bluuebunny/crossref_metadata_2025 huggingface dataset:
Hybrid organic–inorganic perovskite ferroelectrics bring light to semiconducting applications: Bandgap engineering as a starting point
Authors: Yao Jie , Pan Qiang , Feng Zi-Jie , Xiong Yu-An , Sha Tai-Ting , Ji Hao-Ran , Gu Zhu-Xiao , You Yu-Meng
Published: April 2021

Ferroelectrics are attractive due to their great application potential in information storage, optoelectronics, spintronics and sensing. As an important characteristic affecting semiconducting applications, the energy band structure is important for the development of light-emitting devices. Although it is a tremendous challenge to tune the bandgap in inorganic ferroelectric materials due to the strict requirement of structural symmetry for the fragile ferroelectricity, hybrid organic–inorganic perovskite (HOIP) ferroelectrics, which have a flexible structure, provide a new method to optimize the ferroelectric performance and bandgap. Based on the overview of methods for designing ferroelectrics, this Perspective systematically provides in-depth insight into the relationships between the structure–property and bandgap of HOIP ferroelectrics. In addition, we discussed the challenges and directions of HOIP ferroelectrics in semiconducting applications for the future.
Nanoporous Pd1−xCox for hydrogen-intercalation magneto-ionics
Authors: Gößler M. , Topolovec S. , Krenn H. , Würschum R.
Published: April 2021

The use of hydrogen atoms for magneto-ionic applications has only been explored recently. Benefits of hydrogen compared to other ionic species for tuning magnetism are high switching speed and large changes in magnetic moment. Here, we test the influence of hydrogen intercalation on magnetism in nanoporous Pd(1−x)Cox, with Co being located in superparamagnetic clusters, building upon a previously suggested material system. Tailoring the Co concentration and distribution allows the magnitude of the magneto-electric effect to be influenced as well as to gain a deeper understanding of the interaction of hydrogen with magnetic clusters. In situ magnetization measurements are conducted to directly observe the variation in magnetic moment upon hydrogen-charging in nanoporous Pd(1−x)Cox. Temperature-dependent magnetization curves show that interstitial hydrogen atoms lead to an increase in magnetic anisotropy energy, a coupling of individual Co-rich clusters, and the concomitant blocking of their magnetic moments. The large obtained magnetic switching effects upon hydrogen-charging at room temperature (αC,V > 400 Oe V−1; ΔM = 1.5 emu g−1) open up new possibilities to use magneto-ionic effects for real-life applications in magnetic devices.
Phase behavior and percolation in mixed patchy colloids
Authors: Zhu Yiwei , Chapman Walter G.
Published: April 2021

Patchy colloids can be modeled as hard spheres with directional conical association sites. A variety of physical phenomena have been discovered in the patchy colloid system due to its short range and directional interactions. In this work, we combined a cluster distribution theory with generalized Flory and Stockmayer percolation theory to investigate the interplay between phase behavior and percolation for a binary patchy colloid system. The binary patchy colloid system consists of solute molecules with spherically symmetric bonding sites and solvents with two singly bondable sites. Wertheim’s first order thermodynamic perturbation theory (TPT1) has been widely applied to the patchy colloids system and it has been combined with percolation theory to study the percolation threshold. However, due to assumptions behind TPT1, it will lose accuracy for a system in which particles have multiple association sites or multiply bondable sites. A recently proposed cluster distribution theory accurately models association at sites that can form multiple bonds. In this work, we investigate the comparison among cluster distribution theory, TPT1, and Monte Carlo simulation for the bonding states of this binary system in which cluster distribution theory shows excellent agreement with Monte Carlo simulation, while TPT1 has a large deviation with the simulation. Cluster distribution theory was further combined with the Flory and Stockmayer percolation theory to investigate the interplay between phase behavior and percolation threshold. We found that the reduced density and the relative bonding strength of solvent–solvent association and solute–solvent association are key factors for the phase behavior and percolation. Percolation can form at low density and low temperature in the vapor phase of this binary system, where the star-like molecules with 12 long branches formed.
Global solvability in a two-species chemotaxis system with logistic source
Authors: Ren Guoqiang
Published: April 2021

In this paper, we consider a two-species chemotaxis system with a logistic source. We present the global existence of generalized solutions for the two-species chemotaxis system under appropriate regularity assumptions on the initial data. This result partially generalizes and improves previously known ones.
Symmetrical Hopf-induced bursting and hyperchaos control in memristor-based circuit
Authors: Deng Yue , Li Yuxia
Published: April 2021

In this paper, a simple chaotic memristor-based circuit with an external stimulation is proposed, and its basic dynamic properties are demonstrated. When the external perturbation becomes time varying and its frequency is low enough, the system has two-time scales, which can be employed to explore the mechanisms of symmetrical Hopf-induced bursting oscillations and delay effects. Furthermore, delay-times on Hopf-induced bursting at different frequencies of the external stimulation are measured. The results show that the relationship between the delay-time and external frequency is subject to a power law. In order to enhance the existing chaos of the system, a 4D system is developed by adding a nonlinear state feedback controller, which shows hyperchaos under some suitable parameters. These two systems are implemented on Multisim and hardware platforms, and the corresponding experimental results verify the correctness of the numerical simulations.
Cantilever magnetoelectric PZT/Tb–Fe–Co resonators for magnetic sensing applications
Authors: Ngoc N. T. , Agnus G. , Matzen S. , Maroutian T. , Giang D. T. Huong , Lecoeur P.
Published: April 2021

Magnetoelectric material-based cantilever resonators have been considered as a promising solution for magnetic sensing applications. However, most applications focus on bulk piezoelectric (e.g., PZT) laminated composites, which put a critical limit for miniaturizing into micrometer-sized devices. This work aims at demonstrating the potential of a micro-resonator approach with lower power consumption and smaller size. It reports on the fabrication and characterization of a resonant cantilever based on a freestanding multi-ferroic PZT/Tb–Fe–Co thin film multilayer, where the magnetic signal is sensed by measuring the shift of the device resonant frequency. The Tb–Fe–Co layer acts as a magnetic field sensing layer, while the PZT thin film integrated in the capacitor geometry acts as a micro-transducer to obtain an electrical signal. For a magnetic field less than 0.2 T, a sensitivity as high as 487 Hz/T is measured for the sensor under a vacuum environment. While the sensor design has to be further optimized to improve the performance, it is promising as a micro-magnetoelectric sensor for magnetic field sensing.
A compact stilbene crystal neutron spectrometer for NBI-heated plasma neutron diagnostics at EAST
Authors: Liao L. Y. , Zhang Y. M. , Hu Z. M. , Yang D. K. , Ge L. J. , Sun J. Q. , Zhong G. Q. , Hu L. Q. , Wan B. N. , Gorini G. , Nocente M. , Tardocchi M. , Li X. Q. , Fan T. S.
Published: April 2021

Stilbene crystal detectors are widely used as fast neutron measurement tools based on recoil proton detection, such as liquid scintillators. A compact stilbene crystal neutron spectrometer (CSCNS) has been installed at the Experimental Advanced Superconducting Tokamak (EAST) to obtain information on fuel ions produced in the plasma core because of its merits of good n/γ discrimination capability, high detection efficiency, and fast response. For the first time, CSCNS has been used for neutron emission spectroscopy measurements in EAST plasmas with neutral beam injection (NBI) heating. The CSCNS has the same horizontal line of sight as the time-of-flight enhanced diagnostics neutron spectrometer. Under NBI heating scenarios, the time trace of the neutron yield monitored by the CSCNS is similar to the one monitored by a standard 235U fission chamber. The experimental pulse height spectra are also similar to the simulated ones generated by folding the simulated neutron energy spectrum with the detector response functions. These results demonstrate the capability of the CSCNS for neutron diagnostics and the study of fast-ion physics in EAST.
Dataset of noncovalent intermolecular interaction energy curves for 24 small high-spin open-shell dimers
Authors: Madajczyk Katarzyna , Żuchowski Piotr S. , Brzȩk Filip , Rajchel Łukasz , Kȩdziera Dariusz , Modrzejewski Marcin , Hapka Michał
Published: April 2021

We introduce a dataset of 24 interaction energy curves of open-shell noncovalent dimers, referred to as the O24 × 5 dataset. The dataset consists of high-spin dimers up to 11 atoms selected to assure diversity with respect to interaction types: dispersion, electrostatics, and induction. The benchmark interaction energies are obtained at the restricted open-shell CCSD(T) level of theory with complete basis set extrapolation (from aug-cc-pVQZ to aug-cc-pV5Z). We have analyzed the performance of selected wave function methods MP2, CCSD, and CCSD(T) as well as the F12a and F12b variants of coupled-cluster theory. In addition, we have tested dispersion-corrected density functional theory methods based on the PBE exchange-correlation model. The O24 × 5 dataset is a challenge to approximate methods due to the wide range of interaction energy strengths it spans. For the dispersion-dominated and mixed-type subsets, any tested method that does not include the triples contribution yields errors on the order of tens of percent. The electrostatic subset is less demanding with errors that are typically an order of magnitude smaller than the mixed and dispersion-dominated subsets.
A many-body dissipative particle dynamics study of eccentric droplets impacting inclined fiber
Authors: Wang Chenyang , Wu Xiao , Zhang Haixiang , Hao Pengfei , He Feng , Zhang Xiwen
Published: April 2021

The phenomenon of droplets impacting fiber has important applications in the recovery of waste liquid, separation of solid and liquid phases, gas and liquid phases, and glass wool manufacturing. This study explored the impact of droplets on fiber based on the many-body dissipative particle dynamics (MDPD) method. First, the impact of droplets on fiber at different angles was simulated, and the results were found to be in good agreement with the experimental results. We then investigated the influence of droplet eccentricity, fiber tilt angle, and wettability on the collision results and found that droplet critical velocity V*, wetting length L, contact time t, and droplet capture rate all increased with tilt angle and decreased with the increase in eccentricity. In addition, fiber wettability had little effect on contact time t but had a greater effect on critical velocity V*. Except for hydrophobicity, wettability also had little effect on droplet capture rate. The theoretical derivation obtained the analytical formulas of critical velocity V*, dimensionless wetting length L*, and dimensionless contact time t* when the eccentric droplet hits the inclined fiber. The simulation results are highly consistent with the theoretical values. This research possesses important guiding significance for actual production and life.
Plasma–liquid interaction during a pulsed vacuum breakdown
Authors: Barengolts S. A. , Uimanov I. V. , Oreshkin V. I. , Khishchenko K. V. , Oreshkin E. V.
Published: April 2021

The dynamics of phase changes in the material of a copper cathode during the explosion of a microprotrusion on its surface under the action of the explosive electron emission current has been numerically simulated. Numerical data have been obtained that characterize the interaction of the liquid metal and the dense cathode plasma that are formed due to the microprotrusion explosion. It has been shown that, under the action of the pressure exerted by the plasma, the liquid metal is almost completely displaced from the zone of operation of the cathode spot of the vacuum discharge. This leads to the formation of a crater on the cathode surface with microirregularities at its edge. Thus conditions are created for the formation of new microprotrusions, which, when exploding, provide self-sustained and cyclic operation of the vacuum discharge.
Numerical study of interactions between shock waves and a circular or elliptic bubble in air medium
Authors: Chen Jiaojiao , Qu Feng , Wu Xuanting , Wang Zirui , Bai Junqiang
Published: April 2021

The interaction of shock waves with bubbles is of interest in a variety of areas, such as shock wave lithotripsy, cavitation erosion, and sonoluminescence. For these, the spatial technology, which is based on the five-equation model and the finite volume method, is employed to numerically study this issue in this paper. Research on the interaction between shock waves and circular bubbles indicates that the generation and distribution of vorticity have an important influence on the deformation of the bubble interface, and the vorticity will accelerate the turbulent mixing of the two-phase gas. In addition, the interaction processes between shock waves and elliptic bubbles aligned horizontally and elliptic bubbles aligned vertically in air medium with different aspect ratios are investigated. Results show that the time required to generate the transverse jet and vortex structure decreases, and the deformation degree and the collapse speed increase when increasing the aspect ratio of elliptic bubbles aligned horizontally. For elliptic bubbles aligned vertically, the position of the transverse jet is related to the aspect ratio; the greater the aspect ratio, the farther the jet position is from the centerline.
An analytical model for predicting residual stress in TBC-film cooling system considering non-uniform temperature field
Authors: Meng Zewei , Liu Yongbao , Li Yujie , Zhang Yunsong
Published: April 2021

Residual stress is an important parameter to evaluate and predict the interfacial peeling and failure of a thermal barrier coating (TBC) system in the thermal cycle. Considering a non-uniform temperature field, an analytical model for predicting residual stress of the TBC-film cooling system was established. Based on the double-layer TBC-film cooling system, the analytical solutions were validated by comparing with the previous results. Then, the four-layer system, including the superalloy substrate (SUB), the metallic bond coat (BC), the thermally grown oxide (TGO), and the ceramic top coat (TC), was analyzed. The distribution of residual stress was discontinuous at the interface among the layers. The maximum peeling moment occurred at the BC/SUB interface, and the maximum shear stress occurred at the TGO/BC interface. Therefore, the probabilities, of which opening edge cracks (mode I) appeared at the BC/SUB interface and shearing edge cracks (mode II) appeared at the TGO/BC interface, were higher than that at other interfaces. The deflection and bending direction of the system were affected by the temperature difference and coefficient of thermal expansions. The large thickness of the coating could effectively improve the thermal insulation capacity of the system, but the peeling moment and shear stress also increased. Therefore, preventing the thermal growth of the TGO layer and reducing the thickness of the TC layer can improve the stability of the system and extend service lifetime of the system while ensuring that the cooling requirements for hot section components are met.
Detailed crystallographic analysis of the ice V to ice XIII hydrogen-ordering phase transition
Authors: Salzmann Christoph G. , Rosu-Finsen Alexander , Sharif Zainab , Radaelli Paolo G. , Finney John L.
Published: April 2021

Ice V is a structurally highly complex material with 28 water molecules in its monoclinic unit cell. It is classified as a hydrogen-disordered phase of ice. Yet, some of its hydrogen-bonded water molecules display significant orientational order. Upon cooling pure ice V, additional orientational ordering cannot be achieved on the experimental time scale. Doping with hydrochloric acid has been shown to be most effective in enabling the phase transition of ice V to its hydrogen-ordered counterpart ice XIII. Here, we present a detailed crystallographic study of this phase transition investigating the effects of hydrochloric and hydrofluoric acid as well as lithium and potassium hydroxide doping. The magnitudes of the stepwise changes in the lattice constants during the phase transition are found to be more sensitive indicators for the extent of hydrogen order in ice XIII than the appearance of new Bragg peaks. Hydrofluoric acid and lithium hydroxide doping enable similar ordering processes as hydrochloric acid but with slower kinetics. The various possible space groups and ordered configurations of ice XIII are examined systematically, and the previously determined P21/a structure is confirmed. Interestingly, the partial hydrogen order already present in ice V is found to perpetuate into ice XIII, and these ordering processes are found to be independent of pressure. Overall, the hydrogen ordering goes along with a small increase in volume, which appears to be the origin of the slower hydrogen-ordering kinetics under pressure. Heating pressure-quenched samples at ambient pressure revealed low-temperature “transient ordering” features in both diffraction and calorimetry.
Recent advances in catalyst materials for proton exchange membrane fuel cells
Authors: Mølmen L. , Eiler K. , Fast L. , Leisner P. , Pellicer E.
Published: April 2021

Research on fuel cell technology is constantly gaining importance, while global emission requirements are becoming more and more restrictive. For environmentally neutral proton exchange membrane fuel cells (PEMFCs) to become a competitive technology, sustainable infrastructures need to be established. One of the main showstoppers is the utilization of the rare and therefore costly precious metal Pt as the key element in the electrocatalysis of hydrogen and oxygen. A huge amount of research is done on immensely reducing or even replacing Pt for future PEMFC technology. In this research update, the progress on oxygen reduction reaction catalysts in acidic media over the past two years is reviewed, with special attention to their durability.
Semi-grand canonical Monte Carlo simulation of the acrolein induced surface segregation and aggregation of AgPd with machine learning surrogate models
Authors: Liu Mingjie , Yang Yilin , Kitchin John R.
Published: April 2021

The single atom alloy of AgPd has been found to be a promising catalyst for the selective hydrogenation of acrolein. It is also known that the formation of Pd islands on the surface will greatly reduce the selectivity of the reaction. As a result, the surface segregation and aggregation of Pd on the AgPd surface under reaction conditions of selective hydrogenation of acrolein are of great interest. In this work, we lay out a workflow that can predict the surface segregation and aggregation of Pd on a FCC(111) AgPd surface with and without the presence of acrolein. We use machine learning surrogate models to predict the AgPd bulk energy, AgPd slab energy, and acrolein adsorption energy on AgPd slabs. Then, we use the semi-grand canonical Monte Carlo simulation to predict the surface segregation and aggregation under different bulk Pd concentrations. Under vacuum conditions, our method predicts that only trace amount of Pd will exist on the surface at Pd bulk concentrations less than 20%. However, with the presence of acrolein, Pd will start to aggregate as dimers on the surface at Pd bulk concentrations as low as 6.5%.
Composition dependence of spin–orbit torques in PtRh/ferromagnet heterostructures
Authors: Shi Guoyi , Liu Enlong , Yang Qu , Liu Yakun , Cai Kaiming , Yang Hyunsoo
Published: April 2021

We experimentally study the spin–orbit torque (SOT) in PtRh/heterostructures by varying the composition of PtRh alloy. By performing dc-biased spin-torque ferromagnetic resonance and second-harmonic measurements in PtxRh1−x/ferromagnet heterostructures, we find that the effective damping-like spin-torque efficiency and spin Hall conductivity are 0.18 and 3.8 × 105 ℏ/2e Ω−1 m−1 for Pt0.9Rh0.1, respectively, with a low resistivity of 46.9 µΩ cm. Furthermore, current induced SOT switching in PtRh/Co is investigated. The critical current density for SOT switching decreases with an increase in the Rh composition of the PtRh alloy, which can be understood by domain wall assisted switching. Due to a large spin Hall conductivity, a relatively low resistivity, and sustainability of the high temperature process, the PtRh alloy could be an attractive spin source for SOT applications.
Bimodal velocity and size distributions of pulsed superfluid helium droplet beams
Authors: Pandey Rahul , Tran Steven , Zhang Jie , Yao Yuzhong , Kong Wei
Published: April 2021

We report detailed measurements of velocities and sizes of superfluid helium droplets produced from an Even–Lavie pulse valve at stagnation pressures of 20–60 atm and temperatures between 5.7 and 18.0 K. By doping neutral droplets with Rhodamine 6G cations produced from an electrospray ionization source and detecting the positively charged droplets at two different locations along the beam path, we determine the velocities of the different groups of droplets. By subjecting the doped droplet beam to a retardation field, size distributions can then be analyzed. We discover that at stagnation temperatures above 8.0 K, a single group of droplets is observed at both locations, but at 8.0 K and below, two different groups of droplets with different velocities are detectable. The slower group, considered from fragmentation of liquid helium, cannot be deterred by the retardation voltage at 9 kV, implying an exceedingly large size. The faster group, considered from condensation of gaseous helium, has a bimodal distribution when the stagnation temperatures are below 12.3 K at 20 and 40 atm, or 16.1 K at 60 atm. We also report similar size measurements using low energy electrons for impact ionization, and this latter method can be used for facile in situ characterization of pulsed droplet beams. The mechanism of the bimodal size distribution of the condensation group and the reason for the coexistence of both the condensation and fragmentation groups remain elusive.
Assessing the correctness of pressure correction to solvation theories in the study of electron transfer reactions
Authors: Hsu Tzu-Yao , Jeanmairet Guillaume
Published: April 2021

Liquid state theories have emerged as a numerically efficient alternative to costly molecular dynamics simulations of electron transfer reactions in solution. In a recent paper [Jeanmairet et al., Chem. Sci. 10, 2130–2143 (2019)], we introduced the framework to compute the energy gap, free energy profile, and reorganization free energy using molecular density functional theory. However, this technique, as other molecular liquid state theories, overestimates the bulk pressure of the fluid. Because of the very high pressure, the predicted free energy is dramatically exaggerated. Several attempts were made to fix this issue, either based on simple a posteriori correction or by introducing bridge terms. By studying two model half reactions in water, Cl → Cl+ and Cl → Cl−, we assess the correctness of these two types of corrections to study electron transfer reactions. We found that a posteriori correction, because it violates the Variational principle, leads to an inconsistency in the definition of the reorganization free energy and should not be used to study electron transfer reactions. The bridge approach, because it is theoretically well grounded, is perfectly suitable for this type of systems.
Einsteinium chemistry captured
Authors: Miller Johanna L.
Published: April 2021

The creation of a rare molecule offers a peek at how heavy atoms interact with other elements.
Magnetic logic driven by electric current
Authors: Gambardella Pietro , Luo Zhaochu , Heyderman Laura J.
Published: April 2021

Spin-based logic gates consume no power when idle, are compatible with CMOS circuitry, and can be seamlessly integrated with memory.
Age estimation of barramundi (
Authors: Wright C. , Wedding B. B. , Grauf S. , Whybird O. J.
Published: April 2021

The age of whole otoliths from barramundi (Lates calcarifer) obtained from the southern Gulf of Carpentaria were estimated using Fourier transform near-infrared (FT-NIR) spectroscopy. Otoliths from 1716 barramundi collected in 2006, 2009 and 2012–2015 were used in this study. Partial least-squares regression models (PLS-R) and multiple linear regression models (MLR) were developed from the diffuse reflectance spectra and the age was obtained from traditional sectioned otoliths. Calibration models were built up over consecutive years (2012–2015) by using a subset of the samples and used to predict the age of the remaining samples and samples from the following year. Results suggest that when seasonal (temporal) variability is incorporated into the calibration model, FT-NIR has the ability to predict barramundi age (validation R2 ranged from 0.73 to 0.78; RMSEP ranged from 6.92 to 7.64 months). The predicted age class was within 1 year of the reference age in over 96% of the samples. These models were also able to predict the age of otoliths from 2006 and 2009, which were retrieved from long-term storage (validation R2 ranged from 0.77 to 0.84; RMSEP ranged from 8.66 to 10.88 months). The results from this study have shown the potential for barramundi from the southern Gulf of Carpentaria to be aged quickly and accurately by using FT-NIR.
Effects of substrate termination on R
on increase under stress in 650 V GaN power devices
Authors: Li Feiyu , Wang Ronghua , Huang Huolin , Ren Yongshuo , Ren Guangshan , Liang Zhuang , Zhou Fubin , Cheng Wanxi , Liang Huinan
Published: April 2021

Buffer related electron trapping and hot electron injection are responsible for R
on degradation in devices, but the effects of substrate termination are still uncertain. In this work, both positive and negative substrate bias are applied to investigate the different vertical trapping mechanisms in 650 V gallium nitride (GaN) power devices. R
on shows an instant and significant increase under vertical bias stress, and the magnitude of downward buffer electron trapping induced R
on increase is relatively larger than that induced by upward trapping. Additionally, the substrate floated and grounded GaN devices are also submitted to both off-state and semi-on-state stresses to investigate the effects of substrate termination on hot electron injection induced R
on increase. The intensity of the upward electron trapping increases faster with temperature resulting in a higher R
on increase than the downward situation. The hot electron effect is only obvious when the substrate is grounded, suggesting that the main injection destination is not in the buffer. The substrate floated device exhibits a lower R
on increase after both off-state and semi-on-state stresses at elevated temperatures. Substrate floated packages are suggested to ensure reliable dynamic performance of device, especially for high voltage application design.
Effects of Se substitution on the Schottky barrier of a MoS
x
Se(2−x)/graphene heterostructure
Authors: Yin Kui , Huang Tao , Wu Hong-Yu , Si Yuan , Lian Ji-Chun , Xiao Yu-Wen , Zhang Zhaogang , Huang Wei-Qing , Hu Wangyu , Huang Guo-Fang
Published: April 2021

One of the most fundamental and challenging tasks to achieve high-performance ultra-thin atomic field effect transistors (FETs) is to obtain very low or even zero Schottky barrier height (SBH) at source/drain contact. Here, we propose that heteroatom substitution is an effective strategy to tune the performance of two-dimensional materials-based FETs, which is demonstrated by systematically exploring the effects of Se substitution on the structural and electronic properties, and SBH of MoS
x
Se(2−x)/graphene (MoS
x
Se(2−x)/G) heterostructures using first-principles calculations. Our findings suggest that the type and height of Schottky barrier can be adjusted by varying Se concentration. The transformation from n-type Schottky barrier to p-type Schottky barrier can be realized when the Se concentration is greater than 25%. With the increase of Se concentration, a lower p-type Schottky barrier can be obtained at the interface to achieve efficient charge transfer. Moreover, the Schottky barrier of MoS
x
Se(2−x)/G heterostructures with different Se concentration would disappear as the external electric field exceeds certain values. These results would provide a direction in developing high-performance FETs involving heteroatom substitution layers as contact electrodes.
Structural and magnetic properties of hard-soft BaFe12O19/(Zn0.5Co0.5)Fe2O4 ferrites
Authors: Fattouh Farah , Rifai Lama , Habanjar Khulud , Abdallah A M , Hassan R Sayed , Yaacoub Nader , Awad Ramadan
Published: April 2021

Hard-soft nanocomposites of (1 − x) BaFe12O19/x(Zn0.5Co0.5)Fe2O4, for x = 0.00, 0.25, 0.50, 0.75 and 1.00, were prepared via co-precipitation and high-speed ball milling techniques, respectively. The synthesized samples were characterized via x-ray diffraction, transmission electron microscope, Fourier transform infrared (FTIR), and vibrating sample magnetometer. XRD revealed the formation of hard-soft nanocomposites. TEM indicated that the two phases are well distributed and the particle size distribution is narrower for low content of soft phase, leading to better exchange coupling between the grains. Magnetic measurements were performed at 300 K and 77 K. The results showed a good single-phase magnetic behavior, verifying the good exchange coupling between hard and soft phases. For low (Zn0.5Co0.5)Fe2O4 content, the dipolar interactions were dominated by the exchange-coupling interactions. Additionally, the optimum values of saturation and remanent magnetizations, coercivity, and squareness ratio were obtained for x = 0.5. This was attributed to the dominance of exchange-coupling interaction. The enhancement of magnetic properties and energy product (BH)max for nanocomposites at low temperature is skilled in the reduction of the thermal fluxes of magnetic moments at the surface. The maximum energy product (BH)max was observed in C2 at both temperatures with a smaller value than that of pure BaFe12O19.
Computational study of first-row transition metals in monodoped 4H-SiC
Authors: Wolfe Timothy S , Van Ginhoven Renee M , Strachan Alejandro
Published: April 2021

Electronic structure calculations of 4H-SiC doped with various transition metals reveal dilute magnetic semiconductor behavior in a material suitable for high-power and high-frequency semiconductor devices. Our results are consistent with prior work on V, Cr, and Mn doping and explore additional metals: Fe, Co, and Ni. Charge-state calculations show that the latter maintain amphoteric semi-insulating properties while offering a non-zero stable spin polarization and also greater asymmetry in the spin density of states than previously studied dopants. This indicates possible enhanced half-metal properties. Our results are consistent with crystal field theory, which helps interpret the observed spin states and assess the degree of charge localization and, subsequently, the range and strength of interactions relevant to ionization/capture and charge transport. These findings provide new avenues to tune the behavior of 4H-SiC for electronic device applications.
The sound of music: determining Young’s modulus using a guitar string
Authors: Pols Freek
Published: April 2021

When a new topic is introduced in the curriculum, teachers seek various ways to teach students the related concepts. For the novel topic ‘materials’ in the revised Dutch curriculum, I developed an experiment in which students determine Young’s modulus using a guitar string. The experiment not only covers several concepts related to ‘materials’ it also provides a clear link to the physics of music and illustrates to students, aged 16, why the topic ‘materials’ could be of interest.
Impact of divertor closure on edge plasma behavior in EAST H-mode plasmas
Authors: Tao Y Q , Xu G S , Yang Q Q , Yan N , Jia G Z , Meng L Y , Liu S C , Chen L , Yu Y W , Gao W , Wang Y M , Wang L , Zang Q , Gao S L
Published: April 2021

A series of H-mode discharges have been conducted in the EAST tokamak to study the effect of divertor closure on divertor neutral distribution and edge plasmas by scanning the location of the outer strike point. When the outer strike point moves close to the corner within ∼

4.5

cm

, the gauge in upper sub-divertor shows that the neutral pressure increases, and the reciprocating probe at outer mid-plane indicates that electron temperature decreases and electron density increases in the scrape-off layer (SOL). In the meantime, the tungsten impurity concentration and radiation power in the main plasma decrease remarkably, while the main plasma density and stored energy increase slightly. SOLPS-ITER simulation without particle drifts is performed to better understand the impact of divertor closure. The simulation clearly demonstrates that a more closed divertor produces more neutrals around the corner with the increase of electron density and the decrease of electron temperature in the SOL, consistent with experimental results. Furthermore, more neutrals escape the divertor region and penetrate into the pedestal region, which induces more pedestal fuelling, increasing pedestal electron density. EAST will upgrade the lower divertor with a more closed geometry. These results provide important guidance for the upcoming upgrade.
Improvement in Schottky barrier inhomogeneities of Ni/AlGaN/GaN Schottky diodes after cumulative γ-ray irradiation
Authors: Visvkarma Ajay Kumar , Sharma Chandan , Saraswat Chanchal , Rawal D S , Vinayak Seema , Saxena Manoj
Published: April 2021

This article reports the effect of gamma (γ)-ray irradiation on barrier inhomogeneities that leads towards improvement in diode parameters in Ni-AlGaN/GaN Schottky diodes. The Schottky diodes were subjected to a cumulative γ-ray dose up to 15 kGy and their current–voltage (I–V) and capacitance–voltage (C–V) characteristics were measured simultaneously at different temperatures during the pristine stage and after each radiation dose. The Schottky barrier height (Φ
b) had an increase of 10% to 20% in the temperature range greater than 250 K. Whereas, the change in the ideality factor (η) was found to be prevalent at lower temperatures (<250 K). More linearity in the behavior of η variation with temperature was found post γ-irradiation showing an improvement in homogeneity of the metal/semiconductor interface. Post γ-ray exposure, barrier inhomogeneities at the metal/semiconductor interface were found to reduce due to annealing effects that also led towards an increase in the contribution of thermionic emission current flow. Further, a decrease of 16% in the standard deviation of the Gaussian distribution of Φ
b around the mean Φ
b was obtained. A decrease in contact resistance (R
C) was deduced using a circular transmission line method, which was also due to the partial annealing effect of γ-ray radiation. Finally, the channel carrier concentration (n
s), extracted using C–V analysis, was found to remain unaltered.
Multifield inflation beyond Nfield=2: non-Gaussianities and single-field effective theory
Authors: Pinol Lucas
Published: April 2021

In this article, we study in detail the linear dynamics and
cubic interactions for any number Nfield of scalar
fields during inflation, directly in terms of the observable
curvature perturbation ζ and Nfield-1 entropic
fluctuations, a choice that is more suitable for analytical works.
In the linear equations of motion for the perturbations, we uncover
rich geometrical effects beyond terms involving just the scalar
curvature of the field space, and that come from the non-canonical
kinetic structure of the scalar fields when the dimension of the
field space is larger than two. Moreover, we show that a fast
rotation of the local entropic basis can result in negative
eigenvalues for the entropic mass matrix, potentially destabilising
the background dynamics when Nfield⩾ 3. We
also explain how to render manifest the sizes of cubic interactions
between the adiabatic and the entropic fluctuations, extending a
previous work of ours to any number of interacting fields. As a
first analytical application of our generic formalism, we derive the
effective single-field theory for perturbations up to cubic order
when all entropic fluctuations are heavy enough to be integrated
out. In a slow-varying limit, we recover the cubic action expected
from the effective field theory of inflation, but with a prediction
for the usual Wilson coefficients in terms of the multifield
parameters, thus proposing a new interpretation of the bispectrum in
this generic Nfield context.
StellarICS: inverse Compton emission from the quiet Sun and stars from keV to TeV
Authors: Orlando Elena , Strong Andrew
Published: April 2021

The study of the quiet Sun in gamma rays started over a
decade ago, and rapidly gained a wide interest.
Gamma rays from the quiet Sun are produced by Galactic Cosmic Rays (CRs) interacting with its surface (disk component) and with its photon field (spatially extended inverse-Compton component, IC). The latter component is maximum close to the Sun and it is above the background even at large angular distances, extending over the whole sky. First detected with EGRET, it is studied now with Fermi-LAT with high statistical significance.

Observations of the IC component allow us to obtain information on CR electrons and positrons close to the Sun and in the heliosphere for the various periods of solar activity and polarity. They allow to learn about CR interactions and propagation in the stellar photosphere and heliosphere, and to understand the solar environment and its activity. Analyses of solar observations are usually model-driven.
Hence advances in model calculations and constraints from precise CR measurements are timely and needed.

Here we present our StellarICS code to compute the gamma-ray IC emission from the Sun and also from single stars.
The code is publicly available and it is extensively used by the scientific community to analyze Fermi-LAT data. It has been used by the Fermi-LAT collaboration to produce the solar models released with the FSSC Fermi Tools.
Our modeling provides the basis for analyzing and interpreting high-energy data of the Sun and of stars.

After presenting examples of updated solar IC models in the Fermi-LAT energy range that account for the various CR measurements, we extend the models to keV, MeV, and TeV energies for predictions for present and future possible telescopes such as AMEGO, GECCO, an e-ASTROGAM-like instrument, HAWC, LHAASO, SWGO, and X-ray telescopes. We also present predictions for some of the closest and most luminous stars.
Four-party deterministic quantum operation sharing with a generalized seven-qubit Brown state
Authors: Zhang Zhanjun , Zhang Lei , Zhuge Bin , Ye Biaoliang
Published: April 2021

A four-party deterministic single-qubit operation sharing scheme is proposed by using a generalized seven-qubit Brown state in a given qubit distribution as the quantum channel. Its security is confirmed via analyses. The sharing determinacy and the sharer symmetry of the scheme are identified. The experimental feasibility of the scheme is confirmed through discussions. Moreover, the scheme is compared with a competing one which utilizes the same quantum channel. It is found that the present scheme reduces the necessary operations and two-qubit unitary operation types as well as the classical communication cost. The decreases of both the necessary operation complexity and the classical communication cost eventually mean both the increase of the scheme efficiency and the decrease of the resource consumption. Consequently, the present scheme is superior to the competing one.
Investigation of vertical carbon nanosheet growth and its potential for microsupercapacitors
Authors: Velasco A. , Vyas A. , Wang K. , Li Q. , Smith A. D. , Lundgren P. , Enoksson P.
Published: April 2021

One of the biggest applications that are coming with the Internet of Things (IoT) are miniaturized sensor networks that connect wirelessly to each other and the internet. Microsupercapacitors (MSCs) are ideal to power these devices, with large cyclability and lifetime. Porous carbons are the material of choice for these devices, but their morphology and manufacturing are far from optimized. Vertically oriented graphene MSCs have shown great promise due to their high specific surface areas and conductivity. In this work, the growth of vertically aligned carbon nanosheets (CNS) on 2-inch wafers has been studied, and it has been used as active material to manufacture MSC and transmission line model (TLM) wafers. The fabricated CNS MSC devices show a capacitance of 7.4 μF (50.7 μF/cm2, normalized to the area of the electrodes), a five-times increase from previous results obtained by the group.
Assessing the Impact of Industrial Poultry Waste on the Soil Cover
Authors: Tuchkova L E , Verkhovets I A , Tikhoykina I M , Chuvasheva E S
Published: April 2021

The paper describes the impact of industrial poultry waste on the soil pollution degree. Analysis of the results of studying the sanitary-biological indicators of the soil cover for 2017 and 2019 has shown an increase in the pollution with coliform bacteria. High focal pollution of soils with nitrate nitrogen has been detected, which has led to the formation of patches in the soil cover. In 2017, a significant excess of the MPC by all chemical and toxicological indicators of the heavy metal mobility was detected, and 2019 studies showed an excess of the MPC by only copper and zinc. The studied plot belongs to agricultural land of the high-risk category; it is subject to biological pollution and contaminated with heavy metals.
Veterinary-Sanitary Examination of Migratory Bird Carcasses When Stored in a Glacier Under Permafrost Conditions
Authors: Sidorov M N , Tomashevskaya E P , Maksimova A N
Published: April 2021

Due to the annual increase in harvesting wild ducks in the Republic of Sakha (Yakutia) regions, a detailed studying the wild bird meat is required to assess its quality and preserve the population health. Wild ducks harvested in the Ust-Aldan, Tattinsk, and Megino-Kangalassk regions of the Republic of Sakha (Yakutia) have been studied. The meat of the migratory bird carcasses has been studied twice by 4 samples: the first study – after 2-month freezing in a glacier, the second study – after 4-month freezing in a glacier. The materials studied were meat samples taken from gutted wild ducks of four species, harvested in the central zone in autumn, and marked as follows: Sample No. 1 – mallard carcass meat; Sample No. 2 – wigeon carcass meat; Sample no. 3 – shoveler carcass meat; Sample No. 4 - scoter carcass meat. For the study, gutted carcasses were frozen in a glacier at a relative humidity of 70-85 %; the glacier temperature was within -8 to -15 °C. The veterinary-sanitary examination was performed on gutted migratory bird carcasses when stored in glaciers under permafrost conditions with determining organoleptic, physicochemical, and microbiological meat indicators and studying subcutaneous fat of the meat of gutted migratory bird carcasses with determining toxic elements at the State Budgetary Institution of the Republic of Sakha (Yakutia) Yakutskaya RVIL (Yakut Republican Veterinary Testing Laboratory) and the Department of Veterinary-Sanitary Examination and Hygiene of the Veterinary Medicine Faculty of the Federal State Budgetary Educational Institution of Higher Education Arctic State Agrotechnological University. Based on the organoleptic, physicochemical, and microbiological results, as well as the content of toxic elements in the meat, it has been concluded that the use of healthy duck meat as a food product is advisable.
Information Support for Predictive Modeling of Agroecosystems
Authors: Chelovechkova A V , Polyakova E N , Zmyzgova T R
Published: April 2021

In recent years, the anthropogenic load on the environment has been growing. This leads to the aggravation of environmental problems. To solve such problems, different concepts are needed that will allow nature and man to coexist stably. To make the right decision in any area that determines human activity, it is necessary to predict actions and their consequences. At the present stage of the development of science, simple intuition is not enough. High-quality recommendations are also often lost their relevance. In recent years, with the use of information technologies, a fundamentally new approach to working with agroecosystems has been growing - process modeling. At the same time, the created models can provide the solution of the assigned tasks with very high accuracy. Such models take into account soil and climatic conditions, weather factors that determine the area of consideration. The introduction of high-performance computers made it possible to create a reliable base for the development of such models.
Research into Filtration Washing Kinetics of Sludge Pulp Bottom Settlings
Authors: Salamatov V I , Fetisova S A
Published: April 2021

The research presents the results of the study of filtration washing kinetics of sludge pulps containing various substances. The kinetics of the process of washing the valuable solution from mother waters when applying the scrubber solution (water) with the fully engaged surface of the bottom settlings is analysed. Key stages of the washing process are interpreted in the research, as well as the impact of the basic parameters of washing (expendable modulus, washing circulation cycle time, bottom settlings thickness, scrubber solution temperature in the mother waters, etc.) on the performance of washing the valuable solute from interstices of bottom settlings is identified. It is shown that the filtration washing process is influenced by the conditions of appearing the bottom settlings on the filtering element. The research gives an insight into the process of washing the bottom settlings from the flaking and preliminarily concentrated pulps. Analytical expressions for the effectiveness of filtration washing of different stages, which are based on bottom settling specific loads dependent on the dissolved substance and expendable modulus, are provided.