bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamical phase transition and selective energy exchange in dual-cavity optochanical systems
Authors: Liu Ni , Zhang Xiao-Fang , Liang Jiu-Qing ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Theoretical Physics, Shanxi University, Taiyuan 030006, China
Published: June 2021

 In recent years, the cavity quantum photomechanics has been developed rapidly, and played a very important role in quantum information processing, quantum basic principle verification, and high-precision measurement. The kinds of quantum mechanical behaviors have also been explored and discovered in the study of cavity mechanics. By placing the Kerr medium in the system, quantum nonlinearity is introduced into the optomechanical system. Quantum phase transition is a relatively important part in the research of condensed matter physics. Since Dicke quantum phase transition was successfully observed experimentally, the problem of quantum phase transition in the optical cavity has attracted more attention. The spin-coherent-state variation method and the Holstein-Primakoff transformation are used to theoretically calculate the ground state energy functional, and the rich structure of the macroscopic multi-particle quantum state is given by adjusting the parameters. The quantum phase transition evolution equation describes the relationship between each phase and the time of generating a new phase when reaching the critical phase transition point. At the same time, the mode squeezing of multi-mode hybrid optomechanical system has also became one of the basic problems of quantum mechanical behavior in cavity quantum dynamics.

 In this article, we explore the quantum dynamics of optomechanical devices including single-cavity and dual-cavities. We find that the system will undergo a dynamic phase transition, which is similar to the Dicke-Hepp-Lieb superradiant type phase transition, and a new dynamic critical point appears in the coupling between the momentum quadratures of the two optical fields. By manipulating the coupling parameters, we can achieve selective energy exchange between any two modes and the critical coupling point corresponds to selective energy exchange. Mode squeezing, which is easy to measure by applying the quantum uncertainty relationship, is also revealed and consistent with selective energy exchange. The study of coordinate and momentum variances gives us the revelation that the compressed orthogonal variables are the most suitable for measurement because of the small quantum noise. In fact, phononic modes can store energy in a longer duration, while photonic modes can transfer energy in a long distance. This phenomenon makes the hybrid optomechanical cavities useful in the next-generation quantum communications and quantum information processing units.
First-principles study of properties of rare-earth-doped LiFePO4
Authors: Zhong Shu-Lin , Qiu Jia-Hao , Luo Wen-Wei , Wu Mu-Sheng ,   College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, China
Published: June 2021

Doping is one of the most important methods to improve the electronic conductivity and modify its electrochemical performance of LiFePO4. Rare earth elements have become an effective selection for doping modification due to their high electronic charges, large ion radii and strong self-polarization ability. In this work, we study the structural, electronic and ionic diffusion properties of LiFePO4 with rare earth (RE) doping (La, Ce, Pr) by using first-principles calculation based on density functional theory. The calculated results show that the lattice constant and cell volume of LiFePO4 increase to a different degree after RE doping. In the delithiation process, the volume change rate of the material after RE doping is significantly reduced, indicating the cycle performance of the material is improved, on the other hand, the energy density is reduced. The calculated density of states suggests that RE-doped LiFePO4 exhibits metallic characteristics, which is different from the undoped one with semiconductor characteristics. As a result, the RE-doping can increase the electronic conductivity of the material. The calculation of elastic modulus demonstrates the increase of ductility for RE-doped LiFePO4, and it can be predicted that the cycle performance and the rate performance of the RE-doped battery have great improvement. In addition, La and Ce doped LiFePO4 materials exhibit that the complex energy barrier can change during the Li ion migration, and the migration barriers vary considerably, depending on different paths, which is related to the variation of potential energy surface caused by the doping of rare-earth elements. The Li-ions are far from the RE ions, the migration barriers are obviously lower than the undoped one, while the Li-ions are closest to RE ions, the migration barriers increase essentially. Compared with Ce doping, the change of the Li-ion migration barrier caused by La doping is great, indicating that RE ion doping has a greater influence on the local structure of the system.
Mechanism of rapid compression-induced melt crystallization in selenium
Authors: Wang Lu , Wang Ju , Li Na-Na , Liang Ce , Wang Wen-Dan , He Zhu , Liu Xiu-Ru ,   Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China,   Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
Published: June 2021

Amorphous selenium (Se) can be easily prepared by quenching the melt, which indicates that the Se possesses the good glass-forming ability. However, crystallization occurs after rapidly compressing the melt within about 20 ms. In this work, we investigate the mechanism of rapid compression-induced crystallization from Se melt. Compressing Se melt experiments are carried out at the following temperatures: 513, 523 and 533 K. The melt is rapidly compressed under 2.4 GPa for about 20 ms. Different holding times, i.e. 0, 30, 60 min after solidification are adopted. The samples are quenched to room temperature and then unloaded to ambient pressure. The X-ray diffraction analysis of the recovered sample indicates that the crystallization product is the t-Se. It is found that with the prolongation of holding time, the grain size increases due to the continuous aggregation growth of crystal grains. By comparing with the isothermal crystallization products of amorphous Se and ultrafine Se powder, it is suggested that the rapid compression-induced solidification product should be t-Se crystalline. The speculation that the solidification product is amorphous Se and it crystallizes in the cooling process does not hold true. The amorphous Se cannot be prepared through the rapid compression process on a millisecond scale. It is related to the thermal stability of amorphous Se under high pressure. It is reported that the dependence of crystallization temperature Tx on pressure i.e. dTx/dP for amorphous Se is about 40–50 K/GPa in a range of 0.1 MPa–1 GPa. However, the Tx of amorphous Se is almost constant in a range of 2–6 GPa. It means that the thermal stability of amorphous Se against crystallization does not increase with increasing pressure after 2 GPa. In this work, the temperature of 513–533 K in the experiments is higher than the Tx of amorphous Se. Therefore, the t-Se crystal is the stable phase and amorphous Se is unstable. The Se melt tends to crystallize in the supercooled liquid state after rapid compression. It is interesting to investigate the mechanism of dTx/dP curve discontinuous change at around 2 GPa in the future. Both the Se melt after rapid compression and the amorphous Se before crystallization are in supercooled liquid state. We speculate that high pressure may result in the microstructure transition in supercooled liquid state Se.
Far-field diffraction pattern of cube corner retroreflector at oblique incidence
Authors: Tang Kai , Cheng Zhi-En , Deng Hua-Rong , Geng Ren-Fang , Zhang Zhong-Ping ,   Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China,   School of Remote Sensing & Geomatics Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China
Published: June 2021

Corner cube retroreflector (CCR) as a main optical component of laser ranging retroreflector array plays a key role in satellite laser ranging (SLR) to cooperative targets. To accurately estimate the echo energy of SLR, it is necessary to precompute photons’ distribution in the distance of SLR station by calculating the Far field diffraction pattern (FFDP) of CCR under various conditions. In this paper, the analysis of the effective reflection area and optical reflectivity of CCR for arbitrary incidence angle are carried out, in which a method to calculate the CCR effective reflection area with a wider applicability is used, and the difference between optical reflectivity of metal-coated CCR and uncoated (total internal reflection) CCR is also discussed. On this basis, combined with optical diffraction theory, a simulation program for CCR FFDP calculation is established, thereby producing FFDPs of CCR for a variety of incidence angles under different coating conditions. The results show that the FFDP of metal-coated CCR is almost unrelated to the azimuth angle of incident light or polarization, but is determined only by elevation angle of incident light. The pattern is always like Airy spot or its tensile deformation. Relatively, uncoated CCR’s FFDP has a more complex figure, its reflected energy is divided into several lobes whose size, number and position are all influenced by elevation and azimuth angle of incidence, and also by the polarization. Generally, the incidence direction which has a large total intensity of far optical field is to an extent the same as that of large effective reflection area and optical reflectivity. Furthermore, simulation results with uncoated CCR presents a higher relevance of incidence direction and FFDP.

To verify the reliability and correctness of these simulation results, a diffraction optical experimental system at a wavelength of 1550 nm is set up to conduct laboratory confirmation, including laser, camera, beam expander, rotating platform and other essential optics. A silver-coated CCR and an uncoated CCR (both made of fuse silica, each has different dihedral angle offset) are chosen to measure their FFDPs with random polarization directions at several random incidence angles. All the measurement results are in good agreement with the simulations of FFDPs.
First-principles study of e interface interaction and photoelectric properties of the solar cell heterojunction CdS/CdMnTe
Authors: Luan Li-Jun , He Yi , Wang Tao , Liu Zong-Wen ,   School of Materials Science and Engineering, Chang’an University, Xi’an 710064, China,   State Key Laboratory of Solidification Technology, Northwestern Polytechnical University, Xi’an 710072, China,   Australian Centre for Microscopy & Microanalysis, School of Chemical and Biomolecule Engineering, University of Sydney NSW 2006, Australia
Published: June 2021

CdS/CdMnTe heterojunction is the core of photoelectric conversion of CdMnTe film solar cells, whose interface properties have an important influence on the cell efficiency. In this study, the first-principles calculation method based on density functional theory is used to build the surface model for each of the CdS (002) and the CdMnTe (111) and the model of CdS/CdMnTe heterojunction with Mn atoms occupying different positions, and to analyze their electronic properties and optical properties. The results show that the lattice mismatch of the CdS/CdMnTe heterojunction is about 3.5%, the atomic positions and bond lengths of the interface change slightly after relaxation. The density of states shows that there is no interface state near the Fermi level in CdS/CdMnTe interface. Besides, the atoms at CdS/CdMnTe interface are hybridized, which can enhance the interface bonding. The differential charge density analyses indicate that the charge transfer mainly occurs at the interface, and electrons transfer from CdMnTe to CdS. The optical analysis shows that CdS/CdMnTe heterojunction mainly absorbs ultraviolet light, and the absorption coefficient can reach 105 cm–1. However, the optical properties of heterojunctions with different Mn atom positions are slightly different. In a range of 200–250 nm, the absorption coefficient of the heterojunction with Mn atom in the middle layer is larger, but in a range of 250–900 nm, the absorption peak of the heterojunction with Mn atom in the interface layer is higher. The results in this paper can provide some references for improving the photoelectric conversion efficiency of stacked solar cells through the reasonable construction of the heterojunction model and the analysis of the interface photoelectric performance, which is beneficial to the experimental research of multi-band gap heterojunction.
Calibration method of instrument line shape for infrared radiometer
Authors: Sun Yong-Feng , Xu Liang , Shen Xian-Chun , Wang Yu-Hao , Xu Han-Yang , Liu Wen-Qing ,   Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China,   University of Science and Technology of China, Hefei 230026, China
Published: June 2021

Interferometric infrared spectral radiometer has high luminous flux and large passing aperture, so the spectral data collected by the instrument are the convolution of the target spectral data and the instrument line shape (ILS). The main factors affecting the ILS include truncation effect, finite field of view effect, off-axis effect, defocus effect and relative position of detector and so on. In this paper the truncation effect, finite field of view effect, off-axis effect and defocus effect on ILS are expounded. These ILS errors all cause the ideal spectrum to drift towards the low wave number and widen. In this paper, the ideal absorption spectrum of water vapor is simulated by the line-by-line integration, through using MATLAB software and combining with the data of water vapor spectrum in HITRAN database, and the quantitative relationship between the error of instrument linear function and spectral distortion is established. According to the simulation results, a factor weight correction algorithm is proposed. It is believed that with this method, the error spectrum caused by ILS has the same optical properties as the ideal spectrum, but the optical path difference is different. Therefore, the coefficient matrix  H  can be constructed to establish the quantitative relationship between the error spectrum and the ideal spectrum, and the error spectrum can be corrected by using Landweber iterative algorithm. In this paper, the simulation data of water vapor absorption are used to verify the factor weight correction algorithm, and the spectral drift decreases from 0.51 cm–1 to less than 0.01 cm–1. The accuracy of the factor weight correction algorithm is verified by the experimental observation of the standard black body with self-developed interferometric infrared spectral radiometer. The spectral drift of the measured data decreases from 0.226 cm–1 to 0.012 cm–1, and the corrected spectral data are more accurate.
Surface segregation, structural features, and diffusion of NiCu bimetallic nanoparticles
Authors: Deng Yong-He , Zhang Yu-Wen , Tan Heng-Bo , Wen Da-Dong , Gao Ming , Wu An-Ru ,   School of Computational Science and Electronics, Hunan Institute of Engineering, Xiangtan 411104, China,   College of Physics, Mechanical and Electrical Engineering, Jishou University, Jishou 416000, China,   Hunan Provincial Key Laboratory of Vehicle Power and Transmission Systems, Hunan Institute of Engineering, Xiangtan 411104, China
Published: June 2021

Bimetallic core-shell nanoparticles such as NiCu are of great interest not only due to their excellent stability, selectivity, and magnetic and catalytic properties, but also because they are tunable by changing the morphology, surface element distribution, and particle size of the nanoparticles. The surface segregation and structural features of NiCu bimetallic nanoparticles, the deposition growth and the surface diffusion of Cu adsorbed atoms on the Ni substrate surface are studied by using molecular dynamics and the Montero method combined with embedded atomic potential. The results show that the Cu atom has a strong tendency of surface segregation. With the increase of concentration of Cu atoms, Cu atoms preferentially occupy the vertex, edge, (100), and (111) facet of nanoparticles due to the difference in configuration energy between Cu atoms and surface Ni atoms with different coordination numbers after the exchange, and finally form perfect Ni-core/Cu-shell nanoparticles. When growth temperature T = 400 K, the Ni-core/Cu-shell structure formed is the most stable. By observing the NiCu core-shell structure’s growth sequence, it is found that a few Ni atoms are replaced by Cu atoms on the step edge of the Ni substrate. The diffusion energy barrier of Cu atoms adsorbed on a Ni substrate surface is calculated by using the nudged elastic band method. The results show that Cu atoms adsorbed need to overcome a large ES barrier for both exchange and diffusion, making it difficult to diffuse between the facets of Ni substrate surface in a temperature range of 200–800 K. The lowest energy barrier for the diffusion of Cu atoms between facets of Ni substrate surface is 0.43 eV, and the diffusion path is from (111) facet to (100) facet. In contrast to Ni substrate, Ni atoms deposited on Cu substrate can easily migrate from the (111) facet to the (100) facet with a diffusion energy barrier of only about 0.12 eV, and at the present simulated temperature, Ni adsorbed atoms are unable to migrate on the (100) facet, resulting in a growth configuration toward an octahedral shape with its eight apex angles almost occupied by Ni atoms. In this paper, a new idea and method are provided for the preliminary design of NiCu nano-catalysts from atoms.
Surface reverberation based on small-slope approximation in deep water
Authors: Yin Li-Jun , Wu Jin-Rong , Hou Qian-Nan , Ma Li ,   Key Laboratory of Underwater Acoustic Environment, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: June 2021

For the reverberation experiments with a near surface source or receiver, surface reverberation arriving first after source signal is not influenced by bottom reverberation due to time-delay difference of acoustic multipath in deep water. A surface reverberation model is proposed in the paper. The Green’s function of sound propagation is described by the ray theory, and first-order small-slope approximation is employed for the surface scattering from full angle. The effect of bubbles scattering is also considered to get the surface reverberation theory. The reverberation model is verified by comparing the simulation results with the experimental data. The measured data show that the decaying rate of surface reverberation intensity decreases with the frequency increasing. Numerical calculation demonstrates that the frequency dependence is caused by the positive correlation between scattering strength and frequency, and the surface reverberation at low frequency for low sea state is dominated by the scattering from rough air-sea interface. Moreover, the reverberation data from experiment show that the surface reverberation is not sensitive to the change of receiving depth. A method of inversion for the two surface-wave spectral parameters in the model is achieved based on the reverberation model. The inversion results verify that the spectral parameters of rough surface can be obtained from surface reverberation data on the premise of the wind speed parameter. As a result, the scattering properties of rough interface will be obtained.
Phase locking technology for Raman laser system based on 1560 nm external cavity lasers
Authors: Wang Kai-Nan , Cheng Bing , Zhou Yin , Chen Pei-Jun , Zhu Dong , Weng Kan-Xing , Wang He-Lin , Peng Shu-Ping , Wang Xiao-Long , Wu Bin , Lin Qiang ,   Zhejiang Provincial Key Laboratory of Quantum Precision Measurement, College of Science, Zhejiang University of Technology, Hangzhou 310023, China
Published: June 2021

The technology of generating Raman laser is not only an important research content in the field of quantum precision measurement, but also a core technology of quantum inertial sensors such as cold atom gravimeter, gyroscope. For 87Rb atoms, two 780-nm lasers with a frequency difference of 6.834 GHz and a stable phase are needed to generate Raman light. Raman lasers can be generated by optical phase-locked loops of two 780-nm narrow linewidth external cavity tunable semiconductor lasers (ECDL). But the system thus developed is complicated in structure and very poor in environmental adaptability. The other method to generate Raman laser is based on intracavity 1560-nm laser with frequency doubling and electro-optic modulation technology. This system is simple in structure and strong in environmental adaptability, but it will introduce sideband effects and cannot achieve phase lock due to the limit by the linewidth and feedback bandwidth performance of the laser. In view of this, based on two new 1560-nm external cavity lasers and a home-made phase-locked circuit, in this paper the phase lock of the laser is achieved, and a Raman laser with low phase noise is obtained. The phase noise of beat note signal is as low as –95 dBc/Hz at the Fourier frequency in a range from 1 kHz to 10 kHz. A comparison of this system with the phase-locked performance of the 780-nm dual laser and the hybrid dual laser shows that this scheme has a slight advantage. In addition, the effect of the phase-locking performance on the phase noise of the cold atom interferometer through the method of piecewise integration is analyzed in this work. The experimental results given in this work provide a scheme for developing a miniaturized Raman optical system suitable for external fields.
Defects in H/He neutral beam irradiated potassium doped tungsten alloy by positron annihilation technique
Authors: He Wei-Di , Zhang Pei-Yuan , Liu Xiang , Tian Xue-Fen , Fu Xin-Ge , Deng Ai-Hong ,   College of Physics, Sichuan University, Chengdu 610065, China,   Southwestern Institute of Physics, Chengdu 610041, China
Published: June 2021

Pure tungsten (W) is a primary plasm-facing material (PFM) candidate because of its superior properties, but it still has some drawbacks. In order to solve these problems, various methods have been used to improve the performances of tungsten-based materials. Potassium (K) doping, as one of the typical dispersion-strengthening methods for W materials, improves low temperature brittleness, reduces the ductile-brittle transition temperature, and suppresses the recrystallization. Meanwhile, it also improves the thermal shock resistance and fracture toughness of the material by introducing nano-sized K bubbles. However, this method brings a large number of defects inevitably. In fact, the K bubbles and the dislocations which are pinned by these K bubbles can affect the morphology and evolution of hydrogen (H) and helium (He) atoms in the alloys. As a very sensitive method to detect vacancy-type defects in materials, positron annihilation spectroscopy is used to study the irradiation damage caused by H and He atoms in this paper. The calculation of positron lifetime shows that positrons are more sensitive to the vacancy-type defects. Bounding of H and He with vacancies reduces the positron lifetime because of the increase of valence electron density. Combining the calculated results with the positron annihilation lifetime spectrum (PLAS) results shows that the W-K alloy is easier to promote the H atoms to release. Besides, it also more likely to form larger He bubbles which can be estimated by positron lifetime values. The result is also confirmed by the measurements from the scanning electron microscope (SEM) and slow positron Doppler broadening spectroscopy (DBS). The defects in the W-K alloy such as K bubbles and their pinned dislocations can act as diffusion channels to promote the H atoms to release, which gives rise to a smoother surface under the pure H irradiation. Meanwhile, under the condition of the H+6%He irradiation, the K bubbles and their pinned dislocations in the W-K alloy become the capture center of He atoms, promote their nucleation and grow into larger He bubbles. Moreover, under the action of stress and temperature gradient, some of the He bubbles migrate to the surface and release, this process is conducive to the recovery of related defects and the reduction of radiation damage.
Experimental methodology of water cluster doping
Authors: Huang Chuan-Fu ,   School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, China
Published: June 2021

Water is one of the most common molecules in space and is also most valuable substance resource for living activities on earth. Studying water clusters plays an important role in actually utilizing water resources. Meanwhile, water clusters can be used as an ideal water microscopic model, which can expand the development of physical and chemical basic science, for example, it can provide the reference for investigating the size-dependent dissociation properties and interactions between solvents and solutes. On the other hand, the gas-phase mixed acidic water clusters have aroused great interest in recent years. For instance, One has been seeking for the smallest energy structure of pure water clusters and doped acidic molecular water clusters, experimentally and theoretically. In short, doping with foreign molecules or atoms can significantly enlarge the scope of scientific research on water clusters. Currently, there are many approaches to doping water clusters experimentally. This review briefly summarizes these means and compares the characteristics of various doping methods to help researchers to apply water cluster doping experiments more effectively.
Effect of substitution of S for Se on structure and physical properties in Ge11.5As24Se64.5–xSx glass
Authors: Xu Si-Wei , Yang Xiao-Ning , Yang Da-Xin , Wang Xun-Si , Shen Xiang ,   College of Mathematics and Physics, Hunan University of Arts and Science, Changde 415000, China,   Key Laboratory of Photoelectric Materials and Devices of Zhejiang Province, The Research Institute of Advanced Technologies, Ningbo University, Ningbo 315211, China
Published: June 2021

In this paper, chalcogenide glasses Ge11.5As24Se64.5–xSx (x = 0, 16.125%, 32.25%, 48.375% and 64.5%) are prepared and their optical properties are studied in order to select the best components for the use in optical devices. The values of laser damage threshold, refractive index, and third-order nonlinear refractive index, as well as the absorption spectra of the glasses are measured. The results show that the linear and third-order nonlinear refractive indices of the glass decrease gradually, the glass optical band gap increases gradually, and the laser damage threshold increases continuously after the high threshold component S atoms have been introduced gradually. We further investigate the structural origins of these changes in physical properties by Raman scattering spectra and high resolution X-ray photoelectron spectroscopy. By analyzing the evolution process of different structural units in the glass, it is found that the heteropolar bonds (Ge—Se/S, As—Se/S) are dominant in these glass network structures, and compared with Se, and that Ge and As prefer to bond with S. As the ratio of S/Se increases, the number of chemical bonds related to Se (Ge—Se, As—Se and Se—Se) decreases gradually, while the number of chemical bonds related to Se (Ge—S, As—S and S—S) increases gradually, which has little effect on the change of the topological structure of glass. It can be concluded that the main reason for the change of physical properties of glass is the difference of the strength between chemical bonds in the glass structural system.
Quenched solitons and shock waves in Bose-Einstein condensates
Authors: Jia Rui-Yu , Fang Ping-Ping , Gao Chao , Lin Ji ,   Department of Physics, Zhejiang Normal University, Jinhua 321004, China
Published: June 2021

The Bose-Einstein condensate (BEC) formed by ultracold atomic gases provides an ideal platform for studying various quantum phenomena. In this platform, researchers have explored in depth the important equilibrium and steady phenomena including superfluidity, vortices, and solitons, and recently started to study nonequilibrium problems. In a classical system, nonequilibrium problems, such as explosion, usually occur together with shock waves, which is presented when the explosion speed is larger than the local sound speed. For BEC systems which possess quantum properties, how to produce and understand the shock waves becomes a hot research topic. In this work, we systematically discuss the possibility of quantum shock wave and its essential mechanism in a one-dimensional BEC initially containing dark solitons through quenching interactions. When the system is quenched to the limit of non-interaction, we analytically obtain the post-quench dynamics of initially immobile dark solitons, and find the existence of shock wave, which can be explained through the quantum interference effect. When the system is quenched to finite interaction, we find similar phenomena through numerically solving the Gross-Pitaevskii equation, and analyze different situations. When the system is quenched to a finite weaker interaction, the situation is similar to a non-interaction case; when the system is quenched to a stronger interaction, the shock wave is accompanied by the splitting of the initial soliton, and the two objects can synchronously change; specifically when the quenched ratio of strength is an integer squared, the shock wave disappears, and the soliton is split perfectly. We further explore the properties of the shock wave including its amplitude and speed, and obtain the full scenario as the quenched interaction varies. This work provides theoretical guidance for realizing and measuring shock wave in experiment.
Investigation of ab initio nonadiabatic molecular dynamics of excited carriers in condensed matter systems
Authors: Zheng Zhen-Fa , Jiang Xiang , Chu Wei-Bin , Zhang Li-Li , Guo Hong-Li , Zhao Chuan-Yu , Wang Ya-Nan , Wang Ao-Lei , Zheng Qi-Jing , Zhao Jin ,   Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences,  ICQD/Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China, Hefei 230026, China,   Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh 15260, America
Published: June 2021

The excited state dynamics is always an important and challenging problem in condensed matter physics. The dynamics of excited carriers can have different relaxation channels, in which the complicated interactions between different quasi-particles come into play collectively. To understand such ultrafast processes, the ab initio investigations are essential. Combining the real-time time-dependent density functional theory with fewest switches surface hopping scheme, we develop time-dependent ab initio nonadiabatic molecular dynamics (NAMD) code Hefei-NAMD to simulate the excited carrier dynamics in condensed matter systems. Using this method, we investigate the interfacial charge transfer dynamics, the electron–hole recombination dynamics, and the excited spin-polarized hole dynamics in different condensed matter systems. Moreover, we combine ab initio nonadiabatic molecular dynamics with GW plus real-time Bethe-Salpeter equation for the spin-resolved exciton dynamics. We use it to study the spin-valley exciton dynamics in MoS2. It provides a powerful tool for exciton dynamics in solid systems. The state-of-the-art NAMD studies provide a unique insight into a understanding of the ultrafast dynamics of the excited carriers in different condensed matter systems on an atomic scale.
The push-to-open mechanism of the tethered mechanosensitive ion channel NompC
Authors: Wang Yang , Guo Yifeng , Li Guanluan , Liu Chunhong , Wang Lei , Zhang Aihua , Yan Zhiqiang , Song Chen
Published: June 2021

NompC is a mechanosensitive ion channel responsible for the sensation of touch and balance in Drosophila melanogaster. Based on a resolved cryo-EM structure, we performed all-atom molecular dynamics simulations and electrophysiological experiments to study the atomistic details of NompC gating. Our results showed that NompC could be opened by compression of the intracellular ankyrin repeat domain but not by a stretch, and a number of hydrogen bonds along the force convey pathway are important for the mechanosensitivity. Under intracellular compression, the bundled ankyrin repeat region acts like a spring with a spring constant of ~13 pN nm−1 by transferring forces at a rate of ~1.8 nm ps−1. The linker helix region acts as a bridge between the ankyrin repeats and the transient receptor potential (TRP) domain, which passes on the pushing force to the TRP domain to undergo a clockwise rotation, resulting in the opening of the channel. This could be the universal gating mechanism of similar tethered mechanosensitive TRP channels, which enable cells to feel compression and shrinkage.
Uncovering a ‘sensitive window’ of multisensory and motor neuroplasticity in the cerebrum and cerebellum of male and female starlings
Authors: Orije Jasmien , Cardon Emilie , Hamaide Julie , Jonckers Elisabeth , Darras Veerle M , Verhoye Marleen , Van der Linden Annemie
Published: June 2021

Traditionally, research unraveling seasonal neuroplasticity in songbirds has focused on the male song control system and testosterone. We longitudinally monitored the song behavior and neuroplasticity in male and female starlings during multiple photoperiods using Diffusion Tensor and Fixel-Based techniques. These exploratory data-driven whole-brain methods resulted in a population-based tractogram confirming microstructural sexual dimorphisms in the song control system. Furthermore, male brains showed hemispheric asymmetries in the pallium, whereas females had higher interhemispheric connectivity, which could not be attributed to brain size differences. Only females with large brains sing but differ from males in their song behavior by showing involvement of the hippocampus. Both sexes experienced multisensory neuroplasticity in the song control, auditory and visual system, and cerebellum, mainly during the photosensitive period. This period with low gonadal hormone levels might represent a ‘sensitive window’ during which different sensory and motor systems in the cerebrum and cerebellum can be seasonally re-shaped in both sexes.
Spatially displaced excitation contributes to the encoding of interrupted motion by a retinal direction-selective circuit
Authors: Ding Jennifer , Chen Albert , Chung Janet , Acaron Ledesma Hector , Wu Mofei , Berson David M , Palmer Stephanie E , Wei Wei
Published: June 2021

Spatially distributed excitation and inhibition collectively shape a visual neuron’s receptive field (RF) properties. In the direction-selective circuit of the mammalian retina, the role of strong null-direction inhibition of On-Off direction-selective ganglion cells (On-Off DSGCs) on their direction selectivity is well-studied. However, how excitatory inputs influence the On-Off DSGC’s visual response is underexplored. Here, we report that On-Off DSGCs have a spatially displaced glutamatergic receptive field along their horizontal preferred-null motion axes. This displaced receptive field contributes to DSGC null-direction spiking during interrupted motion trajectories. Theoretical analyses indicate that population responses during interrupted motion may help populations of On-Off DSGCs signal the spatial location of moving objects in complex, naturalistic visual environments. Our study highlights that the direction-selective circuit exploits separate sets of mechanisms under different stimulus conditions, and these mechanisms may help encode multiple visual features.
A new giant sauropod,Australotitan cooperensisgen. et sp. nov., from the mid-Cretaceous of Australia
Authors: Hocknull Scott A. , Wilkinson Melville , Lawrence Rochelle A. , Konstantinov Vladislav , Mackenzie Stuart , Mackenzie Robyn
Published: June 2021

A new giant sauropod,Australotitan cooperensisgen. et sp. nov., represents the first record of dinosaurs from the southern-central Winton Formation of the Eromanga Basin, Australia. We estimate the type locality to be 270–300 m from the base of the Winton Formation and compare this to the semi-contemporaneous sauropod taxa,Diamantinasaurus matildaeHocknull et al., 2009,Wintonotitan wattsiHocknull et al., 2009 andSavannasaurus elliottorumPoropat et al., 2016. The new titanosaurian is the largest dinosaur from Australia as represented by osteological remains and based on limb-size comparisons it reached a size similar to that of the giant titanosaurians from South America. Using 3-D surface scan models we compare features of the appendicular skeleton that differentiateAustralotitan cooperensisgen. et sp. nov. as a new taxon. A key limitation to the study of sauropods is the inability to easily and directly compare specimens. Therefore, 3-D cybertypes have become a more standard way to undertake direct comparative assessments. Uncoloured, low resolution, and uncharacterized 3-D surface models can lead to misinterpretations, in particular identification of pre-, syn- and post-depositional distortion. We propose a method for identifying, documenting and illustrating these distortions directly onto the 3-D geometric surface of the models using a colour reference scheme. This new method is repeatable for researchers when observing and documenting specimens including taphonomic alterations and geometric differences. A detailed comparative and preliminary computational phylogenetic assessment supports a shared ancestry for all four Winton Formation taxa, albeit with limited statistical support. Palaeobiogeographical interpretations from these resultant phylogenetic hypotheses remain equivocal due to contrary Asian and South American relationships with the Australian taxa. Temporal and palaeoenvironmental differences between the northern and southern-central sauropod locations are considered to explain the taxonomic and morphological diversity of sauropods from the Winton Formation. Interpretations for this diversity are explored, including an eco-morphocline and/or chronocline across newly developed terrestrial environments as the basin fills.
Understanding the Hazard Profile and Disaster Preparedness Levels of NABH Accredited Hospitals in North India: Evidence from a Cross-sectional Survey 2016
Authors: Yadav Nidhi , Vishwakarma Gayatri , Sodani Prahalad Rai , Kabbinahithlu Preetham , Anchalia Priyanka
Published: June 2021

Introduction: Implementation of quality management systems and accreditation is the best way to understand disaster preparedness of any hospital. The National Board of Hospitals and Healthcare providers (NABH) has laid down standards for hospital. These standards along with the Disaster Management Act 2005 give direction and guidelines to the hospitals for ensuring that hospital prepare for unprecedented events or disaster situations. Aim: To assess the influence of NABH accreditation on disaster preparedness and response of accredited hospitals of North India. Materials and Methods: A cross-sectional, ex-post facto research was conducted in accredited hospitals on North India to understand their level of disaster preparedness and response. Purposive sampling was done and nine hospitals were selected. A validated questionnaire was used to collect data on demographic and disaster profile including procedural, structural and non-structural elements. Statistical Package for the Social Sciences (SPSS) Version 22.0 was used for statistical analysis purpose. Results: Accreditation plays very important role in preparing the hospitals and curating their response towards a disaster event. This study found significant level of disaster preparedness in the accredited hospitals irrespective of the structural difference and age of the hospital. Conclusion: The 4th edition of NABH standards has its 8thChapter on Facility Management and Safety, this chapter has 7 Standards and 46 Objective elements. It guide the hospital regarding provision of safe and secure environment for patients, their families, staff and visitors. Accreditation is the best way to evaluate disaster preparedness of any hospital.
A Prospective Study on Respiratory Viral Pathogens Causing Acute Lower Respiratory Infections in Children below Five Years of Ageat a Tertiary Care Hospital of India
Authors: Raju Apoorva T , Das Rojaleen , Rai Nikki , Kumar Ajay , Gaind Rajni
Published: June 2021

Introduction: The lower respiratory tract infections are a major cause of mortality in children below five years of age. Majority of the time the infection is self-limiting but often gets severe and fatal depending on various factors like age, aetiology, time of diagnosis, appropriate treatment, etc. Aim: To study viral aetiology of Acute Lower Respiratory tract Infections (ALRI) using multiplex real time qualitative Polymerase Chain Reactions (qPCR) among hospitalised children under five years of age. Materials and Methods: This was a hospital based prospective study conducted over a period of two years from June 2015 to May 2017, a throat and nasal swab was collected from 512 children ≤5 years who were being hospitalised for ALRI. The samples were tested by multiplex qPCR to detect viral and p<0.05 was considered as statistically significant. Results: Out of 512 cases, 317 children were further studied. It was found that highest number of ALRI were observed in children of age less than six months i.e., 38.9% followed by 29.4%, 14.8% and 16.9% in the age group of 6-12 months, 12-24 months and 24-60 months, respectively. The one/more viral pathogens were detected in 58.3% (185/317) children. Respiratory Synctial Virus (RSV) was most common virus detected in 51.9% followed by Human Rhinovirus (HRV) in 23.2%. RSV was found to be statistically significant in infants and causes very severe ALRI. Conclusion: The use of multiplex qPCR has clarified the scenario of different respiratory viral aetiologies causing ALRI in different age group of children. The study results enhance knowledge for making strategy to prevent severity of ALRI in different age group, seasons and geographical area.
A Qualitative Assessment of Stress Among Frontline Health Workers During COVID-19 Pandemic
Authors: Sain Sonali , Mukherjee Shuvankar
Published: June 2021

Introduction: Being on the frontline, health care workers are most likely to get exposed to all kinds of stress in the ongoing Coronavirus-2019 pandemic. Both physical and mental stress could influence their well-being and also affect their work efficiency. There is a need of active intervention to restore and maintain the mental health of the frontline health workers. Thus, it is essential to gain an insight into their problems so that it would enable to identify appropriate solutions. Aim: To get an insight into the stress experienced by the COVID-19 community surveillance workers and to explore the perceptions of stress related trigger factors and coping strategies. Materials and Methods: This qualitative study was based on “Focus Group Discussion (FGD)” method and was associated with Nilratan Sircar Medical College & Hospital Kolkata. The participants were COVID-19 community surveillance workers who mainly comprised of “honorary health workers” and “100 days field workers (18-55 years)”, employed in 5 different urban health centers in the Kolkata corporation area during April to June 2020. A total of 55 participants were included in the study in five sessions. Researchers took notes during the session, which was also recorded verbatim. Discussions were mainly conducted over four key areas namely positive aspects of COVID-19 surveillance activities, stress related to surveillance activities, precipitating factors related to stress and coping strategies for these stressful periods. Data was summarised and analysed qualitatively. Results: Participants felt that “they provided service to the society and understood their importance in breaking the chain of transmission”. “This job gave them pride of being a part of health system along with income generation”. However, they also expressed about the stressful situation related to the surveillance activity like social ostracisation, verbal and even physical abuse. Inadequate supply of Personal Protective Equipment (PPE) was revealed. Most of the surveillance workers were informally trained thus they sought help for formal training for surveillance activity. Conclusion: Although the frontline health care workers felt proud to be involved in the surveillance work, almost all of them expressed apprehension against social stigmatisation, verbal and physical abuse. The need for formal training in surveillance work was evident.
Antimicrobial Potential of Sonneratia alba and Sonneratia caseolaris against Shrimp Pathogens
Authors: Pratiwi Dian Yuni
Published: June 2021

Disease is one of the obstacles in shrimp farming. Many countries have experienced economic losses due to disease in shrimp caused by microbes. Many strategies are being used to overcome the problem such as antibiotics, formalin, probiotics, prebiotics, synbiotics, and others. However, the use antibiotics in long term can cause negative effects. So that, the development of potential new natural compounds is required to overcome this problem. This review article aims to explain the nutritional content, bioactive compounds, antimicrobial potential, and the effect of S. alba and S. caseolaris on shrimp survival. Sonneratia alba and Sonneratia caseolaris are plants that have many bioactive compounds such as alkaloids, flavonoids, terpenoids, and phenolics. They have also been shown to inhibit the growth of bacteria such as Vibrio harveyi, Escherichia coli, Staphylococcus aureus, Saprolegnia sp., and others. Application of S. alba and S. caseolaris can also increase the survival rate of infected shrimps. S. alba and S. caseolaris have the potential to be used as antimicrobial agents and can be used to protect shrimp from microbial pathogens.
Prevalence of Extended-Spectrum β-Lactamase and Antimicrobial Susceptibility Pattern of Clinical Isolates of Pseudomonas in Tertiary Care Centre of Kutch
Authors: Kothari Krupali , Solanki Dolly
Published: June 2021

Aim: The current research was performed with an aim to discover the prevalence of ESBL producing P. aeruginosa and also to provide as a direct for doctors administration subjects by executing suitable infection control events as well as inventing an efficient antibiotic policy.

Materials and Methods: The current research was performed in the Department of Microbiology at Gujarat Adani Institute of Medical Science, Bhuj, Kutch, Gujarat over a period for one year. All 250 isolates of Pseudomonas aeruginosa acquired from different clinical samples established in microbiology laboratory from IPD & OPD were incorporated in the research. Different clinical specimens established in our laboratory were coursed and Pseudomonas aeruginosa was recognized as apiece normal microbiological method. All isolates were subjected for ESBL screening test. Antimicrobial susceptibility test was performed by Kirby.

Results: Highest samples established from middle age group (30- 50). Out of 250 isolates, 177 (70.7%) isolates of Pseudomonas aeruginosa demonstrated zone of inhibition≤ 22 mm for Ceftazidime. All ESBL positive Pseudomonas aeruginosa isolates demonstrated elevated confrontation to ciprofloxacin 43 (91.04%), Gentamicin 34 (72.3%) and tobramycin 33 (70.21%).

Conclusion: The majority of isolates were from hospitalized subjects which point out additional probability of their nosocomial predominance.