bluuebunny/crossref_metadata_2025 huggingface dataset:
Lateral electrical transport and field-effect characteristics of sputtered p-type chalcogenide thin films
Authors: Wahid Sumaiya , Daus Alwin , Khan Asir Intisar , Chen Victoria , Neilson Kathryn M. , Islam Mahnaz , Chen Michelle E. , Pop Eric
Published: December 2021

Investigating lateral electrical transport in p-type thin film chalcogenides is important to evaluate their potential for field-effect transistors (FETs) and phase-change memory applications. For instance, p-type FETs with materials sputtered at low temperature (≤ 250 °C) could play a role in flexible electronics or back-end-of-line silicon-compatible processes. Here, we explore lateral transport in chalcogenide films (Sb2Te3, Ge2Sb2Te5, and Ge4Sb6Te7) and multilayers, with Hall measurements (in ≤ 50 nm thin films) and with p-type transistors (in ≤ 5 nm ultrathin films). The highest Hall mobilities are measured for Sb2Te3/GeTe superlattices (∼18 cm2 V−1 s−1 at room temperature), over 2–3× higher than the other films. In ultrathin p-type FETs with Ge2Sb2Te5, we achieve field-effect mobility up to ∼5.5 cm2 V−1 s−1 with on/off current ratio of ∼104, the highest for Ge2Sb2Te5 transistors to date. We also explore process optimizations (e.g., the AlOx capping layer, type of developer for lithography) and uncover their tradeoffs toward the realization of p-type transistors with acceptable mobility and on/off current ratio. Our study provides essential insights into the optimization of electronic devices based on p-type chalcogenides.
In situ cloud particle tracking experiment
Authors: Bertens G. , Bagheri G. , Xu H. , Bodenschatz E. , Moláček J.
Published: December 2021

The collision–coalescence process of inertial particles in turbulence is held responsible for the quick growth of cloud droplets from ∼15 to ∼50 µm in diameter, but it is not well understood. Turbulence has two effects on cloud droplets: (1) it brings them closer together, preferentially concentrating them in certain parts of the flow, and (2) it sporadically creates high accelerations, causing droplets to detach from the underlying flow. These turbulence–cloud droplet interactions are difficult to study numerically or in the laboratory due to the large range of scales involved in atmospheric turbulence, so in situ measurements are needed. Here, we present a Lagrangian particle tracking (LPT) experimental setup situated close to the summit of Mt. Zugspitze at an altitude of 2650 m above the sea level on top of the environmental research station Schneefernerhaus. Clouds naturally occur at this location about a quarter of the time. The LPT experiment probes a volume of ∼40 × 20 × 12 mm3, has a spatial resolution of 5 µm and a temporal resolution of 0.1 ms, and measures accelerations to within 0.1 m s−2. Furthermore, the experiment can slide over a set of rails, driven by a linear motor, to compensate for the mean wind. It can slide up to 7.5 m s−1. By doing so, the average residence time of the particles in the measurement volume increases. The mean wind compensation allows us to study various dynamical quantities, such as the velocity autocorrelation, or the dynamics of clustering. Moreover, it is beneficial for particle tracking, in general, since longer particle tracks allow us to apply better filtering to the tracks and thus increase accuracy. We present the radial distribution function, which quantifies clustering, the longitudinal relative velocity distribution, and the Lagrangian velocity autocorrelation, all computed from cloud droplet trajectories.
Submicron 3D imaging of liquid–vapor interfaces formed in the Cassie–Baxter state
Authors: Klingel S. , Hein A. , Oesterschulze E.
Published: December 2021

In this work, we present a method to microscopically investigate the liquid–vapor interfaces on the bottom side of droplets, which were placed on superhydrophobic structures, so that wetting in the Cassie–Baxter (CB) state occurred. These interfaces are hard to access optically, especially when an opaque substrate material is used, which is usually the case for technical applications. In that case, the menisci have to be observed through the droplet, which substantially deteriorates the imaging quality. Other methods that circumvent these distortions, such as optical coherence tomography, are restricted to a resolution of several micrometers. Confocal or fluorescence microscopy additionally requires a transparent substrate. To measure the liquid–vapor interfaces formed in the Cassie–Baxter state with high accuracy liquid droplets of a monomer solution that chemically reacts to form the elastomer, polydimethylsiloxane was placed on structured surfaces. Because double reentrant structures were used, wetting occurred in the Cassie–Baxter state despite the low surface tension of the monomer solution. After curing, it was possible to remove the solid droplets from the surface and investigate them using confocal microscopy, which provides an excellent height resolution of 10 nm. Test structures such as arrays of stripes and holes with variable spacing or diameter were used to investigate the impact of their geometry on the liquid–vapor interfaces formed in the CB state. Although the maximum height of the menisci on the droplet's bottom side is in the region of several 10 μm, the 10 nm resolution is required to adequately compare their topography with simplified theoretical models.
Data-driven learning of Mori–Zwanzig operators for isotropic turbulence
Authors: Tian Yifeng , Lin Yen Ting , Anghel Marian , Livescu Daniel
Published: December 2021

Developing reduced-order models for turbulent flows, which contain dynamics over a wide range of scales, is an extremely challenging problem. In statistical mechanics, the Mori–Zwanzig (MZ) formalism provides a mathematically exact procedure for constructing reduced-order representations of high-dimensional dynamical systems, where the effects due to the unresolved dynamics are captured in the memory kernel and orthogonal dynamics. Turbulence models based on MZ formalism have been scarce due to the limited knowledge of the MZ operators, which originates from the difficulty in deriving MZ kernels for complex nonlinear dynamical systems. In this work, we apply a recently developed data-driven learning algorithm, which is based on Koopman's description of dynamical systems and Mori's linear projection operator, on a set of fully resolved isotropic turbulence datasets to extract the Mori–Zwanzig operators. With data augmentation using known turbulence symmetries, the extracted Markov term, memory kernel, and orthogonal dynamics are statistically converged and the generalized fluctuation–dissipation relation can be verified. The properties of the memory kernel and orthogonal dynamics, and their dependence on the choices of observables are investigated to address the modeling assumptions that are commonly used in MZ-based models. A series of numerical experiments are then constructed using the extracted kernels to evaluate the memory effects on prediction. The results show that the prediction errors are strongly affected by the choice of observables and can be further reduced by including the past history of the observables in the memory kernel.
Uniform supersonic flow sampling for detection by chirped-pulse rotational spectroscopy
Authors: Gurusinghe Ranil M. , Dias Nureshan , Krueger Ritter , Suits Arthur G.
Published: December 2021

Chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy is a powerful near-universal detection method finding application in many areas. We have previously coupled it with supersonic flows (CPUF) to obtain product branching in reaction and photodissociation. Because chirped-pulse microwave detection requires monitoring the free induction decay on the timescale of microseconds, it cannot be employed with good sensitivity at the high densities achieved in some uniform supersonic flows. For application to low-temperature kinetics studies, a truly uniform flow is required to obtain reliable rate measurements and enjoy all the advantages that CP-FTMW has to offer. To this end, we present a new setup that combines sampling of uniform supersonic flows using an airfoil-shaped sampling device with chirped-pulse mmW detection. Density and temperature variations in the airfoil-sampled uniform flow were revealed using time-dependent rotational spectroscopy of pyridine and vinyl cyanide photoproducts, highlighting the use of UV photodissociation as a sensitive diagnostic tool for uniform flows. The performance of the new airfoil-equipped CPUF rotational spectrometer was validated using kinetics measurements of the CN + C2H6 reaction at 50 K with detection of the HCN product. Issues relating to product detection by rotational spectroscopy and airfoil sampling are discussed. We show that airfoil sampling enables direct measurements of low temperature reaction kinetics on a microsecond timescale, while rotational spectroscopic detection enables highly specific simultaneous detection of reactants and products.
Perspective on the topological rainbow
Authors: Elshahat Sayed , Wang Chenyang , Zhang Hongyu , Lu Cuicui
Published: December 2021

Topological photonics provides a robust platform for the study of nanophotonic devices. The topological rainbow can be used to separate, slow, and trap topological photonic states of different frequencies at different positions. Although numerous reports have investigated the construction of traditional rainbow devices, limited methods have been proposed to realize topological rainbow phenomena and devices. In this Perspective, we provide an overview of the basic concept and mechanisms of rainbow trapping. A topological rainbow is discussed in terms of the implementation of synthetic dimensions. Additionally, recent advances of the topological rainbow are presented for elastic and acoustic waves. We introduce current physical methods of realizing the topological rainbow and discuss potential applications in physics and engineering.
First evidence of avian predation of threatened freshwater mussels (
Authors: Farnworth Bridgette
Published: December 2021

Abstract Context Conservation efforts for New Zealand freshwater mussels (kākahi) are challenging because of their longevity and their complex life history, but also by the scarcity of research that has investigated causes of decline. Reproductive constraints may impair recruitment, but other key aspects that influence population structure, such as predation pressure, remain unknown. Predation is an emerging risk for kākahi because, although bivalve predation has been observed in New Zealand waterways, its prevalence and impacts remain unquantified. Aims The present study resolves trophic interactions with predator populations by identifying kākahi predators and examining characteristics of freshwater mussels (e.g. species or size) that may indicate vulnerability to predation. Methods Intensive monitoring was conducted over 6 weeks (January to March 2020) by using trail cameras to observe kākahi predators at the Orongo Stream, a western Waikato (New Zealand) site with high densities of Echyridella aucklandica (threat status: Vulnerable) and E. menziesii (Declining). Predated kākahi shell remains were analysed to (i) identify typical patterns of shell damage, and (ii) determine prey selectivity via size distribution. Key results Eight observations of an avian predator (pūkeko, Porphyrio porphyrio melanotus) interacting with both E. aucklandica and E. menziesii were recorded; however, E. menziesii comprised a significantly greater proportion of the shell remains that had direct evidence of predation. Both species of mussel displayed significantly more damage to the posterior end of the valves but size selectivity was detected only for E. menziesii. Conclusions Pūkeko actively search for mussels and frequently consume them as part of a wider diet when they are accessible during summer. Whereas healthy populations of freshwater mussels may withstand predation by native species, populations that face substantial pressure from other natural stressors and anthropogenic change may suffer. Predation impacts on kākahi populations should be a factor considered for the future management of New Zealand mussel species. Implications Identifying pūkeko as kākahi predators clarifies food webs for conservation managers and highlights the need to quantify their impact on mussel populations; particularly for E. menziesii, which may be more vulnerable to predation.
Testing the validity of using raceway and swimway performance in sea turtle hatchlings as an index of real-life crawling and swimming performance
Authors: Mazlan Nurul Ainni , Booth David T. , Rusli Mohd Uzair
Published: December 2021

Abstract Context Increasingly, ecological studies of sea turtles are measuring locomotion performance of newly emerged hatchlings in raceways and swimways under the assumption that locomotion performance measured in these structures reflects locomotion performance in nature, and that such measurements reflect the chance of a hatchling surviving dispersion from their natal beach. Aims The aim was to test the assumption that an individual hatchling’s performance measured in artificial structures is correlated with the same individual’s performance in the natural environment (beach and sea), adding confidence that such measurements are an indirect indicator of dispersal ability during the first 24 h of post-nest life. Methods Green turtle (Chelonia mydas) hatchlings that had just emerged from their nest had their crawling and swimming speeds measured in an on-beach raceway and swimway. The same hatchlings then had their beach crawling and sea swimming speed measured and the correlation between their performance in the artificial structures and natural crawls and swims calculated. Key results An individual sea turtle hatchling’s locomotion performance in nature was correlated with its locomotion performance in raceways and swimways, but beach crawling was generally slower than raceway crawling, and sea swimming was generally faster than swimway swimming. We also found a weaker correlation between the raceway and beach crawling speeds than the sea and swimway swimming speeds. Conclusions The measurement of sea turtle hatchling crawling speed and swimming speed in artificial structures correlated with the individual’s locomotion performance in nature, supporting the assumption that the locomotion performance measured in artificial structures reflects their relative locomotion performance in the natural environment. Implications The measurement of sea turtle hatchlings locomotion performance in artificial structures can be used to indicate how variations in the nest microenvironment such as temperature and moisture affect a hatchling’s real-life locomotion performance, and thus reflect a hatchling’s dispersal ability during the first 24 h of post-nest life. Thus, sea turtle rookery managers can use this information to assess how their incubation management strategies affect hatchling locomotion performance, and consequently their likely offshore dispersal ability.
Immune dysregulation in SHARPIN-deficient mice is dependent on CYLD-mediated cell death
Authors: Ang Rosalind L. , Chan Mark , Legarda Diana , Sundberg John P. , Sun Shao-Cong , Gillespie Virginia L. , Chun Nicholas , Heeger Peter S. , Xiong Huabao , Lira Sergio A. , Ting Adrian T.
Published: December 2021

Significance

The mechanisms underlying inflammatory disorders are poorly understood. In this study, we show that inappropriate cell death may cause uncontrolled inflammation. We found that CYLD, an enzyme that removes K63-linked polyubiquitination, is normally inhibited. But in thecpdmmouse strain that has a loss-of-function in theSharpingene, the brake on CYLD is no longer present. When CYLD is no longer inhibited, it turns on death signaling in cells exposed to the cytokine TNF, and the ensuing inappropriate cell death causes skin inflammation and other immune disorders in thecpdmmouse. Removing CYLD from thecpdmmouse prevents cell death and reverses the inflammation. We conclude that excessive CYLD activity leads to inappropriate cell death and inflammation.
Power-law description of martensite transformation curves
Authors: Guimarães J. R. C. , Rios P. R. , Alves A. L. M.
Published: December 2021

This paper revisits the transformation curves of martensite. We obtained a comparative function compatible with plate and lath transformation validated with independent experimental data in the scientific literature, starting with a power law. The model bears two fitting parameters, which could be interpreted after established aspects of the transformations described in the literature. The model provides a framework to analyse ‘isothermal’, ‘athermal’, ‘bursting’ and ‘mechanical induced’ martensitic transformation curves.
Effect of Ni interlayer on the microstructure, mechanical and corrosion properties of the dissimilar 1MnCrMoNi/X70 steels friction welding joint
Authors: Nie Qidong , Wang Xiang , Li Jiaxin , Wang Pengju , Li Xinlin
Published: December 2021

Pure Ni was employed as an intermediate interlayer in the dissimilar 1MnCrMoNi/X70 steels friction welding joint. The effect of the Ni interlayer on the microstructure, mechanical and corrosion properties of the joint was investigated. Compared with the Ni-free joint, the joint with the Ni interlayer had coarser microstructure and lower microhardness. Furthermore, the weld zone of the 1MnCrMoNi steel was abnormally harder than the adjacent thermo-mechanically affected zone. The tensile strength of the joint with the Ni interlayer was improved, and this joint also demonstrated a lower yield ratio, equivalent impact toughness, and enhanced corrosion resistance.
Tool tilt angle induced variation of shoulder-workpiece contact condition in friction stir welding
Authors: Zhai Ming , Wu ChuanSong , Shi Lei
Published: December 2021

The effect of tool tilt angle has not been appropriately considered in modelling friction stir welding process. In this study, the expressions to determine incomplete contact region caused by tool tilt were derived and experimentally verified. Correspondingly, the axial stress, slip rate, friction coefficient were modified separately in complete and incomplete contact regions. It was found that with the increase of tool tilt angle from 1.5° to 4°, the material flow ability towards the advancing side was enhanced at trailing side, the temperature at shoulder/workpiece interface increased from 788 to 810 K, while that at pin/workpiece interface increased from 777 to 802 K. The calculated interface temperature and the thermo-mechanically affected zone boundary were in good agreement with the measured ones.
Random-Gate-Voltage Induced Al’tshuler–Aronov–Spivak Effect in Topological Edge States
Authors: Luo Kun , Chen Wei , Sheng Li , Xing D. Y.
Published: December 2021

Helical edge states are the hallmark of the quantum spin Hall insulator. Recently, several experiments have observed transport signatures contributed by trivial edge states, making it difficult to distinguish between the topologically trivial and nontrivial phases. Here, we show that helical edge states can be identified by the random-gate-voltage induced Φ
0/2-period oscillation of the averaged electron return probability in the interferometer constructed by the edge states. The random gate voltage can highlight the Φ
0/2-period Al’tshuler–Aronov–Spivak oscillation proportional to sin2(2πΦ/Φ
0) by quenching theΦ
0-period Aharonov–Bohm oscillation. It is found that the helical spin texture induced π Berry phase is key to such weak antilocalization behavior with zero return probability at Φ = 0. In contrast, the oscillation for the trivial edge states may exhibit either weak localization or antilocalization depending on the strength of the spin-orbit coupling, which has finite return probability at Φ = 0. Our results provide an effective way for the identification of the helical edge states. The predicted signature is stabilized by the time-reversal symmetry so that it is robust against disorder and does not require any fine adjustment of system.
Improved Superconducting Qubit State Readout by Path Interference
Authors: Wang Zhiling , Bao Zenghui , Wu Yukai , Li Yan , Ma Cheng , Cai Tianqi , Song Yipu , Zhang Hongyi , Duan Luming
Published: December 2021

High fidelity single shot qubit state readout is essential for many quantum information processing protocols. In superconducting quantum circuit, the qubit state is usually determined by detecting the dispersive frequency shift of a microwave cavity from either transmission or reflection. We demonstrate the use of constructive interference between the transmitted and reflected signal to optimize the qubit state readout, with which we find a better resolved state discrimination and an improved qubit readout fidelity. As a simple and convenient approach, our scheme can be combined with other qubit readout methods based on the discrimination of cavity photon states to further improve the qubit state readout.
Ideal Spin Hydrodynamics from the Wigner Function Approach
Authors: Peng Hao-Hao , Zhang Jun-Jie , Sheng Xin-Li , Wang Qun
Published: December 2021

Based on the Wigner function in local equilibrium, we derive hydrodynamical quantities for a system of polarized spin-1/2 particles: the particle number current density, the energy-momentum tensor, the spin tensor, and the dipole moment tensor. Compared with ideal hydrodynamics without spin, additional terms at the first and second orders in the Knudsen number Kn and the average spin polarization χs
have been derived. The Wigner function can be expressed in terms of matrix-valued distributions, whose equilibrium forms are characterized by thermodynamical parameters in quantum statistics. The equations of motion for these parameters are derived by conservation laws at the leading and next-to-leading order Kn and χs
.
Unexpected Selective Absorption of Lithium in Thermally Reduced Graphene Oxide Membranes
Authors: Jiang Jie , Mu Liuhua , Qiang Yu , Yang Yizhou , Wang Zhikun , Yi Ruobing , Qiu Yinwei , Chen Liang , Yan Long , Fang Haiping
Published: December 2021

Lithium plays an increasingly important role in scientific and industrial processes, and it is extremely important to extract lithium from a high Mg2+/Li+ mass ratio brine or to recover lithium from the leachate of spent lithium-ion batteries. Conventional wisdom shows that Li+ with low valence states has a much weaker adsorption (and absorption energy) with graphene than multivalent ions such as Mg2+. Here, we show the selective adsorption of Li+ in thermally reduced graphene oxide (rGO) membranes over other metal ions such as Mg2+, Co2+, Mn2+, Ni2+, or Fe2+. Interestingly, the adsorption strength of Li+ reaches up to 5 times the adsorption strength of Mg2+, and the mass ratio of a mixed Mg2+/Li+ solution at a very high value of 500 : 1 can be effectively reduced to 0.7 : 1 within only six experimental treatment cycles, demonstrating the excellent applicability of the rGO membranes in the Mg2+/Li+ separation. A theoretical analysis indicates that this unexpected selectivity is attributed to the competition between cation–π interaction and steric exclusion when hydrated cations enter the confined space of the rGO membranes.
Determination of the Range of Magnetic Interactions from the Relations between Magnon Eigenvalues at High-Symmetry κ Points
Authors: Wang Di , Yu Jihai , Tang Feng , Li Yuan , Wan Xiangang
Published: December 2021

Magnetic exchange interactions (MEIs) define networks of coupled magnetic moments and lead to a surprisingly rich variety of their magnetic properties. Typically MEIs can be estimated by fitting experimental results. Unfortunately, how many MEIs need to be included in the fitting process for a material is unclear a priori, which limits the results obtained by these conventional methods. Based on linear spin-wave theory but without performing matrix diagonalization, we show that for a general quadratic spin Hamiltonian, there is a simple relation between the Fourier transform of MEIs and the sum of square of magnon energies (SSME). We further show that according to the real-space distance range within which MEIs are considered relevant, one can obtain the corresponding relationships between SSME in momentum space. By directly utilizing these characteristics and the experimental magnon energies at only a few high-symmetry k points in the Brillouin zone, one can obtain strong constraints about the range of exchange path beyond which MEIs can be safely neglected. Our methodology is also generally applicable for other Hamiltonian with quadratic Fermi or Boson operators.
Acceleration of DNA Replication of Klenow Fragment by Small Resisting Force
Authors: Liu Yu-Ru , Wang Peng-Ye , Li Wei , Xie Ping
Published: December 2021

DNA polymerases are an essential class of enzymes or molecular motors that catalyze processive DNA syntheses during DNA replications. A critical issue for DNA polymerases is their molecular mechanism of processive DNA replication. We have proposed a model for chemomechanical coupling of DNA polymerases before, based on which the predicted results have been provided about the dependence of DNA replication velocity upon the external force on Klenow fragment of DNA polymerase I. Here, we performed single molecule measurements of the replication velocity of Klenow fragment under the external force by using magnetic tweezers. The single molecule data verified quantitatively the previous theoretical predictions, which is critical to the chemomechanical coupling mechanism of DNA polymerases. A prominent characteristic for the Klenow fragment is that the replication velocity is independent of the assisting force whereas the velocity increases largely with the increase of the resisting force, attains the maximum velocity at about 3.8 pN and then decreases with the further increase of the resisting force.
Controlling valley-polarisation in graphene via tailored light pulses
Authors: Mrudul M S , Dixit Gopal
Published: December 2021

Analogous to charge and spin, electrons in solids endows an additional degree of freedom: the valley pseudospin. Two-dimensional hexagonal materials such as graphene exhibit two valleys, labelled as K and K′. These two valleys have the potential to realise logical operations in two-dimensional materials. Obtaining the desired control over valley polarisation between the two valleys is a prerequisite for the logical operations. Recently, it was shown that two counter-rotating circularly polarised laser pulses can induce a significant valley-polarisation in graphene. The main focus of the present work is to optimise the valley polarisation in monolayer graphene by controlling different laser parameters, such as wavelength, intensity ratio, frequency ratio and sub-cycle phase in two counter-rotating circularly polarised laser setup. Moreover, an alternate approach, based on single or few-cycle linearly polarised laser pulse, is also explored to induce significant valley polarisation in graphene. Our work could help experimentalists to choose a suitable method with optimised parameter space to obtain the desired control over valley polarisation in monolayer graphene.
Keratinocyte cellular damage induced by pesticide doses below the cytotoxic level evidenced by electrical impedance and broadband dielectric spectroscopy
Authors: Lasalvia M , Ambrico M , Ligonzo T , Perna G , Ambrico P F , Capozzi V
Published: December 2021

The cellular response of a normal human keratinocyte cell line exposed to non-cytotoxic doses of a deltamethrin-based pesticide was investigated by means of two different electrical impedance data spectroscopy approaches: Nyquist plot and broadband dielectric spectroscopy. The measurements have shown that the membrane capacity increases with pesticide concentration and this facilitates the electric current through cell membranes. Furthermore, the impedance of the extracellular matrix also increases with pesticide concentration, thus reducing the electric current outside the cell. Dielectric permittivity changes in the cellular samples at frequencies larger than 100 Hz. Fluorescence (FL) measurements emphasized an increase in neutral membrane lipids as a consequence of the pesticide exposure. Comparison of FL response of pesticide exposed cells with the control ones showed a time increase in the emission intensity, suggesting the existence of a membrane lipid response aimed at repairing the cell damage due to pesticide exposure. Therefore, both spectroscopic techniques have been demonstrated as potential means to investigate the response to cell stress and damage. This opens up new possibilities in the early diagnosis of cellular modifications related to the pesticide exposure of cells.
Distribution and evolution of surface charge in surface dielectric barrier discharge driven by AC and pulse dual power supply
Authors: Yu Si-Qi , Yan Hui-Jie , Li Jia-Qi , Li Ting , Wang Yu-Ying , Song Jian
Published: December 2021

The evolution of surface charge in surface dielectric barrier discharge (SDBD) is observed by using Pockels effect. SDBD is driven by sine AC and pulse dual-power supply voltage. The filamentary discharge and glow-like discharge are enhanced by superimposing positive pulse on sine trough and negative pulse on sine crest, respectively. The interval of enhanced discharge is adjusted by pulse repetition frequency (PRF). The formation and decay of surface charges are analyzed at low PRF, and the accumulation effect is analyzed at high PRF. The results showed that the decay rates of charges decrease with increasing distance from the exposed electrode. When a positive pulse is superimposed on sine trough, the traces of positive charges are filaments with long extending lengths, which are the footprints of discharge channels. The lifetime of positive charges is hundreds of AC cycles (tens of milliseconds). Under certain conditions, subsequent glow-like discharge evolves as ‘flying’ above the dielectric surface (three-dimensional (3D) propagation). Most of the negative charges are neutralized in subsequent filamentary discharge. Some negative charges accumulate downstream and exist longer than positive charges. In the case of negative pulses superimposed on sine crest, the enhanced glow-like discharge appears 3D propagation. The propagation distance is much smaller than that of positive pulse. Most of the negative charges are uniformly distributed near the exposed electrodes with a short lifetime (a few hundred microseconds) and are quickly neutralized in subsequent discharges. The occurrence of 3D propagation requires certain conditions and the mechanism needs further research.
On a force balance and role of cathode plasma in Hall effect thrusters
Authors: Chernyshev Timofey , Krivoruchko Dariya
Published: December 2021

The cathode plasma is a specific transition region in the Hall effect thruster (HET) discharge that localizes between the strongly magnetized acceleration layer (magnetic layer or B-layer) and non-magnetized exhaust plume. Cathode plasma provides a flow of electron current that supplies losses in the magnetic layer (due to ionization, excitation, electron-wall interactions, etc). The electrons’ transport in this region occurs in collisionless mode through the excitation of plasma instabilities. This effect is also known as ‘anomalous transport/conductivity’. In this work, we present the results of a 2D (drift-plane) kinetic simulation of the HET discharge, including the outside region that contains cathode plasma. We discuss the process of cathode plasma formation and the mechanisms of ‘anomalous transport’ inside it. We also analyze how fluid force balance emerges from collisionless kinetic approach. The acceleration mechanism in HETs is commonly described in terms of force balance. Namely, the reactive force produced by accelerated ions has the same value as Ampère’s force acting on a drift current loop. This balance written in integral form provides the basis for quantitative estimations of HETs’ parameters and scaling models.
A switched quasi Z-source three-port (SqZSTP) DC-DC converter for a photovoltaic power generation system
Authors: Dhinesh V , Vijayakumar G
Published: December 2021

In this paper, a modified wide-input switched quasi Z-source three-port (SqZSTP) DC-DC converter is proposed to interface a photovoltaic inverter with a distributed power generation system. The proposed SqZSTP DC-DC converter constructed with a quasi Z-source impedance network and a three-winding high-frequency transformer offers high voltage gain over a wide input voltage range. In the proposed topology, the input port is divided into two ports, to reduce the power rating and voltage stress across each component. The design and operating principles of the SqZSTP DC-DC converter are presented. The steady state and dynamic performance of the proposed SqZSTP DC-DC converter are compared to other converters that have an impedance network in front. The fuzzy logic controller used in the voltage loop avoids variation in the output voltage when a wide variation in the input voltage happens. In order to test the proposed topology, a scaled-down model with a voltage and power rating of 400 V/1400 W was developed. AT conversion efficiency of 94.5% is achieved.
Pre-metal dielectric PE TEOS oxide pitting in 3D NAND: mechanism and solutions
Authors: Hong Peizhen , Xu Qiang , Hou Jingwen , Bai Mingkai , Zhao Zhiguo , Jin Lei , Huo Zongliang , Li Chunlong
Published: December 2021

In 3D NAND, as the stack number increases, the process cost becomes higher and higher, and the stress problem becomes more and more serious. Therefore, the low cost and low stress plasma enhanced tetraethyl orthosilicate (PE TEOS), compared to high density plasma (HDP) oxide, shows its superiority as pre-metal dielectric (PMD) oxide layer in 3D NAND. This paper explores the challenges in the application of PE TEOS in 3D NAND PMD oxide layer. In our experiment both PE TEOS and HDP are employed as the PMD oxide for 3D NAND staircase protection. There is not any void found in the two oxide structures. However, oxide pitting is spotted in the subsequent diluted hydrofluoric acid wet etching in the PE TEOS split. Moreover, we observe that the top silicon nitride corrodes in hot phosphoric acid. We study the mechanism of PE TEOS oxide pitting and silicon nitride corroding, propose two solutions: (1) HDP oxide + PE TEOS, and (2) PE TEOS + dry etching. Experimental results demonstrate that our solutions can well address the issue of PE TEOS oxide pitting and effectively protect the staircase structure. This work extends the application of PE TEOS oxide of which the cost and the stress are both low in 3D NAND.
Engineering the shape memory parameters of graphene/polymer nanocomposites through atomistic simulations: On the effect of nanofiller surface treatment
Authors: Amini Mohammad , Hasheminejad Kourosh , Montazeri Abbas
Published: December 2021

This paper aims to comprehend the mechanisms underlying the shape memory behavior of polylactic acid infused with graphene functionalized by four groups of –OH, –CH3, –NH2, and tethered polymer layer. Applying molecular dynamics simulation, it is revealed that the graphene surface treatment enhances the shape fixity ratio of nanocomposites monotonically by increasing the physical cross-linking points within the polymer matrix. The improvement would be even more pronounced by increasing the coverage degree of small functional groups and grafting density of the covalently bonded polymer chains. Monitoring the key parameters illustrates that contrary to the OH groups, which improve the shape recovery value, the other functional groups degrade it by prohibiting the polymer chains mobility. Attempts to explore the governing mechanism demonstrate that shape fixity is improved when the difference between the potential energy variations in the loading and unloading stages increases. Interestingly, shape recovery is only under the influence of conformational entropy, and it is not affected by the potential energy. As such, we also probe variations of the radius of gyration during the recovery stage to address the role of different functionalization procedures on the reported shape recovery parameter.
Violation of magnetic flux conservation by superconducting nanorings
Authors: Mowgood Iris , Melkonyan Gurgen , Dulal Rajendra , Teknowijoyo Serafim , Chahid Sara , Gulian Armen
Published: December 2021

The behavior of magnetic flux in ring-shaped finite-gap superconductors is explored from the view-point of the flux-conservation theorem, which states that under the variation of an external magnetic field ‘the magnetic flux through the ring remains constant’ (see, e.g., Landau and Lifshitz 1960 Electrodynamics of Continuous Media (New York: Pergamon)). Our results, based on the time-dependent Ginzburg–Landau equations and COMSOL modeling, made it clear that in the general case this theorem is incorrect. While for macroscopic rings the corrections are small, for micro- and nanorings they become rather substantial. The physical reasons behind this effect are discussed. The dependence of flux deviation on ring size, bias temperature and the speed of external flux evolution is explored. The detailed structure of flux distribution inside the ring opening, as well as the electric field distribution inside the ring wire cross section, are revealed. Our results and the developed finite element modeling approach can assist in elucidating various fundamental topics in superconducting nanophysics and in the advancement of nanosize superconducting circuits prior to time-consuming and costly experiments.
Metal-free super-wideband THz absorber for electromagnetic shielding
Authors: Soni Anil Kumar , Giri Pushpa , Varshney Gaurav
Published: December 2021

A technique is implemented for obtaining the high absorption over super-wideband (SWB) in a metal-free THz absorber. The multiple resonant modes with wide spectra are generated in a graphite-based resonator placed on a dielectric cavity merging of which provides the SWB response. The low permittivity dielectric slab sandwiched between the graphite sheet at its bottom and graphite resonator at its top acts as the Fabry–Perot cavity where absorption takes place. The high absorption rate of graphite in the THz regime can make it a suitable candidate for its utilization in implementing the broadband absorber. Thus, the molecular transition due to interaction of energy in graphite also provides the high absorption. The absorption bandwidth can further be enhanced by stacking of multiple layers in two different configurations of the proposed unit cell. The absorber maintains the polarization insensitivity due to symmetry and allows the high absorption for the electromagnetic wave incident up to the angle of more than75°.The proposed absorber can be utilized in the THz electromagnetic shielding applications due to its SWB response.
Nonlinear definition of the shadowy mode in higher-order scalar-tensor theories
Authors: De Felice Antonio , Mukohyama Shinji , Takahashi Kazufumi
Published: December 2021

We study U-DHOST theories, i.e., higher-order scalar-tensor theories which are degenerate only in the unitary gauge and yield an apparently unstable extra mode in a generic coordinate system.
We show that the extra mode satisfies a three-dimensional elliptic differential equation on a spacelike hypersurface, and hence it does not propagate.
We clarify how to treat this “shadowy” mode at both the linear and the nonlinear levels.
Trigger primitive generation algorithm in the CMS barrel muon chambers during HL-LHC
Authors: Trevisani N.
Published: December 2021

This contribution presents an update on the Analytical Method (AM) algorithm for trigger primitive (TP) generation in the CMS Drift Tube (DT) chambers during the High Luminosity LHC operation (HL-LHC or LHC phase 2). The algorithm has been developed and validated both in software with an emulation approach, and through hardware implementation tests. The algorithm is mainly divided into the following steps: a grouping (pattern recognition) step that finds the path of a given muon, a fitting step to extract the track parameters (position and bending angle), and a correlation step that matches the information from the different super-layers and with signal from the resistive plate chambers. Agreement between the software emulation and the firmware implementation has been verified using different data samples, including a sample of real muons collected during 2016 data taking. In this contribution, an update of the grouping step using a pseudo-Bayes classifier will be discussed.
Development of a simultaneous imaging system to measure the optical and gamma ray images of Ir-192 source for high-dose-rate brachytherapy
Authors: Nagata J. , Yamamoto S. , Noguchi Y. , Nakaya T. , Okudaira K. , Kamada K. , Yoshikawa A.
Published: December 2021

In high-dose-rate (HDR) brachytherapy, verification of the
Ir-192 source's position during treatment is needed because such a
source is extremely radioactive. One of the methods used to measure
the source position is based on imaging the gamma rays from the
source, but the absolute position in a patient cannot be
confirmed. To confirm the absolute position, it is necessary to
acquire an optical image in addition to the gamma ray image at the
same time as well as the same position. To simultaneously image the
gamma ray and optical images, we developed an imaging system
composed of a low-sensitivity, high-resolution gamma camera
integrated with a CMOS camera. The gamma camera has a 1-mm-thick
cerium-doped yttrium aluminum perovskite (YAIO3: YAP(Ce))
scintillator plate optically coupled to a position-sensitive
photomultiplier (PSPMT), and a 0.1-mm-diameter pinhole collimator
was mounted in front of the camera to improve spatial resolution and
reduce sensitivity. We employed the concept of a periscope by
placing two mirrors tilted at 45 degrees facing each other in front
of the gamma camera to image the same field of view (FOV) for the
gamma camera and the CMOS camera. The spatial resolution of the
imaging system without the mirrors at 100 mm from the Ir-192 source
was 3.2 mm FWHM, and the sensitivity was 0.283 cps/MBq. There was
almost no performance degradation observed when the mirrors were
positioned in front of the gamma camera. The developed system could
measure the Ir-192 source positions in optical and gamma ray
images. We conclude that the developed imaging system has the
potential to measure the absolute position of an Ir-192 source in
real-time clinical measurements.
Screening of waterflooding, hot waterflooding and steam injection for extra heavy crude oil production from Tatarstan oilfield
Authors: Pituganova A , Minkhanov I , Bolotov A , Varfolomeev M
Published: December 2021

Thermal enhanced oil recovery techniques, especially steam injection, are the most successful techniques for extra heavy crude oil reservoirs. Steam injection and its variations are based on the decrease in oil viscosity with increasing temperature. The main objective of this study is the development of advanced methods for the production of extra heavy crude oil in the oilfield of the Republic of Tatarstan. The filtration experiment was carried out on a bulk model of non-extracted core under reservoir conditions. The experiment involves the injection of slugs of fresh water, hot water and steam. At the stage of water injection, no oil production was observed while during steam injection recovery factor (RF) achieved 13.4 % indicating that fraction of immobile oil and non-vaporizing residual components is high and needed to be recovered by steam assisted EORs.
Innovative Methodology for Assessing the Condition, Certification, Systematization and Accounting of Oil-Contaminated Sites
Authors: Mukhametshina E R , Aitov I S
Published: December 2021

The article describes an innovative method for assessing the condition, certification, systematization and accounting of oil-contaminated sites. The paper offers three-dimensional models, tables on the volume content of petroleum products, tables of the distribution of plots into reclamation groups, QR codes and parcel codes necessary for targeted elimination of the consequences of oil and petroleum products spills in the soil. This technique involves the construction of three-dimensional models of oil-contaminated sites, necessary to reflect the volume of soil contamination, numerical visualization of oil pollution volumes using various data tables, as well as the creation of QR codes and parcel codes, which are necessary to improve the system of accounting, storage and certification of oil-contaminated land.
Drilling mud upward velocity modelling in Ansys CFX software
Authors: Ovsepian E E , Leusheva E L , Morenov V A
Published: December 2021

Drilling mud has various functions, one of which is to carry cuttings to the surface. All other things being equal, the removal of cuttings is characterized by the upward velocity. This paper simulates the rheology of polymer-glycolic non-dispersing mud (in particular viscosity) to achieve the required upward velocity in the «Ansys CFX» software. The viscosity of the mud varies from 6 to 12 mPa·s, on production casing drilling in Arctic conditions. The results of the study showed that for such conditions, the viscosity should be in the range from 6 to 8 mPa·s.
Identification of gas hydrate on bottom-simulating reflector characteristics with 2D seismic pre-stack time migration of North Bali Waters
Authors: Sufajar I A , Manik H M , Nainggolan T B , Kusnida D
Published: December 2021

Gas hydrate is a physical compound composed of gas molecules that are formed in a seabed layer characterised by high pressure and low temperature. It is known as one of the alternative non-conventional hydrocarbons besides petroleum and natural gas. One of the identified areas of gas hydrate stability zone is in the North Bali Waters. The North Bali Waters is part of the North East Java Basin, which has oil and gas exploration and production, both conventional and non-conventional. One method of identifying the content of gas hydrates is by looking at the appearance of the Bottom Simulating Reflector (BSR) as shown on the Pre-Stack Time Migrated seismic sections. The detection of gas hydrate zone is determined by the presence of high amplitude, reversed polarity reflection and cross-cut reflection of sedimentary layer. This study aims to determine the existence of a BSR in the waters of North Bali. The procedures for analysing the existence of Bottom Simulating Reflector in this study are pre-processing, processing, and interpretation of 2D marine seismic data. The result shows gas hydrates found with indicated Bottom Simulating Reflector on CDP 35-812 at TWT depth of 1526-1582 ms, characterised by high amplitude-reverse polarity.
Design and implementation of fish freshness detection algorithm using deep learning
Authors: Anas D F , Jaya I , Nurjanah
Published: December 2021

Organoleptic assessment of fresh fish includes specifications for the quality of the eyes, gills, mucus, odor, texture and flesh (color and appearance). However, not everyone has knowledge about it. This research uses the tiny yolov2 to facilitate the determination of fish freshness levels (good quality, medium quality, poor quality) correctly and fast. There are a few stages in this research, included organoleptic test accompanied by taking fish eye image dataset every hour, processing organoleptic test data labeling, training, and validation. There are three types of fish used, consists ofRastrelliger, Euthynnus affinis, andChanos chanos. Detection of fish freshness level for three species was successfully carried out with the result of average precision is 72.9%, average recall is 57.5%, and accuracy is 57.5%. The factors that affect the prediction results in this study is the collection of datasets before the training process is carried out consisting of fish samples obtained from traditional markets, which are considered inadequate so that it affects the organoleptic test process itself, the organoleptic test that was carried out as a reference for image sorting was considered inaccurate because it used less than 30 untrained panelists and dataset imbalance.