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A New Quantum Key Distribution Scheme Based on Frequency and Time Coding
ZHU Chang-Hua, PEI Chang-Xing, QUAN Dong-Xiao, GAO Jing-Liang, CHEN Nan, YI Yun-Hui
Chin. Phys. Lett. 2010, 27 (9):
090301
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DOI: 10.1088/0256-307X/27/9/090301
A new scheme of quantum key distribution (QKD) using frequency and time coding is proposed, in which the security is based on the frequency-time uncertainty relation. In this scheme, the binary information sequence is encoded randomly on either the central frequency or the time delay of the optical pulse at the sender. The central frequency of the single photon pulse is set as ω1 for bit 0 and set as ω2 for bit 1 when frequency coding is selected. However, the single photon pulse is not delayed for bit 0 and is delayed in τ for 1 when time coding is selected. At the receiver, either the frequency or the time delay of the pulse is measured randomly, and the final key is obtained after basis comparison, data reconciliation and privacy amplification. With the proposed method, the effect of the noise in the fiber channel and environment on the QKD system can be reduced effectively.
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Testing Evolution Equation for Entanglement of Two-Qubit Systems in Noisy Channels on Ensemble Quantum Computers
ZHANG Han, , LUO Jun, REN Ting-Ting, , SUN Xian-Ping,
Chin. Phys. Lett. 2010, 27 (9):
090303
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DOI: 10.1088/0256-307X/27/9/090303
We report the experimental demonstration of decoherence dynamics of entanglement for the four Bell states in two-qubit nuclear-spin systems on ensemble quantum computers. Using artificial error operators to simulate noisy channels, we experimentally investigate the effect of noises on the four Bell states, and furthermore observe the time evolution of entanglement for the four Bell states in different noisy channels by calculating concurrences. Our experimental results show that the concurrences of the different Bell states under the same artificial error operations have the same values within the experimental error, and are independent of the different Bell states. These experimental results verify the theoretical evolution equation developed by Konrad et al.[Nature Phys. 4(2008)99] for two-qubit entanglement.
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Elastic Scattering of 6He + p at 82.3MeV/nucleon
FAISAL Jamil-Qureshi, LOU Jian-Ling, YE Yan-Lin, CAO Zhong-Xin, JIANG Dong-Xing, ZHENG Tao, HUA Hui, LI Zhi-Huan, LI Xiang-Qing, GE Yu-Cheng, PANG Dan-Yang, LI Qi-Te, XIAO Jun, LV Lin-Hui, QIAO Rui, YOU Hai-Bo, CHEN Rui-Jiu, LU Fei, Sakurai H, Otsu H, Nishimura M, Sakaguchi S, Baba H, Togano Y, Yoneda K, LI Chen, WANG Shuo, WANG He, LI Kuo-Ang, Nakamura T, Nakayama Y, Kondo Y, Deguchi S, Satou Y, Tshoo K H
Chin. Phys. Lett. 2010, 27 (9):
092501
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DOI: 10.1088/0256-307X/27/9/092501
Differential cross sections for the elastic scattering of halo nucleus 6He on proton target were measured at 82.3MeV/u. The experimental results are well reproduced by optical model calculations using global potential KD02 with a reduction of the depth of real volume part by a factor of 0.7. A systematic analysis shows that this behavior might be related to the weakly bound property of unstable nuclei.
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Effect of Zeroth-Order beam on Azobenzene Polymer Surface Relief Gratings Fabricated by Phase-Mask Method
WU Wen-Xuan, LUO Yan-Hua, CHENG Xu-Sheng, TIAN Xiu-Jie, QIU Wei-Wei, REN Xi-Feng, ZHU Bing, ZHANG Qi-Jin,
Chin. Phys. Lett. 2010, 27 (9):
094202
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DOI: 10.1088/0256-307X/27/9/094202
In the fabrication of surface relief gratings (SRGs) on azobenzene polymer films with a zeroth-order suppressed diffraction phase mask, it is found that the SRGs' relief figure and period change with the irradiation time, and the period is doubled after a critical time. The time dependence of the changes in the SRG forming process is investigated by theoretical analysis and experiments. An optimum time range for inscription of the sub-micron SRGs is determined to be 5-8 min in terms of both the theoretical and experimental results.
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Range-Gated Laser Stroboscopic Imaging for Night Remote Surveillance
WANG Xin-Wei, ZHOU Yan, FAN Song-Tao, HE Jun, LIU Yu-Liang
Chin. Phys. Lett. 2010, 27 (9):
094203
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DOI: 10.1088/0256-307X/27/9/094203
For night remote surveillance, we present a method, the range-gated laser stroboscopic imaging(RGLSI), which uses a new kind of time delay integration mode to integrate target signals so that night remote surveillance can be realized by a low-energy illuminated laser. The time delay integration in this method has no influence on the video frame rate. Compared with the traditional range-gated laser imaging, RGLSI can reduce scintillation and target speckle effects and significantly improve the image signal-to-noise ratio analyzed. Even under low light level and low visibility conditions, the RGLSI system can effectively work. In a preliminary experiment, we have detected and recognized a railway bridge one kilometer away under a visibility of six kilometers, when the effective illuminated energy is 29.5 μJ.
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Wafer-Level Testable High-Speed Silicon Microring Modulator Integrated with Grating Couplers
XIAO Xi, ZHU Yu, XU Hai-Hua, ZHOU Liang, HU Ying-Tao, LI Zhi-Yong, LI Yun-Tao, YU Yu-De, YU Jin-Zhong
Chin. Phys. Lett. 2010, 27 (9):
094207
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DOI: 10.1088/0256-307X/27/9/094207
A wafer-level testable silicon-on-insulator-based microring modulator is demonstrated with high modulation speed, to which the grating couplers are integrated as the fiber-to-chip interfaces. Cost-efficient fabrications are realized with the help of optical structure and etching depth designs. Grating couplers and waveguides are patterned and etched together with the same slab thickness. Finally we obtain a 3-dB coupling bandwidth of about 60 nm and 10 Gb/s nonreturn-to-zero modulation by wafer-level optical and electrical measurements.
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Imaging for Borehole Wall by a Cylindrical Linear Phased Array
ZHANG Bi-Xing, SHI Fang-Fang, WU Xian-Mei, GONG Jun-Jie, ZHANG Cheng-Guang
Chin. Phys. Lett. 2010, 27 (9):
094301
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DOI: 10.1088/0256-307X/27/9/094301
A new ultrasonic cylindrical linear phased array (CLPA) transducer is designed and fabricated for the borehole wall imaging in petroleum logging based on the previous theoretical researches. First, the CLPA transducer, which is made up of numbers of the piezoelectric elements distributed on the surface of a cylinder uniformly, is designed and fabricated. By transmitting and receiving acoustic waves with 16 active elements and using different groups of the elements under the control of the electric system, the CLPA can scan all areas of the borehole wall dynamically and rapidly without a traditional mechanism around the borehole axis. Then, the theoretical and experimental investigations are conducted in detail for the borehole wall scanning and imaging by the steel pipe and casing borehole with defects distributed in different shapes and directions. It is shown by experiments that the CLPA transducer has good focusing characteristic and good resolution for the borehole wall imaging in acoustic logging.
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A Spectral Coupled-Mode Formulation for Sound Propagation around Axisymmetric Seamounts
LUO Wen-Yu, SCHMIDT Henrik
Chin. Phys. Lett. 2010, 27 (9):
094304
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DOI: 10.1088/0256-307X/27/9/094304
A spectral coupled-mode solution of the three-dimensional (3D) acoustic field generated by a point source in the presence of an axisymmetric seamount is developed. Based on the same theoretical foundation as the formulation presented by Taroudakis [J. Comput. Acoust. 4 (1996) 101], the present approach combines a spectral decomposition in azimuth with a coupled-mode theory for two-way range-dependent propagation. However, the earlier formulations are severely limited in terms of frequency, size and geometry of the seamount, the seabed composition, and the distance between the source and the seamount, and are therefore severely limited in regard to realistic seamount problems. Without changing the fundamental theoretical foundation, the present approach applies a number of modifications to the formulation, leading to orders of magnitude improvement in numerical efficiency for realistic problems. Therefore, realistic propagation and scattering scenarios can be modeled, including effects of seamount roughness and realistic sedimentary structure.
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K-Shell Spectra from CH-Tamped Aluminum Layers Irradiated with Intense Femtosecond Laser Pulses
XIONG Gang, ZHAO Yang, SHANG Wan-Li, HU Zhi-Min, ZHU Tuo, WEI Min-Xi, YANG Guo-Hong, ZHANG Ji-Yan, YANG Jia-Min
Chin. Phys. Lett. 2010, 27 (9):
095202
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DOI: 10.1088/0256-307X/27/9/095202
X-ray spectra of H-like and He-like aluminum ions from aluminum buried in CH layers irradiated with 30 fs, 200 TW laser are measured. The electron temperature and density are derived from line ratios of the He-α resonance line to its satellite lines. Typical temperatures of 490-646 eV and electron densities up to 7×1020 cm-3 are obtained. The results show that the electron density increases and temperature decreases with the increasing CH thickness.
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Small-Angle X-Ray Scattering Study on Nanostructures of Polyimide Films
LIU Xiao-Xu, YIN Jing-Hua, SUN Dao-Bin, BU Wen-Bin, CHENG Wei-Dong, WU Zhong-Hua
Chin. Phys. Lett. 2010, 27 (9):
096103
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DOI: 10.1088/0256-307X/27/9/096103
Inorganic nanohybrid polyimide (PI) is widely applied in electrical and electronic devices for its outstanding insulating properties. Samples 100CR and 100NH are made in Dupont. Among them, 100NH is a kind of pure PI films; however, 100CR is a kind of inorganic nanohybrid PI films with excellent corona-resistance. The nanostructure of PI films is investigated with small-angle x-ray scattering technique and transmission electron microscopy (TEM). The normalized volume fractions of the scatterers in the specimens are obtained with a tangent-by-tangent data analysis for the small-angle x-ray scattering data. The multi-hierarchical scatterers of 100NH can be divided into two dominant components, i.e., the sharp component and the wide component. The sharp component is corresponding to the contribution of PI molecular chains, and the wide component includes the aggregates formed by PI molecular chains and the film has nested dual-fractal characteristics, nevertheless the 100CR film possesses three types of scale scattering made up of inorganic nanoparticles, molecular chains and aggregates. The present films have multi-fractal structures. The distribution and structure of scattering body of two kinds of PI films are analyzed. The results of SAXS agree well with those of TEM methods.
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Structural, Electronic and Elastic Properties of Cubic Perovskites SrSnO3 and SrZrO3 under Hydrostatic Pressure Effect
SHI Li-Wei, DUAN Yi-Feng, YANG Xian-Qing, QIN Li-Xia
Chin. Phys. Lett. 2010, 27 (9):
096201
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DOI: 10.1088/0256-307X/27/9/096201
Using the plane-wave pesudopotential (PWPP) method within the generalized gradient approximation (GGA), we investigate the hydrostatic pressure induced effect on the structural, electronic and elastic properties of cubic perovskites SrSnO3 and SrZrO3. The pressure dependence of the lattice constants, some indirect and direct band gaps, the upper valence bandwidths, the elastic stiffness constants and the aggregate elastic moduli, as well as the Debye temperature are investigated. Our calculated ground-state results are in good agreement with the available experimental and theoretical data.
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Preparation of Thermo-Stable Bulk Metallic Glass of Nd60Cu20Ni10Al10 by Rapid Compression
YUAN Chao-Sheng, LIU Xiu-Ru, SHEN Ru, SUN Zhen-Ya, CHEN Bo, LV Shi-Jie, HE Zhu, HU Yun, HONG Shi-Ming
Chin. Phys. Lett. 2010, 27 (9):
096202
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DOI: 10.1088/0256-307X/27/9/096202
Melt of Nd60Cu20Ni10Al10 alloy is solidified by rapid compression from 0.1 to 5.5 GPa at 793 K and from 0.1 to 3.2 GPa at 873 K within 20 ms, separately. A fully bulk metallic glass is obtained by the rapid compression method. By comparing with as-cast bulk metallic glass (BMG), it is found that Nd60Cu20Ni10Al10 BMG prepared by rapid compression exhibits a higher thermodynamic stability and a paramagnetic property. The relationship between the glass-formation temperature and the pressure in rapid compression for the BMG is demonstrated in the P-T phase diagram.
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Collective Modes and Elastic Constants of Liquid Al83Cu17 Binary Alloy
B. Y. Thakore, S. G. Khambholja, P. H. Suthar, N. K. Bhatt, A. R. Jani
Chin. Phys. Lett. 2010, 27 (9):
096203
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DOI: 10.1088/0256-307X/27/9/096203
The collective dynamics (longitudinal and transverse phonon modes) are studied for aluminum-copper (Al-Cu) binary alloy in terms of the eigen-frequencies of the localized collective excitations. The model pseudopotential formalism is employed using a self-consistent phonon scheme by involving multiple scattering and phonon eigen-frequencies. These frequencies are expressed in terms of many-body correlation functions of atoms as well as of interatomic potential. The important ingredients in the present study are the pair-potential and pair-correlation functions. The most recent and sparingly used local field correlation functions are employed to investigate the influence of the screening effects on the vibrational dynamics of non-crystalline Al83Cu17 binary alloy. The results for the elastic constants like bulk modulus BT, rigidity modulus G, Poisson's ratio ξ, Young's modulus Y, Debye temperature θD, propagation velocity of elastic waves and dispersion curves are reported based on the collective modes of this binary alloys. The present results are consistent and confirm the applicability of model potential and self-consistent phonon theory for such studies.
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A Three-Component Model Suitable for Natural and Ventilated Cavitation
JI Bin, LUO Xian-Wu, ZHANG Yao, RAN Hong-Juan, XU Hong-Yuan, WU Yu-Lin
Chin. Phys. Lett. 2010, 27 (9):
096401
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DOI: 10.1088/0256-307X/27/9/096401
A three-component model based on mass transfer equation is proposed to simulate both the natural and ventilated cavitations. In the present cavitation model, the content of nuclei in the local flow field is updated synchronously, and is coupled with the Rayleigh-Plesset equation so as to capture the cavity development. The proposed model is applied for simulating the cavitating flow around a super-cavitating vehicle in different cavitation conditions. In the case of the natural cavitation simulation, the predicted cavitation characteristics including the cavity length and cavity diameter agrees fairly well with the analytical results. In the case of the mixed cavitation simulation, the gas ventilation obviously influences the development of cavity. With the increase of the gas ventilated rate, the natural cavitation is suppressed remarkably, and a super cavitation is formed even at a relatively larger natural cavitation number.
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A Density Functional Study of Atomic Carbon Adsorption on δ-Pu(111) Surface
WEI Hong-Yuan, XIONG Xiao-Ling, SONG Hong-Tao, LUO Shun-Zhong
Chin. Phys. Lett. 2010, 27 (9):
097102
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DOI: 10.1088/0256-307X/27/9/097102
Adsorption of atomic carbon on δ-Pu(111) surface is investigated systematically using density functional theory with RPBE functional. The adsorption energies, adsorption structures, Mulliken population, work functions, layer and projected density of states are calculated in wide ranges of coverage, which have never been studied before as far as we know. It is found that the hcp-hollow sites is the energetically favorable site for all the coverage range considered. The repulsive interaction is identified, and the adsorption energy decreases with the coverage, while work function increases linearly with the coverage. It is found that the C-Pu interaction is very strong due to the hybridization between the C 2p states and the Pu 5f, Pu 6p,Pu 6d states of topmost layer Plutonium atoms.
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Soft Magnetic Thin Films FeCoHfO for High-Frequency Noise Suppression Applications
LU Guang-Duo, ZHANG Huai-Wu, TANG Xiao-Li
Chin. Phys. Lett. 2010, 27 (9):
097501
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DOI: 10.1088/0256-307X/27/9/097501
A series of FeCoHfO films were fabricated by dc magnetron reactive sputtering at varying partial pressure of oxygen (P O2) from 0 to 11.7%, and the electrical and magnetic properties of films have been studied. It is shown that optimal Fe43.29Co19.51Hf7.49O29.71 films with desired properties can be obtained when the films were prepared under PO2= 5.1%. The films show superior properties of low coercivity, Hc~5.5 Oe, relatively high saturation magnetization, 4πMs~18.3 kG, high anisotropy field Hk~EM>65 Oe, and high electrical resistivity ρ~2675 µΩcm. Permeability spectra shows that the natural ferromagnetic resonant frequency is as high as ~3.1 GHz. The combined merits of the film make the films taken as an ideal candidate material for high-frequency applications such as noise suppressor. In addition, the effects of the film thickness and annealing treatment on the magnetic properties are also reported.
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Fabrication, Structural and Magnetic Properties for Aligned MnBi
LIU Yong-Sheng, ZHANG Jin-Cang, REN Zhong-Ming), GU Min-An, YANG Jing-Jing, CAO Shi-Xun, YANG Zheng-Long
Chin. Phys. Lett. 2010, 27 (9):
097502
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DOI: 10.1088/0256-307X/27/9/097502
MnBi compound is fabricated under a magnetic field of 1 T, and the c-axis of hexagonal MnBi crystal is aligned parallel to the magnetic field direction. The saturation magnetization Ms decreases with the increase of temperature. At temperatures below 200 K, the coercive field Hc is about 150 Oe, while the coercive field Hc increases with temperature above 200 K. From 200 K to 300 K, the remnant magnetization Mr and the Mr/Ms increase with the temperature. Below 200 K, Mr and Mr/Ms reach roughly a constant value. However, there is an abnormal increase at 100 K in Hc, Mr and Mr/Ms, which comes from a spin-reorientation in MnBi. Magnetization results show the spin-reorientation for MnBi at about 91 K due to the variations of the anisotropy constants.
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Modulation of Insulator-Metal Transition Temperature by Visible Light in La7/8Sr1/8MnO3 Thin Film
HU Ling, SUN Yu-Ping, WANG Bo, LUO Xuan, SHENG Zhi-Gao, ZHU Xue-Bin, SONG Wen-Hai, YANG Zhao-Rong, DAI Jian-Ming
Chin. Phys. Lett. 2010, 27 (9):
097504
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DOI: 10.1088/0256-307X/27/9/097504
Effects of magnetic field and light illumination on the electrical transport properties of La7/8Sr1/8MnO3 thin film grown on a Si substrate are investigated. The film shows an insulator-metal transition at TP≈191.9 K and a low-temperature resistance minimum at Tmin≈48 K in darkness. Both magnetic field and light illumination shift the insulator-metal transition temperature TP to be higher, while the low-temperature transport properties of the film induced by them show different trends. That is, the magnetic field and light illumination make the Tmin shift to lower and higher temperatures, respectively. The enhancement of both TP and Tmin under light illumination could be explained in terms of photoinduced hole-doping and demagnetization effects of La7/8Sr1/8MnO3.
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Structural and Magnetic Properties of Nd(Fe,Mo)12Nx Compounds Produced by Strip-Casting Method
LIU Shun-Quan, HAN Jing-Zhi, WANG Chang-Sheng, YANG Jin-Bo, DU Hong-Lin, YANG Ying-Chang
Chin. Phys. Lett. 2010, 27 (9):
097505
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DOI: 10.1088/0256-307X/27/9/097505
The strip casting (SC) technique is employed to fabricate Nd(Fe,Mo)12Nx magnets. The crystallographic structure, intrinsic and permanent magnetic properties, as well as the microstructures of the compound are investigated. There are prominent advantages for the SC Nd-Fe-Mo alloys and their nitrides when compared with the samples prepared by the conventional casting (CC) method: (1) SC technique rebounds to the formation of the compounds crystallizing in a ThMn12-type structure. A single-phased host alloy Nd(Fe,Mo)12 can be directly prepared by strip casting without any isothermal annealing. Accordingly, lower energy cost and less rare earth demand notablely benefit the manufacture processing from a point of economizing. (2) The intrinsic magnetic properties, such as Curie temperature Tc, saturation magnetization Ms and anisotropy field Ha of the SC sample exceed the CC sample due to a phase forming condition with less-Mo-depended. (3) The microstructure studies also demonstrate that the SC compound contains finer grains, better-proportioned phase distribution than the CC compound. Optimized final particles are observed aligned in their easy axis and the energy product of powder sample is up to (BH)max~22 MGOe (176 kJ/m3).
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Preparation and Characteristics of Nanoscale Diamond-Like Carbon Films for Resistive Memory Applications
FU Di, XIE Dan, ZHANG Chen-Hui, ZHANG Di, NIU Jie-Bin, QIAN He, LIU Li-Tian,
Chin. Phys. Lett. 2010, 27 (9):
098102
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DOI: 10.1088/0256-307X/27/9/098102
We propose diamond-like carbon (DLC) as the resistance change material for nonvolatile memory applications. Nanoscale DLC films are prepared by filtered cathodic vacuum arc technique and integrated to W/DLC/W structure devices. The deposited DLC film has a thickness of about 20 nm and high sp3 fraction content. Reversible bistable resistive switching from a high resistance state to a low resistance state, and vice versa, is observed under appropriate unipolar stimulation pulses. High resistance switching ratio (larger than a thousand times) and low level of switching power (about 11 μW) are demonstrated. We propose that the mechanism of the repetitive resistive switching is the growth and breakage of conductive sp2-like filaments in the predominantly sp3-type insulating carbon upon applications of voltage pulses, which is consistent with the experimental results.
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Spin Injection from Ferromagnetic Metal Directly into Non-Magnetic Semiconductor under Different Injection Currents
DENG Ning, TANG Jian-Shi, ZHANG Lei, ZHANG Shu-Chao, CHEN Pei-Yi
Chin. Phys. Lett. 2010, 27 (9):
098501
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DOI: 10.1088/0256-307X/27/9/098501
For ferromagnetic metal (FM)/semiconductor (SC) structure with ohmic contact, the effect of carrier polarization in the semiconductor combined with drift part of injection current on current polarization is investigated. Based on the general model we established here, spin injection efficiency under different injection current levels is calculated. Under a reasonable high injection current, current polarization in the semiconductor is actually much larger than that predicted by the conductivity mismatch model because the effect of carrier polarization is enhanced by the increasing drift current. An appreciable current polarization of 1% could be achieved for the FM/SC structure via ohmic contact, which means that efficient spin injection from FM into SC via ohmic contact is possible. The reported dependence of current polarization on temperature is verified quantitatively. To achieve even larger spin injection efficiency, a gradient doping semiconductor is suggested to enhance the drift current effect.
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Synergistic Effect of Auto-Activation and Small RNA Regulation on Gene Expression
XIONG Li-Ping, MA Yu-Qiang, TANG Lei-Han
Chin. Phys. Lett. 2010, 27 (9):
098701
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DOI: 10.1088/0256-307X/27/9/098701
Auto-activation and small ribonucleic acid (RNA)-mediated regulation are two important mechanisms in controlling gene expression. We study the synergistic effect of these two regulations on gene expression. It is found that under this combinatorial regulation, gene expression exhibits bistable behaviors at the transition regime, while each of these two regulations, if working solely, only leads to monostability. Within the stochastic framework, the base pairing strength between sRNA and mRNA plays an important role in controlling the transition time between on and off states. The noise strength of protein number in the off state approaches 1 and is smaller than that in the on state. The noise strength also depends on which parameters, the feedback strength or the synthesis rate of small RNA, are tuned in switching the gene expression on and off. Our findings may provide a new insight into gene-regulation mechanism and can be applied in synthetic biology.
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The Surface Gravitational Redshift of a Proto Neutron Star
ZHAO Xian-Feng
Chin. Phys. Lett. 2010, 27 (9):
099701
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DOI: 10.1088/0256-307X/27/9/099701
The influence of the σ* and Φ mesons on the surface gravitational redshift of a proto neutron star is investigated within the framework of relativistic mean field theory for the baryon octet {n,p,Λ,Σ-,Σ0, Σ+,Ξ-,Ξ0} system. It is found that, compared with those without considering the contribution of σ* and Φ mesons, the surface gravitational redshift decreases, corresponding to the maximum value of the mass decreasing from 0.2220 to 0.1937, about 12.7%. It is also found that the appearance of σ* and Φ mesons makes the surface gravitational redshift as a function of M/R decrease too, with M and R being the mass and radius of the proto neutron star.
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65 articles
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