bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sub-10 nm metal nanogaps with high SERS performance via a novel conformal coating process
Authors: Wang Yasi , Huang Shengchao , He Jianbo , Zhu Xupeng , Shi HuiMin 
Published: March 2023

Abstract
Metallic nanogaps enables inducing the strong coupling between neighboring metal structures, resulting in a great field enhancement in the gap. Therefore, it is crucial fundamental building blocks for nanoelectronics and nanophotonics. Moreover, the electromagnetic field enhancement of the tiny gap increases rapidly with the decrease of gaps size. Naturally, enables better device performance with higher field enhancements. However, as the size of nanogaps reduced to the sub-10 nm scale, the fabrication of metallic nanogaps faced with great challenges, including the decrease in uniformity, repeatability and stability of the fabricating process due to various manufacturing and physical constraints. Thus, how to further reduce the size of metal nanogaps for higher device performance has become a key issue in this field. In this work, we propose and demonstrate a novel approach to fabricate sub-10 nm metal nanogaps by coating a conformal ultrathin oxide film via atomic-layer deposition. The method can fabricate sub-10 nm gap in dense metal-nanostructure arrays with high stability, reliability and uniformity, which provides a reliable technical for the fabrication and application of high-performed metallic nanogap structures and devices.
Chiral-coupling-assisted refrigeration in trapped ions
Authors: Chen Chi-Chih , Wang Yi-Cheng , Wang Chun-Che , Jen H H 
Published: March 2023

Abstract
Trapped ions can be cooled close to their motional ground state, which is imperative in implementing quantum computation and quantum simulation. Here, we theoretically investigate the capability of light-mediated chiral couplings between ions to enable a superior cooling scheme exceeding the single-ion limit of sideband cooling. Under asymmetric driving, the target ion manifests the chiral-coupling-assisted refrigeration at the price of heating others, where its steady-state phonon occupation outperforms the lower bound set by a single ion. We further explore the optimal operation conditions for the refrigeration where a faster rate of cooling can still be sustained. Under an additional nonguided decay channel, a broader parameter regime emerges to support the superior cooling and carries over into the reciprocal coupling, suppressing the heating effect instead. Our results present a tunable resource of collective chiral couplings which can help surpass the bottleneck of the cooling procedure and open up new possibilities in applications of trapped-ion-based quantum computation and simulation.
Insights into selected 2D piezo Rashba semiconductors for self-powered flexible piezo spintronics: material to contact properties
Authors: IS Fathima , Mohanta Manish Kumar , Sarkar Abir De 
Published: March 2023

Abstract
The new paradigm in electronics consists in realizing the seamless integration of many properties latent in nanomaterials, such as mechanical flexibility, strong spin–orbit coupling (Rashba spin splitting—RSS), and piezoelectricity. Taking cues from the pointers given on 1D ZnO nanowires (ACS Nano 2018 12 1811–20), the concept can be extended to multifunctional two-dimensional (2D) materials, which can serve as an ideal platform in next-generation electronics such as self-powered flexible piezo-spintronic device. However, a microscopically clear understanding reachable from the state-of-the-art density functional theory-based approaches is a prerequisite to advancing this research domain. Atomic-scale insights gained from meticulously performed scientific computations can firmly anchor the growth of this important research field, and that is of undeniable relevance from scientific and technological outlooks. This article reviews the scientific advance in understanding 2D materials hosting all the essential properties, i.e. flexibility, piezoelectricity, and RSS. Important 2D semiconducting monolayers that deserve a special mention, include monolayers of buckled MgX (X = S, Se, Te), CdTe, ZnTe, Janus structures of transition metal trichalcogenides, Janus tellurene and 2D perovskites. van Der Waals multilayers are also built to design multifunctional materials via modulation of the stacking sequence and interlayer coupling between the constituent layers. External electric field, strain engineering and charge doping are perturbations mainly used to tune the spintronic properties. Finally, the contact properties of these monolayers are also crucial for their actual implementation in electronic devices. The nature of the contacts, Schottky/Ohmic, needs to be carefully examined first as it controls the device’s performance. In this regard, the rare occurrence of Ohmic contact in graphene/MgS van der Waals hetero bilayer has been presented in this review article.
The spin polarization of palladium on magneto-electric Cr2O3
Authors: Komesu Takashi , Echtenkamp Will , Binek Christian , Dowben Peter A 
Published: March 2023

Abstract
While induced spin polarization of a palladium (Pd) overlayer on antiferromagnetic and magneto-electric Cr2O3(0001) is possible because of the boundary polarization at the Cr2O3(0001), in the single domain state, the Pd thin film appears to be ferromagnetic on its own, likely as a result of strain. In the conduction band, we find the experimental evidence of ferromagnetic spin polarized in Pd thin films on a Cr2O3(0001) single crystal, especially in the thin limit, Pd thickness of around 1–4 nm. Indeed there is significant spin polarization in 10 Å thick Pd films on Cr2O3(0001) at 310 K, i.e. above the Néel temperature of bulk Cr2O3. While Cr2O3(0001) has surface moments that tend to align along the surface normal, for Pd on Cr2O3, the spin polarization contains an in-plane component. Strain in the Pd adlayer on Cr2O3(0001) appears correlated to the spin polarization measured in spin polarized inverse photoemission spectroscopy. Further evidence for magnetization of Pd on Cr2O3 is provided by measurement of the exchange bias fields in Cr2O3/Pd(buffer)/[Co/Pd]
n
exchange bias systems. The magnitude of the exchange bias field is, over a wide temperature range, virtually unaffected by the Pd thickness variation between 1 and 2 nm.
Imaging of intracerebral hemorrhage with adaptive genetic algorithm in brain electrical impedance tomography
Authors: Shi Yanyan , Liu Zhenkun , Fu Feng , Wang Meng , Lou Yajun , Zheng Shuo 
Published: March 2023

Abstract
Intracerebral hemorrhage refers to bleeding caused by the spontaneous rupture of blood vessels. Accurate diagnosis of hemorrhage is vital in the treatment of a patient. As a new medical imaging technique, electrical impedance tomography (EIT) is able to offer images of conductivity distribution variation caused by pathological change. However, image reconstruction of EIT suffers from the problem of serious ill-posedness. In particular, in brain imaging, irregular and multi-layered head structure together with the low conductivity of the skull further aggravate the problem. In order to address this problem, a new image-reconstruction method is proposed for imaging of hemorrhage in this work. With current solutions solving by a Tikhonov regularization method for the original conductivity distribution, the proposed method enhances the reconstruction quality by introducing an adaptive genetic algorithm. To test the performance of the proposed method, simulation work is conducted. A three-layer head model is established and an inclusion, which simulates hemorrhage, is placed at six different locations in the brain layer. Images reconstructed by the Tikhonov method, Newton–Raphson method and the traditional genetic algorithm are used for comparisons. Quantitative evaluation is also performed. The anti-noise performance of the proposed method is estimated by considering noise with differing signal-to-noise ratios. In addition to simulation, phantom experiments are carried out to further verify the performance of the proposed method. The results show that the proposed method performs well in the reconstruction of simulated intracerebral hemorrhage. With the proposed method, the inclusion can be more accurately reconstructed and the background is much clearer than the other three traditional methods.
A probabilistic deep learning model of inter-fraction anatomical variations in radiotherapy
Authors: Pastor-Serrano Oscar , Habraken Steven , Hoogeman Mischa , Lathouwers Danny , Schaart Dennis , Nomura Yusuke , Xing Lei , Perkó Zoltán 
Published: March 2023

Abstract

Objective. In radiotherapy, the internal movement of organs between treatment sessions causes errors in the final radiation dose delivery. To assess the need for adaptation, motion models can be used to simulate dominant motion patterns and assess anatomical robustness before delivery. Traditionally, such models are based on principal component analysis (PCA) and are either patient-specific (requiring several scans per patient) or population-based, applying the same set of deformations to all patients. We present a hybrid approach which, based on population data, allows to predict patient-specific inter-fraction variations for an individual patient. Approach. We propose a deep learning probabilistic framework that generates deformation vector fields warping a patient's planning computed tomography (CT) into possible patient-specific anatomies. This daily anatomy model (DAM) uses few random variables capturing groups of correlated movements. Given a new planning CT, DAM estimates the joint distribution over the variables, with each sample from the distribution corresponding to a different deformation. We train our model using dataset of 312 CT pairs with prostate, bladder, and rectum delineations from 38 prostate cancer patients. For 2 additional patients (22 CTs), we compute the contour overlap between real and generated images, and compare the sampled and ‘ground truth’ distributions of volume and center of mass changes. Results. With a DICE score of 0.86 ± 0.05 and a distance between prostate contours of 1.09 ± 0.93 mm, DAM matches and improves upon previously published PCA-based models, using as few as 8 latent variables. The overlap between distributions further indicates that DAM’s sampled movements match the range and frequency of clinically observed daily changes on repeat CTs. Significance. Conditioned only on planning CT values and organ contours of a new patient without any pre-processing, DAM can accurately deformations seen during following treatment sessions, enabling anatomically robust treatment planning and robustness evaluation against inter-fraction anatomical changes.
An artificial intelligence-based model for cell killing prediction: development, validation and explainability analysis of the ANAKIN model
Authors: Cordoni Francesco G , Missiaggia Marta , Scifoni Emanuele , La Tessa Chiara 
Published: March 2023

Abstract
The present work develops ANAKIN: an Artificial iNtelligence bAsed model for (radiation-induced) cell KIlliNg prediction. ANAKIN is trained and tested over 513 cell survival experiments with different types of radiation contained in the publicly available PIDE database. We show how ANAKIN accurately predicts several relevant biological endpoints over a wide broad range on ion beams and for a high number of cell-lines. We compare the prediction of ANAKIN to the only two radiobiological models for Relative Biological Effectiveness prediction used in clinics, that is the Microdosimetric Kinetic Model and the Local Effect Model (LEM version III), showing how ANAKIN has higher accuracy over the all considered cell survival fractions. At last, via modern techniques of Explainable Artificial Intelligence (XAI), we show how ANAKIN predictions can be understood and explained, highlighting how ANAKIN is in fact able to reproduce relevant well-known biological patterns, such as the overkilling effect.
Inter-fraction deformable image registration using unsupervised deep learning for CBCT-guided abdominal radiotherapy
Authors: Xie Huiqiao , Lei Yang , Fu Yabo , Wang Tonghe , Roper Justin , Bradley Jeffrey D , Patel Pretesh , Liu Tian , Yang Xiaofeng 
Published: March 2023

Abstract

Objective. CBCTs in image-guided radiotherapy provide crucial anatomy information for patient setup and plan evaluation. Longitudinal CBCT image registration could quantify the inter-fractional anatomic changes, e.g. tumor shrinkage, and daily OAR variation throughout the course of treatment. The purpose of this study is to propose an unsupervised deep learning-based CBCT-CBCT deformable image registration which enables quantitative anatomic variation analysis. Approach. The proposed deformable registration workflow consists of training and inference stages that share the same feed-forward path through a spatial transformation-based network (STN). The STN consists of a global generative adversarial network (GlobalGAN) and a local GAN (LocalGAN) to predict the coarse- and fine-scale motions, respectively. The network was trained by minimizing the image similarity loss and the deformable vector field (DVF) regularization loss without the supervision of ground truth DVFs. During the inference stage, patches of local DVF were predicted by the trained LocalGAN and fused to form a whole-image DVF. The local whole-image DVF was subsequently combined with the GlobalGAN generated DVF to obtain the final DVF. The proposed method was evaluated using 100 fractional CBCTs from 20 abdominal cancer patients in the experiments and 105 fractional CBCTs from a cohort of 21 different abdominal cancer patients in a holdout test. Main Results. Qualitatively, the registration results show good alignment between the deformed CBCT images and the target CBCT image. Quantitatively, the average target registration error calculated on the fiducial markers and manually identified landmarks was 1.91 ± 1.18 mm. The average mean absolute error, normalized cross correlation between the deformed CBCT and target CBCT were 33.42 ± 7.48 HU, 0.94 ± 0.04, respectively. Significance. In summary, an unsupervised deep learning-based CBCT-CBCT registration method is proposed and its feasibility and performance in fractionated image-guided radiotherapy is investigated. This promising registration method could provide fast and accurate longitudinal CBCT alignment to facilitate inter-fractional anatomic changes analysis and prediction.
Design of a generic method for single dual-tracer PET imaging acquisition in clinical routine
Authors: Taheri Nasrin , Le Crom Benjamin , Bouillot Caroline , Chérel Michel , Costes Nicolas , Gouard Sébastien , Marionneau-Lambot Séverine , Merlin Thibault , Visvikis Dimitris , Stute Simon , Carlier Thomas 
Published: March 2023

Abstract
Using different tracers in positron emission tomography (PET) imaging can bring complementary information on tumor heterogeneities. Ideally, PET images of different tracers should be acquired simultaneously to avoid the bias induced by movement and physiological changes between sequential acquisitions. Previous studies have demonstrated the feasibility of recovering separated PET signals or parameters of two or more tracers injected (quasi-)simultaneously in a single acquisition. In this study, a generic framework in the context of dual-tracer PET acquisition is proposed where no strong kinetic assumptions nor specific tuning of parameters are required. The performances of the framework were assessed through simulations involving the combination of [18F]FCH and [18F]FDG injections, two protocols (90 and 60 min acquisition durations) and various activity ratios between the two injections. Preclinical experiments with the same radiotracers were also conducted. Results demonstrate the ability of the method both to extract separated arterial input functions (AIF) from noisy image-derived input function and to separate the dynamic signals and further estimate kinetic parameters. The compromise between bias and variance associated with the estimation of net influx rate K

i
shows that it is preferable to use the second injected radiotracer with twice the activity of the first for both 90 min [18F]FCH+[18F]FDG and 60 min [18F]FDG+[18F]FCH protocols. In these optimal settings, the weighted mean-squared-error of the estimated AIF was always less than 7%. The K

i
bias was similar to the one of single-tracer acquisitions; below 5%. Compared to single-tracer results, the variance of K

i
was twice more for 90 min dual-tracer scenario and four times more for the 60 min scenario. The generic design of the method makes it easy to use for other pairs of radiotracers and even for more than two tracers. The absence of strong kinetic assumptions and tuning parameters makes it suitable for a possible use in clinical routine.
Charge transfer and ionization cross-sections in collisions of singly charged lithium ions with helium and nitrogen atoms
Authors: Al-Ajaleen M , Taoutioui A , Tőkési K 
Published: March 2023

Abstract
We present a non-perturbative classical treatment of the charge transfer and ionization processes in collisions between singly charged lithium ions with helium and nitrogen atomic targets. Single capture and single ionization total cross sections are calculated using a three-body classical trajectory Monte Carlo (CTMC) method in which the interaction between the collision partners is described by a Garvey-type model potential. The cross sections are evaluated for collision energies between 20 keV and 100 MeV. In particular, we found excellent agreement between our results and the available experimental data for the case of the single capture of He(1s) by Li+ ions. In addition, our CTMC results are in a reasonable agreement with the experimental results for collision energies higher than 200 keV for single capture of N(2p) atoms by Li+. Furthermore, we present single ionization cross sections for both collision systems.
Excitation of toroidal Alfvén eigenmode by barely circulating energetic electrons in low density plasmas
Authors: Wang Tao , Zhu Xiang , Zeng Long , Briguglio Sergio , Vlad Gregorio , Zonca Fulvio , Qiu Zhiyong 
Published: March 2023

Abstract
Toroidal Alfvén eigenmodes (TAEs) associated with runaway electrons are observed in low density EAST Ohmic discharges (Zhu et al 2022 Phys. Plasmas
29 062504), which motivate the present work to explore the possible destabilization mechanism using simplified hybrid MHD-kinetic simulations. We show that the barely circulating energetic electrons can satisfy the resonance condition with the TAE, mainly due to vanishing transit frequency near the phase space circulating/trapped separatrix. In addition, the nonlinear saturation study suggests that the phase space resonance structure plays an important role in the eventual saturation amplitude, where a low toroidal mode number is favored in this scenario.
Three-dimensional analysis of RF-biased ion optics with misalignments of apertures
Authors: Li Yifei , Wang Weizong , Liu Wei , Dong Yicheng , Fu Chencong 
Published: March 2023

Abstract
Accelerator grid hole shift is a critical reason for erosion failure of optic systems in ion thrusters, which may also cause an unexpected roll torque about the ion beam axis. A three-dimensional (3D) model of ion optics is developed based on a particle-in-cell Monte Carlo collision method to investigate the plasma dynamics and performance of radio frequency (RF) grid systems with misalignments of apertures, which are compared with those in the direct current (DC) grid system. For the benchmark case, the 3D model gives a better agreement with the experiments in the ion energy distribution function (IEDF) compared with the two-dimensional model from a previous publication, with 36.4% and 47.9% relative error reduction of the peak position and full width at half maximum (FWHM), respectively, indicating the effectiveness of the developed 3D model. Simulations show that in the RF grid system the ion beamlet is deflected in the direction opposite to the shift of the accelerator grid hole, while electrons move first in the hole shift direction, and then deflect in the opposite direction. The average ion beamlet deflection angle calculated is consistent with the predictions from linear optical theory in both the RF and DC grid system. The amplitude of beamlet deflection angle fluctuation with time decreases with the increase of RF frequency. When the grid holes shift, the ion beamlet will deflect with the divergence angle almost unchanged in the DC grid system, while the beamlet divergence angle increases in the RF grid system. When RF frequency is low, the big vortex-like structure in the electron velocity phase diagram breaks into small vortices, showing a reduced oscillation intensity. The hole shift also causes high-frequency oscillation in the shift direction. In terms of performance, the RF grid system is more sensitive to grid hole shift than the DC grid system.
Power concentration determined by thermodynamic properties in complex gas mixtures: the case of plasma-based dry reforming of methane
Authors: Biondo Omar , Hughes Ashley , van de Steeg Alex , Maerivoet Stein , Loenders Björn , van Rooij Gerard , Bogaerts Annemie 
Published: March 2023

Abstract
We investigate discharge contraction in a microwave plasma at sub-atmospheric pressure, operating in CO2 and CO2/CH4 mixtures. The rise of the electron number density with plasma contraction intensifies the gas heating in the core of the plasma. This, in turn, initiates fast core-periphery transport and defines the rate of thermal chemistry over plasma chemistry. In this context, power concentration describes the overall mechanism including plasma contraction and chemical kinetics. In a complex chemistry such as dry reforming of methane, transport of reactive species is essential to define the performance of the reactor and achieve the desired outputs. Thus, we couple experimental observations and thermodynamic calculations for model validation and understanding of reactor performance. Adding CH4 alters the thermodynamic properties of the mixture, especially the reactive component of the heat conductivity. The increase in reactive heat conductivity increases the pressure at which plasma contraction occurs, because higher rates of gas heating are required to reach the same temperature. In addition, we suggest that the predominance of heat conduction over convection is a key condition to observe the effect of heat conductivity on gas temperature.