bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinicolaboratory Profile, Treatment, Intensive Care Needs, and Outcome of Pediatric Inflammatory Multisystem Syndrome Temporally Associated with SARS-CoV-2: A Systematic Review and Meta-analysis
Authors: Williams Vijai , Dash Nabaneeta , Suthar Renu , Mohandoss Vichithra , Jaiswal Nishant , Kavitha T.K. , Nallasamy Karthi , Angurana Suresh Kumar
Published: November 2020

This study was aimed to summarize the current data on clinicolaboratory features, treatment, intensive care needs, and outcome of pediatric inflammatory multisystem syndrome temporally associated with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2; PIMS-TS) or multisystem inflammatory syndrome in children (MIS-C). Articles published in PubMed, Web of Science, Scopus, Google Scholar, and novel coronavirus disease 2019 (COVID-19) research database of World Health Organization (WHO), Centers for Disease Control and Prevention (CDC) database, and Cochrane COVID-19 study register between December 1, 2019 and July 10, 2020. Observational studies involving patients <21 years with PIMS-TS or MIS-C were reported the clinicolaboratory features, treatment, intensive care needs, and outcome. The search identified 422 citations and finally 18 studies with 833 participants that were included in this study, and pooled estimate was calculated for parameters of interest utilizing random effect model. The median age was 9 (range: 8–11) years. Fever, gastrointestinal symptoms, rash, conjunctival injection, and respiratory symptoms were common clinical features. Majority (84%) had positive SARS-CoV-2 antibody test and only one-third had positive reverse transcript polymerase chain reaction (RT-PCR). The most common laboratory abnormalities noted were elevated C-reactive protein (CRP), D-dimer, procalcitonin, brain natriuretic peptide (BNP), fibrinogen, ferritin, troponin, interleukin 6 (IL-6), lymphopenia, hypoalbuminemia, and thrombocytopenia. Cardiovascular complications included shock (65%), myocardial dysfunction (61%), myocarditis (65%), and coronary artery abnormalities (39%). Three-fourths of children required admission to pediatric intensive care unit (PICU) where they received vasoactive medications (61%) and mechanical ventilation (25%). Treatment strategies used included intravenous immunoglobulin (IVIg; 82%), steroids (54%), antiplatelet drugs (64%), and anticoagulation (51%). Mortality for patients with PIMS-TS or MIS-C was low (n = 13). In this systematic review, we highlight key clinical features, laboratory findings, therapeutic strategies, intensive care needs, and observed outcomes for patients with PIMS-TS or MIS-C. Commonly observed clinical manifestations include fever, gastrointestinal symptoms, mucocutaneous findings, cardiac dysfunction, shock, and evidence of hyperinflammation. The majority of children required PICU admission, received immunomodulatory treatment, and had good outcome with low mortality.
Fragile X Syndrome and Periventricular Heterotopias: A Rare Association
Authors: Bidstrup Jakob , Hansen Jonas Kjeldbjerg
Published: November 2020

Fragile X syndrome (FXS) is the most common hereditary cause of intellectual disability in males, with an estimated prevalence of 1:4000. Epilepsy occurs in 10 to 20% of males with FXS and usually has a favorable prognosis and positive response to antiepileptic medication. Numerous anomalies in the central nervous system have been reported in FXS. Among these, periventricular heterotopia (PH) has been reported in two previous cases. Epilepsy is also a common comorbidity in PH, but in contrast to epilepsy in FXS, the severity may vary markedly. We present a boy with FXS, PH, and epilepsy—a combination not previously reported in the literature. The presented case suggests a necessity to consider PH in cases of refractory epilepsy or status epilepticus in patients with FXS, emphasizes the importance of ruling out FXS in children with intellectual disability even if there are only discreet or no clinical signs of the disorder, and underscores that FXS should be considered in patients with PH if no other cause can be found.
Mosaic Trisomy 5: Prenatal Genetic Diagnosis and Outcomes of a New Case
Authors: Sánchez-Herrero Ángeles , Carmona-Talavera Diego , García-Verdevio M Elia , Hernando-Espinilla Amaya , Estañ-Capell Nuria
Published: November 2020

Chromosomal mosaicism is defined as the presence of two or more different cell lines in an organism that originate from the same embryo. Trisomy of chromosome 5 is one of the most severe forms of autosomal trisomy and only seven cases of mosaic trisomy 5 have been reported to date. Mosaicism at prenatal level constitutes a challenge in genetic counseling, particularly in the case of mosaic trisomy 5, due to its low incidence. We report the case of a girl with a prenatal diagnosis of mosaic trisomy 5. The pre- and postnatal genetic tests (noninvasive prenatal testing, array comparative genomic hybridization, karyotype in amniotic fluid cells, karyotype in peripheral blood, and uniparental disomy analysis) revealed the fetal chromosomal status and indicated etiology giving rise to the mosaicism, suggesting a prezygotic meiotic error corrected through late trisomic rescue in the zygote.
The shape – or structure – of water
Authors: Bandari Anashe
Published: November 2020

The interactions of water molecules with one another are difficult to observe experimentally, but important for understanding biological processes.
Plasma polymerization of TEMPO shows promise
Authors: Larter Raima
Published: November 2020

A combination of high pressure and low power in plasma polymerization of a monomer containing NO-like functional groups can produce well-controlled films.
Modulation of ROS in nanosecond-pulsed plasma-activated media for dosage-dependent cancer cell inactivation in vitro
Authors: Jiang C. , Sözer E. B. , Song S. , Lai N. , Vernier P. T. , Guo S.
Published: November 2020

Dosage control of reactive oxygen and nitrogen species (RONS) is critical to low-temperature plasma applications in cancer therapy. Production of RONS by atmospheric pressure, nonequilibrium plasmas in contact with liquid may be modulated via plasma conditions including plasma treatment time and pulse voltage and repetition frequency. In this study, a terephthalic acid-based probe was used to measure hydroxyl radicals [OH(aq)] in water exposed to plasma and to demonstrate that the OH(aq) concentration increases linearly with treatment time. Fluorometric measurements of hydrogen peroxide concentration in plasma-activated water show a linear relationship between the H2O2 production rate and the pulse repetition frequency of the plasma. In vitro plasma treatment of cancer cells shows that pancreatic (Pan02) and breast (4T1-Luc) cancer cells have different sensitivities to plasma exposure. The dependence of Pan02 cell viability on plasma treatment time or pulse voltage is nonlinear. The system described here for generation and delivery of reactive oxygen species from a nanosecond pulsed plasma jet represents a promising alternative approach to cancer therapy.
Topological insulator nanoribbon Josephson junctions: Evidence for size effects in transport properties
Authors: Kunakova Gunta , Surendran Ananthu P. , Montemurro Domenico , Salvato Matteo , Golubev Dmitry , Andzane Jana , Erts Donats , Bauch Thilo , Lombardi Floriana
Published: November 2020

We have used Bi2Se3 nanoribbons, grown by catalyst-free physical vapor deposition to fabricate high quality Josephson junctions with Al superconducting electrodes. In our devices, we observe a pronounced reduction of the Josephson critical current density Jc by reducing the width of the junction, which in our case corresponds to the width of the nanoribbon. Because the topological surface states extend over the entire circumference of the nanoribbon, the superconducting transport associated with them is carried by modes on both the top and bottom surfaces of the nanoribbon. We show that the Jc reduction as a function of the nanoribbon width can be accounted for by assuming that only the modes traveling on the top surface contribute to the Josephson transport as we derive by geometrical consideration. This finding is of great relevance for topological quantum circuitry schemes since it indicates that the Josephson current is mainly carried by the topological surface states.
Numerical scheme for evaluating the collision integrals for triple interactions in relativistic plasma
Authors: Prakapenia M. A. , Siutsou I. A. , Vereshchagin G. V.
Published: November 2020

Binary interactions in relativistic plasma, such as Coulomb and Compton scattering as well as pair creation and annihilation are well known and studied in detail. Triple interactions, namely, relativistic bremsstrahlung, double Compton scattering, radiative pair production, and triple pair production and their inverse processes, are usually considered as emission processes in astrophysical problems, as well as in laboratory plasmas. Their role in plasma kinetics is fundamental [A. G. Aksenov et al., Phys. Rev. Lett. 99, 125003 (2007)]. We present a new conservative scheme for computation of the Uehling–Uhlenbeck collision integral for all triple interactions in relativistic plasma based on direct integration of exact QED matrix elements. Reaction rates for thermal distributions are compared, where possible, with the corresponding analytic expressions, showing good agreement. Our results are relevant for quantitative description of relativistic plasmas out of equilibrium, both under astrophysical and laboratory conditions.
Determining the radial distribution function of water using electron scattering: A key to solution phase chemistry
Authors: de Kock M. B. , Azim S. , Kassier G. H. , Miller R. J. D.
Published: November 2020

High energy electron scattering of liquid water (H2O) at near-ambient temperature and pressure was performed in a transmission electron microscope (TEM) to determine the radial distribution of water, which provides information on intra- and intermolecular spatial correlations. A recently developed environmental liquid cell enables formation of a stable water layer, the thickness of which is readily controlled by pressure and flow rate adjustments of a humid air stream passing between two silicon nitride (Si3N4) membranes. The analysis of the scattering data is adapted from the x-ray methodology to account for multiple scattering in the H2O:Si3N4 sandwich layer. For the H2O layer, we obtain oxygen–oxygen (O–O) and oxygen–hydrogen (O–H) peaks at 2.84 Å and 1.83 Å, respectively, in good agreement with values in the literature. This demonstrates the potential of our approach toward future studies of water-based physics and chemistry in TEMs or electron probes of structural dynamics.
Progress and perspective on polymer templating of multifunctional oxide nanostructures
Authors: Xu Jin , Berg Alexandra I. , Noheda Beatriz , Loos Katja
Published: November 2020

Metal oxides are of much interest in a large number of applications, ranging from microelectronics to catalysis, for which reducing the dimensions to the nanoscale is demanded. For many of these applications, the nano-materials need to be arranged in an orderly fashion on a substrate. A typical approach is patterning thin films using lithography, but in the case of functional oxides, this is restricted to sizes down to about 100 nm due to the structural damage caused at the boundaries of the material during processing having a strong impact on the properties. In addition, for applications in which multifunctional or hybrid materials are requested, as in the case of multiferroic composites, standard top-down methods are inadequate. Here, we evaluate different approaches suitable to obtain large areas of ordered nano-sized structures and nanocomposites, with a particular focus on the literature of multiferroic nanocomposites, and we highlight the polymer-templating method as a promising low-cost alternative.
Leidenfrost drop impact on inclined superheated substrates
Authors: Wang Yujie , El Bouhali Ayoub , Lyu Sijia , Yu Lu , Hao Yue , Zuo Zhigang , Liu Shuhong , Sun Chao
Published: November 2020

In real applications, drops always impact on solid walls with various inclinations. For the oblique impact of a Leidenfrost drop, which has a vapor layer under its bottom surface to prevent its direct contact with the superheated substrate, the drop can nearly frictionlessly slide along the substrate accompanied by spreading and retracting. To individually study these processes, we experimentally observe the impact of ethanol drops on superheated inclined substrates using high-speed imaging from two different views synchronously. We first study the dynamic Leidenfrost temperature, which mainly depends on the normal Weber number We⊥. Then, the substrate temperature is set to be high enough to study the Leidenfrost drop behavior. During the spreading process, drops are always kept uniform, and the maximum spreading factor Dm/D0 follows a power-law dependence on the large normal Weber number We⊥ as Dm/D0=We⊥/12+2 for We⊥ ≥ 30. During the retracting process, drops with low impact velocities become non-uniform due to the gravity effect. For the sliding process, the residence time of all studied drops is nearly a constant, which is not affected by the inclination and the We number. The frictionless vapor layer resulting in the dimensionless sliding distance L/D0 follows a power-law dependence on the parallel Weber number We|| as L/D0∝We||1/2. Without direct contact with the substrate, the behaviors of drops can be separately determined by We⊥ and We||. When the impact velocity is too high, the drop fragments into many tiny droplets, which is called the splashing phenomenon. The critical splashing criterion is found to be We⊥*≃ 120 or K⊥=We⊥Re⊥1/2≃ 5300 in the current parameter regime.
Solitary states in the mean-field limit
Authors: Kruk N. , Maistrenko Y. , Koeppl H.
Published: November 2020

We study active matter systems where the orientational dynamics of underlying self-propelled particles obey second-order equations. By primarily concentrating on a spatially homogeneous setup for particle distribution, our analysis combines theories of active matter and oscillatory networks. For such systems, we analyze the appearance of solitary states via a homoclinic bifurcation as a mechanism of the frequency clustering. By introducing noise, we establish a stochastic version of solitary states and derive the mean-field limit described by a partial differential equation for a one-particle probability density function, which one might call the continuum Kuramoto model with inertia and noise. By studying this limit, we establish second-order phase transitions between polar order and disorder. The combination of both analytical and numerical approaches in our study demonstrates an excellent qualitative agreement between mean-field and finite-size models.
‘It is just part of life’: patient perspectives and experiences of diagnostic imaging referrals
Authors: Makanjee Chandra Rekha , Xu Deon , Sarswat Drishti , Bergh Anne-Marie
Published: November 2020

Referral for a medical imaging examination is an integral part of the medical consultation; however, not much is known about patients’ experience of these referrals. The life-world experiences and perspectives of patients as ‘persons’ referred for an imaging investigation are explored through the lens of person-centred and whole-person care. Individual interviews were conducted with 22 patients referred for an imaging investigation. The findings were interpreted in terms of the journey of a patient; that is, the processes the patient undergoes as a person in the course of a referral for a diagnostic imaging investigation as part of the disease and its treatment. Participants’ life and health journeys are described in terms of three themes: (1) events leading to an imaging examination; (2) the imaging referral experience embedded within the medical encounter; and (3) the integration of the findings of the imaging examination into their everyday life. Health practitioners should be mindful of the complexity of medical consultations that include a referral for an imaging investigation.
Dogmatism manifests in lowered information search under uncertainty
Authors: Schulz Lion , Rollwage Max , Dolan Raymond J. , Fleming Stephen M.
Published: November 2020

Significance

Dogmatic individuals are reluctant to seek out new information to refine their views, often skewing political, scientific, and religious discourse in the process. The cognitive drivers of this reluctance are poorly understood. Here, we isolate an influence of uncertainty on information search using a low-level perceptual decision-making task. We show that people with dogmatic views are both less likely to seek information before committing to a decision and to use fluctuations in uncertainty to guide their search. Our results highlight a cognitive mechanism that may contribute to the formation of dogmatic worldviews.
Motion analysis of kinetic impact projectiles for physics education in real context
Authors: Hernández Carla , Echiburu Mauricio , Humire Fernando , Mosso Edward
Published: November 2020

The article presents a proposal to contextualize the study of movement in introductory courses of university physics, as a contribution to decision making in social situations. For this, the use of kinetic impact projectiles and the actual data provided by official sources are considered. This information is used in an object motion model describing the kinematic characteristics of a spherical projectile (a rubber bullet). For these purposes, a Reynolds number Re ≫ 1 was used, which allows one to apply a nonlinear motion equation to find the velocity and impact energy per unit area of a projectile. The results and analysis of this model can generate an interesting discussion in the classroom about the need to build protocols for the use of kinetic impact projectiles, and the importance of using scientific knowledge in social conflicts.
A mathematical model of the velocity of a cyclist riding over uneven terrain
Authors: D’Alessio Serge
Published: November 2020

Derived in this article is a mathematical model of a cyclist riding over uneven terrain. The model is very general; it is expressed in terms of arbitrary functions that describe how the elevation changes with horizontal distance and how the cyclist’s power output varies, and also accounts for road friction and air resistance. The model was validated by considering special cases such as horizontal and inclined surfaces. Although the governing equation is too complicated to solve exactly for the general case, a numerical solution procedure is proposed and tested. In addition, an approximate analytical solution procedure is outlined. As an illustration some numerical results are presented for the case of a cyclist riding over rolling hills. The adopted approach is well suited for undergraduate students in mathematical physics. The formulation equally applies to a vehicle driving over a variable landscape. This work also unites concepts from physics with mathematical modelling and coding. Lastly, a video abstract is also provided.
Modeling as sensemaking: towards a theory of modelling in physics education
Authors: Sands David
Published: November 2020

Drawing on psychological evidence in problem solving and reasoning, a theory of modelling in physics is advanced. Modelling is framed as a process of making sense of the physical world. The sensemaking process is identified as having at least three distinct stages: making sense of the problem, making sure that the model makes sense, and finally, making sense of the physical world using the model. Key to first stage is the construction of a qualitative mental model. Evidence is cited from the psychological literature in favour of mental modelling as the primary mechanism by which humans reason. The second stage requires the qualitative ideas and relationships contained in the mental model be expressed mathematically so that the validity of the model can be tested in limiting cases and particular circumstances. The last stage involves testing the explanatory and predictive power of the model against known phenomena. The entire process is based on the creation of different representations and their consistent translation across the different stages of the modelling process. It is shown how these ideas can be incorporated into teaching and examples of teaching practices based on these ideas are given.
Perspectives of spin-textured ferroelectrics
Authors: Tao L L , Tsymbal Evgeny Y
Published: November 2020

Spin–orbit coupling (SOC) links the spin degree of freedom to the orbital motion of electrons in a solid and plays an important role in the emergence of new physical phenomena. In non-centrosymmetric materials, the SOC locks the electron’s spin direction to its momentum resulting in non-trivial spin textures in the reciprocal space. Depending on the crystal symmetry, the spin texture may exhibit Rashba, Dresselhaus, persistent, or more intricate configurations. In ferroelectric materials these spin textures are coupled to the ferroelectric polarization and thus can be controlled by its orientation and magnitude. This provides a promising platform to explore the coupling between spin, orbital, valley, and lattice degrees of freedoms in solids and opens a new direction for nonvolatile spintronic devices, such as a spin-ﬁeld-effect transistor and a valley spin valve. Here, we review the recent advances in spin-texture physics of ferroelectric materials and outline possible device implications.
Comment on ‘Understanding the behaviour of pulsed laser dry and wet micromachining processes by multi-phase smoothed particle hydrodynamics (SPH) modeling’
Authors: Jiang Wu-Gui , Zheng Pan , Liao Shu-Mei , Lv Hui
Published: November 2020

The paper ‘Understanding the behaviour of pulsed laser dry and wet micromachining processes by multi-phase smoothed particle hydrodynamics (SPH) modeling’ by Muhammad et al published in 2013 J. Phys. D: Appl. Phys. 46 095101, laid the foundation for SPH simulation of laser melting process including welding and selective laser melting. However, there are some inaccurate or inappropriate mathematical descriptions about the energy conservation in the paper, which may mislead some careless readers and cause unnecessary waste of time. In this paper, some comments and clarifications on the errors are made. By correcting these errors, a deeper understanding on the energy transport during the laser melting processes can also be obtained.
Field emission from two-dimensional GeAs
Authors: Di Bartolomeo Antonio , Grillo Alessandro , Giubileo Filippo , Camilli Luca , Sun Jianbo , Capista Daniele , Passacantando Maurizio
Published: November 2020

GeAs is a layered material of the IV–V groups that is attracting growing attention for possible applications in electronic and optoelectronic devices. In this study, exfoliated multilayer GeAs nanoflakes are structurally characterized and used as the channel of back-gate field-effect transistors. It is shown that their gate-modulated p-type conduction is decreased by exposure to light or electron beam. Moreover, the observation of a field emission (FE) current demonstrates the suitability of GeAs nanoflakes as cold cathodes for electron emission and opens up new perspective applications of two-dimensional GeAs in vacuum electronics. FE occurs with a turn-on field of ∼80

V

μ

m

−
1

and attains a current density higher than 10

A

c

m

−

2

, following the general Fowler–Nordheim model with high reproducibility.
Interactions between atmospheric pressure plasmas and metallic catalyst particles in packed bed reactors
Authors: Kruszelnicki Juliusz , Engeling Kenneth W , Foster John E , Kushner Mark J
Published: November 2020

Atmospheric-pressure plasmas sustained in packed bed reactors (PBRs) are being investigated for chemical conversion of gases and pollution control. Metallic catalysts added to the surfaces of the dielectric beads of PBRs can increase the energy efficiency and selectivity of chemical processes by reducing operating temperature and providing additional reaction pathways. In this paper, results from a computational investigation of plasma surface interactions between micron-scale metallic catalysts and humid-air plasmas in PBRs are discussed. We found that high plasma density regions form in the proximity of the metallic catalysts. These higher-density plasma regions were confirmed experimentally using ICCD imaging. The intense plasmas result from geometrical electric field enhancement and redistribution of charges within the conductive particles, leading to further enhancement. The high electric field at the triple points of the catalysts can produce electric field emission of electrons, which provides a pre-ionization source or additional source of electrons. These regions of high electric field and sources of electrons guide discharges towards the catalysts and increases fluxes of excited species, ions, electrons and photons to their surfaces. These fluxes are focused primarily at the triple points between the metal, dielectric and gas. As a result, the catalyst is locally heated, which could lead to further increased rates of thermocatalytic reactions on the surface. Surface roughness of the metal inclusions can lead to additional electric field enhancement, which changes the character of the discharges in the vicinity of the catalysts while reducing breakdown voltage.
Structural tuning for enhanced magnetic performance by Y substitution in FeB-based metallic glasses
Authors: Shan Guangcun , Li Xin , Tan Haoyi , Shek Chan-Hung , Zhang Jiliang
Published: November 2020

Despite the compositional analogue to Fe71B17(NbYZr)12 metallic glass, the Fe71B17Y12 metallic glass has a saturated magnetization of Ca 108 emu g−1, more than 5 times of that in Fe71B17(NbYZr)12 (20 emu g−1). The structural origin for such significant difference in magnetic performance was investigated by x-ray absorption fine structure spectra and ab initio molecular dynamics (AIMD) simulations including simulated pair-correlation function (PCF) and Voronoi tessellation. Based on the Heisenberg model of magnetism, the narrow distribution of Fe–Fe bonds with larger distances accounts for a large Fe moment of 2.0 μ
B in Fe71B17Y12, while the broad distribution of Fe–Fe bonds leads to ferrimagnetic couplings which result in the small net Fe moment of 0.45 μ
B in Fe71B17(NbYZr)12. This work emphasizes how the substitution of analogous 4d transition metals induces a significantly different magnetism, which sheds lights on the development of new magnetic metallic glasses with both a promising magnetic performance and larger glass forming ability.
Indirect exchange interaction between magnetic impurities in one-dimensional gapped helical states
Authors: Hosseini Mir Vahid , Karimi Zahra , Davoodi Jamal
Published: November 2020

We investigate theoretically indirect exchange interaction between magnetic impurities mediated by one-dimensional gapped helical states. Such states, containing massive Dirac fermions, may be realized on the edge of a two-dimensional topological insulator when time-reversal symmetry is weakly broken. We find that the indirect exchange interaction consists of Heisenberg, Dzyaloshinsky–Moriya, in-plane and out-of-plane Ising terms. These terms decay exponentially when the Fermi level lies inside the bandgap whereas the Dzyaloshinsky–Moriya term has smallest amplitude. Outside the bandgap, the massive helical states modify oscillatory behaviors of the range functions so that the period of oscillations decreases near the edge of band in terms of energy gap or Fermi energy. In addition, the out-of-plane Ising term vanishes in the case of zero-gap structure. Also, the oscillation amplitude of out-of-plane Ising term increases versus energy gap but it decreases as a function of Fermi energy. While the oscillation amplitudes of other components remain constant as functions of energy gap and Fermi energy. Analytical results are also obtained for subgap and over gap regimes. Furthermore, the effects of electron–electron interactions are analyzed.
3D-design-model-assisted shiny surface shape measurement in fringe projection profilometry
Authors: Zhao Xiaxia , Mo Rong , Chang Zhiyong , Dong Jieshi
Published: November 2020

In fringe projection three-dimensional (3D) shape measurement, image saturation is an important influencing factor for shiny surfaces, for example, an aero-engine blade. This paper proposes a novel method assisted by the 3D design model to resolve image saturation. The proposed algorithm has the following characteristics: (a) Based on the high matching between the measured finished object and its 3D design model, the design model is transformed into the discrete point cloud with sufficient accuracy. (b) Based on the spatial coordinate transformation principle, a multi-coordinate system transformation method is proposed to convert discrete point cloud data from the design coordinate system to the world coordinate system. (c) Considering the influence of the actual measurement conditions on the measured object, the existing illumination model is improved by integrating the system’s greyscale nonlinear response, camera exposure time and sensitivity. (d) Combined with the captured grating images and the 3D design model, the parameters are accurately calibrated by the least-squares algorithm. (e) Using the calibrated reflection model, the optimal rotation angle is determined to compensate for the spatial points corresponding to the image saturation area, and finally, the entire measured surface is registered with point clouds in the calculated optimal rotation locations. Our method is used in the actual pressure surface measurement experiment. The experimental results show that our method can effectively measure the space points corresponding to the image saturation area in the optimal rotation angle and improve the measurement accuracy of shiny surfaces.
Highly efficient and blue-emitting CsPbBr3 quantum dots synthesized by two-step supersaturated recrystallization
Authors: Shu Bowang , Chang Yajing , Xu Enze , Yang Supeng , Zhang Jinhua , Jiang Yang , Cheng Xiaopeng , Yu Dabin
Published: November 2020

Highly efficient and blue-emitting CsPbBr3 quantum dots were successfully synthesized by two-step supersaturated recrystallization under ambient condition. This method could control the particle size within 2.8 nm, thus resulting in strong quantum confinement effect of the products. The as-synthesized CsPbBr3 quantum dots presented outstanding optical properties with highest photo-luminescence quantum yield of 87.20% and longest PL lifetime of 12.24 ns. The blue light-emitting diode made from the CsPbBr3 quantum dots exhibited a CIE coordinate (0.14, 0.10), in good agreement with the standard blue CIE coordinate (0.14, 0.08) of National Television System Committee (NTSC).
Designing complex radial heterostructures of Te/Bi2Te3 and Te/Bi2-x
Pb
x
Te3 nanowires: fundamental mechanistic insights into nanowire growth and evolution
Authors: Chatterjee Dipanwita , Kumar Abinash , B Pavithra , N Ravishankar
Published: November 2020

Metal telluride/Te heterostructure nanowires are important thermoelectric materials and it is important to be able to tune these materials according to the requirement of the application. In order to do so, a good understanding of the reaction mechanism and critical observation of the evolution of the nanowire heterostructure during the course of reaction is essential. Here, single crystalline, anisotropic Te core/Bi2Te3 shell nanowires have been synthesized by a facile template-based wet chemical synthesis method. The formation and evolution mechanism of the heterostructure has been elucidated by several control reactions, detailed transmission electron microscopy imaging and composition analysis using energy dispersive spectroscopy in scanning transmission electron microscopy mode of the products of the reactions. Fundamental understanding of the formation mechanism and time-dependent evolution of the core–shell structure in the nanowire have led to successful designing of higher order heterostructures involving Te/Bi2-x
Pb
x
Te3. Through this study, interesting insights into the crystal structure evolution, crystal growth and miscibility of PbTe and Bi2Te3 into each other is obtained.
Understanding homoepitaxial growth of horizontal kinked GaN nanowires
Authors: Wu Shaoteng , Yi Xiaoyan , Tian Shuang , Zhang Shuo , Liu Zhiqiang , Wang Liancheng , Wang Junxi , Li Jinmin
Published: November 2020

Epitaxial horizontal nanowires (NWs) have attracted much attention due to their easily large-scale integration. From the reported literature, epitaxial growth is usually driven by minimization of strain between NW and substrate, which governs the growth along with specific crystallographic orientation. Here, we report the first homoepitaxial growth of horizontal GaN NWs from a surface-directed vapor−liquid−solid growth method. The NWs grow along with six symmetry-equivalent 〈1-100〉 (m-axis) directions, exhibiting a random 60°/120° kinked configuration. Owing to homoepitaxial growth, strain could be eliminated. From the obtained results, we suggest that the formation the horizontal NWs, and their growth direction /orientation is not directly related to the strain minimization. A general rule based on the epitaxial relationship and potential low-index growth orientation is proposed for understanding the arrangement of epitaxial horizontal NWs. It is deduced that kinking of the horizontal NWs was attributed to unintentional guided growth determined by the roughness of the substrates’ surface. This study provides an insight for a better understanding of the evolution of epitaxial horizontal NWs, especially for the growth direction/orientation.
Customizing hydrothermal properties of inkjet printed sensitive films by functionalization of carbon nanotubes
Authors: Bouhamed A , Rajendran D , Frenzel P , Zubkova T , Al-Hamry A , Miesel D , Kamatchi V , Ramalingame R , Bautista-Quijano J R , Lang H , Baumann R R , Kanoun O
Published: November 2020

Multiwalled carbon nanotubes (MWCNTs) are attractive materials for realizing sensors, owing to their high aspect ratio associated with excellent mechanical, electronic, and thermal properties. Moreover, their sensing properties can be tuned by introducing functional groups on their framework and adjusting the processing conditions. In this paper, we investigate the potential of functionalized CNTs for humidity and temperature sensing by optimization of the functionalization, the processing conditions and the printing conditions. The morphology of the differently functionalized MWCNTs is investigated by infrared spectroscopy (IR), scanning electron microscopy, thermogravimetry (TG) and TG-coupled mass-spectrometric studies. Using the functionalized MWCNTs, films were fabricated with different numbers of layers (4, 6, 8, 10 layers) via inkjet printing on a flexible polyimide substrate containing an interdigital microelectrode. The influence of hydrothermal effects was investigated. The sensitivity to humidity is higher for films prepared with MWCNTs functionalized with a high sonication amplitude and a bigger number of layers due to enhancements of hydrophilicity and water mobility. A higher sensitivity to temperature is achieved by a low sonication amplitude and a small number of layers. For the encapsulation of the temperature sensor against humidity, a Bectron layer is proposed, which reduces also the hysteresis effect. This study demonstrates the efficiency of carboxylic functionalized MWCNTs deposit by inkjet printing for realization of sensitive and cost-effective humidity and temperature sensors. It provides a real example for the interesting contribution of functionalization procedures to the sensing properties of MWCNTs films.
Generation of tailored terahertz waves from monolithic integrated metamaterials onto spintronic terahertz emitters
Authors: Liu Yongshan , Bai Zhongyang , Xu Yong , Wu Xiaojun , Sun Yun , Li Helin , Sun Tong , Kong RuRu , Pandey Chandan , Kraft Michael , Song Qinglin , Zhao Weisheng , Nie Tianxiao , Wen Lianggong
Published: November 2020

Recently emerging spintronic terahertz (THz) emitters, featuring many appreciable merits such as low-cost, high efficiency, ultrabroadband, and ease of integration, offer multifaceted capabilities not only in understanding the fundamental ultrafast magnetism physics but also for exploring multifarious practical applications. Integration of various flexible and tunable functions at the source such as polarization manipulation, amplitude tailoring, phase modulation, and radiation beam steering with the spintronic THz emitters and their derivatives can yield more compact and elegant devices. Here, we demonstrate a monolithic metamaterial integrated onto a W/CoFeB/Pt THz nanoemitter for a purpose-designed functionality of the electromagnetically induced transparency analog. Through elaborate engineering the asymmetry degree and geometric parameters of the metamaterial structure, we successfully verified the feasibility of monolithic modulations for the radiated THz waves. The integrated device was eventually compared with a set of stand-alone metamaterial positioning scenarios, and the negligible frequency difference between two of the positioning schemes further manifests almost an ideal realization of the proposed monolithic integrated metamaterial device with a spintronic THz emitter. We believe that such adaptable and scalable devices may make valuable contributions to the designable spintronic THz devices with pre-shaping THz waves and enable chip-scale spintronic THz optics, sensing, and imaging.
Should the concept of stopping potential be removed from teaching for A-level?
Authors: Lloyd D R
Published: November 2020

A widespread textbook error is discussed and explained, and the implications for teaching (and examining) of photoemission are described.
Efficient electron injection by hybrid parametric instability and forward direct laser acceleration in subcritical plasma
Authors: Tsymbalov I , Gorlova D , Ivanov K , Shulyapov S , Prokudin V , Zavorotny A , Volkov R , Bychenkov V , Nedorezov V , Savel’ev A
Published: November 2020

The efficient injection of electrons into a propagating relativistic laser pulse with normalized vector potential a
0 ∼ 2 is demonstrated numerically and experimentally in a thin plasma layer with density 0.15–0.3 of the critical value. The injection is due to the wavebreaking of parametric plasma waves. The trapped particles gain multi-MeV (up to 20 MeV) energies by the direct laser acceleration in the plasma channel formed by the laser pulse in the lower density plasma tail. Numerical calculations were supported by experiments with micron-scale films pre-evaporated by an additional nanosecond laser pulse and a TW femtosecond laser facility. The experimentally observed bunch of electrons with energy above 1.6 MeV had a divergence of ∼0.05 rad and charge of ∼50 pC measured with photoneutron Be(g,n) reaction.
4D printing and collaborative design of highly flexible shape memory alloy structures: a case study for a metallic robot prototype
Authors: Yao Tao , Wang Yongquan , Zhu Botao , Wei Dong , Yang Yang , Han Xiaoxiao
Published: November 2020

This paper investigates the entire process of 4D printing of shape memory alloys (SMAs), characterized by pre-programming of the future responsive shape of a deformable structure during its 3D forming. Taking an inchworm-inspired crawling robot as an application case, we propose a system prototype composed of two deformable SMA structures, i.e. a curved sheet and a spring coil. From the behavioral synergism of these two antagonistically configured structures, the initial and responsive shapes of each binary structure were collaboratively designed. The feature shapes of different structures were then pairwise combined to generate the robot’s gait, which was realized through the alternating activations of the two components. We also investigated the processing strategy and methods of the presented structures with small feature sizes and unique configurations, based on the optimal 3D printing process of selective laser melting of nickel–titanium alloys. The experimental results verified the design expectations and demonstrated the performance stability of the SMA structures under multiple testing cycles. This research confirmed the possible use of hard materials to create customized smart structures with high levels of flexibility and deformation control, providing new ideas for further development of intelligent, flexible robots.
Modelling ageing phenomenon in ferroelectrics via a Landau-type phenomenological model
Authors: He Xuan , Du Haoyuan , Wang Dan , Wang Linxiang , Melnik Roderick
Published: November 2020

In the current paper, the ageing and de-ageing phenomena in ferroelectric ceramics are modelled by a Landau-type model based on the internal bias field theory. A new phenomenological term for the internal bias electrical field is added into the free energy function to simulate the phenomenon of lattice symmetry during the ageing phenomenon. The simulations for both ageing and de-ageing phenomena are successfully presented in the current paper. The hysteretic behaviours of the ageing and de-ageing phenomena are captured very well by the proposed model.
Single input magnetorheological pseudo negative stiffness control for bridge stay cables
Authors: Xu Yan-Wei , Xu Zhao-Dong , Guo Ying-Qing , Huang Xing-Huai , Zhang Jie , Zhao Yu-Liang , Yang Yang , Zhu Chen , Zhou Min
Published: November 2020

The bridge stay cable, one of the most critical components in cable-stayed bridges, is vulnerable to vibrations owing to its low inherent damping capacity. Thus effective vibration control technology for bridge stay cables is extremely critical to safe operations of cable-stayed bridges. Several countermeasures have been presented and/or implemented to mitigate this vibration; however the passive method can only add a small amount of damping to the cables, excessive energy demand of active control devices severely limits its practicality, the semi-active control methods still have the drawbacks of complex state estimation module and a large amount of control algorithm calculation. This paper proposes a practical magnetorheological pseudo negative stiffness (MR-PNS) control system coupled with control strategy for bridge stay cables. The current reference point is introduced in the dynamic modeling of the MR-PNS control system to characterize the current control strategy. This paper investigates the adjustable of MR-PNS control system performance and energy consumption caused by different current strategies. Taking the vibration control of the Nanjing Second Yangtze River Bridge J20 cable as an example, the simulation results highlight the advantages of the MR-PNS control system that the failure area is small, the quasi-optimal area is wide, and it can still keep sort of vibration damping performance in the degenerate area. The model cable vibration control test proves the feasibility and efficiency of the single input MR-PNS bridge stay cables control method.
2020 roadmap on plasma accelerators
Authors: Albert Félicie , Couprie M E , Debus Alexander , Downer Mike C , Faure Jérôme , Flacco Alessandro , Gizzi Leonida A , Grismayer Thomas , Huebl Axel , Joshi Chan , Labat M , Leemans Wim P , Maier Andreas R , Mangles Stuart P D , Mason Paul , Mathieu François , Muggli Patric , Nishiuchi Mamiko , Osterhoff Jens , Rajeev P P , Schramm Ulrich , Schreiber Jörg , Thomas Alec G R , Vay Jean-Luc , Vranic Marija , Zeil Karl
Published: November 2020

Plasma-based accelerators use the strong electromagnetic fields that can be supported by plasmas to accelerate charged particles to high energies. Accelerating field structures in plasma can be generated by powerful laser pulses or charged particle beams. This research field has recently transitioned from involving a few small-scale efforts to the development of national and international networks of scientists supported by substantial investment in large-scale research infrastructure. In this New Journal of Physics 2020 Plasma Accelerator Roadmap, perspectives from experts in this field provide a summary overview of the field and insights into the research needs and developments for an international audience of scientists, including graduate students and researchers entering the field.
Effective elastic wave characteristics of composite media
Authors: Kim J , Torquato S
Published: November 2020

We derive exact expressions for effective elastodynamic properties of two-phase composites in the long-wavelength (quasistatic) regime via homogenized constitutive relations that are local in space. This is accomplished by extending the ‘strong-contrast’ expansion formalism that was previously applied to the static problem. These strong-contrast expansions explicitly incorporate complete microstructural information of the composite via an infinite set of n-point correlation functions. Utilizing the rapid-convergence properties of these series expansions (even for extreme contrast ratios), we extract accurate approximations that depend on the microstructure via the spectral density, which is easy to compute or measure for any composite. We also investigate the predictive power of modifications of such approximation formulas postulated elsewhere (Kim and Torquato 2020 Proc. Natl Acad. Sci.
117 8764) to extend their applicability beyond the quasistatic regime. The accuracy of these nonlocal microstructure-dependent approximations is validated by comparison to full-waveform simulation results for certain models of dispersions. We apply our formulas to a variety of models of nonhyperuniform and hyperuniform disordered composites. We demonstrate that hyperuniform systems are less lossy than their nonhyperuniform counterparts in the quasistatic regime, and stealthy hyperuniform media can be perfectly transparent for a wide range of wavenumbers. Finally, we discuss how to utilize our approximations for engineering composites with prescribed elastic wave characteristics.
Coupling between rotational and translational motions of a vibrated polygonal disk
Authors: Völkel Simeon , Huang Kai
Published: November 2020

We investigate experimentally the dynamics of a single polygonal disk (regular n-gon with 3 ⩽ n ⩽ 8) confined in a closed container under vertical vibrations against gravity. The disks tend to precess continuously upon vibrations, transferring mechanical energy into rotational and lateral translational degrees of freedom (DoF). An analysis of the velocity distribution functions in both DoF suggests that the mobility in both DoF are coupled with each other, exhibiting a characteristic angular velocity that depends on confinement and disk shape. The characteristic angular velocity can be captured with an analytical model considering sustainable precession due to continuous driving. Depending on confinement, translational and rotational kinetic energy fluctuations within one vibration cycle can be synchronized with each other and there exists a regime where injected energy is equally distributed in different DoF. Depending on n, the tendency for the disk to precess varies and there exists a regime (n ⩽ 6) where persistent rotation of the disk rarely lasts longer than one vibration period. Our results suggest the possibility of tuning energy injection into different DoF in vibrated granular disk mono-layers via shape design and confinement.