bluuebunny/crossref_metadata_2025 huggingface dataset:
Citation beneficiaries of discipline-specific mega-journals: who and how much
Authors: Li Jing , Long Qiushuang , Lu Xiaoli , Wu Dengsheng
Published: August 2023

The emergence of mega-journals (MJs) has influenced scholarly communication. One concrete manifestation of this impact is that more citations have been generated. Citations are the foundation of many evaluation metrics to assess the scientific impact of journals, disciplines, and regions. We focused on searching for citation beneficiaries and quantifying the relative benefit at the journal, discipline and region levels. More specifically, we examined the distribution and contribution to citation-based metrics of citations generated by the five discipline-specific mega-journals (DSMJs) categorized as Environmental Sciences (ES) on Web of Science (WoS) from Clarivate Analytics in 2021: Sustainability, International Journal of Environmental Research and Public Health, Environmental Science and Pollution Research, Journal of Cleaner Production and Science of the Total Environment. Analysis of the distribution of citing data of the five DSMJs shows a pattern with wide coverage but skewness by region and the WoS category; that is, papers in the five DSMJs contributed 26.66% of their citations in 2021 to Mainland China and 22.48% to the ES. Moreover, 15 journals within the ES had their JIFs boosted by more than 20%, benefitting from the high citing rates of the five DSMJs. More importantly, the analysis provides clear evidence that DSMJs can contribute to JIF scores throughout a discipline through their volume of references. Overall, DSMJs can widely impact scholarly evaluation because they contribute citation benefits and improve the evaluation index performance of different scientific entities at different levels. Considering the important application of citation indicators in the academic evaluation system and the increase in citations, it is important to reconsider the real research impact that citations can reflect.
Roadmap on ferroelectric hafnia- and zirconia-based materials and devices
Authors: Silva José P. B. , Alcala Ruben , Avci Uygar E. , Barrett Nick , Bégon-Lours Laura , Borg Mattias , Byun Seungyong , Chang Sou-Chi , Cheong Sang-Wook , Choe Duk-Hyun , Coignus Jean , Deshpande Veeresh , Dimoulas Athanasios , Dubourdieu Catherine , Fina Ignasi , Funakubo Hiroshi , Grenouillet Laurent , Gruverman Alexei , Heo Jinseong , Hoffmann Michael , Hsain H. Alex , Huang Fei-Ting , Hwang Cheol Seong , Íñiguez Jorge , Jones Jacob L. , Karpov Ilya V. , Kersch Alfred , Kwon Taegyu , Lancaster Suzanne , Lederer Maximilian , Lee Younghwan , Lomenzo Patrick D. , Martin Lane W. , Martin Simon , Migita Shinji , Mikolajick Thomas , Noheda Beatriz , Park Min Hyuk , Rabe Karin M. , Salahuddin Sayeef , Sánchez Florencio , Seidel Konrad , Shimizu Takao , Shiraishi Takahisa , Slesazeck Stefan , Toriumi Akira , Uchida Hiroshi , Vilquin Bertrand , Xu Xianghan , Ye Kun Hee , Schroeder Uwe
Published: August 2023

Ferroelectric hafnium and zirconium oxides have undergone rapid scientific development over the last decade, pushing them to the forefront of ultralow-power electronic systems. Maximizing the potential application in memory devices or supercapacitors of these materials requires a combined effort by the scientific community to address technical limitations, which still hinder their application. Besides their favorable intrinsic material properties, HfO2–ZrO2 materials face challenges regarding their endurance, retention, wake-up effect, and high switching voltages. In this Roadmap, we intend to combine the expertise of chemistry, physics, material, and device engineers from leading experts in the ferroelectrics research community to set the direction of travel for these binary ferroelectric oxides. Here, we present a comprehensive overview of the current state of the art and offer readers an informed perspective of where this field is heading, what challenges need to be addressed, and possible applications and prospects for further development.
Potential development and electron energy confinement in an expanding magnetic field divertor geometry
Authors: Gupta S. , Yushmanov P. , Barnes D. C. , Dettrick S. A. , Onofri M. , Tajima T. , Binderbauer M. ,   TAE Team
Published: August 2023

The formation of electrostatic potential in an expanding magnetic field divertor is numerically simulated using a kinetic model. As theoretically expected, the electrostatic potential is formed in the expanding magnetic field, which, in combination with the Debye potential near target walls, repels electrons back and balances electron and ion currents. Going beyond the existing theoretical description of the pre-sheath potential formation limited to the asymptotically low electron flow (ue≪vTe), we demonstrate the limit of applicability of asymptotic theory and study pre-sheath potential in practically important range of electron flow [0<Ie<2Isat, where Isat=en(Te+Ti)/mi is the ion saturation current]. Results of the asymptotic theory are fully reproduced at the low side of this range (Ie≪Isat), whereas at high electron current range Ie∼Isat, the pre-sheath potential substantially decreases. The formation of the pre-sheath potential minimizes the interaction of plasma electrons with the material walls and reduces the Debye sheath potential. Reducing the Debye potential forms favorable conditions for eliminating arcing and cold electron emission from the walls. In these favorable conditions, electron thermal losses at the wall could be reduced to minimal theoretical limit of ∼5−8Te per lost ion.
Law of large numbers and central limit theorem for ergodic quantum processes
Authors: Pathirana Lubashan , Schenker Jeffrey
Published: August 2023

A discrete quantum process is represented by a sequence of quantum operations, which are completely positive maps that are not necessarily trace preserving. We consider quantum processes that are obtained by repeated iterations of a quantum operation with noise. Such ergodic quantum processes generalize independent quantum processes. An ergodic theorem describing convergence to equilibrium for a general class of such processes has been recently obtained by Movassagh and Schenker. Under irreducibility and mixing conditions, we obtain a central limit type theorem describing fluctuations around the ergodic limit.
On linked modules over the super-Yangian of the superalgebra Q(1)
Authors: Poletaeva Elena
Published: August 2023

Let Q(n) be the queer Lie superalgebra. We determine conditions under which two one-dimensional modules over the super-Yangian of Q(1) can be extended nontrivially, and thus belong to the same block of the subcategory of finite-dimensional YQ(1)-modules admitting generalized central character χ = 0. We use these results to determine conditions under which two one-dimensional modules over the finite W-algebra for Q(n) can be extended nontrivially. We describe blocks in the category of finite-dimensional modules over the finite W-algebra for Q(2). In certain cases, we determine conditions under which two simple finite-dimensional YQ(1)-modules admitting central character χ ≠ 0 can be extended nontrivially and propose a conjecture in the general case.
Integration of a high finesse cryogenic build-up cavity with an ion trap
Authors: Wipfli Oliver , Passagem Henry Fernandes , Fischer Christoph , Grau Matt , Home Jonathan P.
Published: August 2023

We report on the realization of a hemispherical optical cavity with a finesse of F = 13 000 and sustaining inter-cavity powers of 10 kW, which we operate in a closed-cycle cryostat vacuum system close to 4 K. This was designed and built with an integrated radio-frequency Paul trap in order to combine optical and radio-frequency trapping. The cavity provides a power build-up factor of 2300. We describe a number of aspects of the system's design and operation, including low-vibration mounting and locking and thermal effects at high powers. Thermal self-locking in the high intracavity power regime was observed to enhance passive stability below 1 kHz. Observations made over repeated cool-downs over the course of a year show a repeatable shift between the ion trap center and the cavity mode.
Theory of singlet fission in carotenoid dimers
Authors: Barford William , Chambers Cameron A.
Published: August 2023

We develop a theory of singlet fission in carotenoid dimers. Following photoexcitation of the “bright” state (i.e., a singlet electron–hole pair) in a single carotenoid, the first step in the singlet fission process is ultrafast intramolecular conversion into the highly correlated “dark” (or 2Ag) state. This state has both entangled singlet triplet-pair and charge-transfer character. Our theory is predicated on the assumption that it is the singlet triplet-pair component of the “dark” state that undergoes bimolecular singlet fission. We use valence bond theory to develop a minimal two-chain model of the triplet-pair states. The single and double chain triplet-pair spectra are described, as this helps explain the dynamics and the equilibrated populations. We simulate the dynamics of the initial entangled pair state using the quantum Liouville equation, including both spin-conserving and spin-nonconserving dephasing processes. By computing the intrachain and interchain singlet, triplet, and quintet triplet-pair populations, we show that singlet fission critically depends on the interchain coupling and the driving potential (that determines endothermic vs exothermic fission).
Second harmonic generation in centrosymmetric multilayered structures: Theoretical approach for nonlinear boundary conditions
Authors: Obeid B. , Ionica I. , Vitrant G. , Damianos D. , Bastard L.
Published: August 2023

Second harmonic generation (SHG) is used to characterize the interfaces of centrosymmetric materials typically used in microelectronic/optoelectronic devices. For such applications, the materials are actually multi-layer stacks, and in this case, the SHG can be difficult to interpret and model. This paper presents the theory of the second harmonic light generated from multilayer structures. The focus is on describing the nonlinear boundary conditions at the interfaces between two different materials, taking into account the distinct contributions of bulk and interface regions. Using these conditions, it is possible to calculate the second harmonic signal from any stack of materials. In this paper, we address stacks containing silicon (100) because it is a material with numerous applications. The nonlinear polarization expressions of the surface and bulk of Si(100), according to Sipe et al. [Phys. Rev. B 35, 1129 (1987)], were integrated into nonlinear boundary conditions in order to determine transmitted and reflected second harmonic waves. An analytical validation was performed on the simple case of an air–silicon interface. For multilayered stacks, the model was compared with experimental results obtained on samples corresponding to pragmatic substrates widely used in microelectronic and optoelectronic applications.
PANNA 2.0: Efficient neural network interatomic potentials and new architectures
Authors: Pellegrini Franco , Lot Ruggero , Shaidu Yusuf , Küçükbenli Emine
Published: August 2023

We present the latest release of PANNA 2.0 (Properties from Artificial Neural Network Architectures), a code for the generation of neural network interatomic potentials based on local atomic descriptors and multilayer perceptrons. Built on a new back end, this new release of PANNA features improved tools for customizing and monitoring network training, better graphics processing unit support including a fast descriptor calculator, new plugins for external codes, and a new architecture for the inclusion of long-range electrostatic interactions through a variational charge equilibration scheme. We present an overview of the main features of the new code, and several benchmarks comparing the accuracy of PANNA models to the state of the art, on commonly used benchmarks as well as richer datasets.
A sharp interface approach for wetting dynamics of coated droplets and soft particles
Authors: Pelusi F. , Guglietta F. , Sega M. , Aouane O. , Harting J.
Published: August 2023

The wetting dynamics of liquid particles, from coated droplets to soft capsules, holds significant technological interest. Motivated by the need to simulate liquid metal droplets with an oxidized surface layer, in this work, we introduce a computational scheme that allows us to simulate droplet dynamics with general surface properties and model different levels of interface stiffness, also describing cases that are intermediate between pure droplets and capsules. Our approach is based on a combination of the immersed boundary and the lattice Boltzmann methods. Here, we validate our approach against the theoretical predictions in the context of shear flow and static wetting properties, and we show its effectiveness in accessing the wetting dynamics, exploring the ability of the scheme to address a broad phenomenology.
Thermodynamic analysis of oxide vapor phase epitaxy of GaN
Authors: Sakurai Yuki , Usami Shigeyoshi , Imanishi Masayuki , Sumi Tomoaki , Takino Junichi , Okayama Yoshio , Maruyama Mihoko , Yoshimura Masashi , Hata Masahiko , Isemura Masashi , Mori Yusuke
Published: August 2023

We report on a thermodynamic analysis of oxide vapor phase epitaxy (OVPE) of GaN. We first calculate equilibrium partial pressures of gases for the initial partial pressures of Ga2O, NH3, and H2 as well as the growth temperature. To estimate the growth rate of a GaN crystal, we then define the supersaturation amount determined by the equilibrium and initial partial pressures. In the calculation, the growth rate is significantly influenced by the initial partial pressures of Ga2O and NH3, while it is almost independent of the initial partial pressure of H2 and the growth temperature. Subsequently, we experimentally grow GaN crystals under same conditions as in the thermodynamic analysis. In the range of conditions in this work, the experimental growth rates are nearly consistent with the growth rates predicted by the thermodynamic analysis for all experimental parameters. Thus, the results showed that a high value of the supersaturation amount is advantageous for high-speed growth. Furthermore, we define the supersaturation ratio and investigate the correlation between this parameter and the surface coverage of the polycrystal. The surface coverage of the polycrystal is confirmed to roughly decrease as the value of the supersaturation ratio decreases. Thus, the results showed that a low value of the supersaturation ratio is advantageous for polycrystal-free growth. Finally, we use the thermodynamic analysis to explore the optimal conditions for high-speed and polycrystal-free growth. This revealed that the optimal OVPE growth conditions are both a high partial pressure of Ga2O and a low partial pressure of NH3.
Novel computational fluid dynamics-finite element analysis solution for the study of flexible material wave energy converters
Authors: Huang Yang , Xiao Qing , Idarraga Guillermo , Yang Liu , Dai Saishuai , Abad Farhad , Brennan Feargal , Lotfian Saeid
Published: August 2023

The use of flexible materials for primary mover and power takeoff of wave energy converters (WECs) has attracted considerable attention in recent years, owing to their potential to enhance the reliability, survivability, and wave energy conversion efficiency. Although some reduced order models have been used to study the fluid–structure interaction (FSI) responses of flexible wave energy converters (fWECs), they are somehow inappropriate due to their limited accuracy and applicability span. To gain a deeper understanding of the physical mechanisms in fWECs, a high-fidelity approach is required. In this work, we build up a fluid–structure interaction analysis framework based on computational fluid dynamics and a finite element analysis method. The incompressible viscous flow is resolved by solving three-dimensional unsteady Navier–Stokes equations with a finite volume approach. The structure dynamics are solved by a finite element method, taking the nonlinear behavior of flexible material into consideration. A strong coupling strategy is utilized to enhance the numerical stability and convergence of the iterative process. We demonstrate the present FSI tool is able to provide rich flow field information and structural response details, such as the velocity, pressure, and structural stress distribution. This is illustrated through several case studies, including two types of fWECs. The unsteady wave–structure-interaction and the associated nonlinear phenomena are also accurately captured by this tool.
Intermittency at Earth's bow shock: Measures of turbulence in quasi-parallel and quasi-perpendicular shocks
Authors: Plank J. , Gingell I. L.
Published: August 2023

Turbulent plasmas such as the solar wind and magnetosheath exhibit an energy cascade that is present across a broad range of scales, from the stirring scale at which energy is injected, down to the smallest scales where energy is dissipated through processes such as reconnection and wave–particle interactions. Recent observations of Earth's bow shock reveal a disordered or turbulent transition region exhibiting features of turbulent dissipation, like reconnecting current sheets. We used observations from magnetospheric multiscale (MMS) over four separate bow shock crossings of varying shock normal angle to characterize turbulence in the shock transition region and how it evolves toward the magnetosheath. These cases studies have been chosen to ensure validity of Taylor's hypothesis, which we discuss in depth. We observe the magnetic spectrum evolving by fitting power laws over many short intervals, finding that the power-law index in the shock transition region is separable from the upstream and downstream plasma, for both quasi-perpendicular and quasi-parallel shocks. Across the shock, we see a change in the breakpoint location between inertial and ion power-law slopes. We also observe the evolution of scale-independent kurtosis of magnetic fluctuations across the shock, finding a reduction of high kurtosis intervals downstream of the shock. Finally, we adapt a method for calculating correlation length to include a high-pass filter, allowing estimates for changes in correlation length across the shock. In a quasi-perpendicular shock, we find the correlation length to be significantly smaller in the magnetosheath than in solar wind; however, the opposite can occur for quasi-parallel shocks.
The effect of axisymmetric confinement on propulsion of a three-sphere microswimmer
Authors: Gürbüz Ali , Lemus Andrew , Demir Ebru , Pak On Shun , Daddi-Moussa-Ider Abdallah
Published: August 2023

Swimming at the microscale has recently garnered substantial attention due to the fundamental biological significance of swimming microorganisms and the wide range of biomedical applications for artificial microswimmers. These microswimmers invariably find themselves surrounded by different confining boundaries, which can impact their locomotion in significant and diverse ways. In this work, we employ a widely used three-sphere swimmer model to investigate the effect of confinement on swimming at low Reynolds numbers. We conduct theoretical analysis via the point-particle approximation and numerical simulations based on the finite element method to examine the motion of the swimmer along the centerline in a capillary tube. The axisymmetric configuration reduces the motion to one-dimensional movement, which allows us to quantify how the degree of confinement affects the propulsion speed in a simple manner. Our results show that the confinement does not significantly affect the propulsion speed until the ratio of the radius of the tube to the radius of the sphere is in the range of O(1)−O(10), where the swimmer undergoes substantial reduction in its propulsion speed as the radius of the tube decreases. We provide some physical insights into how reduced hydrodynamic interactions between moving spheres under confinement may hinder the propulsion of the three-sphere swimmer. We also remark that the reduced propulsion performance stands in stark contrast to the enhanced helical propulsion observed in a capillary tube, highlighting how the manifestation of confinement effects can vary qualitatively depending on the propulsion mechanisms employed by the swimmers.
Excellent passivation of germanium surfaces by POx/Al2O3 stacks
Authors: Theeuwes Roel J. , Berghuis Wilhelmus J. H. , Macco Bart , Kessels Wilhelmus M. M.
Published: August 2023

Passivation of germanium surfaces is vital for the application of germanium in next-generation electronic and photonic devices. In this work, it is demonstrated that stacks of phosphorous oxide and aluminum oxide (POx/Al2O3) provide excellent and stable passivation of germanium surfaces, with state-of-the-art surface recombination velocities down to 8.9 cm/s. The POx/Al2O3 stack also exhibits positive fixed charge on germanium, which makes it especially suited for passivation of highly doped n-type germanium surfaces. The chemical passivation mechanism is found to be related to the passivation of defects by hydrogen, which is mobilized by the formation of AlPO4 upon annealing. Furthermore, the GeOx interlayer is removed due to a kind of “self-cleaning” process during the deposition of POx/Al2O3 stacks on germanium, which may in part explain the excellent passivation quality. This self-cleaning of the interface may also allow simplified device fabrication workflows, as pretreatments may be omitted.
Kerr-fully diving into the abyss: analytic solutions to plunging geodesics in Kerr
Authors: Dyson Conor , van de Meent Maarten
Published: August 2023

We present closed-form solutions for the generic class of plunging geodesics in the extended Kerr spacetime using Boyer–Lindquist coordinates. We also specialise to the case of test particles plunging from the innermost precessing stable circular orbit (ISSO) and unstable spherical orbits. We find these solutions in the form of elementary and Jacobi elliptic functions parameterised by Mino time. In particular, we demonstrate that solutions for the ISSO case can be determined almost entirely in terms of elementary functions, depending only on the spin parameter of the black hole and the radius of the ISSO. Furthermore, we introduce a new equation that characterises the radial inflow from the ISSO to the horizon, taking into account the inclination. For ease of application, our solutions have been implemented in a Mathematica package that is available as part of theKerrGeodesicspackage in the Black Hole Perturbation Toolkit.
Analysis and elimination of translation disturbance for patch effect measurement with a torsion pendulum
Authors: Li Ke , Song Chi , Zheng Yunsheng , Hu Ming , Luo Pengshun , Yin Hang , Zhou Zebing
Published: August 2023

Patch effect on conductive surfaces is one of the critical noise sources in many scientific experiments like space gravity programs and gravitational wave detection missions. A high-precision probe-torsion instrument has been developed on ground for measuring patch effect. However, the translation mode of the probe resulting from the environmental disturbance will inevitably affect the measurement in the concerned torsion degree of freedom. In this paper, combining the theoretical analysis as well as the confirmatory experiment, the method based on data analysis is adopted to eliminate the translation effect, finally realizing the best surface potential resolution level of 20 µV Hz

−
1

/

2

.
The inverse Rytov series for diffuse optical tomography
Authors: Machida Manabu
Published: August 2023

The Rytov approximation is known in near-infrared spectroscopy including diffuse optical tomography. In diffuse optical tomography, the Rytov approximation often gives better reconstructed images than the Born approximation. Although related inverse problems are nonlinear, the Rytov approximation is almost always accompanied by the linearization of nonlinear inverse problems. In this paper, we will develop nonlinear reconstruction with the inverse Rytov series. By this, linearization is not necessary and higher order terms in the Rytov series can be used for reconstruction. The convergence and stability are discussed. We find that the inverse Rytov series has a recursive structure similar to the inverse Born series.
Generalized Bayes approach to inverse problems with model misspecification
Authors: Baek Youngsoo , Aquino Wilkins , Mukherjee Sayan
Published: August 2023

We propose a general framework for obtaining probabilistic solutions to PDE-based inverse problems. Bayesian methods are attractive for uncertainty quantification but assume knowledge of the likelihood model or data generation process. This assumption is difficult to justify in many inverse problems, where the specification of the data generation process is not obvious. We adopt a Gibbs posterior framework that directly posits a regularized variational problem on the space of probability distributions of the parameter. We propose a novel model comparison framework that evaluates the optimality of a given loss based on its ‘predictive performance’. We provide cross-validation procedures to calibrate the regularization parameter of the variational objective and compare multiple loss functions. Some novel theoretical properties of Gibbs posteriors are also presented. We illustrate the utility of our framework via a simulated example, motivated by dispersion-based wave models used to characterize arterial vessels in ultrasound vibrometry.
Steering photoassociation of cold 85Rb atoms by two-color slowly-turned-on and rapidly-turned-off laser pulses
Authors: Zhang Rong , Hu Jin-Wei , Wang Gao-Ren , Fu Bina , Han Yong-Chang
Published: August 2023

Photoassociation (PA) of 85Rb atoms from the ground

X

1

Σ

g

+

state to the excited

A

1

Σ

g

+

and

b

3

Π

u

states by two-color laser pulses at 100

μ

K

×

k

B

is investigated by using quantum wavepacket method. Two pulses with detunings δ
1 and δ
2 varying from −1.0 to 1. cm−1 are taken into account. The specific case

δ

1

=
−

δ

2

is generalized to the condition of arbitrary combination of δ
1 and δ
2 for both the Gaussian-pulse field and the slowly-turned-on and rapidly-turned-off (STRT) field. It is found that the introduce of the detunings in the two pluses can enhance the asymmetry of the time profile and broaden the linewidth of the laser field. The two factors can further enhance the PA probability for both resonant and nonresonant regions. Compared to the Gaussian field, the STRT field which is even more asymmetric in time profile and more broaden in linewidth can significantly enhance the PA probability, with the nonresonant transition dominating the PA process. It can be expected that once the two detunings are both positive, which is a relatively loose restriction for coherent control, a considerable PA probability can be obtained in a two-color STRT field.
Inequalities for exchange Slater integrals
Authors: Pain Jean-Christophe
Published: August 2023

The variations of exchange Slater integrals with respect to their order k are not well known. While direct Slater integrals Fk
are positive and decreasing when the order increases, this is not stricto sensu the case for exchange integrals Gk
. However, two inequalities were published by Racah in his seminal article ‘Theory of complex spectra. II’. In this article, we show that the technique used by Racah can be generalized, albeit with cumbersome calculations, to derive further relations, and provide two of them, involving respectively three and four exchange integrals. Such relations can prove useful to detect regularities in complex atomic spectra and classify energy levels.
Additive engineering by tetrabutylammonium iodide for antimony selenosulfide solar cells
Authors: Baron-Jaimes Agustin , Ortiz-Soto Karla Arlen , Millán-Franco Mario Alejandro , Miranda Gamboa Ramses Alejandro , Rincón Marina Elizabeth , Jaramillo-Quintero Oscar Andrés
Published: August 2023

Antimony selenosulfide (Sb2(S,Se)3) solar cells have attracted great attention due to their tunable optoelectronic properties, ease of preparation and low toxicity. However, the harmful intrinsic defect density and internal nonradiative recombination of Sb2(S,Se)3 hinder its practical usage. In this work, a facile additive approach is explored to modify the Sb2(S,Se)3 solar cell efficiency by using tetrabutylammonium iodide (TBAI). After applying a certain amount of TBAI into the Sb2(S,Se)3 precursor solution, the film surface presents lower cracks and roughness than that of the pristine sample. It also increases its hydrophobicity and n-type nature revealed by contact angle and work function measurements. Moreover, the incorporation of TBAI during the formation of the Sb2(S,Se)3 layer improves the quality of the film effectively suppresses its defect trap density, which manifests as a reduction in charge recombination and enhancement of the power conversion efficiency (PCE) when incorporated into solar cells. The fabricated device with 0.62 mol% of TBAI shows the highest PCE (8.87%) and high stability without encapsulation, maintaining about 91% of its initial efficiency after 60 d in air. The results provide a feasible strategy to the ongoing progress of reliable Sb2(S,Se)3 devices.
Redistribution of radionuclides in wall material and its effects on the room dose rate
Authors: Fohlmeister Jens , Hoffmann Bernd
Published: August 2023

Here we investigate the annual effective dose rate obtained from gamma radiation emitted from radionuclides in construction materials in a model room with fixed dimensions. The dose rate is calculated on the whole room area at half the room height. We focus our analyses on a comparison of the annual effective dose rate between the room centre and the room average at half the room height and provide wall-wise quadratic index equations for both. We find that the annual effective dose rate based on the room average is larger than for the room centre due to increased annual effective dose rates for positions in the room closer to the walls. Furthermore, we evaluate the annual effective dose rate under a non-equal distribution of radionuclides in the three wall types (floor and ceiling, long walls, short walls). When considering the room average of the annual effective dose rate, our analysis indicates that it appears advantageous to use construction materials with a higher radionuclide activity concentration for floor and ceiling and the material with a lower radionuclide content for long and short walls, if there is a choice in the construction process.
Theoretical model of magnetoacoustic emission considering the microstructure of ferromagnetic material
Authors: Zhang Hongliang , Jiao Jingpin , Wu Bin , He Cunfu
Published: August 2023

Magnetoacoustic emission (MAE) holds great promise for evaluating the mechanical properties of ferromagnetic materials. To refine the problems of the current theoretical and numerical models of MAE, a theoretical MAE model that considers the microscopic dependence of the hysteresis properties is proposed in this paper. The microstructure (dislocation density and grain size) and the correlation of MAE jumps are considered and incorporated into the model. Then, the influences of magnetization parameters and microstructure parameters on the envelope of the MAE signal are analyzed by the proposed theoretical model. The proposed theoretical model is then fully evaluated by simulations and experiments. The MAE experiments are conducted on ferromagnetic specimens with different hardnesses, and the MAE signals with different hardnesses are simulated by inverting the basic parameters of the MAE model with the genetic algorithm. Further, the crucial hysteresis parameters of the specimens are calculated using the results of microscopic measurements and the calculated parameters agree well with inversion results from experimental signals. The results demonstrate that the proposed theoretical model is valid for the MAE signal simulation. The trends of different hardnesses can be predicted by the MAE simulation signals. Moreover, the model can be used for theoretical analysis of the microscopic dependence of the MAE signal.
Modeling of heterogeneous site energy distributions in precipitate nucleation
Authors: Kahlenberg Robert , Falkinger Georg , Milkereit Benjamin , Kozeschnik Ernst
Published: August 2023

The simulation of heat changes resulting from phase transitions can help to interpret differential scanning calorimetry (DSC) measurements, e.g. of metallic alloy systems in which multiple reactions overlap during non-isothermal heat treatments. So far, simulated DSC curves mostly exhibit sharp reaction peaks as commonly just one mean energy value for a certain type of nucleation site is assumed. This work proposes an efficient model for treating heterogeneous nucleation site energy variations within the framework of classical nucleation theory (CNT). The site energies are assumed to vary according to a Rayleigh distribution and a scaling function. The effect on the nucleation behavior of precipitates is studied. A consideration of the distribution of heterogeneous site energies has the potential to significantly smoothen the numerical treatment of precipitation processes compared to the non-distributed case. The comparison to previously published simulations of DSC curves during the cooling of an AA6005 aluminum alloy demonstrates the advantages of this extension, especially for slow cooling rates.
Development of hybrid bioactive nanofibers composed of star Poly(lactic acid) and gelatin by sol–gel crosslinking during the electrospinning process
Authors: Belabbes Karima , Simon Matthieu , Leon-Valdivieso Christopher Yusef , Massonié Mathilde , Bethry Audrey , Subra Gilles , Garric Xavier , Pinese Coline
Published: August 2023

The design of a biomimetic scaffold is a major challenge in tissue engineering to promote tissue reconstruction. The use of synthetic polymer nanofibers is widely described as they provide biocompatible matrices whose topography mimics natural extracellular matrix (ECM). To closely match the biochemical composition of the ECM, bioactive molecules such as gelatin are added to the nanofibers to enhance cell adhesion and proliferation. To overcome the rapid solubilization of gelatin in biological fluids and to allow a lasting biological effect, the covalent crosslinking of this macromolecule in the network is crucial. The sol–gel route offers the possibility of gentle crosslinking during shaping but is rarely combined with electrospinning. In this study, we present the creation of Poly(lactic acid)/Gelatin hybrid nanofibers by sol–gel route during electrospinning. To enable sol–gel crosslinking, we synthesized star-shaped PLA and functionalized it with silane groups; then we functionalized gelatin with the same groups for their subsequent reaction with the polymer and thus the creation of the hybrid nanonetwork. We evaluated the impact of the presence of gelatin in Poly(lactic acid)/Gelatin hybrid nanofibers at different percentages on the mechanical properties, nanonetwork crosslinking, degradation and biological properties of the hybrid nanofibers. The addition of gelatin modulated nanonetwork crosslinking that impacted the stiffness of the nanofibers, resulting in softer materials for the cells. Moreover, these hybrid nanofibers also showed a significant improvement in fibroblast proliferation and present a degradation rate suitable for tissue reconstruction. Finally, the bioactive hybrid nanofibers possess versatile properties, interesting for various potential applications in tissue reconstruction.
Towards high photoresponse of perovskite nanowire/copper phthalocyanine heterostructured photodetector
Authors: Lu Chengyu , Dai Qinyong , Tang Chenyu , Wang Xinyu , Xu Sunan , Sun Lei , Peng Yingquan , Lv Wenli
Published: August 2023

One-dimensional nanowire structures composed of perovskite are widely recognized for their exceptional optoelectronic performance and mechanical properties, making them a popular area of investigation in photodetection research. In this work, a perovskite nanowire/copper phthalocyanine heterojunction-based photodetector was fabricated, which exhibits high photoresponse in the visible-near-infrared region. The incorporation of a heterojunction significantly enhanced the photoelectric performance. Specifically, the photoresponsivity and external quantum efficiency of the nanowire-based device were elevated from 58.5 A W−1 and 1.35 × 104% to 84.5 A W−1 and 1.97 × 104% at 532 nm, respectively. The enhanced photoresponse of the heterojunction device can be attributed to the unique microstructure of nanowire arrays. The wrapping of the nanowires by copper phthalocyanine forms heterojunctions with a larger dissociation area, which facilitated exciton dissociation and enhanced device performance. This work provides a promising example for optimizing the performance of nanowire devices.
Dual-branch hybrid encoding embedded network for histopathology image classification
Authors: Li Mingshuai , Hu Zhiqiu , Qiu Song , Zhou Chenhao , Weng Jialei , Dong Qiongzhu , Sheng Xia , Ren Ning , Zhou Mei
Published: August 2023

Objective. Learning-based histopathology image (HI) classification methods serve as important tools for auxiliary diagnosis in the prognosis stage. However, most existing methods are focus on a single target cancer due to inter-domain differences among different cancer types, limiting their applicability to different cancer types. To overcome these limitations, this paper presents a high-performance HI classification method that aims to address inter-domain differences and provide an improved solution for reliable and practical HI classification. Approach. Firstly, we collect a high-quality hepatocellular carcinoma (HCC) dataset with enough data to verify the stability and practicability of the method. Secondly, a novel dual-branch hybrid encoding embedded network is proposed, which integrates the feature extraction capabilities of convolutional neural network and Transformer. This well-designed structure enables the network to extract diverse features while minimizing redundancy from a single complex network. Lastly, we develop a salient area constraint loss function tailored to the unique characteristics of HIs to address inter-domain differences and enhance the robustness and universality of the methods. Main results. Extensive experiments have conducted on the proposed HCC dataset and two other publicly available datasets. The proposed method demonstrates outstanding performance with an impressive accuracy of 99.09% on the HCC dataset and achieves state-of-the-art results on the other two public datasets. These remarkable outcomes underscore the superior performance and versatility of our approach in multiple HI classification. Significance. The advancements presented in this study contribute to the field of HI analysis by providing a reliable and practical solution for multiple cancer classification, potentially improving diagnostic accuracy and patient outcomes. Our code is available at https://github.com/lms-design/DHEE-net.
Context-aware dynamic filtering network for confocal laser endomicroscopy image denoising
Authors: Zhou Jingjun , Dong Xiangjiang , Liu Qian
Published: August 2023

Objective. As an emerging diagnosis technology for gastrointestinal diseases, confocal laser endomicroscopy (CLE) is limited by the physical structure of the fiber bundle, leading to the inevitable production of various forms of noise during the imaging process. However, existing denoising methods based on hand-crafted features inefficiently deal with realistic noise in CLE images. To alleviate this challenge, we proposed context-aware kernel estimation and multi-scale dynamic fusion modules to remove realistic noise in CLE images, including multiplicative and additive white noise. Approach. Specifically, a realistic noise statistics model with random noise specific to CLE data is constructed and further used to develop a self-supervised denoised model without the participation of clean images. Secondly, context-aware kernel estimation, which improves the representation of features by similar learnable region weights, addresses the problem of the non-uniform distribution of noises in CLE images and proposes a lightweight denoised model (CLENet). Thirdly, we have developed a multi-scale dynamic fusion module that decouples and recalibrates features, providing a precise and contextually enriched representation of features. Finally, we integrated two developed modules into a U-shaped backbone to build an efficient denoising network named U-CLENet. Main Results. Both proposed methods achieve comparable or better performance with low computational complexity on two gastrointestinal disease CLE image datasets using the same training benchmark. Significance. The proposed approaches improve the visual quality of unclear CLE images for various stages of tumor development, helping to reduce the rate of misdiagnosis in clinical decision-making and achieve computer graphics-assisted diagnosis.
Regularized reconstruction based on joint smoothly clipped absolute deviation regularization and graph manifold learning for fluorescence molecular tomography
Authors: Zhang Jun , Zhang Gege , Chen Yi , Li Kang , Zhao Fengjun , Yi Huangjian , Su Linzhi , Cao 曹 Xin 欣
Published: August 2023

Objective. Fluorescence molecular tomography (FMT) is an optical imaging modality that provides high sensitivity and low cost, which can offer the three-dimensional distribution of biomarkers by detecting the fluorescently labeled probe noninvasively. In the field of preclinical cancer diagnosis and treatment, FMT has gained significant traction. Nonetheless, the current FMT reconstruction results suffer from unsatisfactory morphology and location accuracy of the fluorescence distribution, primarily due to the light scattering effect and the ill-posed nature of the inverse problem. Approach. To address these challenges, a regularized reconstruction method based on joint smoothly clipped absolute deviation regularization and graph manifold learning (SCAD-GML) for FMT is presented in this paper. The SCAD-GML approach combines the sparsity of the fluorescent sources with the latent manifold structure of fluorescent source distribution to achieve more accurate and sparse reconstruction results. To obtain the reconstruction results efficiently, the non-convex gradient descent iterative method is employed to solve the established objective function. To assess the performance of the proposed SCAD-GML method, a comprehensive evaluation is conducted through numerical simulation experiments as well as in vivo experiments. Main results. The results demonstrate that the SCAD-GML method outperforms other methods in terms of both location and shape recovery of fluorescence biomarkers distribution. Siginificance. These findings indicate that the SCAD-GML method has the potential to advance the application of FMT in in vivo biological research.
A soft tactile sensing array with high sensitivity based on MWCNTs-PDMS composite of hierarchically porous structure
Authors: Yu Jianping , Yao Shengjie , Lin Huan , Zhang Yuanxiang , Jiang Xiaoliang , Ghaffar Abdul , Li Xin , Yao Zhehe
Published: August 2023

The advancement of wearable tactile sensors that involves with high sensitivity under ultra-low pressures is crucial for varieties of human-machine interactive applications, like smart phones, healthcare monitoring, and electronic skins. Here in this paper, a soft capacitive tactile sensing array is introduced based on hierarchically porous multi-walled carbon nanotubes (MWCNTs)-polydimethylsiloxane composite, which leads to sensitivity improvement attributing to a synergistic effect of the hierarchically porous elastomer and conductive MWCNTs supplements. The proposed device exhibits superior pressure-sensing performances, with high sensitivity (3.58 kPa−1) under small mechanical stimuli (<80 Pa), broad measuring range (0–265 kPa), fast response time (<45 ms), good repeatability, minimum limit of detection (<10 Pa), as well as low-hysteresis, allowing efficient sensing of pressure from all types of sources, from vulnerable signals such as human breathing, artery and venous pulses, and soft human finger touch to possible brutal variations such as sudden change of object weight or prompt collide. Moreover, extensive body attached experiments confirm that the soft tactile sensing array is fully human compatible and capable for a variety of human-machine interfaces and health monitoring applications.
State carving in a chirally-coupled atom-nanophotonic cavity
Authors: Hiew W S , Jen H H
Published: August 2023

Coherent quantum control of multiqubit systems represents one of the challenging tasks in quantum science and quantum technology. Here we theoretically investigate the reflectivity spectrum in an atom-nanophotonic cavity with collective nonreciprocal couplings. In the strong-coupling regime with a high cooperativity, we theoretically predict distinct on-resonance spectral dips owing to destructive interferences of chiral couplings. Due to the well-separated multiple dips in the spectrum, a contrasted reflectivity suggests a new control knob over the desired entangled state preparation in the basis of coupled and uncoupled states from the atoms’ internal hyperfine ground states. We propose to utilize such atom-nanophotonic cavity to quantum engineer the atomic internal states via photon-mediated dipole–dipole interactions in the coupled state and the chirality of decay channels, where the atomic Bell state and W states for arbitrary number of atoms can be tailored and heralded by state carving in the single-photon reflection spectrum. Our results pave the way toward quantum engineering of multiqubit states and offer new opportunities for coherent and scalable multipartite entanglement transport in atoms coupled to nanophotonic devices.
Dual-mode switchable metasurface for multi-type OAM vortex beam generation and dual-band perfect absorption in terahertz band
Authors: Zhou Zihao , Qi Yunping , Zhang Baohe , Wen Yujiao , Wang Li , Wang Xiangxian
Published: August 2023

As metasurface technology is developing rapidly in the past decades, multi-operating mode and tunability are evolving into hot spots in its development. In this paper, we present a dual-operating mode metasurface consisting of vanadium dioxide (VO2). At room temperature (25 °C), it operates as a reflection mode. Eight metasurface unit cells with different reflection phases are designed, which can achieve 2π phase coverage in the frequency band of 0.4 THz-0.5 THz. Furthermore, by bringing encoded convolution and superposition theorems into the design of metasurface arrays, vertically incident circularly polarized (CP) waves can be transformed into single-beam, multi-beam, deflected and superimposed orbital angular momentum (OAM) vortex beams, respectively. On the other hand, at high temperature (68 °C), it operates as a dual-band terahertz absorber. It achieves near-perfect absorption at 1.71 THz and 1.87 THz with 99.9% and 98.9%, and also has polarization insensitivity. Therefore, the metasurface designed in this paper has promising applications in future terahertz communications, high-resolution imaging, and electromagnetic stealth.