bluuebunny/crossref_metadata_2025 huggingface dataset:
Visible cameras as a non-invasive diagnostic to study negative ion beam properties
Authors: Ugoletti M. , Agostini M. , Barbisan M. , Brombin M. , Cavenago M. , Delogu R. S. , Molon F. , Pasqualotto R. , Pimazzoni A. , Serianni G.
Published: April 2021

Beam tomography is a non-invasive diagnostic that allows us to reconstruct the beam emission profile by measuring the light emitted by the beam particles interacting with the background gas, along an elevated number of lines of sight, which is related to the beam density by assuming a uniform background gas. In the framework of the heating and current drive of future nuclear fusion reactors, negative ion beams of hydrogen and deuterium are required for neutral beam injectors (NBIs) due to their elevated neutralization efficiency at high energy (in the MeV range). Beside the beam energy, beam divergence and homogeneity are two critical aspects in the design of future NBIs. In this paper, the characterization of the negative ion beam of the negative ion source NIO1 (a small-sized radio-frequency driven negative ion source, with 130 mA of total extracted H− current and 60 kV of maximum acceleration) using the tomographic system composed of two visible cameras is presented. The Simultaneous Algebraic Reconstruction Technique (SART) is used as an inversion technique to reconstruct the 3 × 3 matrix of the extracted beamlets, and the beam divergence and homogeneity are studied. The results are compared with the measurements of the other diagnostics and correlated with the source physics. The suitability of visible cameras as a diagnostics system for the characterization of the NIO1 negative ion beam is a small-scale experimental demonstration of the possibility to reconstruct more complicated multi-beamlet profiles, resulting in a powerful diagnostic for large NBIs.
A low-cost 3D printed microfluidic bioreactor and imaging chamber for live-organoid imaging
Authors: Khan Ikram , Prabhakar Anil , Delepine Chloe , Tsang Hayley , Pham Vincent , Sur Mriganka
Published: April 2021

Organoids are biological systems grown in vitro and are observed to self-organize into 3D cellular tissues of specific organs. Brain organoids have emerged as valuable models for the study of human brain development in health and disease. Researchers are now in need of improved culturing and imaging tools to capture the in vitro dynamics of development processes in the brain. Here, we describe the design of a microfluidic chip and bioreactor, to enable in situ tracking and imaging of brain organoids on-chip. The low-cost 3D printed microfluidic bioreactor supports organoid growth and provides an optimal imaging chamber for live-organoid imaging, with drug delivery support. This fully isolated design of a live-cell imaging and culturing platform enables long-term live-imaging of the intact live brain organoids as it grows. We can thus analyze their self-organization in a controlled environment with high temporal and spatial resolution.
Ultraviolet photodissociation of gas-phase iron pentacarbonyl probed with ultrafast infrared spectroscopy
Authors: Cole-Filipiak Neil C. , Troß Jan , Schrader Paul , McCaslin Laura M. , Ramasesha Krupa
Published: April 2021

It is well known that ultraviolet photoexcitation of iron pentacarbonyl results in rapid loss of carbonyl ligands leading to the formation of coordinatively unsaturated iron carbonyl compounds. We employ ultrafast mid-infrared transient absorption spectroscopy to probe the photodissociation dynamics of gas-phase iron pentacarbonyl following ultraviolet excitation at 265 and 199 nm. After photoexcitation at 265 nm, our results show evidence for sequential dissociation of iron pentacarbonyl to form iron tricarbonyl via a short-lived iron tetracarbonyl intermediate. Photodissociation at 199 nm results in the prompt production of Fe(CO)3 within 0.25 ps via several energetically accessible pathways. An additional 15 ps time constant extracted from the data is tentatively assigned to intersystem crossing to the triplet manifold of iron tricarbonyl or iron dicarbonyl. Mechanisms for formation of iron tetracarbonyl, iron tricarbonyl, and iron dicarbonyl are proposed and theoretically validated with one-dimensional cuts through the potential energy surface as well as bond dissociation energies. Ground state calculations are computed at the CCSD(T) level of theory and excited states are computed with EOM-EE-CCSD(dT).
Variational simulation of Schwinger's Hamiltonian with polarization qubits
Authors: Borzenkova O. V. , Struchalin G. I. , Kardashin A. S. , Krasnikov V. V. , Skryabin N. N. , Straupe S. S. , Kulik S. P. , Biamonte J. D.
Published: April 2021

The numerical emulation of quantum physics and quantum chemistry often involves an intractable number of degrees of freedom and admits no known approximation in the general form. In practice, representing quantum-mechanical states using available numerical methods becomes exponentially more challenging with increasing system size. Recently, quantum algorithms implemented as variational models have been proposed to accelerate such simulations. Here, we study the effect of noise on the quantum phase transition in the Schwinger model within a variational framework. The experiments are built using a free space optical scheme to realize a pair of polarization qubits and enable any two-qubit state to be experimentally prepared up to machine tolerance. We specifically exploit the possibility to engineer noise and decoherence for polarization qubits to explore the limits of variational algorithms for noisy intermediate-scale quantum architectures in identifying and quantifying quantum phase transitions with noisy qubits. We find that despite the presence of noise, one can detect the phase transition of the Schwinger Hamiltonian even for a two-qubit system using variational quantum algorithms.
Thermodynamic uncertainty relation to assess biological processes
Authors: Song Yonghyun , Hyeon Changbong
Published: April 2021

We review the trade-offs between speed, fluctuations, and thermodynamic cost involved with biological processes in nonequilibrium states and discuss how optimal these processes are in light of the universal bound set by the thermodynamic uncertainty relation (TUR). The values of the uncertainty product Q of TUR, which can be used as a measure of the precision of enzymatic processes realized for a given thermodynamic cost, are suboptimal when the substrate concentration is at the Michaelis constant, and some of the key biological processes are found to work around this condition. We illustrate the utility of Q in assessing how close the molecular motors and biomass producing machineries are to the TUR bound, and for the cases of biomass production (or biological copying processes), we discuss how their optimality quantified in terms of Q is balanced with the error rate in the information transfer process. We also touch upon the trade-offs in other error-minimizing processes in biology, such as gene regulation and chaperone-assisted protein folding. A spectrum of Q recapitulating the biological processes surveyed here provides glimpses into how biological systems are evolved to optimize and balance the conflicting functional requirements.
Structure evidence of Pna21 phase and field-induced transition of Pna21/R3c in Bi1−xSmxFe0.99Ti0.01O3 ceramics
Authors: Liu Lu , Chen Jing , Zhu Xiao Li , Chen Xiang Ming
Published: April 2021

In this study, the structure evidence of the Pna21 phase and the field-induced transition of Pna21/R3c have been quantitatively investigated in Bi1-xSmxFe0.99Ti0.01O3 (x = 0.12, 0.14, and 0.16) ceramics together with the subsequent electric field-controlled magnetism. A sequential phase transition of R3c-Pna21-Pbnm is detected by Rietveld refinement of the x-ray diffraction data. Further, the electric field-induced phase transition is investigated near the morphotropic phase boundary at x = 0.14, where the structure is tuned from Pna21 to R3c with poling treatment, and this transition could become reversible with as-annealing after poling. For x = 0.14, the structure is tuned from Pna21 to R3c with poling treatment, and this transition could become reversible with as-annealing after poling. The phase transition is confirmed by Rietveld refinements together with VSM measurements, providing an opportunity for electric field-controlled magnetism. The magnetoelectric coupling is enhanced, and the linear magnetoelectric coefficient αME up to 0.91 mV/Oe·cm is obtained in Bi1-xSmxFe0.99Ti0.01O3 ceramics. More importantly, the R3c and Pna21 structures are confirmed by selected area electron diffraction and dark-field analysis at x = 0.14, and the high-resolution TEM image demonstrates the coexistence of the R3c and Pna21 structures.
On the distributions of fuel droplets and in situ vapor in rotating detonation combustion with prevaporized n-heptane sprays
Authors: Meng Qingyang , Zhao Ningbo , Zhang Huangwei
Published: April 2021

Rotating detonation combustion fueled with partially prevaporized n-heptane sprays is studied with the Eulerian–Lagrangian method. A flattened two-dimensional domain with periodic boundaries is considered to mimic the annular rotating detonation combustor. This work focuses on the effects of prevaporized gas temperature and equivalence ratio on two-phase rotating detonation wave propagation and n-heptane droplet vaporization characteristics in the refill zone. The results show that gas temperature has a great impact on n-heptane sprays vaporization in the refill zone. The droplet evaporation rate increases with the gas temperature, especially when they are close to the deflagration surface. High evaporation rate can be observed for those droplets that are freshly injected into the chamber because they closely interact with the hot product gas from the previous cycle of the rotating detonation. A vapor layer between the droplet-laden area and deflagration surface exists and high concentrations of n-heptane can be found along the deflagration surface. A conceptual model for the droplet and vapor distribution in the refill zone is proposed. The results also show that the blast waves can encroach the refill zone and therefore influence the droplet thermodynamic properties inside the refill zone. The blast waves influence the droplet evaporation rate but have limited effects on droplet temperature, diameter, and spatial distributions. Also, the detonation propagation speed increases with increased prevaporized gas temperature and/or equivalence ratio. The detonation cell size decreases and becomes more uniform as the reactant temperature increases. Moreover, the size and irregularity of rotating detonation cells increase when the prevaporized gas equivalence ratio decreases.
Master origination by 248 nm DUV lithography for plasmonic color generation
Authors: Zhu Xiaolong , Czolkos Ilja , Johansson Alicia , Nielsen Theodor , Kristensen Anders
Published: April 2021

Plasmonic color metasurfaces enable high resolution, ink-free color decoration and sensing devices. This work presents a full solution from design of plasmonic color elements suitable for master origination by 248 nm Deep Ultraviolet (DUV) lithography to production grade manufacture of plasmonic color metasurfaces on plastic substrates. Design of hybrid aluminum disk-hole structures with hybridized multiple resonances, which are controlled by the disk-hole distance, enables plasmonic color generation across the visible spectrum with larger sized nanostructures, above 160 nm. Such larger structures can be defined by 248 nm DUV lithography as a cost-efficient and high throughput alternative to, e.g., electron beam lithography.
Nonlinear interaction between two second-mode disturbances with the same frequency in a hypersonic boundary layer over a swept blunt plate
Authors: Ma Shaoxian , Huang Zhangfeng
Published: April 2021

Zero- or low-frequency crossflow instabilities play a dominant role in the hypersonic boundary layer over a swept blunt plate. However, high-frequency second-mode disturbances dominate and lead to transition due to the wall cooling effect. The nonlinear interaction of high-frequency disturbances generates zero- or low-frequency disturbances. This paper investigates the relationship between the generated disturbances and the crossflow instability disturbances through nonlinear parabolized stability equations (NPSE) and direct numerical simulations. It is found that a special zero-frequency disturbance is generated by two second-mode disturbances with the same frequency but different spanwise wavenumbers, defined as a forced solution in this paper. This differs from the so-called eigenvalue solution obtained by linear stability theory, with the growth rate of the former being much larger than that of the latter. Additionally, the profile of the forced solution is similar to that of the second-mode disturbances, but not the crossflow-mode disturbances. The evolution of the forced solution is determined by the initial amplitude, spanwise wavenumber, and frequency of the second-mode disturbances, and is independent of the initial amplitude of crossflow-mode disturbances. If the second-mode disturbances begin to attenuate, the forced solution cannot maintain itself and transitions to the eigenvalue solution. The amplitude of the forced solution can be predicted using magnitude analysis through the amplitude of the second-mode disturbances, and the theoretical predictions are consistent with those of the NPSE when the second-mode disturbances are unstable. The results demonstrate that the forced solution is a mechanism for the second-mode disturbances to promote transition.
Electronic and magnetic properties of two-dimensional of FeX (X = S, Se, Te) monolayers crystallize in the orthorhombic structures
Authors: Bafekry A. , Abdolhosseini Sarsari I. , Faraji M. , Fadlallah M. M. , Jappor H. R. , Karbasizadeh S. , Nguyen V. , Ghergherehchi M.
Published: April 2021

In this Letter, we explore the lattice, dynamical stability, and electronic and magnetic properties of FeTe bulk and FeX (X = S, Se, Te) monolayers using the density functional calculations. The phonon dispersion relation, elastic stability criteria, and cohesive energy results show the stability of studied FeX monolayers. The mechanical properties reveal that all FeX monolayers have a brittle nature. Furthermore, these structures are stable as we move down the 6A group in the periodic table, i.e., from S, Se, and Te. The stability and work function decrease as the electronegativity decreases. The spin-polarized electronic structures demonstrate that the FeTe monolayer has a total magnetization of 3.8 μB, which is smaller than the magnetization of FeTe bulk (4.7 μB). However, FeSe and FeS are nonmagnetic monolayers. The FeTe monolayer can be a good candidate material for spin filter applications due to its electronic and magnetic properties. This study highlights the bright prospect for the application of FeX monolayers in electronic structures.
Criticality in epidemic spread: An application in the case of COVID19 infected population
Authors: Contoyiannis Y. , Stavrinides S. G. , Hanias M. P. , Kampitakis M. , Papadopoulos P. , Picos R. , Potirakis S. M. , Kosmidis E. K.
Published: April 2021

Recently, it has been successfully shown that the temporal evolution of the fraction of COVID-19 infected people possesses the same dynamics as the ones demonstrated by a self-organizing diffusion model over a lattice, in the frame of universality. In this brief, the relevant emerging dynamics are further investigated. Evidence that this nonlinear model demonstrates critical dynamics is scrutinized within the frame of the physics of critical phenomena. Additionally, the concept of criticality over the infected population fraction in epidemics (or a pandemic) is introduced and its importance is discussed, highlighting the emergence of the critical slowdown phenomenon. A simple method is proposed for estimating how far away a population is from this “singular” state, by utilizing the theory of critical phenomena. Finally, a dynamic approach applying the self-organized diffusion model is proposed, resulting in more accurate simulations, which can verify the effectiveness of restrictive measures. All the above are supported by real epidemic data case studies.
Effect of self-assembly on fluorescence in magnetic multiphase flows and its application on the novel detection for COVID-19
Authors: Li Xiang , Dong Zhi-Qiang , Yu Peng , Wang Lian-Ping , Niu Xiao-Dong , Yamaguchi Hiroshi , Li De-Cai
Published: April 2021

In the present study, the magnetic field induced self-assembly processes of magnetic microparticles in an aqueous liquid (the pure magnetic fluid) and nonmagnetic microparticles in ferrofluid (the inverse magnetic fluid) are experimentally investigated. The microparticles are formed into chain-like microstructures in both the pure magnetic fluid and the inverse magnetic fluid by applying the external magnetic field. The fluorescence parameters of these self-assembled chain-like microstructures are measured and compared to those without the effect of magnetic field. It is found that the fluorescence in the pure magnetic fluid is weakened, because the scattering and illuminating areas are reduced in the microstructures. On the contrary, the fluorescence in the inverse magnetic fluid is enhanced, because more fluorescent nonmagnetic microparticles are enriched and become detectable under the effect of the magnetic dipole force and the magnetic levitational force, and their unnecessary scattering can be absorbed by the surrounding ferrofluid. The average enhancement of the fluorescence area ratio in the inverse magnetic fluid with 3 μm nonmagnetic microparticles reaches 112.92%. The present work shows that the inverse magnetic fluid has advantages such as low cost, no scattering effect, stable fluorescence intensity, and relatively low magnetic resistance. In the end, a prototype design for the novel detection of coronavirus disease 2019 based on the magnetic field induced self-assembly in the inverse magnetic fluid is proposed, which could support the epidemic prevention and control.
Drought promotes early leaf abscission regardless of leaf habit but increases litter phosphorus losses only in evergreens
Authors: Dallstream Caroline , Piper Frida I.
Published: April 2021

Drought can alter leaf senescence and nutrient resorption, but whether these alterations are consistent between trees of contrasting leaf habits remains unclear. We conducted an experiment for 2 years with potted saplings to compare leaf habit and drought effects on leaf abscission dynamics and nutrient resorption proficiency in two evergreen and two deciduous Nothofagus (Nothofagaceae) species from southern temperate forests. A global meta-analyses has found similar nitrogen (N) proficiency between leaf habits, and greater phosphorus (P) proficiency for evergreens; however, it is unclear whether these differences are attributable to phylogeny or leaf habit. Leaf habit had no effect on either N or P resorption proficiency, but drought significantly decreased P resorption proficiency, particularly in evergreens. Additionally, drought reduced spring relative growth and promoted significantly earlier leaf abscission in both leaf habits. In evergreens, reduced P proficiency along with a non-significant trend of higher litter mass under drought led to increased litter P content. Thus, leaf P resorption proficiency of evergreens appeared to be hindered by drought, whereas drought-induced senescence was efficient in reducing P losses in deciduous saplings. Our findings suggest that nutrient cycling and species composition in strongly P-limited environments could change under sustained, moderate drought conditions.
BMP heterodimers signal via distinct type I receptor class functions
Authors: Tajer Benjamin , Dutko James A. , Little Shawn C. , Mullins Mary C.
Published: April 2021

Significance

TGF-β family heterodimeric ligands show increased or exclusive signaling compared to homodimeric ligands in both vertebrate and insect development as well as in therapeutically relevant processes, like osteogenesis. However, the mechanisms that differentiate heterodimer and homodimer signaling remain uncharacterized. We show that BMP antagonists do not account for the exclusive signaling of Bmp2/7 heterodimers in zebrafish development. We found that overexpressed homodimers can signal but surprisingly require two distinct type I receptors, like heterodimers, indicating a required activity of the heteromeric type I receptor complex. We further demonstrate that a canonical type I receptor function has been delegated to only one of these receptors, Acvr1. Our findings should inform both basic and translational research in multiple TGF-β family signaling contexts.
Establishment of heterochromatin in domain-size-dependent bursts
Authors: Nickels Jan Fabio , Edwards Ashleigh Katrine , Charlton Sebastian Jespersen , Mortensen Amanda Møller , Hougaard Sif Christine Lykke , Trusina Ala , Sneppen Kim , Thon Geneviève
Published: April 2021

Significance

How repressive heterochromatic states propagate along chromosomes and are subsequently maintained for many cell divisions remain important unanswered questions in biology. Combining mathematical modeling and single-cell measurements, we find that heterochromatin does not propagate in a purely linear manner as often assumed. Rather, sudden transitions can affect large domains globally at once. We suggest this is due to long-range interactions that bring distant nucleosomes close to each other to facilitate their modification. This supports the notion that the compartmentalization of chromatin components within the nucleus and the folding of chromatin into loops dynamically control heterochromatin propagation in three dimensions by bringing nucleosomes and their modifiers into close proximity.
The metabolism-modulating activity of IL-17 signaling in health and disease
Authors: Bechara Rami , McGeachy Mandy J. , Gaffen Sarah L.
Published: April 2021

IL-17 was discovered nearly 30 yr ago, but it has only been recently appreciated that a key function of this cytokine is to orchestrate cellular and organismal metabolism. Indeed, metabolic regulation is integrated into both the physiological and the pathogenic aspects of IL-17 responses. Thus, understanding the interplay between IL-17 and downstream metabolic processes could ultimately inform therapeutic opportunities for diseases involving IL-17, including some not traditionally linked to this cytokine pathway. Here, we discuss the emerging pathophysiological roles of IL-17 related to cellular and organismal metabolism, including metabolic regulation of IL-17 signal transduction.
Kir4.1/Kir5.1 channels possess strong intrinsic inward rectification determined by a voltage-dependent K+-flux gating mechanism
Authors: Marmolejo-Murillo Leticia G. , Aréchiga-Figueroa Iván A. , Moreno-Galindo Eloy G. , Ferrer Tania , Zamora-Cárdenas Rodrigo , Navarro-Polanco Ricardo A. , Sánchez-Chapula José A. , Rodríguez-Menchaca Aldo A.
Published: April 2021

Inwardly rectifying potassium (Kir) channels are broadly expressed in both excitable and nonexcitable tissues, where they contribute to a wide variety of cellular functions. Numerous studies have established that rectification of Kir channels is not an inherent property of the channel protein itself, but rather reflects strong voltage dependence of channel block by intracellular cations, such as polyamines and Mg2+. Here, we identify a previously unknown mechanism of inward rectification in Kir4.1/Kir5.1 channels in the absence of these endogenous blockers. This novel intrinsic rectification originates from the voltage-dependent behavior of Kir4.1/Kir5.1, which is generated by the flux of potassium ions through the channel pore; the inward K+-flux induces the opening of the gate, whereas the outward flux is unable to maintain the gate open. This gating mechanism powered by the K+-flux is convergent with the gating of PIP2 because, at a saturating concentration, PIP2 greatly reduces the inward rectification. Our findings provide evidence of the coexistence of two rectification mechanisms in Kir4.1/Kir5.1 channels: the classical inward rectification induced by blocking cations and an intrinsic voltage-dependent mechanism generated by the K+-flux gating.
The electrohydrodynamic force distribution in surface AC dielectric barrier discharge actuators: do streamers dictate the ionic wind profiles?
Authors: Kourtzanidis K , Dufour G , Rogier F
Published: April 2021

We show that the spatio-temporal electrohydrodynamic (EHD) force production in surface alternative current-dielectric barrier discharge (AC-DBD) actuators is strongly influenced by both the streamer regime during the positive phase and the micro-discharge regime during the negative phase. Focusing on the spatial EHD force profiles, we demonstrate that the ionic wind spatial distribution can only be explained by the positive contribution of the streamer regime. The location of maximum ionic wind is found to be directly linked with the maximum elongation of the streamers at several millimeters from the exposed electrode. In both positive and negative phases of the AC-DBD operation, residual volumetric and surface charges once again linked to the streamer formation and afterburn, result to a variety of positive EHD force zones which, when time-averaged in one AC period, contribute to the generation of the experimentally observed induced thin wall jet. Through a thorough elaboration of our numerical results, we provide an illustrative explanation of the EHD force spatio-temporal evolution, showcase the importance of streamers and retrieve a correct representation of the ionic wind spatial profiles when compared to experiments.
Impact of oxygen flow rate on performance of indium-tin-oxide-based RRAMs
Authors: Tsai Tsung-Ming , Tan Yung-Fang , Wu Cheng-Hsien , Yang Chih-Cheng , Chen Wen-Chung , Lin Chun-Chu , Wu Pei-Yu , Zhang Yong-Ci , Chou Sheng-Yao , Chen Zi-Yu , Lin Tzu-Heng
Published: April 2021

This paper investigates the effect of oxygen flow rates on the performance of the resistive random access memory (RRAM) of indium-tin-oxide (ITO)/ITO(O2)/TiN configuration. By using a co-sputtering deposition system with oxygen gas at different flow rates, oxygen-rich ITO thin films, such as the RRAM switching layer, can be realized. The relationship between oxygen flow rates and electrical characteristics is provided in this research. Further, the material analyses indicate that the oxygen exhibits different bonding characteristics. As a result, the device with the lower oxygen flow rate has better electrical characteristics and reliability. In addition, to explain the experimental results, the Schottky emission conduction mechanism for the high-resistance state and the Ohmic conduction mechanism for the low-resistance state are determined through the current fitting results, and appropriate models are proposed.
Exploration of structural, thermal stability and band-gap tunability of organic and inorganic mixed cation (MA)1−x
Cs
x
PbBr3 perovskite harvester via ultrasonication synthesis route
Authors: Singh Rajan Kumar , Masood Khalid Bin , Jain Neha , Tamrakar Radha , Singh Jai , Kumar Ranveer
Published: April 2021

Extensive investigation over the last few years has been done on halide based perovskite light harvester due to higher power conversion efficiency but the thermal stability with organic cation i.e. methylamine is challenging for the commercialization. Therefore, for improved structural and thermal stability, it is significant to develop a mixed cation base perovskite compound. To improve the thermal and structural stability of the material and easy synthesis method for industrialization of the material, we have demonstrated the compositional engineering of MA/CsPbBr3 perovskite material via ultrasonication synthesis process. The x-ray diffraction, transmission electron microscope, diffuse reflectance spectrometer and simultaneous thermal analyzer (STA) analysis were performed in order to understand the impact of the Cs+ into MAPbBr3 perovskite structure. Structural study reveals that up to 40% Cs+ incorporation into MAPbBr3 has pure Pm−3m cubic phase of perovskite compound with continuously increase in micro strain and lattice contraction. On the other hand, with increasing the concentration of Cs+ than MA+, optical band gap slightly increases. The thermodynamic behavior and thermal stability of the sample was studied with STA (differential scanning calorimetry/thermogravimetry). For the new generation optoelectronics with admirable stability, we believe that pure phase MA0.60Cs0.40PbBr3 perovskite compound may be a promising candidate.
Exploring phase transitions and the emergence of structural complexity at the ESRF extremely brilliant source
Authors: Mezouar M , Garbarino G
Published: April 2021

The underlying mechanisms of phase transitions and the emergence of complexity are long-standing fundamental subjects for which a complete and unified description is still missing. This is due to the intrinsic nature of condensed matter, which contains a very large number of interacting particles. The partial or complete resolution of these open questions will require a considerable development of the experimental and theoretical means. In this context, the newly developed extremely brilliant x-ray source at the European Synchrotron Radiation Facility with its unprecedented performances will provide the scientific community with a unique tool to tackle such challenging objectives. In this review article, we will discuss, through some selected examples, the potential impact this new instrument could have in the short and long term in this field of research.
An adaptive algorithm for multipath-assisted simultaneous localization and mapping using belief propagation
Authors: Dan Zesheng , Lian Baowang , Tang Chengkai
Published: April 2021

In multipath-assisted simultaneous localization and mapping (SLAM), position-related information (delays and angles) in multipath components of radio signals is used to simultaneously localize user equipment (UE) and map the environment. Multipath-assisted SLAM often involves unknown parameters that are potentially time varying, such as measurement noise. Knowledge of the measurement noise is of critical importance to multipath-assisted SLAM, and uncertainty in such knowledge will seriously affect estimation accuracy. We address this challenge by improving the belief propagation (BP)-based SLAM algorithm and proposing an adaptive multipath-assisted SLAM algorithm in a Bayesian tracking framework, which enables accommodation of a model mismatch of the measurement noise online. Specifically, we describe the evolution of the measurement noise standard deviation via a Markov chain and integrate it into the factor graph representing the Bayesian model of the multipath-assisted SLAM. Then, the BP message passing algorithm is leveraged to calculate the marginal posterior distributions of the UE, environmental features and the measurement noise standard deviation to achieve SLAM and the adaptive adjustment of the measurement noise. Finally, the experimental results verify the robustness of the proposed adaptive multipath-assisted SLAM algorithm against the uncertainty of the measurement noise.
Survivability of the thermographic phosphors YAG:Pr and SMP:Sn in a premixed flame
Authors: Kopf A , Bardi M , Kohler E , Endres T , Bruneaux G , Schulz C
Published: April 2021

The survivability of two thermographic phosphors, YAG:Pr3+ and SMP:Sn2+ ((Sr,Mg)3(PO4)2:Sn2+), in a combustion environment is studied in the post-flame regime of a premixed propane/air flame. While the laser-induced luminescence of YAG:Pr3+ can be exploited for in situ temperature measurements in the exhaust gas above the flame, there is no in situ detectable luminescence for SMP:Sn2+ for any reaction conditions within the stability limits of the flame. The phosphor particles are recaptured above the flame and ex situ analyzed for chemical or structural changes using microscopic analysis (SEM/EDX) and x-ray diffraction. The microscopic analysis of post-flame YAG:Pr3+ does not show any alteration, whereas morphology and chemical composition of SMP:Sn2+ have been modified upon passing through the reaction zone, which is responsible for the loss of its luminescence properties.
Influencing factors and growth kinetics analysis of carbon nanotube growth on the surface of continuous fibers
Authors: Qin Jianjie , Wang Chengguo , Yao Zhiqiang , Ma Ziming , Cui Xuanhao , Gao Quan , Wang Yanxiang , Wang Qifen , Wei Huazhen
Published: April 2021

Carbon nanotubes (CNTs) were continuously grown on the surface of the moving carbon fiber by chemical vapor deposition method using a custom-designed production line to prepare composite reinforcements on a large-scale. The systematic study of different parameters affecting the CNT growth revealed simple growth kinetics, which helps to control the surface morphology and structural quality of CNTs. Since hydrogen maintains the activity of the catalyst, it promotes the growth of CNTs in a continuous process. The increase of acetylene partial pressure promotes the accumulation of amorphous or graphite carbon on the catalyst surface, resulting in the decrease of CNT growth rate when acetylene concentration reaches 40%. The growth temperature significantly affects the CNT diameter and structural quality. As the temperature increases, the crystallinity of the tube wall increases obviously, and the CNT diameter increases due to the aggregate growth of the catalyst particles. According to the Arrhenius formula, the apparent activation energy is observed to be 0.67 eV, which proves that both bulk diffusion and surface diffusion exist when activated carbon passes through the catalyst to form CNTs.
Widely tunable surface plasmon resonance and uniquely superior SERS performance of Au nanotube network films
Authors: Lin Yongxing , Wang Liang , Zhang Haibao , Wu Linfeng , Fan Huibo , Liu Xianglan , Zheng Ruobing , Tian Xingyou , He Hui
Published: April 2021

Three-dimensional Au network films with flexibility and transferability were fabricated based on sputtering deposition onto electrospun nanofibers as a template. The films are constructed using long Au nanotubes that are cross-linked with each other and that have dense nanoparticles on the tube wall surface. The surface plasmon resonance (SPR) peaks for the films are tunable in a wide range, from visible light to the near-infrared region, by tuning the inner diameter and/or wall thickness of the nanotubes. Such structured film exhibits significant surface-enhanced Raman scattering (SERS) activity with good signal uniformity and stability, and possesses great potential in the in situ detection of trace organic pollutants on a solid surface by simple transferring. This study provides a Au film with a unique structure and widely tunable SPR for in situ SERS sensing and other needs.
Kinetics control over the Schiff base formation reaction for fabrication of hierarchical porous carbon materials with tunable morphology for high-performance supercapacitors
Authors: Liu Ling , Li Yuntong , Lu Zhenwu , Chen Ting , Cai Qipeng , Xu Yiting , Zeng Birong , Yuan Conghui , Kuo Shiao-Wei , Dai Lizong
Published: April 2021

Schiff base formation reaction is highly dynamic, and the microstructure of Schiff base polymers is greatly affected by reaction kinetics. Herein, a series of Schiff base cross-linked polymers (SPs) with different morphologies are synthesized through adjusting the species and amount of catalysts. Nitrogen/oxygen co-doped hierarchical porous carbon nanoparticles (HPCNs), with tunable morphology, specific surface area (SSA) and porosity, are obtained after one-step carbonization. The optimal sample (HPCN-3) possesses a coral reef-like microstructure, high SSA up to 1003 m2 g−1, and a hierarchical porous structure, exhibiting a remarkable specific capacitance of 359.5 F g−1 (at 0.5 A g−1), outstanding rate capability and cycle stability in a 1 M H2SO4 electrolyte. Additionally, the normalized electric double layer capacitance (EDLC) and faradaic capacitance of HPCN-3 are 0.239 F m−2 and 10.24 F g−1 respectively, certifying its superior electrochemical performance deriving from coral reef-like structure, high external surface area and efficient utilization of heteroatoms. The semi-solid-state symmetrical supercapacitor based on HPCN-3 delivers a capacitance of 55 F g−1 at 0.5 A g−1, good cycle stability of 86.7% after 5000 GCD cycles at 10 A g−1, and the energy density ranges from 7.64 to 4.86 Wh kg−1.
Branching TiO2 nanowire arrays for enhanced ethanol sensing
Authors: Jin Qi , Wen Wei , Zheng Shilie , Jiang Rui , Wu Jin-Ming
Published: April 2021

Nanostructure modulation is effective to achieve high performance TiO2-based gas sensors. We herein report a wet-chemistry route to precipitate directly branched TiO2 nanowire arrays on alumina tubes for gas sensing applications. The optimized branched TiO2 nanowire array exhibits a response of 9.2 towards 100 ppm ethanol; whilst those of the pristine TiO2 nanowire array and the branched TiO2 nanowire powders randomly distributed are 5.1 and 3.1, respectively. The enhanced response is mainly contributed to the unique porous architecture and quasi-aligned nanostructure, which provide more active sites and also favor gas migration. Phase junctions between the backbone and the branch of the branched TiO2 nanowire arrays help the resistance modulation as a result of potential barriers. The facile precipitation of quasi-aligned arrays of branched TiO2 nanowires, which are in situ grown on ceramic tubes, thus provides a new economical synthetic route to TiO2-based sensors with excellent properties.
Prediction of high-performance scenario with localized magnetic shear reversal on EAST tokamak
Authors: Zhang X X , Wu M Q , Li G Q , Ding S Y , Liu X J , Qian J P , Gong X Z , Gao X , Gao S L , Wu X H , Li K
Published: April 2021

An advanced scenario with high poloidal beta, large-radius internal transport barriers (ITBs) and localized reversed-shear q-profile, has been demonstrated in DIII-D/EAST joint experiments recently on the DIII-D tokamak. This scenario is also one of the future explorations on EAST. In this article, integrated modeling has been utilized to explore the regime with localized reversed-shear q-profile and high performance based on the developed long-pulse scenario on EAST. A scenario with a strong reversed-shear q-profile has been achieved with the combination of 2 MW off-axis ECH, 2.6 MW LHW and 2 MW NBI (H98y2 ∼ 1.35,

β

P

∼ 2.56,

β

N

∼ 2.23,

f

bs

∼
56
%

). In addition, a small amount (∼0.1 MW) of centrally deposited ECH facilitates the generation of the bootstrap current on or near the axis, and hence reduces the level of the q-profile in this region; thus, a scenario with localized magnetic shear reversal and strong large-radius ITBs is obtained (H98y2 ∼ 1.4,

β

P

∼ 2.66,

β

N

∼ 2.31,

f

bs

∼
60
%

). Modeling predictions indicate that off-axis ECH/LHW and high plasma density promote the formation of large-radius ITBs. A further increase in the injected power of centrally deposited ECH (0.15 MW) or NBI (4 MW) leads to an increase in the temperature gradient, especially the electron temperature near the axis, and large-radius ITBs disappear in all channels (T
e, T
i, n
e); also, the confinement quality decreases. The bootstrap current density profiles and LHW-driven current profiles tend to peak near the axis due to the increase in electron temperature profiles, which eventually leads to peaked total current profiles, similar to the EAST long-pulse scenario. Changes in magnetic shear result in the disappearance of large-radius ITBs. Modeling validation will be carried out in the near future on the EAST tokamak.
Theoretical description of chirping waves using phase-space waterbags
Authors: Hezaveh H , Qu Z S , Hole M J , Dewar R L
Published: April 2021

The guiding centre dynamics of fast particles can alter the behaviour of energetic particle (EP) driven modes with chirping frequencies. In this paper, the applicability of an earlier trapped/passing locus model (Hezaveh et al 2017 Nucl. Fusion
57 126010) has been extended to regimes where the wave trapping region can expand and trap ambient particles. This extension allows the study of waves with up-ward and down-ward frequency chirping across the full range of EP orbits. Under the adiabatic approximation, the phase-space of EPs is analysed by a Lagrangian contour approach where the islands are discretised using phase-space waterbags. In order to resolve the dynamics during the fast formation of phase-space islands and find an appropriate initialisation for the system, full-scale modelling is implemented using the bump-on-tail code. In addition to investigating the evolution of chirping waves with deepening potentials in a single resonance, we choose specific pitch-angle ranges in which higher resonances can have a relatively considerable contribution to the wave-particle interaction. Hence, the model is also solved in a double-resonance scenario where we report on the significant modifications to the behaviour of the chirping waves due to the 2nd resonance. The model presented in this paper gives a comprehensive 1D paradigm of long range frequency chirping signals observed in experiments with both up-ward and down-ward chirping and multiple resonances.
Optical constants of crystalline Bi2Sr2CaCu2O

8+δ

by Brillouin light scattering spectroscopy
Authors: McNiven B D E , LeBlanc J P F , Andrews G T
Published: April 2021

Room-temperature optical constants of crystalline Bi2Sr2CaCu2O

8
+
δ

were determined using data extracted from Brillouin light scattering spectra. Optical extinction coefficient-to-refractive index ratios at a wavelength of 532 nm were obtained from bulk phonon peak linewidth and frequency shift measurements and range from

0.19
⩽
2
κ
/
n
⩽
0.29

for directions close to the crystallographic c-axis. These ratios, and optical extinction coefficients, absorption coefficients, and imaginary parts of the dielectric function determined from these ratios and known refractive index, are in general agreement with values found in optical reflectance studies, but are 5–7 times larger than those extracted from optical interference measurements.
Saturating multiple ionization in intense mid-infrared laser fields
Authors: Haniel Franz E , Schröder Hartmut , Kahaly Subhendu , Nayak Arjun , Dumergue Mathieu , Mondal Sudipta , Zoltán Filus , Flender Roland , Kurucz Máté , Haizer Ludovit , Kiss Bálint , Charalambidis Dimitris , Kling Matthias F , Tzallas Paraskevas , Bergues Boris
Published: April 2021

The interpretation of experimental data from novel mid-infrared few-cycle laser sources requires an understanding of ionization mechanisms and knowledge about related ion yields. Experimental studies have indicated sequential double ionization as the dominant process above 1014 W cm−2. These results contradict a recent prediction that in this spectral region, non-sequential processes dominate the double ionization of xenon up to intensities of about 1015 W cm−2. In either case, the ratio of doubly to singly charged xenon yield reported in previous studies has been limited to a few percent, indicating a regime well below the onset of saturation of the double ionization process. We present an experimental study of double ionization of xenon and krypton atoms exposed to intense near four-cycle pulses at 3.2 μm. Our experiments rely on the ion microscopy technique, which facilitates the detection of ions originating from a restricted region within the interaction volume, thereby reducing the impact of focal averaging. Our measurements suggest that at intensities of close to 1.2 × 1014 W cm−2, double ionization of xenon and krypton is already significantly saturated. In particular, we find a doubly to singly charged yield ratio of about 75 percent for xenon and 25 percent for krypton. We compare our results with the predictions of different models accounting for the effects of volume averaging and focal geometry. We find that in the deeply saturated regime of our experiment, the Perelomov–Popov–Terentyev theory significantly underestimates the observed double ionization yield.
Suppression of leakage effect of Majorana bound states in the T-shaped quantum-dot structure*
Authors: Gong Wei-Jiang , Xue Yu-Hang , Wang Xiao-Qi , Zhang Lian-Lian , Yi Guang-Yu
Published: April 2021

We theoretically study the transport properties in the T-shaped double-quantum-dot structure, by considering the dot in the main channel to be coupled to the Majorana bound state (MBS) at one end of the topological superconducting nanowire. It is found that the side-coupled dot governs the effect of the MBS on the transport behavior. When its level is consistent with the energy zero point, the MBS contributes little to the conductance spectrum. Otherwise, the linear conductance exhibits notable changes according to the inter-MBS coupling manners. In the absence of inter-MBS coupling, the linear conductance value keeps equal to e
2/2h when the level of the side-coupled dot departs from the energy zero point. However, the linear conductance is always analogous to the MBS-absent case once the inter-MBS coupling comes into play. These findings provide new information about the leakage effect of MBSs in quantum-dot structures.
Classical-field description of Bose–Einstein condensation of parallel light in a nonlinear optical cavity*
Authors: Wang Hui-Fang , Zhang Jin-Jun , Zhang Jian-Jun
Published: April 2021

We study the Bose–Einstein condensation of parallel light in a two-dimensional nonlinear optical cavity, where the massive photons are converted into photon molecules (p-molecules). We extend the classical-field method to provide a description of the two-component system, and we also derive a coupled density equation which can be used to describe the conversion relation between photons and p-molecules. Furthermore, we obtain the chemical potential of the system, and we also find that the system can transform from the mixed photon and p-molecule condensate phase into a pure p-molecule condensate phase. Additionally, we investigate the collective excitation of the system. We also discuss the problem how the spontaneous decay of an atom is influenced by both the phase transition and collective excitation of the coupling system.
Radial profile of bottom quarks in jets in high-energy nuclear collisions *
Authors: Wang Sa , Dai Wei , Zhang Ben-Wei , Wang Enke
Published: April 2021

Angular correlations between a heavy quark (HQ) and its tagged jet are potentially new tools to gain insight into the in-medium partonic interactions in relativistic heavy-ion collisions. In this work, we present the first theoretical study on the radial profiles of B mesons in jets in Pb+Pb collisions at the Large Hadron Collider (LHC). The initial production of a bottom quark tagged jet in p+p is computed by SHERPA, which matches the next-to-leading order matrix elements with contributions of parton showers, whereas the massive quark traversing the quark-gluon plasma is described by a Monte Carlo model, SHELL, which can simultaneously simulate light and heavy flavor in-medium energy loss within the framework of Langevin evolution. In p+p collisions, we find that at lower

the radial profiles of heavy flavors in jets are sensitive to the heavy quark mass. In 0-10% Pb+Pb collisions at

TeV, we observe an inverse modification pattern of the B meson radial profiles in jets at

GeV compared to those of D mesons: the jet quenching effects narrow the jet radial profiles of B mesons in jets while broadening those of D mesons in jets. We find that in A+A collisions, the contribution dissipated from the higher

GeV region naturally has a narrower initial distribution and consequently leads to a narrower modification pattern of the radial profile; however the diffusion nature of the heavy flavor in-medium interactions will give rise to a broader modification pattern of the radial profile. These two effects consequently compete and offset with each other, and the b quarks in jets benefit more from the former and suffer less diffusion effect compared to that of c quarks in jets. These findings can be tested in the future experimental measurements at the LHC to gain better understanding of the mass effect of jet quenching.