bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism of phonon scattering by under-coordinated atoms on surface
Authors: Huo Long-Hua , Xie Guo-Feng ,   School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, China,   Hunan Provincial Key Laboratory of Advanced Materials for New Energy Storage and Conversion, Hunan University of Science and Technology, Xiangtan 411201, China
Published: December 2020

Because of high surface-to-volume ratio (SVR), the most prominent size effect limiting thermal transport originates from the phonon-surface scattering in nanostructures. Here in this work, we propose the mechanism of phonon scattering by the under-coordinated atoms on surface, and derive the phonon scattering rate of this mechanism by quantum perturbation theory combined with bond order theory. The scattering rate of this mechanism is proportional to SVR, therefore the effect of this mechanism on phonon transport increases with the feature-size of nanostructures decreasing. Due to the ω4 dependence of scattering rate for this mechanism, the high-frequency phonons suffer a much stronger scattering than the low-frequency phonons from the under-coordinated atoms on surface. By incorporating this phonon-surface scattering mechanism into the phonon Boltzmann transport equation, we calculate the thermal conductivity of silicon thin films and silicon nanowires. It is found that the calculated results obtained with our model are closer to the experimental data than those with the classical phonon-boundary scattering model. Furthermore, we demonstrate that the influence of this phonon-surface scattering mechanism on thermal transport is not important at a very low temperature due to the Bose-Einstein distribution of phonons. However, with the increase of the temperature, more and more phonons occupy the high-frequency states, and the influence of this scattering mechanism on phonon transport increases. It is astonished that the phonon scattering induced by the under-coordinated atoms on surface is the dominant mechanism in governing phonon heat transport in silicon nanostructures at room temperature. Our findings are helpful not only in understanding the mechanism of phonon-surface scattering, but also in manipulating thermal transport in nanostructures for surface engineering.
Preparation methods and progress of experiments of quantum microwave
Authors: Miao Qiang , Li Xiang , Wu De-Wei , Luo Jun-Wen , Wei Tian-Li , Zhu Hao-Nan ,   Information and Navigation College, Air Force Engineering University, Xi'an 710077, China
Published: December 2020

Based on the characteristics of superposition, entanglement, non-locality and non-clonality of quantum mechanics, quantum information science can break through the physical limits of classical information and open up a new information processing function different from classical electromagnetic application methods. Due to the advantages of high-energy single photon in practical applications, the research and application of optical quantum information technology dominates the development of current quantum information technology. However, the free-space transmission of light waves is greatly affected by weather conditions and atmospheric particles. Comparing with other wave bands, classical microwave signal shows good penetration ability when transmitting in free space. By introducing quantum mechanics, microwave signal also exhibits non-classical merits. As quantum microwave signal inherits both classical transmission performance and quantum non-classical features, it can be utilized as a significant signal source for diverse applications in microwave domain, such as quantum communication, quantum navigation and quantum radar, which are based on quantum technologies in large scale and dynamic free space transmission. There are three main experimental platforms on which quantum microwave is studied and produced. They are cavity quantum electrodynamics(C-QED) system, circuit quantum electrodynamics(c-QED) system, and cavity electro-opto-mechanical(EOM) system, involving with several nonlinear effects such as Kerr effect, Casimir effect, three-wave mixing, etc. In this paper, the setups of these platforms and the preparation principles are introduced. Meanwhile, the preparation principles and methods of microwave single photon, entangled microwave photons, squeezed microwave fields and entangled microwave fields are summarized and analyzed in detail from three aspects. The present status of experimental progress in the relevant fields are summarized and listed as well. Besides, key problems in the application of quantum navigation in free space utilizing quantum microwave are probed. Among them, the most pressing ones are preparation ability, decoherence in transmission and detection of entangled quantum microwave signals, which are also discussed and analyzed in this paper. Finally, we look forward to the future development of quantum microwave technology. It mainly consists of manufacturing microwave detectors with high efficiency, designing thermal photon filters, and developing suitable antennas. We hope that this study can provide useful reference for scholars who are engaged in or interested in research related to quantum microwave technologies.
Two-dimensional wave equation solved by generalized alternating flux based local discontinuous Galerkin method
Authors: Zhang Rong-Pei , Wang Di , Yu Xi-Jun , Wen Xue-Bing ,   College of Mathematics and Systems Science, Shenyang Normal University, Shenyang 110034, China,   Institute of Applied Physics and Computational Mathematics, Beijing 100088, China
Published: December 2020

The wave propagation is often carried out in complex geological structures. Solving the wave propagation problem effectively in inhomogeneous medium is of great interest and has many applications in physics and engineering. In this paper, the local discontinuous Galekin (LDG) method is applied to the numerical solution of the second-order wave equation. Firstly, the auxiliary variables are introduced, and the second-order wave equations are written as a system of first-order partial differential equations. Then the discontinuous Galerkin format is applied to the corresponding linearized wave equations and adjoint equations. We consider the triangulation in this paper. In order to ensure that the discrete format satisfies the energy conservation, the generalized alternating flux is chosen on the element boundary. We proves that the LDG method satisfies the energy conservation. The exponential integral factor method is used in time discretization. In order to improve the computational efficiency, the Krylov subspace method is used to approximate the product of the exponential matrix and the vector. Numerical examples with exact solutions are given in numerical experiments. The numerical results verify the numerical precision and energy conservation of the LDG method. In addition, the calculation of inhomogeneous medium and complex computational regions are considered. The results show that the LDG method is suitable for simulation of complex structures and propagation in multi-scale structured medium.
Vorticity sign law in three-dimensional wake of bluff body at low Reynolds number
Authors: Lin Li-Ming ,   Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Bluff bodies possess many engineering applications. The flow past a bluff body is a classical issue in fluid mechanics. In most of previous studies, the role of streamwise vorticity is mainly stressed in three-dimensional wake flow, such as in the physical origin of streamwise vortices in the mode A, and the complete suppression of alternatively shedding Kármán vortices under the effect of geometric disturbances introduced in the bluff body. However, through the careful investigation of two examples above, the vertical vorticity actually plays a key role. Furthermore, there is a physical phenomenon, special relationship among dominant vorticity components with specific signs or vorticity sign law, occurring in the wake of a bluff body with geometric disturbances. In the present paper, through direct numerical simulations at low Reynolds numbers, such a phenomenon is summarized in two kinds of cylinders, i.e. basic straight cylinder and geometrically disturbed cylinder. Two typical cross-sections are examined, including the circular and square sections. Three sub-regimes (front surfaces, shear layers and wake) are mainly investigated. The numerical results show that two generalized vorticity sign laws exist in the wake of a bluff body. For example, the first sign law shows that the sign of streamwise vorticity is always the same as that of vertical vorticity in the upper shear layer, but opposite in the lower shear layer. The second sign law shows that the sign combination of three components of vorticity is always negative in the shear layers and wake. As for the physical mechanism of sign laws appearing in the present two kinds of cylinders, the main difference between the small perturbance which induces the natural three-dimensional instability and the geometric disturbance leads to the evolution of generated surface vorticity under the effect of inertial forces. These generalized sign laws have been already verified theoretically in the previous work recently. Moreover, sign laws also indicate that the different vortex-shedding patterns in the wake of different bluff bodies are inherently identical from the point of vorticity sign. Considering the physical fact that the wall is the only source of new vorticity in the present vortex dynamics, the theoretical results also indicate that the Π-type vortex with specific groups of vorticity components is a basic vortex pattern generated on the walls, once the three-dimensional wake first appears in the wake at low Reynolds number.
Coherence and path information
Authors: Lü Xin ,   School of Physics and Electrical Engineering, Liupanshui Normal University, Liupanshui 553000, China
Published: December 2020

Complementarity, or more specifically, the wave-particle duality, and quantum coherence are two fundamental concepts in quantum mechanics. Recently, motivated by the progress of the quantification of quantum coherence, the complementary relation between coherence and path information is investigated by many authors, and various duality relations between them are established. Such relations not only provide insights into fundamental problems of quantum mechanics, such as the understanding of quantum coherence and wave-particle duality; but also are important in applications of quantum technologies. In this paper, based on the Bures distance and unambiguous quantum state discrimination, systematic analysis of the complementarity between the quantum coherence and path information in two path interferometers is carried out. Similarly as other related works, the wave aspect, or the visibility of the interferometer, is quantified by the l1-norm measure of quantum coherence, and the path information is considered via unambiguous quantum state discrimination. In this way, a novel duality relation in two path interferometers is obtained. Compared with known results, our work considers mixed states as well as pure states; considers the path predictability resulting from the intrinsic path asymmetry of the quantum state, as well as the path distinguishability resulting from the use of a which-path detector. Therefore, our work systematically generalizes known results in two path interferometers by removing all the unnecessary restrictions. Specifically, the most general form of quantum states in two path interferometers is considered and the duality relation between quantum coherence and path information is proved based on the positivity property of density matrices. The cases of path predictability and path distinguishability are considered separately. For path predictability, the proof is straightforward; whereas some advanced mathematical techniques, such as the Schur-Weyl inequality, properties of the fidelity and properties of positive matrices, are required in order to give a rigorous proof of the duality relation between coherence and path distinguishability. Concrete examples are provided to illustrate the abstract method and results. Our work concerns about two path interferometers exclusively and depends heavily that the dimensionality is two, therefore it would be an interesting task to generalize the results in this paper to n-path interferometers.
Two-dimensional optical edge detection based on Pancharatnam-Berry phase metasurface
Authors: Xie Zhi-Qiang , He Yan-Liang , Wang Pei-Pei , Su Ming-Yang , Chen Xue-Yu , Yang Bo , Liu Jun-Min , Zhou Xin-Xing , Li Ying , Chen Shu-Qing , Fan Dian-Yuan ,   International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology, and Engineering Technology Research Center for 2D Material Information Function Devices and Systems of Guangdong Province, Shenzhen University, Shenzhen 518060, China,   College of New Materials and New Energies, Shenzhen Technology University, Shenzhen 518118, China,   Synergetic Innovation Center for Quantum Effects and Applications, School of Physics and Electronics, Hunan Normal University, Changsha 410081, China
Published: December 2020

With the rapid development of metasurface and metamaterials, the image edge detection based on the optical spatial differential calculation becomes an interesting topic in recent years. There have been a certain number of studies in this region, but most of them are applicable only to one-dimensional optical spatial differential calculation. In this work, a two-dimensional optical differentiator using Pancharatnam-Berry (P-B) phase metasurface is proposed and implemented in optical image two-dimensional edge detection. Based on the principle of the spin-dependent splitting from P-B phase devices, this metasurface is capable of separating the left-handed circularly polarized light from the right-handed circularly polarized light at a certain spatial distance. After filtering out the overlapped linear polarization, the left optical information is the result of the two-dimensional optical spatial differential. Meanwhile, the resolution of the image edge information is adjustable by changing the optic axis distribution of this two-dimensional optical differentiator. These results indicate that our P-B phase metasurface can be applied to the extraction of the optical image two-dimensional edge information, and the extracted edge information is more complete than the previous one-dimensional grating metasurface. For these advantages, this two-dimensional optical differentiator shows great potential applications in ultrafast optical calculation and image processing.
Study on the generation mechanism of bright and dark solitary waves and rogue wave for a fourth-order dispersive nonlinear Schrödinger equation
Authors: Li Min , Wang Bo-Ting , Xu Tao , Shui Juan-Juan ,   Department of Mathematics and Physics, North China Electric Power University, Beijing 102206, China,   College of Science, China University of Petroleum, Beijing 102249, China
Published: December 2020

In this paper, we study the generation mechanism of bright and dark solitary waves and rogue wave for the fourth-order dispersive nonlinear Schrödinger (FODNLS) equation, which can not only model the nonlinear propagation and interaction of ultrashort pulses in the high-speed optical fiber transmission system, but also govern the nonlinear spin excitations in the onedimensional isotropic biquadratic Heisenberg ferromagnetic spin with the octupole-dipole interaction. Firstly, via the phase plane analysis, we obtain both the homoclinic and heteroclinic orbits for the two-dimensional plane autonomous system reduced from the FODNLS equation. Further, we derive the bright and dark solitary wave solutions under the corresponding conditions, which reveals the relationship between the homoclinic (heteroclinic) orbit and solitary wave. Secondly, based on the exact first-order breather solution of the FODNLS equation over a nonvanishing background, we give the explicit expressions of group and phase velocities, and reveal that there exists a jump in both the velocities. Finally, in order to verify that the breather becomes a rogue wave at the jumping point, we obtain the first-order rogue wave solution by taking the limit of the breather solution at such point, which confirms the relationship of the generation of rogue wave with the velocity discontinuity.
Linking local connectivity to atomic-scale relaxation dynamics in metallic glass-forming systems
Authors: Wu Zhen-Wei , Wang Wei-Hua ,   School of Systems Science, Beijing Normal University, Beijing 100875, China,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

For a long time, it has been well recognized that there exists a deep link between the fast vibrational excitations and the slow diffusive dynamics in glass-forming systems. However, it remains as an open question whether and how the short-time scale dynamics associated with vibrational intrabasin excitations is related to the long-time dynamics associated with diffusive interbasin hoppings. In this paper we briefly review the research progress that addresses this challenge. By identifying a structural order parameter—local connectivity of a particle which is defined as the number of nearest neighbors having the same local spatial symmetry, it is found that the local connectivity can tune and modulate both the short-time vibrational dynamics and the long-time relaxation dynamics of the studied particles in a model of metallic supercooled liquid. Furthermore, it reveals that the local connectivity leads the long-time decay of the correlation functions to change from stretched exponentials to compressed ones, indicating a dynamic crossover from diffusive to hyperdiffusive motions. This is the first time to report that in supercooled liquids the particles with particular spatial symmetry can present a faster-than-exponential relaxation that has so far only been reported in out-of-equilibrium materials. The recent results suggest a structural bridge to link the fast vibrational dynamics to the slow structural relaxation in glass-forming systems and extends the compressed exponential relaxation phenomenon from earlier reported out-of-equilibrium materials to the metastable supercooled liquids.
Measurement of time-varying electron density of air spark shock wave plasma jet by the method of microwave Rayleigh scattering
Authors: Wu Jin-Fang , Chen Zhao-Quan , Zhang Ming , Zhang Huang , Zhang San-Yang , Feng De-Ren , Zhou Yu-Ming ,   College of Electrical & Information Engineering, Anhui University of Technology, Key Laboratory of Power Electronics and Electrical Drive in Anhui Province, Maanshan 243032, China
Published: December 2020

It is difficult in measuring the electron density of an atmospheric air spark shock wave plasma jet, due to its variation on the time scale of sub-microseconds. In this paper, the time-varying electron density of air spark shock wave plasma jet is measured, based on the principle of microwave Rayleigh scattering. The system constant A is determined by using calibration of materials with known properties; the results show that the system constant is obtained as A = 1.04 × 105 V·Ω·m–2. According to the principle of microwave Rayleigh scattering, the electron density of the plasma jet is related to its radius and length of the plasma jet plume. Combined with the discharge image captured by ICCD camera, it is observed that the plasma jet plumes are with irregular patterns. In order to facilitate the calculation, the plasma jet plumes are replaced by cylinders with the same volume as the original shapes. Thus, the equivalent radius and length of the plasma jet plume are obtained. According to the known data, the electron density is determined to be in the order of 1020 m–3; its value increases rapidly to the peak value, and after then exponential attenuates along with time. In addition, the effect of different equivalent dimensions of the plasma jet plume on the measurement results is also discussed. It is shown that the calculation result with the time-varying equivalent radius and the time-varying equivalent length is the most effective one. In addition, the first fast peak is caused by the ionization wave of the photo ionization. The actual ionization process is that the air discharge in the cathode cavity releases a large number of high energy photons, which pass through the cathode nozzle and project into the region outside the nozzle; and then the O2 molecule in the ambient air are ionized by those high energy photons to form the plasma jet plume at the time of 1 μs.
Partial synchronization in complex networks: Chimera state, remote synchronization, and cluster synchronization
Authors: Wang Zhen-Hua , Liu Zong-Hua ,   School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
Published: December 2020

In recent years, the study of partial synchronization of coupled oscillators in complex networks has attracted great attention. The underlying reason is both the extensive existence of the patterns of partial synchronization in brain network and their close relationship to brain functions of cognition and memory. In this paper, we briefly review the research progress in this field. According to the researches by different groups, we classify them as three types, i.e. chimera state, remote synchronization, and clustering synchronization. We mainly discuss the conditions of these three states, as well as their models, detections, and their applications in biology. We discuss the relationship among the three types of states and give some outlooks for future studies.
Analysis on early spatiotemporal transmission characteristics of COVID-19
Authors: Wang Cong , Yan Jie , Wang Xu , Li Min ,   Department of Computer Science & Technology, Sichuan Police College, Luzhou 646000, China,   Institute of Sichuan Police Science, Sichuan Police College, Chengdu 610200, China,   Department of Road Traffic Management, Sichuan Police College, Luzhou 646000, China,   School of Movie and Media, Sichuan Normal University, Chengdu 610068, China,   School of Computer Science, Sichuan Normal University, Chengdu 610068, China
Published: December 2020

 In this paper, a simple susceptible-infected (SI) model is build for simulating the early phase of COVID-19 transmission process. By using the data collected from the newest epidemiological investigation, the parameters of SI model is estimated and compared with those from some other studies. The population migration data during Spring festival in China are collected from Baidu.com and also extracted from different news sources, the migration characteristic of Wuhan city in the early phase of the epidemic situation is captured, and substituted into a simple difference equation model which is modified from the SI model for supporting migrations. Then several simulations are performed for the spatiotemporal transmission process of COVID-19 in China. Some conclusions are drawn from simulations and experiments below.

 1) With 95% confidence, the infection rate of COVID-19 is estimated to be in a range of 0.2068–0.2073 in general situation, and the corresponding basic reproduction number R0 is estimated to be in a range of 2.5510–2.6555. A case study shows that under an extreme condition, the infection rate and R0 are estimated to be 0.2862 and 3.1465, respectively.

 2) The Pearson correlation coefficient between Baidu migration index and the number of travelers sent by railway is 0.9108, which indicates a strong linear correlation between them, thus it can be deduced that Baidu migration index is an efficient tool for estimating the migration situation.

 3) The epidemic arrival times for different provinces in China are estimated via simulations, specifically, no more than 1 day within an estimation error of 41.38%; no more than 3 days within an error of 79.31%, and no more than 5 days with an error of 95.55%. An average estimation error is 2.14 days.
Quantization condition of scarring states in complex soft-wall quantum billiards
Authors: Li Xiao-Liang , Chen Xian-Zhang , Liu Chen-Rong , Huang Liang ,   School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
Published: December 2020

Quantum scar is an intriguing phenomenon in quantum or wave dynamics that the wavefunction takes an exceptionally large value around an unstable periodic orbit. It has attracted much attention and advances the understanding of the semiclassical quantization. Most of previous researches involving quantum scars focus on hard-wall quantum billiards. Here we investigate the quantum billiard with a smooth confinement potential which possesses complex classical dynamics. We demonstrate that the semiclassical quantization approach works well for both the stable and unstable classical periodic orbit, besides the fact that the shape of the orbits varies as the energy increases or even the stability switches. The recurrence rule of the quantum scars in this complex solf-wall billiard differs from that of the hard-wall nonrelativistic quantum billiard, such as being equally spaced in energy instead of being equally spaced in the square root of energy. These results implement the previous knowledge and may be used for understanding the measurements of density of states and transport properties in two-dimensional electron systems with random long-range impurities.
Collective behaviors of self-propelled rods under semi-flexible elastic confinement
Authors: Zhong Ying , Shi Xia-Qing ,   Center for Soft Condensed Matter Physics and Interdisciplinary Research, School of Physical Science and Technology, Soochow University, Suzhou 215006, China
Published: December 2020

In biological active systems there commonly exist active rod-like particles under elastic confinement. Here in this work, we study the collective behavior of self-propelled rods confined in an elastic semi-flexible ring. By changing the density of particles and noise level in the system, It is clearly shown that the system has an ordered absorbing phase-separated state of self-propelled rods and the transition to a disordered state as well. The radial polar order parameter and asphericity parameter are characterized to distinguish these states. The results show that the gas density near the central region of the elastic confinement has a saturated gas density that co-exists with the absorbed liquid crystal state at the elastic boundary. In the crossover region, the system suffers an abnormal fluctuation that drives the deformation of the elastic ring. The non-symmetric distribution of particles in the transition region contributes significantly to the collective translocation of the elastic ring.
Temporal filtering characteristics of gated InGaAs/InP single-photon detectors for coincidence measurement
Authors: Jin Ya-Qing , Dong Rui-Fang , Quan Run-Ai , Xiang Xiao , Liu Tao , Zhang Shou-Gang ,   Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, China,   School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Semiconductor single-photon avalanche detectors (SPADs) have played an important role in practical quantum communication technology due to their advantages of small size, low cost and easy operation. Among them, InGaAs/InP SPADs have been widely used in fiber-optic quantum key distribution systems due to their response wavelength range in a near-infrared optical communication band. In order to avoid the influence of dark count and afterpulsing on single photon detection, the gated quenching technologies are widely applied to the InGaAs/InP SPADs. Typically, the duration of gate pulse is set to be as short as a few nanoseconds or even less. As the detection of the arrival of single photons depends on the coincidence between the arrival time of gate pulse and the arrival time of photon, the gate pulse duration of the InGaAs/InP SPADs inevitably affects the effective detection of the single photons. Without the influence of dispersion, the temporal width of the transmitted photons is usually on the order of picoseconds or even less, which is much shorter than the gate width of the InGaAs/InP SPAD. Therefore, the gate width normally has no influence on the temporal measurement of the detected photons. However, in quantum systems involving large dispersion, such as the long-distance fiber-optic quantum communication system, the temporal width of the transmitted photons is significantly broadened by the experienced dispersion so that it may approach to or even exceed the gate width of the single-photon detector. As a result, the effect of the gate width on the recording of the arrival time of the dispersed photons should be taken into account. In this paper, the influence of the gate width coupled to the InGaAs/InP single photon detectors on the measurement of the two-photon coincidence time width is studied both theoretically and experimentally. The theoretical analysis and experimental results are in good agreement with each other, showing that the finally measured coincidence time width of the two-photon state after dispersion is not more than half of the effective gate pulses width. The maximum observable coincidence time width based on the gated single photon detector is fundamentally limited by the gate width, which restricts its applications in quantum information processing based on the two-photon temporal correlation measurement.
Comprehension of computer code relies primarily on domain-general executive brain regions
Authors: Ivanova Anna A , Srikant Shashank , Sueoka Yotaro , Kean Hope H , Dhamala Riva , O'Reilly Una-May , Bers Marina U , Fedorenko Evelina
Published: December 2020

Computer programming is a novel cognitive tool that has transformed modern society. What cognitive and neural mechanisms support this skill? Here, we used functional magnetic resonance imaging to investigate two candidate brain systems: the multiple demand (MD) system, typically recruited during math, logic, problem solving, and executive tasks, and the language system, typically recruited during linguistic processing. We examined MD and language system responses to code written in Python, a text-based programming language (Experiment 1) and in ScratchJr, a graphical programming language (Experiment 2); for both, we contrasted responses to code problems with responses to content-matched sentence problems. We found that the MD system exhibited strong bilateral responses to code in both experiments, whereas the language system responded strongly to sentence problems, but weakly or not at all to code problems. Thus, the MD system supports the use of novel cognitive tools even when the input is structurally similar to natural language.
Transport mechanism of P4 ATPase phosphatidylcholine flippases
Authors: Bai Lin , You Qinglong , Jain Bhawik K , Duan H Diessel , Kovach Amanda , Graham Todd R , Li Huilin
Published: December 2020

The P4 ATPases use ATP hydrolysis to transport large lipid substrates across lipid bilayers. The structures of the endosome- and Golgi-localized phosphatidylserine flippases—such as the yeast Drs2 and human ATP8A1—have recently been reported. However, a substrate-binding site on the cytosolic side has not been found, and the transport mechanisms of P4 ATPases with other substrates are unknown. Here, we report structures of theS. cerevisiaeDnf1–Lem3 and Dnf2–Lem3 complexes. We captured substrate phosphatidylcholine molecules on both the exoplasmic and cytosolic sides and found that they have similar structures. Unexpectedly, Lem3 contributes to substrate binding. The conformational transitions of these phosphatidylcholine transporters match those of the phosphatidylserine transporters, suggesting a conserved mechanism among P4 ATPases. Dnf1/Dnf2 have a unique P domain helix-turn-helix insertion that is important for function. Therefore, P4 ATPases may have retained an overall transport mechanism while evolving distinct features for different lipid substrates.
Torsin ATPases influence chromatin interaction of the Torsin regulator LAP1
Authors: Luithle Naemi , de Bos Jelmi uit , Hovius Ruud , Maslennikova Daria , Lewis Renard TM , Ungricht Rosemarie , Fierz Beat , Kutay Ulrike
Published: December 2020

The inner nuclear membrane is functionalized by diverse transmembrane proteins that associate with nuclear lamins and/or chromatin. When cells enter mitosis, membrane-chromatin contacts must be broken to allow for proper chromosome segregation; yet how this occurs remains ill-understood. Unexpectedly, we observed that an imbalance in the levels of the lamina-associated polypeptide 1 (LAP1), an activator of ER-resident Torsin AAA+-ATPases, causes a failure in membrane removal from mitotic chromatin, accompanied by chromosome segregation errors and changes in post-mitotic nuclear morphology. These defects are dependent on a hitherto unknown chromatin-binding region of LAP1 that we have delineated. LAP1-induced NE abnormalities are efficiently suppressed by expression of wild-type but not ATPase-deficient Torsins. Furthermore, a dominant-negative Torsin induces chromosome segregation defects in a LAP1-dependent manner. These results indicate that association of LAP1 with chromatin in the nucleus can be modulated by Torsins in the perinuclear space, shedding new light on the LAP1-Torsin interplay.
Association and dissociation between the mitochondrial Far complex and Atg32 regulate mitophagy
Authors: Innokentev Aleksei , Furukawa Kentaro , Fukuda Tomoyuki , Saigusa Tetsu , Inoue Keiichi , Yamashita Shun-ichi , Kanki Tomotake
Published: December 2020

Mitophagy plays an important role in mitochondrial homeostasis. In yeast, the phosphorylation of the mitophagy receptor Atg32 by casein kinase 2 is essential for mitophagy. This phosphorylation is counteracted by the yeast equivalent of the STRIPAK complex consisting of the PP2A-like protein phosphatase Ppg1 and Far3-7-8-9-10-11 (Far complex), but the underlying mechanism remains elusive. Here we show that two subpopulations of the Far complex reside in the mitochondria and endoplasmic reticulum, respectively, and play distinct roles; the former inhibits mitophagy via Atg32 dephosphorylation, and the latter regulates TORC2 signaling. Ppg1 and Far11 form a subcomplex, and Ppg1 activity is required for the assembling integrity of Ppg1-Far11-Far8. The Far complex preferentially interacts with phosphorylated Atg32, and this interaction is weakened by mitophagy induction. Furthermore, the artificial tethering of Far8 to Atg32 prevents mitophagy. Taken together, the Ppg1-mediated Far complex formation and its dissociation from Atg32 are crucial for mitophagy regulation.
Canines and carnassials as indicators of sociality in durophagous hyaenids: analyzing the past to understand the present
Authors: Pérez-Claros Juan Antonio , Coca-Ortega Carlos
Published: December 2020

We analyzed the lower and upper dentition of the family Hyaenidae along its evolutionary history from a multivariate point of view. A total of 13,103 individual measurements of the lengths and widths of canines and the main post-canine teeth (lower third and fourth premolar, lower first molar, and upper second, third, and fourth premolars) were collected for 39 extinct and extant species of this family. We analyzed these measurements using principal component analyses. The multivariate structure characterized the main groups of previously defined hyaenid ecomorphs. Strikingly, our analyses also detected differences between social hunting durophages (such asCrocuta crocuta) and solitary scavengers (such asHyaena hyaenaorParahyaena brunnea). Concerning the hyaenid bauplan, social hunters have large carnassials and smaller canines, whereas solitary scavengers show the exact opposite morphological adaptations. Additionally, scavengers exhibited upper canines larger than lower ones, whereas hunters have upper and lower canines of similar size. It is hypothesized that sociality has led to an increase in carnassial length for hunting durophages via scramble competition at feeding. Such competition also penalizes adults from bringing food to cubs, which are consequently breastfed. On the other hand, it is also hypothesized that natural selection has led to solitary scavengers having large canines to transport carcasses to cubs. Our results indicate that these functional aspects are also better reflected by lower teeth than the upper dentition, which leads to a mosaic evolution.
Pectin Strength of Common Varieties of Plantain Peels Used in the Production of Jam/Marmalade
Authors: Akusu O. M. , Chibor B. S.
Published: December 2020

The pectin strength of peels from four plantain cultivars; Horn Plantain (sample B), French Plantain (sample C), False horn Plantain (sample D), and French Horn Plantain (sample E) and its effect on Jam and Marmalade produced was investigated. Pectin was extracted from the plantain peels with distilled water and EDTA at pH 4.3 and 60°C, precipitated with acidified ethyl alcohol and 0.5N HCl. The pectin strength of peels from the French plantain (sample B) was higher than the others. Peels from False horn and French horn plantain both had medium pectin strength. Jam and marmalade produced were evaluated for proximate composition, chemical properties and acceptability. Jam and Marmalade from sample C were high in moisture content with mean values of 43.19 and 41.33%, respectively. Sample E (in both variants) had significant high crude protein (0.33%) compared to all other samples. Marmalade samples had crude fiber values ranging from 0.75% for sample B to 2.25% for sample E. The ash and carbohydrate content of jam and marmalade produced with pectin from French Plantain, False Horn Plantain and French Horn Plantain were significantly higher than the commercial jam and marmalade. Crude fat ranged from 0.45 to 1.15% for both variants (jam and marmalade). They both recorded low protein contents ranging from 0.14 to 0.32% and 0.16 to 0.33% respectively but high carbohydrate content ranging from 50.97 to 67.48% and 52.29 to 69.41% respectively. pH content maintains 3.0-3.10% for all samples. Total sugar content ranged from 55.00 to 63.80% for both Jam and Marmalade. Sample C was most preferred in terms of colour, taste, aroma, appearance, spreadability and overall acceptability, for Jam and Marmalade. All its sensory attributes were compared favorably with the commercial brands. Pectin extracted from plantain peel is strongly recommended for use as gelling agent in Jam and Marmalade production.
Using Instructional Materials to Overcome Students’ Difficulties in Solving Problems Related to Pyramids
Authors: Obeng Awudu , Agyeman Godwin Onwona- , Nkrumah Collin Fordjour
Published: December 2020

This paper remedies the inability of visual Art 2 students of Komfo Anokye Senior High School, Kumasi in calculating the perpendicular height correctly in a given pyramid and further use it to find the volume of the pyramid. Designed instructional materials were used to review the basic concepts like Pythagoras theorem before using activity method in teaching the actual topic- volume of a pyramid.

A pre-test was conducted to identify the specific areas for development and a post-test to assess the effectiveness of the intervention scheme. A sample of fifty students was selected from visual Art 2 of the school. The study concluded with suggestions and recommendations for the effective use of appropriate teaching and learning materials for positive results in teaching of mensuration especially, pyramids.
Purification and Characterization of a Thermostable Chitinase Produced by a Fungus Isolated from Fruit Tree Rhizosphere
Authors: Afolayan I. A. , Oyun J. F. , Ekundayo E. A. , Ekundayo F. O.
Published: December 2020

This study reveals the chitinase producing ability of some fungi isolates cultured from the rhizosphere of different fruit trees such as mango, cassava, guava, and banana inside FUTA farm. A total of 16 isolates identified as Aspergillus nidulans, A. niger, A.flavus, A. fumigatus, A. ripens, Trichoderma viride, Mucor mucedo, Penicillium frequentans, Rhizopus stolonifer, Paecilomyces fumosoroseus, Gibbelula suffulfa and Geotrichum albidum were obtained and screened for chitinolytic activity. The effect of cultural conditions such as pH, temperature, metal ion, nitrogen source and carbon source was determined on Aspergillus nidulans, being the best chitinase producer. Further, the chitinase produced by Aspergillus nidulans was concentrated by ammonium sulphate precipitation and purified consecutively by gel filtration and ion-exchange chromatography. The optimum pH and temperature for chitinase activity and stability were examined as well as the effect of metal ions on the enzyme activity. The enzyme was most active at pH 7.0 and it was relatively stable at pH 4.0 - 9.0 retaining over 60% of initial activity after 120 min of incubation. The enzyme was most active at 50°C, possessing high thermal stability at high temperature of 70°C. The purified chitinase was significantly inactivated at 80°C and almost completely at 90°C when it was pre-incubated at these temperatures for 60 min. The enzyme was strongly inhibited by FeSO4, ZnCl2 and MnCl2 and was less sensitive to CaCl2 and KCl. This purified Aspergillus nidulans chitinase can be used as a catalyst for the degradation of chitin-containing compounds.
Impact of Lockdown amid COVID-19 Pandemic on Temperature and Rainfall in Sub-Himalayan Ranges of Jammu & Kashmir Union Territory, India
Authors: Singh Mahender , Vikas Vishaw , Dadhich Sushmita M. , Sharma Rohit
Published: December 2020

The study was conducted to evaluate the effect of lockdown on temperature and rainfall in sub-Himalayan ranges i.e. Foothills of NW Shivaliks and Pir Panjal ranges of Jammu & Kashmir Union Territory, India. The statistical analysis inferred that due to the implementation of complete lockdown in region amid COVID-19 pandemic has brought reductions in day temperature in foothills of NW Shivaliks by 10.29% and 2.20% compared to year 2018 and 2019 respectively. While under Pir Panjal range the reduction in day temperature was found to be significant by 6.08% and 4.13%. Also evaluation of night temperature values revealed the significant reductions by 10.29% and 2.20% as compared to year 2018 and 2019 in foothills of NW Shivaliks and 10.37%, 5.93% in Pir Panjal. The Rainfall also increased in both sub-Himalayan ranges during this period and it was >100% and 70.25% under foothills of NW Shivaliks, 34.6% and 100% under Pir Panjal range. Hence the present study highlighted a plausible impact of lockdown on the weather parameters of the region, making it an efficient tool to mitigate the pace of regional changing climatic patterns for long term sustainability, productivity and for better soil, plant and animal health.
Combining Ability Studies for Identifying High Sugar Yielding Sweet Sorghum [Sorghum bicolor (L.) Moench] Genotypes
Authors: Nandeshwar B. C. , Biri Beka , Dugassa Alemayehu
Published: December 2020

Combining ability analysis provides information about the gene action involved in the expression of a trait and facilitates breeding of superior cultivars. Hence, 45 hybrids evolved from 10 parent half-diallel were evaluated for combining ability to identify good general combiners and superior cross combinations for high ethanol yield from sweet sorghum. RSSV-21-2 has been identified as the best general combiner. It can be used in pedigree breeding programme for the incorporation of desired traits for enhancing ethanol yield. ARS-SS-35-1 × NSS-218 and ARS-SS-83 × NSS-221-2 have been identified as the best specific combinations. These could be exploited in heterosis breeding programme.
Yulin Children's Hospital's Response to COVID-19 Epidemic Prevention and Control Measures and Effects
Authors: Huirong Li
Published: December 2020

Objective: Introduce the prevention and control measures and effects during COVID-19, and provide a basis for strengthening the emergency response ability of children's hospitals to respond to public health emergencies.

Methods: Introduced the epidemic prevention and control measures of the Children's Hospital of Yulin City, Shaanxi Province from January 22 to July 31, and summarize the prevention and control effects

Results: During this period, according to the relevant national guidelines and regulations, the hospital established a reasonable hospital management model, formulated scientific prevention and control plans, and introduced effective prevention and control measures, realizing zero infection among front-line medical workers, zero spread of the epidemic in the hospital, and zero death among confirmed patients in the hospital.

Conclusion: The prevention and control work of Yulin Children's hospital has comprehensive overall deployment and effective prevention and control measures, which has certain reference significance for the prevention and control work of large comprehensive children's specialized hospitals.
Dietary Enrichment with Omega -3 Fatty Acid Potentiates Leptin Permeability through the Blood-Brain Barrier in Wistar Rats
Authors: Taiwo Ebuehi, Osaretin Albert , Enioluwayan Oyegoke, , Mulkah Ajagun-Ogunleye, Olufemi , Adebola Olu-Taiwo,
Published: December 2020

Obesity is an excessive accumulation of fat which causes several health implications. It is a risk factor for most disabilities and non-communicable diseases such as cardiovascular diseases, diabetes, cancer, neurodegenerative diseases, etc. The present study aimed to show the effect of short and long-term supplementation of an enriched diet with different concentrations of omega-3 fatty acid on cerebrospinal fluid (CSF), and serum leptin ratio, adiposity and lipid profile in albino Wistar rats. Serum-leptin ratios and indicators such as lipid profile, feed consumption, and adiposity index were obtained to ascertain the effect of the enriched diet on health and wellness. Forty Wistar rats divided into four groups of ten were used, comprising of five males and females; Groups A, B, C and D. The group A, the control, was fed with rat chow and water alone. Groups B, C and D were fed with rat chow supplemented with 10%, 20% and 40% omega-3 fatty acid respectively. The permeability of the blood-brain barrier (BBB) with leptin significantly increased across the experimental groups in a concentration-dependent manner.

Practical Applications: Omega-3-fatty acids, also called polyunsaturated fatty acids are well known for their cardioprotective properties. ALA, α-linoleic acid, eicosapentanoic acid (EPA), and docosahexanoic acid (DHA) have been collectively referred to as omega-3 fatty acids. ALA, an essential fatty acid, can be converted into EPA and DHA. These polyunsaturated fatty acids (PUFA) are obtained from fish-oil and other kinds of seafood. Dietary consumption is essential for a better blood lipid profile and reduced risk for cardiovascular disease. In the present study, supplementation with omega-3 fatty acids improved blood-lipid profile, increased HDL which are essential in preventing obesity. Equally reported here is that concentrations of serum-leptin and CSF were used to derive the leptin ratio. There was also a significant decrease in the adiposity index across the groups. The feed consumption and CSF leptin were given as r=-0.46 for the short term diet, while r=0.34 for the long term diet group. Data of the study indicate that omega-3 fatty acid enrichment had a diminishing effect on both adiposity and appetite, but enhanced the permeability of leptin through the blood-brain barrier in the Wistar rats. The relevance of this study is that omega-3-fatty acid food supplementation could aid in weight management and assist in the prevention and control of obesity.