bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of nanodroplets on solid spheres
Authors: Wang Yi-Feng , Ma Qiang , Wei Bo-Jian , Gao Shu-Rong , Yang Yan-Ru , Zheng Shao-Fei , Lee Duu-Jong , Wang Xiao-Dong
Published: August 2023

Rising nanoscale technologies arouse interest in investigating the impact dynamics of nanodroplets. In this work, the impact of nanodroplets on solid spheres is investigated by the molecular dynamics simulation method, to comprehensively report outcome regimes and reveal the curvature effect, in wide ranges of Weber numbers (We) from 1.5 to 235.8, diameter ratios (λ) of nanodroplets to solid spheres from 0.3 to 5, and contact angles (θ) from 105° to 135°. Five outcomes are identified, including deposition, bouncing, splash, covering, and dripping. The former three outcomes are found in the high diameter ratio range (λ > 1), showing similar dynamic behaviors with impacts on flat surfaces, whereas in the low diameter ratio range (λ ≤)1, splash disappears, and covering and dripping take place additionally. At each contact angle, the outcomes are recorded in λ-We phase diagrams. It is found that the bouncing, splash, covering, and dripping are all promoted by decreasing diameter ratios; in addition, the critical Weber numbers for trigging bouncing and splash increase with decreasing θ. However, the critical We of the boundary between the bouncing to other regimes in the low diameter ratio range is not sensitive to wettability owing to the relatively small diameter of solid spheres. For quantitatively describing the curvature effect, the boundaries between the deposition and bouncing regimes in the high diameter ratio range and between the bouncing and other regimes in the low diameter ratio range are established. Both the established models show satisfactory agreement with the boundaries in the phase diagrams.
An experimental study on the impact of Boger and Newtonian droplets on spherical surfaces
Authors: Sheykhian Mohammad Kazam , Kayhani Mohammad Hasan , Norouzi Mahmood , Kim Mirae , Kim Kyung Chun
Published: August 2023

This study examined the impact of Boger droplets on spherical surfaces, considering the various properties of liquids and surfaces for the first time. The experimental setup involved spheres with three different diameters composed of hydrophilic and hydrophobic surfaces. The main innovative aspect of the present study lies in the examination of the effects of rheological properties including elasticity, elongational viscosity, and the first normal stress difference on the impact of Boger droplets on solid surfaces via stress analysis. For this purpose, the results of the impact of Boger droplets are compared to the impact of equivalent Newtonian droplets with the same viscosity and surface tension coefficient. The research also explored the influences of Weber number, diameter ratio, and surface wettability on the dynamic behaviors of viscoelastic droplets during the spreading and receding stages. The results suggested that increasing the Weber number increases the maximum spreading factor of the droplets. A smaller diameter ratio required more time to reach this factor. The surface wettability significantly affected the receding phase, while its effect on the spreading stage was minimal. Droplets exhibited more retraction on surfaces with higher contact angles. The Newtonian fluids showed greater spreading and retraction than viscoelastic fluids with the same viscosity, highlighting the influence of fluid elasticity. It is shown that the normal stress caused by extensional viscosity during droplet spreading is significantly higher than the normal stress difference resulting from shear deformation, showing different behaviors between these two types of stress concerning droplets.
Bio-templated energy transfer system for constructing artificial light-harvesting antennae, white light generation, and photonic nanowires
Authors: Pramanik Srikrishna , Mukherjee Saptarshi
Published: August 2023

Developing environmentally friendly, sustainable, and biocompatible artificial light-harvesting systems has become an essential area of research to understand natural light-harvesting processes involving multistep resonance energy transfer and building efficient energy conversion systems related to energy and optoelectronic applications. In this direction, bio-scaffolded artificial energy transfer systems for panchromatic light collection and sequential energy transfer have fascinated the scientific community. In this review, we have discussed what the dynamic structure and intrinsic physical properties of biomolecules like deoxyribonucleic acid, proteins, and peptides can provide for the development of new optical devices, sustainable and environmentally friendly white emitting materials, and cascaded energy transfer systems for energy harvesting from light. In doing so, we have highlighted some of the recent advances in bio-scaffolds as a platform for the assembly of different types of donor–acceptor chromophores involved in fluorescence energy transfer.
Effects of surface imperfections on the transitional boundary layer
Authors: Teng Ming
Published: August 2023

The present work explores the effects of surface imperfections on the transition to turbulence of an incompressible boundary layer over a flat-plate. The analysis focuses on flow mean-dynamics. Visualization of instantaneous coherent structures provides insight into the flow evolution. Geometries considered include forward-facing steps and a step-cavity, representative of roughness commonly seen in manufacturing; the step-sizes and cavity depth are a small fraction of the local boundary layer thickness. A series of well-resolved direct numerical simulations are performed. A controlled Klebanoff-type transition is initiated via a narrow vibrating ribbon placed upstream of the surface imperfection. To distinguish the impact of the forward-facing step and the effect of the cavity, data from a flat-plate and medium-height backward-facing step cases from a previous study [M. Teng and U. Piomelli, “Instability and transition of a boundary layer over a backward-facing step,” Fluids 7, 35 (2022).] is employed as a reference for comparison. The perturbations are found to be locally stabilized, and transition inception is delayed for the medium-height forward-facing step, whereas in all other cases, increased growth-rates promote the onset of transition. The evolution of flow structures in the step-cavity case resembles that of the medium-height backward-facing step: the Kelvin–Helmholtz instability is a predominant mechanism that drives the amplification in the separation region. The phenomenon of stabilization and destabilization is explained from the perspective of energy budget analysis. Although the active instability mechanisms for each surface imperfection are locally influential, the route to turbulence via the Klebanoff regime remains qualitatively the same, independent of stabilizing or destabilizing effect.
174Yb+–113Cd+ sympathetic-cooling bi-species Coulomb crystal applied to microwave frequency standard
Authors: Zheng Y. , Qin H. R. , Miao S. N. , Xin N. C. , Chen Y. T. , Han J. Z. , Zhang J. W. , Wang L. J.
Published: August 2023

We reported the realization of a 174Yb+–113Cd+ bi-species Coulomb crystal comprising 174Yb+, a heavier ion, as coolant and verified the potential of applying a coolant ion with a greater mass than the clock ion to sympathetically cooled microwave frequency standard. The two species of massive ions stably trapped in a Paul trap make up this large two-component crystal. The 113Cd+ ions are trapped in the center, which reduces considerably RF heating and excess micro-motion to which the 113Cd+ ions are subjected. Under this scheme, the uncertainty due to the second-order Doppler effect is reduced to 5×10−16, which represents an order of magnitude improvement over sympathetic cooled 40Ca+–113Cd+ crystal. The second-order Zeeman frequency shift, which contributes the largest term of the systematic frequency shifts to the microwave ion frequency standard, is estimated to be as low as 7.133×10−13 corresponding to the low value of the operating magnetic field. The relevant AC Stark shift uncertainty is estimated to be 4×10−19. These results demonstrate that using a heavier coolant ion is far superior and confirm the feasibility of a sympathetic-cooled cadmium-ion microwave clock system employing a 174Yb+–113Cd+ bicrystal.
Hydrophobic poly-TPD modified PEDOT PSS surface for improved and stable photovoltaic performance of MAPbI3 based p-i-n perovskite solar cells
Authors: Alexander Akhil , Pillai Anitha B. , Pulikodan Vijith K. , Joseph Alvin , Raees A Muhammed , Namboothiry Manoj A. G.
Published: August 2023

Inferior morphology of perovskite films and suppressed hole extraction restricts the performance of perovskite solar cells (PSCs) with a PEDOT:PSS hole transporting layer (HTL). In this work, poly-TPD is used to modify the surface of PEDOT:PSS films in PSC. The presence of hydrophobic poly-TPD decreases the nucleation sites, and as a result, perovskite films with larger grains are obtained. Improved energy level alignment in the presence of poly-TPD results in enhanced hole extraction from the perovskite layer to the HTL. The improved morphology and charge extraction resulted in improved photovoltaic performance. The power conversion efficiency (PCE) of PSCs was increased from 13.6% to 16.1% with the incorporation of poly-TPD. Also, the shelf life of the PSCs has exhibited considerable improvement due to the presence of hydrophobic poly-TPD and fewer number of grain boundaries. After 66 days, the PSC with poly-TPD maintained 96% of its initial PCE, whereas the PCE of the control device degraded to 72% of its initial value.
Random organization and non-equilibrium hyperuniform fluids on a sphere
Authors: Lei Yusheng , Zheng Ning , Ni Ran
Published: August 2023

Randomly organizing hyperuniform fluid induced by reciprocal activation is a non-equilibrium fluid with vanishing density fluctuations at large length scales such as crystals. Here, we extend this new state of matter to a closed manifold, namely a spherical surface. We find that the random organization on a spherical surface behaves similar to that in two dimensional Euclidean space, and the absorbing transition on a sphere also belongs to the conserved directed percolation universality class. Moreover, the reciprocal activation can also induce a non-equilibrium hyperuniform fluid on a sphere. The spherical structure factor at the absorbing transition and the non-equilibrium hyperuniform fluid phases are scaled as S(l → 0) ∼ (l/R)0.45 and S(l → 0) ∼ l(l + 1)/R2, respectively, which are both hyperuniform according to the definition of hyperuniformity on a sphere with l, the wave number, and R, the radius of the spherical surface. We also consider the impact of inertia in realistic hyperuniform fluids, and it is found only by adding an extra length-scale, above which hyperuniform scaling appears. Our finding suggests a new method for creating non-equilibrium hyperuniform fluids on closed manifolds to avoid boundary effects.
Ionically driven synthesis and exchange bias in Mn4N/MnNx heterostructures
Authors: Chen Zhijie , Jensen Christopher J. , Liu Chen , Zhang Xixiang , Liu Kai
Published: August 2023

Ferrimagnets have received renewed attention as a promising platform for spintronic applications. Of particular interest is the Mn4N from the ε-phase of the manganese nitride as an emergent rare-earth-free spintronic material due to its perpendicular magnetic anisotropy, small saturation magnetization, high thermal stability, and large domain wall velocity. We have achieved high-quality (001)-ordered Mn4N thin film by sputtering Mn onto η-phase Mn3N2 seed layers on Si substrates. As the deposited Mn thickness varies, nitrogen ion migration across the Mn3N2/Mn layers leads to a continuous evolution of the layers to Mn3N2/Mn2N/Mn4N, Mn2N/Mn4N, and eventually Mn4N alone. The ferrimagnetic Mn4N, indeed, exhibits perpendicular magnetic anisotropy and forms via a nucleation-and-growth mechanism. The nitrogen ion migration is also manifested in a significant exchange bias, up to 0.3 T at 5 K, due to the interactions between ferrimagnetic Mn4N and antiferromagnetic Mn3N2 and Mn2N. These results demonstrate a promising all-nitride magneto-ionic platform with remarkable tunability for device applications.
PCS/Bonds and PCS0: Pick your molecule and get its accurate structure and ground state rotational constants at DFT cost
Authors: Barone Vincenzo
Published: August 2023

An unsupervised computational protocol is proposed with the aim of obtaining accurate structures of large molecules in the gas phase at the cost of standard density functional theory (DFT) computations. The whole workflow is fully automated and provides optimized equilibrium geometries and ground state rotational constants to be directly compared with experiments. The results for a panel of molecules of biological or medicinal interest show that the accuracy of the results delivered by the new tool at the cost of a single DFT geometry optimization is close to that delivered by state-of-the-art composite wavefunction methods for small semi-rigid molecules.
The quorum-sensing peptidic inhibitor rescues host immune system eradication: A novel infectivity mechanism
Authors: Yehuda Avishag , Malach Einav , Vanunu Ofri Shahar , Slamti Leyla , Kuo Shanny Hsuan , Lau Jonathan Z. , Oh Myung Whan , Adeoye John , Shlezinger Neta , Lereclus Didier , Lau Gee W. , Hayouka Zvi
Published: August 2023

Subverting the host immune system is a major task for any given pathogen to assure its survival and proliferation. For the opportunistic human pathogen
Bacillus cereus
(Bc), immune evasion enables the establishment of potent infections. In various species of the Bc group, the pleiotropic regulator PlcR and its cognate cell–cell signaling peptide PapR
7
regulate virulence gene expression in response to fluctuations in population density, i.e., a quorum-sensing (QS) system. However, how QS exerts its effects during infections and whether PlcR confers the immune evading ability remain unclear. Herein, we report how interception of the QS communication in Bc obliterates the ability to affect the host immune system. Here, we designed a peptide-based QS inhibitor that suppresses PlcR-dependent virulence factor expression and attenuates Bc infectivity in mouse models. We demonstrate that the QS peptidic inhibitor blocks host immune system–mediated eradication by reducing the expression of PlcR-regulated major toxins similarly to the profile that was observed for isogenic strains. Our findings provide evidence that Bc infectivity is regulated by QS circuit-mediated destruction of host immunity, thus reveal a interesting strategy to limit Bc virulence and enhance host defense. This peptidic quorum-quenching agent constitutes a readily accessible chemical tool for studying how other pathogen QS systems modulate host immunity and forms a basis for development of anti-infective therapeutics.
SARS-CoV-2 Mac1 is required for IFN antagonism and efficient virus replication in cell culture and in mice
Authors: Alhammad Yousef M. , Parthasarathy Srivatsan , Ghimire Roshan , Kerr Catherine M. , O’Connor Joseph J. , Pfannenstiel Jessica J. , Chanda Debarati , Miller Caden A. , Baumlin Nathalie , Salathe Matthias , Unckless Robert L. , Zuñiga Sonia , Enjuanes Luis , More Sunil , Channappanavar Rudragouda , Fehr Anthony R.
Published: August 2023

Several coronavirus (CoV) encoded proteins are being evaluated as targets for antiviral therapies for COVID-19. Included in these drug targets is the conserved macrodomain, or Mac1, an ADP-ribosylhydrolase and ADP-ribose binding protein encoded as a small domain at the N terminus of nonstructural protein 3. Utilizing point mutant recombinant viruses, Mac1 was shown to be critical for both murine hepatitis virus (MHV) and severe acute respiratory syndrome (SARS)-CoV virulence. However, as a potential drug target, it is imperative to understand how a complete Mac1 deletion impacts the replication and pathogenesis of different CoVs. To this end, we created recombinant bacterial artificial chromosomes (BACs) containing complete Mac1 deletions (ΔMac1) in MHV, MERS-CoV, and SARS-CoV-2. While we were unable to recover infectious virus from MHV or MERS-CoV ΔMac1 BACs, SARS-CoV-2 ΔMac1 was readily recovered from BAC transfection, indicating a stark difference in the requirement for Mac1 between different CoVs. Furthermore, SARS-CoV-2 ΔMac1 replicated at or near wild-type levels in multiple cell lines susceptible to infection. However, in a mouse model of severe infection, ΔMac1 was quickly cleared causing minimal pathology without any morbidity. ΔMac1 SARS-CoV-2 induced increased levels of interferon (IFN) and IFN-stimulated gene expression in cell culture and mice, indicating that Mac1 blocks IFN responses which may contribute to its attenuation. ΔMac1 infection also led to a stark reduction in inflammatory monocytes and neutrophils. These results demonstrate that Mac1 only minimally impacts SARS-CoV-2 replication, unlike MHV and MERS-CoV, but is required for SARS-CoV-2 pathogenesis and is a unique antiviral drug target.
Elastocaloric signatures of symmetric and antisymmetric strain-tuning of quadrupolar and magnetic phases in DyB
2
C
2
Authors: Ye Linda , Sun Yue , Sunko Veronika , Rodriguez-Nieva Joaquin F. , Ikeda Matthias S. , Worasaran Thanapat , Sorensen Matthew E. , Bachmann Maja D. , Orenstein Joseph , Fisher Ian R.
Published: August 2023

The adiabatic elastocaloric effect measures the temperature change of a given system with strain and provides a thermodynamic probe of the entropic landscape in the temperature-strain space. Here, we demonstrate that the DC bias strain-dependence of AC elastocaloric effect allows decomposition of the latter into symmetric (rotation-symmetry-preserving) and antisymmetric (rotation-symmetry-breaking) strain channels, using a tetragonal

f

-electron intermetallic DyB

2

C

2

—whose antiferroquadrupolar order breaks local fourfold rotational symmetries while globally remaining tetragonal—as a showcase example. We capture the strain evolution of its quadrupolar and magnetic phase transitions using both singularities in the elastocaloric coefficient and its jumps at the transitions, and the latter we show follows a modified Ehrenfest relation. We find that antisymmetric strain couples to the underlying order parameter in a biquadratic (linear-quadratic) manner in the antiferroquadrupolar (canted antiferromagnetic) phase, which are attributed to a preserved (broken) global tetragonal symmetry, respectively. The broken tetragonal symmetry in the magnetic phase is further evidenced by elastocaloric strain-hysteresis and optical birefringence. Additionally, within the staggered quadrupolar order, the observed elastocaloric response reflects a quadratic increase of entropy with antisymmetric strain, analogous to the role magnetic field plays for Ising antiferromagnetic orders by promoting pseudospin flips. Our results demonstrate AC elastocaloric effect as a compact and incisive thermodynamic probe into the coupling between electronic degrees of freedom and strain in free energy, which holds the potential for investigating and understanding the symmetry of a wide variety of ordered phases in broader classes of quantum materials.
Granola Nazis and the great reset
Authors: Tebaldi Catherine
Published: August 2023

This paper analyzes the naturalization of Nazism, through semiotic processes of enregisterment, circulation, and regimentation of the register “nature-tradition” associated with a characterological figure I term the Granola Nazi. Granola Nazi is assembled through a rhematized set of semiotic elements, images, practices and forms of talk, which have come to indicate socially typified personae – strong virile white farmers, traditional earthy homesteading moms – and the moral order they embody. Using linguistic anthropological and digital methods, this analysis draws on 885 Instagram accounts as well as linked data from YouTube and print media (i.e. cookbooks, diet advice), to explore how the worlds of far right neo-folkish movement intersect with discourses of health and wellness, creating moralized discourses of “natural beauty” and “folk vitality” which naturalize far- right racial hierarchies. This is at once a co-option of discourses of health and environment, but also one which reveals the how the naturalization of Nazism is made possible by racism and sexism in long present in liberal talk about nature, beauty or wellness.
Impoliteness and pragmatic preferences in German translations of British and Irish children’s fiction
Authors: Pleyer Monika
Published: August 2023

This paper argues that linguistic impoliteness in British and Irish children’s fiction undergoes some severe changes when translated into German. A novel system with five translation strategies is developed to account for the omission, weakening or aggravation of impolite utterances in the source text. In an analysis of three British and Irish children’s books and their German translations, it further shows that genre and publication date have a strong influence on the kind and number of changes to the source text. Especially older texts and school stories include a tendency to delete impolite utterances or use colloquial language which makes conflicts appear less serious.
From the sensing body to language, and back
Authors: Mondada Lorenza
Published: August 2023

Tasting sessions are an exemplary setting to investigate how participants choose descriptors for expressing sensorial judgments, based upon their own sensorial experience, as well as on existing available terminologies in different languages. On the basis of video-recorded tasting sessions of amateurs and professionals, the study shows how participants navigate between different types of descriptions – vocalizations, lexical descriptors, and clausal descriptions – in different languages, within ordinary vs specialized professional repertoires. Based on multimodal conversation analysis and ethnomethodology, the study reveals how they establish the interactional semantics of the descriptors in both a situated and a standardized/standardizing way, and they establish the (un)translatability of these descriptors. Different conceptions of translation and translatability are discussed, contributing to a pragmatic of translation sensu latu.
GRaM-X: a new GPU-accelerated dynamical spacetime GRMHD code for Exascale computing with the Einstein Toolkit
Authors: Shankar Swapnil , Mösta Philipp , Brandt Steven R , Haas Roland , Schnetter Erik , de Graaf Yannick
Published: August 2023

We present GRaM-X (General Relativistic accelerated Magnetohydrodynamics on AMReX), a new GPU-accelerated dynamical-spacetime general relativistic magnetohydrodynamics (GRMHD) code which extends the GRMHD capability of Einstein Toolkit to GPU-based exascale systems. GRaM-X supports 3D adaptive mesh refinement (AMR) on GPUs via a new AMR driver for the Einstein Toolkit called CarpetX which in turn leverages AMReX, an AMR library developed for use by the United States DOE’s Exascale Computing Project. We use the Z4c formalism to evolve the Einstein equations and the Valencia formulation to evolve the equations of GRMHD. GRaM-X supports both analytic as well as tabulated equations of state. We implement TVD and WENO reconstruction methods as well as the HLLE Riemann solver. We test the accuracy of the code using a range of tests on static spacetime, e.g. 1D magnetohydrodynamics shocktubes, the 2D magnetic rotor and a cylindrical explosion, as well as on dynamical spacetimes, i.e. the oscillations of a 3D Tolman-Oppenheimer-Volkhof star. We find excellent agreement with analytic results and results of other codes reported in literature. We also perform scaling tests and find that GRaM-X shows a weak scaling efficiency of ∼40%–50% on 2304 nodes (13824 NVIDIA V100 GPUs) with respect to single-node performance on OLCF’s supercomputer Summit.
Smooth metrics can hide thin shells
Authors: Feng Justin C
Published: August 2023

In this note, I consider a class of metric tensors with smooth components that naively appear to describe dynamical wormholes with vanishing spacetime curvature. I point out that the smoothness of the metric tensor components is deceptive, and that in general relativity, such metrics must be sourced by exotic thin shells.
Inexpensive and rapid fabrication of PDMS microfluidic devices for biological testing applications using low cost commercially available 3D printers
Authors: Ramasamy Megala , Ho Brandon , Phan Chau-Minh , Qin Ning , Ren Carolyn L , Jones Lyndon
Published: August 2023

Polydimethylsiloxane (PDMS) elastomers have been extensively used in the development of microfluidic devices, capable of miniaturizing biomolecular and cellular assays to the microlitre and nanolitre range, thereby increasing the throughput of experimentation. PDMS has been widely used due to its optical clarity and biocompatibility, among other desirable physical and chemical properties. Despite the widespread use of PDMS in microfluidic devices, the fabrication process typically via soft lithography technology requires specialized facilities, instruments, and materials only available in a limited number of laboratories. To expand microfluidic research capabilities to a greater scientific population, we developed and characterized a simple and robust method of fabricating relatively inexpensive PDMS microfluidic devices using readily available reagents and commercially available three-dimensional (3D) printers. The moulds produced from the 3D printers resolve designed microfluidic channel features accurately with high resolution (>100 µm). The critical physical and chemical post-processing modifications we outline here are required to generate functional and optically clear microfluidic devices.
Simple method to suppress n = −2 harmonic for periodic leaky-wave antennas with open-stopband suppression
Authors: Lei Siyuan , Wei Gao , Han Kangkang , Wang Min
Published: August 2023

Periodic leaky-wave antennas (PLWAs) suffer two main issues limiting their scanning ability. The first one is n= −2 spatial harmonic radiation, generating high grating-lobe levels. In this paper, a simple technique by introducing glide-symmetry structure to the PLWA is analysed and used to reduce n = −2 space harmonic level and enhance n = −1 harmonic radiation, subsequently. The other issue is open-stopband (OSB), preventing PLWAs from scanning through broadside. By analysing the ABCD matrix of the cascaded equivalent circuit for the unit cell, a conjugate match condition to counteract the susceptance of the radiation element to suppress the OSB is obtained, which is simple without extracting any parameters. A half-mode substrate integrated waveguide-based prototype is designed and manufactured to demonstrate the proposed methods. The measured results show that the proposed antenna achieves gain fluctuation lower than 1 dB and sidelobe level less than −12 dB, indicating OSB and n = −2 harmonic suppression well, which demonstrates the validity of the proposed method.
Development of magnetic image super-resolution model for nondestructive testing
Authors: Le Hoangcong , Luong Van Su , Le Minhhuy
Published: August 2023

Electromagnetic testing (ET) is a method in the nondestructive evaluation (NDE) methodology for detecting and evaluating cracks in engineering structures by measuring the distribution of the electromagnetic field. With the development of advanced deep learning (DL) techniques, DL is getting attention in crack detection problems through the measuring signals of NDE systems. However, obtaining the necessary big data for such experiments is a time-consuming and expensive task. Moreover, the quality of the crack detection results heavily depends on the quality and spatial resolution of the input image data. In this research, we solve the above-mentioned problems by proposing a DL-based method on the magnetic image for both the image super-resolution and image denoise. We first build a magnetic image simulation framework for the ET system, and thus, it is possible to build a large dataset for training the DL model. Second, we build a DL model for enhancing the quality of the magnetic image in both the spatial resolution and the denoise signal. This approach helps to reduce the cost of experiments (i.e. reducing the number of sensors for each experiment), sensor fabrication process, and noise removal of the ET system. We evaluate the proposed approach on several cracks with different sizes and shapes of aluminum specimens. The evaluation metrics, such as the structural similarity index measure (SSIM) and root mean square error show good performance of the proposed approach and compared to traditional methods.
Twin-boundary and precipitate interaction in Mg–Al alloy: an MD study
Authors: Moitra Amitava
Published: August 2023

Strengthening of Mg-alloys by precipitation is much less efficient than in other metallic alloys (e.g. Al) as the Mg17Al12 precipitates grow as thin plate or lozenge shaped or long rod shape parallel to the basal plane. Recently atomistic simulations reveal that the dislocation-precipitate interaction is very week to claim for the precipitation hardening mechanism. However, the interaction of twin-boundary with the Mg17Al12 precipitate remains unexplored using atomistic simulation. In the present study we focus on the twin-boundary/precipitate interaction at different temperatures, precipitate sizes and varied applied loads, carried out using classical molecular dynamics methodology. In particular, the activation energies necessary to overcome various precipitates are determined as a function of the temperature, precipitate size and applied load. The velocity profile of the twin is calibrated with these different external conditions. An attractive nature of interaction has been observed while the twin-boundary comes closer to the precipitate and a network of dislocations are observed when the twin-boundary bypass the precipitate, as manifested through our atomistic microstructures. These results provide valuable information about the precipitate hardening mechanisms and suggested new avenues to improve the mechanical properties of Mg–Al alloys.
Microscopic investigation of intrinsic defects in CVD grown MoS2 monolayers
Authors: Senkić Ana , Supina Antonio , Akturk Mert , Gadermaier Christoph , Maiuri Margherita , Cerullo Giulio , Vujičić Nataša
Published: August 2023

Defects in two-dimensional (2D) transition metal dichalcogenides (TMDs) greatly influence their electronic and optical properties by introducing localized in-gap states. Using different non-invasive techniques, we have investigated the spatial distribution of intrinsic defects in as-grown chemical vapor deposition (CVD) MoS2 monolayers and correlated the results with the growth temperature of the sample. We have shown that by increasing the CVD growth temperature the concentration of defects decreases and their spatial distribution and type change, influencing the sample’s electronic and optical properties.
In situ thermal noise measurements under nanoindentation of suspended graphene
Authors: Takehara Rin , Uto Yuki , Matsui Tomohiro , Hara Masahiro
Published: August 2023

We demonstrated thermal noise measurement under the nanoindentation of monolayer and bilayer graphene nanodrums. The resonant oscillation of the cantilever excited only by a thermal energy is detectable even in the case of contact with a suspended graphene. The contact resonance fRequency can be obtained in 1 millisecond intervals during the force curve measurement by optimizing the parameters of a real-time spectrum analyzer. The pretension value of the graphene nanodrum is evaluated by the minimum frequency just when the applied force of the cantilever becomes zero. The simultaneous measurement of the force and the resonant frequency with respect to the deformation of the graphene nanodrum enables us to determine the value of InvOLS (inverse optical lever sensitivity) more accurately in each measurement. From the analysis scheme, force curve measurements of the graphene nanodrums with the same diameters show good reproducibility. We also revealed that the effective spring constant of the graphene nanodrums consists of a weak sample-dependent pretension factor and a deformation-dependent factor proportional to the number of graphene layers.
A crossbar architecture based system (CAS) as hydrogen gas sensing platform
Authors: Jana Abir , Kanrar Sharmistha Shee , De Arpan , Kumari Komal , Gupta Bhaskar , Sarkar Subir Kumar
Published: August 2023

The development of sensing technologies and miniaturization allows for the development of smart systems with elevated sensing performance. Silicon-based hydrogen sensors have received a lot of attention due to its electrical conductivity and the mechanical endurance. With this motivation, we have proposed a two-terminal silicon-based device in a crossbar architecture as a hydrogen gas sensing platform. In this work, we have adopted a multi-layer modeling approach to analyze the performance of the proposed system. Technology computer-aided design models have been used to capture device performance. A gas sensor model based on hydrogen adsorption on the Palladium surface and a crossbar model has been adopted to understand the Palladium work function variation with gas pressure and the performance of the proposed crossbar system respectively. We have shown the impact of parameters like interconnect resistance and array size on the whole system’s performance. Finally, a comprehensive analysis has been provided for the design rule of this architecture. A fabrication process to spur future experimental works has also been added. This work will provide computational insight into the performance of a crossbar hydrogen sensor system, optimized against some critical parameters.
High sensitivity and wide range flexible piezoresistive sensor based on petal-shaped MOF-derived NiCo-NPC
Authors: Zeng Ziran , Li Yunfan , Zhao Yilin , Yuan Jun , Yi Longju , Li Peilong , Cheng Gary J , Liu Feng
Published: August 2023

Due to the advantages of high porosity, excellent conductivity, and tunable morphology, carbonized metal-organic framework (C-MOF) is expected to become an ideal material for constructing high-performance flexible pressure sensor. Herein, to achieving the suitable morphology of C-MOF for piezoresistive sensors, a rapid thermal process (RTP) was used for carbonization of NiCo-MOF, and the petal-shaped NiCo alloy nanoparticles/nanoporous carbon composites (NiCo-NPCs) were obtained. Compared with NiCo-NPCs carbonized by common thermal process (CTP), NiCo-NPCs carbonized by RTP exhibit a modified morphology with smaller particle size and larger most frequent pore diameter. Due to the modified morphology, the piezoresistive sensor with RTP-carbonized NiCo-NPCs has a high sensitivity of 62.13 kPa–1 at 0–3 kPa, which is 3.46 times higher than that of the sensor with CTP-carbonized NiCo-NPCs. Meanwhile, the sensor shows an ultra-wide range of 1000 kPa, excellent cycle stability (>4000 cycles), and fast response/recovery time of 25/44 ms. Furthermore, the application of the sensor in dynamic loading test, airflow monitoring, voice recognition, and gesture detection demonstrates its great application prospects. In short, this work investigates the application of carbonized NiCo-MOFs in flexible pressure sensors, and provides a new strategy to improve the performance of piezoresistive sensors with porous carbon derived from MOFs.
MRI magnitude signal-based proton beam visualisation in water phantoms reflects composite effects of beam-induced buoyant convection and radiation chemistry
Authors: Schieferecke Juliane , Gantz Sebastian , Karsch Leonhard , Pawelke Jörg , Hoffmann Aswin
Published: August 2023

Objective. Local magnetic resonance (MR) signal loss was previously observed during proton beam irradiation of free-floating water phantoms at ambient temperature using a research prototype in-beam magnetic resonance imaging (MRI) scanner. The emergence of this MR signal loss was hypothesised to be dependent on beam-induced convection. The aim of this study was therefore to unravel whether physical conditions allowing the development of convection must prevail for the beam-induced MRI signatures to emerge. Approach. The convection dependence of MRI magnitude signal-based proton beam visualisation was investigated in combined irradiation and imaging experiments using a gradient echo (GE)-based time-of-flight (ToF) angiography pulse sequence, which was first tested for its suitability for proton beam visualisation in free-floating water phantoms at ambient temperature. Subsequently, buoyant convection was selectively suppressed in water phantoms using either mechanical barriers or temperature control of water expansivity. The underlying contrast mechanism was further assessed using sagittal imaging and variation of T1 relaxation time-weighting. Main results. In the absence of convection-driven water flow, weak beam-induced MR signal changes occurred, whereas strong changes did occur when convection was not mechanically or thermally inhibited. Moreover, the degree of signal loss was found to change with the variation of T1-weighting. Consequently, beam-induced MR signal loss in free-floating water phantoms at ambient temperature does not exclusively originate from buoyant convection, but is caused by local composite effects of beam-induced motion and radiation chemistry resulting in a local change in the water T1 relaxation time. Significance. The identification of ToF angiography sequence-based proton beam visualisation in water phantoms to result from composite effects of beam-induced motion and radiation chemistry represents the starting point for the future elucidation of the currently unexplained motion-based MRI contrast mechanism and the identification of the proton beam-induced material change causing T1 relaxation time lengthening.
Thermal neutron detection and track recognition method in reference and out-of-field radiotherapy FLASH electron fields using Timepix3 detectors
Authors: Oancea Cristina , Solc Jaroslav , Bourgouin Alexandra , Granja Carlos , Jakubek Jan , Pivec Jiri , Riemer Felix , Vykydal Zdenek , Worm Steven , Marek Lukas
Published: August 2023

Objective. This work presents a method for enhanced detection, imaging, and measurement of the thermal neutron flux. Approach. Measurements were performed in a water tank, while the detector is positioned out-of-field of a 20 MeV ultra-high pulse dose rate electron beam. A semiconductor pixel detector Timepix3 with a silicon sensor partially covered by a 6LiF neutron converter was used to measure the flux, spatial, and time characteristics of the neutron field. To provide absolute measurements of thermal neutron flux, the detection efficiency calibration of the detectors was performed in a reference thermal neutron field. Neutron signals are recognized and discriminated against other particles such as gamma rays and x-rays. This is achieved by the resolving power of the pixel detector using machine learning algorithms and high-resolution pattern recognition analysis of the high-energy tracks created by thermal neutron interactions in the converter. Main results. The resulting thermal neutrons equivalent dose was obtained using conversion factor (2.13(10) pSv·cm2) from thermal neutron fluence to thermal neutron equivalent dose obtained by Monte Carlo simulations. The calibrated detectors were used to characterize scattered radiation created by electron beams. The results at 12.0 cm depth in the beam axis inside of the water for a delivered dose per pulse of 1.85 Gy (pulse length of 2.4 μs) at the reference depth, showed a contribution of flux of 4.07(8) × 103 particles·cm−2·s−1 and equivalent dose of 1.73(3) nSv per pulse, which is lower by ∼9 orders of magnitude than the delivered dose. Significance. The presented methodology for in-water measurements and identification of characteristic thermal neutrons tracks serves for the selective quantification of equivalent dose made by thermal neutrons in out-of-field particle therapy.
In vivo dosimetry in cancer patients undergoing intraoperative radiation therapy
Authors: Petoukhova Anna , Snijder Roland , Vissers Thomas , Ceha Heleen , Struikmans Henk
Published: August 2023

In vivo dosimetry (IVD) is an important tool in external beam radiotherapy (EBRT) to detect major errors by assessing differences between expected and delivered dose and to record the received dose by individual patients. Also, in intraoperative radiation therapy (IORT), IVD is highly relevant to register the delivered dose. This is especially relevant in low-risk breast cancer patients since a high dose of IORT is delivered in a single fraction. In contrast to EBRT, online treatment planning based on intraoperative imaging is only under development for IORT. Up to date, two commercial treatment planning systems proposed intraoperative ultrasound or in-room cone-beam CT for real-time IORT planning. This makes IVD even more important because of the possibility for real-time treatment adaptation. Here, we summarize recent developments and applications of IVD methods for IORT in clinical practice, highlighting important contributions and identifying specific challenges such as a treatment planning system for IORT. HDR brachytherapy as a delivery technique was not considered. We add IVD for ultrahigh dose rate (FLASH) radiotherapy that promises to improve the treatment efficacy, when compared to conventional radiotherapy by limiting the rate of toxicity while maintaining similar tumour control probabilities. To date, FLASH IORT is not yet in clinical use.
Joint two-stage convolutional neural networks for intracranial aneurysms detection on 3D TOF-MRA
Authors: Zhou Yuxi , Yang Yifeng , Fang Ting , Jia Shouqiang , Nie Shengdong , Ye Xiaodan
Published: August 2023

Objective. This study aims to develop a three-dimensional convolutional neural network utilizing computer-aided diagnostic technology to facilitate the detection of intracranial aneurysms and automatically assess their location and extent, thereby enhancing the efficiency of radiologists, and streamlining clinical workflows. Approach. A retrospective study was conducted, proposing a joint segmentation and classification network (JSCD-Net) that employs 3D time-of-flight magnetic resonance angiography images for preliminary detection of aneurysms and the minimization of false positives. Specifically, the U-Net++ network was utilized for pre-detection of aneurysms. This was followed by the creation of a multi-path network, co-trained with U-Net++ to correct the results of the first stage to further reduce the rate of false positives. Model effectiveness and robustness were evaluated using sensitivity and false positive analyses on internal and external datasets. A cross-validated free-response receiver operating characteristic curve was also plotted. Main results. JSCD-Net demonstrated a sensitivity of 91.2% (31 of 34; 95% CI: 77.0, 97.0) with an average of 3.55 false positives per scan on the internal test set. For the external test set, it identified 97.2% (70 of 72; 95% CI: 90.4, 99.2) of aneurysms with an average of 2.7 false positives per scan. Significance. When compared with the existing studies, the proposed model shows high sensitivity in detecting intracranial aneurysms with a reasonable number of false positives per case. This result emphasizes the model’s potential as a valuable tool in aiding clinical diagnoses.
Bio-potential noise of dry printed electrodes: physiology versus the skin-electrode impedance
Authors: Arché-Núñez Ana , Krebsbach Peter , Levit Bara , Possti Daniel , Gerston Aaron , Knoll Thorsten , Velten Thomas , Bar-Haim Chen , Oz Shani , Klorfeld-Auslender Shira , Hernandez-Sosa Gerardo , Mirelman Anat , Hanein Yael
Published: August 2023

Objective. To explore noise characteristics and the effect physiological activity has on the link between impedance and noise. Approach. Dry-printed electrodes are emerging as a new and exciting technology for skin electro-physiology. Such electrode arrays offer many advantages including user convenience, quick placement, and high resolution. Here we analyze extensive electro-physiological data recorded from the arm and the face to study and quantify the noise of dry electrodes, and to characterize the link between noise and impedance. In particular, we studied the effect of the physiological state of the subject (e.g. rapid eye movement sleep) on noise. Main results. We show that baseline noise values extracted from dry electrodes in the arm are in agreement with the Nyquist equation. In the face, on the other hand, the measured noise values were higher than the values predicted by the Nyquist equation. In addition, we studied how different electrode properties affect performances, including electrode size, shape, and material properties. Significance. Altogether, the results presented here provide a basis for understanding dry electrode performances and substantiate their great potential in electro-physiological investigations.
Collective synchronization of dissipatively-coupled noise-activated processes
Authors: Chatzittofi M , Golestanian R , Agudo-Canalejo J
Published: August 2023

We study the stochastic dynamics of an arbitrary number of noise-activated cyclic processes, or oscillators, that are all coupled to each other via a dissipative coupling. The N coupled oscillators are described by N phase coordinates driven in a tilted washboard potential. At low N and strong coupling, we find synchronization as well as an enhancement in the average speed of the oscillators. In the large N regime, we show that the collective dynamics can be described through a mean-field theory, which predicts a great enhancement in the average speed. In fact, beyond a critical value of the coupling strength, noise activation becomes irrelevant and the dynamics switch to an effectively deterministic ‘running’ mode. Finally, we study the stochastic thermodynamics of the coupled oscillators, in particular their performance with regards to the thermodynamic uncertainty relation.
Semi-empirical Haken–Strobl model for molecular spin qubits
Authors: Aruachan Katy , Colón Yamil J , Aravena Daniel , Herrera Felipe
Published: August 2023

Understanding the physical processes that determine the relaxation T
1 and dephasing T
2 times of molecular spin qubits is critical for envisioned applications in quantum metrology and information processing. Recent spin-echo measurements of solid-state molecular spin qubits have stimulated the development of quantum mechanical models for predicting intrinsic qubit timescales using first-principles electronic structure methods. We develop an alternative semi-empirical approach to construct Redfield quantum master equations for molecular spin qubits using a stochastic Haken–Strobl theory for a central spin with fluctuating gyromagnetic tensor due to spin-lattice interaction and fluctuating local magnetic field due to interactions with lattice spins. Using two vanadium-based spin qubits as case studies, we compute qubit population and decoherence times as a function of temperature and magnetic field, using a bath spectral density parametrized with a small number of T
1 measurements. The theory quantitatively agrees with experimental data over a range of conditions beyond those used to parameterize the model, demonstrating the generalization potential of the method. The ability of the model to describe the temperature dependence of the ratio

T
2

/

T
1

is discussed and possible applications for designing novel molecule-based quantum magnetometers are suggested.