bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance of multilayer dielectric grating irradiated by ultrashort optical pulse
Authors: Liu Shi-Jie  , Ma Jian-Yong  , Shen Zi-Cai  , Kong Wei-Jin  , Shen Jian  , Jin Yun-Xia  , Zhao Yuan-An  , Shao Jian-Da  , Fan Zheng-Xiu  ,   (1)中国科学院上海光学精密机械研究所，上海 201800; (2)中国科学院上海光学精密机械研究所，上海 201800;中国科学院研究生院，北京 100049
Published: December 2020

In the ultrashort pulse high-energy laser system based on chirped pulse amplification technique, multilayer dielectric grating with good output waveform and high laser induced damage threshold plays an important role. Based on Fourier spectral transform and rigorous modal method, optical characteristic of multilayer dielectric grating under irradiation of ultrashort optical pulse is analyzed. The results show that the reflected pulse at the -1 order exhibits asymmetrical Gaussian shape with oscillatory tail in the front edge and decreasing energy when the reflection bandwidth is narrower than the frequency bandwidth of the incident pulse with Guassian shape. The effect of structure parameters of multilayer dielectric grating on the reflection bandwidth are discussed in detail, which provides guidance to the design of multilayer dielectric grating with desired reflection bandwidth. Finally, near-field distribution of multilayer dielectric grating is analyzed to study its damages induced by ultrashort pulses.
Theoretical study of optical parametric chirped pulse amplification pumped by divergent beams
Authors: Liu Hua-Gang  , Zhang Ruo-Bing  , Zhang Hai-Qing  , Zhu Chen  , Ma Jing  , Wang Qing-Yue  ,   天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津 300072
Published: December 2020

The gain bandwidth of optical parametric chirped pulse amplification pumped by divergent beams has been theoretically studied. Several gain curves are simulated when the pump are non-diffraction-limited Gaussian beams or a beams having rectangular distribution in spatial spectrum respectively，using the method of Fourier transform and the fourth-order Runge-Kutta algorithm. The results show that the gain bandwidth of optical parametric chirped pulse amplification can be obviously improved by using divergent pump beams, either in the visible or in the near infrared region. Very high gain and broadband spectrum can be obtained if the divergence angle and intensity of the pump is selected properly.
First-principles calculation of Be(0001) thin films: quantum size effect and adsorption of atomic hydrogen
Authors: Song Hong-Zhou  , Zhang Ping  , Zhao Xian-Geng  ,   北京应用物理与计算数学研究所，北京  100088
Published: December 2020

We have carried out first-principles calculations of Be(0001) thin films to study the oscillatory quantum size effects exhibited in the surface energy, work function, and binding energy of the atomic hydrogen monolayer adsorption. The prominent enhancement of the surface density of states at the Fermi level makes Be(0001) thin films more metallic compared to the crystalline Be. As a result, the calculated energetics of Be films and the properties of atomic H adsorption onto Be(0001) surface are featured by a quantum oscillatory behavior. Furthermore, The prominent change in the Be(0001) surface electronic structure by the atomic hydrogen adsorption has also been shown.
Tunable split ring resonator and its effect
Authors: Zhang Fu-Li  , Zhao Xiao-Peng  ,   西北工业大学电流变技术研究所,西安 710072
Published: December 2020

It has been theoretically and experimentally shown that split ring resonators (SRRs) can be used as a negative permeability medium near its magnetic resonance frequency. In this paper, a new structure for magnetic resonance has been designed by introducing a short wire into the common SRRs. The effects of short wire on the transmission characteristics of SRRs and left-handed metamaterials (LHMs) are experimentally and numerically investigated. The results show that an additional capacitor, formed by short wire and the gap side of SRR, leads to higher capacitance around the gap and lower the resonance frequency of SRRs. The resonance frequency of SRRs decreases with the length of short wire, but increases with the distance between short wire and SRRs. The short wire has no significant influence on the negative permeability of SRR. It is also demonstrated that the left-handed transmission peak, negative permeability, antiresonance frequency of permittivity and negative refractive index of LHMs could be tuned by controlling the distance between the short wire and the SRR.
Growth mechanism of diamond-like carbon film based on the simulation model of atomic motion
Authors: Ma Tian-Bao  , Hu Yuan-Zhong  , Wang Hui  ,   清华大学摩擦学国家重点实验室，北京  100084
Published: December 2020

Molecular dynamics simulations are performed to study the growth of diamond-like carbon (DLC) films on the atomic scale. The behaviors of incident atoms on the surface are classified into four categories: surface freezing, migration, implantation and rebounding, according to the atomic movement. The behaviors of incident atoms have an important impact on microstructure and growth mode of DLC film. The transverse migration of the atoms is the main route of film relaxation. The competition between atomic implantation and migration determines the growth mode and final structures of the film. Energy dependence of surface behaviors of deposited atoms and film structures is analyzed statistically, which deepens the understanding of DLC film growth mechanism.
Rapid dendritic growth in highly undercooled ternary Ni-Cu-Co alloy
Authors: Zang Du-Yang  , Wang Hai-Peng  , Wei Bing-Bo  ,   西北工业大学应用物理系,西安 710072
Published: December 2020

Rapid dendritic growth in undercooled liquid Ni80Cu10Co10 alloy has been investigated. This liquid ternary alloy was undercooled by a large degree up to 335 K(0.2TL) with electromagnetic levitation method. The rapidly solidified microstructure is revealed to be α-Ni solid solution phase by X-ray diffraction and differential scanning calorimetry. With the increase of undercooling, the microstructure is drastically refined. Its morphology transfers from coarse dendrite into equiaxial grains when undercooling exceeds 110 K. The solute microsegregation is suppressed with the enhancement of solute trapping effect under high undercooling condition. The dendritic growth velocity was measured as a function of undercooling. At extremely large undercoolings, the dendritic growth velocity of α-Ni phase is restrained by the solute diffusion of Cu and Co, and even decreases once undercooling exceeds 284 K.
First principles study of the electronic structure of ReSi1.75
Authors: Qiu An-Ning  , Zhang Lan-Ting  , Wu Jian-Sheng  ,   上海交通大学材料科学与工程学院，教育部高温材料及高温测试开放实验室，上海 200030
Published: December 2020

First principles full-potential linearized augmented plane wave method with local density approximation (LDA) was applied to calculate the ground state properties of ReSi1.75 crystal. Optimized results show that the equilibrium lattice constant of ReSi1.75 is smaller than experimental data by about 0.6%. On the basis of LDA results, LDA+U method was used to calculate the electronic structure. When Ueff=U-J=4.4eV, ReSi1.75 has a narrow gap semiconductor band structure with an indirect gap of 0.12 eV and a direct gap of 0.36eV. Effective mass calculation shows the highly anisotropic character of ReSi1.75 crystals. The density of sates changes sharply near Fermi level，thus the thermoelectric properties can be improved by doping.
Study of electronic structure of 3, 4, 9, 10-perylenetetracarboxylic bisimidazole/Ag interface by photoemission
Authors: Zhang Wen-Hua  , Mo Xiong  , Wang Guo-Dong  , Wang Li-Wu  , Xu Fa-Qiang  , Pan Hai-Bin  , Shi Min-Min  , Chen Hong-Zheng  , Wang Mang  ,   (1)浙江大学高分子科学与工程系，杭州 310027; (2)中国科学技术大学国家同步辐射实验室，合肥 230029
Published: December 2020

Synchrotron radiation photoemission was used to investigate the interface between the organic semiconductor (BZP) and polycrystalline silver film. Before complete coverage by one monolayer, the BZP molecules interacted weekly with silver and a gap state appeared at 0.9eV below Fermi level. After the coverage is complete, the growth of BZP is inferred to be in the 3D-island mode and the interaction with the substrate gradually diminishes. Because of the final state effect, the highest occupied molecular orbital (HOMO) level shifts to higher binding energy and reaches ultimately 2.3eV of the HOMO level in the bulk. The deposition of BZP on silver surface resulted in the decrease of sample work function, which demonstrats interfacial dipoles forming on the BZP/Ag contact (Δ=0.3eV) and indicats the electrons being deviated from the organic molecules to the metal substrate. In addition, the effect of annealing and exposure to oxygen on the BZP/Ag interface has been taken into account. It is found that the binding energies of the characteristic peaks of BZP and the gap state hardly change after interface annealing at 250 ℃, but after being exposed to oxygen, the gap state disappears and the valence bands shift to lower binding energies.
Effects of excited states for d3 ions on spin-Hamiltonian parameters of the ground state 4A2 in axial-symmetrical crystal field
Authors: Wei Qun  , Yang Zi-Yuan  , Wang Can-Jun  , Xu Qi-Ming  ,   (1)宝鸡文理学院物理系非线性研究所，宝鸡  721007; (2)西安建筑科技大学材料科学与工程学院，西安  710055; (3)西安建筑科技大学材料科学与工程学院，西安  710055;宝鸡文理学院物理系非线性研究所，宝鸡  721007
Published: December 2020

The mechanism of influence of the spin quartets and doublets of d3 ion on the spin-Hamiltonian (SH) parameters(including zero-field splitting(ZFS) and g-factors)of the ground state 4A2(4F) is discussed in terms of complete diagonalization method(CDM) under trigonal symmetry and tetragonal symmetry. And these microcosmic mechanisms, including SO mechanism, SS mechanism, SOO mechanism, SO-SS-SOO combined mechanism have been analyzed. It is found that (1) the contributions to ZFS parameter from the spin quartets and doublets are all important; (2) the contributions to the g-factors of the ground state from the spin quartets are predominant, whereas the contributions from spin doublets are slight. In addition, it is shown that SS mechanism and SOO mechanism are determined by spin quartets in SH parameters calculation.
Hyperchaotic Lorenz system
Authors: Wang Xing-Yuan  , Wang Ming-Jun  ,   大连理工大学电子与信息工程学院，大连 116024
Published: December 2020

This paper presents a four-dimensional hyperchaotic Lorenz system, obtained by adding a nonlinear controller to Lorenz chaotic system. The hyperchaotic Lorenz system is studied by bifurcation diagram, Lyapunov exponent spectrum and phase diagram. Numerical simulations show that the new system's behavior can be convergent, divergent, periodic, chaotic and hyperchaotic as the parameter varies.
Calculation of energy levels in InGaAs/GaAs quantum dot array
Authors: Yang Xiao-Jie  , Wang Qing  , Ma Wen-Quan  , Chen Liang-Hui  ,   中国科学院半导体研究所纳米光电子实验室，北京 100083
Published: December 2020

The subbands of the ground state EC1, the first excited state EC2 and heavy hole state EHH1 are calculated by solving the eigenvalues of effective-mass Hamiltonian H0 which is derived from eight-band k·p theory and the calculations are performed at kx=ky=kz=0 for the three-dimensional array of InGaAs/GaAs quantum dots (QDs). With indium content in InGaAs QDs gradually increasing from 30% to 100%, the intersubband transition wavelength of EC2 to EC1 blue-shifts from 18.50 to 11.87 μm，while the transition wavelength of EC1 to EHH1 red-shifts from 1.04 to 1.73 μm. With the sizes of In0.5Ga0.5As and InAs QDs increasing from 1.0 to 5.0 nm, the intersubband transition from EC1 to EC2 transforms from bound-state-to-continuum-state to bound-state-to-bound-state, and the corresponding intersubband transition wavelengths red-shift from 8.12 μm (5.90 μm) to 53.47 μm (31.87 μm), respectively, and the transition wavelengths of EC1 to EHH1 red-shift from 1.13 μm (1.60 μm) to 1.27 μm (2.01 μm), respectively.
The total energy of Heisenberg ferromagnetic systems
Authors: Wang Huai-Yu  , Xia Qing  ,   (1)清华大学物理系,北京 100084; (2)西安机电信息技术研究所,西安 710065
Published: December 2020

The total energy of the Heisenberg ferromagnetic system is calculated by the many-body Green's function method under random phase approximation when the correlation function 〈S+S-〉 is considered. A general expression of the total energy universally applicable to any spin quantum number S is obtained. Numerical results are computed. The energy is lower than the case when the correlation function is not included.
Nonlinear noise reduction for the observation data of climatology based on the searching average method
Authors: Hou Wei  , Lian Yi  , Feng Guo-Lin  ,   (1)国家气候中心气候研究开放实验室，北京  100081；扬州大学物理科学与技术学院，扬州  225002; (2)吉林省气象科技研究所气候研究开放实验室，长春  130062; (3)吉林省气象科技研究所气候研究开放实验室，长春  130062；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029
Published: December 2020

The searching average nonlinear noise reduction method, which is based on local linear fit to the nonlinear dynamics, is introduced to reduce the noise in the observation data of climatology. Recurrence plots are used to estimate the size of local neighbors. The noise reduction is improved markedly. In order to show the validity of the program in noise reduction, it is first applied to a noise time series of Henon map contaminated by Gaussian white noise. And then, this noise reduction scheme is applied separately to the observation data of meteorology. The analyses of a nonlinear prediction demonstrate the efficiency of the method for noise reduction.
Mei symmetry and conserved quantity of Tzénoff equations for nonholonomic systems
Authors: Zheng Shi-Wang  , Jia Li-Qun  ,   (1)江南大学理学院，无锡  214122; (2)商丘师范学院物理与信息工程系，商丘  476000
Published: December 2020

The Mei symmetry of Tzénoff equations for nonholonomic systems under the infinitesimal transformation of groups is studied in this paper. The definition and the criterion equations of the symmetry are given. If the symmetry is a Lie symmetry, then the Hojman conserved quantity of the Tzénoff equation can be obtained by the Mei symmetry.
A solution to the ground and single vortex states of Bose-condensed gas in an axially symmetric harmonic trap
Authors: Xu Zhi-Jun  , Shi Jian-Qing  , Lin Guo-Cheng  ,   (1)浙江工业大学应用物理系，杭州  310032; (2)浙江工业大学应用物理系，杭州  310032；波谱与原子分子物理国家重点实验室，武汉  430071
Published: December 2020

For a Bose-condensed gas in an axially symmetric harmonic trap at zero temperature, a new trial wave function of the ground and single vortex states is considered based on the mean-field energy functional and variational method. Once the wave function is known, we can explore the particle-number dependence of relevant quantities, such as energy, chemical potential, aspect ratio of the velocity distribution and critical angular velocity for production of vortices. These results agree well with previous numerical solutions of the G-P equation given by Dalfovo et al.
Further discussions on the Hawking radiation of charged particles via tunneling from the Reissner-Norstrom black hole
Authors: Hu Ya-Peng  , Zhang Jing-Yi  , Zhao Zheng  ,   北京师范大学物理系，北京  100875
Published: December 2020

Taking for an example the Reissner-Norstrom black hole, we reinvestigate its Hawking radiation of charged particles via tunneling, which is viewed from the laws of black hole thermodynamics. After rewriting the imaginary part of the action into the related functions of laws of black hole thermodynamics, we find that there is an underlying relation between the first and second law of black hole thermodynamics and Hawking radiation via tunneling based on Parikh and Wilczek's original works. Moreover, if we consider the tunneling process as a reversible process, the result in Hawking radiation via tunneling is consistent with the first and second law of black hole thermodynamics. In other words, Parikh's conclusion is only valid for the reversible process.
A blind separation method for chaotic signals
Authors: Li Xue-Xia  , Feng Jiu-Chao  ,   (1)西南大学电子信息工程学院，重庆  400715; (2)西南大学电子信息工程学院，重庆  400715；华南理工大学电子与信息学院，广州  510641
Published: December 2020

Separation of multiple mixing chaotic signals is an important issue in chaos and its applications. An instantaneous blind separation method for linearly mixed chaotic signals is proposed in this paper, in which the uncorrelation characteristics of chaotic signals are utilized. In the case of unknown mixture matrix and chaotic equations, the inverse matrix for reconstructing the source chaotic signals can be directly estimated from the observation by the approach of solving eigenvectors. The results by computer simulation indicate that the multiple mixing chaotic signals, by using the method, can be effectively separated from noisy background even when the signal to noise ration is low.
Chaotic time series prediction based on RBF neural networks with a new clustering algorithm
Authors: Zhang Jun-Feng  , Hu Shou-Song  ,   南京航空航天大学自动化学院,210016  南京
Published: December 2020

Two-phase learning method is considered in this paper to configure the RBF neural networks for chaotic time series prediction. When determining the hidden-layer centers with the unsupervised learning algorithm, a new distance measure is presented based on Gaussian basis, and the strategy of input-output clustering is employed in combination. The punishment factor in Gaussian basis distance is designed based on Fisher separable ratio, which can improve the clustering performance. Moreover, the introduction of input-output clustering strategy establishes the relation between the clustering performance and the prediction performance. Therefore, the RBF neural networks constructed by this method can not only assure the compact structure, but also improve the prediction performance. This method is applied to Mackey-Glass, Lorenz and Logistic chaotic time series prediction, and the results indicate its validity.
The complexity measure analysis of conductance fluctuation signals of gas-liquid two-phase flow and its flow pattern characterization
Authors: Jin Ning-De  , Dong Fang  , Zhao Shu  ,   天津大学电气与自动化工程学院，天津  300072
Published: December 2020

To discuss the relation between complexity measures extracted from time series and flow pattern transition in gas-liquid two-phase flow, this paper analyzes the recognition capability of three complexity measures, including Lempel-Ziv complexity, spectral entropy and approximate entropy to different signals, such as periodic signal, stochastic signal, mixed stochastic signal and chaotic signal, and then the paper discusses the influence of the length of time series to the algorithms of the three complexity measures. Based on the above studies, we extracted the three complexity measures from eighty conductance fluctuating signals of gas-liquid two phase flow in vertical upward pipe. The results indicate that the three complexity measures are sensitive to the flow pattern transition in gas-liquid two-phase flow. By analyzing the rules of three complexity measures with the changes of gas-liquid two-phase flow parameters, we can get the dynamics structure inversion characters of gas-liquid two-phase flow, and they provide an efficient, supplementary diagnostic tool to reveal the flow pattern transition mechanism of gas-liquid two-phase flow.
The coherence of resonance fluorescence for two atoms in a cavity
Authors: Cheng Gui-Ping  , Ke Sha-Sha  , Zhang Li-Hui  , Li Gao-Xiang  ,   (1)华中师范大学物理科学与技术学院，武汉  430079; (2)江汉大学物理系，武汉  430056
Published: December 2020

We have investigated the coherence of resonance fluorescence for a coherently driven two two-level atoms coupled to a single-mode cavity in the bad cavity limit. By adjusting the detuning of the cavity-mode frequency from the driving filed frequency, we can enhance the fringe contrast factor as well as decrease the second order correlation function. The surprising effect produced by the detuning has an effect on the atomic dress-state population, which makes the fringe contrast factor and the second order correlation function changed evidently.
Dipole squeezing in the system of the two-mode entangled coherent field interacting with atoms in Bell states in Kerr medium
Authors: Lin Ji-Cheng  , Zheng Xiao-Hu  , Cao Zhuo-Liang  ,   (1)安徽大学物理与材料科学学院，合肥  230039; (2)南京晓庄学院物理系，南京  210017；安徽大学物理与材料科学学院，合肥  230039
Published: December 2020

The atomic dipole squeezing effect in the system of two identical two-level atoms in the Bell state interacting with the two-mode entangled coherent state field in Kerr medium are investigated by means of solving the Schrdinger equation and numerical calculations. The effects on the atomic dipole squeezing effect produced by the atomic initial state, mean photon number of light field, the degree of the entanglement of the entangled coherent field, the coupling strength of the Kerr medium with the light field and the coupling strength of dipole-dipole interaction between atoms are discussed. The results show that the dipole squeezing effect does not appear for the Bell state |β11>, while there can be dipole squeezing effect under certain conditions for the Bell states |β00> or |β01> or |β10>. In the latter case, the dipole squeezing effect depends on the coupling strength of the Kerr medium with the light field, the mean photon number and the degree of entanglement of the two-mode entangled coherent field.
Mutual interactions of multiple partially incoherent spatial solitons
Authors: Huang Chun-Fu  , Guo Ru  , Liu Si-Min  ,   南开大学物理学院,天津  300071
Published: December 2020

We investigate numerically the interactions of multiple partially incoherent spatial solitons in a nonlinear medium with logarithmic saturable nonlinearity based on the coherent density approach. Numerical results show that the interactions of incoherent solitons is somewhat similar to that of coherent solitons when the incoherence parameter is small; while for large incoherence parameter, the interactions of incoherent solitons are always attractive because the strong incoherent interactions blur out the initial relative phase between the incoherent solitons. Especially for the π-out-of-phase incoherent solitons, they can propagate in parallel under appropriate incoherence parameter. Mutual interactions of multiple partially incoherent spatial solitons can lead to a variety of induced waveguide configurations that allows steering, switching and guiding light with light.
Study of complete photonic band gap in two-dimensional chessboard of non-Bravais lattice
Authors: Wang Jing-Li  , Chen He-Ming  ,   南京邮电大学光电工程学院光纤通信研究所，南京  210003
Published: December 2020

A two-dimensional chessboard of non-Bravais lattice is designed in this paper: the square columns in photonic structure of a two-dimensional square lattice are rotated by 45°,and a cylinder is introduced into the center of each lattice unit cell. The complete photonic band gap in two-dimensional chessboard of non-Bravais lattice is calculated by the plane wave expansion method. The result shows that a gap width to midgap frequency ratio Δω/ω of chessboard non-Bravais lattice is almost 5 times that of the ordinary chessboard lattice, and the number of complete photonic band gaps is increased. Comparaed with other compound lattices, the optimal Δω/ω of chessboard non-Bravais lattice is 2.1 times that of a kind of compound lattices.
Design of triangular lattice photonic crystals using genetic algorithms
Authors: Gong Chun-Juan  , Hu Xiong-Wei  ,   中国科学院半导体研究所集成光电子学国家重点实验室，北京  100083
Published: December 2020

Genetic Algorithms (GAs) were used to design triangular lattice photonic crystals with large absolute band-gap. Considering fabricating issues, the algorithms represented the unit cell with large pixels and took the largest absolute band-gap under the fifth band as the objective function. By integrating Fourier transform data storage mechanism, the algorithms ran efficiently and effectively and optimized a triangular lattice photonic crystal with scatters in the shape of ‘dielectric-air rod'. It had a large absolute band gap with relative width (ratio of gap width to midgap) 23.8%.
Parameter identification and backstepping design of synchronization controller for uncertain chaotic system
Authors: Lü Ling  , Guo Zhi-An  , Li Yan  , Xia Xiao-Lan  ,   (1)大连交通大学数理系,大连  116028; (2)辽宁师范大学物理与电子技术学院,大连  116029
Published: December 2020

A parameter observer is designed to identify Rossler system with unknow parameters. Chaos synchronization between uncertain Rossler system and Coullet system is realized via backstepping method.The synchronization controller is presented based on stability theory, and the area of controlling gain is determined. The simulation results show that all the state variables in the Coullet system can track any desired trajectory in the Rossler system exactly when the parameter observer and backstepping controller are functioning, which shows the method is effective and feasible.
Vlasov simulation of the relativistic effect on the breaking of large amplitude plasma waves
Authors: Xu Hui  , Sheng Zheng-Ming  , Zhang Jie  ,   中国科学院物理研究所光物理实验室,北京  100080
Published: December 2020

The influence of relativistic and thermal effects on plasma wave breaking has been studied by solving the coupled Vlasov-Poission equations. When the relativistic effect is not considered, the wave breaking will not occur, provided the initial perturbation is less than certain value as predicted previously, and the largest amplitude of the plasma wave will decrease with the increase of the initial temperature. When the relativistic effect is considered, wave breaking always occurs during the time evolution, irrespective of the initial perturbation amplitude. Yet the smaller the initial perturbation amplitude is, the longer is the time for wave breaking to occur. With large initial perturbations, wave breaking can always occur with and without the relativistic effect. However, the results are significantly different in the two cases. The thermal effects of electrons decrease the threshold value of initial amplitude for wave breaking and large phase velocity makes the nonlinear phenomenon occur more easily.
Indentation-induced crystallization in a metallic glass
Authors: Yan Zhi-Jie  , Li Jin-Fu  , Zhou Yao-He  , Wu Yan-Qing  ,   (1)上海交通大学环境科学与工程学院，上海  200030; (2)上海交通大学金属基复合材料国家重点实验室，材料学院，上海  200030; (3)上海交通大学金属基复合材料国家重点实验室，材料学院，上海  200030；太原科技大学材料科学与工程学院，太原  030024
Published: December 2020

The microstructure change in the Vickers indent of the Zr65Al7.5Ni10Cu12.5Ag5 metallic glass at room temperature is investigated by transmission electron microscopy. It is found that the indentation-induced crystallization occurs namely underneath the indenter edges, where viscous flow is involved and crystals with the size larger than 1 μm appeav. The selected area electron diffraction shows that the crystalline phases are stable tetragonal CuZr2 or NiZr2, but not the icosahedral one that grows as metastable phase on heating. The local temperature rise during indentation can be ignored, which further suggests that the mechanically induced crystallization in a metallic glass is attributed to the viscous flow rather than the local heating effect.
Effect of ramping from low temperatures on oxygen precipitation in Czochralski silicon
Authors: Cui Can  , Ma Xiang-Yang  , Yang De-Ren  ,   (1)浙江大学硅材料国家重点实验室，杭州  310027; (2)浙江理工大学物理系，杭州  310018；浙江大学硅材料国家重点实验室，杭州  310027
Published: December 2020

Czochralski (CZ) silicon wafers were firstly subjected to a variety of ramping annealing from low temperatures to 750℃, and then subjected to a prolonged anneal at 750℃ for up to 64 h. It was revealed that the prior ramping anneal from low temperature lead to strong enhancement of oxygen precipitation in the subsequent annealing, and the lower the starting temperature the stronger the enhancement. It is considered that at low temperatures (450—650℃) the diffusion of oxygen was greatly enhanced and therefore the nucleation of oxygen precipitation was facilitated. Moreover, the slow ramping rate could also increase the stability as well as facilitate the growth of the oxygen precipitate nuclei formed at low temperature. A novel internal gettering (IG) process based on ramping anneal from low temperature has been developed, which can reduce the annealing time and therefore the thermal budget. However, the ramping anneal from low temperature is not available for the application of magic denude zone (MDZ) process.
Injection and transport of the charge carriers in metal/impurity polymer/metal structure
Authors: Li Hai-Hong  , Li Dong-Mei  , Liu Wen  , Li Yuan  , Liu Xiao-Jing  , Liu De-Sheng  , Xie Shi-Jie  ,   (1)山东大学物理与微电子学院，晶体材料国家重点实验室，济南  250100; (2)山东大学物理与微电子学院，晶体材料国家重点实验室，济南  250100；济宁学院物理系，曲阜  273100
Published: December 2020

Using the tight-binding Su-Schrieffer-Heeger (SSH) model and a nonadiabatic dynamical evolution method, the dynamic process of the charge carrier injection and transport through metal/ polymer/metal structure was studied, for which the polymer chain contains an impurity ion. The electron wave function was described by the time-dependent Schrdinger equation, while the polymer lattice was treated classically by the Newtonian equations of motion. It was found that the impurity ion acts as a control gate on the charge carriers, while the state of the control gate is determined by the strength of the electric field and the magnitude of the bias voltage.
Boundary alternating current characteristics of an ideal p-n junction diode
Authors: Halimulati  , Abai  , Baishan  , Aimaiti  ,   新疆大学物理科学与技术学院，乌鲁木齐  830046
Published: December 2020

According to basic assumptions about the ideal operating state of p-n junction diode, deducing the relation of the time dependence of constant on the parameters such as diode size, diffusion length, carrier lifetime and alternating current frequency etc. at the base and near the p-n junction interface when diode is working under the applied alternating current. From the results,we discovered that in the two kinds of states of low and high current frequencies, the diode characteristics act on the time constants differently. In the low frequency state, the time constant is related to the material characteristics but not to applied current frequency. But in high frequency state, the time constant has no relation with the material characteristics, and was only related to the applied current frequency.
The property of third-order optical nonlinear susceptibility of water soluble CdTe quantum dots
Authors: Wu Wen-Zhi  , Zheng Zhi-Ren  , Jin Qin-Han  , Yan Yu-Xi  , Liu Wei-Long  , Zhang Jian-Ping  , Yang Yan-Qiang  , Su Wen-Hui  ,   (1)哈尔滨工业大学，凝聚态科学与技术研究中心，哈尔滨  150001; (2)哈尔滨工业大学，凝聚态科学与技术研究中心，哈尔滨  150001；中国人民大学化学系，北京  100872; (3)吉林大学，化学学院微分析仪器研究所，长春  130021
Published: December 2020

The property of optical nonlinear susceptibility of the CdTe quantum dots (QDs) has been studied by using Z-scan and optical Kerr effect technique. Laser-induced sign reversal of the nonlinear refractive index of CdTe quantum dots appears under femtosecond and picosecond pulse excitation. Two-phonon absorption and free carrier absorption in the nanometer-sized CdTe are the possible origins of the nonlinear absorption. This material has the ultrafast response time of less than 400 fs in optical switching operation, and the peak Kerr transmittance is found to be 32 times greater than that of the standard CS2 liquid Kerr medium.
A method for generating chaotic spread-spectrum sequences and their optimized selection algorithm
Authors: Yu Zhen-Biao  , Feng Jiu-Chao  ,   华南理工大学电子与信息学院，广州  510641
Published: December 2020

A method for generating chaotic spread-spectrum sequences based on the combined chaotic map is proposed. An optimized selection algorithm based on the property requirement of spread-spectrum sequences and the performance index of multiple access interference is also presented. Simulation is performed for the optimized chaotic sequence, and an optimized logistic sequence is applied to a direct sequence spread-spectrum CDMA system under different channel conditions. The results show that the chaotic spread-spectrum sequences generated by the proposed method have similar performance as the logistic spread-spectrum sequences and have better security.
A new hyperchaotic Lü system and its circuit realization
Authors: Liu Yang-Zheng  ,   南京工程学院非线性物理研究所，南京  211167
Published: December 2020

The four-dimensional hyperchaos system is built by adding an additional state to the three-order Lü system. Some of its basic dynamical properties are studied briefly, such as the feature of equilibrium, the hyperchaos attractor, Lyapunov exponent and fractal dimension. An electronic circuit is designed to realize the four-dimensional hyperchaos system. Moreover, a novel analogue circuit is realized for the verification of various attractors.
Analysis and circuit implementation of a new four-dimensional non-autonomous hyper-chaotic system
Authors: Cang Shi-Jian  , Chen Zeng-Qiang  , Yuan Zhu-Zhi  ,   (1)南开大学自动化系，天津  300071; (2)天津科技大学工业设计系，天津  300222；南开大学自动化系，天津  300071
Published: December 2020

A new four-dimensional non-autonomous hyper-chaotic system is presented by adding input signal to a hyper-chaotic system based on Lorenz system. The resulting hyper-chaotic system may have any dynamic beharior among the periodic orbits, two-tori, chaos and hyper-chaos by controlling the frequency of input signal, while the periodic orbits are more prominent. The phenomenon in well demonstrated by numerical simulations and bifurcation analysis. Finally, an analog electronic circuit is designed to implement the new system，and the experimental results of the non-autonomous hyper-chaotic circuit well agreed with the simulation results.
Self-starting mode-locked Cr4+:YAG laser with Gires-Tournois interferometer mirror for dispersion compensation
Authors: Zhou Bin-Bin  , Zhang Wei  , Zhan Min-Jie  , Wei Zhi-Yi  ,   (1)北京大学物理学院，北京  100871; (2)中国科学院物理研究所光物理重点实验室，北京凝聚态物理国家实验室，北京  100080
Published: December 2020

A self-starting mode-locked Cr4+:YAG laser is reported, which incorporates a broadband SESAM and uses a piece of GTI mirror to compensate the intra-cavity group-delay dispersion. 65-fs pulses are generated at an average power of 95 mW with a 45 nm spectral bandwidth centered at 1508 nm under the pump power of 9 W.
Prediction of the crystallization temperature and crystallization driving force for Mg-Ni-Nd amorphous alloys
Authors: Wu Dong-Chang  , Huang Lin-Jun  , Liang Gong-Ying  ,   西安交通大学理学院材料物理系，西安  710049
Published: December 2020

A method for predicting the crystallization temperature and crystallization driving force of ternary amorphous alloys was provided. This method is an extension of the smallest-vacancy model suggested by Buschow for evaluating crystallization temperatures. The crystallization enthalpy and crystallization driving force are evaluated by using Miedema's semi-empirical model and the crystallization temperature is predicted. Calculation of the crystallization temperatures and enthalpy for (Mg70.6Ni29.4)1-xNdx(x＝5,10,15) amorphous alloys are performed by using this method. The calculated results accord well with experimental data and the relative error is less than 8% and 7% for crystallization temperature and crystallization enthalpy, respectively. It is found that with the increasing of crystallization driving force the retention rates of discharge capacity of Mg-Ni-Nd amorphous alloys decreases. For the (Mg70.6Ni29.4)1-xNdx(x＝1—20) amorphous alloys, the lowest crystallization driving force appears when the Nd content reaches 6.3%. That means (Mg70.6Ni29.4)93.7Nd6.3 amorphous alloy could have better retention rate of discharge capacity.
Piezoelectric properties and charge transport for fluorocarbon polymers with cellular structure
Authors: Zhang Xiao-Qing  , Huang Jin-Feng  , Wang Fei-Peng  , Xia Zhong-Fu  ,   同济大学波耳固体物理研究所，上海  200092
Published: December 2020

A new method for prepering piezoelectric polymer with cellular structure (piezoelectret) is introduced. Their piezoelectric activity and thermal stability are investigated for the fluorocarbon piezoelectret films produced in this method. The quasistatic piezoelectric d33 coefficients up to 2200pC/N are obtained for the fluorocarbon piezoelectret films; d33 coefficients are relatively independent on the applied pressure in the range of 20kPa; comparing to polypropylene piezoelectret film the new fluorocarbon films show not only higher values of d33，but also much better thermal stability; Furthermore，the thermal stability of the fluorocarbon piezoelectret film can be further improved by the process of pre-ageing. The enhanced thermal stability of d33 for such fluorocarbon films is due to the good thermal stability of charges in fluoroethylenepropylene (FEP) and polytetrafluoroethylene (PTFE)，and the dimension stability of such cellular structure. The charge recombination is mainly through the drifting of the detraped charges along the inside surfaces of the cavities when the films are thermally stimulated.
The light source, optical waveguide and light enhancement of nano-integrated optical circuit
Authors: Liu Dan  , Ma Ren-Min  , Wang Fei-Fei  , Zhang Zeng-Xing  , Zhang Zhen-Sheng  , Zhang Xue-Jin  , Wang Xiao  , Bai Yong-Qiang  , Zhu Xing  , Dai Lun  , Zhang Bei  ,   (1)北京大学物理学院,人工微结构与介观物理国家重点实验室,北京  100871; (2)北京大学物理学院,人工微结构与介观物理国家重点实验室,北京  100871；国家纳米科学中心,北京  100080; (3)中国科学院物理研究所,北京  100080
Published: December 2020

Scanning near-field microscopy (SNOM) was used to investigate the low-dimensional semiconductor fluorescence divices, which can work as micro-nano-light source, nano-optical waveguide and light enhancement component in nano-integrated optical circuit. It was found that the quality of semiconductor wire end emission was mainly determined by the sample radius. By designing the wire radius and topography reasonably, it can be used as the light source and optical waveguide in nano-integrated optical circuit. ZnO tetrapod, comb, and CdS multi-branch nano-ribbon also presented quite good adequacy for optical waveguide application, which can function well in light division, congregation, coupling and filtering. 2-D photonic crystal can enhance the light intensity of GaN based LED by as large as 5.2 times. About 30% fluorescence is confined to the surface of photonic crystal. This conclusion is helpful for the optimization of LED light emission. When the resonance excitation condition is fulfilled, Surface plasmm polaritons (SPP) will be excited at the interface between the semiconductor and the silver thin film, which will bring about strong enhancement of electromagnetic field at the interface. Photonic crystal and SPP can realize light enhancement under low_dimensional and nano-scale conditions. The experimental results show that both of them have the potential application as enhancement components in nano-integrated optical circuit.
Experimental research on the degree of clustering in Bi3+-Ga3+ co-doped high concentration Er3+-doped silica-based fiber
Authors: Chang De-Yuan  , Zheng Kai  , Wei Yan  , Li Bin  , Fu Yong-Jun  , Wei Huai  , Jian Shui-Sheng  ,   (1)全光网络与现代通信网教育部重点实验室，北京  100044; (2)全光网络与现代通信网教育部重点实验室，北京  100044；北京交通大学光波技术研究所，北京  100044
Published: December 2020

In order to obtain high-concentration doped erbium ions in silica-based fiber, we manufactured Er3+-Bi3+-Ga3+ co-doped fiber using MCVD and solution doping technique. The concentration of Er3+ in the fiber was about 5.24×1025/m3. We described a new method to measure the degree of clustering in the Er3+-Bi3+-Ga3+ co-doped fiber using fiber transmission experiment. Compared with other methods, the new method is simpler and more accurate. By the new method, the degree of clustering in Er3+-Bi3+-Ga3+ co-doped fiber was determined. It was shown that co-doped Bi3+-Ga3+ strongly increased the Er3+ solubility in the silica-based fiber.
Irregular spin tunneling for Bose-Einstein condensates in a sweeping magnetic field
Authors: Wang Guan-Fang  , Liu Hong  ,   (1)北京物资学院物流学院，北京  101149；北京物理所凝聚态物理国家实验室，北京  100080; (2)北京应用物理与计算数学研究所，北京  100088
Published: December 2020

With a mean-field treatment, the spin tunneling of spin-1 Bose-Einstein condensates in a linearly sweeping magnetic field is investigated. We focus on a typical alkali Bose atoms 87Rb condensate and study its tunneling dynamics under different sweeping rates of external magnetic field. In the adiabatic (i.e., slowly sweeping) and sudden (i.e., fast sweeping) limits, no tunneling is observed. In the case of moderate sweeping rates, the tunneling dynamics is found to be very sensitive to the sweeping rate, showing a chaotic-like tunneling regime. By magnifying the apparently chaotic regime, however, we find interestingly that the plot becomes resolvable at a resolution of 10-8T/s where the tunneling probability with respect to the sweeping rate shows a regular pseudo-periodic pattern. Moreover, a conserved quantity standing for the magnetization in experiments is found which can dramatically affect the above picture of the spin tunneling. Theoretically, we give a reasonable interpretation to the above findings.
A selective effect of dopamine on information-seeking
Authors: Vellani Valentina , de Vries Lianne P , Gaule Anne , Sharot Tali
Published: December 2020

Humans are motivated to seek information from their environment. How the brain motivates this behavior is unknown. One speculation is that the brain employs neuromodulatory systems implicated in primary reward-seeking, in particular dopamine, to instruct information-seeking. However, there has been no causal test for the role of dopamine in information-seeking. Here, we show that administration of a drug that enhances dopamine function (dihydroxy-L-phenylalanine; L-DOPA) reduces the impact of valence on information-seeking. Specifically, while participants under Placebo sought more information about potential gains than losses, under L-DOPA this difference was not observed. The results provide new insight into the neurobiology of information-seeking and generates the prediction that abnormal dopaminergic function (such as in Parkinson’s disease) will result in valence-dependent changes to information-seeking.
Calcium depletion challenges endoplasmic reticulum proteostasis by destabilising BiP-substrate complexes
Authors: Preissler Steffen , Rato Claudia , Yan Yahui , Perera Luke A , Czako Aron , Ron David
Published: December 2020

The metazoan endoplasmic reticulum (ER) serves both as a hub for maturation of secreted proteins and as an intracellular calcium storage compartment, facilitating calcium-release-dependent cellular processes. ER calcium depletion robustly activates the unfolded protein response (UPR). However, it is unclear how fluctuations in ER calcium impact organellar proteostasis. Here, we report that calcium selectively affects the dynamics of the abundant metazoan ER Hsp70 chaperone BiP, by enhancing its affinity for ADP. In the calcium-replete ER, ADP rebinding to post-ATP hydrolysis BiP-substrate complexes competes with ATP binding during both spontaneous and co-chaperone-assisted nucleotide exchange, favouring substrate retention. Conversely, in the calcium-depleted ER, relative acceleration of ADP-to-ATP exchange favours substrate release. These findings explain the rapid dissociation of certain substrates from BiP observed in the calcium-depleted ER and suggest a mechanism for tuning ER quality control and coupling UPR activity to signals that mobilise ER calcium in secretory cells.
The interplay between asymmetric and symmetric DNA loop extrusion
Authors: Banigan Edward J , Mirny Leonid A
Published: December 2020

Chromosome compaction is essential for reliable transmission of genetic information. Experiments suggest that ∼1000-fold compaction is driven by condensin complexes that extrude chromatin loops, by progressively collecting chromatin fiber from one or both sides of the complex to form a growing loop. Theory indicates that symmetric two-sided loop extrusion can achieve such compaction, but recent single-molecule studies (Golfier et al., 2020) observed diverse dynamics of condensins that perform one-sided, symmetric two-sided, and asymmetric two-sided extrusion. We use simulations and theory to determine how these molecular properties lead to chromosome compaction. High compaction can be achieved if even a small fraction of condensins have two essential properties: a long residence time and the ability to perform two-sided (not necessarily symmetric) extrusion. In mixtures of condensins I and II, coupling two-sided extrusion and stable chromatin binding by condensin II promotes compaction. These results provide missing connections between single-molecule observations and chromosome-scale organization.
Formulation of Stable Nanoliposomes of Docetaxel: Design, Optimization, and in-vitro Characterization
Authors: Harwalkar Mallappa S. , Salunkhe Kishor S. , Chavan Machindra J. , Chintamani Ravindra B. , Shendge Raosaheb Sopanrao
Published: December 2020

Background: Liposome offers many advantages over conventional dosage forms, like increased bioavailability, possibility of releasing drug at slower and constant rate, accurate drug release. Docetaxel is approved by the FDA for the treatment of locally advanced or metastatic breast cancer, head and neck cancer, gastric cancer. Docetaxel is BCS Class 4 drug; hence efficacy can be improved with liposomal formulation.

Objectives: The Present study prepared Docetaxel loaded liposomal formulation.

Materials and Methods: Formulation batches were designed on the basis of solvent, lipid to cholesterol ratio, lipid to release modifier ratio, hydration temperature and various physicochemical and morphological properties of formulation were examined. The zeta potential, particle size determination, pH, stability, determination of encapsulation efficacy, morphology of formulation and in-vitro drug release were investigated.

Results:  The zeta potential values of FD5 and FD9 were found to be -12.6 to -12.9 mV and -10.6 to -11.9 mV respectively. The entrapment efficiency of formulations of batch FD5 and FD9 were found to be 83.20% and 85.22% respectively. By comparing both FD5 and FD9 it was found that FD9 batch is optimized than FD5 in all aspects.  The formulation batch FD9 has particle size of 105 nm, zeta potential in range of -10.6 to -11.9 mV; Drug entrapment efficiency 85.22%, Assay of formulation was 99.56 % and FD9 formulation shows extended release of Drug up to 13 hours.

Conclusion: The study confirmed that the Liposome formulation was successfully prepared and evaluated.
Carbodicarbene Bismaalkene Cations: Unravelling the Complexities of Carbene versus Carbone in Heavy Pnictogen Chemistry
Authors: Walley Jacob E. , Warring Levi S. , Wang Guocang , Dickie Diane A. , Pan Sudip , Frenking Gernot , Gilliard Robert J.
Published: December 2020

We report a combined experimental and theoretical study on the first examples of carbodicarbene (CDC)‐stabilized bismuth complexes, which feature low‐coordinate cationic bismuth centers with C=Bi multiple‐bond character. Monocations [(CDC)Bi(Ph)Cl][SbF6] (8) and [(CDC)BiBr2(THF)2][SbF6] (11), dications [(CDC)Bi(Ph)][SbF6]2(9) and [(CDC)BiBr(THF)3][NTf2]2(12), and trication [(CDC)2Bi][NTf2]3(13) have been synthesized via sequential halide abstractions from (CDC)Bi(Ph)Cl2(7) and (CDC)BiBr3(10). Notably, the dications and trication exhibit CBi double dative bonds and thus represent unprecedented bismaalkene cations. The synthesis of these species highlights a unique non‐reductive route to C−Bi π‐bonding character. The CDC‐[Bi] complexes (7–13) were compared with related NHC‐[Bi] complexes (1,3–6) and show substantially different structural properties. Indeed, the CDC ligand has a remarkable influence on the overall stability of the resulting low‐coordinate Bi complexes, suggesting that CDC is a superior ligand to NHC in heavy pnictogen chemistry.