bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetophotonics for sensing and magnetometry toward industrial applications
Authors: Rizal Conrad , Manera Maria Grazia , Ignatyeva Daria O. , Mejía-Salazar Jorge R. , Rella Roberto , Belotelov Vladimir I. , Pineider Francesco , Maccaferri Nicolò
Published: December 2021

Magnetic nanostructures sustaining different types of optical modes have been used for magnetometry and label-free ultrasensitive refractive index probing, where the main challenge is the realization of compact devices that are able to transfer this technology from research laboratories to smart industry. This Perspective discusses the state-of-the-art and emerging trends in realizing innovative sensors containing new architectures and materials exploiting the unique ability to actively manipulate their optical properties using an externally applied magnetic field. In addition to the well-established use of propagating and localized plasmonic fields, in the so-called magnetoplasmonics, we identified a new potential of the all-dielectric platforms for sensing to overcome losses inherent to metallic components. In describing recent advances, emphasis is placed on several feasible industrial applications, trying to give our vision on the future of this promising field of research merging optics, magnetism, and nanotechnology.
Linear stability of a contaminated shear-imposed viscoelastic liquid flowing down an inclined plane
Authors: Pal Subham , Samanta Arghya
Published: December 2021

A linear stability analysis is carried out for a contaminated viscoelastic liquid flowing down an inclined plane in the presence of an imposed shear stress, where the elastic behavior of the liquid follows the upper-convected Maxwell model. The earlier work [Wei, “Stability of a viscoelastic falling film with surfactant subjected to an interfacial shear,” Phys. Rev. E 71, 066306 (2005)] conducted analytically in the long-wave regime is revisited again in exploring the results in the arbitrary wavenumber regime. An Orr–Sommerfeld-type eigenvalue problem is formed for the viscoelastic liquid and solved both analytically and numerically by using the long-wave expansion and Chebyshev spectral collocation technique, respectively. It is found that with increase in the value of the Weissenberg number, the critical Reynolds number for the interface mode reduces, but the stable region enhances in the finite wavenumber regime. Furthermore, the unstable domain induced by the interface mode reduces in the presence of insoluble surfactant but enhances in the presence of applied shear stress. If the Reynolds number is high, but the inclination angle is small, the shear mode arises in the numerical simulation, which becomes weaker in the presence of the Weissenberg number and Marangoni number but becomes stronger in the presence of applied shear stress. In a special case, it is demonstrated that the present study recovers the results of Walters's liquid B″ in the limit of low viscoelastic parameter.
Generation of Amplified Spontaneous Emission in Lead Halide Perovskite Semiconductors
Authors: Suárez Isaac , Martínez Pastor Juan P.
Published: December 2021

Lead halide perovskites (LHPs) have arisen as a new class of semiconductors with excellent perspectives to become an alternative to traditional III–V epitaxial nanostructures for applications in active photonics. From the earliest demonstration of amplified spontaneous emission (ASE) with CH3NH3PbX3 (X = Cl, Br, I) polycrystalline thin films in 2014, more than 200 papers have been published in this field with regards to the improvement of the ASE figures of merit or the understanding of the underlaying physical mechanisms in the generation of optical gain for different LHPs. This extraordinary progress has resulted in the synthesis of either CH3NH3PbX3 perovskites as polycrystalline thin films or layers made of fully inorganic CsPbX3 perovskite nanocrystals (PNCs) that can be integrated in different optical architectures or substrates using cheap and straightforward solution processing techniques. Consequently, ASE with thresholds smaller than a few nJ cm−2 or lasing under continuous wave operation, among other impressive results, have been recently achieved. The role of the radiative recombination time, nonradiative traps, Auger recombination, excitation fluency, and absorption coefficient are discussed in this chapter within the framework of available studies and results in the literature, as well as in the light of our own work. This chapter will also review the most important results obtained by the scientific community in the field of active photonic devices and integrated concepts based on LHPs, which contain the integration of bulk polycrystalline and PNC thin films on different substrates, even those which are flexible. Spontaneous emission and ASE will be discussed based on a rate equation model incorporated into a beam propagation algorithm, in the case of optical waveguides, to simulate the generation and propagation of emitted light and optical gain, as an important tool toward the design of active integrated photonics based on LHPs.
Perovskite Metamaterials and Metasurfaces
Authors: Adamo Giorgio , Tian Jingyi , Krishnamoorthy Harish N. S. , Cortecchia Daniele , Long Guankui , Soci Cesare
Published: December 2021

Nanophotonics has emerged in recent years as the branch of science capable of connecting conventional optics with nanoscale phenomena. The key feature enabling this convergence is the ability of nanosized photonic objects to confine light within volumes comparable to or smaller than their physical sizes, far beyond the wavelength of the optical excitation. Proper arrangements of a large number of nanophotonic building blocks on two-dimensional landscapes, known as metamaterials and metasurfaces, allow for considerable enhancement of the response of the individual constituent parts and give access to optical functionalities, which would otherwise be unattainable.
Reptile assisted reproductive technologies: can ART help conserve 300 million years of evolution by preserving extant reptile biodiversity?
Authors: Perry Sean M. , Mitchell Mark A.
Published: December 2021

Biodiversity loss is the greatest environmental problem threatening ecosystem, animal, and human health. Anthropogenic induced changes to climate, habitat, disease, species distributions, poaching, and unsustainable trade have accelerated extinction rates in all vertebrates, including reptiles. Preventing reptile extinctions will require humans to acknowledge these losses and develop ex situ and in situ plans to preserve them. Assisted reproductive technologies (ART) are management tools used to protect numerous vertebrate taxa; however, progress in developing ART for reptiles has lagged. Creating functional and sustainable reptile ART will strengthen our conservation capacity by capturing genetic material from select individuals to overcome natural or manmade boundaries. Utilising short-term gamete storage and genome resource banking, in conjunction with timed artificial insemination (AI) or ex ovo incubation, could lead to profound advances in reptile conservation, mitigating the loss of reptile biodiversity. In this article, we review ART reptile research completed since the 1970s. Topics include AI, hormonal control of reproduction, gamete collection, gamete storage, and genome resource banking. Additionally, we review the potential application of advanced reproductive methodologies, including in vitro/ex ovo fertilisation, intracytoplasmic sperm injection, cloning (somatic cell nuclear transfer), and genetic editing.
Neutrophil:lymphocyte and estradiol:progesterone ratios as predictive markers for ovarian hyperstimulation syndrome (OHSS)
Authors: Baser Emre , Aydogan Kirmizi Demet , Ozelci Runa , Aldemir Oya , Dilbaz Berna , Dilbaz Serdar , Moraloglu Tekin Ozlem
Published: December 2021

This study was based on the pathophysiology of the disease and aimed at predicting ovarian hyperstimulation syndrome (OHSS) by determining the importance of ratios obtained from the inflammatory process associated with oestradiol and progesterone in recent years. Out of 242 infertile women who underwent assisted reproductive therapy, 59 patients who developed OHSS were taken as the study group, while the remaining 122 normo-responder (NR) and 61 hyper-responder (HR) patients constituted the control group. The neutrophil to lymphocyte (NLR) and oestradiol/progesterone (EPR) ratios were found to be statistically significantly higher in the OHSS group (P < 0.001). A multivariate logistic regression analysis revealed that the NLR (OR = 2.410, P = 0.001) and EPR (OR = 1.701, P = 0.028) were independent predictors for the development of OHSS. In conclusion, in OHSS inadequate progesterone levels may inhibit suppression of the exaggerated inflammatory process caused by high E2 levels, and NLR and EPR can be used to predict the development of OHSS in patients undergoing controlled ovarian hyperstimulation during in vitro fertilisation cycles.
Amphiphilic proteins coassemble into multiphasic condensates and act as biomolecular surfactants
Authors: Kelley Fleurie M. , Favetta Bruna , Regy Roshan Mammen , Mittal Jeetain , Schuster Benjamin S.
Published: December 2021

Significance

Membraneless organelles are assemblies of highly concentrated biomolecules that condense through liquid–liquid phase separation. One major question in the field is how proteins assemble into multilayered condensates. Understanding mechanisms of formation of these systems is important for understanding the function and regulation of multiphasic organelles, such as P granules and nucleoli. A second outstanding question is how the size of biomolecular condensates is controlled. In this work, we generated amphiphilic proteins that localize to the surface of condensates. We observed diverse assemblies, including condensates enveloped by surfactant-like films, as well as complex multiphasic morphologies. In some configurations, these surfactant-like proteins influence condensate size. Our results suggest an important role of protein amphiphiles in establishing membraneless organelle structure and function.
Recurrent high-impact mutations at cognate structural positions in class A G protein-coupled receptors expressed in tumors
Authors: Huh Eunna , Gallion Jonathan , Agosto Melina A. , Wright Sara J. , Wensel Theodore G. , Lichtarge Olivier
Published: December 2021

Significance

GPCRs and GPCR pathways are increasingly being implicated in human malignancies, placing them among the most promising cancer drug candidates. Our results reveal enrichment of highly impactful, recurrent GPCR mutations within cancers. We found that cognate mutations in selected class A GPCRs have deleterious effects on signaling function. The results also suggest that olfactory receptors, often considered inconsequential, display a nonrandom mutation pattern in tumors in which they are expressed. These findings support the idea that protein paralogs can act in parallel as members of an onco-group.
Direct visualization of a static incommensurate antiferromagnetic order in Fe-doped Bi
2
Sr
2
CaCu
2
O
8+δ
Authors: Wan Siyuan , Li Huazhou , Choubey Peayush , Gu Qiangqiang , Li Han , Yang Huan , Eremin Ilya M. , Gu Genda , Wen Hai-Hu
Published: December 2021

Significance

The pairing mechanism of high-temperature superconductivity, especially in cuprates, remains as the most challenging issue in condensed matter physics. The antiferromagnetic (AF) order/correlation is supposed to be important for inducing pairing and superconductivity. In this paper, we report the observation of a static incommensurate AF order by spin-polarized scanning tunneling microscope in Fe-doped Bi2212 with a nearly optimally doped state of superconductivity. The local incommensurate AF order can be directly visualized in regions with some Fe impurities. Our measurements provide a basis to study the interplay between superconductivity and AF spin fluctuations in cuprates.
Symmetric activation and modulation of the human calcium-sensing receptor
Authors: Park Jinseo , Zuo Hao , Frangaj Aurel , Fu Ziao , Yen Laura Y. , Zhang Zhening , Mosyak Lidia , Slavkovich Vesna N. , Liu Jonathan , Ray Kimberly M. , Cao Baohua , Vallese Francesca , Geng Yong , Chen Shaoxia , Grassucci Robert , Dandey Venkata P. , Tan Yong Zi , Eng Edward , Lee Yeji , Kloss Brian , Liu Zheng , Hendrickson Wayne A. , Potter Clinton S. , Carragher Bridget , Graziano Joseph , Conigrave Arthur D. , Frank Joachim , Clarke Oliver B. , Fan Qing R.
Published: December 2021

Significance

The human calcium-sensing receptor maintains a stable concentration of calcium in the blood. Naturally occurring mutations in the receptor are linked to calcium homeostatic disorders including hypercalcemia and hypocalcemia. Modulation of the receptor function can provide therapeutic relief of these conditions. The structures of the calcium-sensing receptor in the absence and presence of various allosteric modulators reveal the mechanism by which these modifiers up- or down-regulate receptor function. We have captured symmetric forms of the homodimeric receptor both at rest and upon stimulation and concluded that receptor activation involves a conformational change at its dimer interface. The structural details of the calcium-sensing receptor in different functional states may assist the design of new therapeutics for diseases related to calcium homeostasis.
Translating (political) religious and secularist worldviews in a post-secular age
Authors: Basalamah Salah
Published: December 2021

Inspired by the works of François Burgat, Jürgen Habermas and Jean-Marc Ferry, this paper addresses the notions of the religious, the political, the radical/extreme, the conservative, the secular and the social as the objects of an extended conception of translation that defines translation as a mode of intercomprehension between competing or adversary groups within a single or among diverse societies. Shifting focus away from textual manipulations, it conceives of translation as a form of active engagement in social and discursive negotiations and explores translation as it brings about change in the dynamics of intergroup and intercultural relations.
Particle motion in circularly polarized vacuum pp waves
Authors: Zhang P M , Elbistan M , Horvathy P A
Published: December 2021

Bialynicki-Birula and Charzynski argued that a gravitational wave emitted during the merger of a black hole binary may be approximated by a circularly polarized wave which may in turn trap particles (Bialynicki-Birula and Charzynski 2018 Phys. Rev. Lett.
121 171101). In this paper we consider particle motion in a class of gravitational waves which includes, besides circularly polarized periodic waves (CPP) (Stephani et al 2003 Exact Solutions of Einstein’s Field Equations (Cambridge: Cambridge University Press)), also the one proposed by Lukash V N (1975 Sov. Phys. JETP
40 792; 1974 Zh. Eksp. Teor. Fiz.
67 1594–1608; 1974 Astr. Zh.
51 281; 1976 Nuovo Cimento B 35 208) to study anisotropic cosmological models. Both waves have a seven-parameter conformal symmetry which contains, in addition to the generic five-parameter (broken) Carroll group, also a 6th isometry. The Lukash spacetime can be transformed by a conformal rescaling of time to a perturbed CPP problem. Bounded geodesics, found both analytically and numerically, arise when the Lukash wave is of Bianchi type VI. Their symmetries can also be derived from the Lukash–CPP relation. Particle trapping is discussed.
Cauchy and Goursat problems for the generalized spin zero rest-mass equations on Minkowski spacetime
Authors: Xuan Pham Truong
Published: December 2021

In this paper, we study the Cauchy and Goursat problems of the spin-n/2 zero rest-mass equations on Minkowski spacetime by using the conformal geometric method. In our strategy, we prove the wellposedness of the Cauchy problem in Einstein’s cylinder. Then we establish pointwise decays of the fields and prove the energy equalities of the conformal fields between the null conformal boundaries

I

±

and the hypersurface

Σ

0

=

t
=
0

. Finally, we prove the wellposedness of the Goursat problem in the partial conformal compactification by using the energy equalities and the generalisation of Hörmander’s result.
Addendum: Considerations about the incompleteness of the Ehrenfest’s theorem in quantum mechanics (2021 Eur. J. Phys.
42 065405)
Authors: Giordano Domenico , Amodio Pierluigi
Published: December 2021

We describe the analytical solution of the eigenvalue problem introduced in our article mentioned in the title and relative to a punctiform electric charge confined in an one-dimensional box in the presence of an electric field. We also derive and discuss the analytical expressions of the external forces acting on the punctiform charge and associated with the boundaries of the one-dimensional box in the presence of the electric field.
The influence of a second ground electrode on hydrogen peroxide production from an atmospheric pressure argon plasma jet and correlation to antibacterial efficacy and mammalian cell cytotoxicity
Authors: Ghimire Bhagirath , Patenall Bethany L , Szili Endre J , Gaur Nishtha , Lamichhane Pradeep , Thet Naing T , Trivedi Dhruv , Jenkins Andrew Toby A , Short Robert D
Published: December 2021

This study investigates how addition of a 2nd ground electrode in an argon plasma jet influences the production of hydrogen peroxide (H2O2) in deionised water (DIW). Briefly, plasma is ignited by purging argon gas through a quartz tube at 1 l min−1 and applying a sinusoidal voltage of 7 kV (peak–peak) at 23.5 kHz to a high voltage stainless steel needle electrode sealed inside the quartz tube surrounded by one or two copper ring(s) that served as the ground electrode(s) situated downstream of the high voltage electrode. The mechanisms of H2O2 production are investigated through the electrical and optical plasma properties and chemical analysis of the treated DIW. We discover that the addition of a 2nd ground electrode results in higher accumulation of charges on the inner wall surface of the quartz tube of the plasma jet assembly resulting in an increase in the discharge current and dissipated power. This further leads to an increase in the electron temperature that more than doubles the H2O2 production through dissociative recombination of water vapour molecules, whilst still maintaining a biological tissue tolerable gas temperature. The double ground electrode plasma jet is shown to be highly effective at reducing the growth of common wound pathogens (Pseudomonas aeruginosa and Staphylococcus aureus) in both planktonic and biofilm states whilst inducing a low level of cytotoxicity in HaCaT keratinocyte skin-like cells under certain conditions. The information provided in this study is useful in understanding the complex physicochemical processes that influence H2O2 production in plasma jets, which is needed to optimise the development of plasma sources for clinical applications.
Vibrational modes and crystallographic structure of Cd3As2 and (Cd1-x
Zn
x
)3As2 epilayers
Authors: Fluegel B , Rice A D , Alberi K
Published: December 2021

Low-temperature Raman scattering is used to study the crystal structure of molecular-beam epitaxially grown layers of the Dirac semimetal Cd3As2 and its related alloy (Cd1-x
Zn
x
)3As2. The combination of narrow-linewidth spectra, multiple growth directions and full polarization analysis allows improved accuracy in identifying the irreducible representation of over 57 Raman-active vibrations. Several disagreements with previous identifications are found. Structurally, the results agree with the centrosymmetric I41/acd space group of bulk-grown Cd3As2 and are clearly distinct from the Raman spectra of nanoscale platelets and wires. Three-fold twinning is seen in (112) Cd3As2 grown on (111) zincblende substrates corresponding to the three possible tetragonal orientations. In dilute (Cd1-x
Zn
x
)3As2, phonons have a frequency and scattering amplitude dependence on Zn concentration that is continuous with Cd3As2 but at least one frequency is absent at the alloy endpoint, preventing a simple one-mode description of the alloy phonon.
Electronic structure modification in Fe-substituted β-Ga2O3 from resonant photoemission and soft x-ray absorption spectroscopies
Authors: Ghosh Sahadeb , Nand Mangla , Kamparath Rajiv , Gupta Mukul , Phase D M , Jha S N , Singh S D , Ganguli Tapas
Published: December 2021

Oriented thin films of β-(Ga1−x
Fe
x
)2O3 were deposited by radio frequency magnetron sputtering on c-Al2O3 and GaN substrates. The itinerant character of the Fe 3d states forming the top of the valence band (VB) of the Fe-substituted β-Ga2O3 thin films has been determined from resonant photoelectron spectroscopy. Further, the admixture of the itinerant and localized characters of these Fe 3d states has been obtained for larger binding energies; i.e. deeper in the VB. The bottom of the conduction band (CB) for β-(Ga1−x
Fe
x
)2O3 has been also found to have strongly hybridized states involving Fe 3d and O 2p states compared to that of Ga 4s in pristine β-Ga2O3. This suggests that β-Ga2O3 transforms from a band-like system to a charge-transfer system with Fe substitution. Furthermore, the bandgap red shifts with Fe composition, which has been found to be primarily related to the shift of the CB edge.
Recent advances in THz detectors based on semiconductor structures with quantum confinement: a review
Authors: Yachmenev A E , Khabibullin R A , Ponomarev D S
Published: December 2021

Beginning from the 1990s, an ever-lasting interest in the terahertz (THz) spectroscopy and THz instruments has produced wide progress in the development of high-speed THz detectors. The constantly growing requirements aimed at the increase of spectral resolution, sensitivity, and acquisition rate of THz detectors have attracted much attention in this field. In the present review, we summarize the most recent advances in the THz photodetectors based on semiconductor structures with quantum confinement of an electron gas. Their main advantages over existing detectors are fast response time, increased spectral resolution, and multicolor operation thanks to the variability of their designs and band structure engineering. These all allow for using them in various important applications such as single photon detection, THz heterodyne detection, continuous monitoring of toxic gases, THz free space communications and radio astronomy.
A highly stable temperature sensor based on Au/Cu/n-Si Schottky barrier diodes dependent on the inner metal thickness
Authors: Efeoğlu Hasan , Turut Abdulmecit
Published: December 2021

We have fabricated Au/n-Si (D1), Au/Cu/n-Si (D2), Au/Cu(4 nm)/n-Si (D3) and Au/Cu(2 nm)/n-Si (D4) Schottky barrier diodes (SBDs). The thickness of the Cu Schottky contact (SC) films for diodes D2, D3 and D4 was chosen as 100, 4 and 2 nm, respectively. We investigated the thermal sensitivity from the voltage–temperature (V–T) characteristics of the SBDs at different current levels. TheV–Tmeasurements were done in the temperature range from 10 to 320 K with steps of 2 K at different current levels from 50 nA to 141.70µA. TheV–Tcurves showed a good degree of linearity for all SBDs. The slope dV/dT =α(αis the thermal sensitivity coefficient) for each diode decreased with increasing current from 50 nA to 141.70µA. However, the SBDs with a Cu SC had approximately the sameαvalue independent of metal thickness at the same current level. That is, the value of the thermal sensitivity coefficient changed from approximately 2.48 mV K−1at 50 nA to 1.82 at 141.70µA for the SBDs with a Cu SC independent of metal thickness. Furthermore, theαversus current level plots of the diodes exhibited a linear behavior. The interceptα0and slope dα/dIvalues of theαversus current level plots were obtained as 2.80 mV K−1and −0.0843 mV A–1K−1for D2, and 2.85 mV K−1and −0.092 mV A–1K−1for D3 and 2.83 mV K−1and −0.0876 mV A–1K−1for D4. These values are very close to each other and the difference between the slope (dα/dI) values is small enough to be neglected.
Electronic properties of TaAs2 topological semimetal investigated by transport and ARPES
Authors: Wadge Ashutosh S , Grabecki Grzegorz , Autieri Carmine , Kowalski Bogdan J , Iwanowski Przemysław , Cuono Giuseppe , Islam M F , Canali C M , Dybko Krzysztof , Hruban Andrzej , Łusakowski Andrzej , Wojciechowski Tomasz , Diduszko Ryszard , Lynnyk Artem , Olszowska Natalia , Rosmus Marcin , Kołodziej J , Wiśniewski Andrzej
Published: December 2021

We have performed electron transport and angle-resolved photo-emission spectroscopy (ARPES) measurements on single crystals of transition metal dipnictide TaAs2 cleaved along the (

2

¯

01) surface which has the lowest cleavage energy. A Fourier transform of the Shubnikov–de Haas oscillations shows four different peaks whose angular dependence was studied with respect to the angle between magnetic field and the [

2

¯

01] direction. The results indicate elliptical shape of the Fermi surface cross-sections. Additionally, a mobility spectrum analysis was carried out, which also reveals at least four types of carriers contributing to the conductance (two kinds of electrons and two kinds of holes). ARPES spectra were taken on freshly cleaved (

2

¯

01) surface and it was found that bulk states pockets at constant energy surface are elliptical, which confirms the magnetotransport angle dependent studies. First-principles calculations support the interpretation of the experimental results. The theoretical calculations better reproduce the ARPES data if the theoretical Fermi level (FL) is increased, which is due to a small n-doping of the samples. This shifts the FL closer to the Dirac point, allowing investigating the physics of the Dirac and Weyl points, making this compound a platform for the investigation of the Dirac and Weyl points in three-dimensional materials.
In-process range-resolved interferometric (RRI) 3D layer height measurements for wire + arc additive manufacturing (WAAM)
Authors: Hallam Jonathan M , Kissinger Thomas , Charrett Thomas O H , Tatam Ralph P
Published: December 2021

In this work a range resolved interferometry (RRI) instrument for absolute distance measurements is integrated into a wire + arc additive manufacturing (WAAM) system to provide in-process monitoring of layer height, and prospects for volume and profile monitoring are discussed. In this experiment titanium feedstock was used to create a 150 mm long, 13.5 mm high wall comprised of 11 WAAM deposited layers. The RRI in-process measurements are in very good agreement (

<

0.05 mm) with both mid-process, on-machine micrometre measurements taken by hand after each WAAM deposition, and post-process laser scanning measurements of the completed wall. The high depth of field allows direct referencing of the layer height measurements to the build plate making the measurement independent of the motion system and build plate bending, considerably lowering uncertainties. This, together with the capability for cost-effective in-process measurements in harsh environments, should make the proposed approach very interesting for routine use in WAAM systems.
Design, fabrication and application of magnetically actuated micro/nanorobots: a review
Authors: Wang Zhongbao , Xu Zhenjin , Zhu Bin , Zhang Yang , Lin Jiawei , Wu Yigen , Wu Dezhi
Published: December 2021

Magnetically actuated micro/nanorobots are typical micro- and nanoscale artificial devices with favorable attributes of quick response, remote and contactless control, harmless human-machine interaction and high economic efficiency. Under external magnetic actuation strategies, they are capable of achieving elaborate manipulation and navigation in extreme biomedical environments. This review focuses on state-of-the-art progresses in design strategies, fabrication techniques and applications of magnetically actuated micro/nanorobots. Firstly, recent advances of various robot designs, including helical robots, surface walkers, ciliary robots, scaffold robots and biohybrid robots, are discussed separately. Secondly, the main progresses of common fabrication techniques are respectively introduced, and application achievements on these robots in targeted drug delivery, minimally invasive surgery and cell manipulation are also presented. Finally, a short summary is made, and the current challenges and future work for magnetically actuated micro/nanorobots are discussed.
Rare earth doped metal oxide nanoparticles for photocatalysis: a perspective
Authors: Mehtab Amir , Ahmed Jahangeer , Alshehri Saad M , Mao Yuanbing , Ahmad Tokeer
Published: December 2021

Metal oxides are well-known materials that have been considered as the prominent photocatalysts. Photocatalysis is a promising way to address the environmental issues which are caused by fossil fuel the combustion and industrial pollutants. Lot of efforts such as doping of metal oxides with metals, non-metals have been made to enhance their photocatalytic activity. More specifically, in this review we have discussed detailed synthesis procedures of rare earth doped metal oxides performed in the past decades. The advantage of doping metal oxides with rare earth metals is that they readily combine with functional groups due to the 4f vacant orbitals. Moreover, doping rare earth metals causes absorbance shift to the visible region of the electromagnetic spectrum which results to show prominent photocatalysis in this region. The effect of rare earth doping on different parameters of metal oxides such as band gap and charge carrier recombination rate has been made in great details. In perspective section, we have given a brief description about how researchers can improve the photocatalytic efficiencies of different metal oxides in coming future. The strategies and outcomes outlined in this review are expected to stimulate the search for a whole new set of rare earth doped metal oxides for efficient photocatalytic applications.
Evolution and modulation of Ag filament dynamics within memristive devices based on necklace-like Ag@TiO2 nanowire networks
Authors: Weng Zhengjin , Zhao Zhiwei , Jiang Helong , Fang Yong , Lei Wei , Liu Changsheng
Published: December 2021

Random nanowire networks (NWNs) are regarded as promising memristive materials for applications in information storage, selectors, and neuromorphic computing. The further insight to understand their resistive switching properties and conduction mechanisms is crucial to realize the full potential of random NWNs. Here, a novel planar memristive device based on necklace-like structure Ag@TiO2 NWN is reported, in which a strategy only using water to tailor the TiO2 shell on Ag core for necklace-like core–shell structure is developed to achieve uniform topology connectivity. With analyzing the influence of compliance current on resistive switching characteristics and further tracing evolution trends of resistance state during the repetitive switching cycles, two distinctive evolution trends of low resistance state failure and high resistance state failure are revealed, which bear resemblance to memory loss and consolidation in biological systems. The underlying conduction mechanisms are related to the modulation of the Ag accumulation dynamics inside the filaments at cross-point junctions within conductive paths of NWNs. An optimizing principle is then proposed to design reproducible and reliable threshold switching devices by tuning the NWN density and electrical stimulation. The optimized threshold switching devices have a high ON/OFF ratio of ∼107 with threshold voltage as low as 0.35 V. This work will provide insights into engineering random NWNs for diverse functions by modulating external excitation and optimizing NWN parameters to satisfy specific applications, transforming from neuromorphic systems to threshold switching devices as selectors.
Investigating the n = 1 and n = 2 error fields in W7-X using the newly accelerated FIELDLINES code
Authors: Engels Dion , Lazerson Samuel A , Bykov Victor , Proll Josefine H E
Published: December 2021

No fusion device can be created without some uncertainty; there is always a slight deviation from the geometric specification. These deviations can add up create a deviation of the magnetic field. This deviation is known as the (magnetic) error field. Correcting these error fields is desired as they cause asymmetries in the divertor loads and can thus cause damage to the device if they grow too large. These error fields can be defined by their toroidal (n) and poloidal number (m). The correction of the n = 1 and n = 2 fields in Wendelstein 7-X (W7-X) is investigated in this work. This investigation focuses on field line diffusion to the divertor, a proxy for divertor heat flux. Such work leverages the 25× speedup obtained through the implementation of a new particle-wall collision model. The n = 1 and n = 2 error fields of the as-built coils model of W7-X are corrected by scanning phase and amplitude of the trim and control coils. Reductions in the divertor load asymmetry by factors of four are demonstrated using error field correction. It is found that the as-built coils model has a significantly lower

m

/

n
=
1

/

1

error field than found in experiments (Bozhenkov et al 2018 Nucl. Fusion
59 026004).
Kelvin-Helmholtz instability and induced magnetic reconnection at the Earth’s magnetopause: a 3D simulation based on satellite data
Authors: Faganello M , Sisti M , Califano F , Lavraud B
Published: December 2021

A 3D two-fluid simulation, using plasma parameters as measured by MMS on 8 September 2015, shows the nonlinear development of the Kelvin–Helmholtz instability at the Earth’s magnetopause. It shows extremely rich dynamics, including the development of a complex magnetic topology, vortex merging and secondary instabilities. Vortex induced and mid-latitude magnetic reconnection coexist and produce an asymmetric distribution of magnetic reconnection events. Off-equator reconnection exhibits a predominance of events in the Southern Hemisphere during the early nonlinear phase, as observed by satellites at the dayside magnetopause. The late nonlinear phase shows the development of vortex pairing for all latitudes while secondary Kelvin–Helmholtz instability develops only in the Northern Hemisphere, leading to an enhancement of the occurrence of off-equator reconnection there. Since vortices move tailward while evolving, this suggests that reconnection events in the Northern Hemisphere should dominate at the nightside magnetopause.
The effect of magnetic island on toroidal ion temperature gradient mode instability
Authors: Zhang Guodong , Guo Weixin , Wang Lu
Published: December 2021

In this work, we have investigated the influence of magnetic island (MI) on electrostatic toroidal ion temperature gradient (ITG) mode, where the ions are described by gyro-kinetic equations including MI, and adiabatic approximation is used for electrons. The eigen-equation for short-wavelength toroidal ITG mode in Fourier-ballooning representation is derived, and the corresponding eigenvalue as well as mode structure are solved. Both the flattening effects of MI on plasma pressure and MI-scale

E
⃗

×

B
⃗

shear flow are considered. It is found that when only considering the flattening effects of MI, the ITG mode can be stabilized compared to the case without MI. Meanwhile, the effective toroidal ITG mode drive can be enhanced by including MI-scale

E
⃗

×

B
⃗

flow, which indicates the dominant destabilizing by MI-scale

E
⃗

×

B
⃗

flow over the stabilizing by flattening profile, which results in a higher growth rate than the case without MI. It is also found that the total flow shearing may prevent the ITG turbulence spreading from the X-point of MI but is not strong enough to prevent spreading from the separatrix across the O-point of larger MI via comparison between the flow shearing rate and the linear growth rate. Furthermore, the corresponding width of the lowest-order mode structure in the ballooning angle is slightly widened (narrowed) for the case without (with) MI-scale

E
⃗

×

B
⃗

flow, compared to the case without MI. Moreover, the shifted even symmetry in the ballooning angle is not qualitatively influenced by the presence of MI. The mode structure is radially asymmetric but is symmetric with respect to the phase of MI at the O-point.
Low-energy electron beam generation in inductively coupled plasma via a DC biased grid
Authors: Jung Jiwon , Lee Moo-Young , Hwang Jae-Gu , Lee Moo-Hyun , Kim Min-Seok , Lee Jaewon , Chung Chin-Wook
Published: December 2021

Low-energy electron beam generation using a DC biased grid was investigated in an inductively coupled plasma (ICP). The electron beam was measured in argon gas at various pressures, ICP source powers, and substrate voltages (V
sub). At a low ICP source power (50 W), an electron beam was generated even at small values of V
sub (10 V), however at a high ICP source power (200 W), an electron beam was only generated when a higher voltage (30 V) was applied due to the short sheath thickness on the grid surface. The sheath on the grid surface is an important factor for generating electron beams because low-energy electrons are blocked. If the sheath thickness to small, a high voltage should be applied to generate an electron beam, as accelerate regions cannot exist without the sheath. At high pressure, since electrons experience numerous neutral collisions, a high substrate voltage is needed to generate an electron beam. However, if the applied substrate voltage becomes too high (40 V) at high pressure, high-energy electrons result in secondary plasma under the grid. Therefore, maintaining a low pressure and low ICP source power is important for generating electron beams.
Three-dimensional tomographically reconstructed optical emission profiles of Hall thruster plasmas
Authors: Kim Jinwoo , Lee Dongho , Doh Guentae , Park Sanghoo , Kim Holak , Choe Wonho
Published: December 2021

A diagnostic system was developed for spectrally resolved, three-dimensional tomographic reconstruction of Hall thruster plasmas, and local intensity profiles of Xe I and Xe II emissions were reconstructed. In this diagnostic system, 28 virtual cameras were generated using a single, fixed charge-coupled device camera by rotating the Hall thruster to form a sufficient number of lines of sight. The Phillips–Tikhonov regularization algorithm was used to reconstruct local emission profiles from the line-integrated emission signals. The reconstruction performance was evaluated using both azimuthally symmetric and asymmetric synthetic phantom images including 5% Gaussian white noise, which resulted in a root-mean-square error of the reconstruction within an order of 10−3 even for a 1% difference in the azimuthal intensity distribution. Using the developed system, three-dimensional local profiles of Xe II emission (541.9 nm) from radiative decay of the excited state 5p4(3P2)6p2[3]°5/2 and Xe I emission (881.9 nm) from 5p5(2P°3/2)6p2[5/2]3 were obtained, and two different shapes were found depending on the wavelength and the distance from the thruster exit plane. In particular, a stretched central jet structure was distinctively observed in the Xe II emission profile beyond 10 mm from the thruster exit, while gradual broadening was found in the Xe I emission. Approximately 10% azimuthal nonuniformities were observed in the local Xe I and Xe II intensity profiles in the near-plume region (<10 mm), which could not be quantitatively distinguished by analysis of the frontal photographic image. Three-dimensional Xe I and Xe II intensity profiles were also obtained in the plume region, and the differences in the structures of both emissions were visually confirmed.
Study of ion separation mechanism in the multi-component vacuum arc discharge
Authors: Sun Qiang , Zhou Qianhong , Zhang Hantian , Yang Wei , Dong Ye , Song Mengmeng
Published: December 2021

The separation phenomenon of light and heavy ions was widely observed experimentally in the vacuum arc discharge with multi-component composite cathode. In this work, a two-dimensional axisymmetric multi-fluid model is used to study the separation mechanism in the multi-component composite cathode vacuum arc. The multi-component vacuum arcs are simulated as a whole which includes separate cathode spot jets, the mixing region, and common arc column. The results show that the plasma jets originated from the separate cathode spot mix together to form a common arc column after a certain distance from the cathode. Due to the rapid increase of ion temperature dozens of times in mixing region of cathode spot jet, the effect of pressure gradient becomes far greater than that of the collisions between light and heavy ions. This leads to a shift in the predominant ion motion mechanism from ion–ion collision (single cathode spot jet region) to pressure expansion (the mixing region). Finally, the light ions gain higher velocities under pressure expansion. In addition, the effect of thermal conductivity and viscosity leads to the wider high temperature regions for light ions, thus making a wider distribution of corresponding ion flux. The numerical results are qualitatively consistent with the experimental results. This paper provides an insight into ion separation mechanism in the multi-component vacuum arc.
Transient behavior of drift and ionization in atmospheric pressure nitrogen discharge
Authors: Dhali S K
Published: December 2021

The fluid models are frequently used to describe a non-thermal plasma such as a streamer discharge. The required electron transport data and rate coefficients for the fluid model are parametrized using the local field approximation (LFA) in first order models and the local-mean-energy approximation (LMEA) in second order models. We performed Monte Carlo simulations in Nitrogen gas with step changes in the E/N (reduced electric field) to study the behavior of the transport properties in the transient phase. During the transient phase of the simulation, we extract the instantaneous electron mean energy, which is different from the steady state mean electron energy, and the corresponding transport parameters and rate coefficients. Our results indicate that the mean electron energy is not a suitable parameter for mobility/drift of electrons due to big difference in momentum relaxation and energy relaxation. However, the high energy threshold rates such as ionization show a strong correlation to mean electron energy. In second order models where the energy-balance equation is solved, we suggest that it would rather be appropriate to use the local electric field to find electron drift velocity in gases such as Nitrogen and the local mean electron energy to determine the ionization and excitation rates.
Design and modelling tools for DC HTS cables for the future railway network in France
Authors: Hajiri Gabriel , Berger Kévin , Dorget Rémi , Lévêque Jean , Caron Hervé
Published: December 2021

The use of high-temperature superconducting (HTS) cables in power systems increases the transmission capacity, whereas reducing the volume of the installation. In addition, in high current applications, HTS cables considerably reduce power losses, right-of-ways and total system mass. This paper presents different multi-physics studies to be performed to accurately design the direct current (DC) HTS cables for the future railway network planned by the French company SNCF. The process used to design DC cables for high operating current (between 5 kA and 20 kA at 1750 V) made of commercial (RE)BaCuO tapes is presented. In this design process, the critical current density dependence J
c(B, θ, T) of the superconducting tapes, the thermal properties of the materials used as well as different cable cooling configurations are considered. Finally, we discuss the selection of the appropriate cooling configuration to ensure adequate cooling of the cable.
Spontaneous trail formation in populations of auto-chemotactic walkers
Authors: Mokhtari Zahra , Patterson Robert I A , Höfling Felix
Published: December 2021

We study the formation of trails in populations of self-propelled agents that make oriented deposits of pheromones and also sense such deposits to which they then respond with gradual changes of their direction of motion. Based on extensive off-lattice computer simulations aiming at the scale of insects, e.g. ants, we identify a number of emerging stationary patterns and obtain qualitatively the non-equilibrium state diagram of the model, spanned by the strength of the agent–pheromone interaction and the number density of the population. In particular, we demonstrate the spontaneous formation of persistent, macroscopic trails, and highlight some behaviour that is consistent with a dynamic phase transition. This includes a characterisation of the mass of system-spanning trails as a potential order parameter. We also propose a dynamic model for a few macroscopic observables, including the sub-population size of trail-following agents, which captures the early phase of trail formation.
Quantum batteries at the verge of a phase transition
Authors: Barra Felipe , Hovhannisyan Karen V , Imparato Alberto
Published: December 2021

Starting from the observation that the reduced state of a system strongly coupled to a bath is, in general, an athermal state, we introduce and study a cyclic battery–charger quantum device that is in thermal equilibrium, or in a ground state, during the charge storing stage. The cycle has four stages: the equilibrium storage stage is interrupted by disconnecting the battery from the charger, then work is extracted from the battery, and then the battery is reconnected with the charger; finally, the system is brought back to equilibrium. At no point during the cycle are the battery–charger correlations artificially erased. We study the case where the battery and charger together comprise a spin-1/2 Ising chain, and show that the main characteristics—the extracted energy and the thermodynamic efficiency—can be enhanced by operating the cycle close to the quantum phase transition point. When the battery is just a single spin, we find that the output work and efficiency show a scaling behavior at criticality and derive the corresponding critical exponents. Due to always present correlations between the battery and the charger, operations that are equivalent from the perspective of the battery can entail different energetic costs for switching the battery–charger coupling. This happens only when the coupling term does not commute with the battery’s bare Hamiltonian, and we use this purely quantum leverage to further optimize the performance of the device.
Assessment of weak-coupling approximations on a driven two-level system under dissipation
Authors: Teixeira W S , Semião F L , Tuorila J , Möttönen M
Published: December 2021

The standard weak-coupling approximations associated to open quantum systems have been extensively used in the description of a two-level quantum system, qubit, subjected to relatively weak dissipation compared with the qubit frequency. However, recent progress in the experimental implementations of controlled quantum systems with increased levels of on-demand engineered dissipation has motivated precision studies in parameter regimes that question the validity of the approximations, especially in the presence of time-dependent drive fields. In this paper, we address the precision of weak-coupling approximations by studying a driven qubit through the numerically exact and non-perturbative method known as the stochastic Liouville–von Neumann equation with dissipation. By considering weak drive fields and a cold Ohmic environment with a high cutoff frequency, we use the Markovian Lindblad master equation as a point of comparison for the SLED method and study the influence of the bath-induced energy shift on the qubit dynamics. We also propose a metric that may be used in experiments to map the regime of validity of the Lindblad equation in predicting the steady state of the driven qubit. In addition, we study signatures of the well-known Mollow triplet and observe its meltdown owing to dissipation in an experimentally feasible parameter regime of circuit electrodynamics. Besides shedding light on the practical limitations of the Lindblad equation, we expect our results to inspire future experimental research on engineered open quantum systems, the accurate modeling of which may benefit from non-perturbative methods.