bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of growth kinetics during remote epitaxy of complex oxides on graphene by pulsed laser deposition
Authors: Wohlgemuth M. A. , Trstenjak U. , Sarantopoulos A. , Gunkel F. , Dittmann R.
Published: February 2024

Remote epitaxy through 2D materials opens new opportunities for research and application, overcoming some limitations of classical epitaxy and allowing the creation of freestanding layers. However, using graphene as a 2D interlayer for remote epitaxy of metal oxides is challenging, particularly when carried out by pulsed laser deposition (PLD). The graphene layer can be easily oxidized under the typically applied high oxygen pressures, and the impact of highly kinetic particles of the plasma plume can lead to severe damages. In this study, both aspects are addressed: Argon is introduced as an inert background gas in order to avoid oxidation and to reduce the kinetic impact of the plasma species on graphene. The laser spot size is minimized to control the plasma plume and particle flux. As a model system, strontium titanate (STO) is quasi-homoepitaxially grown on graphene buffered STO single crystals. Raman spectroscopy is performed to evaluate the 2D, G, and D band fingerprints of the graphene layer and to assess the defect structure of the interlayer after the deposition. Our results prove that control of the growth kinetics by reducing the laser spot size and by using high argon pressures provides a key strategy to conserve graphene with a low defect density during PLD while allowing a layer-by-layer growth of structurally coherent oxide layers. This strategy may be generalized for the PLD remote epitaxy of many complex oxides, opening the way for integrating 2D materials with complex oxides using widely accessible PLD processes.
Laser excitation of magnons in NiO via spin–phonon coupling
Authors: Shi Wei , Wang Yangkai , He Hongchuan , Huang Qiuping , Fu Zhengping , Wang Jianlin , Lu Yalin
Published: February 2024

Antiferromagnetic materials have recently been proposed as new types of terahertz (THz) range spintronic devices owing to their ultrafast spin dynamics. Manipulating their spin dynamics expediently, however, remains a key challenge. Here, we demonstrate the laser excitation of magnons in a prototypical antiferromagnet NiO via spin–phonon coupling. The terahertz time-domain spectrum revealed the frequencies of antiferromagnetic magnons near 1 THz. Laser excitations in the visible spectrum caused a noticeable softening of the magnons. Raman spectroscopy results established the presence of optical phonons. The laser heating effect was excluded by finite-element analysis and variable-temperature measurements. The temperature- and power-dependent properties suggest an optical phonon–magnon coupling mechanism. Laser excitation raises the optical phonon temperature, linked with the magnon temperature, via the magnon–phonon interaction. Consequently, the magnon temperature rises, and the magnon mode frequency softens. Our findings shed light on spin–phonon coupling in antiferromagnetic insulators and open a route for creating rapid opto-spintronic devices that utilize antiferromagnetic materials.
Reducing Richtmyer–Meshkov instability jet velocity via inverse design
Authors: Kline Dylan J. , Hennessey Michael P. , Amondson David K. , Lin Steve , Grapes Michael D. , Ferrucci Massimiliano , Li Peggy , Springer H. Keo , Reeves Robert V. , Sullivan Kyle T. , Belof Jonathan L.
Published: February 2024

In this work, we detail a novel application of inverse design and advanced manufacturing to rapidly develop and experimentally validate modifications to a shaped charge jet analog. The shaped charge jet analog comprises a copper liner, a high explosive (HE), and a silicone buffer. We apply a genetic algorithm to determine an optimal buffer design that can be placed between the liner and the HE that results in the largest possible change in jet velocity. The use of a genetic algorithm allows for discoveries of unintuitive, complex, yet optimal buffer designs. Experiments using the optimal design verified the effectiveness of the buffer and validated the machine learning approach to hydrodynamic design optimization.
Multifunctional molecular linker on buried interface for efficient and stable cesium–formamidinium perovskite solar cells
Authors: Wu Yan , Wang Yu , Song Jiaxing , Wu Xianrui , Zhao Yongkang , Li Huinan , Yin Xinxing , Hu Lin , Su Zhen , Jin Yingzhi , Zhang Xinyu , Cheng Yongliang , Li Zaifang
Published: February 2024

Interface engineering is one of the key issues in fabricating efficient and stable perovskite solar cells (PSCs). Herein, we introduced self-assembled molecules of 3,4,5-trimethoxyphenylacetic acid (PAA) and 3,4,5-trimethoxyphenylpropionic acid (PPA) as a multifunctional linker to modify the buried interface between SnO2 and the Cs/FA perovskite. These modifiers can simultaneously bond to the SnO2 surface and chemically interact with perovskite to passivate the surface defects. Moreover, the PAA/PPA can facilitate the crystal growth of perovskite to form high-quality films. Accordingly, the defect density and trap-assisted charge recombination at the interface and within the perovskite are markedly reduced. Additionally, the large dipole moments of modifiers induce the modulation of energy level of SnO2, resulting in the favorable band alignment and thus the enhanced electron extraction and transport. As a result, PPA is certified to be more effective in interfacial regulation, and the Cs/FA-based PSC produces a significantly increased PCE of 22.2% with inhibited hysteresis, higher than the control (20.0%) and PAA-modified (21.5%) ones. Meanwhile, the unencapsulated devices with PAA/PPA modification presented much better ambient and thermal stability than the control device.
Nano-positive up negative down in binary oxide ferroelectrics
Authors: Gomez Andres , Celano Umberto
Published: February 2024

Ferroelectric HfO2 and ZrO2-based materials are promising candidates for next-generation ferroelectric devices, but their characterization is challenging due to complex factors such as crystal phases, degradation mechanisms, and local inhomogeneities. In this work, we propose a novel nanosized positive-up-negative-down (PUND) method to assess the ferroelectric response of doped-HfO2. This method is based on actual current probing and is immune to most electrostatic artifacts that plague other electrical atomic force microscopy (AFM) techniques. We demonstrate the PUND method’s ability to induce ferroelectric switching in Si-doped HfO2 and investigate the distinctive PUND response obtained for individual grains. We also extract the polarization charge based on a direct estimate of the tip–sample contact area. The proposed PUND method is a significant innovation as it is a method to combine the high spatial resolution of AFM with the immunity to electrostatic artifacts of current probing. This makes it a powerful tool for studying ferroelectric materials at the nanoscale, where local inhomogeneities and other effects can have a significant impact on their behavior. The PUND method is also notable for its ability to extract polarization charge based on a direct estimate of the tip–sample contact area. This is a significant improvement over previous methods, which often relied on indirect or approximate estimates of the contact area. Overall, the PUND method is a novel and innovative technique that offers significant advantages for the characterization of ferroelectric materials at the nanoscale. It is expected to have a major impact on the research and development of next-generation ferroelectric devices.
A novel self-adaptive SIS model based on the mutual interaction between a graph and its line graph
Authors: Bartesaghi Paolo , Clemente Gian Paolo , Grassi Rosanna
Published: February 2024

We propose a new paradigm to design a network-based self-adaptive epidemic model that relies on the interplay between the network and its line graph. We implement this proposal on a susceptible-infected-susceptible model in which both nodes and edges are considered susceptible and their respective probabilities of being infected result in a real-time re-modulation of the weights of both the graph and its line graph. The new model can be considered as an appropriate perturbation of the standard susceptible-infected-susceptible model, and the coupling between the graph and its line graph is interpreted as a reinforcement factor that fosters diffusion through a continuous adjustment of the parameters involved. We study the existence and stability conditions of the endemic and disease-free states for general network topologies. Moreover, we introduce, through the asymptotic values in the endemic steady states, a new type of eigenvector centrality where the score of a node depends on both the neighboring nodes and the edges connected to it. We also investigate the properties of this new model on some specific synthetic graphs, such as cycle, regular, and star graphs. Finally, we perform a series of numerical simulations and prove their effectiveness in capturing some empirical evidence on behavioral adoption mechanisms.
Understanding melting of Ti crystals with spherical voids from molecular dynamics simulations
Authors: Hazarika Manash Protim , Chakraborty Somendra Nath
Published: February 2024

Titanium (Ti) is one of the most important metals used in several industrial applications, and the presence of spherical defect reduces its strength and stability. We simulate the melting of Ti crystals with a spherical void of radii 0.6, 0.8, 1.0, and 1.5 nm and also of the crystal without it. Ti is modeled using embedded atom method ,and all crystals are heated at 1 atm from 300 to 2200 K till it melts completely. All molecular dynamics trajectories are analyzed using radial distribution functions, bond-orientational order parameters, Voronoi tessellation, and velocity auto-correlation functions. The results show that 0.6, 0.8, 1.0, and 1.5 nm voids fill before the crystals melt and they fill immediately within few picoseconds; thereafter, atoms rearrange/order to crystal like arrangements, wherein overall crystallinity remains hcp for crystals with 0.6 and 0.8 nm void and changes to bcc for the crystals with 1.0 and 1.5 nm voids. For all crystals with and without void, melting takes place with the loss of both long- and short-range orders and not from liquid like nuclei as proposed by classical nucleation theory.
A falling fluid droplet in an oscillating flow field
Authors: Williams I. T. , Kalliadasis S. , Generalis S. C. , Trevelyan P. M. J.
Published: February 2024

We examine the flow in and around a falling fluid droplet in a vertically oscillating flow. We assume axisymmetric Stokes flow, and for small deformations to the droplet, the governing equations can be linearized leading to an infinite system of linear ordinary differential equations. In this study, we have analytically solved the problem in the small-capillary limit. We note that the solution locally breaks down at the poles of the droplet. The drag and center of the mass were also obtained. In the case when only odd modes are present, the droplet shows three-dimensional axisymmetric heart-shaped solutions oscillating vertically in time. When only even modes are present, the droplet exhibits axisymmetric stretching and squeezing.
Coupled instability modes at a solvent/non-solvent interface to decorate cellulose acetate flowers
Authors: Vanarse Vinod Babasaheb , Thakur Siddharth , Ghosh Abir , Parmar Prathu Raja , Bandyopadhyay Dipankar
Published: February 2024

Dispensing a water drop on the thin film of a solution composed of cellulose acetate (CA) in dimethyl formamide (DMF) forms a thin and porous CA layer at the water–DMF interface. While a denser water drop on a rarer CA–DMF film manifests a Rayleigh–Taylor instability—RTI, the dynamically forming porous layer at the water–DMF interface triggers a Saffman–Taylor instability—STI. The combined effects of RTI and STI enable the formation, growth, coalescence, and branching of an array of periodic finger patterns to finally develop into a flower-like morphology. A general linear stability analysis (GLSA) of a thin bilayer composed of a Newtonian and incompressible water layer resting on a Darcy–Brinkman porous medium could predict the length and the time scales of such a finger formation phenomenon. The GLSA uncovers the crucial roles of pressure gradients originating from the gravitational effects, osmotic forces, the Marangoni effect, and capillary forces on the dynamics of the finger formation. While the density difference between water and CA–DMF layer plays a crucial role in deciding the initial finger spacing, the osmotic pressure dictates the formation, growth, branching, and coalescence of fingers. The length-FL and number-Navg of fingers are found to scale as FL∼We0.33Re−0.25 and Navg∼We0.33Re0.25. Further, an inverse relationship of the concentration of CA (C) with ∼We−0.3 and ∼Re−0.7 highlights its role in the formation and growth of fingers. The loading of CA in DMF, the viscosity and density of the CA–DMF film, and the curvature of the fingers are found to be other parameters that decide morphologies.
Measuring the permittivity of fused silica with planar on-wafer structures up to 325 GHz
Authors: Bergmann Florian , Jungwirth Nicholas R. , Bosworth Bryan T. , Cheron Jerome , Long Christian J. , Orloff Nathan D.
Published: February 2024

Fused silica has become an interesting alternative to silicon for millimeter-wave (mmWave) applications. Unfortunately, there are a few reports on the measurement of fused silica's permittivity above 110 GHz that use electrical rather than optical methods. Given that mmWave applications use electrical circuits, additional electrical data would be useful to industry. To test the feasibility of electrical methods, we applied on-wafer techniques based on coplanar waveguide transmission lines to measure the complex permittivity of fused silica to 325 GHz. Our approach used the multiline thru-reflect-line algorithm on the scattering parameter measurements of transmission lines. Our method combined these results with dc measurements of the resistivity of the metals, simulations of the coplanar waveguide cross section, and dimensional metrology. In short, our measurements do not show significant dielectric dispersion for fused silica up to 325 GHz. The resulting complex permittivity was ϵr=3.87±0.03 and a loss tangent tanδ< 0.005 from 320 MHz to 325 GHz. To support our conclusions, we performed an uncertainty analysis considering relevant sources of uncertainty. In the broader context, these results show that fused silica is a suitable substrate for mmWave electronics where the loss tangent must be less than 0.005 up to 325 GHz.
Photothermal defect imaging in hybrid fiber metal laminates using the virtual wave concept
Authors: Gahleitner L. , Thummerer G. , Plank B. , Wiedemann J. , Mayr G. , Hühne C. , Burgholzer P. , Cakmak U.
Published: February 2024

This study presents photothermal imaging results of subsurface material defects within fiber metal laminates utilizing the virtual wave concept. Therefore, we theoretically analyze the propagation of the virtual wave signal in a hybrid composite laminate via the method of images. For provoking local material damage, the hybrid composite sample is subjected to a defined impact loading. The results obtained from photothermal defect imaging, utilizing rectangular laser pulse excitation, are compared with results obtained from 3D x-ray computed tomography. To sum up, we demonstrate a fast, non-invasive, and easily interpretable reconstruction of defects within macroscopic hybrid composite laminates based on the virtual wave concept.
Time-resolved analysis of dual-gate FETs with non-parabolic energy dispersion for THz applications
Authors: Pech M. , Abdi A. , Schulz D.
Published: February 2024

The investigation of charge carrier transport in state-of-the-art nanoelectronic devices based on III/V semiconductors proves to be challenging, even more so when the highly non-parabolic energy dispersion exhibited by these materials is taken into account. Unlike the common approach of neglecting this behavior by the use of the parabolic band approximation, a novel combination of a tight-binding approach with a quantum Liouville-type equation is introduced here, where any arbitrary energy dispersion can effectively be included. This leads to a discretization based on the atomic structure without the need for finite difference approximations of the Hamiltonian. Because this allows for the stationary as well as the transient simulation of quantum charge carrier transport, it is well suited for the analysis of ultrathin FETs such as dual-gate FETs when it is combined with a mode-space approach. We demonstrate that the parabolic approximation not only vastly underestimates the current densities when compared to the non-parabolic case but also fails to capture transient effects such as gain compression when amplifier operation is considered.
Exploring poly-crystallization in semiconductors through assumption-less growth simulations: CdTe/CdS case study
Authors: Abdullah Sharmin , Zhou Xiaowang , Aguirre Rodolfo , Zubia David
Published: February 2024

Crystal growth is a complex process with far-reaching implications for high-performance materials across various fields. Recent advancements in structural analysis methods such as polyhedral template matching, which allows semiconductor-specific analysis, coupled with simulation technology, have enabled the comprehensive study of crystallization dynamics in semiconductors. However, the exploration of polycrystalline semiconductors created with minimal external intervention of the crystallization processes is relatively uncharted in comparison with metals. In this study, we employ molecular dynamics to simulate the growth of polycrystalline CdTe/CdS with the assumptions of classical mechanics, a Stillinger–Weber potential, an amorphous substrate, and common vapor growth conditions to allow the polycrystalline structures to evolve naturally. Post-simulation, we identify and analyze impactful structures and events, comparing them to theory and experiment to gain insight into various modes of crystallization dynamics. Two research questions guided the study: (1) How realistic are assumption-less simulated polycrystalline semiconductor structures? (2) To what extent can the approach provide insight into crystallization? The simulations, performed with minimal external control, yield polycrystalline structures mirroring experimental findings. The analysis reveals key crystallization insights, such as the role of amorphous atoms in the transition from nucleation to grain growth and the transformative impact of single events, such as dislocations, on crystallization dynamics. The method paves the way for reproducing and analyzing realistic polycrystalline semiconductor structures with minimal simulation assumptions across various growth modes.
Triple electromagnetically induced transparency generated slow light for multiple carbon nanotube resonators
Authors: Chen Hua-Jun
Published: February 2024

Hybrid spin-mechanical systems offer a promising platform for advancing quantum science and technology. However, practical implementation of applications within these hybrid quantum systems demands the seamless integration of supplementary physical components. In this context, we present a proposal for a multi-mode spin-mechanical setup, featuring the utilization of three-mode coupling nanomechanical carbon nanotube (CNT) resonators. These resonators interact with each other via a phase-dependent phonon-exchange mechanism, which is coupled to the same nitrogen vacancy (NV) centers in diamond. Based on the modulation of the phonon–phonon coupling phase and leveraging the triple Fano-like resonance phenomenon, a tripling of electromagnetically induced transparency (EIT) becomes achievable within the system. This tripling is accompanied by swift dispersion, leading to a subtle advancement or delay in outcomes. The phenomenon of triple Fano-like resonance, alongside the resulting triple EIT, engenders noteworthy slow-to-fast and fast-to-slow light effects, which is theoretically demonstrated in CNT resonators, with both identical and distinct frequencies. The findings underscore that CNT resonators with varying frequencies can evoke a more pronounced transition in the slow–fast–slow and fast–slow–fast light effects. This study lays the foundation for the application of phonon-mediated optical information storage and processing.
Three-dimensional numerical investigation of impact-freezing of tin drops on an incline using a phase field method
Authors: Shen Mingguang , Li Ben Q.
Published: February 2024

Drop impact-freezing on an incline is omnipresent in nature and industrial applications like 3D (three-dimensional) printing, but most current research concentrates on the impact instead of the interaction between impact and freezing. This paper thus developed an OpenMP-paralleled phase field model to probe into the underlying physics in 3D printing conditions. The finite difference solution to the Cahn–Hilliard equation helps track the evolving liquid–gas interface, and the liquid fraction is defined over the whole computational domain to distinguish between solid and fluid. The model was first validated against two experiments, showing agreeable consistency. Then, it was applied to inclined impact without and with phase change. The effect of inclination angles was also examined. It was found that increasing inclination angles can extend contact time, and that solidification cannot retard the gravity-driven fluid flow down the incline at an inclination angle of 45° but can at an inclination angle below 30°. Besides, the retracting speed declines with increased inclination angles.
Mesoscale self-organization of polydisperse magnetic nanoparticles at the water surface
Authors: Ukleev Victor , Khassanov Artoem , Snigireva Irina , Konovalov Oleg , Vorobiev Alexei
Published: February 2024

In this study, we investigated the self-ordering process in Langmuir films of polydisperse iron oxide nanoparticles on a water surface, employing in situ x-ray scattering, surface pressure-area isotherm analysis, and Brewster angle microscopy. X-ray reflectometry confirmed the formation of a monolayer, while grazing incidence small-angle x-ray scattering revealed short-range lateral correlations with a characteristic length equal to the mean particle size. Remarkably, our findings indicated that at zero surface pressure, the particles organized into submicrometer clusters, merging upon compression to form a homogeneous layer. These layers were subsequently transferred to a solid substrate using the Langmuir–Schaefer technique and further characterized via scanning electron microscopy and polarized neutron reflectometry. Notably, our measurements revealed a second characteristic length in the lateral correlations, orders of magnitude longer than the mean particle diameter, with polydisperse particles forming circular clusters densely packed in a hexagonal lattice. Furthermore, our evidence suggests that the lattice constant of this mesocrystal depends on the characteristics of the particle size distribution, specifically the mean particle size and the width of the size distribution. In addition, we observed internal size separation within these clusters, where larger particles were positioned closer to the center of the cluster. Finally, polarized neutron reflectometry measurements provided valuable insights into the magnetization profile across the layer.
Nonadiabatic transitions during a passage near a critical point
Authors: Sinitsyn Nikolai A. , Sadhasivam Vijay Ganesh , Suzuki Fumika
Published: February 2024

The passage through a critical point of a many-body quantum system leads to abundant nonadiabatic excitations. Here, we explore a regime, in which the critical point is not crossed although the system is passing slowly very close to it. We show that the leading exponent for the excitation probability can then be obtained by standard arguments of the Dykhne formula, but the exponential prefactor is no longer simple and behaves as a power law on the characteristic transition rate. We derive this prefactor for the nonlinear Landau–Zener model by adjusting Dykhne’s approach. Then, we introduce an exactly solvable model of the transition near a critical point in the Stark ladder. We derive the number of excitations for it without approximations and find qualitatively similar results for the excitation scaling.
Microfluidic shearing regulated in spin-coated dielectrics for ultra-low voltage and high-performance synaptic transistors
Authors: Li Yushan , Jing Lixin , Qu Dandan , Xu Zihao , Tao Ruiqiang , Fan Zhen , Zhou Guofu , Lu Xubing , Liu Junming
Published: February 2024

Polarization-based synaptic transistors offer the advantages of low power consumption and non-volatility, but they face significant challenges in achieving multi-level conductance states and low operating voltage. Here, this issue was resolved by precisely controlling the alignment of polar electret molecule chains through microfluidic techniques in spin-coating. Optimized devices exhibit cycles of near-linear potentiation and depression, yielding 80 distinct conductance states under ultra-low voltage pulse stimulation (0.1 V/−0.1 V), with an ideal dynamic range of approximately 90 nA. Additionally, simulated image recognition accuracy exceeds 90%, highlighting exceptional weight updating capabilities. This work opens up an avenue for low-cost, low-power, and high-performance synaptic devices.
Ultraviolet laser-etched Norland optical adhesive 81 micromodel for studying two-phase flow experiments
Authors: Huang Tao , Huang Xinlei , Huang Zhaoqin , Qian Huanran
Published: February 2024

As the global energy demand grows, maximizing oil extraction from known reserves has become critical. The study of microfluidic flow and transport in porous media has become a key direction for future subsurface energy technologies. However, the high requirements of fabrication techniques and materials have constrained the progress of micro-scale experiments. In this study, we have innovatively proposed a microfluidic chip fabrication method based on ultraviolet laser, and a set of visualized microdrive platforms is developed to allow direct observation of two-phase flow processes at the pore scale. In this study, two pore structures—one with low porosity and high connectivity and the other with high porosity but low connectivity—were constructed to investigate the effect of pore structure on recovery. Two micromodels with different pore structures were fabricated, and water and surfactant drive experiments were conducted at different drive rates, respectively. The results show that increasing the replacement rate and introducing surfactant can somewhat improve the final recovery. Using surfactant is more effective in enhancing the recovery rate than increasing the replacement rate. The complexity of pore structure is one of the main factors affecting the formation of residual oil. The microfluidic experimental setup proposed in this study reduces the time and cost of conventional practical methods. It permits visualization of the oil drive process, demonstrating that the Norland Optical Adhesive 81 (NOA81) micromodel is a valuable tool in two-phase flow studies and its applications.
Broken edge spin symmetry induces a spin-polarized current in graphene nanoribbon
Authors: Ali Shahjad , Ali Md Ehesan
Published: February 2024

Zigzag graphene nanoribbons (ZGNRs) are known to possess spin moments at the hydrogen-terminated edge carbon atoms; thus, spin-polarized electron transmission is expected, while the current is longitudinally passed through the ZGNRs. However, in pristine ZGNRs, spin-polarized transmission is not observed due to symmetric anti-parallel distributions of the spin densities between the edges. Here, the hypothesis is that any physical or chemical process that breaks such anti-parallel spin symmetry can induce spin-polarized transmission in ZGNRs. In this work, we have established this proof-of-concept by depositing the trimethylenemethane (TMM) radical on 6ZGNRH and investigating the quantum transport properties by employing density functional theory in conjunction with the nonequilibrium Green’s function method. Although TMM has a high magnetic moment (

2

μ

B

), it does not induce magnetization in 6ZGNRH when TMM is physisorbed. However, during the chemisorption of TMM, it forms the

π
−
π

bond with the 6ZGNRH in a particular geometric configuration, where the p

z
orbitals of carbon atoms of TMM have maximum overlap with the p

z
orbitals of carbon atoms of 6ZGNRH. The chemisorption of TMM transfers the spin moment to 6ZGNRH, which breaks the edge spin symmetry of pristine 6ZGNRH. The adsorption of the TMM radical results in transmission dips in the transmission spectra due to interference between localized states of TMM and 6ZGNRH states. This induces spin-polarized transmission with 60% spin-filtering efficiency at zero bias, which can further be enhanced up to 92% by applying a bias voltage of 1.0 V.
Tailoring optoelectronic performance through compositional engineering to optimize trap densities in Cs
x
MA(1−
x)
PbI3 perovskite nanowires
Authors: Han Bin , Hu Yu , Liu Bo , Wang Guanghui , Qiu Qi , Tang Yanren , Ma Shufang , Xu Bingshe , Qiu Bocang , Hsu Hsien-Yi
Published: February 2024

Organic-inorganic methylammonium lead iodide perovskite (MAPbI3) nanowires (NWs) have attracted significant attention in the realm of optoelectronic devices due to their outstanding optoelectronic properties. However, the persistent challenge of high trap densities has been a limiting factor in realizing their full potential in device performance. To address this challenge, we incorporated cesium (Cs) and systematically investigated the impact of Cs concentration on the trap densities and the optoelectronic characteristics of Cs
x
MA(1−x)PbI3 NWs. Our findings unveiled an initial reduction in trap densities as Cs+ content increased, with the lowest point occurring at x = 0.2. However, beyond this threshold, trap densities began to rise, eventually surpassing those observed in pure MAPbI3 at x = 0.4. Furthermore, we fabricated single NW photodetectors to assess how Cs+ content influenced optoelectronic properties. The results indicated that Cs+ incorporation led to enhancements in photocurrent and response speed, withthe optimal performance observed at x = 0.2. Our study provides valuable insights into the role of Cs+ incorporation in tailoring the optoelectronic properties of perovskite NWs.
Tracking electron motion within and outside of Floquet bands from attosecond pulse trains in time-resolved ARPES
Authors: Neufeld Ofer , Hübener Hannes , Giovannini Umberto De , Rubio Angel
Published: February 2024

Floquet engineering has recently emerged as a technique for controlling material properties with light. Floquet phases can be probed with time- and angle-resolved photoelectron spectroscopy (Tr-ARPES), providing direct access to the laser-dressed electronic bands. Applications of Tr-ARPES to date focused on observing the Floquet-Bloch bands themselves, and their build-up and dephasing on sub-laser-cycle timescales. However, momentum and energy resolved sub-laser-cycle dynamics between Floquet bands have not been analyzed. Given that Floquet theory strictly applies in time-periodic conditions, the notion of resolving sub-laser-cycle dynamics between Floquet states seems contradictory—it requires probe pulse durations below a laser cycle that inherently cannot discern the time-periodic nature of the light-matter system. Here we propose to employ attosecond pulse train probes with the same temporal periodicity as the Floquet-dressing pump pulse, allowing both attosecond sub-laser-cycle resolution and a proper projection of Tr-ARPES spectra on the Floquet–Bloch bands. We formulate and employ this approach in ab-initio calculations in light-driven graphene. Our calculations predict significant sub-laser-cycle dynamics occurring within the Floquet phase with the majority of electrons moving within and in-between Floquet bands, and a small portion residing and moving outside of them in what we denote as ‘non-Floquet’ bands. We establish that non-Floquet bands arise from the pump laser envelope that induces non-adiabatic electronic excitations during the pulse turn-on and turn-off. By performing calculations in systems with poly-chromatic pumps we also show that Floquet states are not formed on a sub-laser-cycle level. This work indicates that the Floquet-Bloch states are generally not a complete basis set for sub-laser-cycle dynamics in steady-state phases of matter.
A method of measuring equivalent parameters of quartz crystal resonators
Authors: Wan Yang , Yang Zhuoping , Luan Xinghe , Wu Fengshun
Published: February 2024

Quartz crystal resonators (QCRs) can be described by four parameters in the BVD-equivalent circuit: static capacitance (C
0), motional capacitance (C
1), motional inductance (L
1), and motional resistance (R
1). In this study, we propose a set of formulae through theoretical deduction to evaluate these four parameters using the impedances of QCRs at different frequencies. Using this method, engineers can evaluate the four parameters without theoretical errors in only one frequency sweep. The method has been verified by LTspice simulation. In the simulation, the average error was 0.35%, which demonstrated its correctness. Meanwhile, in practical measurements, compared to the parameters reported by 250B, the parameters calculated using this method demonstrated better fitting ability. Moreover, the calculation process was simple. Therefore, the measuring procedures and apparatus can be simplified using this method.
Spatial coherence research and passive speckle suppression for edge-emitting broad-area semiconductor lasers
Authors: Chen Ao , Zhang WeiQiao , Zhou XuYan , Liu Jing , Zheng WanHua
Published: February 2024

The spatial coherence of filaments in edge-emitting broad-area semiconductor lasers (BALs) is studied based on speckle theory, and a passive speckle suppression method for BALs is demonstrated. A fly-eye lens is used to integrate the filaments and homogenize the laser beam. The speckle contrast is consistent with theoretical calculation, which proves the spatial incoherence of filaments. A light pipe is used to introduce an optical path difference between light with different incident angles, enabling more incoherent beamlets. These beamlets are then combined at different illuminating angles by a double-sided fly-eye lens and focusing lens. As a result, the subjective speckle contrast is reduced from 95.94% to 19.13% at 1.2 A while maintaining a high luminous efficiency of 77.8%. This work provides important design principles for laser display systems.
Meet in person to make breakthroughs, says study
Authors: Hiscott Laura
Published: February 2024

The online world makes it easier for researchers to collaborate – but does not result in more groundbreaking work, finds a new study.
Some thoughts on automation and mathematical research
Authors: Venkatesh Akshay
Published: February 2024

I discuss how mathematicians come to a shared notion of what is important, and how automated reasoning might affect that process.
Quantifying water-use efficiency in plant canopies with varying leaf angle and density distribution
Authors: Ponce de León María A , Bailey Brian N
Published: February 2024

Background and Aims

Variation in architectural traits related to the spatial and angular distribution of leaf area can have considerable impacts on canopy-scale fluxes contributing to water-use efficiency (WUE). These architectural traits are frequent targets for crop improvement and for improving the understanding and predictions of net ecosystem carbon and water fluxes.

Methods

A three-dimensional, leaf-resolving model along with a range of virtually generated hypothetical canopies were used to quantify interactions between canopy structure and WUE by examining its response to variation of leaf inclination independent of leaf azimuth, canopy heterogeneity, vegetation density and physiological parameters.

Key Results

Overall, increasing leaf area index (LAI), increasing the daily-averaged fraction of leaf area projected in the sun direction (Gavg) via the leaf inclination or azimuth distribution and increasing homogeneity had a similar effect on canopy-scale daily fluxes contributing to WUE. Increasing any of these parameters tended to increase daily light interception, increase daily net photosynthesis at low LAI and decrease it at high LAI, increase daily transpiration and decrease WUE. Isolated spherical crowns could decrease photosynthesis by ~60 % but increase daily WUE ≤130 % relative to a homogeneous canopy with equivalent leaf area density. There was no observed optimum in daily canopy WUE as LAI, leaf angle distribution or heterogeneity was varied. However, when the canopy was dense, a more vertical leaf angle distribution could increase both photosynthesis and WUE simultaneously.

Conclusions

Variation in leaf angle and density distributions can have a substantial impact on canopy-level carbon and water fluxes, with potential trade-offs between the two. These traits might therefore be viable target traits for increasing or maintaining crop productivity while using less water, and for improvement of simplified models. Increasing canopy density or decreasing canopy heterogeneity increases the impact of leaf angle on WUE and its dependent processes.
Management of ventricular tachycardias: insights on centre settings, procedural workflow, endpoints, and implementation of guidelines—results from an EHRA survey
Authors: Sultan Arian , Futyma Piotr , Metzner Andreas , Anic Ante , Richter Sergio , Roten Laurent , Badertscher Patrick , Conte Giulio , Chun Julian K R
Published: February 2024

Ventricular tachycardia (VT), and its occurrence, is still one of the main reasons for sudden cardiac death and, therefore, for increased mortality and morbidity foremost in patients with structural heart [Kahle A-K, Jungen C, Alken F-A, Scherschel K, Willems S, Pürerfellner H et al. Management of ventricular tachycardia in patients with ischaemic cardiomyopathy: contemporary armamentarium. Europace 2022;24:538–51]. Catheter ablation has become a safe and effective treatment option in patients with recurrent VT [Cronin EM, Bogun FM, Maury P, Peichl P, Chen M, Namboodiri N et al. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias. Heart Rhythm 2020;17:e2–154]. Previous and current guidelines provide guidance on indication for VT ablation and risk assessment and evaluation of underlying disease. However, no uniform recommendation is provided regarding procedural strategies, timing of ablation, and centre setting. Therefore, these specifics seem to differ largely, and recent data are sparse. This physician-based European Heart Rhythm Association survey aims to deliver insights on not only infrastructural settings but also procedural specifics, applied technologies, ablation strategies, and procedural endpoints. Therefore, these findings might deliver a real-world scenario of VT management and potentially are of guidance for other centres.
The clinical anatomy of the atrioventricular conduction axis
Authors: Sánchez-Quintana Damián , Cabrera Jose-Angel , Anderson Robert H
Published: February 2024

It is axiomatic that the chances of achieving accurate capture of the conduction axis and its fascicles will be optimized by equally accurate knowledge of the relationship of the components to the recognizable cardiac landmarks, and we find it surprising that acknowledged experts should continue to use drawings that fall short in terms of anatomical accuracy. The accuracy achieved by Sunao Tawara (1906) in showing the location of the atrioventricular conduction axis is little short of astounding. Our purpose in bringing this to current attention is to question the need of the experts to have produced such inaccurate representations, since the findings of Tawara have been extensively endorsed in very recent years. The recent studies do no more than point to the amazing accuracy of the initial account of Tawara. At the same time, we draw attention to the findings described in the middle of the 20th century by Ivan Mahaim (1947). These observations have tended to be ignored in recent accounts. They are, perhaps, of equal significance to those seeking specifically to pace the left fascicles of the branching atrioventricular bundle.
Adequacy of health message tailoring for ethnic minorities: Pasifika communities in Sydney, Australia, during COVID-19
Authors: Palu Elizabeth , McBride Kate A , Simmons David , Thompson Ronda , Cavallaro Cassandra , Cooper Ellen , Felila Makeleta , MacMillan Freya
Published: February 2024

Ethnic minorities, such as Pasifika, residing in high-income countries were at higher risk of COVID-19 infection during the pandemic. To understand the experiences of Pasifika, including message dissemination and barriers to tailored public health messaging during the pandemic, a qualitative study was undertaken, underpinned by Laswell’s Model of Communication and Bandura’s social cognitive theory with data collected using Pasifika methods. Pasifika adults (n = 65) were recruited across Sydney from July 2020 to March 2022. Health care professionals (HCP) (n = 17) employed by four local health districts (LHDs) and Pasifika community-based organizations delivering multicultural COVID-19-related work within the study catchment, were also recruited. Five themes were constructed from the data of: (i) prevailing fear and uncertainty over COVID-19 infection and losing employment; (ii) limited knowledge of government perpetuating distrust in Government as a benevolent source of information; (iii) faith and trust as priorities for health decision-making; (iv) ‘Coconut wireless’—the role of family, friends and community in disseminating public health messages through word of mouth; and (v) limited health literacy affecting compliance with public health orders. Community members identified important messages and resources had not been sufficiently distributed. Most HCPs understood the necessity of grassroots-level engagement but reported existing approaches were inadequate to navigate challenges. These findings highlight the need for public health promotion and communication strategies that consider both the social and cultural determinants of health. We propose a 7-point checklist as a cultural appropriateness lens to assist the development and rating of existing or new health promotion messaging and resources.
Exploring settings as social complex adaptive systems in setting-based health research: a scoping review
Authors: Keshavarz Mohammadi Nastaran , Rezaei Zahed , Burggraf Larissa , Pype Peter
Published: February 2024

Since launching health health-promoting settings approach to health by WHO, valuable progress has happened in implementing its holistic concepts in settings such as cities, schools, workplaces, hospitals and healthcare services. However, significant knowledge–intention–success gaps still exist in creating sustainable health-promoting changes in settings. The complexity of the task of bridging this gap has contributed to the call for a complexity-informed paradigm shift to health as well as settings, followed by increasing consultation of relevant complexity theories, frameworks and tools in health research. This paper provides a critical scoping review of the application of complex adaptive system (CAS) theory in settings-based health promotion research. We included 14 papers, mostly qualitative studies, reporting on planning or implementation of change initiatives, less on its evaluation. CAS theory application was often incomplete thereby reducing the potential benefit of using this lens to understand change management. We suggest some recommendations how to comprehensively apply the CAS theory in setting-based health research and to report on all CAS characteristics to enhance the understanding of settings as adaptive health-promoting settings.
A76 COMBINING TOFACITINIB AND USTEKINUMAB FOR REFRACTORY ULCERATIVE COLITIS: A CASE REPORT
Authors: Bucheeri M A , Alabdulkarim B , Wolman S
Published: February 2024

Background

The paradigm for Inflammatory Bowel Disease (IBD) management has shifted towards prioritizing remission of inflammation over symptom control, emphasizing sustained, corticosteroid-free remission at the clinical, endoscopic, and histologic levels. The shift is due to the recognition that uncontrolled inflammation often causes morbidity; after one year of biological therapy, 40% of patients still experience persistent disease activity.

Several approaches have been proposed to address this challenge, including drug level monitoring, dosage titration, antibody screening, and, as a last resort, surgical intervention. Emerging limited studies suggest the potential efficacy of combining two biological agents or a biological agent with small molecules in IBD, contrasting the efficacy and safety concerns encountered with their use in rheumatological diseases.

Aims

To describe a case of successful combination therapy with Tofacitinib and Ustekinumab in refractory Ulcerative Colitis with a review of the current literature.

Methods

This case describes a 35-year-old male patient with severe Ulcerative Colitis refractory to 5-ASA, Azathioprine, Infliximab with Methotrexate, Vedolizumab, Ustekinumab and Tofacitinib. His disease persisted with primary treatment failures requiring hospital admissions and rescuing with parenteral steroids. He was switched back to Ustekinumab with minimal symptom improvement but required repeated steroid courses to achieve control. After deliberations, Tofacitinib was added. This combination achieved remission of his symptoms and inflammatory markers, mainly guided by fecal calprotectin (from 3728 µg/g to 46 µg/g), as well as endoscopic and histologic remission. He is being weaned off the oral budesonide he had been on to augment his response.

Results

After 4 years of combination therapy, he remains in remission with no adverse events or infections.

Reassuringly, Janus Kinase inhibitors (i.e., Tofacitinib) have a short half-life, allowing prompt discontinuation if indicated, especially in the event of infection. Furthermore, biologics such as Vedolizumab, Ustekinumab, and Risankizumab offer minimal systemic immunosuppression and do not appear to raise the risk of infection.

Apart from safety concerns and limited data on the use of combination therapy, significant economic implications exist. However, the attainability of cheaper generic forms of small molecules (e.g., Tofacitinib roughly costs a quarter of the brand price in Ontario, Canada) adds another advantage to their combination use.

Conclusions

Combination therapy with biologics and small molecules is a potential consideration for treating severe or refractory Ulcerative Colitis or IBD. To bridge the knowledge gap regarding combination therapies in IBD, further studies are needed on efficacy, safety, long-term effects, and economic impact.

Funding Agencies

None