bluuebunny/crossref_metadata_2025 huggingface dataset:
Dipole-dominated dissipative magnetic solitons in quasi-one-dimensional spin-torque oscillators
Authors: Verba R. V. , Tiberkevich V. S. , Slavin A. N.
Published: August 2020

It is well-known that a spin-transfer torque caused by a dc electric current can excite in a two-dimensional ferromagnetic film exchange-dominated magnetic solitons, often called “spin-wave bullets”, under the condition of a negative nonlinear shift of spin wave frequency. In this work, we demonstrate that in a quasi-one-dimensional (1D) case, e.g., in a nanowire spin-Hall oscillator, it is possible to excite a stable dissipative magnetic soliton, which is dominated by the dipole-dipole interaction. This dissipative magnetic soliton can be described in the framework of a 1D Ginzburg-Landau auto-oscillator model, and has the shape similar to that of the exchange-dominated spin wave bullet, but with a different spatial localization law. The influence of the dipolar interaction makes possible the stabilization of a dissipative soliton in a relatively large (micron-sized) active area of the oscillator, which is in a sharp contrast with the two-dimensional case, where the excitation of a stable spin-wave bullet was observed only in relatively small active areas having typical sizes of the order of 100 nm. The characteristics and possible applications of these dipole-dominated spin wave bullets are discussed.
Effective many-body interactions in one-dimensional dilute Bose gases
Authors: Kolezhuk A. K.
Published: August 2020

We propose a new method of constructing the effective theory for a multicomponent low-dimensional dilute Bose gas. The method is based on obtaining and solving renormalization group equations for all many-body interactions of density-density type in the one-loop approximation. In contrast to the standard approach based on two-body interactions, our method does not rely on the introduction of density-dependent infrared cutoff, and is able to reproduce exactly the leading term in the energy density of the one-dimensional dilute Bose gas, and to obtain the next term with the error of less than 2%.
Spin chirality and polarized neutrons
Authors: Maleyev S. V.
Published: August 2020

There are the static and dynamical spin chiralities. The former is a result non-collinear spin structure. The second takes place in the magnetized samples. Both are considered and illustrated by results of the neutron scattering experiments.
Spin-current dissipation in a thin-film bilayer ferromagnet/antiferromagnet
Authors: Polishchuk D. M. , Polek T. I. , Borynskyi V. Yu. , Kravets A. F. , Tovstolytkin A. I. , Pogorily A. M. , Korenivski V.
Published: August 2020

Ferromagnetic resonance in multilayer metal nanostructures containing an antiferromagnetic layer of variable thickness is studied. The contribution to the linewidth of the ferromagnetic resonance that is caused by spin-pumping current dissipation in an exchange-coupled antiferromagnetic/ferromagnetic bilayer is determined. The dissipative processes that occur in the bulk of the antiferromagnet and at the interface between the antiferromagnet (Fe50Mn50) and the ferromagnet (permalloy, Ni81Fe19) are distinguished. The details of how the dissipation transforms when the antiferromagnet Néel vector deviates from the direction of the exchange-pinning field are determined. The proposed method is effective for studying spin scattering in individual layers and at interlayer interfaces in complex magnetic systems.
Tunneling magnon flow across the terminated ferromagnetic chain
Authors: Petrov E. G.
Published: August 2020

A mechanism is proposed for transferring magnon energy from one ferromagnet to another by tunneling magnons through a bridging ferromagnetic wire that connects ferromagnets. In the framework of the model of Bose gas for the magnons, expressions are found for the power of the transferred magnon energy from a ferromagnet having a higher temperature to a colder ferromagnet. It is shown how the efficiency of tunneling transport depends on the parameters of exchange interactions in the “ferromagnet-wire-ferromagnet” system, the single-ion anisotropy of the structural units of the system, and the magnetic field. As an example, the role of single-ion anisotropy in the formation of resonant and non-resonant transmission of magnons between ferromagnets and adjacent wire terminal units is shown, which accordingly significantly enhances or weakens the tunneling flow of magnons from one ferromagnet to another.
Nonstationary forced motion of domain walls in ferrimagnets near the spin compensation point
Authors: Ivanov B. A. , Galkina E. G. , Kireev V. E. , Kulagin N. E. , Ovcharov R. V. , Khymyn R. S.
Published: August 2020

The motion of domain walls in ferrimagnets near the sublattice spin compensation point is studied theoretically, when there is an exchange enhancement in the limiting velocity of the wall. Nonlinear regimes of high-velocity nonstationary wall motion are found. A magnet parameter region in which the collective variable approach is invalid, is detected. In this region, the wall motion is accompanied by the periodic appearance of instability with respect to the increase in spin oscillations inside the domain wall.
Dynamics of pair of coupled nonlinear systems. I. Magnetic systems
Authors: Kovalev A. S. , Prilepskii Y. E. , Gradjushko K. A.
Published: August 2020

In the framework of the Landau–Lifshitz equations for discrete systems, the dynamics of two classical magnetic moments modeling weakly coupled magnetic nanodots, layers of quasi-two-dimensional magnets and two-sublattice magnets are considered. Exact solutions of dynamic equations are found and investigated. Particular attention is paid to the study of essentially nonlinear inhomogeneous states with different levels of excitation for identical subsystems as a discrete analog for the magnetic solitons.
Structural analysis of pulsed magnets considering interface characteristics
Authors: Chen S. , Peng T. , Li Y. , Lv Y. , Wang S. , Li L.
Published: August 2020

The aim of traditional designs of pulsed magnets is to keep the von-Mises stress on the midplane less than the ultimate tensile strength of materials. However, recently failed high-field experiments showed that some short circuits occurred at the magnet end, which is most possibly caused by the axial displacement of wires. This indicates that the former design is inadequate and accurate axial mechanical analysis of magnets is necessary. In this paper, a finite element model of pulsed magnets considering interface characteristics is proposed. Both the contact status and interfacial friction between the conductor layers and reinforcements can be accounted for Simulations are conducted with a failed 95 T dual-coil prototype, which was originally designed with the self-developed Pulsed Magnet Design Software (PMDS) software. The simulation results show that all the originally expected separations calculated by the PMDS software disappear due to the compression. This makes the calculated maximal von-Mises stress of the inner four reinforcement layers about 600 MPa less than the former designs. The influence of the interfacial friction is also presented. Besides, the simulations show that the maximum axial displacement at the magnet end is up to 8 mm at the designed peak field, which is deadly to the insulations. Hence, we suggest that the axial displacement at the magnet end should also be one design objective of pulsed magnets. At last, the factors affecting the axial displacement are analyzed.
Free energy of the quantum Sherrington–Kirkpatrick spin-glass model with transverse field
Authors: Adhikari Arka , Brennecke Christian
Published: August 2020

We consider the quantum Sherrington–Kirkpatrick (SK) spin-glass model with a transverse field and provide a formula for its free energy in the thermodynamic limit, valid for all inverse temperatures β > 0. To characterize the free energy, we use the path integral representation of the partition function and approximate the model by a sequence of finite-dimensional vector-spin glasses with Rd-valued spins. This enables us to use the results of Panchenko who generalized [Ann. Probab. 46(2), 829–864 (2018); ibid, 46(2), 865–896 (2018)] the Parisi formula to classical vector-spin glasses. As a consequence, we can express the thermodynamic limit of the free energy of the quantum SK model as the d → ∞ limit of the free energies of the d-dimensional approximations of the model.
Carrier-injection and succeeding pre-channel formation in organic thin-film transistor observed with time-domain reflectometry
Authors: Sakai Masatoshi , Liao Weisong , Okada Yugo , Kudo Kazuhiro
Published: August 2020

Carrier-injection and the succeeding pre-channel-formation dynamics in organic thin-film transistor was observed using time-domain reflectometry. Having previously analyzed the depth-wise variation in the initial carrier-injection from the contact electrode to the channel region, we focus here on the succeeding pre-channel-formation dynamics. We demonstrate that a hole concentration in the semiconductor/gate insulator interface increases until its electrical capacitance is filled through contact and access resistances. Thereafter, the injected-hole distribution gradually spreads. A reduction in both contact and access resistances is crucial not only for the static characteristics of the field effect transistor but also the dynamical response.
Thermal dynamic imaging of mid-infrared quantum cascade lasers with high temporal–spatial resolution
Authors: Wang Siyi , Xu Chao , Duan Fei , Wen Boyu , Rassel S. M. Shazzad , Tam Man Chun , Wasilewski Zbigniew , Wei Lan , Ban Dayan
Published: August 2020

The time-resolved (TR) temperature profile of actively biased mid-infrared quantum cascade lasers (MIR QCLs) was measured by using charge-coupled-device (CCD)-based thermoreflectance microscopy (TRM) with an ultrafast temporal resolution of 50 ns and a high spatial resolution of 390 nm. Based on the measured TR two-dimensional (2D) temperature profiles, the heat generation and dissipation dynamics within the lasers have been investigated. It is found that the active-region temperature increases quickly to a peak value (up to ∼100 °C above ambient room temperature) within 500 ns upon pulsed current injection of 6 A. The heat dissipation to the top and bottom cladding layers of the device is initially comparable, yet it evolves differently with time. Within 1–2 μs, the heat dissipation to the top cladding is substantially reduced and most of the heat is drained to the substrate through the bottom cladding layer. This constrained heat dissipation results in the elevated temperature in the active region, leading to thermal quenching of lasing operation, which is confirmed by experimental light–current–voltage measurement and theoretical thermal modeling. The TRM is an enabling tool for probing internal thermal dynamics of many active electronic and photonic devices, particularly for those needing special heat and thermal arrangement.
Heterogeneous photoresponse of individual grain in all-inorganic perovskite solar cells
Authors: Wang Yanyan , Hu Ziyang , Yao Wenlong , Yang Cheng , Zhang Houcheng , Zhang Jing , Zhu Yuejin
Published: August 2020

Photoresponse is affected by the microscopic structure and orientation of the perovskite crystals, but it is difficult to quantify the individual grain size and always acts as homogeneous. Using scanning probe microscopy, the local electrical properties of individual grains in all-inorganic perovskites are mapped. Surface potential variations on lateral distance scales within or larger than one grain size are presented. Among perovskite grains, three discrete photoconductivity levels are identified, corresponding to the facet-dependent density of trap states, which was further demonstrated by the light intensity dependence of the local current–voltage curve of each grain.
Frameworks for investigation of nonlinear dynamics: Experimental study of the turbulent jet
Authors: Rafati Sina , Clemens Noel T.
Published: August 2020

Analysis methods that have been developed in the field of nonlinear dynamics have provided valuable insights into the physics of turbulent flows, although their application to open flows is less well explored. The nonlinear dynamics of a turbulent jet with a low-to-moderate Reynolds number is investigated by using the single-trajectory framework and ensemble framework. We have used Lyapunov exponents to calculate the spectra of scaling indices of the attractor. First, we evaluated the frameworks on two theoretical models, one with a stationary attractor (Lorenz-63) and the other with time-varying characteristics (Lorenz-84). Theoretical studies showed that in dynamical systems with a stable attractor, both frameworks estimated the same largest Lyapunov exponent. The ensemble framework enables us to resolve the unsteady characteristics of a time-varying strange attractor. Second, we applied both frameworks to time-resolved planar velocity fields in a turbulent jet at local Reynolds numbers (Reδ) of 3000 and 5000. Time-resolved particle image velocimetry was utilized to measure streamwise and transverse velocity components. Results support the presence of a low-dimensional attractor in the reconstructed phase space with a chaotic characteristic. Despite considerable changes in the dynamics for the higher Reynolds number case, the system’s fractal dimension did not change significantly. We have used Lagrangian Coherent Structures (LCSs) to study the relationship between changes in the Lyapunov exponent with flow topological features. Results suggest that holes in the stable LCSs provide a path for the entrainment of the coflow, which is shown to be one of the main contributors to high Lyapunov exponents.
Enhancement of the spin–orbit torque efficiency in W/Cu/CoFeB heterostructures via interface engineering
Authors: Yang Pei , Shao Qiming , Yu Guoqiang , He Congli , Wong Kin , Lu Xianyang , Zhang Junran , Liu Bo , Meng Hao , He Liang , Wang Kang L. , Xu Yongbing
Published: August 2020

Here, the spin-torque ferromagnetic resonance signal and the spin Hall magnetoresistance induced by the spin Hall effect of W/Cu/CoFeB heterostructures with different Cu layer thicknesses (tCu) have been systemically studied. The effective spin mixing conductance geff↑↓, the interfacial spin transparency T, and the real spin–orbit torque efficiency (JsJc)real show a significant increase compared to the W/CoFeB heterostructure. (JsJc)real reaches its maximum of ∼0.54, increased up to ∼50% at the optimized tCu ∼ 0.52 nm according to our theoretical prediction. More importantly, the intrinsic spin Hall angle of W, θSHint ∼ 0.79 ± 0.20, has also been obtained after the correction of the inverse spin Hall effect and T. This suggests that the Cu insertion improves the interface quality and, therefore, assists the spin transport in the heterostructures, which potentially improves the performance of next-generation spintronic devices.
Unraveling magneto-structural coupling of Ni2MnGa alloy under the application of stress and magnetic field using in situ polarized neutron diffraction
Authors: Ke Y. B. , Lan S. , Wu Y. , Wu H. H. , Hutanu V. , Deng H. , Pramanick A. , Ren Y. , Wang X.-L.
Published: August 2020

The magneto-structural evolution of a Ni2MnGa single crystal was investigated by in situ polarized neutron diffraction under both magnetic field and mechanical loading. The ability to separate the nuclear and magnetic scatterings by polarized neutrons enables simultaneous observations of the twin reorientation (through twin boundary motion) and magnetic moment configuration. It is found that under a 1.0 T saturating magnetic field, twin reorientation can be activated by compressive stress and is accompanied by a realignment of the magnetic moment, which follows the easy axis of the twin variant. On the other hand, compressive stress as small as 1.0 MPa can freeze the twin reorientation. The evolution of the magnetic scattering amplitudes suggests that the change in magnetization was mainly achieved through the magnetic domain wall motion, while the twin boundary motion was blocked.
Understanding the sensitivity of the two-temperature model for electron–phonon coupling measurements
Authors: Naldo Sarah B. , Bernotas Andrius V. , Donovan Brian F.
Published: August 2020

A crucial parameter in understanding hot electron physics is the electron–phonon (EP) coupling factor along with the governing physical relationships of the Two-Temperature Model (TTM) for electron thermalization. One of the most common ways to experimentally interrogate EP coupling is via ultra-fast optical excitement and thermoreflectance measurement. While there has been a significant amount of work using this method, there has been relatively little exploration of the sensitivity of the TTM to the parameters involved. In this work, we utilize the mathematical formulation of the least squares fitting method in order to understand the sensitivity of the TTM to the various thermophysical factors involved. We find that analysis of the sum of squared errors yields substantial physical insight and will help guide experimentalists in their ability to confidently measure a wide variety of hot electron dynamics.
Demonstration of single-phase wurtzite BAlN with over 20% boron content by metalorganic chemical vapor deposition
Authors: Tran Tinh Binh , Liao Che-Hao , AlQatari Feras , Li Xiaohang
Published: August 2020

Wurtzite BAlN alloys are emerging ultrawide bandgap III-nitride semiconductors promising for optical and electronic devices. Yet the boron compositions of the grown alloys have been limited. In this Letter, we report on the demonstration of a thick single-phase wurtzite BAlN film with a boron composition over 20%. The growth was conducted at 1010 °C and 150 Torr with continuous flows of group-III precursors and ammonia with a growth rate of 2.2 μm/h by metalorganic chemical vapor deposition. The boron composition was studied by x-ray diffraction (XRD), secondary neutral mass spectrometry (SNMS), and Rutherford backscattering spectrometry (RBS). The XRD 2θ scan exhibited the clear wurtzite BAlN peak 1.82° larger than the AlN peak, indicating the boron composition of 30.9% based on the lattice constants of wurtzite AlN and BN. The SNMS and RBS experiments, independent of strain and defects, revealed that the boron content was 22%. The microstructures of the wurtzite BAlN film were further studied by transmission electron microscopy, showing an initial 5 nm thick layer free of crystal twinning followed by widespread crystal twinning with lattice rotations of 60° clockwise and anti-clockwise. The optical transmission experiment manifested that the bandgap of the smaller-lattice BAlN film was 5.1 eV, smaller than that of larger-lattice AlN. This trend was the opposite of the conventional InGaAlN but consistent with theoretical predictions. This study would greatly facilitate the research of material, physics, and devices incorporating the wurtzite BAlN alloys.
Effect of interfacial oxidation layer in spin pumping experiments on Ni80Fe20/SrIrO3 heterostructures
Authors: Suraj T. S. , Müller Manuel , Gelder Sarah , Geprägs Stephan , Opel Matthias , Weiler Mathias , Sethupathi K. , Huebl Hans , Gross Rudolf , Ramachandra Rao M. S. , Althammer Matthias
Published: August 2020

SrIrO3 with its large spin–orbit coupling and low charge conductivity has emerged as a potential candidate for efficient spin–orbit torque magnetization control in spintronic devices. Here we report on the influence of an interfacial oxide layer on spin pumping experiments in Ni80Fe20 (NiFe)/SrIrO3 bilayer heterostructures. To investigate this scenario, we have carried out broadband ferromagnetic resonance (BBFMR) measurements, which indicate the presence of an interfacial antiferromagnetic oxide layer. We performed in-plane BBFMR experiments at cryogenic temperatures, which allowed us to simultaneously study dynamic spin pumping properties (Gilbert damping) and static magnetic properties (such as the effective magnetization and magnetic anisotropy). The results for NiFe/SrIrO3 bilayer thin films were analyzed and compared to those from a NiFe/NbN/SrIrO3 trilayer reference sample, where a spin-transparent, ultra-thin NbN layer was inserted to prevent the oxidation of NiFe. At low temperatures, we observe substantial differences in the magnetization dynamics parameters of these samples. In particular, the Gilbert damping in the NiFe/SrIrO3 bilayer sample drastically increases below 50K, which can be well explained by enhanced spin fluctuations at the antiferromagnetic ordering temperature of the interfacial oxide layer. Our results emphasize that this interfacial oxide layer plays an important role for the spin current transport across the NiFe/SrIrO3 interface.
Synthesis, Characterisation, and Determination of Physical Properties of New Two-Protonic Acid Ionic Liquid and its Catalytic Application in the Esterification
Authors: Shahnavaz Zohreh , Zaharani Lia , Khaligh Nader Ghaffari , Mihankhah Taraneh , Johan Mohd Rafie
Published: August 2020

A new ionic liquid was synthesised, and its chemical structure was elucidated by FT-IR, 1D NMR, 2D NMR, and mass analyses. Some physical properties, thermal behaviour, and thermal stability of this ionic liquid were investigated. The formation of a two-protonic acid salt namely 4,4′-trimethylene-N,N′-dipiperidinium sulfate instead of 4,4′-trimethylene-N,N′-dipiperidinium hydrogensulfate was evidenced by NMR analyses. The catalytic activity of this ionic liquid was demonstrated in the esterification reaction of n-butanol and glacial acetic acid under different conditions. The desired acetate was obtained in 62–88% yield without using a Dean–Stark apparatus under optimal conditions of 10 mol-% of the ionic liquid, an alcohol to glacial acetic acid mole ratio of 1.3:1.0, a temperature of 75–100°C, and a reaction time of 4h. α-Tocopherol (α-TCP), a highly efficient form of vitamin E, was also treated with glacial acetic acid in the presence of the ionic liquid, and O-acetyl-α-tocopherol (Ac-TCP) was obtained in 88.4% yield. The separation of esters was conducted during workup without the utilisation of high-cost column chromatography. The residue and ionic liquid were used in subsequent runs after the extraction of desired products. The ionic liquid exhibited high catalytic activity even after five runs with no significant change in its chemical structure and catalytic efficiency.
Synthesis of a Novel Library of 1-Substituted Pyrido[1,2-a]benzimidazoles
Authors: Gadde Satyanarayana , Leung Yun Cheuk , Bhadbade Mohan , Cheung Belamy B. , Black David StC. , Kumar Naresh
Published: August 2020

The reactivity and synthesis of new analogues of pyrido[1,2-a]benzimidazoles have been explored. Twenty-three derivatives bearing phenoxy, thiophenoxy, aniline, and aryl groups at the 1-position were successfully synthesised in 25–91% yield, via nucleophilic substitution, Buchwald–Hartwig amination, and Suzuki coupling type processes. Solvent free synthetic protocols were employed to achieve the nucleophilic substitution of anilines with electron donating groups or moderately electron withdrawing groups on a sterically demanding intermediate (7a). An unusual polycyclic heterocycle was identified as a side-product during this work: a dimeric bis(pyrido[1,2-a]benzimidazole).
Transcriptome-wide analysis of PGC-1α–binding RNAs identifies genes linked to glucagon metabolic action
Authors: Tavares Clint D. J. , Aigner Stefan , Sharabi Kfir , Sathe Shashank , Mutlu Beste , Yeo Gene W. , Puigserver Pere
Published: August 2020

Significance

Glucagon action in liver is a central response to fasting and type 2 diabetes. Glucagon action has been delineated through regulatory mechanisms involving signaling, transcription factor/coactivator-based gluconeogenic gene expression, and metabolic enzyme activity. Understanding the molecular mechanisms whereby glucagon controls energy metabolism will define new strategies and potential therapies to treat metabolic diseases. Here, we have identified a regulatory mechanism whereby PGC-1α, a known transcriptional regulator of glucagon action, binds RNAs linked to glucose energy metabolism. PGC-1α represents a class of RNA-binding proteins that act as a transcriptional coactivator through transcription factor binding, but also binds to RNA sequences to control specific mRNA transcripts encoding for metabolic and bioenergetic genes.
Glycosylation-dependent opsonophagocytic activity of staphylococcal protein A antibodies
Authors: Chen Xinhai , Shi Miaomiao , Tong Xin , Kim Hwan Keun , Wang Lai-Xi , Schneewind Olaf , Missiakas Dominique
Published: August 2020

Significance

All currently licensed antibodies against bacteria target exotoxins. For most pathogens, neutralization of toxin(s) is not sufficient to prevent bacterial replication. Antibodies against surface determinants represent better candidates to enhance opsonophagocytic killing, but the mechanisms of action of such antibodies have not been systematically studied. Staphylococcal protein A is a conserved surface protein of
Staphylococcus aureus
and a crucial virulence determinant that manipulates B-cell responses and blocks deposition of opsonin. Monoclonal antibodies directed against SpA represent potential therapeutic agents as well as a formidable tool to identify and optimize effector functions of antibodies that can promote bacterial clearance.
Genomic plasticity of pathogenic
Escherichia coli
mediates
d
-serine tolerance via multiple adaptive mechanisms
Authors: O’Boyle Nicky , Connolly James P. R. , Tucker Nicholas P. , Roe Andrew J.
Published: August 2020

Significance

Pathogens ensure infection of favored sites in the body by responding to chemical signals. One chemical abundant in urine, the amino acid
d
-Ser, is toxic to EHEC and reduces expression of the machinery used for host cell attachment, making the bladder an unfavorable environment. We observed that under
d
-Ser stress, EHEC acquires genetic changes that lead to blocking
d
-Ser uptake into the cell or activating a silent enzyme for degrading
d
-Ser. This prevents growth inhibition and, critically, inhibits the repression of attachment machinery normally caused by
d
-Ser. These findings highlight the importance of pathogen evolution in determining how host molecules regulate colonization. These interactions underpin a process known as niche restriction that is important for pathogen success within the host.
ERPP provision in the UK
Authors: Walková Milada
Published: August 2020

This paper attempts to map the territory of ERPP, both in terms of pedagogical theory and its practical application, in the United Kingdom. The aim of the paper is threefold. First, the paper reviews specific challenges of researchers writing in English as their additional language and working in ‘periphery’ countries. Second, based on the review and working within the framework of critical pragmatic EAP (Harwood & Hadley, 2004), the paper proposes five ingredients of a comprehensive ERPP curriculum, namely (a) publication process, (b) language and rhetorical conventions of ERPP genres, (c) writing for an international audience, (d) collaboration, and (e) sharing research outcomes. Taken together, these develop not only Kwan’s (2010) four competences for research publication, but also three additional competences for ERPP proposed here – collaborative competence, outreach competence and competence in building resilience. Finally, the paper discusses ERPP provision available at the Russell Group universities in the UK and evaluates it against the proposed curriculum, highlighting examples of good teaching practice and areas for further pedagogical development.
Computational prediction of RNA tertiary structures using machine learning methods*
Authors: Huang Bin , Du Yuanyang , Zhang Shuai , Li Wenfei , Wang Jun , Zhang Jian
Published: August 2020

RNAs play crucial and versatile roles in biological processes. Computational prediction approaches can help to understand RNA structures and their stabilizing factors, thus providing information on their functions, and facilitating the design of new RNAs. Machine learning (ML) techniques have made tremendous progress in many fields in the past few years. Although their usage in protein-related fields has a long history, the use of ML methods in predicting RNA tertiary structures is new and rare. Here, we review the recent advances of using ML methods on RNA structure predictions and discuss the advantages and limitation, the difficulties and potentials of these approaches when applied in the field.
Polarization-insensitive complementary metamaterial structure based on graphene for independently tuning multiple transparency windows*
Authors: Huang Hailong , Xia Hui , Li Hongjian
Published: August 2020

Polarization-insensitive multiple transparency windows are obtained with a graphene-based complementary metamaterial structure in terahertz regions, which is composed of two kinds of monolayer graphene perforated in shapes of a cross and four identical split rings that construct a resonator. The geometric parameters of resonators are different from each other. Numerical and theoretical results show that the quantum effect of Autler–Townes splitting is the key factor for appearance of transparency windows within the resonant dips. Further investigation demonstrates that by employing the fourfold-symmetry graphene complementary structure, polarization-independent transparency windows can be achieved. Moreover, multiple transparency windows can be separately manipulated over a broad frequency range via adjusting the chemical potential of the corresponding graphene resonators, and the bandwidth as well as resonance strength can also be tuned by changing the relative displacement between resonators each consisting of a cross and four split rings. The proposed metamaterial structure may be utilized in some practical applications with requirements of no polarization-varied loss and slowing the light speed.
Interfacial properties of g-C3N4/TiO2 heterostructures studied by DFT calculations*
Authors: Peng Chen-Shan , Zhou Yong-Dong , Zhang Sui-Shuan , Zhao Zong-Yan
Published: August 2020

Constructing the hetrostructure is a feasible strategy to enhance the performances of photocatalysts. However, there are still some fundamental details and mechanisms for the specific design of photocatalysts with heterostructure, which need further confirming and explain. In this work, g-C3N4-based heterostructures are constructed with TiO2 in different ways, and their intrinsic factors to improve the photocatalytic activity are systematically studied by density functional theory (DFT). When g-C3N4 combines horizontally with TiO2 to form a heterostructure, the interaction between them is dominated by van der Waals interaction. Although the recombination of photo-generated electron–hole pair cannot be inhibited significantly, this van der Waals interaction can regulate the electronic structures of the two components, which is conducive to the participation of photo-generated electrons and holes in the photocatalytic reaction. When the g-C3N4 combines vertically with TiO2 to form a heterostructure, their interface states show obvious covalent features, which is very beneficial for the photo-generated electrons’ and holes’ transport along the opposite directions on both sides of the interface. Furthermore, the built-in electric field of g-C3N4/TiO2 heterostructure is directed from TiO2 layer to g-C3N4 layer under equilibrium, so the photo-generated electron–hole pairs can be spatially separated from each other. These calculated results show that no matter how g-C3N4 and TiO2 are combined together, the g-C3N4/TiO2 heterostructure can enhance the photocatalytic performance through corresponding ways.
Influences of increasing gate stem height on DC and RF performances of InAlAs/InGaAs InP-based HEMTs*
Authors: Tong Zhi-Hang , Ding Peng , Su Yong-Bo , Wang Da-Hai , Jin Zhi
Published: August 2020

The T-gate stem height of InAlAs/InGaAs InP-based high electron mobility transistor (HEMT) is increased from 165 nm to 250 nm. The influences of increasing the gate stem height on the direct current (DC) and radio frequency (RF) performances of device are investigated. A 120-nm-long gate, 250-nm-high gate stem device exhibits a higher threshold voltage (V
th) of 60 mV than a 120-nm-long gate devices with a short gate stem, caused by more Pt distributions on the gate foot edges of the high Ti/Pt/Au gate. The Pt distribution in Schottky contact metal is found to increase with the gate stem height or the gate length increasing, and thus enhancing the Schottky barrier height and expanding the gate length, which can be due to the increased internal tensile stress of Pt. The more Pt distributions for the high gate stem device also lead to more obvious Pt sinking, which reduces the distance between the gate and the InGaAs channel so that the transconductance (g
m) of the high gate stem device is 70 mS/mm larger than that of the short stem device. As for the RF performances, the gate extrinsic parasitic capacitance decreases and the intrinsic transconductance increases after the gate stem height has been increased, so the RF performances of device are obviously improved. The high gate stem device yields a maximum f
t of 270 GHz and f
max of 460 GHz, while the short gate stem device has a maximum f
t of 240 GHz and the f
max of 370 GHz.
On Board Intelligence for Public Transportation in Developing Countries using IoT
Authors: Rehman A , Mumtaz T
Published: August 2020

This study is carried out for indigenous development of an ITS (Intelligent Transportation System) device aimed particularly for public transport buses in the developing countries with poor infrastructure and unaccountable transportation services. The developed system uses IoT technology, extendable hardware and open source software in order to achieve commercial scalability by government and transportation authorities in such countries. The proposed device essentially collects and store data from the bus fleet and communicates the information to a central server from which software applications for passengers and transport operators are developed accordingly. The device functionality is divided into three categories which are Environment Sensing, Vehicle Management and Safety. The acquired dataset can be used to produce useful insights that can benefit the social and commercial sector of the city. Analytics such as fuel consumption, vehicle health, predicting driver behaviour, forecasting of rush-hours and vehicle maintenance requirements can be estimated. The device is packaged into a box with proper considerations of reliability in terms of power, weather proofing, storage and cabling. The proposed device will allow the passengers, especially in developing cities, to plan their journeys ahead of time and provide a holistic decision support system to the transport authorities.
Self-cleaning of glass surface to maximize the PV cell efficiency
Authors: Ayaz Adnan , Ahmad Hussain , Ahmad Faraz , Khan Ahmad , hasnain Tarmazi S. M. , Gul Rizwan M. , saher Saim
Published: August 2020

Photovoltaic (PV) modules are widely used for harnessing solar energy which ensure maximum output when their glass surface is clean. However, PV modules are open to dust, grime and other contaminations which get deposited on their surface causing reduction in transmittance and hence their efficiency reduces. It is therefore required to clean the glass surface of PV modules time to time either manually by labor or using some special arrangements such as automated systems. However, these techniques are either laborious or require extra energy. Therefore, another solution to offset such complications is to use chemical coatings which ensure self-cleaning of glass surface by increasing water contact angle. In the present study, two types of water repellent chemicals (such as trimethylchlorosilane and hexamethyldisilazane) have been used to coat the glass surface using dip coating technique. The performance of such coated glass slides has been investigated using some important characterization techniques, such as finding transmittance by spectrophotometer and measuring water contact angle using a high resolution camera. Moreover, the self-cleaning effect has been observed using a microbalance to measure dust on coated glass exposed to open atmosphere and compared with uncoated glass. The results revealed that these coatings have increased the water contact angle up to 149% which reduces friction between the glass surface and water droplets. Moreover, the friction reduction helps in mobility of water droplets which in turn can easily carry out dust along with them, thus improving the efficiency of PV module.
Cost-effective, Reliable, and Precise Surface Mount Device (SMD) on PCBs
Authors: Iftikhar B , Malik M M , Hadi S , Wajid O , Farooq M N , Rehman M M , Hassan A K
Published: August 2020

Automated Pick-and-Place (P&P) machines offer a new prospective for the assembly of Surface Mount Devices (SMDs) on Printed Circuit Boards (PCBs), owing to their advantages of time-effectiveness and precision. SMDs are widely used to improve production efficiency and reduce common defects. However, these machines are quite expensive and not easily available for the local market. This study is based on the design of a P&P machine model that incorporates principles of machine learning theory. The model has been developed in such a way that it can be introduced to the local market in a more cost-effective manner without compromising on its precision and accuracy.
Stress Analysis of Composite Leaf Spring – Comparative Approach
Authors: Malik Sheharyar , Afaq Kamran S.
Published: August 2020

Automobile manufacturers are focusing on weight reduction for saving natural resources and enhancing the fuel efficiency; automobiles are sharing almost half of the world’s fuel consumption and a major source of pollution, thus reducing the weight will directly result in the reduction of fuel consumption. The leaf spring is one of the main candidates for the weight reduction in an automobile as they still holds the worth although many shocks absorbing devices are in the market these days. This paper is aimed to present the comparative study of steel and composite leaf spring with the later type having the same geometrical characteristics of steel leaf spring. Validations are carried out by modelling leaf spring on ANSYS & comparing it with analytical results. The results showed that the stresses in composite leaf spring are 64.8% lower than the stresses in the steel leaf spring for the same geometrical characteristics. The results for deflections showed also good agreement with analytical results and a decrement of 51.3% is found for composite leaf spring. The proposed methodology helps us to reduce the weight of leaf spring by approximately 74.39% without compromising on allowable stresses and thus also increasing the strain energy of the particular leaf spring.
Performance of statistical control tools in identifying the defect on plunger- A review
Authors: Aravindhan N. , Chidambaranathan BIBIN , Rokesh D. , Jagadesh D. , Pravin S. , Ramkumar N.
Published: August 2020

In this paper, we carried out a study to upsurge the brilliance of the plungers used in the braking system. The main focus has been taken on various defects that occur in the plungers during manufacturing. In this work, we analyzed the types of defects that transpire in the plunger. The foremost issue is acknowledged using tools like Pareto graphic representation, root and effect diagram, Failure Mode and Effect Analysis, Trend Analysis and Control chart. We identified more frequently occurring defects and major causes and effects of these defects in plungers. Based on the result of the analysis, interpretation measures are taken to overcome the defects of the plungers that will help to improve the overall efficiency of the brake system in vehicles.
Implementation of on-demand low rate wireless parameter monitoring system for industrial machineries.
Authors: Shrivastava Riya , Kodnani Jigyasa , Gupta Samridhi , Mehta Dakshta , Raja Singh R. , Meikandasivam S.
Published: August 2020

Systematic and rigorous monitoring of critical equipment is the cornerstone of any successful preventive management system in the industrial environment. Recent developments in cost-effective wireless sensor network (WSN) technologies promising a wider and more sustainable deployment of distributed sensing and processing infrastructure. In this research work, it is mainly focused on the electrical monitoring parameter and enable remote switching devices for optimal power management systems using ZigBee. This paper proposes a digital system for electrical system parameters such as voltage and current using ZigBee-based wireless sensor networks (WSNs). The main feature of ZigBee protocol, to act as a communicable medium between transmitter and receiver modules, which is suitable for the industrial environment.
Description
Authors: Stalnaker Joanna
Published: August 2020

Description is generally associated with the novel in its modern form, a perception captured in one of the dictums from Gustave Flaubert’s Dictionary of Received Ideas: “Descriptions: There are always too many of them in novels.” But description has a much longer history and abounds in other genres, from the epic to lyric and didactic poetry to tragedy and beyond. In the 18th century, it was even considered a genre unto itself, in the newly conceived genre of descriptive poetry popularized by the Scottish poet James Thomson. Description also features prominently in genres of writing often considered nonliterary, such as encyclopedias, scientific writing, how-to manuals, and travel guides. Indeed, critical suspicion surrounding description in Western rhetorical and poetic tradition stems in part from the perception that it can too easily become a site for the incursion of the nonliterary (i.e., things rather than people, scientific or technical knowledge, abstruse vocabulary) into the literary domain.

Description resists easy definition and has been characterized as one of the blind spots of Western literary discourse. In antiquity, rhetorical and poetic treatises gave scant attention to description, and neoclassical poetic doctrine was more concerned with policing description’s boundaries than defining it. It was not until the 18th century that description emerged as a theoretical problem worthy of debate and as a prominent literary practice. Since antiquity, description has been associated with visualization and the visual arts, through the rhetorical figures of enargeia and ekphrasis and the Renaissance doctrine of ut pictura poesis. Through this association, description has close ties to mimesis and has proved especially vulnerable to Platonic attacks on poetry, and on literature more broadly, as a mere copy of reality. In the 19th century, description featured prominently in the realist novel, but in the mid-20th century it was used, notably by the French New Novelists, as a means of contesting realism. Formalist and structuralist criticism sparked renewed interest in theorizing description in the 1970s and 1980s. At the beginning of the 21st century, in an age of interdisciplinarity when the boundaries between the literary and the nonliterary have become increasingly porous, description has once again emerged as a key theoretical problem for thinking across disciplines and has even been proposed as a new mode of reading that avoids the pitfalls of humanist hermeneutics.
Citizenship of the European Union
Authors: Maas Willem
Published: August 2020

Citizenship is usually conceptualized as a unitary and exclusive relationship between an individual and a sovereign state; yet the European Union (EU) has developed the most advanced form of contemporary supranational citizenship. Citizenship of the European Union guarantees EU citizens and most members of their families the right to move, live, and work across the territory of the EU. It also guarantees the right to vote in local and European elections in the member state of residence, the right to consular protection outside the EU when the member state of nationality is not represented, the right to access documents or petition Parliament or the Ombudsman in any of the official languages, and the right to be treated free from nationality-based discrimination. Though on the political agenda since the postwar origins of European integration, EU citizenship was not formalized into EU law until the Maastricht Treaty. Since then, the Court of Justice of the European Union (CJEU) has declared that “EU Citizenship is destined to be the fundamental status of nationals of the Member States” and there are ongoing discussions about the relationship between EU and member state citizenship. In terms of identity, increasing numbers of Europeans see themselves as citizens of the EU, and questions of citizenship are at the heart of debates about the nature of European integration.
Development Policy and European Union Politics
Authors: Arts Karin
Published: August 2020

Development cooperation is one of the traditional policy domains of the European Union (EU). Over the years it advanced from an instrument used in colonial times to one of modern partnership, although European self-interest remains a driving force. Jointly, the EU and its member states are the largest development donor in the world and also provide sizable market access and investment to developing countries. Their overall performance record has been assessed fairly positively by internal and external parties, although many possible improvements have been identified. The various enlargements of the EU traceably supported a widening of the geographic and substantive scope of EU development policies and practice. In addition, EU development cooperation was reinforced by the fact that it gradually received a firmer basis in the constituent EU treaties.

The “European Consensus on Development” document, as revised in 2017, laid out the main direction of and emphases in EU development cooperation until the year 2030. The European Consensus prescribed a rights-based approach, and squarely placed the United Nations “Agenda 2030” and the Sustainable Development Goals (SDGs) contained in it, as the main framework and objectives for EU development cooperation.

A wide range of actors is involved in EU development cooperation, in part because this is an area of shared competence among the EU member states that pursue their own national policies as well as those specified by the EU. Thus, EU actors such as the European Commission, Council, and Parliament feature in this policy field along with EU member states and individual or collective developing country actors. The most prominent example of this is the African, Caribbean, and Pacific (ACP) Group of States, which consists of 79 countries. Civil society organizations, including non-governmental development organizations, both from the North and the South, also seek to influence or otherwise engage with the policies and practices of EU development cooperation.

While EU development cooperation is an established policy field, it is also still very much a work in progress, and major challenges lay ahead for action in the period up to 2030, the year in which the SDGs are to be realized. These major challenges include funding, strengthening the EU’s political clout in the world by using development cooperation more strategically for forging and influencing global decision-making on relevant topics, renewing and innovating the relations between the EU and ACP countries, handling the consequences of Brexit, and improving on the delivery of EU development cooperation.