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Additive Temporal Coloured Noise Induced Eckhaus Instability in Complex Ginzburg--Landau Equation System
WANG Xin, TIAN Xu, WANG Hong-Li, OUYANG Qi, , LI Hao
Chin. Phys. Lett. 2004, 21 (12):
2365-2368
.
The effect of additive coloured noises, which are correlated in time, on one-dimensional travelling waves in the complex Ginzburg--Landau equation is studied by numerical simulations. We found that a small coloured noise with temporal correlation could considerably influence the stability of one-dimensional wave trains. There exists an optimal temporal correlation of noise where travelling waves are the most vulnerable. To elucidate the phenomena, we statistically calculated the convective velocities Vg of the wave packets, and found that the coloured noise with an appropriate temporal correlation can decrease Vg, making the system convectively more unstable.
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Activation Characteristics of Fuel Breeding Blanket Module in Fusion Driven Subcritical System
HUANG Qun-Ying, LI Jian-Gang, CHEN Yi-Xue
Chin. Phys. Lett. 2004, 21 (12):
2384-2387
.
Shortage of energy resources and production of long-lived radioactivity wastes from fission reactors are among the main problems which will be faced in the world in the near future. The conceptual design of a fusion driven subcritical system (FDS) is underway in Institute of Plasma Physics, Chinese Academy of Sciences. There are alternative designs for multi-functional blanket modules of the FDS, such as fuel breeding blanket module (FBB) to produce fuels for fission reactors, tritium breeding blanket module to produce the fuel, i.e. tritium, for fusion reactor and waste transmutation blanket module to try to permanently dispose of long-lived radioactivity wastes from fission reactors, etc. Activation of the fuel breeding blanket of the fusion driven subcritical system (FDS-FBB) by D-T fusion neutrons from the plasma and fission neutrons from the hybrid blanket are calculated and analysed under the neutron wall loading 0.5MW/m2 and neutron fluence 15MW.yr/m2. The neutron spectrum is calculated with the worldwide-used transport code MCNP/4C and activation calculations are carried out with the well known European inventory code FISPACT/99 with the latest released IAEA Fusion Evaluated Nuclear Data Library FENDL-2.0 and the ENDF/B-V uranium evaluated data. Induced radioactivities, dose rates and afterheats, etc, for different components of the FDS-FBB are compared and analysed.
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Single-Walled Carbon Nanotubes Acting as Controllable Transport Channels
HUANG Bo-Da, XIA Yue-Yuan, ZHAO Ming-Wen, LI Feng, LIU Xiang-Dong, JI Yan-Ju, SONG Chen, TAN Zhen-Yu, LIU Hui
Chin. Phys. Lett. 2004, 21 (12):
2388-2391
.
The motion and equilibrium distribution of water molecules adsorbed inside neutral and negatively charged single-walled carbon nanotubes (SWNTs) have been studied using molecular dynamics simulations (MDSs) at room temperature based on CHARMM (Chemistry at HARvard Molecular Mechanics) potential parameters. We find that water molecules have a conspicuous electropism phenomenon and regular tubule patterns inside and outside the charged tube wall. The analyses of the motion behaviour of water molecules in the radial and axial directions show that by charging the SWNT, the adsorption efficiency is greatly enhanced, and the electric field produced by the charged SWNTs prevents water molecules from flowing out of the nanotube. However, water molecules can travel through the neutral SWNT in a fluctuating manner. This indicates that by electrically charging and uncharging the SWNTs, one can control the adsorption and transport behaviour of polar molecules in SWNTs for using as a stable storage medium or long transport channels. The transport velocity can be tailored by changing the charge on the SWNTs, which may have a further application as modulatable transport channels.
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Bichromatic Coherent Population Trapping Under Hanle Configuration
WANG Yi, , HU Zheng-Feng, XU Xin-Ping, ZHANG Peng-Fei, ZHANG Hai-Chao, LIU Hua, ZHAN Ming-Sheng, WANG Yu-Zhu,
Chin. Phys. Lett. 2004, 21 (12):
2392-2394
.
We report the observation of bichromatic coherent population trapping under the transition 87RbFg =1 → Fe = 0 with two linearly polarized laser beams by means of a Hanle effect configuration. The mechanism behind this effect is identified, and numerical solutions for the pump rates equations are presented.
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Dynamic Behaviour of Self-Diffraction in Bacteriorhodopsin Film
GUO Zong-Xia, CHEN Gui-Ying, ZHANG Chun-Ping, TIAN Jian-Guo, Q. Wang Song, SHEN Bin, FU Guang-Hua
Chin. Phys. Lett. 2004, 21 (12):
2418-2421
.
We investigate the dependences of the diffraction efficiency of the first order self-diffracted beam in bacteriorhodopsin (bR) films on the illumination time, the intensity and wavelength of the incident light. When the blue light ( λ = 488nm) and low intensity red light ( λ = 632.8nm) are incident on the bR film respectively, the diffraction efficiencies increase from zero to a stable value with the illumination time. When the green light ( λ = 533nm) and high-intensity red light illuminate the bR film respectively, the diffraction efficiencies increase from zero to the maximum and then decrease to a stable value with the illumination time. Rise and decay times are dependent on the intensity and wavelength of the incident light. The maximal diffraction efficiency of the red light is twice as high as that of the green light. The highest diffraction efficiency of 5.4% is obtained at 633 nm. The diffraction efficiency change with the time for the green light is larger than that for the blue and red light.
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Three-Rod Resonator for Krypton Lamp Pumped 1.8 kW Continuous-Wave Nd:YAG Laser
LI Qiang, FANG Ming-Xing, WANG Zhi-Yong, YU Zhen-Sheng, LEI Hong, GUO Jiang, LI Gang, ZUO Tie-Chuan
Chin. Phys. Lett. 2004, 21 (12):
2422-2425
.
A three-rod series resonator cw Nd:YAG laser suitable for the industrial applications is presented. The symmetrical resonator laser has been developed and is rated at 1820-W output power with beam parameter product 24mm.mrad. By utilizing the symmetrical resonator design, the characteristic of beam with multi-rod is not obviously decreased compared with that of a single one. The system total electro-optics efficiency of lamp pumped YAG crystal is as high as 4.0%. The main factors, which affect output power and beam quality of high power solid-state laser module, are theoretically analysed.
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Polarized Emission of an Eu3+ Doped Azo-Polymer Waveguide
WANG Dong, ZHANG Jiang-Ying, MING Hai, YAN Qing, ZHANG Qi-Jin, WANG Pei, YANG Jun, ZHENG Zhi-Qiang
Chin. Phys. Lett. 2004, 21 (12):
2445-2447
.
We investigate the polarized emission behaviour of an Eu3+ doped azo-polymer waveguide. Affected by the azobenzene groups in the photoinduced orientation process by the 532nm linearly polarized laser, the ligands were realigned orderly perpendicular to the direction of the orientation direction. This leads to the polarized absorption and emission of the waveguide in the orientation direction. By an m-line apparatus based on the prism coupling technique, two guided propagation modes were observed in the waveguide, and the refractive index at 650nm in TE polarizations is 1.7505.
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Nonlinear-Ion-Acoustic-Wave Instability, Threshold, Half Width of Trapped Region and Transition Region
XIAO Zuo, WANG Wen-Qing, HAO Yong-Qiang
Chin. Phys. Lett. 2004, 21 (12):
2461-2464
.
Nonlinear Landau damping of ion acoustic wave (IAW) is one of the most important phenomena in the ionosphere and in space and laboratory plasma as well. The instability growth rate of the IAW with electron drift, the amplitude threshold for exciting the nonlinear effects, the half widths of the trapped region with the trapped electrons are studied experimentally. Under the experimental conditions, it is shown that there is a frequency range of 140--160 kHz, within which the growth rate has the largest value of about 6×104--1.5×105 s-1. We obtain the transitional region width caused by collisions theoretically and experimentally, for the first time to our knowledge. The experimental results are in good agreement with the theoretical prediction.
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Radiation Energy Loss from Laser-Heated Shenguang-II Hohlraums
CHANG Tie-Qiang, WANG Guang-Yu, DUAN Qing-Sheng, PEI Wen-Bing, GU Pei-Jun, ZHANG Xing-Hong, DING Yong-Kun,
ZHENG Zhi-Jian, YANG Jia-Min, HUANG Tian-Xuan, SUN Ke-Xu
Chin. Phys. Lett. 2004, 21 (12):
2469-2471
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The x ray energy loss out of laser-heated hohlraum through laser entrance holes (LEH) is discussed in detail according to a simple theoretical model and is compared with the hohlraum experimental data measured at Shenguang II laser facility. The radiation loss is considered to be composed of two parts, that is, direct contribution from laser spots and re-emitted part from the x ray-heated hohlraum inner wall, and the former accounts for about 20% of the total loss for the Shenguang II hohlraums. Owing to the non-equilibrium characteristics of laser target coupling the direct contribution part is non-equilibrium in spectrum.
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First Divertor Operation on the HL-2A Tokamak
YANG Qing-Wei, DING Xuan-Tong, YAN Long-Wen, XUAN Wei-Min, LIU De-Quan, CHEN Liao-Yuan, SONG Xian-Ming, YUAN Bao-Shan, ZHANG Jin-Hua, CAO Zeng, LI Xiao-Dong, MAO Wei-Cheng, ZHOU Cai-Pin, WANG En-Yao, YAN Jian-Cheng, LIU Yong, HL-A team
Chin. Phys. Lett. 2004, 21 (12):
2475-2478
.
HL-2A device is the first divertor tokamak in China. One of its main subjects is to study the features of the divertor plasma. In the last campaign, the first divertor configuration has been achieved and sustained on the HL-2A tokamak. Here we give a brief description about the HL-2A tokamak, diagnostics arrangements, and the equilibrium analysis results on divertor configuration. The main results of divertor experiments are also presented.
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Experimental Investigation on Low Magnetic Field Operation of an Overmoded Slow-Wave High-Power Microwave Generator
ZHANG Jun, ZHONG Hui-Huang, SHU Ting, LUO Ling, WANG Yong
Chin. Phys. Lett. 2004, 21 (12):
2479-2481
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The experimental results of an overmoded slow-wave high-power microwave generator operated at low magnetic field are presented. The feasibility of low magnetic field operation is investigated both theoretically and experimentally based on the characteristics of the overmoded slow-wave device. The experiments were carried out at the Spark-2 accelerator. Under the condition of guiding magnetic field strength of 0.55T, diode voltage of 474kV, and beam current of 5.2kA, a microwave was generated with power of 510MW, mode of TM01, and frequency of 9.54GHz. The relative half-width of the frequency spectrum is less than 1%, and the beam-to-microwave efficiency is about 21% in our experiments.
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A Mechanism for the Self-Organization of Colloidal Gold Nanoparticles
ZHANG Yong-Jun, HAN Guan-Qi, LI Wei, DAI Min, ZHANG Yu, HUANG Xin-Fan, CHEN Kun-Ji
Chin. Phys. Lett. 2004, 21 (12):
2486-2488
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We report a two-stage mechanism of formation of the two-dimensional surperlattices in colloidal gold nanoparticles. The first stage is the formation and growth of holes. When the film is thinner than the "pancake" thickness and because the solvent volatility holes nucleate and grow, the dry solid surface is exposed. The second stage corresponds to the reorganization of the colloids in the impacted areas between several holes, in which the particles gathering along the rims order due to the van der Waals-type attraction between colloids and the confinement by the length of dodecanethiol. Then at a compromised distance and perfect position giving the minimum free energy, ordering occurs in small domains along the boundary of the hole. When the ordered domains become closer because of the hole growth, they rotate at certain angles and the further ordering appears.
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Enhancement of Critical Current Density in Graphite Doped MgB2 Wires
XU Hong-Liang, , FENG Yong, XU Zheng, YAN Guo, CAO Lie-Zhao, LI Xiao-Guang
Chin. Phys. Lett. 2004, 21 (12):
2511-2513
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Graphite doped MgB2-xCx (x = 0.00, 0.05, 0.10) wires were fabricated via the in situ powder-in-tube method in flowing argon by using low carbon steel tubes as the sheath materials. With the increase of graphite concentration, the amount of unreacted graphite in the core area increases, and the average grain size of MgB2 decreases. It is found that the critical current density Jc can be significantly improved by graphite doping. The MgB2 wire with x = 0.05 exhibits the best Jc value of 16710A/cm2 at 6K, 4.5T, but the MgB1.9C0.1 wire has the highest Jc value of 2060 A/cm2 at 6K, 8T. It is suggested that the enhancement of Jc is due to not only the improvement of the microstructure features but also the introduction of pinning centres.
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Ultrafast Energy Transfer and Enhanced Two-Photon Absorption in a Novel Porphyrin Side-Chain Polymer
WANG Hui, HUANG Ya-Ping, DENG Li, ZHAO Fu-Li, LIN Wei-Zhu, WANG Jian, LIANG Zhao-Xi
Chin. Phys. Lett. 2004, 21 (12):
2521-2524
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Ultrafast relaxation processes and transient two-photon absorption are studied in a novel porphyrin side-chain polymer, 5-hydroxy-10,15,20-triphenyl-porphyrin-poly(glycidyl methacrylate) (HTPP-PGMA), by using picosecond luminescence spectroscopy and femtosecond pump--probe techniques. HTPP-PGMA exhibits the ultrafast initial luminescence decay (~300ps), which is absent in the conventional porphyrin monomer such as TPP. Enhanced two-photon absorption was observed in HTPP-PGMA; the corresponding Im x(3) is about 2.8× 1011esu, which is almost one order of magnitude larger than that of the conventional porphyrin monomer (TPP) (~1.3×1012esu). The ultrafast energy transfer plays an important role in the excited-state relaxation dynamics observed in HTPP-PGMA. The potential application of HTPP-PGMA in optical switching is discussed.
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Abnormal Energy Dependence of Photoluminescence Decay Time in InGaN Epilayer
HUANG Jin-Song, LUO Xiang-Dong, YANG Xu-Dong, SUN Zheng, SUN Bao-Quan, XU Zhong-Ying, GE Wei-Kun
Chin. Phys. Lett. 2004, 21 (12):
2529-2532
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We employ photoluminescence (PL) and time-resolved PL to study exciton localization effect in InGaN epilayers. By measuring the exciton decay time as a function of the monitored emission energy at different temperatures, we have found unusual behaviour of the energy dependence in the PL decay process. At low temperature, the measured PL decay time increases with the emission energy. It decreases with the emission energy at 200K, and remains nearly constant at the intermediate temperature of 120K. We have studied the dot size effect on the radiative recombination time by calculating the temperature dependence of the exciton recombination lifetime in quantum dots, and have found that the observed behaviour can be well correlated to the exciton localization in quantum dots. This suggestion is further supported by steady state PL results
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Photoluminescence Characterization of Silicon Nanoparticles Hybridized Europium Complex
RAN Guang-Zhao, BIAN Zu-Qiang, LIU Shi-Feng, HUANG Chun-Hui, QIN Guo-Gang,
Chin. Phys. Lett. 2004, 21 (12):
2533-2535
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A europium complex Eu (DBM)3 TPPO (Eu tris(benzoylmethide)- (triphenylphosphine oxide)) and silicon nanoparticles have been hybridized. The hybridization can evidently change the photoluminescence (PL) characteristics of the Eu complex in the following aspects: under an excitation of 390nm, the intensity of the PL peak at 611nm due to the 5D0--7F2 transition of the Eu3+ ions has been increased by 30%, and the integrated PL intensity in the visible range has been increased by nearly 3 times; the PL excitation efficiency beyond 440nm has been improved evidently; the peak in the PL excitation spectrum shifts from 408 to 388nm, and the PL decay time decreases from 2.07 to 0.96μs. The experimental results indicate that in the PL process, the photoexcited energy may transfer from the silicon nanoparticles to the Eu3+ ions.
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Mechanical Properties of Breast Cancer Cell Membrane Studied with Optical Tweezers
GUO Hong-Lian, LIU Chun-Xiang, DUAN Jian-Fa, Jiang Yu-Qiang, HAN Xue-Hai, LI Zhao-Lin, CHENG Bing-Ying, ZHANG Dao-Zhong
Chin. Phys. Lett. 2004, 21 (12):
2543-2546
.
Membrane tethers are extracted from breast cancer cells using a force generated by an optical trap. It is experimentally obtained that the radius of tether is about 0.1μm and the static tether force is about
8.5 pN. Calculations based on the experimental measurements give a bending modulus for the tether of 1.35×10-19Nm and a surface membrane tension of 6.76×10-6N/m in the breast cancer
cell. The treatment with cytochalasin D results in the decreasing bending modulus and decreasing apparent surface tension. When the membrane protein caveolin is over-expressed, similar cases occur in bending modulus and apparent surface tension. In addition, the viscous resistance coefficient of the membrane is calculated to be 1.15pN.s/μm according to the dynamic tether forces obtained under different pulling velocities.
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65 articles
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