bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Celebrity Endorsement on Customer with Reference to Mobile
Authors: Gaikwad Smita , Muley Anand
Published: July 2024

This paper analyze, impact of celebrity endorsement of products (Mobile) is the collaborating multichannel promotion of products or services This marketing provides customers time and location conscious of personalized information that promotes goods, services and ideas. On other side of the debate, proponents argue that celebrity endorsements play a vital role in enhancing brand visibility and consumer recall. They contend that aligning a brand with a well-known personality can effectively capture consumer attention in a competitive Advertising landscape. Additionally, celebrities are believed to lend credibility to a brand and establish emotional connections with consumers, influencing their purchasing decisions positively. Therefore, while celebrity endorsements can be a powerful tool for brand building and marketing, their success hinges on various factors such as the relevance of the celebrity to the brand, consumer perception, and the overall marketing strategy. The debate regarding the positive or negative impact of celebrity endorsements on brands underscores the complexity of this marketing approach and the need for careful consideration and strategic alignment to maximize its effectiveness.
Technostress: A Critical Assessment of Its Negative Aspects and Strategies for Coping
Authors: Thakur Pankaj , Kumari Santosh
Published: July 2024

The information and technological changes have increased the flow of information, and it has crossed space and time limits. Radical changes in ICT have accelerated the rhythm of life and work. The rhythmic acceleration can be felt in the professional as well as personal life. Information and communication technology is widely used in today’s work culture and it is contributing to the newly growing problem known as technostress. Technostress cannot be avoided as most organizations across the globe are using digital technology. Continuous digitization significantly affects the work and workers in organizations. It has both negative as well as positive consequences but negative consequences are more as per the different studies. Numerous empirical studies have been conducted on technostress but among them, few have comprehensive reviews, which have led to fragmented information about the technostress. The main objective of this study is to review the negative implications of technostress and how to cope with them. We gathered data from published articles available in different databases. The integrative research design has been used to carry out the research. Based on the results available from different studies, we have conceptualized this study and it will help individuals and managers to be aware of technostress impacts. Organizations can manage well in time the unwanted risks that technostress brings into them. In this review article, we have shown the negative impacts of technostress and strains arising as a result of technostress along with the coping mechanism that helps to mitigate the negative outcomes of technostress.
Les techniques de base en physiothérapie pour le praticien généraliste
Authors: Tiberghien Hélène
Published: July 2024

Les techniques de base en physiothérapie requérant peu de matériel sont la thermothérapie, les massages, la kinésithérapie passive et active, l’électrothérapie et la cryothérapie.

Ces techniques sont simples de réalisation et sont à la portée de tout vétérinaire généraliste, sous réserve de connaissance des indications et contre-indications.

Ces techniques sont conseillées sur de nombreuses affections telles que l’arthrose, le post opératoire orthopédique, les tendinites et les spasmes musculaires.

La réalisation peut être faite lors d’une consultation en clinique vétérinaire ou conseillées à domicile au propriétaire, quotidiennement ou plusieurs fois par semaine.

Elles améliorent grandement le confort et la qualité de vie de l’animal.
Traumatismes des voies urinaires :
techniques radiographiques avec produit de contraste
Authors: Manassero Mathieu , Maquet Delphine
Published: July 2024

Les traumatismes des voies urinaires sont des affections graves nécessitant une prise en charge spécifique. Malgré l’avènement de l’échographie, les examens radiographiques avec produit de contraste restent des techniques de choix pour confirmer la rupture, déterminer sa localisation précise et la démarche thérapeutique à appliquer.

Les examens radiographiques avec produit de contraste sont des techniques simples mais qui nécessitent une démarche codifiée, chaque examen répondant à une suspicion clinique précise.

Le produit de contraste de choix lors de suspicion de brèche de l’appareil urinaire est un produit de contraste iodé non ionique et hydrosoluble qui doit être réchauffé à 38° C.

La cystographie (injection rétrograde de 5 à 10 ml/kg de produit de contraste à 150 à 200 mgIode/ml) est indiquée lors de suspicion de brèche vésicale.

L’urétrographie rétrograde (chez le mâle) et la vaginourétrographie (chez la femelle) sont indiquées lors de suspicion de brèche urétrale. Le volume du produit de contraste (150 à 200 mg Iode/ml) à injecter correspond chez le mâle à la dose de 10 à 20 ml par animal chez le chien et à la dose de 3 à 10 ml par animal chez le chat ; et chez la femelle, à la dose de 30 à 90 ml par animal chez la chienne et à 10 à 20 ml par animal chez la chatte.

En pratique, le volume d’injection suffisant est atteint lorsqu’une légère résistance est ressentie sur le piston.

L’urographie intraveineuse (UIV) et la pyélographie permettent de mettre en évidence les ruptures pyéliques et ou urétérales. La pyélographie antérograde percutanée permet un marquage plus sélectif, donc de meilleure qualité que l’UIV. Elle nécessite cependant plus de technicité et est à réserver aux cas pour lesquels il existe une latéralisation de la lésion et pour lesquels une dilatation pyélique ipsilatérale supérieur à 4 mm est présente. L’UIV reste une technique plus simple à mettre en place et ne nécessitant pas d’échographie concomittante.

Quel que soit l’examen réalisé, les complications sont rares, mais une fluidothérapie post marquage est préconisée.
Dossier : « La recherche au défi de la crise des temporalités » : Mauvais temps sur la métropole grenobloise ? Pour une analyse transdisciplinaire de la relation aléas hydroclimatiques/tempo sociétal/timing organisationnel
Authors: Renou Yvan , Brochet Antoine , Creutin Jean-Dominique , Cartier Stéphane , Kharbouche Mohammed , Blanchet Juliette
Published: July 2024

Déployant une méthodologie originale, cet article étudie la nature du couplage entre l’évolution climatique à l’échelle métropolitaine et les stratégies d’adaptation socioéconomique mises en œuvre pour y faire face. L’analyse située du système métropolitain grenoblois illustre notamment comment le rythme de l’organisation collective peine à suivre l’évolution climatique locale. Ce « climat de mauvais temps » trace, via la notion de régime de risque d’inondation, la fréquence des extrêmes hydroclimatiques, le rythme d’adaptation des territoires et les modalités concrètes d’organisation collective. Pour affronter ces enjeux temporels, il semble urgent qu’émergent des coalitions transdisciplinaires localisées. Structurées scientifiquement et politiquement, ces dernières sont appelées à coproduire une information climatique robuste et pertinente et à imaginer des stratégies soutenables pour le territoire. Afin de consolider analytiquement cette dynamique, nous invitons à un approfondissement de l’enjeu temporel au sein de la perspective des communs.
Synthesis of Difluoromethyl Chromono[3,2-c]pyrazolines/pyrazoles by [3+2] Cycloaddition Reaction of Difluoroacetohydrazonoyl Bromides with 3-EWG-Chromones
Authors: Wang Ke-Hu , Hu Yulai , Liang Xiuwen , Luo Wenjing , Chen Maizhuo , Wang Junjiao , Huang Danfeng
Published: July 2024

A highly convenient and straightforward strategy for the synthesis of difluoromethyl substituted tricyclic fused chromono[3,2-c]pyrazolines/pyrazoles is developed via [3+2]-cycloaddition of difluoroacetohydrazonoyl bromides to chromene derivatives bearing an electron-withdrawing group at the 3-position. The reaction has the advantages of mild conditions, good tolerance of functional groups, and simple operation.
Generalized solutions to the model of compressible viscous fluids coupled with the Poisson equation
Authors: Tan Zhong , Yang Hui
Published: July 2024

This paper deals with the model of compressible viscous and barotropic fluids coupled with the Poisson equation in a bounded domain Ω⊂R3 with C2+α (0 < α < 1) boundary ∂Ω. We prove the existence and weak-strong uniqueness of dissipative solutions when the adiabatic exponent γ > 1. We find that the Poisson term ρ∇Φ is not integrable when γ∈(1,32). We will make full use of the Poisson equation and energy inequality to overcome this difficulty. Finally, we obtain that ρ∇Φ leads to the decrease of Reynolds stress R and the increase of the energy dissipation defect E.
Rapid detection of incipient foil failure and remediation for longevity in repetitively pulsed, electron-beam-pumped excimer lasers for fusion research
Authors: Myers M. C. , Giuliani J. L. , Wolford M. F. , Hegeler F. , Robson A. E. , Sethian J. D.
Published: July 2024

The use of an electron beam to pump an excimer laser has the advantage of being readily scalable to higher laser energies at high efficiency. Typically, a pulsed power driver generates the electron beam in a vacuum diode that consists of an electron emitter and a thin anode foil that holds the vacuum against the atmospheric-pressure laser gas. Even a miniscule leak in the anode foil can lead to an electrical breakdown in the vacuum diode, resulting in the destruction of the foil and evidence of the failure mechanism. The problem is even more onerous at the high voltage, high current, and pulse repetition frequencies needed for the large-area diodes used in excimer lasers for fusion research. Electra is one such laser used at the Naval Research Laboratory to develop excimer laser technologies for inertial fusion energy. To achieve longevity on Electra, it was necessary to instantly detect an incipient foil failure and halt the pulsed power drivers so the physical cause(s) could be studied. This rapid detection was accomplished using an optically filtered photodiode that senses the presence of argon emission from a Penning discharge vessel attached to the vacuum diodes. Details of this “Spectral Penning Leak Detector” device and its operation are presented. The diagnostics allowed the identification of a recurrent pinhole leak in the anode foil induced by cathode spots, which were created by electron emission from the foil during post-pulse voltage reversals. Eliminating the voltage reversals increased the continuous operation of the Electra laser from hundreds of shots to over 90 000 shots.
Minimum dimensionless pressure technique for the indirect measurement of contact angles on super-hydrophobic surfaces
Authors: Escobar Juan Valentin
Published: July 2024

Measuring contact angles (CAs) on super-hydrophobic surfaces (CA ≥150°) can be challenging using traditional methods. In this work, we develop an alternative technique to measure CAs indirectly by measuring the minimum of the dimensionless hydrostatic pressure of a droplet as it de-wets a surface. This technique does not require measuring the slope of the profile close to the three-phase contact line and is devoid of any external pressure or force gauges. An experimental proof of principle is presented. Our results suggest that this technique may become a viable alternative for measuring the CA on super-hydrophobic and liquid repellent surfaces with relatively low uncertainty.
Numerical simulation of spinodal dewetting using single-component multiphase pseudopotential lattice Boltzmann method at high density ratio
Authors: Manga Ramya Durga , Sarkar Jayati
Published: July 2024

Spinodal dewetting is the spontaneous rupture and dewetting of thin liquid film (thickness less than 100 nm) on a solid substrate due to the attractive intermolecular forces between the interfaces of the liquid-bounding fluid and the liquid bounded solid substrate. Most of the reported numerical studies are performed by simplification of the Navier–Stokes (NS) equations using lubrication approximation. The lubrication approximation, however, is not valid for all the types of liquid thin films. For example, in metallic films, contact angles are greater than 30o, and inertial forces are also significant. So, to understand thin film dewetting dynamics, there is a need to solve the NS equation without simplification. The present numerical study investigates the spinodal dewetting of thin liquid films under van der Waals force by indirectly solving NS equations using one of the mesoscopic approaches, the lattice Boltzmann method (LBM). The stability analysis is carried out using a single-component multiphase pseudopotential LBM with a multiple relaxation time collision operator at the density ratio of 98.48, in both 2D (two-dimension) and 3D (three-dimension). D2Q9 (D2 represents two-dimension and Q9 represents nine possible microscopic velocities in which a particle can move) and D3Q15 (D3 represents three-dimension and Q15 represents 15 possible microscopic velocities in which a particle can move) lattice models are used in 2D and 3D, respectively. In-house codes are developed using C language, and the 3D LBM codes have been parallelized using a message-passing interface. The reported dewetting stages, namely, the arrangement of fluctuations on a dominant wavelength, hole formation, and expansion, are successfully observed with the present numerical method in both the dimensions. The breakup of liquid threads between the holes into droplets due to Rayleigh instability has also been captured in 3D. In 2D, at the time of initial rupture of the film, the average dominant wavelength [λdom,rupavg] is calculated by DFT (discrete Fourier transform), and it was observed that λdom,rupavg was much greater than that predicted by linear stability analysis λdom,LSA, using lubrication approximation. This study reveals that this deviation can be contributed to the shear stresses present at the interface, high contact angles, and diffused interface.
Independently regulating the electric and magnetic properties of flaky FeSiAl powder based composites for high-performance microwave absorber
Authors: Hu Jinwen , Wu Zhengying , Huang Zhengsheng , Wu You , He Jiayi , Wang Yi , Ju Wenbo , Zhong Xichun , Liu Zhongwu
Published: July 2024

Flaky structures can effectively enhance the microwave absorbing properties of metallic magnetic particles, but the interaction between the electromagnetic waves and particles in different directions is not well understood. Here, the oriented FeSiAl/paraffin composites were prepared under a rotational magnetic field and made into co-axial rings for electromagnetic measurements. The FeSiAl flakes in the rings are oriented along different angles with respect to the electric and magnetic fields of the microwave. The effects of the angles on the electric and magnetic properties as well as the microwave absorbing properties of the composite are investigated. It is found that the electric and magnetic properties can be modified independently by adjusting the angles between the flakes and the electric field and between the flakes and the magnetic field, respectively. The underlying mechanisms can be understood using electromagnetic and micromagnetic simulations. The anisotropic permittivity originates from the induced electric field of the flaky particles, while the anisotropic permeability results from the effect of the demagnetization field. An optimal orientation structure can reduce the permittivity by suppressing the induced electric field while maintaining high permeability by reducing the demagnetization energy in the magnetization process, which is beneficial to the impedance matching of the composite. Thus, the orientation structure is extremely efficient in regulating the microwave absorption performance of the flaky particles. This work proposed a general strategy for microwave absorbers to modulate microwave absorption performances between high-frequency and low-frequency by simply operating the orientation structures of the flaky particles.
Electric conductivity at the detonation of trinitrotoluene charges with different structures, densities, and additives
Authors: Satonkina N. P. , Ershov A. P. , Medvedev D. A.
Published: July 2024

The paper presents results of the investigation of electric properties at the detonation of trinitrotoluene (TNT, trotyl, C7H5N3O6) charges with different preparation methods, structures, and densities, with the addition of glass microspheres and water. The detonation characteristics are compared with the literature data. We discuss the nature of the electric conductivity, the connection between the kinetics and conductivity, and the influence of inert additives. Most of the experimental data on the electric conductivity are presented for the first time.
Large eddy simulation of non-stationary highly turbulent hurricane boundary layer winds
Authors: Ma Tianqi , Sun Chao , Miller Paul
Published: July 2024

Recent extreme tropical cyclones have caused extensive damage to critical civil infrastructure globally. To better capture the unique hurricane wind characteristics, a large eddy simulation (LES) hurricane boundary layer (HBL) model is developed by considering the variation of meso-scale kinematic and thermodynamic conditions. An asymmetric model is adopted to obtain the gradient wind velocity using the National Hurricane Center data. The meso-scale thermal conditions are obtained by extracting the hourly air temperature and relative humidity profiles from the ERA5 reanalysis output. Measurements recorded at the Aransas County airport during Hurricane Harvey and at the City of Naples during Irma are used to validate the developed LES model. Research results show that the simulated 10-min average wind speed and direction are consistent with the observations. The developed model can well predict the high wind turbulence intensity, which is around 20 % in Hurricane Harvey and 26 % in Hurricane Irma. The 3-s gust wind speeds reach 62.4 m/s at 10-m elevation during Hurricane Harvey and 53.5 m/s at 15-m elevation during Hurricane Irma, close to the field observed data of 61.3 and 54.2 m/s, respectively. The simulated 3-s gust factors are close to the observation except at some moments with significant variations because of the poorly understood physical phenomena. The simulated wind spectrum in longitudinal and lateral directions agrees well with the observed results. In addition, the vertical profiles of averaged wind speed and inflow angle agree with dropsonde observations. The maximum supergradient wind speed height decreases as it approaches the hurricane center. In summary, the developed LES-based HBL model can capture the main characteristics of hurricane structure and turbulence characteristics and is applicable for modeling civil infrastructure exposed to hurricanes.
Three-dimensional large eddy simulation urban neighborhood model with updated building drag coefficient and universal multiscale Smagorinsky model
Authors: Shui Qingxiang , Gu Zhaolin , Wang Daguo
Published: July 2024

Various drag-porosity models for urban buildings have been developed to explain the changes caused by building layout on airflow and turbulence in urban neighborhoods. One-dimensional building drag-porosity models with different model coefficients have been widely used to study the airflow in urban neighborhoods. However, these models often rely on length scales to calculate the eddy viscosity and dissipation rate using K-theory, which also need to be adjusted for different urban configurations. This study aims to address this limitation by developing a building drag parameterization version of the three-dimensional large eddy simulation neighborhood model (LES building drag-porosity model). The proposed model incorporates an updated building drag coefficient and the universal multiscale Smagorinsky model, making it suitable for simulating airflows in idealized and real urban neighborhoods with compact mid-rise buildings. To evaluate the performance of the proposed model, building-resolving LES was conducted for idealized and real neighborhoods. The vertical profiles of the turbulent kinetic energy and vertical turbulent momentum flux obtained using proposed model are superior to those obtained using previous models.
Volumetric reconstruction of flow particles through light field particle image velocimetry and deep neural network
Authors: Zhu Xiaoyu , Fu Mengxi , Xu Chuanlong , Hossain Md. Moinul , Khoo Boo Cheong
Published: July 2024

Tomographic reconstruction of three-dimensional (3D) tracer particle distributions through light field particle image velocimetry (LF-PIV) faces challenges in low reconstruction resolution owing to the elongation effect and extensive computational cost incurred by the iterative process. To resolve these challenges, this study proposes a deep neural network-based volumetric reconstruction approach to alleviate the reconstruction elongation and enhance the reconstruction efficiency. A tailored deep learning model (namely, LF-DNN) incorporating residual neural network architecture and a novel hybrid loss function is established to reconstruct the particle distributions through LF images. The parallax information of the flow field decoded from the raw LF data is leveraged as the input features of the network model. Comparative studies between the proposed method and the traditional tomographic reconstruction algorithms (multiplicative algebraic reconstruction technique, MART and pre-recognition MART, PR-MART) are performed through synthetic datasets. Experiments on a cylinder wake flow are further conducted to validate the performance of the proposed LF-DNN. The results indicate that the LF-DNN outperforms MART and PR-MART in terms of the reconstruction quality, mitigation of elongation effect, and noise resilience. The LF-DNN also improves the reconstruction efficiency which is 9.6 and 7.1 times higher than the MART and PR-MART, respectively. The relative error of the cylinder wake flow achieved by the LF-DNN is 2% lower than the MART. It suggests that the LF-DNN can facilitate accurate volumetric particle reconstruction and hence the three-dimensional flow measurement by single camera-based LF-PIV.
An insight into the wake evolution of power-law flow past three tandem circular cylinders
Authors: Zhu Hongjun , Xie Yipu , Li Yingmei , Zhong Jiawen , Zhou Tongming
Published: July 2024

This paper reports the wake flow evolution of power-law flow past three tandem cylinders with identical diameter and spacing at a low incoming Reynolds number of Re = 80. The flow characteristics of power-law fluid with variable power-law index n are examined at spacing ratios of L/D = 3, 5, and 8 (where L is the spacing between the centers of two adjacent cylinders and D is the cylinder diameter). Three combined wake interference regimes are identified, including the overshoot-overshoot, overshoot-alternate reattachment, and alternate reattachment-quasi-co-shedding regimes, which are distinctly illustrated from the dynamic mode decomposition results. The quasi-co-shedding regime mainly occurs between the middle and downstream cylinders (denoted as C2 and C3, respectively) when L/D = 5 and L/D = 8. The switching of wake regime contributes to the sudden changes of hydrodynamic coefficients of the cylinders. Nevertheless, due to the shadowing effect, the drags of C2 and C3 remain to smaller than that of the upstream cylinder (denoted as C1).
Phonon screening and dissociation of excitons at finite temperatures from first principles
Authors: Alvertis Antonios M. , Haber Jonah B. , Li Zhenglu , Coveney Christopher J. N. , Louie Steven G. , Filip Marina R. , Neaton Jeffrey B.
Published: July 2024

The properties of excitons, or correlated electron–hole pairs, are of paramount importance to optoelectronic applications of materials. A central component of exciton physics is the electron–hole interaction, which is commonly treated as screened solely by electrons within a material. However, nuclear motion can screen this Coulomb interaction as well, with several recent studies developing model approaches for approximating the phonon screening of excitonic properties. While these model approaches tend to improve agreement with experiment, they rely on several approximations that restrict their applicability to a wide range of materials, and thus far they have neglected the effect of finite temperatures. Here, we develop a fully first-principles, parameter-free approach to compute the temperature-dependent effects of phonon screening within the ab initioGW-Bethe–Salpeter equation framework. We recover previously proposed models of phonon screening as well-defined limits of our general framework, and discuss their validity by comparing them against our first-principles results. We develop an efficient computational workflow and apply it to a diverse set of semiconductors, specifically AlN, CdS, GaN, MgO, andSrTiO3. We demonstrate under different physical scenarios how excitons may be screened by multiple polar optical or acoustic phonons, how their binding energies can exhibit strong temperature dependence, and the ultrafast timescales on which they dissociate into free electron–hole pairs.
Cytoplasmic stirring by active carpets
Authors: Chakrabarti Brato , Rachh Manas , Shvartsman Stanislav Y. , Shelley Michael J.
Published: July 2024

Large cells often rely on cytoplasmic flows for intracellular transport, maintaining homeostasis, and positioning cellular components. Understanding the mechanisms of these flows is essential for gaining insights into cell function, developmental processes, and evolutionary adaptability. Here, we focus on a class of self-organized cytoplasmic stirring mechanisms that result from fluid–structure interactions between cytoskeletal elements at the cell cortex. Drawing inspiration from streaming flows in late-stage fruit fly oocytes, we propose an analytically tractable active carpet theory. This model deciphers the origins and three-dimensional spatiotemporal organization of such flows. Through a combination of simulations and weakly nonlinear theory, we establish the pathway of the streaming flow to its global attractor: a cell-spanning vortical twister. Our study reveals the inherent symmetries of this emergent flow, its low-dimensional structure, and illustrates how complex fluid–structure interaction aligns with classical solutions in Stokes flow. This framework can be easily adapted to elucidate a broad spectrum of self-organized, cortex-driven intracellular flows.
Terminology, popularisation and ideology in contemporary China
Authors: Bertulessi Chiara
Published: July 2024

This paper explores the relationship between terminology, the popularisation of scientific and technical knowledge
and ideology in the People’s Republic of China. Specifically, it presents a study that focuses on an online daily column entitled
‘Scientific & Technical Term of the Day’ (每日科技名词),
a terminology popularisation project promoted by China’s contemporary political leadership and implemented through the digital
institutional platform Xuexi qiangguo 学习强国.

Drawing on the theoretical frameworks of critical discourse studies and legitimation in discourse, as well as
frame analysis and frame semantics, the paper presents an analysis of expository texts designed to complement the knowledge provided by
terminographic definitions of the terms published in the daily column. The focus is on the framing of China and the Party-state in
these texts, which, it is argued, can also be interpreted as legitimation strategies.
Integrating machine learning and the finite element method for assessing stiffness degradation in photovoltaic modules
Authors: Li Weiqing
Published: July 2024

This study introduces a novel machine learning (ML) method utilizing a stacked auto-encoder network to predict stiffness degradation in photovoltaic (PV) modules with pre-existing cracks. The input data for the training process was derived from numerical simulations, ensuring a comprehensive representation of module behavior under various conditions. The findings highlight the robust predictive capability of the model, as evidenced by its impressive R2 value of 0.961 and notably low root mean square error (RMSE) of 4.02%. These metrics significantly outperform those of other conventional methods, including the artificial neural network with R2 of 0.905 and RMSE of 9.43%, the space vector machine with R2 of 0.827 and RMSE of 17.93%, and the random forest (RF) with R2 of 0.899 and RMSE of 11.02%. Moreover, the findings suggest that the predictive dynamics of degradation are affected by the varying weight functions of different input parameters, such as climate temperature (CT), grain size (GS), material effort, and pre-crack size, as the degradation level changes. Furthermore, a geometric analysis reveals model deficiencies where significant overestimations correlate with thicker glass components, while pronounced underestimations are predominantly associated with thinner layers of polycrystalline silicon wafer and Ethylene Vinyl Acetate in the module. As a case study, it demonstrated that to maintain a constant degradation level between 1.30 and 1.32 in a PV module with components featuring consistent geometric attributes, the input parameters must be kept within specific ranges: CT ranging from 33 °C to 57 °C, GS ranging from 36 to 81 μm, material effort ranging from 0.74 to 0.81, and pre-crack size ranging from 24 to 32 μm. Therefore, this underscores that the ML model not only predicts degradation but also delineates the parameter space required to achieve a consistent output value.
Covalent surface modification of single-layer graphene-like BC6N nanosheets with reactive nitrenes for selective ammonia sensing via DFT modeling
Authors: Baachaoui Sabrine , Hajlaoui Rabiaa , Aoun Sami Ben , Fortunelli Alessandro , Sementa Luca , Raouafi Noureddine
Published: July 2024

Novel graphene-like nanomaterials with a non-zero bandgap are important for the design of gas sensors. The selectivity toward specific targets can be tuned by introducing appropriate functional groups on their surfaces. In this study, we use first-principles simulations, in the form of density functional theory (DFT), to investigate the covalent functionalization of a single-layer graphitized BC6N with azides to yield aziridine-functionalized adducts and explore their possible use to realize ammonia sensors. First, we determine the most favorable sites for physical adsorption and chemical reaction of methylnitrene, arising from the decomposition of methylazide, onto a BC6N monolayer. Then, we examine the thermodynamics of the [1 + 2]–cycloaddition reaction of various phenylnitrenes and perfluorinated phenylnitrenes para-substituted with (R = CO2H, SO3H) groups, demonstrating favorable energetics. We also monitor the effect of the functionalization on the electronic properties of the nanosheets via density of states and band structure analyses. Finally, we test four dBC6N to gBC6N substrates in the sensing of ammonia. We show that, thanks to their hydrogen bonding capabilities, the functionalized BC6N can selectively detect ammonia, with interaction energies varying from −0.54 eV to −1.37 eV, even in presence of competing gas such as CO2 and H2O, as also confirmed by analyzing the change in the electronic properties and the values of recovery times near ambient temperature. Importantly, we model the conductance of a selected substrate alone and in presence of NH3 to determine its effect on the integrated current, showing that humidity and coverage conditions should be properly tuned to use HO2C-functionalized BC6N-based nanomaterials to develop selective gas sensors for ammonia.
Robust optimization strategies for contour uncertainties in online adaptive radiation therapy
Authors: Smolders A , Bengtsson I , Forsgren A , Lomax A , Weber D C , Fredriksson A , Albertini F
Published: July 2024

Objective. Online adaptive radiation therapy requires fast and automated contouring of daily scans for treatment plan re-optimization. However, automated contouring is imperfect and introduces contour uncertainties. This work aims at developing and comparing robust optimization strategies accounting for such uncertainties. Approach. A deep-learning method was used to predict the uncertainty of deformable image registration, and to generate a finite set of daily contour samples. Ten optimization strategies were compared: two baseline methods, five methods that convert contour samples into voxel-wise probabilities, and three methods accounting explicitly for contour samples as scenarios in robust optimization. Target coverage and organ-at-risk (OAR) sparing were evaluated robustly for simplified proton therapy plans for five head-and-neck cancer patients. Results. We found that explicitly including target contour uncertainty in robust optimization provides robust target coverage with better OAR sparing than the baseline methods, without increasing the optimization time. Although OAR doses first increased when increasing target robustness, this effect could be prevented by additionally including robustness to OAR contour uncertainty. Compared to the probability-based methods, the scenario-based methods spared the OARs more, but increased integral dose and required more computation time. Significance. This work proposed efficient and beneficial strategies to mitigate contour uncertainty in treatment plan optimization. This facilitates the adoption of automatic contouring in online adaptive radiation therapy and, more generally, enables mitigation also of other sources of contour uncertainty in treatment planning.
A non-neutral 1D fluid model of hall thruster discharges: full electron inertia and anode sheath reversal
Authors: Poli D , Fajardo P , Ahedo E
Published: July 2024

A non-neutral model (NNM) of the axial plasma discharge in a Hall thruster, including full electron inertia, is presented. In the finite-volume formulation, two types of sheath boundary conditions previously used in the literature are tested and proven to behave practically identically in this model. Both normal and reversed (i.e. electron repelling and attracting, respectively) anode sheaths are admitted. This model is compared with the quasineutral model developed in a previous work, which includes only azimuthal electron inertia and normal anode sheaths. Both models agree excellently within the parametric region where steady-state solutions with a normal anode sheath exist. The NNM shows the absence of steady-state solutions with a reversed anode sheath. Nonetheless, a reversed sheath can appear during the transient to a steady-state solution with a normal sheath and the periodic transition from a normal to a reversed sheath can be observed in the presence of breathing-mode oscillations. In other cases, the reversed sheath leads to the discharge shut-off. Full electron inertia is always important in the presence of a reversed sheath. The parametric threshold of the wall accommodation parameter from a stationary solution to a breathing mode one differs slightly between the non-neutral and the quasi-neutral model.
Parity violation in primordial tensor non-Gaussianities from matter bounce cosmology
Authors: Akama Shingo , Zhu Mian
Published: July 2024

It has been shown that primordial tensor non-Gaussianities from a cubic Weyl action with a
non-dynamical coupling are suppressed by the so-called slow-roll parameter in a conventional framework of slow-roll inflation. In this paper, we consider matter bounce cosmology in which the background spacetime is no longer quasi-de Sitter, and hence one might expect that the matter bounce models could predict non-suppressed non-Gaussianities. Nevertheless, we first show that the corresponding non-Gaussian amplitudes from the cubic Weyl term with a non-dynamical coupling are much smaller than those from the conventional slow-roll inflation, in spite of the fact that there is no slow-roll suppression. We then introduce a dynamical coupling that can boost the magnitude of graviton cubic interactions and clarify that there is a parameter region where the tensor non-Gaussianities can be enhanced and can potentially be tested by cosmic microwave background experiments.
Initial testing of Alfvén eigenmode feedback control with machine-learning observers on DIII-D
Authors: Rothstein Andrew , Jalalvand Azarakhsh , Abbate Joseph , Erickson Keith , Kolemen Egemen
Published: July 2024

A first of its kind fully data-driven system has been developed and implemented into the DIII-D plasma control system to detect and control Alfvén eigenmodes (AE) in real-time. Susceptibility to fast ion-induced AE is a challenge in fully non-inductive tokamak operation, which significantly reduces fast-particle confinement and results in degraded fusion gain. Controlling AEs in real-time to improve fast-ion confinement is, hence, important for future advanced tokamak fusion reactors. The models were implemented and tested in experiments which showed that neural networks (NN) are highly effective in detecting 5 types of AE (BAE, EAE, LFM, RSAE, TAE) using high resolution ECE. To estimate the neutron deficit, a NN has been trained that outputs the classical neutron rate using similar inputs to NUBEAM. Also a preliminary ML-based proportional control has been designed and gone through initial testing in experiment to use feedback-control on the neutral beam power to achieve desired amplitude of AE modes and neutron deficits. The effect of AEs on fast-ion confinement is measured by analysing the gap in classical neutron rate from the proposed NN-based NUBEAM and the measured neutron rate.
Reusable optically stimulated luminescence dosimetry films for 2D dose verification of proton therapy
Authors: Clausen S. J. G. , Jensen M. L. , Nielsen C. L. , Jensen M. F. , Muren L. , Søndergaard C. S. , Skyt P. S. , Stick L. B. , Yates E. , Vindbæk S. H. , Balling P.
Published: July 2024

Accurate surface-dose measurements in proton therapy are challenging and often of poor spatial resolution for most dosimeter types. However, optically stimulated luminescence (OSL) based 2D dosimeters could provide the required spatial dose resolution. The aim of this study was to investigate the dosimetric precision and energy dependence of an in-house made reusable dosimeter composed of a silicone-film containing OSL-active nanoparticles. The dosimeter was irradiated with a clinical proton therapy field and the readout dose was compared to the results from a commercial dosimeter. The pixelwise noise-to-signal ratio for the OSL dosimeter remained below 2% for doses above 1 Gy, and the energy dependence was negligible in the investigated energy range.
Effects of signal source to camera distance in Cherenkov dosimetry using polarized imaging
Authors: Poher Audran , Michaud Gérémy , Archambault Louis , Beaulieu Luc
Published: July 2024

As Cherenkov emissions are related to dose, they can be used as signal for dosimetric purposes using polarized imaging. However, when using this method, angular corrections must be applied because of Cherenkov anisotropy. Several Cherenkov light source-to-camera distances were tested to characterize its impact on the deviations from reference values of the calculated dose distributions. Average relative differences ranging from −1.6% to −11% between Cherenkov-based results and scintillation results were extracted. It is observed that an increase in Cherenkov light source-to-camera distance decreases the difference between the Cherenkov optical signal and the dose. This reduces the importance of angular corrections at higher distances (4 m and beyond).
Sorbitol to reduce Fe diffusion in a Fricke gel dosimeter and enhance its resistance to elongation
Authors: Piotrowski Michał , Maras Piotr , Kozicki Marek
Published: July 2024

This work presents a 2D Fricke dosimeter with xylenol orange (XO), gelatine matrix and addition of sorbitol. The dosimeter was irradiated with various monitor units ranging from 500 to 10000 MU (3.6-72 Gy). The addition of sorbitol significantly reduced the diffusion coefficient of Fe3+ ions and improved the mechanical properties of the gel, while the chemical stability of the dosimeter decreased.
Scintillation Imaging as Versatile Tool for Validation of UHDR Treatment Plans Across Modalities
Authors: Clark Megan , Vasytlsiv Roman , Gladstone David , Mascia Anthony , Harms Joseph , Bruza Petr
Published: July 2024

Scintillation imaging has been shown to provide high spatio-temporal surface dose information for delivery verification of ultra-high dose rate (UHDR) beams. To obtain higher dose rates, modified clinical machines are often utilized, requiring extensive re-characterization and treatment validation. The goal of this work was to demonstrate the utility of 1.) projecting surface images to depth and 2.) quinine-doped water tank imaging for 3D beam verification across different UHDR treatment modalities.
Polymer gel dosimetry of added High-Z elements in radiation fields of electrons and photons with low and high photon energy
Authors: Buchner Katharina , Gober Manuela , Berg Andreas
Published: July 2024

A dose enhancement in tumors can in principle be achieved using an enrichment of elements with high atomic number (“High-Z therapy”). The proof of dose enhancement at low non-toxic concentrations remains difficult with standard dosimeters due to the small distance of secondary electrons of X-ray photon energies. We investigated within an exploratory research approach the dose enhancement in tissue equivalent environment using MRI analysis of polymer gel dosimeters doped with molecules containing high-Z elements: bismuth, silver iodide and iopromide, a radio-diagnostic contrast agent for X-ray imaging, in photon fields of low (200 kV X-ray) and high energy (6 MV) and in an electron field (6 MeV). An enhancement of the dose response up to a relative dose enhancement factor rDEexp≌1.4 was observed for low concentrations (w/w=0.006) of iopromide, already approved for vascular angiography with X-rays. Experimental limitations and challenging interpretations are outlined.
Development and verification of a Geant4 model of the electron beam mode in a clinical linear accelerator
Authors: Miloichikova I. , Bulavskaya A. , Bushmina E. , Dusaev R. , Gargioni E. , Gavrikov B. , Grigorieva A. , Stuchebrov S.
Published: July 2024

At present, a significant number of studies are focused on the development of novel methodologies for the fabrication of dosimetry phantoms. One of these methods is to produce heterogeneous samples by 3D printing. In order to select the most appropriate parameters for such products, it is necessary to conduct numerical simulations. In this work, we developed the model of a beam-forming system using a medical linear accelerator as a reference. This model was used to determine simulation parameters and corresponding dose distributions of an electron beam with nominal energies of 6, 12, and 15 MeV in a homogeneous water phantom. These parameters were, in fact, adapted to provide maximum agreement between simulated distributions and those experimentally obtained with the clinical linear accelerator. The beam simulation was performed using the Geant4 Monte Carlo toolkit. The simulation geometry of the accelerator treatment head includes scattering foil and a flattening filter, which are designed for electron beam broadening. Additionally, the beam-forming system was incorporated to collimate the beam to the required size. A metal applicator was included to reduce the contribution of electron scattering in air. The main simulation parameters were iteratively tuned by comparing simulation results with experimentally obtained data. It is shown that the simulated percentage depth dose and transverse profiles for electron beams in water phantom are in good agreement with the experimental data obtained with a cylindrical ionization chamber. This demonstrates that the methodology employed in the development of the numerical model of the medical linear accelerator is vendor-independent, readily implementable, and allows for rapid calculations. Furthermore, the model can be applied for a variety of purposes, including the selection of parameters for the fabrication of heterogeneous dosimetry phantoms.
Pneumatic extrusion bioprinting-based high throughput fabrication of a melanoma 3D cell culture model for anti-cancer drug screening
Authors: de Villiers Maryke , Kotzé Awie F , du Plessis Lissinda H
Published: July 2024

The high incidence of malignant melanoma highlights the need for in vitro models that accurately represent the tumour microenvironment, enabling developments in melanoma therapy and drug screening. Despite several advancements in 3D cell culture models, appropriate melanoma models for evaluating drug efficacy are still in high demand. The 3D pneumatic extrusion-based bioprinting technology offers numerous benefits, including the ability to achieve high-throughput capabilities. However, there is a lack of research that combines pneumatic extrusion-based bioprinting with analytical assays to enable efficient drug screening in 3D melanoma models. To address this gap, this study developed a simple and highly reproducible approach to fabricate a 3D A375 melanoma cell culture model using the pneumatic extrusion-based bioprinting technology. To optimise this method, the bioprinting parameters for producing 3D cell cultures in a 96-well plate were adjusted to improve reproducibility while maintaining the desired droplet size and a cell viability of 92.13 ± 6.02%. The cross-linking method was optimised by evaluating cell viability and proliferation of the 3D bioprinted cells in three different concentrations of calcium chloride. The lower concentration of 50 mM resulted in higher cell viability and increased cell proliferation after 9 d of incubation. The A375 cells exhibited a steadier proliferation rate in the 3D bioprinted cell cultures, and tended to aggregate into spheroids, whereas the 2D cell cultures generally formed monolayered cell sheets. In addition, we evaluated the drug responses of four different anti-cancer drugs on the A375 cells in both the 2D and 3D cell cultures. The 3D cell cultures exhibited higher levels of drug resistance in all four tested anti-cancer drugs. This method presents a simple and cost-effective method of producing and analysing 3D cell culture models that do not add additional complexity to current assays and shows considerable potential for advancing 3D cell culture models’ drug efficacy evaluations.
Estimation of the injection criteria for magnetic hyperthermia therapy based on tumor morphology
Authors: Singh Amritpal , Kumar Neeraj
Published: July 2024

Intratumoral multi-injection strategy enhances the efficacy of magnetic nanoparticle hyperthermia therapy (MNPH). In this study, criteria for the selection of injections and their location depending on the tumor shape/geometry are developed. The developed strategy is based on the thermal dosimetry results of different invasive 3D tumor models during MNPH simulation. MNPH simulations are conducted on physical tumor tissue models encased within healthy tissue. The tumor shapes are geometrically divided into a central tumor region containing maximum tumor volume and a peripheral tumor portion protruding in any random direction. The concepts of core and invasive radius are used to geometrically divide the tumor volume. Primary & secondary injections are used to inject MNP fluid into these respective tumor regions based on the invasiveness of the tumor. The optimization strategy is devised based on the zone of influence of primary & secondary injection. Results indicate that the zone of influence of secondary injection lies between 0.7 and 0.8 times the radial distance between the center of the tumor core and branch node point (extreme far endpoint on the invasive tumor surface). Additionally, the multi-injection strategy is more effective when the protrusion volume exceeds

10
%

of the total volume. The proposed algorithm is used to devise multi-injection strategies for arbitrarily shaped tumors and will assist in pre-planning magnetic nanoparticle hyperthermia therapy.