Development of arc root attachment in the nozzle of 1 kW N2 and H2-N2 arcjet thrusters

Arc root behavior affects the energy transfer and nozzle erosion in an arcjet thruster. To investigate the development of arc root attachment in 1 kW class N2 and H2-N2 arcjet thrusters from the time of ignition to the stably working condition, a kinetic series of end-on view images of the nozzle obtained by a high-speed video camera was analyzed. The addition of hydrogen leads to higher arc voltage levels and the determining factor for the mode of arc root attachment was found to be the nozzle temperature. At lower nozzle temperatures, constricted type attachment with unstable motions of the arc root was observed, while a fully diffused and stable arc root was observed at elevated nozzle temperatures.

从电鳐电器官中提取N2-AchR纯品建立EAMG模型

下载PDF阅读器目的 从厦门海域单鳍电鳐的电器官中提取烟碱型乙酰胆碱受体(N2-AchR)纯品,用纯化的N2-AchR 免疫Lewis大鼠,建立实验性自身免疫性重症肌无力(EAMG)动物模型.方法 参照文献报道[1-2]从电鳐电器官提取N2-AchR纯品,并采用SDS凝胶电泳蛋白定性鉴定及考马斯亮兰定蛋白含量;以纯提的蛋白主动免疫Lewis大鼠,共免疫3次,于末次免疫后第3日进行EAMG大鼠临床评分及攀网时间、肌电图、血清Nz-AchRab含量、突触后膜上N2-AehR数目的 检测.结果 纯化的蛋白含量为1.097m咖l(标准品为1mg,ml);EAMG模型组与佐剂组比较,攀网时间明显降低(p<0.01);临床评分及肌电图第五个反应幅度衰减百分率显著升高(P<0.01);血清N2-AchRab含量明显增加(P<0.01);突触后膜上Nr-AchR数目显著减少(P<0.01).结论 从单鳍电鳐电器官纯提的Nz-AchR蛋白成功诱导EAMG模型,为进一步研究重症肌无力创造了良好条件.

电子级气体N2、H2、O2、Ar、He、HCl、CO2、NH3 28种杂质分析技术及质量监控

于G批量导入至Hzhangdi

RAMAN-SCATTERING BY LO PHONONS IN (GAAS)N1/(ALAS)N2 ULTRATHIN-LAYER SUPERLATTICES

Raman spectra of (GaAs)n1/(AlAs)n2 ultrathin-layer superlattices were measured at room temperature and under off-resonance conditions. The experimental results show that there are two effects in ultrathin-layer superlattices: the confinement effect of LO phonons and the alloy effect. It is found that the relative intensity of the disorder-activated TO mode can give a measure of the alloy effect. The Raman spectra of one-monolayer superlattices measured in various scattering configurations are very similar to those of the Al0.5Ga0.5As alloy, and thus the alloy effect is prominent. However, in the case of monolayer number n greater-than-or-equal-to 4, the confined effect is prominent, while the alloy effect is only shown as an interface effect.

Effect of Nozzle Temperature on the Performance of a 1 kW H2-N2 Arcjet Thruster

A 1 kW-class arcjet thruster was ¯red in a vacuum chamber at a pressure of 18 Pa. A gas mixture of H2 : N2 = 2.8 : 1.5 in volume at a total °ow rate of 4.3 slm was used as the propellant with an input power ¯xed at 860 W. The time-dependent thrust, nozzle temperature and inlet pressure of the propellant were measured simultaneously. Results showed that with the increase in nozzle temperature the thrust decreased and various losses increased. The physical mechanisms involved in these effects are discussed.

Theoretical calculation of photoionization cross sections of B-like ions: N2+, O3+ and F4+

There can be found some notable discrepancies with regard to the resonance structures when R-matrix calculations from the Opacity Project and other sources are compared with recent absolute experimental measurements of Bizau et al [Astron. Astrophts. 439 387 (2005)] for B-like ions N2+, O3+ and F4+. We performed close-coupling calculations based on the R-matrix formalism for the photoionizations of ions mentioned above both for the ground states and first excited states in the near threshold regions. The present results are compared with experimental ones given by Bizau et al and earlier theoretical ones. Excellent agreement is obtained between our theoretical results and the experimental photoionization cross sections. The present calculations show a significant improvement over the previous theoretical results.

A method for quantitative analysis of nitrogen oxides and N2 by means of mass spectrometry with the assistance of a catalytic technique for the reduction of NO with CO or hydrocarbons

Mass spectrometry is not able to differentiate NOx and N2 from other interferences (e.g. CO and C2H4) in the deNOx reactions. In the present study, a quantitative method for analysis of NOx and N2 simultaneously in these reactions with an assisted converter operated at higher temperature under O2-rich condition, which eliminates the interferences, is developed. The NOx conversion from this method is comparable to the one from an Automotive Emission Analyser equipped with NOx electrochemical sensor. Two types of deNOx reactions are tested in terms of selectivity of N2 production. The application of this method is discussed.