bluuebunny/crossref_metadata_2025_split huggingface dataset:
Momentum relaxation effects in 2D-Xene field effect device structures
Authors: Basak Anirban , Brahma Pratik , Muralidharan Bhaskaran 
Published: October 2021

Abstract
We analyze the electric field driven topological field effect transition on 2D-xene materials with the addition of momentum relaxation effects, in order to account for dephasing processes. The topological field effect transition between the quantum spin Hall phase and the quantum valley Hall phase is analyzed in detail using the Keldysh non-equilibrium Green’s function technique with the inclusion of momentum and phase relaxation, within the self-consistent Born approximation. Details of the transition with applied electric field are elucidated for the ON–OFF characteristics with emphasis on the transport properties along with the tomography of the current carrying edge states. We note that for moderate momentum relaxation, the current carrying quantum spin Hall edge states are still pristine and show moderate decay with propagation. To facilitate our analysis, we introduce two metrics in our calculations, the coherent transmission and the effective transmission. In elucidating the physics clearly, we show that the effective transmission, which is derived rigorously from the quantum mechanical current operator is indeed the right quantity to analyze topological stability against dephasing. Exploring further, we show that the insulating quantum valley Hall phase, as a result of dephasing carries band-tails which potentially activates parasitic OFF currents, thereby degrading the ON–OFF ratios. Our analysis sets the stage for realistic modeling of topological field effect devices for various applications, with the inclusion of scattering effects and analyzing their role in the optimization of the device performance.
Light assisted synthesis of poly-para-phenylene on Ag(001)
Authors: Langlais V , Schneider K , Tang H 
Published: October 2021

Abstract
A detailed study of poly-para-phenylene (PPP) obtained by light-assisted on-surface-synthesis (OSS) on Ag(100) was carried out by scanning tunneling microscopy and spectroscopy together with density functional theory calculations. The use of light in combination with heat allows to lower by 50 K annealing temperature the each stage of the Ullmann coupling. Debromination of the 4,4″ dibromo-p-terphenyl precursors was thus realized at 300 K, the formation of the first oligomers from the organometallic intermediate by silver bridging atom release at 423 K and PPP by complete elimination of the silver at 473 K. This approach to lower the reaction temperature permits to enhance the Ag(100) surface reactivity to become comparable to that of Cu(111). The underlying mechanism of light effect was proposed to occur via surface mediated excitation, with the creation of photoexcited electrons known as hot electrons correlated with surface plasmon excitation. This original pathway combining both light and heat provides an additional parameter to control OSS by separating the precursor activation stage from the diffusion.
Structural, electronic and magnetic properties of weakly correlated metal Sr2CrTiO6: a first principles study
Authors: Dhawan Rakshanda , Balasubramanian Padmanabhan , Nautiyal Tashi 
Published: October 2021

Abstract
Structural, electronic and magnetic behaviour of a less-explored material Sr2CrTiO6 has been investigated using ab
initio calculations with generalized gradient approximation (GGA) and GGA + U methods, where U is the Hubbard parameter. For each of the three possible Cr/Ti cationic arrangements in the unit cell, considered in this work, the non-magnetic band structure shows distinct traits with significant flat-band regions leading to large t
2g
density of states around the Fermi energy. The Cr4+ ion in Sr2CrTiO6, which is a d
2 system, shows a reverse splitting of the t
2g
orbitals. The calculated hopping matrix contains non-zero off-diagonal elements between the d

xz
and d

yz
orbitals, while the d

xy
orbitals remain largely unmixed. A minimal tight binding model successfully reproduces the six t
2g
bands around the Fermi energy. The Fermi surface shows a two-dimensional nesting feature for the layered arrangement of Cr and Ti atoms. Fixed spin moment studies suggest that the magnetism in this compound cannot be explained by Stoner’s criterion of an itinerant band ferromagnet. In the absence of Hubbard U term, the ground state is a half-metallic ferromagnet. Calculations for the anti-ferromagnetic spin arrangement show re-arrangement of orbital character resulting in (a) narrow d

xz
/d

yz
bands and sharp peaks in the density of states at the Fermi energy and (b) highly dispersive d

xy
bands with a broader density of states around the Fermi energy. The metallicity persists even with increasing U for both the spin arrangements, thus suggesting that Sr2CrTiO6 belongs to the class of weakly correlated metals, while the shifting of O 2p states towards the Fermi energy with U indicates a negative charge-transfer character in Sr2CrTiO6.
Slip band formation in low and high solute aluminum: a combined experimental and modeling study
Authors: Prakash Aditya , Tak Tawqeer Nasir , Pai Namit N , Murty S V S Narayana , Guruprasad P J , Doherty R D , Samajdar Indradev 
Published: October 2021

Abstract
Direct ex situ observations related slip band formation with deformed microstructures in commercial AA1050 and AA2219. The samples from both grades had similar grain sizes (∼250 μm) and nearly random crystallographic textures. However, AA2219 contained significantly more solute. Slip bands, on the internal long transverse (LT) plane in split channel die specimens, were characterized by primary spacings (λ) of 2–9 μm, heights (Z) of 160–360 nm and secondary shear strains (

γ

LT

S

). Higher deformation temperatures for both grades increased λ, decreased, Z and

r
e
d
u
c
e
d

γ

LT

S

. At all deformation temperatures, AA1050 had smaller λ and higher Z, while AA2219 showed higher

γ

LT

S

. In-grain misorientations, but not residual strains, were larger in grains with finer λ in AA1050, but less so in AA2219. Discrete dislocation dynamics (DDD) simulations reported realistic slip bands with slip localizations. The simulations, initiated with static obstacles and sources, led to dislocation interactions and junction formation. The probability of junction stabilization (p) determined the ratio of dynamic sources to obstacles. Slip band formation appeared to be an outcome of the release of piled up dislocations leading to dislocation avalanches. Slip localization increased weakly with finer active slip plane spacing (λ
*), giving higher dynamic obstacle strengths and densities, but strongly with smaller p. In particular, the DDD simulations captured experimental patterns of higher slip localizations and dislocation densities in low solute aluminum with finer λ
*.
Construction of 3D CrN@nitrogen-doped carbon nanosheet arrays by reactive magnetron sputtering for the free-standing electrode of supercapacitor
Authors: Xu Xun , Chang Songyang , Hong Zhuozheng , Zeng Ye , Zhang Hao , Li Ping , Zheng Shizheng , Wang Zhoucheng , Duo Shuwang 
Published: October 2021

Abstract
Owing to their favorable chemical stabilities and electronic conductivities, transition metal nitrides (TMNs) have been targeted as the potential electrode materials for the supercapacitors. Herein, 3D CrN@nitrogen-doped carbon nanosheet arrays (NCs) were successfully deposited on carbon paper (CP) by reactive magnetron sputtering method. The CrN@NCs@CP electrode exhibited satisfactory electrochemical properties: initially, the electrode showed a 132.1 mF cm−2 specific capacitance at 1.0 mA cm−2 current density; subsequently, the electrode demonstrated a 95.9% capacitance retention after 20 000 galvanostatic charge–discharge cycles at 5.0 mA cm−2 current density. The specific capacitance of the CrN@NCs@CP electrode was significantly higher than that of the CrN@CP electrode (4.1 mF cm−2 at 1.0 mA cm−2). Furthermore, the symmetric supercapacitor that incorporated two CrN@NCs@CP electrodes demonstrated 5.28 μWh cm−2 (2.7 Wh kg−1) energy density at 0.41 mW cm−2 power density. These findings exemplify the suitability of the 3D composite electrodes of TMNs for energy storage application.
Visualization of a hexagonal boron nitride monolayer on an ultra-thin gold film via reflected light microscopy
Authors: Hattori Yoshiaki , Taniguchi Takashi , Watanabe Kenji , Kitamura Masatoshi 
Published: October 2021

Abstract
Hexagonal boron nitride (h-BN) is an important insulating layered material for two-dimensional heterostructure devices. Among many applications, few-layer h-BN films have been employed as superior tunneling barrier films. However, it is difficult to construct a heterostructure with ultra-thin h-BN owing to the poor visibility of flakes on substrates, especially on a metallic surface substrate. Since reflectance from a metallic surface is generally high, a h-BN film on a metallic surface does not largely influence reflection spectra. In the present study, a thin Au layer with a thickness of ∼10 nm deposited on a Si substrate with a thermally grown SiO2 was used for visualizing h-BN flakes. The thin Au layer possesses conductivity and transparency. Thus, the Au/SiO2/Si structure serves as an electrode and contributes to the visualization of an ultra-thin film according to optical interference. As a demonstration, the wavelength-dependent contrast of exfoliated few-layer h-BN flakes on the substrate was investigated under a quasi-monochromatic light using an optical microscope. A monolayer h-BN film was recognized in the image taken by a standard digital camera using a narrow band-pass filter of 490 nm, providing maximum contrast. Since the contrast increases linearly with the number of layers, the appropriate number of layers is identified from the contrast. Furthermore, the insulating property of a h-BN flake is examined using a conductive atomic force microscope to confirm whether the thin Au layer serves as an electrode. The tunneling current through the h-BN flake is consistent with the number of layers estimated from the contrast.
Cytocompatibility of carboxylated multi-wall carbon nanotubes in stem cells from human exfoliated deciduous teeth
Authors: Oliveira Eduarda R , Fayer Leonara , Zanette Rafaella S S , Ladeira Luiz O , de Oliveira Luiz F C , Maranduba Carlos M C , Brandão Humberto M , Munk Michele 
Published: October 2021

Abstract
Carboxylated multi-wall carbon nanotube (MWCNT-COOH) presents unique properties due to nanoscale dimensions and permits a broad range of applications in different fields, such as bone tissue engineering and regenerative medicine. However, the cytocompatibility of MWCNT-COOH with human stem cells is poorly understood. Thus, studies elucidating how MWCNT-COOH affects human stem cell viability are essential to a safer application of nanotechnologies. Using stem cells from the human exfoliated deciduous teeth model, we have evaluated the effects of MWCNT-COOH on cell viability, oxidative cell stress, and DNA integrity. Results demonstrated that despite the decreased metabolism of mitochondria, MWCNT-COOH had no toxicity against stem cells. Cells maintained viability after MWCNT-COOH exposure. MWCNT-COOH did not alter the superoxide dismutase activity and did not cause genotoxic effects. The present findings are relevant to the potential application of MWCNT-COOH in the tissue engineering and regenerative medicine fields.
Absence of absolutely continuous diffraction spectrum for certain S-adic tilings
Authors: Nagai Yasushi 
Published: October 2021

Abstract
Quasiperiodic tilings are often considered as structure models of quasicrystals. In this context, it is important to study the nature of the diffraction measures for tilings. In this article, we investigate the diffraction measures for S-adic tilings in

R

d

, which are constructed from a family of geometric substitution rules. In particular, we firstly give a sufficient condition for the absolutely continuous component of the diffraction measure for an S-adic tiling to be zero. Next, we prove this sufficient condition for ‘almost all’ binary block-substitution cases and thus prove the absence of the absolutely continuous diffraction spectrum for most of S-adic tilings from a family of binary block substitutions.
Well-posedness and global dynamics for the critical Hardy–Sobolev parabolic equation
Authors: Chikami Noboru , Ikeda Masahiro , Taniguchi Koichi 
Published: October 2021

Abstract
We study the Cauchy problem for the semilinear heat equation with the singular potential, called the Hardy–Sobolev parabolic equation, in the energy space. The aim of this paper is to determine a necessary and sufficient condition on initial data below or at the ground state, under which the behavior of solutions is completely dichotomized. More precisely, the solution exists globally in time and its energy decays to zero in time, or it blows up in finite or infinite time. The result on the dichotomy for the corresponding Dirichlet problem is also shown as a by-product via comparison principle.
A deep-learning method for generating synthetic kV-CT and improving tumor segmentation for helical tomotherapy of nasopharyngeal carcinoma
Authors: Chen Xinyuan , Yang Bining , Li Jingwen , Zhu Ji , Ma Xiangyu , Chen Deqi , Hu Zhihui , Men Kuo , Dai Jianrong 
Published: October 2021

Abstract

Objective: Megavoltage computed tomography (MV-CT) is used for setup verification and adaptive radiotherapy in tomotherapy. However, its low contrast and high noise lead to poor image quality. This study aimed to develop a deep-learning-based method to generate synthetic kilovoltage CT (skV-CT) and then evaluate its ability to improve image quality and tumor segmentation. Approach: The planning kV-CT and MV-CT images of 270 patients with nasopharyngeal carcinoma (NPC) treated on an Accuray TomoHD system were used. An improved cycle-consistent adversarial network which used residual blocks as its generator was adopted to learn the mapping between MV-CT and kV-CT and then generate skV-CT from MV-CT. A Catphan 700 phantom and 30 patients with NPC were used to evaluate image quality. The quantitative indices included contrast-to-noise ratio (CNR), uniformity and signal-to-noise ratio (SNR) for the phantom and the structural similarity index measure (SSIM), mean absolute error (MAE), and peak signal-to-noise ratio (PSNR) for patients. Next, we trained three models for segmentation of the clinical target volume (CTV): MV-CT, skV-CT, and MV-CT combined with skV-CT. The segmentation accuracy was compared with indices of the dice similarity coefficient (DSC) and mean distance agreement (MDA). Main
results: Compared with MV-CT, skV-CT showed significant improvement in CNR (184.0%), image uniformity (34.7%), and SNR (199.0%) in the phantom study and improved SSIM (1.7%), MAE (24.7%), and PSNR (7.5%) in the patient study. For CTV segmentation with only MV-CT, only skV-CT, and MV-CT combined with skV-CT, the DSCs were 0.75 ± 0.04, 0.78 ± 0.04, and 0.79 ± 0.03, respectively, and the MDAs (in mm) were 3.69 ± 0.81, 3.14 ± 0.80, and 2.90 ± 0.62, respectively. Significance: The proposed method improved the image quality of MV-CT and thus tumor segmentation in helical tomotherapy. The method potentially can benefit adaptive radiotherapy.
Out-of-field dose and its constituent components for a 1.5 T MR-Linac
Authors: Yang Bin , Tang Ka Keung , Huang Chen-Yu , Geng Hui , Lam Wai Wang , Wong Yeung Sum , Tse Mei Yan , Lau Ka Ki , Cheung Kin Yin , Yu Siu Ki 
Published: October 2021

Abstract
This study aims to quantify the relative contributions of phantom scatter, collimator scatter and head leakage to the out-of-field doses (OFDs) of both static fields and clinical intensity-modulated radiation therapy (IMRT) treatments in a 1.5 T MR-Linac. The OFDs of static fields were measured at increasing distances from the field edge in an MR-conditional water phantom. Inline scans at depths of dmax (14 mm), 50 and 100 mm were performed for static fields of 5 × 5, 10 × 10 and 15 × 15 cm2 under three different conditions: full scatter, with phantom scatter prevented, and head leakage only. Crossline scans at isocenter and offset positions were performed in full scatter condition. EBT3 radiochromic films were placed at 100 mm depth of solid water phantom to measure the OFD of clinical IMRT plans. All water tank data were normalized to Dmax of a 10 × 10 cm2 field and the film results were presented as a fraction of the target mean dose. The OFD in the inline direction varied from 3.5% (15 × 15 cm2, 100 mm depth, 50 mm distance) to 0.014% (5 × 5 cm2, dmax, 400 mm distance). For all static fields, the collimator scatter was higher than the phantom scatter and head leakage at a distance of 100–400 mm. Head leakage remained the smallest among the three components, except at long distances (>375 mm) with small field size. Compared to the inline scans, the crossline scans at the isocenter showed higher doses at distances longer than 80 mm. All crossline profiles at longitudinal offset positions showed a cone shape with laterally shifted maxima. The OFD of IMRT deliveries varied with different target size. For prostate stereotactic body radiation therapy (SBRT) treatment, the OFD decreased from 2% to 0.03% at a distance of 50–500 mm. The OFDs have been measured for a 1.5 T MR-Linac. The presented dosimetric data are valuable for radiation safety assessments on patients treated with the MR-Linac, such as evaluating carcinogenic risk and radiation exposure to cardiac implantable electronic devices.
Temporal studies of titanium ionised density fraction in reactive HiPIMS with nitrogen admixture
Authors: Bernátová K , Klein P , Hnilica J , Vašina P 
Published: October 2021

Abstract
Temporal evolutions of the ground state number densities of titanium atoms and ions and the ionised density fraction during pulse on-time are experimentally investigated for the high-power impulse magnetron sputtering process in an Ar and Ar/N2 atmosphere. For the study, two distinct pulses with the same pulse length at a constant average power but different pulse off-times were selected. In both conditions, four representative points within the hysteresis curve were chosen, and the time evolutions of sputtered species densities were investigated in both the target and the substrate regions. At the pulse beginning, a high density of residual particles sputtered during the previous pulse is present in both studied regions. In the target region, in conditions of longer pulse off-time and thus higher peak discharge current, 95% of sputtered particles are ionised in metallic, transition and compound regimes. With shorter pulse off-time conditions, and thus a lower peak discharge current, the ionised density fraction is the lowest in the metallic regime; in the transition and compound regimes, it exceeds 80%. In the substrate region, the temporal evolution of sputtered species densities differs from that obtained in the target region. After the pulse ignition, titanium atoms and ions remaining near the substrate from the previous pulse are pushed away. In the metallic regime, the sputtered atoms refill the substrate region already during the pulse on-time in both the low- and high-current conditions. In the high-current conditions, the titanium ions arrive at the substrate together with the sputtered atoms; however, in the low-current conditions, the titanium ion density decreases during the pulse on-time, and the titanium ions arrive later during the pulse off-time. In the transition and compound regimes, both densities steadily decrease during the pulse on-time and the titanium atoms and ions arrive at the substrate during the pulse off-time.
Benefits of using arrays of vertical nanowire FETs in integrated circuits to mitigate variability
Authors: del Moral A , Amat E , Bausells J , Perez-Murano F 
Published: October 2021

Abstract
We investigate the benefits of the use of arrays of vertical nanowire (vNW) field-effect transistors (FETs) to implement integrated circuits. By means of technology computer aided design and circuit simulations, the optimal dimensions of the vNWFETs are determined. Device and circuit variability levels have been investigated. The benefits of using array configurations are the decrease of the response time and a significant mitigation of the variability level as the number of the elements in the array increases.
Study of traps in low-temperature polysilicon thin film transistors using a current transient method
Authors: Zhu Hui , Xie Na , Wang Si , Huang Zeng , Fang Zhixuan , Liu Zheng , Li Dong , Feng Shiwei , Guo Chunsheng , Zhang Yamin , Zhou Lixing , Liu Bo 
Published: October 2021

Abstract
The trap characteristics of low-temperature polysilicon thin film transistors (TFTs) are studied using a current transient method that is based on the trapping and detrapping of charge carriers from the trap sites in the device. Analysis of the measured current transient curve allowed three types of detrapping behavior to be identified, each of which displayed a different time constant, activation energy, and spatial position. This current transient method can be integrated into the negative bias temperature instability stress test used for the reliability study. The peak amplitudes of the traps increase because of the stress applied in the test, thus demonstrating that the degradation mechanism of the TFTs is closely related to changes in the traps in these devices.
A reconstructed three-dimensional HTS bulk electromagnetic model considering J
c spatial inhomogeneity and its implementation in a bulks’ combination system
Authors: Cheng Yanxing , Zheng Jun , Huang Huan , Deng Zigang 
Published: October 2021

Abstract
High-temperature superconducting (HTS) bulks in HTS Maglev systems are always arrayed in a combination to make full use of the applied magnetic field of the permanent magnet guideway (PMG). An excellent combination scheme improves the overall levitation and guidance performance significantly. In this paper, a three-dimensional (3D) electromagnetic model of the real HTS-PMG maglev system with an HTS bulk array was established. This model comprehensively expresses the influence of various factors on the
E
–
J
relationship and the 3D spatial distribution of J
c, including internal factors such as the inhomogeneity and anisotropy of electromagnetic characteristics, as well as external factors such as applied magnetic field and working temperature. A ternary function was proposed to describe the uneven distribution of J
c caused by the bulk’s growth process, which is an interesting phenomenological modeling attempt. In the simulations of the bulks’ combinations, perfect magnetic conductor boundary conditions were applied on the contact surface to simulate two bulks touching each other. Besides, the research target includes reproducing the shapes, the orientations, and the combination scheme of HTS bulks in the real PMG magnetic field. The calculation results of levitation force of the cylindrical bulk under different spatial orientations above the PMG were compared with the experimental results, through which the accuracy of the model was verified. On this basis, the influence of the magnetic field generated by the superconducting current on the nearby bulk was further explored. It was found that this magnetic field has a small contribution to the total levitation force and a relatively obvious influence on the guidance force. When the lateral displacement is large, such as 5 mm, the magnetic field generated by the superconducting current slightly increases the total guidance force stiffness. According to more simulated conditions, some optimization strategies on bulk combinations were proposed. This work provides not only a 3D descriptive model for fitting the real multi-bulk-combination maglev scenarios but also some optimization strategies for the HTS maglev transportation applications.