bluuebunny/crossref_metadata_2025 huggingface dataset:
A deep-reinforcement learning approach for optimizing homogeneous droplet routing in digital microfluidic biochips
Authors: Saha Basudev , Das Bidyut , Majumder Mukta
Published: March 2023

Over the past two decades, digital microfluidic biochips have been in much demand for safety-critical and biomedical applications and increasingly important in point-of-care analysis, drug discovery, and immunoassays, among other areas. However, for complex bioassays, finding routes for the transportation of droplets in an electrowetting-on-dielectric digital biochip while maintaining their discreteness is a challenging task. In this study, we propose a deep reinforcement learning-based droplet routing technique for digital microfluidic biochips. The technique is implemented on a distributed architecture to optimize the possible paths for predefined source–target pairs of droplets. The actors of the technique calculate the possible routes of the source–target pairs and store the experience in a replay buffer, and the learner fetches the experiences and updates the routing paths. The proposed algorithm was applied to benchmark suites I and III as two different test benches, and it achieved significant improvements over state-of-the-art techniques.
Market model shows optimized strategies for implementing nuclear-renewable hybrid energy systems
Authors: Liebendorfer Adam
Published: March 2023

Most detailed analysis of the impact of hybrid energy systems to date demonstrates income-generating boosts to efficiency when considering grid reserves and thermal load.
Quasiperiodic solutions to nonlinear random Schrödinger equations at fixed potential realizations
Authors: Geng Jiansheng , Sun Yingnan , Wang W.-M.
Published: March 2023

In this paper, we study the discrete nonlinear random Schrödinger equation [Formula: see text] on [Formula: see text], where 0 < ɛ, δ ≪ 1, Δ is the discrete Laplacian, and V is the random potential. We fix the random potential V in a good set. Then, we use small amplitudes as parameters to construct quasiperiodic solutions of the nonlinear random Schrödinger equation.
Exploring ultra-high-intensity wakefields in carbon nanotube arrays: An effective plasma-density approach
Authors: Bonatto A. , Xia G. , Apsimon O. , Bontoiu C. , Kukstas E. , Rodin V. , Yadav M. , Welsch C. P. , Resta-López J.
Published: March 2023

Charged particle acceleration using solid-state nanostructures has attracted attention in recent years as a method of achieving ultra-high-gradient acceleration in the TV/m domain. More concretely, metallic hollow nanostructures could be suitable for particle acceleration through the excitation of wakefields by a laser or a high-intensity charged particle beam in a high-density solid-state plasma. For instance, due to their special channeling properties as well as optoelectronic and thermo-mechanical properties, carbon nanotubes could be an excellent medium for this purpose. This article investigates the feasibility of generating ultra-high-gradient acceleration using carbon nanotube arrays, modeled as solid-state plasmas in conventional particle-in-cell simulations performed in a two-dimensional axisymmetric (quasi-3D) geometry. The generation of beam-driven plasma wakefields depending on different parameters of the solid structure is discussed in detail. Furthermore, by adopting an effective plasma-density approach, existing analytical expressions, originally derived for homogeneous plasmas, can be used to describe wakefields driven in periodic non-uniform plasmas.
A physics-preserving pure streamfunction formulation and high-order compact solver with high-resolution for three-dimensional steady incompressible flows
Authors: Guo Xiaohu
Published: March 2023

In this paper, a pure streamfunction high-order compact (HOC) difference solver is proposed for three-dimensional (3D) steady incompressible flows. A physics-preserving pure streamfunction formulation is first introduced for the steady 3D incompressible Navier–Stokes (NS) equations without in-flow and out-flow boundary conditions, where the divergence of streamfunction ∇ · ψ is maintained in the convective and the vortex-stretching terms together in the nonlinear term of equations to reduce the physics-informed loss. Moreover, taking the streamfunction-vector components and their first-order partial derivatives as unknown variables, some fourth-order compact schemes are suggested for the partial derivatives that appear in the streamfunction formulation, and a high-resolution HOC scheme is introduced for approximating the pure third-order partial derivatives in the convective term. Meanwhile, a new HOC scheme is proposed for the first-type boundary conditions of the streamfunction. Finally, a fourth-order compact difference scheme and its algorithm are established for the 3D steady incompressible NS equations in the streamfunction form, subject to no in-flow and out-flow boundary conditions. Several numerical examples are carried out to validate and prove the accuracy, convergence, and efficiency of the proposed new method. Numerical results reveal that the proposed method not only can achieve fourth-order accuracy but also has excellent convergence, high-resolution, and low computational cost at higher Reynolds number.
Raman spectroscopic characterizations of graphene on oxide substrates for remote epitaxy
Authors: Shrestha S. , Chang C. S. , Lee S. , Kothalawala N. L. , Kim D. Y. , Minola M. , Kim J. , Seo A.
Published: March 2023

Graphene layers placed on SrTiO3 single-crystal substrates, i.e., templates for remote epitaxy of functional oxide membranes, were investigated using temperature-dependent confocal Raman spectroscopy. This approach successfully resolved distinct Raman modes of graphene that are often untraceable in conventional measurements with non-confocal optics due to the strong Raman scattering background of SrTiO3. Information on defects and strain states was obtained for a few graphene/SrTiO3 samples that were synthesized by different techniques. This confocal Raman spectroscopic approach can shed light on the investigation of not only this graphene/SrTiO3 system but also various two-dimensional layered materials whose Raman modes interfere with their substrates.
A least squares perspective of Green–Gauss gradient schemes
Authors: Deka Mandeep , Assam Ashwani , Natarajan Ganesh
Published: March 2023

The least squares and Green–Gauss gradient schemes have been traditionally studied as two distinct techniques for gradient computation on unstructured meshes in the literature. In this Letter, we show that the Green–Gauss gradient method can be interpreted as a weighted least squares gradient scheme and that methods of the Green–Gauss family may therefore be encompassed in the larger set of least squares-based gradient schemes.
Contamination by antibiotics and their degradation and removal methods
Authors: Yu Chan , Huang Huawei , Jin Haiyang , Zhang Wei , Lv Zhanao , Zhao Liangyuan
Published: March 2023

Context Antibiotics are a new pollutant with biological activity. In recent decades, the presence and fate of antibiotics in water environment have received special attention because of their persistence and resistance to biodegradation and potential risks to ecological and human health. Aims This review addresses the current state of antibiotics, concerning the input sources and the distribution characteristics in China, and mainly summarised the degradation and removal methods applied to the antibiotics. Methods The relevant literature from the past 20 years was reviewed, the distribution of antibiotics in China was summarised, and the method of removing antibiotics was proposed. Key results Further optimisation and combination of the above methods was an important development direction in the future. Conclusions The results showed that, at present, antibiotic pollution in the middle and lower reaches of the Yangtze River and the lakes in China is serious, posing a potential threat to human health and the entire ecosystem. Conventional treatment, oxidative degradation and physical removal could remove degradable antibiotics to a certain extent. Further optimisation and combination of the above methods will be an important development direction in the future. Implications The research results provided data support for exploring effective antibiotic removal methods.
Frequency effects and aspect morphology with state verbs in heritage Spanish
Authors: Thane Patrick D.
Published: March 2023

A total of 54 HS and 17 Spanish-dominant participants completed an elicited production task (EPT) and a forced choice task (FCT) to explore how proficiency, frequency of use, age of acquisition of English, morphological regularity, and lexical frequency affected their production and selection of preterit morphology with states. Results showed that HS’ production of preterit with states was negatively correlated with lexical frequency, such that these bilinguals were more likely to use the preterit with less-frequent verbs. Higher-proficiency speakers were less susceptible to the effects of lexical frequency in production. In contrast, proficiency modulated HS’ responses in the FCT. HS were more likely to select the preterit in the FCT than to produce it in the EPT. Together, these results support theories of heritage language acquisition that emphasize the role of activation of linguistic features and asymmetries between production and comprehension.
The characteristic initial value problem for the conformally invariant wave equation on a Schwarzschild background
Authors: Hennig Jörg
Published: March 2023

We resume former discussions of the conformally invariant wave equation on a Schwarzschild background, with a particular focus on the behaviour of solutions near the ‘cylinder’, i.e. Friedrich’s representation of spacelike infinity. This analysis can be considered a toy model for the behaviour of the full Einstein equations and the resulting logarithmic singularities that appear to be characteristic for massive spacetimes. The investigation of the Cauchy problem for the conformally invariant wave equation (Frauendiener and Hennig 2018 Class. Quantum Grav.
35 065015) showed that solutions generically develop logarithmic singularities at infinitely many expansion orders at the cylinder, but an arbitrary finite number of these singularities can be removed by appropriately restricting the initial data prescribed at t = 0. From a physical point of view, any data at t = 0 are determined from the earlier history of the system and hence not exactly ‘free data’. Therefore, it is appropriate to ask what happens if we ‘go further back in time’ and prescribe initial data as early as possible, namely at a portion of past null infinity, and on a second past null hypersurface to complete the initial value problem. Will regular data at past null infinity automatically lead to a regular evolution up to future null infinity? Or does past regularity restrict the solutions too much, and regularity at both null infinities is mutually exclusive? Or do we still have suitable degrees of freedom for the data that can be chosen to influence regularity of the solutions to any desired degree? In order to answer these questions, we study the corresponding characteristic initial value problem. In particular, we investigate in detail the appearance of singularities at expansion orders

n
=
0
,
…
,
4

for angular modes

ℓ
=
0
,
…
,
4

.
Interaction of atmospheric pressure helium plasma jet with tilted dielectric target: split and deviation of ionization waves
Authors: Liu Guoqiang , Xia Yang , Han Lei , Shang Kefeng , Liu Dongping
Published: March 2023

Atmospheric pressure plasma jets (APPJs) are commonly used plasma sources in many biomedical applications. Typically, the APPJs are not always perpendicular to the target to be treated. In this paper, the effects of tilted angle (

α

), relative permittivity (

ε

r

) of the target, the target potential, the distance (

d

) and the discharge parameters on the interaction of a helium APPJ with the target are investigated. Spatio-temporal resolved images show that the ionization wave (IW) split into a surface ionization wave (SIW) and a continued propagate IW when it approaches the target. The split leads to a position deviation of the IW interaction with the target. The measurements show that the split and deviation of IWs are strongly dependent on

α

and

ε

r

. For

ε

r

⩾

9, the split can be only observed with

α

<

60°. The deviation gradually decreases as

α

increases from 15° to 90° with

ε

r

=

9. With the increase of

ε

r

from 9 to 56, the split and deviation are more pronounced with

α

= 30°. The deviation gradually increases as applied voltage and

d

values increase from 5.5 to 10.0 kV and 19–24 mm, respectively. However, the deviation is independent of the gas flow rate of 400–2000 standard cubic centimeters per minute. The split of IW depends on the combined effect of enhanced electric field due to target polarization and mismatch between the propagation direction of IW and the direction of enhanced electric field caused by

α

variation. An increase in

ε

r

results in a stronger dielectric polarization effect. Changes in

α

cause a misalignment between the propagation direction of IW and the direction of enhanced electric field. Additionally, decreasing

α

shortens the perpendicular distance (

d

sin

α

) between IW and the target surface, further enhancing the electric field in the perpendicular direction. After the split, there is an interaction between the SIW and the IW. The propagation of the SIW is restricted to the local electric field of IW.
Multifunctional praseodymium-doped composite silica glasses for UV shielding and photonic applications
Authors: Gracie P J , Geetha D , Battisha I K
Published: March 2023

Silica phosphate glasses strengthened with a calcium oxide modifier and doped with different concentrations (0%, 0.5%, 1%, 1.5 mol%) of praseodymium (Pr3+) were synthesized by a sol–gel method. The absence of sharp peaks in the X-ray diffraction spectra confirms the noncrystallinity of the glasses. Higher doping indicates increasing optical bandgaps due to Burstein–Moss shift, which also reflects on structural disorders at the absorption tails, as validated by Urbach’s rule. The density increases with a subsequent decrease in oxygen-packing density, proving the mechanical and chemical stability of the glasses. The composite glasses are multifunctional with marked absorption at 280 nm predicting their purpose as UV shielding films. Luminescence corresponding to the intra 4f transition,

1

D

2

→

1

G

4

in the infrared region, with high transmission and low reflection losses suggests the use of the synthesized glass material for S-band telecommunications, while the radiative process involving

3

P

0

→

3

F

2

yields a predominant red laser source. Commission International de l’Eclairage color coordinates observe warmer red emission corresponding to a correlated color temperature of 3200 K. The composite silica phosphate glass systems evidence the effective role of Pr3+ for photonic applications.
Calibration of a circular structured light measurement system based on a multi-diameter calibrator
Authors: Zhao Huining , Zhang Zuo , Fan Mengyao , Xia Haojie , Yu Liandong
Published: March 2023

To solve the measurement problems of the inner shape of large-scale workpieces, such as excavators with movable arms, this paper proposes an inner shape measurement method based on circular structured light. First, the center of the circular laser stripe is extracted based on a modified Steger method. Second, a multi-diameter concentric calibration gauge design is used to calibrate the optical plane of the proposed system and address the problem of the optical plane deviation and motion error in the 1D linear stage of the traditional calibration process. Finally, the experiments are conducted. The corresponding experimental results demonstrate that the proposed measurement method facilitates a fast calibration of the camera and an efficient extraction of the center of the light stripe, resulting in a relative error of less than 0.012%. The measurement method can be further applied to deep-hole workpieces, such as steel tubes and natural gas tube lines, among others.
An SI-traceable multilateration coordinate measurement system with half the uncertainty of a laser tracker
Authors: Guillory Joffray , Truong Daniel , Wallerand Jean-Pierre , Svantesson Claes-Göran , Herbertsson Magnus , Bergstrand Sten
Published: March 2023

We have validated the performance of a prototype coordinate measurement system based on multilateration by comparing it to a laser tracker, i.e. a well-proven instrument widely used in the industry. After establishing the uncertainty budget of the different systems, we performed position measurements with both instruments on common targets. Using the estimated uncertainties associated with the measurements, we found that the multilateration system provided lower position uncertainties than the laser tracker: on average 18 µm versus 33 µm for distances up to 12 m. The uncertainties represented by confidence ellipsoids are compatible between the two systems: for confidence regions of 95% probability, they overlap as expected, i.e. in 94% of the cases. We also measured the length of a 0.8 m long reference scale bar with the multilateration system at an error of only 2 µm. This cross-comparison is a new and key step in the characterization of this SI-traceable multilateration system.
Staying recognised as clever: high-achieving physics students’ identity performances
Authors: Bøe Maria Vetleseter
Published: March 2023

Physics is criticized for a strong disciplinary culture that many students struggle to identify with. This study uses 12 longitudinal interviews with four high-achieving students in Norway, following them from secondary physics and into university science, technology, engineering, and mathematics (STEM) studies, exploring how they perform their identities within physics. Data were analysed thematically, and findings include that recognition as clever at something difficult motivated the students to engage with physics in certain ways, mainly doing what it takes to excel on tests and get top marks. When they entered prestigious university STEM programmes with different demands and peers, the students modified their behaviour to maintain recognition as clever. I argue that the way these students engage with physics is formed by a culture of achivement, and that by working to be and stay recognised as clever at something difficult, the students contribute to reinforcing the same culture. Implications include broadening what is recognised in our classrooms as being good at physics, especially moving beyond solving problems correctly and including scientific practices such as asking questions, collaboration, and argumentation.
The problem of capturing marginality in model reductions of turbulence
Authors: Gillot C , Dif-Pradalier G , Sarazin Y , Bourdelle C , Bañón Navarro A , Camenen Y , Citrin J , Di Siena A , Garbet X , Ghendrih Ph , Grandgirard V , Manas P , Widmer F
Published: March 2023

Reduced quasilinear and nonlinear (gradient-driven) models with scale separations, commonly used to interpret experiments and to forecast turbulent transport levels in magnetised plasmas, are tested against nonlinear models without scale separations (flux-driven). Two distinct regimes of turbulence—either above threshold or near marginal stability—are investigated with Boltzmann electrons. The success of reduced models hinges in particular on the reproduction of nonlinear fluxes. Good agreement between models is found above threshold, whilst reduced models significantly underpredict fluxes near marginality, overlooking mesoscale flow organisation and turbulence self-advection. Constructive prescriptions whereby to improve reduced models are discussed.
Nonlinearity modulation in a mode-localized mass sensor based on electrostatically coupled resonators under primary and superharmonic resonances
Authors: Lyu Ming , Zhao Jian , Kacem Najib , Song Jiahao , Fan Kefeng , Liu Pengbo , Huang Yu
Published: March 2023

A general model of a mode-localized mass sensor incorporating two weakly coupled clamped-clamped microbeams under electrostatic excitation is presented, and a reduced-order model considering quadratic and cubic nonlinearities is established. The multiple time scales method is used to solve the dynamic characteristics of the coupled resonators under primary resonance, simultaneous superharmonic and primary excitations, and one-third superharmonic resonance respectively, and to analyze the contribution of each harmonic excitation term. It is shown that the sensor can display softening, hardening, and linear behaviors by tuning the overall nonlinear coefficient in three different excitation scenarios. Furthermore, the conditions for restoring linear behavior with the highest possible amplitude without any hysteresis under different excitations are obtained. Finally, the mass sensitivities represented by the relative shift of amplitude ratio are calculated for all the resulting dynamic behaviors. The results show that the sensitivity is highest, for the hardening behavior in the in-phase mode and for the softening behavior in the out-of-phase mode. Interestingly, the sensitivities of the linear behavior obtained by nonlinearity modulation are the same for the two vibration modes, which is improve the output stability. Consequently, the sensor resolution can be significantly enhanced below the pull-in instability, while avoiding noise mixing.
Design and metrological studies of a reference UV- index detector
Authors: Abdel Baset Yasmen , Hamed Sawsan , Reda Sameh , Farag Hamed , Ghany H A Abdel , Faramawy Samaa
Published: March 2023

The ultraviolet index UVI is a very important parameter used to inform the public about UV disadvantages . This can affect human health and lead to several issues. Many manufacturers have developed UV-index UVI radiometers based on the detection of the UV actinic spectral range. The response band of these radiometers is far from the actual actinic spectral range. This study aims to build a UVI detector of the actual actinic spectrum reaching the Earth to be used as a reference standard in the radiometry lab at NIS Egypt. The novelty of this study is the selection of a ready-manufactured sensor based on a GaP Schottky photodiode sensor to solve the defects in the present UVI radiometer and a careful selection of a short-pass filter and transmission diffuser. The calibration and measurement facilities available at NIS Egypt were used to describe the components. The designed detector response at 280–400 nm was used to capture the actual actinic spectrum. Several metrological studies were carried out in the laboratory to characterize the performance of the UVI detector, including spectral matching, angular response measurement, linearity, and spatial non-uniformity response. The results show and discuss the radiometric characterization of this detector.
Adjustment of eccentricity and split angle for improved SERS and refractive index sensing of TiN nanodonuts
Authors: Rong WangXu , Du ChaoLing , Lei MingXin , Zhang XiaoYang , Ding YiHan , Li Xiang , Shi DaNing
Published: March 2023

The unique refractory plasmonic properties and strong enhancement of the electric field within the inherent gap of titanium nitride (TiN) nanodonuts make them excellent candidates for surface-enhanced Raman scattering (SERS)- and refractive index (RI)-sensing applications. The eccentricity and split angles are critical parameters for tuning the localized surface plasmon resonance (LSPR) properties of the donuts, which were numerically investigated using the finite element method herein. We demonstrated that the proposed donuts provided efficient SERS and RI sensing substrates capable of working in regions ranging from ultraviolet (UV) to near-infrared (NIR). By adjusting the eccentricity and split angles, the corresponding optimized RI sensitivity and SERS enhancement factor reached 1,374 nm RIU−1 and 6.8 × 104, respectively. Moreover, the effects of both incident polarisation and electromagnetic (EM) field distributions on the LSPR properties were elucidated and discussed. This study provides new insights for understanding the LSPR properties of TiN nanoparticles and enables the rational design of efficient refractory plasmon-based SERS and RI-sensing substrates.
Natural line profile asymmetry
Authors: Anikin A , Zalialiutdinov T , Solovyev D
Published: March 2023

The paper discusses the line profile asymmetry of the photon scattering process that arises naturally in quantum electrodynamics (QED). Based on precision spectroscopic experiments conducted on hydrogen atoms, we focus our attention on the two-photon 1s − 2s transition. As one of the most precisely determined transition frequencies, it is a key pillar of optical frequency standards and is used in determining fundamental physical constants, testing physical principles, and searching constraints on new fundamental interactions. The results obtained in this work show the need to take into account the natural line profile asymmetry in precision spectroscopic experiments.
Tabletop potentials for inflation from f(R) gravity
Authors: Shtanov Yuri , Sahni Varun , Mishra Swagat S.
Published: March 2023

We show that a large class of modified gravity theories (MOG) with the Jordan-frame Lagrangian f(R) translate into scalar-field (scalaron) models with hilltop potentials in the Einstein frame. (A rare exception to this rule is provided by the Starobinsky model for which the corresponding scalaron potential is plateau-like for ϕ > 0.) We find that MOG models featuring two distinct mass scales lead to scalaron potentials that have a flattened hilltop, or tabletop. Inflationary evolution in tabletop models agrees very well with CMB observations. Tabletop potentials therefore provide a new and compelling class of MOG-based inflationary models. By contrast, MOG models with a single mass scale generally correspond to steep hilltop potentials and fail to reproduce the CMB power spectrum. Inflationary evolution in hilltop/tabletop models can proceed in two alternative directions: towards the stable point at small R describing the observable universe, or towards the asymptotic region at large R. The MOG models which we examine have several new properties including the fact that gravity can become asymptotically vanishing, with G
eff → 0, at infinite or large finite values of the scalar curvature R. A universe evolving towards the asymptotically vanishing gravity region at large R will either run into a 'Big-Rip' singularity, or inflate eternally.
Constraints on primordial-black-hole population and cosmic expansion history from GWTC-3
Authors: Chen Zu-Cheng , Du Shen-Shi , Huang Qing-Guo , You Zhi-Qiang
Published: March 2023

Gravitational waves (GWs) from compact binary coalescences provide an independent probe of
the cosmic expansion history other than electromagnetic waves. In this work, we assume the binary
black holes (BBHs) detected by LIGO-Virgo-KAGRA (LVK) collaborations are of primordial origin and
constrain the population parameters of primordial black holes (PBHs) and Hubble parameter H(z)
using 42 BBHs from third LVK GW transient catalog (GWTC-3). Three PBH mass models are
considered: lognormal, power-law, and critical collapse PBH mass functions. By performing a
hierarchical Bayesian population analysis, the Bayes factor strongly disfavors the power-law PBH
mass function against the other two in GWTC-3. The constraints on standard Λ CDM
cosmological parameters are rather weak and in agreement with current results. When combining the
multi-messenger standard siren measurement from GW170817, the Hubble constant H
0 is constrained
to be 69-8
+19 km s-1 Mpc-1 and 70-8
+26 km s-1 Mpc-1 at 68% confidence for the lognormal and
critical collapse mass models, respectively. Furthermore, we consider a mixed ABH+PBH model, in
which we assume LVK BBHs can come from both the astrophysical black hole (ABH) and PBH
channels. We find that the ABH+PBH model can better describe the mass distribution in GWTC-3 than
any single ABH or PBH model, thus improving the precision to constrain the Hubble constant. With
the increased BBH events, the mixed ABH+PBH model provides a robust statistical inference for both
the population and cosmological parameters.
Parametric dependence of microwave beam broadening by plasma density turbulence
Authors: Holland L.A. , Köhn-Seemann A. , Vann R.G.L.
Published: March 2023

High-power microwave beams used for heating and current drive in magnetically confined fusion plasmas can be broadened significantly by plasma turbulence, negatively impacting the efficiency of the machine. The dependence of this beam broadening on plasma and beam parameters is not yet fully understood, particularly where the dependence on one parameter is not separable from the dependence on the other parameters, meaning the dependence must be expressed via functions of linear combinations of parameters, rather than functions of single parameters. The aim of this work is to develop an empirical model for how the broadening depends on plasma and beam parameters, allowing for the easy estimation of beam broadening by turbulence without the need for computationally expensive full-wave simulations. In this paper, a microwave beam is simulated propagating through a turbulent layer of plasma using the 2D full-wave cold plasma code EMIT-2D. The dependence of beam broadening on background plasma density, fluctuation amplitude, turbulence correlation lengths in the radial and poloidal direction, thickness of the turbulence layer, and microwave beam waist are considered. The parameter scans are conducted in pairwise combinations of the parameters in order to determine the separability of the dependencies. We find that the dependence on the radial and poloidal correlation lengths are not separable from each other, and neither are the dependences on the fluctuation level and the background density, but all other dependencies are separable. Ignoring this inseparability in the correlation lengths will usually result in an over-prediction of the broadening in tokamak plasmas. An empirical formula for the beam broadening based on the turbulence and beam parameters is found for fusion-relevant scenarios, making prediction of the effect possible in microseconds, instead of the hours required for full-wave simulation. This could then be of use for integrated modelling of heating and current drive systems.
Feynman-Kac theory of time-integrated functionals: Itô versus functional calculus
Authors: Dieball Cai , Godec Aljaž
Published: March 2023

The fluctuations of dynamical functionals such as the empirical density and current as well as heat, work and generalized currents in stochastic thermodynamics are usually studied within the Feynman-Kac tilting formalism, which in the Physics literature is typically derived by some form of Kramers-Moyal expansion, or in the Mathematical literature via the Cameron-Martin-Girsanov approach. Here we derive the Feynman-Kac theory for general additive dynamical functionals directly via Itô calculus and via functional calculus, where the latter results in fact appears to be new. Using Dyson series we then independently recapitulate recent results on steady-state (co)variances of general additive dynamical functionals derived recently in Dieball and Godec (2022 Phys. Rev. Lett.
129 140601) and Dieball and Godec (2022 Phys. Rev. Res.
4 033243). We hope for our work to put the different approaches to the statistics of dynamical functionals employed in the field on a common footing, and to illustrate more easily accessible ways to the tilting formalism.
Twinned dendrites in CrB-structured intermetallic NiGd
Authors: Niersbach T , Kolbe M , Becker M , Kargl F
Published: March 2023

The formation of twinned dendrites was investigated in orthorhombic CrB-structured NiGd. A NiGd droplet embedded in borosilicate glass-flux was processed by differential scanning calorimetry. A small undercooling of ≈ 20 °C was reached and a cross-section of the solidified sample was analyzed with EBSD. A twinned dendrite is found, that exhibits a twin boundary in its center, both parts sharing a <110> direction and a misorientation angle of 40° between its two parts. The present findings are in agreement with model predictions for CrB-structured alloy solidification based on the investigation of deeply undercooled and homogeneously nucleating NiZr. The present investigation on NiGd serves as a first important step to validate the model’s predictions. Due to the observation of twinned dendrites at small undercoolings, the present study may further serve as a first-step to extend the model to heterogeneous growth regimes.
Effect of Eu and P additions with Ta grain refiner on the solidification microstructure of Al-7Si-0.3Mg alloys
Authors: Spacil I , Schumacher P , Li J
Published: March 2023

Al-7Si-0.3Mg based alloys have been widely used. Nevertheless, at least three issues during melt treatment (grain refinement of Al grains, modification of eutectic Si and refinement of eutectic grain size) need to be further explored. In this contribution, we focus on these three melt treatments. For grain refinement of Al grains, the stochiometric Al-2.2Ti-1B grain refiner rod together with 0.12 wt. % Ta was used. For modification of eutectic Si, Eu up to 500 ppm was used. The best modification can be obtained with 200 ppm Eu. By further increasing Eu up to 500 ppm, modification level becomes worse due to the formation of Al2Si2Eu. For the refinement of eutectic grain size, a combined addition of Eu (up to 500 ppm) and P (up to 40 ppm) was used. With increasing P concentration, the modification of eutectic Si became worse. The size of eutectic Si increases, the shape factor of eutectic Si decreases. When the P concentration is higher, more Eu is needed for a well-modified eutectic Si. This investigation provides a novel concept for melt treatment of Al-Si-Mg based alloys.
Accelerated material development for laser powder-bed fusion using the arc melting process
Authors: Reiersen M , Gunnaes A E , Azar A S , Diplas S , Du Q , M’hamdi M.
Published: March 2023

Metal additive manufacturing has in recent years gained an increasing amount of attention, especially the subgroup of laser powder-bed fusion and aluminium alloys. However, established alloys are designed for casting and forging and often require alterations to make them eligible for the challenging processing conditions. The material selection is limited and calls for new alloys tailored specifically for additive manufacturing. In this work, an analysis suite is proposed as a tool to investigate material systems quickly and in-expensively for use in additive manufacturing. The selected material system is the Al7075 aluminium alloy, which is susceptible to cracking caused by hot tearing. To resolve this issue, it is mixed with varying quantities of silicon. The effect of silicon on solidification, grain refinement, and the resulting crack susceptibility is investigated with thermodynamical calculations considering the columnar to equiaxed transition, optical microscopy, and scanning electron microscopy after being processed by arc melting. The thermodynamical calculations of the compositions indicated a trend between the decreased columnar to equiaxed transition point at elevated temperature gradients to the silicon concentration. The experimental results reflected a similar trend by observing the reduction of the average grain size in the material system from 2470 μm2 to 323 μm2 for a composition with 0 wt.% and 10.5 wt.% silicon respectively. A composition of interest from the result was further mixed with zirconium hydride to investigate its grain refining properties on the alloy. The average grain size was reduced from 1055 μm2 to 453 μm2 by the inclusion of 0.24 wt.% zirconium. As such, this work provides a new approach to investigating a material system for use in additive manufacturing.
Influence of stirring process during slurry formation on the casting defects and high-temperature fatigue of rheocast AlSi7Mg alloys
Authors: Zaffarani P , Zhang Q , Jarfors A E W , Timelli G
Published: March 2023

The effects of the stirring phase during slurry formation on the defect’s content and the influence on the high-temperature fatigue behaviour of a rheocast AlSi7Mg alloy were investigated. Single or double-stir step was used during RheoMetal processing. Metallographic and image analysis techniques were performed to quantitatively examine the defect’s changes occurring with different stirring methods. Samples were cross-sectioned along the gauge length, and the pores content was measured. Uniaxial fatigue tests were performed at high temperature (150 °C) with the staircase method, applying a stress ratio of R = −1. Fracture surfaces were examined using a scanning electron microscope to determine the fatigue crack initiation sites, type and size of the defects. Shrinkage porosity has more probability of acting as a crack initiator than gas porosity or oxides. The double-stir step effectively reduces the size of pores compared to the conventional technique; it reduces porosity to less than half if compared to the single-stir process. Shrinkage pores distribution show a higher population of smaller pores for the double-stir process. According to the Dixon-Mood formula, the mean fatigue strengths are comparable. The capability of the double-stir to reduce porosity is evident, even having no significant effect on the high-temperature fatigue life.
Numerical modelling of porosity with combined gas and shrinkage effects in HPDC
Authors: Godwal U , Bhagavath S , Ghaffari B , Li M , Lee P D , Karagadde S
Published: March 2023

High-pressure die casting is a manufacturing process in which near-net-shape components are produced rapidly under a pressurized environment. However, due to the relatively higher cooling rate prevailing during the process, isolated liquid pockets form at certain locations, leading to increased porosity formation. A one-dimensional deformable grid numerical model has been developed for predicting the evolution of a single pore in an elementary volume, which combines the diffusion model with the shrinkage affected growth. The model accounts for the change in pore size due to shrinkage and inter-granular growth. This model can provide predictions in representative volumes and be used for component level predictions by combining with a macroscopic model.
In-situ investigation of the solidification dynamics in an irregular eutectic alloy
Authors: Mohagheghi S , Bottin-Rousseau S , Şerefoğlu M
Published: March 2023

We present an in-situ experimental investigation of irregular eutectic growth dynamics observed optically in real time during directional solidification (DS) and rotating directional solidification (RDS) of a model transparent alloy, namely Amino-methyl-propanediol-Succinonitrile (AMPD-SCN). The SCN-rich solid grows with a nonfaceted solid-liquid interface, while AMPD forms thin whisker-like faceted crystals. With RDS, we observed simultaneously four distinct growth dynamics along the solidification front thanks to the rotation induced velocity ramp. At low velocity, AMPD crystals grow individually, with their leading tip ahead of – at a higher temperature than – the SCN-liquid interface which presents a linear undercooling change with V ramp. This regime is defined as a quasi-steady decoupled growth. During RDS, AMPD crystals are found to rotate with the sample in this regime. When they can reach the unsteady coupled-growth regime at higher V, since increasing V favors the formation of AMPD-SCN-liquid trijunctions, they start to branch noncrystallographically. At higher velocity, impurity effects lead to the formation of two-phase fingers. Further increase in the velocity results in the formation of primary SCN dendrites and a fine interdendritic eutectic microstructure. DS experiments confirmed the existence of those regimes at different velocities.
Pseudo-4D view of the growth and form of crystallographically ‘locked’ eutectic colonies
Authors: Chao P , Lindemann G R , Shahani A J
Published: March 2023

A number of fundamental questions remain unanswered regarding the interior structure of eutectic cells or colonies growing into a liquid. Here, we observe experimentally the solidification behaviour of an Al-Al2Cu eutectic as a model system using a novel imaging approach that combines in situ X-radiography and ex situ X-ray tomography. The former allows us to trace the solid-liquid interfaces while the latter enables us to visualize the solid-solid interfaces. When put together, we can visualize in 4D (i.e., three-dimensional space plus time) the development of a crystallographically ‘locked’ eutectic microstructure in the presence of an oscillatory eutectic-liquid velocity driven by thermosolutal convection. These details provide direct insight into the mechanism of the lamella-to-rod transition as the eutectic accommodates fluctuations in interfacial composition and growth velocity. We find that this morphological transition reflects a delicate balance between the motion of trijunctions and the stiffness of low-energy, solid-solid interfaces. Our pseudo-4D tomography approach holds broad appeal to the solidification science community, as it can temporally resolve the solidification process on the order of seconds and spatially resolves individual lamellae on the order of micrometres, thereby overcoming the space-time trade-off in conventional in situ X-ray tomography.
Microstructure evolution induced by solidification and ferrite–austenite massive-like transformation in Fe–C alloys
Authors: Tsuji S , Nanri T , Narumi T , Katsube R , Yasuda H
Published: March 2023

The coarsening of austenite grains produced through a massive-like transformation from the ferrite to the austenite phase during/after solidification in Fe–0.45mass%C steel was examined through time-resolved X-ray diffraction measurements using time-resolved computed tomography. The δ phase solidification resulted in a single δ grain in the observation region (0.6 mm in diameter, 0.1 mm in height). The massive-like transformation produced multiple γ grains, and coarsening immediately followed the transformation. The coarsening in the observation region was completed even within 200 s. A correlation of crystallographic orientation between the γ grains was found in the γ grain structure. The massive-like transformation frequently produced fcc (111) twinned grains, and the twinned austenite grains tended to remain during coarsening because the twin interface energy is lower than the grain boundary energy. The massive-like transformation following the solidification contributed to the texture formation in the γ grain structure.
Microstructural study of containerless solidification of Al-5wt%Ce alloy
Authors: Valloton J , Vogel S C , Henein H
Published: March 2023

Containerless solidification of Al-5wt%Ce is investigated experimentally using the electromagnetic levitation technique. The processed samples show small primary undercooling and minimal eutectic undercooling. Phase fractions determined by neutron diffraction are similar to the values obtained from a Scheil-Gulliver solidification simulation. Significant solidification shrinkage at the top of the samples indicate that solidification started at the bottom and the front propagated upwards. X-ray microscopy results show multiple nucleation events throughout the samples.
An example of a non-amenable dynamical system which is boundary amenable
Authors: Bassi Jacopo , Rădulescu Florin
Published: March 2023

It is shown that the action of

SL
⁡
(
3
,

Z

)

\operatorname {SL}(3,\mathbb {Z})

on the Stone-Čech boundary of

SL
⁡
(
3
,

Z

)

/

SL
⁡
(
2
,

Z

)

\operatorname {SL}(3,\mathbb {Z}) / \operatorname {SL}(2,\mathbb {Z})

is amenable. This confirms a prediction by Bekka and Kalantar [Trans. Amer. Math. Soc. 373 (2020), pp. 2105–2133].
𝑝-group Galois covers of curves in characteristic 𝑝
Authors: Garnek Jędrzej
Published: March 2023

We study cohomologies of a curve with an action of a finite

p
p

-group over a field of characteristic

p
p

. Assuming the existence of a certain “magical element” in the function field of the curve, we compute the equivariant structure of the module of holomorphic differentials and the de Rham cohomology, up to certain local terms. We show that a generic

p
p

-group cover has a “magical element”. As an application we compute the de Rham cohomology of a curve with an action of a finite cyclic group of prime order.
T-Cell Prolymphocytic Leukemia With t(X;14)(q28;q11.2): A Clinicopathologic Study of 15 Cases
Authors: Hu Zhihong , Medeiros L Jeffrey , Xu Mina , Yuan Ji , Peker Deniz , Shao Lina , Tang Zhenya , Mai Brenda , Thakral Beenu , Rios Adan , Hu Shimin , Wang Wei
Published: March 2023

Objectives

T-cell prolymphocytic leukemia (T-PLL) is a rare mature T-cell leukemia usually characterized by inv(14)(q11.2q32)/t(14;14)(q11.2;q32). In this study, we aimed to investigate the clinicopathologic features and molecular profile of T-PLL associated with t(X;14)(q28;q11.2).

Methods

The study group included 10 women and 5 men with a median age of 64 years. All 15 patients had a diagnosis of T-PLL with t(X;14)(q28;q11.2).

Results

All 15 patients had lymphocytosis at initial diagnosis. Morphologically, the leukemic cells had features of prolymphocytes in 11 patients, small cell variant in 3, and cerebriform variant in 1. All 15 patients had hypercellular bone marrow with an interstitial infiltrate in 12 (80%) cases. By flow cytometry, the leukemic cells were surface CD3+/CD5+/CD7+/CD26+/CD52+/TCR α/β+ in 15 (100%) cases, CD2+ in 14 (93%) cases, CD4+/CD8+ in 8 (53%) cases, CD4+/CD8– in 6 (40%) cases, and CD4–/CD8 + in 1 (7%) case. At the cytogenetic level, complex karyotypes with t(X;14)(q28;q11.2) were seen in all 15 patients assessed. Mutational analysis showed mutations of JAK3 in 5 of 6 and STAT5B p.N642H in 2 of 6 patients. Patients received variable treatments, including 12 with alemtuzumab. After a median follow-up of 17.2 months, 8 of 15 (53%) patients died.

Conclusions

T-PLL with t(X;14)(q28;q11.2) frequently shows a complex karyotype and mutations involving JAK/STAT pathway, and it is an aggressive disease with a poor outcome.
Frailty Among Breast Cancer Survivors: Evidence From Swedish Population Data
Authors: Wennberg Alexandra M , Matthews Anthony , Talbäck Mats , Ebeling Marcus , Ek Stina , Feychting Maria , Modig Karin
Published: March 2023

Incidence and survival of breast cancer, the most common cancer among women, have been increasing, leaving survivors at risk of aging-related health conditions. In this matched cohort study, we examined frailty risk with the Hospital Frailty Risk Score among breast cancer survivors (n = 34,900) and age-matched comparison subjects (n = 290,063). Women born in 1935–1975, registered in the Swedish Total Population Register (1991–2015), were eligible for inclusion. Survivors had a first breast cancer diagnosis in 1991–2005 and survived ≥5 years after initial diagnosis. Death date was determined by linkage to the National Cause of Death Registry (through 2015). Cancer survivorship was weakly associated with frailty (subdistribution hazard ratio (SHR) = 1.04, 95% confidence interval (CI): 1.00, 1.07). In age-stratified models, those diagnosed at younger ages (<50 years) had higher risk of frailty (SHR = 1.12, 95% CI: 1.00, 1.24) than those diagnosed at ages 50–65 (SHR = 1.03, 95% CI: 0.98, 1.07) or >65 (SHR = 1.09, 95% CI: 1.02, 1.17) years. Additionally, there was increased risk of frailty for diagnoses in 2000 or later (SHR = 1.15, 95% CI: 1.09, 1.21) compared with before 2000 (SHR = 0.97, 95% CI: 0.93, 1.17). This supports work from smaller samples showing that breast cancer survivors have increased frailty risk, particularly when diagnosed at younger ages.