Researching | WLXB Volume 69 Issue 10,2020

D-brane interaction, the open string pair production and its enhancement plus its possible detection

Jian-Xin Lu, and Nan Zhang

This review article reports the recent studies, based on a series of publications by one of the present authors along with his collaborators, regarding the interaction between two D-branes, the open string pair production and its possible enhancement in Type II superstring theories. Specifically, computed is the intera

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 101101-1 (2020)

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Ions beam induced luminescence study of variation of defects in zinc oxide during ion implant and after annealing

Chang-Wei Luo, Meng-Lin Qiu, Guang-Fu Wang, Ting-Shun Wang, Guo-Qiang Zhao, and Qing-Song Hua

The optical and electrical properties of ZnO related on the type and the concentration of defects in ZnO crystal. Ion implantation and annealing can change the type and the concentration of defects in ZnO. To understand the variation of defects in ZnO during ion implantation and after different temperature annealing, i The optical and electrical properties of ZnO related on the type and the concentration of defects in ZnO crystal. Ion implantation and annealing can change the type and the concentration of defects in ZnO. To understand the variation of defects in ZnO during ion implantation and after different temperature annealing, in situ luminescence measurements of ZnO crystal samples were carried out by ion beam induced luminescence (IBIL) during ion implantation of 2 MeV H⁺ and then after annealing at 473 K and 800 K in vacuum on the GIC4117 tandem accelerator in Beijing Normal University. IBIL spectra of ZnO showtwo emission peaks: UV emission, which is called near band emission (NBE), and visible emission, which is called deep band emission (DBE).The high-intensity of DBE and weak NBE of IBIL spectra of ZnOmay be due to the NBE is intrinsic to ZnO samples and therefore is just visibly observed from samples that are virtually defect-free. With the ion implantation, the destruction of the crystal structure and the arising of a mass of defects, inducing the weak intensity NBE and intense DBE.In addition, the overall IBIL spectra of ZnOreveal decrease intensity with the ion fluence,which indicates that the concentration of luminescence centersdecreases duringion implantation.With the H⁺ fluence, the concentration of the point defects increases. The point defects migrate and subsequently agglomerate into larger defect clusters. These defect clusters serve as traps for catching electrons and holes, which result in the quenching of luminescence centres. Annealing can help todecompose the defect clusters and repair the defects of crystal. However, amounts of defects and clusters still remain in the irradiated sample annealed at 473 K in vacuum, which acted as nonradiative center and suppress the luminescence induced weak intensity of IBIL. Annealing the sample at 800 K in vacuum may facilitate the decomposition of defect clusters during ion irradiation to point defects and the point defect return to the lattice position that can reduce the nonequilibrium defects inside the crystal and improve the crystallinity of the crystal, which increase the intensity of its IBIL. .

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 102901-1 (2020)

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Corrosion and tribological properties of TiAlCN/TiAlN/TiAlcomposite system deposited by magneticfliter cathode vacuum arctechnique

Shu-Nian Chen, Bin Liao, Lin Chen, Zhi-Qiang Zhang, Yong-Qing Shen, Hao-Qi Wang, Pan Pang, Xian-Ying Wu, Qing-Song Hua, and Guang-Yu He

The experiment is based on novel magnetic filtered cathodic vacuum arc (FCVA) technology, the effects of the structure and C contents of TiAlCN/TiAlN/TiAl composite coating on anticorrosion and wear resistance were studied. The macro/micro properties of the coatings were systematically characterized by SEM, XRD, XPS, e

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 107202-1 (2020)

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In situ luminescence measurement from lithium fluoride under various ions

Meng-lin Qiu, Guo-qiang Zhao, Ting-shun Wang, Chang-wei Luo, Guang-fu Wang, Feng-shou Zhang, Sha-sha Lv, and Bin Liao

To contrast the generation and their evolution behaviors of irradiation damage in lithium fluoride under various ion, in situ luminescence measurements from lithium fluoride are carried out under 100 keV H+, He+ and O+ on the ion beam induced luminescence(IBIL) experimental setup on BNU400 ion implanter. Combined with

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 107801-1 (2020)

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Tribocorrosion performance of Nitrogen-doped diamond like carbon coating by high power impulse magnetron sputtering technique

Yong-Qing Shen, Zhi-Qiang Zhang, Bin Liao, Xian-Ying Wu, Xu Zhang, Qing-Song Hua, and Man-Yu Bao

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 108101-1 (2020)

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Thick yet tough TiN coatings deposited by filter cathode vacuum arc technology

Zhi-Qiang Zhang, Bin Liao, Yi-Xiang Ou, Feng-Shou Zhang, Xu Zhang, Yong-Qing Shen, Shu-Nian Chen, Qing-Song Hua, Guang-Yu He, and Xiao-Ping Ouyang

There are some high requirements for mechanical property to protective coatings of turbojet engine compressor blades as the appearance of extreme service conditions. The hard coating with high toughness, good adhesion, good wear resistance and excellent load carrying capacity is a potential coating for extreme service

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 108103-1 (2020)

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New advances in the research of stimulated emission depletion super-resolution microscopy

Jia-Lin Wang, Wei Yan, Jia Zhang, Lu-Wei Wang, Zhi-Gang Yang, and Jun-Le Qu

Due to the influence of the diffraction limit, the lateral spatial resolution and axial spatial resolution of traditional optical microscopes are limited to ~200 nm and ~500 nm, respectively. In the past two decades, with the rapid development of high-intensity lasers, high-sensitivity detectors and other optoelectroni Due to the influence of the diffraction limit, the lateral spatial resolution and axial spatial resolution of traditional optical microscopes are limited to ~200 nm and ~500 nm, respectively. In the past two decades, with the rapid development of high-intensity lasers, high-sensitivity detectors and other optoelectronic devices, there have been reported many super-resolution imaging techniques that bypass the optical diffraction limit with different methods. Among these techniques, stimulated emission depletion microscopy (STED) technology has the advantages of high imaging resolution and fast imaging speed. This technology uses two lasers for imaging, one of which is used to excite fluorescence, and the other donut-shaped depletion laser is used to suppress the emission of fluorescent molecules around the fluorescent spot, in order to reduce the fluorescence point spread function and achieve super resolution Imaging. After recent years of development, the STED system has got great progress no matter from the generation, calibration and scanning of the beam, and the final imaging. In terms of laser source, new laser sources such as continuous wave beams, supercontinuum laser, stimulated Raman scattered laser, and higher-order Bessel beams have appeared; in scanning and calibration, new efficiency technology such as parallel scanning and automatic calibration have also appeared; In imaging, new methods such as time gating and phasor analysis have emerged to improve imaging quality. These new technologies and methods are of great significance to improve the efficiency of STED system construction and imaging. In addition, this paper also focuses on the ways to expand the imaging functions of the STED system. First, for three-dimensional STED imaging, this paper mainly introduces three methods to realize three-dimensional STED imaging by wavefront non-coherent adjustment, 4Pi and structured light illumination methods. Second, for multi-color imaging, this paper introduces several dual-color and multi-color imaging techniques for special dyes. Third, this paper introduces the combination of STED technology with fluorescence correlation spectroscopy technology, cell expansion technology, scanning ion-conductance microscope, photo-activated localization microscopy/stochastic optical reconstruction microscopy and other technologies. Finally, this paper systematically discusses the new research progress of STED technology in recent years, and discusses the future development trend of STED technology..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 108702-1 (2020)

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Approximate method to evaluate the regional control efficacy of COVID-19

Ji-Peng Li, Feng Hong, Wei Bai, Jing-Yi Liao, Yan-Ru Zhang, and Tao Zhou

The cumulative number of local confirmed cases was highly correlated with the total inflow population from Wuhan before the city closure, and the proportion of third-generation infections in a local region is tiny. Accordingly, we proposed an approximate method to quantitatively evaluate the regional control efficacy o

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 100201-1 (2020)

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Three wires ring magnetic guide based on Archimedean spirals

Yun-Long Ling, Chuan Wang, and Hai-Chao Zhang

We propose a scheme to create a ring magnetic guide based on Archimedean spirals. This scheme is significant to obtaining large circle area for atom interference and the realization of guided atom-interferometer gyroscopes. Then the scheme can be used to realize an inertial sensing system which is independent of the GP We propose a scheme to create a ring magnetic guide based on Archimedean spirals. This scheme is significant to obtaining large circle area for atom interference and the realization of guided atom-interferometer gyroscopes. Then the scheme can be used to realize an inertial sensing system which is independent of the GPS system.The wires structure with

$ {\text{π}}/3$

rotational symmetry is composed of three wires. Each wire is centrosymmetric and consists of a pair of Archimedean spirals connected by two arcs. Consequently, the leading wire ends of the layout can be arranged separately in the different place of the layout plane. If the leading wire ends are put together somewhere, the closed ring guide cannot form and a gap appears in the guide due to the concentrated distribution of the leading wire ends. Since the leading wire ends distribute in the different location with

$ {\text{π}}/3$

rotational symmetry in our scheme, when direct currents are applied, the closed ring trap can be generated ingeniously. We calculate and analyze the magnetic field distribution generated by our structure after loading currents in the cylindrical coordinates system. To get higher sensitivity compared to GPS and make the ring trap locate in a proper height above the chip surface, we set the initial radius of Archimedean spirals

$ a=5\ {\rm{mm}}$

and the distance between neighboring spirals

$ d=0.1\ {\rm{mm}}$

. When three wires carry direct currents in an opposite current-phase-difference between the adjacent wires, a closed ring magnetic guide indeed appears but with six zero magnetic field points along the guide center. Because of the variation of the current density along r direction in Archimedean spirals, the magnetic field of the guide center is not zero at most angle. However, the variation cannot avoid the existence of zero points and the distribution of the zero points is determined by the rotational symmetry of the wires structure. Since atoms near the zero points of the magnetic field would be lost from the trap, the zero points must be removed from the center of the ring guide. Based on the time-orbiting-potential principle (TOP), we add an ac current modulation on the direct currents above to eliminate the influence of the zero points of the guide center. We give the ac current expressions and discuss the effects of currents parameters on the ring guide. The current phase reflects how the currents change in three wires. The modulation depth determines the effect of the modulation: if the modulation depth is too high, the trap may disappear; if the modulation depth is too low, the effect is minimal. The modulation frequency reflects the change rate of the modulation magnetic field.To ensure the smoothness of the guide along angular direction and adiabatic following of the magnetic field, we set the modulation depth

$ I_j/I_i=0.1$

, the current-phase

$ \phi=2{\text{π}}/3$

and the modulation frequency

$ \omega_b=2{\text{π}}\times10\ {\rm{kHz}}$

. The numerical calculation results indicate that ac current modulation can change the magnetic field intensity of the guide center and smooth the variance of the magnetic field intensity of the guide along angular direction. We take the cross section of the guide with

$ \theta={\text{π}}/2$

, for example. The minimum of the instantaneous magnetic field rotates and our structure has formed a TOP trap in both the r and z directions. In angular direction, the magnetic field intensity of the guide center changes near

$ 0.25\ {\rm{mT}}$

. The difference between the maximum and the minimum is

$ \Delta\,B\approx0.007\ {\rm{mT}}$

which is small enough compared to applying direct current only. Therefore, based on the Archimedean spirals and ac current modulation, we obtain an enclosed and smooth ring magnetic guide without zero magnetic fields along the guide center for neutral atoms. The location of the guide center also changes along the angle direction. The amplitudes of variation along r and z directions are

$ \Delta r=0.015\ {\rm{mm}}$

,

$ \Delta z=0.005\ {\rm{mm}}$

, which are

$ \Delta r/l\approx0.3\,\%$

,

$ \Delta z/l\approx0.1\,\%$

compared with

$ l\approx2{\text{π}} a/6\approx5.236\ {\rm{mm}}$

. Compared to other schemes, our structure can be etched on an atom chip and is easily to apply modulation currents, which is simple and stable to form a ring magnetic guide. This scheme can be used to realize a compact, low power and stable inertial sensor based on atom-chip gyroscope device..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 100301-1 (2020)

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Investigation of NO content varaitaion in the lymphatic vessels under different outlet pressures by a lattice Boltzmann method

Yi-Nan He, Qian-Yi Zhang, Hua-Jian Wei, and Juan Shi

The lymphatic system is an important defense function system in the human body. It is also critical to humoral homeostasis. Local dysfunction will cause edema, immune deficiency, and a high incidence. There are intraluminal valves in the lymphatic system, which allows the lymph fluid to flow to the large veins and hear The lymphatic system is an important defense function system in the human body. It is also critical to humoral homeostasis. Local dysfunction will cause edema, immune deficiency, and a high incidence. There are intraluminal valves in the lymphatic system, which allows the lymph fluid to flow to the large veins and heart. It has three major immune functions. First, it can resist bacterial viruses and protect the human body from disease attacks. Secondly, it is supplemented by lymphocytes to remove the products produced by metabolism. In the end, The damaged organs and tissues are repaired by lymphocytes to restore normal physiological functions. The lymphatic system does not have the same pump as the heart of the blood circulatory system. The driving of lymph is mainly done by the spontaneous contraction of the lymphatics (the lung lymphatic system is compressed by the alveoli). The autonomic contraction cycle of lymphatic vessels is caused by the increase of Ca²⁺ in lymphocytes, and the contraction drives the fluid to produce shearing force. The shearing force produces nitric oxide synthase (eNOS) in lymphatic endothelial cells, and eNOS increases NO and increases NO. Decreasing Ca²⁺ relaxes lymphatic vessels, fluid shear rate decreases after lymphatic vessel relaxation, eNOS decreases, NO decreases, Ca²⁺ increases, lymphocytes contract, and a new cycle begins. It can be seen that the concentration of NO and its distribution play a key role in the contraction of lymphatic vessels. Obviously, export pressure affects the shear rate of fluid in the lymphatics, which in turn affects the concentration of NO and the contraction of lymphatic vessels. To investigate the effect of lymphatic outlet pressure on lymphatic vessel contraction, we established a lattice Boltzmann model to simulate the initial lymphatic vessels embedded in porous tissue and the collecting lymphatic vessels with two pairs of valves. The valve is the main source of NO. Once contraction begins, the contraction is spontaneous, self-sustaining, and the system exhibits non-linear dynamics. This model can reproduce NO and The interaction of Ca²⁺ and the spontaneous contraction of lymphatic vessels, and the distribution of NO under different outlet pressures and their average values were studied..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 100501-1 (2020)

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Nonequilibrium statistical theoretical analysis method of TDDB of gate oxide

Wen-Jing Zhao, Meng-Guang Ding, Xiao-Li Yang, and Hai-Yun Hu

As one of the important factors affecting the reliability of Complementary metal oxide semiconductor integrated circuits, the time-dependent dielectric breakdown of gate oxide has always been the focus of domestic and foreign scientists. The previous researches have shown that when the electrons pass through the silico As one of the important factors affecting the reliability of Complementary metal oxide semiconductor integrated circuits, the time-dependent dielectric breakdown of gate oxide has always been the focus of domestic and foreign scientists. The previous researches have shown that when the electrons pass through the silicon dioxide lattice and collide with it, part of their kinetic energy will be dissipated, then among of which can create some sort of defects that behave as electron traps. However, when the electron traps density reaches a critical value in the gate oxide, the destructive thermal effects open a low-resistance ohmic path between the electrodes, thus, triggering the breakdown conducting mechanism. In this paper, in order to employing a statistical theoretical analysis method, the behavior related with time-dependent dielectric breakdown of gate oxide was investigated in detail. The following useful results are obtained, (i) According to the microscopic mechanism of the time-dependent dielectric breakdown of gate oxide under electrical stresses associated with the randomness and irreversibility of the electron traps generation in gate oxide, a theoretical analysis method has been proposed, which is based on the equation of the electron traps generation rate combined with the Langevin equation in random theory and the Fokker-Planck equation in the non-equilibrium statistical theory. (ii) In light of the dynamic equilibrium model, the generation rate equations of electron traps under constant current stress and constant voltage stress as well as the probability density distribution functions of electron traps density were determined. By integrating these distribution function, the cumulative failure rate was further obtained. (iii) Taking the specific metal oxide semiconductor capacitors as examples, the relationship between the most probable lifetime of the gate oxide and the constant current stress, constant voltage stress, as well as its thickness have been revealed. And the concept of "breakdown limit" was defined by analogy with the concept of "fatigue limit" in the phenomenon of solid fracture. (iv) The dependence of the cumulative failure rate on the current stress, voltage stress, and time has been presented. A characteristic value of the time was introduced to indicate the time when the cumulative failure rate reaches 0.63. At this time, most devices have breakdown failure. Besides, the test parameters are not affected by previous failures, and they are close to that of the cumulative failure rate of 1. The results show that the probability density distribution function of electron traps density satisfies lognormal distribution, and the obtained distribution of failures fits well with the experimental statistical data..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 100502-1 (2020)

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Investigation on the directional transportation of coupled Brownian motors with asymmetric friction

Xu Zhang, Jia-Hui Cao, Bao-Quan Ai, Tian-Fu Gao, and Zhi-Gang Zheng

Biological molecular motors exist in cells widely. They can make use of intracellular free energy to complete all kinds of internal biological transports by transforming chemical energy into mechanical energy. The kind of directional movement of biological molecular motors plays a very important role in intracellular m Biological molecular motors exist in cells widely. They can make use of intracellular free energy to complete all kinds of internal biological transports by transforming chemical energy into mechanical energy. The kind of directional movement of biological molecular motors plays a very important role in intracellular material transportation. In order to study the transport mechanism of molecular motors further, a large number of ratchet models are proposed, such as rocking ratchets and flashing ratchets. By investigating various kinds of ratchets we can not only understand the directional movement mechanism of Brownian particles, but can find suitable conditions in which the performance of Brownian motors’ directional transportation could be enhanced. Meanwhile, the investigation of ratchets could also be applied in manufacturing nanometer devices.At present, the directional transportation of Brownian ratchet has attracted extensive interests of researchers. In general, most friction factors of Brownian ratchet models are considered unit. In fact, the concentration of solutions and cell fluid impurity affect the actual frictional damping conditions, so the real frictional coefficient of Brownian motors is often changed. In addition, lots of experimental studies have shown that the movement of Brownian motors is collectively directed motion and the kind of directional movement is induced by intermolecular coupling interaction. As a result, it is more valuable to investigate the transporting performance of coupled Brownian particles that existed in different frictional damping conditions. In order to enhance the transporting performance of Brownian ratchet in different frictional damping conditions, we discuss how the frictional damping factor influences the directional movement of coupled Brownian particles deeply when Brownian particles drag loads.In this paper, we established the overdamped frictional ratchets, and then we investigated how frictional damping coefficient ratio, coupling strength and external force amplitude affect the transportation of coupled Brownian ratchets. On the basis of the investigation, some interesting results are found. The directional transport of frictional ratchets can be promoted by adjusting the frictional damping factor. Besides, the transportation can obtain the maximum under the appropriate friction factor case. In addition, under certain frictional damping condition, the directional transportation of the friction ratchets present multi-peak structure as the external force amplitude increases. Meanwhile, the appropriate free length and coupling strength can also enhance the transportation characteristic of frictional ratchets. All conclusions obtained in this paper can not be applied in selecting suitable frictional damping conditions experimentally to improve the directional transportation of coupled Brownian ratchets, but they can also be used in developing and manufacturing nanometer devices..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 100503-1 (2020)

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Generation of 8 Gb/s physical random numbers based on spontaneous chaotic oscillation of GaAs/Al_0.45Ga_0.55As superlattices

Yan-Fei Liu, Cheng Chen, Dong-Dong Yang, and Xiu-Jian Li

Secret key is required in secure communications, and random numbers are generally used as keys to encrypt the original information. So it is crucial for cryptography and secure communication to generate the physical random number, which is completely safer than pseudo random number. However, Existing physical random nu

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 100504-1 (2020)

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A hybrid model for photovoltaic power prediction of both convolutional and long short-term memory neural networks optimized by genetic algorithm

Chen-Yang Wang, Qian-Qian Duan, Kai Zhou, Jing Yao, Min Su, Yi-Chao Fu, Jun-Yang Ji, Xin Hong, Xue-Qin Liu, and Zhi-Yong Wang

Photovoltaic power generation is affected by weather and geographical environment, showing fluctuations and random multi-interference, and its output power is easy to change with changes in external factors. Therefore, the prediction of output power is crucial to optimize the grid-connected operation of photovoltaic po

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 100701-1 (2020)

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Study on the ground state properties and excitation properties of C₁₈ under different external electric fields

Shi-Xiong Li, De-Liang Chen, Zheng-Ping Zhang, Zheng-Wen Long, and Shui-Jie Qin

In this work, density functional theory method with the ωB97XD/def2-TZVP level is carried out to investigate the ground state structures, energy, electronic structures, aromaticity, infrared and Raman spectra of cyclo[18]carbon under different external electric field in the x, y and z direction of cyclo[18]carbon molec In this work, density functional theory method with the ωB97XD/def2-TZVP level is carried out to investigate the ground state structures, energy, electronic structures, aromaticity, infrared and Raman spectra of cyclo[18]carbon under different external electric field in the x, y and z direction of cyclo[18]carbon molecule. The excitation properties (the first 48 excited states containing excited energies, excited wavelengths and oscillator strengths) of cyclo[18]carbon are calculated by the time-dependent density functional theory method (TD-ωB97XD) with the def2-TZVP basis set under the same external electric field. The results show that cyclo[18]carbon can be elongated in thex or y direction under the electric field, and some C-C bond lengths can be elongated or shortened under the electric field. Meanwhile, the calculated results show that electric dipole moment is proved to be increasing with the increase of the external field intensity, but the total energy and LUMO-HOMO gap are proved to decrease with the increase of external field intensity. Moreover, addition of electric field can modify the electron delocalization and molecular aromaticity, such as external electric field in z direction can lower the electron delocalization and molecular aromaticity and external electric field in x or y direction can enhance the electron delocalization and molecular aromaticity. The addition of electric field can modify the infrared spectra, such as shift of vibrational frequencies and strengthening of infrared peaks. Furthermore, the calculated results indicate that the external electric field has significant effects on the excitation properties of cyclo[18]carbon. The increase of the electric field intensity can lead to the redshift of transition wavelengths (such as the first excited state). With the change of the electric field intensity, the stronger excited state (with the bigger oscillator strength) can become weak (with the small oscillator strength) or optically inactive (with the oscillator strength of zero). Meanwhile, the weak or optically inactive excited state can become stronger excited state by the external field. The ground state properties and excitation properties of cyclo[18]carbon can be modified by the external electric field. Our works can provide theoretical guidance for the application of cyclo[18]carbon in the nanotechnology such as molecular device..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 103101-1 (2020)

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Intersystem crossing of 2-Methlypyrazine studied by femtosecond photoelectron imaging

Abulimiti Bumaliya, Feng-Zi Ling, Xu-Lan Deng, Jie Wei, Xin-Li Song, Mei Xiang, and Bing Zhang

The ultrafast nonadibatic relaxation dynamics of the excited state of 2-methylpyrazine has been studied by using femtosecond time-resolved photoelectron imaging and femtosecond time-resolved mass spectrometry. The first excited state S1 of 2-methylpyrazine was excited by 323 nm pump light, and the excited state deactiv

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 103301-1 (2020)

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Characteristics of multi-crystals monfiguration X-ray diffraction and application in characterizing synchrotron beamline bandwidth

Jun-Liang Yang, Zhong-Liang Li, Tang Li, Ye Zhu, Li Song, Lian Xue, and Xiao-Wei Zhang

In this paper, the X-ray diffraction experiment with multiple crystals configuration and its application in characterizing the emission characteristics of double crystal monochromator (DCM) on BL09 beamline of Shanghai Synchrotron Radiation Facility (SSRF) are reported. It is a non-dispersion configuration when the sec In this paper, the X-ray diffraction experiment with multiple crystals configuration and its application in characterizing the emission characteristics of double crystal monochromator (DCM) on BL09 beamline of Shanghai Synchrotron Radiation Facility (SSRF) are reported. It is a non-dispersion configuration when the second crystal of DCM and the crystal analyzer form a (+n, –n) type experimental configuration. The rocking curve of the analyzer crystal can only reflect the operation of the DCM. It is the dispersion configurations when the second crystal of DCM and the crystal analyzer form the (+n, +n), (+n, –m) and (+n, +m) type experimental configuration. The width of the analyzer crystal rocking curve includes not only the intrinsic bandwidth of the DCM and the analyzer crystal, but also the angular divergence of the beamline. In this paper, we use the method of DuMond diagram to explicitly illustrate the characteristics of the output beam of the DCM which can be measured under the above two kinds of experimental configurations, and distinguish the diffraction characteristics of different experimental configurations at the same time. Finally, the angular bandwidth and the relative energy bandwidth of the DCM are 5.40(4) arcsec and1.30(1) × 10^–4 @ 10 keV, respectively, which are obtained by deconvolution of the analyzer crystal in (+1, –1) nondispersive configuration. The angular distribution and the relative energy bandwidth of the synchrotron radiation beams are 26(1) arcsec and 6.3(2) × 10^–4 @ 10 keV, respectively, which are obtained by deconvolution of the analyzer crystal and removal of dispersion broadening in (+1, +1), (+1, –3) and (+1, +3) dispersion configuration. After removing the influence of the DCM, the obtained angular divergence of the light source by 25(1) arcsec @ 10 keV, is consistent with the theoretical value of the bending source. In addition, under a series of different white beam entrance slit widths, we characterize the divergence and bandwidth of the beam emitted from the monochromator by the method of multi-crystals dispersion configuration and the DuMond diagram..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 104101-1 (2020)

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Maximum ceasing angle of inclination andflux formula for granular orifice flow in water

Wen-Tao Xie, Ruo-Ru Li, Zheng Peng, and Yi-Min Jiang

In previous work [Acta Phys. Sin. 60 054501 (2011)], we found that for inclined Granular Orifice Flow (GOF) in air, regardless of the orifice size, the flow rate Q had a good linear relationship with the cosine of the inclination $\cos \theta $, i.e. $\dfrac{Q}{{{Q_0}}} = 1 - \dfrac{{\cos \theta - 1}}{{\cos {\theta _{\

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 104501-1 (2020)

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Controllable nano-friction of graphene surface by fabricating nanoscale patterning based on atomic force microscopy

Yu-Xiang Zhang, Yi-Tian Peng, and Hao-Jie Lang

Friction-controlled graphene has great potential as a solid lubricant in micro/nano electromechanical systems. In this work, the conductive atomic force microscope was used to conduct oxidation etching on the graphene surface to produce different nanoscale patterns. The frictional properties of graphene nanoscale patte

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 106801-1 (2020)

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First-principles study on effect of Re on micro structure and mechanical properties of Ni₃Al intermetallics

Xue-Lan Hu, Rui-Zhi Lu, Zhi-Long Wang, and Ya-Ru Wang

The effects of Re on the microstructure and mechanical properties of $ {\gamma '}$ phase Ni3Al intermetallics are investigated by using first-principles method based on density functional theory and generalized gradient approximation. It shows that in most stoichiometric ranges, the dissolution energy of Re replaci The effects of Re on the microstructure and mechanical properties of

$ {\gamma '}$

phase Ni₃Al intermetallics are investigated by using first-principles method based on density functional theory and generalized gradient approximation. It shows that in most stoichiometric ranges, the dissolution energy of Re replacing Al site is smaller than that of Re replacing Ni site. That means the energetically-favorable site of Re in Ni₃Al is Al replace site. We further investigate the interaction between two Re atoms in Ni₃Al. The larger the distance between two Re atoms, the more stable the system becomes, showing that Re atoms are dispersed in Ni₃Al instead of being aggregated. Re doping causes a small increase in the lattice constant of Ni₃Al intermetallics without causing serious lattice deformation. Analyses on differential charge density and state density show that Re atom bonds with neighboring atoms, especially with Ni atoms, and reduces the surrounding Ni—Al bond energy. Analyses on local state density show that Re atom has orbital interaction with the neighboring Ni and Al atoms, and the interaction with Ni is larger, which concerns the 5d orbit of Re and the 3d orbit of Ni. The effect of Re on the mechanical properties of Ni₃Al intermetallics is also investigated. The elastic constants calculating results together with empirical criteria indicate the presence of Re atom (corresponding concentration is 0.93%) can cause increase of the stiffness and hardness of Ni₃Al. The Cauchy pressure value shows a slight improvement in toughness. The increase of Re doping concentration (the concentration of Re in Ni₃Al is 1.85%) can cause increase of the lattice constant, stiffness and hardness and decrease of the ductility of Ni₃Al. In order to correct the temperature of the results obtained by first-principles method, the influence of temperature on the mechanical properties of Ni₃Al has been further investigated through Phonopy calculation. The influence of temperature on the coefficient of thermal expansion and bulk modulus of elasticity is obtained by quasi harmonic approximation. The results show that the addition of Re slightly enhances the entropy of Ni₃Al, but causes decrease of its Helmholtz free energy on a small extent. At high temperature, doping of Re greatly strengthens the bulk modulus of Ni₃Al but decreases the thermal expansion coefficient of which. Results of the current research can provide theoretical data for improving the mechanical properties of single crystal turbine blades of aero-engines..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 107101-1 (2020)

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Light-field assisted spin-polarized transport properties in magnetic-electric barrier structures

Chun-Lei Li, Yan Xu, Jun Zheng, Xiao-Ming Wang, Rui-Yang Yuan, and Yong Guo

Based on the Floquet theory and transfer-matrix method, We investigated the influence of light-field on the spin-polarized transport properties for electrons tunneling through two kinds of magnetic-electric barrier structures (the $\delta$-doped magnetic-barrier can be realized in experiments by depositing two ferromag

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 107201-1 (2020)

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Effect of biquadratic exchange and anisotropy on the critical temperature of antiferromagnet

Lin Wen, and Ai-Yuan Hu

The existence of biquadratic exchange had been well established by Anderson, Huang and Allen. Early investigations indicated that the biquadratic exchange term in spin Hamiltonian was found to have significant effects on the magnetic properties of compounds containing iron-group ions or rare-earth metal ions. Recently,The existence of biquadratic exchange had been well established by Anderson, Huang and Allen. Early investigations indicated that the biquadratic exchange term in spin Hamiltonian was found to have significant effects on the magnetic properties of compounds containing iron-group ions or rare-earth metal ions. Recently, studying the anisotropic magnetic excitation of iron-based superconducting materials indicated that the experimental phenomenon cannot be explained well only by a simple collinear Heisenberg antiferromagnetic model. However, if the nearest neighbor biquadratic spin coupling is introduced, the experiment can be well explained. Similar results had also been obtained in the investigation of the superconducting material FeSe. As a result, exploring the effect of biquadratic exchange interactions on the magnetic properties of magnetic systems is significance. In this paper, we use the double-time Green's function method to study the properties of the spin-1 Heisenberg antiferromagnets with biquadratic exchange interactions and anisotropy on a three-dimensional lattice. We derive the equation of motion of the Green's function by a standard procedure. In the course of this, the higher order Green functions have to be decoupled. For the higher order Green functions of different lattice points, a Tyablikov or random phase approximation decoupling are used to decuple. For the higher order Green functions of the same lattice points, we adopt the Anderson-Callen decoupling to decouple. Based on the above procedures, the analytic expressions of the magnetization and critical temperature are obtained. The effects of biquadratic exchange interactions and anisotropy on the critical temperature are discussed in detailed. Our results show that the critical temperature increases with the increase of the anisotropy for a given biquadratic interaction. Regardless of the value of the anisotropy, the critical temperature always decreases with the increase of the biquadratic interaction. As the value of anisotropic parameter

$\eta = 0$

, there is an obvious linear relationship between the critical temperature and the biquadratic interaction. However, when the anisotropy of the system becomes weaker, there is no such linear relationship between them. By comparing similar ferromagnetic models, it is found that the results of this paper are significantly different from those of the ferromagnetic model. When the biquadratic interaction is equal to 0, our results agree with other theoretical results..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 107501-1 (2020)

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Effect of Gd doping on the structure, dielectric and multiferroic properties of 0.7BiFe_0.95Ga_0.05O₃-0.3BaTiO₃ceramics

Ru-Xia Yang, Yu-Ming Lu, Li-Zhu Zeng, Lu-Jia Zhang, and Guan-Nan Li

The 0.7Bi1–xGdxFe0.95Ga0.05O3-0.3BaTiO3 (BGxFG-BT, x = 0, 0.05, 0.1, 0.15, 0.2) ceramics were successfully synthesized via the conventional solid-state reaction method. The effects of Gd doping on crystal structure, microstructure, dielectric, ferroelectric and magnetic properties were systematically investigated. X-ra

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 107701-1 (2020)

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Studies of circular dichroism of planar composite metal nanostructure arrays

Aba Tudahong, Yu Qu, Jun-Ran Bai, and Zhong-Yue Zhang

Circular dichroism effects have been widely used in circular polarizers, optical modulators and optoelectronic devices. Periodically arranged artificial metal chiral nanostructures has a strong electromagnetic coupling effect with light, which can greatly increase the interaction between the light and matter. Three-dim Circular dichroism effects have been widely used in circular polarizers, optical modulators and optoelectronic devices. Periodically arranged artificial metal chiral nanostructures has a strong electromagnetic coupling effect with light, which can greatly increase the interaction between the light and matter. Three-dimensional helix and helix-like chiral nanostructures show a larger circular dichroism effect due to the strong interactions between electric and magnetic resonance. The double-layer structures also can produce large circular dichroism, which signals also results from electric dipoles with different orientations between the two layers. Although the three dimensional plasmonic structures have shown large circular dichroism signals, however, three dimensional devices hold disadvantages in wide practical applications because of their complicated fabricating process, especially at micro- and nanoscales. Recent years, circular dichroism signals of planar nanostructures have been studied owing to their easy fabrication and wide potential applications. The resonance mode of planar metal nanostructures is sensitive to the shape, geometry, materials and surrounding environment of nanostructures, which provides a feasible technical approach for adjusting the circular dichroism signal of planar metal nanostructures. In this article, larger circular dichroism signals are realized through planar composite golden nanostructures, which composed of infinite long nanowire and G-shaped nanostructure. The absorption spectra, surface charge distributions at resonance wavelength of planar composite golden nanostructure are calculated by finite element method. For comparison, a circular dichroism signal with only G-shaped nanostructures is also studied. The numerical results show that under the illumination of right-handed polarized and left-handed polarized light, the planar composite golden nanostructure and G-shaped nanostructure exhibit electric dipole, quadrupolar, octupolar resonance modes, respectively. When the G-shaped nanostructure is connected to an infinitely long nanowire, all resonance peaks have a red shift and infinitely long nanowire increases the local surface resonance intensity under different circularly polarized light excitation. Therefore, it significantly enhances the circular dichroism signal of the planar composite golden nanostructure. At the same time, the influence of geometric parameters such as the different length of each nanorod of the G-shaped nanostructure and the thickness of the infinitely length nanowire on the circular dichroism modes are also studied. The findings may provide some guideline and methods for improving the circular dichroism signal of planar chiral nanostructure..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 107802-1 (2020)

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Size Regulation and Photoluminescence Properties of β-Ga₂O₃ Nanomaterials

Teng-Yu Ma, Wan-Jun Li, Xian-Wang He, Hui Hu, Li-Juan Huang, Hong Zhang, Yuan-Qiang Xiong, Hong-Lin Li, Li-Juan Ye, and Chun-Yang Kong

Gallium oxide (Ga2O3) nanomaterials have great potential in the fields of ultraviolet transparent electrodes, high-temperature gas sensors, solar blind ultraviolet detectors and power devices, while achieving Ga2O3 nanomaterials with high crystalline quality and controllable size and morphology still remains challenge.

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 108102-1 (2020)

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Ge Schottky diode for improving energy conversion efficiency of the receiver of microwave wireless power transfer

Yu-Chen Li, Hang-Yu Chen, and Jian-Jun Song

Microwave wireless power transfer(MWPT) can break through the restriction of transmission line to transmit electrical energy, which is conducive to dealing with power supply in complex scenarios, and has a very large application prospect. Energy conversion efficiency is an important parameter of MWPT. Hence, researcher Microwave wireless power transfer(MWPT) can break through the restriction of transmission line to transmit electrical energy, which is conducive to dealing with power supply in complex scenarios, and has a very large application prospect. Energy conversion efficiency is an important parameter of MWPT. Hence, researchers are focus on improving the conversion efficiency of MWPT from different ways. Schottky diode is the core component of the rectifier circuit, which determines the limit of the energy conversion efficiency. However, the research involving the design of Schottky diode has rarely reported. In this paper, a GeOI folded space charge region Schottky diode is proposed. The space charge region of the proposed Schottky diode is composed of two parts: the vertical space charge region and the horizontal space charge region. So the capacitor is also divided into two parts, namely the vertical capacitor and the lateral capacitor. In the device model, these two capacitors are in series. So the total capacitance will be reduced. This article establishes its capacitance model and completes the optimization of device material parameters and structure parameters. The designed device parameters are as follows: the doping concentration of the heavily doped buffer layer on the left side of the Ge material is 2 × 10²⁰ cm^–3 to form Ohm contact, the doping concentration of the lightly doped region on the right side is 3.8 × 10¹⁷ cm^–3, the thickness of the folded region is 0.2 μm, the Schottky metal is Wu, the width of metal is 8 μm, and the length of metal is 2 μm. We use the proposed Schottky diode as the core rectifier to simulate the rectifier circuit by using ADS, in which the SPICE parameters of the proposed Schottky diode was extract using Cadence Model Editor. When the input energy is 24.5 dBm, the energy conversion efficiency reached 75.4%. Compared with the conventional schottky diode, the energy conversion efficiency is significantly improved. The study of the proposed Schottky diodes can provide valuable reference for improving the energy conversion efficiency of microwave wireless energy transmission..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 108401-1 (2020)

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The electron emission characteristics of GaAs photocathode with vacuum-channel structure

Guang-Hui Hao, Pan-Yang Han, Xing-Hui Li, Ze-Peng Li, and Yu-Juan Gao

The photocathode was an ideal electronic source with fast response, centralized distribution of electronic capabilities, and many other advantages. But for its low emission current density and short lifetime at ion bombardment environment, it will not be used in power devices and large scientific devices. Although the The photocathode was an ideal electronic source with fast response, centralized distribution of electronic capabilities, and many other advantages. But for its low emission current density and short lifetime at ion bombardment environment, it will not be used in power devices and large scientific devices. Although the emission current of the photocathode can be increased with the aid of electric filed, it was not reach the milliamperelevel. In the field emission cathode, the strong electric field can effectively reduce the surface barrier of the emitter, so that the cathode produces electron emission. Based on the photoelectric conversion mechanism of photocathode and the electron emission theory of field emission cathode, a vacuum channel structure photocathode module is designed. The cathode modules with GaAs substrate were fabricated by the peritoneal and etching process. The parameters of vacuum channel were 3 μm × 700 μm, and its array structure was 1 × 100. The deep of the vacuum channels were 400 nm. It can be seen from the test result, the emission current of the photocathode was 26.12 mA with the laser beam power 5 W, and its emission current density was 5.33 A/cm². During cathode operation, the laser beam and emission will cause the temperature of the photocathode material to rise, and this could icreasing the conductivity of the GaAs, the efficiency of electron supplement from negative electrode to electron emission area of the GaAs will also be improving. Its emission current could reach 89.69 mA at 400 ℃. Because there is no active atom on the photocathode surface, its lifetime was longer than the traditional photocathode that astivated by Cs/O. The life test of the photocathode modules was carried out, its emission current was 4.5 mA ± 0.3 mA within the 144 h, and its performance was not attenuate significantly. The vacuum channel was the main area of the photocatode electron emission, and the shape of electron beam can be easily obtained by adjusting the structure of the vacuum channel parameters. This advantage can improve the applicability of high current density photocathode in vacuum electronic devices and equipment..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 108501-1 (2020)

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Single molecular kinetics during the interactions between melittin and a bi-component lipid membrane

Cheng Xu, Zhao Lin, Kai Yang, and Bing Yuan

Due to the unique bacterial killing ability through membrane permeabilization and content leakage, antimicrobial peptides (AMPs) have been regarded as promising candidates against the severe threats of drug-resistant bacteria and even superbugs to public health. However, investigations of the mechanism underlying their

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 108701-1 (2020)

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Study of multiscale entropy model to evaluate the cognitive behavior of healthy elderly people based on resting state functional magnetic resonance imaging

Fu-Yi Zhang, Man-Ling Ge, Zhi-Tong Guo, Chong Xie, Ze-Kun Yang, and Zi-Bo Song

At present, resting state functional magnetic resonance imaging (rfMRI) has provided an efficient, rapid and advanced technology for brain function detection. Entropy can capture the dynamic characteristics of neural signals and might be used as a quantitative evaluation parameter. However, there are some problems rema At present, resting state functional magnetic resonance imaging (rfMRI) has provided an efficient, rapid and advanced technology for brain function detection. Entropy can capture the dynamic characteristics of neural signals and might be used as a quantitative evaluation parameter. However, there are some problems remain solved yet, such as the entropy model computing with a fixed scale, and whether the entropy model could evaluate the cognitive performance.These problems will affect the accuracy of detection. Therefore, the multi-scale entropy model combined with a machine learning method is proposed here to investigate the relationship between complexity derived from BOLD signal and cognitive score of healthy elderly people, so as to some new imaging biomarkers could be illuminate by rfMRI. A total of 98 healthy old volunteers were selected and divided into two groups according to the pre-scan scores for the cognitive questions test (regarded as cognitive performance here): excellent group and poor group. Firstly, the multi-scale entropy model was constructed, the entropy of scanning data was calculated in two groups, and the parameters of the model were optimized by statistics and comparison with the help machine learning method. Secondly, the eigenvectors were constructed by the entropy values of the indicative brain areas with high statistical significance under the optimized parameters of multi-scale model. Finally, the sample data were divided into either training set or testing set, in which 78 people were randomly included in the training set and the rest of 20 people were included in the testing set. The two groups of data were classified and tested by the extreme learning machine. It was found that there was a significant difference between the frontal and temporal regions in the assessment of cognitive scores of the elderly by the multi-scale entropy model based on rfMRI, and the sorting rate for the cognitive scores could reach up to 80%. Conclusion: the optimized multi-scale entropy model can effectively distinguish the cognitive scores of healthy elderly people at the frontal lobe, temporal lobe and other marker brain regions. This study has highlighted the optimization advantage of the multi-scale entropy model with the help of machine learning, and might provide a new detection parameter and a potential method for rfMRI to replace the subjective and tedious traditional cognitive scale form tests..

Acta Physica Sinica

Publication Date: Jan. 01, 1900
Vol. 69, Issue 10, 108703-1 (2020)

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