bluuebunny/crossref_metadata_2025 huggingface dataset:
Argon tagging of doubly transition metal doped aluminum clusters: The importance of electronic shielding
Authors: Vanbuel Jan , Ferrari Piero , Jia Meiye , Fielicke André , Janssens Ewald
Published: February 2021

The interaction of argon with doubly transition metal doped aluminum clusters, AlnTM2+ (n = 1–18, TM = V, Nb, Co, Rh), is studied experimentally in the gas phase via mass spectrometry. Density functional theory calculations on selected sizes are used to understand the argon affinity of the clusters, which differ depending on the transition metal dopant. The analysis is focused on two pairs of consecutive sizes: Al6,7V2+ and Al4,5Rh2+, the largest of each pair showing a low affinity toward Ar. Another remarkable observation is a pronounced drop in reactivity at n = 14, independent of the dopant element. Analysis of the cluster orbitals shows that this feature is not a consequence of cage formation but is electronic in nature. The mass spectra demonstrate a high similarity between the size-dependent reactivity of the clusters with Ar and H2. Orbital interactions provide an intuitive link between the two and further establish the importance of precursor states in the reactions of the clusters with hydrogen.
Effects of size ratio and inter-cylinder spacing on wake transition in flow past finite inline circular cylinders mounted on plane surface
Authors: Kumar Prashant , Tiwari Shaligram
Published: February 2021

Three-dimensional numerical computations have been carried out in flow past two inline finite-height circular cylinders using Open Source Field Operation and Manipulation. Investigations have been carried out for the varying Reynolds number (Re) ranging from 150 to 300. The diameter of the upstream cylinder is varied in such a way that the size ratio (SR, ratio of the diameter of the upstream cylinder to that of the downstream cylinder) takes values of 0.25, 0.5, and 1.0. For each size of the upstream cylinder, the downstream cylinder is placed at different locations in the streamwise direction. Effects of Re, SR, and inter-cylinder spacing (S) on three-dimensional unsteady wake characteristics behind upstream and downstream cylinders have been examined using iso-Q surfaces. Unsteady wake oscillations in both the wakes are analyzed qualitatively and quantitatively in terms of Hilbert spectra and the degree of stationarity using the transverse velocity component in the wake. Different flow regimes for upstream and downstream wakes have been identified and discussed with the change in Re, SR, and S. Transitions in the wake flow are illustrated using vorticity contours, frequency spectra, and bifurcation diagram. The level of wake synchronization in the upstream wake, downstream wake, and between both the wakes has been identified with the help of the cross correlation function.
Optoelectronic properties of diketopyrrolopyrrole homopolymers compared to donor–acceptor copolymers
Authors: Salzner Ulrike
Published: February 2021

Diketopyrrolopyrrole (DPP) is a component of a large number of materials used for optoelectronic applications. As it is exclusively used in combination with aromatic donors, the properties of its homopolymers are unknown. Because donor–acceptor character has been shown for other systems to reduce bandwidths, DPP homopolymers should have even larger conduction bands and better n-type conductivity than the thiophene-flanked systems, which have exceptional n-type conductivity and ambipolar character. Therefore, a theoretical study was carried out to elucidate the properties of the unknown DPP homopolymer. Calculations were done with density functional theory and with the complete active space self-consistent field method plus n-electron valence state perturbation theory for the dynamic correlation. Poly-DPP is predicted to have radical character and an extremely wide low-lying conduction band. If it were possible to produce this material, it should have unprecedented n-type conductivity and might be a synthetic metal. A comparison with various unknown donor–acceptor systems containing vinyl groups and thienyl rings with a higher concentration of DPP than the known copolymers reveals how donor–acceptor substitution reduces bandwidths and decreases electron affinities.
Sensitivity of the messina (
Authors: Ballard Ross A. , Peck David M.
Published: February 2021

Messina (Melilotus siculus) is a new annual pasture legume with better combined waterlogging and salt tolerance than other annual legumes. Messina cv. Neptune and a new salt-tolerant rhizobial symbiont (Sinorhizobium medicae SRDI-554) were made available to Australian growers in 2017. Messina is related to the annual medics (Medicago spp.) that are nodulated by the same genus of rhizobia and regarded as sensitive to soil acidity. Because some saltland soils are acidic, it is important to understand the sensitivity of messina to soil acidity in order to avoid failures during early adoption. Acidity tolerance of the messina–Sinorhizobium symbiosis was investigated in a hydroponic experiment (inoculation with SRDI-554, or the salt-intolerant strain WSM-1115 recommended for medics), and in three acidic soils (pHCa 4.3–5.5) (inoculation with SRDI-554 ± lime pelleting of seed), in the greenhouse. In the hydroponic experiment, the percentage of messina plants (with SRDI-554) that formed nodules declined at pH levels between 5.7 (43%) and 5.5 (4%). Strain SRDI-554 was slightly more sensitive to acidity than strain WSM-1115. In the acidic soils, more plants formed nodules than in the hydroponic experiment at similar pH levels; however, without lime pelleting, nodule number was inadequate at soil pHCa <5.5. Addition of lime to seed was beneficial to messina nodulation. Nodule number per plant increased from 4.0 to 9.6 with the addition of lime. The messina–Sinorhizobium symbiosis was confirmed as sensitive to low pH. At pHCa 5.5, which is the level recommended as the lower limit for growing messina, nodule number was constrained in both hydroponics and soil. The risk of suboptimal nodulation would be reduced if the recommended lower soil pH limit for growing messina is increased to pHCa 5.8, in line with most annual medics. Efforts to improve the acidity tolerance of the messina symbiosis would be best focused on the rhizobial symbiont, rather than the plant.
Oceanian Sovereignty: rethinking conservation in a sea of islands
Authors: Bambridge Tamatoa , D’Arcy Paul , Mawyer Alexander
Published: February 2021

In an age of dramatic environmental and ecological challenges, the dynamics of sovereignty associated with the conservation of natural resources in Oceania are in flux. This article draws on the transformative work of Tongan anthropologist and political philosopher Epeli Hau‘ofa to articulate characteristics of an Oceanian Sovereignty that illuminate ongoing conceptual shifts around conservation in this region. In the wake of intensifying and accelerating environmental challenges from global warming and other hazard drivers, understanding Indigenous peoples and local communities’ deeply rooted and emerging perceptions and conceptions of rights over, responsibilities towards, and respect for, nature is a critical context for necessary transformations within conservation science, policy and practice. The articulation of sovereignty that we identify in Hau‘ofa sheds light on how Oceania’s peoples are asserting rights to make choices about the environmental futures of ocean and island spaces. Oceanian Sovereignty emphasises past, present and future obligations enacted though sustainable use in partnership with an ancestral ocean deeply embedded in cultural identity as a basis of governance rather than in legal and political arguments grounded in the constitutions of states. The resultant nature politics are exemplified in what we term tidal thinking. Tidal thinking refers to Indigenous and local peoples’ fluid responses to current challenges around conservation and sustainable management of island and ocean futures and the linked wellbeing of human and non-human entities within them. We conclude with a number of conservation practice, governance, and policy implications that tidal thinking around Oceanian Sovereignty entails.
Continuous topological transition from metal to dielectric
Authors: Yang Fan , Ma Shaojie , Ding Kun , Zhang Shuang , Pendry J. B.
Published: February 2021

Significance

We extend the concept of metals and dielectrics to the “generalized metal/dielectric” by treating a pure metal or dielectric as the limiting case of a metal–dielectric layered metamaterial. Specifically, the metamaterial with metal filling ratio larger than one-half shares the same topological invariant as a pure metal and thus exhibits some metallic behaviors. In contrast, the dielectric-rich metamaterial and a pure dielectric are topologically equivalent and display dielectric properties. The topological edge state exists between the generalized metal and dielectric, giving the surface plasmon polariton (SPP) an additional physical meaning: the limiting case of a topological edge state.
Ultrasound activates mechanosensitive TRAAK K
+
channels through the lipid membrane
Authors: Sorum Ben , Rietmeijer Robert A. , Gopakumar Karthika , Adesnik Hillel , Brohawn Stephen G.
Published: February 2021

Significance

Ultrasound stimulation modulates the electrical activity of excitable cells, including in neurons of the brain and central nervous system. Compared to other neuromodulatory techniques, ultrasound offers several advantages; for example, it can be noninvasively transmitted through the skull and focused to deep brain regions. However, the molecular basis underlying the effects of ultrasound on neural activity is not known. Here, we show that ultrasound activates the mechanosensitive ion channel TRAAK through the membrane in a manner analogous to canonical mechanical activation, likely by increasing membrane tension to promote channel opening. These results suggest mechanosensitive channels underlie physiological responses to ultrasound and could serve as tools for acoustic neuromodulation of genetically targeted cells.
Neural and behavioral control in
Caenorhabditis elegans
by a yellow-light–activatable caged compound
Authors: Takahashi Hironori , Kamiya Mako , Kawatani Minoru , Umezawa Keitaro , Ukita Yoshiaki , Niwa Shinsuke , Oda Toshiyuki , Urano Yasuteru
Published: February 2021

Significance

Caged compounds that release bioactive molecules upon light irradiation are widely used by biologists. However, their application to neuroscientific research in the nematode
Caenorhabditis elegans
has been hampered by several drawbacks: Most of the caged compounds require short-wavelength light that induces an innate photophobic response, while red-shifted compounds show reduced temporal resolution of photocontrol or generate toxic levels of reactive oxygen species under normoxic conditions. We developed caged compounds based on a π-extended BODIPY derivative, Keio Fluors-1 (KFL-1), that releases an activator on yellow light illumination. This enables the behavior of
C. elegans
to be controlled by selectively activating specific neurons without inducing a photophobic response and without crosstalk between uncaging and fluorescence monitoring of neural activity.
Pluripotent stem cell-derived epithelium misidentified as brain microvascular endothelium requires ETS factors to acquire vascular fate
Authors: Lu Tyler M. , Houghton Sean , Magdeldin Tarig , Durán José Gabriel Barcia , Minotti Andrew P. , Snead Amanda , Sproul Andrew , Nguyen Duc-Huy T. , Xiang Jenny , Fine Howard A. , Rosenwaks Zev , Studer Lorenz , Rafii Shahin , Agalliu Dritan , Redmond David , Lis Raphaël
Published: February 2021

Significance

Human PSC-derived iBMECs have been generated to study disease mechanisms and drug development for neurological disorders. However, their full transcriptomic characterization is unclear, which could result in inaccurate physiological studies and development of treatments with ineffective clinical outcomes. Utilizing a comprehensive transcriptomic metaanalysis validated by physiological studies, we find that many current protocols used to generate iBMECs produce a homogenous epithelial cell population. Overexpression of ETS transcription factors reprogram these cells into phenotypic endothelial cells (rECs) which recapitulate certain vascular functions, albeit lacking expression of some organotypic transporter genes and high electrical resistance in vitro. Nevertheless, they represent a crucial step toward the generation of an in vitro

model suitable for physiological and pharmaceutical studies of the blood–brain barrier.
Interface mobility between monomers in dimeric bovine ATP synthase participates in the ultrastructure of inner mitochondrial membranes
Authors: Spikes Tobias E. , Montgomery Martin G. , Walker John E.
Published: February 2021

Significance

Mitochondria are the powerhouses of eukaryotic cells. Pairs of molecular machines with a rotary action, called ATP synthase, are embedded in their inner membranes and produce adenosine triphosphate, ATP, the fuel of life. These dimers form long rows on cristae tips, helping to endow them with their characteristic and mobile tubular shape. Our structural analyses of bovine dimers show that some structural changes depend on catalysis and others are independent. The monomers pivot and translate at wedge-shaped structures in their membrane domains. The structures suggest how dimeric ATP synthases might interact and fashion themselves to the range of oligomeric arrangements observed in mitochondria, whilst allowing the ATP synthase to produce ATP under a wide range of physiological conditions.
The Mtatsminda Pantheon: a memory site and symbol of identity
Authors: Chikovani Nino
Published: February 2021

The paper deals with the Pantheon of Writers and Public Figures at the Mtatsminda rise in Tbilisi. The latter represents a memory site of widely recognized symbolic importance for a long time. Initiated at the end of the nineteenth century and opened in the 1920s, the Pantheon was conceived of as a symbol of collective identity of Georgia. The status of the Pantheon of Writers and Public Figures has largely defined its history in the following decades, both in the Soviet period and afterwards. The paper aims to trace the transformation of the idea of the Mtatsminda Pantheon as a symbol of Georgian identity over a century, to explain how and why the meanings assigned to the Pantheon evolved over time, thus contributing towards the formation of a collective memory – one of the essential elements of national identity. The work draws upon factual evidence and theoretical judgements presented in various pieces of research, as well as the analysis of papers reflecting different subject-specific discussions, information spread by media outlets, including popular newspapers, magazines, and official documents.
Emergence of the circle in a statistical model of random cubic graphs
Authors: Kelly Christy , Trugenberger Carlo , Biancalana Fabio
Published: February 2021

We consider a formal discretisation of Euclidean quantum gravity defined by a statistical model of random 3-regular graphs and making using of the Ollivier curvature, a coarse analogue of the Ricci curvature. Numerical analysis shows that the Hausdorff and spectral dimensions of the model approach 1 in the joint classical-thermodynamic limit and we argue that the scaling limit of the model is the circle of radius r,

S

r

1

. Given mild kinematic constraints, these claims can be proven with full mathematical rigour: speaking precisely, it may be shown that for 3-regular graphs of girth at least 4, any sequence of action minimising configurations converges in the sense of Gromov–Hausdorff to

S

r

1

. We also present strong evidence for the existence of a second-order phase transition through an analysis of finite size effects. This—essentially solvable—toy model of emergent one-dimensional geometry is meant as a controllable paradigm for the nonperturbative definition of random flat surfaces.
Rotating black hole with an anisotropic matter field as a particle accelerator
Authors: Ahmed Rizwan C L , Naveena Kumara A , Hegde Kartheek , Ali Md Sabir , Ajith K M
Published: February 2021

Recently, a generalised solution for Einstein equations for a rotating black hole, surrounded by matter field was proposed, which is the Kerr–Newman spacetime with an anisotropic matter [Phys. Rev. D. 101 064067]. Due to the negative radial pressure of the anisotropic matter, the solution possesses an additional hair along with the conventional mass, charge and spin. In this article we show that, this new class of black holes can act as a cosmic particle accelerator during the collision of two generic particles in its gravitational field in the ergo-region. The centre of mass energy of the particles shoots to an arbitrary high value in the vicinity of the event horizon for the extremal black hole. The physical conditions for the collision to take place are obtained by studying the horizon structure and circular particle motion. The results obtained are interesting from an astrophysical perspective.
A Ka-band pattern-reconfigurable microstrip antenna enabled by PIN diodes with accurate extraction of equivalent circuit parameters
Authors: Jiang Wan , Huang Yong Mao , Zhang Biao , Ling Jianhang , Waldschmidt Christian
Published: February 2021

A Ka-band microstrip antenna based on PIN diodes with accurate extraction of equivalent circuit parameters for pattern reconfigurability is proposed in this work. With the increase in operation frequency, the parasitic effect introduced by PIN diodes has tremendous influence on the performance of reconfigurable antennas; hence, the conventional equivalent circuit parameters of the PIN diodes are not applicable for higher-frequency applications, such as millimeter-wave circuits and antennas. Therefore, accurate equivalent circuit models of the conventional PIN diodes are essential in the millimeter-wave reconfigurable antenna design. Based on the combination of simulation and experimental results, accurate equivalent circuit model parameters for the millimeter-wave range of the PIN diode are extracted, with a pattern-reconfigurable antenna being developed afterwards. The proposed antenna consists of two PIN diodes, two interdigital capacitors, an L-shaped slot, and their bias networks. Particularly, the interdigital capacitors are utilized to isolate direct current (DC) from radio frequency circuits, which is able to improve the economic efficiency of the antenna notably as compared with conventional chip capacitors in the Ka-band. By combining a suitable arrangement of the diodes’ location and the DC bias networks, the main beam direction of the proposed antenna can be switched between −60° and 60°. To demonstrate the proposed idea, a prototype antenna is fabricated and measured. The measured results agree with the simulation quite well, with a good performance around 30 GHz and a gain greater than 5 dBi for both modes being achieved.
Effect of hydrogen and oxygen plasma on the photoelectronic current and photo-response time of SnS2 flakes
Authors: Xia Minggang , Hu Ruixue , Wang Min , Liu Shiru , He Shaodan , Cheng Zhaofang
Published: February 2021

The photoelectronic properties of SnS2 flakes have been widely studied due to the abundance and environmentally friendly qualities of this material. However, the defects and residual molecules adsorbed on the SnS2 surface can have a negative influence on the photoelectronic current and photo-response time. In this paper we examine the effects of these two factors on the photoelectronic currents of SnS2 flakes. Defects on a single crystal SnS2 surface are fabricated using hydrogen and oxygen plasma and are characterized by atomic force microscopy, confocal micro-Raman spectroscopy and photoluminescence spectroscopy. Doping by oxygen plasma can be demonstrated by x-ray photoelectron spectroscopy. Both the photoelectronic current and the switching speed (on and off times) are reduced after hydrogen plasma treatment. However, oxygen plasma has two effects on SnS2 thin film transistors. First, oxygen plasma can remove the residual molecules within a short irradiation time. In this case, the photoelectronic current of SnS2 treated with oxygen plasma is enhanced several times. Second, with a longer treatment time oxygen plasma induces many defects and doping on the SnS2 flake surface, as reflected in the reduced photoelectronic current and switching speed. Results of this work have significant practical applications for photoelectronic detection with SnS2 flakes.
Old enemy, new threat: you can’t solve today’s problems with yesterday’s solution
Authors: Rehani Madan M
Published: February 2021

The radiation protection principles of justification, optimization, and dose limitation as enumerated by the International Commission on Radiological Protection have been guiding light for the profession for over three decades. The dose limitation does not apply to medical exposure but keeping patients’ doses low is achieved through optimization, particularly by developing and using diagnostic reference levels (DRLs). There are new findings that demonstrate that despite using the best possible approaches to justification and optimization including as well use of DRLs, a very large number of patients are receiving doses in excess of 100 mSv of effective dose or organ doses exceeding 100 mGy. A non-ignorable fraction of patients is receiving such high doses in a single day. The magnitude of such patients creates the need for a relook into the principles with the intent to understand what can be done to attend to today’s problems. A look at other areas such as approaches, and principles used in the pharmaceutical industry and in traffic management throws some light into what can be learnt from these examples. It appears that the system needs to be enriched to deal with the protection of the individual patient. The currently available approaches and even the principles are largely based on the protection of the population or group of patients. The third level of justification for individual needs further refinement to take into account series of imaging many patients are needing, and cumulative radiation doses involved, many of which happen in a short duration of 1 to 5 years. There is every likelihood of patient radiation doses continuing to increase further that underscores the need for timely attention. This paper provides several suggestions to deal with the situation.
GUI for Bayesian sample size planning in type A uncertainty evaluation
Authors: Martin Jörg , Elster Clemens
Published: February 2021

We present a graphical user interface (GUI) for planning the sample size needed to reach a specified target uncertainty in a Bayesian type A uncertainty evaluation of normal or Poisson distributed data. To this end we build on a criterion previously introduced by Martin and Elster (2020 Stat. Methods Appl. 1–21) and called the variation of the posterior variance criterion. This criterion includes, and extends, standard Bayesian sample size planning procedures. Guidance is provided for the elicitation of the required prior knowledge in a way that makes the approach easily accessible for metrologists. The GUI also includes a menu that performs the Bayesian inference after the experiment has been carried out.
Measurement of boundary layer transition on oscillating airfoil using cntTSP in low-speed wind tunnel
Authors: Ikami Tsubasa , Fujita Koji , Nagai Hiroki , Yorita Daisuke
Published: February 2021

cntTSP is a flow visualization technique that combines temperature-sensitive paint (TSP) and carbon nanotube (CNT). TSP is a sprayable temperature sensor, and CNT is used as a thin inner electric heater for the TSP. The cntTSP technique allows the visualization of the movement of the boundary layer transition on a moving airfoil. In this study, cntTSP was applied to a pitch-oscillating airfoil in a low-speed wind tunnel. Three methods were compared as methods for detecting the boundary layer transition position. The transition position was successfully evaluated using a heat transfer coefficient that was calculated by the surface temperature. Moreover, at a high-reduced frequency, the detected transition positions were different between the pitching-up and pitching-down procedure. Moreover, we observed a hysteresis loop of the transition position.
A reversible and stable doping technique to invert the carrier polarity of MoTe2
Authors: Aftab Sikandar , Samiya Ms , Raza Ali , Iqbal Muhammad Waqas , Haque Hafiz Mansoor Ul , Ramachandraiah Karna , Yousuf Saqlain , Jun Seong Chan , Rehman Atteq Ur , Iqbal Muhammad Zahir
Published: February 2021

Two-dimensional (2D) materials can be implemented in several functional devices for future optoelectronics and electronics applications. Remarkably, recent research on p–n diodes by stacking 2D materials in heterostructures or homostructures (out of plane) has been carried out extensively with novel designs that are impossible with conventional bulk semiconductor materials. However, the insight of a lateral p–n diode through a single nanoflake based on 2D material needs attention to facilitate the miniaturization of device architectures with efficient performance. Here, we have established a physical carrier-type inversion technique to invert the polarity of MoTe2-based field-effect transistors (FETs) with deep ultraviolet (DUV) doping in (oxygen) O2 and (nitrogen) N2 gas environments. A p-type MoTe2 nanoflake transformed its polarity to n-type when irradiated under DUV illumination in an N2 gaseous atmosphere, and it returned to its original state once irradiated in an O2 gaseous environment. Further, Kelvin probe force microscopy (KPFM) measurements were employed to support our findings, where the value of the work function changed from ∼4.8 and ∼4.5 eV when p-type MoTe2 inverted to the n-type, respectively. Also, using this approach, an in-plane homogeneous p–n junction was formed and achieved a diode rectifying ratio (If/Ir) up to ∼3.8 × 104. This effective approach for carrier-type inversion may play an important role in the advancement of functional devices.
A design-based activity for teaching and learning torque
Authors: Ladachart Luecha , Khamlarsai Sirinapa , Phothong Wilawan
Published: February 2021

This paper proposes a design-based activity for students to learn about the concept of torque using everyday materials and equipment.
Teaching the moment of inertia by measuring the angular speed with a smartphone’s sensors
Authors: Puttharugsa Chokchai , Chatchawaltheerat Theerawat , Teeratchanan Pattanasak
Published: February 2021

This paper demonstrates the use of the sensors of a smartphone in recording experimental data for studying the moment of inertia of a compound pendulum. The smartphone was attached to the beam to record at various points the angular position and angular speed of a compound pendulum. We altered the position of the smartphone along the beam resulting in the change of the system’s moment of inertia. The experimental result agreed with the theoretical calculation. This experiment will stimulate students to conduct such an experiment themselves and helps students understand the relationship between angular speed and its moment of inertia.
Development of a cryogenic indentation tool with in situ optical observation, application to the mechanical characterization of II–VI semiconductors
Authors: Broult T , Kerlain A , Destefanis V , Guinedor P , Bourhis E Le , Patriarche G
Published: February 2021

Infrared detectors based on II–VI semiconductors are cooled from room temperature (RT) to cryogenic temperatures between 80 K and 150 K in order to operate with strong requirements regarding sensor performances for infrared detection. At these cryogenic temperatures, the mechanical properties of II–VI alloys have to be known in detail to improve handling, use and lifetime of infrared sensors. We have developed a cryogenic indentation tool and in situ measured the mechanical properties of CdZnTe alloys at both RT and 90 K. CdZnTe hardness increases by a factor of about 3 when cooling from RT to 90 K, from 0.6 GPa to 1.6 GPa. The plastic flow driving mechanism shows at least two different domains with activation energies around 0.01 eV at low temperatures and around 0.05 eV at RT, showing an increase by a factor of about 5. These two domains might be ‘connected’ by an intermediate domain in the 235 K–290 K temperature range. Radial cracks can be in situ detected. Toughness of CdZnTe alloys also increases dramatically by a factor of about 2 with cooling down to cryogenic temperature from 0.13 MPa.m1/2 at RT to 0.25 MPa.m1/2 at 90 K.
Proton irradiation effects on buffer-free gallium nitride on silicon carbide high electron mobility transistor-based radio frequency power amplifier
Authors: Raut Samriddhi , Sehra Khushwant , Mishra Meena , Rawal D S , Gupta Mridula , Saxena Manoj
Published: February 2021

In this work, a comprehensive technology computer aided design-based investigation of a buffer-free high electron mobility transistor under proton radiation is presented. With a 37.55% thinner architecture (without thick and highly doped Fe buffer) grown on silicon carbide substrate, this device design improves the two-dimensional electron gas (2DEG) confinement and helps to eliminate the various dispersion effects and buffer leakage. To gain better insight into the buffer-free device architecture, direct current (DC), thermal, and radio frequency (RF) studies are carried out. To establish the various prospects of this device in high-power and space applications, the performance of the device under 1.8 MeV proton radiation environment is systematically studied. A comparison demonstrates that the buffer-free structure under proton radiation with fluence

1
×

10

14

c

m

−
2

shows a current

I

D
,
M
a
x

degradation of 18.68% compared with 72.7% in the case of conventional architecture. The excellent capability of the buffer-free device to confine 2DEG more precisely even under radiation environments can be concluded from the various DC and RF parameters studied. An extensive study of the effects of proton fluences and biases on the RF power amplifier figures of merit was also conducted by carrying out harmonic balance simulations for different radiation setups, which demonstrates excellent performance of the buffer-free structure.
Exploiting ferroelectric and ferroelastic effects in piezoelectric energy harvesting: theoretical studies and parameter optimization
Authors: Behlen Lennart , Warkentin Andreas , Ricoeur Andreas
Published: February 2021

While piezoelectric energy harvesting typically focuses on converting mechanical into electrical energy on the basis of the linear reversible piezoelectric effect, the potential of exploiting the non-linear ferroelectric effect is investigated theoretically in this paper. Due to its dissipative nature, domain switching, on the one hand, is basically avoided in order to prevent mechanical energy from being converted into heat. However, the electrical output, on the other hand, is augmented due to the increased change of electric displacement. In view of these conflicting issues, one main objective in ferroelectric energy harvesting thus is to identify mechanical and electrical process parameters providing appropriate figures of merit. Being an efficient approach to numerically simulate multiphysical polycrystalline material behavior, the so-called condensed method is taken as a basis for the investigation and finally optimization of controllable parameters of ferroelectric energy harvesting cycles. A first idea of a technical implementation taken from literature is considered as cycle of reference, constituting the starting point of the present study, being focused on material aspects rather than on harvesting devices. Different quality assessing parameters are introduced, taking into account general aspects of harvesting efficiency as well as the ratio of irreversible switching-related to reversible piezoelectric contributions. Residual stresses are likewise predicted to give an idea of reliability and the risk of fracture. Two types of cycles and associated optimal process parameters are finally presented.
Calculation of electronic and optical properties of 1550 nm VCSEL based on Group IV elements
Authors: Li Hongqiang , Zhang Sai , Zhang Yikai , Ding Mingjun , Lu Xinyan , Daniel Prades Joan
Published: February 2021

Si/SiGe quantum well (QW) structures show considerable potential in revolutionising Si photonics. This study proposes a novel 1550 nm vertical cavity surface-emitting laser (VCSEL) that is based on Group IV elements and composed of Si/SiO2 distributed Bragg reflectors and Si/Si0.13Ge0.87 QWs. Material composition and QW width in the active region are optimised. The proposed Group IV-based VCSEL can exhibit epitaxial growth on a vertical binary blazed grating coupler and increase coupling efficiency relative to the traditional Group III–V-based VCSEL with an Si waveguide. The proposed VCSEL on Si based on the Group IV element scheme is a cheap, high-yielding and temperature-insensitive on-chip light source that can be used in large-scale, high-density monolithic integration.
New structures for closed-form wave solutions for the dynamical equations model related to the ion sound and Langmuir waves
Authors: Alam Md Nur , Osman M S
Published: February 2021

This treatise analyzes the coupled nonlinear system of the model for the ion sound and Langmuir waves. The modified

(
G
′

/

G
)

-expansion procedure is utilized to raise new closed-form wave solutions. Those solutions are investigated through hyperbolic, trigonometric and rational function. The graphical design makes the dynamics of the equations noticeable. It provides the mathematical foundation in diverse sectors of underwater acoustics, electromagnetic wave propagation, design of specific optoelectronic devices and physics quantum mechanics. Herein, we concluded that the studied approach is advanced, meaningful and significant in implementing many solutions of several nonlinear partial differential equations occurring in applied sciences.
Coexistence and fluctuations phenomena with Davidson-like potentials in quadrupole–octupole deformed nuclei
Authors: Hammad M M , Mansour W H , El-Maghraby E M , Motaweh H A , Aly Ayman A
Published: February 2021

The energy spectra of three types of two-dimensional potentials (we will call them ‘Davidson-like potentials’ (DLPs)), characterized by four minima separated by barriers, are investigated. The predictions for spectra and wave functions are obtained by using the nine-point finite-difference method. For these potentials, with the existence of a single configuration, a transition of spectra, as a function of barrier height, is covered from tunneling splitting modes to fluctuations phenomena, with equal peaks wave functions, crossing to the spectra of purely anharmonic oscillator potentials (AOPs). A different type of phase transition occurs when two (or more) configurations coexist. With the change of the parameters, a transition of spectra is covered from coexistence phenomena of two distinct quantum tunneling modes to fluctuations phenomena, with unequal peaks wave functions, crossing to the spectra of purely AOPs. Using DLPs, a particular application of the coherent quadrupole–octupole model to describe energy bands with alternating parity of the nuclei 100Mo, 146,148Nd, 148,150Sm, 220Ra, 220,222Rn, and 220,222Th is presented. The global parametrization of the model for the selected nuclei is achieved.
Realization of simultaneous balanced multi-outputs for multi-protocols QKD decoding based on silica-based planar lightwave circuit*
Authors: You Jin , Wang Yue , An Jun-Ming
Published: February 2021

Silica-based planar lightwave circuit (PLC) devices can reduce transmission loss and cost in a quantum key distribution (QKD) system, and have potential applications in integration and production. A PLC-based quantum decoding integrated chip for multi-protocols is designed and fabricated, which is composed of variable optical splitters (VOSs), asymmetric Mach–Zehnder interferometers (AMZIs), and variable directional couplers (VDCs). Balanced pulse-pairs of four outputs are obtained simultaneously with measured delay times of 405 ps and 402 ps, respectively. The chip has advantages in achieving high interference visibility and low quantum bit error rate (QBER).
Axiomatic tests for the Boltzmann distribution
Authors: Cerreia-Vioglio Simone , Maccheroni Fabio , Marinacci Massimo , Rustichini Aldo
Published: February 2021

The Boltzmann distribution family describes a single parameter (temperature) class of probability distributions over a state space; at any given temperature, the ratio of probabilities of two states depends exponentially on their difference in energy. Beyond physics, this distribution family is very popular in many important disciplines, under different names with different interpretations. Such widespread use in diverse fields suggests a common conceptual structure. We identify such a structure on the basis of few natural axioms that can be statistically tested. Our axiomatic characterization thus provides alternative empirical tests of the Boltzmannian modeling theories.
To the issue regarding the content of the future specialists training in the field of modern optics and photonics
Authors: Chulkova G M , Petrova E B
Published: February 2021

The article is a continuation of the authors’ works on the problem of achievements presentation of modern physics to future teachers and physics students. It deals with the issues related to the necessity explanation of the transition from electronic circuits to optical ones and technologies of optical circuits development. Moreover, the article shows the ways to motivate students to study physics and conduct experimental research. One such a way is to involve students to real scientific research. As a result, they can feel the importance of their contribution to the work of the group of researchers and appreciate the benefits of collective forms of work. The authors emphasize that nowadays professors and students have new opportunities associated with the access to new information and computer technologies, as well as greater the availability of rather complex physical equipment. The accessibility is connected with the organization of centers for common usage equipment, remote access to various databases of connected with results scientific research. All of the mentioned issues create favorable conditions for the further attempt to familiarize students with the problems of modern science.
Application of the clustering algorithm in an automated training system
Authors: Popov A A , Ovsyankin A K , Emomaliev M R , Satsuk M M
Published: February 2021

The development of information technologies provides a new, unique opportunity to conduct classes with the introduction of automated training systems for disciplines, which allows the student to choose the time and place for training, makes it possible to use new information technologies in training, and to a certain extent reduces training costs. The problem of improving the quality of the educational process in an educational institution is being solved because of the use of automated systems. This task is the main one in the activities of each educational institution. The development of a high-quality system will provide an increase in the student’s knowledge in the chosen field, and help to form an up-to-date curriculum for training. The purpose of this work is to create an automated training system using the clustering and content ranking algorithm, which can improve the quality of the student’s educational process.
Electronic poster as a way to implement educational activities
Authors: Pinevich E V , Kalinina I M , Abyshkina V V , Tugova Y A
Published: February 2021

The article is devoted to the description of the electronic educational poster created on one of the popular open platforms on the Internet and used as a way to implement educational activities in a distance or mixed (distance–face-to-face) format of teaching Russian to foreign students-masters of technical specialties. Work with the electronic educational poster is presented as an effective method of teaching, since the Russian language for foreign students at technical universities is a way of gaining knowledge on the future specialty, communication in Russian and getting to know Russian culture in general. Like any innovative technique, an electronic educational poster is not the main one that gives fundamental knowledge in the studied discipline, but an auxiliary tool that increases the motivation of students and increases their knowledge in the field of Russian vocabulary and grammar. The authors of the article describe the algorithm for creating an electronic educational poster, and also share practical recommendations for working with it. The article also presents the experiment conducted with master students of the faculty of pre-university training and 1st year students who studied Russian, the scientific style of speech and cultural linguistics using an electronic educational poster; examples of materials and tasks posted on the poster are given. At the end of the article, the results of the experiment are given and the prospects for the use of electronic posters in educational activities are outlined.
Innovative technology for assessing the quality of information security systems in the design of a modern educational environment
Authors: Bulgakov O M , Kadnova A M , Grebennikova N I , Meshcheryakov V A , Belyaev R V
Published: February 2021

The article describes an experimentally-based innovative technology for assessing the performance characteristic «Usability» of the information security system in the automated system of the digital educational environment. This characteristic consists of indicators: the structure of a typical operation, time index and probability rate. On the basis of the obtained results of the assessment of the listed indicators it is possible to choose an information security system for the designed digital educational environment.
Teaching EFL through culture and technologies
Authors: Arkhipova Maria V , Zhulina Elena V , Shutova Natalia V , Orlova Olga A , Medvedeva Elena Y
Published: February 2021

The article refers to the experience of introducing the Country Studies Course into University Baccalaureate curriculum for students majoring in studying English as a foreign language in Minin Nizhny Novgorod State Pedagogical University, Russia. The purpose of the present research is to describe the program of the academic discipline, its objectives, content modules and teaching methods. The course, viewed as a contribution to University curriculum development, proves its effectiveness, helping students understand the countries, people and traditional values, get rid of existing prejudices, and it can be one of the ways contributing to mutual understanding, tolerance, appreciation of history, and culture. Information and communications technology is used as an effective teaching tool, meeting the needs of the modern generation of students. The study is a source of guidance and practical advice for novice and experienced teachers as well as administration seeking to compare existing programs with the aim to introduce the best practice into University education.
The relationship of value and life-meaning orientations of modern students with pedagogical technologies of educational activities
Authors: Andryewskaja Sviatlana V , Bryksa Yuliya , Kiryienka Aliaksandr S , Khudziakov Andrei Y
Published: February 2021

The paper examines the relationship between value and life-meaning orientations as well as of motivation for the affiliation of modern students with pedagogical technologies of educational activities. The following pedagogical technologies are considered: the technology of problem-based learning, multilevel learning, game technologies, the project method, learning technologies in collaboration, information and communication technologies in learning. The relationship between students’ value orientations and their preferred learning organization technologies has been studied. It was revealed that students with dominant internal values prefer practice-oriented approaches and technologies in teaching. Students with a predominant locus of self-control prefer collaborative learning technology. Students with a high degree of "affiliation motivation" prefer communicative learning technologies associated with teamwork and active communication with peers. The study of personal characteristics and values of students allows organizing more efficient educational activities using new pedagogical technologies.
Study on the cross-correlation between two country for soybean futures price and exchange rate
Authors: Hua Peiyan
Published: February 2021

The paper investigates the connection between two countries’ foreign exchange and futures market for soybean, DCE NO.1 soybean and CBOT soybean as the research object by using multifractal detrended cross-correlation analysis (MF-DCCA). Results indicate a significant multifractal cross-correlation among USDCNY and two country’s soybean futures. By contrasting the multifractality of the original series to processed series, we discover that the fat-tailed distribution serves as the primary cause for USDCNY-DCE sets while the long-range correlation explains the other. Our result shows that the soybean futures in China has a higher multifractality degree, but the fluctuation of exchange rate has a better pass-through effect on the price of US soybean futures’ market.
Research on synergy of science and technology policy types and policy tools based on analysis of policy text
Authors: Guo Chundong , Niu Yibo
Published: February 2021

The development of the times has brought about a new form of policy formulation from single targeting to multi-policy coordination. It has put forward new requirements for the science and technology policy system, and how to formulate scientific and reasonable science and technology policy has become the most important problem. In order to explore the approached to this problem, this paper, combining different periods of data characteristics for comparative analysis, starts with the classification of policies and the synergistic effect of policy types and policy tools, constructing a collaborative analysis model of policy function to study the collaborative research between science and technology policy types and policy tools. Finally, it is suggested that the formulation of science and technology policy should closely combine the background of the times with the characteristics of policy types, and the corresponding policy tools should be synthetically selected to match its applicability.
Risk analysis of College Students’ e-commerce live broadcast based on data in survey
Authors: Xia Lixin , Lin Hongzhen , Huang Na , Li Jing
Published: February 2021

In the process of China’s rapid economic development, e-commerce live shopping has played an important role. However, as the main group of e-commerce live shopping for college students, related shopping risks occur frequently, causing things to harm their own interests. Therefore, it is an important topic to explore the sources of risks and measures to prevent risks. In this regard, this article uses SPSS to analyze relevant result data through a questionnaire survey, with college students as the main group of the survey. The study found that many college students have a low level of understanding of the risks of shopping, and in the process of live e-commerce shopping, they are generally concerned about product quality, business reputation and whether personal information is easy to leak. Therefore, in order to better enable college students to avoid risks in the process of live shopping and take effective measures towards the risks occurrence, we suggest strengthening the popularization of e-commerce live broadcast risk prevention knowledge for college students, so that they can master relevant legal knowledge to a certain degree. College students can take measures to retain electronic invoices or proof of their purchase while merchants can improve payment security levels.