bluuebunny/crossref_metadata_2025 huggingface dataset:
Near-field character and improvement technology of induced spatial incoherence
Authors: Li Fu-Jian  , Gao Yan-Qi  , Zhao Xiao-Hui  , Ji Lai-Lin  , Wang Wei  , Huang Xiu-Guang  , Ma Wei-Xin  , Sui Zhan  , Pei Wen-Bing  ,   Shanghai Institute of Laser Plasma, China Academy of Engineering Physics, Shanghai 201800, China;,   National Laboratory on High Power Laser and Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China;,   Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

Induced spatial incoherence technology is a beam-smoothing method with its own unique advantages for laser driven inertial confinement fusion. However, simply using the induced spatial incoherent method will induce a strong near-field intensity spatial modulation, which will threaten the safety of the operation and severely limit the maximum output capability of the device. This is also one of the main technical obstacles to applying induced spatial incoherence to a high-power laser device used for fusion. In this paper, a technique of smoothing the near-field spatial intensity modulation caused by induced spatial incoherence is introduced. By using a two-lens filter system, a homogeneous and stable near-field intensity distribution can be obtained on the premise of reserving the innate advantages of induced spatial incoherence (better far-field smoothing characteristics), thereby avoiding the damage to devices and limitation to output capacity in high power laser system using induced spatial incoherence. Based on the theoretical modeling and numerical analysis, using modulation degree, softening factor, and transmittance as evaluation parameters, the near-field light characters with three kinds of filter apertures, such as square, round, and Gaussian, are compared and analyzed. Finally, in a typical optimization result there are used 16×16 induced spatial incoherent divisions and a square aperture with 0.8 times diffraction limit width. In this case, the near-field intensity distribution is uniform, and at the same time, good smoothing effect on far-field and a high energy utilization rate are ensured. On this basis, according to the actual application of the device, the influence of the collimation error on the near-field intensity distribution is further analyzed. The results show that as long as the collimation error is less than 0.1 times the diffraction limit, the near-field quality will not be affected. The simulation analysis of the focal spot obtained by induced spatial incoherence shows that the addition of the filtering system can further improve the low frequency uniformity of the focal spot.
Mechanism for regulation and control of emulsion droplet generation in co-flow microfluidic device via electric field
Authors: Li Lei  , Zhang Cheng-Bin  ,   Key Laboratory of Energy Thermal Conversion and Control, Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China
Published: December 2020

Applying the active control of electric field to the preparation of micro-droplets via the traditional microfluidic technology has attracted great attention because it can effectively improve the controllability of the preparing process. Therefore, a full understanding of mechanism for the regulation and control of microdroplets's generation by the microfluidic technology and electric field will provide interesting possibilities for the active control of producing required microdroplets in the practical applications. A transient theoretical model is developed via the coupling of phase-field method and electrostatic model to numerically investigate the generation of the single-phase droplets in a co-flow microfluidic device under the control of a uniform direct-current electric field. Via the numerical simulations based on the transient model, the control mechanisms of the electric field on dynamic behaviors of the droplets generation are revealed, and the influences of flow and electric parameters on the droplets generation characteristics are elucidated. The results indicate that the electrostatic field is able to generate an electric field force toward the inner phase fluid in the normal direction of the interface between two-phase fluids with different electric parameters. The electric field force enhances the necking and breaking of the inner fluid interface, which accelerates the droplets' generation, increases droplet deformation degree, and reduces droplet size. As the electric capillary number increases under the same hydrodynamic capillary number, the droplet formation pattern is transformed from dripping regime with only a single droplet formed per cycle to another dripping regime with one main droplet formed together with the following satellite droplets per cycle. In addition, according to the numerical results in this work, we organize a regime diagram to quantitatively represent the respective regime of these two flow patterns as a function of hydrodynamic capillary number and electric capillary number. The regime diagram indicates that with the increase in hydrodynamic capillary number and electric capillary number, the viscous drag force and electric field force are strengthened, which induces the formation of a slender liquid thread of inner fluid at the later stage of the necking process. This contributes to triggering the Rayleigh-Plateau instability on the liquid thread of inner fluid, and thus facilitating the generation of satellite droplets via the breakup of the liquid thread.
Quantum computation and quantum simulation
Authors: Fan Heng  ,   Solid State Quantum Information and Computation Laboratory, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

In past few years, quantum computation and quantum simulation have been developed rapidly. The research on quantum computation and quantum simulation involving medium scale number of qubits will have a development priority. In this paper, we review recent developments in those directions. The review will include quantum simulation of many-body system, quantum computation, digital quantum simulators and cloud quantum computation platforms, and quantum software. The quantum simulation of many-body system will include the simulation of quantum dynamics, time crystal and many-body localization, quantum statistical physics and quantum chemistry. The review of those results is based on our consideration to the current characteristics of quantum computation and quantum simulation. Specifically, the number of available qubits is on a medium scale from dozens to several hundreds, the fidelity of the quantum logic gate is not high enough for several thousand of operations. In this sense, the present research is at the stage from fundamental explorations to practical applications. With these in mind, we hope that this review can be helpful for the future study in quantum computation and quantum simulation.
Quantum control of nitrogen-vacancy center in diamond
Authors: Liu Gang-Qin  , Xing Jian  , Pan Xin-Yu  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong Special Administrative Region, China;,   Collaborative Innovation Center of Quantum Matter, Beijing 100871, China;,   Chinese Academy of Sciences Center of Excellence in Topological Quantum Computation, Beijing 100190, China
Published: December 2020

Quantum computing and quantum sensing have received much attention in recent years. As an atomic quantum system with super-long coherence time and spin-dependent optical transitions at room temperature, nitrogen-vacancy (NV) center in diamond is one of the well-studied physical systems in quantum information science. In this review, we brief the working principles and quantum control techniques of this single spin system, and also several experimental demonstrations. We focus on the following points:1) coherent manipulation of single spins with optically detected magnetic resonance; 2) main mechanism of NV election spin decoherence and schemes of coherence protection; 3) quantum sensing and quantum computing applications of spin quantum control techniques. Some open questions are discussed at the end of this review.
Magnetoelectric effect in stretch-shear mode self-biased LiNbO3 based composite with high-frequency resonant response
Authors: Xin Cheng-Zhou  , Ma Jian-Nan  , Ma Jing  , Nan Ce-Wen  ,   State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

Magnetoelectric (ME) composites have received attention abidingly due to the promising potential applications in magnetic field sensor and energy harvester. In recent years, shear mode ME composite was frequently discussed with promising applications in high-frequency magnetic field with large signal-to-noise ratio. Single-crystal LiNbO3, as a lead-free piezoelectric phase with high mechanical quality factor and small dielectric constant, is suitable for achieving a large shear ME effect with large shear piezoelectric coefficient d15 or d24, and different piezoelectric coefficients can be obtained by crystal-cut transformation. The transformation rule of shear ME coefficient with transformation of LiNbO3 crystal orientation and the MHz high-frequency magnetic detection is still lacking. Furthermore, self-biased ME composite can be obtained with SrFe12O19 ribbon, which is useful for the integration and miniaturization of ME sensor. In the present work, we use a series of X-cut LiNbO3 to obtain different d15 or d16 in a stretch-shear ME composite. Piezoelectric coefficient d15 and ME coefficient E15 of Metglas/LiNbO3 composite are obtained in experiment, respectively. The results show that LiNbO3 xzt/30 has the largest d15 and E15, and the transformation rule of E15 is consistent with the coordinate transformation of d15. The structure of stretch-shear ME composite is optimized to improve the ME coefficient. Then the stretch-shear mode self-biased SrFe12O19/Metglas/LiNbO3 composite is fabricated, and shear ME response is observed under zero external direct current magnetic bias. Moreover, E15 at electromechanical resonance frequency is gained at shear-mode high frequency (0.991 MHz and 3.51 MHz). The largest ME coefficient E15 is acquired in the stretch-shear 5-foil Metglas/LiNbO3 (xzt/30) composite of 134.16 mV/(cmOe) at 1 kHz and 9.17 V/(cm Oe) at 3.51 MHz. This work is beneficial to the confirming of the corresponding rules of shear ME coefficient and LiNbO3 piezoelectric coefficient, showing that the composite possesses the potential applications in integration, miniaturization and high-frequency resonant sensor.
The total variation constrained data divergence minimization model for image reconstruction and its Chambolle-Pock solving algorithm
Authors: Qiao Zhi-Wei  ,   School of Computer and Information Technology, Shanxi University, Taiyuan 030006, China
Published: December 2020

Image reconstruction is an important inverse problem to reconstruct images from its transform. The two main reconstruction methods are the analytic method and the iterative method. The analytic method, for example, the filtered backprojection algorithm, needs complete projection data, so it is not competent to accurately reconstruct an image from sparse data. Thus the iterative method combined with optimization techniques has received more and more attention. The optimization-based iterative image reconstruction algorithm may accurately reconstruct images by the use of compressed sensing, low rank matrix and other sparse optimization techniques. Among them, the total variation (TV) minimization model is a simple but effective optimization model. The traditional, constrained TV model employs the data fidelity term as the constraint term and the TV regularization term as the objective function. In the present work, we study a novel, TV constrained, data divergence minimization (TVcDM) model and its solver. We derive in detail the Chambolle-Pock (CP) algorithm for solving the TVcDM model, verify the correctness of the model and its solver, analyze the convergence behavior of the algorithm, evaluate the sparse reconstruction ability of the TVcDM-CP algorithm and finally analyze the influence of the model parameters on reconstruction and the effect of algorithm parameters on convergence rate. The studies show that the TVcDM model may accurately reconstruct images from sparse-view projections. The TVcDM-CP algorithm may ensure convergence but the vibration phenomena may be observed in the convergence process. The model parameter, TV tolerance, has important influence on reconstruction quality, i. e. too big a value introduces noise whereas too small a value may smoothen the image details. Also, the studies reveal that different algorithm-parameter selections may lead to different convergence rates. The TVcDM-CP algorithm may be tailored and applied to other computed tomography scanning configurations and other imaging modalities. The necessary key work is just to design the corresponding system matrix and select the optimal model parameters and algorithm parameters according to the insights gained in the work.
Overview of magnetic skyrmion-based devices and applications
Authors: Xia Jing  , Han Zong-Yi  , Song Yi-Fan  , Jiang Wen-Jing  , Lin Liu-Rong  , Zhang Xi-Chao  , Liu Xiao-Xi  , Zhou Yan  ,   School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen 518172, China;,   Department of Electrical and Computer Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
Published: December 2020

Magnetic skyrmions possess topologically non-trivial particle-like nanoscale domain wall structures, which have reasonably good stability and unique dynamic properties and can be controlled by magnetic fields, electric fields, and electric currents. Therefore, magnetic skyrmions are expected to be used as novel information carriers in the next-generation high-density, low-energy-consumption, and non-volatile information storage and logic computing devices. Since the first experimental observation of magnetic skyrmions in 2009, a number of skyrmion-based device prototypes have been proposed. In this article, we review the recently proposed skyrmion-based devices and applications, including skyrmion-based racetrack memory, logic computing device, transistor-like functional device, and nano-oscillator. We first discuss advantages of skyrmion-based racetrack memory and solutions for some problems we are facing currently. We then introduce the duplication and merging of magnetic skyrmions and the skyrmion-based logic OR and AND gates. We also introduce the switch function of skyrmion-based transistor-like functional device. The switch function is realized via a voltage gate and controlled by the applied voltage as well as the driving spin current. Besides, a brief introduction of the skyrmion-based nano-oscillator is given. In addition, we introduce several possible methods to encode binary information in skyrmion-based devices. Finally, we discuss some possible future novel applications based on magnetic skyrmions.
Scanning tunneling microscopy research of Bi(110) thin films grown on NbSe2
Authors: Liu Jian-Yu  , Sun Hao-Hua  , Guan Dan-Dan  , Li Yao-Yi  , Wang Shi-Yong  , Liu Can-Hua  , Zheng Hao  , Jia Jin-Feng  ,   Key Laboratory of Artificial Structures and Quantum Control, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China;,   Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
Published: December 2020

Due to the novel physical properties induced by the strong spin orbit coupling and band inversions in the energy band structure, two-dimensional topological insulator has become a hot research point in the field of condensed matter physics and material science in recent years. Particularly, two-dimensional topological insulator may host exotic Majorana fermionic excitations in its edge state if superconductivity is introduced. Bi thin film with (111) orientation proves to be a two-dimensional topological insulator both in theory and in experiment. However, the topological nature of Bi thin film with (110) orientation has not yet been confirmed. In this study, high quality Bi(110) thin films are successfully prepared on superconductor NbSe2 surfaces, by the molecular beam epitaxial technology at ambient temperature and a low deposition rate (~24℃,~3 min/bilayer). The morphologies and electronic properties of the samples are studied by using scanning tunneling microscopy and spectroscopy. The experimental results reveal that the growth mode changes from bilayer (BL) in BL mode to monolayer (ML) in ML mode. Such transition takes place at a critical height of about 4 BLs. The mechanism of the growth mode transition is believed to be induced by the drastic variation of the surface energies of the thin films with different thickness values. Due to the large coverage of Bi(110) film on the NbSe2 substrate, it is almost impossible to find the exposed areas of NbSe2 substrate surface in practice. Especially on the sample with a large number of layers of Bi thin film, it is hard to directly determine the number of layers for each film. Hence, the critical thickness could be only estimated by controlling the deposition time and growth rate combining with the measurements of stage height of the film. The nearly identical local density of states wherever measured in the interior of a terrace or at the step edges can be discerned from the dI/dV spectra, which is thus hard to corroborate with non-trivial topology in either BL or ML thick Bi(110) film. The superconductivity induced by proximity effect from the superconducting substrate NbSe2 is also observed on the thin films. Through Bardeen-Cooper-Schrieffer type data fitting, the superconducting gap on the Bi thin film is estimated at about 0.5 meV. In addition, the quantum well state, which is often observed in thin films, is also revealed from the Bi(110) thin films, whose characteristic is equal energy spacing between peaks in dI/dV spectra. Noticeably, the spectral shapes of BL and ML are similar, and the local density of states from adjacent film layers displays an approximate πup phase shift.
Key distribution based on unidirectional injection of vertical cavity surface emitting laser system
Authors: Zhang Hao  , Guo Xing-Xing  , Xiang Shui-Ying  ,   State Key Laboratory of Integrated Service Networks, School of Telecommunication Engineering, Xidian University, Xi'an 710071, China
Published: December 2020

Random source is important for the security of key distribution. In this paper, a novel secure key distribution scheme based on unidirectional injection of vertical cavity surface emitting laser (VCSEL) system is proposed. In the proposed scheme, a chaotic signal without time delay signature is generated by a VCSEL subject to unidirectional optical injection, which is regarded as a master laser. The chaotic signal generated by the master VCSEL is further injected into two slave VCSELs to obtain synchronized bandwidth-enhanced chaotic signals. After that, by sampling, quantizing and XOR operation on the two synchronized chaotic signals, two key streams can be obtained.
Based on the well-known spin-flip model, the time delay signature of chaotic signals generated by master VCSEL and the synchronization performance between the master VCSELs and two slave VCSELs are numerically investigated in detail. It is shown that by the unidirectional injection, the chaotic outputs can be achieved in the master VCSEL in a wide range of frequency detuning and coupling strength. More importantly, no time delay signature can be observed in the auto correlation function of the chaotic intensity time series generated by the master VCSEL. Besides, we find that high quality synchronization is achieved between the bandwidth-enhanced chaotic signals generated by two slave VCSELs under the common driving of master VCSEL. The synchronization coefficient between two slave VCSELs increases up to 0.99, and the synchronization coefficient between master VCSEL and salve VCSEL is only 0.74. Note that such a high quality synchronization between two slave VCSELs while relatively low quality synchronization between the master and slave VCSEL is conducible to ensuring the security of key distribution.
In addition, the effects of tunable parameters on key bit error rate are considered, and two quantization methods are employed for comparison. Numerical simulation results show that the key bit error rate between two legitimate users is as low as 1%, and the key bit error rate between legitimate user and eavesdropper is higher than 10% in the single-threshold case; the bit error rate can even be as low as 10-6 in the double-threshold case. The influence of parameter mismatch on key bit error rate is also discussed, and it is suggested that two salve VCSELs should be finely matched to ensure low bit error rate. Finally, NIST randomness test is performed for the generated key streams. Hence, the proposed scheme enhances the security of key distribution, which is valuable for further developing the chaos communication systems.
Strontium optical lattice clock
Authors: Lin Yi-Ge  , Fang Zhan-Jun  ,   National Institute of Metrology, Beijing 100029, China;,   National Time and Frequency Metrology Center, Beijing 100029, China
Published: December 2020

The strontium optical lattice clock has experienced a rapid development since the beginning of the 21st century. Its relative frequency uncertainty, on the order of 10-18, has surpassed that of the cesium fountain clock, the current primary standard for time and frequency. This supreme level of precision reflects one of the most advanced measurement capabilities of mankind. This article reviews the current progress of the strontium optical lattice clock, and describes its key components and techniques, including high-resolution spectroscopy, close-loop operation, evaluation of systematic shifts, and absolute frequency measurement. The applications and future outlook of the strontium clock are also summarized.
Research progress of light out-coupling in organic light-emitting diodes with non-period micro/nanostructures
Authors: Liu Meng-Jiao  , Zhang Xin-Wen  , Wang Jiong  , Qin Ya-Bo  , Chen Yue-Hua  , Huang Wei  ,   National Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
Published: December 2020

Organic light-emitting diodes (OLEDs) possess a number of advantages such as low power consumption, light weight, wide color gamut, high response speed, and high contrast ratio. They have received widespread attention due to their tremendous commercial applications in the fields of full-color flat panel display and solid-state lighting. Although nearly 100% internal quantum efficiency of OLED has been achieved through adopting phosphorescence or thermally activated delayed fluorescence emitters. However, the majority of light generated in an emitting layer is confined within the whole device but does not escape into air due to the induced surface plasmons at the interface between metal and dielectric layers as well as the differences in refractive index between layers of OLED structures including air, glass substrate, transparent electrode as well as organic or inorganic layers. The external quantum efficiency for an OLED with a flat glass substrate is limited to~20%. A low light out-coupling efficiency severely restricts the development and application of OLED. Therefore, enhancing the light out-coupling efficiency of OLED via light extraction technology offers the greatest potential for achieving a substantial increase in the external quantum efficiency of OLED and has been one of the most attractive projects. Up to now, lots of light out-coupling technologies such as micro-lens arrays, photonic crystal, Bragg mirrors and periodic grating have been suggested to enhance the out-coupling efficiency of OLEDs. However, the periodic light out-coupling structures have a limitation that the electroluminescence intensity and spectrum of OLED usually depend on the viewing angle. The angular dependence of the emission characteristic does not hold true for actual display applications due to its deviation from the Lambertian intensity distribution. In this review, we present recent research progress of using non-period micro/nanostructures to improve the light out-coupling efficiency of OLED. In contrast to the emission directionality for OLED using periodic light out-coupling structures, the luminance distribution and spectral stability of OLED based on non-period micro/nanostructures are insensitive to viewing angle. Various light out-coupling techniques such as random micro/nano lens structure, light scattering medium layer, polymer porous scattering films, random concave-convex corrugated structure, and random buckled structure are summarized and discussed. These techniques have the potential applications in displays and solid-state lighting. Finally, summary and prospects regarding to light-coupling techniques of OLEDs are presented.
Research progress of metal catalysts enhanced synthesized by cold plasma
Authors: Li Zhuang  , Di Lan-Bo  , Yu Feng  , Zhang Xiu-Ling  ,   College of Physical Science and Technology, Dalian University, Dalian 116622, China;,   School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, China
Published: December 2020

Cold plasma is a kind of non-thermal plasma, and characterized by high electron temperature (1-10 eV) and low gas temperature, which can be close to room temperature. It has been proved to be a fast, facile and environmentally friendly new method for synthesizing supported metal catalysts. Enhanced synthesis of metal catalysts by cold plasma consists of complex physical and chemical reactions. On the one hand, the active environment provided by cold plasma, can not only speed up the chemical reactions, shorten the reaction time from a few hours to several minutes, but also realize the kinetically or thermodynamically infeasible chemical reactions to achieve unconventional preparation. On the other hand, the phase contact behavior on a mesoscopic scale is influenced during cold plasma enhanced preparation, thereby the metal catalysts with structure different from that synthesized by traditional method. This review summarizes the reactor structure, physical and chemical mechanism for synthesizing metal catalysts by cold plasma, as well as the structure characteristics of the obtained metal catalysts. According to the working pressure, cold plasma can be categorized into low-pressure (LP) cold plasma and atmospheric-pressure (AP) cold plasma. The LP cold plasma is often generated by radio frequency glow discharge or direct current glow discharge, while the AP cold plasma is generally generated by dielectric barrier discharge and AP cold plasma jet. Energetic electrons are deemed to be the reducing agents for LP cold plasma. However, due to the frequent collisions among the electrons and gas molecules at atmospheric pressure, the electron energy in AP cold plasma is not high enough to reduce the metal ions directly. Therefore, hydrogen-containing gases are often adopted to generate active hydrogen species to reduce the metal ions. The process of synthesizing the metal catalysts by using the cold plasma is a fast, low-temperature process, and in the preparation process there exists a strong Coulomb repulsion. Therefore, metal catalysts with small size and high dispersion of metal nanoparticles, strong metal-support interaction, as well as specific metal structures (alloying degree and crystallinity) and modified supports can be obtained. Correspondingly, metal catalysts with high catalytic activity and stability can be synthesized. In addition, the challenges of preparing the cold plasma are discussed, and the future development is also prospected.
Exploration and physical investigation of FeSe-based superconductors
Authors: Wang Nai-Zhou  , Shi Meng-Zhu  , Lei Bin  , Chen Xian-Hui  ,   Department of Physics, University of Science and Technology of China, Hefei 230026, China;,   CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei 230026, China;,   Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China;,   CAS Center for Excellence in Superconducting Electronics(CENSE), Shanghai 200050, China
Published: December 2020

Since the high-Tc superconductivity in iron-based superconductors was found in 2008, numerous new iron-based superconductors have been discovered. Of them, FeSe-based superconductors receive the most attention due to their unique properties. Here, we briefly introduce the structure and physical properties of two newly found FeSe-based superconductors, i.e. (Li, Fe) OHFeSe and (CTA)x FeSe. The former is synthesized by the hydrothermal method, while the latter is synthesized by electrochemical intercalation method. Moreover, we also introduce the tuning of electronic properties of FeSe by electric-double-layer and solid-ion-conductor based transistors.
Applications of new exfoliation technique in study of two-dimensional materials
Authors: Xu Hong1\2  , Meng Lei1\3  , Li Yang1\4  , Yang Tian-Zhong  , Bao Li-Hong  , Liu Guo-Dong  , Zhao Lin  , Liu Tian-Sheng  , Xing Jie  , Gao Hong-Jun  , Zhou Xing-Jiang  , Huang Yuan  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   School of Science, China University of Geosciences, Beijing 100083, China;,   College of Science, Minzu University of China, Beijing 100081, China;,   School of Environment and Safety Engineering, North University of China, Taiyuan 030051, China
Published: December 2020

Since the discovery of graphene, mechanical exfoliation technology has become one of the important methods of preparing high-quality two-dimensional (2D) materials. This technology shows some unique advantages in the study of the intrinsic properties of 2D materials. However, traditional mechanical exfoliation method also has some obvious deficiencies, such as low yield ratio and small size of the resulting single-or few-layer flakes, which hinders the research progress in the field of 2D materials. In recent years, we made a series of breakthroughs in mechanical exfoliation technology, and independently developed a new type of mechanical exfoliation method with universality. The core of this new method is to enhance the van der Waals interaction between the layered material and the substrate by changing multiple parameters in the exfoliation process, thereby increasing the yield ratio and area of the monolayer. Taking graphene for example, we can now increase the size of graphene from micron to millimeter, increase over 100000 times in area, and yield ratio more than 95%, in the meantime graphene still maintains very high quality. This new mechanical exfoliation method shows great universality, and high-quality monolayer flake with a size of millimeters or more has been obtained in dozens of layered material systems including MoS2, WSe2, MoTe2, and Bi2212. More importantly, some special structures can be fabricated by optimizing exfoliation parameters, such as bubble and wrinkle structures, which paves the way for the study of these special material systems. Many scientific problems are still worth exploring in the mechanical exfoliation technology, and the breakthrough of this technology will greatly promote the research progress in the field of 2D materials.
Research progress on FeSe-based superconducting materials
Authors: Jin Shi-Feng  , Guo Jian-Gang  , Wang Gang  , Chen Xiao-Long  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;,   Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
Published: December 2020

FeSe-based superconductors, as an important part of the family of iron-based superconducting materials, have attracted intensive research interest in the field of condensed matter physics. The exploration and preparation of such superconducting materials is the basis for studying their physical properties. At present, the exploration of FeSe-based superconducting materials mainly focuses on intercalated materials and epitaxial single-layer FeSe films. Among them, the intercalated FeSe-based superconducting materials have unique properties and are numerous in variety. This paper introduces a series of FeSe-based high-temperature superconducting materials discovered in recent years, covering KxFe2Se2, AxNH3FeSe, LiOHFeSe and organic molecular intercalation FeSe, etc., their properties and impacts are also briefly described.
An Error Analysis of Research Project Abstracts Written by Thai Undergraduate Students
Authors: Amnuai Wirada
Published: December 2020

Errors in writing are unavoidable while students are trying to develop their writing skills. There have been several studies on identifying writing problems or errors in students’ writing. It is believed that identifying students’ written tasks is an effective tool to explore the difficulties involved in learning language. This helps teachers’ awareness of the serious problems which occur in students’ writing and allows them to pay closer attention to their errors. The aim of the present research study is to pinpoint writing errors in English abstracts written by Thai undergraduate students. Forty abstracts of research projects were collected and analysed. The error analysis was conducted at the sentence level, word level, and mechanics aspect. The five most frequent error types ranking from the most frequent to least frequent were word choice, preposition, sentence construction, singular or plural forms and quotation marks. The findings of the present study have shed light on the students’ writing ability and give an insight into what the problems students face when writing their abstracts. Also, the errors found in the abstracts in the present study have pedagogical implications concerning English language learning, particularly with writing courses. The findings will be helpful for teachers to develop teaching materials to assist their students from committing errors when writing English abstracts and to improve academic writing skills.
Validity and Reliability Study of Academic Self-Efficacy Scale for Faculty Members
Authors: Safali Serdar , Akpunar Bürhan
Published: December 2020

In this study, it is aimed to develop a measurement tool with measurement validity and reliability, which can be utilized to identify the academic self-efficacy attitudes of faculty members working in the education faculty. The literature was screened during the development of the scale, the opinions of the teaching staff about the subject were taken one-on-one, and a pool of 40 items was created by making use of the previous studies related to this field. The validity and reliability of the measurement tool were analyzed on the 410-person data set obtained from the application. Exploratory Factor Analysis (EFA) was conducted with the remaining 200 data from the data set, without looking at specific criterion on the structure validity of the scale. As a result of the Exploratory Factor Analysis applied to the data obtained after the first application, 7 items were removed from the 40-item scale. It was determined that the remaining 33 items consisted of 5 sub-dimensions. The scale sub-dimensions are named as follow respectively; “Comparing yourself with other faculty members”, “Being able to combat the difficulties faced”, “Self-development”, “Effective teaching process of a course” and “Extracurricular activity”. The Cronbach’s alpha coefficient was .877 for the whole scale, and it was as follows for the sub-dimensions in respective order; .920.927.895.833 and .828. These findings have revealed that the scale is a tool that can measure academic staffs’ Self-Efficacy levels with five factors. The scale is expected to be used by researchers in the field.
The present paper investigates the Hijazi Arabic (HA) morphosyntactic properties of the widely known linguistic phenomenon of sluicing from a generative perspective, taking into account the latest advancements of the Minimalist Approach (Chomsky 1995, 2000, 2001). In this paper, sluicing is a linguistic phenomenon of deleting an entire TP clause, leaving only a wh-remnant. Adopting the Structural PF-Deletion approach, we argue that HA employs sluicing and that the ellipsis site contains a fully-fledged syntactic structure that must be deleted at the PF level after the movement of the remnant to a higher CP. On a par with previous crosslinguistic ellipsis studies, the current study shows that ellipsis is permitted if and only if there is a specific head carrying some specific morphosyntactic properties occurring in a local relation to the ellipsis site. This specific head, with its morphosyntactic properties, licenses for the ellipsis phenomenon to occur. The head properties trigger the whword to move from its base-generated position to the specifier position of this particular head, i.e., Spec CP, and then delete all other constituents included within the TP.
Authors: Mohammad Al Zahrani , Khulud Al Thagafi
Published: December 2020

The present paper investigates the Hijazi Arabic (HA) morphosyntactic properties of the widely known linguistic phenomenon of sluicing from a generative perspective, taking into account the latest advancements of the Minimalist Approach (Chomsky 1995, 2000, 2001). In this paper, sluicing is a linguistic phenomenon of deleting an entire TP clause, leaving only a wh-remnant. Adopting the Structural PF-Deletion approach, we argue that HA employs sluicing and that the ellipsis site contains a fully-fledged syntactic structure that must be deleted at the PF level after the movement of the remnant to a higher CP. On a par with previous crosslinguistic ellipsis studies, the current study shows that ellipsis is permitted if and only if there is a specific head carrying some specific morphosyntactic properties occurring in a local relation to the ellipsis site. This specific head, with its morphosyntactic properties, licenses for the ellipsis phenomenon to occur. The head properties trigger the whword to move from its base-generated position to the specifier position of this particular head, i.e., Spec CP, and then delete all other constituents included within the TP.
Evaluation of Suitability of a Listening Textbook for English Majors in Universities of China
Authors: Zhang Xuezhu
Published: December 2020

Textbooks occurring in diverse social settings points to the need to make textbook evaluation in its social context. Many researchers have highlighted the significance of evaluating textbooks in local practices. The present study aims at exploring the suitability of a listening textbook--- A Listening Course(I) published by Shanghai Foreign Language Education Press in terms of content analysis. The analysis of the textbook finds that the general organization of the book, text types, listening tasks and activities are mostly suitable for first-grade English majors, but it still needs improvement on theme interests, authenticity, task options and assessment. Although ALC is a localized textbook, it still mirrors the macrocosm of English language teaching. The findings of this study will shed light on developing listening materials for textbook developers in order to avoid some pitfalls, and enlighten teachers on selecting suitable listening textbooks.
Feasibility of automated planning for whole‐brain radiation therapy using deep learning
Authors: Yu Jesang , Goh Youngmoon , Song Kye Jin , Kwak Jungwon , Cho Byungchul , Kim Su San , Lee Sang‐wook , Choi Eun Kyung
Published: December 2020

Purpose

The purpose of this study was to develop automated planning for whole‐brain radiation therapy (WBRT) using a U‐net‐based deep‐learning model for predicting the multileaf collimator (MLC) shape bypassing the contouring processes.

Methods

A dataset of 55 cases, including 40 training sets, five validation sets, and 10 test sets, was used to predict the static MLC shape. The digitally reconstructed radiograph (DRR) reconstructed from planning CT images as an input layer and the MLC shape as an output layer are connected one‐to‐one via the U‐net modeling. The Dice similarity coefficient (DSC) was used as the loss function in the training and ninefold cross‐validation. Dose‐volume‐histogram (DVH) curves were constructed for assessing the automatic MLC shaping performance. Deep‐learning (DL) and manually optimized (MO) approaches were compared based on the DVH curves and dose distributions.

Results

The ninefold cross‐validation ensemble test results were consistent with DSC values of 94.6 ± 0.4 and 94.7 ± 0.9 in training and validation learnings, respectively. The dose coverages of 95% target volume were (98.0 ± 0.7)% and (98.3 ± 0.8)%, and the maximum doses for the lens as critical organ‐at‐risk were 2.9 Gy and 3.9 Gy for DL and MO, respectively. The DL technique shows the consistent results in terms of the DVH parameter except for MLC shaping prediction for dose saving of small organs such as lens.

Conclusions

Comparable with the MO plan result, the WBRT plan quality obtained using the DL approach is clinically acceptable. Moreover, the DL approach enables WBRT auto‐planning without the time‐consuming manual MLC shaping and target contouring.
MAX Phases as Nanolaminate Materials: Chemical Composition, Microstructure, Synthesis, Properties, and Applications
Authors: Fu Le , Xia Wei
Published: December 2020

In recent years, MAX phases, a family of nanolaminate materials, have garnered tremendous research interest worldwide, due to the fact that they possess an excellent combination of both metallic and ceramic characteristics. The number of publications on MAX phases has experienced an almost exponential increase in the past decade. The main objective herein is to develop a comprehensive understanding of MAX phases, meanwhile presenting the recent progress and development of MAX phases. The Review starts with introducing the chemical composition of MAX phases, followed by reviewing the microstructure, which includes both the well‐known 211, 312, and 413 structures and the newly discovered out‐of‐plane ordered and in‐plane ordered structures. A wide range of synthesis methods are reviewed, such as traditional hot pressing, pressure‐less sintering, and recently reported substitutional solid–liquid reaction method. The chemical and physical properties of MAX phases are summarized. The potential fields of applications for MAX phases are surveyed, such as high‐temperature materials, nuclear materials, precursors for MXene, etc. In addition, an outlook for future research on MXX phases is also presented.
Tuning Mechanical Properties in Polycrystalline Solids Using a Deep Generative Framework
Authors: Hsu Yu-Chuan , Yu Chi-Hua , Buehler Markus J.
Published: December 2020

A framework for inverse design of tuning mechanical properties of polycrystalline brittle materials is presented using artificial intelligence (AI). Crystalline solids, which often exhibit distinct mechanical properties at different orientations, can be used as building blocks for polycrystalline composites. However, the design space of geometry and crystal misorientations is typically intractable, and all possible solutions cannot be discovered using experiment or numerical simulation. Herein, a framework using deep learning (DL) alongside a genetic algorithm (GA) is adopted to generate composite polycrystalline materials, whereas the raw material is brittle and sensitive to crystalline orientation, to achieve distinct mechanical properties in various combinatorial designs. The DL model, trained by full‐atomistic simulations of crystals with different orientations, evolves autonomously to yield a desirable range of target toughness values, exemplified in maximizing and minimizing toughness, which are validated by molecular dynamics (MD) simulations. It is found that higher crystal misorientations are preferred for high toughness, as opposed to lower overall misorientations for low‐toughness designs. Notably, this shows that a mechanism can be extracted from the AI algorithm. This materiomics method may ultimately change the way nanomaterials are designed, and can be applied to de novo biomaterial design, architected materials, and bioinspired structural materials.
Biocultural approaches to transgender and gender diverse experience and health: Integrating biomarkers and advancing gender/sex research
Authors: DuBois L. Zachary , Gibb James K. , Juster Robert‐Paul , Powers Sally I.
Published: December 2020

Transgender and gender diverse (TGD) people are increasingly visible in U.S. communities and in national media. With this increased visibility, access to gender affirming healthcare is also on the rise, particularly for urban youth. Political backlash and entrenchment in a gender binary, however, continue to marginalize TGD people, increasing risk for health disparities. The 2016 National Institute of Health recognition of sexual and gender minority people as a health disparities population increases available funding for much‐needed research. In this article, we speak to the need for a biocultural human biology of gender/sex diversity by delineating factors that influence physiological functioning, mental health, and physical health of TGD people. We propose that many of these factors can best be investigated with minimally invasively collected biomarker samples (MICBS) and discuss how to integrate MICBS into research inclusive of TGD people. Research use of MICBS among TGD people remains limited, and wider use could enable essential biological and health data to be collected from a population often excluded from research. We provide a broad overview of terminology and current literature, point to key research questions, and address potential challenges researchers might face when aiming to integrate MCIBS in research inclusive of transgender and gender diverse people. We argue that, when used effectively, MICBS can enhance human biologists' ability to empirically measure physiology and health‐related outcomes and enable more accurate identification of pathways linking human experience, embodiment, and health.
Chemically Fueled Volume Phase Transition of Polyacid Microgels
Authors: Heckel Jonas , Loescher Sebastian , Mathers Robert T. , Walther Andreas
Published: December 2020

Microgels are soft colloids that show responsive behavior and are easy to functionalize for applications. They are considered key components for future smart colloidal material systems. However, so far microgel systems have almost exclusively been studied in classical responsive switching settings using external triggers, while internally organized, autonomous control mechanisms as found in supramolecular chemistry and DNA nanotechnology relying on fuel‐driven out‐of‐equilibrium concepts have not been implemented into microgel systems. Here, we introduce chemically fueled transient volume phase transitions (VPTs) for poly(methacrylic acid) (PMAA) microgels, where the collapsed hydrophobic state can be programmed using the fuel concentration in a cyclic reaction network. We discuss details of the system behavior as a function of pH and fuel amount, unravel kinetically trapped regions and showcase transient encapsulation and time‐programmed release as a first application.