Thermal Decomposition of 1,2-Dichloroethane in a Single-Pulse Shock Tube

在单脉冲激波管上,研究了1,2-二氯乙烷的热裂解.实验的激波条件为:温度区间1020 K＜T＜1190 K, 压力: P=0.12 MPa,实验时间τ=0.5 ms;实验气体为1,2-二氯乙烷稀释于Ar气中(3.95 mmol/L).以4-甲基-1-环己烯作为对比速率法实验的内标物,用4-甲基-1-环己烯开环反应的速率常数k=1015.3exp(-33400/T) s-1,以及从其产物的浓度推定出实验温度.经激波加热后的实验气体的终产物用气相色谱分析出主要成分为C2H3Cl,指示出主要反应通道为β消去反应.如把所有产物C2H3Cl都归于β消去反应,则可推定出表观之反应速率常数k1a=5.0×1013exp(-30000/T) s-1.对于由C-Cl键断键反应引发的链反应的可能影响做了分析研究.用了一种简便分析可推知在实验的温度范围内的低端(1020 K)链反应的影响可以忽略,而在其高端(1190 K)链反应将给出10%的终产物C2H3Cl的附加浓度,获得真实的β消去反应速率常数则必须把这部分予以扣除.经过这样的校正之后,最后得到CH2ClCH2Clβ消去反应速率常数为k1c=2.3×1013exp(-29200/T) s-1.

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.

Generation of 1.5-12 ns width-tunable 532 nm pulses by adopting laser-induced plasma shutter technique

The pulse-shaping technique has found widespread applications in nonlinear optics and material processing. Experimental research on laser-induced plasma shutter to control the 532 nm pulse width is conducted. The impacts of the total pulse output energy on pulse compression are investigated, and a useful conclusion can be drawn that there exists an optimal value of pulse energy at which the shortest output pulse of 3.23 ns can be obtained without a device for delay-time. Once the device for delay-time is employed to change the optical differences between two laser paths, the pulse width can be further shortened to 1.51 ns. In short, the 1.5-12 ns width-tunable 532 nm laser pulses have been obtained by adopting the laser-induced plasma shutter technique. (C) 2007 Elsevier GmbH. All rights reserved.

Laser-diode-pumped Cr4+,Nd3+: YAG with self-Q-switched laser output of 1.4 W

By use of a laser diode as a pump source, a self-Q-switched laser from a Cr,Nd:YAG crystal is demonstrated. The output Q-switched traces are very stable, the threshold pump power is 3.5 W, the pulse duration is 50 ns, and the slope efficiency is as high as 20%. In addition, the pulse width remains constant while the pulse repetition rate Varies with pump power. (C) 2000 Optical Society of America OCIS codes: 140.0140, 140.2020, 140.3380, 140.3480, 140.3540, 140.3580.

Effects of exposure to 50 Hz magnetic field of 1 mT on the performance of detour learning task by chicks

In the present study, we examined the effects of exposure to an extremely low-frequency magnetic field of 1 mT intensity on learning and memory in Lohmann brown domestic chicks using detour learning task. These results show that 20 h/day exposure to a low

Growth kinetics of 1-2 mm and 3-4 mm colonies of Nostoc sphaeroides (Cyanophyta) in outdoor culture

Nostoc sphaeroides Kutzing was cultivated in paddlewheel-driven raceway ponds and the growth kinetics of 1-2 mm and 3-4 mm colonies of N. sphaeroides was studied. The biomass productivities in 2.5 m(2) raceway ponds inoculated with 1-2 mm and 3-4 mm colonies were 5.2 and 0.25 g dry wt m(-2) stop d(-1), respectively. Furthermore, differently sized colonies showed different relative water content, total soluble carbohydrates, chlorophyll a content and density of filaments. This is the first report on mass culture of N. sphaeroides under outdoor conditions.

Small-Signal Equivalent-Circuit Model and Characterization of 1.55-mu m Buried Tunnel Junction Vertical-Cavity Surface-Emitting Lasers

The work was supported in part by the National Natural Science Foundation of China under Grant 60536010, Grant 60606019, Grant 60777029, and Grant 60820106004, and in part by the National Basic Research Program of China under Grant 2006CB604902, Grant 2006CB302806, and Grant 2006dfa11880.