bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectro-spatial analysis of elastic wave propagation in nonlinear elastic metamaterial systems with damping
Authors: Liu Mao , Zhou Fujian
Published: November 2022

Different from the linear counterpart, elastic wave propagation in nonlinear elastic metamaterials with damping (EMD) systems has much more novel behaviors. It is little work that reveals the nonlinear wave propagation mechanism in the nonlinear EMD in the literature. In this paper, nonlinear EMD systems with different configurations for the nonlinear elements are constructed to study the nonlinear wave propagation characteristics based on the analytical formulation. Nonlinear wave propagation attenuation characteristics in nonlinear EMD systems are studied in the frequency-domain. Spectro-spatial characteristics of nonlinear traveling wave packet in space- and time-domain are also analyzed to reveal space frequency-domain characteristics. Influences of different configurations for the nonlinear elements on wave propagation in nonlinear EMD systems are discussed. Results shown that locations of band structures can be tuned by changing intensities of nonlinearities in the nonlinear EMD systems, which are not found in the linear system. Moreover, different configurations for the nonlinear elements can lead to localization feature emerged in a nonlinear EMD system, which indicates solitary waves causing from the interaction between dispersion and nonlinearity exist in the nonlinear systems. This interesting wave propagating properties can be used to design new devices for acoustic switches, energy harvesting, and broadband vibration control.
High-energy P2-type Na-layered oxide cathode with sequentially occurred anionic redox and suppressed phase transition
Authors: Lee Sangyeop , Kang Jungmin , Cho Min-kyung , Park Hyunyoung , Ko Wonseok , Lee Yongseok , Ahn Jinho , Lee Seokjin , Sim Eunji , Ihm Kyuwook , Hong Jihyun , Kim Hyungsub , Kim Jongsoon
Published: November 2022

Although anionic-redox-based layered oxide materials have attracted great attention as promising cathodes for Na-ion batteries because of their high practical capacities, they suffer from undesirable structural degradation, resulting in the poor electrochemical behavior. Moreover, the occurrence of stable anionic-redox reaction without the use of expensive elements such as Li, Co, and Ni is considered one of the most important issues for high-energy and low-cost Na-ion batteries. Herein, using first-principles calculation and various experimental techniques, we investigate the combination of vacancy (□) and Ti4+ cations in the transition-metal sites to enable outstanding anionic-redox-based electrochemical performance in the Na-ion battery system. The presence of vacancies in the P2-type Na0.56[Ti0.1Mn0.76□0.14]O2 structure suppresses the large structural change such as the P2–OP4 phase transition, and Ti4+ cations in the structure result in selectively oxidized oxygen ions with structural stabilization during Na+ deintercalation in the high-voltage region. The high structural stability of P2-type Na0.56[Ti0.1Mn0.76□0.14]O2 enables not only the high specific capacity of 224.92 mAh g−1 at 13 mA g−1 (1C = 264.1 mA g−1) with an average potential of ∼2.62 V (vs Na+/Na) but also excellent cycle performance with a capacity retention of ∼80.38% after 200 cycles at 52 mA g−1 with high coulombic efficiencies above 99%. Although there are some issues such as low Na contents in the as-prepared state, these findings suggest potential strategies to stabilize the anionic-redox reaction and structure in layered-oxide cathodes for high-energy and low-cost Na-ion batteries.
Sensitized triplet–triplet annihilation based photon upconversion in full organic and hybrid multicomponent systems
Authors: Ronchi Alessandra , Monguzzi Angelo
Published: November 2022

In the last 15 years, the attention dedicated to organic conjugated systems experienced outstanding growth because of the renewed interest in mechanisms involving triplet states such as singlet fission, thermally activated delayed fluorescence, and intersystem crossing enhanced phosphorescence. Photon upconversion via sensitized triplet–triplet annihilation (sTTA) enables the conversion of low-energy photons into high-energy ones, and it has been proposed in multicomponent systems as an efficient managing strategy of non-coherent photons. This mechanism exploits the annihilation of two optically dark triplet states of emitter moieties to produce high-energy photons. The annihilating triplets are sensitized through Dexter energy transfer by a light-harvester, typically a conjugated molecule or a nanocrystal, so sTTA upconversion is usually performed in bi-component systems. The high yield observed at low excitation intensities stimulated thriving research in the field, leading to the development of a large family of fully organic and hybrid sTTA multicomponent upconverters. Here, we compare the evolution of these two families of systems with respect to the sTTA upconversion main figures of merit, highlighting the strengths and weaknesses of both approaches, according to the results reported in the literature. The data presented are also discussed in the perspective of future developments in the field, pointing out the challenges that are still to be faced for the technological use of the sTTA upconversion process.
Cobalt as a promising dopant for producing semi-insulating β-Ga2O3 crystals: Charge state transition levels from experiment and theory
Authors: Seyidov Palvan , Varley Joel B. , Galazka Zbigniew , Chou Ta-Shun , Popp Andreas , Fiedler Andreas , Irmscher Klaus
Published: November 2022

Optical absorption and photoconductivity measurements of Co-doped β-Ga2O3 crystals reveal the photon energies of optically excited charge transfer between the Co related deep levels and the conduction or valence band. The corresponding photoionization cross sections are fitted by a phenomenological model considering electron–phonon coupling. The obtained fitting parameters: thermal ionization (zero-phonon transition) energy, Franck–Condon shift, and effective phonon energy are compared with corresponding values predicted by first principle calculations based on density functional theory. A (+/0) donor level ∼0.85 eV above the valence band maximum and a (0/−) acceptor level ∼2.1 eV below the conduction band minimum are consistently derived. Temperature-dependent electrical resistivity measurement at elevated temperatures (up to 1000 K) yields a thermal activation energy of 2.1 ± 0.1 eV, consistent with the position of the Co acceptor level. Furthermore, the results show that Co doping is promising for producing semi-insulating β-Ga2O3 crystals.
Overcoming non-radiative losses with AlGaAs PIN junctions for near-field thermophotonic energy harvesting
Authors: Legendre J. , Chapuis P.-O.
Published: November 2022

In a thermophotonic device used in an energy-harvesting configuration, a hot light-emitting diode (LED) is coupled to a photovoltaic (PV) cell by means of electroluminescent radiation in order to produce electrical power. Using fluctuational electrodynamics and the drift-diffusion equations, we optimize a device made of an AlGaAs PIN LED and a GaAs PIN PV cell with matched bandgaps. We find that the LED can work as an efficient heat pump only in the near field, where radiative heat transfer is increased by wave tunneling. A key reason is that non-radiative recombination rates are reduced compared to radiative ones in this regime. At 10 nm gap distance and for 100 cm s−1 effective surface recombination velocity, the power output can reach 2.2 W cm−2 for a 600 K LED, which highlights the potential for low-grade energy harvesting.
Rayleigh waves in nonpolar Al0.7Sc0.3N(112¯0) films with enhanced electromechanical coupling and quality factor
Authors: Feil N. M. , Nair A. , Pashchenko V. , Kirste L. , Ambacher O.
Published: November 2022

This work reports on the growth of 1 µm nonpolar a-plane Al0.7Sc0.3N(112¯0) thin films on an r-plane sapphire Al2O3(11¯02) via magnetron sputter epitaxy. The electro-acoustic properties of the film structures were characterized using surface acoustic wave (SAW) resonators. Measured electrical responses were found to be strongly anisotropic in terms of the wave propagation direction. We identified a sagittal polarized Rayleigh wave mode with large coupling (keff2= 3.7%), increased phase velocity (v= 4825 m/s), as well as high quality factor (Q > 1000) for SAW propagation along the c-axis [0001] and normalized thicknesses h/λ=0.2. Finite element method simulations using electro-acoustic properties of Al0.7Sc0.3N obtained from the density functional theory reproduce our experimental results.
Microstructure and mechanical property of gas tungsten arc and friction stir welds of L12 precipitate FCC high-entropy alloy
Authors: Hsieh Poying , Liao Chihhsien , Liu Hungchih , Lin Poting , Shen Paikeng , Hunag Shaowei , Sato Yutaka S. , Tsai Chewei
Published: November 2022

The welding technology is significant for application of high-entropy alloys (HEAs) in the industry. In this study, the mechanical properties and microstructures of Al0.2Co1.5CrFeNi1.5Ti0.3 after welding by gas tungsten arc (GTA) welding and friction stir welding (FSW) are discussed, respectively. GTA welding of precipitated HEAs resulted in the formation of dendrites in the fusion zone; the hardness and tensile strength of the GTA weld decreased to 68% and 51% compared to the base metal, respectively. However, FSW exhibited excellent mechanical properties, which were still over 94% of the hardness value and tensile strength of the base metal. The microstructure was characterized by discontinuous dynamic recrystallization and the grain refinement effect in the stir zone. The microstructure of the two welds resulted in different mechanical properties. The weld after FSW was strengthened by the grain refinement strengthening, which almost compensates the decrease in hardness caused by the re-dissolution of all precipitates in the stir zone, while the dendritic structure strongly affected the mechanical properties and softened the fusion zone after the GTA process. During the tensile test, the digital image correlation was conducted simultaneously. It shows that the GTA weld had lower strength with nonuniform deformation in the fusion zone, while the FSW weld showed higher strength with uniform deformation.
Enhancing wind power forecasting from meteorological parameters using machine learning models
Authors: Singh Upma , Rizwan M.
Published: November 2022

Short-term wind power forecasting is crucial for power system stability, dispatching, and cost control. Wind energy has the potential to be a viable source of renewable energy. Wind power generation forecasting is vital for resolving the supply and demand challenges of the smart grid. Moreover, one of the most problematic aspects of wind power is its high fluctuation and intermittent nature, which makes forecasting difficult. The goal of this research is to create machine learning models that can properly estimate wind power production. Significantly, the major contributions of this work are highlighted in the following significant elements. First, a data analysis framework for visualizing the gathered dataset from the SCADA system is presented. Second, for forecasting wind power time-series dataset values, we examine the predicting performance of various machine learning models using various statistical indices. The experimental findings demonstrate that with a minor reconstruction error, the proposed forecast approaches can minimize the complexity of the forecasting. Furthermore, in terms of forecast accuracy, a gradient boosting regression model outperforms other benchmark models. According to the analysis, our methodology might be applied in real-world circumstances to assist the management group in regulating the power provided by wind turbines.
Detection of high energy ionizing radiation using deeply depleted graphene–oxide–semiconductor junctions
Authors: Ruiz Isaac , Vizkelethy Gyorgy , McDonald Anthony E. , Howell Stephen W. , Thelen Paul M. , Goldflam Michael D. , Beechem Thomas E.
Published: November 2022

Graphene’s linear band structure and two-dimensional density of states provide an implicit advantage for sensing charge. Here, these advantages are leveraged in a deeply depleted graphene–oxide–semiconductor (D2GOS) junction detector architecture to sense carriers created by ionizing radiation. Specifically, the room temperature response of a silicon-based D2GOS junction is analyzed during irradiation with 20 MeV Si4+ ions. Detection was demonstrated for doses ranging from 12 to 1200 ions with device functionality maintained with no substantive degradation. To understand the device response, D2GOS pixels were characterized post-irradiation via a combination of electrical characterization, Raman spectroscopy, and photocurrent mapping. This combined characterization methodology underscores the lack of discernible damage caused by irradiation to the graphene while highlighting the nature of interactions between the incident ions and the silicon absorber.
Charging storage phosphors using a white flashlight via the upconversion approach
Authors: Shi Tingxing , Chen Feng , Zhao Xiyu , Zhang Jiahua , Wang Xiao-Jun , Liu Feng
Published: November 2022

As an emerging approach to charge storage phosphors, upconversion charging (UCC) is attracting increased attention owing to its fundamental and practical perspectives. Despite the potential, further development of the UCC technology is restricted by the limited types of excitation light sources. Here, we use a white flashlight as excitation to investigate the UCC performance of storage phosphors. We demonstrate, as an example, that a Y3Al2Ga3O12:Pr3+ phosphor exhibits long-lasting emissions in the ultraviolet and visible regions after intense illumination from the flashlight. Thermoluminescence investigations reveal that both excited-state absorption and energy-transfer upconversion are involved in the UCC process. Based on the luminescence performance of the white-light charged phosphor, a conceptual thermometry approach is introduced, which can remotely sense the local temperature by monitoring the afterglow intensity ratio. Considering the wide use of flashlight, such a white-light excitability and the associated glow emission may potentially revolutionize the way to utilize storage phosphors.
Swollen cubic phases with reduced hardness solubilizing a model fragrance oil as a co-surfactant
Authors: Tchakalova Vera , Zemb Thomas , Testard Fabienne
Published: November 2022

Swollen cubic lyotropic ternary phases with Pn3m symmetry and reduced hardness were obtained from a specific binary mixture of cubic phase-forming (phytantriol) and lamellar phase-forming (decaglycerol monooleate) compounds. The microstructures were determined by using a small-angle x-ray scattering technique. The softness and temperature-induced phase transitions were investigated by means of rheology. The incorporation of a surface-active fragrance compound (linalool) at concentrations up to 6 wt. % induced a structural transition toward a softer Im3m bulk cubic phase with longer water channels. Higher linalool concentrations allowed for the spontaneous dispersion of the bulk cubic phase into microscopic particles with a cubic structure (cubosomes).
Transition behavior of the seizure dynamics modulated by the astrocyte inositol triphosphate noise
Authors: Li Jiajia , Feng Peihua , Zhao Liang , Chen Junying , Du Mengmeng , Song Jian , Wu Ying
Published: November 2022

Epilepsy is a neurological disorder with recurrent seizures, which convey complex dynamical characteristics including chaos and randomness. Until now, the underlying mechanism has not been fully elucidated, especially the bistable property beneath the epileptic random induction phenomena in certain conditions. Inspired by the recent finding that astrocyte GTPase-activating protein (G-protein)-coupled receptors could be involved in stochastic epileptic seizures, we proposed a neuron–astrocyte network model, incorporating the noise of the astrocytic second messenger, inositol triphosphate (IP3) that is modulated by G-protein-coupled receptor activation. Based on this model, we have statistically analyzed the transitions of epileptic seizures by performing repeatable simulation trials. Our simulation results show that the increase in the IP3 noise intensity induces depolarization-block epileptic seizures together with an increase in neuronal firing frequency, consistent with corresponding experiments. Meanwhile, the bistable states of the seizure dynamics were present under certain noise intensities, during which the neuronal firing pattern switches between regular sparse spiking and epileptic seizure states. This random presence of epileptic seizures is absent when the noise intensity continues to increase, accompanying with an increase in the epileptic depolarization block duration. The simulation results also shed light on the fact that calcium signals in astrocytes play significant roles in the pattern formations of the epileptic seizure. Our results provide a potential pathway for understanding the epileptic randomness in certain conditions.
Dynamical stability of random delayed FitzHugh–Nagumo lattice systems driven by nonlinear Wong–Zakai noise
Authors: Yang Shuang , Li Yangrong , Caraballo Tomás
Published: November 2022

In this paper, two problems related to FitzHugh–Nagumo lattice systems are analyzed. The first one is concerned with the asymptotic behavior of random delayed FitzHugh–Nagumo lattice systems driven by nonlinear Wong–Zakai noise. We obtain a new result ensuring that such a system approximates the corresponding deterministic system when the correlation time of Wong–Zakai noise goes to infinity rather than to zero. We first prove the existence of tempered random attractors for the random delayed lattice systems with a nonlinear drift function and a nonlinear diffusion term. The pullback asymptotic compactness of solutions is proved thanks to the Ascoli–Arzelà theorem and uniform tail-estimates. We then show the upper semicontinuity of attractors as the correlation time tends to infinity. As for the second problem, we consider the corresponding deterministic version of the previous model and study the convergence of attractors when the delay approaches zero. That is, the upper semicontinuity of attractors for the delayed system to the non-delayed one is proved.
Optically thick GaInAs/GaAsP strain-balanced quantum-well tandem solar cells with 29.2% efficiency under the AM0 space spectrum
Authors: France Ryan M. , Selvidge Jennifer , Mukherjee Kunal , Steiner Myles A.
Published: November 2022

GaAs is often used as a multijunction subcell due to its high material quality on GaAs substrates, despite having a non-optimal bandgap. The bandgap can be beneficially reduced using many layers of thin, strain-balanced GaInAs in a superlattice or quantum well device, but achieving excellent carrier collection without increased recombination has proven challenging. Here, we develop and demonstrate high performance, optically thick GaInAs/GaAsP strain-balanced solar cells. Excellent material quality is achieved in thick superlattices by using growth conditions that limit progressive thickness and composition fluctuations. Bandgap-voltage offsets as low as 0.31 V are shown in superlattice cells using thin, highly strained GaP barriers. Optically thick superlattice cells with over 2500 nm of total GaInAs in the depletion region are developed, enabling 3.8 mA/cm2 of extra photocurrent beyond the GaAs band edge under the AM0 space spectrum. Optimized superlattice solar cells are incorporated into two-junction devices that achieve 29.2% efficiency under the AM0 space spectrum due to their improved bandgap combination and high subcell voltages.
An ultra-fast liquid switch for terahertz radiation
Authors: Buchmann Adrian , Hoberg Claudius , Novelli Fabio
Published: November 2022

Ultra-fast switches are essential devices for basic research and technological development. Here, we demonstrate that aqueous solutions of sodium iodide can be used for this purpose. When pumped with an intense optical pulse at 400 nm, these water-based liquids display large and fast responses in the terahertz range, around 1 THz. In a 9M NaI solution at a temperature comprised between 10 and 50 °C, the relative variation of the terahertz peak transmission drops by 20% at the pump–probe overlap and recovers with a fast time constant of ∼70 fs. As the optical properties of the liquid vary on a timescale shorter than the terahertz cycle, it is possible to tailor the shape of the transmitted terahertz fields. In this way, we demonstrate the frequency upshifting of terahertz radiation from about 1 to 3 THz and beyond with an efficiency of 4%.
Electrohydrodynamic instability and disintegration of low viscous liquid jet
Authors: Wang Zhentao , Kong Qian , Li Bin , Tian Jiameng , Yu Kai , Wang Junfeng
Published: November 2022

The simple-jet mode can be developed from dripping, dripping faucet (transition), and jetting when subjected to a sufficient strong electric field caused by a needle-plated electrode. In the present work, the instability and disintegration of an electrified jet of anhydrous ethanol in the electrohydrodynamic simple-jet mode are visualized by a high-speed camera. A systematic analysis and description on the evolution of the breakup morphology of the charged jet in the simple-jet mode was carried out. In the dripping mode at low Weber number, the unstable simple-jet occurs, while the stable simple-jet mode happens as Weber number higher than critical value. In a dripping faucet and jetting regime, the simple-jet mode can easily take place, and jet undergoes typical breakup modes including varicose, whipping, whipping assisted bifurcation, and ramified instabilities as electric potential increases. The growth rate of the maximum perturbation of the zero-, first-, and second-order surface waves determines the type of the instabilities. The operating window of the simple-jet mode is presented to indicate that the simple-jet mode only operates in the suitable range of Weber number and electric Bond number. The spray characteristics, including envelope angle, droplet size, and the stable length of the electrified jet, have been explored to demonstrate that the uniform drops could be generated in the simple-jet regime. The evolution from the cone-jet to the simple-jet mode is also observed when a special hemispherical nozzle is used. For an almost stable electric potential, the cone-jet can gradually transform into the simple-jet with an increase in the liquid flow rate.
In utero exposure to the Great Depression is reflected in late-life epigenetic aging signatures
Authors: Schmitz Lauren L. , Duque Valentina
Published: November 2022

Research on maternal-fetal epigenetic programming argues that adverse exposures to the intrauterine environment can have long-term effects on adult morbidity and mortality. However, causal research on epigenetic programming in humans at a population level is rare and is often unable to separate intrauterine effects from conditions in the postnatal period that may continue to impact child development. In this study, we used a quasi-natural experiment that leverages state-year variation in economic shocks during the Great Depression to examine the causal effect of environmental exposures in early life on late-life accelerated epigenetic aging for 832 participants in the US Health and Retirement Study (HRS). HRS is the first population-representative study to collect epigenome-wide DNA methylation data that has the sample size and geographic variation necessary to exploit quasi-random variation in state environments, which expands possibilities for causal research in epigenetics. Our findings suggest that exposure to changing economic conditions in the 1930s had lasting impacts on next-generation epigenetic aging signatures that were developed to predict mortality risk (GrimAge) and physiological decline (DunedinPoAm). We show that these effects are localized to the in utero period specifically as opposed to the preconception, postnatal, childhood, or early adolescent periods. After evaluating endogenous shifts in mortality and fertility related to Depression-era birth cohorts, we conclude that these effects likely represent lower bound estimates of the true impacts of the economic shock on long-term epigenetic aging.
Vestibular evoked potential response in adults with type 1 diabetes
Authors: Hamed Sherifa Ahmed , Fahim Dalia Fahim Mohammed
Published: November 2022

Purpose

Vestibular system is critical for maintaining balance. This study aimed to determine the function of the saccule of the otolith organ in adults with type 1 diabetes (T1D) using cervical vestibular evoked myogenic potential (cVEMP) and its independently associated demographic, clinical and laboratory variables.

Method

This case-control cross-sectional study included 60 patients (male = 15; female = 45) and 30 healthy adults. They underwent cVEMP.

Results

Patients had mean age of 30.63 ± 4.20 years and duration of illness of 14.68 ± 3.65 years. More than 50% had frequent diabetic ketoacidosis (DKA), 30% had frequent hypoglycaemic attack, 35% had comorbid hyperlipidaemia, and 40% had peripheral neuropathy. Dizziness was reported in 30%. Compared to controls, 40% of patients had significantly delayed absolute latencies of P1 and N1 (p = 0.01) either unilateral or bilateral and 80% had reduced P1-N1 amplitudes (p = 0.001). Higher frequencies of abnormalities were present bilaterally. Asymmetry ratio (AR) was reported in 25%. Patients with longer duration of diabetes (>5 year), dizziness, HbA1c (>7%), frequent DKA or hypoglycaemic attacks and peripheral neuropathy had significantly prolonged P1 and N1 latencies and reduced P1-N1 amplitudes compared to those with shorter duration of diabetes, without dizziness, with HbA1c% ≤7%, low frequency of DKA hypoglycaemic attacks and those without peripheral neuropathy. Multiple regression analysis showed that presence of delayed P1 latencies and reduced P1-N1 amplitudes were significantly correlated with duration of diabetes > 5 years [OR = 3.60 (95%CI = 1.80–6.44), p = 0.01; OR = 4.56 (95%CI = 2.80–7.80), p = 0.01] and HbA1c levels >7% [OR = 5.26(95%CI = 3.83–8.05), p = 0.001; OR = 4.55(95%CI = 2.45–8.55), p = 0.001].

Conclusion

The dysfunctions of the saccule of otolith organ and/or its pathway are prevalent in adults with T1D and correlated with duration and severity of diabetes. Therefore, optimal control of glycemic control is essential.
Quantum Engineering of Helical Charge Migration in HCCI
Authors: Liu ChunMei , Manz Jörn , Wang Huihui , Yang Yonggang
Published: November 2022

Electronic charge of molecules can move on time scales when the nuclei stand practically still, from few hundreds of attoseconds to few femtoseconds. This ultrafast process is called “charge migration”. A typical consequence is rapid change of electronic dipole, which points to the center of charge. Corresponding linear (one-dimensional, 1D) and planar (2D) dipolar motions have already been well documented. Here we construct the first case of charge migration which causes chiral 3D dipolar motion, specifically along a helix about oriented iodo-acetylene (HCCI). Quantum dynamics simulations show that this can be induced by well-designed laser pulses.
Revisiting the photonic orbital Hall effect with the vortex mode decomposition
Authors: Mei Wang , Tan Yawei , Zhang Zan , Cheng Jiahao , Cao Yong , Ling Xiaohui
Published: November 2022

The photonic orbital Hall effect (POHE) refers to the vortex-dependent beam shifts, which is generally believed to result from the conversion of intrinsic orbital angular momentum (IOAM) to extrinsic orbital angular momentum (EOAM). However, the physical mechanism of the POHE, such as how the IOAM is converted to the EOAM, remains further elucidation. In this paper, we re-examine the POHE of a vortex beam with additional IOAM illuminating at an optically thin slab by means of vortex mode decomposition. By considering the competition and coupling between the radial and azimuthal vortex harmonics of the abnormal mode in the transmitted beam, it is found that the underlying mechanism of the POHE is in fact a spin-to-orbital angular momentum (OAM) conversion process. And the IOAM carried by the incident beam is directly superimposed on the OAM obtained during the conversion. Our findings not only offer an alternative perspective for understanding the POHE, but also exhibit application potential in orbit–orbit and spin–orbit optical components.
Anisotropic magneto-optical transport properties in black phosphorus induced by in-plane magnetic field
Authors: Wu Ping , Shi Zhen-Gang , Chen Xiongwen , Zhou Xiaoying
Published: November 2022

We study the Landau levels and magneto-optical properties of bulk black phosphorus (BP) subjected to an in-plane magnetic field along the armchair direction based on an effective

k
⋅
p

Hamiltonian. We analytically obtain the Landau levels by the perturbation method, which agrees well with the results of numerical diagonalization. By using the Kubo formula, we find the magneto-optical transition selection rules and conductance spectra for inter-band transitions are highly anisotropic. In particular, for linearly polarized light along the armchair direction, the magneto-optical transition selection rule is

Δ
n

= 0, where n is the Landau level index. However, for linearly polarized light along the zigzag and stacking direction, the magneto-optical transition selection rules become

Δ
n

= ±1. The magneto-optical conductance excited by linearly polarized light along the armchair direction is two order of magnitude larger than those excited by linearly polarized light along the zigzag and stacking direction because the inter-band coupling only exists in the armchair direction. Our results are useful to detect the band parameters of BP and design magnetically controlled optical devices based on it.
Three-dimensional defects detection of high-voltage cable joint based on iterative residual fitting
Authors: Zheng Zhihao , Bian Jiayin , Gao Yuqun , He Shuqi , Liu Wanzhong , Song Tao , Liu Guihua
Published: November 2022

Aiming at the three-dimensional (3D) defects detection of high-voltage cables joint, a method based on iterative residual fitting is proposed. The 3D point cloud data was obtained by reconstructing the laser line projected onto the surface of the high-voltage cable joint. In order to remove noise generated by reconstruction which is located above or below the curve, a simple and effective strategy that the noise can be filtered by the gradient change in the neighborhood is adopted. Then a continuous iterative residual fitting method is proposed to effectively reduce the interference of the defect area on the curve fitting accuracy, thereby obtaining the accurate equation expression of the cable surface curve. By comparing the residual value of the high-voltage cable surface points relative to the fitting curve, the points of the defect area are marked. Finally 3D defect area is extracted through segmentation and clustering. Experiments have verified the effectiveness of the proposed method on artificial standard size defects and real manual ground defects. The absolute error of the depth (height) of artificial standard size defects is less than 0.05 mm. Compared with the traditional cylindrical fitting method, it can be seen that the recognition rate of the proposed method for manually ground defects of high-voltage cable joint is much higher than that of cylinder fitting method.
Multilayer interface tracking model of pure tungsten oxidation
Authors: Huang Shu , Kerr Ryan , Murphy Samuel , Gilbert Mark R , Marian Jaime
Published: November 2022

We present a numerical model to predict oxide scale growth on tungsten surfaces under exposure to oxygen at high temperatures. The model captures the formation of four thermodynamically-compatible oxide sublayers, WO2, WO2.72, WO2.9, and WO3, on top of the metal substrate. Oxide layer growth is simulated by tracking the oxide/oxide and oxide/metal interfaces using a sharp-interface Stefan model coupled to diffusion kinetics. The model is parameterized using selected experimental measurements and electronic structure calculations of the diffusivities of all the oxide subphases involved. We simulate oxide growth at temperatures of 600∘C and above, extracting the power law growth exponents in each case, which we find to deviate from classical parabolic growth in several cases. We conduct a comparison of the model predictions with an extensive experimental data set, with reasonable agreement at most temperatures. While many gaps in our understanding still exist, this work is a first attempt at embedding the thermodynamic and kinetic complexity of tungsten oxide growth into a comprehensive mesoscale kinetic model that attempts to capture the essential features of tungsten oxidation to fill existing knowledge gaps and guide and enhance future tungsten oxidation models.
Unidirectional Rashba spin splitting in single layer WS2(1−x)Se2x alloy
Authors: Zribi Jihene , Pierucci Debora , Bisti Federico , Zheng Biyuan , Avila José , Khalil Lama , Ernandes Cyrine , Chaste Julien , Oehler Fabrice , Pala Marco , Maroutian Thomas , Hermes Ilka , Lhuillier Emmanuel , Pan Anlian , Ouerghi Abdelkarim
Published: November 2022

Atomically thin two-dimensional (2D) layered semiconductors such as transition metal dichalcogenides have attracted considerable attention due to their tunable band gap, intriguing spin-valley physics, piezoelectric effects and potential device applications. Here we study the electronic properties of a single layer WS1.4Se0.6 alloys. The electronic structure of this alloy, explored using angle resolved photoemission spectroscopy, shows a clear valence band structure anisotropy characterized by two paraboloids shifted in one direction of the k-space by a constant in-plane vector. This band splitting is a signature of a unidirectional Rashba spin splitting with a related giant Rashba parameter of 2.8 ± 0.7 eV Å. The combination of angle resolved photoemission spectroscopy with piezo force microscopy highlights the link between this giant unidirectional Rashba spin splitting and an in-plane polarization present in the alloy. These peculiar anisotropic properties of the WS1.4Se0.6 alloy can be related to local atomic orders induced during the growth process due the different size and electronegativity between S and Se atoms. This distorted crystal structure combined to the observed macroscopic tensile strain, as evidenced by photoluminescence, displays electric dipoles with a strong in-plane component, as shown by piezoelectric microscopy. The interplay between semiconducting properties, in-plane spontaneous polarization and giant out-of-plane Rashba spin-splitting in this 2D material has potential for a wide range of applications in next-generation electronics, piezotronics and spintronics devices.
Current density-induced emergence of soft and hard magnetic phases in Fe nanowire arrays
Authors: Noori Farzaneh , Almasi Kashi Mohammad , Montazer Amir H
Published: November 2022

The capability of generating magnetically soft and hard phases in a material is important in many aspects, ranging from basic science to applications. Here, the emergence of soft and hard magnetic phases is reported in Fe nanowire (NW) arrays with a diameter of 35 nm fabricated by using a pulsed electrochemical deposition method in porous aluminum oxide templates under different current density (C

d
) values in the range of 25–100 mA cm−2. The variation of C

d
influences the grain size, crystallinity, electrodeposition efficiency and length of the Fe NWs, as characterized by x-ray diffraction, high-resolution transmission electron microscopy, vibrating sample magnetometry and field-emission scanning electron microscopy. Increasing C

d
from 25 to 80 mA cm−2 results in a significant decrease in coercivity and squareness from 1590 to 900 Oe and 0.9 to 0.5, respectively, inducing the soft and hard phases along the length of Fe NWs. Further increasing the C

d
leads to the separation of the phases, as evidenced by first-order reversal curve analysis. From a theoretical aspect, the emergence of the soft phase may lead to the occurrence of the fanning reversal mode in the NWs, for which there is no precedent in previous experimental investigations.
New insights into the lightning discharge processes
Authors: Rakov V A , Tran M D , Zhu Y , Ding Z , Leal A F R , Kereszy I , Chen S
Published: November 2022

This review covers selected results of recent observations of lightning discharges performed across the entire electromagnetic spectrum (radiofrequency, optical, and energetic radiation) at the Lightning Observatory in Gainesville, Florida. The most important results include (a) characterization of the preliminary-breakdown, stepped-leader, and return-stroke processes in high-intensity (⩾50 kA) negative lightning discharges, (b) the first high-speed video images of bidirectional leader that made contact with the ground and produced a return stroke, (c) discovery of negative stepped leader branches colliding with the lateral surface of neighboring branches of the same leader, (d) new data on the occurrence context and properties of compact intracloud discharges, and (e) observation of a terrestrial gamma-ray flash that occurred during a bipolar cloud-to-ground lightning discharge. The results serve to improve our understanding of the physics of lightning with important implications for lightning modeling, lightning protection, and high-energy atmospheric physics studies.
Surface resistance effects of medium temperature baking of buffered chemical polished 1.3 GHz nine-cell large-grain cavities
Authors: Yang Zhitao , Hao Jiankui , Quan Shengwen , Lin Lin , Wang Fang , Jiao Fei , Liu Hantian , Yao Zeqin , Ren Manqian , Liu Kexin
Published: November 2022

Three 1.3 GHz nine-cell large-grain superconducting niobium cavities were investigated with medium-temperature baking, using buffered chemical polishing to remove the impurity profiles from previous heat treatments. The average intrinsic quality factor in 2 K vertical tests of the cavities was 2.7 × 1010 at 16 MV m−1 with maximum accelerating gradients of 20–22 MV m−1. These promising values confirmed the effectiveness of an improved medium-temperature baking recipe for niobium cavities, beneficial for superconducting radiofrequency applications. Furthermore, resistance analysis demonstrated that medium-temperature baking reduced both the Bardeen–Cooper–Schrieffer (BCS) resistance and the residual resistance of the cavities. Impurity analysis on niobium samples provided some proof that the reduction in BCS resistance was due to the shortened electron mean free path while the reduction in residual resistance was probably associated with mitigation of the increase in interstitial impurity atoms.
Singularity formation in asymptotically safe cosmology with inhomogeneous equation of state
Authors: Trivedi Oem , Khlopov Maxim
Published: November 2022

Interest in cosmological singularities has remarkably grown in recent times, particularly on future singularities with the discovery of late-time acceleration of the universe and dark energy. While such explorations have previously been done in various modified gravity and quantum gravitationally inspired cosmologies (besides standard general relativistic cosmology), no such an endeavour has been taken up till now in the realms of renormalization group approaches to cosmology and we have hence took up on this journey. In this work, we consider the formation of cosmological singularities in an asymptotically safe cosmology where the cut off scale is proportional to the Hubble parameter. We consider a well motivated inhomogeneous form of the equation of state(EOS) as well. We firstly delve into some basics of this cosmology and show that such a scenario permits a transition between phantom and quintessence forms of universal evolution. We then show that one can have Type I - Type IV singularities in such a cosmology for various version of the EOS and that the singularities can occur both in finite and infinite time. The conditions in which these singularities occur is significantly different than how they occur in the standard cosmology, with the formulations being even more involved. Interestingly this difference comes about without the need of any free parameters in the cosmological models, which is usually what one observes when one goes for the same pursuit via various modified gravity/ QG inspired cosmological approaches. Furthermore, we showed that usual singularity removal methods like conformal anomaly effects and f(R) gravity effects do not offer much hope for singularity removal in this cosmology.
Multiple interactions between fishbone instabilities and internal transport barriers in EAST plasmas
Authors: Ge Wanling , Wang Zheng-Xiong , Wang Feng , Liu Zixi , Xu Liqing
Published: November 2022

Fishbone instabilities and internal transport barriers (ITBs) are frequently and sequentially observed in tokamak plasmas. Recently, the relationship between fishbone instabilities and ITBs was numerically studied, mainly on the basis of experimental results (Liu et al 2020 Nucl. Fusion
60 122001). It was identified that a radial electric field can be generated by the fishbone itself, which may act as a trigger for ITB formation. To gain a deeper understanding of this subject, in this work we further demonstrate the multiple interactions between fishbone instability and ITBs in Experimental Advanced Superconducting Tokamak (EAST) experiments (discharge #56933) using the hybrid kinetic-MHD code M3D-K. In multiple-n simulations, it is found that a zonal electric field can be induced in the nonlinear fishbone stage, leading to a relatively large E × B zonal flow that is sufficient to suppress the dominant microinstability before ITB formation; this should account for ITB triggering. After the ITB is triggered, the equilibrium pressure gradient increases and fast ions from the neutral beam injection accumulate in the ITB region. Linear simulations are performed to analyze the effect of ITB formation on fishbone instability. It is shown that due to the change of the pressure gradient during ITB expansion, the change in the bootstrap current density profile modifies the q-profile and then stabilizes the fishbone mode. Additionally, the accumulation of the fast ions leads to a broadening of fast ion distribution around the ITB region, which also has a stabilizing effect on the fishbone mode.
Stellarator coil optimization supporting multiple magnetic configurations
Authors: Lee Brandon F. , Paul Elizabeth J. , Stadler Georg , Landreman Matt
Published: November 2022

We present a technique that can be used to design stellarators with a high degree of experimental flexibility. For our purposes, flexibility is defined by the range of values the rotational transform can take on the magnetic axis of the vacuum field while maintaining satisfactory quasisymmetry. We show that accounting for configuration flexibility during the modular coil design improves flexibility beyond that attained by previous methods. Careful placement of planar control coils and the incorporation of an integrability objective enhance the quasisymmetry and nested flux surface volume of each configuration. We show that it is possible to achieve flexibility, quasisymmetry, and nested flux surface volume to reasonable degrees with a relatively simple coil set through an NCSX-like example. This example coil design is optimized to achieve three rotational transform targets and nested flux surface volumes in each magnetic configuration larger than the NCSX design plasma volume. Our work suggests that there is a tradeoff between flexibility, quasisymmetry, and volume of nested flux surfaces.
Variation of coastal resource potential in Tejakula District
Authors: Citra I P A , Purwanto I P A
Published: November 2022

This research was conducted in Tejakula District, Buleleng Regency with the aim of (1) describing the potential of coastal resources in Tejakula District, (2) analyzing the level of potential coastal resources in each coastal village in Tejakula District. This research uses descriptive design. Data were collected through observation, interview, and documentation techniques and then analyzed qualitatively. The results showed the highest potential of biological resources in the form of fish resources, coral reefs and turtles, non-biological resources in the form of salt ponds, artificial resources in the form of boats, and environmental services in the form of marine tourism including (dolphin attraction, snorkeling, and dive). Second, variations in the potential of coastal resources in Tejakula District are grouped into three. The potential of coastal resources with a high category is in Tejakula Village because coastal resources have been fully managed, especially the utilization of tourism potential, coastal resources with moderate potential namely in Bondalem Village, Les Village, and Penuktukan Village because coastal resources are still in management such as developing tourism potential, and coastal resources with low potential are found in Tembok, Sambirenteng, Julah, Sambiran, and Pacung Village because they have not developed tourism potential and only develop fisheries resources.
Estuary boundary based on waters surface salinity in cimandiri estuary and cisadane estuary, indonesia.
Authors: Octavia W D , Supriatna S , Saraswati R
Published: November 2022

Estuary is an exclusive system and have an important role but also have vulnerabilities that can threaten life in the estuary region, so it is necessary to have knowledge of estuarine boundaries so that conservation can be maintained. This study aims to analyze the boundaries of the Cimandiri Estuary and the Cisadane Estuary based on surface water salinity, and analyze the relationship of estuarine surface water salinity with rainfall, sea surface currents and tides in the Cimandiri Estuary and Cisadane Estuary. The variables used in this study are salinity, rainfall, sea surface currents, and tides. The research method use the Cimandiri Algorithm by processing OLI Landsat 8 Imagery in 2018 and 2019. The results of this study are estuary boundaries divided into 3 estuary boundary classes specifically Mexo-oligohaline (0.5-5 ‰), Mexo-mesohaline (5-18 ‰), and Mexo-polyhaline (18-30 ‰). Cimandiri’s salinity value is strongly affected by season, then by tides and last by the currents, it is because the Cimandiri Estuary has a deep waters. Meanwhile in the Cisadane Estuary, the salinity value is strongly influenced by season, then by the currents and tides, and also influenced by freshwater from land, it is because the Cisadane Estuary has a shallow water.
Adsorption of ammonium ions in aqueous solution using raw and treated peat soil
Authors: Yuliani G , Nandatamadini F , Widhiyatna D , Mollah M , Mutiara S , Setiabudi A
Published: November 2022

Peat exists in abundance in many parts of the world, but has low economic value. The presence of active functional groups, in the form of carboxyl and phenolic groups, makes peat an alternative sorbent having high porosity and ion exchange ability. Washing peat soil prior to adsorption has been reported to be effective in increasing its ion exchange capacity. In this study, the effect of peat washing using NaOH on its adsorption capacity for ammonium ions was investigated. The FTIR analysis indicated decreases in -OH absorption at 3300-3600 cm-1, C=O (carboxylate) at 1625 cm-1 and C-O at 1300-1000 cm-1 possibly due to the replacement of H+ by Na+ upon peat washing using NaOH. SEM analyses of peat samples showed a more homogeneous surface morphology upon washing. BET analysis results showed a reduction in surface area, pore size, and pore volume. However, the adsorption study conducted in batch mode indicated that the adsorption capacities of washed and raw peats were 28.08 mg/g and 14.48 mg/g, respectively. It can be concluded that washing peat soil using NaOH solution may alter its surface properties and may be beneficial in improving its adsorption capacity towards ammonium ions in aqueous solution.