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An Experiment for Generating the 14-Tone Stable Carriers Using Recirculating Frequency Shifter

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Chinese Physics Letters 2010年第9期27卷 103-106页

作者：田凤张晓光李建平席丽霞 Key Laboratory of Information Photonics and Optical Communications (BUPT) (Ministry of Education) Beijing University of Posts and Telecommunications Beijing 100876

In experiment, the generation of 14-tone stable carriers with recirculating frequency shifter is realized. Some factors that impact the performance of the carrier generation are discussed. It is experimentally found that the balance and the insertion loss of the inphase/quadrature （I/Q,） modulator, the accurate π/2 phase difference and equal power level of two rf signals which are applied to the two ports of the I/Q, modulator, the gain of the optical amplifier, the bandwidth and sharp window spectrum of the tunable filter and the stability of the optical signals＇ states of polarization fed into I/Q, modulator, play important roles in the generation of a stable multi-tone carrier source. By employing appropriate techniques we obtain 14-tone stable carriers in the experiment.

关键词： stabling Stability Stables Experimentation Harbours

Stable Narrow Linewidth 689 nm Diode Laser for the Second Stage Cooling and Trapping of Strontium Atoms

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Chinese Physics Letters 2010年第7期27卷 126-128页

作者：李烨林弋戈赵阳王强王少凯杨涛曹建平李天初方占军臧二军 Division of Electricity and Quantum Metrology National Institute of Metrology Beijing 100013 Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 Department of optical Engineering Beijing Institute of Technology Beijing 100081

We report stable narrow linewidth laser systems based on self-developed Littman configuration external cavity diode lasers （ECDLs）. The frequency of the ECDL is stabilized to a high fineness ultralow-expansion glass reference cavity with the Pound-Drever-Hall technique. By heterodyne beating of two identical systems, we conclude that the linewidth 4.3× 10^-14 at an averaging measurement time. of each ECDL is reduced to lower than 150 Hz and its frequency stability reaches time of 1 s, the averaged long-term frequency drift is less than 0.2 Hz/s over 30 h

关键词： stabling Stables Stability Lasers Timing Time Measurement

Ab initio Study of He Stability in hcp-Ti

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Chinese Physics Letters 2010年第12期27卷 42-45页

作者：代云雅杨莉彭述明龙兴贵高飞祖小涛 Department of Applied Physics University of Electronic Science and Technology of China Chengdu 610054 Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Mianyang 621900 Pacific Northwest National Laboratory PO Box 999 Richland WA 99352 USA

Tile stability of He in hep-Ti is studied using the a5 initio method based on the density functional theory. The results indicate that a single He atom prefers to occupy the tetrahedral site rather than the octahedral site. The interaction of He defects with Ti atoms is employed to explain the relative stabilities of He point defects in hcp-Ti. The relative stability of He defects in hcp-Ti is useful for He clustering and bubble nucleation in metal tritides, which provides the basis for development of improved atomistic models.

关键词： stabling Stables Stability Uses Defects

Conserved Residues in the Subunit Interface of tau Glutathione S-transferase Affect Catalytic and Structural Functions

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Journal of Integrative Plant Biology 2011年第1期53卷 35-43页

作者： Cai-Ling Wang Hai-Ling Yang College of Life Sciences and Biotechnology Beijing Forestry University Beijing 100083 China

The tau class glutathione S-transferases （GSTs） have important roles in stress tolerance and the detoxification of herbicides in crops and weeds. Structural investigations of a wheat tau GST （TaGSTU4） show two subunit interactions： a hydrogen bond between the Tyr93 and Pro65 from another subunit of the dimer, and two salt bridges between residues Glu78 and side chains of Arg95 and Arg99 in the opposite subunit. By investigating enzyme activities, kinetic parameters and structural characterizations, this study showed the following results：（i） the hydrogen bond interaction between the Tyr93 and Pro65 was not essential for dimerization, but contributed to the enzyme＇s catalytic activity, thermal stability and affinity towards substrates glutathione and 1-chloro-2, 4-dinitrobenzene; and （ii） two salt bridges mainly contributed to the protein structure stability and catalysis. The results of this study form a structural and functional basis for rational design of more selective and environmentally friendly herbicides.

关键词： Herbicides Glutathione stabling Salts Hydrogen Enzymes Hydrogenation Stability Brining Stables