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Volume 11 Issue 8
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Original Articles
Antishadowing Corrections in the Evolution Equation of Quark Distributions
ZHU Wei, XUE Dali*
Chin. Phys. Lett. 1994, 11 (8): 465-468 .  
Abstract   PDF(pc) (137KB) ( 358 )
We introduce the antishadowing effect to restore the momentum sum rule in the quantum chromodynamics evolution equation for quarks in small x region.

NNδ Interaction at Finite Temperature
ZHENG Guotong, SU Rukeng*
Chin. Phys. Lett. 1994, 11 (8): 469-471 .  
Abstract   PDF(pc) (118KB) ( 388 )
In the framework of finite-temperature field theory the NNδ interaction is discussed. We find that the temperature dependence of the effective mass of δ-meson is quite similar to that given from the finite-temperature quantum chromodynamics sum rules, and the δ-nucleon coupling constant will approach zero as temperature grows to 215 MeV.
Suppression of Dilepton in Expanding Hot Baryon-Rich Quark-Gluon Matter
HE Zejun, ZHANG Jiaju, CHENG Junfeng, XIU Xaoming
Chin. Phys. Lett. 1994, 11 (8): 472-475 .  
Abstract   PDF(pc) (225KB) ( 426 )
With the increase of the initial baryon density, the dilepton production in invariant masses between 2mπ and 1 GeV is shown to be suppressed and an abnormal peak of the dilepton spectrum appears near the invariant mass 0.75 GeV if a baryon-rich quark-gluon matter was formed in the ultrarelativistic nucleus-nucleus collision. These predictions are important for several large-scale experiments at CERN and Brookhaven.
Increase of the K++ Ratio Induced by Collective Effects in Relativistic Heavy-Ion Collisions
ZHENG Shian, LI Xueqian
Chin. Phys. Lett. 1994, 11 (8): 476-479 .  
Abstract   PDF(pc) (248KB) ( 384 )
The collective effects on the increase of the K++ ratio in relativistic heavy-ion collisions are analyzed with the excited nucleon model. The gradual increase of the K++ ratio from p-Be to p-Au to the Si-Au central collisions may be explained self-consistently by multiscattering and secondary hadron collisions without requiring the formation of the4quark gluon plasma.
Are Massive Main Sequence Stars and Wolf-Rayet Stars Detectable Sources of the Intersteller Medium 26A1?
PENG Qiuhe
Chin. Phys. Lett. 1994, 11 (8): 480-483 .  
Abstract   PDF(pc) (209KB) ( 458 )
Taken the recent experiments of nuclear physics into account, the massive main sequence stars and Wolf-Rayet stars are hard to provide enough interstellar medium 26A1 to be detected, which is discussed in the text.
Single Electron Capture for Impact of Proton on H2
WU Weimin*, GU Jian, WU Songmao, LU Fuquan, YANG Fujia
Chin. Phys. Lett. 1994, 11 (8): 484-487 .  
Abstract   PDF(pc) (195KB) ( 346 )
The cross sections of electron capture for 3-10 keV proton traversing H2 were measured by using the ‘growth rate’ method. The experimental procedure is described. The experimental results are in good agreement with the recommended data.
Efficient Formation of Large Chain Carbon Clusters
ZHU Lei, LU Jianzhong, WU Meiping, LI Yufen
Chin. Phys. Lett. 1994, 11 (8): 488-490 .  
Abstract   PDF(pc) (166KB) ( 389 )
We find that bare C-n clusters favor chain structure from n =4 up to 43 by laser desorption mass spectrometric study of C60 admixed with polystyrene, whereas both one- and two-dimensional structures should coexist in the same mass region in gas, phase generally. The origin of the anomaly was also proposed in the text.
Femtosecond Studies on Third-Order Optical Nonlinearities of Polyanilines
WANG Hui, LAI Tianshu, LIN Weizhu, MO Dang, OUYANG Meng*, GONG Kecheng*
Chin. Phys. Lett. 1994, 11 (8): 491-493 .  
Abstract   PDF(pc) (166KB) ( 481 )
The ultrafast dynamics of third order nonlinearities of polyaniline (PAn) and polyaniline doped in polymethyl mathacrylate (PAn-PMMA) films are investigated using femtosecond absorption spectroscopy. An ultrafast initial exciton deformation time of about 100fs is observed in PAn film. In PAn-PMMA film, the third-order nonlinearity results in an efficient two-photon absorption at about 2eV.
Structural Anomalies of Bi-2223 Phase in the Temperature Range of 8-305K
DONG Cheng, WU Fei, CHEN Hong, CHE Guangcan, LI Jingwei, FAN Yongxin, ZHAO Zhongxian
Chin. Phys. Lett. 1994, 11 (8): 494-497 .  
Abstract   PDF(pc) (206KB) ( 365 )
A nearly single-phased Bi-2223 sample with Tc 108K was studied by low-temperature powder x-ray diffraction. Several discontinuous changes of lattice parameters are observed around 245, 160, 125,100 and 20K. The most pronounced anomalies occur dose to the superconducting transition temperature. Our observation indicates that electron-lattice interaction is quite strong near Tc.
Effects of Hydrogen Ion Bombardment on Carbon Terminated Si (111) Surface Studied by LEED and AES
HU Xiaoming, LIN Zhangda
Chin. Phys. Lett. 1994, 11 (8): 498-501 .  
Abstract   PDF(pc) (182KB) ( 519 )
Etching effects of hydrogen ions on the Si(111)-(1x1)C surface have been studied by LEED (low-energy electron diffraction) and AES (Auger electron spectroscopy). It has been found that hydrogen ions, can break the carbon-silicon covalent bonds and cause a phase transition of Si(111)-(1x1)C to the reconstructed Si(111)-(7x7) structure.
Surface Free Energies and Morphologies of Chemical Vapor Deposited Diamond Films
ZHANG Yafei, ZHANG Fangqing, CHEN Guanghua
Chin. Phys. Lett. 1994, 11 (8): 502-505 .  
Abstract   PDF(pc) (254KB) ( 472 )
We have calculated the surface free energies of the chemical vapor deposited diamond crystals during the preparation process, using the model that a fraction of carbon dangling bonds on the growth surface are saturated by hydrogen. The results show that the surface free energies of the three most energetically favored crystal planes, i. e. (100), (110) and (111), can be used to interpret the changes of predominant facets in the surface morphology from {100} to {111} with increasing substrate temperature. In chemical vapor deposition conditions, it is found that the growth surfaces of diamond are more stable than that of graphite.
Structure and Oriented Growth of CoCr Films With Amorphous Ti Underlayer
YAN Minglang*, GENG Shengli, YANG Zheng
Chin. Phys. Lett. 1994, 11 (8): 506-509 .  
Abstract   PDF(pc) (207KB) ( 426 )
CoCr films with and without amorphous Ti underlayers were deposited by rf magnetron sputtering. We studied the growth characteristics and the dispersion of crystallographic orientation of CoCr films over a thickness range from 20 to 600nm. A 20nm-thick CoCr film with Ti underlayer possesses hcp structure and its c-axis is normal to the film plane. However, the CoCr flim without Ti underlayer is amorphous. Whether their structure are amorphous or hcp texture, the Ti underlayers always promote preferred orientation of CoCr films at the early growth stage.
Giant Magnetoresistance Effect in Melt Spun CoCu granular Alloys
LI Min, ZHAO Xuegen, ZHAO Tongyun, ZHAO Jiangao, SHEN Baogen, CHAI Weiping, GU Yousong, MAI Zhenhong, MEI Liangmo
Chin. Phys. Lett. 1994, 11 (8): 510-513 .  
Abstract   PDF(pc) (223KB) ( 426 )
granular magnetic CoxCu1-x(x= 0.05 - 0.5) alloy ribbons were prepared by melt spinning method, and the structural, magnetotransport, magnetic properties and the effects of annealing on these properties were studied by x-ray diffraction, vibrating sample magnetometer, magnetoresistance measurement at room temperature. Giant magnetoresistance was observed over a broad range of Co concentrations with a maximum magnetoresistance (MR) ratio of 7.8% (at x = 0.20 and 500°C annealing) under a magnetic field of 20kOe. The MR ratio increases with the annealing temperature and reaches a maximum at about 500°C and then drops. The dependence of MR and magnetization on magnetic field for various granule parameters were studied by controlling the nucleation and growth of Co granules.

Size and Temperature Dependence of Dielectric Constant of Ultrafine PbTiO3 Particles
QU Baodong, JIANG Bin, WANG Yuguo, ZHANG Peilin, ZHONG Weilie
Chin. Phys. Lett. 1994, 11 (8): 514-517 .  
Abstract   PDF(pc) (239KB) ( 533 )
Using sol-gel method, we prepared ferroelectric PbTiO3 fine particles with particle size covering the range 20-200nm; the dielectric properties of powder compact were studied in the present work. The room temperature dielectric constant increases with the decrease in particle size and reaches a maximum value at the size of about 40nm. The temperature dependence of dielectric constant involving the evolution of particle size during the measurement is discussed.
Influence of Rapid Thermal Annealing on Structural and Interfacial Properties of Lead-Zirconate-Titanate Thin Films Prepared by Excimer Laser Deposition
ZHENG Lirong, CHEN Yiqing, LIN Chenglu, ZOU Shichang
Chin. Phys. Lett. 1994, 11 (8): 518-521 .  
Abstract   PDF(pc) (234KB) ( 465 )
Lead zirconate titanate thin films were prepared by pulsed excimer laser deposition on silicon substrates. Rapid thermal annealing was used to improve its properties. Structural and interfacial characteristics of the films before and after annealing were investigated by x-ray diffraction, Rutherford backscattering spectrometry and automatic spreading resistance.
Fractal Property of the Cytoskeleton in the Living Cells
TANG Xiaowei, LIU Jinbo, WU Bichu
Chin. Phys. Lett. 1994, 11 (8): 522-525 .  
Abstract   PDF(pc) (199KB) ( 413 )
The fractal property of the cytoskeleton in the living cells is investigated. Based on the experimental data of intracellular particle movement, the self-similarity of the cytoskeleton in the living cells is observed and the fractal dimensions of different parts of the cytoskeleton determined by means of line-segment method vary from 1.35 to 2. The Quasi-Brownian movements of intracellular particles are clearly shown.
Phase Transition in 1+1 Dimensional Charged Dilaton Black Holes
CAI Ronggen, SU Rukeng
Chin. Phys. Lett. 1994, 11 (8): 526-528 .  
Abstract   PDF(pc) (100KB) ( 451 )
Using the Landau phase transition theory, we calculate some second moments of ther-modynamical quantities for two-dimensional charged dilaton black boles. We find that some second moments diverge, and a nonequilibrium phase transition occurs when the two-dimensional charged black boles are from the nonextreme to the extreme.
17 articles