wildtypes,suggesting that Pxyellow is not directly involved in regulation of growth,development,or reproduction.This work advances our understanding of the genetic and insect science molecular basis for body pigmentation of P xylostella,and opens a wide avenue for development of the genctcally based pest control techniques using Pxyellow as a screening marker.

Investigation of temperature-dependent small-signal performances of TB SOI MOSFETs

This paper investigated the temperature dependence of the cryogenic small-signal ac performances of multi-finger partially depleted（PD） silicon-on-insulator（SOI） metal oxide semiconductor field effect transistors（MOSFETs）,with T-gate body contact（TB） structure.The measurement results show that the cut-off frequency increases from 78 GHz at 300 K to 120 GHz at 77 K and the maximum oscillation frequency increases from 54 GHz at 300 K to 80 GHz at 77 K,and these are mainly due to the effect of negative temperature dependence of threshold voltage and transconductance.By using a simple equivalent circuit model,the temperature-dependent small-signal parameters are discussed in detail.The understanding of cryogenic small-signal performance is beneficial to develop the PD SOI MOSFETs integrated circuits for ultra-low temperature applications.