bluuebunny/crossref_metadata_2025 huggingface dataset:
A flexible methodology for generating 3D graphite dosimetry data in Advanced Gas-Cooled Reactors
Authors: Allen Dennis , Thornton Dean , Watson James , Shaw Simon
Published: November 2024

The safety cases for the UKs Advanced Gas-Cooled Reactors require a robust understanding of the structural integrity of their constituent graphite bricks. Both neutron damage and graphite weight loss have significant effects upon material properties. Graphite weight loss occurs via radiolytic oxidation, initiated by neutron and gamma-ray dose. This includes contributions from fast neutrons, gamma-rays from the fuel, and secondary gamma-rays. An accurate knowledge of the dosimetry history of trepanned graphite samples is important, as well as the ability to make forward predictions for any brick within the core. It is therefore necessary to calculate both these dosimetry quantities with a high degree of spatial accuracy, taking into account the time-varying nature of local fuel channel powers as well as the way in which weight loss itself affects the dosimetry data. The Monte Carlo method is the most accurate available for the calculation of radiation dosimetry data. However, it is impractical to undertake full scale Monte Carlo calculations for a whole reactor core and to represent every required period of time and graphite weight loss, which will also vary in time and space. An alternative approach has been developed by Jacobs which exploits the high accuracy afforded by the Monte Carlo method, but is also flexible and practical enough to provide 3D dosimetry data for any graphite brick within the active cores, at any point in time and at any required graphite weight loss. The Power Partitioning Method uses MCBEND-generated dosimetry “Contribution Matrices”, coupled with PANTHER “core follow” fuel powers, to calculate dosimetry data anywhere within selected fuel channels or interstitial bricks.
Four decades of progress in PWRs surveillance program dosimetry measurements at the MADERE platform
Authors: Fausser Clément , Domergue Christophe , Philibert Hervé , Bonora Jonathan , Pépino Alexandra , Bourganel Stéphane , Jeuland Kévin , Galant Céline , Subercaze Alexandre , Grégoire Gilles , Tisseur David , Destouches Christophe , Thiollay Nicolas
Published: November 2024

Since 1981, the French Alternative Energies and Atomic Energy Commission has been measuring the dosimeters of the surveillance capsules of the French pressurized water reactors and assessing their neutron fluence. This represents more than 250 surveillance PWR capsules, i.e. 4 thousands dosimeters. Started in Grenoble, this work continued in Cadarache with the creation of the “Measurement Applied to DosimEtry in Reactors” (MADERE) platform within the Dosimetry, Sensors and Instrumentation Laboratory (LDCI). Since 1998, all surveillance dosimeters measurements (i.e. Al-Co, 238U, 237Np, Ni, Cu, Fe and Nb) have been performed at MADERE under the “Cofrac Essais” accreditation according to the ISO/IEC 17025 international standard. The evolution over time of the 1σ measurement uncertainty of the activity of each is presented in this paper. Since 2015, they are [±1.3% ; ±2.9%] for 238U with Ni encapsulation, [±0.8% ; ±2.1%] for 238U with Ti encapsulation, [±1.2% ; ±4.9%] for 238U with stainless steel encapsulation, ±1.3% for 237Np dosimeters, ±1.2% for Al-Co, [±1.2% ; ±1.4%] for nickel, copper and iron, [±3.3%; ±3.9%] for niobium if unbroken after irradiation.
Activity measurements and calculations for gamma-emitting radionuclides in concrete drill cores of unit 2 of the Greifswald NPP
Authors: Poenitz Erik , Roode-Gutzmer Quirina Isabella , Barkleit Astrid , Konheiser Joerg
Published: November 2024

Due to Germany’s nuclear phase-out, decommissioning and final disposal of construction materials of Nuclear Power Plants (NPP) become increasingly important. The reliable determination of radionuclides produced by neutron activation, the activity as a function of time since shutdown and investigation of subsequent radionuclide mobility are subject of a research project. Drill cores of the concrete shielding of unit 2 of the Greifswald NPP were retrieved. Specific activities of gamma emitters and the elemental composition were measured. The radiation transport code MCNP 6 was used for the calculation of spectral neutron fluences. A neutron radiation field calculation reveals that the maximum neutron fluence at the concrete component is located in the floor just below the RPV. The concrete structures closest to the reactor core are shielded efficiently against neutron radiation by the annular water tank. Measured and calculated specific activities of 152Eu, 154Eu and 60Co for the cement screed at the position of the maximum neutron fluence are surprisingly low. A specific exemption (i.e. release from radiation protection surveillance but mandatory for final disposal) of the screed sample according to Germany’s Radiation Protection Ordnance is expected to be possible approximately 4 decades after the shutdown of the NPP.
Investigation of RPV samples of the Greifswald NPP with focus on retrospective dosimetry
Authors: Poenitz Erik , Konheiser Joerg
Published: November 2024

Reactor pressure vessel (RPV) samples of units 1 and 4 of the Greifswald NPP were investigated with focus on retrospective dosimetry. Specific activities of long-lived radionuclides 63Ni, 93mNb, 94Nb and 99Tc as well as the concentrations of the producing elements were measured. Investigated samples comprise base metal, welding metal and cladding of the RPV. Neutron fluences obtained with the M onte-Carlo codes TRAM O and M CNP were used to calculate specific activities. The gamma-emitter 94Nb appears as a promising candidate due to the large Nb concentration in the cladding of the VVER RPVs. For 93mNb, a very good agreement of measured und calculated activities was found for the RPV cladding samples where 93mNb is primarily produced by the threshold reaction 93Nb(n,n’)93mNb. A strong scatter of the ratios of calculated and experimental activities is observed for 63Ni which is primarily produced by slow neutrons. For 99Tc, a good agreement of calculated and measured activities was found for the majority of the base metal and welding metal samples but not for the cladding samples. Updated reaction cross section data for 62Ni(n,γ) and 92M o(n,γ) lead to a better agreement of calculated and measured activities for 63Ni and 93mNb.
Revision of PSI calculation capabilities and validation experience on the BEPU-type reactor dosimetry applications
Authors: Vasiliev Alexander , Ferroukhi Hakim , Pecchia Marko , Rochman Dimitri , Laureau Axel , Lamirand Vincent , Pautz Andreas
Published: November 2024

The present paper summarizes the experience accumulated at the Laboratory for Reactor Physics and Thermal-Hydraulics (LRT) of the Paul Scherrer Institute in the field of reactor dosimetry, as well as outlines the recent progress achieved in relation to the associated nuclear data uncertainty propagation methodologies. For dosimetry simulations, the CASMO/SIMULATE/MCNP/FISPACT-II system of codes is in operation at LRT/Nuclear Energy and Safety (NES) Research Division, which is based on the use of validated CASMO/SIMULATE cycle-specific core-follow models of Swiss LWRs. Coupling with FISPACT-II provides the capability for detailed isotopic inventory tracking under irradiation, assessment of materials activation and dpa values, etc. The use of the seamless calculation scheme with translation of the core-follow simulation results into the detailed neutron source specifications for consequent Monte Carlo simulations, accomplished with nuclear data uncertainty propagation capabilities and integrated with appropriate dosimetry validation database, makes the PSI methodology well aligned with the generic best estimate plus uncertainty (BEPU) approach principles. For specific illustrations, this paper presents some results on evaluation of: 1) a few well-known OECD/NEA reactor shielding experimental benchmarks (SINBAD benchmarks H.B. Robinson-2, ASPIS-PCA REPLICA), 2) some dosimetry data obtained from a Swiss PWR and 3) simulation of the dosimetry measurements for the ‘PETALE’ experimental program at the EPFL research reactor ‘CROCUS’, as they were foreseen at the time of the experimental planning. Finally, ways to further enhance the simulation methodology and models are discussed.
Ex-vessel neutron dosimetry results in the extended beltline region
Authors: Hayes Eugene T.
Published: November 2024

Embrittlement of the pressure vessel has been a long-standing concern for pressurized water reactors. Historically, the beltline region of the pressure vessel, or the region of the pressure vessel located opposite the active fuel, has been the primary focus of embrittlement concerns. Embrittlement evaluations typically include a calculation of the neutron flux incident on the pressure vessel, which is in part validated with measurements. In the context of life extension, the beltline region, which is technically defined as the portion of the pressure vessel experiencing fast neutron fluence (E > 1.0 MeV) equal to or greater than 1017 n/cm2, is growing axially. Present fluence calculations for many plants indicate that the beltline region at the end of the 60 years of operation may extend to the bottom of the pressure vessel nozzles. Calculations in the extended beltline are difficult to validate as there are few dosimetry measurements available. At one Westinghouse 4-loop plant, ex-vessel neutron dosimetry sensor sets were irradiated in the extended beltline region. The measurements in the extended beltline region compare well with the discrete ordinates (RAPTOR-M3G) transport calculations and indicate the net uncertainty may be on the order of 30% in the extended beltline region.
Results of the reactor dosimetry experiments performed for verification of the neutron transport calculations at the Hungarian Paks Nuclear Power Plant
Authors: Zsolnay Eva M. , Czifrus Szabolcs , Kis Dániel , Horváth András , Gerényi Anita
Published: November 2024

The operational lifespan of all four units at the Hungarian Paks Nuclear Power Plant (NPP) has been extended by 20 years beyond the original 30-year term. This extension has been implemented gradually, in one- to two-year increments, since 2013. The Hungarian Atomic Energy Authority, responsible for granting approval for these life extensions, has prescribed the continuous and rigorous monitoring of the reactor pressure vessel (RPV) throughout the plant’s extended service life. Among the key requirements is the validation of the neutron transport calculations, with specific attention to the large Lead Factor (LF), which reaches around 12 at the reactor core’s center. To meet these regulatory requirements, neutron transport calculations and reactor dosimetry measurements using neutron activation detectors (neutron monitors) have been conducted both inside and outside the RPV. Inside measurements were taken in the RPV surveillance channel, while outside measurements were conducted in the cavity adjacent to the outer wall of the RPV. These efforts aim to determine the key parameters of the neutron irradiation and validation is achieved if the experimental results agree with the neutron transport calculations at both the surveillance position and the RPV's outer wall (in the cavity), ensuring that the calculations are also valid for the inner wall of the RPV. This paper presents the validation of experimental data used to confirm the accuracy of the neutron transport calculations. The results of irradiations conducted over one- and four-year periods are compared and analyzed to demonstrate the authenticity of the experimental data for validation of the calculation results.
On radiation situation in vicinity of PET production cyclotron
Authors: Zmeškal Marek , Košt’ál Michal , Czakoj Tomáš , Šimon Jan , Schulc Martin , Vadják Šimon , Antoš Michal , Matěj Zdeněk
Published: November 2024

The medical cyclotrons intended for the production of medical isotopes are relatively widespread. The most common radioisotope product of these facilities is 18F which origins from 18O(p, n)18F reaction. Due to relatively large amounts of produced nuclei, the leakage neutron and gamma flux is a big issue in radiation safety in such cyclotron labs. Due to relatively high energies of accelerated protons, high energy gammas and neutrons are produced with energies above 10 MeV with high penetration properties. Neutron and gamma spectra around cyclotron IBA Cyclone 18/9 intended for production of 18F was measured with stilbene detector. It was compared to simulated neutron spectra with various Monte Carlo codes and with spectral indices calculated from reaction rates in activation detectors. Strong disagreement in simulation of spectra in backward angles was found for MC codes Geant4 and MCNP6.2.
Fast and thermal neutron spectrum dosimetry measurements in the Advanced Test Reactor large-B and small-l positions following the sixth core internals change-out
Authors: Reichenberger Michael , Maile Andrew , Johnson Matthew , Norman Daren , Bays Samuel , McCary Kelly , Manwaring Nathan
Published: November 2024

The Advanced Test Reactor (ATR) has a wide variety of irradiation positions that have had experiments that were developed by users from around the world. Most experiment irradiations rely on thoroughly benchmarked numerical models. However, some irradiation positions in ATR are not as well- characterized and are complicated by spectral perturbations from control cylinder orientation. The “small I” and “large-B” irradiation positions are located nearby control cylinders and suffer from these flux perturbations from control cylinder orientations that change during an irradiation cycle to maintain the desired core power distribution. Models predicted that these types of position would exhibit both spectral shifts and amplitude changes in neutron flux, but few measurements have been conducted to benchmark these predictions. Recently, requalification testing was performed to confirm the operational readiness of the ATR following the completion of the Core Internals Change-out (CIC). These tests provided a unique opportunity to validate the analytical methods used to simulate the ATR because nearly all components in the reactor were in a clean as-built state, significantly reducing modelling uncertainties. One subset of the testing included characterization of the fast and thermal neutron flux in the “small-I” and “large-B” positions using silver, cobalt, and nickel neutron dosimetry. In contrast to typical irradiation cycles, the control cylinders were held in position during the post-CIC nuclear testing. The specific activity of these dosimeter wires was measured following two low-power tests with different control cylinder positions.
MRI of the Elbow – Update 2024
Authors: Schinnerl Christoph , Weber Marc-André , Benninger Emanuel , Fischer Tim S. , Falkowski Anna L.
Published: November 2024

Elbow pain can result in significant morbidity. MRI can help diagnosing the cause of elbow pain.

Based on a systematic literature search as well as knowledge gained through frequent participation in conferences dedicated to advances in musculoskeletal imaging, this review aims to give a brief overview of normal anatomy and common pathologies of tendons and ligaments of the elbow on magnetic resonance imaging.

Stabilization of the elbow joint is provided by osseous structures and passive ligamentous and active muscular support. Loss of these important stabilizers, due to trauma and overuse, can result in elbow instability. Additional MR views or intra-articular contrast media can be useful for the detection of specific pathologies.

MRI is frequently used to detect posttraumatic or chronic conditions, which can lead to posterolateral or posteromedial elbow instability. Knowledge of normal anatomy, variants, pathologies, as well as appropriate imaging is crucial to make the diagnosis.
A new technique: Acar's atony suture for postpartum uterine
hemorrhage
Authors: Acar Ali , Alan Cemre , Doğru Şükran
Published: November 2024

Objective This study aims to define a new compression suture technique
that is easy to apply and effective in stopping PPH immediately.

Study Design This is a retrospective study of 22 women who received
Acar's uterine compressive atony sutures at a single tertiary hospital
between January 2021 and November 2023. Demographic and obstetric data were
collected. Outcomes included units of blood transfused, intraoperative and
postoperative adverse events, duration of hospital admission, and hysterectomy
rate.

Results The new suture technique was successful in all cases. Acar's
atony suture effectively stopped PPH due to uterine atony. None of the patients
needed a hysterectomy. Ten (45.5%) patients received blood product transfusions.
Only two of the patients (9%), both of whom had given birth in an external
center and in whom the suture was applied afterwards, needed a a stay in the
postoperative intensive care unit. The mean hospital stay was 4±1 days.

Conclusions Acar's atony suture is a practical, feasible, and
uterine-sparing technique for PPH due to uterine atony.
Murdered and missing: description, art, and human rights
Authors: Islas Weinstein Tania , Garnsey Eliza
Published: November 2024

The aim of the article is to explore how describing works of art and artistic practices enables a deeper understanding of the political dimensions and effects of art. Drawing on visual and documentary analysis, the article explores two artworks: Azúcar Rabiosa (‘Rabid Sugar’) (2018) by Cerrucha which addresses the justice system’s inaction regarding femicides and transfemicides in Mexico and Remain (2018) by Hoda Afshar, which documents the experiences of a group of stateless men who were left to languish when the Australian government closed its offshore immigration detention centre. Two key arguments emerge. First, making visible through description different aspects of artistic objects and practices helps account for what these artworks do politically. Second, taking description seriously enables us to understand how these artworks make claims to human rights.
Textbooks, hunger, and humanitarian narratives: representations of U.S. food policies to Germany on a regional scale (1949–89)
Authors: van Mourik Anne
Published: November 2024

This article investigates the significance of United States (U.S.) post-WWII food aid to Germany in West German textbooks from a regional angle during the Cold War period. Previous studies have predominantly focused on interpreting the significance of U.S. aid in West Germany from a national standpoint, overlooking regional variations in humanitarian narratives. This study challenges the national scale as the exclusive basis of collective meaning. By exploring educational materials from three different German regions—Berlin, Bavaria and North Rhine-Westphalia, it examines the different afterlives of U.S. aid in West German humanitarian narratives. Further attention for nuances in reconstructing humanitarian narratives not only does justice to the distinct regional histories and memory cultures, but also gives scope to reassessments of dominant narratives.
Verification of electromagnetic simulation capabilities in global gyrokinetic particle-in-cell code GTS
Authors: Startsev Edward A. , Wang Weixing , Yoo Min-Gu , Chen Jin , Ethier Stephane
Published: November 2024

Recently, the numerical scheme presented by Mishchenko et al. [Phys. Plasmas 21, 052113 (2014); 21, 092110 (2014)] enabled explicit gyrokinetic simulations of low-frequency electromagnetic instabilities in tokamaks at experimentally relevant values of plasma β. This scheme resolved the long-standing cancellation problem that previously hindered gyrokinetic particle-in-cell code simulations of magnetohydrodynamic phenomena with inherently small parallel electric fields. Moreover, the scheme did not employ approximations that eliminate critical tearing-type instabilities. Here, we report on the implementation of this numerical scheme in the global gyrokinetic particle-in-cell code GTS. This implementation allows for a more complete and accurate picture of interaction between small scale turbulence and MHD modes in tokamaks. Additionally, we present a comprehensive set of verification simulations of numerous electromagnetic instabilities relevant to present-day tokamaks. These simulations encompass the kinetic ballooning mode, the internal kink mode, the tearing mode, the micro-tearing mode, and the toroidal Alfven eigenmode destabilized by energetic ions, which are all instrumental in understanding tokamak physics. We will also showcase the preliminary nonlinear simulations of kinetic ballooning instabilities and (2,1) island formation due to tearing mode instability. These simulations validate the accuracy of the scheme implementation and pave the way for studying how these instabilities affect plasma confinement and performance.
Design studies on electronics and data acquisition of a real time diamond spectrometer for the SPARC neutron camera
Authors: Petruzzo M. , Celora A. , Croci G. , Gallo E. , Gorini G. , Grosso G. , Nocente M. , Parisi M. , Putignano O. , Raj P. , Rigamonti D. , Rebai M. , Reinke M. , Scioscioli F. , Tardocchi M. , Tedoldi L.
Published: November 2024

The design of a compact 2 × 2 diamond matrix with independent and redundant pixels optimized for the spectrometric neutron camera of the SPARC tokamak is presented in this article. Such a matrix overcomes the constraints in dynamic range posed by the size of a single diamond sensor while keeping the ability to perform energy spectral analysis, marking a significant advancement in tokamak neutron diagnostics. A charge pre-amplifier based on radio frequency amplifiers based on InGaP technology transistors, offering up to 2 GHz bandwidth with high robustness against radiation, has been developed. A first single-channel device has been tested and proven to provide a fast signal development time of 20–25 ns, necessary to mitigate pileup effects while offering precise energy measurements. As the diamond sensors may suffer from polarization effects due to the trapping of charges at the diamond/metal interface, a periodical bias inversion can guarantee optimal performance. To facilitate that, a reversible high voltage power supply has been developed. The ongoing development of data acquisition equipment and real-time processing algorithms based on programmable gate arrays further enhances the neutron camera’s capabilities.
Analytical model of small- and large-amplitude drop oscillation dynamics
Authors: Tonini S. , Cossali G. E.
Published: November 2024

The mechanical energy balance over a bulk of fluid that oscillates between prolate and oblate shapes in another immiscible fluid is solved using a general spheroidal coordinate system. The drop shape is described by a unique parameter that may continuously vary over the time, making the implementation of the model rather simple. Potential flow is assumed, and inertial and viscous effects are accounted for in both the inner and outer flow fields. The characteristics of drop oscillation for small and large amplitudes are studied, and the results are compared with theoretical, experimental, and numerical data from the open literature. The rather satisfactory validation of the model over a large variety of operating conditions allows its extension to include other physical phenomenon, like evaporation and its effect on drop oscillation.
Probing shocks interacting with radiation waves with the Radishock experiment
Authors: Coffing Shane X. , Wood Suzannah R. , Byvank T. , Robey Harry F. , Doss Forrest W. , Fryer Chris L. , Johns Heather M. , Kozlowski Pawel M. , Fontes Christopher J. , Meyerhofer D. D. , Urbatsch Todd J.
Published: November 2024

Both radiation flows and shocks have been extensively studied in the laboratory in the past few decades due to their critical roles in many astrophysical and high-energy density physics processes. In the Radishock experiment, a halfraum-powered radiation wave is driven into a low-density foam and interacts with an ablatively driven, counter-propagating shock. The interacting waves produce a spike in energy density with a temperature greater than the local temperature of the individual waves. As in the successful predecessor experiment, COAX, the primary diagnostic uses absorption spectroscopy at many locations down the cylindrical target, enabling a spatial temperature inference of the radiation wave and its interactions with the shock. Combined with a radiography diagnostic that is capable of imaging the shock and interaction features, we are able to study and inform model predictions of the interaction spike phenomenon. We describe the underlying physics behind the shock interactions with the radiation front and the implications of this experimental study for a broad range of astrophysical phenomena.
Flow of ferrofluid within a channel driven by a rotating magnetic field: Implications of surface magnetic stresses and magnetic body couples
Authors: Contreras-Mateus M. Daniela , Ariza-León Emiliano , Chaves-Guerrero Arlex
Published: November 2024

This research presents a discussion of the flow of a ferrofluid in a square cross-sectional area channel driven by a rotating magnetic field. The objective was to evaluate the coupled effect of surface magnetic stresses and diffusion of the internal angular momentum as potential mechanisms for generating flow. In many analyses of flow induced by time-dependent magnetic fields, the effect of the diffusion of the internal angular momentum has been dismissed, based on the negligible value of the spin viscosity coefficient estimated from order-of-magnitude analyses. In light of these considerations, we conducted a review of the existing analyses and put forward a new approach of the order-of-magnitude analysis of the spin viscosity coefficient. The paper presents a detailed description of the solution procedure for the flow field, with and without the inclusion of the diffusion of the internal angular momentum. To justify the assumptions involved in the analytical solution of the flow, we expanded a previous scale analysis to define Reynolds and Strouhal numbers in the linear and internal angular momentum balance equations. It was proven that the maximum surface velocity predicted at the ferrofluid–air boundary closely aligns with the reported experimental data for moderate amplitudes of the magnetic field.
Selecting relevant structural features for glassy dynamics by information imbalance
Authors: Sharma Anand , Liu Chen , Ozawa Misaki
Published: November 2024

We numerically investigate the identification of relevant structural features that contribute to the dynamical heterogeneity in a model glass-forming liquid. By employing the recently proposed information imbalance technique, we select these features from a range of physically motivated descriptors. This selection process is performed in a supervised manner (using both dynamical and structural data) and an unsupervised manner (using only structural data). We then apply the selected features to predict future dynamics using a machine learning technique. One of the advantages of the information imbalance technique is that it does not assume any model a priori, i.e., it is a non-parametric method. Finally, we discuss the potential applications of this approach in identifying the dominant mechanisms governing the glassy slow dynamics.
Numerical simulation of the coupled thermal-hydro-mechanical fields for evaluating CO2 geo-sequestration storage in deep saline aquifers of Hainan Fushan Sag, China
Authors: Ye Zhenni , Shi Mu , Lin Yi , Long Qijian , Zhao Yamin , Sun Huan
Published: November 2024

Geo-sequestration storage of CO2 in saline aquifers is an important technological option to reduce carbon emissions in China in the future. The theory of geo-sequestration storage of CO2 in saline aquifers involves complex physical operations and chemical phenomena among reservoir stress, seepage, and temperature fields, and the numerical simulation models coupling thermal-hydro-mechanical (THM) fields are widely applied to analyze the evolution of multiphysical processes in CO2 reservoirs. Based on the geo-sequestration storage project of saline aquifer CO2 in Fushan Sag, Hainan Province, under the premise of considering the change of permeability and porosity after the mineralization of CO2 in the rock reservoirs, this study simulates the evolution of temperature, stress, and seepage fields during the sequestration process of saline aquifer Continuous CO2 injection wells clarifies the range of influence of the temperature field, seepage field, and the boundary of its stress field of saline aquifer Continuous CO2 injection wells in different sequestration periods. It reveals the influence mechanism of the fault structure on the reservoir CO2 sequestration pressure and capacity, and evaluates and estimates the CO2 injection storage capacity of Fu 1# well in Fushan Sag and on this basis. The THM numerical simulation model proposed in this study plays a crucial role in guiding theoretical evaluations of the CO2 geo-sequestration potential in saline aquifers and determining its technical parameters, thereby offering significant value for engineering applications.
Influence of a dynamic gas film on underwater drag reduction
Authors: Liang Jiahui , Wang Bao , Wang Caihua , Yan Dayun , Sun Na
Published: November 2024

The gas film at the liquid–solid interface, induced by hydrophobic microstructure, can achieve a high-efficiency underwater drag reduction. However, previous studies have rarely considered the impact of changes in gas structure morphology on drag performance, especially under turbulent conditions. We conducted numerical simulations to examine the dynamic process of gas on a hydrophobic spanwise grooved surface under turbulent conditions. Our findings indicate that the morphology of the gas phase structure at the liquid–solid interface undergoes continuous alterations due to fluid action, resulting in a dynamic state of drag performance. In addition, the gas morphology that completely covers the groove surface will reduce the turbulent kinetic energy on the groove surface, resulting in a better drag reduction effect. In the flow velocity range of 10–20 m/s, the drag reduction effect of the superhydrophobic grooved surface increases with the flow velocity. Finally, we conducted experiments to validate the effectiveness of this result. A mechanism for underwater drag reduction was proposed based on these simulation results. This study offers a novel perspective on the phenomenon of underwater gas drag reduction, which could significantly influence its practical applications, especially under real working conditions.
Propagation gap for shear waves in binary liquids: Analytical and simulation study
Authors: Bryk Taras , Kopcha Maria , Yidak Ihor
Published: November 2024

Transverse collective excitations in 50-50 and 80-20 Lennard-Jones binary liquid mixtures are studied for different mass ratio of components R at fixed numerical densities. Increasing the mass ratio results in a growing difference between frequencies of shear waves and transverse optic modes. We report an increase in the propagation gap width for shear waves with mass ratio of components and compare it to the gap width expression, known from the transverse dynamics of simple liquids. A four-variable dynamic model of transverse dynamics in binary liquids with an account of cross correlations between total-mass and mass-concentration transverse current fluctuations is solved analytically in the long-wavelength region. An equation for the propagation gap of shear waves for binary liquids is reported and analyzed.
On the transition between two-phase and single-phase interface dynamics in ammonia sprays
Authors: Guida Paolo , Roberts William L.
Published: November 2024

This study explores the application of the density gradient theory to assess the validity of the two-phase spray atomization theory in multi-component ammonia sprays under conditions relevant to practical applications. The research focuses on analyzing the liquid–vapor interface structure at thermodynamic equilibrium. The most recent Helmholtz energy equation of state was employed to compute density profiles for ammonia and the surrounding nitrogen gas. The study investigates species distribution at equilibrium by examining minimal Helmholtz free energy states and evaluates critical parameters, such as interface thickness. The Knudsen number was also calculated as a temperature function to characterize the spray regime. The findings indicate that when the reduced temperature exceeds 0.95, a diffuse interface forms in ammonia-nitrogen systems, supporting using phase-field models for simulating ammonia injection in practical scenarios.
The propulsive effect of thermal waves
Authors: Hossain M. Z. , Floryan J. M.
Published: November 2024

The use of thermal waves as a potential propulsion method has been investigated. The test flow system involves two horizontal parallel plates, one fixed and exposed to thermal waves and the other allowed to move. The propulsive effect is quantified using the velocity of this plate. It is shown that, in general, the plate moves opposite to the wave direction, but its characteristics depend on whether the waves have subcritical or supercritical amplitudes. In the case of subcritical amplitudes, the plate velocity varies proportionally to the square of the wave amplitude, and its most effective wavelength corresponds to the wave number α≈2. In the case of supercritical amplitudes, the system response is affected by nonlinear thermal streaming, which produces faster plate movement. The plate velocity variations as a function of the wave velocity exhibit hysteresis with respect to changing wave direction; multiple solutions are possible for nominally identical flow conditions, with some of the solution branches terminating at limit points.
Characterizing a device for easy simulation of compression waves induced by trains passing through tunnels
Authors: Liu Feng , Wei Mengjie , Yang Haibo , Song Xiaoyu , Lan Yuan , Chen Dawei , Wang Kaiwen
Published: November 2024

When a high-speed train enters a tunnel, an initial compression wave (ICW) is generated, which radiates out as it propagates lengthways through the tunnel to the exit, forming an uncomfortable micro-pressure wave (MPW). The aim of this research is to develop a scaled device to quickly simulate this aerodynamic phenomenon. Our device achieves this by using the instantaneous release of high-pressure air in the chamber. In the first part of the paper, the reliability of this device is verified by various methods, including an airtightness check, calibration of transducers, and repeatability experiments. Next, the mapping of the parameters of the device to engineering values is discussed. The propagation process of the ICW and the pressure fluctuations in the tunnel are then analyzed, and the discussion centers around a control variable case. Finally, the MPW generated near the tunnel exit is explored and acoustically evaluated. It is found that the initial pressure in the chamber, the opening voltage, and the number of solenoid valves in the experiment can be mapped to the train speed, the characteristic length of train nose, and the blockage ratio, respectively. When the pressure amplitude of the ICW is higher, there will be a certain steepening phenomenon in the propagation process. The pressure fluctuation cycle in the tunnel is calculated as 4× tunnel length/wave velocity, and the amplitude of fluctuation decays exponentially over the cycles. In most cases, the sound pressure level of MPWs near the tunnel exit exceeds the hearing threshold, based on the auditory properties of the human ear.
A data-free Kolmogorov–Arnold Network-based method for structured mesh generation
Authors: Peng Jiaming , Chen Xinhai , Zhang Qingyang , Deng Liang , Shen Liming , Liu Jie
Published: November 2024

Mesh generation is a critical but time-consuming process for stable and accurate numerical simulations. Although multi-layer perceptron-based meshing methods can be effective, they suffer from slow training convergence and heavy reliance on prior datasets. To overcome these problems, we propose the Kolmogorov–Arnold Network-based meshing network, an efficient data-free method for structured mesh generation. The proposed method takes the meshing task as an optimization problem and embeds meshing-related differential equations into the loss function of Kolmogorov–Arnold Networks. It employs two parts to generate meshes efficiently. The Kolmogorov–Arnold Network part introduces learnable activation functions on the edges of the network, which enables the network to learn meshing rules between parametric and computational domains. The physics-informed learning part provides meshing-related information to guide the network training. Finally, the proposed method can produce high-quality structured meshes with a user-defined number of quadrilateral or hexahedral cells through feed-forward prediction. Experiments on different geometries show that the proposed method achieves up to three orders of magnitude improvement in meshing efficiency compared to traditional methods. It also outperforms state-of-the-art multi-layer perceptron-based methods, yielding high-quality meshes in both two-dimensional and three-dimensional cases without prepared data.
Properties of a trapped multiple-species bosonic mixture at the infinite-particle-number limit: A solvable model
Authors: Alon O. E. , Cederbaum L. S.
Published: November 2024

We investigate a trapped mixture of Bose–Einstein condensates consisting of a multiple number of P species. To be able to do so, an exactly solvable many-body model is called into play. This is the P-species harmonic-interaction model. After presenting the Hamiltonian, the ground-state energy and wavefunction are explicitly calculated. All properties of the mixture’s ground state can, in principle, be obtained from the many-particle wavefunction. A scheme to integrate the all-particle density matrix is derived and implemented, leading to closed-form expressions for the reduced one-particle density matrices. Of particular interest is the infinite-particle-number limit, which is obtained when the numbers of bosons are taken to infinity while keeping the interaction parameters fixed. We first prove that at the infinite-particle-number limit all the species are 100% condensed. The mean-field solution of the P-species mixture is also obtained analytically and is used to show that the energy per particle and densities per particle computed at the many-body level of theory boil down to their mean-field counterparts. Despite these, correlations in the mixture exist at the infinite-particle-number limit. To this end, we obtain closed-form expressions for the correlation energy, namely, the difference between the mean-field and many-body energies, and the depletion of the species, i.e., the number of particles residing outside the condensed modes, at the infinite-particle-number limit. The depletion and the correlation energy per species are shown to critically depend on the number of species. Of separate interest is the entanglement between one species of bosons and the other P − 1 species. This quantity is governed by the coupling of the center-of-mass coordinates of the species and is obtained by the respective Schmidt decomposition of the P-species wavefunction. Interestingly, there is an optimal number of species, here P = 3, where the entanglement is maximal. Importantly, the manifestation of this interspecies entanglement in an observable is possible. It is the position–momentum uncertainty product of one species in the presence of the other P − 1 species, which is derived and demonstrated to correlate with the interspecies entanglement. All in all, we show and explain how correlations at the infinite-particle-number limit of a trapped multiple-species bosonic mixture depend on the interactions and how they evolve with the number of species. Generalizations and implications are briefly discussed.
Baseline assessment of microplastics and biochemical response of Anadara antiquata as a sentinel species for biomonitoring in Fiji
Authors: Varea Rufino , Dehm Jasha , Mani Francis
Published: November 2024

Context Microplastics are a concern for maritime nations such as Fiji, which rely heavily on seafood, such as bivalves, which can transfer pollutants through the food chain. The lack of biomonitoring studies in the Pacific region highlights the necessity of researching microplastic pollution in seafood. Aims This study quantifies microplastics in Anadara antiquata, a commonly consumed shellfish in Fiji, and evaluates its general biochemical responses. As a baseline, this study is not to draw an association between the two endpoints (microplastics and biochemical responses), rather present these as baselines for future studies. Methods A total of 58 specimens from Ba River Delta, Rakiraki Bay and Vueti Navakavu were examined, where differences in potential sources or pathways for microplastics, including anthropogenic pollutants with the potential to induce stress on marine animals, were considered (rivers, industrial zones, stormwater outlets, sewerage outfalls and mining area). Specific hepatopancreatic enzyme activities associated with detoxification (glutathione-S transferase, GST) and oxidative stress (glutathione peroxidase, GPX, and glutathione reductase, GR) were measured. Key results Microplastics were extracted, classified by morphology and quantified. The study found that 64% of specimens had microplastics, <1.0 mm being more prevalent. Ba River Delta showed significant biochemical stress (Kruskal–Wallis test; P < 0.05) with GST (χ2 = 40.28, d.f. = 2, P-value < 0.001), GPX (χ2 = 38.38, d.f. = 2, P-value < 0.001) and GR χ2 = 45.14, d.f. = 2, P-value < 0.001) being considered as likely to be responding to pollution. Conclusion As a baseline, the study underlines the need for biomonitoring as a result of varying and concerning levels of pollution and biochemical stress responses found across the study areas. Integrating biomonitoring methods into risk-assessment protocols in Fiji may support establishment of opportunities or considerations for health guidelines and policy interventions to minimise human exposure to microplastics, and regulate environmental pollution. Implications These measures are crucial for protecting public health and monitoring pollution impacts.
Targeted degradation of Pin1 by protein-destabilizing compounds
Authors: Alboreggia Giulia , Udompholkul Parima , Rodriguez Isaac , Blaha Gregor , Pellecchia Maurizio
Published: November 2024

The concept of targeted protein degradation is at the forefront of modern drug discovery, which aims to eliminate disease-causing proteins using specific molecules. In this paper, we explored the idea to design protein degraders based on the section of ligands that cause protein destabilization, hence that facilitate the cellular breakdown of the target. Our studies present covalent agents targeting Pin1, a cis–trans prolyl isomerase that plays a crucial role in tumorigenesis. Our design strategy entailed iterative optimizations of agents for potency and Pin1 destabilization in vitro. Biophysical and cellular studies suggest that the agents may act like
molecular crowbars
, displacing protein-stabilizing interactions that open the structure for recognition by the proteasome degradation machinery. This approach resulted in a series of potent and effective Pin1 degraders with potential applications in target validation and in therapeutic development. We propose that our design strategy can identify molecular degraders without engineering bifunctional agents that artificially create interactions between a disease-causing protein and a ubiquitin ligase.
Origins of synergy in multilipid lubrication
Authors: Cao Yifeng , Jin Di , Kampf Nir , Klein Jacob
Published: November 2024

Lipid bilayers, ubiquitous in living systems, form lubricious boundary layers in aqueous media, with broad relevance for biolubrication, especially in mechanically stressed environments such as articular cartilage in joints, as well as for modifying material interfacial properties. Model studies have revealed efficient lubricity by single-component lipid bilayers; synovial joints, however (e.g. hips and knees), comprise over a hundred different lipids, raising the question of whether this is natural redundancy or whether it confers any lubrication benefits. Here, we examine lubrication by progressively more complex mixtures of lipids representative of those in joints, using a surface forces balance at physiologically relevant salt concentrations and pressures. We find that different combinations of such lipids differ very significantly in the robustness of the bilayers to hemifusion under physiological loads (when lubrication breaks down), indicating a clear lubrication synergy afforded by multiple lipid types in the bilayers. Insight into the origins of this synergy is provided by detailed molecular dynamics simulations of potential profiles for the formation of stalks, the essential precursors of hemifusion, between bilayers of the different lipid mixtures used in the experiments. These reveal how bilayer hemifusion—and thus lubrication breakdown—depends on the detailed lipid bilayer composition, through the corresponding separation into domains that are better able to resist stalk formation. Our results shed light on the role of lipid-type proliferation in biolubrication synergy, point to improved treatment modalities for common joint diseases such as osteoarthritis, and indicate how lipid-based interfacial modification in a materials context may be optimized.
Hierarchical behavior control by a single class of interneurons
Authors: Huo Jing , Xu Tianqi , Liu Qi , Polat Mahiber , Kumar Sandeep , Zhang Xiaoqian , Leifer Andrew M. , Wen Quan
Published: November 2024

Animal behavior is organized into nested temporal patterns that span multiple timescales. This behavior hierarchy is believed to arise from a hierarchical neural architecture: Neurons near the top of the hierarchy are involved in planning, selecting, initiating, and maintaining motor programs, whereas those near the bottom of the hierarchy act in concert to produce fine spatiotemporal motor activity. In
Caenorhabditis elegans
, behavior on a long timescale emerges from ordered and flexible transitions between different behavioral states, such as forward, reversal, and turn. On a short timescale, different parts of the animal body coordinate fast rhythmic bending sequences to produce directional movements. Here, we show that Sublateral Anterior A (SAA), a class of interneurons that enable cross-communication between dorsal and ventral head motor neurons, play a dual role in shaping behavioral dynamics on different timescales. On a short timescale, SAA regulate and stabilize rhythmic bending activity during forward movements. On a long timescale, the same neurons suppress spontaneous reversals and facilitate reversal termination by inhibiting Ring Interneuron M (RIM), an integrating neuron that helps maintain a behavioral state. These results suggest that feedback from a lower-level cell assembly to a higher-level command center is essential for bridging behavioral dynamics at different levels.