bluuebunny/crossref_metadata_2025 huggingface dataset:
The red giant branch tip in the SDSS, PS1, JWST, NGRST, and Euclid photometric systems
Authors: Bellazzini M. , Pascale R.
Published: August 2024

We used synthetic photometry from Gaia DR3 BP and RP spectra for a large selected sample of stars in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) to derive the magnitude of the red giant branch (RGB) tip for these two galaxies in several passbands across a range of widely used optical photometric systems, including those of space missions that have not yet started their operations. The RGB tip is estimated by fitting a well motivated model to the RGB luminosity function (LF) within a fully Bayesian framework, allowing for a proper representation of the uncertainties of all the involved parameters and their correlations. By adopting the best available distance and interstellar extinction estimates, we provide a calibration of the RGB tip as a standard candle for the following passbands: Johnson-Kron-Cousins I (mainly used for validation purposes), Hubble Space Telescope F814W, Sloan Digital Sky Survey i and z, PanSTARRS 1 y, James Webb Space Telescope F090W, Nancy Grace Roman Space Telescope Z087, and Euclid IE, with an accuracy within a few per cent, depending on the case. We used theoretical models to explore the trend of the absolute magnitude of the tip as a function of colour in the different passbands (beyond the range spanned by the LMC and SMC), as well as its dependency on age. These calibrations can be very helpful to obtain state-of-the-art RGB tip distance estimates to stellar systems in a very large range of distances directly from data in the natural photometric system of these surveys and/or missions, without recurring to photometric transformations. We have made the photometric catalogues publicly available for calibrations in additional passbands or for different approaches in the estimate of the tip, as well as for stellar populations and stellar astrophysics studies that may take advantage of large and homogeneous datasets of stars with magnitudes in 22 different passbands.
Detection of a new sample of Galactic white dwarfs in the direction of the Small Magellanic Cloud
Authors: Sidharth A. V. , Shridharan B. , Mathew B. , Devaraj A. , Cysil T. B. , Stalin C. S. , Arun R. , Bhattacharyya S. , Kartha S. S. , Robin T.
Published: August 2024

Aims. In this study, we demonstrate the efficacy of the Ultraviolet Imaging Telescope (UVIT) in identifying and characterizing white dwarfs (WDs) within the Milky Way Galaxy.

Methods. Leveraging the UVIT point-source catalogue towards the Small Magellanic Cloud and cross-matching it with Gaia DR3 data, we identified 43 single WDs (37 new detections), 13 new WD+main-sequence candidates, and 161 UV bright main-sequence stars by analysing their spectral energy distributions. Using the WD evolutionary models, we determined the masses, effective temperatures, and cooling ages of these identified WDs.

Results. The masses of these WDs range from 0.2 to 1.3 M⊙ and the effective temperatures (Teff) lie between 10 000 K to 15 000 K, with cooling ages spanning 0.1–2 Gyr. Notably, we detect WDs that are hotter than reported in the literature, which we attribute to the sensitivity of UVIT. Furthermore, we report the detection of 20 new extremely low-mass candidates from our analysis. Future spectroscopic studies of the extremely low-mass candidates will help us understand the formation scenarios of these exotic objects. Despite limitations in Gaia DR3 distance measurements for optically faint WDs, we provide a crude estimate of the WD space density within 1kpc of 1.3 × 10−3 pc−3, which is higher than previous estimates in the literature.

Conclusions. Our results underscore the instrumental capabilities of UVIT and anticipate forthcoming UV missions such as INSIST for systematic WD discovery. Our method sets a precedent for future analyses in other UVIT fields to find more WDs and perform spectroscopic studies to verify their candidacy.
The boring history of Gaia BH3 from isolated binary evolution
Authors: Iorio Giuliano , Torniamenti Stefano , Mapelli Michela , Dall’Amico Marco , Trani Alessandro A. , Rastello Sara , Sgalletta Cecilia , Rinaldi Stefano , Costa Guglielmo , Dahl-Lahtinen Bera A. , Escobar Gastón J. , Korb Erika , Vaccaro M. Paola , Lacchin Elena , Mestichelli Benedetta , Di Carlo Ugo N. , Spera Mario , Arca Sedda Manuel
Published: August 2024

Gaia BH3 is the first observed dormant black hole (BH) with a mass of ≈30 M⊙, and it represents the first confirmation that such massive BHs are associated with metal-poor stars. Here, we explore the isolated binary formation channel for Gaia BH3, focusing on the old and metal-poor stellar population of the Milky Way halo. We used the MIST stellar models and our open-source population synthesis code SEVN to evolve 5.6 × 108 binaries, exploring 20 sets of parameters that encompass different natal kicks, metallicities, common envelope efficiencies and binding energies, and models for the Roche-lobe overflow. We find that systems such as Gaia BH3 form preferentially from binaries initially composed of a massive star (40–60 M⊙) and a low-mass companion (<1 M⊙) in a wide (P > 103 days) and eccentric orbit (e > 0.6). Such progenitor binary stars do not undergo any Roche-lobe overflow episode during their entire evolution, so the final orbital properties of the BH-star system are essentially determined at the core collapse of the primary star. Low natal kicks (≲ 10 km/s) significantly favour the formation of Gaia BH3-like systems, but high velocity kicks up to ≈220 km/s are also allowed. We estimated the formation efficiency for Gaia BH3-like systems in old (t >10 Gyr) and metal-poor (Z < 0.01) populations to be ∼4 × 10−8 M⊙−1 (for our fiducial model), representing ~3% of the whole simulated BH-star population. We expect up to ≈4000 BH-star systems in the Galactic halo formed through isolated evolution, of which ≈100 are compatible with Gaia BH3. Gaia BH3-like systems represent a common product of isolated binary evolution at low metallicity (Z < 0.01), but given the steep density profile of the Galactic halo, we do not expect more than one at the observed distance of Gaia BH3. Our models show that even if it was born inside a stellar cluster, Gaia BH3 is compatible with a primordial binary star that escaped from its parent cluster without experiencing significant dynamical interactions.
Connecting stochastic optimal control and reinforcement learning
Authors: Quer J. , Ribera Borrell Enric
Published: August 2024

In this paper the connection between stochastic optimal control and reinforcement learning is investigated. Our main motivation is to apply importance sampling to sampling rare events which can be reformulated as an optimal control problem. By using a parameterised approach the optimal control problem becomes a stochastic optimization problem which still raises some open questions regarding how to tackle the scalability to high-dimensional problems and how to deal with the intrinsic metastability of the system. To explore new methods we link the optimal control problem to reinforcement learning since both share the same underlying framework, namely a Markov Decision Process (MDP). For the optimal control problem we show how the MDP can be formulated. In addition we discuss how the stochastic optimal control problem can be interpreted in the framework of reinforcement learning. At the end of the article we present the application of two different reinforcement learning algorithms to the optimal control problem and a comparison of the advantages and disadvantages of the two algorithms.
Tutorials: Physics-informed machine learning methods of computing 1D phase-field models
Authors: Li Wei , Fang Ruqing , Jiao Junning , Vassilakis Georgios N. , Zhu Juner
Published: August 2024

Phase-field models are widely used to describe phase transitions and interface evolution in various scientific disciplines. In this Tutorial, we present two neural network methods for solving them. The first method is based on physics-informed neural networks (PINNs), which enforce the governing equations and boundary/initial conditions in the loss function. The second method is based on deep operator neural networks (DeepONets), which treat the neural network as an operator that maps the current state of the field variable to the next state. Both methods are demonstrated with the Allen–Cahn equation in one dimension, and the results are compared with the ground truth. This Tutorial also discusses the advantages and limitations of each method, as well as the potential extensions and improvements.
Structural color in fruits: Biomaterials to inspire physical optics
Authors: Middleton R. , Sinnott-Armstrong M.
Published: August 2024

This Tutorial introduces structural color in fruits as a phenomenon of diverse optical materials. Originally best known in abiotic materials and animals, structural colors are being increasingly described in plants. Structural colors have already inspired a variety of useful products, and plants are especially attractive as models to develop new bioinspired technologies thanks to the comparative ease of working with them compared with animal systems. Already, human-engineered structural colors modeled after plant cellulose-based architectures have shown promising applications in colorants and sensors. However, structural colors include a far broader group of materials and architectures beyond cellulose. Understanding the new and diverse structures that have recently been described in plants should provoke research into new bioinspired products based on plant optical structures and biomaterials. In this Tutorial, we focus on fruits as new structures have recently been discovered, leading to new opportunities for bioinspired technologies. We bring together a review of optical structures found in fruits from a physical optics perspective, with a consideration of each structure as an opportunity in bioinspired and biomimetic design.
Simulating spin biology using a digital quantum computer: Prospects on a near-term quantum hardware emulator
Authors: Alvarez Pedro H. , Chowdhury Farhan T. , Smith Luke D. , Brokowski Trevor J. , Aiello Clarice D. , Kattnig Daniel R. , de Oliveira Marcos C.
Published: August 2024

Understanding the intricate quantum spin dynamics of radical pair reactions is crucial for unraveling the underlying nature of chemical processes across diverse scientific domains. In this work, we leverage Trotterization to map coherent radical pair spin dynamics onto a digital gate-based quantum simulation. Our results demonstrated an agreement between the idealized noiseless quantum circuit simulations and established master equation approaches for homogeneous radical pair recombination, identifying ∼15 Trotter steps to be sufficient for faithfully reproducing the coupled spin dynamics of a prototypical system. By utilizing this computational technique to study the dynamics of spin systems of biological relevance, our findings underscore the potential of digital quantum simulation (DQS) of complex radical pair reactions and builds the groundwork toward more utilitarian investigations into their intricate reaction dynamics. We further investigate the effect of realistic error models on our DQS approach and provide an upper limit for the number of Trotter steps that can currently be applied in the absence of error mitigation techniques before losing simulation accuracy to deleterious noise effects.
Skew-product attractors of non-autonomous Caputo fractional differential equations
Authors: Cui Hongyong , Kloeden Peter E.
Published: August 2024

A non-autonomous Caputo fractional differential equation (FDE) of order α∈(0,1) in Rd with a driving system on a compact base space P is shown to generate a skew-product semi-flow on Cα×P, where Cα is the space of continuous functions f:R+→Rd with a weighted norm giving uniform convergence on compact time subsets. This skew-product semi-flow is then shown to have a bounded and closed attractor when the vector field of the Caputo FDE satisfies a uniform dissipativity condition. It attracts bounded sets of constant initial functions f in here Cα. The properties and structure of this attractor in Cα×P are also discussed.
Design and commissioning of resistive foil bolometer diagnostics on the ST40 tokamak
Authors: Harryman D. M. , Colgan C. , Lovell J. , Moscheni M. , Naylor G. , Rengle A. , Sertoli M. , Sladkomedova A. , Thwaites R.
Published: August 2024

Following successful campaigns on the compact high field spherical tokamak ST40, resistive gold foil bolometers have now been installed to measure the radiated power profile. Positioned on the midplane, two bolometer cameras offer perspectives of the horizontal and vertical planes, while the third camera, situated above the midplane, provides a vertical view of the top divertor plates, including the X-point and the strike points. These cameras use a commercial off-the-shelf data acquisition platform with modules specifically designed for bolometers in a Wheatstone bridge configuration, providing both phase sensitive detection and in situ calibration. This paper presents an overview of the design and functionality of all three cameras and the commissioning of the horizontal plane camera. The commissioning of the horizontal camera shows data from a range of plasma pulses, presenting a positive correlation between the relative profiles measured from the bolometer camera and an absolute extreme ultraviolet diode camera viewing along similar lines of sight.
All-in-one probe for exploring self-organized two-fluid equilibria in toroidal plasmas
Authors: Himura H. , Almagri A. F. , Sarff J. S. , Ashida Y. , Inagaki S. , Fujiwara H. , Inoue T. , Sanpei A. , Linden J. von der , McCollam K. J. , Hurst N. C. , Forest C. B.
Published: August 2024

This paper presents the development of an all-in-one probe to simultaneously measure all components of the generalized Ohm’s law in reversed-field pinch plasmas and tokamaks. The polyhedral configuration of the Mach probe is achieved through the specific arrangement, angle, and depth of the collimator channel apertures drilled into the surface of a hollow boron nitride cylinder encasing it. This probe includes a central Mach probe to assess the ion velocity field in three dimensions. Initial tests at the RELAX and Madison Symmetric Torus machines have confirmed the probe’s effectiveness, revealing an octahedron form similar to a tetrahedron. The probe seems to function correctly and is expected to facilitate the empirical validation of two-fluid equilibria at the periphery of toroidal plasmas.
Development of improved higher-order correction for the NIF opacity spectrometer
Authors: Hobbs B. A. , Mayes D. C. , Heeter R. F. , Bradley P. A. , Dutra E. C. , Fontes C. J. , Gallardo-Diaz E. , Hohenberger M. , Johns H. M. , Opachich Y. P. , Robey H. F. , Stoupin S. , Wallace M. S. , Webster L. G. , Montgomery M. H. , Perry T. S. , Winget D. E.
Published: August 2024

X-ray opacity measurements on the National Ignition Facility (NIF) are in the process of reproducing earlier measurements from the Sandia Z Facility, in particular for oxygen and iron plasmas. These measurements have the potential to revise our understanding of the “solar problem” and of the hot degenerate Q class white dwarf structure by probing plasma conditions near the base of their convection zones. Accurate opacity measurements using soft x-ray Bragg crystal spectrometers require correction for higher-order diffraction effects. Extending prior work in this area [Dutra et al., Review of Scientific Instruments 93, 113527 (2022)], we have developed a new method to remove higher-order spectral components from NIF opacity spectrometer data. By modeling absorption and backlighting continuum spectra and subtracting the second- and third-order components from the measured data, we are able to perform this correction while avoiding imprinting first-order model line features onto the data.
Nonvolatile control of switchable anomalous valley Hall effect in GdF2/Sc2CO2 multiferroic heterostructure
Authors: Zhu Yunlai , Yuan Tengteng , Zhang Junjie , Sun Xi , Zhao Yongjie , Zhu Ying , Xu Zuyu , Wu Zuheng , Dai Yuehua , Yang Fei
Published: August 2024

In two-dimensional valleytronics, the controllability of anomalous valley Hall effect is the key to its practical application. However, most of the previously proposed control methods are volatile or irreversible. Here, using first principles calculations, we demonstrate that the GdF2/Sc2CO2 multiferroic heterojunction can exhibit nonvolatile switching of its electronic band structures. Interestingly, the polarization switching of the ferroelectric monolayer induces movement in the valley polarization band of GdF2, enabling manipulation of the valley Hall effect. This allows the memory state encoded in the ferroelectric monolayer to be read out via the anomalous valley Hall signal of the heterostructures. The switchable anomalous valley Hall effect can also be achieved by applying biaxial strain in the GdF2/Sc2CO2 multiferroic heterojunction. By harnessing this intriguing anomalous valley Hall effect switching characteristic, we develop a nonvolatile valleytronics memory device. This work provides a way to achieve nonvolatile control in valleytronics and promotes the design of memory devices.
Enhancing triboelectrification via multiscale roughness dependent thermal dissipation
Authors: Kim Jong Hun , An Yong Ho , Hu Ying Chieh , Kong Dae Sol , Ahn Hyun Soo , Park Jeong Young , Jung Jong Hoon
Published: August 2024

Polymer-based triboelectric nanogenerators (TENGs) have held promise due to their excellent interfacial conformity and ease of fabrication. However, the role of surface roughness in triboelectricity requires further study. In this study, we have manipulated the nano-/micro-scale roughness configuration in polydimethylsiloxane (PDMS) over a wide range of extents using various sandpaper-based templates. According to the power spectral density analysis, the spatial frequency of template-free PDMS exhibits several distinct bandwidth regions each with different fractal dimensions significantly higher than 2, despite having the lowest roughness value. In contrast, most template-based PDMS shows an entire spatial frequency region that scales nearly with a single power factor corresponding to a fractal dimension as low as 2, despite slight increases in roughness values. Consequently, the surface temperature gradient and output performance of TENG increased, following the trend of fractal dimension and roughness, but the surface potentials have remained almost invariant. However, excessive increases in the surface roughness cause the spatial frequency to be divided once again into several different bandwidth regions with different cutoffs and higher fractal dimensions. These results suggest that the performance of TENG can be controlled by tuning both surface roughness and self-affine properties over multiple scales. Specifically, adhesive interaction becomes dominant on surfaces with lower fractality, enhancing TENG performance due to the expanded contact area. This study sheds light on the relationship among triboelectricity, thermal dissipation, and topography.
High-performance uncooled PbSe/CdSe nanostructured mid-infrared photodetector with tunable cutoff wavelength
Authors: Rastkar Mirzaei Milad , Shi Zhisheng
Published: August 2024

Room-temperature (RT) high-performance mid-wavelength infrared (MWIR) Lead Selenide (PbSe)/Cadmium Selenide (CdSe) heterostructure nanocrystal photoconductors are designed and fabricated on commercial silicon dioxide on silicon (SiO2/Si) wafer via vapor phase deposition. Tunable absorption edges at 3.75 and 4.0 μm are demonstrated with different sizes of the nanostructure. The devices are annealed in oxygen to make the thin film much more sensitive to MWIR light. The detectors are etched by the reactive ion etching method to define an active area of 17.5 × 20 μm2. All devices exhibit external quantum efficiencies exceeding 100%, a clear indication of photoconductive gain. 1/f noise is the dominating noise source, and it follows Hooge's empirical relation for a homogeneous semiconductor. RT peak specific detectivity (D*) of 2.17 × 1010 and 1.61 × 1010 Jones is achieved for pixels with absorption edge at 3.75 and 4 μm, respectively.
Review of Scientific Instruments New Products
Authors: Mandelis Andreas
Published: August 2024

In order to supplement manufacturers’ information, this department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials that supersede the earlier data or suggest new research applications.
Unveiling the hidden reserves: allocation strategies associated with underground organs of Cerrado legumes in fire-prone savannas
Authors: Cozin Bruno Bonadio , Ferreira Tassia Caroline , Daibes L. Felipe , de Carvalho Isabella Fiorini , dos Santos Beatriz Silvério , de Souza Roberta Possas , de Camargos Liliane Santos , Martins Aline Redondo
Published: August 2024

The synthesis and differential allocation of reserve compounds is an important adaptive mechanism that enables species to resprout in fire-prone ecosystems. The analysis of compound allocation dynamics (differential accumulation of compounds between plant organs) provides insights into plant responses to disturbances. The aim was to quantify reserves in eight legume species from Cerrado open savannas with high fire frequency in order to investigate the patterns of allocation and distribution of compounds between leaves and underground organs, drawing ecophysiological inferences. The species were collected in ‘campo sujo’ areas of the Cerrado. Leaves and underground organs (xylopodium, taproot tubers) were subjected to physiological analyses. Overall, underground organs were characterised by greater deposits of carbohydrates, mainly soluble sugars, and also with the accumulation of proteins and amino acids. This suggests that nitrogen reserves, as well as carbohydrates, may have an ecophysiological function in response to fire, being allocated to the underground organs. Phenols were mainly evident in leaves, but a morphophysiological pattern was identified, where the two species with taproot tubers tended to concentrate more phenols in the underground portion compared to species with xylopodium, possibly due to functional differences between these organs. Such data allow inferring relevant ecophysiological dynamics in legumes from open savannas.
Designing turbulence with entangled vortices
Authors: Shen Weiyu , Yao Jie , Yang Yue
Published: August 2024

Matter entanglement is a common chaotic structure found in both quantum and classical systems. For classical turbulence, viscous vortices are like sinews in fluid flows, storing and dissipating energy and accommodating strain and stress throughout a complex vortex network. However, to explain how the statistical properties of turbulence arise from elemental vortical structures remains challenging. Here, we use the quantum vortex tangle as a skeleton to generate an instantaneous classical turbulent field with intertwined vortex tubes. Combining the quantum skeleton and tunable vortex thickness makes the synthetic turbulence satisfy key statistical laws, offering valuable insights for elucidating energy cascade and extreme events. By manipulating the elemental structures, we customize turbulence with desired statistical features. This bottom–up approach of designing turbulence provides a testbed for analyzing and modeling turbulence.
Distinct roles of Kif6 and Kif9 in mammalian ciliary trafficking and motility
Authors: Fang Chuyu , Pan Xinwen , Li Di , Chen Wei , Huang Ying , Chen Yawen , Li Luan , Gao Qi , Liang Xin , Li Dong , Zhu Xueliang , Yan Xiumin
Published: August 2024

Ciliary beat and intraflagellar transport depend on dynein and kinesin motors. The kinesin-9 family members Kif6 and Kif9 are implicated in motile cilia motilities across protists and mammals. How they function and whether they act redundantly, however, remain unclear. Here, we show that Kif6 and Kif9 play distinct roles in mammals. Kif6 forms puncta that move bidirectionally along axonemes, whereas Kif9 appears to oscillate regionally on the ciliary central apparatus. Consistently, only Kif6 displays microtubule-based motor activity in vitro, and its ciliary localization requires its ATPase activity. Kif6 deficiency in mice disrupts coordinated ciliary beat across ependymal tissues and impairs cerebrospinal fluid flow, resulting in severe hydrocephalus and high mortality. Kif9 deficiency causes mild hydrocephalus without obviously affecting the ciliary beat or the lifespan. Kif6−/− and Kif9−/− males are infertile but exhibit oligozoospermia with poor sperm motility and defective forward motion of sperms, respectively. These results suggest Kif6 as a motor for cargo transport and Kif9 as a central apparatus regulator.
Photo- and exchange-field controlled spin and valley polarized transport in a normal/antiferromagnetic/normal (N/AF/N) junction based on transition metal dichalcogenides
Authors: Hosseinzadeh Helaleh Shahla , Alipourzadeh Mohammad , Hajati Yaser
Published: August 2024

We theoretically investigate spin- and valley-polarized transport within a normal/antiferromagnetic/normal (N/AF/N) junction based on transition metal dichalcogenides (TMDs), under the influence of off-resonance circularly polarized light and gate voltage. Antiferromagnetism modulates spin states and the effective gap, reducing the spin gap for one state while increasing it for the opposite, resulting in a broad spin polarization and a controlled gap. Off-resonance circularly polarized light adjusts the valley degree of freedom and the effective gap, providing a wide range of valley polarization. Harnessing the strong spin–orbit coupling in TMDs enables perfect spin-valley polarization in the proposed junction across a wide range of Fermi energies through AF and/or off-resonance light manipulation. AF manipulation effectively narrows the band gap of TMDs at lower light energies, enhancing potential applications of the proposed junction for spin-valley filtering.
Cathodoluminescence from interlayer excitons in a 2D semiconductor heterobilayer
Authors: Borghi Matteo T A , Wilson Neil R
Published: August 2024

Photoluminescence has widely been used to study excitons in semiconducting transition metal dichalcogenide (MX2) monolayers, demonstrating strong light-matter interactions and locked spin and valley degrees of freedom. In heterobilayers composed of overlapping monolayers of two different MX2, an interlayer exciton can form, with the hole localised in one layer and the electron in the other. These interlayer excitons are long-lived, field-tunable, and can be trapped by moiré patterns formed at small twist angles between the layers. Here we demonstrate that emission from radiative recombination of interlayer excitons can be observed by cathodoluminescence from a WSe2/MoSe2 heterobilayer encapsulated in hexagonal boron nitride. The higher spatial resolution of cathodoluminescence, compared to photoluminescence, allows detailed analysis of sample heterogeneity at the 100 s of nm lengthscales over which twist angles tend to vary in dry-transfer fabricated heterostructures.
On q-Painlevé VI and the geometry of Segre surfaces
Authors: Roffelsen Pieter
Published: August 2024

In the context of q-Painlevé VI with generic parameter values, the Riemann–Hilbert correspondence induces a one-to-one mapping between solutions of the nonlinear equation and points on an affine Segre surface. Upon fixing a generic point on the surface, we give formulae for the function values of the corresponding solution near the critical points, in the form of complete, convergent, asymptotic expansions. These lead in particular to the solution of the nonlinear connection problem for the general solution of q-Painlevé VI. We further show that, when the point on the Segre surface is moved to one of the sixteen lines on the surface, one of the asymptotic expansions near the critical points truncates, under suitable parameter assumptions. At intersection points of lines, this then yields doubly truncated asymptotics at one of the critical points or simultaneous truncation at both.
Optimizing photocurrent intensity in layered SiGe heterostructures
Authors: Sultan M T , Ciurea M L , Stavarache I , Thórarinsdóttir K A , Arnalds U B , Teodorescu V , Manolescu A , Ingvarsson S , Svavarsson H G
Published: August 2024

We study the dependence of photo-spectral intensity on tri- and multilayers of SiO2/[SiGe [

d

SiGe

]/SiO2]
N
with repetitions N = 1 to 10 and thicknesses

d

SiGe

=
5

–100 nm. Photocurrent analysis reveals a bimodal spectral feature. A comparison of the photocurrent analysis between tri- and multilayers shows that in the multilayer structures, the photo-spectral intensity increases with increasing repetition N. The change in intensity could then be further tuned by changing the thickness of the SiGe layers

d

SiGe

. We attribute the change in intensity to an increase in tensile strain, along with increased Ge atomic concentration and reduced SiGe-nano cluster size.
Electromechanical response of multilayer graphene sheet/polypropylene nanocomposites and its relationship with the graphene sheet physicochemical properties
Authors: Medina C , Canché H , Oliva-Avilés A I , Avilés F
Published: August 2024

The mechanical, electrical, and piezoresistive responses of multilayer graphene sheet (GS)/polypropylene (PP) nanocomposites are investigated using four GSs of distinctive physicochemical properties. It is found that the morphology of the interconnected network of GS agglomerates at the mesoscale governs the mechanical, electrical, and electro-mechanical (piezoresistive) properties of the PP nanocomposites. The morphology of the mesoscale network of electroconductive fillers governs the effective properties of the nanocomposite. This network morphology strongly depends on the GS lateral size, dispersion, agglomeration, and, to a lesser extent, the specific surface area of the GSs. Within the range of lateral sizes investigated herein (1–21 μm), larger GSs yields nanocomposites with higher electrical conductivity. On the other hand, GSs of moderate lateral size (∼6.5 μm) and specific surface area of ∼141 m2 g−1 render GS/PP nanocomposites with a more dispersed and more sparsely interconnected network. This better dispersed network with agglomerates of smaller dimensions is concomitant with improved stiffness and strength, and higher gauge factors (∼18.2) for this GS/PP nanocomposites. Excellent capabilities for detection of human motion were proved for these nanocomposites.
Responsibility of small defects for the low radiation tolerance of coated conductors
Authors: Unterrainer Raphael , Gambino Davide , Semper Florian , Bodenseher Alexander , Torsello Daniele , Laviano Francesco , Fischer David X , Eisterer Michael
Published: August 2024

Rare-earth-barium-copper-oxide based coated conductors exhibit a relatively low radiation robustness compared to e.g. Nb3Sn due to the d-wave symmetry of the order parameter, rendering impurity scattering pair breaking. The type and size of the introduced defects influence the degrading effects on the superconducting properties; thus the disorder cannot be quantified by the number of displaced atoms alone. In order to develop degradation mitigation strategies for radiation intense environments, it is relevant to distinguish between detrimental and beneficial defect structures. Gadolinium-barium-copper-oxide based samples irradiated with the full TRIGA Mark II fission reactor spectrum accumulate a high density of point-like defects and small clusters due to n - γ capture reactions of gadolinium. This leads to a 14–15 times stronger degradation of the critical temperature compared to samples shielded from slow neutrons. At the same time both irradiation techniques lead to the same degradation behavior of the critical current density as function of the transition temperature

J

c

(

T

c

)

. Furthermore, annealing the degraded samples displayed the same

T

c

recovery rates, indicating the universality of the defects responsible for the degradation. Since the primary knock on atom of the n - γ reaction as well as the recoil energy is known, we used molecular dynamics simulations to calculate which defects are formed in the neutron capture process and density functional theory to assess their influence on the local density of states. The defects found in the simulation were mainly single defects as well as clusters consisting of Oxygen Frenkel pairs, however, more complex defects such as Gd

C
u

antisites occurred as well.
Noise scaling in SQUID arrays
Authors: Nieves O A , Müller K-H
Published: August 2024

We numerically investigate the noise scaling in high-Tc
commensurate 1D and 2D SQUID arrays. We show that the voltage noise spectral density in 1D arrays violates the scaling rule of

∼

1

/

N
p

for the number Np
of Josephson junctions in parallel. In contrast, in 2D arrays with Ns
1D arrays in series, the voltage noise spectral density follows more closely the expected scaling behaviour of

∼

N
s

/

N
p

. Additionally, we reveal how the flux and magnetic field rms noise spectral densities deviate from their expected

∼

(

N
s

N
p

)

−
1

/

2

scaling and discuss their implications for designing low noise magnetometers.
Evaluating the risk of malaria transmission within the Central African Republic with the goal of stabilising and eliminating the infection
Authors: Shalini Priya S , Ganesan K , Uma Maheshwari P , Aakash M
Published: August 2024

In this paper, we formulate a multi-compartmental mathematical model for humans and mosquitoes. We construct the system of differential equations for an SEITVR for the human compartment and an SEI for the mosquito compartment. We investigate the outbreak of malaria and its effect on the Central African Republic. The analysis of the compartmental model is carried out using stability analysis and Routh Hurwitz Criterion technique is used to indicate the major impact of the model and to improve the model through minor modifications in the transformation of disease in the population. Our model exhibits two equilibrium points, disease free equilibrium points and endemic equilibrium points. The next generation matrix is used to determine the basic reproduction number R
0. A new compartmental model was framed and estimated the malaria spread after 2023 in the Central African Republic, which is the novelty of this research. Our main motivation is to make the Central African Republic a malaria free country. A Numerical example are provided to validate our results for both the disease free state and endemic state of each model. We believe that this investigation will be more effective in reducing malaria infection and stop spreading.
Polycyclic aromatic compounds surface modulation of TiO2@SiO2 nanoparticles enhances the insulation performance of polypropylene film
Authors: Xie Jun , Liu Ziqian , Liu Qi , Shi Xiaoyu , Xie Qing
Published: August 2024

Polypropylene (PP) film is an important component of metallized film capacitors. However, the insulation issues of polypropylene film significantly affect the safe and stable operation of capacitors. In this study, polycyclic aromatic compounds (PAC) were introduced to the surface of TiO2@SiO2 nanoparticles via chemical grafting, preparing Ti@Si-PAC nanofillers, to achieve modulation of the nanoparticle/PP interface. The experimental and simulation results indicate that Ti@Si-PAC/PP exhibits excellent insulation performance. The study indicates that the surface modulation of nanoparticles by PAC introduces a ‘soft interface’ between the nanoparticles and the polypropylene matrix. The ‘soft interface’ enhances the interfacial interaction, reduces dielectric loss, and introduces deep traps, exhibiting a significant inhibitory effect on carrier migration. Additionally, the introduction of PAC enhances the electron trapping capability in the interface region, which plays a positive role in quenching free radical chain reactions and reducing the damage of high-energy electrons to polypropylene molecular segments. This study provides an effective method for enhancing the insulation performance of polypropylene.
Ripple-induced neoclassical toroidal viscous torque in Augmented-First Plasma operation phase in ITER
Authors: Liu Yueqiang , Bai Xue , Gribov Y. , Koechl F. , Loarte A. , Pinches S.D. , Schmitz L.
Published: August 2024

A systematic calculation is performed on the ripple-induced neoclassical toroidal viscous (NTV) torque for new ITER scenarios designed for the Augmented-First Plasma (A-FP) operation phase with the full tungsten wall, where the plasma-wall gap is varied in view of mitigating the impact of tungsten wall-plasma interactions. The torque calculation includes drift kinetic response of the plasma thermal and energetic particles to the n = 18 (n is the toroidal harmonic number) ripple field. For the plasma scenario with ~45 cm plasma-wall gap at the outboard mid-plane and considering the corrected ripple level of 0.17% by the ferritic steel inserts, the computed net NTV torque acting on the plasma column is in the sub-Nm level. However, with decreasing the plasma-wall gap, the computed net NTV torque can reach a level comparable to that produced by the neutral-beam momentum injection in ITER. Ripple correction by ferritic inserts reduces the net torque by a factor of 3.3 for all the three A-FP scenarios considered. The

n

ω
d

=
l

ω
b

(with ω

d
and ω

b
being the toroidal precession and bounce frequencies of trapped particles, respectively, and l an integer number) type of resonance-enhancement of the NTV torque, due to thermal particles, is found to be weak in ITER despite high-n of 18. The same also holds for the ITER 10 MA steady state scenario from the D-T operation phase, where the aforementioned resonance associated with fusion-born alphas is also included. The ripple-induced NTV torque is well below that produced by the resonant magnetic perturbation applied for controlling the type-I edge-localized mode in ITER.
Study on the effect of thiol structure on the properties of thiol-ene system
Authors: Yue Jiarui , Chen Chuanxin , Zhang Ling , Nie Jun , Zhu Xiaoqun , Cheng Wei
Published: August 2024

Using Pentaerythritol tetra (3-mercapto propionate) as primary thiol and Pentaerythritol tetra (3-mercapto butylate) as secondary thiol, the effect of thiol structure on the properties of the thiol-ene system were investigated. The results show that for the triallyl isocyanurate system, the thiol structure had little effect on the glass transition temperature, but for the tri (1, 2-propylene glycol) diacrylate and divinylbenzene system, the secondary thiol systems showed a higher glass transition temperature. In terms of optical properties and anti-swelling, the primary thiol system showed better performance.
Comparison of contact time dependence of adhesion force between silica/DLC and silica/graphene interfaces by AFM at different humidities
Authors: Wang Runsheng , Lai Tianmao
Published: August 2024

Understanding adhesion mechanisms is one way to address failures in micro-nano devices. In this paper, the adhesion forces of diamond-like carbon film (DLC) and graphene were measured, and the differences between them were compared. The results show that the adhesion forces on the DLC are dependent on the contact time, but this dependence is disrupted by repeated contacts. The impact of repeated contacts is inevitable. With the increase of repeated contacts, the size of the liquid bridge was changed, and the time to reach saturation became shorter. Finally, at low relative humidity (RH), the adhesion behaviors become independent. In contrast, the adhesion forces of graphene had no contact time dependence under each RH. The adhesion forces remained stable at low and medium RH, and the influence of repeated contacts was weak. At high RH, a sudden increase in adhesion forces caused by repeated contacts can be observed. The adhesion behaviors under different RHs are attributed to the size change of the liquid bridge. The results help people understand the adhesion mechanisms and provide some help in solving the failure problem of micro-nano devices.
The influence of aluminum content on thermal properties of copper-aluminum alloys: a first-principles calculation
Authors: Yang Jinhe , Zhang Shuting , Ouyang Peixuan , Du Kaiping , Pi Ziqiang , Zheng Zhaoran , Chen Xing
Published: August 2024

Copper-aluminum alloy, also called aluminum bronze, is a type of host material for abradable sealing coatings. The amount of aluminum content obviously affects the properties of the coating. This research uses the density functional theory to calculate the properties of an aluminum bronze with different aluminum content. The copper-aluminum alloy model uses the model of special quasirandom structures (SQS). The elastic constant, melting point, constant pressure specific heat capacity, and thermal expansion coefficient of the copper-aluminum alloys were calculated using the quasi-harmonic approximation (QHA) method. The copper-aluminum alloys with three different nominal components were prepared using vacuum induction melting. The melting point, thermal expansion coefficient, and specific heat capacity of the copper-aluminum alloys were characterized through experiments. The results showed that the melting point of the copper-aluminum alloys decreased with an increase in aluminum content. Additionally, the coefficient of thermal expansion of the copper-aluminum alloy increased with the increase in aluminum content. Furthermore, the specific heat capacity of the copper-aluminum alloy initially increased and then reached a turning point when the β’ phase was generated. The experimental values conform well to the calculated values.
The effect of rare earth yttrium on properties of Ni-W/ZrO2 layers
Authors: Feng Pei , Shi Yuhua , Jiang Dayong , Lu Ling , Shang Peng , Li Bin
Published: August 2024

Aluminum alloys often fail to meet harsh environmental conditions, such as abrasion and erosion, due to their inherent limitations in terms of unsatisfied hardness and wear resistance. In this paper, Re/Ni-W-ZrO2 composite layers are fabricated on the surface of an aluminum alloy matrix by electroplation. The cross-sectional morphology, elemental distribution, thickness and surface hardness of the composite coatings are characterized. The impact of the addition of Re-Y(NO3)3 on the characteristics of the coating is further examined. The coating is well bonded to the matrix material while ZrO2 particles are dispersed within the Ni-W base metal layer with a thickness of 136 μm. When Re is added to 1.5 g/L, the thickness and hardness are enhanced significantly. This is because the unique 4f electronic structure of rare earth elements not only plays a role in refining the grain during the coating growth process, but also effectively reduces the overpotential that may be generated during the deposition process, thereby increasing the deposition rate, so as to obtain a denser and finer grain structure.
Effect of preload distribution on dynamic characteristics of machine tool bolted joint structure
Authors: Yan Xing , Liu Zhifeng , Chen Wentao , Li Ying
Published: August 2024

The bolted joint is the machine tool’s primary connection mode. The bolted joint structures have a profound influence on the dynamic performance of the machine tool. Due to factors such as design and manufacturing processes, bolted joint structures often exhibit uneven stress distribution, which severely affects the dynamic properties of the structure. The common frame connection structure in the machine tool infrastructure is used as the research object. A simulation model was established to study the influence of bolt preload distribution on structural dynamics based on the improved thin-layer element method. The results show that using more small bolts can improve the uniformity of stiffness distribution and the natural frequency of the structure. When the bolt specification and number remain unchanged, the dispersion of bolt preload has little influence on the dynamic performance of the structure. The research results have a certain guiding significance for the optimization design of bolt joint structure of machine tools.
Design of programmable filter based on microcontroller
Authors: Lv Meimei , Wang Jigang , Liu Shizhe , Qiao Lufeng
Published: August 2024

The system is designed with a microcontroller (AT89S52) as the core, developed based on the Keil 51 software system, combined with LCD display and necessary peripheral circuits to form a programmable controlled high-precision filter. The system mainly consists of the amplifier module, filter module, parameter setting and LCD display module, and amplitude-frequency characteristic testing module. The programmable control of the amplifier consists of a D/A converter DAC0832 and a programmable filter MAX262. By setting the amplifier and filter parameters on the keyboard, the gain and step adjustment can be achieved with high accuracy. The amplitude-frequency characteristic test signal source is implemented by DDS. Due to the use of a software operating system and a Chinese LCD module for display, this programmable filter provides a very user-friendly human-computer interaction interface.
Synergistic effect of coal gangue on intumescent flame retardants
Authors: Huang Haoqi , Deng Junpin , Xu Boyang , Kang Le
Published: August 2024

In order to improve the flame retardant properties of wood plywood, intumescent flame retardant coatings were prepared using melamine, borate, pentaerythritol and urea as the basic formulations and gangue as a modified additive. The flame retardancy of the samples was characterized using a cone calorimeter, scanning electron microscope, X-ray diffraction and thermogravimetric analysis. In addition, the study investigated the effect of gangue content on the properties of the prepared coatings. The results show that the doping of gangue in intumescent flame retardant coatings can improve the flame retardant effect of the coatings. Specifically, when the mass fraction of gangue was 8 wt%, the exothermic rate, total smoke production and total exothermic amount of the coating were significantly reduced. Moreover, the addition of gangue promoted the formation of a continuous and dense carbon layer structure during the combustion process of the coating, which produced a molten substance that effectively isolated oxygen and heat, thus strengthening the fire-retardant and heat-insulating properties of the coating. The results of this study provide valuable insights into the development of flame retardant coating formulations for wood plywood.
Vibration simulation and analysis of high-speed railways sound barriers under different conditions of bolts loosening
Authors: Hu Shihui , Zhao Qian , Jiang Bolong , Tan Zhao , Qi Chunyu , Song Zhenan
Published: August 2024

The structural instability caused by the bolts’ loosening of the sound barrier of high-speed railways has become an important reason affecting its safe use, but there is still a lack of basic research on the possible structural vibration of the sound barrier when the bolts are loosened. In this study, a finite element model of the sound barrier of the high-speed railway was constructed, and the vibration mode simulation analysis under different bolt loosening conditions was carried out. The results show that the loosening of the bolts between the column and the concrete foundation will cause the vibration frequency of the overall structure of the sound barrier to change, induce new local mode shapes, and lead to the increase of vibration displacement at the top of the column. The results of this study will provide a reference for the structural health detection method of high-speed railway sound barriers in the future.