bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and optimization of an advanced time-of-flight neutron spectrometer for deuterium plasmas of the large helical device
Authors: Zhang Yimo , Ge Lijian , Hu Zhimeng , Sun Jiaqi , Li Xiangqing , Ogawa Kunihiro , Isobe Mitsutaka , Sangaroon Siriyaporn , Liao Longyong , Yang Danke , Gorini Giuseppe , Nocente Massimo , Tardocchi Marco , Fan Tieshuan
Published: May 2021

A time-of-flight neutron spectrometer based on the Time-Of-Flight Enhanced Diagnostic (TOFED) concept has been designed and is under development for the Large Helical Device (LHD). It will be the first advanced neutron spectrometer to measure the 2.45 MeV D–D neutrons (DDNs) from helical/stellarator plasmas. The main mission of the new TOFED is to study the supra-thermal deuterons generated from the auxiliary heating systems in helical plasmas by measuring the time-of-flight spectra of DDN. It will also measure the triton burnup neutrons (TBNs) from the d+t reactions, unlike the original TOFED in the EAST tokamak. Its capability of diagnosing the TBN ratios is evaluated in this work. This new TOFED is expected to be installed in the basement under the LHD hall and shares the collimator with one channel of the vertical neutron camera to define its line of sight. The distance from its primary scintillators to the equatorial plane of LHD plasmas is about 15.5 m. Based on Monte Carlo simulation by a GEANT4 model, the resolution of the DDN energy spectra is 6.6%. When projected onto the neutron rates that are typically obtained in LHD deuterium plasmas (an order of 1015 n/s with neutral beam injection), we expect to obtain the DDN and TBN counting rates of about 2.5 · 105 counts/s and 250 counts/s, respectively. This will allow us to analyze the DDN time-of-flight spectra on time scales of 0.1 s and diagnose the TBN emission rates in several seconds with one instrument, for the first time in helical/stellarator plasmas.
The acceleration of charged particles and formation of power-law energy spectra in nonrelativistic magnetic reconnection
Authors: Li Xiaocan , Guo Fan , Liu Yi-Hsin
Published: May 2021

Magnetic reconnection is a primary driver of particle acceleration processes in space and astrophysical plasmas. Understanding how particles are accelerated and the resulting particle energy spectra are among the central topics in reconnection studies. We review recent advances in addressing this problem in nonrelativistic reconnection that is relevant to space and solar plasmas and beyond. We focus on particle acceleration mechanisms, particle transport due to 3D reconnection physics, and their roles in forming power-law particle energy spectra. We conclude by pointing out the challenges in studying particle acceleration and transport in a large-scale reconnection layer and the relevant issues to be addressed in the future.
Design principles for achieving red emission in Eu2+/Eu3+ doped inorganic solids
Authors: Qiao Jianwei , Xia Zhiguo
Published: May 2021

Rare earth (RE) ions activated inorganic phosphors with multi-color emissions have received considerable attention because of their emerging applications in solid-state lighting, backlight displays, lasers, biomedical imaging, and so on. This tutorial review concerns the design principles for Eu2+ and Eu3+ activated red-emitting inorganic solids and highlights the influencing factors on the luminescence performance. Based on the recent advances in structural design of inorganic RE phosphors, we proposed several design principles for achieving red emission in Eu2+/Eu3+ ions doped solid-state materials. On the one hand, for the realization of red emission from Eu2+ ion, the used strategies include the following: (1) designed synthesis of new Eu2+-doped nitride or sulfide phosphors, (2) anionic substitution achieves large centroid shift, (3) Eu2+ occupies polyhedrons with small coordination numbers to obtain large ɛcfs, (4) doping concentration controls the distribution of Eu2+ ions, (5) mixed ligands induce large ΔS, and (6) doping Eu2+ in nitrides with UCr4C4-type structure to achieve narrow-band red emission. On the other hand, for the red emission originating from a Eu3+ ion, the design principles are listed as follows: (i) designed synthesis of Eu3+-doped phosphors with small CT energy, (ii) realization of low excitation energy by doping sensitizer ions, (iii) Eu3+ luminescence enhancement by charge compensation, and (iv) occupation of unsymmetrical sites to maintain high color purity of Eu3+. Finally, we discuss and look at the future opportunities for Eu2+/Eu3+ activated red phosphors.
Effect of temperature anisotropy on residual zonal flow level
Authors: Cho Y. W. , Hahm T. S.
Published: May 2021

Residual level (RZF) of long wavelength zonal flows in high aspect ratio collisionless toroidal plasma with a bi-Maxwellian distribution is calculated using the modern bounce-kinetic theory of neoclassical polarization density [L. Wang and T. S. Hahm, Phys. Plasmas 16, 062309 (2009)]. The result which generalizes the well-known formula for the Maxwellian distribution function [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)], RZF=[1+1.63q2ϵ−1/2(T⊥/T∥)3/2]−1, shows a strong dependence on the temperature ratio. Here T⊥ and T∥ are the temperatures in the perpendicular and parallel directions with respect to magnetic field, ϵ is the local inverse aspect ratio, and q is the safety factor. This scaling can be understood from the scalings of barely trapped/passing particles' population fraction and their radial orbit width as well as those of the second adiabatic invariant and the bounce/transit frequency.
Effects of Ca doping on the crystallization kinetics of GeTe
Authors: Wang Chenfei , Yao Guanjun , Liu Juncheng , Mao Yuanen , Leng Wenhao , Chen Yimin , Shen Xiang , Wang Jun-Qiang , Wang Rongping
Published: May 2021

Doping is an effective way to improve the performance of conventional phase-change materials. We introduced an alkaline element calcium (Ca) in GeTe films and studied their crystallization kinetics by using flash DSC. It was found that a small amount of Ca doping (4.0 at. %) can significantly enhance the thermal stability, but the maximum crystal growth rate does not decrease significantly. Moreover, no any Ca-related crystalline phase and Ca-related chemical bond can be found in Ca-doped GeTe, implying that Ca atoms are in free state in GeTe matrix.
Effect of Ca2+ - Si4+ on Y3Al5O12:Ce ceramic phosphors for white laser-diodes lighting
Authors: Ding Hui , Hu Pan , Liu Zehua , Sun Peng , Liu Yongfu , Luo Zhaohua , Chao Kefu , Jiang Haochuan , Jiang Jun
Published: May 2021

Y2.985-xCe0.015CaxAl5-xSixO12 (YAG:1.5%Ce+xCS) ceramic phosphors (CPs) were synthesized by a vacuum sintering method. The addition of CaCO3 and SiO2 significantly reduces the sintering temperature of CPs. The effects of Ca2+ - Si4+ on luminescent properties and microstructures of YAG:Ce CPs are discussed. The Ca2+ - Si4+ cannot be completely dissolved in the YAG:Ce CPs when x reaches to 0.2. Combining the results of XRD, photoluminescence, and cathodoluminescence spectra proved the existence of the Ca2Al2SiO7. The performances of the titled CPs in high-power white laser diodes lighting are characterized.
Metal-catalyzed reactions for the C(sp2)–N bond formation: achievements of recent years
Authors: Beletskaya Irina P. , Averin Alexei D.
Published: May 2021

The review deals with the main catalytic methods for the C(sp2)–N bond formation, including Buchwald–Hartwig palladium-catalyzed amination of aryl and heteroaryl halides, renaissance of the Ullmann chemistry,i.e., the application of catalysis by copper complexes to form the carbon–nitrogen bond, and Chan–Lam reactions of (hetero)arylboronic acids with amines. Also, oxidative amination with C–H activation, which has been booming during the last decade, is addressed. Particular attention is paid to achievements in the application of heterogenized catalysts.

The bibliography includes 350 references.
Young peoples’ perspectives about care in a youth-friendly general practice
Authors: McKinlay Eileen , Morgan Sonya , Garrett Sue , Dunlop Abby , Pullon Sue
Published: May 2021

INTRODUCTION Youth health outcomes are poor in New Zealand and have a life-long impact on individuals, whānau (family) and society. Little is known about how young people view their experiences of general practice care despite it being the most common place to access health care. AIM This study sought to explore young peoples’ experiences of care in a selected, youth-friendly general practice. METHODS In-depth individual interviews with six young people. RESULTS Four themes were identified from young peoples’ narratives in relation to their experiences of general practice care: going to the doctor is not easy for a young person; the attributes of staff make all the difference; specific youth-friendly consultation practices help young people; and a youth-friendly physical environment can help young people access services and feel safe. DISCUSSION Even though the study general practice had explicitly instituted youth-friendly initiatives, including offering no-charge consultations and specialist staff members, young people still described considerable barriers to attendance. Many barriers are practice-based and could be modified by staff training, provision of further youth care staff roles and consideration of environmental changes. Other barriers such as waiving prescription costs need government funding.
Warming enabled upslope advance in western US forest fires
Authors: Alizadeh Mohammad Reza , Abatzoglou John T. , Luce Charles H. , Adamowski Jan F. , Farid Arvin , Sadegh Mojtaba
Published: May 2021

Significance

Forest fires of the western United States have advanced upslope over the past few decades, scorching territories previously too wet to burn. We document an upslope advancement of high-elevation fires of 7.6 m/y, a rate comparable to the elevational velocity of vapor pressure deficit of 8.9 m/y. Strong interannual links between aridity and high-elevation forest fires and reduced influence of fire exclusion policies in montane mesic forests imply such changes are a byproduct of climate warming. We estimate that increased aridity between 1984 and 2017 exposed an additional 81,500 km
2
of western US montane forests to fires. These changes have significant implications for terrestrial carbon storage, snowpack, and water quantity and quality.
Discovery in space of ethanolamine, the simplest phospholipid head group
Authors: Rivilla Víctor M. , Jiménez-Serra Izaskun , Martín-Pintado Jesús , Briones Carlos , Rodríguez-Almeida Lucas F. , Rico-Villas Fernando , Tercero Belén , Zeng Shaoshan , Colzi Laura , de Vicente Pablo , Martín Sergio , Requena-Torres Miguel A.
Published: May 2021

Significance

The detection of ethanolamine (

N
H

2

C
H

2

C
H

2

OH) in a molecular cloud in the interstellar medium confirms that a precursor of phospholipids is efficiently formed by interstellar chemistry. Hence, ethanolamine could have been transferred from the proto-Solar nebula to planetesimals and minor bodies of the Solar System and thereafter to our planet. The prebiotic availability of ethanolamine on early Earth could have triggered the formation of efficient and permeable amphiphilic molecules such as phospholipids, thus playing a relevant role in the evolution of the first cellular membranes needed for the emergence of life.
Auxin guides germ-cell specification in
Arabidopsis
anthers
Authors: Zheng Yafeng , Wang Donghui , Ye Sida , Chen Wenqian , Li Guilan , Xu Zhihong , Bai Shunong , Zhao Feng
Published: May 2021

Significance

Germ cells (GCs) (i.e., the cells that are committed to meiosis and gametogenesis) are key carriers for eukaryotes to complete their life cycle, transmitting their genetic information from one generation to the next while generating variations to integrate environmental changes. Compared to what has been known in animals, very little is known about how the GCs in plants are segregated from somatic cells. This work demonstrates that auxin is a key factor guiding GC specification in
Arabidopsis
anthers. Local auxin biosynthesis interacts with the transcription of
SPOROCYTELESS/NOZZLE
and a progressive GC specification itself to form a dynamic feedback circuit that ensures the completion of GC specification.
Suppression of female fertility in
Aedes aegypti
with a CRISPR-targeted male-sterile mutation
Authors: Chen Jieyan , Luo Junjie , Wang Yijin , Gurav Adishthi S. , Li Ming , Akbari Omar S. , Montell Craig
Published: May 2021

Significance

Aedes aegypti
are mosquitoes that transmit dengue and other viruses that infect millions of people annually. One approach to control
Ae. aegypti
is through the release of sterile males, which suppresses fertilization by fertile males following mating with sterile males. To generate sterile males, the current approach is to mutagenize mosquitoes nonspecifically, which reduces the health of the males. Here, we used genome editing to selectively disrupt a gene (
B2t
) that specifically affects male fertility. The mutant males were healthy and were effective in suppressing females from producing progeny with fertile males. These studies raise the possibility that the
B2t
mutation can be employed to improve the sterile insect technique and reduce diseases spread by
Ae. aegypti
.
Paysandisia archon (South American palm borer).
Authors: Riolo P. , Nardi Sandro
Published: May 2021

P. archon is a Neotropical castniid species. It is not considered a pest in most of its native range, probably because it lives mainly on wild palm trees and not on crops; however, Houlbert (1918) and Bourquin (1933) reported that it had the potential to become a serious pest of palms. It was accidentally introduced to Europe from Argentina, as larvae hidden in imported palm trees, mostly Butia yatay and Trithrinax campestris. In Europe, where it is spreading rapidly, P. archon was first found in 2001 in Spain (Aguilar et al., 2001), France (Drescher and Dufay, 2001; Sarto i Monteys and Aguilar, 2001) and Italy (Espinosa et al., 2003; Riolo et al., 2004) and is considered an invasive species in these countries. It is already an invasive pest in France, Italy and Spain, where serious damage and plant mortality has been reported (1000 palm trees have been destroyed) and has become a pest in Buenos Aires, where it was introduced from north-east Argentina (Sarto i Monteys and Aguilar, 2005). The moth is currently listed in the EPPO A2 List (n. 338) of 'Pests recommended for regulation as quarantine pests' (OEPP/EPPO, 2008) and in European Phytosanitary Legislation in AnnexII/Part A/Section II (COMMISSION DIRECTIVE 2009/7/EC of 10 February 2009 amending Annexes I, II, IV and V to Council Directive 2000/29/EC on protective measures against the introduction into the Community of organisms harmful to plants or plant products and against their spread within the Community).
Pseudomonas syringae pv. actinidiae (bacterial canker of kiwifruit).
Authors: Loreti Stefania , Berry Jocelyn A
Published: May 2021

Bacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae (Psa), is a serious threat to kiwifruit production worldwide. At least four related but genetically distinct lineages of Psa are currently known, and more are likely to exist. In 2008, a particularly virulent strain emerged in Italy and spread rapidly to all main global kiwifruit production areas. This strain is variously referred to as the pandemic strain, PsaV or Biovar 3. Different Actinidia species and cultivars show varying susceptibility to Psa, and breeding resistant or tolerant kiwifruit varieties is highly important to the industry. Like all pathovars of Pseudomonas syringae, Psa is present in infected plant material. Transfer of nursery material is a major source of long distance spread, while agronomic techniques such as pruning can contribute to spread within and between orchards. The pathogen can be dispersed in aerosols and can be carried between trees and adjacent orchards in wind-driven rain. Psa is listed on the EPPO Alert List.
Continuous-Variable Measurement-Device-Independent Quantum Key Distribution with One-Time Shot-Noise Unit Calibration
Authors: Huang Luyu , Zhang Yichen , Yu Song
Published: May 2021

Imperfections in practical detectors, including limited detection efficiency, and inherent electronic noise, can seriously decrease the transmission distance of continuous-variable measurement-device-independent quantum key distribution systems. Owing to the difficulties inherent in realizing a high-efficiency fiber homodyne detector, challenges still exist in continuous-variable measurement-device-independent quantum key distribution system implementation. We offer an alternative approach in an attempt to solve these difficulties and improve the potential for system implementation. Here, a novel practical detector modeling method is utilized, which is combined with a one-time shot-noise-unit calibration method for the purpose of system realization. The new modeling method benefits greatly from taking advantage of one-time shot-noise-unit calibration methods, such as measuring electronic noise and shot noise directly to a novel shot-noise unit, so as to eliminate the statistical fluctuations found in previous methods; this makes the implementation of such systems simpler, and the calibration progress more accurate. We provide a simulation of the secret key rate versus distance with different parameters. In addition, the minimal detection efficiency required at each distance, as well as the contrast between the two methods, are also shown, so as to provide a reference in terms of system realization.
Phase-Modulated 2D Topological Physics in a One-Dimensional Ultracold System
Authors: Guo Gang-Feng , Bao Xi-Xi , Tan Lei , Gu Huai-Qiang
Published: May 2021

We propose a one-dimensional optical lattice model to simulate and explore two-dimensional topological phases with ultracold atoms, considering the phases of the hopping strengths as an extra dimension. It is shown that the model exhibits nontrivial phases, and corresponding two chiral-edge states. Moreover, we demonstrate the connections between changes in the topological invariants and the Dirac points. Furthermore, the topological order detected by the particle pumping approach in cold atoms is also investigated. The results obtained here provide a feasible and flexible method of simulating and exploring high-dimensional topological phases in low-dimension systems via the controllable phase of the hopping strength.
Bidirectional Information Flow Quantum State Tomography
Authors: Huang Huikang , Situ Haozhen , Zheng Shenggen
Published: May 2021

The exact reconstruction of many-body quantum systems is one of the major challenges in modern physics, because it is impractical to overcome the exponential complexity problem brought by high-dimensional quantum many-body systems. Recently, machine learning techniques are well used to promote quantum information research and quantum state tomography has also been developed by neural network generative models. We propose a quantum state tomography method, which is based on a bidirectional gated recurrent unit neural network, to learn and reconstruct both easy quantum states and hard quantum states in this study. We are able to use fewer measurement samples in our method to reconstruct these quantum states and to obtain high fidelity.
Excess Diffusion of a Driven Colloidal Particle in a Convection Array
Authors: Yin Qingqing , Li Yunyun , Marchesoni Fabio , Debnath Debajyoti , Ghosh Pulak K.
Published: May 2021

We numerically investigate the transport of a passive colloidal particle in a periodic array of planar counter-rotating convection rolls, at high Péclet numbers. It is shown that an external bias, oriented parallel to the array, produces a huge excess diffusion peak, in cases where bias and advection drag become comparable. This effect is not restricted to one-dimensional convection geometries, and occurs independently of the array’s boundary conditions.
Constraining Isovector Nuclear Interactions with Giant Dipole Resonance and Neutron Skin in 208Pb from a Bayesian Approach
Authors: Xu Jun
Published: May 2021

The remaining uncertainties in relation to isovector nuclear interactions call for reliable experimental measurements of isovector probes in finite nuclei. Based on the Bayesian analysis, although neutron-skin thickness data or isovector giant dipole resonance data in 208Pb can constrain only one isovector interaction parameter, correlations among other parameters can also be built. Using combined data for both the neutron-skin thickness and the isovector giant dipole resonance helps to significantly constrain all isovector interaction parameters; as such, it serves as a useful methodology for future research.
Generation of a Plasma Waveguide with Slow-Wave Structure
Authors: Zhang Xiao-Bo , Qiao Xin , Zhang Ai-Xia , Xue Ju-Kui
Published: May 2021

Using the particle-in-cell simulations, we report an efficient scheme to generate a slow wave structure in the electron density of a plasma waveguide, based on the array laser–plasma interaction. The spatial distribution of the electron density of the plasma waveguide is modulated via effective control of the super-Gaussian index and array pattern code of the lasers. A complete overview of the holding time, and the bearable laser’s intensity of the electron density structure of the plasma waveguide, is obtained. In addition, the holding time of the slow wave structure of the plasma waveguide is also controlled by adjusting the frequency of the array laser beam. Finally, effects due to ion motion are discussed in detail.
Energetic Particle Transport Prediction for CFETR Steady State Scenario Based on Critical Gradient Model
Authors: Zou Yunpeng , Chan V. S. , Chen Wei , Wang Yongqin , Hou Yumei , Zhu Yiren
Published: May 2021

The critical gradient mode (CGM) is employed to predict the energetic particle (EP) transport induced by the Alfvén eigenmode (AE). To improve the model, the normalized critical density gradient is set as an inverse proportional function of energetic particle density; consequently, the threshold evolves during EP transport. Moreover, in order to consider the EP orbit loss mechanism in CGM, ORBIT code is employed to calculate the EP loss cone in phase space. With these improvements, the AE enhances EPs radial transport, pushing the particles into the loss cone. The combination of the two mechanisms raises the lost fraction to 6.6%, which is higher than the linear superposition of the two mechanisms. However, the loss is still far lower than that observed in current experiments. Avoiding significant overlap between the AE unstable region and the loss cone is a key factor in minimizing EP loss.
Zintl Phase BaAgSb: Low Thermal Conductivity and High Performance Thermoelectric Material in Ab Initio Calculation
Authors: Wang Shao-Fei , Zhang Zhi-Gang , Wang Bao-Tian , Zhang Jun-Rong , Wang Fang-Wei
Published: May 2021

Thermoelectric materials are critical parts in thermal electric devices. Here, Zintl phase BaAgSb in space group of P63/mmc is reported as a promising thermoelectric material in density function theory. The anisotropic lattice thermal conductivity and phonon transport properties are investigated in theory. The strong phonon-phonon scattering in BaAgSb exhibits ultra-low lattice thermal conductivity of 0.59 W⋅m−1⋅K−1 along c-axis at 800 K, and high thermoelectric performance ZT = 0.94 at 400 K. The mix of covalent and ionic bond supports high carrier mobility and low thermal conductivity. The unusual features make BaAgSb a potential thermoelectric material.
Physical Properties Revealed by Transport Measurements for Superconducting Nd0.8Sr0.2NiO2 Thin Films
Authors: Xiang Ying , Li Qing , Li Yueying , Yang Huan , Nie Yuefeng , Wen Hai-Hu
Published: May 2021

The newly discovered superconductivity in infinite-layer nickelate superconducting films has attracted much attention, largely because their crystalline and electronic structures are similar to those of high-T
c cuprate superconductors. The upper critical field can provide a great deal of information on the subject of superconductivity, but detailed experimental data are still lacking for these films. We present the temperature- and angle-dependence of resistivity, measured under different magnetic fields H in Nd0.8Sr0.2NiO2 thin films. The onset superconducting transition occurs at about 16.2 K at 0 T. Temperature-dependent upper critical fields, determined using a criterion very close to the onset transition, show a clear negative curvature near the critical transition temperature, which can be explained as a consequence of the paramagnetically limited effect on superconductivity. The temperature-dependent anisotropy of the upper critical field is obtained from resistivity data, which yields a value decreasing from 3 to 1.2 with a reduction in temperature. This can be explained in terms of the variable contribution from the orbital limit effect on the upper critical field. The angle-dependence of resistivity at a fixed temperature, and at different magnetic fields, cannot be scaled to a curve, which deviates from the prediction of the anisotropic Ginzburg–Landau theory. However, at low temperatures, the resistance difference can be scaled via the parameter Hβ
|cosθ| (β = 6–1), with θ being the angle enclosed between the c-axis and the applied magnetic field. As the first detailed study of the upper critical field of nickelate thin films, our results clearly indicate a small anisotropy, and a paramagnetically limited effect, in terms of superconductivity, in nickelate superconductors.
Polarization Mechanism in Filled Tungsten Bronze Ba4Eu2Ti4Nb6O30 with Pinched P – E Hysteresis Loops
Authors: Zhu Lang , Zhu Xiao-Li , Liu Xiao-Qiang , Chen Xiang-Ming
Published: May 2021

Pinched P–E hysteresis loops have been observed in filled tungsten bronze Ba4Eu2Ti4Nb6O30, indicating the presence of novel polarization mechanisms. We investigate the evolution of polar order in filled tungsten bronze Ba4Eu2Ti4Nb6O30, together with its dielectric properties over a wide temperature range, from 50 K to 773 K. The temperature dependences of the dielectric properties exhibit two low-temperature dielectric relaxations, at around 300 K (P1), and 100 K (P2), and a high temperature peak at 588 K with no frequency dispersion, indicating the ferroelectric transition temperature T
c. Pinched P–E loops are observed in the temperature range between the low temperature relaxation at P1, and the ferroelectric transition. On cooling, the pinched P–E hysteresis loops open gradually, with increasing remnant polarization (P
r). Two pairs of reversal electric fields indicate two types of polar reversal mechanisms, with an activated energy of 1.41 eV (E
1), and 0.94 eV (E
2), respectively. One corresponds to the field-induced transition from a nonpolar to a polar state, which dominates at a high temperature close to T
c, while the other relates to the reversal of ferroelectric domains which stabilize gradually on cooling. At temperatures below 300 K, the polarization exhibits an evident decrease, probably related to the disruption of the polar order due to the dielectric relaxation at P1.
High-fidelity modeling of breakdown in helium: initiation processes and secondary electron emission
Authors: Lietz Amanda M , Barnat Edward V , Nail George R , Roberds Nicholas A , Fierro Andrew S , Yee Benjamin T , Moore Chris H , Clem Paul G , Hopkins Matthew M
Published: May 2021

Understanding the role of physical processes contributing to breakdown is critical for many applications in which breakdown is undesirable, such as capacitors, and applications in which controlled breakdown is intended, such as plasma medicine, lightning protection, and materials processing. The electron emission from the cathode is a critical source of electrons which then undergo impact ionization to produce electrical breakdown. In this study, the role of secondary electron yields due to photons (γ
ph) and ions (γ
i) in direct current breakdown is investigated using a particle-in-cell direct simulation Monte Carlo model. The plasma studied is a one-dimensional discharge in 50 Torr of pure helium with a platinum cathode, gap size of 1.15 cm, and voltages of 1.2–1.8 kV. The current traces are compared with experimental measurements. Larger values of γ
ph generally result in a faster breakdown, while larger values of γ
i result in a larger maximum current. The 58.4 nm photons emitted from He(21P) are the primary source of electrons at the cathode before the cathode fall is developed. Of the values of γ
ph and γ
i investigated, those which provide the best agreement with the experimental current measurements are γ
ph = 0.005 and γ
i = 0.01. These values are significantly lower than those in the literature for pristine platinum or for a graphitic carbon film which we speculate may cover the platinum. This difference is in part due to the limitations of a one-dimensional model but may also indicate surface conditions and exposure to a plasma can have a significant effect on the secondary electron yields. The effects of applied voltage and the current produced by a UV diode which was used to initiate the discharge, are also discussed.
Collisional electron momentum loss in low temperature plasmas: on the validity of the classical approximation
Authors: Vass Máté , Wilczek Sebastian , Lafleur Trevor , Brinkmann Ralf Peter , Donkó Zoltán , Schulze Julian
Published: May 2021

The electron momentum loss obtained from kinetic simulations, as well as the classical approximation based on the electron–neutral collision frequency, are calculated and compared in low pressure capacitively coupled plasmas in argon, helium and oxygen gases. The classical approximation (which is commonly used in theoretical or numerical fluid models) exaggerates the role of low-energy electrons and can lead to a significantly lower momentum loss compared to the exact momentum loss depending on the gas used, even if the exact electron distribution function is known. This leads to an underestimation of the Ohmic power absorption and a change in the harmonic content of the momentum loss as revealed by Fourier analysis. For argon, the classical approximation is found to be particularly poor and is partially related to the presence of a Ramsauer–Townsend minimum in the momentum transfer cross-section at low electron energies: a fact confirmed by using a ‘fake’ argon gas where the Ramsauer–Townsend minimum is artificially removed. The results are of broad general relevance to low-temperature plasmas, and can be useful for assessing errors in plasma fluid models.
Direct evidence of gradient drift instability being the origin of a rotating spoke in a crossed field plasma
Authors: Xu Liang , Eremin Denis , Brinkmann Ralf Peter
Published: May 2021

A plasma rotating spoke in a crossed field discharge is studied using 2D radial-azimuthal fully kinetic particle-in-cell Monte Carlo collision simulations. The kinetic model reveals the whole perturbation spectrum of the gradient drift instability in the linear stage: Simon–Hoh, lower hybrid, and ion sound modes, providing direct evidence of the spoke of gradient drift instability nature. The two-fluid dispersion relation of gradient drift instability was utilized to analyze the linear development of instabilities in the simulations. The charge separation effect was incorporated in the fluid linear theory and a super-resolution signal processing method (multiple signal classification) was applied to obtain the numerical frequency spectrum. The simulated spectrum and growth rate show excellent agreement with the theoretical dispersion relation (real frequency and imaginary frequency) in the investigated cases. The most linearly unstable mode was found to be the lower hybrid instability and the mode transition into the m = 1 macroscopic rotating structure after saturation of the linear phase is accompanied by an inverse energy cascade. In the nonlinear stage, pronounced spoke phenomena can occur when the heating of E

θ
× B electron flow channeled in the spoke front passage suffices to provide enhanced ionization.
Loophole-free plug-and-play quantum key distribution
Authors: Qi Ruoyang , Zhang Haoran , Gao Jiancun , Yin Liuguo , Long Gui-Lu
Published: May 2021

Robust, simple, and flexible quantum key distribution (QKD) is vital for realizing practical applications of this technique. Contrary to typical phase-coded QKD schemes, the plug-and-play QKD design requires only one arm-length-insensitive interferometer without active feedback, in which the noise is automatically compensated by the two-way structure. However, there are certain possible loopholes in the typical plug-and-play designs, which require consideration and strict monitoring. This study proposes a new design of theoretically loophole-free plug-and-play QKD scheme with two-way protocol and presents an experimental demonstration of said scheme. The security is analyzed under a collective attack scenario assisted by the decoy state method. The scheme was implemented in a 50.4 km commercial fibre without active feedback. The system showed highly robust performance with an ultra-low error rate and maintained an ultra-high visibility of 0.9947 ± 0.0002 through significant environmental changes over 24 hours.
Comparison of a direct measure of barrier crossing times with indirect measures such as the Larmor time
Authors: Rivlin Tom , Pollak Eli , Dumont Randall S
Published: May 2021

Different approaches for considering barrier crossing times are analyzed, with special emphasis on recent experiments which attempt to measure what is commonly referred to as the Larmor tunneling time. We show that that these experiments cannot reveal the Larmor time, due to the finite energy width of the incident particles. The Larmor time, which measures changes in spin polarization, is classified together with other measurements such as the Buttiker–Landauer oscillating barrier time as indirect measurements of interaction times of scattered particles. In contrast, we present a direct quantum mechanical measure of a barrier crossing time taken to be the difference between the mean flight time for a particle transmitted through a potential barrier incident on a screen and the time it would take to reach the same screen without the barrier. These metrics are asymptotic, in the sense that they infer a time from a measurement after the scattering event is over, whereas other measures like the dwell time are local. Some time measures are well-defined only for incident states which are monochromatic in energy, others are well-defined also for incident wavepackets whose incident energy width is finite. In this paper we compare the different approaches to conclude that only the flight time can be used to answer the provocative (but ultimately ill-posed) question: how much time does it take to tunnel through a barrier?
Entanglement and avoided crossing dynamics in the disordered Majumdar-Ghosh model
Authors: Barkataki Pranay , Ramkarthik M S
Published: May 2021

We study the ground and first excited state of the finite one dimensional Majumdar-Ghosh model with quenched disorder about the avoided crossings. We find a relation between the shift of the first avoided crossing and average value of random numbers. For low disorder regime, the two-qubit, odd and even partition entanglement gets exchanged at avoided crossings for low spin, and former two for any value of spin. This effect has a deep relation with the dimerization nature of these states. We develop an expression sans entanglement measures to detect and study these crossings.
Examination of the impact of tank material on ultrasonic measurements
Authors: Rymarczyk T , Gołąbek M , Rymarczyk P , Adamkiewicz P , Niderla K
Published: May 2021

The article presents the research of the tank material effect on the propagation of the ultrasonic signal. Measurements ware made using a prototype measuring card for an ultrasonic tomograph. The device has independent four channels with ultrasonic pulsers, ADC converters, filters, amplifiers, and envelope converters.
Assessment of the importance of branches considering new energy access
Authors: Zhang D L , Yang S , Huang W X , Wu J , Zhang Y Y , Tian X , Guo Z H
Published: May 2021

Under the background of increasing penetration rate of new energy, the risk level of power system is getting higher and higher. Identifying the key branches of the system quickly and accurately is of great significance for improving the stability of power grid operation and preventing the occurrence of blackouts. This paper models the uncertain factors after the new energy is connected and establishes a grid risk assessment system. Based on the probabilistic power flow calculation, the comprehensive system risk index under the decommissioning of each branch is obtained as the branch importance through five indicators like power flow fluctuation risk and line active power over-limit risk The improved IEEE-39 node system is used as an example for simulation calculation. The results verify the effectiveness of this method, which can distinguish the importance of branches, and provide references for safety early warning and differentiated planning.
Construction of the core backbone grid based on the maximum profit-to-risk ratio
Authors: Zhang D L , Yang S , Huang W X , Wu J , Zhang Y Y , Tian X , Guo Z H
Published: May 2021

The construction of the core backbone grid affects the ability of the power system to resist disasters and failures. However, traditional construction methods favor stable water and thermal power sources, which are no longer in line with the development trend of modern power systems. After new energy is connected to the core backbone grid, how to balance the system risk and the economic benefits it brings needs to be solved urgently. This paper takes the maximum profit-to-risk ratio as the objective function, and constructs the core backbone grid by a step-by-step method. The results of the improved IEEE 188 node calculation example show that the method proposed in this paper can effectively distinguish the key branch and nodes of the system. The core backbone grid structure constructed can ensure the stability of the system and improve the economy of the disaster-resistant system through the access of new energy units.
1kW Bidirectional 48V-12V DCDC Converter Design Based on Full Bridge CLLC Topology and FDP Controlling Method for Electric Vehicles Application
Authors: Liu Hai , He Lenian
Published: May 2021

Present electric vehicles market calls for 1kW bidirectional 48V-12V DCDC converters with high performances. The requirements that isolation and soft switching determine the power stage topology choosing range. Based on previous research results and actual requirements of this application, full-bridge CLLC topology is chosen for further analyses and designs. By properly choosing resonant devices, operating frequency (F), phase shift (P) between power side and load side, and duty (D) of power side, the power system achieves high efficiency with soft switching. Soft switching comes from a small extra time per period with no power transfer. The FPD has respective influences on the performances of the power system. For each one of FDP, there is a balance and two important performances that are conversion efficiency and output voltage accuracy which are listed for illustrating influences of F P D and choosing a best FPD for the whole system. The whole system includes power stage design on PCB and controlling stage design on integrated circuits. FPD can be designed self-adapting respectively and a simple control loop is proposed with adjustable D and settled F P. A proper FPD can achieve over 98.9% efficiency and control loop can be verified workable for load variation.
Optimal penetration of distributed generation system in radial distribution network using adaptive scheme
Authors: Gill A , Singh P
Published: May 2021

In this paper, an adaptive scheme based on biogeography based optimization and particle swarm optimization method for optimal penetration and sizing of distributed generation system in the existing radial distribution network at the optimal bus is suggested. Power losses and voltage profile maintenance are the biggest restrictions of the existing power system. These power losses will be calculated by load flow analysis and the adaptive scheme has been applied for power loss reduction and enhancing voltage profile. The testing of the adaptive scheme for optimal penetration and sizing of distributed generation system will be done at the IEEE 69 bus radial distribution network. This adaptive scheme and IEEE 69 bus radial distribution network are modelled with the help of Matlab software.
Analysis of Drug Classification using Mechanism of Action
Authors: Puneeth G R , Mahesh S R , Adithya H , Bhargava Sharma J , Kumari H A Chaya , Gururaj H L , Hong Lin
Published: May 2021

Mechanism of action (MOA) refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular targets to which the drug binds, such as an enzyme or receptor. Receptor sites have specific affinities for drugs based on the chemical structure of the drug, as well as the specific action that occurs there. Drugs usually work by binding to a receptor and up-regulating (agonist) or down-regulating (antagonist) the production of some downstream cellular activity. If it is known that a disease affects some particular receptor or downstream set of cell activity, then scientists can develop drugs faster if they can predict how cells and genes affect various receptor sites. This paper contains a detailed review on Mechanism of Action.
Overview and research progress of no reference image quality evaluation methods
Authors: Wang Hao Yue , Chen XiangNing , Du ShuHan , Xu BiJie , Liu Yan
Published: May 2021

Image quality will greatly affect the acquisition of human visual information, but the image will inevitably cause a certain degree of distortion in the process of transmission, compression, coding and so on. At this time, the accuracy of image quality evaluation (IQA) is particularly important, which also makes IQA an important research direction in the field of image processing. IQA methods are divided into subjective image quality evaluation method and objective image quality evaluation method.there are many subjective evaluation methods, and the international telecommunications union (ITU) has also proposed many subjective evaluation methods and standards. there are three most commonly used methods, namely, the double stimulation continuous quality classification method, the single stimulation continuous quality classification method and the double stimulation damage classification method. Correspondingly, there are three kinds of objective evaluation methods, full reference, half reference and no reference. At present, this paper selects the research focus of IQA field-no reference image quality evaluation method as the main research object, summarizes the advantages and disadvantages of each non-reference evaluation method, and prospects the future development of the non-reference image quality evaluation method.
Mono-pulse radar angle estimation algorithm under low signal-to-noise ratio
Authors: Dong Wenhao , Wang Jingyi , Song Zhiyong
Published: May 2021

In the case of low signal-to-noise ratio (SNR), in order to improve the angle measurement accuracy of the mono-pulse radar seeker, a target angle estimation algorithm is proposed. The algorithm takes the target angle as a state variable under the Bayesian framework, expands it to the state vector, performs state modeling and observation modeling on it, and builds a particle-based eye angle estimator, which improves the target angle estimation performance. The effectiveness of the algorithm is verified by the simulation data of the medium pulse repetition frequency radar seeker.
Convolutional Bi-directional Long Short Term Memory Network based Dynamic Fault Diagnosis for Transformer DGA
Authors: Luo Lin , Pei Xiaodeng , Shuai Chen
Published: May 2021

Dissolved gas analysis (DGA) method is one of the important methods to detect early internal faults in transformers. Aiming at the shortcomings of feature extraction and online modelling in the analysis model based on shallow layer, a transformer DGA online fault diagnosis method combining convolutional neural network and bidirectional long short term memory network is proposed in this paper. By using multi-time characteristic gas data as the input of the diagnostic model, combined with convolution and pooling, the fault sensitive features were extracted, and the time dimension features were extracted by using the recursive neural network with gated structure. Under various evaluation criteria, it is compared with convolutional neural network, bidirectional long short-term memory (Bi-LSTM) network and dynamic support vector machine. The experimental results show that the online transformer diagnosis model proposed in this paper, which considers both time and space characteristics, has higher prediction accuracy.
β-Glucan Extraction from Mycelium in Spent Mushroom Substrate of Pleurotus ostreatus and Schizophyllum commune
Authors: Nasir A M , Ruslan N R N , Zakaria Z , Hassan S A M , Ishak N , Rohaizad N M , Gunny A A N
Published: May 2021

Spent mushroom substrate (SMS) is the biomass waste produced from the production of mushroom which generating disposal problems. To overcome the problem the extraction of bioactive compound such as β-glucan from the waste SMS could solve the problem and can also increase its added value. β-glucan appears to be promising for aiding in the cure of tumorous disease and help to reduce the cholesterol levels in blood. In this study, β-glucan was extracted and compared from two different commercial mushroom (Pleurotus ostreatus and Schizophyllum commune) from its fruiting body and mycelium on solid waste SMS using chemical extraction methods. The characteristics of physical structure, functional group and properties of extracted β-glucan was investigated. Here, Fourier-transform infrared (FTIR) and screening electron microscope (SEM) were used to identify and evaluated the structural conformations of β-glucan and physical structure. The functional properties, swelling power, viscosity and fat binding capacity were analyzed. Based on results, mycelia of Pleurotus ostreatus shown highest swelling power (11.74 g/g) and fat binding capacity (12.09 g oil/g sample) while, mycelia of Schizophyllum commune shown the highest viscosity (11.85 cP). Since the value for all functional properties shown the highest value on mycelium compare to fruiting body, thus it is strength that β-glucan extraction from mycelium solid waste has high novel properties compare with mushroom fruiting body.
Co-pyrolysis of lemongrass waste and residual cooking oil in a fixed bed reactor
Authors: Ahmad R , Baharein N A F K , Mohamed A R , Kasim N N
Published: May 2021

Co-pyrolysis of lemongrass waste and residual cooking oil was examined in a fixed bed reactor. The goal was to study the effect of pyrolysis parameters on bio-oil yield. Bio-oil product characteristics between lemongrass pyrolysis and residual cooking oil co-pyrolysis were analysed. The variable parameters were temperature (350, 400, 450 and 500 ° C), particle size lemongrass (< 150, 150, 212, 300 and 425μm) and holding time (3, 5 and 7 minutes). The mixing ratios of lemongrass waste to waste cooking oil were respectively 100:0, 90:10, 80:20, 60:40 and 50:50. The optimal temperature was 400 °C with the highest yield of 30.5 percent bio-oil at the particle size of 300 μm, holding time of 5 minutes and the mixing ratio of 80:20. The addition of residual cooking oil increased the quality of the bio-oil obtained in term of phenol compounds.