bluuebunny/crossref_metadata_2025 huggingface dataset:
3D confinement alters smooth muscle cell responses to chemical and mechanical cues
Authors: Hemmati Farnaz , Akinpelu Ayuba , Nweze Daniel Chinedu , Mistriotis Panagiotis
Published: October 2024

Smooth muscle cell (SMC) phenotypic switching is a hallmark of many vascular diseases. Although prior work has established that chemical and mechanical cues contribute to SMC phenotypic switching, the impact of three-dimensional (3D) confinement on this process remains elusive. Yet, in vivo, arterial SMCs reside within confined environments. In this study, we designed a microfluidic assay to investigate the interplay between 3D confinement and different environmental stimuli in SMC function. Our results show that tightly, but not moderately, confined SMCs acquire a contractile phenotype when exposed to collagen I. Elevated compressive forces induced by hydrostatic pressure abolish this upregulation of the contractile phenotype and compromise SMC survival, particularly in tightly confined spaces. Transforming growth factor beta 1, which promotes the contractile state in moderate confinement, fails to enhance the contractility of tightly confined cells. Fibronectin and engagement of cadherin 2 suppress the contractile phenotype of SMCs regardless of the degree of confinement. In contrast, homophilic engagement of cadherin 11 upregulates SMC-specific genes and enhances contractility in both moderately and tightly confined cells. Overall, our work introduces 3D confinement as a regulator of SMC phenotypic responses to chemical and mechanical signals.
Polymer-doped two-dimensional turbulent flow to study the transition from Newtonian turbulence to elastic instability
Authors: Fukushima Kengo , Kishi Haruki , Sago Ryotaro , Suzuki Hiroshi , Poole Robert J. , Hidema Ruri
Published: October 2024

Detecting the flow regimes of Newtonian turbulence (NT), elasto-inertial filament (EIF), elasto-inertial turbulence (EIT), and maximum drag reduction (MDR) of polymer solution and their transition has been a hot topic in the last decade. We attempted to detect NT, EIF, EIT, and MDR by visualizing vortex shedding downstream of an array of cylinders that was inserted perpendicular to polymer-doped two-dimensional (2D) flow. Since polymers are stretched at the cylinders, the consequent vortex shedding is affected by viscoelasticity. The flow regimes are characterized based on Weissenberg (Wi) and Reynolds numbers (Re) with the relaxation time of the polymeric solution estimated from capillary-thinning experiments. The flow regimes are observed for different molecular weights of polyethylene oxide and polyacrylamide in solution and are categorized as either vortex type 1, type 2, and type 3 on a Re–Wi map based on flow visualization using particle image velocimetry. In addition, turbulent statistics of these flow regimes are calculated to more fully quantify these flow regimes. We found that vortex types from 1 to 3 have a similarity to NT, EIF, EIT, and MDR. In addition, characteristic turbulent energy transfer without an increase in turbulent energy production was found in the flow regimes of vortex types 2 and 3 of each polymer solution. Our results suggest intriguing parallels between pipe, jet, and 2D turbulent flow for drag-reducing polymeric solutions.
Effect of weak intermolecular interactions on the ionization of benzene derivatives dimers
Authors: Lucia-Tamudo Jesús , López-Sánchez Rubén , Nogueira Juan J. , Díaz-Tendero Sergio
Published: October 2024

The interactions between π-systems in dimers of aromatic molecules lead to particularly stable conformations within the relative orientations of the monomers. Extensive research has been conducted on the properties of these complexes in the neutral state. However, in recent decades, there has been a significant surge in applications harnessing these structures for electrical purposes. Therefore, this study places particular emphasis on a deeper understanding of the redox properties of these compounds and how to modify them. To achieve this, we have focused on modeling the effect of a wide range of functional groups on the redox properties of benzene derivatives, observing a correlation between these properties and the change in the molecular dipole moment. Then, we investigated the effect of π-stacking interactions on these properties in dimers formed by either identical or different monomers. In both cases, there is an enhancement of the reducing character of the systems due to these interactions. Upon oxidation, the charge is distributed proportionally to the redox potential of each monomer. Therefore, if there is heterogeneity in these potentials, the properties of the complete cationic system will be influenced by the monomer with a greater tendency to undergo oxidation. The considered models serve as an excellent example for studying the behavior of nucleobases in DNA or aromatic amino acids, among others.
Hydrogen diffusion mechanisms in the 4130X steel: An integrated study with electrochemical experiments and molecular dynamics simulations
Authors: Li Jiaqing , Zheng Zhiye , Yu Xi , Lu Kai , Liang Huilong , Yin Pengbo , Teng Lin , Zhang Che , Deng Guanyu
Published: October 2024

In this work, hydrogen diffusion behavior and mechanisms in the 4130X steel influenced by temperature, locally high concentration, and grain boundary were studied by leveraging both electrochemical hydrogen permeation experiments and molecular dynamics simulations. It was revealed that the hydrogen diffusion coefficient of the 4130X steel was increased with increasing temperature and decreasing locally high hydrogen concentration. The grain boundaries with misorientation below 15° characterized by an electron backscatter diffraction map were identified as hydrogen trapping sites, thus rendering a lower mean square displacement of hydrogen atoms and localized hydrogen diffusion trajectories. Furthermore, at a high hydrogen concentration of 4 at. %, these grain boundaries were saturated by hydrogen atoms, and platelet-like hydrogen clusters were formed within the lattice, which further inhibited the diffusive motion of hydrogen atoms. These findings would deepen our understanding of hydrogen embrittlement mechanisms by establishing the connections between macroscopic permeation behavior and atomic-scale hydrogen diffusion in structural materials.
Limit cycle oscillations in the zonal-flow-catalyzed interactions of ion-temperature-gradient turbulence
Authors: Li P.-Y. , Terry P. W.
Published: October 2024

Limit-cycle oscillations are studied for ion temperature gradient turbulence, which, in the absence of large diamagnetic (mean) shear flows, saturates through energy transfer from unstable modes to large-scale stable modes via zonal-flow intermediary modes. Oscillations of zonal flow and turbulence levels are strongly constrained by the reactive, largely non-dissipative character of the zonal flows. Since existing predator–prey models for observed oscillations in experiments do not include energy transfer through zonal flows to stable modes, low-order fluid models with this physics are constructed and investigated. A simple three-wave truncation produces low-amplitude zonal flows that slowly oscillate around a zero mean, with turbulence oscillations between coupled wavenumbers that exceed linear frequencies by orders of magnitude. This inconsistency with experimental observations is caused by the weak non-linear drive of zonal flows in three-wave systems and the lack of multiple-wavenumber turbulent interactions. A more comprehensive model that preserves multiple wavenumber interactions within the context of conservative zonal-flow-mediated energy transfer to stable modes accurately reflects observed dynamics when the phase between stable and unstable modes is occasionally randomized.
Understanding thickness-dependent stability of tungsten-doped indium oxide transistors
Authors: Kim Hyunjin , Choi Hyun-Sik , Yun Gyungwon , Cho Won-Ju , Park Hamin
Published: October 2024

In this study, the influence of the thickness of the channel layer on the electrical properties and stability of tungsten-doped indium oxide (IWO) thin-film transistors (TFTs) was investigated. Although oxide-semiconductor TFTs, particularly indium gallium zinc oxide, are promising, problems related to oxygen vacancies have led to their instability. In contrast, IWO has proven to be a compelling alternative because of its robust resistance to oxygen vacancies. IWO TFTs with varying channel thicknesses (10, 20, and 30 nm) were fabricated, and the device parameters, such as threshold voltage (Vth), subthreshold swing (SS), field-effect mobility (μFE), and on/off current ratio (Ion/Ioff), were analyzed. It was found that as the channel thickness increased, Vth exhibited a negative shift and SS increased, indicating an increase in carrier concentration. This phenomenon is attributed to the bulk trap density, in particular to oxygen vacancies. Negative bias stress tests confirmed the influence of the oxygen vacancies, with thicker channels showing more pronounced shifts. Low-frequency noise measurements were consistent with the carrier number fluctuation model, indicating that defects within the channel region contribute to the observed noise. The study concludes that identifying an optimal channel thickness during device manufacturing is crucial for improved TFT performance, with 20 nm devices characterized by high μFE and comparable trap density to 10 nm. This study provides valuable insight into the nuanced relationship between the channel thickness, trap density, and electrical performance of IWO TFTs.
Dependence of interfacial mixing for thermally induced magnetization switching in Gd/Fe multilayers
Authors: Jiang Caijian , Liu Donglin , Song Xinyu , Xu Chudong
Published: October 2024

The use of femtosecond laser pulses for ultrafast triggering of magnetization switching is of great interest in multilayer systems with great tunability. At present, the impact of interfacial mixing on magnetization switching has not been thoroughly investigated. In this paper, the impact of interfacial mixing on magnetization dynamics in multilayer systems is investigated by a combination of atomic spin dynamics and two-temperature models. Our results show that interfacial mixing in multilayer systems not only reduces the energy density required for magnetization switching but also expands the range of pulse durations that can trigger magnetization switching. In addition, we have investigated the dependence of the switching time on the interfacial mixing in multilayer systems. The results show that interfacial mixing can accelerate the process of magnetization dynamics, thus providing a theoretical basis for the design of faster speed optically controlled magnetic tunnel junctions.
Environmental impact of waste plastic oil and hydrogen-enriched diesel engines: A comprehensive review on performance, combustion, and emissions
Authors: Sanyal Amit , Choudhary Akhilesh Kumar
Published: October 2024

This review focuses on the sustainable use of waste plastic by converting it into waste plastic oil (WPO) through catalytic pyrolysis. The primary objective is to explore the potential of WPO, derived from used polyethylene terephthalate bottles, as an alternative fuel for diesel engines. This review also evaluates WPO's physical and chemical properties, revealing that it possesses fuel attributes similar to those of petroleum-based fuels. Catalytic pyrolysis is employed on a laboratory scale, using catalysts such as silica, Zeolite Socony Mobil-5 (ZSM-5), alumina, and kaolin to extract WPO from mixed waste plastics. However, direct use of WPO in diesel engines has shown drawbacks, including significant combustion delays and increased emissions. To address these issues, this review suggests blending WPO with diesel fuel rather than using it as a standalone fuel. Furthermore, the review explores hydrogen enrichment in WPO blends to improve combustion efficiency. Hydrogen enrichment enhances thermal efficiency and reduces environmental emissions, showing potential for improved performance and lower brake-specific fuel consumption. This review presents a comparative analysis of various WPO blends with hydrogen enrichment, highlighting the benefits of incorporating hydrogen to boost combustion and performance. Although promising, further research is needed to ensure the sustainability and effectiveness of WPO blends as a long-term energy source.
Acoustic metagrating focusing and Bessel vortexes
Authors: Zhao Ke-qi , Zou Hong-yu , Xia Yu-han , Wu Cheng-hao , Xu Le-yang , Ge Yong , Yuan Shou-qi , Sun Hong-xiang
Published: October 2024

Acoustic focusing and Bessel vortexes have great potential in medical ultrasound, particle trapping, and information processing. Based on the generalized Snell's law (GSL), metasurface focusing and Bessel vortexes were achieved by using in-plane phase profiles to shape wavefronts. Recent developments in acoustic metagratings (AMs) have demonstrated an extension of the GSL capable of switching transmitted and reflected vortexes that are determined by the parity of the number of wave propagation trips. However, these metagratings were designed with a certain one-dimensional phase gradient along the azimuthal direction, and the propagation of vortexes were generally fixed into cylindrical waveguides owing to energy divergence. The propagation and manipulation of acoustic vortexes in three-dimensional (3D) free space, caused by AMs with two-dimensional (2D) aperiodic phase gradients, still pose a great challenge. Here, we experimentally demonstrate two types of switchable acoustic lenses with focusing and Bessel vortexes. Based on the GSL extension, by separating and attaching 2D dual-layer aperiodic AMs in both lenses, the switch between the reflected focusing vortex and transmitted focusing/Bessel vortex with the same focus length and topological charge in 3D free space can be observed. The designed dual-layer AMs can realize the short-range and long-range focusing vortexes in 3D free space and also have the advantage of convenient function switching, which may pave the way for designing switchable focusing vortex lenses with practical applications.
Spatiotemporal coupling deep neural network for time-resolved flow field reconstruction around a circular cylinder
Authors: Jin Xiaowei , Xu Mengjie , Yang Yefei , Chen Wenli
Published: October 2024

We propose a spatiotemporal coupling deep neural network approach for time-resolved reconstruction of the velocity field around a circular cylinder. The neural network leverages two distinct data types: (1) non-time-resolved velocity field around the cylinder, consisting of fixed frequency sampling and variable frequency sampling velocity field, and (2) the time-resolved surface pressure sequence around the cylinder. The deep neural network comprises two sub-networks: a convolutional autoencoder (CAE) for nonlinear mode extraction and a Transformer for sequence-to-sequence learning. We refer to this architecture as CTNet (CAE-Transformer Network). The encoder in the CAE maps non-time-resolved velocity field to a latent vector, enabling the extraction of nonlinear modal coefficients. An appropriate time window length for the surface pressure sequence is then selected to establish a Transformer sequence learning model, using the chosen sequence as input to predict the corresponding nonlinear modal coefficients. Once the Transformer is well trained, the time-resolved nonlinear modal coefficients of velocity field can be achieved. Along with the well-trained decoder in the CAE, the time-resolved velocity field can be reconstructed from the output of the Transformer. We verify the performance of CTNet by a simulated dataset at a representative Reynolds number of 3900. The results show a relative reconstruction error of just 6.3% for the time-resolved velocity field, demonstrating high reliability in the reconstruction. We further compare the reconstructed velocity field obtained with and without the utilization of variable frequency sampling velocity field. Notably, the inclusion of variable frequency sampling velocity field significantly improves the reconstruction quality.
On the focusing effect and interfacial evolution of incident shock waves impinging on double-layer nested heavy gas bubbles
Authors: Jin Yong , Li Runze , Zhang Yi , Zhu Yuejin
Published: October 2024

A detailed numerical study about the planar incident shock wave impinging on heavy bubbles with different components and nested structures was conducted. Results show that the shock wave convergence occurs when the incident shock wave impinging on the pure SF6 bubble or CO2-SF6 nested bubbles, which triggers the shock wave focusing and obtains a high transient pressure. Changing the nested position and radius of the SF6 bubble in CO2-SF6 nested bubbles will change the interactional time and relative position of waves to affect the shock wave focusing time and peak pressure. Specifically, the shock wave focusing effect is enhanced, and the peak pressure is increased when the inner bubble is drifted downstream, high density, and larger sized. Thus, the later the shock wave focusing occurs, the higher the transient maximum pressure. The shock wave focusing process of double-layer nested bubbles is presented as follows: the new small shock wave (SS) formed by the intersection between the incident transmitted shock wave and the transmitted shock wave and another new shock wave formed by the collision of diffracted transmitted shock waves move in opposite directions to squeeze the undisturbed region and finally produce a high instantaneous pressure, where SS plays a major role in shock wave focusing. Further, the greater the intensity and velocity of focusing shock waves, the stronger the focusing effect and the higher the transient pressure.
Swirl-induced hysteresis in a sudden expansion flow
Authors: Holemans T. , Yang Z. , De Greef J. , Vanierschot M.
Published: October 2024

Swirling sudden expansion flows are complex flow fields containing several coherent structures that depend on the swirl number and can exhibit hysteresis behavior between increasing and subsequently decreasing swirl levels. While these flows have extensively been studied in simple geometries, results involving special designed nozzles are scarce. Therefore, this paper aims to provide insights into a more complex geometry, specifically a two-step conical expansion with a converging outlet. Experimental data is acquired for changing swirl numbers at a Reynolds number in the range of 35, 000. Stereoscopic Particle Image Velocimetry is employed to characterize downstream flow structures, while Laser Doppler Velocimetry is used to characterize upstream structures and to determine the inlet swirl number. Several distinct flow patterns are found as a function of the swirl number and the identified flow patterns include, in order of increasing swirl, a Closed Jet Flow, an Open Jet Flow (OJF), and a Coandã Jet Flow (CoJF). A central positive axial velocity is noted for both OJF and CoJF downstream of the expansion due to the converging outlet geometry. At higher swirl numbers, Vortex Breakdown moves upstream into the nozzle until a negative axial velocity is noted in the inlet tube. For these higher swirl numbers, no hysteresis is observed in the inlet tube between increasing and subsequently decreasing swirl. However, downstream of the nozzle, it is observed that the CoJF detaches at a lower swirl number than the swirl number required for attachment, indicating a hysteresis effect between in- and decreasing swirl.
Spectral proper orthogonal decomposition analysis of a spatially developing underexpanded round jet at Re = 45 000
Authors: Wang Rui , Wu Feng , Fei Haoqi , Wang Xiaojing , Xu Hui
Published: October 2024

This study conducts a comprehensive analysis of the coherent structures within a spatially developing underexpanded axisymmetric jet at a Reynolds number of 45 000, utilizing high-fidelity implicit large eddy simulations (iLES) in conjunction with spectral proper orthogonal decomposition (SPOD). In the frequency–wavenumber space, the global SPOD analysis identifies three distinct coherent structures, corresponding to three different mechanisms, namely, Kelvin–Helmholtz (KH), Orr, and lift-up. Their salient characteristics are discussed in detail. Local SPOD analysis further explores the streamwise evolution of these coherent structures, revealing that the influence of KH mechanism is confined to the near field, while the lift-up mechanism persists and dominates the energy content beyond the potential core, with the streaks of azimuthal wavenumbers one and two being the most energetic. The reconstruction of turbulent kinetic energy (TKE) and Reynolds shear stress from SPOD modes is assessed, and the first few azimuthal modes with low wavenumbers and frequencies are found crucial for capturing the dominant features of the flow. It is found that only the m = 0 and m = 1 modes contribute to the TKE at the centerline. The Reynolds shear stress reconstruction quality is comparable to TKE, but with a negligible contribution from the m = 0 mode. The azimuthal mode m = 1 captures the slope of the actual Reynolds shear stress profile in the vicinity of centerline, while m = 2 and higher modes capture the peak location of the actual profile.
Giant and robust thermal nonreciprocity in a fluid–solid multiphase circulator
Authors: Qiu Yuguang , Yang Fubao , Huang Jiping , Xu Liujun
Published: October 2024

Nonreciprocal heat transfer is crucial for modern energy utilization and conversion. Rotational bias in circulators made of fluid or solid monophase materials enables thermal nonreciprocity at two output ports. However, sensitivity to multiple factors like port position and circulator radius necessitates precise rotational bias, making giant thermal nonreciprocity fragile. Here, we propose a fluid–solid multiphase circulator by incorporating a solid rotating ring into a fluid circulator. The rotation speed flexibly controls the heat exchange ratio between the fluid–solid interface. Giant thermal nonreciprocity is obtained when the solid and fluid speeds are nearly synchronized, yielding distinctly different temperature amplitudes at two output ports. The rectification ratio robustly reaches the maximum due to its independence of port position and circulator radius. These findings also apply to more ports and other diffusion domains like mass transport, inspiring a fluid–solid hybrid paradigm for diffusion regulation.
Mechanistic study of β-Ga2O3 nitridation by RF nitrogen plasma for GaN heteroepitaxy
Authors: Landi Matthew M. , Kelly Frank P. , Vesto Riley E. , Kim Kyekyoon
Published: October 2024

The transformation of 2¯01β-Ga2O3 to h-GaN under exposure to RF nitrogen plasma was monitored in situ by reflection high-energy electron diffraction. Analysis of the reaction kinetics reveals that the nitridation process is initiated by the formation of an oxynitride phase and proceeds via two-dimensional nucleation and growth of wurtzite GaN grains. X-ray photoelectron spectra suggest a Ga−(NxO1−x) type configuration dominates the surface early in the nitridation process. The surface restructuring is followed by a diffusion-fed phase transformation, which propagates the wurzite GaN structure into the substrate upon reaching 70% nitrogen anion site occupation, corresponding to the oxygen solubility in h-GaN. A direct correlation is observed between the nitridated film morphology and the epitaxial film crystallinity, demonstrating control of the residual strain, lateral coherence, and mosaicity in subsequent GaN epitaxy by the nitridation conditions. This study provides mechanistic details of the nitridation reaction of 2¯01β-Ga2O3 facilitating the optimization of the nitridation process toward improving GaN-2¯01β-Ga2O3 heterojunctions.
Phonon-charge carrier dynamics via grain-boundary phase in equilibrium reaction of higher manganese silicide/CNF hybrid composites
Authors: Vijay V. , Karuna J. , Archana J. , Navaneethan M.
Published: October 2024

Higher manganese (TE) silicide (HMS), an eco-friendly, low-cost, and earth-abundant p-type thermoelectric material, exposes a Nowotny chimney-ladder crystal structure, obeying the 14th-electron rule. Here, a hybrid composite of a carbon nanofiber (CNF) and HMS was synthesized by vacuum melting followed by spark plasma sintering, and its thermoelectric performance were demonstrated. The incorporation of CNF with HMS notably enhances the Seebeck coefficient and decline the thermal conductivity without significantly affecting the carrier concentration and electrical conductivity due to the interfacial energy filtering effect. A maximum Seebeck coefficient of 307 μV/K was recorded for the 0.5% CNF composite with HMS, leading to accomplish a high-power factor of 1755.63 μW/mK2 at 803 K. Also, interfaces, grain boundaries, and dislocations leading to the high magnitude of strain, confirmed from HR-TEM and strain analysis, leads to decrease in lattice thermal conductivity to 1.95 W/mK. As a result, HMS attains the peak zT value of 0.64, suggesting that carbon-based composites are a promising way to boost the thermoelectric performance of HMS-based compounds.
Thermistors and stacked thermopile on III-nitride LED wafer and their application for on-chip temperature measurement
Authors: Tong Jing , Yan Jiabin , Fang Li
Published: October 2024

Temperature measurement of devices in working state is of critical importance. In this work, GaN-based thermistors and a thermopile are monolithically integrated with a III-nitride blue light-emitting diode (LED) for the on-chip temperature measurement of the LED. The thermistor is based on the temperature-dependent resistance, and the stacked thermopile is based on the Seebeck effect. The measured results indicate that both thermistors and the thermopile can monitor the temperature of the LED sensitively. Due to the advantages of higher sensitivity and easier signal processing, the thermopile is more suitable for real-time monitoring.
Vortex-induced vibration and energy harvesting of cylinder system with nonlinear springs
Authors: Zhang Xinsheng , Chen Dongyang , Tang Ye , Lin Yaochen , Liu Jing , Pan Guang
Published: October 2024

Vortex-induced vibration is a common fluid–structure coupling phenomenon in ocean engineering. As a nonlinear stiffness structure caused by anisotropic deformation and support gap, nonlinear spring is of great significance in the field of vortex-induced vibration. Based on the structural dynamics equations and the wake oscillator model, the vibration model of the 2-Degree of Freedom cylinder system with the nonlinear stiffness spring is established. The stiffness ratio, mass ratio, and damping ratio of the cylinder system are changed, and the amplitude and frequency response are analyzed to obtain the effect of nonlinear spring on vortex-induced vibration. The results show that the cylinder system with a nonlinear stiffness spring can maintain a high vibration amplitude in a large Reynolds number range, and the smaller the mass ratio, the more significant the effect is. When m*=1.5, the amplitude of the cylinder system in a cross flow is greater than 0.6 at Re = 180 000–480 000. The energy harvesting in the vortex-induced vibration of cylinder systems with nonlinear stiffness springs is also studied. The efficiency depends on the damping ratio and Reynolds number. When the damping ratio is constant, the energy harvesting efficiency increases first and then decreases with the Reynolds number increases. When m*=1.5, the energy harvesting efficiency of the cylinder system is 19.27% with Re= 35 000 and damping ratio ξ=0.155. As a kind of renewable energy, energy harvesting in vortex-induced vibration is a potential development direction in the future energy field.
In situ monitoring of quantum dot growth using a magnification inferred curvature method
Authors: Kwoen J. , Arakawa Y.
Published: October 2024

The growth of InAs on a GaAs (001) substrate follows the Stranski–Krastanov (S–K) growth mode. Initially, the stress due to the lattice constant difference is small, resulting in two-dimensional growth. However, as the thickness of the growth layer increases, this stress accumulates, and upon reaching a critical film thickness, the growth transitions to three-dimensional, facilitating stress relaxation. Strain changes during crystal growth can be observed through variations in substrate curvature. However, in InAs/GaAs quantum dots (QDs), these changes are minimal, making observation challenging. Previously, the curvature of the substrate during InAs/GaAs QD formation could only be estimated with low precision, necessitating the use of very thin substrates with cantilever structures to achieve higher curvature. In this study, we applied the magnification inferred curvature (MIC) method, which allows for high-precision estimation of substrate curvature during molecular beam epitaxy growth. This method enabled us to observe strain changes during the formation and relaxation processes of QDs on standard-thickness GaAs (001) substrates. The results highlight the potential of the MIC method in investigating the complex interplay of strain and stress in semiconductor growth processes, emphasizing its suitability for fabricating next-generation QD devices.
Determination of the particle size distribution of cube-shaped colloidal perovskite quantum dots from photoluminescence spectra: A combined theoretical–experimental approach
Authors: Ferreira Diego Lourençoni , Silva Andreza Germana , Schiavon Marco Antônio , Vivas Marcelo Gonçalves
Published: October 2024

A theoretical–experimental approach is proposed to convert the photoluminescence spectra of colloidal perovskite quantum dot ensembles into accurate estimates for their intrinsic particle size distribution functions. Two main problems were addressed and properly correlated: the size dependence of the first excitonic transition in a single cube-shaped quantum dot and the inhomogeneous broadening of the fluorescence line shape due to the size nonuniformity of the chemically prepared quantum dot suspension in addition to the single-dot homogeneous broadening. By applying the reported methodology to CsPbBr3 quantum dot samples belonging to the strong and intermediate confinement regimes, the calculated size distributions exhibited close agreement with those obtained from transmission electron microscopy, with precise estimates for the average particle size and standard deviation. Specifically for strongly confined ultrasmall CsPbBr3 quantum dots, the presented spectroscopic model for size distribution computation is based on a new analytical expression for the size-dependent bandgap, which was developed within the framework of the finite-depth square-well effective mass approximation accounting for band nonparabolicity effects. Such a quantum mechanical approach correctly predicts the expected transition to the intermediate confinement regime in sufficiently large quantum dots, which are traditionally described by the well-known bandgap equation in the infinite potential barrier limit with a spatially correlated electron–hole wavefunction and nonparabolic carrier effective masses. The proposed calculation scheme originates from general theoretical considerations so that it can be readily adapted to semiconductor quantum dots of many other systems, from all inorganic metal halides to hybrid perovskite materials, regardless of the adopted chemical synthesis route.
New results on the motion of interfaces of multi-layer radial Hele-Shaw flows
Authors: Daripa Prabir , Gin Craig
Published: October 2024

We study the dynamical system arising from the linear stability analysis of multi-layer radial Hele-Shaw flows with time-dependent injection rates. An analysis of the system provides conditions under which the disturbances on all interfaces either monotonically decrease or monotonically increase. Additionally, we show that in any multi-layer radial Hele-Shaw flow, if all of the interfaces are circular initially except for one perturbed interface then there exists a time-dependent injection rate such that the circular interfaces remain circular as they propagate and the disturbance on the perturbed interface decays. The motion of the interfaces is also investigated numerically by integrating the dynamical system for the case of constant and time-independent injection rates. This reveals some very interesting dynamics of interfaces in multi-layer flows. It is found that: (i) A disturbance of one interface can be transferred to the other interface(s); (ii) The disturbances on the interfaces can develop either in phase or out of phase from any arbitrary initial disturbance; and (iii) The dynamics of the flow can change dramatically with the addition of more interfaces. With time-dependent injection rate, there are more possibilities. In particular it is shown that an appropriate injection rate can result in a stable configuration, which consists of all perfectly circular interfaces except for one that is perturbed with a monochromatic wave of infinitesimal amplitude. The prescribed injection rate results in the perturbation decaying even if the configuration (i.e., the setup consisting of all but one circular interface and one perturbed circular interface) itself is unstable to disturbances on any one or more of the circular interfaces. However, it may not be without a challenge to realize such a flow in practice.
Anion regulation for surface passivation enables ultrahigh-stability perovskite nanocrystals
Authors: Zhang Tong , Zu Yanqing , Zeng Binglin , Gan Run , Liu Peitao , Li Xiaodong , Han Fengbo , Qian Yu , Zhao Lei , Feng Ailing , Wu Zhaoxin
Published: October 2024

All-inorganic perovskite CsPbBr3 nanocrystals (NCs) display high photoluminescence quantum yield and narrow emission, which show great potential application in optoelectronic devices. However, the poor environment stability of NCs will hinder their practical application. Herein, a series of ionic liquids with different anions (BF4−, Br−, and NO3−) were used as a sole capping ligand to synthesize NCs. Among the three samples, 1-hexadecyl-3-methylimidazolium tetrafluoroborate ([C16MIM]BF4) capped NCs have the highest stability in light, thermal, and water, possibly attributing to the in situ passivation of bromine vacancy via pseudohalogen BF4− and tight binding of ionic liquid ligands and lead atoms. In addition, green-emission [C16MIM]BF4 NCs were used to assemble a white light-emitting diode device, and it possessed a wide National Television System Committee color gamut of 124.5% and a stable emission peak at high driving currents of 380 mA. This work paves the way for resurfacing perovskite NCs with ultrahigh stability, thereby driving the perovskite NC display industry closer to real-world application.
Evaporation of stable microemulsion droplets
Authors: Krishan Bal , Rastogi Preetika , Rao D. Chaitanya Kumar , Kaisare Niket S. , Basavaraj Madivala G. , Basu Saptarshi
Published: October 2024

Emulsion fuels have the potential to reduce both particulate matter and NOx emissions and can potentially improve the efficiency of combustion engines. However, their limited stability remains a critical barrier to practical use as an alternative fuel. In this study, we explore the evaporation behavior of thermodynamically stable water-in-oil microemulsions. The water-in-oil microemulsion droplets prepared from different types of oil were acoustically levitated and heated using a continuous laser at different irradiation intensities. We show that the evaporation characteristics of these microemulsions can be controlled by varying water-to-surfactant molar ratio (ω) and volume fraction of the dispersed phase (ϕ). The emulsion droplets undergo three distinct stages of evaporation, namely preheating, steady evaporation, and unsteady evaporation. During the steady evaporation phase, increasing ϕ reduces the evaporation rate for a fixed ω. It is observed that the evaporation of microemulsion is governed by the complex interplay between its constituents and their properties. We propose a parameter (η) denoting the volume fraction ratio between volatile and nonvolatile components, which indicates the cumulative influence of various factors affecting the evaporation process. The evaporation of microemulsions eventually leads to the formation of solid spherical shells, which may undergo buckling. The distinction in the morphology of these shells is explored in detail using scanning electron microscopy imaging.
A high-performance selenium nanoflake-based avalanche photodetector
Authors: Liu Handa , Huang Haoxin , Xia Yunpeng , Zhang Han , Wang Huide , Zha Jiajia , Tan Chaoliang
Published: October 2024

Photodetectors are now indispensable in our daily lives, and there is a pressing need to explore new materials and mechanisms that can push the boundaries of device performance. Two-dimensional (2D) van der Waals (vdW) semiconductors have emerged recently as a promising material platform with exceptional optoelectronic properties, making them particularly suitable for high-performance photodetectors. However, photoinduced carrier generation in conventional 2D vdW photodetectors are usually limited, and new mechanisms need to be introduced to enhance device performance. Herein, we report a high-performance avalanche photodetector based on selenium (Se) nanoflakes. Our device achieves a high photoresponsivity (R) and specific detectivity (D*) of 361 A·W−1 and 2.4 × 1012 Jones, respectively. These figures of merit are two orders of magnitude higher than that in conventional Se photoconductive photodetectors. As a large bandgap vdW semiconductor, the Se channel allows the application of an extremely large bias voltage across it, and the resulting high electric field leads to the avalanche multiplication of carriers, which lays the groundwork for the improved device performance.
Hole diffusion length and mobility of a long wavelength infrared InAs/InAsSb type-II superlattice nBn design
Authors: Soibel Alexander , Ting David Z. , Khoshakhlagh Arezou , Bouschet Maxime , Fisher Anita M. , Pepper Brian J. , Gunapala Sarath D.
Published: October 2024

We demonstrated high-performance 8.9 μm cutoff wavelength nBn InAs/InAsSb type-II strained-layer superlattice (T2SL). These detectors exhibit a long minority carrier (hole) lifetime of 1.2 μs at 80 K, high quantum efficiency of 40% for back-side illuminated devices without antireflection coating, and low dark current density of 4.6 × 10−6 A/cm2 at 80 K. We measured absorption, minority carrier (hole) lifetime, quantum efficiency, and spectral response as a function of the temperature and applied bias. We investigated the temperature dependence of the hole diffusion length and mobility and found that their values increase with temperature from 1.3 μm and 6.5 cm2/Vs at 30 K to 6.5 μm and 36 cm2/Vs at T = 90 K. We compared the measured diffusion length and mobility of holes in long-wavelength infrared (LWIR) T2SL with these parameters of a high-performance mid-wavelength infrared (MWIR) T2SL. Unexpectedly, hole mobility in LWIR T2SL was found to be higher than in MWIR that is contrary to the theoretical predictions.
Three-dimensional resonant sloshing in an upright cylindrical container with a ring baffle
Authors: Liu Dongxi , Chang Fangyuan , Wang Jin
Published: October 2024

The effect of ring baffles on suppressing the three-dimensional (3D) resonant sloshing in an upright cylindrical container is experimentally investigated. The main objectives of this work are to examine the effectiveness of various baffle configurations, to establish the stability boundaries of the stable steady-state waves in the unbaffled and baffled containers, to provide accurate experimental data for the verification of the analytical and numerical models, and to prompt future investigations. For this purpose, hundreds of sloshing experiments are conducted in a cylindrical container with or without a ring baffle. An analytical potential-flow solution and an asymptotic multimodal method are used to elucidate the experimental results. It is found that the vertical location of the ring baffle has small influence on the fundamental natural frequency of the system; however, it has a significant influence on the viscous damping and the damping rate increases gradually with the ascension of the baffle. When the distance between the baffle and the free liquid surface is sufficiently large, the system exhibits three types of resonant wave patterns, namely stable planar, stable swirling, and irregular chaotic. These wave patterns are qualitatively and quantitatively similar to those in the unbaffled container. When the baffle is near the free liquid surface, neither the chaotic waves nor the swirling waves take place, but a new wave pattern with the characteristic of multiple wave crests is observed. Probably, this is the first time that the 3D resonant sloshing in the baffled cylindrical container has been systematically investigated.
Review of Scientific Instruments New Products
Authors: Mandelis Andreas
Published: October 2024

In order to supplement manufacturers’ information, this department will welcome the submission of brief communications by our readers reporting measurements on the physical properties of materials that supersede earlier data or suggest new research applications.
Unmasking the polygamous nature of quantum nonlocality
Authors: Cieśliński Paweł , Knips Lukas , Kowalczyk Mateusz , Laskowski Wiesław , Paterek Tomasz , Vértesi Tamás , Weinfurter Harald
Published: October 2024

Quantum mechanics imposes limits on the statistics of certain observables. Perhaps the most famous example is the uncertainty principle. Similar trade-offs also exist for the simultaneous violation of multiple Bell inequalities. In the simplest case of three observers, it has been shown that if two observers violate a Bell inequality, then none of them can violate any Bell inequality with the third observer, a property called monogamy of Bell violations. Forms of Bell monogamy have been linked to the no-signaling principle, and the inability of simultaneous violations of all inequalities is regarded as their fundamental property. Here, we show that the Bell monogamy does not hold universally and that in fact the only monogamous situation exists for only three observers. Consequently, the nature of quantum nonlocality is truly polygamous. We present a systematic methodology for identifying quantum states, measurements, and tight Bell inequalities that do not obey the monogamy principle for any number of more than three observers. The identified polygamous inequalities enable any subset of

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observers to reveal nonlocality, which is also shown experimentally by measuring Bell-type correlations of six-photon Dicke states. Our findings may be exploited for multiparty quantum key distribution as well as simultaneous self-testing of multiple nodes in quantum networks.
Post-editing neural machine translation in specialised languages
Authors: Kübler Natalie , Martikainen Hanna , Mestivier Alexandra , Pecman Mojca
Published: October 2024

This study focuses on phraseology in specialised texts and on students’ difficulties pertaining to
phraseology in post-editing neural machine translation output. It is undertaken within the corpus-based methodological
framework that we have developed for several purposes, one of which being to assess the impact of corpus use on
translation and post-editing. The objective of the study is to propose a descriptive analysis of typical student
errors related to phraseology in order to design tailored pedagogical materials. We aim to show that, with consistent
training in querying corpora and in interpreting results in an appropriate manner, students can manage to improve
their productions when translating specialised texts or when post-editing machine translation output.
The middle construction and some machine translation issues
Authors: Gutiérrez Macarena Palma
Published: October 2024

This paper aims at exploring the colloconstructional analysis of multiword units (MWU) in machine
translation regarding the middle construction in terms of compositional cospecification (Yoshimura, 1998; Yoshimura & Taylor, 2004). For
that purpose, I examine the Adverb + Verb collocation focusing on the predicates cut and
drive, collocated with quality-oriented adjuncts (Heyvaert,
2003) and incorporating Inanimate Subject entities (Patients, Enablers and Instruments). The number of
instances examined is 500+. The data analysed reveals that apart from the generalised Qt-Qc pattern
in shift of semantic importance, other patterns (namely, Qc-Qc) can be found by virtue of the
prototype effects of the construction (cf. Taylor, 1995), thus, providing a
potential source of disambiguation in the computational treatment of MWU in machine translation.
English Prosody in First and Second Language Speakers
Authors: McClellan Karin
Published: October 2024

Discover the intricate dynamics of L2 prosody with this pioneering study, which examines how advanced learners from Czech, German, and Spanish backgrounds engage with British and American English intonation. By employing a multidimensional approach - spanning phonetic, phonological, discourse-pragmatic, and sociolinguistic perspectives - this book provides a comprehensive overview of L2 prosodic features, highlighting patterns of intonational phrasing, f0 range, and the use of tones and uptalk. Building on foundational works by Pierrehumbert, Mennen, and Gut, this work bridges significant gaps in the field by comparing different L1 and L2 varieties, integrating diverse linguistic variables, and proposing a multifactorial model of L2 prosody. Relevant for linguists, language educators, and researchers in SLA, the findings offer valuable insights for reducing foreign accents and enhancing intelligibility, making it an essential resource for improving language teaching methodologies and learner outcomes. Dive into this essential guide and elevate your understanding of L2 prosody and its impact on effective communication.
Chapter 1. Building a comparable corpus of online discussions on Wikipedia
Authors: Ho-Dac Lydia-Mai
Published: October 2024

This chapter presents the EFG WikiCorpus, a corpus composed of all the talk pages dedicated to (co)writing an article in the English, French and German Wikipedias. This chapter explains the place of talk pages in Wikipedia and describes what is the basic structure of a talk page before detailing the building process of the EFG WikiCorpus: from the Wikipedia archives to a TEI resource encoded according to the TEI CMC-core schema. It concludes with a quantitative overview of the EFG WikiCorpus and the EFG WikiDemoCorpus, a derived subcorpus used for qualitative analyses in various contributions of this volume.
Chapter 6. Exploring the evolution of Wikipedia articles through Contropedia
Authors: Laniado David , Mauri Michele , Borra Erik
Published: October 2024

Wikipedia is not just a corpus of encyclopedic articles; it also includes an entire edit history that details the evolution of each article. However, such records are often unknown to the general public, and too complex for researchers to use. Contropedia uses innovative techniques to allow for the visualization, exploration and investigation of the evolution of Wikipedia articles and disputes about their content. This chapter introduces Contropedia and provides an in-depth analysis of two articles from the WikiDemoCorpus: the English language article ‘Chiropractic’ and a multilingual comparison of articles on the European migration crisis. These use cases illustrate Contropedia’s visual and analytical modules for analyzing controversies within an article and for cross-cultural comparison.