bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time-resolved measurement of the free electron and neutral gas line density in a hydrogen theta-pinch plasma target by two-color interferometry
Authors: Christ P , Bonilla Guzmán Y , Cistakov C , Iberler M , Laghchioua L , Jacoby J 
Published: January 2022

Abstract
A hydrogen theta-pinch plasma is diagnosed by two-color interferometry to determine the line density of the free electrons and the hydrogen gas. From the ratio of these line densities, the effective ionization can be calculated. The free electron line density and the effective ionization degree are the most essential quantities for the evaluation of the plasma regarding its applicability as a target in context of plasma ion beam interaction to increase the charge state of the ion beam (plasma stripper). The two-color interferometric diagnostic shows that both line densities exhibit a periodic behavior predefined by the periodic current and at the time the free electron line density reaches a local maximum, the hydrogen line density falls to a local minimum. This occurs, because the plasma axially expands from the coil center by evading the radial compression force of the magnetic field, creating an ionizing wave in the residual gas. The theta-pinch was set up in two versions, with one of them using a cylindrical coil and the other using a spherical coil. For the cylindrical version, the best working point regarding the free electron line density and the effective ionization degree is

1.45
±
0.04

×

10

18

cm−2 and

0.826
±
0.022

at 20 Pa and 16 kV. In contrast, for the spherical version, lower values of

1.23
±
0.03

×

10

18

cm

−
2

and

0.699
±
0.019

at 20 Pa and 18 kV were found. Additionally, a new set-up is proposed for optimizing the plasma target regarding the free electron line density and the effective ionization degree, as well as how to maintain them on a sufficient level for several

10

μ

s.
Can oxygen vacancies in ceria surfaces be measured by O1s photoemission spectroscopy?
Authors: Bosio Noemi , Schaefer Andreas , Grönbeck Henrik 
Published: January 2022

Abstract
X-ray photoemission spectroscopy is a standard technique for materials characterization and the O 1s binding energy is commonly measured for oxides. Here we use density functional theory calculations to investigate how the O 1s binding energy in CeO2(111) is influenced by the presence of oxygen vacancies. The case with point vacancies in CeO2(111) is compared to complete reduction to Ce2O3. Reduction of CeO2 by oxygen vacancies is found to have a minor effect on the O 1s binding energy. The O 1s binding energy is instead clearly changed when the character of the chemical bond for the considered oxygen atom is modified by, for example, the formation of OH-groups or carbonates.
Artificial neural network potential for Au20 clusters based on the first-principles
Authors: Cao Lingzhi , Guo Yibo , Han Wenhua , Xu Wenwu , Sai Linwei , Fu Jie 
Published: January 2022

Abstract
The search of ground-state structures (GSSs) of gold (Au) clusters is a formidable challenge due to the complexity of potential energy surface (PES). In this work, we have built a high-dimensional artificial neural network (ANN) potential to describe the PES of Au20 clusters. The ANN potential is trained through learning the GSS search process of Au20 by the combination of density functional theory (DFT) method and genetic algorithm. The root mean square errors of energy and force are 7.72 meV atom−1 and 217.02 meV Å−1, respectively. As a result, it can find the lowest-energy structure (LES) of Au20 clusters that is consistent with previous results. Furthermore, the scalability test shows that it can predict the energy of smaller size Au16–19 clusters with errors less than 22.85 meV atom−1, and for larger size Au21–25 clusters, the errors are below 36.94 meV atom−1. Extra attention should be paid to its accuracy for Au21–25 clusters. Applying the ANN to search the GSSs of Au16–25, we discover two new structures of Au16 and Au21 that are not reported before and several candidate LESs of Au16–18. In summary, this work proves that an ANN potential trained for specific size clusters could reproduce the GSS search process by DFT and be applied in the GSS search of smaller size clusters nearby. Therefore, we claim that building ANN potential based on DFT data is one of the most promising ways to effectively accelerate the GSS pre-screening of clusters.
Superior hydrophobic silica-coated quantum dot for stable optical performance in humid environments
Authors: Zhou Shuling , Xie Bin , Yang Xuan , Zhang Xinfeng , Luo Xiaobing 
Published: January 2022

Abstract
Quantum dot (QD) features many exceptional optical performances but is also vulnerable to moisture which results in structural damage and luminescent decrease. This work provided and fabricated a novel superior hydrophobic methylated core/shell silica-coated QD (MSQ) for high water stability. QD was coated with a silica shell and then surface-methylated by trimethyl silane. Mercaptopropyl trimethoxy silane, tetraethyl orthosilicate, and ethoxy trimethyl silane were utilized as the ligand exchanger, the raw material of silica, and the surface modification, respectively. Characterization results illustrated the core/shell structure of MSQ. In addition, its water contact angle was up to 159.6°. QD-, silica-coated QD(SQ)-, and MSQ-silicone were made and displayed similar absorption, emission, and excitation spectra but different water stabilities. The photoluminescence intensity and photoluminescence quantum yield of MSQ-silicone hardly changed during 15 d of water immersion, in contrast to the dramatical decrease of other two kinds of composite silicone. Specifically, the photoluminescence quantum yield decreases of MSQ-, SQ-, and QD-silicone were 1%, 40%, and 43%, respectively. Therefore, MSQ had a much better water stability. The superior hydrophobic methylated silica-coated QD has a great potential to realize the long-term working stability in a humid environment and the wider application in diverse fields.
Formation of carnation-like ZIF-9 nanostructure to achieve superior electrocatalytic oxygen evolution
Authors: Li Tianyang , Xu Zhikun , Lin Shuangyan 
Published: January 2022

Abstract
Rational design and controllable synthesis of metal-organic frameworks nanosheets is critical for electrochemical catalysis. Herein, a carnation-like ZIF-9 nanostructure made of nanosheets is grown on nickel foam (ZIF-9/NF) by a simple one-step solvothermal method, the morphology evolution and the electrocatalytic oxygen evolution properties have been investigated by controlling the solvothermal time. The binder-free ZIF-9-d/NF (60 h, solvothermal time is 60 h) electrode delivers efficient electrocatalytic oxygen evolution reaction activity with low overpotentials of 312 and 337 mV at 50 and 100 mA cm−2, respectively. Furthermore, ZIF-9-d/NF (60 h) exhibits excellent stability without obvious attenuation for at least 30 h at 200 mA cm−2. The excellent performances can be attributed to the combination of the highly exposed active sites in the ZIF-9-d nanosheets, as well as the effective electron conduction and mass transfer. This work provides much possibilities for ZIF-9 nanosheets as binder-free electrode for electrocatalyst.
Improved photocatalytic activity and stability of black phosphorus/multi-walled carbon nanotube hybrid for RhB degradation
Authors: Yang Heli , Liang Yizun , Wang Chi , Song Xin , Ge Yanqing , Lang Ran , Li Kai , Mei Yi 
Published: January 2022

Abstract
Black phosphorus (BP) is a two-dimensional (2D) semiconductor that has recently attracted much interest due to its unique characteristics. However, BP is susceptible to oxidization under ambient conditions. In this work, a facile one-step route is presented, in which stable P–C bonds were formed by ball milling bulk BP and multi-walled carbon nanotubes (MWCNTs) mixture without any additives. The BP-MWCNTs hybrid and the milled BP (m-BP) were both dispersed in water under ambient conditions, and their optical absorbances were monitored. The resulting data showed that the absorbance value of the BP-MWCNTs hybrid decreased by 10.87% after 5 d, whereas the m-BP decreased by 59.21%. Surprisingly, the BP-MWCNTs hybrid also exhibited ultrahigh photocatalytic activity in the visible light range. Within 60 min of irradiation, the removal efficiency of rhodamine B (RhB) by the BP-MWCNTs hybrid reached 88.42%, which is four times higher than that of the bare m-BP. This improvement can be attributed to the formation of the P–C bond and the enhanced surface adsorption capacity resulting from the introduction of the MWCNTs, indicating that the utilization of the charges on the surface of the photocatalyst is further improved. In short, this study not only provides an easy method to synthesize the stable BP-based material for practical applications but also represents a new approach to enhance the photocatalytic activity of BP.
Fusion Siamese network with drift correction for target tracking in ultrasound sequences
Authors: Wu Chan , Fu Tianyu , Wang Yifan , Lin Yucong , Wang Yan , Ai Danni , Fan Jingfan , Song Hong , Yang Jian 
Published: January 2022

Abstract
Motion tracking techniques can revise the bias arising from respiration-caused motion in radiation therapy. Tracking key structures accurately and at a real-time speed is necessary for effective motion tracking. In this work, we propose a fusion Siamese network with drift correction for target tracking in ultrasound sequences. Specifically, the network fuses four response maps generated by the cross-correlation between convolution layers at different resolutions to reduce up-sampling error. A correction strategy combining local structural similarity and target trajectory is proposed to revise the target drift predicted by the network. Moreover, a coarse-to-fine strategy is proposed to train the network with a limited number of annotated images, in which an augmented dataset is generated by corner points to learn network features with high generalizability. The proposed method is evaluated on the basis of the public dataset of the MICCAI 2015 Challenge on Liver UltraSound Tracking (CLUST) and our ultrasound image dataset, which is provided by the Chinese People’s Liberation Army General Hospital (CPLAGH). A tracking error of 0.80 ± 1.16 mm is observed for 85 targets across 39 ultrasound sequences in the CLUST dataset. A tracking error of 0.61 ± 0.36 mm is observed for 20 targets across 10 ultrasound sequences in the CPLAGH dataset. The effectiveness of the proposed fusion and correction strategies is verified via two ablation experiments. Overall, the experimental results demonstrate the effectiveness of the proposed fusion Siamese network with drift correction and reveal its potential in clinical practice.
Spatiotemporal optimisation of prostate intensity modulated proton therapy (IMPT) treatments
Authors: Manganaro L , Attili A , Bortfeld T , Paganetti H 
Published: January 2022

Abstract

Objective. In intensity modulated particle therapy (IMPT), the adoption of spatially and temporally heterogeneous dose distributions allows to decouple the fractionation scheme from the patient anatomy, so that an hypofractionated schedule can be selectively created inside the tumour, while simultaneously exploiting the fractionation effect in the healthy tissues. In this paper, the authors show the reproducibility of the method on a set of prostate patients, quantifying the dependencies of the achievable benefit with respect to conventional and hypofractionated schemes and the sensitivity of the method to setup errors and range uncertainty. Approach. On a cohort of 9 patients, non-uniform IMPT plans were optimised and compared to conventional and hypofractionated schedules. For each patient, the comparison of the three strategies has been based on the output of the cost function used to optimise the treatments. The analysis has been repeated considering different α/β ratios for the tumour, namely 1.5, 3 and 4.5 Gy. For a single patient, setup errors and beam range uncertainty have been analysed: the plans, for each optimisation strategy, have been iteratively forward planned 500 times with randomly varying the patient position in each fraction, and 200 times for systematic range shift. Main results. An average 10% benefit has been shown for the lowest α/β ratio considered for the tumour, where the non-uniform schedule generally converges to hypofractionation; the benefit decreases to 5%–7% for higher α/β ratios, for which the non-uniform schedule always showed better outcomes with respect to the other fractionation schedules. An increased sensitivity to uncertainty, especially for setup errors, has been shown, which can be associated to the spatial non-uniformity of the dose distributions peculiar of the spatiotemporal plans. Significance. This work represents the first investigation of spatiotemporal fractionation for prostate cancer and the beginning of further investigations before clinical implementation can be considered.
Investigation of the effect of structural defects from hydride precipitation on superconducting properties of high purity SRF cavity Nb using magneto-optical and electron imaging methods
Authors: Wang Mingmin , Polyanskii Anatolii , Balachandran Shreyas , Chetri Santosh , Crimp Martin A , Lee Peter J , Bieler Thomas R 
Published: January 2022

Abstract
Nb is an elemental superconductor with a critical temperature of 9.3 K and is widely used to fabricate superconducting radiofrequency (SRF) cavities for particle accelerators. However, microstructural defects in Nb, such as grain boundaries (GBs) and dislocations, can act as pinning centers for magnetic flux that can degrade SRF cavity performance. Hydrogen contamination is also detrimental to SRF cavity performance due to the formation of normal conducting hydrides during cool down. In this study, disc shaped Nb bi-crystals extracted from high-purity large-grain Nb slices were investigated to study the effects of GBs, hydrogen, and dislocations on superconducting properties. Grain orientation and GB misorientation were measured using Laue x-ray diffraction and electron backscattered diffraction (EBSD) analyses. Cryogenic magneto-optical imaging was used to directly observe magnetic flux penetration below

T
c

= 9.3 K. Damage caused by low temperature precipitation of hydrides and their dissolution upon reheating after cryogenic cycles was examined using electron channeling contrast imaging, and EBSD. The relationships between hydride formation, dislocation content, GBs, cryo-cooling, heat treatment (HT), and flux penetration indicate that both GB character and hydrogen content affect magnetic flux penetration. Such flux penetration could be facilitated by dislocation structures and low angle GBs resulting from hydride precipitation and HT.
Off-resonant dynamics of the Rabi model under a deep-strong slow driving
Authors: Wang Hanyu , Lü Zhiguo , Zheng Hang 
Published: January 2022

Abstract
We investigate the dynamics of a two-level system driven by a deep-strong slow sinusoidal field using a novel counterrotating-hybridized rotating-wave (CHRW) method. By two successive unitary transformations, we obtain a transformed Hamiltonian which possesses a simple rotating-wave interaction with a renormalized driving strength and a modified tunneling strength. The modified CHRW method allows us to directly calculate the analytical results of the dynamics and Bloch-Siegert shift. We show that the results given by the modified CHRW method are in good agreement with the numerical solutions of the Rabi model with a moderate strong driving strength in the off-resonance case. It turns out that the modified CHRW method is beyond the traditional rotating-wave approximation in some interesting parameter regions. As the modified CHRW method is mathematically simple and physically clear, it may be applied to driven dissipative systems which are difficult to solve numerically.
Theta low-gamma phase amplitude coupling in the human orbitofrontal cortex increases during a conflict-processing task
Authors: Chen Kuang-Hsuan , Tang Austin M , Gilbert Zachary D , Martin Del Campo-Vera Roberto , Sebastian Rinu , Gogia Angad S , Sundaram Shivani , Tabarsi Emiliano , Lee Yelim , Lee Richard , Nune George , Liu Charles Y , Kellis Spencer , Lee Brian 
Published: January 2022

Abstract

Objective. The human orbitofrontal cortex (OFC) is involved in automatic response inhibition and conflict processing, but the mechanism of frequency-specific power changes that control these functions is unknown. Theta and gamma activity have been independently observed in the OFC during conflict processing, while theta–gamma interactions in other brain areas have been noted primarily in studies of memory. Within the OFC, it is possible that theta–gamma phase amplitude coupling (PAC) drives conflict processing. This study aims to characterize the coupled relationship between theta and gamma frequency bands in the OFC during conflict processing using a modified Stroop task. Approach. Eight epilepsy patients implanted with OFC stereotactic electroencephalography electrodes participated in a color-word modified Stroop task. PAC between theta phase and gamma amplitude was assessed to determine the timing and magnitude of neural oscillatory changes. Group analysis was conducted using a non-parametric cluster-permutation t-test on coherence values. Main results. Theta-low gamma (LG) PAC significantly increased in five out of eight patients during successful trials of the incongruent condition compared with the congruent condition. Significant increases in theta-LG PAC were most prominent during cue processing 200–800 ms after cue presentation. On group analysis, trial-averaged mean theta-LG PAC was statistically significantly greater in the incongruent condition compared to the congruent condition (p < 0.001, Cohen’s d = 0.51). Significance. For the first time, we report that OFC theta phase and LG amplitude coupling increases during conflict resolution. Given the delayed onset after cue presentation, OFC theta-LG PAC may contribute to conflict processing after conflict detection and before motor response. This explanation follows the hypothesis that global theta waves modulate local gamma signals. Understanding this relationship within the OFC will help further elucidate the neural mechanisms of human conflict resolution.
Epidemic oscillations induced by social network control
Authors: Caccioli Fabio , De Martino Daniele 
Published: January 2022

Abstract
Epidemic spreading can be suppressed by the introduction of containment measures such as social distancing and lockdowns. Yet, when such measures are relaxed, new epidemic waves and infection cycles may occur. Here we explore this issue in compartmentalized epidemic models on graphs in presence of a feedback between the infection state of the population and the structure of its social network for the case of discontinuous control. We show that in random graphs the effect of containment measures is simply captured by a renormalization of the effective infection rate that accounts for the change in the branching ratio of the network. In our simple setting, a piece-wise mean-field approximation can be used to derive analytical formulae for the number of epidemic waves and their length. A variant of the model with imperfect information is used to model data of the recent COVID-19 epidemics in the Basque Country and Lombardy, where we estimate the extent of social network disruption during lockdowns and characterize the dynamical trajectories in the phase space.
Performance of scintillating tiles with direct silicon-photomultiplier (SiPM) readout for application to large area detectors
Authors: Balla A. , Buonomo B. , Cafaro V. , Calcaterra A. , Cardelli F. , Ceccucci A. , Ciambrone P. , Cicero V. , Di Giovenale D. , Di Giulio C. , Felici G. , Foggetta L.G. , Giordano V. , Lanfranchi G. , Lax I. , Montanari A. , Papalino G. , Paoloni A. , Rovelli T. , Saputi A. , Torromeo G. , Tosi N. 
Published: January 2022

Abstract
The light yield, the time resolution and the efficiency of
different types of scintillating tiles with direct Silicon
Photomultiplier readout and instrumented with a customised front-end
electronics have been measured at the Beam Test Facility of
Laboratori Nazionali di Frascati and several test stands. The
results obtained on minimum ionising particles with different
detector configurations are presented. A time resolution of the
order of 300 ps, a light yield of more than 230 photo-electrons, and
an efficiency better than 99.8% are obtained with
∼ 225 cm2 large area tiles. This technology is suitable
for a wide range of applications in high-energy physics, in
particular for large area muon and timing detectors.
A major shift in U.S. land development avoids significant losses in forest and agricultural land
Authors: Bigelow Daniel P , Lewis David J , Mihiar Christopher 
Published: January 2022

Abstract
Land development, which typically results from the conversion of lands previously in agricultural and forest uses, is one of the most fundamental ways in which humans impact the natural environment. We study the remarkable decline in land development rates across the conterminous United States over the period 2000–2015, which occurred after development rates had grown rapidly over the last two decades of the 20th century. Despite relatively constant population growth since 1980, we find that the current annual rate of land development has declined consistently across several stratifications of the U.S. land base and amounts to less than 25% of the peak rate observed in the mid-late 1990s, implying that the developed land base of the U.S. has become increasingly dense in recent years. We show that the widespread shift in land development rates resulted in 7 million acres of avoided land development, roughly half of which would have come from conversions of forested lands. Panel data econometric estimation indicates that growth in development over the last two decades of the 20th century was driven by falling gas prices (an important component of commuting costs) and, to a lesser extent, rising incomes. Since 2000, however, income growth has been stagnant while gas prices have risen sharply, and we find that the latter has played a larger role in shaping the recent shift towards denser development. Results illustrate an often overlooked effect of how rising gas prices can indirectly avoid losses in forest and agricultural land by reducing developed land-use change.